TY - CHAP TI - Impingement Cooling for Combustor Liner Backside Cooling AU - Ekkad, S.V. T2 - Impingement jet cooling in gas turbines A2 - Amano, Ryo A2 - Sunden, Bengt PY - 2014/// PB - WIT Press ER - TY - CONF TI - Characterization of the NASA Langley Arc Heated Scramjet Test Facility using NO PLIF AB - The nitric oxide planar laser-induced fluorescence (NO PLIF) imaging was used to characterize the air flow of the NASA Langley Arc Heated Scramjet Test Facility (AHSTF) configured with a Mach 6 nozzle. The arc raises the enthalpy of the test gas in AHSTF, producing nitric oxide. Nitric oxide persists as the temperature drops through the nozzle into the test section. NO PLIF was used to qualitatively visualize the flowfield at different experimental conditions, measure the temperature of the gas flow exiting the facility nozzle, and visualize the wave structure downstream of the nozzle at different operating conditions. Uniformity and repeatability of the nozzle flow were assessed. Expansion and compression waves on the free-jet shear layer as the nozzle flow expands into the test section were visualized. The main purpose of these experiments was to assess the uniformity of the NO in the freestream gas for planned experiments, in which NO PLIF will be used for qualitative fuel-mole-fraction sensitive imaging. The shot-to-shot fluctuations in the PLIF signal, caused by variations in the overall laser intensity as well as NO concentration and temperature variations in the flow was 20-25% of the mean signal, as determined by taking the standard deviation of a set of images obtained at constant conditions and dividing by the mean. The fluctuations within individual images, caused by laser sheet spatial variations as well as NO concentration and temperature variations in the flow, were about 28% of the mean in images, determined by taking standard deviation within individual images, dividing by the mean in the same image and averaged over the set of images. Applying an averaged laser sheet intensity correction reduced the within-image intensity fluctuations to about 10% suggesting that the NO concentration is uniform to within 10%. There was no significant difference in flow uniformity between the low and high enthalpy settings. While not strictly quantitative, the temperature maps show qualitative agreement with the computations of the flow. C2 - 2014/// C3 - AIAA AVIATION 2014 - 30th AIAA Aerodynamic Measurement Technology and Ground Testing Conference DA - 2014/// DO - 10.2514/6.2014-2652 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85078067828&partnerID=MN8TOARS ER - TY - ER - TY - JOUR TI - Sand transport in a two pass internal cooling duct with rib turbulators AU - Singh, Sukhjinder AU - Tafti, Danesh AU - Reagle, Colin AU - Delimont, Jacob AU - Ng, Wing AU - Ekkad, Srinath T2 - International Journal of Heat and Fluid Flow AB - Jet engines often operate under dirty conditions where large amounts of particulate matter can be ingested, especially, sand, ash and dirt. Particulate matter in different engine components can lead to degradation in performance. The focus of this study is to investigate the sand transport and deposition in the internal cooling passages of turbine blades. A two pass stationary square duct with rib turbulators subjected to sand ingestion is studied using Large Eddy Simulations (LES). Each pass has ribs on two opposite walls and aligned normal to the main flow direction. The rib pitch to rib height (P/e) is 9.28, the rib height to channel hydraulic diameter (e/Dh) is 0.0625 and calculations have been carried out for a bulk Reynolds number of 25,000. Particle sizes in the range 0.5–25 μm are considered, with the same size distribution as found in Arizona Road Dust (medium). Large Eddy Simulation (LES) with a wall-model is used to model the flow and sand particles are modeled using a discrete Lagrangian framework. Results quantify the distribution of particle impingement density on all surfaces. Highest particle impingement density is found in the first quarter section of the second pass after the 180° turn, where the recorded impingement is more than twice that of any other region. It is also found that the average particle impingement per pitch is 28% higher in the second pass than the first pass. Results show lower particle tendency to impact the region immediately behind the rib in the first pass compared to the second pass where particle impingement is more uniform in the region between two ribs. The rib face facing the flow is by far is the most susceptible to impingement and hence deposition and erosion. The results of this simulation are compared to experiments conducted on an identical two pass geometry with Arizona Road Dust particles. The numerical predictions showed good qualitative agreement with experimental measurements. These results identify the damage prone areas in the internal cooling passages of a turbine blade under the influence of sand ingestion. This information can help modify the geometry of the blade or location of film cooling holes to avoid hole blockage and degradation of heat transfer at the walls. DA - 2014/4// PY - 2014/4// DO - 10.1016/j.ijheatfluidflow.2014.01.006 VL - 46 SP - 158-167 J2 - International Journal of Heat and Fluid Flow LA - en OP - SN - 0142-727X UR - http://dx.doi.org/10.1016/j.ijheatfluidflow.2014.01.006 DB - Crossref ER - TY - JOUR TI - Study of microparticle rebound characteristics under high temperature conditions AU - Reagle, C.J. AU - Delimont, J.M. AU - Ng, W.F. AU - Ekkad, S.V. T2 - Journal of Engineering for Gas Turbines and Power AB - Large amounts of tiny microparticles are ingested into gas turbines over their operating life, resulting in unexpected wear and tear. Knowledge of such microparticle behavior at gas turbine operating temperatures is limited in published literature. In this study, Arizona road dust (ARD) is injected into a hot flow field to measure the effects of high temperature and velocity on particle rebound from a polished 304 stainless steel (SS) coupon. The results are compared with baseline (27 m/s) measurements at ambient (300 K) temperature made in the Virginia Tech Aerothermal Rig, as well as previously published literature. Mean coefficient of restitution (COR) was shown to decrease with the increased temperature/velocity conditions in the VT Aerothermal Rig. The effects of increasing temperature and velocity led to a 12% average reduction in COR at 533 K (47 m/s), 15% average reduction in COR at 866 K (77 m/s), and 16% average reduction in COR at 1073 K (102 m/s) compared with ambient results. The decrease in COR appeared to be almost entirely a result of increased velocity that resulted from heating the flow. Trends show that temperature plays a minor role in energy transfer between particle and impact surface below a critical temperature. DA - 2014/// PY - 2014/// DO - 10.1115/1.4025346 VL - 136 IS - 1 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84888144064&partnerID=MN8TOARS ER - TY - CONF TI - Netl research efforts on development and integration of advanced material systems and airfoil cooling configurations for future land-based gas turbine engines AU - Alvin, M.A. AU - Klinger, J. AU - McMordie, B. AU - Chyu, M. AU - Siw, S. AU - Miller, N. AU - Reddy, B.V.K. AU - Gleeson, B. AU - Anderson, I. AU - Heidloff, A. AU - Ekkad, S. AU - Ramesh, S. AU - Kang, B. AB - As future land-based gas turbine engines are being designed to operate with inlet temperatures exceeding 1300°C (2370°F), efforts at NETL have been focused on developing advanced materials systems that are integrated with novel airfoil cooling architectures. Recent achievements in the areas of low cost diffusion bond coat systems applied to single- and poly-crystalline nickel-based superalloys, as well as development of thin nickel-based oxide dispersion strengthened layers are presented in this paper. Integration of these material systems with commercially cast, novel, pin-fin internal cooling airfoil arrays, tripod film cooling hole architectures, trailing edge cooling geometries, and near surface micro-channel concepts is also presented. C2 - 2014/// C3 - Proceedings of the ASME Turbo Expo DA - 2014/// DO - 10.1115/GT2014-25640 VL - 6 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84922817151&partnerID=MN8TOARS ER - TY - CONF TI - Heat transfer performance of a transonic turbine blade passage in presence of leakage flow through upstream slot and mateface gap with endwall contouring AU - Roy, A. AU - Jain, S. AU - Ekkad, S.V. AU - Ng, W.F. AU - Lohaus, A.S. AU - Crawford, M.E. AB - Comparison of heat transfer performance of a non-axisymmetric contoured endwall to a planar baseline endwall in presence of leakage flow through stator-rotor rim seal interface and mateface gap is reported in this paper. Heat transfer experiments were performed on a high turning (∼127°) turbine airfoil passage at Virginia Tech’s transonic blow down cascade facility under design conditions (exit isentropic Mach number 0.88 and 0° incidence) for two leakage flow configurations — 1) mateface blowing only, 2) simultaneous coolant injection from the upstream slot as well as mateface gap. Coolant to mainstream mass flow ratios (MFR) were 0.35% for mateface blowing only, whereas for combination blowing, a 1.0% MFR was chosen from upstream slot and 0.35% MFR from mateface. A common source of coolant supply to the upstream slot and mateface plenum made sure the coolant temperatures were identical at both upstream slot and mateface gap at the injection location. The contoured endwall geometry was generated to minimize secondary aerodynamic losses. Transient IR (Infrared) thermography technique was used to measure endwall surface temperature and a linear regression method was developed for simultaneous calculation of heat transfer coefficient (HTC) and adiabatic cooling effectiveness (ETA), assuming a 1D semi-infinite transient conduction. Results indicate reduction in local hot spot regions near suction side as well as area averaged HTC using the contoured endwall compared to baseline endwall for all coolant blowing cases. Contoured geometry also shows better coolant coverage profiles further along the passage. Detailed interpretation of the heat transfer results along with near endwall flow physics has also been discussed. C2 - 2014/// C3 - Proceedings of the ASME Turbo Expo DA - 2014/// DO - 10.1115/GT2014-26476 VL - 5B UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84922368826&partnerID=MN8TOARS ER - TY - CONF TI - Evaluation of herringbone wavy fin based heat exchanger for heat transfer enhancement in automobile exhaust energy harvesting systems AU - Athavale, J.D. AU - Pandit, J. AU - Ekkad, S.V. AU - Huxtable, S.T. C2 - 2014/// C3 - Proceedings of the 15th International Heat Transfer Conference, IHTC 2014 DA - 2014/// DO - 10.1615/ihtc15.hte.009825 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85085407349&partnerID=MN8TOARS ER - TY - CONF TI - Effect of temperature on microparticle rebound characteristics at constant impact velocity AU - Delimont, J.M. AU - Murdock, M.K. AU - Ng, W.F. AU - Ekkad, S.V. AB - Many gas turbine engines operate in harsh environments where the engines ingest solid particles. Ingested particles accelerate the deterioration of engine components and reduce the engine’s service life. Understanding particle impacts on materials used in gas turbines at representative engine conditions leads to improved designs for turbomachinery operating in particle-laden environments. Coefficient of Restitution (COR) is a measure of particle/wall interaction and is used to study erosion and deposition. In the current study, the effect of temperature (independent of velocity) on COR was investigated. Arizona Road Dust (ARD) of 20–40/μm size was injected into a flow field to measure the effects of temperature and velocity on particle rebound. Target coupon materials used were 304 stainless steel and Hastelloy X. Tests were performed at three different temperatures, 300 K (ambient), 873 K, and 1073 K while the velocity of the flow field was held constant at 28 m/s. The impingement angle of the bulk sand on the coupon was varied from 30 ° to 80 ° for each temperature tested. The COR was found to decrease substantially from the ambient case to the 873 K and 1073 K cases. This decrease is believed to be due to the changes in the surface of both materials due to oxide layer formation which occurs as the target material is heated. The Hastelloy X material exhibits a larger decrease in COR than the stainless steel 304 material. The results are also compared to previously published literature. C2 - 2014/// C3 - Proceedings of the ASME Turbo Expo DA - 2014/// DO - 10.1115/GT2014-25687 VL - 1A UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84961300111&partnerID=MN8TOARS ER - TY - CONF TI - Effect of near melting temperatures on microparticle sand rebound characteristics at constant impact velocity AU - Delimont, J.M. AU - Murdock, M.K. AU - Ng, W.F. AU - Ekkad, S.V. AB - When gas turbine engines operate in environments where the intake air has some concentration of particles, the engine will experience degradation. Very few studies of microparticles at temperatures approaching the melting temperature of the particles are available in open literature. Coefficient of Restitution (COR), a measure of the particles’ impact characteristics, was measured for microparticles using a particle tracking technique. This study presents data taken using the Virginia Tech Aerothermal Rig and Arizona Road Dust (ARD) of 20–40μm size range. Data was taken at temperatures up to and including 1323 K, where significant deposition of the sand particles was observed. The velocity at which the particles impact the surface was held at a constant 70m/s for all of the temperature cases. The target on which the particles impacted was made of a nickel alloy, Hastelloy X. The particle angle of impact was also varied between 30° and 80°. The COR of the particles decreases slightly as some of the particles approach their glass transition point and start to become molten. Other particles, which do not become molten due to different particle composition, rebound and maintain a relatively high COR. Images were taken using a microscope to examine the particle deposition that occurs at various angles. A rebound ratio is formulated to give a measure of the number of particles which deposit on the surface. The results show an increase in deposition as the temperature approaches the melting temperature of sand. C2 - 2014/// C3 - Proceedings of the ASME Turbo Expo DA - 2014/// DO - 10.1115/GT2014-25686 VL - 1A UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84961342703&partnerID=MN8TOARS ER - TY - CONF TI - Aerodynamic performance of a transonic turbine blade passage in presence of upstream slot and mateface gap with endwall contouring AU - Jain, S. AU - Roy, A. AU - Ng, W. AU - Ekkad, S. AU - Lohaus, A.S. AU - Taremi, F. AB - The present article investigates mixed out aerodynamic loss coefficient measurements for a high turning, contoured endwall passage under transonic operating conditions in presence of upstream purge slot and mateface gap. The upstream purge slot represents the gap between stator-rotor interface and the mateface gap simulates the assembly feature between adjacent airfoils in an actual high pressure turbine stage. While the performance of the mateface and upstream slot has been studied for lower Mach number, no studies exist in literature for transonic flow conditions. Experiments were performed at the Virginia Tech’s linear, transonic blow down cascade facility. Measurements were carried out at design conditions (isentropic exit Mach number of 0.88, design incidence) without and with coolant blowing. Upstream leakage flow of 1.0% coolant to mainstream mass flow ratio (MFR) was considered with the presence of mateface gap. There was no coolant blowing through the mateface gap itself. Cascade exit pressure measurements were carried out using a 5-hole probe traverse at a plane 1.0-Cax downstream of the trailing edge. Spanwise measurements were performed to complete the entire 2D loss plane from endwall to midspan, which were used to plot pitchwise averaged losses for different span locations and loss contours for the passage. Results reveal significant reduction in aerodynamic losses using the contoured endwall due to the modification of flow physics compared to a non-contoured planar endwall. The heat transfer experiments, designed to find the heat transfer coefficient and the film cooling effectiveness are described in detail in a separate paper [1]. C2 - 2014/// C3 - Proceedings of the ASME Turbo Expo DA - 2014/// DO - 10.1115/GT2014-26475 VL - 2C UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84922210927&partnerID=MN8TOARS ER - TY - CONF TI - Flow field and liner heat transfer for a model annular combustor equipped with radial swirlers AU - Ramirez, D.G. AU - Kumar, V. AU - Ekkad, S.V. AU - Tafti, D. AU - Kim, Y. AU - Moon, H.-K. AU - Srinivasan, R. AB - Swirling flows for combustion stabilization, flame confinement, and proper fuel mixing and recirculation are prevalent in gas turbine combustor applications. Modern gas turbines use swirlers to induce strong rotating vortices and recirculation of the combustion gases to enhance combustion efficiency and stability. This study presents an experimental investigation of the flow field and wall heat transfer characteristics inside a model annular combustor equipped with radial swirlers. 2D Particle Image Velocimetry (2D-PIV) was used to characterize the flow field inside the combustor model. PIV measurements were taken for a single Reynolds number of 70000. To study the recirculation zone, data along the axial direction of the combustor were captured. The data show a slightly asymmetric flow, with the recirculation zone extending up to , where D is the hydraulic diameter of the entire annulus ( m). To study the evolution of the rotating vortex and the flow velocity close to the liner walls, PIV data was also captured at six cross-sections of the annular combustor. The vortex center was observed to be below the center of the swirler, consistent with the asymmetry observed in the axial measurements. Infrared (IR) thermography was used to measure the steady state heat transfer coefficients along the outer and inner liner walls for Reynolds numbers of , , and . The comparison between the heat transfer results for the different Reynolds numbers reveals a relatively constant position for the peak heat transfer at from the swirler exit for both walls. Computational Fluid Dynamics (CFD) calculations were also performed to better understand the characteristics of the flow inside the model combustor. The CFD model reproduces the experimental setup with a mesh of 25 million cells. A ReynoldsAveraged Navier-Stokes (RANS) model was used in the simulation, qualitatively reproducing the overall characteristics observed in the experiment. C2 - 2014/// C3 - 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference 2014 DA - 2014/// DO - 10.2514/6.2014-3436 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84913533935&partnerID=MN8TOARS ER - TY - CONF TI - Experimental and computational analysis of film cooling hole performance on a high temperature test rig AU - Ramesh, S. AU - Ekkad, S.V. AU - Straub, D.L. AU - Lawson, S.A. AU - Alvin, M.A. AB - Demand for more power from a gas turbine causes rotor inlet temperature to increase and in order to restrict the metal temperature in hot gas path components within a safe working limit, a better cooling system must be employed. This paper focuses on evaluating the performance of a film cooling hole in engine like conditions. Lab-scale experiments conducted prior to this study have established that tripod holes provide higher effectiveness compared to cylindrical and shaped holes while consuming only half the coolant. In spite of showing potential, it still has to yield superior cooling at engine like conditions. The high temperature test rig facility at NETL can raise the mainstream gas temperature as high as 1175 °C. Coolant temperature is adjusted to study film cooling performance at density ratio 2.8. This study presents results of baseline coupon testing. Metal coupons are made of Haynes230 alloy and are fabricated with cylindrical holes. Surface temperature is recorded using an IR thermographic camera which was calibrated using thermocouples, for different blowing ratios (0.5–2.0). Alongside experiment, a numerical model was also developed in an attempt to provide additional insight on the distribution of surface temperature and overall effectiveness downstream of cooling hole. It was observed that film cooling is effective at M=2.0 and 1.5 and this was associated with high inlet turbulence and swirling velocities disrupting the film cooling performance at lower blowing ratios. CFD predictions seemed to match better at M 1.0 but were found to deviate considerably at other blowing ratios. C2 - 2014/// C3 - ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) DA - 2014/// DO - 10.1115/IMECE2014-38735 VL - 8B UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84926431961&partnerID=MN8TOARS ER - TY - CONF TI - Evaluation of multi-louvered fin based heat exchangers for use in automobile exhaust energy harvesting systems AU - Athavale, J. AU - Pandit, J. AU - Ekkad, S.V. AU - Huxtable, S.T. C2 - 2014/// C3 - 52nd AIAA Aerospace Sciences Meeting - AIAA Science and Technology Forum and Exposition, SciTech 2014 DA - 2014/// DO - 10.2514/6.2014-0860 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85088760741&partnerID=MN8TOARS ER - TY - JOUR TI - Effect of rotation on detailed heat transfer distribution for various rib geometries in developing channel flow AU - Lamont, J.A. AU - Ekkad, S.V. AU - Alvin, M.A. T2 - Journal of Heat Transfer AB - The effects of Coriolis force and centrifugal buoyancy have a significant impact on heat transfer behavior inside rotating internal serpentine coolant channels for turbine blades. Due to the complexity of added rotation inside such channels, detailed knowledge of the heat transfer will greatly enhance the blade designer's ability to predict hot spots so coolant may be distributed more effectively. The effects of high rotation numbers are investigated on the heat transfer distributions for different rib types in near entrance and entrance region of the channels. It is important to determine the actual enhancement derived from turbulating channel entrances where heat transfer is already high due to entrance effects and boundary layer growth. A transient liquid crystal technique is used to measure detailed heat transfer coefficients (htc) for a rotating, short length, radially outward coolant channel with rib turbulators. Different rib types such as 90 deg, W, and M-shaped ribs are used to roughen the walls to enhance heat transfer. The channel Reynolds number is held constant at 12,000 while the rotation number is increased up to 0.5. Results show that in the near entrance region, the high performance W and M-shaped ribs are just as effective as the simple 90 deg ribs in enhancing heat transfer. The entrance effect in the developing region causes significantly high baseline heat transfer coefficients thus reducing the effective of the ribs to further enhance heat transfer. Rotation causes increase in heat transfer on the trailing side, while the leading side remains relatively constant limiting the decrement in leading side heat transfer. For all rotational cases, the W and M-shaped ribs show significant effect of rotation with large differences between leading and trailing side heat transfer. DA - 2014/// PY - 2014/// DO - 10.1115/1.4025211 VL - 136 IS - 1 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84887916305&partnerID=MN8TOARS ER - TY - JOUR TI - Effect of pin fin to channel height ratio and pin fin geometry on heat transfer performance for flow in rectangular channels AU - Pandit, Jaideep AU - Thompson, Megan AU - Ekkad, Srinath V. AU - Huxtable, Scott T. T2 - International Journal of Heat and Mass Transfer AB - The efficiency of a thermoelectric generator (TEG) can be defined as the ratio of the power output to the heat input at the hot side of the device. This ratio is governed by the laws of thermodynamics and thus cannot exceed the Carnot efficiency. It follows that the greater the difference between the temperatures of the hot and cold sides of the device, the greater the efficiency and power output from the TEG. This study focuses on effective techniques to enhance heat transfer on the hot side of the TEG in order to increase the total power output from the device. In this study heat transfer enhancement mechanisms are evaluated for the hot side of a TEG system generating power from waste heat in automobile exhaust gases. The use of pin fins was examined, as they are a common and effective way to increase heat transfer in a channel. Heat transfer enhancement measurements are presented with 3-dimensional partial pin fin arrays of circular, triangular, hexagonal, and diamond shapes on the walls of a rectangular channel representing the hot side of the TEG system and the automobile exhaust duct. Channel heights are varied to measure the effect of the pin fin height to channel height ratio while keeping the pin fin height constant. Channel hydraulic diameter and configuration of the fins were chosen based on existing literature. Pin fin performance is studied over a range of Reynolds numbers, calculated based on full channel height. The pin fins with the best initial performance have been further analyzed by varying the channel height in order to change the pin fin to channel height ratio while keeping the hydraulic diameter to pin fin height ratio constant. The experiments use the transient liquid crystal method to measure detailed heat transfer coefficients on the test surface. Results show that the diamond pin fins perform the best in enhancing heat transfer. Lower channel heights that cause pin fins to block 50% of the channel provide significantly higher heat transfer coefficients. DA - 2014/10// PY - 2014/10// DO - 10.1016/j.ijheatmasstransfer.2014.05.030 VL - 77 SP - 359-368 J2 - International Journal of Heat and Mass Transfer LA - en OP - SN - 0017-9310 UR - http://dx.doi.org/10.1016/j.ijheatmasstransfer.2014.05.030 DB - Crossref ER - TY - CONF TI - Direct-coupling simulation of thermal-hydraulic and stress analysis in a Cross-Wave primary surface heat exchanger AU - Zhang, J. AU - Ma, T. AU - Zeng, M. AU - Ekkad, S.V. AU - Wang, Q.W. AB - Fluid flow with heat transfer in the Cross Wave (CW) primary surface channels may cause an external stress in the plate due to the non-uniform pressure on the plate surface and non-uniform temperature inside the plate. The plate construction can be deformed under this external stress, which will affect the flow of the fluid by changing the channel dimensions and thus affect the temperature fields. To solve the multi-physical field problem, a direct-coupling simulation method of thermal-hydraulic and stress analysis in a Crow-Wave (CW) primary surface heat exchanger is presented in this paper. The method is based on the commercial code STAR-CD and ABAQUS, and an in house procedure is added to accomplish the direct-coupling simulation in a transient process between thermal-hydraulic and stress modules. Due to the complicated simulation of fluid flow and heat transfer in a two-coupled CW fluid channels in which each channel is separated by the plate (original model) in the CFD (Computer Fluid Dynamics) procedure, an alternative CFD model that is different from the original model is constructed to enable the CFD analysis. The detailed geometry of the original mode is generated in the CAE (Computer Aided Engineering) procedure. A data transition program is developed to control and transform analysis data between the CFD model and the CAE model. The coupling relationship of surface pressure, temperature and the material stress in the CW primary surface heat exchanger is uncovered. The results indicates that the high thermal stress and large displacement about 2.26 × 103 MPa of stress and 8.28 × 10−2 mm of displacement are generated at the beginning of time steps. Therefore, more attention should be paid during the starting up and emergency stop process due to the excessive build of stress during the transient conditions. C2 - 2014/// C3 - ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) DA - 2014/// DO - 10.1115/IMECE2014-37325 VL - 8A UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84926368064&partnerID=MN8TOARS ER - TY - JOUR TI - Effects of hierarchical features on longevity of submerged superhydrophobic surfaces with parallel grooves AU - Hemeda, A. A. AU - Gad-el-Hak, M. AU - Tafreshi, H. Vahedi T2 - Physics of Fluids AB - While the air–water interface over superhydrophobic surfaces decorated with hierarchical micro- or nanosized geometrical features have shown improved stability under elevated pressures, their underwater longevity—-the time that it takes for the surface to transition to the Wenzel state—-has not been studied. The current work is devised to study the effects of such hierarchical features on the longevity of superhydrophobic surfaces. For the sake of simplicity, our study is limited to superhydrophobic surfaces composed of parallel grooves with side fins. The effects of fins on the critical pressure—-the pressure at which the surface starts transitioning to the Wenzel state—-and longevity are predicted using a mathematical approach based on the balance of forces across the air–water interface. Our results quantitatively demonstrate that the addition of hierarchical fins significantly improves the mechanical stability of the air–water interface, due to the high advancing contact angles that can be achieved when an interface comes in contact with the fins sharp corners. For longevity on the contrary, the hierarchical fins were only effective at hydrostatic pressures below the critical pressure of the original smooth-walled groove. Our results indicate that increasing the length of the fins decreases the critical pressure of a submerged superhydrophobic groove but increases its longevity. Increasing the thickness of the fins can improve both the critical pressure and longevity of a submerged groove. The mathematical framework presented in this paper can be used to custom-design superhydrophobic surfaces for different applications. DA - 2014/8// PY - 2014/8// DO - 10.1063/1.4891363 VL - 26 IS - 8 SP - 082103 J2 - Physics of Fluids LA - en OP - SN - 1070-6631 1089-7666 UR - http://dx.doi.org/10.1063/1.4891363 DB - Crossref ER - TY - JOUR TI - Finite Element Analysis Project Proposal AU - Fong, Rey-Yie Abel AU - Chang, Huan-Yu Tony DA - 2014/// PY - 2014/// ER - TY - JOUR TI - Demonstration Software Modeling Exercise Aids Taiwan’s Yachtbuilding Community AU - Fong, Rey-Yie AU - Tsai, Ray AU - Lin, Yu-Chieh AU - Ou, Chia-Chuan T2 - High-Performance Composites DA - 2014/// PY - 2014/// VL - 22 IS - 3 SP - 68-69 ER - TY - JOUR TI - Luxury Yacht Design Takes a New Tack AU - Fong, Rey-Yie AU - Tsai, Ray AU - Lin, Yu-Chieh AU - Ou, Chia-Chuan T2 - Maritime Reporter and Engineering News DA - 2014/// PY - 2014/// ER - TY - JOUR TI - Finite Element Analysis Project Proposal for Yacht Hydrodynamic Quantification AU - Fong, Rey-Yie Abel AU - Chang, Huan-Yu Tony DA - 2014/// PY - 2014/// ER - TY - JOUR TI - Modeling the mechanical behavior of P3HT/fullerene blends for photovoltaic applications AU - Zhao, B. AU - Awartani, O. AU - O’Connor, B.T. AU - Zikry, M.A. T2 - Journal of the Gilded Age and Progressive Era DA - 2014/// PY - 2014/// DO - 10.1557/opl.2014.128 VL - 1628 IS - 2 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84919391709&partnerID=MN8TOARS ER - TY - JOUR TI - Editorial AU - Zikry, M. T2 - Journal of Engineering Materials and Technology AB - Dear Readers,I am honored to be named, the Editor in Chief for the ASME Journal of Engineering Materials and Technology. The journal has been in existence since 1973, and it is associated with the Materials Division of ASME. It has been providing top-quality research papers on contemporary issues of engineering materials and technology, for a broad spectrum of issues pertaining to experimental, computational, and theoretical investigations of the mechanical behavior of materials with a mechanics of materials perspective, at physical scales ranging from the nano to the macro for materials, such as metals, polymers, ceramics, composites, biomaterials, and nanostructured materials.I am indebted to the selfless service of all the previous editors, and especially, my predecessor, Professor Hussein Zbib, who have all guided the journal to the highest standards. The journal’s aim now is to continue to publish research of the highest quality and of lasting significance in areas related to engineering materials, mechanics of materials, and materials technology. The scope is broad, since it encompasses interdisciplinary research that spans fundamental knowledge, which is related to mechanics of materials, materials science, mathematics, and applied physics, and technological applications, which are related to engineering innovations and applications. The journal will include research articles, technical notes, book reviews, and special issues related to emerging areas.The content of the journal will, therefore, move to emphasize the multidisciplinary efforts needed to advance the field in areas related to materials development, experimental and computational analysis, and engineering innovation. Our aim, as an editorial board, in conjunction with the publishing team, is to establish the journal as the leading international forum for original scientific research with balanced contributions that combine theoretical, experimental, and computational investigations. We look forward to that challenge. DA - 2014/// PY - 2014/// DO - 10.1115/1.4026012 VL - 136 IS - 1 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84889836991&partnerID=MN8TOARS ER - TY - JOUR TI - General Formulations for Predicting Longevity of Submerged Superhydrophobic Surfaces Composed of Pores or Posts AU - Hemeda, A. A. AU - Tafreshi, H. Vahedi T2 - Langmuir AB - Superhydrophobicity can arise from the ability of a submerged rough hydrophobic surface to trap air in its surface pores, and thereby reduce the contact area between the water and the frictional solid walls. A submerged surface can only remain superhydrophobic (SHP) as long as it retains the air in its pores. SHP surfaces have a short underwater life, and their longevity depends strongly on the hydrostatic pressure at which they operate. In this work, a comprehensive mathematical framework is developed to predict the mechanical stability and the longevity of submerged SHP surfaces with arbitrary pore or post geometries. We start by deriving an integro-partial differential equation for the 3-D shape of the air-water interface, and use this information to predict the rate of dissolution of the entrapped air into the ambient water under different hydrostatic pressures. For the special case of circular pores, the above integro-partial differential equation is reduced to easy-to-solve ordinary differential equations. In addition, approximate nonlinear algebraic solutions are also obtained for surfaces with circular pores or posts. The effects of geometrical parameters and hydrostatic conditions on surface stability and longevity are discussed in detail. Moreover, a simple equivalent pore diameter method is developed for SHP surfaces composed of posts with ordered or random configuration--an otherwise complicated task requiring the solution of an integro-partial differential equation. DA - 2014/8/21/ PY - 2014/8/21/ DO - 10.1021/la501894u VL - 30 IS - 34 SP - 10317-10327 J2 - Langmuir LA - en OP - SN - 0743-7463 1520-5827 UR - http://dx.doi.org/10.1021/la501894u DB - Crossref ER - TY - JOUR TI - Modeling performance of multi-component fibrous insulations against conductive and radiative heat transfer AU - Arambakam, R. AU - Tafreshi, H. Vahedi AU - Pourdeyhimi, B. T2 - International Journal of Heat and Mass Transfer AB - In this work, we present a simulation methodology for studying heat transfer in multi-component fibrous media. Our simulation method is designed for high-porosity insulation media with air as the interstitial fluid where conduction through the solid structure is minimal. We obtain the resistance of fibrous media to radiative heat via a simulation method that incorporates both the microscale (fiber-level) and macroscale (media-level) properties of the constituent materials. We then combine this information with that obtained analytically for the conduction heat transfer through the media. The method presented here allows one to obtain quantitative predictions for the performance of media made up of different combinations of fibers with different materials or dimensions. For validation purposes, we simulated the experiment of Houston and Korpela [28] which was conducted for glass fiber insulations, and observed good agreement between the measurements and our predictions. For further demonstration, insulation media made up of glass and mineral wools fibers with different mass fractions and fiber diameters are simulated in blend and layered configurations and compared with each other. It was found that layered and blended fibrous multi-component insulations exhibit similar performance. It was also found that the stacking sequence does not affect the thermal resistance of layered media for the range of parameters studied here, in agreement with previous studies. DA - 2014/4// PY - 2014/4// DO - 10.1016/j.ijheatmasstransfer.2013.12.031 VL - 71 SP - 341-348 J2 - International Journal of Heat and Mass Transfer LA - en OP - SN - 0017-9310 UR - http://dx.doi.org/10.1016/j.ijheatmasstransfer.2013.12.031 DB - Crossref KW - Radiative heat transfer KW - Conduction heat transfer KW - Composite insulation media KW - Fibrous media ER - TY - JOUR TI - Modeling service life of pleated filters exposed to poly-dispersed aerosols AU - Saleh, A.M. AU - Fotovati, S. AU - Vahedi Tafreshi, H. AU - Pourdeyhimi, B. T2 - Powder Technology AB - In this work, we present a fast and flexible 3-D macroscale simulation method for modeling the instantaneous pressure drop and collection efficiency of pleated fibrous filters when exposed to poly-dispersed aerosols in both surface and depth filtration regimes. The simulations are conducted using the Fluent CFD code enhanced with a series of in-house subroutines. A cluster-injection method is developed to accelerate the formation and growth of dust-cake both inside and outside the filter media. Once calibrated with experiment or more accurate microscale simulations, the cluster-injection method can be used to simulate the service life of a pleated filter with reasonable accuracy and CPU time. The simulation methodology developed in this work can be used to design and develop pleated filters for different applications. In particular, it allows one to study the effects of pleat shape, pleat count, filter porosity, fiber diameter(s), flow velocity, aerosol concentration, and particle diameter, as well as the aerodynamic parameters of the flow on the evolution of a filter's pressure drop and collection efficiency over time. For demonstration purposes, performance of an arbitrary filter with 2 and 4 pleats per inch is simulated when challenged with poly-dispersed particles of 1 to 10 μm in diameter. For the filter simulated here, it was found that exposure to the above poly-dispersed aerosols results in a shorter service life in comparison to when the filter is exposure to mono-dispersed aerosols with a diameter of 1 or 10 μm having the same mass flux. DA - 2014/// PY - 2014/// DO - 10.1016/j.powtec.2014.06.011 VL - 266 SP - 79-89 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84903575710&partnerID=MN8TOARS KW - Modeling filtration KW - Dust-loading KW - Pleated filters KW - CFD simulation KW - Modeling poly-dispersed aerosols ER - TY - JOUR TI - Modeling air-water interface in disordered fibrous media with heterogeneous wettabilities AU - Bucher, T.M. AU - Vahedi Tafreshi, H. T2 - Colloids and Surfaces A: Physicochemical and Engineering Aspects AB - Considering the balance of mechanical forces across a meniscus anchored to two circular objects, we developed a CPU-friendly semi-analytical algorithm for tracking the instantaneous shape and position of the air–water interface inside microstructures that resemble a collection of disordered parallel cylinders, e.g., a bundle of fibers in a fiber-reinforced composite or microfabricated posts in a microfluidic system. In the context of fluid transport in fibrous media, in particular, the methodology presented in this paper provides a means for producing a relationship between capillary pressure and fluid saturation in media with heterogeneous wettabilities – often needed to predict the rate of fluid transport. In addition, we developed a conversion formulation that allows a capillary pressure–saturation relationship obtained for one combination of contact angles to be used to construct such a relationship for media with different combinations of contact angles, eliminating the need for additional simulations. DA - 2014/// PY - 2014/// DO - 10.1016/j.colsurfa.2014.08.006 VL - 461 IS - 1 SP - 323-335 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84906769865&partnerID=MN8TOARS KW - Capillarity KW - Fibrous media KW - Contact angles KW - Dissimilar fibers KW - Wettability ER - TY - JOUR TI - A simple semi-numerical model for designing pleated air filters under dust loading AU - Saleh, A.M. AU - Vahedi Tafreshi, H. T2 - Separation and Purification Technology AB - In this work, we present a semi-numerical 2-D model for predicting the instantaneous pressure drop and collection efficiency of filters made up of rectangular and triangular pleats in both depth and surface filtration regimes. Inspired from previous CFD simulations, our semi-numerical model adopts appropriate average velocity profiles in the axial and lateral directions to approximate the flow field inside rectangular and triangular pleat channels. The model therefore circumvents the need to obtain a CPU-intensive solution for the partial differential equations governing the flow through a filter, i.e., Navier–Stokes equations. The above-mentioned analytical flow field can then be used to predict the trajectory of the particles flowing through the pleat channels by numerically solving the equation of motion for each particle—a simple set of second order ordinary differential equations. With the particles trajectories obtained, the deposition location and so the dust-cake profile can be approximated. This allows one to predict the instantaneous pressure drop and collection efficiency of a filter (filter’s service life) with a CPU-time of practically zero min. The model developed in this work is aimed at providing the aerosol filtration industry with a fast, but yet fairly accurate method of designing pleated filters. A brief parametric study is presented for model demonstration. In addition, a comparison between the predictions of our model and some experimental data from literature is presented for completeness of the study. DA - 2014/// PY - 2014/// DO - 10.1016/j.seppur.2014.09.029 VL - 137 SP - 94-108 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84908463218&partnerID=MN8TOARS KW - Modeling Pleated Filter KW - Modeling Aerosol Filtration KW - Dust Loading ER - TY - JOUR TI - Energy harvesting of piezoelectric stack actuator from a shock event AU - Lee, A.J. AU - Wang, Y. AU - Inman, D.J. T2 - Journal of Vibration and Acoustics, Transactions of the ASME AB - The energy harvesting performance of a piezoelectric stack actuator under a shock event is theoretically and experimentally investigated. The first method is derived from the single degree of freedom constitutive equations, and then a correction factor is applied onto the resulting electromechanically coupled equations of motion. The second approach is deriving the coupled equations of motion with Hamilton's principle and the constitutive equations, and then formulating it with the finite element method. Two experimental cases matched well with the model predictions where the percent errors were 3.90% and 3.26% for the SDOF analysis and 1.52% and 1.42% for the FEM. DA - 2014/// PY - 2014/// DO - 10.1115/1.4025878 VL - 136 IS - 1 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84902192173&partnerID=MN8TOARS ER - TY - JOUR TI - Ultrasound-Triggered Regulation of Blood Glucose Levels Using Injectable Nano-Network AU - Di, Jin AU - Price, Jennifer AU - Gu, Xiao AU - Jiang, Xiaoning AU - Jing, Yun AU - Gu, Zhen T2 - Advanced Healthcare Materials AB - The integration of an injectable insulin-encapsulated nano-network with a focused ultrasound system (FUS) can remotely regulate insulin release both in vitro and in vivo. A single subcutaneous injection of the nano-network with intermittent FUS administration facilitates reduction of the blood glucose levels in type 1 diabetic mice for up to 10 d. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. DA - 2014/6// PY - 2014/6// DO - 10.1002/ADHM.201300490 VL - 3 IS - 6 SP - 811–816 SN - 2192-2640 UR - http://dx.doi.org/10.1002/ADHM.201300490 ER - TY - JOUR TI - Biaxially Mechanical Tuning of 2-D Reversible and Irreversible Surface Topologies through Simultaneous and Sequential Wrinkling AU - Yin, Jie AU - Yagüe, Jose Luis AU - Boyce, Mary C. AU - Gleason, Karen K. T2 - ACS Applied Materials & Interfaces AB - Controlled buckling is a facile means of structuring surfaces. The resulting ordered wrinkling topologies provide surface properties and features desired for multifunctional applications. Here, we study the biaxially dynamic tuning of two-dimensional wrinkled micropatterns under cyclic mechanical stretching/releasing/restretching simultaneously or sequentially. A biaxially prestretched PDMS substrate is coated with a stiff polymer deposited by initiated chemical vapor deposition (iCVD). Applying a mechanical release/restretch cycle in two directions loaded simultaneously or sequentially to the wrinkled system results in a variety of dynamic and tunable wrinkled geometries, the evolution of which is investigated using in situ optical profilometry, numerical simulations, and theoretical modeling. Results show that restretching ordered herringbone micropatterns, created through sequential release of biaxial prestrain, leads to reversible and repeatable surface topography. The initial flat surface and the same wrinkled herringbone pattern are obtained alternatively after cyclic release/restretch processes, owing to the highly ordered structure leaving no avenue for trapping irregular topological regions during cycling as further evidenced by the uniformity of strains distributions and negligible residual strain. Conversely, restretching disordered labyrinth micropatterns created through simultaneous release shows an irreversible surface topology whether after sequential or simultaneous restretching due to creation of irregular surface topologies with regions of highly concentrated strain upon formation of the labyrinth which then lead to residual strains and trapped topologies upon cycling; furthermore, these trapped topologies depend upon the subsequent strain histories as well as the cycle. The disordered labyrinth pattern varies after each cyclic release/restretch process, presenting residual shallow patterns instead of achieving a flat state. The ability to dynamically tune the highly ordered herringbone patterning through mechanical stretching or other actuation makes these wrinkles excellent candidates for tunable multifunctional surfaces properties such as reflectivity, friction, anisotropic liquid flow or boundary layer control. DA - 2014/2/14/ PY - 2014/2/14/ DO - 10.1021/am4054207 VL - 6 IS - 4 SP - 2850-2857 J2 - ACS Appl. Mater. Interfaces LA - en OP - SN - 1944-8244 1944-8252 UR - http://dx.doi.org/10.1021/am4054207 DB - Crossref KW - buckling KW - chemical vapor deposition KW - computer modeling KW - pattern KW - thin films ER - TY - BOOK TI - 8th International Conference on Porous Metals and Metallic Foams A3 - Rabiei, A. DA - 2014/// PY - 2014/// VL - 4 SP - 400 PB - Elseiver ER - TY - JOUR TI - Preface AU - Rabiei, Afsaneh T2 - Procedia Materials Science DA - 2014/// PY - 2014/// DO - 10.1016/J.MSPRO.2014.07.552 VL - 4 SP - 1 J2 - Procedia Materials Science LA - en OP - SN - 2211-8128 UR - http://dx.doi.org/10.1016/J.MSPRO.2014.07.552 DB - Crossref ER - TY - CONF TI - Noise-Influenced Dynamics in Nonlinear Systems AU - Perkins, Edmon AU - Balachandran, Balakumar T2 - Ford Foundation Conference C2 - 2014/// CY - Newport Beach, CA DA - 2014/// PY - 2014/// ER - TY - JOUR TI - Linear-Quadratic-Gaussian Control of Rijke-Type Combustion Instability AU - Rubio Hervas, J. AU - Zhao, D. AU - Reyhanoglu, M. T2 - Mathematics in Engineering, Science and Aerospace DA - 2014/// PY - 2014/// VL - 5 IS - 4 SP - 445-456 ER - TY - JOUR TI - Thrust-vector control of a three-axis stabilized upper-stage rocket with fuel slosh dynamics AU - Rubio Hervas, J.R. AU - Reyhanoglu, M. T2 - Acta Astronautica AB - This paper studies the thrust vector control problem for an upper-stage rocket with fuel slosh dynamics. The dynamics of a three-axis stabilized spacecraft with a single partially-filled fuel tank are formulated and the sloshing propellant is modeled as a multi-mass–spring system, where the oscillation frequencies of the mass–spring elements represent the prominent sloshing modes. The equations of motion are expressed in terms of the three-dimensional spacecraft translational velocity vector, the attitude, the angular velocity, and the internal coordinates representing the slosh modes. A Lyapunov-based nonlinear feedback control law is proposed to control the translational velocity vector and the attitude of the spacecraft, while attenuating the sloshing modes characterizing the internal dynamics. A simulation example is included to illustrate the effectiveness of the control law. DA - 2014/5// PY - 2014/5// DO - 10.1016/j.actaastro.2014.01.022 VL - 98 SP - 120–127 KW - Thrust-vector control KW - Propellant slosh KW - Lyapunov methods ER - TY - CONF TI - Sliding mode control of fixed-wing UAVs in windy environments AU - Hervas, Jaime Rubio AU - Kayacan, Erdal AU - Reyhanoglu, Mahmut AU - Tang, Hui T2 - 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV) AB - In this paper, a fully nonlinear aircraft dynamic model in the presence of wind is introduced. Assuming the wind vortex hypothesis, the equations of motion are formulated in a novel nonlinear control system form that is affine in control input for the chosen aircraft model. A sliding mode controller is subsequently developed where the position of the throttle is used to control the air velocity and the aileron, elevator, and rudder deflections are employed to control the rest of the dynamics. It is shown that the full state converges to the desired values even in the presence of the uncertainties imposed by the wind. The applicability of the controller design is illustrated through simulations in the presence of uncertainties. C2 - 2014/12// C3 - 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV) CY - Singapore DA - 2014/12// PY - 2014/12/10/ DO - 10.1109/ICARCV.2014.7064440 PB - IEEE SN - 9781479951994 UR - http://dx.doi.org/10.1109/ICARCV.2014.7064440 ER - TY - JOUR TI - Feedback control of acoustic disturbance transient growth in triggering thermoacoustic instability AU - Zhao, Dan AU - Reyhanoglu, Mahmut T2 - Journal of Sound and Vibration AB - Transient growth of acoustic disturbances could trigger thermoacoustic instability in a combustion system with non-orthogonal eigenmodes, even with stable eigenvalues. In this work, feedback control of transient growth of flow perturbations in a Rijke-type combustion system is considered. For this, a generalized thermoacoustic model with distributed monopole-like actuators is developed. The model is formulated in state-space to gain insights on the interaction between various eigenmodes and the dynamic response of the system to the actuators. Three critical parameters are identified: (1) the mode number, (2) the number of actuators, and (3) the locations of the actuators. It is shown that in general the number of the actuators K is related to the mode number N as K=N2. For simplicity in illustrating the main results of the paper, two different thermoacoustic systems are considered: system (a) with one mode and system (b) that involves two modes. The actuator location effect is studied in system (a) and it is found that the actuator location plays an important role in determining the control effort. In addition, sensitivity analysis of pressure- and velocity-related control parameters is conducted. In system (b), when the actuators are turned off (i.e., open-loop configuration), it is observed that acoustic energy transfers from the high frequency mode to the lower frequency mode. After some time, the energy is transferred back. Moreover, the high frequency oscillation grows into nonlinear limit cycle with the low frequency oscillation amplified. As a linear-quadratic regulator (LQR) is implemented to tune the actuators, both systems become asymptotically stable. However, the LQR controller fails in eliminating the transient growth, which may potentially trigger thermoacoustic instability. In order to achieve strict dissipativity (i.e., unity maximum transient growth), a transient growth controller is systematically designed and tested in both systems. Comparison is then made between the performance of the LQR controller and that of the transient growth controller. It is found in both systems that the transient growth controller achieves both exponential decay of the flow disturbance energy and unity maximum transient growth. DA - 2014/8// PY - 2014/8// DO - 10.1016/j.jsv.2014.04.015 VL - 333 IS - 16 SP - 3639-3656 J2 - Journal of Sound and Vibration LA - en OP - SN - 0022-460X UR - http://dx.doi.org/10.1016/j.jsv.2014.04.015 DB - Crossref ER - TY - JOUR TI - Stable hierarchical model predictive control using an inner loop reference model and λ-contractive terminal constraint sets AU - Vermillion, Chris AU - Menezes, Amor AU - Kolmanovsky, Ilya T2 - Automatica AB - This paper proposes a novel hierarchical model predictive control (MPC) strategy that guarantees overall system stability. This method differs significantly from previous approaches to guaranteeing overall stability, which have relied upon a multi-rate framework where the inner loop (low level) is updated at a faster rate than the outer loop (high level), and the inner loop must reach a steady state within each outer loop time step. In contrast, the method proposed in this paper is aimed at stabilizing the origin of an error system characterized by the difference between the inner loop state and the state specified by a full-order reference model. This makes the method applicable to systems with reduced levels of time scale separation. This paper proposes a framework for guaranteeing stability that leverages the use of the reference model, in conjunction with λ-contractive constraint sets for both the inner and outer loops. The effectiveness of the proposed reference model-based strategy is shown through simulation on an existing stirred-tank reactor problem, where we demonstrate that the MPC optimization problem remains feasible and that the system remains stable and continues to perform well when time scale separation between the inner and outer loops is reduced. DA - 2014/1// PY - 2014/1// DO - 10.1016/j.automatica.2013.10.009 VL - 50 IS - 1 SP - 92-99 J2 - Automatica LA - en OP - SN - 0005-1098 UR - http://dx.doi.org/10.1016/j.automatica.2013.10.009 DB - Crossref ER - TY - JOUR TI - Comparison of soot formation for diesel and jet-a in a constant volume combustion chamber using two-color pyrometry AU - Jing, W. AU - Roberts, W. AU - Fang, T. T2 - SAE Technical Papers DA - 2014/// PY - 2014/// DO - 10.4271/2014-01-1251 VL - 1 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84899540595&partnerID=MN8TOARS ER - TY - JOUR TI - Three-dimensional anisotropic moisture absorption in quartz-reinforced bismaleimide laminates AU - Grace, L.R. AU - Altan, M.C. T2 - Polymer Engineering & Science AB - The three-dimensional anisotropic moisture absorption behavior of quartz-fiber-reinforced bismaleimide (BMI) laminates is investigated by collecting 21 months of experimental gravimetric data. Laminates of six, twelve, and forty plies and various planar aspect ratios are used to determine the three-dimensional anisotropic diffusion behavior when exposed to full immersion in distilled water at 25°C. The long-term moisture absorption behavior deviates from the widely used Fickian model, but can be accurately captured by the three-dimensional, anisotropic hindered diffusion model (3D HDM). Excellent agreement is achieved between experimental gravimetric data and the 3D HDM for all laminate thicknesses. Recovered model parameters are shown to slightly vary with laminate thickness due to the small changes in the cured-ply thickness. However, model parameters identified for a given laminate thickness are observed to accurately predict the absorption behavior of samples with different planar dimensions. Equilibrium moisture content of 1.72, 1.69, and 1.84% and corresponding diffusion hindrance coefficients of 0.807, 0.844, and 0.671 are recovered for six, twelve, and forty-ply laminates, respectively, thus confirming strong non-Fickian behavior. Moisture absorption parameters may be determined successfully at 16.5 months of immersion, before reaching approximately 85% of the equilibrium moisture content at 21 months. Subsequent gravimetric measurements up to 21 months are consistent with the predicted long-term behavior. POLYM. ENG. SCI., 54:137–146, 2014. © 2013 Society of Plastics Engineers DA - 2014/1// PY - 2014/1// DO - 10.1002/PEN.23549 VL - 54 IS - 1 SP - 137–146 SN - 0032-3888 UR - http://dx.doi.org/10.1002/PEN.23549 ER - TY - CONF TI - Nonlinear automatic landing control of unmanned aerial vehicles on moving platforms via a 3D laser radar AU - Hervas, Jaime Rubio AU - Reyhanoglu, Mahmut AU - Tang, Hui T2 - 10TH INTERNATIONAL CONFERENCE ON MATHEMATICAL PROBLEMS IN ENGINEERING, AEROSPACE AND SCIENCES: ICNPAA 2014 AB - Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Jaime Rubio Hervas, Mahmut Reyhanoglu, Hui Tang; Nonlinear automatic landing control of unmanned aerial vehicles on moving platforms via a 3D laser radar. AIP Conf. Proc. 10 December 2014; 1637 (1): 907–917. https://doi.org/10.1063/1.4904663 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search C2 - 2014/// C3 - DA - 2014/// DO - 10.1063/1.4904663 PB - AIP Publishing LLC UR - http://dx.doi.org/10.1063/1.4904663 DB - Crossref KW - UAV KW - sliding mode KW - nonlinear control KW - state estimation KW - extended Kalman filter KW - laser radar KW - landing ER - TY - CONF TI - Observer-based control of Rijke-type combustion instability AU - Hervas, Jaime Rubio AU - Zhao, Dan AU - Reyhanoglu, Mahmut T2 - 10TH INTERNATIONAL CONFERENCE ON MATHEMATICAL PROBLEMS IN ENGINEERING, AEROSPACE AND SCIENCES: ICNPAA 2014 AB - In this work, observer-based feedback control of combustion instability in a Rijke-type thermoacoustic system is considered. A generalized thermoacoustic model with distributed monopole-like actuators is developed. The model is linearized and formulated in state-space and it is assumed that pressure sensors are the only information available for feedback. It is shown that a system of this form is observable. As a Linear-Quadratic-Gaussian (LQG) controller is implemented to tune the actuators, the system becomes asymptotically stable. The performance of the controller is evaluated with a system involving two modes. The successful demonstration indicates that the observer-based feedback controller can be applied to a real combustion system with multiple modes. C2 - 2014/// C3 - DA - 2014/// DO - 10.1063/1.4904662 PB - AIP Publishing LLC UR - http://dx.doi.org/10.1063/1.4904662 DB - Crossref KW - Combustion instability KW - LQG control KW - non-normality ER - TY - CONF TI - Feedback Control of Transient Growth of Thermoacoustic Oscillations AU - Zhao, Dan AU - Reyhanoglu, Mahmut T2 - 20th AIAA/CEAS Aeroacoustics Conference C2 - 2014/6/13/ C3 - 20th AIAA/CEAS Aeroacoustics Conference DA - 2014/6/13/ DO - 10.2514/6.2014-3183 PB - American Institute of Aeronautics and Astronautics SN - 9781624102851 UR - http://dx.doi.org/10.2514/6.2014-3183 DB - Crossref ER - TY - CONF TI - Observer-based nonlinear control of space vehicles with multi-mass fuel slosh dynamics AU - Hervas, Jaime Rubio AU - Reyhanoglu, Mahmut T2 - 2014 IEEE 23rd International Symposium on Industrial Electronics (ISIE) AB - This paper studies the problem of observer-based control of space vehicles with fuel slosh dynamics in a zero gravity environment. Multi-mass-spring models are considered for the characterization of the most prominent sloshing modes. The control objective is to control the translational velocity vector and the attitude of the spacecraft, while attenuating the sloshing modes. A full-state feedback that uses a reduced-order observer for the estimation of the slosh states is proposed to achieve the objective. The effectiveness of the proposed observer-based control law is illustrated through a computer simulation. C2 - 2014/6// C3 - 2014 IEEE 23rd International Symposium on Industrial Electronics (ISIE) DA - 2014/6// DO - 10.1109/ISIE.2014.6864607 PB - IEEE SN - 9781479923991 UR - http://dx.doi.org/10.1109/ISIE.2014.6864607 DB - Crossref ER - TY - CONF TI - Automatic landing control of Unmanned Aerial Vehicles on moving platforms AU - Hervas, Jaime Rubio AU - Reyhanoglu, Mahmut AU - Tang, Hui T2 - 2014 IEEE 23rd International Symposium on Industrial Electronics (ISIE) AB - This paper studies the landing control problem for Unmanned Aerial Vehicles (UAVs) on an oscillating platform such as a ship deck in a rough sea. A full nonlinear mathematical model is first introduced for the UAV in an inertial frame. A Fourier transform based method is then employed for a realistic characterization of the sea motion and the ship dynamics. Finally, a landing control algorithm is developed based on the dynamics of the UAV relative to the ship. The effectiveness of the control algorithm is illustrated through a simulation example. C2 - 2014/6// C3 - 2014 IEEE 23rd International Symposium on Industrial Electronics (ISIE) DA - 2014/6// DO - 10.1109/ISIE.2014.6864588 PB - IEEE SN - 9781479923991 UR - http://dx.doi.org/10.1109/ISIE.2014.6864588 DB - Crossref ER - TY - CONF TI - Nonlinear feedback control of thermoacoustic oscillations in a Rijke tube AU - Hervas, Jaime Rubio AU - Zhao, Dan AU - Reyhanoglu, Mahmut T2 - 2014 IEEE 23rd International Symposium on Industrial Electronics (ISIE) AB - Flow disturbances could undergo transient growth to trigger thermoacoustic instability in a combustion system with non-orthogonal eigenmodes. In this work, nonlinear feedback control of thermoacoustic oscillations in a Rijke-type combustion system is considered. A generalized thermoacoustic model with distributed monopole-like actuators is proposed. To stabilize the thermoacoustic system, a Lyapunov-based nonlinear controller is developed. It is shown that the nonlinear feedback controller achieves both exponential decay of the flow disturbance energy and unity maximum transient growth. C2 - 2014/6// C3 - 2014 IEEE 23rd International Symposium on Industrial Electronics (ISIE) DA - 2014/6// DO - 10.1109/ISIE.2014.6864606 PB - IEEE SN - 9781479923991 UR - http://dx.doi.org/10.1109/ISIE.2014.6864606 DB - Crossref ER - TY - CONF TI - Evaluation of a Water Channel-Based Platform for Characterizing Aerostat Flight Dynamics: A Case Study on a Lighter-Than-Air Wind Energy System AU - Vermillion, Chris AU - Glass, Ben AU - Greenwood, Sam T2 - 21st AIAA Lighter-Than-Air Systems Technology Conference AB - Aerostat development and testing costs often suffer from a lack of scalability. In particular, it very difficult to fabricate an inexpensive lighter-than-air system that can be evaluated in a lab environment, since the maximum allowable mass of the aerostat becomes prohibitively low for small length scales. This paper presents an evaluation of a novel water channel-based platform for assessing the flight dynamics of aerostats at a very small scale, in a lab environment, for a very low cost. Altaeros Energies’ buoyant airborne turbine (BAT) is used as a case study to demonstrate the effectiveness of the proposed approach. Specifically, we identify important dynamic scaling properties and show how the water channel experiments are run to match these properties closely in the water channel vs. full-scale settings. We then show how the water channel results can be used in concert with a simulation model to predict the performance of the full-scale system. The ultimate result is a design which, after an inexpensive evaluation process, can proceed to a larger-scale prototype stage with a high degree of confidence in its success. C2 - 2014/6/13/ C3 - 21st AIAA Lighter-Than-Air Systems Technology Conference DA - 2014/6/13/ DO - 10.2514/6.2014-2711 PB - American Institute of Aeronautics and Astronautics SN - 9781624102868 UR - http://dx.doi.org/10.2514/6.2014-2711 DB - Crossref ER - TY - CONF TI - Development and Full-Scale Experimental Validation of a Rapid Prototyping Environment for Plant and Control Design of Airborne Wind Energy Systems AU - Vermillion, Chris AU - Glass, Ben AU - Szalai, Balazs T2 - ASME 2014 Dynamic Systems and Control Conference AB - Airborne wind energy systems present great promise for inexpensive, clean energy at remote locations, but have only been demonstrated through short-duration flights in very limited wind conditions. Because of the time and money that is required to implement full-scale airborne wind energy prototypes, convergence toward designs that achieve longer-duration flight in adverse weather has been slow. This paper presents an inexpensive rapid prototyping approach for improving the flight dynamics and control of airborne wind energy systems, which has been implemented and validated on Altaeros Energies most recent full-scale flight prototype. The approach involves the 3d printing of lab-scale water channel models of airborne wind energy lifting bodies, which enable prediction of dynamic flight characteristics, rapid iteration between the designs, identification of unknown or poorly known parameters, and improved control design. By applying this approach to its last prototype design cycle, Altaeros demonstrated robust operation in double the wind speeds sustained by its previous prototype (reaching a maximum of 21.2 m/s, with sustained 10–15 m/s winds), with demonstrably improved flight characteristics. C2 - 2014/10/22/ C3 - Volume 2: Dynamic Modeling and Diagnostics in Biomedical Systems; Dynamics and Control of Wind Energy Systems; Vehicle Energy Management Optimization; Energy Storage, Optimization; Transportation and Grid Applications; Estimation and Identification Methods, Tracking, Detection, Alternative Propulsion Systems; Ground and Space Vehicle Dynamics; Intelligent Transportation Systems and Control; Energy Harvesting; Modeling and Control for Thermo-Fluid Applications, IC Engines, Manufacturing DA - 2014/10/22/ DO - 10.1115/dscc2014-5907 PB - American Society of Mechanical Engineers SN - 9780791846193 UR - http://dx.doi.org/10.1115/dscc2014-5907 DB - Crossref ER - TY - JOUR TI - Model-Based Plant Design and Hierarchical Control of a Prototype Lighter-Than-Air Wind Energy System, With Experimental Flight Test Results AU - Vermillion, Chris AU - Grunnagle, Trey AU - Lim, Ronny AU - Kolmanovsky, Ilya T2 - IEEE Transactions on Control Systems Technology AB - This paper presents the modeling, control system design, and experimental results for a prototype lighter-than-air wind energy system being pioneered by Altaeros Energies. This unique design features a horizontal-axis turbine that is elevated to high altitudes through a buoyant shroud, which is tethered to a ground-based platform. The system's altitude can be adjusted to maximize power production, and because the system is both functional and economical in a stationary position, it circumvents many of the controls challenges faced by kite-based wind energy systems. However, the need for generation of energy introduces pointing, efficiency, and autonomy requirements, which are not faced by conventional aerostats, thereby requiring a careful model-based control design. In this paper, we provide a dynamic model of the Altaeros system, then show how this model is leveraged in the plant design and in the design of the control system, which provides full autonomy, from takeoff, through power production, to autonomous landing. We provide simulation and experimental results that demonstrate the performance of the prototype and point to important areas where Altaeros will focus its efforts moving forward. DA - 2014/3// PY - 2014/3// DO - 10.1109/tcst.2013.2263505 VL - 22 IS - 2 SP - 531-542 J2 - IEEE Trans. Contr. Syst. Technol. OP - SN - 1063-6536 1558-0865 UR - http://dx.doi.org/10.1109/tcst.2013.2263505 DB - Crossref KW - Aerospace KW - energy systems KW - predictive control ER - TY - JOUR TI - Measurements of ultrasound velocity and attenuation in numerical anisotropic porous media compared to Biot’s and multiple scattering models AU - Mézière, Fabien AU - Muller, Marie AU - Bossy, Emmanuel AU - Derode, Arnaud T2 - Ultrasonics AB - This article quantitatively investigates ultrasound propagation in numerical anisotropic porous media with finite-difference simulations in 3D. The propagation media consist of clusters of ellipsoidal scatterers randomly distributed in water, mimicking the anisotropic structure of cancellous bone. Velocities and attenuation coefficients of the ensemble-averaged transmitted wave (also known as the coherent wave) are measured in various configurations. As in real cancellous bone, one or two longitudinal modes emerge, depending on the micro-structure. The results are confronted with two standard theoretical approaches: Biot's theory, usually invoked in porous media, and the Independent Scattering Approximation (ISA), a classical first-order approach of multiple scattering theory. On the one hand, when only one longitudinal wave is observed, it is found that at porosities higher than 90% the ISA successfully predicts the attenuation coefficient (unlike Biot's theory), as well as the existence of negative dispersion. On the other hand, the ISA is not well suited to study two-wave propagation, unlike Biot's model, at least as far as wave speeds are concerned. No free fitting parameters were used for the application of Biot's theory. Finally we investigate the phase-shift between waves in the fluid and the solid structure, and compare them to Biot's predictions of in-phase and out-of-phase motions. DA - 2014/7// PY - 2014/7// DO - 10.1016/J.ULTRAS.2013.09.013 VL - 54 IS - 5 SP - 1146-1154 J2 - Ultrasonics LA - en OP - SN - 0041-624X UR - http://dx.doi.org/10.1016/J.ULTRAS.2013.09.013 DB - Crossref KW - Cancellous bone KW - Fast and slow waves KW - Porous media KW - Multiple scattering KW - Biot's theory ER - TY - JOUR TI - Drug Delivery: Ultrasound-Triggered Regulation of Blood Glucose Levels Using Injectable Nano-Network (Adv. Healthcare Mater. 6/2014) AU - Di, Jin AU - Price, Jennifer AU - Gu, Xiao AU - Jiang, Xiaoning AU - Jing, Yun AU - Gu, Zhen T2 - Advanced Healthcare Materials AB - On page 811, Y. Jing, Z. Gu and co-workers present the integration of an injectable nano-network with a focused ultrasound system (FUS) which can remotely regulate insulin release both in vitro and in vivo. Serving as a synthetic insulin reservoir, the nano-network consisting of adhesive biodegradable nanoparticles promotes insulin release upon FUS triggers in a pulsatile, remote and non-invasive control manner. Image courtesy of Dwayne Martin. DA - 2014/6// PY - 2014/6// DO - 10.1002/ADHM.201470027 VL - 3 IS - 6 SP - 789-789 J2 - Adv. Healthcare Mater. LA - en OP - SN - 2192-2640 UR - http://dx.doi.org/10.1002/ADHM.201470027 DB - Crossref ER - TY - JOUR TI - Corrigendum to “Soot measurements for diesel and biodiesel spray combustion under high temperature highly diluted ambient conditions” [Fuel 135 (2014) 340–351] AU - Zhang, Ji AU - Jing, Wei AU - Roberts, William L. AU - Fang, Tiegang T2 - Fuel DA - 2014/12// PY - 2014/12// DO - 10.1016/J.FUEL.2014.08.052 VL - 137 SP - 413 J2 - Fuel LA - en OP - SN - 0016-2361 UR - http://dx.doi.org/10.1016/J.FUEL.2014.08.052 DB - Crossref ER - TY - JOUR TI - Use of Composite Metal Foam for Improving Absorption of Collision Forces AU - Alvandi-Tabrizi, Youness AU - Rabiei, Afsaneh T2 - Procedia Materials Science AB - Studies devoted to understand the mechanical behavior of Composite Metal Foams (CMFs) have revealed superior energy absorption capacity under quasi-static loading. Accordingly, CMF is a great nominee to replace currently used materials in vehicles crash energy management system. However, in order to utilize the full capacity of CMF under impact loading, understanding its high strain rate behavior is needed. This paper seeks to investigate the strain rate sensitivity of CMF by conducting Split Hopkinson Pressure Bar experiments. The test samples were manufactured using powder metallurgy technique and the role of loading rate and sample size was studied. The obtained results shows high rate dependency of the stress-strain behavior and an improvement in energy absorption capacity under impact loading. DA - 2014/// PY - 2014/// DO - 10.1016/j.mspro.2014.07.577 VL - 4 SP - 377-382 J2 - Procedia Materials Science LA - en OP - SN - 2211-8128 UR - http://dx.doi.org/10.1016/j.mspro.2014.07.577 DB - Crossref KW - Compiste metal foam KW - Dynamic loading KW - Powder Metallurgy KW - Split Hopkinson pressure bar ER - TY - JOUR TI - Introduction of a New Type of Metal Foam (Metallic Bubble Wrap) AU - Miao, Di AU - Rabiei, Afsaneh T2 - Procedia Materials Science AB - New type of metallic foam is processed in the form of thin sheet aluminum with longer lifetime and more reliable properties than currently used metal foams. The current closed cell metallic foams are highly porous and non-uniform and their deformation behavior is not predictable, particularly in a thin sheet form. The new material has combined rolling technique with careful placement of foaming agent to produce thin sheet metal foams (a metallic version of bubble wraps) with regular pore structure and possibility of further addition of reinforcement. Both tension test results and bending test results show improvements in mechanical properties of aluminum bubble wrap. DA - 2014/// PY - 2014/// DO - 10.1016/j.mspro.2014.07.563 VL - 4 SP - 3-7 J2 - Procedia Materials Science LA - en OP - SN - 2211-8128 UR - http://dx.doi.org/10.1016/j.mspro.2014.07.563 DB - Crossref KW - Metallic bubble wrap KW - roll bonding KW - three-point bending test KW - tensile test KW - mechanical properties ER - TY - JOUR TI - Applications of Open-cell and Closed-cell Metal Foams for Radiation Shielding AU - Chen, Shuo AU - Bourham, Mohamed AU - Rabiei, Afsaneh T2 - Procedia Materials Science AB - A comparison of attenuation effectiveness against gamma rays and thermal neutrons among aluminum A356, close-cell composite metal foams and open-cell Aluminum foam infiltrated with variety of second phase materials were investigated experimentally and theoretically in this study. Gamma rays attenuation measurements were carried out at photon energies of 0.060, 1.173, and 1.332 MeV and thermal neutron transmission measurements were conducted at North Carolina State University using PLUSTAR Neutron Powder Diffraction Facility with a thermal neutron flux of about 0.5x105n/cm2/s at the specimen location. The results obtained revealed that close-cell composite metal foams offer better gamma rays and neutron attenuation capabilities compared to aluminum A356, whereas open-cell Al foam with fillers exhibit higher neutron attenuation effectiveness than close-cell composite metal foams but less gamma rays shielding property than that of aluminum A356. This study indicates the potential of utilizing the light-weight composite metal foams as shielding material replacing current heavy materials used for attenuation of gamma rays and thermal neutrons with additional advantages such as high energy absorption and excellent heat rejection capabilities. DA - 2014/// PY - 2014/// DO - 10.1016/j.mspro.2014.07.560 VL - 4 SP - 293-298 J2 - Procedia Materials Science LA - en OP - SN - 2211-8128 UR - http://dx.doi.org/10.1016/j.mspro.2014.07.560 DB - Crossref KW - Gamma ray KW - Neutron KW - Areal density KW - Radiation shielding ER - TY - JOUR TI - Ballistic Performance of a Composite Metal Foam-ceramic Armor System AU - Garcia-Avila, Matias AU - Portanova, Marc AU - Rabiei, Afsaneh T2 - Procedia Materials Science AB - Composite Metal Foam is a low-weight, high-strength porous material capable of absorbing great amounts of energy under loading. In this report, Composite Metal Foam panels are manufactured using powder metallurgy technique and 2 mm steel hollow spheres in a steel matrix and used in conjunction with a ceramic plate to fabricate a new light-weight composite armor system. This armor system is tested under ballistic loading using 7.62x51 mm M80 and 7.62x63 mm M2 AP projectiles at varying impact velocities for single and multi-impact scenarios. The material behavior, failure mechanism, and ballistic performance of the armor system are studied for optimization. DA - 2014/// PY - 2014/// DO - 10.1016/j.mspro.2014.07.571 VL - 4 SP - 151-156 J2 - Procedia Materials Science LA - en OP - SN - 2211-8128 UR - http://dx.doi.org/10.1016/j.mspro.2014.07.571 DB - Crossref KW - Composite metal foam KW - Powder metallurgy KW - Ballistic KW - Energy absorption ER - TY - JOUR TI - The design and applications of superomniphobic surfaces AU - Kota, Arun K AU - Kwon, Gibum AU - Tuteja, Anish T2 - NPG Asia Materials AB - Surfaces that display contact angles >150° along with low contact angle hysteresis with essentially all high and low surface tension liquids, including water, oils and alcohols, are known as superomniphobic surfaces. Such surfaces have a range of commercial applications, including self-cleaning, non-fouling, stain-free clothing, drag reduction, corrosion prevention and separation of liquids. Such surfaces have thus generated immense academic and industrial interest in recent years. In this review, we discuss the systematic design of superomniphobic surfaces. In particular, we discuss the significance of surface energy, roughness and the critical role of re-entrant texture in obtaining the so-called Cassie–Baxter state with low surface tension liquids. We also discuss how hierarchical scales of texture can yield high contact angles and decrease the contact angle hysteresis of superomniphobic surfaces by reducing the solid–liquid contact area. On the basis of this understanding, we discuss dimensionless design parameters that allow for the systematic design of superomniphobic surfaces. We also review the current literature on superomniphobic surfaces, paying particular attention to surfaces that demonstrate good mechanical, chemical and radiation durability—traits that are essential for any commercial application of superomniphobic surfaces. Finally, we conclude by identifying the unresolved challenges in the fabrication of durable superomniphobic surfaces and highlight the future needs in the field. Surfaces that display contact angles >150° along with a low contact angle hysteresis for both low and high surface tension liquids are known as superomniphobic surfaces. Such surfaces have several applications, including self-cleaning, non-fouling, stain-free clothing, drag reduction, corrosion prevention and separation of liquids. In this review, we discuss the design criteria, recent studies, applications, challenges and potential of superomniphobic surfaces. Surfaces that strongly repel low surface tension liquids (e.g. oils and alcohols) are classified as superoleophobic and those that strongly repel high surface tension liquids (e.g. water) are classified as superhydrophobic. However, if a surface shows both these characteristics, it can be considered superomniphobic. Liquid droplets on superomniphobic surfaces roll off very easily and, as a result, these surfaces are attractive as non-fouling coatings, self-cleaning surfaces and liquid-separation techniques. Anish Tuteja at the University of Michigan, United States, and colleagues review the design principles required to fabricate superomniphobic surfaces. They discuss surface energy, roughness and hierarchical scales of surface texture, and recognize the importance of re-entrant textures (i.e. convex topography) to achieve superomniphobicity. Several examples of superomniphobic surfaces are presented with particular focus on the need to improve chemical and mechanical durability, to realize their full potential in commercial and industrial applications. DA - 2014/7// PY - 2014/7// DO - 10.1038/am.2014.34 VL - 6 IS - 7 SP - e109-e109 J2 - NPG Asia Mater LA - en OP - SN - 1884-4049 1884-4057 UR - http://dx.doi.org/10.1038/am.2014.34 DB - Crossref KW - Oil-repellent KW - Omniphobic KW - Superhydrophobic KW - Superoleophobic KW - Superomniphobic KW - Water-repellent ER - TY - JOUR TI - Analytical and Numerical Modeling of Thick Tube Hydroforging AU - Alzahrani, Bandar AU - Ngaile, Gracious T2 - Procedia Engineering AB - Hydroforging is a hybrid forming operation whereby a thick tube is formed to a desired geometry by combining forging and hydroforming processes. Through this process hollow structures with high strength-to-weight ratio can be produced for applications in power transmission systems, etc. In this process, a thick tube is deformed by pressurized fluid contained within the tube using a multi-purpose punch assembly, which is also used to feed tube material into the die cavity. An analytical model for determining pressure-feed loading paths is formulated for the hydroforging process. The model is derived based of plasticity theory and deformed shape evolution. Stepwise solution schemes are used to calculate instantaneous pressure, material feed, stresses, strains, and other geometrical parameters. The derived analytical model can be used for preliminary process design before embarking in extensive FE simulations. The model is also ideal for rapid establishment of loading paths for different geometrical configurations. Thus, time spent in trial-and-error finite element simulations carried out to determine optimal loading path for a specific part can be reduced significantly. DA - 2014/// PY - 2014/// DO - 10.1016/J.PROENG.2014.10.312 VL - 81 SP - 2223-2229 J2 - Procedia Engineering LA - en OP - SN - 1877-7058 UR - http://dx.doi.org/10.1016/J.PROENG.2014.10.312 DB - Crossref KW - Tube hydroforming process KW - Thick tube hydroforging KW - Analytical modeling KW - Numerical simulation KW - Loading path ER - TY - JOUR TI - High-velocity impact bonding of dissimilar metals by chemically produced hydrogen energy AU - Ngaile, Gracious AU - Lohr, Peter AU - Modlin, Rhyne AU - Lowrie, James T2 - Manufacturing Letters AB - There has been a growing demand in the fabrication of dissimilar metal parts for application in the automotive, aerospace, defense, chemical and nuclear industries. Welding of dissimilar materials can be accomplished via impact welding, which can minimize the formation of a continuous inter-metallic phase, while chemically bonding dissimilar metals. This paper discusses an innovative technique for bonding dissimilar metals by chemically produced hydrogen energy by reacting aluminum powder and water. Experiments were carried out to bond copper and stainless steel billets. Preliminary test results show the potential of this technique for near-net-shape impact bonding of discrete parts. DA - 2014/4// PY - 2014/4// DO - 10.1016/J.MFGLET.2014.01.003 VL - 2 IS - 2 SP - 40-43 J2 - Manufacturing Letters LA - en OP - SN - 2213-8463 UR - http://dx.doi.org/10.1016/J.MFGLET.2014.01.003 DB - Crossref ER - TY - JOUR TI - Consideration of Cyclic Degradation of the Material and Abnormality of the Surface Layer Mechanical Properties in Calculating the Life of a Plate with an Opening* AU - Mironov, V. I. AU - Kuznetsov, A. V. AU - Emel’yanov, I. G. T2 - Strength of Materials DA - 2014/9// PY - 2014/9// DO - 10.1007/S11223-014-9594-Y VL - 46 IS - 5 SP - 638-643 J2 - Strength Mater LA - en OP - SN - 0039-2316 1573-9325 UR - http://dx.doi.org/10.1007/S11223-014-9594-Y DB - Crossref KW - plate with an opening KW - fatigue crack KW - cyclic degradation of the material KW - total stress-strain curve ER - TY - JOUR TI - Vortex dynamics around pitching plates AU - Jantzen, Ryan T. AU - Taira, Kunihiko AU - Granlund, Kenneth O. AU - Ol, Michael V. T2 - Physics of Fluids AB - Vortex dynamics of wakes generated by rectangular aspect-ratio 2 and 4 and two-dimensional pitching flat plates in free stream are examined with direct numerical simulation and water tunnel experiments. Evolution of wake vortices comprised of tip, leading-edge, and trailing-edge vortices is compared with force history for a range of pitch rates. The plate pivots about its leading edge with reduced frequency from π/8 to π/48, which corresponds to pitching over 1 to 6 chord lengths of travel. Computations have reasonable agreement with experiments, despite large differences in Reynolds number. Computations show that the tip effects are confined initially near the wing tips, but begin to strongly affect the leading-edge vortex as the motion of the plate proceeds, with concomitant effects on lift and drag history. Scaling relations based on reduced frequency are shown to collapse aerodynamic force history for the various pitch rates. DA - 2014/5// PY - 2014/5// DO - 10.1063/1.4879035 VL - 26 IS - 5 SP - 053606 J2 - Physics of Fluids LA - en OP - SN - 1070-6631 1089-7666 UR - http://dx.doi.org/10.1063/1.4879035 DB - Crossref ER - TY - JOUR TI - Airfoil longitudinal gust response in separated vs. attached flows AU - Granlund, K. AU - Monnier, B. AU - Ol, M. AU - Williams, D. T2 - Physics of Fluids AB - Airfoil aerodynamic loads are expected to have quasi-steady, linear dependence on the history of input disturbances, provided that small-amplitude bounds are observed. We explore this assertion for the problem of periodic sinusoidal streamwise gusts, by comparing experiments on nominally 2D airfoils in temporally sinusoidal modulation of freestream speed in a wind tunnel vs. sinusoidal displacement of the airfoil in constant freestream in a water tunnel. In the wind tunnel, there is a streamwise unsteady pressure gradient causing a buoyancy force, while in the water tunnel one must subtract the inertial load of the test article. Both experiments have an added-mass contribution to aerodynamic force. Within measurement resolution, lift and drag, fluctuating and mean, were in good agreement between the two facilities. For incidence angle below static stall, small-disturbance theory was found to be in good agreement with measured lift history, regardless of oscillation frequency. The circulatory component of fluctuating drag was found to be independent of oscillation frequency. For larger incidence angles, there is marked departure between the measured lift history and that predicted from Greenberg's formula. Flow visualization shows coupling between bluff-body shedding and motion-induced shedding, identifiable with lift cancellation or augmentation, depending on the reduced frequency. Isolating the buoyancy effect in the wind tunnel and dynamic tares in the water tunnel, and theoretical calculation of apparent-mass in both cases, we arrive at good agreement in measured circulatory contribution between the two experiments whether the flow is attached or separated substantiating the linear superposition of the various constituents to total lift and drag, and supporting the idea that aerodynamic gust response can legitimately be studied in a steady freestream by oscillating the test article. DA - 2014/2// PY - 2014/2// DO - 10.1063/1.4864338 VL - 26 IS - 2 SP - 027103 J2 - Physics of Fluids LA - en OP - SN - 1070-6631 1089-7666 UR - http://dx.doi.org/10.1063/1.4864338 DB - Crossref ER - TY - JOUR TI - Size effect on the thermal conductivity of ultrathin polystyrene films T2 - Applied Physics Letters AB - Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Jun Liu, Shenghong Ju, Yifu Ding, Ronggui Yang; Size effect on the thermal conductivity of ultrathin polystyrene films. Appl. Phys. Lett. 14 April 2014; 104 (15): 153110. https://doi.org/10.1063/1.4871737 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioApplied Physics Letters Search Advanced Search |Citation Search DA - 2014/4/14/ PY - 2014/4/14/ DO - 10.1063/1.4871737 UR - http://dx.doi.org/10.1063/1.4871737 ER - TY - JOUR TI - Pump-probe measurements of the thermal conductivity tensor for materials lacking in-plane symmetry T2 - Review of Scientific Instruments AB - We previously demonstrated an extension of time-domain thermoreflectance (TDTR) which utilizes offset pump and probe laser locations to measure in-plane thermal transport properties of multilayers. However, the technique was limited to systems of transversely isotropic materials studied using axisymmetric laser intensities. Here, we extend the mathematics so that data reduction can be performed on non-transversely isotropic systems. An analytic solution of the diffusion equation for an N-layer system is given, where each layer has a homogenous but otherwise arbitrary thermal conductivity tensor and the illuminating spots have arbitrary intensity profiles. As a demonstration, we use both TDTR and time-resolved magneto-optic Kerr effect measurements to obtain thermal conductivity tensor elements of <110> α-SiO2. We show that the out-of-phase beam offset sweep has full-width half-maxima that contains nearly independent sensitivity to the in-plane thermal conductivity corresponding to the scanning direction. Also, we demonstrate a Nb-V alloy as a low thermal conductivity TDTR transducer layer that helps improve the accuracy of in-plane measurements. DA - 2014/10// PY - 2014/10// DO - 10.1063/1.4897622 UR - http://dx.doi.org/10.1063/1.4897622 ER - TY - JOUR TI - Measurement of the anisotropic thermal conductivity of molybdenum disulfide by the time-resolved magneto-optic Kerr effect T2 - Journal of Applied Physics AB - We use pump-probe metrology based on the magneto-optic Kerr effect to measure the anisotropic thermal conductivity of (001)-oriented MoS2 crystals. A ≈20 nm thick CoPt multilayer with perpendicular magnetization serves as the heater and thermometer in the experiment. The low thermal conductivity and small thickness of the CoPt transducer improve the sensitivity of the measurement to lateral heat flow in the MoS2 crystal. The thermal conductivity of MoS2 is highly anisotropic with basal-plane thermal conductivity varying between 85–110 W m-1 K-1 as a function of laser spot size. The basal-plane thermal conductivity is a factor of ≈50 larger than the c-axis thermal conductivity, 2.0±0.3 W m-1 K-1. DA - 2014/12/21/ PY - 2014/12/21/ DO - 10.1063/1.4904513 UR - http://dx.doi.org/10.1063/1.4904513 ER - TY - JOUR TI - Prediction of matrix-to-cell stress transfer in heart valve tissues AU - Huang, Siyao AU - Huang, Hsiao-Ying Shadow T2 - Journal of Biological Physics AB - Non-linear and anisotropic heart valve leaflet tissue mechanics manifest principally from the stratification, orientation, and inhomogeneity of their collagenous microstructures. Disturbance of the native collagen fiber network has clear consequences for valve and leaflet tissue mechanics and presumably, by virtue of their intimate embedment, on the valvular interstitial cell stress–strain state and concomitant phenotype. In the current study, a set of virtual biaxial stretch experiments were conducted on porcine pulmonary valve leaflet tissue photomicrographs via an image-based finite element approach. Stress distribution evolution during diastolic valve closure was predicted at both the tissue and cellular levels. Orthotropic material properties consistent with distinct stages of diastolic loading were applied. Virtual experiments predicted tissue- and cellular-level stress fields, providing insight into how matrix-to-cell stress transfer may be influenced by the inhomogeneous collagen fiber architecture, tissue anisotropic material properties, and the cellular distribution within the leaflet tissue. To the best of the authors’ knowledge, this is the first study reporting on the evolution of stress fields at both the tissue and cellular levels in valvular tissue and thus contributes toward refining our collective understanding of valvular tissue micromechanics while providing a computational tool enabling the further study of valvular cell–matrix interactions. DA - 2014/10/9/ PY - 2014/10/9/ DO - 10.1007/s10867-014-9362-z VL - 41 IS - 1 SP - 9-22 J2 - J Biol Phys LA - en OP - SN - 0092-0606 1573-0689 UR - http://dx.doi.org/10.1007/s10867-014-9362-z DB - Crossref KW - Finite element method KW - Heart valve tissues KW - Biomechanics KW - Stress analysis KW - Collagen fiber orientation KW - Tissue engineering ER - TY - JOUR TI - Special Section on Spectroscopy, Scattering, and Imaging Techniques for Nanostructured Materials AU - Huang, Hsiao-Ying Shadow AU - Subramanian, Arunkumar T2 - Journal of Nanotechnology in Engineering and Medicine AB - Nanotechnology has seen rapid progress in recent years, with the emergence of advanced capabilities to synthesize and characterize precisely engineered materials that point toward disruptive new performance regimes of relevance for diverse application areas. Understanding how the atomic, electronic, mechanical, and magnetic structures/properties of materials relate to their performance across multiple length-scales is, thus, of growing importance. This special topic titled “Spectroscopy, Scattering, and Imaging Techniques for Nanostructured Materials” focuses on understanding these fundamental processes, which occur within material systems in the atomic or nanoscopic regime, using advanced tools such as time-of-flight secondary ion mass spectrometry, scanning electron microscopy (SEM), X-ray diffraction (XRD), helium ion microscopy (HIM), atomic force microscopy, Raman thermometry, and in situ imaging techniques. This understanding is being leveraged by the scientific community to deliver new knowledge that has the potential to improve the performance of different material systems: lithium-ion battery materials, biological materials, nanostructured materials for energy applications, carbon nanofiber, nanoparticles, nanowires (NW), silicon microcantilevers, etc. The special topic brings together a wide variety of excellent contributions from the scientific community showcasing the depth and breadth in this vibrant topical area within nanotechnology. The collection of papers exemplifies how the current state-of-the-art of imaging and spectroscopic techniques provides new insights into these exciting nano and biological materials with unprecedented resolution.Seven papers were submitted to this special section. Chiu Huang and colleagues at North Carolina State University investigate the origins of voltage fluctuations in high discharging current rate (C-rate) lithium-ion batteries by quantifying lithium-ion intensity and distribution via time-of-flight secondary ion mass spectrometry. Interestingly, it is observed that lithium-ion intensity and distribution are not C-rate dependent, suggesting that different lithium-ion insertion mechanisms might be solely responsible for the observed low-frequency voltage fluctuation at higher C-rates.The paper from Palapati et al. at Virginia Commonwealth University investigates elastic modulus measurements on large diameter NW using a nano-assembled platform. The nanomechanical platform is constructed by assembling single NWs across pairs of gold nano-electrodes using dielectrophoresis and contains a short, suspended segment of the NW (in air) between the assembly electrodes. AFM force spectroscopy measurements are followed. The study demonstrates the measurement technique using lithium iron phosphate NW, which is a cathodic material of interest for battery applications, as a model system and presents a finite element model to extract the Young's modulus from nanomechanical data. This data is relevant for use within computational models that predict the stresses and cycle-life capabilities of battery nanomaterial systems.Samykano et al. at the North Carolina A&T State University provide morphological and crystallographic characterization of nickel NW synthesized by template based electrodeposition method. The structure and morphology of the synthesized NW are studied using HIM and SEM methods. The crystallographic properties of the grown NW are also studied using XRD. The results clearly indicate that properties of synthesized nickel NW are strongly influenced by the applied magnetic field and current density intensity during the synthesis process.Zhang and colleagues at Purdue University have utilized Raman thermometry to characterize bone materials and studied the influence of structural hierarchy on physical properties such as thermal conductivity and its correlation with mechanical stresses. The unique analytic-experimental approach provides stress-thermal conductivity correlation in bovine cortical bone as a function of nanomechanical compressive stress and temperature changes. It is observed that the thermal conductivity values increase and then decrease as a function of increase in compressive strain in bone tissues.Goudarzi et al. at University of British Columbia characterize different lignin powders via XRD and study the variations in the XRD patterns during carbon nanofiber formation. The results indicate that the graphite peak for (101) plane is available in the grinded carbon nanofibers, and it is suggested that the available sulfate groups in lignins might facilitate graphite formation in carbon nanofiber production process.Tomar's research group at Purdue University reports in situ creep properties of silicon microcantilevers in the temperature range of 25 °C to 100 °C under uni-axial compressive stress; as the silicon structures are commonly subject to this temperature range and the stress level of tens to hundreds of MPa in micro-electromechanical systems. The results reveal that in the stress range of 50–150 MPa, the strain rate of the silicon cantilever increases linearly as a function of applied stress, and the strain rate also increases as a function of increased temperature. Moreover, the sensitivity of the strain rate change with respect to change in temperature or stress is much lower comparing with the literature values. It is suggested the near-surface atoms of the microscale silicon exhibit a relaxed state signified by lower surface stress values than bulk, especially at high temperature.Jingjie Zhang and Da-Ren Chen at Virginia Commonwealth University have provided a review article on differential mobility particle sizers for nanoparticle characterization. These instruments are used for characterizing gas-borne particles in submicrometer and nanometer diameter ranges. Specifically, aerosol chargers, differential mobility analyzers (DMA), and particle concentration detectors are discussed. This article gives an interesting overview of the state-of-art DMAs, which are particularly designed for sizing particles with the sizes down to sub-10 nm.We would like to thank the authors for choosing to publish their work to this special section in the ASME Journal of Nanotechnology in Engineering and Medicine. The papers included in this special section gives an interesting snap shot of the current research topics in this emerging area of nanoscience and nano-engineering. We hope that this special section will stimulate future discussion and collaboration among physicists, engineers, and material scientists in this interdisciplinary research field and we hope you enjoy reading this special section. DA - 2014/9/11/ PY - 2014/9/11/ DO - 10.1115/1.4028352 VL - 5 IS - 2 SP - 020201 J2 - J. Nanotechnol. Eng. Med LA - en OP - SN - 1949-2944 UR - http://dx.doi.org/10.1115/1.4028352 DB - Crossref ER - TY - CONF TI - Soft dry electrodes for electrocardiogram with conductive silver nanowires AU - Myers, A. AU - Zhu, Y. C2 - 2014/// C3 - Materials Research Society Symposium Proceedings DA - 2014/// DO - 10.1557/opl.2014.787 VL - 1685 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84926351615&partnerID=MN8TOARS ER - TY - JOUR TI - Temperature sensor made of polymer-derived ceramics for high-temperature applications AU - Zhao, R. AU - Shao, G. AU - Cao, Y. AU - An, L. AU - Xu, C. T2 - Sensors and Actuators, A: Physical AB - This paper describes the use of polymer-derived SiAlCN (silicoaluminum carbonitride) ceramics (PDC) to fabricate a temperature sensor for high-temperature applications. A unique sensor head was designed and fabricated with Pt wires seamlessly embedded in as electrodes. Material characterization test demonstrates that the resistance of the senor head decreases monotonically with surrounding temperature, suggesting its readiness to be used for temperature measurement. In actual experiment (temperature up to 830 °C), the measurement of the PDC sensor demonstrates good repeatability to both unidirectional and bidirectional temperature variations for the total span of 10 h, and its measurement follows closely with the thermal couple measurement. These results demonstrated that the temperature sensors made of polymer-derived ceramics (PDC) have excellent accuracy and repeatability, and can be used in high temperature environment. DA - 2014/// PY - 2014/// DO - 10.1016/j.sna.2014.08.012 VL - 219 SP - 58-64 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84907528396&partnerID=MN8TOARS KW - High-temperature sensor KW - Temperature measurement KW - Polymer-derived ceramic KW - Turbine engine ER - TY - JOUR TI - Interaction of the cutting tools and the ceramic-reinforced metal matrix composites during micro-machining: A review AU - Liu, J. AU - Li, J. AU - Xu, C. T2 - CIRP Journal of Manufacturing Science and Technology AB - High performance ceramic-reinforced metal matrix composites (MMCs) are becoming widely popular in industry and the mechanical machining method is one of the most suitable manufacturing techniques for near net shape MMC components. This paper provides a comprehensive literature review to enhance the fundamental understanding of the tool–workpiece interactions in micro-scale during cutting process on engineered-heterogeneous materials. The paper focuses on mechanical properties, fracture mechanism and machinability of ceramic-reinforced MMCs, with significant emphasis on the chip formation mechanism considering different dominant effects, such as materials strengthening mechanisms, micro-structural effect, size effect and minimum chip thickness effect. It also includes some work that, while not directly focused on micro-scale cutting ceramic-reinforced MMCs, but provided important insight to the field of cutting engineered-heterogeneous materials (non-eutectic). Furthermore, process modeling studies for micro-scale cutting are also surveyed, including the cutting force modeling, dynamics modeling and surface generation modeling. The comments on future needs and directions are provided at the end. DA - 2014/// PY - 2014/// DO - 10.1016/j.cirpj.2014.01.003 VL - 7 IS - 2 SP - 55-70 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84894105664&partnerID=MN8TOARS KW - Micro-machining KW - Heterogeneous materials KW - Ceramic particle reinforcement KW - Metal matrix composites KW - Size effect KW - Minimum chip thickness KW - Tool-workpiece interaction KW - Strengthening mechanism KW - Materials microstructural effect KW - Materials mechanical property KW - Fracture mechanism KW - Machining dynamics KW - Surface generation ER - TY - JOUR TI - Evanescent-mode-resonator-based and antenna-integrated wireless passive pressure sensors for harsh-environment applications AU - Cheng, H. AU - Shao, G. AU - Ebadi, S. AU - Ren, X. AU - Harris, K. AU - Liu, J. AU - Xu, C. AU - An, L. AU - Gong, X. T2 - Sensors and Actuators, A: Physical AB - A wireless pressure sensor for high-temperature applications is demonstrated based on a microwave evanescent-mode cavity resonator. Cavity deformation resulting from applied external pressure can be detected by measuring the resonant frequency change of the sensor. Compact sensor size is achieved by loading a cylindrical post inside the cavity resonator. In addition, a patch antenna is seamlessly integrated with the pressure sensor, without additional volume. This pressure sensor is able to survive high temperatures by adopting passive structures and robust ceramic/metallic materials. Fully-dense silicoaluminum carbonitride (SiAlCN) ceramic is used herein owing to its excellent thermal–mechanical properties and manufacturability as a Polymer-Derived Ceramic (PDC). A PDC soft-lithography technique is developed to fabricate the ceramic pressure sensor. In order to wirelessly interrogate the pressure sensor at high temperatures, a robust interrogation antenna is designed and fabricated with a wide fractional bandwidth. Finally, the cavity deformation of pressure sensor versus external pressure is measured at high temperatures up to 800 °C. The resonant frequency decreases from 11.75 to 11.56 GHz, when the applied external force on the sensor increases from 0 to 5 N at 800 °C. DA - 2014/// PY - 2014/// DO - 10.1016/j.sna.2014.09.010 VL - 220 SP - 22-33 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84957042668&partnerID=MN8TOARS KW - Evanescent-mode resonator KW - Harsh environment KW - Integrated antenna KW - Polymer-Derived Ceramic KW - Pressure sensor KW - Wireless passive sensor ER - TY - JOUR TI - Evaluation of ductile fracture models in finite element simulation of metal cutting processes AU - Liu, J. AU - Bai, Y. AU - Xu, C. T2 - Journal of Manufacturing Science and Engineering, Transactions of the ASME AB - In this paper, a systematic evaluation of six ductile fracture models is conducted to identify the most suitable fracture criterion for metal cutting processes. Six fracture models are evaluated in this study, including constant fracture strain, Johnson-Cook, Johnson-Cook coupling criterion, Wilkins, modified Cockcroft-Latham, and Bao-Wierzbicki fracture criterion. By means of abaqus built-in commands and a user material subroutine (VUMAT), these fracture models are implemented into a finite element (FE) model of orthogonal cutting processes in abaqus/Explicit platform. The local parameters (stress, strain, fracture factor, and velocity fields) and global variables (chip morphology, cutting forces, temperature, shear angle, and machined surface integrity) are evaluated. The numerical simulation results are examined by comparing to experimental results of 2024-T3 aluminum alloy published in the open literature. Based on the results, it is found that damage evolution should be considered in cutting process FE simulation. Moreover, the B-W fracture model with consideration of rate dependency, temperature effect and damage evolution gives the best prediction of chip removal behavior of ductile metals. DA - 2014/// PY - 2014/// DO - 10.1115/1.4025625 VL - 136 IS - 1 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84894082831&partnerID=MN8TOARS KW - finite element modeling KW - ductile fracture models KW - machining processes simulation KW - Johnson-Cook (J-C) model KW - chip formation ER - TY - JOUR TI - In Situ Imaging of Lithium-Ion Batteries Via the Secondary Ion Mass Spectrometry AU - ChiuHuang, Cheng-Kai AU - Zhou, Chuanzhen AU - Shadow Huang, Hsiao-Ying T2 - Journal of Nanotechnology in Engineering and Medicine AB - To develop lithium-ion batteries with a high rate-capability and low cost, the prevention of capacity loss is one of major challenges, which needs to be tackled in the lithium-ion battery industry. During electrochemical processes, lithium ions diffuse from and insert into battery electrodes accompanied with the phase transformation, whereas ionic diffusivity and concentration are keys to the resultant battery capacity. In the current study, we compare voltage versus capacity of lithium-ion batteries at different current-rates (C-rates) discharging. Larger hysteresis and voltage fluctuations are observed in higher C-rate samples. We investigate origins of voltage fluctuations by quantifying lithium-ion intensity and distribution via a time-of-flight secondary ion mass spectrometry (ToF-SIMS). The result shows that for fully discharged samples, lithium-ion intensity and distribution are not C-rate dependent, suggesting different lithium-ion insertion mechanisms at a higher C-rate discharging might be solely responsible for the observed low frequency voltage fluctuation. DA - 2014/8/19/ PY - 2014/8/19/ DO - 10.1115/1.4028010 VL - 5 IS - 2 SP - 021002 J2 - J. Nanotechnol. Eng. Med LA - en OP - SN - 1949-2944 UR - http://dx.doi.org/10.1115/1.4028010 DB - Crossref ER - TY - JOUR TI - Directional Biomechanical Properties Of Porcine Skin Tissue AU - Huang, Hsiao Ying Shadow AU - Huang, Siyao AU - Frazier, Colin P. AU - Prim, Peter M. AU - Harrysson, Ola T2 - Journal of Mechanics in Medicine and Biology AB - Skin is a multilayered composite material and composed principally of the proteins collagen, elastic fibers and fibroblasts. The direction-dependent material properties of skin tissue is important for physiological functions like skin expansion. The current study has developed methods to characterize the directional biomechanical properties of porcine skin tissues as studies have shown that pigs represent a useful animal model due to similarities between porcine and human skin. It is observed that skin tissue has a nonlinear anisotropy biomechanical behavior, where the parameters of material modulus is 378 ± 160 kPa in the preferred-fiber direction and 65.96 ± 40.49 kPa in the cross-fiber direction when stretching above 30% strain equibiaxially. The result from the study provides methods of characterizing biaxial mechanical properties of skin tissue, as the collagen fiber direction appears to be one of the primary determinants of tissue anisotropy. DA - 2014/8// PY - 2014/8// DO - 10.1142/S0219519414500699 VL - 14 IS - 05 SP - 1450069 SN - 0219-5194 1793-6810 UR - http://dx.doi.org/10.1142/S0219519414500699 KW - Mechanical property KW - skin tissue KW - collagen fiber orientation ER - TY - JOUR TI - Sliding Mode Control of Feed Drive System for a Three-axis Micro-Machining Platform with Nano-Resolution AU - Ji, Y. AU - Xu, C. T2 - Journal of Control Engineering and Technology DA - 2014/// PY - 2014/// VL - 4 IS - 1 SP - 29–36 ER - TY - SOUND TI - Optimization of Carbon Nanofibers Alignment Induced by Shear Force AU - Yang, J. AU - Xu, C. DA - 2014/// PY - 2014/// ER - TY - JOUR TI - Vortex dynamics around pitching plates AU - Jantzen R., Taira K. AU - Granlund K., AU - M., Ol T2 - Physics of Fluids (Woodbury, N.Y.) DA - 2014/// PY - 2014/// VL - 26 IS - 053606 ER - TY - JOUR TI - Free-to-Pivot Flat Plates in Hover for Reynolds Numbers 14 to 21,200 AU - Granlund, Kenneth O. AU - Ol, Michael V. AU - Bernal, Luis P. T2 - AIAA JOURNAL AB - No AccessTechnical NoteFree-to-Pivot Flat Plates in Hover for Reynolds Numbers 14 to 21,200Kenneth O. Granlund, Michael V. Ol and Luis P. BernalKenneth O. GranlundAerospace Systems Directorate, U.S. Air Force Research Laboratory, Wright–Patterson Air Force Base, Ohio 45433-7542*Aerospace Systems Directorate; . Senior Member AIAA.Search for more papers by this author, Michael V. OlAerospace Systems Directorate, U.S. Air Force Research Laboratory, Wright–Patterson Air Force Base, Ohio 45433-7542†Aerospace Systems Directorate. Associate Fellow AIAA.Search for more papers by this author and Luis P. BernalDepartment of Aerospace Engineering, University of Michigan, Ann Arbor, Michigan 48109-2140‡Department of Aerospace Engineering. Senior Member AIAA.Search for more papers by this authorPublished Online:26 Aug 2014https://doi.org/10.2514/1.J053169SectionsView Full TextPDFPDF Plus ToolsAdd to favoritesDownload citationTrack citations ShareShare onFacebookTwitterLinked InRedditEmail About References [1] Freymuth P., “Thrust Generation by an Airfoil in Hover Modes,” Experiments in Fluids, Vol. 9, Nos. 1–2, 1990, pp. 17–24. doi:https://doi.org/10.1007/BF00575331 EXFLDU 0723-4864 CrossrefGoogle Scholar[2] Sane S. P. and Dickinson M. H., “The Control of Flight Force by a Flapping Wing: Lift and Drag Production,” Journal of Experimental Biology, Vol. 204, Aug. 2001, pp. 2607–2626. JEBIAM 0022-0949 CrossrefGoogle Scholar[3] Dickson W. and Dickinson M., “The Effect of Advance Ratio on the Aerodynamics of Revolving Wings,” Journal of Experimental Biology, Vol. 207, Nov. 2004, pp. 4269–4281. doi:https://doi.org/10.1242/jeb.01266 JEBIAM 0022-0949 CrossrefGoogle Scholar[4] Wan H., Dong H. and Huang G., “Hovering Hinge-Connected Flapping Plate with Passive Deflection,” AIAA Journal, Vol. 50, No. 9, 2012, pp. 2020–2026. doi:https://doi.org/10.2514/1.J051375 AIAJAH 0001-1452 LinkGoogle Scholar[5] Shyy W., Aono H., Kang C.-k. and Liu H., An Introduction to Flapping Wing Aerodynamics, Cambridge Univ. Press, New York, 2013, pp. 95–116. CrossrefGoogle Scholar[6] Granlund K., Ol M. and Bernal L., “Unsteady Pitching Flat Plates,” Journal of Fluid Mechanics, Vol. 733, Oct. 2013, p. R5. doi:https://doi.org/10.1017/jfm.2013.444 JFLSA7 0022-1120 CrossrefGoogle Scholar[7] Granlund K., Ol M. and Bernal L., “Quasi-Steady Response of Free-to-Pivot Flat Plates in Hover,” Journal of Fluids and Structures, Vol. 40, July 2013, pp. 337–355. doi:https://doi.org/10.1016/j.jfluidstructs.2013.02.020 0889-9746 CrossrefGoogle Scholar[8] Gaston Z., Wan H., Dong H. and Ol M., “Analysis of a Hinge-Connected Flapping Plate with an Implemented Torsional Spring Model,” AIAA Paper 2012-0298, 2012. LinkGoogle Scholar[9] Doman D., Oppenheimer M. and Sigthorsson D., “Wingbeat Shape Modulation for Flapping-Wing Micro-Air-Vehicle Control During Hover,” Journal of Guidance, Control, and Dynamics, Vol. 33, No. 3, 2010, pp. 724–739. doi:https://doi.org/10.2514/1.47146 JGCDDT 0162-3192 LinkGoogle Scholar[10] Wood R., “The First Takeoff of a Biologically Inspired At-Scale Robotic Insect,” IEEE Transactions on Robotics, Vol. 24, No. 2, 2007, pp. 341–347. doi:https://doi.org/10.1109/TRO.2008.916997 IRAUEZ 1042-296X CrossrefGoogle Scholar[11] Ol M. V., Bernal L. P., Kang C.-K. and Shyy W., “Shallow and Deep Dynamic Stall for Flapping Low Reynolds Number Airfoils,” Experiments in Fluids, Vol. 46, No. 5, 2009, pp. 883–901. doi:https://doi.org/10.1007/s00348-009-0660-3 EXFLDU 0723-4864 CrossrefGoogle Scholar[12] Chabalko C., Fitzgerald T., Valdez M. and Balachandran B., “Flapping Aerodynamics and Ground Effect,” AIAA Paper 2012-0420, 2012. LinkGoogle Scholar[13] Minier C. S. and Dalton N. N., Physical Properties of Glycerine and it’s Solutions, American Chemical Society Monograph 117, Reinhold, New York, 1953, p. 10. Google Scholar[14] Poelma C., Dickson W. and Dickinson M. H., “Time-Resolved Reconstruction of the Full Velocity Field Around a Dynamically-Scaled Flapping Wing,” Experiments in Fluids, Vol. 41, No. 2, 2006, pp. 213–225. doi:https://doi.org/10.1007/s00348-006-0172-3 EXFLDU 0723-4864 CrossrefGoogle Scholar[15] Dong H., Lian Z. and Harff M., “Optimal Settings of Aerodynamic Performance Parameters in Hovering Flight,” International Journal of Micro Air Vehicles, Vol. 1, No. 3, Sept. 2009, pp. 173–181. doi:https://doi.org/10.1260/175682909789996195 CrossrefGoogle Scholar[16] Bos F. M., van Oudheusden B. and Bijl H., “Wing Performance and 3-D Vortical Structure Formation in Flapping Flight,” Journal of Fluids and Structures, Vol. 42, Oct. 2013, pp. 130–151. doi:https://doi.org/10.1016/j.jfluidstructs.2013.04.002 0889-9746 CrossrefGoogle Scholar Previous article Next article DA - 2014/9// PY - 2014/9// DO - 10.2514/1.j053169 VL - 52 IS - 9 SP - 2083-2086 SN - 1533-385X ER - TY - JOUR TI - Effect of Root Cutout on Force Coefficients of Rotating Wings AU - Schlueter, Kristy L. AU - Jones, Anya R. AU - Granlund, Kenneth AU - Oi, Michael T2 - AIAA JOURNAL AB - No AccessTechnical NoteEffect of Root Cutout on Force Coefficients of Rotating WingsKristy L. Schlueter, Anya R. Jones, Kenneth Granlund and Michael OlKristy L. SchlueterDepartment of Aerospace Engineering, University of Maryland, College Park, Maryland 20742*Graduate Research Assistant, Department of Aerospace Engineering. Student Member AIAA.Search for more papers by this author, Anya R. JonesDepartment of Aerospace Engineering, University of Maryland, College Park, Maryland 20742†Assistant Professor, Department of Aerospace Engineering. Senior Member AIAA.Search for more papers by this author, Kenneth GranlundU.S. Air Force Research Laboratory, Wright–Patterson Air Force Base, Ohio 45433‡Post-Doctoral Scholar, Aerospace Systems Directorate. Senior Member AIAA.Search for more papers by this author and Michael OlU.S. Air Force Research Laboratory, Wright–Patterson Air Force Base, Ohio 45433§Senior Aerospace Engineer, Aerospace Systems Directorate. Associate Fellow AIAA.Search for more papers by this authorPublished Online:6 Jun 2014https://doi.org/10.2514/1.J052821SectionsRead Now ToolsAdd to favoritesDownload citationTrack citations About References [1] Sane S. P., “The Aerodynamics of Insect Flight,” Journal of Experimental Biology, Vol. 206, No. 23, 2003, pp. 4191–4208. doi:https://doi.org/10.1242/jeb.00663 JEBIAM 0022-0949 CrossrefGoogle Scholar[2] Platzer M. F., Jones K. D., Young J. and Lai J. C. S., “Flapping-Wing Aerodynamics: Progress and Challenges,” AIAA Journal, Vol. 46, No. 9, 2008, pp. 2136–2149. doi:https://doi.org/10.2514/1.29263 AIAJAH 0001-1452 LinkGoogle Scholar[3] Shyy W., Aono H., Chimakurthi S. K., Trizila P., Kang C.-K., Cesnik C. E. S. and Liu H., “Recent Progress in Flapping Wing Aerodynamics and Aeroelasticity,” Progress in Aerospace Sciences, Vol. 46, No. 7, 2010, pp. 284–327. doi:https://doi.org/10.1016/j.paerosci.2010.01.001 PAESD6 0376-0421 CrossrefGoogle Scholar[4] Garmann D. J., Visbal M. R. and Orkwis P. D., “Three-Dimensional Flow Structure and Aerodynamic Loading on a Low Aspect Ratio, Revolving Wing,” 42nd AIAA Fluid Dynamics Conference and Exhibit, AIAA Paper 2012-3277, 2012. Google Scholar[5] Dickinson M. H. and Götz K. G., “Unsteady Aerodynamic Performance of Model Wings at Low Reynolds Numbers,” Journal of Experimental Biology, Vol. 174, No. 1, Jan. 1993, pp. 45–64. JEBIAM 0022-0949 CrossrefGoogle Scholar[6] Pitt Ford C. W. and Babinsky H., “Lift and the Leading-Edge Vortex,” Journal of Fluid Mechanics, Vol. 720, April 2013, pp. 280–313. doi:https://doi.org/10.1017/jfm.2013.28 JFLSA7 0022-1120 CrossrefGoogle Scholar[7] Lentink D. and Dickinson M. H., “Rotational Accelerations Stabilize Leading Edge Vortices on Revolving Fly Wings,” Journal of Experimental Biology, Vol. 212, No. 16, Aug. 2009, pp. 2705–2719. doi:https://doi.org/10.1242/jeb.022269 JEBIAM 0022-0949 CrossrefGoogle Scholar[8] Eldredge J. and Wang C., “Improved Low-Order Modeling of a Pitching and Perching Plate,” 41st AIAA Fluid Dynamics Conference and Exhibit, AIAA Paper 2011-3579, 2011. Google Scholar[9] Ramesh K., Gopalarathnam A., Edwards J. R., Ol M. V. and Granlund K., “Theoretical, Computational, and Experimental Studies of a Flat Plate Undergoing High-Amplitude Pitching Motion,” 49th AIAA Aerospace Sciences Meeting and Exhibit, AIAA Paper 2011-217, 2012. LinkGoogle Scholar[10] Jones A. R. and Babinsky H., “Unsteady Lift Generation on Rotating Wings at Low Reynolds Numbers,” Journal of Aircraft, Vol. 47, No. 3, 2010, pp. 1013–1021. doi:https://doi.org/10.2514/1.46649 JAIRAM 0021-8669 LinkGoogle Scholar[11] Jones A. R. and Babinsky H., “Reynolds Number Effects on Leading Edge Vortex Development on a Waving Wing,” Experiments in Fluids, Vol. 51, No. 1, 2011, pp. 197–210. doi:https://doi.org/10.1007/s00348-010-1037-3 EXFLDU 0723-4864 CrossrefGoogle Scholar[12] Kolluru Venkata S. and Jones A. R., “Leading Edge Vortex Structure Over Multiple Revolutions of a Rotating Wing,” Journal of Aircraft, Vol. 50, No. 4, 2013, pp. 1312–1316. doi:https://doi.org/10.2514/1.C032128 JAIRAM 0021-8669 LinkGoogle Scholar[13] Ol M. V., Bernal L., Kang C.-K. and Shyy W., “Shallow and Deep Dynamic Stall for Flapping Low Reynolds Number Airfoils,” Experiments in Fluids, Vol. 46, No. 5, 2009. doi:https://doi.org/10.1007/s00348-009-0660-3 EXFLDU 0723-4864 CrossrefGoogle Scholar[14] Wang C. and Eldredge J., “Low-Order Phenomenological Modeling of Leading-Edge Vortex Formation,” Theoretical and Computational Fluid Dynmaics, Vol. 27, No. 5, Sept. 2013, pp. 1–22. doi:https://doi.org/10.1007/s00162-012-0279-5 Google Scholar Previous article Next article DA - 2014/6// PY - 2014/6// DO - 10.2514/1.j052821 VL - 52 IS - 6 SP - 1322-1325 SN - 1533-385X ER - TY - JOUR TI - Airfoil longitudinal gust response in separated vs. attached flows AU - Granlund, K. AU - Monnier, B. Ol AU - M. AU - Williams, D. T2 - Physics of Fluids (Woodbury, N.Y.) DA - 2014/// PY - 2014/// VL - 26 IS - 027103 ER - TY - JOUR TI - Direct numerical simulation of high-speed transition due to an isolated roughness element AU - Subbareddy, Pramod K. AU - Bartkowicz, Matthew D. AU - Candler, Graham V. T2 - Journal of Fluid Mechanics AB - Abstract We study the transition of a Mach 6 laminar boundary layer due to an isolated cylindrical roughness element using large-scale direct numerical simulations (DNS). Three flow conditions, corresponding to experiments conducted at the Purdue Mach 6 quiet wind tunnel are simulated. Solutions are obtained using a high-order, low-dissipation scheme for the convection terms in the Navier–Stokes equations. The lowest Reynolds number ( $Re$ ) case is steady, whereas the two higher $Re$ cases break down to a quasi-turbulent state. Statistics from the highest $Re$ case show the presence of a wedge of fully developed turbulent flow towards the end of the domain. The simulations do not employ forcing of any kind, apart from the roughness element itself, and the results suggest a self-sustaining mechanism that causes the flow to transition at a sufficiently large Reynolds number. Statistics, including spectra, are compared with available experimental data. Visualizations of the flow explore the dominant and dynamically significant flow structures: the upstream shock system, the horseshoe vortices formed in the upstream separated boundary layer and the shear layer that separates from the top and sides of the cylindrical roughness element. Streamwise and spanwise planes of data were used to perform a dynamic mode decomposition (DMD) (Rowley et al. , J. Fluid Mech. , vol. 641, 2009, pp. 115–127; Schmid, J. Fluid Mech. , vol. 656, 2010, pp. 5–28). DA - 2014/5/9/ PY - 2014/5/9/ DO - 10.1017/JFM.2014.204 VL - 748 SP - 848-878 J2 - J. Fluid Mech. LA - en OP - SN - 0022-1120 1469-7645 UR - http://dx.doi.org/10.1017/JFM.2014.204 DB - Crossref KW - compressible boundary layers KW - instability KW - transition to turbulence ER - TY - CONF TI - A general framework of hybrid graph sampling for complex network analysis AU - Xu, X. AU - Lee, C. H. AU - Eun, D. Y. AB - Being able to capture the properties of massive real graphs and also greatly reduce data scale and processing complexity, graph sampling techniques provide an efficient tool for complex network analysis. Random walk-based sampling has become popular to obtain asymptotically uniform samples in the recent literature. However, it produces highly correlated samples and often leads to poor estimation accuracy in sampling large networks. Another widely-used approach is to launch random jump by querying randomly generated user/node ID, but also has the drawback of unexpected cost when the ID space is sparsely populated. In this paper, we develop a hybrid graph sampling framework that inherits the benefit of returning immediate samples from random walk-based crawling, while incorporating the advantage of reducing the correlation in the obtained samples from random jump. We aim to strike the right balance between random jump and crawling by analyzing the resulting asymptotic variance of an estimator of any graph nodal property, in order to give guidelines on the design of better graph sampling methods. We also provide simulation results on real network (graph) to confirm our theoretical findings. C2 - 2014/// C3 - 2014 proceedings ieee infocom DA - 2014/// DO - 10.1109/infocom.2014.6848229 SP - 2795-2803 ER - TY - CONF TI - Tissue- and cell-level stress distributions of the heart valve tissue during diastole AU - Huang, S. Y. AU - Huang, H. Y. S. C2 - 2014/// C3 - Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2013, vol 9 DA - 2014/// ER - TY - CONF TI - Modeling prion transport in a tunneling nanotube AU - Kuznetsov, I. A. AU - Kuznetsov, A. V. AB - We develop a model for simulating prion transport in a tunneling nanotube (TNT). We simulate the situation when two cells, one of which is infected, are connected by a TNT. We consider two mechanisms of prion transport: lateral diffusion in the TNT membrane and active actin-dependent transport inside endocytic vesicles. Endocytic vesicles are propelled by myosin Va molecular motors. Since the transit time of prions through a TNT is short (several minutes), the two population model developed here assumes that there is no interchange between the two prion populations, and that partitioning between the prion populations is decided by prion loading at the TNT entrance. The split between the two prion populations at the TNT entrance is decided by the degree of loading, which indicates the portion of prions that enter a TNT in endocytic vesicles. An analytical solution describing prion concentrations and fluxes is obtained. C2 - 2014/// C3 - Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2013, vol 3B DA - 2014/// DO - 10.1115/imece2013-62461 ER - TY - CONF TI - Modeling of tau protein transport in axons AU - Kuznetsov, I. A. AU - Kuznetsov, A. V. AB - This paper develops a simplified analytical solution for the slow axonal transport of tau proteins. A six kinetic state model developed in Jung and Brown [1] was used to simulate transport of tau. The model was extended by accounting for tau degradation and diffusion in the off-track kinetic states. The analytical solution was obtained by assuming that transitions between anterograde and retrograde states are infrequent. This assumption was validated through an analysis of the sensitivity of the solution to changes in the values of the two kinetic constants that describe the transition rates between the anterograde and retrograde states, and by a comparison with the experimentally measured tau distributions reported in Konzack et al. [2]. The predicted average transport velocity of tau was also in the experimentally reported range. C2 - 2014/// C3 - Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2013, vol 3B DA - 2014/// DO - 10.1115/imece2013-62430 ER - TY - CONF TI - Modeling leftward flow in the embryonic node AU - Kuznetsov, A. V. AU - Blinov, D. G. AU - Avramenko, A. A. AU - Shevchuk, I. V. AU - Tyrinov, A. I. AU - Kuznetsov, I. A. AB - The establishment of the left-right asymmetry during the development of vertebrates is a fascinating phenomenon that is still not fully understood. Extensive research suggests that in mice a small triangular cavity, called the ventral node, is responsible for breaking the left-right symmetry. A mouse node is ∼ 50 microns across and ∼10 microns deep. The surface of the nodal pit is covered by 200–300 monocilia whose rotation is responsible for the leftward flow in the node. We developed a simplified method of modeling the extraembryonic fluid flow and morphogen transport in a nodal cavity. We simplified the problem as flow in a 2D cavity; the effect of rotating cilia was modeled by specifying a constant vorticity at the edge of the ciliated layer. We also developed approximate solutions for morphogen transport in the nodal pit. The solutions were obtained utilizing the proper generalized decomposition method. We compared our approximate solutions with the results of numerical simulation of flow caused by the rotation of 81 cilia, and obtained reasonable agreement in most of the flow domain. We discuss locations where agreement is less accurate. The obtained semi-analytical solutions enable a quick analysis of flow and morphogen distribution in a nodal pit. C2 - 2014/// C3 - Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2013, vol 7B DA - 2014/// DO - 10.1115/imece2013-62503 ER - TY - CONF TI - Investigation of enhancement in pool boiling heat transfer of a binary temperature sensitive magnetic fluid AU - Karimi-Moghaddam, G. AU - Gould, R. D. AU - Bhattacharya, S. AB - In this paper, the performance of pool boiling heat transfer using a binary temperature sensitive magnetic fluid in the presence of a non-uniform magnetic field is investigated numerically. By using a binary magnetic fluid, enhanced boiling heat transfer is obtained by thermomagnetic convection without deterioration of properties of the fluid. This work is aimed at gaining a qualitative understanding the magnetic field effects on boiling heat transfer enhancement of magnetic fluids. In order to accomplish this, the boiling process and the effects of position of the external magnetic field on flow pattern and heat transfer are investigated in a 2D rectangular domain using COMSOL Multiphysics simulation software. Finally, the boiling curves for a binary temperature sensitive magnetic fluid and its base fluid (without magnetic particles) are compared for various applied heat flux magnitudes. C2 - 2014/// C3 - Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2013, vol 8b DA - 2014/// DO - 10.1115/imece2013-66308 ER - TY - CONF TI - Exploring lithium-ion intensity and distribution via a time-of-flight secondary ion mass spectroscopy AU - ChiuHuang, C. K. AU - Zhou, C. Z. AU - Huang, H. Y. S. C2 - 2014/// C3 - Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2013, vol 10 DA - 2014/// ER - TY - CONF TI - Experimental observations of nitrogen diluted ethylene and methane jet flames AU - Hutchins, A. R. AU - Kribs, J. D. AU - Muncey, R. D. AU - Reach, W. A. AU - Lyons, K. M. C2 - 2014/// C3 - Proceedings of the ASME Summer Heat Transfer Conference - 2013, vol 2 DA - 2014/// ER - TY - CONF TI - Enhancement of tribological performance via innovative tooling design for extrusion processes AU - Lowrie, J. B. AU - Ngaile, G. AB - Due to the expense and negative environmental impact of commonly used conversion coating type lubricants a new method for reducing the friction in the extrusion process is desired. This paper investigates the possibility of modifying the die set to better the tribological conditions and reduce friction in the extrusion process. A novel design of extrusion tooling is proposed, in which the die set is segmented into three separate pieces, a punch, a wall die, and a bottom die. Additionally, the wall die is given the freedom to move along the axis of the punch and a high pressure lubricant is supplied to the interface between the wall and bottom dies. Preliminary tests of the segmented tooling show that, if the tribological conditions are severe enough, the forming load will decrease in comparison to a conventional extrusion system. C2 - 2014/// C3 - Proceedings of the ASME 9th International Manufacturing Science and Engineering Conference, 2014, vol 2 DA - 2014/// DO - 10.1115/msec2014-4170 ER - TY - CONF TI - DDPM-DEM simulations of particulate flows in human tracheobronchial airways AU - Feng, Y. AU - Kleinstreuer, C. AB - Dense particle-suspension flows in which particle-particle interactions are a dominant feature encompass a diverse range of industrial and geophysical contexts, e.g., slurry pipeline, fluidized beds, debris flows, sediment transport, etc. The one-way dispersed phase model (DPM), i.e., the conventional one-way coupling Euler-Lagrange method is not suitable for dense fluid-particle flows [1]. The reason is that such commercial CFD-software does not consider the contact between the fluid, particles and wall surfaces with respect to particle inertia and material properties. Hence, two-way coupling of the Dense Dispersed Phase Model (DDPM) combined with the Discrete Element Method (DEM) has been introduced into the commercial CFD software via in-house codes. As a result, more comprehensive and robust computational models based on the DDPM-DEM method have been developed, which can accurately predict the dynamics of dense particle suspensions. Focusing on the interaction forces between particles and the combination of discrete and continuum phases, inhaled aerosol transport and deposition in the idealized tracheobronchial airways [2] was simulated and analyzed, generating more physical insight. In addition, it allows for comparisons between different numerical methods, i.e., the classical one-way Euler-Lagrange method, two-way Euler-Lagrange method, EL-ER method [3], and the present DDPM-DEM method, considering micron- and nano-particle transport and deposition in human lungs. C2 - 2014/// C3 - Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2013, vol 3B DA - 2014/// DO - 10.1115/imece2013-62307 ER - TY - CONF TI - Comparison of representative interactive flamelet and detailed chemistry based combustion models for internal combustion engines AU - Wang, M. AU - Raju, M. AU - Pomraning, E. AU - Kundu, P. AU - Pei, Y. AU - Som, S. C2 - 2014/// C3 - Proceedings of the ASME Internal Combustion Engine Division, Fall Technical Conference, 2014, vol 2 DA - 2014/// ER - TY - CONF TI - Acoustic wave microsensor array for tactile sensing AU - Kim, K. AU - Jiang, X. N. AB - Tactile perception is a critical requirement for surgery procedures such as minimally invasive surgery (MIS). In this study, an acoustic wave tactile sensor array for force and shear modulus sensing was investigated. This device can sense the magnitude of the applied force change and the tissue’s shear modulus change by means of detecting an electrical impedance change. The 6×6 array with a pitch of 1.3 mm was fabricated using a face-shear mode PMN-PT piezoelectric resonator which is highly sensitive to acoustic impedance load. External forces (0–5 N) were applied to the sensor and the electric impedance shift was measured. The sensitivity was found to be 56.87 Ohm/N. Imaging test results for different force and load stiffnesses were also obtained. The proposed tactile sensing technique is also favorable for a number of other biomedical applications including haptic sensors for the robotic surgery and artificial skin or fingers. C2 - 2014/// C3 - Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2013, vol 3B DA - 2014/// DO - 10.1115/imece2013-66098 ER - TY - CONF TI - A non-dimensional analysis to characterize thermomagnetic convection of a temperature sensitive magnetic fluid in a flow loop AU - Karimi-Moghaddam, G. AU - Gould, R. D. AU - Bhattacharya, S. AB - This paper presents results from theoretical and numerical studies of a single-phase, temperature sensitive magnetic fluid operating under steady-state laminar flow conditions in a partially heated thermomagnetic circulation loop under the influence of an external magnetic field (created by a solenoid). A one-dimensional theoretical model has been developed using scaling arguments to characterize thermomagnetic circulation in this loop in terms of the geometric length scales, magnetic fluid properties, and strength of the imposed magnetic field. In parallel to this theoretical analysis, supporting numerical simulations using COMSOL Multiphysics simulation software have been undertaken to obtain data for use in this 1D model. A correlation for the non-dimensional heat transfer (Nusselt number) as a function of the appropriate magnetic Rayleigh number and a correlation for the mass flow rate based on the system’s properties are developed. C2 - 2014/// C3 - Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2013, vol 8b DA - 2014/// DO - 10.1115/imece2013-66313 ER - TY - CONF TI - A biomechanical study of directional mechanical properties of porcine skin tissues AU - Huang, H. Y. S. AU - Huang, S. Y. AU - Gettys, T. AU - Prim, P. M. AU - Harrysson, O. L. C2 - 2014/// C3 - Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2013, vol 9 DA - 2014/// ER - TY - CONF TI - Using a goal-switching selection operator in multi-objective genetic algorithm optimization problems AU - Shaefer, D. AU - Ferguson, S. AB - This paper demonstrates how solution quality for multiobjective optimization problems can be improved by altering the selection phase of a multiobjective genetic algorithm. Rather than the traditional roulette selection used in algorithms like NSGA-II, this paper adds a goal switching technique to the selection operator. Goal switching in this context represents the rotation of the selection operator among a problem’s various objective functions to increase search diversity. This rotation can be specified over a set period of generations, evaluations, CPU time, or other factors defined by the designer. This technique is tested using a set period of generations before switching occurs, with only one objective considered at a time. Two test cases are explored, the first as identified in the Congress on Evolutionary Computation (CEC) 2009 special session and the second a case study concerning the market-driven design of a MP3 player product line. These problems were chosen because the first test case’s Pareto frontier is continuous and concave while being relatively easy to find. The second Pareto frontier is more difficult to obtain and the problem’s design space is significantly more complex. Selection operators of roulette and roulette with goal switching were tested with 3 to 7 design variables for the CEC 09 problem, and 81 design variables for the MP3 player problem. Results show that goal switching improves the number of Pareto frontier points found and can also lead to improvements in hypervolume and/or mean time to convergence. C2 - 2014/// C3 - Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, 2013, vol 3B DA - 2014/// DO - 10.1115/detc2013-13199 ER - TY - CONF TI - A concept selection framework for early sorting of reconfigurable system designs AU - Denhart, J. AU - Gemmer, T. AU - Ferguson, S. AU - Mazzoleni, A. AB - A seven-step framework for sorting proposed concepts of system changes / reconfigurations is presented that seeks to characterize the overall ramifications on system architecture. This framework is intended for use immediately following a concept generation phase. The framework uses three simple questions: “What level of the system design does this concept apply to?” “What levels of the system design does the concept impact?” and “What is the severity of this impact?” A flowchart leads the designer through these questions and assigns each concept a classification from one to five based on the answers. Class one concepts have little to no impact on the rest of the system architecture. They can be included with little fear of massive change propagation and system redesign. Class five concepts carry large changes to system architecture and therefore should be included only if they can be shown to be highly beneficial, or if there remains enough design freedom such that the cost of changing the system architecture is minimal. Meanwhile, class five concepts are likely to have much higher potential to create revolutionary design. A case study is used to demonstrate the application of the sorting framework in the context of a Mars rover mission. Several example concepts are provided to illustrate key insights from the case study. Convergence of the framework is explored by comparing the authors’ results to a second test done by a new design team. C2 - 2014/// C3 - Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, 2013, vol 3B DA - 2014/// DO - 10.1115/detc2013-13222 ER - TY - CONF TI - Enhanced targeted initial populations for multiobjective product line optimization AU - Foster, G. AU - Ferguson, S. AB - Initial populations for genetic algorithms are often created using randomly generated designs in an effort to maximize the genetic diversity in the design space. However, research indicates that the inclusion of solutions generated based on domain knowledge (i.e. non-random solutions) can notably improve the performance of the genetic algorithm with respect to solution performance and/or computational cost for convergence. This performance increase is extremely valuable for computationally expensive problems, such as product line optimization. In prior research, the authors demonstrated these improvements for product line design problems where market share of preference was the performance objective. Initial product line solutions were constructed from products that had the largest product-level utility for individual respondents. However, this simple product identification strategy did not adequately scale to accommodate the richer design problem associated with multiple objectives. This paper extends the creation of targeted initial populations to multiobjective product line design problems by using the objectives of the problem, instead of product level utility, to identify candidate designs. A MP3 player and vehicle feature packaging product line design problems are used to demonstrate this approach and assess the improvement of this modification. C2 - 2014/// C3 - Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, 2013, vol 3A DA - 2014/// DO - 10.1115/detc2013-13303 ER - TY - CONF TI - Effects of feedback on design space exploration AU - Foster, G. AU - Denhart, J. AU - Ferguson, S. AB - The ultimate goal of this research is to provide computer based educational software that exposes engineering students to design tradeoffs early in their undergraduate experience. This paper investigates two feedback elements for their ability to enhance those students’ understanding of the tradeoffs inherent in a water rocket propulsion design problem: 1) a Latin hypercube sample that allows the student to select a starting point and 2) sensitivity values that displayed local gradient information. Assessments are made using data logged during the students’ interaction with the software and a series of quizzes performed throughout the study. The results indicate that the sensitivity information improves the students’ ability to locate designs with good performance, while the Latin hypercube adversely affects the students’ ability to visualize the objective space. C2 - 2014/// C3 - Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, 2013, vol 1 DA - 2014/// DO - 10.1115/detc2013-13243 ER - TY - CONF TI - Design of a compliant flexure joint for use in a flow energy harvester AU - Chatterjee, P. AU - Bryant, M. AB - This paper presents an initial experimental and computational investigation of a flow-induced vibration energy harvester with a compliant flexure mechanism. This energy harvester utilizes the aeroelastic flutter phenomenon to convert the flow energy to vibrational energy which can be converted into useful electrical power using piezoelectric transducers. However, unlike previous flutter-based flow energy harvesters [1] which require assembling multiple components to create the necessary aeroelastic arrangement, the device described here utilizes a monolithic, compact design to achieve the same. In this paper, we propose a flexure design for this device and model it using analytic methods and finite element simulations. A proof of concept energy harvester incorporating this flexure design has been fabricated and experimentally investigated in wind tunnel testing. C2 - 2014/// C3 - Proceedings of the ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems, 2014, vol 2 DA - 2014/// DO - 10.1115/smasis2014-7503 ER - TY - CONF TI - Novel wearable EMG sensors based on nanowire technology AU - Mills, Amanda AU - Du, L. AU - Huang, H. AU - Zhu, Y. AB - Wearable electrodes made of silver nanowires (AgNWs) have demonstrated great potential for sensing a variety of physical and physiological signals. This paper aimed to study the feasibility of AgNWs electrodes for measuring surface electromyographic (sEMG) signals. One human subject was recruited and instructed to perform wrist extension repetitively or to produce no movement in the experiment. sEMG signals were collected from the right extensor digitorum communis of the human subject by an AgNWs electrode and a commercially available Ag/AgCl wet sEMG electrode, separately. The quality of recorded sEMG in time and frequency domains was compared between the two types of electrodes. The results showed that the sEMG signals recorded by the AgNW electrode were comparable with that by the Ag/AgCl electrode. Since the dry AgNWs electrodes are flexible, wearable, and potentially robust for daily use, novel AgNW-based EMG electrodes are promising for many biomedical applications, such as myoelectric control of artificial limbs. C2 - 2014/// C3 - 2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2014 DA - 2014/// DO - 10.1109/embc.2014.6943928 SP - 1674-1677 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84929492543&partnerID=MN8TOARS ER - TY - JOUR TI - Thrombolysis enhanced by dual-frequency high-intensity focused ultrasound AU - Guo, Sijia AU - Suo, Dingjie AU - Jing, Yun AU - Jiang, Xiaoning AU - Frank, Jonathan AU - Lin, Weili T2 - 2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS) AB - It has been demonstrated that high-intensity focused ultrasound can be an efficient method to induce thrombolysis. Excessive thermal effect on neighboring tissue is however a concern. The goal of this work is to test the efficacy of dual-frequency ultrasound-induced thrombolysis, with the aim to reduce the acoustic power required to achieve the same lysis rate (mass loss of blood clots over time) as single-frequency ultrasound. In vitro clots of mouse blood were prepared and placed at the focus of two piezoelectric ultrasound transducers (center frequencies were 0.95 MHz and 1.5 MHz, respectively). 0.65 W ultrasound waves with 10% duty cycle were employed in both single- and dual-frequency ultrasound exposures. The mass losses of the clots were recorded to obtain the lysis rate after each test. It was found that dual-frequency results in more efficient thrombolysis. Cavitation bubble modeling was also conducted for both single- and dual-frequency ultrasound to explain the experimental founding. DA - 2014/// PY - 2014/// DO - 10.1109/ultsym.2014.0541 SP - 2173-2176 SN - 1948-5719 KW - dual-frequency ultrasound KW - thrombolysis KW - cavitation KW - high-intensity focused ultrasound (HIFU) ER - TY - JOUR TI - Dual Frequency Transducers for Intravascular Ultrasound Super-harmonic Imaging and Acoustic Angiography AU - Ma, Jianguo AU - Jiang, Xiaoning AU - Martin, Karl H. AU - Dayton, Paul A. AU - Li, Yang AU - Zhou, Qifa T2 - 2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS) AB - Imaging of coronary vasa vasorum may lead to assessment of the vulnerable plaque development in diagnosis of atherosclerosis diseases. Intravascular ultrasound (IVUS) imaging transducers capable of detecting microvessels via nonlinear contrast imaging could provide valuable diagnostic information, however such transducers are not yet produced commercially. Dual-frequency transducers capable of detection of microbubble super-harmonics have shown promise as a new contrast-enhanced IVUS (CE-IVUS) platform. Contrast-to-tissue ratio (CTR) in CE-IVUS imaging can be closely associated with the low frequency transmitter performance. In this paper, multiple dual frequency IVUS transducers with different transmission frequencies (6.5 and 5 MHz) and different materials (PMN-PT single crystals and 1-3 composite) were developed and evaluated. All transducer structures were constructed with the 30 MHz high frequency reception element in front of the low frequency transmission element. Super-harmonic imaging was carried out using a tissue mimicking phantom. With similar peak negative pressures, the lower transmission frequency transducers generated higher CTR (23 dB for 5 MHz transmission). With similar input excitations, the PMN-PT 1-3 composite produced higher resolution (70 μm for 1-cycle burst excitation) than single crystal ones (> 150 μm). Dual frequency transducers with 5 MHz transmitters made of PMN-PT 1-3 composite are preferable in the CE-IVUS imaging. DA - 2014/// PY - 2014/// DO - 10.1109/ultsym.2014.0166 SP - 675-678 SN - 1948-5719 KW - ultrasound transducers KW - dual frequency transducer KW - intravascular ultrasound KW - contrast super-harmonic imaging KW - acoustic angiography ER - TY - JOUR TI - Development of Transmitters in Dual-Frequency Transducers for Interventional Contrast Enhanced Imaging and Acoustic Angiography AU - Kim, Jinwook AU - Li, Sibo AU - Jiang, Xiaoning AU - Kasoji, Sandeep AU - Dayton, Paul A. T2 - 2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS) AB - Spatial limitation can be a challenge to interventional ultrasound transducers for dual-frequency contrast-enhanced ultrasound imaging, or acoustic angiography. A low frequency (<; 3 MHz) transmission with moderate peak negative pressure (PNP) and short pulse length is not easily attainable within limited dimensions. In this paper, a new design of the low frequency transmitter of dual-frequency transducers is presented. 1-3 composites for interventional transmitter design were analyzed by the Krimholtz-Leedom-Matthaei (KLM) model and finite element analysis (FEA). The dual frequency transducer prototype with a 2 MHz 1-3 composite transmitter and a 14 MHz receiver was fabricated and characterized, followed by microbubble detection tests. The transmitter showed the peak negative pressure (PNP) of -1.5 MPa. The -6 dB pulse echo fractional bandwidth for the transmitter and receiver were 61 % and 45 %, respectively. The prototyped dual frequency transducer was used to successfully excite microbubbles and to detect super harmonic responses from microbubbles. The measured harmonic signal showed a 12 dB contrast-to-noise ratio (CNR). DA - 2014/// PY - 2014/// DO - 10.1109/ultsym.2014.0167 SP - 679-682 SN - 1948-5719 KW - interventional ultrasound KW - contrast enhanced imaging KW - dual frequency transducers KW - super-harmonic imaging ER - TY - JOUR TI - Development of Dual-layer Micromachined Composite Transducers for Broadband Ultrasound Imaging AU - Li, Sibo AU - Jiang, Xiaoning AU - Tian, Jian AU - Han, Pengdi T2 - 2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS) AB - We presented in this paper the development of micromachined 1-3 composite dual layer transducers for multifrequency imaging. The effective electromechanical coupling coefficient and acoustic impedance of the micromachined PMN-PT 1-3 composite material was measured to be 0.73 and 18 MRayl, respectively. Based on the material, a dual-layer transducer prototype was developed. The probe was operated at both 15 MHz and 48 MHz. To characterize the transducer, pulse echo test was conducted, achieved a 73% and 70% bandwidth at low and high resonance, respectively. At fundamental mode, it showed transmitting sensitivity of 26 KPa/V, These results suggested great potential for medical broadband imaging applications. DA - 2014/// PY - 2014/// DO - 10.1109/ultsym.2014.0164 SP - 667-670 SN - 1948-5719 KW - tissue harmonic imaging KW - 1-3 composite KW - duallayer transducer KW - broadband ultrasound ER - TY - CONF TI - Design and phantom testing of a bi-frequency co-linear array AU - Wang, Z. C. AU - Li, S. B. AU - Jiang, X. N. AU - Liu, R. B. AU - Geng, X. C. C2 - 2014/// C3 - 2014 IEEE International Ultrasonics Symposium (IUS) DA - 2014/// SP - 2108-2111 ER - TY - CONF TI - Analytical and numerical modeling of thick tube hydroforging AU - Alzahrani, B. AU - Ngaile, G. C2 - 2014/// C3 - 11th international conference on technology of plasticity, ictp 2014 DA - 2014/// VL - 81 SP - 2223-2229 ER - TY - JOUR TI - An array transmitter for dual-frequency contrast enhanced intravascular ultrasound imaging AU - Wang, Zhuochen AU - Ma, Jianguo AU - Jiang, Xiaoning AU - Martin, Karl Heath AU - Dayton, Paul A. T2 - 2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS) AB - Recent studies suggests that contrast ultrasound for molecular imaging or vasa vasorum (VV) assessment may be promising in identification of vulnerable plaques. However, conventional intravascular ultrasound (IVUS) transducers with frequency of 15 MHz – 60 MHz are not optimized for imaging with micro bubble contrast agents due to the ineffective micro bubble excitation at high frequencies and poor signal separation from tissue. This paper presents design and fabrication of a lateral mode transducer array with center frequency of 2 MHz for contrast enhanced IVUS (CE-IVUS) imaging, which can generate sufficient pressure to excite microbubbles more effectively and therefore could be used for dual-frequency microbubble superharmonic imaging, or ‘acoustic angiography’. Several commercial transducers with central frequency of 15 MHz, 20 MHz and 25 MHz were used as receivers to receive the contrast signal. In the contrast testing, the high frequency echo of the nonlinear response from microbubbles in a micro-tube with diameter of 0.2 mm was detected. The maximum contrast to noise ratio was 12.2 dB. The results show that superharmonic signals (over 9 th harmonic) can be received; suggesting good resolution and signal separation in contrast enhanced IVUS imaging. DA - 2014/// PY - 2014/// DO - 10.1109/ultsym.2014.0524 SP - 2104-2107 SN - 1948-5719 KW - contrast ultrasound KW - transmitting array transducer KW - angiography lateral mode transducer KW - superharmonic KW - acoustic angiography ER - TY - JOUR TI - Acoustic radiation force (ARF) generation with a novel dual-frequency intravascular transducer. AU - Czernuszcwicz, Tomasz J. AU - Gallippi, Caterina M. AU - Wang, Zhuochen AU - Ma, Jianguo AU - Jiang, Xiaoning T2 - 2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS) AB - Atherosclerosis and coronary artery disease remain the leading cause of death in the US. Coronary plaque is visualized with intravascular ultrasound (IVUS) and is typically implemented with high center frequencies (>20 MHz) for superior spatial resolution. Coronary plaque characterization may be improved by implementing elasticity imaging techniques such as acoustic radiation force impulse (ARFI) imaging using IVUS transducers. In this work we propose to extend ARFI imaging to a novel, dual-frequency small-aperture transducer design that includes a low-frequency “pushing” element and a high-frequency “tracking” element. A 40 MHz element (0.6 mm × 0.6 mm) was integrated onto a 5 MHz element (0.6 mm × 3 mm). Both elements of the transducer were fabricated from single crystal PMN-PT and the whole transducer was mounted on a 20 gauge needle tip. ARF-induced motion from the low-frequency element was quantified using optical tracking methods in a translucent phantom (∼8 kPa) containing embedded graphite microparticles. Displacements induced by ARF excitations with 300, 600, 900, and 1200 cycles (5 MHz, 190 V) were captured and compared to baseline. Median (inter-quartile range) peak displacements for 300, 600, 900, and 1200 cycles were 0.33 (0.27 – 0.39) µm, 0.72 (0.62 – 0.87) µm, 1.1 (1.0 – 1.3) µm, and 1.6 (1.43 – 1.75) µm, respectively. In another phantom, 40 MHz pulse/echo RF lines were captured to demonstrate backscatter sensitivity. The results of this study show that ARF generation and high-resolution tracking is feasible on a small-aperture transducer fit for IVUS implementation. DA - 2014/// PY - 2014/// DO - 10.1109/ultsym.2014.0569 SP - 2284-2287 SN - 1948-5719 KW - ultrasound transducer KW - dual frequency KW - acoustic radiation force KW - ARFI KW - intravascular KW - IVUS ER - TY - JOUR TI - A Wave-Vector-Frequency-Domain Method for Linear/nonlinear Wave Modeling in Heterogeneous Media AU - Jing, Yun T2 - 2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS) AB - In this paper, we will present a modified wave-vector-frequency-domain method for predicting linear/nonlinear wave propagation in arbitrarily heterogeneous media. The Westervelt equation for heterogeneous media will be transformed into the wave-vector-frequency-domain. An implicit analytic solution based on the Green's function will be shown and can be solved by a previously developed stepping algorithm. Numerical results are compared with those of the k-space method which shows good agreement. DA - 2014/// PY - 2014/// DO - 10.1109/ultsym.2014.0038 SP - 150-153 SN - 1948-5719 KW - wave-vector-frequency-domain KW - nonlinear wave KW - heterogeneous media ER - TY - JOUR TI - A Configurable Dual-Frequency Transmit/Receive System for Acoustic Angiography Imaging AU - Li, Yang AU - Ma, Jianguo AU - Martin, K. Heath AU - Choi, Hojong AU - Dayton, Paul A. AU - Jiang, Xiaoning AU - Shung, K. Kirk AU - Zhou, Qifa T2 - 2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS) AB - Acoustic angiography is a high-resolution imaging modality for small vascular structure. It utilizes the nonlinear backscatter of microbubble contrast agents (MCAs) to delineate blood vessels. In acoustic angiography, where MCAs are insonified with high rarefractional pressures at resonance frequency (6.5MHz), high-order harmonics (30 MHz) become more evident and can be utilized to produce high-resolution images for detecting small vascular structures. We developed a configurable dual-frequency system platform dedicated to acoustic angiography. The system consists of pulse generation, data acquisition and signal processing blocks. It is controlled by a field programmable gate array (FPGA), which enables flexible programming, and many on-board processing and stimulation modes. The system was shown to be capable of acoustic angiography as well as traditional B-mode imaging. DA - 2014/// PY - 2014/// DO - 10.1109/ultsym.2014.0180 SP - 731-733 SN - 1948-5719 KW - contrast imaging KW - FPGA KW - configurable system KW - acoustic angiography ER - TY - CONF TI - Dynamic output feedback controller design for T-S fuzzy plants with actuator saturation using linear fractional transformation AU - Liu, Y. AU - Ban, X. J. AU - Wu, F. AU - Lam, H. K. AB - In this paper, a systematic synthesis method for Takagi-Sugeno fuzzy dynamic output feedback controller is proposed for T-S fuzzy plants with actuator saturation. By using the deadzone function, both the T-S fuzzy plant with actuator saturation and the T-S fuzzy dynamic output feedback controller are transformed into the form of linear fractional transformation (LFT). Within the framework of LFT, the issue of stability as well as Hoo performance is cast as a convex optimization problem which can be approached by solving a set of linear matrix inequalities. A numerical example is presented to illustrate the effectiveness of the proposed method. C2 - 2014/// C3 - 2014 ieee international conference on fuzzy systems (fuzz-ieee) DA - 2014/// DO - 10.1109/fuzz-ieee.2014.6891617 SP - 2125-2132 ER - TY - CONF TI - Piezoelectric actuators with active and passive frames AU - Tolliver, L. AU - Jiang, X. N. AU - Xu, T. B. AB - Electromechanical actuators that generate large displacements, have large load capabilities, and demonstrate strong resonance characteristics are in great demand in the areas of precision positioning, active vibration control, and energy harvesting. Piezoelectric materials have been widely investigated for these applications because of their high energy density, quick response time, and relatively low driving voltages, but they demonstrate very small strain, typically about 0.1%. We present experimental and finite element results for two designs that use active and passive frames, respectively, to enhance the small strain in piezoelectric multilayer stacks. The first design, stacked-HYBATS, employs the synergetic contribution of d33 and d31 mode piezoelectric material. Finite element results show that this structure can generate over 50 microns of displacement and nearly 40 N of blocking force in a 36 mm × 22 mm × 10 mm footprint. The second design employs frames made from passive materials to form two stages of strain amplification in a 42 mm × 30 mm × 20 mm footprint. This two-stage design can produce over 600 microns of displacement and has a blocking force of 27 N. The active and passive materials of both designs can be varied to maximize displacement and/or blocking force. The stacked-HYBATS and the two-stage amplification system display favorable force-displacement capabilities and are promising for a variety of manufacturing and space technology applications. C2 - 2014/// C3 - Proceedings of the ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems - 2013, vol 1 DA - 2014/// DO - 10.1115/smasis2013-3064 ER - TY - CONF TI - Fiber bragg gratings for heat flux measurements in thermal protection systems under a steady conductive thermal load AU - Hackney, D. A. AU - Peters, K. J. AU - Black, R. J. AU - Costa, J. M. AU - Moslehi, B. AU - Zarnescu, L. C2 - 2014/// C3 - Proceedings of the ASME Conference on Smart Materials Adaptive Structures and Intelligent Systems - 2013, vol 2 DA - 2014/// ER - TY - JOUR TI - Fabrication and measurement of a flexoelectric micro-pyramid composite AU - Huang, Wenbin AU - Shu, Longlong AU - Kwon, Seol Ryung AU - Zhang, Shujun AU - Yuan, Fuh-Gwo AU - Jiang, Xiaoning T2 - AIP ADVANCES AB - A fabrication method by combining precision mechanical dicing and wet etching was developed to prepare micro-pyramid structures based on (Ba0.67Sr0.33)TiO3 ceramics. The effective piezoelectric properties of flexoelectric pyramid structures in ten micrometers scale were investigated and measured through converse flexoelectric effect. The scaling effect of the flexoelectric response was demonstrated as the structure size shrinks down. The results do suggest the great potential of flexoelectric micro pyramids as an alternative to lead-free piezoelectric material. DA - 2014/12// PY - 2014/12// DO - 10.1063/1.4904024 VL - 4 IS - 12 SP - SN - 2158-3226 ER - TY - JOUR TI - Analysis, Fabrication, and Testing of a Liquid Piston Compressor Prototype for an Ocean Compressed Air Energy Storage (OCAES) System AU - Park, J. AU - Ro, P. AU - He, X. AU - Mazzoleni, A. T2 - Marine Technology Society Journal AB - Abstract Previous work concerning ocean compressed air energy storage (OCAES) systems has revealed the need for an efficient means for compressing air that minimizes the energy lost to heat during the compression process. In this paper, we present analysis, simulation, and testing of a tabletop proof-of-concept experiment of a liquid piston compression system coupled with a simulated OCAES system, with special attention given to heat transfer issues. An experimental model of a liquid piston system was built and tested with two different materials, polycarbonate and aluminum alloy, used for the compression chamber. This tabletop liquid piston system was tested in conjunction with a simulated OCAES system, which consisted of a hydrostatic tank connected to a compressed-air source from the wall to mimic the constant hydrostatic pressure at ocean depth experienced by the air stored in an actual OCAES system. Good agreement was found between the experimental and numerical studies and demonstrated that the heat transfer characteristics of a liquid piston compression process are effective in reducing the increase in air temperature that occurs during the compression process. The results also suggest that it may be possible to achieve a near-isothermal process with a fully optimized liquid piston compression system. DA - 2014/// PY - 2014/// DO - 10.4031/mtsj.48.6.3 VL - 48 IS - 6 SP - 86-97 SN - 1948-1209 KW - ocean-based energy KW - compressed air KW - energy storage KW - liquid piston KW - isothermal ER - TY - JOUR TI - Surface-Energy-Assisted Perfect Transfer of Centimeter-Scale Mono layer and Few-Layer MoS2 Films onto Arbitrary Substrates AU - Gurarslan, Alper AU - Yu, Yifei AU - Su, Liqin AU - Yu, Yiling AU - Suarez, Francisco AU - Yao, Shanshan AU - Zhu, Yong AU - Ozturk, Mehmet AU - Zhang, Yong AU - Cao, Linyou T2 - ACS NANO AB - The transfer of synthesized 2D MoS2 films is important for fundamental and applied research. However, it is problematic to translate the well-established transfer processes for graphene to MoS2 due to different growth mechanisms and surface properties. Here we demonstrate a surface-energy-assisted process that can perfectly transfer centimeter-scale monolayer and few-layer MoS2 films from original growth substrates onto arbitrary substrates with no observable wrinkles, cracks, and polymer residues. The unique strategies used in this process include leveraging the penetration of water between hydrophobic MoS2 films and hydrophilic growth substrates to lift off the films and dry transferring the film after the lift off. This is in stark contrast with the previous transfer process for synthesized MoS2 films, which explores the etching of the growth substrate by hot base solutions to lift off the films. Our transfer process can effectively eliminate the mechanical force caused by bubble generations, the attacks from chemical etchants, and the capillary force induced when transferring the film outside solutions as in the previous transfer process, which consists of the major causes for the previous unsatisfactory transfer. Our transfer process also benefits from using polystyrene (PS), instead of poly(methyl methacrylate) (PMMA) that was widely used previously, as the carrier polymer. PS can form more intimate interaction with MoS2 films than PMMA and is important for maintaining the integrity of the film during the transfer process. This surface-energy-assisted approach can be generally applied to the transfer of other 2D materials, such as WS2. DA - 2014/11// PY - 2014/11// DO - 10.1021/nn5057673 VL - 8 IS - 11 SP - 11522-11528 SN - 1936-086X KW - molybdenum disulfide KW - 2D materials KW - tungsten disulfide KW - surface energy KW - large scale ER - TY - CONF TI - Output feedback reset control of general MIMO LTI systems AU - Yuan, C. Z. AU - Wu, F. AB - This paper presents a systematic Lyapunov-based approach for output-feedback reset control of linear time-invariant (LTI) systems with a general multiple-input multiple-output (MIMO) configuration. The reset controller consists of a base linear controller and a reset law that enforces resets to the controller states. Based on the extended Lyapunov-like function (ELF) technique, the reset controller with guaranteed exponential stability and weighted L 2 -gain performance is synthesized by solving a set of linear matrix inequalities (LMIs) with linear search over two scalar variables. A numerical example is used to illustrate the effectiveness of the proposed approach. C2 - 2014/// C3 - 2014 European Control Conference (ECC) DA - 2014/// DO - 10.1109/ecc.2014.6862225 SP - 2334-2339 ER - TY - JOUR TI - Modification of Properties of Yttria Stabilized Zirconia Epitaxial Thin Films by Excimer Laser Annealing AU - Bayati, R. AU - Molaeil, R. AU - Richmond, A. AU - Nori, S. AU - Wu, F. AU - Kumar, D. AU - Narayan, J. AU - Reynolds, J. G. AU - Reynolds, C. L., Jr. T2 - ACS APPLIED MATERIALS & INTERFACES AB - This study focuses on the ultrafast improvement of surface wettability, electrical, and room temperature magnetic characteristics of cubic zirconia single crystalline thin films after laser annealing. The point defects generated by the laser treatment are envisaged to play a critical role in altering the above properties. Yttria stabilized zirconia (YSZ) thin films were epitaxially grown on Si(100) substrates by pulsed laser deposition technique and subsequently annealed by a KrF excimer laser beam (τ = 25 ns) using low-energy laser pulses. An atomically sharp interface, parallel to the film free surface, between laser annealed layer and the pristine region was observed. The single crystalline nature of thin films was preserved following the laser treatment. The laser–solid interaction with YSZ led to the introduction of point defects, i.e., oxygen vacancies, resulting in a strained structure which, in turn, resulted in the formation of a tetragonal-like zirconia. With the increase of number of laser pulses the laser treated films got highly disordered due to the high concentration of the point defects, while maintaining their crystalline nature. Although the surface of the pristine sample showed weak hydrophilic characteristics (contact angle ∼ 73°), the laser annealed samples exhibited significantly improved hydrophilic characteristics. It was found that there is an optimum number of laser pulses where the maximum hydrophilicity (contact angle ∼ 22°) is obtained. The carrier concentration in the sample with the highest hydrophilicity was determined to be higher by about 5 orders of magnitude compared to the pristine sample. This sample possessed the lowest electrical resistivity. The laser annealed YSZ epilayers showed a superior room-temperature ferromagnetic behavior, compared to the pristine samples. A 2-fold enhancement in the magnetization of the samples was observed following the laser treatment which is a clear demonstration of the key role of defects and their transient distribution throughout the lattice. All these observations were correlated with the formation of point defects due to the photon interaction with YSZ and absorption of energy of the KrF laser photons to produce defects. DA - 2014/12/24/ PY - 2014/12/24/ DO - 10.1021/am506298y VL - 6 IS - 24 SP - 22316-22325 SN - 1944-8252 KW - ZrO2 KW - zirconia KW - epitaxy KW - wettability KW - conductivity KW - ferromagnetism KW - defect ER - TY - CONF TI - Effects of hydrogen enrichment on the reattachment and hysteresis of lifted methane flames AU - Kribs, J. D. AU - Hutchins, A. R. AU - Reach, W. A. AU - Hasan, T. S. AU - Lyons, K. M. C2 - 2014/// C3 - Proceedings of the ASME Power Conference, 2013, vol 1 DA - 2014/// ER - TY - CONF TI - Dwell-time min-switching for discrete-time switched linear systems AU - Duan, C. AU - Wu, F. AB - This paper addresses analysis and switching control problems of discrete-time switched linear systems. A mixed time-driven and state-dependent switching strategy is proposed to guarantee an average dwell time even when all subsystems are unstable. The switching rule and its associated switching output feedback controllers are designed to stabilize the switched system and achieve a disturbance attenuation performance. The proposed analysis and switching control approach could refrain frequent switches commonly observed in min-switching based designs. The effectiveness of the proposed approach is illustrated through a numerical example. C2 - 2014/// C3 - 2014 European Control Conference (ECC) DA - 2014/// DO - 10.1109/ecc.2014.6862224 SP - 2540-2545 ER - TY - JOUR TI - Dual-Frequency Piezoelectric Transducers for Contrast Enhanced Ultrasound Imaging AU - Martin, K. Heath AU - Lindsey, Brooks D. AU - Ma, Jianguo AU - Lee, Mike AU - Li, Sibo AU - Foster, F. Stuart AU - Jiang, Xiaoning AU - Dayton, Paul A. T2 - SENSORS AB - For many years, ultrasound has provided clinicians with an affordable and effective imaging tool for applications ranging from cardiology to obstetrics. Development of microbubble contrast agents over the past several decades has enabled ultrasound to distinguish between blood flow and surrounding tissue. Current clinical practices using microbubble contrast agents rely heavily on user training to evaluate degree of localized perfusion. Advances in separating the signals produced from contrast agents versus surrounding tissue backscatter provide unique opportunities for specialized sensors designed to image microbubbles with higher signal to noise and resolution than previously possible. In this review article, we describe the background principles and recent developments of ultrasound transducer technology for receiving signals produced by contrast agents while rejecting signals arising from soft tissue. This approach relies on transmitting at a low-frequency and receiving microbubble harmonic signals at frequencies many times higher than the transmitted frequency. Design and fabrication of dual-frequency transducers and the extension of recent developments in transducer technology for dual-frequency harmonic imaging are discussed. DA - 2014/11// PY - 2014/11// DO - 10.3390/s141120825 VL - 14 IS - 11 SP - 20825-20842 SN - 1424-8220 KW - acoustics KW - acoustic angiography KW - dual-frequency KW - superharmonic KW - harmonic KW - broadband KW - microbubbles ER - TY - CONF TI - Assessment of stabilization mechanisms of confined, turbulent, lifted jet flames: Effects of ambient coflow AU - Hutchins, A. R. AU - Kribs, J. D. AU - Muncey, R. D. AU - Lyons, K. M. C2 - 2014/// C3 - Proceedings of the ASME Power Conference, 2013, vol 1 DA - 2014/// ER - TY - JOUR TI - Fiber Bragg grating spectral features for structural health monitoring of composite structures AU - Webb, Sean AU - Peters, Kara AU - Zikry, Mohammed AU - Stan, Nikola AU - Chadderdon, Spencer AU - Selfridge, Richard AU - Schultz, Stephen T2 - 23RD INTERNATIONAL CONFERENCE ON OPTICAL FIBRE SENSORS AB - We demonstrate the measurement of and applications for reflected spectral signatures obtained from FBG sen- sors in dynamic environments. Three uses of the spectral distortion measurements for monitoring of airframe structures are presented: the measurement of the dynamic response of a laminated plate to an impact event; the measurement of damage induced spectral distortion in a thin plate during vibration loading; and the measurement of the change in dynamic response of an adhesively bonded joint with the progression of fatigue damage. DA - 2014/// PY - 2014/// DO - 10.1117/12.2059625 VL - 9157 SP - SN - 1996-756X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84903169877&partnerID=MN8TOARS KW - embedded sensing KW - structural health monitoring KW - fiber Bragg gratings ER - TY - CONF TI - Estimating trust from agents' interactions via commitments AU - Kalia, A. K. AU - Zhang, Z. AU - Singh, M. P. C2 - 2014/// C3 - 21st european conference on artificial intelligence (ecai 2014) DA - 2014/// VL - 263 SP - 1043-1044 ER - TY - JOUR TI - Development of chemically produced hydrogen energy-based impact bonding process for dissimilar metals AU - Ngaile, Gracious AU - Lohr, Peter AU - Lowrie, James AU - Modlin, Rhyne T2 - JOURNAL OF MANUFACTURING PROCESSES AB - There has been a growing demand in the fabrication of dissimilar metal parts for application in the automotive, aerospace, defense, chemical and nuclear industries. Welding of dissimilar materials can be accomplished via impact welding, which can minimize the formation of a continuous inter-metallic phase, while chemically bonding dissimilar metals. This paper discusses an innovative technique for bonding dissimilar metals by chemically produced hydrogen energy by reacting aluminum powder and water. Experiments were carried out to study impact bond characteristics using copper and stainless steel cylindrical billets. The influence of nosed flyer billet angle and billet mass on bonding characteristics were studied. The test results have demonstrated that the nosed flyer billet angle has significant influence on wavy bond patterns at the interface. Among the three flyer billet nose angles of 9°, 12° and 15°, the billets with a flyer angle of 15° resulted in a complete wave morphological pattern along the whole sample cross-section. This study shows the potential of developing a cost effective system/machinery where discrete metal parts can be bonded at near net shape. DA - 2014/10// PY - 2014/10// DO - 10.1016/j.jmapro.2014.07.005 VL - 16 IS - 4 SP - 518-526 SN - 2212-4616 KW - Hydrogen energy KW - Explosive welding KW - Metal bonding ER - TY - CONF TI - Crack propagation testing using a YCOB acoustic emission sensor AU - Johnson, J. A. AU - Kim, K. AU - Zhang, S. J. AU - Jiang, X. N. AB - Piezoelectric crystals are popular for passive sensors, such as accelerometers and acoustic emission sensors, due to their robustness and high sensitivity. These sensors are widespread in structural health monitoring among civil and industrial structures, but there is little application in high temperature environments (e.g. > 1000°C) due to the few materials that are capable of operating at elevated temperatures. Most piezoelectric materials suffer from a loss of electric properties above temperatures in the 500-700°C range, but rare earth oxyborate crystals, such as Yttrium calcium oxyborate (YCOB), retain their piezoelectric properties above 1000 °C. Our previous research demonstrated that YCOB can be used to detect transient lamb waves via Hsu-Nielsen tests, which replicate acoustic emission waves, up to 1000°C. In this paper, YCOB piezoelectric acoustic emission sensors were tested for their ability to detect crack progression at elevated temperatures. The sensor was fabricated using a YCOB single crystal and Inconel electrodes and wires. The sensor was mounted onto a stainless steel bar substrate, which was machined to include a pre-crack notch. A dynamic load was induced on the bar with a shaker in order to force the crack to advance along the thickness of the substrate. The obtained raw data was processed and analyzed in the frequency domain and compared to the Lamb wave modes that were evaluated in previous Hsu-Nielsen testing for the substrate. C2 - 2014/// C3 - Nondestructive characterization for composite materials, aerospace engineering, civil infrastructure, and homeland security 2014 DA - 2014/// DO - 10.1117/12.2045091 VL - 9063 ER - TY - JOUR TI - Anisotropic Complementary Acoustic Metamaterial for Canceling out Aberrating Layers AU - Shen, Chen AU - Xu, Jun AU - Fang, Nicholas X. AU - Jing, Yun T2 - PHYSICAL REVIEW X AB - Medical techniques such as transcranial ultrasound beam focusing suffer from energy losses and distorted acoustic fields. Researchers show how metamaterials can be used to enhance acoustic transmission. DA - 2014/11/19/ PY - 2014/11/19/ DO - 10.1103/physrevx.4.041033 VL - 4 IS - 4 SP - SN - 2160-3308 ER - TY - JOUR TI - Variable recruitment fluidic artificial muscles: modeling and experiments AU - Bryant, Matthew AU - Meller, Michael A. AU - Garcia, Ephrahim T2 - SMART MATERIALS AND STRUCTURES AB - We investigate taking advantage of the lightweight, compliant nature of fluidic artificial muscles to create variable recruitment actuators in the form of artificial muscle bundles. Several actuator elements at different diameter scales are packaged to act as a single actuator device. The actuator elements of the bundle can be connected to the fluidic control circuit so that different groups of actuator elements, much like individual muscle fibers, can be activated independently depending on the required force output and motion. This novel actuation concept allows us to save energy by effectively impedance matching the active size of the actuators on the fly based on the instantaneous required load. This design also allows a single bundled actuator to operate in substantially different force regimes, which could be valuable for robots that need to perform a wide variety of tasks and interact safely with humans. This paper proposes, models and analyzes the actuation efficiency of this actuator concept. The analysis shows that variable recruitment operation can create an actuator that reduces throttling valve losses to operate more efficiently over a broader range of its force–strain operating space. We also present preliminary results of the design, fabrication and experimental characterization of three such bioinspired variable recruitment actuator prototypes. DA - 2014/7// PY - 2014/7// DO - 10.1088/0964-1726/23/7/074009 VL - 23 IS - 7 SP - SN - 1361-665X KW - McKibben muscle KW - fluidic artificial muscle KW - hydraulic artificial muscle KW - (FMC)-M-2 KW - variable recruitment KW - muscle bundle KW - bioinspired KW - efficiency ER - TY - JOUR TI - Modeling tether–ballast asteroid diversion systems, including tether mass and elasticity AU - French, David B. AU - Mazzoleni, Andre P. T2 - Acta Astronautica AB - Abstract The risk of an impact between a large asteroid and the Earth has been significant enough to attract the attention of many researchers. This paper focuses on a mitigation technique that involves the use of a long tether and ballast mass to divert an asteroid. When such a tether is modeled as massless and inelastic, results show that the method may be viable for diverting asteroids away from a collision with the Earth; the next step towards demonstrating the viability of the approach is to conduct a study which uses a more realistic tether model. This paper presents such a study, in which the tether models include tether mass and elasticity. These models verify that a tether–ballast system is capable of diverting Earth-threatening asteroids. Detailed parametric studies are presented which illustrate how system performance depends on tether mass and elasticity. Also, case studies are presented which show how more realistic models can aid in the design of tether–ballast asteroid mitigation systems. Key findings include the dangers imposed by periods during which the tether goes slack and ways to preclude this. DA - 2014/10// PY - 2014/10// DO - 10.1016/j.actaastro.2014.04.014 VL - 103 SP - 282-306 J2 - Acta Astronautica LA - en OP - SN - 0094-5765 UR - http://dx.doi.org/10.1016/j.actaastro.2014.04.014 DB - Crossref KW - Asteroid KW - Tether KW - Mitigation KW - Diversion KW - Near earth object (NEO) KW - Potentially hazardous asteroid (PHA) ER - TY - JOUR TI - Effect of Polymer Microstructure on the Nucleation Behavior of Alumina via Atomic Layer Deposition AU - Padbury, Richard P. AU - Jur, Jesse S. T2 - JOURNAL OF PHYSICAL CHEMISTRY C AB - Atomic layer deposition is a technique that is able to integrate nanoscale inorganic coatings to organic polymers. Through this process a number of different inorganic coating morphologies are able to form during ALD nucleation on a wide variety of polymers. In this work, we provide a systematic analysis of the ALD nucleation characteristics on polymers that have subtle variations in microstructure, such as, the addition of pendant groups or change in length of the polymer repeat unit. Specifically, in situ quartz crystal microgravimetry is employed to understand the nucleation behavior of alumina ALD in a series of poly n-methacrylate and polyester thin films. The work indicates the effect that a subtle change in polymer microstructure has on the properties of the polymer film. The data indicates that the glass transition temperature of the polymer, as influenced by variations in microstructure, has a significant impact on the absorption/desorption characteristics during TMA/water exposures. Through this systematic approach, we demonstrate that ALD process parameters must be adjusted accordingly to promote the formation of desirable inorganic material interfaces. DA - 2014/8/14/ PY - 2014/8/14/ DO - 10.1021/jp506456y VL - 118 IS - 32 SP - 18805-18813 SN - 1932-7455 ER - TY - JOUR TI - Directional biomechanical properties of porcine skin tissue AU - Huang, H. Y. S. AU - Huang, S. Y. AU - Frazier, C. P. AU - Prim, P. M. AU - Harrysson, O. T2 - Journal of Mechanics in Medicine and Biology DA - 2014/// PY - 2014/// VL - 14 IS - 5 ER - TY - JOUR TI - Creating targeted initial populations for genetic product searches in heterogeneous markets AU - Foster, Garrett AU - Turner, Callaway AU - Ferguson, Scott AU - Donndelinger, Joseph T2 - ENGINEERING OPTIMIZATION AB - AbstractGenetic searches often use randomly generated initial populations to maximize diversity and enable a thorough sampling of the design space. While many of these initial configurations perform poorly, the trade-off between population diversity and solution quality is typically acceptable for small-scale problems. Navigating complex design spaces, however, often requires computationally intelligent approaches that improve solution quality. This article draws on research advances in market-based product design and heuristic optimization to strategically construct ‘targeted’ initial populations. Targeted initial designs are created using respondent-level part-worths estimated from discrete choice models. These designs are then integrated into a traditional genetic search. Two case study problems of differing complexity are presented to illustrate the benefits of this approach. In both problems, targeted populations lead to computational savings and product configurations with improved market share of preferences. Future research efforts to tailor this approach and extend it towards multiple objectives are also discussed.Keywords: genetic searchmarket-based product designproduct line optimizationmixed-integer optimization DA - 2014/12// PY - 2014/12// DO - 10.1080/0305215x.2013.861458 VL - 46 IS - 12 SP - 1729-1747 SN - 1029-0273 KW - genetic search KW - market-based product design KW - product line optimization KW - mixed-integer optimization ER - TY - JOUR TI - Analysis and synthesis of linear hybrid systems with state-triggered jumps AU - Yuan, Chengzhi AU - Wu, Fen T2 - NONLINEAR ANALYSIS-HYBRID SYSTEMS AB - This paper investigates first the stability and L2-gain problems for a class of linear hybrid control systems with state-triggered jumps by using an extended Lyapunov-like function (ELF) technique. The obtained results are then applied to facilitate the joint design of a hybrid controller (linear controller plus reset law) for a continuous-time linear time-invariant (LTI) plant. The hybrid H∞ synthesis conditions are expressed in linear matrix inequalities (LMIs) with two line search parameters. An inverted pendulum example is used to illustrate the effectiveness of the proposed approach. DA - 2014/11// PY - 2014/11// DO - 10.1016/j.nahs.2014.05.002 VL - 14 SP - 47-60 SN - 1878-7460 KW - Hybrid controller synthesis KW - Impulsive systems KW - Reset control KW - Linear matrix inequality ER - TY - JOUR TI - Temperature-Dependent Infiltration of Polymers during Sequential Exposures to Trimethylaluminum AU - Padbury, Richard P. AU - Jur, Jesse S. T2 - LANGMUIR AB - Atomic layer deposition provides the opportunity to introduce nanoscale inorganic coatings to organic polymers creating coatings of varied compositions of finish with distinctive interfaces. Prior research has shown that ALD materials nucleation on polymers varies in composition and structure based on how the precursor interacts with the polymer chemistry and the process conditions. To study this in more detail, in situ quartz crystal microgravimetry is employed to understand the infiltration and saturation behavior of trimethylaluminum in polyamide-6, poly(acrylic acid), poly(ethylene terephthalate), and poly(methyl methacrylate). Emphasis is placed on understanding reactive vapor diffusion into these polymers as the exposure temperature is varied. Finally, we propose potential growth mechanisms based on the temperature-dependent observations in this work that enables the ability to produce a customized interface for ALD materials growth on polymer substrates. DA - 2014/8/5/ PY - 2014/8/5/ DO - 10.1021/la501679f VL - 30 IS - 30 SP - 9228-9238 SN - 0743-7463 ER - TY - JOUR TI - Spectroscopy, scattering and imaging techniques for nanostructured materials AU - Huang, H.-Y. S. AU - Subramanian, A. T2 - Journal of Nanotechnology in Engineering and Medicine DA - 2014/// PY - 2014/// VL - 5 IS - 2 ER - TY - JOUR TI - Soot measurements for diesel and biodiesel spray combustion under high temperature highly diluted ambient conditions AU - Zhang, Ji AU - Jing, Wei AU - Roberts, William L. AU - Fang, Tiegang T2 - FUEL AB - This paper presents the soot temperature and KL factor for biodiesel, namely fatty acid methyl ester (FAME) and diesel fuel combustion in a constant volume chamber using a two-color technique. The KL factor is a parameter for soot concentration, where K is an absorption coefficient and proportional to the number density of soot particles, L is the geometric thickness of the flame along the optical detection axis, and KL factor is proportional to soot volume fraction. The main objective is to explore a combustion regime called high-temperature and highly-diluted combustion (HTHDC) and compare it with the conventional and low-temperature combustion (LTC) modes. The three different combustion regimes are implemented under different ambient temperatures (800 K, 1000 K, and 1400 K) and ambient oxygen concentrations (10%, 15%, and 21%). Results are presented in terms of soot temperature and KL factor images, time-resolved pixel-averaged soot temperature, KL factor, and spatially integrated KL factor over the soot area. The time-averaged results for these three regimes are compared for both diesel and biodiesel fuels. Results show complex combined effects of the ambient temperature and oxygen concentration, and that two-color temperature for the HTHDC mode at the 10% oxygen level can actually be lower than the conventional mode. Increasing ambient oxygen and temperature increases soot temperature. Diesel fuel results in higher soot temperature than biodiesel for all three regimes. Results also show that diesel and biodiesel fuels have very different burning and sooting behavior under the three different combustion regimes. For diesel fuel, the HTHDC regime offers better results in terms of lower soot than the conventional and LTC regimes, and the 10% O2, 1400 K ambient condition shows the lowest soot concentration while maintaining a moderate two-color temperature. For biodiesel, the 15% O2, 800 K ambient condition shows some advantages in terms of reducing soot concentration. Based on these results, the practical implementation of this combustion mode is outlined and a feasible option is proposed. DA - 2014/11/1/ PY - 2014/11/1/ DO - 10.1016/j.fuel.2014.06.071 VL - 135 SP - 340-351 SN - 1873-7153 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84904957615&partnerID=MN8TOARS KW - Biodiesel KW - Soot KW - Spray combustion KW - Two-color thermometry KW - High temperature highly diluted combustion ER - TY - JOUR TI - Positive exchange bias in epitaxial permalloy/MgO integrated with Si (100) AU - Rao, S. S. AU - Prater, J. T. AU - Wu, Fan AU - Nori, S. AU - Kumar, D. AU - Yue, L. AU - Liou, S. -H. AU - Narayan, J. T2 - CURRENT OPINION IN SOLID STATE & MATERIALS SCIENCE AB - In magnetic random access memory (MRAM) devices, soft magnetic thin film elements such as permalloy (Py) are used as unit cells of information. The epitaxial integration of these elements with the technologically important substrate Si (1 0 0) and a thorough understanding of their magnetic properties are critical for CMOS-based magnetic devices. We report on the epitaxial growth of Ni82.5Fe17.5 (permalloy, Py) on Si (1 0 0) using a TiN/MgO buffer layer. Initial stages of growth are characterized by the formation of discrete islands that gradually merge into a continuous film as deposition times are extended. Interestingly, we find that the magnetic features of Py films in early stages of island coalescence are distinctly different from the films formed initially (discrete islands) and after extended deposition times (narrow distribution of equiaxed granular films). Isothermal in-plane and out-of-plane magnetic measurements performed on these transitional films show highly anisotropic magnetic behavior with an easy magnetization axis lying in the plane of the film. Importantly, when this sample is zero-field cooled, a positive exchange bias and vertical loop shift are observed, unusual for a soft ferromagnet like Py. Repeated field cycling and hysteresis loops up to the fields of 7T produced reproducible hysteresis loops indicating the existence of strongly pinned spin configurations. Classical interface related exchange bias models cannot explain the observed magnetic features of the transitional Py films. We believe that the anomalous magnetic behavior of such Py films may be explained by considering the highly irregular morphology that develops at intermediate growth times that are possibly also undergoing a transition from Bloch to Neel domain wall structures as a function of Py island size. This study broadens the current understanding of magnetic properties of Py thin layers for technological applications in magneto-electronic devices, integrated with Si (1 0 0). DA - 2014/6// PY - 2014/6// DO - 10.1016/j.cossms.2014.02.001 VL - 18 IS - 3 SP - 140-146 SN - 1879-0348 KW - Positive exchange bias KW - Permalloy islands KW - Epitaxial integration KW - Pulsed laser deposition KW - Domain matching epitaxy ER - TY - JOUR TI - Mapping Antiretroviral Drugs in Tissue by IR-MALDESI MSI Coupled to the Q Exactive and Comparison with LC-MS/MS SRM Assay AU - Barry, Jeremy A. AU - Robichaud, Guillaume AU - Bokhart, Mark T. AU - Thompson, Corbin AU - Sykes, Craig AU - Kashuba, Angela D. M. AU - Muddiman, David C. T2 - JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY AB - This work describes the coupling of the IR-MALDESI imaging source with the Q Exactive mass spectrometer. IR-MALDESI MSI was used to elucidate the spatial distribution of several HIV drugs in cervical tissues that had been incubated in either a low or high concentration. Serial sections of those analyzed by IR-MALDESI MSI were homogenized and analyzed by LC-MS/MS to quantify the amount of each drug present in the tissue. By comparing the two techniques, an agreement between the average intensities from the imaging experiment and the absolute quantities for each drug was observed. This correlation between these two techniques serves as a prerequisite to quantitative IR-MALDESI MSI. In addition, a targeted MS2 imaging experiment was also conducted to demonstrate the capabilities of the Q Exactive and to highlight the added selectivity that can be obtained with SRM or MRM imaging experiments. DA - 2014/12// PY - 2014/12// DO - 10.1007/s13361-014-0884-1 VL - 25 IS - 12 SP - 2038-2047 SN - 1879-1123 KW - IR-MALDESI KW - Mass spectrometry imaging KW - LC-MS/MS KW - Drug distribution ER - TY - JOUR TI - In-situ imaging of lithium-ion batteries via the secondary ion mass spectrometry AU - ChiuHuang, C.-K. AU - Zhou, C. AU - Huang, H.-Y. S. T2 - Journal of Nanotechnology in Engineering and Medicine DA - 2014/// PY - 2014/// VL - 5 IS - 2 ER - TY - JOUR TI - In situ emulsification using a non-uniform alternating electric field AU - Choi, Suhwan AU - Saveliev, Alexei V. T2 - APPLIED PHYSICS LETTERS AB - We report an electric field based method for in situ emulsification of water droplets immersed in a continuous oil phase. High density water-in-oil emulsions are generated using non-uniform ac electric fields applied between needle and plate electrodes. An initial water droplet is entrained in the area of high electric field near the needle electrode where it is dispersed under the influence of high electric stresses. Breakup mechanisms responsible for a gradual dispersion of the water droplets are investigated. Identified mechanisms involve drop elongation to a cylindrical shape followed by a capillary breakup, ac electrospraying from individual water droplets, and formation and breakup of bead-like structures comprised by the water droplets interconnected by thin water bridges. Water droplets with diameters close to 1 μm and a narrow size distribution are formed at long processing times. The generated emulsion has a well-defined boundary and is confined near the needle electrode in a shape resembling a pendant drop. DA - 2014/8/18/ PY - 2014/8/18/ DO - 10.1063/1.4893670 VL - 105 IS - 7 SP - SN - 1077-3118 ER - TY - JOUR TI - High strain-rate interfacial behavior of layered metallic composites AU - Khanikar, Prasenjit AU - Zikry, M. A. T2 - MECHANICS OF MATERIALS AB - The high strain-rate interfacial behavior of layered aluminum composite has been investigated. A dislocation-density based crystalline plasticity formulation, specialized finite-element techniques, rational crystallographic orientation relations, and a new fracture methodology for large scale plasticity been used. Two alloy layers, a high strength alloy, aluminum 2195, and an aluminum alloy 2139, with high toughness, were modeled with representative microstructures that included precipitates, dispersed particles, and different grain boundary (GB) distributions. The new fracture methodology, based on an overlapping element method and phantom nodes, along with a fracture criteria specialized for fracture on different cleavage planes is used to model interfacial delamination. Dislocation-density evolution significantly affects the delamination process, and this has a directly related to the strengthening, toughening, and failure of the layered composite. It is also shown that brittle alumina (Al2O3) platelets in the interface region played an important role in interfacial delamination and overall composite behavior. DA - 2014/10// PY - 2014/10// DO - 10.1016/j.mechmat.2014.07.008 VL - 77 SP - 52-66 SN - 1872-7743 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84904976514&partnerID=MN8TOARS KW - Interface delamination KW - Dynamic fracture KW - Layered aluminum composite KW - Dislocation KW - Crystal plasticity KW - Finite element method ER - TY - JOUR TI - Analysis and control of switched linear systems via dwell-time min-switching AU - Duan, Chang AU - Wu, Fen T2 - SYSTEMS & CONTROL LETTERS AB - This paper addresses analysis and switching control problems of switched linear systems. To this end, a mixed time-driven and state-dependent switching strategy is proposed. It guarantees an average dwell time even when all subsystems are unstable. The switching rule and its associated switching output feedback controllers are designed to stabilize the switched system and satisfy a weighted L2 gain performance. The proposed analysis and switching control approach could refrain frequent switches commonly observed in min-switching based designs. The effectiveness of the proposed approach has been illustrated through a spherical inverted pendulum example. DA - 2014/8// PY - 2014/8// DO - 10.1016/j.sysconle.2014.05.004 VL - 70 SP - 8-16 SN - 1872-7956 KW - Switched linear system KW - Dwell-time KW - Min-switching KW - Bilinear matrix inequality KW - Stabilization and weighted L-2 gain ER - TY - JOUR TI - The onset of convection in a horizontal nanofluid layer of finite depth: A revised model AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER AB - This paper presents a revised linear stability analysis for the onset of natural convection in a horizontal nanofluid layer. The employed model incorporates the effects of Brownian motion and thermophoresis. It is now assumed that the value of the temperature can be imposed on the boundaries, but the nanoparticle fraction adjusts so that the nanoparticle flux is zero on the boundaries. It is shown that, with the new boundary conditions, oscillatory convection can no longer occur. The pertinent dimensionless nanofluid parameters have been rescaled. The effect of the nanoparticles on non-oscillatory convection is destabilizing. DA - 2014/10// PY - 2014/10// DO - 10.1016/j.ijheatmasstransfer.2014.06.020 VL - 77 SP - 915-918 SN - 1879-2189 KW - Nanofluid KW - Brownian motion KW - Thermophoresis KW - Natural convection KW - Horizontal layer ER - TY - JOUR TI - Side branch-based acoustic metamaterials with a broad-band negative bulk modulus AU - Shen, Chen AU - Jing, Yun T2 - APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING DA - 2014/12// PY - 2014/12// DO - 10.1007/s00339-014-8603-0 VL - 117 IS - 4 SP - 1885-1891 SN - 1432-0630 ER - TY - JOUR TI - Self-similar flow due to the stretching of a deformable fiber AU - Fang, Tiegang AU - El-Mistikawy, Tarek M. A. T2 - EUROPEAN PHYSICAL JOURNAL PLUS DA - 2014/11/25/ PY - 2014/11/25/ DO - 10.1140/epjp/i2014-14252-6 VL - 129 IS - 11 SP - SN - 2190-5444 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84919884593&partnerID=MN8TOARS ER - TY - JOUR TI - Relationship between direct and converse flexoelectric coefficients AU - Shu, Longlong AU - Li, Fei AU - Huang, Wenbin AU - Wei, Xiaoyong AU - Yao, , Xi AU - Jiang, Xiaoning T2 - JOURNAL OF APPLIED PHYSICS AB - Flexoelectric effect, as a universal electromechanical coupling, has drawn lots of interests in dielectric materials. However, due to the restrictions of present measurement techniques, only part of coefficients has been experimentally examined. In this study, we derived the coordinate-dependent Gibbs free energy density function in the inhomogeneous spatial field to investigate the relationship between the direct and converse flexoelectric coefficients. In crystalline mediums and systems, the direct and converse flexoelectric coefficients are proved to equivalent according to the Maxwell relation. These results will broaden the application of the Maxwell relation into non-linear spatial field, and provide the guideline for experimental measurement and prediction of flexoelectric coefficients. DA - 2014/10/14/ PY - 2014/10/14/ DO - 10.1063/1.4897647 VL - 116 IS - 14 SP - SN - 1089-7550 ER - TY - JOUR TI - Miniature horizontal axis wind turbine system for multipurpose application AU - Xu, F. J. AU - Yuan, F. G. AU - Hu, J. Z. AU - Qiu, Y. P. T2 - ENERGY AB - A MWT (miniature wind turbine) has received great attention recently for powering WISP (Wireless Intelligent Sensor Platform). In this study, two MHAWTs (miniature horizontal axis wind turbines) with and without gear transmission were designed and fabricated. A physics-based model was proposed and the optimal load resistances of the MHAWTs were predicted. The open circuit voltages, output powers and net efficiencies were measured under various ambient winds and load resistances. The experimental results showed the optimal load resistances matched well with the predicted results; the MHAWT without gear obtained higher output power at the wind speed of 2 m/s to 6 m/s, while the geared MHAWT exhibited better performance at the wind speed higher than 6 m/s. In addition, a DCM (discontinuous conduction mode) buck-boost converter was adopted as an interface circuit to maximize the charging power from MHAWTs to rechargeable batteries, exhibiting maximum efficiencies above 85%. The charging power reached about 8 mW and 36 mW at the wind speeds of 4 m/s and 6 m/s respectively, which indicated that the MHAWTs were capable for sufficient energy harvesting for powering low-power electronics continuously. DA - 2014/10/1/ PY - 2014/10/1/ DO - 10.1016/j.energy.2014.07.046 VL - 75 SP - 216-224 SN - 1873-6785 KW - Miniature horizontal axis wind turbine KW - Equivalent electromechanical circuit model KW - Gear transmission KW - Interface circuit KW - Energy harvesting ER - TY - JOUR TI - Mach 6 Wake Flow Simulations Using a Large-Eddy Simulation/Reynolds-Averaged Navier Stokes Model AU - Salazar, Giovanni AU - Edwards, Jack R. T2 - JOURNAL OF SPACECRAFT AND ROCKETS AB - A hybrid large-eddy simulation/Reynolds-averaged Navier–Stokes turbulence model is used to simulate the Mach 6 flow around a scaled model similar to NASA’s Orion multipurpose crew vehicle. The results for surface pressure and heat transfer are compared with experimental data from previous base flow experiments conducted at the Calspan—University at Buffalo Research Center. Using the highest Reynolds number test case ( based on capsule diameter), different numerical aspects of the hybrid approach are addressed, such as use of a low-dissipation scheme, a modification to the eddy-viscosity blending function, time-averaging results, filtering computational results, and sensitivity to grid resolution. In addition, results are compared with Reynolds-Averaged Navier–Stokes using Menter’s two-equation baseline model and to detached-eddy simulation predictions. By introducing a new modification to the blending from Reynolds-averaged Navier–Stokes to large-eddy simulation within boundary layers, very good agreement with the experiment is obtained in regions where the boundary-layer grid spacing is too coarse for large-eddy simulation. The findings show that the high-fidelity schemes produce results that agree much better with the experimental data than Reynolds-averaged Navier–Stokes methods, which tend to underpredict base pressures and overpredict heat fluxes. The overall accuracy of each scheme is evaluated using a normalized root mean square error in different regions of the flow, and the analysis shows that, in separated regions, the integrated error is over 120% using a Reynolds-averaged Navier–Stokes model, and 30–50% using the higher fidelity schemes. Additionally, the hybrid methodology presented is further validated by considering a lower Reynolds number , where the flow is nominally transitional, and very accurate heat transfer predictions are also obtained. DA - 2014/// PY - 2014/// DO - 10.2514/1.a32729 VL - 51 IS - 4 SP - 1329-1348 SN - 1533-6794 ER - TY - JOUR TI - Iteration schemes for rapid post-stall aerodynamic prediction of wings using a decambering approach AU - Paul, R. C. AU - Gopalarathnam, A. T2 - International Journal for Numerical Methods in Fluids AB - SUMMARY Nonlinear aerodynamics of wings may be evaluated using an iterative decambering approach. In this approach, the effect of flow separation due to stall at any wing section is modeled as an effective reduction in section camber. The approach uses a wing analysis method for potential‐flow calculations and viscous airfoil lift curves for the sections as input. The calculation procedure is implemented using a Newton–Raphson iteration to simultaneously satisfy the boundary condition, which comes from potential‐flow wing theory, and drive the sectional operating points toward their respective viscous lift curves, as required for convergence. Of particular interest in this research is the calculation of the residuals during the Newton iteration. Unlike a typical implementation of the Newton iteration, the residual calculation is not performed via a straightforward function evaluation, but rather by estimating the target operating points on the input viscous lift curves. Estimation of these target operating points depends on the assumptions made in the cross‐coupling of the decambering at the different sections. This paper presents four residual calculation schemes for the decambering approach. The residual calculation schemes are compared against each other to assess computational speed and robustness. Decambering results are also compared with higher‐order computational fluid dynamics (CFD) solutions for rectangular and swept wings. Results from the best scheme compare well with the CFD solutions for the rectangular wing, motivating further development of the method. Poor predictions for the swept wings are traced to spanwise propagation of separated flow at stall, highlighting the limitations of the current approach. Copyright © 2014 John Wiley & Sons, Ltd. DA - 2014/7/5/ PY - 2014/7/5/ DO - 10.1002/fld.3931 VL - 76 IS - 4 SP - 199-222 J2 - Int. J. Numer. Meth. Fluids LA - en OP - SN - 0271-2091 UR - http://dx.doi.org/10.1002/fld.3931 DB - Crossref KW - nonlinear aerodynamics KW - stall KW - flight dynamics KW - viscous effects KW - Newton iteration KW - wing aerodynamics ER - TY - JOUR TI - Giant flexoelectricity in Ba0.6Sr0.4TiO3/Ni0.8Zn0.2Fe2O4 composite AU - Li, Yong AU - Shu, Longlong AU - Huang, Wenbin AU - Jiang, Xiaoning AU - Wang, Hong T2 - APPLIED PHYSICS LETTERS AB - Enhanced flexoelectricity in perovskite ceramics and single crystals has been reported before. In this letter, 3-3 ceramic-ceramic Ba0.6Sr0.4TiO3/Ni0.8Zn0.2Fe2O4 composite with a colossal permittivity was employed in the conventional pure bending experiment in order to examine the transverse flexoelectric response. The measured flexoelectric coefficient at 30 Hz is 128 μC/m and varies to 16 μC/m with the frequency increasing from 30 Hz to 120 Hz, mainly due to the inverse correlation between the permittivity and the frequency. This result reveals the permittivity dependence of flexoelectric coefficient in the frequency dispersion materials, suggesting that the giant permittivity composites can be good flexoelectric materials. DA - 2014/10/20/ PY - 2014/10/20/ DO - 10.1063/1.4899060 VL - 105 IS - 16 SP - SN - 1077-3118 ER - TY - JOUR TI - Flexoelectricity in barium strontium titanate thin film AU - Kwon, Seol Ryung AU - Huang, Wenbin AU - Shu, Longlong AU - Yuan, Fuh-Gwo AU - Maria, Jon-Paul AU - Jiang, Xiaoning T2 - APPLIED PHYSICS LETTERS AB - Flexoelectricity, the linear coupling between the strain gradient and the induced electric polarization, has been intensively studied as an alternative to piezoelectricity. Especially, it is of interest to develop flexoelectric devices on micro/nano scales due to the inherent scaling effect of flexoelectric effect. Ba0.7Sr0.3TiO3 thin film with a thickness of 130 nm was fabricated on a silicon wafer using a RF magnetron sputtering process. The flexoelectric coefficients of the prepared thin films were determined experimentally. It was revealed that the thin films possessed a transverse flexoelectric coefficient of 24.5 μC/m at Curie temperature (∼28 °C) and 17.44 μC/m at 41 °C. The measured flexoelectric coefficients are comparable to that of bulk BST ceramics, which are reported to be 10–100 μC/m. This result suggests that the flexoelectric thin film structures can be effectively used for micro/nano-sensing devices. DA - 2014/10/6/ PY - 2014/10/6/ DO - 10.1063/1.4898139 VL - 105 IS - 14 SP - SN - 1077-3118 ER - TY - JOUR TI - Energy Harvesting for Self-Powered Aerostructure Actuation AU - Bryant, Matthew AU - Pizzonia, Matthew AU - Mehallow, Michael AU - Garcia, Ephrahim T2 - ACTIVE AND PASSIVE SMART STRUCTURES AND INTEGRATED SYSTEMS 2014 AB - This paper proposes and experimentally investigates applying piezoelectric energy harvesting devices driven by flow induced vibrations to create self-powered actuation of aerostructure surfaces such as tabs, flaps, spoilers, or morphing devices. Recently, we have investigated flow-induced vibrations and limit cycle oscillations due to aeroelastic flutter phenomena in piezoelectric structures as a mechanism to harvest energy from an ambient fluid flow. We will describe how our experimental investigations in a wind tunnel have demonstrated that this harvested energy can be stored and used on-demand to actuate a control surface such as a trailing edge flap in the airflow. This actuated control surface could take the form of a separate and discrete actuated flap, or could constitute rotating or deflecting the oscillating energy harvester itself to produce a non-zero mean angle of attack. Such a rotation of the energy harvester and the associated change in aerodynamic force is shown to influence the operating wind speed range of the device, its limit cycle oscillation (LCO) amplitude, and its harvested power output; hence creating a coupling between the device’s performance as an energy harvester and as a control surface. Finally, the induced changes in the lift, pitching moment, and drag acting on a wing model are quantified and compared for a control surface equipped with an oscillating energy harvester and a traditional, static control surface of the same geometry. The results show that when operated in small amplitude LCO the energy harvester adds negligible aerodynamic drag. DA - 2014/// PY - 2014/// DO - 10.1117/12.2046408 VL - 9057 SP - SN - 1996-756X KW - energy harvesting KW - flutter KW - aeroelasticity KW - piezoelectric KW - aeroelectroelastic KW - self-powered actuator ER - TY - JOUR TI - Cracks Monitoring and Characterization Using Ba0.64Sr0.36TiO3 Flexoelectric Strain Gradient Sensors AU - Huang, Wenbin AU - Yang, Shaorui AU - Zhang, Ningyi AU - Yuan, Fuh-Gwo AU - Jiang, Xiaoning T2 - SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2014 AB - This paper presents a new method for monitoring and characterizing cracks using Ba0.64Sr0.36TiO3 flexoelectric strain gradient sensors. Firstly, strain gradient field around the mixed mode asymptotic crack tip was analyzed, followed by the derivation of induced flexoelectric polarization in the strain gradient sensors attached in the vicinity of a crack tip. It was found that the flexoelectric polarization of the sensor can be expressed as a function of the stress intensity factors of crack and relative coordinates between the sensor and crack. Given the information of the crack size, further analysis demonstrates that the location of the crack can be traced through the calculation based on flexoelectric outputs of the distributed sensors. A specimen with Mode-I crack was then prepared with two strain gradient sensors (4.7 mm × 0.9 mm × 0.3 mm) attached close to the crack tip to verify the analytical model for detection of cracks. The experimental results yield accurate location of the crack, confirming that flexoelectric strain gradient sensing can be a good avenue for monitoring cracks. DA - 2014/// PY - 2014/// DO - 10.1117/12.2045166 VL - 9061 SP - SN - 0277-786X KW - Crack detection KW - stress intensify factors KW - flexoelectric KW - strain gradient sensing ER - TY - JOUR TI - Climbing Robot Actuated by Meso-Hydraulic Artificial Muscles AU - Bryant, Matthew AU - Fitzgerald, Jason AU - Miller, Samuel AU - Saltzman, Jonah AU - Kim, Sangkyu AU - Lin, Yong AU - Garcia, Ephrahim T2 - ACTIVE AND PASSIVE SMART STRUCTURES AND INTEGRATED SYSTEMS 2014 AB - This paper presents the design, construction, experimental characterization, and system testing of a legged, wall-climbing robot actuated by meso-scale hydraulic artificial muscles. While small wall-climbing robots have seen increased research attention in recent years, most authors have primarily focused on designs for the gripping and adhesion of the robot to the wall, while using only standard DC servo-motors for actuation. This project seeks to explore and demonstrate a different actuation mechanism that utilizes hydraulic artificial muscles. A four-limb climbing robot platform that includes a full closed-loop hydraulic power and control system, custom hydraulic artificial muscles for actuation, an on-board microcontroller and RF receiver for control, and compliant claws with integrated sensing for gripping a variety of wall surfaces has been constructed and is currently being tested to investigate this actuation method. On-board power consumption data-logging during climbing operation, analysis of the robot kinematics and climbing behavior, and artificial muscle force-displacement characterization are presented to investigate and this actuation method. DA - 2014/// PY - 2014/// DO - 10.1117/12.2046368 VL - 9057 SP - SN - 1996-756X KW - climbing robot KW - wall climbing KW - bio-inspired KW - artificial muscle KW - McKibben muscle KW - hydraulic muscle ER - TY - JOUR TI - Approximate method for computing convective heating on hypersonic vehicles using unstructured grids AU - Hamilton, H. H. AU - Weilmuenster, K. J. AU - DeJarnette, F. R. T2 - Journal of Spacecraft and Rockets DA - 2014/// PY - 2014/// VL - 51 IS - 4 SP - 1288-1305 ER - TY - JOUR TI - Silver dopants for targeted and untargeted direct analysis of unsaturated lipids via infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) AU - Meier, Florian AU - Garrard, Kenneth P. AU - Muddiman, David C. T2 - RAPID COMMUNICATIONS IN MASS SPECTROMETRY AB - Unsaturated lipids play a crucial role in cellular processes as signaling factors, membrane building blocks or energy storage molecules. However, adequate mass spectrometry imaging of this diverse group of molecules remains challenging. In this study we implemented silver cationization for direct analysis by infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) to enhance the ion abundances for olefinic lipids and facilitate peak assignment.Trace amounts of silver nitrate were doped into the electrospray solvent of an IR-MALDESI imaging source coupled to an Orbitrap mass analyzer. Calcifediol was examined as a model compound to demonstrate the effect of silver dopants on sensitivity and assay robustness. Dried human serum spots were subsequently analyzed to compare Ag-doped solvents with previously described solvent compositions. Mass differences as well as ion abundance ratio filters were employed to interpret results based on the characteristic isotopic pattern of silver.Olefinic lipids were readily observed as silver adducts in IR-MALDESI analyses. Silver cationization decreased the limit of detection for calcifediol by at least one order of magnitude and was not affected in complex biological matrices. The ion abundance ratio and mass difference of [M + (107) Ag(+)](+) and [M + (109) Ag(+)](+) were successfully applied to facilitate the spectral assignment of silver adducts. Overall, silver cationization increased the analyte coverage in human serum by 43% compared with a standard IR-MALDESI approach.Silver cationization has been shown to enhance IR-MALDESI sensitivity and selectivity for unsaturated lipids, even when applied to complex samples. Increased compound coverage, enhanced robustness as well as the developed tools for peak assignment and mapping of isotopic patterns will clearly benefit future mass spectrometry imaging studies. DA - 2014/11/30/ PY - 2014/11/30/ DO - 10.1002/rcm.7041 VL - 28 IS - 22 SP - 2461-2470 SN - 1097-0231 ER - TY - JOUR TI - Performance Analysis and Technical Feasibility Assessment of a Transforming Roving-Rolling Explorer Rover for Mars Exploration AU - Edwin, Lionel E. AU - Denhart, Jason D. AU - Gemmer, Thomas R. AU - Ferguson, Scott M. AU - Mazzoleni, Andre P. T2 - JOURNAL OF MECHANICAL DESIGN AB - This paper explores a two state rover concept called the Transforming Roving-Rolling Explorer (TRREx). The first state allows the rover to travel like a conventional 6-wheeled rover. The second state is a sphere to permit faster descent of steep inclines. Performance of this concept is compared to a traditional rocker-bogie (RB) architecture using hi-fidelity simulations in Webots. Results show that for missions involving very rugged terrain, or a considerable amount of downhill travel, the TRREx outperforms the rocker-bogie. Locomotion of the TRREx system using a continuous shifting of the center of mass through “actuated rolling” is also explored. A dynamics model for a cylindrical representation of the rover is simulated to identify feasible configurations capable of generating and maintaining continuous rolling motion even on sandy terrain. Results show that in sufficiently benign terrain gradual inclines can be traversed with actuated rolling. This model allows for increased exploration of the problem's design space and assists in establishing parameters for an Earth prototype. DA - 2014/7// PY - 2014/7// DO - 10.1115/1.4027336 VL - 136 IS - 7 SP - SN - 1050-0472 ER - TY - JOUR TI - Microstructural modeling of crack nucleation and propagation in high strength martensitic steels AU - Wu, Q. AU - Zikry, M. A. T2 - INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES AB - A dislocation-density based multiple-slip crystalline plasticity formulation, a dislocation-density grain boundary (GB) interaction scheme, and an overlapping fracture method were used to investigate crack nucleation and propagation in martensitic steel with retained austenite for both quasi-static and dynamic loading conditions. The formulation accounts for variant morphologies, orientation relationships, and retained austenite that are uniquely inherent to lath martensitic microstructures. The interrelated effects of dislocation-density evolution ahead of crack front and the variant distribution of martensitic blocks on crack nucleation and propagation are investigated. It is shown that dislocation-density generation ahead of crack front can induce dislocation-density accumulations and plastic deformation that can blunt crack propagation. These predictions indicate that variant distribution of martensitic blocks can be optimized to mitigate and potentially inhibit material failure. DA - 2014/12// PY - 2014/12// DO - 10.1016/j.ijsolstr.2014.08.021 VL - 51 IS - 25-26 SP - 4345-4356 SN - 1879-2146 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84923217972&partnerID=MN8TOARS KW - Dislocation-density KW - Lath martensite KW - Retained austenite KW - Crack nucleation ER - TY - JOUR TI - Increasing dynamic range of a fibre Bragg grating edge-filtering interrogator with a proportional control loop AU - Stan, Nikola AU - Bailey, D. C. AU - Chadderdon, S. L. AU - Webb, S. AU - Zikry, M. AU - Peters, K. J. AU - Selfridge, R. H. AU - Schultz, S. M. T2 - MEASUREMENT SCIENCE AND TECHNOLOGY AB - We present a fibre Bragg grating (FBG) interrogator that uses a microcontroller board and a tunable optical filter in a proportional control loop to increase dynamic range and achieve high strain sensitivity. It is an edge-filtering interrogator with added proportional control loop that locks the operating wavelength to the mid-reflection point on the FBG spectrum. The interrogator separates low-frequency (LF) components of strain and measures them with extended dynamic range, while at the same time measuring high-frequency (HF) strain without loss in strain sensitivity. In this paper, we describe the implementation of the interrogator and analyse the characteristics of individual components, such as the speed and voltage resolution of the microcontroller and the tunable optical filter. We measure the performance of the proportional control loop at frequencies up to 1 kHz and characterize the system using control theory. We illustrate the limitation of the conventional interrogator to measure strains greater than 40 μ and demonstrate successful application of the proposed interrogator for simultaneous measurement of 450 μ LF strain at 50 Hz superimposed with 32 kHz HF strain. DA - 2014/6// PY - 2014/6// DO - 10.1088/0957-0233/25/6/065206 VL - 25 IS - 6 SP - SN - 1361-6501 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84899634683&partnerID=MN8TOARS KW - fibre Bragg grating KW - edge-filtering interrogation KW - proportional control loop KW - strain measurement KW - structural health monitoring ER - TY - JOUR TI - Evaluation of turbulence-chemistry interaction under diesel engine conditions with multi-flamelet RIF model AU - Kundu, P. AU - Pei, Y. J. AU - Wang, M. J. AU - Mandhapati, R. AU - Som, S. T2 - Atomization and Sprays DA - 2014/// PY - 2014/// VL - 24 IS - 9 SP - 779-800 ER - TY - JOUR TI - Conformal Atomic Layer Deposition of Alumina on Millimeter Tall, Vertically-Aligned Carbon Nanotube Arrays AU - Stano, Kelly L. AU - Carroll, Murphy AU - Padbury, Richard AU - McCord, Marian AU - Jur, Jesse S. AU - Bradford, Philip D. T2 - ACS APPLIED MATERIALS & INTERFACES AB - Atomic layer deposition (ALD) can be used to coat high aspect ratio and high surface area substrates with conformal and precisely controlled thin films. Vertically aligned arrays of multiwalled carbon nanotubes (MWCNTs) with lengths up to 1.5 mm were conformally coated with alumina from base to tip. The nucleation and growth behaviors of Al2O3 ALD precursors on the MWCNTs were studied as a function of CNT surface chemistry. CNT surfaces were modified through a series of post-treatments including pyrolytic carbon deposition, high temperature thermal annealing, and oxygen plasma functionalization. Conformal coatings were achieved where post-treatments resulted in increased defect density as well as the extent of functionalization, as characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. Using thermogravimetric analysis, it was determined that MWCNTs treated with pyrolytic carbon and plasma functionalization prior to ALD coating were more stable to thermal oxidation than pristine ALD coated samples. Functionalized and ALD coated arrays had a compressive modulus more than two times higher than a pristine array coated for the same number of cycles. Cross-sectional energy dispersive X-ray spectroscopy confirmed that Al2O3 could be uniformly deposited through the entire thickness of the vertically aligned MWCNT array by manipulating sample orientation and mounting techniques. Following the ALD coating, the MWCNT arrays demonstrated hydrophilic wetting behavior and also exhibited foam-like recovery following compressive strain. DA - 2014/11/12/ PY - 2014/11/12/ DO - 10.1021/am505107s VL - 6 IS - 21 SP - 19135-19143 SN - 1944-8244 KW - carbon nanotube (CNT) KW - atomic layer deposition (ALD) KW - alumina KW - aligned carbon nanotube array KW - CNT-inorganic hybrid KW - plasma KW - functionalization ER - TY - JOUR TI - Concentration photovoltaic-thermal energy co-generation system using nanofluids for cooling and heating AU - Xu, Zelin AU - Kleinstreuer, Clement T2 - ENERGY CONVERSION AND MANAGEMENT AB - New designs of dual concentration photovoltaic–thermal (CPV/T) systems can provide both electrical and thermal energy, while reducing solar cell material usage via optical techniques. The overall system efficiency can be improved by using advanced dual-purpose liquids with enhanced heat transfer characteristics, such as nanofluids. In this paper the use of nanofluids, i.e., dilute nanoparticle suspensions in liquids, are considered for improved efficiency of a CPV/T system for the first time. Specifically, a 2-D model coupling thermal analysis and computational fluid dynamics simulations has been developed to calculate efficiencies of individual subsystems as well as the overall system. A new thermal conductivity model for nanofluids, which was validated with experimental data sets, was employed. The electrical and thermal performances of the system were evaluated for different climatic conditions. The results show that using nanofluids improves the electrical and total efficiencies of the system, especially when using silicon solar cells. For example, if the nanofluid outlet temperature of the solar cell is set to 62 °C via a controlled flow rate, the system overall efficiency could reach 70% with electrical and thermal contributions amounting to 11% and 59%, respectively. In summary, a nanofluid-based system is preferable to water-based systems in the long run. DA - 2014/11// PY - 2014/11// DO - 10.1016/j.enconman.2014.07.047 VL - 87 SP - 504-512 SN - 1879-2227 KW - Co-generation KW - Concentration photovoltaic-thermal (CPV/T) system KW - Nanofluid thermal conductivity KW - System efficiencies ER - TY - JOUR TI - Comparison of precursor infiltration into polymer thin films via atomic layer deposition and sequential vapor infiltration using in-situ quartz crystal microgravimetry AU - Padbury, Richard P. AU - Jur, Jesse S. T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A AB - Previous research exploring inorganic materials nucleation behavior on polymers via atomic layer deposition indicates the formation of hybrid organic–inorganic materials that form within the subsurface of the polymer. This has inspired adaptations to the process, such as sequential vapor infiltration, which enhances the diffusion of organometallic precursors into the subsurface of the polymer to promote the formation of a hybrid organic–inorganic coating. This work highlights the fundamental difference in mass uptake behavior between atomic layer deposition and sequential vapor infiltration using in-situ methods. In particular, in-situ quartz crystal microgravimetry is used to compare the mass uptake behavior of trimethyl aluminum in poly(butylene terephthalate) and polyamide-6 polymer thin films. The importance of trimethyl aluminum diffusion into the polymer subsurface and the subsequent chemical reactions with polymer functional groups are discussed. DA - 2014/7// PY - 2014/7// DO - 10.1116/1.4882654 VL - 32 IS - 4 SP - SN - 1520-8559 ER - TY - JOUR TI - Burner lip temperature and stabilization of a non-premixed jet flame AU - Lamige, S. AU - Lyons, K. M. AU - Galizzi, C. AU - Andre, F. AU - Kuehni, M. AU - Escudie, D. T2 - EXPERIMENTAL THERMAL AND FLUID SCIENCE AB - This experimental study addresses issues on heat transfer between the nozzle and the base of a non-premixed methane/air jet-flame. The burner lip temperature as well as temperature gradients at the top of the straight tube burner are systematically thermocouple-monitored, along with axial and radial positions of the flame attachment location by means of CH*-chemiluminescence imaging. The effects on lip temperature are tested for several parameters: flame state, either attached or lifted; aerodynamic conditions, over a very wide range of fuel injection velocities, covering both laminar and turbulent pipe flow for the inlet fuel, as well as momentum and velocity ratios between fuel and coflow both lower and greater than unity; nozzle rim coating, either uncoated or black-coated; initial reactant temperature, with preheating temperatures from 295 K to 1000 K; and burner material thermal conductivity, between 2.7 and 400 W/(m K). The observed phenomena are described and discussed in relation with changes of these parameters. Some conclusions are also drawn as for the relative importance of the different modes of heat transfer in the flame attachment zone, towards a better understanding of the flame stabilization process. In particular, flame attachment height measurements reveal a critical value towards high lip temperature obtained with low burner thermal conductivity. Eventually, this work allowed identification of four regions depending on fuel injection velocity, each associated with particular evolutions in terms of flame location and lip temperature. DA - 2014/7// PY - 2014/7// DO - 10.1016/j.expthermflusci.2013.11.008 VL - 56 SP - 45-52 SN - 1879-2286 KW - Non-premixed flame KW - Stabilization KW - Attachment height KW - Heat transfer KW - Burner material KW - Lip temperature ER - TY - JOUR TI - Assessment of chemical kinetic modeling for silane/hydrogen mixtures in hypersonic applications AU - Esposito, G. AU - Rahimi, M. J. AU - Chelliah, H. K. AU - Vogel, P. D. AU - Edwards, J. R. T2 - AIAA Journal DA - 2014/// PY - 2014/// VL - 52 IS - 10 SP - 2213-2222 ER - TY - JOUR TI - Announcing the 2013 Measurement Science and Technology Outstanding Paper Awards AU - Foss, John AU - Dewhurst, Richard AU - Yacoot, Andrew AU - Tadigadapa, Srinivas AU - Peters, Kara T2 - MEASUREMENT SCIENCE AND TECHNOLOGY DA - 2014/7// PY - 2014/7// DO - 10.1088/0957-0233/25/7/070201 VL - 25 IS - 7 SP - SN - 1361-6501 ER - TY - JOUR TI - A Nondimensional Analysis to Characterize Thermomagnetic Convection of a Temperature Sensitive Magnetic Fluid in a Flow Loop AU - Karimi-Moghaddam, Giti AU - Gould, Richard D. AU - Bhattacharya, Subhashish T2 - JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME AB - This paper presents results from theoretical and numerical studies of a single-phase, temperature sensitive magnetic fluid operating under steady-state laminar flow conditions in a partially heated thermomagnetic circulation loop under the influence of an external magnetic field (created by a solenoid). A one-dimensional theoretical model has been developed using scaling arguments to characterize thermomagnetic circulation in this loop in terms of the geometric length scales, magnetic fluid properties, and the strength of the imposed magnetic field. In parallel to this theoretical analysis, supporting numerical simulations using Comsol Multiphysics simulation software have been undertaken to obtain data for use in this 1D model. Comparison between experimental data and numerical simulation results and also a grid sensitivity analysis was carried out to validate the numerical simulation. A correlation for the nondimensional heat transfer (Nusselt number) as a function of the appropriate magnetic Rayleigh number and a correlation for the mass flow rate based on the system's properties are developed. DA - 2014/9// PY - 2014/9// DO - 10.1115/1.4027863 VL - 136 IS - 9 SP - SN - 1528-8943 KW - nondimensional analysis KW - thermomagnetic circulation KW - temperature sensitive ferrofluid ER - TY - JOUR TI - What tau distribution maximizes fast axonal transport toward the axonal synapse? AU - Kuznetsov, I. A. AU - Kuznetsov, A. V. T2 - MATHEMATICAL BIOSCIENCES AB - This theoretical research is aimed at investigating the question of why tau protein concentration exhibits a proximal–distal increase in healthy axons and a proximal–distal decrease in degenerating axons in Alzheimer’s disease. We developed a model of fast axonal transport toward the axon synapse. The model is based on recently published experimental results by Dixit et al. (2008) [1] who reported that the attachment rate of kinesin-1 to MTs is reduced by tau. Cytoplasmic dynein is affected less by tau (dynein is affected at much higher tau concentrations than those that affect kinesin-1). We used the model to investigate the effect of various tau distributions along the axon length on organelle flux toward the axon synapse. We found that a proximal–distal increase in tau concentration leads to a higher organelle flux while a proximal–distal decrease in tau concentration leads to a smaller organelle flux than a uniform tau concentration. We also computed what tau distribution would give the largest organelle flux toward the synapse. We found that in order to maximize organelle flux, the tau concentration has to be at its minimum level in the proximal axon and its maximum level at the distal axon, which is in agreement with the bang–bang principle in optimal control theory. DA - 2014/7// PY - 2014/7// DO - 10.1016/j.mbs.2014.04.001 VL - 253 SP - 19-24 SN - 1879-3134 KW - Tau protein KW - Organelle transport KW - Optimal control KW - Alzheimer's disease ER - TY - JOUR TI - Stabilisation of Markov jump linear systems subject to both state and mode detection delays AU - Yang, Ting AU - Zhang, Lixian AU - Li, Yuandi AU - Leng, Yusong T2 - IET CONTROL THEORY AND APPLICATIONS AB - This study addresses the stabilisation problem of a class of discrete-time Markov jump linear systems subject to time delays which occur in both the system state and mode detection. The mode detection delay means that there exists a lag between the switching of the system modes and the switching of the corresponding controllers. The state delays are considered to be random but with upper and lower bounds, and the mode detection delay is assumed to be constant. With an extended state space, the underlying system can be remodelled as a Markov jump linear system in which the system complexity and the number of system modes are both increased to a certain extent, but remain unchanged when the mode detection delay becomes larger. A sufficient condition guaranteeing the stochastic stability of the system is obtained via a modified stochastic Lyapunov function. The effectiveness of the proposed design approach is demonstrated by a numerical example. DA - 2014/3/6/ PY - 2014/3/6/ DO - 10.1049/iet-cta.2013.0507 VL - 8 IS - 4 SP - 260-266 SN - 1751-8652 ER - TY - JOUR TI - Sorting of cargos between axons and dendrites: modelling of differences in cargo transport in these two types of neurites AU - Kuznetsov, A. V. T2 - COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING AB - AbstractExplaining how intracellular cargos are sorted between axons and dendrites is important for a mechanistic understanding of what happens in many neurodegenerative disorders. A simple model of cargo sorting relies on differences in microtubule (MT) orientation between axons and dendrites: in mammalian neurons all MTs in axons have their plus ends directed outward while in proximal regions of dendrites the MT polarity is mixed. It can therefore be assumed that cargos that need to be driven into axons associate with kinesin motors while cargos that need to be driven into dendrites associate with dynein motors. This paper develops equations of cargo transport in axons and dendrites based on the above assumptions. Propagation of a pulse of radiolabelled cargos entering an axon and dendrite is simulated. The model equations are solved utilising the Laplace transform method. Differences in cargo transport between axons and dendrites are discussed.Keywords:: neuronsintracellular transportaxonal and dendritic cargosmodelling DA - 2014/5/19/ PY - 2014/5/19/ DO - 10.1080/10255842.2012.716047 VL - 17 IS - 7 SP - 792-799 SN - 1476-8259 KW - axonal and dendritic cargos KW - intracellular transport KW - modelling KW - neurons ER - TY - JOUR TI - Skin Burn Translation Model for Evaluating Hand Protection in Flash Fire Exposures AU - Hummel, Alexander AU - Barker, Roger AU - Lyons, Kevin T2 - FIRE TECHNOLOGY DA - 2014/9// PY - 2014/9// DO - 10.1007/s10694-013-0336-7 VL - 50 IS - 5 SP - 1285-1299 SN - 1572-8099 KW - Burn injury prediction modeling KW - Human skin burns KW - Flame protection KW - Thermal protection KW - Protective clothing KW - Instrumented manikin fire test systems ER - TY - JOUR TI - Nanostructured Materials for Electronics and Photonics AU - Bayati, R. AU - Mishra, Y. K. AU - Naseri, N. AU - Nori, S. T2 - JOURNAL OF NANOMATERIALS AB - This special issue addresses both experimental and theoretical research works in the areas of nanoscale electronic, optoelectronic, andmagneto-optical materials. It aims to facilitate the dissemination of interdisciplinary research results in the interrelated and rapidly converging fields of nanoelectronics and photonics. The main focus of this issue is placed on enhancing the performance of electronic devices using nanoscience and nanotechnology.The following aspects were considered as particular interests for this special issue: DA - 2014/// PY - 2014/// DO - 10.1155/2014/725764 VL - 2014 SP - SN - 1687-4129 ER - TY - JOUR TI - Localized measurements of composite dynamic response for health monitoring AU - Webb, Sean AU - Oman, Kyle AU - Peters, Karsa AU - Stan, Nikola AU - Chadderdon, Sspencer AU - Selfridge, Richard AU - Schultz, Stephen T2 - SMART SENSOR PHENOMENA, TECHNOLOGY, NETWORKS, AND SYSTEMS INTEGRATION 2014 AB - We demonstrate the measurement of and applications for full-spectral measurements collected from FBG sensors in dynamic loading environments. The measurement of the dynamic response of a laminated plate to an impact event highlights the information gained during the event as compared to after the event. The measurement of damage induced spectral distortion in a thin plate during vibration loading demonstrates the capability of separating spectral distortion due to multiple effects, including damage and vibration loading. Finally, the measurement of the change in dynamic response of an adhesively bonded joint highlights the capability to measure the progression of fatigue damage. Confirmation that the change in FBG response is due to fatigue damage is performed through independent pulsed phase thermography imaging of the adhesively bonded joint. DA - 2014/// PY - 2014/// DO - 10.1117/12.2045255 VL - 9062 SP - SN - 1996-756X KW - embedded sensing KW - structural health monitoring KW - fiber Bragg gratings ER - TY - JOUR TI - Large-Eddy/Reynolds-Averaged Navier-Stokes Simulations of Reactive Flow in Dual-Mode Scramjet Combustor AU - Fulton, Jesse A. AU - Edwards, Jack R. AU - Hassan, Hassan A. AU - McDaniel, James C. AU - Goyne, Christopher P. AU - Rockwell, Robert D. AU - Cutler, Andrew D. AU - Johansen, Craig T. AU - Danehy, Paul M. T2 - JOURNAL OF PROPULSION AND POWER AB - Numerical simulations of the turbulent reactive flow within a model scramjet combustor configuration, experimentally mapped at the University of Virginia’s Scramjet Combustion Facility at an equivalence ratio of 0.17, are described in this paper. A hybrid large-eddy simulation/Reynolds-averaged Navier–Stokes method is used, with special attention focused on capturing facility-specific effects, such as asymmetric inflow temperature distributions, on flow development within the combustor. Predictions obtained using two nine-species hydrogen oxidation models are compared with experimental data obtained using coherent anti-Stokes Raman spectroscopy, hydroxyl radical planar laser-induced fluorescence, stereoscopic particle image velocimetry, and focusing schlieren techniques. The large-eddy simulation/Reynolds-averaged Navier–Stokes models accurately capture the mean structure of the fully developed flame but tend to overpredict fluctuation levels toward the outer edge of the reactive plume. Model predictions worsen in the flame-anchoring region just downstream of the fuel injector. Here, turbulence/chemistry interactions are more pronounced, and the flame is more influenced by the inflow conditions. Comparisons with hydroxyl radical planar laser-induced fluorescence imagery indicate that the large-eddy simulation/Reynolds-averaged Navier–Stokes model can capture the effects of larger turbulent scales in deforming the flame structure but does not capture the effects of small turbulent structures in broadening the OH profiles. DA - 2014/// PY - 2014/// DO - 10.2514/1.b34929 VL - 30 IS - 3 SP - 558-575 SN - 1533-3876 ER - TY - JOUR TI - Indirect Intelligent Sliding Mode Control of Antagonistic Shape Memory Alloy Actuators Using Hysteretic Recurrent Neural Networks AU - Wiest, Jennifer Hannen AU - Buckner, Gregory D. T2 - IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY AB - This paper presents the development of an indirect intelligent sliding mode control (IISMC) system for use with antagonistic shape memory alloy (SMA) actuators. The controller manipulates input voltages to a pair of offset antagonistic SMA tendons, resulting in heat-induced bending of a flexible beam. Hysteresis compensation is achieved using a pair of hysteretic recurrent neural networks, which map the nonlinear, hysteretic relationships between SMA temperatures and bending angle for each tendon. The sliding mode control law regulates tendon temperatures based on reference and measured bending angle. Additionally, the IISMC incorporates an antislack component to increase tendon responsiveness. Experimental results demonstrate precise tracking of periodic reference trajectories. The controller is robust to model uncertainty, disturbances, and parameter variations, with bending angle tracking results superior to those of an optimized proportional + integral controller. DA - 2014/5// PY - 2014/5// DO - 10.1109/tcst.2013.2272420 VL - 22 IS - 3 SP - 921-929 SN - 1558-0865 KW - Intelligent control KW - microactuators KW - recurrent neural networks KW - shape memory alloys KW - sliding mode control ER - TY - JOUR TI - Experimental and computational investigation of the dynamic behavior of Al-Cu-Li alloys AU - Khanikar, P. AU - Liu, Y. AU - Zikry, Mohammed T2 - Materials Science & Engineering. A, Structural Materials: Properties, Microstructure and Processing AB - A dislocation-density based crystalline plasticity formulation, finite-element techniques, rational crystallographic orientation relations and a new fracture methodology were used to predict the failure modes associated with the high strain rate behavior of high strength Al–Cu–Li alloys. Widely used aluminum alloy 2195 (AA2195) was taken as the representative of Al–Cu–Li alloys. Experimental characterization using Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) were performed to gain insights on microstructural behavior. The alloy aggregate was modeled with representative microstructures that included precipitates, dispersed particles, and different grain boundary (GB) distributions. The new fracture methodology, based on overlapping elements and phantom nodes, was used with a fracture criteria specialized for fracture on different cleavage planes to investigate dynamic crack nucleation and growth. The compressive behavior of AA2195 under high strain rate loading was compared with that of Al–Cu alloy 2139 to further understand the behavior of the AA2195 with the more ductile AA2139. The predictions quantify how local microstructural effects, due to precipitates and dispersed particles, have a dominant effect on crack initiation and growth. DA - 2014/// PY - 2014/// DO - 10.1016/j.msea.2014.02.089 VL - 604 SP - 67–77 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84897871655&partnerID=MN8TOARS ER - TY - JOUR TI - EFFECTS OF DILUENTS ON SOOT SURFACE TEMPERATURE AND VOLUME FRACTION IN DILUTED ETHYLENE DIFFUSION FLAMES AT PRESSURE AU - Kailasanathan, Ranjith Kumar Abhinavam AU - Zhang, Ji AU - Fang, Tiegang AU - Roberts, William L. T2 - COMBUSTION SCIENCE AND TECHNOLOGY AB - AbstractSoot surface temperature and volume fraction are measured in ethylene/air coflowing laminar diffusion flames at high pressures, diluted with one of four diluents (argon, helium, nitrogen, and carbon dioxide) using a two-color technique. Both temperature and soot measurements presented are line-of-sight averages. The results aid in understanding the kinetic and thermodynamic behavior of the soot formation and oxidation chemistry with changes in diluents, ultimately leading to possible methods of reducing soot emission from practical combustion hardware. The diluted fuel and coflow exit velocities (top-hat profiles) were matched at all pressures to minimize shear effects. In addition to the velocity-matched flow rates, the mass fluxes were held constant for all pressures. Addition of a diluent has a pronounced effect on both the soot surface temperature and volume fraction, with the helium diluted flame yielding the maximum and carbon dioxide diluted flame yielding minimum soot surface temperature and volume fraction. At low pressures, peak soot volume fraction exists at the tip of the flame, and with an increase in pressure, the location shifts lower to the wings of the flame. Due to the very high diffusivity of helium, significantly higher temperature and volume fraction are measured and explained. Carbon dioxide has the most dramatic soot suppression effect. By comparing the soot yield with previously measured soot precursor concentrations in the same flame, it is clear that the lower soot yield is a result of enhanced oxidation rates rather than a reduction in precursor formation.Keywords: Elevated pressureLaminar diffusion flameSoot surface temperatureSoot volume fraction DA - 2014/// PY - 2014/// DO - 10.1080/00102202.2013.878710 VL - 186 IS - 6 SP - 815-828 SN - 1563-521X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84901250746&partnerID=MN8TOARS KW - Elevated pressure KW - Laminar diffusion flame KW - Soot surface temperature KW - Soot volume fraction ER - TY - JOUR TI - Drag reduction on aircraft configurations with adaptive lifting surfaces AU - Cusher, Aaron A. AU - Gopalarathnam, Ashok T2 - Aerospace Science and Technology AB - An approach, applicable to multiple-lifting-surface fixed-wing aircraft operating at subcritical Mach numbers, is presented for minimizing induced and profile drag with a constraint on the pitching moment. The approach allows the designer to select surface incidence, twist, and flap angles as variables for the optimization. The numerical formulation uses superposition to construct the spanwise lift distribution from basic and additional loadings, and decomposes the flap-angle distributions for each surface into mean and variation distributions. Together, these elements enable the solution of the problem using semi-analytical methods that also provide insight. Results are presented for a three surface aircraft which highlights low drag possibilities with positive static margins, presents the trade-offs between induced and profile drag, and provides insight into the aerodynamics of multiple lifting surface configurations. DA - 2014/4// PY - 2014/4// DO - 10.1016/j.ast.2014.01.012 VL - 34 SP - 35-44 J2 - Aerospace Science and Technology LA - en OP - SN - 1270-9638 UR - http://dx.doi.org/10.1016/j.ast.2014.01.012 DB - Crossref KW - Configuration aerodynamics KW - Drag reduction KW - Adaptive wings KW - Aircraft aerodynamics KW - Aircraft design ER - TY - JOUR TI - Discrete-vortex method with novel shedding criterion for unsteady aerofoil flows with intermittent leading-edge vortex shedding AU - Ramesh, Kiran AU - Gopalarathnam, Ashok AU - Granlund, Kenneth AU - Ol, Michael V. AU - Edwards, Jack R. T2 - Journal of Fluid Mechanics AB - Abstract Unsteady aerofoil flows are often characterized by leading-edge vortex (LEV) shedding. While experiments and high-order computations have contributed to our understanding of these flows, fast low-order methods are needed for engineering tasks. Classical unsteady aerofoil theories are limited to small amplitudes and attached leading-edge flows. Discrete-vortex methods that model vortex shedding from leading edges assume continuous shedding, valid only for sharp leading edges, or shedding governed by ad-hoc criteria such as a critical angle of attack, valid only for a restricted set of kinematics. We present a criterion for intermittent vortex shedding from rounded leading edges that is governed by a maximum allowable leading-edge suction. We show that, when using unsteady thin aerofoil theory, this leading-edge suction parameter (LESP) is related to the $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}A_0$ term in the Fourier series representing the chordwise variation of bound vorticity. Furthermore, for any aerofoil and Reynolds number, there is a critical value of the LESP, which is independent of the motion kinematics. When the instantaneous LESP value exceeds the critical value, vortex shedding occurs at the leading edge. We have augmented a discrete-time, arbitrary-motion, unsteady thin aerofoil theory with discrete-vortex shedding from the leading edge governed by the instantaneous LESP. Thus, the use of a single empirical parameter, the critical-LESP value, allows us to determine the onset, growth, and termination of LEVs. We show, by comparison with experimental and computational results for several aerofoils, motions and Reynolds numbers, that this computationally inexpensive method is successful in predicting the complex flows and forces resulting from intermittent LEV shedding, thus validating the LESP concept. DA - 2014/6/23/ PY - 2014/6/23/ DO - 10.1017/jfm.2014.297 VL - 751 SP - 500-538 J2 - J. Fluid Mech. LA - en OP - SN - 0022-1120 1469-7645 UR - http://dx.doi.org/10.1017/jfm.2014.297 DB - Crossref KW - computational methods KW - separated flows KW - vortex interactions ER - TY - JOUR TI - Converse flexoelectric coefficient f(1212) in bulk Ba0.67Sr0.33TiO3 AU - Shu, Longlong AU - Huang, Wenbin AU - Kwon, Seol Ryung AU - Wang, Zhao AU - Li, Fei AU - Wei, Xiaoyong AU - Zhang, Shujun AU - Lanagan, Michael AU - Yao, , Xi AU - Jiang, Xiaoning T2 - APPLIED PHYSICS LETTERS AB - Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Longlong Shu, Wenbin Huang, Seol Ryung Kwon, Zhao Wang, Fei Li, Xiaoyong Wei, Shujun Zhang, Michael Lanagan, Xi Yao, Xiaoning Jiang; Converse flexoelectric coefficient f1212 in bulk Ba0.67Sr0.33TiO3. Appl. Phys. Lett. 9 June 2014; 104 (23): 232902. https://doi.org/10.1063/1.4882060 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioApplied Physics Letters Search Advanced Search |Citation Search DA - 2014/6/9/ PY - 2014/6/9/ DO - 10.1063/1.4882060 VL - 104 IS - 23 SP - SN - 1077-3118 ER - TY - JOUR TI - Collaborative Experimental and Computational Study of a Dual-Mode Scramjet Combustor AU - Rockwell, Robert D., Jr. AU - Goyne, Christopher R. AU - Rice, Brian E. AU - Kouchi, Toshinori AU - McDaniel, James C. AU - Edwards, Jack R. T2 - JOURNAL OF PROPULSION AND POWER AB - Advanced computational models of hypersonic air-breathing combustion processes are being developed to better understand and predict the complex flows within a dual-mode scramjet combustor. However, the accuracy of these models can only be quantified through comparison to experimental databases. Moreover, the quality of computational results is dependent on accurate and detailed knowledge of the combustor inflow and boundary conditions. Toward these ends, this paper describes results from a collaboration of experimental and computational investigators. Detailed computational fluid dynamics and finite element analyses were performed throughout the design and implementation of experiments involving a direct-connect scramjet combustor operating at steady state during long duration testing. The test section hardware was designed to provide substantial access for optical laser diagnostics. Measurement locations included the inflow plane and several locations downstream of fuel injection. A suite of advanced in-stream diagnostics were applied, many of which are described in companion papers. Significant results in this paper include measured static wall pressures and temperatures, stereoscopic particle image velocimetry, and focused schlieren imaging. Validated thermal finite element calculations in the scramjet hardware and temperature maps of the flow path boundaries are also presented. Comparison of experimental results with computational fluid dynamics predictions are discussed in a separate paper. DA - 2014/// PY - 2014/// DO - 10.2514/1.b35021 VL - 30 IS - 3 SP - 530-538 SN - 1533-3876 ER - TY - JOUR TI - Batch sedimentation in an impulsively heated system AU - Joshi, A. C. AU - Ward, T. T2 - Journal of Petroleum Science and Engineering DA - 2014/// PY - 2014/// VL - 118 SP - 15-26 ER - TY - JOUR TI - An implicit Hermite WENO reconstruction-based discontinuous Galerkin method on tetrahedral grids AU - Xia, Yidong AU - Luo, Hong AU - Nourgaliev, Robert T2 - COMPUTERS & FLUIDS AB - An Implicit Reconstructed Discontinuous Galerkin method, IRDG (P1P2), is presented for solving the compressible Euler equations on tetrahedral grids. In this method, a quadratic polynomial (P2) solution is first reconstructed using a least-squares method from the underlying linear polynomial (P1) DG solution. By taking advantage of the derivatives in the DG formulation, the stencils used in the reconstruction involve only von Neumann neighborhood (adjacent face-neighboring cells) and thus are compact and consistent with the underlying DG method. The final P2 solution is then obtained using a WENO reconstruction, which is necessary to ensure stability of the RDG (P1P2) method. A matrix-free GMRES (generalized minimum residual) algorithm is presented to solve the approximate system of linear equations arising from Newton linearization. The LU-SGS (lower–upper symmetric Gauss–Seidel) preconditioner is applied with both the simplified and approximate Jacobian matrices. The numerical experiments on a variety of flow problems demonstrate that the developed IRDG (P1P2) method is able to obtain a speedup of at least two orders of magnitude than its explicit counterpart, maintain the linear stability, and achieve the designed third order of accuracy: one order of accuracy higher than the underlying second-order DG (P1) method without significant increase in computing costs and storage requirements. It is also found that a well approximated Jacobian matrix is essential for the IRDG method to achieve fast converging speed and maintain robustness on large-scale problems. DA - 2014/6/13/ PY - 2014/6/13/ DO - 10.1016/j.compfluid.2014.02.027 VL - 96 SP - 406-421 SN - 1879-0747 KW - Discontinuous Galerkin KW - Reconstruction method KW - WENO KW - Compressible flows KW - Implicit method KW - Tetrahedral grids ER - TY - JOUR TI - A super-compact metamaterial absorber cell in L-band AU - Cao, Z. X. AU - Yuan, F. G. AU - Li, L. H. T2 - JOURNAL OF APPLIED PHYSICS AB - A super-compact metamaterial absorber (SMA) unit cell in L band (1–2 GHz) is proposed, which is composed of a pair of electric ring resonator (ERR) and its complementary ERR (CERR) with a high dielectric substrate sandwiched in between. The CERR has a cross sectional area where approximately the etched copper foil in ERR is now retained, and the remaining region is now etched. In contract with quarter-wavelength (λ/4) thickness which is required for conventional absorbers, the largest in-plane dimension and thickness of the SMA cell are only λ/33 and λ/250, respectively, leading to a super compact cell volume. While traditionally the long straight wire is introduced in electric-LC resonators for increasing inductance, the CERR achieves similar inductance with much shorter lengths. Thus, its cell dimensions can be drastically reduced without compromising its performance. In addition, simulations together with an automated phase correction algorithm show that the SMA is a type of metamaterial possessing simultaneous negative electric permittivity (NEP) and negative magnetic permeability (NMP). Further the SMA has a very large imaginary part of the NEP and NMP, resulting in significantly large imaginary part of the refractive index at resonant frequency. These properties are well suited to design excellent absorbers. In addition, numerical results demonstrate that the maximum absorption coefficient of the SMA can reach greater than 99% at resonant frequency, and the full-width half-maximum is roughly 1% of the operating frequency, and a wide incident angle of ±49° over 90% absorption. Meanwhile, it is pointed out that this type of absorber is rather sensitive to polarization characteristic of the incident electromagnetic wave. DA - 2014/5/14/ PY - 2014/5/14/ DO - 10.1063/1.4875835 VL - 115 IS - 18 SP - SN - 1089-7550 ER - TY - JOUR TI - A set of parallel, implicit methods for a reconstructed discontinuous Galerkin method for compressible flows on 3D hybrid grids AU - Xia, Yidong AU - Luo, Hong AU - Frisbey, Megan AU - Nourgaliev, Robert T2 - COMPUTERS & FLUIDS AB - A set of implicit methods are proposed for a third-order hierarchical WENO reconstructed discontinuous Galerkin method for compressible flows on 3D hybrid grids. An attractive feature in these methods are the application of the Jacobian matrix based on the P1 element approximation, resulting in a huge reduction of memory requirement compared with DG (P2). Also, three approaches — analytical derivation, divided differencing, and automatic differentiation (AD) are presented to construct the Jacobian matrix respectively, where the AD approach shows the best robustness. A variety of compressible flow problems are computed to demonstrate the fast convergence property of the implemented flow solver. Furthermore, an SPMD (single program, multiple data) programming paradigm based on MPI is proposed to achieve parallelism. The numerical results on complex geometries indicate that this low-storage implicit method can provide a viable and attractive DG solution for complicated flows of practical importance. DA - 2014/7/2/ PY - 2014/7/2/ DO - 10.1016/j.compfluid.2014.01.023 VL - 98 SP - 134-151 SN - 1879-0747 KW - Discontinuous Galerkin KW - Hierarchical WENO reconstruction KW - Implicit methods KW - Automatic differentiation KW - Parallel computing ER - TY - JOUR TI - A nonlinear principal component analysis approach for turbulent combustion composition space AU - Mirgolbabaei, Hessam AU - Echekki, Tarek AU - Smaoui, Nejib T2 - INTERNATIONAL JOURNAL OF HYDROGEN ENERGY AB - An approach for the determination of principal components using nonlinear principal component analysis (NLPCA) is proposed in the context of turbulent combustion. NLPCA addresses complex data sets where the contours of the inherent principal directions are curved in the original manifold. Thermo-chemical scalars' statistics are reconstructed from the optimally derived moments. The tabulation of the scalars is then implemented, using artificial neural networks (ANN). The approach is implemented on numerical data generated for the stand-alone one-dimensional turbulence (ODT) simulation of hydrogen autoignition in a turbulent jet with preheated air. It is found that 2 nonlinear principal components are sufficient to capture thermo-chemical scalars' profiles. For some of the scalars, a single principal component reasonably captures the scalars' profiles as well. DA - 2014/3/18/ PY - 2014/3/18/ DO - 10.1016/j.ijhydene.2013.12.195 VL - 39 IS - 9 SP - 4622-4633 SN - 1879-3487 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84895441869&partnerID=MN8TOARS KW - Turbulent combustion KW - Nonlinear principal component analysis KW - Autoignition ER - TY - JOUR TI - A new type of microphone using flexoelectric barium strontium titnate AU - Kwon, Seol Ryung AU - Huang, Wenbin AU - Zhang, Shujun AU - Yuan, Fuh-Gwo AU - Jiang, Xiaoning T2 - SMART SENSOR PHENOMENA, TECHNOLOGY, NETWORKS, AND SYSTEMS INTEGRATION 2014 AB - A flexoelectric bridge-structured microphone using bulk barium strontium titanate (Ba0.65Sr0.35TiO3 or BST) ceramic was investigated in this study. The flexoelectric microphone was installed in an anechoic box and exposed to the sound pressure emitted from a loud speaker. Charge sensitivity of the flexoelectric microphone was measured and calibrated using a reference microphone. The 1.5 mm×768 μm×50 μm micro-machined bridge-structured flexoelectric microphone has a sensitivity of 0.92 pC/Pa, while its resonance frequency was calculated to be 98.67 kHz. The analytical and experimental results show that the flexoelectric microphone has both high sensitivity and broad bandwidth, indicating that flexoelectric microphones are potential candidates for many applications. DA - 2014/// PY - 2014/// DO - 10.1117/12.2045072 VL - 9062 SP - SN - 1996-756X KW - Microphone KW - flexoelectricity KW - BST KW - micro-bridge ER - TY - JOUR TI - A new metastable precipitate phase in Mg-Gd-Y-Zr alloy AU - Zhou, H. AU - Xu, W. Z. AU - Jian, W. W. AU - Cheng, G. M. AU - Ma, X. L. AU - Guo, W. AU - Mathaudhu, S. N. AU - Wang, Q. D. AU - Zhu, Y. T. T2 - PHILOSOPHICAL MAGAZINE AB - Mg–RE alloys are among the strongest Mg-based alloys due to their unique precipitation structures. A previously unobserved metastable phase (βT) is found to coexist with reported β″ and β′ metastable phases under peak ageing conditions in a Mg–Gd–Y–Zr alloy. The position of the RE elements within the βT phase is identified using atomic-resolution high-angle annular dark field scanning transmission electron microscopy imaging, and the βT phase is shown to have an orthorhombic structure with a stoichiometry of Mg5RE. Based on these observations, a new precipitation sequence is proposed. DA - 2014/// PY - 2014/// DO - 10.1080/14786435.2014.913115 VL - 94 IS - 21 SP - 2403-2409 SN - 1478-6443 KW - magnesium alloys KW - metastable phases KW - base-centred orthorhombic structure KW - phase transformations ER - TY - JOUR TI - A Model for Quantifying System Evolvability Based on Excess and Capacity AU - Tackett, Morgan W. P. AU - Mattson, Christopher A. AU - Ferguson, Scott M. T2 - JOURNAL OF MECHANICAL DESIGN AB - An important factor in system longevity is service-phase evolvability, which is defined as the ability of a system to physically transform from one configuration to a more desirable configuration while in service. These transformations may or may not be known during the design process, and may or may not be reversible. In a different study, we examined 210 engineered systems and found that system excess and modularity allow a system to evolve while in service. Building on this observation, the present paper introduces mathematical relationships that map a system's excess to that system's ability to evolve. As introduced in this paper, this relationship is derived from elastic potential-energy theories. The use of the evolvability measure, and other related measures presented herein, are illustrated with simple examples and applied to the design of U.S. Navy nuclear aircraft carriers. Using these relationships, we show that the Navy's new Ford-class aircraft carrier is measurably more evolvable than the Nimitz-class carriers. While the ability for systems to evolve is based on excess and modularity, this paper is focused only on excess. The mapping between modularity and evolvability is the focus of another work by the authors. DA - 2014/5// PY - 2014/5// DO - 10.1115/1.4026648 VL - 136 IS - 5 SP - SN - 1050-0472 KW - reconfigurability KW - flexibility KW - adaptability KW - transformation KW - evolvability KW - service-phase evolution KW - system changes KW - system space ER - TY - JOUR TI - Virtualisation of stress distribution in heart valve tissue AU - Huang, Siyao AU - Huang, Hsiao-Ying Shadow T2 - COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING AB - This study presents an image-based finite element analysis incorporating histological photomicrographs of heart valve tissues. We report stress fields inside heart valve tissues, where heterogeneously distributed collagen fibres are responsible for transmitting forces into cells. Linear isotropic and anisotropic tissue material property models are incorporated to quantify the overall stress distributions in heart valve tissues. By establishing an effective predictive method with new computational tools and by performing virtual experiments on the heart valve tissue photomicrographs, we clarify how stresses are transferred from matrix to cell. The results clearly reveal the roles of heterogeneously distributed collagen fibres in mitigating stress developments inside heart valve tissues. Moreover, most local peak stresses occur around cell nuclei, suggesting that higher stress may be mediated by cells for biomechanical regulations. DA - 2014/// PY - 2014/// DO - 10.1080/10255842.2013.763937 VL - 17 IS - 15 SP - 1696-1704 SN - 1476-8259 KW - heart valve tissue KW - finite element method KW - collagen fibre architecture KW - stress analysis ER - TY - JOUR TI - Stretchable and Reversibly Deformable Radio Frequency Antennas Based on Silver Nanowires AU - Song, Lingnan AU - Myers, Amanda C. AU - Adams, Jacob J. AU - Zhu, Yong T2 - ACS APPLIED MATERIALS & INTERFACES AB - We demonstrate a class of microstrip patch antennas that are stretchable, mechanically tunable, and reversibly deformable. The radiating element of the antenna consists of highly conductive and stretchable material with screen-printed silver nanowires embedded in the surface layer of an elastomeric substrate. A 3-GHz microstrip patch antenna and a 6-GHz 2-element patch array are fabricated. Radiating properties of the antennas are characterized under tensile strain and agree well with the simulation results. The antenna is reconfigurable because the resonant frequency is a function of the applied tensile strain. The antenna is thus well suited for applications like wireless strain sensing. The material and fabrication technique reported here could be extended to achieve other types of stretchable antennas with more complex patterns and multilayer structures. DA - 2014/3/26/ PY - 2014/3/26/ DO - 10.1021/am405972e VL - 6 IS - 6 SP - 4248-4253 SN - 1944-8252 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84896995952&partnerID=MN8TOARS KW - silver nanowire KW - stretchable antenna KW - wireless strain sensing KW - printed electronics KW - microstrip patch antenna ER - TY - JOUR TI - Morphological Origin of Charge Transport Anisotropy in Aligned Polythiophene Thin Films AU - Brendan T. O'Connor, AU - Reid, Obadiah G. AU - Zhang, Xinran AU - Kline, R. Joseph AU - Richter, Lee J. AU - Gundlach, David J. AU - DeLongchamp, Dean M. AU - Toney, Michael F. AU - Kopidakis, Nikos AU - Rumbles, Garry T2 - ADVANCED FUNCTIONAL MATERIALS AB - The morphological origin of anisotropic charge transport in uniaxially strain aligned poly(3‐hexylthiophene) (P3HT) films is investigated. The macroscale field effect mobility anisotropy is measured in an organic thin film transistor (OTFT) configuration and compared to the local aggregate P3HT mobility anisotropy determined using time‐resolved microwave conductivity (TRMC) measurements. The field effect mobility anisotropy in highly aligned P3HT films is substantially higher than the local mobility anisotropy in the aggregate P3HT. This difference is attributed to preferentially aligned polymer tie‐chains at grain boundaries that contribute to macroscale charge transport anisotropy but not the local anisotropy. The formation of sharp grains between oriented crystalline P3HT, through tie chain removal by thermal annealing the strained aligned films, results in an order of magnitude drop in the measured field effect mobility for charge transport parallel to the strain direction. The field effect mobility anisotropy is cut in half while the local mobility anisotropy remains relatively constant. The local mobility anisotropy is found to be surprisingly low in the aligned films, suggesting that the π−π stacking direction supports charge carrier mobility on the same order of magnitude as that in the intrachain direction, possibly due to poor intrachain mobility through chain torsion. DA - 2014/6// PY - 2014/6// DO - 10.1002/adfm.201303351 VL - 24 IS - 22 SP - 3422-3431 SN - 1616-3028 KW - organic electronics KW - conducting polymers KW - organic field-effect transistors KW - polymer alignment KW - P3HT ER - TY - JOUR TI - Micron-particle transport, interactions and deposition in triple lung-airway bifurcations using a novel modeling approach AU - Feng, Y. AU - Kleinstreuer, C. T2 - JOURNAL OF AEROSOL SCIENCE AB - Particulate suspensions inhaled by humans are typically dilute and hence interactions between particles can be neglected. In such cases conventional Euler–Lagrange or Euler–Euler methods are suitable to simulate micron- or nano-particle transport and deposition in human respiratory systems. However, when challenging conditions, such as large pressure differentials, high velocity gradients and/or intense particle collisions, exist, alternative approaches for numerical analysis are required to capture fluid–particle, particle–particle, and particle–wall interactions. In the present study, the dense discrete phase model (DDPM) in conjunction with the discrete element method (DEM) have been employed to simulate micron–particle transport, interaction and deposition dynamics in different triple bifurcations (i.e., G3–G6, G6–G9, and G9–G12), using ANSYS Fluent 14.0 enhanced by user-defined functions (UDFs). In light of the relatively high computational cost when employing DDPM–DEM for such simulations throughout the human respiratory system, it may be necessary to combine different computational fluid–particle dynamics (CF–PD) models based on the local intensity of particle–particle interactions. Thus, the validity and necessity of the DDPM–DEM approach for different lung airway generations were numerically investigated, considering new parametric criteria for the use of most suitable numerical models. Specifically, the relative intensities of three major particle deposition mechanisms (i.e., inertial impaction, secondary-flow effect, and particle–particle-interaction impact) in idealized lung-airway segments were investigated. As a result, a new criterion for CF–PD model combination in terms of a relationship between inlet-particle stacking-volume fraction, ϕ, and percentage-of-fate changing particles, Δβp, is proposed. Visualizations of the fluid–particle dynamics in bifurcating airways have been provided as well. Results of this study pave the way for accurate and cost-effective CF–PD simulations of lung-aerosol dynamics, aiming at the improvement of respiratory dose estimation for health risk assessment in case of toxic particles and for treatment options in case of therapeutic particles. DA - 2014/5// PY - 2014/5// DO - 10.1016/j.jaerosci.2014.01.003 VL - 71 SP - 1-15 SN - 1879-1964 KW - Dense discrete phase model (DDPM) KW - Discrete element method (DEM) KW - Lung aerosol dynamics KW - Triple bifurcations KW - Particle-particle interactions KW - Model combination criteria ER - TY - JOUR TI - Magnetohydrodynamic viscous flow over a nonlinearly moving surface: Closed-form solutions AU - Fang, Tiegang T2 - EUROPEAN PHYSICAL JOURNAL PLUS DA - 2014/5/26/ PY - 2014/5/26/ DO - 10.1140/epjp/i2014-14092-4 VL - 129 IS - 5 SP - SN - 2190-5444 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84907522318&partnerID=MN8TOARS ER - TY - JOUR TI - Laser interaction effects of electromagnetic absorption and microstructural defects on hot-spot formation in RDX-PCTFE energetic aggregates AU - Brown, Judith A. AU - LaBarbera, Darrell A. AU - Zikry, Mohammed A. T2 - MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING AB - Hot-spot formation in energetic aggregates subjected to dynamic pressure loading and laser irradiation has been investigated. Specialized finite-element techniques with a dislocation-density-based crystalline plasticity constitutive formulation and thermo-mechanical coupling of heat conduction, adiabatic heating, laser heating and thermal decomposition were used to predict hot-spot formation in RDX–polymer aggregates subjected to dynamic pressures and laser energies. The effects of the electromagnetic absorption coefficient coupled with void distribution and spacing, grain morphology, crystal–binder interactions and dislocation densities were analyzed to determine their influence on the time, location and mechanisms of hot-spot formation. Four different mechanisms for hot-spot initiation under dynamic laser and pressure loads were identified, which depend on the localization of plastic shear strain and laser heat absorption within the aggregate. The predictions indicate that hot-spot formation is accelerated by higher absorption coefficients and by localized plastic deformations that occur in areas of significant laser heating. DA - 2014/7// PY - 2014/7// DO - 10.1088/0965-0393/22/5/055013 VL - 22 IS - 5 SP - SN - 1361-651X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84903137725&partnerID=MN8TOARS KW - energetic materials KW - hot spots KW - laser KW - dislocation-density ER - TY - JOUR TI - Integration of epitaxial permalloy on Si (100) through domain matching epitaxy paradigm AU - Rao, S. S. AU - Prater, J. T. AU - Wu, Fan AU - Nori, Sudhakar AU - Kumar, D. AU - Narayan, J. T2 - CURRENT OPINION IN SOLID STATE & MATERIALS SCIENCE AB - Abstract This paper addresses epitaxial integration of magnetic materials with Si (1 0 0) based solid state devices. Epitaxial Ni82.5Fe17.5 (permalloy, Py) thin films have been synthesized by pulsed laser deposition (PLD) on Si (1 0 0) using MgO/TiN as a template buffer. This epitaxial growth of these large lattice misfit systems was achieved through domain matching epitaxy (DME). The in-plane XRD pattern and selective area electron diffraction (SAED) results clearly indicate cube-on-cube epitaxial alignment. The bright field TEM image of Py/MgO/TiN/Si (1 0 0) heterostructure infers a Py layer thickness of ∼30 nm, with a well aligned island (150–200 nm) structure that is consistent with Volmer–Weber type growth. Magnetization data collected at 4 K and 300 K indicates that the easy axis of the magnetization lies in the plane of the Py. In addition, we have observed an intrinsic positive exchange bias (PEB) field of ∼104 Oe, where the magnetic hysteresis loop is shifted toward the positive field axis under zero field cooling conditions. DA - 2014/2// PY - 2014/2// DO - 10.1016/j.cossms.2013.07.004 VL - 18 IS - 1 SP - 1-5 SN - 1879-0348 KW - Permalloy KW - Pulsed laser deposition KW - Coercive field KW - Exchange bias KW - Domain matching epitaxy ER - TY - JOUR TI - Flow, heat, and species transfer over a stretching plate considering coupled Stefan blowing effects from species transfer AU - Fang, Tiegang AU - Jing, Wei T2 - COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION AB - In this paper, we investigate the flow, heat and mass transfer of a viscous fluid flow over a stretching sheet by including the blowing effects of mass transfer under high flux conditions. Mass transfer in this work means species transfer and is different from mass transpiration for permeable walls. The new contribution from this work is, for the first time, to consider the coupled blowing effects from massive species transfer on flow, heat, and species transfer for a stretching plate. Based on the exact solutions of the momentum equations, which are valid for the whole Navier–Stokes equations, the energy and mass transfer equations are solved exactly and the effects of the blowing parameter, the Schmidt number, and the Prandtl number on the flow, heat and mass transfer are presented and discussed. The solution is given in terms of an incomplete Gamma function. It is found the coupled blowing effects due to mass transfer can have significant influences on velocity profiles, drag, heat flux, as well as temperature and concentration profiles. These solutions provide rare results with closed form analytical expressions and can be used as benchmark problem for numerical code validation. DA - 2014/9// PY - 2014/9// DO - 10.1016/j.cnsns.2014.02.009 VL - 19 IS - 9 SP - 3086-3097 SN - 1878-7274 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84897073047&partnerID=MN8TOARS KW - Navier-Stokes equation KW - Similarity equation KW - Stretching surface KW - Analytical solution KW - Heat transfer KW - Mass transfer KW - Blowing effect ER - TY - JOUR TI - Fabricating copper components with electron beam melting AU - Frigola, P. AU - Harrysson, O. A. AU - Horn, T. J. AU - West, H. A. AU - Aman, R. L. AU - Rigsbee, J. M. AU - Ramirez, D. A. AU - Murr, L. E. AU - Medina, F. AU - Wicker, R. B. AU - Rodriguez, E. T2 - Advanced Materials & Processes DA - 2014/// PY - 2014/// VL - 172 IS - 7 SP - 20-24 ER - TY - JOUR TI - Control of Polynomial Nonlinear Systems Using Higher Degree Lyapunov Functions AU - Yang, Shuowei AU - Wu, Fen T2 - JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME AB - In this paper, we propose a new control design approach for polynomial nonlinear systems based on higher degree Lyapunov functions. To derive higher degree Lyapunov functions and polynomial nonlinear controllers effectively, the original nonlinear systems are augmented under the rule of power transformation. The augmented systems have more state variables and the additional variables represent higher order combinations of the original ones. As a result, the stabilization and L2 gain control problems with higher degree Lyapunov functions can be recast to the search of quadratic Lyapunov functions for augmented nonlinear systems. The sum-of-squares (SOS) programming is then used to solve the quadratic Lyapunov function of augmented state variables (higher degree in terms of original states) and its associated nonlinear controllers through convex optimization problems. The proposed control approach has also been extended to polynomial nonlinear systems subject to actuator saturations for better performance including domain of attraction (DOA) expansion and regional L2 gain minimization. Several examples are used to illustrate the advantages and benefits of the proposed approach for unsaturated and saturated polynomial nonlinear systems. DA - 2014/5// PY - 2014/5// DO - 10.1115/1.4026172 VL - 136 IS - 3 SP - SN - 1528-9028 ER - TY - JOUR TI - An automated phase correction algorithm for retrieving permittivity and permeability of electromagnetic metamaterials AU - Cao, Z. X. AU - Yuan, F. G. AU - Li, L. H. T2 - AIP ADVANCES AB - To retrieve complex-valued effective permittivity and permeability of electromagnetic metamaterials (EMMs) based on resonant effect from scattering parameters using a complex logarithmic function is not inevitable. When complex values are expressed in terms of magnitude and phase, an infinite number of permissible phase angles is permissible due to the multi-valued property of complex logarithmic functions. Special attention needs to be paid to ensure continuity of the effective permittivity and permeability of lossy metamaterials as frequency sweeps. In this paper, an automated phase correction (APC) algorithm is proposed to properly trace and compensate phase angles of the complex logarithmic function which may experience abrupt phase jumps near the resonant frequency region of the concerned EMMs, and hence the continuity of the effective optical properties of lossy metamaterials is ensured. The algorithm is then verified to extract effective optical properties from the simulated scattering parameters of the four different types of metamaterial media: a cut-wire cell array, a split ring resonator (SRR) cell array, an electric-LC (E-LC) resonator cell array, and a combined SRR and wire cell array respectively. The results demonstrate that the proposed algorithm is highly accurate and effective. DA - 2014/6// PY - 2014/6// DO - 10.1063/1.4882155 VL - 4 IS - 6 SP - SN - 2158-3226 ER - TY - JOUR TI - An Improved Wave-Vector Frequency-Domain Method for Nonlinear Wave Modeling AU - Jing, Yun AU - Tao, Molei AU - Cannata, Jonathan T2 - IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL AB - In this paper, a recently developed wave-vector frequency-domain method for nonlinear wave modeling is improved and verified by numerical simulations and underwater experiments. Higher order numeric schemes are proposed that significantly increase the modeling accuracy, thereby allowing for a larger step size and shorter computation time. The improved algorithms replace the left-point Riemann sum in the original algorithm by the trapezoidal or Simpson's integration. Plane waves and a phased array were first studied to numerically validate the model. It is shown that the left-point Riemann sum, trapezoidal, and Simpson's integration have first-, second-, and third-order global accuracy, respectively. A highly focused therapeutic transducer was then used for experimental verifications. Short high-intensity pulses were generated. 2-D scans were conducted at a prefocal plane, which were later used as the input to the numerical model to predict the acoustic field at other planes. Good agreement is observed between simulations and experiments. DA - 2014/3// PY - 2014/3// DO - 10.1109/tuffc.2014.2935 VL - 61 IS - 3 SP - 515-524 SN - 1525-8955 ER - TY - JOUR TI - A two population model of prion transport through a tunnelling nanotube AU - Kuznetsov, I. A. AU - Kuznetsov, A. V. T2 - COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING AB - This article develops a two prion population model that simulates prion trafficking between an infected dendritic cell and a neuron. The situation when the two cells are connected by a tunnelling nanotube (TNT) is simulated. Two mechanisms of prion transport are considered: lateral diffusion in the TNT membrane and active actin-dependent transport inside endocytic vesicles that are propelled by myosin Va molecular motors. Analytical solutions describing prion concentrations and fluxes are obtained. Numerical results are compared with those predicted by a single prion population model that relies on a single reaction-diffusion equation and accounts for the two modes of prion transport in an effective way. DA - 2014/// PY - 2014/// DO - 10.1080/10255842.2013.763938 VL - 17 IS - 15 SP - 1705-1715 SN - 1476-8259 KW - membrane nanotubes KW - prions KW - molecular motors KW - traffic KW - modelling ER - TY - JOUR TI - The effect of 1% tropicamide-induced mydriasis and cycloplegia on spherical refraction of the adult horse AU - McMullen, Richard J., Jr. AU - Davidson, Michael G. AU - Gilger, Brian C. T2 - VETERINARY OPHTHALMOLOGY AB - Abstract Objectives To determine the effects of tropicamide 1% on the refractive state of the adult equine globe and identify the most appropriate time period (in relation to mydriasis) to perform streak retinoscopy. Animals studied Eight university‐owned mares of various ages and breeds. Procedures Topical tropicamide 1% was applied to one randomly selected eye from each of the horses to induce mydriasis and cycloplegia. The contralateral eyes served as controls. Streak retinoscopy and pupillometry were performed prior to, and every 5 min after tropicamide 1% installation for 90 min. Results All values are expressed as mean ± SD . Both horizontal (2.8 ± 0.74 mm) and vertical (7.3 ± 1.29 mm) mean pupil diameters increased significantly ( P < 0.04) in the treatment eyes compared with the control eyes (horizontal [0.48 ± 0.85 mm] and vertical [1.06 ± 1.31 mm] pupil diameter). No significant differences in the refractive states of the treatment (horizontal: +0.25 ± 0.43 D and vertical: +0.41 ± 0.37 D) or control (horizontal: +0.34 ± 0.39 D and vertical: +0.41 ± 0.37 D) eyes were identified at any time point. Three of the eight treatment eyes demonstrated blurry or reversing streak reflexes during streak retinoscopy evaluation following the application of topical tropicamide 1%. Conclusions While these reflexes did not significantly influence streak retinoscopy results, their presence may subjectively influence a novice retinoscopist's ability to obtain accurate results. Therefore, optimal streak retinoscopy results may be obtained prior to, or 40‐ to 45‐min following the application of topical tropicamide 1%, once near‐maximal dilation has been achieved. DA - 2014/3// PY - 2014/3// DO - 10.1111/vop.12055 VL - 17 IS - 2 SP - 120-125 SN - 1463-5224 KW - cycloplegia KW - equine ophthalmology KW - mydriasis KW - pupillometry KW - streak retinoscopy KW - tropicamide ER - TY - JOUR TI - Reliability-based vehicle safety assessment and design optimization of roadway radius and speed limit in windy environments AU - Shin, J. AU - Lee, I. T2 - Journal of Mechanical Design (New York, N.Y. : 1990) DA - 2014/// PY - 2014/// VL - 136 IS - 8 ER - TY - JOUR TI - Organic photovoltaic cells with controlled polarization sensitivity AU - Awartani, Omar AU - Kudenov, Michael W. AU - Brendan T. O'Connor, T2 - APPLIED PHYSICS LETTERS AB - In this study, we demonstrate linearly polarized organic photovoltaic cells with a well-controlled level of polarization sensitivity. The polarized devices were created through the application of a large uniaxial strain to the bulk heterojunction poly(3-hexylthiophene):Phenyl-C61-butyric acid methyl ester (P3HT:PCBM) film and printing the plastically deformed active layer onto a PEDOT:PSS and indium tin oxide coated glass substrate. The P3HT:PCBM layer is processed such that it is able to accommodate high strains (over 100%) without fracture. After printing the strained films, thermal annealing is used to optimize solar cell performance while maintaining polarization sensitivity. A dichroic ratio and short circuit current ratio of ≈6.1 and ≈1.6 were achieved, respectively. DA - 2014/3/3/ PY - 2014/3/3/ DO - 10.1063/1.4868041 VL - 104 IS - 9 SP - SN - 1077-3118 ER - TY - JOUR TI - Multi-Objective Design Optimization of a Variable Geometry Spray Fuel Injector AU - Archer, J. R. AU - Fang, Tiegang AU - Ferguson, Scott AU - Buckner, Gregory D. T2 - JOURNAL OF MECHANICAL DESIGN AB - This paper explores the simulation-based design optimization of a variable geometry spray (VGS) fuel injector. A multi-objective genetic algorithm (MOGA) is interfaced with commercial computational fluid dynamics (CFD) software and high performance computing capabilities to evaluate the spray characteristics of each VGS candidate design. A three-point full factorial experimental design is conducted to identify significant design variables and to better understand possible variable interactions. The Pareto frontier of optimal designs reveals the inherent tradeoff between two performance objectives—actuator stroke and spray angle sensitivity. Analysis of these solutions provides insight into dependencies between design parameters and the performance objectives and is used to assess possible performance gains with respect to initial prototype configurations. These insights provide valuable design information for the continued development of this VGS technology. DA - 2014/4// PY - 2014/4// DO - 10.1115/1.4026263 VL - 136 IS - 4 SP - SN - 1050-0472 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84903773146&partnerID=MN8TOARS ER - TY - JOUR TI - Large-Eddy Simulation/Reynolds-Averaged Navier-Stokes Simulations of High-Speed Mixing Processes AU - Zilberter, Ilya A. AU - Edwards, Jack R. T2 - AIAA JOURNAL AB - A large-eddy simulation/Reynolds-averaged Navier–Stokes model is applied to three high-speed mixing layers and three sonic injection flows to generate data suitable for evaluating two current Reynolds-averaged Navier–Stokes models for turbulent mass diffusivity. These models solve transport equations for concentration variance and dissipation rate and differ in the constitutive relation for the turbulent mass diffusivity and the form of the evolution equation for the dissipation rate. The predictive capability of the large-eddy simulation/Reynolds-averaged Navier–Stokes model is assessed through simulations of an air–air mixing-layer experiment and a sonic ethylene injection into a Mach 2.0 airstream. This model provides good predictions of the mean velocity, turbulence intensity, and rms temperature fluctuation throughout the shear layer flowfield but slightly over-predicts the spreading rate of the mixing layer. The simulation of the sonic injection is in generally good agreement with the experiment but underpredicts the level of jet entrainment. Four other large-eddy simulation/Reynolds-averaged Navier–Stokes data sets, involving the replacement of the lower airstream in the mixing-layer configuration by an argon stream and a helium stream, and a replacement of the injectant gas in the sonic injection experiment with argon and helium are also generated. All data sets are “mined” to extract turbulent mass diffusivities, concentration variances, and scalar dissipation rates associated with the resolved eddy motion. The results show that both models can be optimized to achieve a good match with the exact scalar variance production rate. DA - 2014/7// PY - 2014/7// DO - 10.2514/1.j052745 VL - 52 IS - 7 SP - 1486-1501 SN - 1533-385X ER - TY - JOUR TI - Interfacial sliding and buckling of monolayer graphene on a stretchable substrate AU - Jiang, T. AU - Huang, R. AU - Zhu, Y. T2 - Advanced Functional Materials AB - The nonlinear mechanical response of monolayer graphene on polyethylene terephthalate (PET) is characterised using in‐situ Raman spectroscopy and atomic force microscopy. While interfacial stress transfer leads to tension in graphene as the PET substrate is stretched, retraction of the substrate during unloading imposes compression in the graphene. Two interfacial failure mechanisms, shear sliding under tension and buckling under compression, are identified. Using a nonlinear shear‐lag model, the interfacial shear strength is found to range between 0.46 and 0.69 MPa. The critical strain for onset of interfacial sliding is ∼0.3%, while the maximum strain that can be transferred to graphene ranges from 1.2% to 1.6% depending on the interfacial shear strength and graphene size. Beyond a critical compressive strain of around −0.7%, buckling ridges are observed after unloading. The results from this work provide valuable insight and design guidelines for a broad spectrum of applications of graphene and other 2D nanomaterials, such as flexible and stretchable electronics, strain sensing, and nanocomposites. DA - 2014/// PY - 2014/// DO - 10.1002/adfm.201301999 VL - 24 IS - 3 SP - 396-402 ER - TY - JOUR TI - Impact of Fluid-Structure Interaction on Direct Tumor-Targeting in a Representative Hepatic Artery System AU - Childress, Emily M. AU - Kleinstreuer, Clement T2 - ANNALS OF BIOMEDICAL ENGINEERING DA - 2014/3// PY - 2014/3// DO - 10.1007/s10439-013-0910-7 VL - 42 IS - 3 SP - 461-474 SN - 1573-9686 KW - Optimal tumor-targeting KW - Drug particles KW - Fluid-particle dynamics KW - Fluid-structure interaction KW - Rigid-wall assumption ER - TY - JOUR TI - Hybrid Large-Eddy/Reynolds-Averaged Navier-Stokes Simulations of Flow Through a Model Scramjet AU - Potturi, Amarnatha S. AU - Edwards, Jack R. T2 - AIAA JOURNAL AB - The reactive flow through a model scramjet combustor is simulated using a hybrid large-eddy/Reynolds-averaged Navier–Stokes technique. The scramjet configuration considered is similar to the one investigated at the Institute for Chemical Propulsion of the DLR, German Aerospace Center. The model scramjet consists of 15 fuel-injecting holes, located on the base of a wedge-shaped fuel injector, through which hydrogen is injected at sonic conditions. In the present study, only five of the 15 fuel-injecting holes are considered, and periodicity is assumed in the spanwise direction. Several parametric studies are conducted with a view toward determining the sensitivities of the predictions to modeling and algorithmic variations. Different grids (two different topologies), flux reconstruction methods (total variation diminishing and piecewise parabolic method), reaction mechanisms, and inflow boundary conditions (uniform and nonuniform) are used. To enhance fuel–air mixing, a synthetic eddy method is used to generate turbulence in the injector boundary layers and the hydrogen jets. Finally, a partially stirred reactor-type subgrid combustion model is used as a subgrid closure for the species production rates. The results show that, in all the cases, a lifted flame is predicted with varying standoff distances, heat releases, and shapes. DA - 2014/7// PY - 2014/7// DO - 10.2514/1.j052595 VL - 52 IS - 7 SP - 1417-1429 SN - 1533-385X ER - TY - JOUR TI - Forced convection in a parallel-plate channel occupied by a nanofluid or a porous medium saturated by a nanofluid (vol 70, pg 430, 2014) AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER DA - 2014/9// PY - 2014/9// DO - 10.1016/j.ijheatmasstransfer.2014.04.051 VL - 76 SP - 534-534 SN - 1879-2189 ER - TY - JOUR TI - Breakup of liquid jets from non-circular orifices AU - Sharma, Priyesh AU - Fang, Tiegang T2 - EXPERIMENTS IN FLUIDS DA - 2014/2// PY - 2014/2// DO - 10.1007/s00348-014-1666-z VL - 55 IS - 2 SP - SN - 1432-1114 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84892389249&partnerID=MN8TOARS ER - TY - JOUR TI - Blasius flow with non-linear Rosseland thermal radiation AU - Pantokratoras, Asterios AU - Fang, Tiegang T2 - MECCANICA DA - 2014/6// PY - 2014/6// DO - 10.1007/s11012-014-9911-3 VL - 49 IS - 6 SP - 1539-1545 SN - 1572-9648 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84901607173&partnerID=MN8TOARS KW - Thermal radiation KW - Non-linear Rosseland approximation KW - Heat transfer KW - Boundary layers KW - Blasius flow ER - TY - JOUR TI - Wearable multifunctional sensors using printed stretchable conductors made of silver nanowires AU - Yao, Shanshan AU - Zhu, Yong T2 - NANOSCALE AB - Considerable efforts have been made to achieve highly sensitive and wearable sensors that can simultaneously detect multiple stimuli such as stretch, pressure, temperature or touch. Here we develop highly stretchable multifunctional sensors that can detect strain (up to 50%), pressure (up to ∼1.2 MPa) and finger touch with high sensitivity, fast response time (∼40 ms) and good pressure mapping function. The reported sensors utilize the capacitive sensing mechanism, where silver nanowires are used as electrodes (conductors) and Ecoflex is used as a dielectric. The silver nanowire electrodes are screen printed. Our sensors have been demonstrated for several wearable applications including monitoring thumb movement, sensing the strain of the knee joint in patellar reflex (knee-jerk) and other human motions such as walking, running and jumping from squatting, illustrating the potential utilities of such sensors in robotic systems, prosthetics, healthcare and flexible touch panels. DA - 2014/// PY - 2014/// DO - 10.1039/c3nr05496a VL - 6 IS - 4 SP - 2345-2352 SN - 2040-3372 ER - TY - JOUR TI - Low-Frequency Unsteadiness of Shock Wave/Turbulent Boundary Layer Interactions AU - Clemens, Noel T. AU - Narayanaswamy, Venkateswaran T2 - ANNUAL REVIEW OF FLUID MECHANICS, VOL 46 AB - Shock wave/boundary layer interactions occur in a wide range of supersonic internal and external flows, and often these interactions are associated with turbulent boundary layer separation. The resulting separated flow is associated with large-scale, low-frequency unsteadiness whose cause has been the subject of much attention and debate. In particular, some researchers have concluded that the source of low-frequency motions is in the upstream boundary layer, whereas others have argued for a downstream instability as the driving mechanism. Owing to substantial recent activity, we are close to developing a comprehensive understanding, albeit only in simplified flow configurations. A plausible model is that the interaction responds as a dynamical system that is forced by external disturbances. The low-frequency dynamics seem to be adequately described by a recently proposed shear layer entrainment-recharge mechanism. Upstream boundary layer fluctuations seem to be an important source of disturbances, but the evidence suggests that their impact is reduced with increasing size of the separated flow. DA - 2014/// PY - 2014/// DO - 10.1146/annurev-fluid-010313-141346 VL - 46 SP - 469-492 SN - 0066-4189 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84891810972&partnerID=MN8TOARS KW - supersonic KW - separation KW - bubble KW - reattachment KW - instability ER - TY - JOUR TI - Hybrid Three-Dimensional (3-D) Woven Thick Composite Architectures in Bending AU - Pankow, Mark AU - Quabili, Ashiq AU - Yen, Chian-Fong T2 - JOM DA - 2014/2// PY - 2014/2// DO - 10.1007/s11837-013-0825-7 VL - 66 IS - 2 SP - 255-260 SN - 1543-1851 ER - TY - JOUR TI - High-temperature acoustic emission sensing tests using a yttrium calcium oxyborate sensor AU - Johnson, J. A. AU - Kim, K. AU - Zhang, S. J. AU - Wu, D. AU - Jiang, X. N. T2 - IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control AB - Piezoelectric materials have been broadly utilized in acoustic emission sensors, but are often hindered by the loss of piezoelectric properties at temperatures in the 500°C to 700°C range or higher. In this paper, a piezoelectric acoustic emission sensor was designed and fabricated using yttrium calcium oxyborate (YCOB) single crystals, followed by Hsu-Nielsen tests for high-temperature (>700°C) applications. The sensitivity of the YCOB sensor was found to have minimal degradation with increasing temperature up to 1000°C. During Hsu-Nielsen tests with a steel bar, this YCOB acoustic sensor showed the ability to detect zero-order symmetric and antisymmetric modes at 30 and 120 kHz, respectively, as well as distinguish a first-order antisymmetric mode at 240 kHz at elevated temperatures up to 1000°C. The frequency characteristics of the signal were verified using a finite-element model and wavelet transformation analysis. DA - 2014/// PY - 2014/// DO - 10.1109/tuffc.2014.6805694 VL - 61 IS - 5 SP - 805-814 ER - TY - JOUR TI - High-Temperature Piezoelectric Sensing AU - Jiang, Xiaoning AU - Kim, Kyungrim AU - Zhang, Shujun AU - Johnson, Joseph AU - Salazar, Giovanni T2 - SENSORS AB - Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented. DA - 2014/1// PY - 2014/1// DO - 10.3390/s140100144 VL - 14 IS - 1 SP - 144-169 SN - 1424-8220 KW - high-temperature sensing KW - high-temperature piezoelectrics KW - piezoelectric sensors KW - high-temperature piezoelectric sensors ER - TY - JOUR TI - Flow and Mass Transfer for an Unsteady Stagnation-Point Flow Over a Moving Wall Considering Blowing Effects AU - Fang, Tiegang T2 - JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME AB - In this paper, the flow and mass transfer of a two-dimensional unsteady stagnation-point flow over a moving wall, considering the coupled blowing effect from mass transfer, is studied. Similarity equations are derived and solved in a closed form. The flow solution is an exact solution to the two-dimensional unsteady Navier–Stokes equations. An analytical solution of the boundary layer mass transfer equation is obtained together with the momentum solution. The examples demonstrate the significant impacts of the blowing effects on the flow and mass transfer characteristics. A higher blowing parameter results in a lower wall stress and thicker boundary layers with less mass transfer flux at the wall. The higher wall moving parameters produce higher mass transfer flux and blowing velocity. The Schmidt parameters generate a local maximum for the mass transfer flux and blowing velocity under given wall moving and blowing parameters. DA - 2014/7// PY - 2014/7// DO - 10.1115/1.4026665 VL - 136 IS - 7 SP - SN - 1528-901X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84900014339&partnerID=MN8TOARS KW - similarity equation KW - unsteady stagnation-point flow KW - moving wall KW - Navier-Stokes equations KW - mass transfer KW - blowing effect ER - TY - JOUR TI - Effects of electric fields on stabilized lifted propane flames AU - Hutchins, A. R. AU - Reach, W. A. AU - Kribs, J. D. AU - Lyons, K. M. T2 - Journal of Energy Resources Technology DA - 2014/// PY - 2014/// VL - 136 IS - 2 ER - TY - JOUR TI - Effect of the Magnetic Pole Arrangement on the Surface Roughness of STS 304 by Magnetic Abrasive Machining AU - Yoon, Sung AU - Tu, Juei-Feng AU - Lee, Jun Ho AU - Yang, Gyun Eui AU - Mun, Sang Don T2 - INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING DA - 2014/7// PY - 2014/7// DO - 10.1007/s12541-014-0467-x VL - 15 IS - 7 SP - 1275-1281 SN - 2005-4602 KW - Magnetic pole arrangement KW - Inner surface roughness KW - Magnetic pole vibration device KW - Proximity sensor KW - Removed weight ER - TY - JOUR TI - A preliminary engineering design of intravascular dual-frequency transducers for contrast-enhanced acoustic angiography and molecular imaging AU - Ma, J. G. AU - Martin, K. H. AU - Dayton, P. A. AU - Jiang, X. N. T2 - IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control AB - Current intravascular ultrasound (IVUS) probes are not optimized for contrast detection because of their design for high-frequency fundamental-mode imaging. However, data from transcutaneous contrast imaging suggests the possibility of utilizing contrast ultrasound for molecular imaging or vasa vasorum assessment to further elucidate atherosclerotic plaque deposition. This paper presents the design, fabrication, and characterization of a small-aperture (0.6 × 3 mm) IVUS probe optimized for high-frequency contrast imaging. The design utilizes a dual-frequency (6.5 MHz/30 MHz) transducer arrangement for exciting microbubbles at low frequencies (near their resonance) and detecting their broadband harmonics at high frequencies, minimizing detected tissue backscatter. The prototype probe is able to generate nonlinear microbubble response with more than 1.2 MPa of rarefractional pressure (mechanical index: 0.48) at 6.5 MHz, and is also able to detect microbubble response with a broadband receiving element (center frequency: 30 MHz, -6-dB fractional bandwidth: 58.6%). Nonlinear super-harmonics from microbubbles flowing through a 200-μm-diameter micro-tube were clearly detected with a signal-to-noise ratio higher than 12 dB. Preliminary phantom imaging at the fundamental frequency (30 MHz) and dual-frequency super-harmonic imaging results suggest the promise of small aperture, dual-frequency IVUS transducers for contrast-enhanced IVUS imaging. DA - 2014/// PY - 2014/// DO - 10.1109/tuffc.2014.6805699 VL - 61 IS - 5 SP - 870-880 ER - TY - JOUR TI - Stabilizing carbon nanotube yarns using chemical vapor infiltration AU - Thiagarajan, V. AU - Wang, X. AU - Bradford, P. D. AU - Zhu, Y. T. AU - Yuan, F. G. T2 - COMPOSITES SCIENCE AND TECHNOLOGY AB - Carbon nanotube (CNT) yarns exhibit high strength, low density, and relatively good conductivity and piezoresistivity, which makes them an ideal candidate for many advanced applications such as reinforcements for multifunctional composites. However, CNT yarns usually lack the required property stability under load. In this paper a method for stabilizing CNT yarn using chemical vapor infiltration (CVI) to infiltrate and deposit pyrocarbon into CNT yarns is reported. The deposited pyrocarbon effectively binds neighboring CNTs to inhibit inter-nanotube sliding under load, which consequently stabilize the CNT yarns. Relaxation tests showed that compared to pristine CNT yarns, the stabilized yarns have higher electrical stability as well as load retention (∼93% versus ∼61%). There was also a concomitant increase in density along with improved electrical conductivity, mechanical strength and stiffness. Furthermore, under sonication the CVI treated yarns resisted disintegration, making them suitable for electrochemical applications. DA - 2014/1/10/ PY - 2014/1/10/ DO - 10.1016/j.compscitech.2013.10.008 VL - 90 SP - 82-87 SN - 1879-1050 KW - Carbon nanotubes KW - Nano-composites KW - Electrical properties KW - Mechanical properties KW - Scanning electron microscopy (SEM) KW - Chemical vapor infiltration (CVI) ER - TY - JOUR TI - Natural convective boundary-layer flow of a nanofluid past a vertical plate: A revised model AU - Kuznetsov, A. V. AU - Nield, D. A. T2 - INTERNATIONAL JOURNAL OF THERMAL SCIENCES AB - The problem of natural convective boundary-layer flow of a nanofluid past a vertical plate is revisited. The model, which includes the effects of Brownian motion and thermophoresis, is revised so that the nanofluid particle fraction on the boundary is passively rather than actively controlled. In this respect the model is more realistic physically than that employed by previous authors. DA - 2014/3// PY - 2014/3// DO - 10.1016/j.ijthermalsci.2013.10.007 VL - 77 SP - 126-129 SN - 1778-4166 KW - Nanofluid KW - Brownian motion KW - Thermophoresis KW - Natural convection KW - Boundary layer KW - Vertical plate ER - TY - JOUR TI - Microstructurally induced computational and material instabilities AU - Lee, W. M. AU - Zikry, M. A. T2 - INTERNATIONAL JOURNAL OF PLASTICITY AB - Abstract A dislocation-density based finite strain crystal plasticity finite element model and an hourglass strain measure orthogonal to the linear velocity field were used to investigate microstructural effects on deformation and hourglass instability. An aluminum aggregate was modeled in quasi-static plane strain tension and compression, and the effects of the presence of manganese-based dispersed particles were investigated. Both local plastic deformation and the presence of these dispersed particles can trigger hourglass instabilities, which can be mistaken for deformation or failure modes. These hourglass modes occur due to the difference in the deformability of neighboring elements or regions and the associated energy modes associated with hourglassing, and the proposed computational methodology can be used to delineate between failure modes and numerical instabilities. DA - 2014/1// PY - 2014/1// DO - 10.1016/j.ijplas.2013.06.011 VL - 52 SP - 95-104 SN - 1879-2154 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84888199883&partnerID=MN8TOARS KW - Hourglass KW - Microstructure KW - Plasticity KW - Instability KW - Large-strain ER - TY - JOUR TI - Mechanical Properties of Silicon Carbide Nanowires: Effect of Size-Dependent Defect Density AU - Cheng, Guangming AU - Chang, Tzu-Hsuan AU - Qin, Qingquan AU - Huang, Hanchen AU - Zhu, Yong T2 - NANO LETTERS AB - This paper reports quantitative mechanical characterization of silicon carbide (SiC) nanowires (NWs) via in situ tensile tests inside scanning electron microscopy using a microelectromechanical system. The NWs are synthesized using the vapor-liquid-solid process with growth direction of ⟨111⟩. They consist of three types of structures, pure face-centered cubic (3C) structure, 3C structure with an inclined stacking fault (SF), and highly defective structure, in a periodic fashion along the NW length. The SiC NWs are found to deform linear elastically until brittle fracture. Their fracture origin is identified in the 3C structures with inclined SFs, rather than the highly defective structures. The fracture strength increases as the NW diameter decreases from 45 to 17 nm, approaching the theoretical strength of 3C SiC. The size effect on fracture strength of SiC NWs is attributed to the size-dependent defect density rather than the surface effect that is dominant for single crystalline NWs. DA - 2014/2// PY - 2014/2// DO - 10.1021/nl404058r VL - 14 IS - 2 SP - 754-758 SN - 1530-6992 KW - Size effect KW - ultrahigh strength KW - in situ tensile testing KW - brittle fracture KW - nanomechanics ER - TY - JOUR TI - Local Thermal Non-equilibrium and Heterogeneity Effects on the Onset of Convection in an Internally Heated Porous Medium AU - Kuznetsov, A. V. AU - Nield, D. A. T2 - TRANSPORT IN POROUS MEDIA DA - 2014/3// PY - 2014/3// DO - 10.1007/s11242-013-0258-3 VL - 102 IS - 1 SP - 15-30 SN - 1573-1634 KW - Local thermal non-equilibrium KW - Porous medium KW - Instability KW - Natural convection KW - Heterogeneity ER - TY - JOUR TI - Local Thermal Non-Equilibrium and Heterogeneity Effects on the Onset of Convection in a Layered Porous Medium AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - TRANSPORT IN POROUS MEDIA DA - 2014/3// PY - 2014/3// DO - 10.1007/s11242-013-0224-0 VL - 102 IS - 1 SP - 1-13 SN - 1573-1634 KW - Local thermal non-equilibrium KW - Porous medium KW - Instability KW - Natural convection ER - TY - JOUR TI - IR-MALDESI Mass Spectrometry Imaging of Biological Tissue Sections Using Ice as a Matrix AU - Robichaud, Guillaume AU - Barry, Jeremy A. AU - Muddiman, David C. T2 - JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY AB - Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) mass spectrometry imaging of biological tissue sections using a layer of deposited ice as an energy-absorbing matrix was investigated. Dynamics of plume ablation were first explored using a nanosecond exposure shadowgraphy system designed to simultaneously collect pictures of the plume with a camera and collect the Fourier transform ion cyclotron resonance FT-ICR mass spectrum corresponding to that same ablation event. Ablation of fresh tissue analyzed with and without using ice as a matrix were compared using this technique. Effect of spot-to-spot distance, number of laser shots per pixel, and tissue condition (matrix) on ion abundance were also investigated for 50 μm-thick tissue sections. Finally, the statistical method called design of experiments was used to compare source parameters and determine the optimal conditions for IR-MALDESI of tissue sections using deposited ice as a matrix. With a better understanding of the fundamentals of ablation dynamics and a systematic approach to explore the experimental space, it was possible to improve ion abundance by nearly one order of magnitude. DA - 2014/3// PY - 2014/3// DO - 10.1007/s13361-013-0787-6 VL - 25 IS - 3 SP - 319-328 SN - 1879-1123 KW - Mass spectrometry imaging KW - IR-MALDESI KW - Tissue ablation KW - Shadowgraphy ER - TY - JOUR TI - Guided wave generation, sensing and damage detection using in-plane shear piezoelectric wafers AU - Zhou, Wensong AU - Li, Hui AU - Yuan, Fuh-Gwo T2 - SMART MATERIALS AND STRUCTURES AB - This work presents guided wave generation, sensing, and damage detection in metallic plates using in-plane shear (d36 type) piezoelectric wafers as actuators and sensors. The conventional lead zirconate titanate (PZT) based on induced in-plane normal strain (d31 type) has been widely used to excite and receive guided waves in plates, pipes or thin-walled structures. The d36 type of piezoelectric wafer, however, induces in-plane (or called face) shear deformation in the plane normal to its polarization direction. This form of electromechanical coupling generates more significant shear horizontal (SH) waves in certain wave propagation directions, whose amplitudes are much greater than those of Lamb waves. In this paper, an analysis of SH waves generated using in-plane shear electromechanical coupling is firstly presented, followed by a multiphysics finite element analysis for comparison purposes. Voltage responses of both the conventional d31 and the new d36 sensors are obtained for comparison purposes. Results indicate that this type of wafer has the potential to provide a simple quantitative estimation of damage in structural health monitoring. DA - 2014/1// PY - 2014/1// DO - 10.1088/0964-1726/23/1/015014 VL - 23 IS - 1 SP - SN - 1361-665X KW - guided wave KW - damage detection KW - in-plane shear KW - piezoelectric wafer ER - TY - JOUR TI - Ga and Al doped zinc oxide thin films for transparent conducting oxide applications: Structure-property correlations AU - Temizer, N. K. AU - Nori, S. AU - Narayan, J. T2 - Journal of Applied Physics DA - 2014/// PY - 2014/// VL - 115 IS - 2 ER - TY - JOUR TI - Approximate modelling of the leftward flow and morphogen transport in the embryonic node by specifying vorticity at the ciliated surface AU - Kuznetsov, A. V. AU - Blinov, D. G. AU - Avramenko, A. A. AU - Shevchuk, I. V. AU - Tyrinov, A. I. AU - Kuznetsov, I. A. T2 - JOURNAL OF FLUID MECHANICS AB - Abstract In this paper, we have developed an approximate method for modelling the flow of embryonic fluid in a ventral node. We simplified the problem as flow in a two-dimensional cavity; the effect of rotating cilia was modelled by specifying a constant vorticity at the edge of the ciliated layer. We also developed an approximate solution for morphogen transport in the nodal pit. The solutions were obtained utilizing the proper generalized decomposition (PGD) method. We compared our approximate solutions with the results of numerical simulation of flow caused by the rotation of 81 cilia, and obtained reasonable agreement in most of the flow domain. We discuss locations where agreement is less accurate. The obtained semi-analytical solutions simplify the analysis of flow and morphogen distribution in a nodal pit. DA - 2014/1// PY - 2014/1// DO - 10.1017/jfm.2013.588 VL - 738 SP - 492-521 SN - 1469-7645 KW - biomedical flows KW - convection in cavities KW - low-dimensional models ER - TY - JOUR TI - Analysis and control of switched linear systems via modified Lyapunov-Metzler inequalities AU - Duan, Chang AU - Wu, Fen T2 - INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL AB - SUMMARY This paper addresses analysis and switching control problems of continuous/discrete‐time switched linear systems. A particular class of matrix inequalities, the so‐called Lyapunov–Metzler inequalities, will be modified to provide conditions for stability analysis and output feedback control synthesis under a relaxed min‐switching logic. The switching rule combined with switching output feedback controllers will be designed to stabilize the switched system and satisfy a prespecified gain performance. The proposed analysis and switching control approach could refrain frequent switches commonly observed in min‐switching based designs. The effectiveness of the proposed approach will be illustrated through numerical examples. Copyright © 2012 John Wiley & Sons, Ltd. DA - 2014/1/25/ PY - 2014/1/25/ DO - 10.1002/rnc.2886 VL - 24 IS - 2 SP - 276-294 SN - 1099-1239 KW - stability analysis KW - switching output feedback control KW - min-switching logic KW - linear matrix inequalities (LMIs) ER - TY - JOUR TI - A trapezoidal flexoelectric accelerometer AU - Huang, Wenbin AU - Kwon, Seol-Ryung AU - Zhang, Shujun AU - Yuan, Fuh-Gwo AU - Jiang, Xiaoning T2 - JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES AB - In this article a new acceleration sensor using flexoelectric barium strontium titanate cantilever was designed, fabricated, and tested for vibration monitoring. The flexoelectric sensors were configured as a trapezoidal unimorph with a barium strontium titanate layer bonded onto a steel substrate. Seismic mass was attached to the unimorph tip to amplify the transverse flexoelectric response of the barium strontium titanate layer. The theoretical model was developed and validated by vibration tests using the prototyped flexoelectric unimorph. The prototyped accelerometer with thickness of 0.1 mm and length and width in millimeters showed a stable sensitivity of 0.84 pC/g over the frequency range of 100 Hz–1.6 kHz. The aging property of the flexoelectric material was demonstrated to be much better than that of the reported piezoelectric materials right after poling. Scaling effect analysis was also performed for flexoelectric unimorphs. The test results and initial scaling effect analysis indicate that micro/nano flexoelectric sensing holds promise for a broad range of applications. DA - 2014/2// PY - 2014/2// DO - 10.1177/1045389x13491021 VL - 25 IS - 3 SP - 271-277 SN - 1530-8138 KW - Flexoelectric KW - accelerometer KW - barium strontium titanate KW - flexoelectric unimorph ER - TY - JOUR TI - A review of mass customization across marketing, engineering and distribution domains toward development of a process framework AU - Ferguson, Scott M. AU - Olewnik, Andrew T. AU - Cormier, Phil T2 - RESEARCH IN ENGINEERING DESIGN DA - 2014/1// PY - 2014/1// DO - 10.1007/s00163-013-0162-4 VL - 25 IS - 1 SP - 11-30 SN - 1435-6066 KW - Mass customization KW - Collaborative design KW - Design process KW - Marketing KW - Engineering KW - Distribution KW - Product platforms KW - Product families KW - Reconfigurable design KW - Discrete choice ER - TY - JOUR TI - Thermal instability in a porous medium layer saturated by a nanofluid: A revised model AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER AB - We develop an extension of our previous thermal instability analysis of a nanofluid-saturated porous layer. The extension is based on a new boundary condition for the nanoparticle fraction, which is physically more realistic. In the previous model we imposed both temperature and nanoparticle volume fractions at the boundaries of the layer. It is now assumed that the value of the temperature can be imposed on the boundaries, but the nanoparticle fraction adjusts so that the nanoparticle flux is zero on the boundaries. The new boundary condition on the nanoparticle volume fraction is made possible by accounting for the contributions of the effect of thermophoresis to the nanoparticle flux. It is shown that, with the new boundary conditions, oscillatory convection cannot occur. The effect of the nanoparticles on non-oscillatory convection is destabilizing. DA - 2014/1// PY - 2014/1// DO - 10.1016/j.ijheatmasstransfer.2013.09.026 VL - 68 SP - 211-214 SN - 1879-2189 KW - Nanofluid KW - Porous medium KW - Instability KW - Natural convection ER - TY - JOUR TI - The Onset of Convection in an Internally Heated Nanofluid Layer AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME AB - We analytically studied the onset of convection, induced by internal heating, such as that produced by microwave heating or chemical reaction, in a horizontal layer of a nanofluid subject to Brownian motion and thermophoresis. This is a fundamentally different situation from traditionally studied heating from below. Convection, when it occurs, is now concentrated in the portion of the layer where the upward vertical gradient is negative, which is the upper portion of the layer. The situation of internal heating also allows employing more realistic boundary conditions than those hitherto used. DA - 2014/1// PY - 2014/1// DO - 10.1115/1.4025048 VL - 136 IS - 1 SP - SN - 1528-8943 KW - nanofluid KW - Brownian motion KW - thermophoresis KW - natural convection KW - Galerkin method KW - internal heating ER - TY - JOUR TI - Novel light-weight materials for shielding gamma ray AU - Chen, S. AU - Bourham, M. AU - Rabiei, A. T2 - Radiation Physics and Chemistry AB - A comparison of gamma ray attenuation effectiveness of bulk aluminum, close-cell composite metal foams and open-cell aluminum foam infiltrated with variety of second phase materials were investigated and reported in this study. Mass attenuation coefficients for six sets of samples with three different areal densities of 2, 5 and 10 g/cm2 were determined at photon energies of 0.060, 0.662, 1.173, and 1.332 MeV. Theoretical values were calculated using XCOM software package. A complete agreement was observed between experimental and theoretical results. It is observed that close-cell composite metal foams exhibit a better shielding capability compared to open-cell Al foam with fillers. It is also observed that close-cell composite metal foams offer superior shielding effectiveness compared to bulk aluminum for energies below 0.662 MeV, the mass attenuation coefficients of steel–steel composite metal foam and Al–steel composite metal foam were measured 400 and 300% higher than that of aluminum A356. This study indicates the potential of utilizing the light-weight composite metal foams as shielding material replacing current heavy materials used for attenuation of low energy gamma ray with additional advantages such as high energy absorption and excellent heat rejection capabilities. DA - 2014/// PY - 2014/// DO - 10.1016/j.radphyschem.2013.08.001 VL - 96 SP - 27–37 ER - TY - JOUR TI - Nonlinear reduction of combustion composition space with kernel principal component analysis AU - Mirgolbabaei, Hessam AU - Echekki, Tarek T2 - COMBUSTION AND FLAME AB - Kernel principal component analysis (KPCA) as a nonlinear alternative to classical principal component analysis (PCA) of combustion composition space is investigated. With the proposed approach, thermo-chemical scalar’s statistics are reconstructed from the KPCA derived moments. The tabulation of the scalars is then implemented using artificial neural networks (ANN). Excellent agreement with the original data is obtained with only 2 principal components (PCs) from numerical simulations of the Sandia Flame F flame for major species and temperature. A formulation for the source and diffusion coefficient matrix for the PCs is proposed. This formulation enables the tabulation of these key transport terms in terms of the PCs and their potential implementation for the numerical solution of the PCs’ transport equations. DA - 2014/1// PY - 2014/1// DO - 10.1016/j.combustflame.2013.08.016 VL - 161 IS - 1 SP - 118-126 SN - 1556-2921 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84887826057&partnerID=MN8TOARS KW - Kernel principal component analysis KW - Principal component analysis KW - Turbulent nonpremixed flames ER - TY - JOUR TI - Modeling anterograde and retrograde transport of short mobile microtubules from the site of axonal branch formation AU - Kuznetsov, I. A. AU - Kuznetsov, A. V. T2 - JOURNAL OF BIOLOGICAL PHYSICS AB - This theoretical research is motivated by a recent model of microtubule (MT) transport put forward by Baas and Mozgova (Cytoskeleton 69:416-425, 2012). According to their model, in an axon all plus-end-distal mobile MTs move anterogradely while all minus-end-distal mobile MTs move retrogradely. Retrograde MT transport thus represents a mechanism by which minus-end-distal MTs are removed from the axon. We suggested equations that implement Baas and Mozgova's model. We employed these equations to simulate transport of short mobile MTs from a region (such as the site of axonal branch formation) where MT severing activity results in generation of a large number of short MTs of both orientations. We obtained the exact and approximate transient solutions of these equations utilizing the Laplace transform technique. We applied the obtained solutions to calculate the average rates of anterograde and retrograde transport of short MTs. DA - 2014/1// PY - 2014/1// DO - 10.1007/s10867-013-9334-8 VL - 40 IS - 1 SP - 41-53 SN - 1573-0689 KW - Microtubule transport KW - Neurons KW - Molecular motors KW - Exact solution ER - TY - JOUR TI - Experimental characterization of a micro-hole drilling process with short micro-second pulses by a CW single-mode fiber laser AU - Tu, Jay AU - Paleocrassas, Alexander G. AU - Reeves, Nicholas AU - Rajule, Nilesh T2 - Optics and Lasers in Engineering AB - Laser ablation with pulse durations in a few microseconds is a viable solution for micro-hole drilling applications which require large material removal rate (MRR) with moderate hole quality. However, the body of work regarding short microsecond laser drilling/ablation is small. The objective of this paper is to experimentally characterize this short micro-second laser micro-hole drilling technique using a 300 W, CW, single-mode fiber laser. This CW fiber laser is controlled to produce modulated pulses from 1 μs to 8 μs and these modulated laser pulses have a unique profile which contains an initial spike with a peak power of 1500 W for 1 μs, followed by the steady state power of 300 W. Because of its excellent beam quality, the laser beam produced by this fiber laser can be focused to a small spot size of 10 μm to achieve very high power density up to 1.9 GW/cm2. With one single laser pulse at approximately 1 μs, a blind hole of 167 μm in depth and 23 μm in opening diameter can be created in a stainless substrate. The experimental characterization of this micro-hole drilling process includes laser control, laser beam characterization, hole formation, photodiode measurements of the vapor intensity, high-speed photography of vapor/plasma formation, and spectroscopic measurements of plasma. The results show that, due to very high irradiance of the fiber laser beam, the absorbed energy not only is sufficient to melt and vaporize the material, but also is able to dissociate vapor into intense plasma at temperatures over 16,000 K. The hole drilling mechanism by this short microsecond laser ablation is due to a combination of adiabatic evaporation and ejection of fine droplets. DA - 2014/4// PY - 2014/4// DO - 10.1016/J.OPTLASENG.2013.11.002 VL - 55 SP - 275-283 J2 - Optics and Lasers in Engineering LA - en OP - SN - 0143-8166 UR - http://dx.doi.org/10.1016/J.OPTLASENG.2013.11.002 DB - Crossref KW - Micro-hole drilling KW - Laser ablation KW - Fiber laser KW - Plasma KW - Melt ejection ER - TY - JOUR TI - Convective Instability of the Darcy Flow in a Horizontal Layer With Symmetric Wall Heat Fluxes and Local Thermal Nonequilibrium AU - Barletta, A. AU - Celli, M. AU - Kuznetsov, A. V. T2 - JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME AB - The linear stability of the parallel Darcy throughflow in a horizontal plane porous layer with impermeable boundaries subject to a symmetric net heating or cooling is investigated. The onset conditions for the secondary thermoconvective flow are expressed through a neutral stability bound for the Darcy–Rayleigh number associated with the uniform heat flux supplied or removed from the walls. The study is performed by taking into account a condition of local thermal nonequilibrium between the solid phase and the fluid phase. The linear stability analysis is carried out according to the normal modes' decomposition of the perturbations to the basic state. The governing equations for the disturbances are solved numerically as an eigenvalue problem leading to the neutral stability condition. If compared with the asymptotic condition of local thermal equilibrium, the regime of local nonequilibrium manifests an enhanced instability. This behavior is displayed by lower critical values of the Darcy–Rayleigh number, eventually tending to zero when the thermal conductivity of the solid phase is much larger than the conductivity of the fluid phase. In this special limit, which can be invoked as an approximate model of a gas-saturated metallic foam, the basic throughflow is always unstable to external disturbances of arbitrarily small amplitude. DA - 2014/1// PY - 2014/1// DO - 10.1115/1.4024070 VL - 136 IS - 1 SP - SN - 1528-8943 KW - porous medium KW - Darcy's law KW - linear stability KW - buoyant flow KW - local thermal nonequilibrium ER - TY - JOUR TI - Computationally Efficient Particle Release Map Determination for Direct Tumor-Targeting in a Representative Hepatic Artery System AU - Childress, E. M. AU - Kleinstreuer, C. T2 - JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME AB - Implementation of a novel direct tumor-targeting technique requires a computer modeling stage to generate particle release maps (PRMs) which allow for optimal catheter positioning and selection of best injection intervals for drug-particles. This simulation task for a patient-specific PRM may require excessive computational resources and a relatively long turn-around time for a fully transient analysis. Hence, steady-state conditions were sought which generates PRMs equivalent to the pulsatile arterial flow environment. Fluid-particle transport in a representative hepatic artery system was simulated under fully transient and steady-state flow conditions and their corresponding PRMs were analyzed and compared. Comparisons of the transient PRMs from ten equal intervals of the cardiac pulse revealed that the diastolic phase produced relatively constant PRMs due to its semisteady flow conditions. Furthermore, steady-state PRMs, which best matched the transient particle release maps, were found for each interval and over the entire cardiac pulse. From these comparisons, the flow rate and outlet pressure differences proved to be important parameters for estimating the PRMs. The computational times of the fully transient and steady simulations differed greatly, i.e., about 10 days versus 0.5 to 1 h, respectively. The time-averaged scenario may provide the best steady conditions for estimating the transient particle release maps. However, given the considerable changes in the PRMs due to the accelerating and decelerating phases of the cardiac cycle, it may be better to model several steady scenarios, which encompass the wide range of flows and pressures experienced by the arterial system in order to observe how the PRMs may change throughout the pulse. While adding more computation time, this method is still significantly faster than running the full transient case. Finally, while the best steady PRMs provide a qualitative guide for best catheter placement, the final injection position could be adjusted in vivo using biodegradable mock-spheres to ensure that patient-specific optimal tumor-targeting is achieved. In general, the methodology described could generate computationally very efficient and sufficiently accurate solutions for the transient fluid-particle dynamics problem. However, future work should test this methodology in patient-specific geometries subject to various flow waveforms. DA - 2014/1// PY - 2014/1// DO - 10.1115/1.4025881 VL - 136 IS - 1 SP - SN - 1528-8951 KW - drug-particle transport KW - tumor-targeting KW - computational efficiency ER - TY - JOUR TI - Characterization of fatigue damage in adhesively bonded lap joints through dynamic, full-spectral interrogation of fiber Bragg grating sensors: 2. Simulations AU - Webb, S. AU - Shin, P. AU - Peters, K. AU - Zikry, M. A. AU - Stan, N. AU - Chadderdon, S. AU - Selfridge, R. AU - Schultz, S. T2 - SMART MATERIALS AND STRUCTURES AB - In this paper, we simulate the response of fiber Bragg grating (FBG) sensors embedded in the adhesive layer of a composite lap that is subjected to harmonic excitation. To simulate accumulated fatigue damage at the adhesive layer, two forms of numerical nonlinearities are introduced into the model: (1) progressive plastic deformation of the adhesive and (2) changing the boundary of an interfacial defect at the adhesive layer across the overlap shear area. The simulation results are compared with previous measurements of the dynamic, full-spectral response of such FBG sensors for condition monitoring of the lap joint. Short-time Fourier transforms (STFT) of the locally extracted axial strain time histories reveal a transition to nonlinear behavior of the composite lap joint by means of intermittent frequencies that were observed in the experimental measurements and are not associated with the external excitation. The simulation results verify that the nonlinear changes in measured dynamic FBG responses are due to the progression of damage in the lap joint. DA - 2014/2// PY - 2014/2// DO - 10.1088/0964-1726/23/2/025017 VL - 23 IS - 2 SP - SN - 1361-665X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84892411813&partnerID=MN8TOARS KW - fiber Bragg grating sensors KW - composite lap joint KW - full-spectral interrogation KW - nonlinear dynamic structural behavior ER - TY - JOUR TI - Characterization of fatigue damage in adhesively bonded lap joints through dynamic, full-spectral interrogation of fiber Bragg grating sensors: 1. Experiments AU - Webb, S. AU - Shin, P. AU - Peters, K. AU - Zikry, M. A. AU - Stan, N. AU - Chadderdon, S. AU - Selfridge, R. AU - Schultz, S. T2 - SMART MATERIALS AND STRUCTURES AB - In this study we measure the in situ response of a fiber Bragg grating (FBG) sensor embedded in the adhesive layer of a single composite lap joint, subjected to harmonic excitation after fatigue loading. After a fully reversed cyclic fatigue loading is applied to the composite lap joint, the full-spectral response of the sensor is interrogated at 100 kHz during two loading conditions: with and without an added harmonic excitation. The full-spectral information avoided dynamic measurement errors often experienced using conventional peak wavelength and edge filtering techniques. The short-time Fourier transform (STFT) is computed for the extracted peak wavelength information to reveal time-dependent frequencies and amplitudes of the dynamic FBG sensor response. The dynamic response of the FBG sensor indicated a transition to strong nonlinear dynamic behavior as fatigue-induced damage progressed. The ability to measure the dynamic response of the lap joint through sensors embedded in the adhesive layer can provide in situ monitoring of the lap joint condition. DA - 2014/2// PY - 2014/2// DO - 10.1088/0964-1726/23/2/025016 VL - 23 IS - 2 SP - SN - 1361-665X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84892404653&partnerID=MN8TOARS KW - fiber Bragg grating sensors KW - composite lap joint KW - dynamic full-spectral interrogation KW - vibration KW - structural health monitoring ER - TY - JOUR TI - Ultrarich Filtration Combustion of Ethane AU - Toledo, Mario AU - Utria, Ithriscia AU - Saveliev, Alexei V. T2 - ENERGY & FUELS AB - Ultrarich filtration combustion of ethane is studied in a porous medium composed of alumina spheres with the aim to achieve optimized conversion to hydrogen and syngas. Temperature, velocities, and chemical products of the combustion waves are recorded experimentally in a range of equivalence ratios ϕ from stoichiometry (ϕ = 1) to ϕ = 2.5. Experimental and numerical results are reported for 3.5 mm diameter alumina spheres; an oxygen content of the oxidizer is varied from 21 to 30%. Two temperature models based on GRI-MECH 3.0 and San Diego-MECH demonstrated good agreement with the experimental results. The maximum hydrogen concentration of 19.3% was recorded at ϕ = 2.5 and a 30% oxygen content in the oxidizer. DA - 2014/2// PY - 2014/2// DO - 10.1021/ef402264a VL - 28 IS - 2 SP - 1536-1540 SN - 1520-5029 ER - TY - JOUR TI - Submicrometre particle filtration with a dc activated plasma textile AU - Rasipuram, S. C. AU - Wu, M. AU - Kuznetsov, I. A. AU - Kuznetsov, A. V. AU - Levine, J. F. AU - Jasper, W. J. AU - Saveliev, A. V. T2 - JOURNAL OF PHYSICS D-APPLIED PHYSICS AB - Plasma textiles are novel fabrics incorporating the advantages of cold plasma and low-cost non-woven or woven textile fabrics. In plasma textiles, electrodes are integrated into the fabric, and a corona discharge is activated within and on the surface of the fabric by applying high voltages above 10 kV between the electrodes. When the plasma textile is activated, submicrometre particles approaching the textile are charged by the deposition of ions and electrons produced by the corona, and then collected by the textile material. A stable plasma discharge was experimentally verified on the surface of the textile that was locally smooth but not rigid. A filtration efficiency close to 100% was observed in experiments conducted on salt particles with diameters ranging from 50 to 300 nm. Unlike conventional fibrous filters, the plasma textile provided uniform filtration in this range, without exhibiting a maximum particle penetration size. DA - 2014/1/15/ PY - 2014/1/15/ DO - 10.1088/0022-3727/47/2/025201 VL - 47 IS - 2 SP - SN - 1361-6463 KW - non-thermal plasmas KW - filtration KW - corona discharge KW - plasma textile ER - TY - JOUR TI - Predictions of High Strain Rate Failure Modes in Layered Aluminum Composites AU - Khanikar, Prasenjit AU - Zikry, M. A. T2 - METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE DA - 2014/1// PY - 2014/1// DO - 10.1007/s11661-013-2016-0 VL - 45A IS - 1 SP - 60-71 SN - 1543-1940 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84891630404&partnerID=MN8TOARS ER - TY - JOUR TI - Forced convection in a parallel-plate channel occupied by a nanofluid or a porous medium saturated by a nanofluid AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER AB - An analytical study is made of fully-developed laminar forced convection in a parallel-plate channel occupied by a nanofluid or by a porous medium saturated by a nanofluid, subject to uniform-flux boundary conditions. A model incorporating the effects of Brownian motion and thermophoresis is adopted. (Previous analytical studies using this model have been concerned with natural convection.) It is found that the combined effect of these two agencies is to reduce the Nusselt number. DA - 2014/3// PY - 2014/3// DO - 10.1016/j.ijheatmasstransfer.2013.11.016 VL - 70 SP - 430-433 SN - 1879-2189 KW - Nanofluid KW - Forced convection KW - Channel KW - Porous medium ER - TY - JOUR TI - Dynamic analysis of a tethered satellite system with a moving mass AU - Jung, Wonyoung AU - Mazzoleni, Andre P. AU - Chung, Jintai T2 - NONLINEAR DYNAMICS DA - 2014/1// PY - 2014/1// DO - 10.1007/s11071-013-1064-8 VL - 75 IS - 1-2 SP - 267-281 SN - 1573-269X KW - Nonlinear dynamics KW - Tethered satellites KW - Dumbbell model KW - Moving mass KW - Libration angle ER - TY - JOUR TI - Disruption of microalgal cells using high-frequency focused ultrasound AU - Wang, Meng AU - Yuan, Wenqiao AU - Jiang, Xiaoning AU - Jing, Yun AU - Wang, Zhuochen T2 - BIORESOURCE TECHNOLOGY AB - The objective of this study was to evaluate the effectiveness of high-frequency focused ultrasound (HFFU) in microalgal cell disruption. Two microalgal species including Scenedesmus dimorphus and Nannochloropsis oculata were treated by a 3.2-MHz, 40-W focused ultrasound and a 100-W, low-frequency (20kHz) non-focused ultrasound (LFNFU). The results demonstrated that HFFU was effective in the disruption of microalgal cells, indicated by significantly increased lipid fluorescence density, the decrease of cell sizes, and the increase of chlorophyll a fluorescence density after treatments. Compared with LFNFU, HFFU treatment was more energy efficient. The combination of high and low frequency treatments was found to be even more effective than single frequency treatment at the same processing time, indicating that frequency played a critical role in cell disruption. In both HFFU and LFNFU treatments, the effectiveness of cell disruption was found to be dependent on the cell treated. DA - 2014/2// PY - 2014/2// DO - 10.1016/j.biortech.2013.11.054 VL - 153 SP - 315-321 SN - 1873-2976 KW - Microalgae KW - Ultrasound KW - Cell disruption KW - Lipid extraction ER - TY - JOUR TI - Development of a patient-specific bone analog for the biomechanical evaluation of custom implants AU - Horn, Timothy J. AU - Harrysson, Ola L. A. AU - West, Harvey A., II AU - Little, Jeffrey P. AU - Marcellin-Little, Denis J. T2 - RAPID PROTOTYPING JOURNAL AB - Purpose – The aim of this study is to describe an improved experimental substrate for the mechanical testing of patient-specific implants fabricated using direct metal additive manufacturing processes. This method reduces variability and sample size requirements and addresses the importance of geometry at the bone/implant interface. Design/methodology/approach – Short-fiber glass/resin materials for cortical bone and polyurethane foam materials for cancellous bone were evaluated using standard tensile coupons. A method for fabricating bone analogs with patient-specific geometries using rapid tooling is presented. Bone analogs of a canine radius were fabricated and compared to cadaveric specimens in several biomechanical tests as validation. Findings – The analog materials exhibit a tensile modulus that falls within the range of expected values for cortical and cancellous bone. The tensile properties of the cortical bone analog vary with fiber loading. The canine radius models exhibited similar mechanical properties to the cadaveric specimens with a reduced variability. Research limitations/implications – Additional replications involving different bone geometries, types of bone and/or implants are required for a full validation. Further, the materials used here are only intended to mimic the mechanical properties of bone on a macro scale within a relatively narrow range. These analog models have not been shown to address the complex microscopic or viscoelastic behavior of bone in the present study. Originality/value – Scientific data on the formulation and fabrication of bone analogs are absent from the literature. The literature also lacks an experimental platform that matches patient-specific implant/bone geometries at the bone implant interface. DA - 2014/// PY - 2014/// DO - 10.1108/rpj-08-2012-0069 VL - 20 IS - 1 SP - 41-49 SN - 1758-7670 KW - Biomechanical testing KW - Rapid tooling KW - Bone analog KW - Custom implant KW - Mechanical properties of bone ER - TY - JOUR TI - Computational Sensitivity Analysis to Identify Muscles That Can Mechanically Contribute to Shoulder Deformity Following Brachial Plexus Birth Palsy AU - Crouch, Dustin L. AU - Plate, Johannes F. AU - Li, Zhongyu AU - Saul, Katherine R. T2 - JOURNAL OF HAND SURGERY-AMERICAN VOLUME AB - Purpose Two mechanisms, strength imbalance or impaired longitudinal muscle growth, potentially cause osseous and postural shoulder deformity in children with brachial plexus birth palsy. Our objective was to determine which muscles, via either deformity mechanism, were mechanically capable of producing forces that could promote shoulder deformity. Methods In an upper limb computational musculoskeletal model, we simulated strength imbalance by allowing each muscle crossing the shoulder to produce 30% of its maximum force. To simulate impaired longitudinal muscle growth, the functional length of each muscle crossing the shoulder was reduced by 30%. We performed a sensitivity analysis to identify muscles that, through either simulated deformity mechanism, increased the posteriorly directed, compressive glenohumeral joint force consistent with osseous deformity or reduced the shoulder external rotation or abduction range of motion consistent with postural deformity. Results Most of the increase in the posterior glenohumeral joint force by the strength imbalance mechanism was caused by the subscapularis, latissimus dorsi, and infraspinatus. Posterior glenohumeral joint force increased the most owing to impaired growth of the infraspinatus, subscapularis, and long head of biceps. Through the strength imbalance mechanism, the subscapularis, anterior deltoid, and pectoralis major muscles reduced external shoulder rotation by 28°, 17°, and 10°, respectively. Shoulder motion was reduced by 40° to 56° owing to impaired growth of the anterior deltoid, subscapularis, and long head of triceps. Conclusions The infraspinatus, subscapularis, latissimus dorsi, long head of biceps, anterior deltoid, pectoralis major, and long head of triceps were identified in this computational study as being the most capable of producing shoulder forces that may contribute to shoulder deformity following brachial plexus birth palsy. Clinical relevance The muscles mechanically capable of producing deforming shoulder forces should be the focus of experimental studies investigating the musculoskeletal consequences of brachial plexus birth palsy and are potentially critical targets for treating shoulder deformity. Two mechanisms, strength imbalance or impaired longitudinal muscle growth, potentially cause osseous and postural shoulder deformity in children with brachial plexus birth palsy. Our objective was to determine which muscles, via either deformity mechanism, were mechanically capable of producing forces that could promote shoulder deformity. In an upper limb computational musculoskeletal model, we simulated strength imbalance by allowing each muscle crossing the shoulder to produce 30% of its maximum force. To simulate impaired longitudinal muscle growth, the functional length of each muscle crossing the shoulder was reduced by 30%. We performed a sensitivity analysis to identify muscles that, through either simulated deformity mechanism, increased the posteriorly directed, compressive glenohumeral joint force consistent with osseous deformity or reduced the shoulder external rotation or abduction range of motion consistent with postural deformity. Most of the increase in the posterior glenohumeral joint force by the strength imbalance mechanism was caused by the subscapularis, latissimus dorsi, and infraspinatus. Posterior glenohumeral joint force increased the most owing to impaired growth of the infraspinatus, subscapularis, and long head of biceps. Through the strength imbalance mechanism, the subscapularis, anterior deltoid, and pectoralis major muscles reduced external shoulder rotation by 28°, 17°, and 10°, respectively. Shoulder motion was reduced by 40° to 56° owing to impaired growth of the anterior deltoid, subscapularis, and long head of triceps. The infraspinatus, subscapularis, latissimus dorsi, long head of biceps, anterior deltoid, pectoralis major, and long head of triceps were identified in this computational study as being the most capable of producing shoulder forces that may contribute to shoulder deformity following brachial plexus birth palsy. DA - 2014/2// PY - 2014/2// DO - 10.1016/j.jhsa.2013.10.027 VL - 39 IS - 2 SP - 303-311 SN - 1531-6564 KW - Biomechanics KW - brachial plexus KW - deformity KW - shoulder KW - simulation ER -