TY - CONF TI - Real-time MRI-Guided Needle Placement Robot with Integrated Fiber Optic Force Sensing AB - This paper presents the first prototype of a magnetic resonance imaging (MRI) compatible piezoelectric actuated robot integrated with a high-resolution fiber optic sensor for prostate brachytherapy with real-time in situ needle steering capability in 3T MRI. The 6-degrees-of-freedom (DOF) robot consists of a modular 3-DOF needle driver with fiducial tracking frame and a 3-DOF actuated Cartesian stage. The needle driver provides needle cannula rotation and translation (2-DOF) and stylet translation (1-DOF). The driver mimics the manual physician gesture by two point grasping. To render proprioception associated with prostate interventions, a Fabry Perot interferometer based fiber optic strain sensor is designed to provide high-resolution axial needle insertion force measurement and is robust to large range of temperature variation. The paper explains the robot mechanism, controller design, optical modeling and opto-mechanical design of the force sensor. MRI compatibility of the robot is evaluated under 3T MRI using standard prostate imaging sequences and average signal noise ratio (SNR) loss is limited to 2% during actuator motion. A dynamic needle insertion is performed and bevel tip needle steering capability is demonstrated under continuous real-time MRI guidance, both with no visually identifiable interference during robot motion. Fiber optic sensor calibration validates the theoretical modeling with satisfactory sensing range and resolution for prostate intervention. C2 - 2011/// C3 - IEEE International Conference on Robotics and Automation DA - 2011/// DO - 10.1109/ICRA.2011.5979539 UR - https://publons.com/wos-op/publon/19604808/ ER - TY - CONF TI - An Affordable Compact Humanoid Robot for Autism Spectrum Disorder Interventions in Children AB - Autism Spectrum Disorder impacts an ever-increasing number of children. The disorder is marked by social functioning that is characterized by impairment in the use of nonverbal behaviors, failure to develop appropriate peer relationships and lack of social and emotional exchanges. Providing early intervention through the modality of play therapy has been effective in improving behavioral and social outcomes for children with autism. Interacting with humanoid robots that provide simple emotional response and interaction has been shown to improve the communication skills of autistic children. In particular, early intervention and continuous care provide significantly better outcomes. Currently, there are no robots capable of meeting these requirements that are both low-cost and available to families of autistic children for in-home use. This paper proposes the piloting the use of robotics as an improved diagnostic and early intervention tool for autistic children that is affordable, non-threatening, durable, and capable of interacting with an autistic child. This robot has the ability to track the child with its 3 degree of freedom (DOF) eyes and 3-DOF head, open and close its 1-DOF beak and 1-DOF each eyelids, raise its 1-DOF each wings, play sound, and record sound. These attributes will give it the ability to be used for the diagnosis and treatment of autism. As part of this project, the robot and the electronic and control software have been developed, and integrating semi-autonomous interaction, teleoperation from a remote healthcare provider and initiating trials with children in a local clinic are in progress. C2 - 2011/// C3 - Annual International Conference of the IEEE Engineering in Medicine and Biology DA - 2011/// DO - 10.1109/IEMBS.2011.6091316 UR - https://publons.com/wos-op/publon/4427059/ ER - TY - CONF TI - Upconverting nanophosphors for high temperature applications AU - Guo, X. AU - Zhao, H. AU - Song, H. AU - Combs, C. AU - Narayanaswamy, V. AU - Clemens, N. AU - Chen, X. AU - Li, K.K. AU - Zou, Y.K. AU - Jiang, H. C2 - 2011/// C3 - Technical Proceedings of the 2011 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2011 DA - 2011/// VL - 1 SP - 429-432 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-81455133723&partnerID=MN8TOARS ER - TY - JOUR TI - Kr-PLIF for scalar imaging in supersonic flows AU - Narayanaswamy, V. AU - Burns, R. AU - Clemens, N.T. T2 - Optics Letters AB - Experiments were performed to explore the use of two-photon planar laser-induced fluorescence (PLIF) of krypton gas for applications of scalar imaging in supersonic flows. Experiments were performed in an underexpanded jet of krypton, which exhibited a wide range of conditions, from subsonic to hypersonic. Excellent signal-to-noise ratios were obtained, showing the technique is suitable for single-shot imaging. The data were used to infer the distribution of gas density and temperature by correcting the fluorescence signal for quenching effects and using isentropic relations. The centerline variation of the density and temperature from the experiments agree very well with those predicted with an empirical correlation and a CFD simulation (FLUENT). Overall, the high signal levels and quantifiable measurements indicate that Kr-PLIF could be an effective scalar marker for use in supersonic and hypersonic flow applications. DA - 2011/// PY - 2011/// DO - 10.1364/OL.36.004185 VL - 36 IS - 21 SP - 4185-4187 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80455129888&partnerID=MN8TOARS ER - TY - CONF TI - Prediction and validation of performance of an entrained flow gasifier model AU - Roy, A. AU - Ekkad, S.V. AU - Vandsburger, U. AB - Computational fluid dynamics (CFD) simulation of a single stage, dry-feed entrained flow gasifier is carried out to predict several physical and chemical processes within the gasifier. The model is developed using a commercial software package FLUENT. The CFD model is based on an Eulerian-Lagrangian framework, where the continuous fluid phase is modeled in Eulerian approach and the particle flow trajectory is simulated in Lagrangian frame. The two phases are coupled by appropriate source terms in the conservation equations. The gasification process can be divided into the following sub-processes, which are inert heating, moisture release, coal devolatilization, char gasification and gas phase reactions. Discrete Phase Model (DPM) is used to model the coal particles and coupled with heterogeneous particle surface reactions in Species Transport module. The interaction between reaction chemistry and turbulence is described by Finite-rate/Eddy dissipation model. The simulation provides detailed information of temperature field and species concentration profile inside the gasifier. The temperature distribution clearly indicates the three different reaction zones for devolatilization, gasification and reduction. Steady state model predictions are compared with benchmark experimental data from literature. The trend of the predicted species mole fraction distribution is in good agreement within error bound of the experiment. The model thus provides a validated set of model parameters along with an insight to the underlying flow physics and chemical reactions of gasification process that can be employed to improve design of experiments. This study also develops the basis to achieve further accuracy incorporating complex effects such as detailed reaction kinetic mechanisms, proper devolatilization models, effect of ash-slag transition and particle deposition. C2 - 2011/// C3 - ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011 DA - 2011/// DO - 10.1115/imece2011-63770 VL - 4 SP - 1609-1617 M1 - PARTS A AND B UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84869162837&partnerID=MN8TOARS ER - TY - CONF TI - Film-cooling performance of anti-vortex hole on a flat plate AU - Narzary, D.P. AU - LeBlanc, C. AU - Ekkad, S. AB - Film cooling performance of two hole geometries is evaluated on a flat plate surface with steady-state IR (infrared thermography) technique. The base geometry is a simple cylindrical hole design inclined at 30° from the surface with pitch-to-diameter ratio of 3.0. The second geometry is an anti-vortex design where the two side holes, also of the same diameter, branch out from the root at 15° angle. The pitch-to-diameter ratio is 6.0 between the main holes. The mainstream Reynolds number is 3110 based on the coolant hole diameter. Two secondary fluids — air and carbon-dioxide — were used to study the effects of coolant-to-mainstream density ratio (DR = 0.95 and 1.45) on film cooling effectiveness. Several blowing ratios in the range 0.5 –4.0 were investigated independently at the two density ratios. Results indicate significant improvement in effectiveness with anti-vortex holes compared to cylindrical holes at all the blowing ratios studied. At any given blowing ratio, the anti-vortex hole design uses 50% less coolant and provides at least 30–40% higher cooling effectiveness. The use of relatively dense secondary fluid improves effectiveness immediately downstream of the anti-vortex holes but leads to poor performance downstream. C2 - 2011/// C3 - ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 DA - 2011/// DO - 10.1115/ajtec2011-44161 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84990174925&partnerID=MN8TOARS ER - TY - JOUR TI - Experimental and numerical investigation of convective heat transfer in a gas turbine can combustor AU - Patil, S. AU - Abraham, S. AU - Tafti, D. AU - Ekkad, S. AU - Kim, Y. AU - Dutta, P. AU - Moon, H.-K. AU - Srinivasan, R. T2 - Journal of Turbomachinery AB - Experiments and numerical computations are performed to investigate the convective heat transfer characteristics of a gas turbine can combustor under cold flow conditions in a Reynolds number range between 50,000 and 500,000 with a characteristic swirl number of 0.7. It is observed that the flow field in the combustor is characterized by an expanding swirling flow, which impinges on the liner wall close to the inlet of the combustor. The impinging shear layer is responsible for the peak location of heat transfer augmentation. It is observed that as Reynolds number increases from 50,000 to 500,000, the peak heat transfer augmentation ratio (compared with fully developed pipe flow) reduces from 10.5 to 2.75. This is attributed to the reduction in normalized turbulent kinetic energy in the impinging shear layer, which is strongly dependent on the swirl number that remains constant at 0.7 with Reynolds number. Additionally, the peak location does not change with Reynolds number since the flow structure in the combustor is also a function of the swirl number. The size of the corner recirculation zone near the combustor liner remains the same for all Reynolds numbers and hence the location of shear layer impingement and peak augmentation does not change. DA - 2011/// PY - 2011/// DO - 10.1115/1.4001173 VL - 133 IS - 1 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79251510862&partnerID=MN8TOARS ER - TY - JOUR TI - Study of Flow and Convective Heat Transfer in a Simulated Scaled Up Low Emission Annular Combustor AU - Patil, Sunil AU - Sedalor, Teddy AU - Tafti, Danesh AU - Ekkad, Srinath AU - Kim, Yong AU - Dutta, Partha AU - Moon, Hee-Koo AU - Srinivasan, Ram T2 - Journal of Thermal Science and Engineering Applications AB - Modern dry low emissions (DLE) combustors are characterized by highly swirling and expanding flows that makes the convective heat load on the gas side difficult to predict and estimate. A coupled experimental–numerical study of swirling flow inside a DLE annular combustor model is used to determine the distribution of heat transfer on the liner walls. Three different Reynolds numbers are investigated in the range of 210,000–840,000 with a characteristic swirl number of 0.98. The maximum heat transfer coefficient enhancement ratio decreased from 6 to 3.6 as the flow Reynolds number increased from 210,000 to 840,000. This is attributed to a reduction in the normalized turbulent kinetic energy in the impinging shear layer, which is strongly dependent on the swirl number that remains constant at 0.98 for the Reynolds number range investigated. The location of peak heat transfer did not change with the increase in Reynolds number since the flow structures in the combustors did not change with Reynolds number. Results also showed that the heat transfer distributions in the annulus have slightly different characteristics for the concave and convex walls. A modified swirl number accounting for the step expansion ratio is defined to facilitate comparison between the heat transfer characteristics in the annular combustor with previous work in a can combustor. A higher modified swirl number in the annular combustor resulted in higher heat transfer augmentation and a slower decay with Reynolds number. DA - 2011/8/12/ PY - 2011/8/12/ DO - 10.1115/1.4004531 VL - 3 IS - 3 LA - en OP - SN - 1948-5085 1948-5093 UR - http://dx.doi.org/10.1115/1.4004531 DB - Crossref ER - TY - CONF TI - Performance of tripod antivortex injection holes on vane suction side film cooling AU - LeBlanc, C. AU - Narzary, D.P. AU - Ekkad, S. AU - Alvin, M.A. C2 - 2011/// C3 - 47th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2011 DA - 2011/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84880695195&partnerID=MN8TOARS ER - TY - CONF TI - Optimized impingement configurations for double wall cooling applications AU - Stoakes, P. AU - Ekkad, S. AB - Double wall cooling is a very effective technique for increasing heat transfer in hot gas path components utilizing a narrow channel near the surface of the component. Multiple techniques exist to increase the heat transfer within the narrow channel, including the use of impingement jets, turbulators and microchannels. A preliminary study has been performed using computational fluid dynamics (CFD) to determine the heat transfer benefits of double wall cooling technology when compared to a smooth wall square channel and a ribbed wall square channel. Conjugate CFD simulations of flow through an aluminum channel were performed to include the effects of conduction through the solid and convection within the main channel. The design for the preliminary study consists of a square main channel and a narrow impingement channel connected by a series of holes creating impingement jets on the outer surface of the impingement channel. The study examines multiple parameters to increase heat transfer without increasing the pumping power required. The parameters studied include diameter of impingement jets, jet-to-jet spacing, number of impingement jets, and jet-to-wall spacing. Results show that the impingement channel height-to-diameter ratio has a strong impact on heat transfer effectiveness. This study also provides a new optimization methodology for improving cooling designs with specific targets. C2 - 2011/// C3 - Proceedings of the ASME Turbo Expo DA - 2011/// DO - 10.1115/GT2011-46143 VL - 5 SP - 1535-1543 M1 - PARTS A AND B UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84865521645&partnerID=MN8TOARS ER - TY - CONF TI - Investigation of effect of end wall contouring methods on a transonic turbine blade passage AU - Panchal, K. AU - Abraham, S. AU - Ekkad, S.V. AU - Ng, W. AU - Brown, B.J. AU - Malandra, A. AB - End wall contouring has been widely studied during past two decades for secondary loss reduction in turbine passages. Recent non-axisymmetric end wall contouring methods have shown more promise for loss reduction as compared to the axisymmetric end wall contouring methods used in initial studies. The end wall contouring methods have shown definite promise, especially, for the turbine passages at low design exit Mach numbers. A class of methods exists in the literature where the end wall surface is defined by using a combination of two curves. These curves specify surface topology variation in streamwise and pitchwise directions. Another class of methods depends on surface contour optimization, in which the modification of surface contours is achieved by changing the control point locations that define the surface topology. A definitive, passage design parameter based method of contouring is still not available. However, a general guideline for the trend of contour variation, along pitchwise and streamwise direction, can certainly be extrapolated from the existing literature. It is not clear, however, whether such a trend can be fitted to any blade profile to achieve, least of all a nonoptimum but a definite, reduction in losses. Moreover, almost all of the existing studies have focused on end wall contouring of passages with low exit Mach numbers. Some researchers, indeed, have used blades designed for high turning and high exit Mach number. However, such studies were done at Mach number well below the intended design condition. A study of effect of end wall contouring on a high turning blade with high design exit Mach number is not available in open literature. The present study investigates the effect of application of three different types of end wall contouring methods through numerical simulation, on a high turning transonic turbine blade passage. The main contouring method is based on total loss reduction criterion which is described here in detail. The contouring methodology described here avoids the deficiency of current commercial mesh generation software in context of automated meshing and provides a robust end wall optimization methodology. The geometry that gives minimum SKE values is compared with this loss optimized geometry. Additionally, a normalized contoured surface topology was extracted from a previous study that has similar blade design parameters and this surface was fitted to the turbine passage under study in order to investigate the effect of such trend based surface fitting. This contour geometry has also been compared with the other two contour geometries. Aerodynamic response of these geometries has been compared in detail with the baseline case without any end wall contouring. A comparison of shape and location of end wall contours on aerodynamic performance has been provided. The results indicate that end wall contouring for transonic turbine blades may not result in as significant gains at design conditions as those claimed for low speed turbine passages in previous studies. C2 - 2011/// C3 - Proceedings of the ASME Turbo Expo DA - 2011/// DO - 10.1115/GT2011-45192 VL - 7 SP - 523-534 M1 - PARTS A, B, AND C UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84865553526&partnerID=MN8TOARS ER - TY - CONF TI - Heat transfer distribution of various rib geometries for developing flow at high rotation numbers AU - Lamont, J.A. AU - Ekkad, S.V. AU - Alvin, M.A. AB - The Coriolis force and centrifugal buoyancy have a significant effect on the cooling performance for rotating internal serpentine coolant channels in gas turbine blades. As coolant flow in rotation is highly complex, detailed knowledge of the heat transfer over a surface will greatly enhance the blade designer’s ability to predict hot spots so coolant may be distributed effectively. The present study uses a novel transient liquid crystal technique to measure heat transfer on a rotating, radially outward coolant channel, which is a simplified model of the actual coolant channels. Various rib types such as 90°, W, and M-shaped ribs of varying types are used to roughen the walls. The present study measures the effects of high rotation numbers (Ro) on the performance and heat transfer distribution of different rib types in developing flow. The present study measures how effective the ribs are up to Ro = 0.5. The Reynolds number (Re) is held constant at 12,000. Results show that in the developing region, the W and M-shaped “high-performance” ribs are just as effective as the simple 90° ribs for increasing heat transfer. The entrance effect in the developing region causes significantly high baseline heat transfer enhancement which may explain why ribs are not as effective as they are in the fully developed region. As the rotation number is increased, results show that the heat transfer on the trailing side increases, while the leading side decreases to a limit and remains constant. For all rotational cases, the W and M-shaped ribs show large changes to the heat transfer distributions on the leading and trailing sides. C2 - 2011/// C3 - ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011 DA - 2011/// DO - 10.1115/imece2011-62610 VL - 10 SP - 1039-1047 M1 - PARTS A AND B UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84869169448&partnerID=MN8TOARS ER - TY - CONF TI - Experimental validation of syngas composition of an entrained flow gasifier model under different operating conditions AU - Roy, A. AU - Ekkad, S.V. AU - Vandsburger, U. C2 - 2011/// C3 - 28th Annual International Pittsburgh Coal Conference 2011, PCC 2011 DA - 2011/// VL - 2 SP - 870-878 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84877599974&partnerID=MN8TOARS ER - TY - CONF TI - Effects of Rotation on jet impingement channel heat transfer AU - Lamont, J.A. AU - Ekkad, S.V. AB - The effects of the Coriolis force and centrifugal buoyancy is investigated in rotating internal serpentine coolant channels in turbine blades. For complex flow in rotating channels, detailed measurements of the heat transfer over the channel surface will greatly enhance the blade designer’s ability to predict hot spots so coolant air may be distributed more effectively. The present study uses a novel transient liquid crystal technique to measure heat transfer in a rotating, radially outward channel with impingement jets. This is the beginning of a comprehensive study on rotational effects on jet impingement. A simple case with a single row of constant pitch impinging jets with crossflow effect is presented to demonstrate the novel liquid crystal technique and document the baseline effects for this type of geoemtry. The present study examines the differences in heat transfer distributions due to variations in jet Rotation number and jet orifice-to-target surface distance. Colder air below room temperature is passed through a room temperature test section to simulate the centrifugal buoyancy effect seen in a real engine environment. This ensures that buoyancy is acting in a similar direction as in actual turbine blades where walls are hotter than the coolant fluid. Three parameters were controlled in the testing: jet coolant-to-wall temperature ratio, average jet Reynolds number, and average jet Rotation number. Results show, like serpentine channels, the trailing side experiences an increase in heat transfer and the leading side experiences a decrease for all jet channel height to jet diameter ratios (H/dj). At a jet channel height to jet diameter ratio of 1, the cross-flow from upstream spent jets greatly affects impingement heat transfer behavior in the channel. C2 - 2011/// C3 - Proceedings of the ASME Turbo Expo DA - 2011/// DO - 10.1115/GT2011-45744 VL - 5 SP - 1269-1278 M1 - PARTS A AND B UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84865459680&partnerID=MN8TOARS ER - TY - CONF TI - Effect of turbine airfoil shape on aerodynamic losses for turbine airfoils operating under transonic conditions AU - Abraham, S. AU - Panchal, K. AU - Ekkad, S.V. AU - Ng, W. AU - Brown, B.J. AU - Malandra, A. AB - Profile and secondary loss correlations have been developed and improved over the years to include the induced incidence and leading edge geometry and to reflect recent trends in turbine design. All of these investigations have resulted in better understanding of the flow field in turbine passages. However, there is still insufficient data on the performance of turbine airfoils with high turning angles operating at varying incidence angles at transonic Mach numbers. The paper presents detailed aerodynamic measurements for three different turbine airfoils with similar turning angles but different aerodynamic shapes. Midspan total pressure loss, secondary flow field, and static pressure measurements on the airfoil surface in the cascades are presented and compared for the three different airfoil sets. The airfoils are designed for the same velocity triangles (inlet/exit gas angles and Mach number). Airfoil curvature and true chord are varied to change the loading vs. chord. The objective is to investigate the type of loading distribution and its effect on aerodynamic performance (pressure loss). Measurements are made at +10, 0 and −10 degree incidence angles for high turning turbine airfoils with ∼127 degree turning. The cascade exit Mach numbers were varied within a range from 0.6 to 1.1. In order to attain a ratio of inlet Mach number to exit Mach number that is representative to that encountered in a real engine, the exit span is increased relative to the inlet span. This results in one end wall diverging from inlet to exit at a 13 degree angle, which simulates the required leading edge loading as seen in an engine. 3D viscous compressible CFD analysis was carried out in order to compare the results with experimentally obtained values and to further investigate the flow characteristics of the airfoils under study. C2 - 2011/// C3 - Proceedings of the ASME Turbo Expo DA - 2011/// DO - 10.1115/GT2011-45188 VL - 7 SP - 511-521 M1 - PARTS A, B, AND C UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84865447168&partnerID=MN8TOARS ER - TY - CONF TI - Effect of airfoil shape and turning angle on turbine airfoil aerodynamic performance at transonic conditions AU - Abraham, S. AU - Panchal, K. AU - Ekkad, S.V. AU - Ng, W. AU - Brown, B.J. AU - Malandra, A. AB - Performance data for high turning gas turbine blades under transonic Mach numbers is significantly lacking in literature. Performance of three gas turbine airfoils with varying turning angles at transonic flow conditions was investigated in this study. Midspan total pressure loss, secondary flow field and static pressure measurements on the airfoil surface in a linear cascade setting were measured. Airfoil curvature and true chord were varied to change the loading vs. chord for each airfoil. Airfoils A, D and E are designed to operate at different velocity triangles. Velocity triangle requirements (inlet/exit Mach number and gas angles) come from 1D and 2D models that include calibrated loss systems. One of the goals of this study was to use the experimental data to confirm/refine loss predictions for the effect of various Mach numbers and gas turning angles. The cascade exit Mach numbers were varied within a range from 0.6 to 1.1. The airfoil turning angle ranges from 120° to 138°. A realistic inlet/exit Mach number ratio, that is representative of that seen in a real engine, was obtained by reducing the inlet span with respect to the exit span of the airfoil, thereby creating a quasi 2D cascade. In order to compare the experimental results and study the detailed flow characteristics, 3D viscous compressible CFD analysis was also carried out. C2 - 2011/// C3 - ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011 DA - 2011/// DO - 10.1115/imece2011-62167 VL - 6 SP - 1199-1208 M1 - PARTS A AND B UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84869155002&partnerID=MN8TOARS ER - TY - CONF TI - Detailed heat transfer measurements inside rotating ribbed channels using the transient liquid crystal technique AU - Lamont, J.A. AU - Ekkad, S.V. AB - The effects of the Coriolis force and centrifugal buoyancy are well known in rotating internal serpentine coolant channels in turbine blades. As channel flow in rotation is highly complex, detailed knowledge of the heat transfer over a surface will greatly enhance the blade designer’s ability to predict hot spots so coolant may be distributed effectively. The present study uses a novel transient liquid crystal technique to measure heat transfer on a rotating two-pass channel surface with chilled inlet air. The present study examines the differences in heat transfer distributions of three channel types in rotation: smooth wall, 90° ribs, and W-shaped ribs. The two channels in the test section model radially inward and outward flow. To account for centrifugal buoyancy, cold air is passed through a room temperature test section. This ensures that buoyancy is acting in a similar direction to real turbine blades. Three parameters were controlled in the testing: inlet coolant-to-wall density ratio, channel Reynolds number, and Rotation number. Results were compared to previous studies with similar test conditions. The present study shows that the W-shaped ribs enhance heat transfer in all cases (stationary and rotating) approximately 2–3 times better than the 90° ribs. The W-shaped ribbed channel is least affected by rotation due to the complex nature of the flow generated by the geometry. C2 - 2011/// C3 - ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 DA - 2011/// DO - 10.1115/ajtec2011-44127 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85087998196&partnerID=MN8TOARS ER - TY - CONF TI - Detailed heat transfer distributions in engine similar cooling channels for a turbine rotor blade with different rib orientations AU - LeBlanc, C. AU - Ekkad, S.V. AU - Lambert, T. AU - Rajendran, V. AB - Detailed Nusselt number distributions are presented for a gas turbine engine similar internal channel geometry used for cooling a modern first stage rotor blade. The cooling design has one leading edge channel and a three-pass channel that covers the rest of the blade. The simulated model, generated from the midspan section of an actual cooling circuit, was studied for wall heat transfer coefficient measurements using the transient liquid crystal technique. The model wall inner surfaces were sprayed with thermochromic liquid crystals, and a transient test was used to obtain the local heat transfer coefficients from the measured color change. Results are presented for a nominal channel inlet leading edge channel Reynolds number of 10700 and a channel inlet three-pass channel Reynolds number of 25500. Detailed heat transfer measurements are presented for the simulated leading edge, first pass, second pass and third pass interior walls for different rib configurations. The channels were studied for smooth, 90° ribs, and angled ribs geometries in addition to ribs on the divider walls between adjacent passages. Overall pressure drop measurements were also obtained for each passage. Some of these results are compared with the predicted heat transfer from standard correlations used in design practices. Results show very complicated heat transfer behavior in these realistic channels compared to results obtained in simplistic geometry channels from published studies. In some cases, the Nusselt numbers predicted by correlations are 50–60% higher than obtained from the current experiments. C2 - 2011/// C3 - Proceedings of the ASME Turbo Expo DA - 2011/// DO - 10.1115/GT2011-45254 VL - 5 SP - 1109-1116 M1 - PARTS A AND B UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84865500616&partnerID=MN8TOARS ER - TY - CONF TI - A Comparison Study between ALE and SPH for Yacht Structure Design under Slamming Impact Loads AU - Fong, Rey-Yie C2 - 2011/// C3 - Abaqus Taiwan Users’ Conference DA - 2011/// ER - TY - CONF TI - 95' Planning Yacht Structure Strength and Stiffness Analysis AU - Ou, Chia-Chuan AU - Fong, Rey-Yie AU - Lin, Yu-Chieh C2 - 2011/// C3 - Abaqus Taiwan Users’ Conference DA - 2011/// ER - TY - CONF TI - Microstructural modeling of failure modes in martensitic steel alloys AU - Shanthraj, P. AU - Hatem, T.M. AU - Zikry, M.A. C2 - 2011/// C3 - Materials Research Society Symposium Proceedings DA - 2011/// DO - 10.1557/opl.2011.1446 VL - 1296 SP - 56-61 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84859022469&partnerID=MN8TOARS ER - TY - CONF TI - Tunneling effects and electrical conductivity of CNT polymer composites AU - Xu, S. AU - Rezvanian, O. AU - Peters, K. AU - Zikry, M.A. C2 - 2011/// C3 - Materials Research Society Symposium Proceedings DA - 2011/// DO - 10.1557/opl.2011.606 VL - 1304 SP - 50-56 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84860133288&partnerID=MN8TOARS ER - TY - CONF TI - Indentation and contact mechanics of nanocrystalline diamond crystals: A hierarchical molecular dynamics and finite-element approach AU - Pearson, J.D. AU - Zikry, M.A. AB - Molecular dynamics (MD) and finite-element (FE) simulations of a nano-crystalline diamond (NCD) grain system subjected to indentation were undertaken to understand how contact behavior pertaining to the surface roughness of NCD crystals can be spanned from the molecular to the continuum scale. It is shown that if the same surface roughness morphology, grain orientations, and elastic properties are used for both MD and FE simulations, there is agreement between contact pressures for relatively low indentation loads and shallow substrates. It should be emphasized that the strong correlation between MD and FE methods can also be due to the lack of defect nucleation associated with the elastic deformation of the NCD system. These predictions can be used for a hierarchical computational framework to harness the advantages of both computational approaches. Inherent to this approach is representation of surface roughness and crystal orientation that is physically consistent for both computational approaches. Using the techniques presented herein, MD simulations of fluids and fluid solid interactions may be able to be accurately performed using computational fluid dynamics (CFD) and FE simulations if an appropriate set of translation rules can be found for converting MD models to CFD models. An initial analysis of the requirements to convert MD models to CFD is undertaken and a subset of the necessary rules is postulated. C2 - 2011/// C3 - Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference DA - 2011/// DO - 10.2514/6.2011-1925 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84872434507&partnerID=MN8TOARS ER - TY - CONF TI - High-speed full-spectrum fiber Bragg gratings interrogator system and testing AU - Chadderdon, S. AU - Selfridge, R. AU - Schultz, S. AU - Webb, S. AU - Park, C. AU - Peters, K. AU - Zikry, M. AB - This paper presents a high repetition rate fiber Bragg grating (FBG) interrogation system that is able to capture the entire reflection spectrum at a rate of up to 300 kHz. The system uses a high speed MEMS based tunable optical filter that is driven with a sinusoidal voltage. The time varying FBG reflection spectrum in transmitted through the tunable filter. The time varying signal is then mapped into time varying reflection spectra. This interrogation system is used during two dynamic strain tests, in which the reflection spectra are measured at a repetition rate of 100 kHz. The first test is the impact of a woven carbon composite and the second test is on an electromagnetic railgun. C2 - 2011/// C3 - Proceedings of SPIE - The International Society for Optical Engineering DA - 2011/// DO - 10.1117/12.885138 VL - 7753 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79958006102&partnerID=MN8TOARS ER - TY - JOUR TI - Modeling Superhydrophobic Surfaces Comprised of Random Roughness AU - Samaha, M.A> AU - Tafreshi, H.V. AU - Gad-el-Hak, M. T2 - Bulletin of the American Physical Society DA - 2011/// PY - 2011/// VL - 56 IS - 18 SP - 314 ER - TY - CONF TI - On the Drag Force and Collection Efficiency of Circular and Non-Circular, Clean and Loaded Submicron Fibers AU - Hosseini, S.A. AU - Tafreshi, H.V. T2 - American Filtration and Separation Society C2 - 2011/5/10/ CY - Louisville, Kentucky DA - 2011/5/10/ PY - 2011/5/10/ ER - TY - JOUR TI - Salinity Effects on Superhydrophobic Coatings AU - Ochanda, F.O. AU - Samaha, M.A. AU - Tafreshi, H.V. AU - Tepper, G.C. AU - Gad-el-Hak, M. T2 - Bulletin of the American Physical Society DA - 2011/// PY - 2011/// VL - 56 IS - 18 SP - 314 ER - TY - CONF TI - An Overview on Micro- and Macro-Scale Modeling of Aerosol Filters AU - Tafreshi, H.V. AU - Pourdeyhimi, B. T2 - NETInc, Innovative Nonwovens Conference C2 - 2011/9/13/ CY - Atlanta, Georgia DA - 2011/9/13/ PY - 2011/9/13/ ER - TY - CONF TI - An Overview on Modeling Fluid Absorption in Fibrous Media AU - Bucher, T.M. AU - Tafreshi, H.V. T2 - NETInc, Innovative Nonwovens Conference C2 - 2011/9/13/ CY - Atlanta, Georgia DA - 2011/9/13/ PY - 2011/9/13/ ER - TY - JOUR TI - Fabrication of Superhydrophobic Fiber Coatings by DC-Biased AC-Electrospinning AU - Gad-el-Hak, M. AU - .Ochanda, F.O. AU - Samaha, M.A. AU - Tafreshi, H.V. AU - Tepper, G.C. T2 - Bulletin of the American Physical Society DA - 2011/// PY - 2011/// VL - 56 IS - 18 SP - 50 ER - TY - JOUR TI - Predicting Stability of Air-Water Interface on Superhydrophobic Surfaces AU - Emami, B. AU - Tafreshi, H.V. AU - Gad-el-Hak, M. AU - Tepper, G.C. T2 - Bulletin of the American Physical Society DA - 2011/// PY - 2011/// VL - 56 IS - 18 SP - 55 ER - TY - JOUR TI - On the Resistance of Nanofibrous Superhydrophobic Coatings to Hydrostatic Pressures AU - Bucher, T.M. AU - Emami, B. AU - Tafreshi, H.V. AU - Gad-el-Hak, M. AU - Tepper, G.C. T2 - Bulletin of the American Physical Society DA - 2011/// PY - 2011/// VL - 56 IS - 18 SP - 175 ER - TY - JOUR TI - In Situ, Noninvasive Characterization of Superhydrophobic Coatings AU - Tepper, G.C. AU - Samaha, M.A. AU - Tafreshi, H.V. AU - Gad-el-Hak, M. AU - Situ, In T2 - Bulletin of the American Physical Society DA - 2011/// PY - 2011/// VL - 56 IS - 18 SP - 314 ER - TY - JOUR TI - Fabrication of superhydrophobic fiber coatings by DC-biased AC-electrospinning AU - Ochanda, Fredrick O. AU - Samaha, Mohamed A. AU - Tafreshi, Hooman Vahedi AU - Tepper, Gary C. AU - Gad-el-Hak, Mohamed T2 - Journal of Applied Polymer Science AB - Abstract Mesh‐like fiber mats of polystyrene (PS) were deposited using DC‐biased AC‐electrospinning. Superhydrophobic surfaces with water contact angles greater than 150° and gas fraction values of up to 97% were obtained. Rheological study was conducted on these fiber surfaces and showed a decrease in shear stress when compared with a noncoated surface (no slip), making them excellent candidates for applications requiring the reduction of skin‐friction drag in submerged surfaces. We have also shown that addition of a second, low‐surface energy polymer to a solution of PS can be used to control the fiber internal porosity depending on the concentration of the second polymer. Contact‐angle measurements on mats consisting of porous and nonporous fibers have been used to evaluate the role of the larger spaces between the fibers and the pores on individual fibers on superhydrophobicity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 DA - 2011/8/9/ PY - 2011/8/9/ DO - 10.1002/app.34583 VL - 123 IS - 2 SP - 1112-1119 J2 - J. Appl. Polym. Sci. LA - en OP - SN - 0021-8995 UR - http://dx.doi.org/10.1002/app.34583 DB - Crossref KW - superhydrophobic surfaces KW - electrospinning KW - DC-biased AC-electrospinning KW - superhydrophobic fibrous coatings KW - fabrication and characterization of superhydrophobic surfaces ER - TY - JOUR TI - Modeling motion-induced fluid release from partially saturated fibrous media onto surfaces with different hydrophilicity AU - Ashari, A. AU - Bucher, T.M. AU - Tafreshi, H. Vahedi T2 - International Journal of Heat and Fluid Flow AB - Modeling the rate of fluid release from moving partially saturated nonwoven sheets in contact with a solid surface is a challenge, as the release rate depends on many parameters, some of which are difficult to quantify. In this paper, we report on a diffusion-controlled boundary treatment which we have developed to simulate fluid release from partially saturated porous materials onto surfaces with different hydrophilicy. The new boundary treatment considers the solid impermeable surface as a fictitious porous layer with a known fluid diffusive coefficient. Motion of the porous sheet on the surface is incorporated in the simulations by periodically resetting the saturation of the fictitious layer equal to zero, with a period obtained from the sheet’s speed of motion. Fluid transport inside the fibrous sheets is calculated by solving Richards’ equation of two-phase flows in porous media. Our numerical simulations are accompanied with experimental data obtained using a custom-made test rig for the release of liquid from partially saturated media at different speeds. It is demonstrated that the novel mathematical formulations presented here can correctly predict the rate of fluid release from moving fibrous sheets onto solid surfaces with different hydrophilicity as a function of time. DA - 2011/10// PY - 2011/10// DO - 10.1016/j.ijheatfluidflow.2011.06.002 VL - 32 IS - 5 SP - 1076-1081 J2 - International Journal of Heat and Fluid Flow LA - en OP - SN - 0142-727X UR - http://dx.doi.org/10.1016/j.ijheatfluidflow.2011.06.002 DB - Crossref KW - Two-phase flow KW - Fibrous media KW - Richards' equation KW - Controlled release KW - Relative permeability KW - Capillary pressure ER - TY - JOUR TI - Predicting shape and stability of air–water interface on superhydrophobic surfaces with randomly distributed, dissimilar posts AU - Emami, B. AU - Tafreshi, H. Vahedi AU - Gad-el-Hak, M. AU - Tepper, G. C. T2 - Applied Physics Letters AB - A mathematical framework developed to calculate the shape of the air–water interface and predict the stability of a microfabricated superhydrophobic surface with randomly distributed posts of dissimilar diameters and heights is presented. Using the Young–Laplace equation, a second-order partial differential equation is derived and solved numerically to obtain the shape of the interface, and to predict the critical hydrostatic pressure at which the superhydrophobicity vanishes in a submersed surface. Two examples are given for demonstration of the method’s capabilities and accuracy. DA - 2011/5/16/ PY - 2011/5/16/ DO - 10.1063/1.3590268 VL - 98 IS - 20 SP - 203106 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.3590268 DB - Crossref ER - TY - JOUR TI - In situ, noninvasive characterization of superhydrophobic coatings AU - Samaha, Mohamed A. AU - Ochanda, Fredrick O. AU - Tafreshi, Hooman Vahedi AU - Tepper, Gary C. AU - Gad-el-Hak, Mohamed T2 - Review of Scientific Instruments AB - Light scattering was used to measure the time-dependent loss of air entrapped within a submerged microporous hydrophobic surface subjected to different environmental conditions. The loss of trapped air resulted in a measurable decrease in surface reflectivity and the kinetics of the process was determined in real time and compared to surface properties, such as porosity and morphology. The light-scattering results were compared with measurements of skin-friction drag, static contact angle, and contact-angle hysteresis. The in situ, noninvasive optical technique was shown to correlate well with the more conventional methods for quantifying surface hydrophobicity, such as flow slip and contact angle. DA - 2011/4// PY - 2011/4// DO - 10.1063/1.3579498 VL - 82 IS - 4 SP - 045109 J2 - Review of Scientific Instruments LA - en OP - SN - 0034-6748 1089-7623 UR - http://dx.doi.org/10.1063/1.3579498 DB - Crossref ER - TY - JOUR TI - A Monte Carlo simulation of radiative heat through fibrous media: Effects of boundary conditions and microstructural parameters AU - Arambakam, R. AU - Hosseini, S.A. AU - Tafreshi, H. Vahedi AU - Pourdeyhimi, B. T2 - International Journal of Thermal Sciences AB - This work reports on a Monte Carlo Ray Tracing (MCRT) simulation technique devised to study steady-state radiative heat transfer in fibrous insulation materials. The media consist of specular opaque fibers having unimodal/bimodal fiber diameter distributions. The simulations are conducted in 2-D ordered geometries, and the role of lateral symmetric or periodic boundary conditions are discussed in detail. Our results indicate that with the symmetric or periodic boundary condition, view factor Fi,i should be excluded from the calculations leading to temperature prediction. This is especially important when the media are made of fibers arranged in ordered configurations. In agreement with our previous 3-D MCRT simulations, the 2-D MCRT simulations presented here reveal that heat flux through a fibrous medium decreases by increasing packing fraction of the fibers, when fiber diameter is kept constant. Moreover, increasing fibers’ absorptivity was found to decrease the radiation transmittance through the media. In this work, we have also studied radiative heat transfer through bimodal fibrous media, and concluded that increasing fibers’ dissimilarity increases energy transmittance through the media, if porosity and number of fibers are kept constant. It was also found that temperature of the fibers is almost independent of the media’s porosity or diameter ratios. DA - 2011/6// PY - 2011/6// DO - 10.1016/j.ijthermalsci.2011.01.015 VL - 50 IS - 6 SP - 935-941 J2 - International Journal of Thermal Sciences LA - en OP - SN - 1290-0729 UR - http://dx.doi.org/10.1016/j.ijthermalsci.2011.01.015 DB - Crossref KW - Radiative heat transfer KW - Fibrous media KW - High-temperature insulation KW - Ray tracing ER - TY - JOUR TI - Analytical expressions for predicting performance of aerosol filtration media made up of trilobal fibers AU - Fotovati, S. AU - Tafreshi, H. Vahedi AU - Pourdeyhimi, B. T2 - Journal of Hazardous Materials AB - Despite the widespread use of fibrous filtration media made up of trilobal fibers (referred to as trilobal media here), no mathematical formulations have yet been developed to predict their collection efficiency or pressure drop. In this study, we model the cross-section of a trilobal fiber with three overlapping ellipses separated from one another by a 120° transformation. We generate 2-D models representing the internal structure of trilobal filters having fibers with different dimensions and aspect ratios, and used them to predict pressure drop and collection efficiency of trilobal filter media. This information is then utilized to define an equivalent medium with circular fibers for each trilobal filter. Our results indicate that the circumscribed circle of a trilobal fiber can serve as an equivalent circular diameter, and therefore be used in the existing empirical/semi-empirical correlations that have previously been developed for predicting performance of filters with circular fibers. We have also proposed easy-to-use expressions that can be used with our equivalent circumscribed diameters for calculating the pressure drop of trilobal media. DA - 2011/2// PY - 2011/2// DO - 10.1016/j.jhazmat.2010.12.027 VL - 186 IS - 2-3 SP - 1503-1512 J2 - Journal of Hazardous Materials LA - en OP - SN - 0304-3894 UR - http://dx.doi.org/10.1016/j.jhazmat.2010.12.027 DB - Crossref KW - Aerosol filtration KW - Trilobal fibers KW - CFD simulation ER - TY - JOUR TI - Simulation of meniscus stability in superhydrophobic granular surfaces under hydrostatic pressures AU - Emami, B. AU - Bucher, T.M. AU - Tafreshi, H. Vahedi AU - Pestov, D. AU - Gad-el-Hak, M. AU - Tepper, G.C. T2 - Colloids and Surfaces A: Physicochemical and Engineering Aspects AB - In this work, a series of numerical simulations has been devised to study the performance of granular superhydrophobic surfaces under elevated hydrostatic pressures. Using balance of forces, an analytical expression has also been developed to predict the critical pressure at which a submersed idealized granular superhydrophobic surface comprised of spherical particles, orderly packed next to one another, departs from the Cassie state. Predictions of our analytical expression have been compared with those of a series of 3-D full-morphology numerical simulations, and reasonable agreement has been observed between the two methods. Full-morphology simulations were then used, for the first time, to compute the critical pressure of superhydrophobic surfaces comprised of randomly distributed spherical particles (e.g., superhydrophobic coatings developed by depositing of hydrophobic aerogel particles), where no analytical method is applicable due to the complexity of the coatings’ morphology. Results of our numerical simulations indicate that for coatings made up of mono-disperse hydrophobic particles, critical pressure increases with increasing the solid volume fraction. However, increasing particle diameter results in lower critical pressures when the coating's solid volume fraction is held constant. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.colsurfa.2011.05.055 VL - 385 IS - 1-3 SP - 95-103 J2 - Colloids and Surfaces A: Physicochemical and Engineering Aspects LA - en OP - SN - 0927-7757 UR - http://dx.doi.org/10.1016/j.colsurfa.2011.05.055 DB - Crossref KW - Superhydrophobic coating KW - Granular surface KW - Critical pressure KW - 3-D modeling KW - Capillary pressure ER - TY - JOUR TI - On the importance of fibers' cross-sectional shape for air filters operating in the slip flow regime AU - Hosseini, S.A. AU - Tafreshi, H. Vahedi T2 - Powder Technology AB - In this paper, we investigate the effects of fibers' cross-sectional shape on the performance of a fibrous filter in the slip and no-slip flow regimes. The slip flow regime is expected to prevail when fiber diameter is comparable in size to the mean free path of the gas molecules (about 65 nm at normal temperatures and pressures), whereas the no-slip flow regime describes the aerodynamic condition of flow through media with large fibers. Our numerical simulations conducted for flow around single fibers with different geometries indicate that, while the collection efficiency is only weakly affected by the cross-sectional shape of nanofibers, the fiber drag (i.e., permeability of the media) can be considerably influenced by the fiber's shape. Simulating the flow field around nano- and microfibers with circular, square, trilobal, and elliptical cross-sections, it was found that the more streamlined the fiber geometry, the lower the fiber drag caused by a nanofiber relative to that generated by its micron-sized counterpart. DA - 2011/10// PY - 2011/10// DO - 10.1016/j.powtec.2011.06.025 VL - 212 IS - 3 SP - 425-431 J2 - Powder Technology LA - en OP - SN - 0032-5910 UR - http://dx.doi.org/10.1016/j.powtec.2011.06.025 DB - Crossref KW - Nanofiber KW - Aerosols KW - Filtration KW - Fibrous media KW - CFD simulation KW - Square fibers ER - TY - JOUR TI - A methodology for determining optimal thermal damage in magnetic nanoparticle hyperthermia cancer treatment AU - Mital, Manu AU - Tafreshi, Hooman V. T2 - International Journal for Numerical Methods in Biomedical Engineering AB - SUMMARY Hyperthermia treatment of tumors uses localized heating to damage cancer cells and can also be utilized to increase the efficacy of other treatment methods such as chemotherapy. Magnetic nanoparticle hyperthermia is one of the least invasive techniques of delivering heat. It is based on injecting magnetic nanoparticles into the tumor and subjecting them to an alternating magnetic field. The technique is aimed at damaging the tumor without affecting the surrounding healthy tissue. In this preliminary study, we consider a simplified model (two concentric spheres that represent the tumor and its surrounding tissues) that employs a numerical solution of the Pennes bioheat equation. The model assumes a Gaussian distribution for the spatial variation of the applied thermal energy and an exponential decay function for the time variation. The objective of the study is to optimize the parameters that control the spatial and the time variation of the thermal energy. The optimization process is performed by formulating a fitness function that rewards damage in the region representing the tumor but penalizes damage in the surrounding tissues. Because of the flatness of this fitness function near the optimum, a genetic algorithm is used as the optimization method for its robust non‐gradient‐based approach. The overall aim of this work is to propose a methodology that can be used for hyperthermia treatment in a clinical scenario. Copyright © 2011 John Wiley & Sons, Ltd. DA - 2011/7/29/ PY - 2011/7/29/ DO - 10.1002/cnm.1456 VL - 28 IS - 2 SP - 205-213 J2 - Int. J. Numer. Meth. Biomed. Engng. LA - en OP - SN - 2040-7939 UR - http://dx.doi.org/10.1002/cnm.1456 DB - Crossref KW - hyperthermia KW - thermal dose KW - magnetic heating KW - breast cancer ER - TY - JOUR TI - Modeling drag reduction and meniscus stability of superhydrophobic surfaces comprised of random roughness AU - Samaha, M.A. AU - Vahedi Tafreshi, H. AU - Gad-el-Hak, M. T2 - Physics of Fluids AB - Previous studies dedicated to modeling drag reduction and stability of the air-water interface on superhydrophobic surfaces were conducted for microfabricated coatings produced by placing hydrophobic microposts/microridges arranged on a flat surface in aligned or staggered configurations. In this paper, we model the performance of superhydrophobic surfaces comprised of randomly distributed roughness (e.g., particles or microposts) that resembles natural superhydrophobic surfaces, or those produced via random deposition of hydrophobic particles. Such fabrication method is far less expensive than microfabrication, making the technology more practical for large submerged bodies such as submarines and ships. The present numerical simulations are aimed at improving our understanding of the drag reduction effect and the stability of the air-water interface in terms of the microstructure parameters. For comparison and validation, we have also simulated the flow over superhydrophobic surfaces made up of aligned or staggered microposts for channel flows as well as streamwise or spanwise ridges configurations for pipe flows. The present results are compared with theoretical and experimental studies reported in the literature. In particular, our simulation results are compared with work of Sbragaglia and Prosperetti, and good agreement has been observed for gas fractions up to about 0.9. The numerical simulations indicate that the random distribution of surface roughness has a favorable effect on drag reduction, as long as the gas fraction is kept the same. This effect peaks at about 30% as the gas fraction increases to 0.98. The stability of the meniscus, however, is strongly influenced by the average spacing between the roughness peaks, which needs to be carefully examined before a surface can be recommended for fabrication. It was found that at a given maximum allowable pressure, surfaces with random post distribution produce less drag reduction than those made up of staggered posts. DA - 2011/// PY - 2011/// DO - 10.1063/1.3537833 VL - 23 IS - 1 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79551512121&partnerID=MN8TOARS ER - TY - CONF TI - Transient modeling of dust-loaded pleated air filters AU - Fotovati, S. AU - Hosseini, S.A. AU - Vahedi Tafreshi, H. AU - Pourdeyhimi, B. C2 - 2011/// C3 - American Filtration and Separations Society Annual Conference 2011 - Shape up to Green DA - 2011/// SP - 464-470 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84883797244&partnerID=MN8TOARS ER - TY - JOUR TI - A piezoelectric multilayer-stacked hybrid actuation/transduction system AU - Xu, Tian-Bing AU - Jiang, Xiaoning AU - Su, Ji T2 - Applied Physics Letters AB - A piezoelectric multilayer-stacked hybrid actuation/transduction system (stacked-HYBATS) is reported in this letter. It uses synergetic contributions from positive-strain and negative-strain piezoelectric multilayer-stacks to give displacements of about 3.5 times those of the same-sized piezoelectric flextensional actuator/transducer. The resonance of a stacked-HYBATS is enhanced comparing with that of actuators with either stack alone. The effective piezoelectric coefficient of the stacked-HYBATS is 2.5×106 pm/V at the resonance frequency and 1.5×105 pm/V at off-resonance frequencies. The stacked-HYBATS provides an approach for high performance electromechanical devices. DA - 2011/6/13/ PY - 2011/6/13/ DO - 10.1063/1.3600057 VL - 98 IS - 24 SP - 243503 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.3600057 DB - Crossref ER - TY - JOUR TI - Strain-Sensing Elastomer/Carbon Nanofiber “Metacomposites” AU - Zhu, Jiahua AU - Wei, Suying AU - Ryu, Jongeun AU - Guo, Zhanhu T2 - The Journal of Physical Chemistry C AB - Electrically conductive elastomer nanocomposites reinforced with 1, 2, 3, and 5 wt % carbon nanofibers (CNFs) have been fabricated from two slightly different elastomers (VM1, VM2). The electrical and dielectric percolation threshold of 1 wt % in VM2 nanocomposites is much lower than 3 wt % in the VM1 nanocomposites. Unique negative permittivity is observed in the composites with the CNF concentration correlating well with the percolation thresholds. About 40% unrecoverable strain loss and a permanently increased resistivity by about 2 orders of magnitude are observed due to the formation and opening/closing of the cracks during the first cyclic loading. In the subsequent stretching cycles, the reversible resistivity at 120% strain is about 2–3 orders of magnitude higher than that at 40% strain. Higher fraction of ethylene is found to reduce the thermal stability of the propylene portion in the elastomer. An enhanced thermal stability of the elastomers is observed in both nanocomposite systems; however, the CNFs affect the glass transition and melting behaviors in an opposite way in the two different nanocomposite systems arising from the dispersion quality difference. Melting enthalpy from differential scanning calorimetry (DSC) reveals that the CNFs play a more important role in the VM2 crystallization than that in VM1 composites. DA - 2011/6/17/ PY - 2011/6/17/ DO - 10.1021/jp202999c VL - 115 IS - 27 SP - 13215-13222 J2 - J. Phys. Chem. C LA - en OP - SN - 1932-7447 1932-7455 UR - http://dx.doi.org/10.1021/jp202999c DB - Crossref ER - TY - JOUR TI - Poly(propylene)/Graphene Nanoplatelet Nanocomposites: Melt Rheological Behavior and Thermal, Electrical, and Electronic Properties AU - Li, Yunfeng AU - Zhu, Jiahua AU - Wei, Suying AU - Ryu, Jongeun AU - Sun, Luyi AU - Guo, Zhanhu T2 - Macromolecular Chemistry and Physics AB - Poly(propylene) polymer nanocomposites containing graphene nanoplatelets (GnPs) with different loadings are fabricated via a facile ex-situ solution approach. Improved thermal stability and higher crystallinity are observed in the PNCs. Both electrical conductivity and real permittivity increase with increasing GnP loading. Electrical conductivity percolation is observed at 12.0 wt% GnP. The rheological behavior of the PNC melts are also investigated. It is found that the modulus and viscosity are reduced at small GnP loadings and increased above a critical loading. DA - 2011/7/22/ PY - 2011/7/22/ DO - 10.1002/macp.201100263 VL - 212 IS - 18 SP - 1951-1959 J2 - Macromol. Chem. Phys. LA - en OP - SN - 1022-1352 UR - http://dx.doi.org/10.1002/macp.201100263 DB - Crossref KW - electrical conductivity KW - graphene nanoplatelets KW - melt rheological behavior KW - poly(propylene) ER - TY - JOUR TI - Subcellular Resolution Mapping of Endogenous Cytokine Secretion by Nano-Plasmonic-Resonator Sensor Array AU - Wang, Sheng AU - Ota, Sadao AU - Guo, Bin AU - Ryu, Jongeun AU - Rhodes, Christopher AU - Xiong, Yi AU - Kalim, Sheraz AU - Zeng, Li AU - Chen, Yong AU - Teitell, Michael A. AU - Zhang, Xiang T2 - Nano Letters AB - Local extracellular signaling is central for cellular interactions and organizations. We report a novel sensing technique to interrogate extracellular signaling at the subcellular level. We developed an in situ immunoassay based on giant optical enhancement of a tunable nano-plasmonic-resonator array fabricated by nanoimprint lithography. Our nanoplasmonic device significantly increases the signal-to-noise ratio to enable the first time submicrometer resolution quantitative mapping of endogenous cytokine secretion. Our study shows a markedly high local interleukin-2 (IL-2) concentration within the immediate vicinity of the cell which finally validates a decades-old hypothesis on autocrine physiological concentration and spatial range. This general sensing technique can be applied for a broad range of cellular communication studies to improve our understanding of subcellular signaling and function. DA - 2011/8/10/ PY - 2011/8/10/ DO - 10.1021/nl2018838 VL - 11 IS - 8 SP - 3431-3434 J2 - Nano Lett. LA - en OP - SN - 1530-6984 1530-6992 UR - http://dx.doi.org/10.1021/nl2018838 DB - Crossref KW - Biosensing KW - plasmonic resonator KW - in situ immunoassay KW - cytokine KW - T cell KW - nanoimprint lithography (NIL) ER - TY - JOUR TI - Reactive Sintering of Copper Nanoparticles Using Intense Pulsed Light for Printed Electronics AU - Ryu, Jongeun AU - Kim, Hak-Sung AU - Hahn, H. Thomas T2 - Journal of Electronic Materials DA - 2011/// PY - 2011/// DO - 10.1007/s11664-010-1384-0 VL - 40 IS - 1 SP - 42–50 SN - 0361-5235 1543-186X UR - http://dx.doi.org/10.1007/s11664-010-1384-0 KW - Intense pulsed light KW - reactive sintering KW - copper oxide KW - printed electronics ER - TY - JOUR TI - Sintering of Inkjet-Printed Silver Nanoparticles at Room Temperature Using Intense Pulsed Light AU - Kang, J. S. AU - Ryu, J. AU - Kim, H. S. AU - Hahn, H. T. T2 - Journal of Electronic Materials DA - 2011/8/12/ PY - 2011/8/12/ DO - 10.1007/s11664-011-1711-0 VL - 40 IS - 11 SP - 2268-2277 J2 - Journal of Elec Materi LA - en OP - SN - 0361-5235 1543-186X UR - http://dx.doi.org/10.1007/s11664-011-1711-0 DB - Crossref KW - Intense pulsed light KW - silver KW - nanoparticle KW - sintering ER - TY - CHAP TI - Modeling and Control of Space Vehicles with Fuel Slosh Dynamics AU - Reyhanoglu, M. T2 - Advances in Spacecraft Technologies A2 - Hall, Jason PY - 2011/// SP - 549–562 PB - InTech SN - 9789533075518 ER - TY - CONF TI - Feasibility of Space Vehicle Debris Hazard Airspace Stratification AU - Reyhanoglu, Mahmut AU - Drakunov, Sergey AU - Mumme, Joern T2 - AIAA SPACE 2011 Conference & Exposition AB - knowledge of the initial state vector, ambient wind conditions, and the key parameters including the maximum and minimum ballistic coecients. In addition, propagation of all debris pieces to the ground would require extensive computer time. In this paper, we study the feasibility in terms of the technical computational constraints needed to identify hazarded altitude layers at dierent times. We describe all assumptions employed along with their justication. Moreover, we demonstrate the sensitivity of the results to the values of key parameters including the maximum and minimum ballistic coecients of the vehicle debris, and ambient wind conditions. C2 - 2011/9/27/ C3 - AIAA SPACE 2011 Conference & Exposition CY - Long Beach, CA DA - 2011/9/27/ PY - 2011/9/27/ DO - 10.2514/6.2011-7182 PB - American Institute of Aeronautics and Astronautics SN - 9781600869532 UR - http://dx.doi.org/10.2514/6.2011-7182 ER - TY - CONF TI - Nonlinear control of a spacecraft with multiple fuel slosh modes AU - Reyhanoglu, Mahmut AU - Rubio Hervas, Jaime T2 - 2011 50th IEEE Conference on Decision and Control and European Control Conference (CDC-ECC 2011) AB - This paper studies the modeling and control problem for a spacecraft with fuel slosh dynamics. A multi-pendulum model is considered for the characterization of the most prominent sloshing modes. The control inputs are defined by the gimbal deflection angle of a non-throttable thrust engine and a pitching moment about the center of mass of the spacecraft. The control objective, as is typical in a thrust vector control design, is to control the translational velocity vector and the attitude of the spacecraft, while attenuating the sloshing modes. A nonlinear mathematical model that reflects all of these assumptions is first derived. Then, a Lyapunov-based nonlinear feedback controller is designed to achieve the control objective. Finally, a simulation example is included to demonstrate the effectiveness of the controller. C2 - 2011/12// C3 - Proceedings of the 2011 50th IEEE Conference on Decision and Control and European Control Conference CY - Orlando, FL DA - 2011/12// PY - 2011/12/12/ DO - 10.1109/cdc.2011.6160660 PB - IEEE SN - 9781612848013 9781612848006 9781467304573 9781612847993 UR - http://dx.doi.org/10.1109/cdc.2011.6160660 ER - TY - JOUR TI - Predictive Control Allocation for a Thermal Management System Based on an Inner Loop Reference Model—Design, Analysis, and Experimental Results AU - Vermillion, Chris AU - Sun, Jing AU - Butts, Ken T2 - IEEE Transactions on Control Systems Technology AB - This paper addresses the challenge of controlling an overactuated engine thermal management system where two actuators, with different dynamic authorities and saturation limits, are used to obtain tight temperature regulation. A modular control strategy is proposed that combines model predictive control allocation (MPCA) with the use of an inner loop reference model. This results in an inner loop controller that closely matches a dynamic specification for input-output performance while addressing actuator dynamics and saturation constraints. This paper presents the design and implementation strategy and illustrates the effectiveness of the proposed solution through real-time simulation and experimental results. DA - 2011/7// PY - 2011/7// DO - 10.1109/tcst.2010.2053370 VL - 19 IS - 4 SP - 772-781 J2 - IEEE Trans. Contr. Syst. Technol. OP - SN - 1063-6536 1558-0865 UR - http://dx.doi.org/10.1109/tcst.2010.2053370 DB - Crossref KW - Automotive control KW - decentralized control KW - model predictive control (MPC) KW - powertrain control ER - TY - CONF TI - Spray combustion of biodiesel and diesel in a constant volume combustion chamber AU - Zhang, J. AU - Fang, T. C2 - 2011/// C3 - SAE 2011 World Congress and Exhibition DA - 2011/// DO - 10.4271/2011-01-1380 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79959820861&partnerID=MN8TOARS ER - TY - JOUR TI - Spray combustion of biodiesel and diesel in a constant volume combustion chamber AU - Zhang, J. AU - Fang, T. T2 - SAE Technical Papers DA - 2011/// PY - 2011/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84877163563&partnerID=MN8TOARS ER - TY - CONF TI - Simultaneous imaging of OH* chemiluminescence and flame luminosity of diesel and biodiesel spray combustion AU - Zhang, J. AU - Fang, Tiegang AB - The research on the spray combustion of diesel and biodiesel is vital to the understanding of emission formation and optimal utilization of fuel. This paper studies the biodiesel and diesel spray combustion in a constant volume chamber under different simulated diesel engine conditions. The ambient temperature at fuel injection varied from 800K to 1200K, while the ambient oxygen concentration was maintained at 21%. Simultaneous high speed imaging of OH* chemiluminescence and flame luminosity was employed to visualize the whole combustion process. Heat release rate was analyzed based on the measured combustion pressure. The apparent heat release rate analysis shows that biodiesel has a shorter ignition delay time than diesel, and biodiesel has a smaller cumulative heat release value due to its lower heating value. The overlaying image of OH* chemiluminescence and flame luminosity clearly identifies the high temperature reaction regions and soot formation regions. The line-of-sight images agree with the published observation that the hydroxyl radical is formed on the lean side of the flame edge. Decreasing ambient temperature greatly reduces the OH* chemiluminescence intensity of the diesel combustion, while the impact is smoother and milder for biodiesel combustion. Biodiesel shows a significantly lower level of flame luminosity than diesel under all conditions. These combined observations lead to a speculation that the soot oxidation process may serve as an important contributor to OH* chemiluminescence intensity for late stage combustion, and biodiesel shows a tendency to produce less soot than diesel under the investigated conditions. C2 - 2011/// C3 - American Society of Mechanical Engineers, Internal Combustion Engine Division (Publication) ICE DA - 2011/// DO - 10.1115/ICEF2011-60103 SP - 415-421 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84862580656&partnerID=MN8TOARS ER - TY - JOUR TI - A simulation analysis of the combined effects of muscle strength and surgical tensioning on lateral pinch force following brachioradialis to flexor pollicis longus transfer AU - Mogk, Jeremy P.M. AU - Johanson, M. Elise AU - Hentz, Vincent R. AU - Saul, Katherine R. AU - Murray, Wendy M. T2 - Journal of Biomechanics AB - Biomechanical simulations of tendon transfers performed following tetraplegia suggest that surgical tensioning influences clinical outcomes. However, previous studies have focused on the biomechanical properties of only the transferred muscle. We developed simulations of the tetraplegic upper limb following transfer of the brachioradialis (BR) to the flexor pollicis longus (FPL) to examine the influence of residual upper limb strength on predictions of post-operative transferred muscle function. Our simulations included the transfer, ECRB, ECRL, the three heads of the triceps, brachialis, and both heads of the biceps. Simulations were integrated with experimental data, including EMG and joint posture data collected from five individuals with tetraplegia and BR-FPL tendon transfers during maximal lateral pinch force exertions. Given a measured co-activation pattern for the non-paralyzed muscles in the tetraplegic upper limb, we computed the highest activation for the transferred BR for which neither the elbow nor the wrist flexor moment was larger than the respective joint extensor moment. In this context, the effects of surgical tensioning were evaluated by comparing the resulting pinch force produced at different muscle strength levels, including patient-specific scaling. Our simulations suggest that extensor muscle weakness in the tetraplegic limb limits the potential to augment total pinch force through surgical tensioning. Incorporating patient-specific muscle volume, EMG activity, joint posture, and strength measurements generated simulation results that were comparable to experimental results. Our study suggests that scaling models to the population of interest facilitates accurate simulation of post-operative outcomes, and carries utility for guiding and developing rehabilitation training protocols. DA - 2011/2// PY - 2011/2// DO - 10.1016/j.jbiomech.2010.11.004 VL - 44 IS - 4 SP - 669-675 J2 - Journal of Biomechanics LA - en OP - SN - 0021-9290 UR - http://dx.doi.org/10.1016/j.jbiomech.2010.11.004 DB - Crossref KW - Biomechanical modeling KW - Simulation KW - Upper extremity KW - Lateral pinch KW - Upper limb function ER - TY - CONF TI - Feedback Control of a Nonholonomic Vehicle among Moving Obstacles using Variable Structure Observer AU - Armstrong, Stephen AU - Drakunov, Sergey AU - Reyhanoglu, Mahmut T2 - Infotech@Aerospace 2011 AB - A feedback controller is developed for navigating a nonholonomic vehicle in an area with multiple stationary and possibly moving obstacles. Among other applications the developed algorithms can be used for automatic parking of a passenger car in a parking lot with complex conguration or a ground robot in cluttered environment. Several approaches are explored which combine nonholonomic systems control based on sliding modes and potential eld methods. C2 - 2011/3/29/ C3 - Infotech@Aerospace 2011 DA - 2011/3/29/ DO - 10.2514/6.2011-1586 PB - American Institute of Aeronautics and Astronautics SN - 9781600869440 UR - http://dx.doi.org/10.2514/6.2011-1586 DB - Crossref ER - TY - CONF TI - Nonlinear estimation of fluid flow velocity fields AU - MacKunis, W. AU - Drakunov, S. V. AU - Reyhanoglu, M. AU - Ukeiley, L. T2 - 2011 50th IEEE Conference on Decision and Control and European Control Conference (CDC-ECC 2011) AB - A proper orthogonal decomposition (POD)-based nonlinear estimator for fluid flow velocity fields is developed, which is capable of achieving finite-time convergence of the Galerkin coefficient estimates. Using Galerkin projection and POD-based model reduction, the incompressible Navier-Stokes equations are recast as a set of nonlinear ordinary differential equations in the Galerkin coefficients. A sliding-mode-based observer is designed to estimate the unknown time-varying Galerkin coefficients. Convergence of the estimates is proven to be achieved in finite time, and high-fidelity numerical simulation results are provided to complement the theoretical development. C2 - 2011/12// C3 - IEEE Conference on Decision and Control and European Control Conference DA - 2011/12// DO - 10.1109/cdc.2011.6161193 PB - IEEE SN - 9781612848013 9781612848006 9781467304573 9781612847993 UR - http://dx.doi.org/10.1109/cdc.2011.6161193 DB - Crossref ER - TY - CONF TI - Three-axis magnetic attitude control algorithms for small satellites AU - Reyhanoglu, Mahmut AU - Hervas, Jaime Rubio T2 - 2011 5th International Conference on Recent Advances in Space Technologies (RAST) AB - Recently there has been a surge of interest in developing new techniques for the attitude control of small satellites using only magnetic actuation. Although the control torque at any instant can only be generated perpendicular to the geomagnetic field vector, such a spacecraft is still controllable if the magnetic field along its orbit is periodic in time. In this paper we present three-axis attitude control algorithms for small satellites using only magnetic torquers and investigate their performance through simulations. These algorithms combine ideas from averaging and linear quadratic regulation. Computer simulations are included to illustrate the effectiveness of the proposed control laws. C2 - 2011/6// C3 - Proceedings of 5th International Conference on Recent Advances in Space Technologies - RAST2011 DA - 2011/6// DO - 10.1109/rast.2011.5966973 PB - IEEE SN - 9781424496174 UR - http://dx.doi.org/10.1109/rast.2011.5966973 DB - Crossref ER - TY - CONF TI - Nonlinear control of space vehicles with multi-mass fuel slosh dynamics AU - Reyhanoglu, Mahmut AU - Hervas, Jaime Rubio T2 - 2011 5th International Conference on Recent Advances in Space Technologies (RAST) AB - This paper studies the maneuvering control problem for 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, as is typical for spacecraft maneuvering problems, is to control the translational velocity vector and the attitude of the spacecraft, while attenuating the sloshing modes characterizing the internal dynamics. Subsequently, a nonlinear mathematical model that reflects all of these assumptions is derived. Finally, a Lyapunov-based nonlinear feedback controller is designed to achieve this control objective. A simulation example is included to illustrate the effectiveness of the controller. C2 - 2011/6// C3 - Proceedings of 5th International Conference on Recent Advances in Space Technologies - RAST2011 DA - 2011/6// DO - 10.1109/rast.2011.5966834 PB - IEEE SN - 9781424496174 UR - http://dx.doi.org/10.1109/rast.2011.5966834 DB - Crossref ER - TY - JOUR TI - Hierarchical sliding mode observers for distributed parameter systems AU - Drakunov, Sergey V AU - Reyhanoglu, Mahmut T2 - Journal of Vibration and Control AB - In this work we suggest hierarchical sliding mode observers for complex systems which include distributed parameter systems and combinations of distributed parameter and lumped parameter systems, modeling, for example, an actuator dynamics. The main idea is based on the observer suggested previously for general nonlinear lumped parameter systems that is using the equivalent values of the discontinuous function to obtain additional information about the system state. Such observers can be written directly into system’s original variables without requiring the state transformation. In this paper, using a modal representation of the distributed system and the hierarchy of sliding modes, we develop a structure of such an observer for a wide class of systems described by partial differential equations or combinations of ordinary and partial differential equations. An example is presented which illustrates the proposed method. DA - 2011/9// PY - 2011/9// DO - 10.1177/1077546310370401 VL - 17 IS - 10 SP - 1441-1453 J2 - Journal of Vibration and Control LA - en OP - SN - 1077-5463 1741-2986 UR - http://dx.doi.org/10.1177/1077546310370401 DB - Crossref KW - Sliding mode observer KW - distributed parameter systems ER - TY - JOUR TI - Mechanics of Nanoindentation on a Monolayer of Colloidal Hollow Nanoparticles AU - Yin, Jie AU - Retsch, Markus AU - Lee, Jae-Hwang AU - Thomas, Edwin L. AU - Boyce, Mary C. T2 - Langmuir AB - We explore the collective mechanical behavior of monolayer assemblies composed of close-packed arrays of hollow silica nanoparticles using a spherical nanoindentor. Seven types of well-defined hollow nanoparticles are studied with their radii ranging from 100 to 300 nm and shell thickness ranging from 14 to 44 nm. Micromechanical models reveal the underlying deformation mechanisms during indentation, where the consecutive contacting of the indentor with an increasing number of nanoparticles results in a nonlinear increase in the indentation force with penetration depth. Each contacted hollow nanoparticle successively locally bends, flattens, and then locally buckles. The effective indentation modulus of the monolayer film, which is obtained by a Hertzian fit to the experimental data, is found to be proportional to the elastic modulus of the nanoparticle shell material and scales exponentially with the ratio of particle shell thickness t to radius R to the power of 2.3. Furthermore, we find that for a constant film density with the same t/R of the constituent nanoparticles, smaller particles with a thinner shell can provide a higher effective indentation modulus, compared to their larger diameter and thicker shell counterparts. This study provides useful insights and guidance for constructing high-performance lightweight nanoparticle films and coatings with potential applications in tailoring stiffness and mechanical energy absorption. DA - 2011/9/6/ PY - 2011/9/6/ DO - 10.1021/la2018117 VL - 27 IS - 17 SP - 10492-10500 J2 - Langmuir LA - en OP - SN - 0743-7463 1520-5827 UR - http://dx.doi.org/10.1021/la2018117 DB - Crossref ER - TY - JOUR TI - Electrical and dielectric properties of polyaniline–Al2O3 nanocomposites derived from various Al2O3 nanostructures AU - Zhu, Jiahua AU - Wei, Suying AU - Zhang, Lei AU - Mao, Yuanbing AU - Ryu, Jongeun AU - Haldolaarachchige, Neel AU - Young, David P. AU - Guo, Zhanhu T2 - Journal of Materials Chemistry AB - Four Al2O3 nanostructures (i.e. nanofiber, nanoplatelet, nanorod and nanoflake) have been successfully synthesized via hydrothermal procedures followed by a dehydration process. Subsequently, polyaniline (PANI) nanocomposites incorporating these four Al2O3 nanostructures have been fabricated using a surface initialized polymerization (SIP) method. Both TEM and SEM are used to characterize the morphologies of the Al2O3 nanostructures and PANI/Al2O3 nanocomposites. X-Ray diffraction results reveal that the morphology of the nanofiller has a significant effect on the crystallization behavior of the PANI during polymerization. The electrical conductivity and dielectric permittivity of these nanocomposites are strongly related to both the morphology of the filler and the dispersion quality. Temperature-dependent-conductivity measurements from 50–290 K show that the electron transportation of the nanocomposites follows a quasi 3-d variable range hopping (VRH) conduction mechanism. The extent of charge carrier delocalization calculated from VRH is well correlated to the dielectric response of these nanocomposites. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) results reveal an enhanced thermal stability of the PANI/Al2O3 nanocomposites as compared to that of pure PANI due to the strong interaction between the nanofillers and polymer matrix. The mechanism of the SIP method is also elaborated in this work. DA - 2011/// PY - 2011/// DO - 10.1039/c0jm03908j VL - 21 IS - 11 SP - 3952 J2 - J. Mater. Chem. LA - en OP - SN - 0959-9428 1364-5501 UR - http://dx.doi.org/10.1039/c0jm03908j DB - Crossref ER - TY - JOUR TI - Polyaniline-tungsten oxide metacomposites with tunable electronic properties AU - Zhu, Jiahua AU - Wei, Suying AU - Zhang, Lei AU - Mao, Yuanbing AU - Ryu, Jongeun AU - Karki, Amar B. AU - Young, David P. AU - Guo, Zhanhu T2 - J. Mater. Chem. AB - Polyaniline (PANI) nanocomposites reinforced with tungsten oxide (WO3) nanoparticles (NPs) and nanorods (NRs) are fabricated via a facile surface-initiated-polymerization (SIP) method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations reveal the uniform coating of polymer on the filler surface and a good dispersion of the nanofillers within the polymer matrix. Unique negative permittivity is observed in pure PANI and its nanocomposites. The switching frequency (frequency where real permittivity switches from negative to positive) can be easily tuned by changing the particle loading and filler morphology. Conductivity measurements are performed from 50∼290 K, and results show that the electron transportation in the nanocomposites follows a quasi 3-d variable range hopping (VRH) conduction mechanism. The extent of charge carrier delocalization calculated from VRH well explains the dielectric response of the metacomposites. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) reveal an enhanced thermal stability of the nanocomposites with the addition of nanofillers as compared to that of pure PANI. DA - 2011/// PY - 2011/// DO - 10.1039/c0jm02090g VL - 21 IS - 2 SP - 342-348 J2 - J. Mater. Chem. LA - en OP - SN - 0959-9428 1364-5501 UR - http://dx.doi.org/10.1039/c0jm02090g DB - Crossref ER - TY - JOUR TI - Stable Hierarchical Model Predictive Control Using an Inner Loop Reference Model* AU - Vermillion, Chris AU - Menezes, Amor AU - Kolmanovsky, Ilya T2 - IFAC Proceedings Volumes AB - This paper proposes a novel hierarchical model predictive control (MPC) strategy that guarantees overall system stability. Our 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, our approach 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 our method applicable to systems that do not possess the level of time scale separation that is required to apply the multi-rate framework successfully. Stability constraints for the proposed algorithm are derived, and the effectiveness of the proposed reference model-based strategy is shown through simulation on a 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 - 2011/1// PY - 2011/1// DO - 10.3182/20110828-6-it-1002.02733 VL - 44 IS - 1 SP - 9278-9283 J2 - IFAC Proceedings Volumes LA - en OP - SN - 1474-6670 UR - http://dx.doi.org/10.3182/20110828-6-it-1002.02733 DB - Crossref ER - TY - JOUR TI - Influence of multiple gas inlet jets on fluidized bed hydrodynamics using Particle Image Velocimetry and Digital Image Analysis AU - Agarwal, Gaurav AU - Lattimer, Brian AU - Ekkad, Srinath AU - Vandsburger, Uri T2 - Powder Technology AB - A rectangular fluidized bed setup was developed to study the evolution of inlet gas jets located at the distributor. Experiments were conducted with varying distributor types and bed media to understand the motion of particles and jets in the grid-zone region of a fluidized bed. Particle Image Velocimetry and Digital Image Analysis were used to quantify the parameters that characterize these jets. A grid-zone phenomenological model was developed to compare these parameters with those available in the literature. It was determined from this study that jet penetration length behavior is consistently different for fluidization velocities below and above the minimum fluidization. For velocities above minimum fluidization, jet lengths were found to increase more rapidly with increase in orifice velocity than for operating conditions below minimum fluidization. DA - 2011/11// PY - 2011/11// DO - 10.1016/j.powtec.2011.08.002 VL - 214 IS - 1 SP - 122-134 J2 - Powder Technology LA - en OP - SN - 0032-5910 UR - http://dx.doi.org/10.1016/j.powtec.2011.08.002 DB - Crossref KW - Two-dimensional beds KW - Multiple jets KW - Phenomenological model KW - Grid-zone KW - Particle Image Velocimetry KW - Digital Image Analysis ER - TY - JOUR TI - Experimental and numerical investigation of confined oblique impingement configurations for high heat flux applications AU - Parida, Pritish R. AU - Ekkad, Srinath V. AU - Ngo, Khai T2 - International Journal of Thermal Sciences AB - Breakthroughs in recent cutting-edge electronic technologies have become increasingly dependent on the ability to safely dissipate large amount of heat from small areas. Improvements in cooling methodologies are therefore required to avoid unacceptable temperature rise and at the same time maintain a high efficiency. Jet impingement is one such cooling scheme which has been widely used to dissipate transient and steady concentrated heat loads. The configuration examined in the present paper aims at wall-integrated inclined impinging jets in a confined environment. Coolant outlet is perpendicular to the plane of the impinging jets and is along the cross-flow direction. The main objective of the present work is to gain insight both experimentally and numerically into designing and analysis of a jet impinging cooling scheme for high heat density applications systems such as micro- and meso-scale electronic systems and trailing edge of a turbine blade. An overall enhancement of 150%–200% in the maximum heat transfer coefficient has been recorded both experimentally and computationally due to impingement and associated swirl. Results are presented to show the effect of the wall induced swirl and the associated enhanced heat transfer mechanism. The presence of fins between the jets further increases the cooling area and adds additional conduction area. The present scheme is therefore expected to provide alternatives for overcoming the existing heat distribution and cooling problems in high heat flux dissipating devices. DA - 2011/6// PY - 2011/6// DO - 10.1016/j.ijthermalsci.2011.01.010 VL - 50 IS - 6 SP - 1037-1050 J2 - International Journal of Thermal Sciences LA - en OP - SN - 1290-0729 UR - http://dx.doi.org/10.1016/j.ijthermalsci.2011.01.010 DB - Crossref KW - Jet impingement cooling KW - Electronic cooling KW - Thermal management ER - TY - JOUR TI - Computer Simulation of Nerve Transfer Strategies for Restoring Shoulder Function After Adult C5 and C6 Root Avulsion Injuries AU - Crouch, Dustin L. AU - Li, Zhongyu AU - Barnwell, Jonathan C. AU - Plate, Johannes F. AU - Daly, Melissa AU - Saul, Katherine R. T2 - The Journal of Hand Surgery AB - Purpose Functional ability after nerve transfer for upper brachial plexus injuries relies on both the function and magnitude of force recovery of targeted muscles. Following nerve transfers targeting either the axillary nerve, suprascapular nerve, or both, it is unclear whether functional ability is restored in the face of limited muscle force recovery. Methods We used a computer model to simulate flexing the elbow while maintaining a functional shoulder posture for 3 nerve transfer scenarios. We assessed the minimum restored force capacity necessary to perform the task, the associated compensations by neighboring muscles, and the effect of altered muscle coordination on movement effort. Results The minimum force restored by the axillary, suprascapular, and combined nerve transfers that was required for the model to simulate the desired movement was 25%, 40%, and 15% of the unimpaired muscle force capacity, respectively. When the deltoid was paralyzed, the infraspinatus and subscapularis muscles generated higher shoulder abduction moments to compensate for deltoid weakness. For all scenarios, movement effort increased as restored force capacity decreased. Conclusions Combined axillary and suprascapular nerve transfer required the least restored force capacity to perform the desired elbow flexion task, whereas single suprascapular nerve transfer required the most restored force capacity to perform the same task. Although compensation mechanisms allowed all scenarios to perform the desired movement despite weakened shoulder muscles, compensation increased movement effort. Dynamic simulations allowed independent evaluation of the effect of restored force capacity on functional outcome in a way that is not possible experimentally. Clinical relevance Simultaneous nerve transfer to suprascapular and axillary nerves yields the best simulated biomechanical outcome for lower magnitudes of muscle force recovery in this computer model. Axillary nerve transfer performs nearly as well as the combined transfer, whereas suprascapular nerve transfer is more sensitive to the magnitude of reinnervation and is therefore avoided. Functional ability after nerve transfer for upper brachial plexus injuries relies on both the function and magnitude of force recovery of targeted muscles. Following nerve transfers targeting either the axillary nerve, suprascapular nerve, or both, it is unclear whether functional ability is restored in the face of limited muscle force recovery. We used a computer model to simulate flexing the elbow while maintaining a functional shoulder posture for 3 nerve transfer scenarios. We assessed the minimum restored force capacity necessary to perform the task, the associated compensations by neighboring muscles, and the effect of altered muscle coordination on movement effort. The minimum force restored by the axillary, suprascapular, and combined nerve transfers that was required for the model to simulate the desired movement was 25%, 40%, and 15% of the unimpaired muscle force capacity, respectively. When the deltoid was paralyzed, the infraspinatus and subscapularis muscles generated higher shoulder abduction moments to compensate for deltoid weakness. For all scenarios, movement effort increased as restored force capacity decreased. Combined axillary and suprascapular nerve transfer required the least restored force capacity to perform the desired elbow flexion task, whereas single suprascapular nerve transfer required the most restored force capacity to perform the same task. Although compensation mechanisms allowed all scenarios to perform the desired movement despite weakened shoulder muscles, compensation increased movement effort. Dynamic simulations allowed independent evaluation of the effect of restored force capacity on functional outcome in a way that is not possible experimentally. DA - 2011/10// PY - 2011/10// DO - 10.1016/j.jhsa.2011.07.019 VL - 36 IS - 10 SP - 1644-1651 J2 - The Journal of Hand Surgery LA - en OP - SN - 0363-5023 UR - http://dx.doi.org/10.1016/j.jhsa.2011.07.019 DB - Crossref KW - Biomechanics KW - computer simulation KW - brachial plexus KW - nerve transfer KW - shoulder ER - TY - JOUR TI - Postural dependence of passive tension in the supraspinatus following rotator cuff repair: A simulation analysis AU - Saul, Katherine R. AU - Hayon, Solomon AU - Smith, Thomas L. AU - Tuohy, Christopher J. AU - Mannava, Sandeep T2 - Clinical Biomechanics AB - Background Despite surgical advances, repair of rotator cuff tears is associated with 20–70% incidence of recurrent tearing. The tension required to repair the torn tendon influences surgical outcomes and may be dependent on the gap length from torn tendon that must be spanned by the repair. Detailed understanding of forces throughout the range of motion (ROM) may allow surgeons to make evidence-based recommendations for post-operative care. Methods We used a computational shoulder model to assess passive tension and total moment-generating capacity in supraspinatus for repairs of gaps up to 3 cm throughout the shoulder (ROM). Findings In 60° abduction, increased gap length from 0.5 cm to 3 cm caused increases in passive force from 3 N to 58 N, consistent with those seen during clinical repair. For reduced abduction, passive forces increased substantially. For a 0.5 cm gap, tension throughout the ROM (elevation, plane of elevation, and rotation) is within reasonable limits, but larger gaps are associated with tensions that markedly exceed reported pull-out strength of sutures and anchors. Peak moment for a large 3 cm gap length was 5.09 Nm, a 53% reduction in moment-generating capacity compared to uninjured supraspinatus. Interpretation We conclude that shoulder posture is an important determinant of passive forces during rotator cuff repair surgery. Choosing postures that reduce forces intraoperatively to permit repair of larger gaps may lead to failure postoperatively when the shoulder is mobilized. For larger defects, loss of strength in supraspinatus may be substantial following repair even if retear is prevented. DA - 2011/10// PY - 2011/10// DO - 10.1016/j.clinbiomech.2011.04.005 VL - 26 IS - 8 SP - 804-810 J2 - Clinical Biomechanics LA - en OP - SN - 0268-0033 UR - http://dx.doi.org/10.1016/j.clinbiomech.2011.04.005 DB - Crossref KW - Computation KW - Musculoskeletal KW - Strength KW - Shoulder KW - Rotator cuff ER - TY - JOUR TI - Contributions of Neural Tone to In Vivo Passive Muscle–Tendon Unit Biomechanical Properties in a Rat Rotator Cuff Animal Model AU - Mannava, Sandeep AU - Wiggins, Walter F. AU - Saul, Katherine R. AU - Stitzel, Joel D. AU - Smith, Beth P. AU - Andrew Koman, L. AU - Smith, Thomas L. AU - Tuohy, Christopher J. T2 - Annals of Biomedical Engineering DA - 2011/3/29/ PY - 2011/3/29/ DO - 10.1007/S10439-011-0301-X VL - 39 IS - 7 SP - 1914-1924 J2 - Ann Biomed Eng LA - en OP - SN - 0090-6964 1573-9686 UR - http://dx.doi.org/10.1007/S10439-011-0301-X DB - Crossref KW - Botulinum neurotoxin A KW - Soft-tissue biomechanics KW - Rat rotator cuff KW - Skeletal muscle tone ER - TY - JOUR TI - Shock loading of 3D woven composites: A validated finite element investigation AU - Pankow, M. AU - Waas, A.M. AU - Yen, Chian-Fong AU - Ghiorse, Seth T2 - Composite Structures AB - In a companion paper in this issue (Pankow et al., 2010 [1]), experimental results for the deformation response of 3D glass fiber textile composites subjected to shock wave pulse pressure loading were presented. In this paper, finite element models are developed to simulate the deformation response and damage development observed in the experiments. Two levels of models are presented, with the first focused on a layered, homogenous orthotropic model that examined the bulk macroscopic deformation response. In the second model, each layer is represented to capture the interactions between fiber tows and matrix, taking into account the discrete non-homogeneous material distribution in each layer. Both models incorporated a user defined subroutine within the commercial software ABAQUS to capture matrix micro-cracking, which is responsible for damage development and growth. Results from the computational models correlated well with experimental results and observed locations of matrix micro-cracking. DA - 2011/4// PY - 2011/4// DO - 10.1016/j.compstruct.2010.11.001 VL - 93 IS - 5 SP - 1347-1362 J2 - Composite Structures LA - en OP - SN - 0263-8223 UR - http://dx.doi.org/10.1016/j.compstruct.2010.11.001 DB - Crossref KW - Shock loading KW - Matrix micro-cracking KW - High strain rate KW - Shock modeling KW - Material characterization KW - Finite elements ER - TY - JOUR TI - Shock response of 3D woven composites: An experimental investigation AU - Pankow, M. AU - Justusson, B. AU - Salvi, A. AU - Waas, A.M. AU - Yen, Chian-Fong AU - Ghiorse, Seth T2 - Composite Structures AB - A modified shock tube was used to determine the effect of shock wave loading on 3D woven composite panels. The shock wave, which produces a short duration steeply rising pressure pulse when impacting the panel, was used to load the panels. The out of plane deformation response was measured using a full field Digital Image Correlation (DIC) technique. The results allow for measurements of full field displacements and strains in the samples. Three distinct textile composite architectures, corresponding to different amounts of Z-fiber (fiber tows that bind the different textile layers together) were investigated. Two separate shock intensities were used. Matrix micro-cracking was observed to be the mechanism by which failure is initiated, and this micro-cracking was found to occur closest to the center of the panel where the outer-surface straining is highest. Fiber tow failure was absent in the shock strengths studied in the present work. The results suggest that the 6% Z-fiber architecture provided the largest panel stiffness and the least amount of damage. This result suggests that this may be the optimal architecture and density for orthogonally woven Z-fiber reinforced composites, however due to the complex nature of the problem the same architecture with a different tow (and fiber) volume fraction may yield different results. DA - 2011/4// PY - 2011/4// DO - 10.1016/j.compstruct.2010.10.021 VL - 93 IS - 5 SP - 1337-1346 J2 - Composite Structures LA - en OP - SN - 0263-8223 UR - http://dx.doi.org/10.1016/j.compstruct.2010.10.021 DB - Crossref KW - Shock loading KW - Matrix micro-cracking KW - High strain rate KW - 3D woven KW - Bending KW - Material characterization ER - TY - JOUR TI - Split Hopkinson pressure bar testing of 3D woven composites AU - Pankow, M. AU - Salvi, A. AU - Waas, A.M. AU - Yen, C.F. AU - Ghiorse, S. T2 - Composites Science and Technology AB - Results from a series of split Hopkinson pressure bar (SHPB) tests on 3D woven tetxile composites (3DWC) are presented. These tests were done to determine the rate dependent compression response of 3DWC. Three different configurations of the 3DWC, corresponding to compression response in the plane of the material and through-the-thickness direction (out-of-plane) were studied. The rate dependent responses were compared against quasi-static test results and it was found that 3DWC showed an increase in strength in all three directions studied, however, accompanied by a transition in the failure mechanism. The in-plane orientations showed the largest increase in (about 100%) strength at the elevated rates of loading. A follow-on paper provides finite element based results that correspond to the experimental results presented here. DA - 2011/6// PY - 2011/6// DO - 10.1016/j.compscitech.2011.03.017 VL - 71 IS - 9 SP - 1196-1208 J2 - Composites Science and Technology LA - en OP - SN - 0266-3538 UR - http://dx.doi.org/10.1016/j.compscitech.2011.03.017 DB - Crossref KW - Impact behaviour KW - Braiding KW - Mechanical properties KW - Textile composites KW - Delamination KW - Plastic Deformation ER - TY - JOUR TI - Resistance to delamination of 3D woven textile composites evaluated using End Notch Flexure (ENF) tests: Cohesive zone based computational results AU - Pankow, M. AU - Waas, A.M. AU - Yen, C.F. AU - Ghiorse, S. T2 - Composites Part A: Applied Science and Manufacturing AB - The flexural response of 3D woven textile composite panels containing an edge crack is evaluated using the End Notch Flexure (ENF) test. In doing so, the effectiveness of 3D reinforcement in increasing and/or eliminating delamination is demonstrated. A finite element model of the ENF configuration using the Discrete Cohesive Zone Model (DCZM) was used to evaluate the deformation response and fracture properties corresponding to the experimental results presented in Pankow et al. (2011) [1]. A modified trapezoidal traction law was used in the DCZM to computationally evaluate the ENF test results. Good agreement between experimental results and predictions are reported, up to the point at which the crack reaches under the loading roller and damage begins to occur locally under the roller. DA - 2011/12// PY - 2011/12// DO - 10.1016/j.compositesa.2011.07.028 VL - 42 IS - 12 SP - 1863-1872 J2 - Composites Part A: Applied Science and Manufacturing LA - en OP - SN - 1359-835X UR - http://dx.doi.org/10.1016/j.compositesa.2011.07.028 DB - Crossref KW - 3-Dimensional reinforcement KW - Fracture KW - Impact behavior KW - Finite element analysis (FEA) ER - TY - JOUR TI - Resistance to delamination of 3D woven textile composites evaluated using End Notch Flexure (ENF) tests: Experimental results AU - Pankow, M. AU - Salvi, A. AU - Waas, A.M. AU - Yen, C.F. AU - Ghiorse, S. T2 - Composites Part A: Applied Science and Manufacturing AB - The flexural response of 3D woven textile composite panels containing an edge crack is evaluated using the End Notch Flexure (ENF) test. In doing so, the effectiveness of 3D reinforcement in increasing and/or eliminating delamination is demonstrated. Two types of textile architectures, referred to as Z-fiber reinforcement and a layer-to-layer architecture were examined. At quasi-static and low rate; 0.01 mm/Section (0.0004 in/s) and 50.8 mm/Section (2 in/s), results showed that the Z-fiber reinforcement provided a higher strength, although the layer-to-layer reinforcement provided more energy absorption and prevented mode II crack propagation, thus providing insight into eliminating the delamination mode of failure. At higher loading rates, using an instrumented drop tower at impactor velocities of 2.79 m/Section (110 in/s) and 3.96 m/Section (156 in/s), results suggested a rate dependent mode II strength of the material. Computational models to further explore the experimental results are presented in a follow-on paper in this issue of the journal [1]. DA - 2011/10// PY - 2011/10// DO - 10.1016/j.compositesa.2011.06.013 VL - 42 IS - 10 SP - 1463-1476 J2 - Composites Part A: Applied Science and Manufacturing LA - en OP - SN - 1359-835X UR - http://dx.doi.org/10.1016/j.compositesa.2011.06.013 DB - Crossref KW - 3-Dimensional reinforcement KW - Fracture KW - Fracture toughness KW - Impact behavior ER - TY - JOUR TI - Method for acquiring pressure measurements in presence of plasma-induced interference for supersonic flow control applications AU - Narayanaswamy, Venkateswaran AU - Clemens, Noel T AU - Raja, Laxminarayan L T2 - Measurement Science and Technology AB - The operation of pulsed-plasma actuators for flow control is often associated with the presence of charged species in the flow and severe electromagnetic interference with external circuitry. These effects can lead to time-resolved transducer pressure measurements that are contaminated with electromagnetic interference effects or even transducer damage due to the interaction with charged species. A new technique is developed that enables high-bandwidth pressure measurements to be made in the presence of such rapidly switched plasma actuators. The technique is applied for the specific configuration of a pulsed-plasma jet actuator (spark jet) that is used to control the unsteadiness of a shock wave/boundary layer interaction generated by a compression ramp in a Mach 3 flow. The critical component of the technique involves using a pulsed-ground electrode to drain the charged species from the plasma jet before they reach the pressure transducer. The pulsed-ground electrode was shown to drain charged species into the pulsed ground prior to interacting with the transducer, which made it possible to make measurements without damaging the transducer. The resulting signals were still contaminated by electromagnetic interference spikes and so a data-processing technique was used to remove the artifacts and recover a largely uncontaminated power spectrum. The signal processing scheme used interpolation schemes previously developed for laser Doppler velocimetry applications. The data-processing procedure is demonstrated with a benchmark case in which the electromagnetic interference was isolated from the pulsed-plasma jet actuation effect. It is shown that the data-processing procedure removed the contamination from the electromagnetic interference at all frequencies but for the pulsing frequency and its higher harmonics. DA - 2011/11/15/ PY - 2011/11/15/ DO - 10.1088/0957-0233/22/12/125107 VL - 22 IS - 12 SP - 125107 J2 - Meas. Sci. Technol. OP - SN - 0957-0233 1361-6501 UR - http://dx.doi.org/10.1088/0957-0233/22/12/125107 DB - Crossref KW - plasma discharge KW - electromagnetic interference KW - flow control KW - shock wave KW - separation KW - actuator KW - jets ER - TY - JOUR TI - Mixture fraction imaging in turbulent non-premixed flames with two-photon LIF of krypton AU - Hsu, A.G. AU - Narayanaswamy, V. AU - Clemens, N.T. AU - Frank, J.H. T2 - Proceedings of the Combustion Institute AB - The use of a noble gas as an inert tracer for mixing studies in combustion systems is investigated. Simultaneous two-photon laser-induced fluorescence (LIF) of krypton and Rayleigh scattering are used for imaging measurements of mixture fraction and temperature in turbulent non-premixed jet flames. The turbulent flames investigated in this study include a piloted CH4/air flame (Sandia flame D) and a CH4/H2/N2 flame (DLR-B flame). These flames are well-documented in the literature and enable an evaluation of krypton as a tracer in different fuel mixtures with varying degrees of differential diffusion. Krypton is excited from the ground state to the 5p[3/2]2 state using 215 nm laser radiation, and the fluorescence decay to the metastable state, 5s[3/2]2, is detected at 760 nm. Single-shot krypton LIF and Rayleigh scattering images are analyzed in an iterative routine to determine mixture fraction and temperature. Measurements of the temperature- and species-dependent quenching rates for Kr-LIF are incorporated into this routine. The resulting average radial profiles of mixture fraction and temperature for both flames agree well with previously published measurements. The use of a noble gas as a chemically inert tracer has potential applications for mixing studies in a broad range of combustion environments. DA - 2011/// PY - 2011/// DO - 10.1016/j.proci.2010.06.051 VL - 33 IS - 1 SP - 759-766 J2 - Proceedings of the Combustion Institute LA - en OP - SN - 1540-7489 UR - http://dx.doi.org/10.1016/j.proci.2010.06.051 DB - Crossref KW - Turbulent flames KW - Mixture fraction imaging KW - Two-photon LIF imaging ER - TY - JOUR TI - Combining two-dimensional spatially selective RF excitation, parallel imaging, and UNFOLD for accelerated MR thermometry imaging AU - Mei, Chang-Sheng AU - Panych, Lawrence P. AU - Yuan, Jing AU - McDannold, Nathan J. AU - Treat, Lisa H. AU - Jing, Yun AU - Madore, Bruno T2 - Magnetic Resonance in Medicine AB - Abstract MR thermometry can be a very challenging application, as good resolution may be needed along spatial, temporal, and temperature axes. Given that the heated foci produced during thermal therapies are typically much smaller than the anatomy being imaged, much of the imaged field‐of‐view is not actually being heated and may not require temperature monitoring. In this work, many‐fold improvements were obtained in terms of temporal resolution and/or 3D spatial coverage by sacrificing some of the in‐plane spatial coverage. To do so, three fast‐imaging approaches were jointly implemented with a spoiled gradient echo sequence: (1) two‐dimensional spatially selective RF excitation, (2) unaliasing by Fourier encoding the overlaps using the temporal dimension (UNFOLD), and (3) parallel imaging. The sequence was tested during experiments with focused ultrasound heating in ex vivo tissue and a tissue‐mimicking phantom. Temperature maps were estimated from phase‐difference images based on the water proton resonance frequency shift. Results were compared to those obtained from a spoiled gradient echo sequence sequence, using a t ‐test. Temporal resolution was increased by 24‐fold, with temperature uncertainty less than 1°C, while maintaining accurate temperature measurements (mean difference between measurements, as observed in gel = 0.1°C ± 0.6; R = 0.98; P > 0.05). Magn Reson Med 66:112–122, 2011. © 2011 Wiley‐Liss, Inc. DA - 2011/2/17/ PY - 2011/2/17/ DO - 10.1002/mrm.22788 VL - 66 IS - 1 SP - 112-122 J2 - Magn. Reson. Med. LA - en OP - SN - 0740-3194 UR - http://dx.doi.org/10.1002/mrm.22788 DB - Crossref KW - 2DRF excitations KW - UNFOLD KW - parallel imaging KW - fast imaging KW - MR thermometry ER - TY - JOUR TI - The pre-stack migration imaging technique for damages identification in concrete structures AU - Luo, Ying AU - Wang, Ziping AU - Xu, Baiqiang AU - Yuan, Fuhgwo T2 - Theoretical and Applied Mechanics Letters AB - Pre-stack migration imaging (PMI) method, which is used in geophysical exploration by the performance of single side detection and visually display, can be used to identify the location, orientation, and severity of damages in concrete structure. In particular, this letter focuses on the experimental study by using a finite number of sensors for further practical applications. A concrete structure with a surface-mounted linear PZT transducers array is illustrated. Three types of damages, horizontal, dipping and V-shaped crack damage, have been studied. A pre-stack reverse time migration technique is used to back-propagate the scattering waves and to image damages in concrete structure. The migration results from the scattering waves of an artificial damage are presented. It is shown that the existence of the damage in concrete structure is correctly revealed through migration process. DA - 2011/// PY - 2011/// DO - 10.1063/2.1105104 VL - 1 IS - 5 SP - 051004 J2 - Theoretical and Applied Mechanics Letters LA - en OP - SN - 2095-0349 UR - http://dx.doi.org/10.1063/2.1105104 DB - Crossref KW - ultrasonic waves KW - PMI KW - damage identification ER - TY - JOUR TI - Nonlinear vibration energy harvester using diamagnetic levitation AU - Liu, L. AU - Yuan, F. G. T2 - Applied Physics Letters AB - This letter proposes a nonlinear vibration energy harvester based on stabilized magnetic levitation using diamagnetic. Restoring forces induced by the magnetic field in harvesting vibration energy is employed instead of the forces introduced by conventional mechanical suspensions; therefore dissipation of vibration energy into heat through mechanical suspensions is eliminated. The core of the design consists of two spiral coils made of diamagnetic materials, which serve dual purposes: providing nonlinear restoring force and harnessing eddy current to power external circuits. From the theoretical analysis presented, the proposed harvester has the potential to provide wideband power outputs in low frequency range. DA - 2011/5/16/ PY - 2011/5/16/ DO - 10.1063/1.3583675 VL - 98 IS - 20 SP - 203507 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.3583675 DB - Crossref ER - TY - BOOK TI - Design of an eco-power automobile body made from green composite and its structural optimization in FEA AU - Luan, K. AU - Sun, B. AU - Gu, B. AU - Zhang, J. AB - Ramie (Boehmeria nivea) is a kind of natural fiber that has good mechanical and environmental friendly properties. The fabric woven by ramie yarns shows excellent dimensional stability. Polypropylene (PP) was used as matrix for its recyclable and thermoplastic properties. PP is the widely used thermoplastics for composite and currently it is very common in building, construction, furniture and automotive products. Since the eco-power automobile body was designed for light-weight and low fuel consumption, there seems to be high potential application to automobile industry for ramie-PP composite. Therefore, in this paper, we developed a constitution of fabric to form stable structure reinforcement. The reinforcement and PP particles were treated in vulcanizer by thermo-compression technology. The fundamental mechanical properties of the composite were tested for finite element analysis (FEA). An eco-power automobile body was designed in Pro/E ® Wildfire 5.0 and transferred to Finite Element Analysis Software for material and structural simulation analysis. Structural improvement and sizing optimization of the eco-power automobile body model were simulated to judge the material application and its structure effectiveness. DA - 2011/// PY - 2011/// DO - 10.4028/www.scientific.net/AMR.287-290.405 VL - 287-290 SE - 405-409 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79961228066&partnerID=MN8TOARS KW - Green composite KW - ramie KW - Polypropylene KW - FEA KW - light-weighting KW - simulation ER - TY - JOUR TI - A Multi-scale geometrical model for finite element analyses of three-dimensional angle-interlock woven composite under ballistic penetration AU - Luan, K. AU - Sun, B. AU - Gu, B. T2 - CMES - Computer Modeling in Engineering and Sciences DA - 2011/// PY - 2011/// VL - 79 IS - 1 SP - 31-61 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-82055206970&partnerID=MN8TOARS ER - TY - JOUR TI - Dislocation density evolution and interactions in crystalline materials AU - Shanthraj, P. AU - Zikry, M.A. T2 - Acta Materialia AB - Dislocation density-based evolution formulations that are related to a heterogeneous microstructure and are physically representative of different crystalline interactions have been developed. The balance between the generation and annihilation of dislocations, through glissile and forest interactions at the slip system level, is taken as the basis for the evolution of mobile and immobile dislocation densities. The evolution equations are coupled to a multiple slip crystal plasticity formulation, and a framework is established that relates it to a general class of crystallographies and deformation modes. Specialized finite element (FE) methodologies have then been used to investigate how certain dislocation density activities, such as dislocation density interactions and immobilization, are directly related to strain hardening and microstructure evolution. The predictions are validated with channel die compressed (CDC) experiments, and are consistent with inelastic deformation modes of fcc metals. DA - 2011/12// PY - 2011/12// DO - 10.1016/j.actamat.2011.08.041 VL - 59 IS - 20 SP - 7695-7702 J2 - Acta Materialia LA - en OP - SN - 1359-6454 UR - http://dx.doi.org/10.1016/j.actamat.2011.08.041 DB - Crossref KW - Dislocation density KW - Computational model KW - Crystal plasticity KW - Localization ER - TY - JOUR TI - Laminar-to-turbulent fluid-nanoparticle dynamics simulations: Model comparisons and nanoparticle-deposition applications AU - Zhang, Zhe AU - Kleinstreuer, Clement T2 - International Journal for Numerical Methods in Biomedical Engineering AB - SUMMARY Relying on benchmark experimental data sets for flow in conduits with local constrictions, LES and three widely used RANS turbulence models, i.e. the low Reynolds number (LRN) k‐ω model, standard k‐ω model and shear stress transport (SST) transition model, were compared and evaluated to gain new physical insight and provide useful turbulence modeling information. These two geometric test cases may represent stenosed arteries and a segment of the human upper airways where the velocity fields undergo all flow regimes, i.e. from laminar, via transitional, to fully turbulent. The comparison study revealed that the standard k‐ω models amplify the flow instabilities after the constrictions, and hence fail to capture the laminar flow behavior at relatively LRNs. The overall performances of LES, the LRN k‐ω model and SST transition model do not have measurable differences in predicting laminar flows and transition to turbulent flow, while the SST transition model may give a better prediction of turbulence kinetic energy profiles in some cases. Clearly, LES can provide instantaneous velocity fluctuations, which may be significant for turbulent micron particle transport/deposition in the respiratory tract. However, it requires 100‐fold more computational time than RANS turbulence models. The use of different turbulence models has a minor effect on nanoparticle deposition in human upper airways when the inspiratory flow rate is low, say, Q = 10L/min. The relative difference for deposition fraction (DF) of nanoparticles with d p >10nm is measurable at a medium inhalation flow rate (say, Q = 30L/min) when employing different turbulence models. However, the absolute difference in DFs is within 0.5% for all‐sized nanoparticles (i.e. 1nm⩽ d p ⩽50nm) because the DF in the oral airway is very low (say, <1.5%) when 10 nm and 10 L/min. The modeling and simulation information provided are most useful for computational fluid–particle dynamics practitioners to obtain accurate lung deposition concentrations of inhaled toxic or therapeutic nanoparticles. The physical insight provided sheds additional light on the laminar‐to‐turbulent airflow and nanoparticle transport/deposition in locally constricted conduits. Copyright © 2011 John Wiley & Sons, Ltd. DA - 2011/5/2/ PY - 2011/5/2/ DO - 10.1002/cnm.1447 VL - 27 IS - 12 SP - 1930-1950 J2 - Int. J. Numer. Meth. Biomed. Engng. LA - en OP - SN - 2040-7939 UR - http://dx.doi.org/10.1002/cnm.1447 DB - Crossref KW - laminar-to-turbulent flow KW - nanoparticle deposition KW - computer simulation KW - human upper airways ER - TY - JOUR TI - Diffraction efficiency of 200-nm-period critical-angle transmission gratings in the soft x-ray and extreme ultraviolet wavelength bands AU - Heilmann, Ralf K. AU - Ahn, Minseung AU - Bruccoleri, Alex AU - Chang, Chih-Hao AU - Gullikson, Eric M. AU - Mukherjee, Pran AU - Schattenburg, Mark L. T2 - Applied Optics AB - We report on measurements of the diffraction efficiency of 200-nm-period freestanding blazed transmission gratings for wavelengths in the 0.96 to 19.4 nm range. These critical-angle transmission (CAT) gratings achieve highly efficient blazing over a broad band via total external reflection off the sidewalls of smooth, tens of nanometer thin ultrahigh aspect-ratio silicon grating bars and thus combine the advantages of blazed x-ray reflection gratings with those of more conventional x-ray transmission gratings. Prototype gratings with maximum depths of 3.2 and 6 μm were investigated at two different blaze angles. In these initial CAT gratings the grating bars are monolithically connected to a cross support mesh that only leaves less than half of the grating area unobstructed. Because of our initial fabrication approach, the support mesh bars feature a strongly trapezoidal cross section that leads to varying CAT grating depths and partial absorption of diffracted orders. While theory predicts broadband absolute diffraction efficiencies as high as 60% for ideal CAT gratings without a support mesh, experimental results show efficiencies in the range of ∼50–100% of theoretical predictions when taking the effects of the support mesh into account. Future minimization of the support mesh therefore promises broadband CAT grating absolute diffraction efficiencies of 50% or higher. DA - 2011/3/25/ PY - 2011/3/25/ DO - 10.1364/ao.50.001364 VL - 50 IS - 10 SP - 1364 J2 - Appl. Opt. LA - en OP - SN - 0003-6935 1539-4522 UR - http://dx.doi.org/10.1364/ao.50.001364 DB - Crossref ER - TY - JOUR TI - Nanostructured gradient-index antireflection diffractive optics AU - Chang, Chih-Hao AU - Dominguez-Caballero, Jose A. AU - Choi, Hyungryul J. AU - Barbastathis, George T2 - Optics Letters AB - We describe the fabrication and characterization of a nanostructured diffractive element with near-zero reflection losses. In this element, subwavelength nanostructures emulating adiabatic index matching are integrated on the surface of a diffractive microstructure to suppress reflected diffraction orders. The fabricated silicon grating exhibits reflected efficiencies that are suppressed by 2 orders of magnitude over broad wavelength bands and wide incident angles. Theoretical models of the fabricated structure based on rigorous coupled-wave analysis and effective medium theory are in agreement with the experimental data. The proposed principles can be applied to improve the performance of any diffractive structures, potentially leading to more efficient Fresnel lenses, holographic elements, and integrated optical systems. DA - 2011/6/15/ PY - 2011/6/15/ DO - 10.1364/ol.36.002354 VL - 36 IS - 12 SP - 2354 J2 - Opt. Lett. LA - en OP - SN - 0146-9592 1539-4794 UR - http://dx.doi.org/10.1364/ol.36.002354 DB - Crossref ER - TY - JOUR TI - From Two-Dimensional Colloidal Self-Assembly to Three-Dimensional Nanolithography AU - Chang, C.-H. AU - Tian, L. AU - Hesse, W. R. AU - Gao, H. AU - Choi, H. J. AU - Kim, J.-G. AU - Siddiqui, M. AU - Barbastathis, G. T2 - Nano Letters AB - A number of "top-down" lithographic and "bottom-up" self-assembly methods have been developed to fabricate three-dimensional (3D) nanostructures to support the recent advances in nanotechnology. But they are limited by a number of factors such as fabrication cost, pattern resolution, and/or flexibility of geometry. Here we present a 3D nanolithography process that utilizes self-assembled nanospheres to create a periodic array of focal spots, which are then replicated across multiple depth in a transparent medium according to the Talbot effect. The Talbot field then exposes a pattern onto the underlying photoresist, recording the 3D intensity distribution. We have demonstrated designable complex 3D periodic structures with 80 nm minimum feature size, roughly one-fourth of the operating wavelength. This approach combines 2D colloidal self-assembly and 3D phase lithography, is robust, cost-effective, and widely applicable to nanoscale research and manufacturing. DA - 2011/6/8/ PY - 2011/6/8/ DO - 10.1021/nl2011824 VL - 11 IS - 6 SP - 2533-2537 J2 - Nano Lett. LA - en OP - SN - 1530-6984 1530-6992 UR - http://dx.doi.org/10.1021/nl2011824 DB - Crossref KW - 3D nanostructures KW - colloidal assembly KW - nanosphere lithography KW - phase lithography ER - TY - BOOK TI - Turbulent combustion: Concepts, governing equations and modeling strategies AU - Echekki, T. AU - Mastorakos, E. AB - The numerical modeling of turbulent combustion problems is based on the solution of a set of conservation equations for momentum and scalars, plus additional auxiliary equations. These equations have very well-defined foundations in their instantaneous and spatially-resolved forms and they represent a myriad of problems that are encountered in a very broad range of applications. However, their practical solution poses important problems. First, models of turbulent combustion problems form an important subset of models for turbulent flows. Second, the reacting nature of turbulent combustion flows imposes additional challenges of resolution of all relevant scales that govern turbulent combustion and closure for scalars. This chapter attempts to review the governing equations from the perspective of modern solution techniques, which take root in some of the classical strategies adopted to address turbulent combustion modeling. We also attempt to outline common themes and to provide an outlook where present efforts are heading. DA - 2011/// PY - 2011/// DO - 10.1007/978-94-007-0412-1_2 VL - 95 SE - 19-39 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84859956540&partnerID=MN8TOARS ER - TY - BOOK TI - The emerging role of multiscale methods in turbulent combustion AU - Echekki, T. DA - 2011/// PY - 2011/// DO - 10.1007/978-94-007-0412-1_8 VL - 95 SE - 177-192 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84859970461&partnerID=MN8TOARS ER - TY - BOOK TI - The one-dimensional-turbulence model AU - Echekki, T. AU - Kerstein, A.R. AU - Sutherland, J.C. AB - The one-dimensional turbulence (ODT) model represents an efficient and novel multiscale approach to couple the processes of reaction, diffusion and turbulent transport. The principal ingredients of the model include a coupled deterministic solution for reaction and molecular transport and a stochastic prescription for turbulent transport. The model may be implemented as stand-alone for simple turbulent flows and admits various forms for the description of spatially developing and temporally developing flows. It also may be implemented within the context of a coupled multiscale solution using the ODTLES approach. This chapter outlines the model formulation, and applications of ODT using stand-alone solutions and ODTLES. DA - 2011/// PY - 2011/// DO - 10.1007/978-94-007-0412-1_11 VL - 95 SE - 249-276 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84859994366&partnerID=MN8TOARS ER - TY - BOOK TI - Traditional and non-traditional control techniques for grinding processes AU - Liu, J. AU - Xu, C. AU - Jackson, M. DA - 2011/// PY - 2011/// DO - 10.1007/978-1-4419-7302-3_6 SE - 269-302 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84889788116&partnerID=MN8TOARS KW - Grinding KW - Control systems KW - Mathematical modeling KW - Quality ER - TY - JOUR TI - Synthesis of spherical non-oxide silicon carbonitride ceramic particles AU - Yu, Y. AU - Chen, Y. AU - Xu, C. AU - Fang, J. AU - An, L. T2 - Journal of the American Ceramic Society AB - In this article, we report a simple technique for synthesizing spherical non‐oxide silicon carbonitride ceramic particles from a polysilazane precursor. In this technique, the spherical particles of the polysilazane precursor were synthesized first via a precipitation polymerization process and then converted to ceramic particles by pyrolysis. The resultant ceramic particles exhibited a close‐to‐perfect spherical shape and a narrow size distribution around 430 nm. The precipitation and pyrolysis processes were characterized using SEM , TEM , FTIR , and XRD to illustrate the formation mechanisms of the ceramic particles. DA - 2011/// PY - 2011/// DO - 10.1111/j.1551-2916.2011.04713.x VL - 94 IS - 9 SP - 2779-2782 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80052973104&partnerID=MN8TOARS ER - TY - JOUR TI - Synthesis of nanostructured silicon carbide at ultralow temperature using self-assembled polymer micelles as a precursor AU - Yu, Y. AU - Yang, X. AU - Xu, C. AU - Fang, J. AU - An, L. T2 - Journal of Materials Chemistry AB - Nanostructured SiC ceramics exhibit unusual and superior properties compared to their microstructured counterparts, thus hold promise for widespread applications. We report a novel technique for synthesizing dense nanostructured SiC at an ultralow-temperature without pressure. In this technique, polyvinylsilazane-block-polystyrene (PVSZ-b-PS) block copolymers were synthesized and then self-assembled into nano-scaled micelles with the precursor PVSZ as the core and the sacrificial PS as the shell. The subsequent pyrolysis converted the aggregation of the micelles into dense nanostructured SiC with a grain size of ∼20–30 nm at 800 °C. DA - 2011/// PY - 2011/// DO - 10.1039/c1jm13973h VL - 21 IS - 44 SP - 17619-17622 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80455137269&partnerID=MN8TOARS ER - TY - JOUR TI - Self-assembled carbon-silicon carbonitride nanocomposites: High-performance anode materials for lithium-ion batteries AU - Chen, Y. AU - Li, C. AU - Wang, Y. AU - Zhang, Q. AU - Xu, C. AU - Wei, B. AU - An, L. T2 - Journal of Materials Chemistry AB - A new class of nanocomposites comprising an amorphous silicon carbonitride matrix and carbon nanoclusters was synthesized by decomposing polymeric precursors with thermally induced phase separation. Electrochemical measurements show that the nanocomposite with 30% of carbon nanoclusters exhibits a specific capacity of 480 mA h g−1 and excellent cycling performance. The high capacity of the nanocomposites is attributed to the formation of a novel structure around the SiCN–C interface. The excellent electrochemical properties, together with the simple, low-cost processing, make the nanocomposites very promising for Li-ion battery applications. DA - 2011/// PY - 2011/// DO - 10.1039/c1jm13733f VL - 21 IS - 45 SP - 18186-18190 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80755125485&partnerID=MN8TOARS ER - TY - CONF TI - Modeling and control of feed drive system for a micro-machining platform with nano-resolution AU - Ji, Y. AU - Zhao, R. AU - Xu, C. AB - The feed drive system plays a key role of increasing processing efficiency and improving machining quality of parts. The external disturbances, such as cutting forces and frictional nonlinearities seriously affect the machining quality. The feed drive system should be capable of rejecting such disturbances. In this paper, the feed drive system of a micro-machining platform with nano-resolution was modeled and controlled. A decoupled algorithm was implemented to linearly regulate flux-producing and force-producing currents of motor. The current controller was designed based on the electrical model of motor employing pole-zero cancellation method. The speed controllers, i.e., proportional-integral (PI) and sliding mode control (SMC) were designed and compared. The SMC exhibits the better property of rejecting the external disturbance compared to PI controller. The electromagnetic force produced by Linear Permanent Magnet Synchronous Machine (LPMSM) under SMC expresses the quicker response to external variations. The models will be further applied for the design of cross-coupling servo control for this five-axis reconfigurable micro-machining platform. C2 - 2011/// C3 - ASME 2011 Dynamic Systems and Control Conference and Bath/ASME Symposium on Fluid Power and Motion Control, DSCC 2011 DA - 2011/// DO - 10.1115/DSCC2011-6026 VL - 1 SP - 263-270 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84881465535&partnerID=MN8TOARS ER - TY - CONF TI - Investigation on the effect of SiC nanoparticles on cutting forces for micro-milling Magnesium Matrix Composites AU - Liu, J. AU - Li, J. AU - Ji, Y. AU - Xu, C. AB - Magnesium Metal Matrix Composites (Mg-MMCs) with nano-sized reinforcements exhibit better mechanical properties comparing to pure Magnesium (Mg) and its alloys. However, it is challenging to improve the machinability of this kind of composites. An analytical cutting force model for the micro-milling process was developed and validated to analyze the micro-machinability of the SiC nanoparticles reinforced Mg-MMCs. This model is different from the previous ones because it encompasses the behaviors of the reinforcement nanoparticles in the three cutting regimes, i.e., shearing, ploughing and elastic recovery. The volume fraction of particles and particle size are considered as two significant factors affecting the cutting forces in this model. The effects of the reinforcement nanoparticles on cutting forces were studied through modeling and experimental validation. The simulated cutting forces show a good agreement with the experimental data. Moreover, it is indicated that the amplitude and profile of cutting forces vary with the reinforcement particle’s volume fraction. This mainly arises from the strengthening effect of SiC nanoparticles. C2 - 2011/// C3 - ASME 2011 International Manufacturing Science and Engineering Conference, MSEC 2011 DA - 2011/// DO - 10.1115/MSEC2011-50170 VL - 2 SP - 525-536 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-82455175639&partnerID=MN8TOARS ER - TY - CONF TI - Analysis of a simultaneous CNC turning and boring operation via multisensor monitoring AU - Deane, E. AU - Hernandez, M. AU - Giesecke, D. AU - Meanor, M. AU - Collins, S. AU - Ji, Y. AU - Xu, C. AB - The introduction of multi-axis CNC machining has reduced machining time and increased production rates. However, optimizing simultaneous operations to produce quality parts and prolong tool life still possesses a challenge to engineers due to the mutual interactions of two tools removing material and the amount of factors and noise in a production environment. Since there are multiple factors and the sources of error are unknown, we use a statistical approach to obtain and organize information. A design of experiment study was implemented across twelve sensor responses to optimize the spindle speed, feed rate, inner diameter (ID) depth of cut and outer diameter (OD) depth of cut for simultaneous turning and boring roughing operations. The optimal machining conditions were obtained by a response optimizer from Minitab 16 statistical software. The optimized settings result in 13% reduced cutting and 10% reduced total power consumption for a 3% increase of average power. Future studies will cross correlate different responses to reduce the number of sensors in developing a robust adaptive controller for chatter detection and tool condition monitoring. C2 - 2011/// C3 - ASME 2011 International Manufacturing Science and Engineering Conference, MSEC 2011 DA - 2011/// DO - 10.1115/MSEC2011-50168 VL - 2 SP - 273-280 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-82455166830&partnerID=MN8TOARS ER - TY - JOUR TI - Aluminum nanocomposites having wear resistance better than stainless steel AU - An, L. AU - Qu, J. AU - Luo, J. AU - Fan, Y. AU - Zhang, L. AU - Liu, J. AU - Xu, C. AU - Blau, P.J. T2 - Journal of Materials Research DA - 2011/// PY - 2011/// DO - 10.1557/jmr.2011.263 VL - 26 IS - 19 SP - 2479-2483 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84873392830&partnerID=MN8TOARS ER - TY - JOUR TI - A self-tuning fuzzy controller for a class of multi-input multi-output nonlinear systems AU - Xu, C. AU - Shin, Y.C. T2 - Engineering Applications of Artificial Intelligence AB - This paper presents a systematic design procedure of a multivariable fuzzy controller for a general Multi-Input Multi-Output (MIMO) nonlinear system with an input–output monotonic relationship or a piecewise monotonic relationship for each input–output pair. Firstly, the system is modeled as a Fuzzy Basis Function Network (FBFN) and its Relative Gain Array (RGA) is calculated based on the obtained fuzzy model. The proposed multivariable fuzzy controller is constructed with two orthogonal fuzzy control engines. The horizontal fuzzy control engine for each system input–output pair has a hierarchical structure to update the control parameters online and compensate for unknown system variations. The perpendicular fuzzy control engine is designed based on the system RGA to eliminate the multivariable interaction effect. The resultant closed-loop fuzzy control system is proved to be passive stable as long as the augmented open-loop system is input–output passive. Two sets of simulation examples demonstrate that the proposed fuzzy control strategy can be a promising way in controlling multivariable nonlinear systems with unknown system uncertainties and time-varying parameters. DA - 2011/// PY - 2011/// DO - 10.1016/j.engappai.2010.10.021 VL - 24 IS - 2 SP - 238-250 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79151477967&partnerID=MN8TOARS KW - Fuzzy control KW - Self-tuning systems KW - Multi-input multi-output system KW - Relative gain array KW - Non-linear systems ER - TY - CONF TI - An Overview of Lithium-Ion Battery Cathode Materials AU - Wang, Yi-Xu AU - Huang, Hsiao-Ying Shadow AB - ABSTRACT The need for the development and deployment of reliable and efficient energy storage devices, such as lithium-ion rechargeable batteries, is becoming increasingly important due to the scarcity of petroleum. In this work, we provide an overview of commercially available cathode materials for Li-ion rechargeable batteries and focus on characteristics that give rise to optimal energy storage systems for future transportation modes. The study shows that the development of lithium-iron-phosphate (LiFePO 4 ) batteries promises an alternative to conventional lithiumion batteries, with their potential for high energy capacity and power density, improved safety, and reduced cost. This work contributes to the fundamental knowledge of lithium-ion battery cathode materials and helps with the design of better rechargeable batteries, and thus leads to economic and environmental benefits. C2 - 2011/// C3 - Materials Research Society 2011 Spring Meeting CY - San Francisco, CA DA - 2011/// DO - 10.1557/opl.2011.1363 SP - 1363-RR05-30 ER - TY - SOUND TI - Recent Advances on Wireless Passive High-Temperature Sensors for Harsh Environments AU - Gong, X. AU - An, L. AU - Xu, C. DA - 2011/// PY - 2011/// N1 - Invited RN - Invited ER - TY - SOUND TI - Investigation of Micro-End-Milling of Polymer-Derived Ceramics for High Temperature Micro-Sensor Fabrication AU - Liu, J. AU - Li, J. AU - Shao, G. AU - Ji, Y. AU - Xu, C. AU - An, L. DA - 2011/// PY - 2011/// ER - TY - JOUR TI - Modeling and testing of a novel aeroelastic flutter energy harvester AU - Bryant, Matthew AU - Garcia, Ephrahim T2 - Journal of Vibration and Acoustics AB - This paper proposes a novel piezoelectric energy harvesting device driven by aeroelastic flutter vibrations of a simple pin connected flap and beam. The system is subject to a modal convergence flutter response above a critical wind speed and then oscillates in a limit cycle at higher wind speeds. A linearized analytical model of the device is derived to include the effects of the three-way coupling between the structural, unsteady aerodynamic, and electrical aspects of the system. A stability analysis of this model is presented to determine the frequency and wind speed at the onset of the flutter instability, which dictates the cut-in conditions for energy harvesting. In order to estimate the electrical output of the energy harvester, the amplitude and frequency of the flutter limit cycle are also investigated. The limit cycle behavior is simulated in the time domain with a semi-empirical nonlinear model that accounts for the effects of the dynamic stall over the flap at large deflections. Wind tunnel test results are presented to determine the empirical aerodynamic model coefficients and to characterize the power output and flutter frequency of the energy harvester as functions of incident wind speed. DA - 2011/// PY - 2011/// DO - 10.1115/1.4002788 VL - 133 ER - TY - JOUR TI - Aeroelastic flutter energy harvester design: the sensitivity of the driving instability to system parameters AU - Bryant, Matthew AU - Wolff, Eric AU - Garcia, Ephrahim T2 - SMART MATERIALS AND STRUCTURES AB - This study examines the design parameters affecting the stability characteristics of a novel fluid flow energy harvesting device powered by aeroelastic flutter vibrations. The energy harvester makes use of a modal convergence flutter instability to generate limit cycle bending oscillations of a cantilevered piezoelectric beam with a small flap connected to its free end by a revolute joint. The critical flow speed at which destabilizing aerodynamic effects cause self-excited vibrations of the structure to emerge is essential to the design of the energy harvester because it sets the lower bound on the operating wind speed and frequency range of the system. A linearized analytic model of the device that accounts for the three-way coupling between the structural, unsteady aerodynamic, and electrical aspects of the system is used to examine tuning several design parameters while the size of the system is held fixed. The effects on the aeroelastic system dynamics and relative sensitivity of the flutter stability boundary are presented and discussed. A wind tunnel experiment is performed to validate the model predictions for the most significant system parameters. DA - 2011/12// PY - 2011/12// DO - 10.1088/0964-1726/20/12/125017 VL - 20 IS - 12 SP - SN - 1361-665X ER - TY - CONF TI - Comparison of Lithium-ion battery cathode materials and the internal stress development AU - Wang, Yi-Xu AU - Huang, Hsiao-Ying Shadow AB - The need for development and deployment of reliable and efficient energy storage devices, such as lithium-ion rechargeable batteries, is becoming increasingly important due to the scarcity of petroleum. Lithium-ion batteries operate via an electrochemical process in which lithium ions are shuttled between cathode and anode while electrons flowing through an external wire to form an electrical circuit. The study showed that the development of lithium-iron-phosphate (LiFePO4) batteries promises an alternative to conventional lithium-ion batteries, with their potential for high energy capacity and power density, improved safety, and reduced cost. However, current prototype LiFePO4 batteries have been reported to lose capacity over ∼3000 charge/discharge cycles or degrade rapidly under high discharging rate. In this study, we report that the mechanical and structural failures are attributed to dislocations formations. Analytical models and crystal visualizations provide details to further understand the stress development due to lithium movements during charging or discharging. This study contributes to the fundamental understanding of the mechanisms of capacity loss in lithium-ion battery materials and helps the design of better rechargeable batteries, and thus leads to economic and environmental benefits. C2 - 2011/// C3 - Proceedings of the ASME International Mechanical Engineering Congress and Exposition CY - Denver, CO DA - 2011/// DO - 10.1115/IMECE2011-65663 SP - 1685-1694 ER - TY - JOUR TI - AN EXPERIMENTAL STUDY ON GASOLINE DIRECT-INJECTION SPRAY AND ATOMIZATION CHARACTERISTICS OF ALCOHOL FUELS AND ISOOCTANE AU - Zhang, Ji AU - Yao, Shanshan AU - Patel, Himesh AU - Fang, Tiegang T2 - ATOMIZATION AND SPRAYS AB - Alcohol fuels such as butanol and ethanol are considered as the alternative or blending fuels to conventional gasoline for fewer emissions and their renewable capability. In this paper the spray structure development and atomization for butanol, ethanol, and isooctane were investigated using a swirl-type inwardly opening gasoline direct-injection (GDI) injector. Two pressures of 7.0 and 10.2 MPa were used for each fuel, and the fuel was injected into a room condition. Transient spray images were taken by using a high-speed camera for visualization and cone angle analysis. Sauter mean diameter (SMD), DV(50), DV(90), and particle size distribution (PSD) were measured using a laser diffraction technique. Results of the transient images clearly show the sac spray at the initial phase (phase 1) and the main spray structure at the developed phase (phase 2). The cone angles at the developed phase for butanol and ethanol are consistently stable, while isooctane presents relatively large fluctuations. The largest cone angle value is observed for ethanol at both injection pressures, while butanol shows the smallest. Higher injection pressure leads to a smaller cone angle for each fuel, among which isooctane shows the largest decrease. In phase 1, isooctane shows a bouncing trend in terms of DV(90), as opposed to butanol and ethanol which show a gradual decrease. In phase 2, all three fuels show consistently smaller droplet size compared to phase 1, suggesting good atomization. A higher injection pressure helps isooctane to reduce the droplet size, meanwhile enabling butanol and ethanol to produce a more uniform PSD, but it does not necessarily induce the droplet size decrease for butanol and ethanol at the current experimental setting. DA - 2011/// PY - 2011/// DO - 10.1615/atomizspr.2011003624 VL - 21 IS - 5 SP - 363-374 SN - 1936-2684 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84555203802&partnerID=MN8TOARS KW - butanol KW - ethanol KW - isooctane KW - GDI KW - SMD KW - particle size distribution (PSD) ER - TY - JOUR TI - Scaling effect of flexoelectric (Ba,Sr)TiO3 microcantilevers AU - Huang, Wenbin AU - Kim, Kyungrim AU - Zhang, Shujun AU - Yuan, Fuh-Gwo AU - Jiang, Xiaoning T2 - PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS AB - Abstract The flexoelectric microcantilever offers an alternative approach for the development of micro/nano‐sensors. The transverse flexoelectric coefficients µ 12 of barium strontium titanate microcantilevers were measured at room temperature, and found to keep the same value of 8.5 µC/m for microcantilevers with thickness ranging from 30 µm to 1.4 mm. The calculated effective piezoelectric coefficient and electrical energy density of flexoelectric cantilevers are superior to those of their piezoelectric counterparts, suggesting that the flexoelectricity‐induced polarization can be significantly increased as structures are scaled down due to the scaling effect of strain gradient, holding promise for flexoelectric micro/nano cantilever sensing applications. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) DA - 2011/9// PY - 2011/9// DO - 10.1002/pssr.201105326 VL - 5 IS - 9 SP - 350-352 SN - 1862-6254 KW - flexoelectricity KW - microcantilevers KW - (Ba,Sr)TiO3 KW - sensors ER - TY - JOUR TI - Real-Time Friction Error Compensation in Tube Hydroforming Process Control AU - Ngaile, Gracious AU - Yang, Chen AU - Kilonzo, Obadiah T2 - JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME AB - Tube hydroforming (THF) is a metal-forming process that uses a pressurized fluid in place of a hard tool to plastically deform a given tube into a desired shape. In addition to the internal pressure, the tube material is fed axially toward the die cavity. One of the challenges in THF is the nonlinear and varying friction conditions at the tube-tool interface, which make it difficult to establish accurate loading paths (pressure versus feed) for THF. A THF process control model that can compensate for the loading path deviation due to frictional errors in tube hydroforming is proposed. In the proposed model, an algorithm and a software platform have been developed such that the sensed forming load from a THF machine is mapped to a database containing a set of loading paths that correspond to different friction conditions for a specific part. A real-time friction error compensation is then carried out by readjusting the loading path as the THF process progresses. This scheme reduces part failures that would normally occur due to variability in friction conditions. The implementation and experimental verification of the proposed model is discussed. DA - 2011/12// PY - 2011/12// DO - 10.1115/1.4005430 VL - 133 IS - 6 SP - SN - 1087-1357 ER - TY - JOUR TI - Preform Design for Tube Hydroforming Based on Wrinkle Formation AU - Yang, Chen AU - Ngaile, Gracious T2 - JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME AB - A two-stage preforming process based on wrinkle formation is developed for the tube hydroforming process to accumulate material in the forming zone, thus reducing the thinning rate and improving the formability. In preforming stage one, the wrinkle onset is triggered with limited axial compression. In preforming stage two, the wrinkle grows stably and uniformly to a certain height. Then, the preformed wrinkles are flattened to conform to the die shape in the final tube hydroforming process. An analytical model based on bifurcation analysis and postbuckling analysis of the elastic-plastic circular cylinder under axial compression and internal pressure is used to study the wrinkle evolution characteristics in tube hydroforming. The analytical results offer valuable guidance to the process design of the two-stage preforming process. To validate this methodology, preform die sets for two axisymmetric parts were designed and tube hydroforming experiments were carried out on SS 304 tubing. Through this methodology, an expansion rate of 71% was achieved. DA - 2011/12// PY - 2011/12// DO - 10.1115/1.4005118 VL - 133 IS - 6 SP - SN - 1528-8935 KW - tube hydroforming KW - preform design KW - tube bulging KW - wrinkle onset KW - wrinkle evolution KW - FEA ER - TY - JOUR TI - Numerical assessment of hydrodynamic characteristics in chlorine contact tank AU - Amini, R. AU - Taghipour, R. AU - Mirgolbabaei, H. T2 - International Journal for Numerical Methods in Fluids DA - 2011/// PY - 2011/// VL - 67 IS - 7 SP - 885-898 ER - TY - JOUR TI - Analysis of Multi-Layer Immiscible Fluid Flow in a Microchannel AU - Li, Jie AU - Sheeran, Paul S. AU - Kleinstreuer, Clement T2 - JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME AB - The development of microfluidics platforms in recent years has led to an increase in the number of applications involving the flow of multiple immiscible layers of viscous electrolyte fluids. In this study, numerical results as well as analytic equations for velocity and shear stress profiles were derived for N layers with known viscosities, assuming steady laminar flow in a microchannel driven by pressure and/or electro-static (Coulomb) forces. Numerical simulation results, using a commercial software package, match analytical results for fully-developed flow. Entrance flow effects with centered fluid-layer shrinking were studied as well. Specifically, cases with larger viscosities in the inner layers show a very good agreement with experimental correlations for the dimensionless entrance length as a function of inlet Reynolds number. However, significant deviations may occur for multilayer flows with smaller viscosities in the inner layers. A correlation was deduced for the two-layer electroosmotic flow and the pressure driven flow, both being more complex when compared with single-layer flows. The impact of using power-law fluids on resulting velocity profiles has also been explored and compared to Newtonian fluid flows. The present model readily allows for an exploration of the impact of design choices on velocity profiles, shear stress, and channel distribution in multilayer microchannel flows as a function of layered viscosity distribution and type of driving force. DA - 2011/11// PY - 2011/11// DO - 10.1115/1.4005134 VL - 133 IS - 11 SP - SN - 1528-901X KW - immiscible fluids KW - multilayer viscosities KW - non-newtonian fluids KW - pressure-driven flow KW - electroosmotic flow KW - microchannel entrance effects ER - TY - JOUR TI - A mechanics of materials model for the creping process AU - Ramasubramanian, M. K. AU - Sun, Z. H. AU - Chen, G. T2 - Journal of Manufacturing Science and Engineering DA - 2011/// PY - 2011/// VL - 133 IS - 5 ER - TY - JOUR TI - Nanofluid bio-thermal convection: simultaneous effects of gyrotactic and oxytactic micro-organisms AU - Kuznetsov, A. V. T2 - FLUID DYNAMICS RESEARCH AB - This paper investigates the onset of nanofluid bio-thermal convection in a horizontal layer of finite depth for the case when the suspension contains two species of motile micro-organisms exhibiting different taxes, gyrotactic and oxytactic micro-organisms. The obtained instability problem is controlled by four agencies, namely by distributions of nanoparticles, gyrotactic and oxytactic micro-organisms and by the vertical temperature variation. The utilization of the linear instability theory makes it possible to decouple the effects of these agencies and obtain an eigenvalue equation that involves four Rayleigh numbers: the nanoparticle Rayleigh number, the bioconvection gyrotactic and oxytactic Rayleigh numbers, and the traditional thermal Rayleigh number. Each Rayleigh number represents the effect of one of the four aforementioned agencies. Previously obtained results are recovered for limiting cases. The effects of different agencies on the boundary of marginal non-oscillatory instability are investigated. DA - 2011/10// PY - 2011/10// DO - 10.1088/0169-5983/43/5/055505 VL - 43 IS - 5 SP - SN - 0169-5983 ER - TY - JOUR TI - Multifunctional ZnO/Nylon 6 nanofiber mats by an electrospinning-electrospraying hybrid process for use in protective applications AU - Vitchuli, Narendiran AU - Shi, Quan AU - Nowak, Joshua AU - Kay, Kathryn AU - Caldwell, Jane M. AU - Breidt, Frederick AU - Bourham, Mohamed AU - McCord, Marian AU - Zhang, Xiangwu T2 - SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS AB - ZnO/Nylon 6 nanofiber mats were prepared by an electrospinning-electrospraying hybrid process in which ZnO nanoparticles were dispersed on the surface of Nylon 6 nanofibers without becoming completely embedded. The prepared ZnO/Nylon 6 nanofiber mats were evaluated for their abilities to kill bacteria or inhibit their growth and to catalytically detoxify chemicals. Results showed that these ZnO/Nylon 6 nanofiber mats had excellent antibacterial efficiency (99.99%) against both the Gram-negative Escherichia coli and Gram-positive Bacillus cereus bacteria. In addition, they exhibited good detoxifying efficiency (95%) against paraoxon, a simulant of highly toxic chemicals. ZnO/Nylon 6 nanofiber mats were also deposited onto nylon/cotton woven fabrics and the nanofiber mats did not significantly affect the moisture vapor transmission rates and air permeability values of the fabrics. Therefore, ZnO/Nylon 6 nanofiber mats prepared by the electrospinning-electrospraying hybrid process are promising material candidates for protective applications. DA - 2011/10// PY - 2011/10// DO - 10.1088/1468-6996/12/5/055004 VL - 12 IS - 5 SP - SN - 1468-6996 KW - electrospinning KW - electrospraying KW - Nylon 6 KW - zinc oxide KW - antibacterial KW - detoxification ER - TY - JOUR TI - Viscous Swirling Flow over a Stretching Cylinder AU - Fang, Tiegang AU - Yao, Shanshan T2 - CHINESE PHYSICS LETTERS AB - We investigate a viscous flow over a cylinder with stretching and torsional motion. There is an exact solution to the Navier—Stokes equations and there exists a unique solution for all the given values of the flow Reynolds number. The results show that velocity decays faster for a higher Reynolds number and the flow penetrates shallower into the ambient fluid. All the velocity profiles decay algebraically to the ambient zero velocity. DA - 2011/11// PY - 2011/11// DO - 10.1088/0256-307x/28/11/114702 VL - 28 IS - 11 SP - SN - 0256-307X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-81855177082&partnerID=MN8TOARS ER - TY - JOUR TI - Unsteady Viscous Flow over an Expanding Stretching Cylinder AU - Tie-Gang, Fang AU - Ji, Zhang AU - Yong-Fang, Zhong AU - Hua, Tao T2 - CHINESE PHYSICS LETTERS AB - We study the viscous flow over an expanding stretching cylinder. The solution is exact to the Navier—Stokes equations. The stretching velocity of the cylinder is proportional to the axial distance from the origin and decreases with time. There exists a unique solution for the flow with all the studied values of Reynolds number and the unsteadiness parameter. Reversal flows exist for an expanding stretching cylinder. The velocity decays faster for a larger Reynolds number and a more rapidly expanding cylinder. DA - 2011/12// PY - 2011/12// DO - 10.1088/0256-307x/28/12/124707 VL - 28 IS - 12 SP - SN - 0256-307X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-83455233823&partnerID=MN8TOARS ER - TY - JOUR TI - The effects of combined horizontal and vertical heterogeneity on the onset of convection in a porous medium with horizontal throughflow AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER AB - The effects of hydrodynamic and thermal heterogeneity, for the case of variation in both the horizontal and vertical directions, on the onset of convection in a horizontal layer of a saturated porous medium uniformly heated from below, with horizontal throughflow, are studied analytically for the case of weak heterogeneity. It is found that the horizontal throughflow has no effect on the stability of the longitudinal modes but it does affect the stability of the transverse modes. When the permeability decreases in the direction of the throughflow the transverse modes are stabilized (and so the longitudinal ones are favored). When the permeability increases in the direction of the throughflow a small amount of throughflow may destabilize the transverse modes and so destabilize the layer as a whole. DA - 2011/12// PY - 2011/12// DO - 10.1016/j.ijheatmasstransfer.2011.07.019 VL - 54 IS - 25-26 SP - 5595-5601 SN - 1879-2189 KW - Porous medium KW - Onset of convection KW - Heterogeneity KW - Throughflow ER - TY - JOUR TI - The Effect of Vertical Throughflow on the Onset of Convection in a Porous Medium in a Rectangular Box AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - TRANSPORT IN POROUS MEDIA DA - 2011/12// PY - 2011/12// DO - 10.1007/s11242-011-9828-4 VL - 90 IS - 3 SP - 993-1000 SN - 1573-1634 KW - Throughflow KW - Thermal instability KW - Rectangular box ER - TY - JOUR TI - Onset of Convection in a Porous Medium with Strong Vertical Throughflow AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - TRANSPORT IN POROUS MEDIA DA - 2011/12// PY - 2011/12// DO - 10.1007/s11242-011-9821-y VL - 90 IS - 3 SP - 883-888 SN - 1573-1634 KW - Instability KW - Convection KW - Vertical throughflow KW - Asymptotic analysis ER - TY - JOUR TI - Modeling of grain boundary transmission, emission, absorption and overall crystalline behavior in Sigma 1, Sigma 3, and Sigma 17b bicrystals AU - Shi, Jibin AU - Zikry, Mohammed A. T2 - JOURNAL OF MATERIALS RESEARCH DA - 2011/7// PY - 2011/7// DO - 10.1557/jmr.2011.192 VL - 26 IS - 14 SP - 1676-1687 SN - 0884-2914 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-81455159237&partnerID=MN8TOARS ER - TY - JOUR TI - Generalized nonlinear H-infinity synthesis condition with its numerically efficient solution AU - Zheng, Qian AU - Wu, Fen T2 - INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL AB - Abstract In this paper, we will first derive a general synthesis condition for the output‐feedback ℋ︁ ∞ control of smooth nonlinear systems. Computationally efficient ℋ︁ ∞ control design procedure for a subclass of smooth nonlinear systems with polynomial vector field is then proposed by converting the resulting Hamilton‐Jacobi‐Isaacs inequalities from rational forms to their equivalent polynomial forms. Using quadratic Lyapunov functions, both the state‐feedback and output‐feedback problems will be reformulated as semi‐definite optimization conditions and locally tractable solutions can be obtained through sum‐of‐squares (SOS) programming. The proposed nonlinear ℋ︁ ∞ design approach achieves significant relaxations on the plant structure compared with existing results in the literature. Moreover, the SOS‐based solution algorithm provides an effective computational scheme to break the bottleneck in solving nonlinear ℋ︁ ∞ and optimal control problems. The proposed nonlinear ℋ︁ ∞ control approach has been applied to several examples to demonstrate its advantages over existing nonlinear control techniques and its usefulness to engineering problems. Copyright © 2010 John Wiley & Sons, Ltd. DA - 2011/12// PY - 2011/12// DO - 10.1002/rnc.1682 VL - 21 IS - 18 SP - 2079-2100 SN - 1099-1239 KW - nonlinear H-infinity control KW - output feedback KW - polynomial nonlinear systems KW - SOS programming ER - TY - JOUR TI - Effect of pharmaceutical agent degradation on axonal transport drug delivery: An analytical solution for a transient situation AU - Kuznetsov, A. V. T2 - INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER AB - This paper is motivated by recent experimental research that demonstrated pharmacological efficiency of axonal transport drug delivery. The purpose is to develop a model of this process and to study how the rate of destruction of pharmaceutical agent complexes (PACs) affects their transport in the axon. The model includes two populations of PACs: PACs in the state when they are driven retrogradely (from the axon terminal toward the neuron soma) by dynein motors and PACs residing in the accumulated state (but can still be re-released to the dynein-driven state). The coupling between the kinetic states is accounted for by first-order reactions. Utilizing Laplace transform, analytical solutions for concentrations of these two populations of PACs are obtained. The effect of PAC destruction is investigated for different values of other parameters. It is shown that the shapes of the waves describing the PAC concentrations can be significantly affected by transport parameters. DA - 2011/12// PY - 2011/12// DO - 10.1016/j.icheatmasstransfer.2011.08.018 VL - 38 IS - 10 SP - 1317-1321 SN - 0735-1933 KW - Targeted drug delivery KW - Neurons KW - Molecular motors KW - Axonal transport KW - Analytical solution ER - TY - JOUR TI - Dynamic failure behavior of nanocrystalline Cu at atomic scales AU - Dongare, A.M. AU - Rajendran, A.M. AU - Lamattina, B. AU - Zikry, M.A. AU - Brenner, D.W. T2 - Computers, Materials and Continua DA - 2011/// PY - 2011/// VL - 24 IS - 1 SP - 43-60 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80155206327&partnerID=MN8TOARS ER - TY - JOUR TI - Continuum modeling of large-strain deformation modes in gold nanowires AU - Rezvanian, Omid AU - Zikry, Mohammed A. T2 - JOURNAL OF MATERIALS RESEARCH DA - 2011/9// PY - 2011/9// DO - 10.1557/jmr.2011.148 VL - 26 IS - 17 SP - 2286-2292 SN - 2044-5326 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84864699682&partnerID=MN8TOARS ER - TY - JOUR TI - An analytical solution describing retrograde viral transport in an axon AU - Kuznetsov, A. V. T2 - INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER AB - An analytical solution representing a wave of viral concentration as it propagates from the axon synapse toward the neuron soma is obtained. The obtained solution is based on a model of molecular motor-assisted retrograde transport of a neurotropic virus in an axon of a peripheral nervous system. It is established that the velocity of the viral concentration wave is almost independent of the rate of viral destruction in the axon, but depends on viral diffusivity, especially right after viral uptake at the synapse, when viral concentration gradient is large. As time progresses, the velocity of the viral concentration wave approaches that of a dynein motor, which indicates that for a large time viral transport in an axon is almost exclusively motor-driven. DA - 2011/12// PY - 2011/12// DO - 10.1016/j.icheatmasstransfer.2011.08.016 VL - 38 IS - 10 SP - 1313-1316 SN - 1879-0178 KW - Neurotropic virus KW - Retrograde axonal transport KW - Molecular motors KW - Virus trafficking ER - TY - JOUR TI - A model for determining initial dislocation-densities associated with martensitic transformations AU - Hatem, T. M. AU - Zikry, M. A. T2 - MATERIALS SCIENCE AND TECHNOLOGY AB - A three-dimensional multiple-slip dislocation-density-based crystal plasticity formulation, and specialised finite element formulations were used to determine the initial dislocation-densities associated with martensitic transformations in steel alloys. The analysis is based on modelling the shear part from the phenomenological theory of martensitic transformation to obtain both the transformation mobile and immobile dislocation-densities. The model was validated with experiments related to the transformation of lath martensite in high-strength low-alloying steels. DA - 2011/10// PY - 2011/10// DO - 10.1179/1743284711y.0000000079 VL - 27 IS - 10 SP - 1570-1573 SN - 0267-0836 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80054886787&partnerID=MN8TOARS KW - Martensitic phase transformation KW - Martensitic steel KW - Dislocation-densities KW - Finite element analysis ER - TY - JOUR TI - The Effects of Combined Horizontal and Vertical Heterogeneity on the Onset of Convection in a Porous Medium with Vertical Throughflow AU - Kuznetsov, A. V. AU - Nield, D. A. T2 - TRANSPORT IN POROUS MEDIA DA - 2011/11// PY - 2011/11// DO - 10.1007/s11242-011-9795-9 VL - 90 IS - 2 SP - 465-478 SN - 1573-1634 KW - Permeability heterogeneity KW - Throughflow KW - Thermal instability KW - Horizontal layer ER - TY - JOUR TI - Producing superior composites by winding carbon nanotubes onto a mandrel under a poly(vinyl alcohol) spray AU - Liu, Wei AU - Zhang, Xiaohua AU - Xu, Geng AU - Bradford, Philip D. AU - Wang, Xin AU - Zhao, Haibo AU - Zhang, Yingying AU - Jia, Quanxi AU - Yuan, Fuh-Gwo AU - Li, Qingwen AU - Qiu, Yiping AU - Zhu, Yuntian T2 - CARBON AB - A simple method for processing high-performance carbon nanotube (CNT)/poly(vinyl alcohol) (PVA) composites by coupling the spraying of a PVA solution with the continuous winding of CNT sheets from an array onto a rotating mandrel is reported. This method allows the CNT composites to have a high CNT volume fraction, while having a high degree of alignment, long CNTs, and good integration with the matrix, which are extremely difficult to realize simultaneously by other processes. As a result, the composites have a toughness, strength and electrical conductivity up to 100 J/g, 1.8 GPa and 780 S/cm, respectively. Such a one-step synthesis process is promising for industrial productions and also works for different types of polymers. DA - 2011/11// PY - 2011/11// DO - 10.1016/j.carbon.2011.06.089 VL - 49 IS - 14 SP - 4786-4791 SN - 1873-3891 ER - TY - JOUR TI - Modelling active transport in Drosophila unipolar motor neurons AU - Kuznetsov, A. V. T2 - COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING AB - This paper develops a model for simulating organelle transport in Drosophila unipolar motor neurons. The paper is motivated by a recent experimental investigation by Stone et al. (Microtubules have opposite orientation in axons and dendrites of Drosophila neurons. Mol Biol Cell.19:4122-4129) who proposed a map of microtubule (MT) orientation in Drosophila neurons, and explained why dynein mutations selectively impede dendritic growth without having much effect on axonal growth. Two different approaches to modelling the effect of dynein mutations are utilised: one through assuming a reduced average velocity of a dynein mutant motor and the other through assuming its decreased processivity (an increased detachment rate from MTs). Modified Smith-Simmons equations are used for developing a continuum model of the process. Distributions of organelle concentrations as well as distributions of diffusion, motor-driven and total organelle fluxes are simulated. DA - 2011/// PY - 2011/// DO - 10.1080/10255842.2010.515983 VL - 14 IS - 12 SP - 1117-1131 SN - 1025-5842 KW - mathematical modelling KW - molecular motors KW - microtubules KW - fast axonal transport KW - neurons KW - axons and dendrites ER - TY - JOUR TI - Investigation of Jet-Flame Blowout with Lean-Limit Considerations AU - Moore, Nancy J. AU - Kribs, James AU - Lyons, Kevin M. T2 - FLOW TURBULENCE AND COMBUSTION DA - 2011/12// PY - 2011/12// DO - 10.1007/s10494-011-9334-3 VL - 87 IS - 4 SP - 525-536 SN - 1386-6184 KW - Turbulent reacting flows KW - Fuels dilution KW - Lean limit KW - Flame ER - TY - JOUR TI - Dynamic modeling and simulation of a real world billiard AU - Hartl, Alexandre E. AU - Miller, Bruce N. AU - Mazzoleni, Andre P. T2 - PHYSICS LETTERS A AB - Gravitational billiards provide an experimentally accessible arena for testing formulations of nonlinear dynamics. We present a mathematical model that captures the essential dynamics required for describing the motion of a realistic billiard for arbitrary boundaries. Simulations of the model are applied to parabolic, wedge and hyperbolic billiards that are driven sinusoidally. Direct comparisons are made between the modelʼs predictions and previously published experimental data. It is shown that the data can be successfully modeled with a simple set of parameters without an assumption of exotic energy dependence. DA - 2011/10/3/ PY - 2011/10/3/ DO - 10.1016/j.physleta.2011.08.038 VL - 375 IS - 42 SP - 3682-3686 SN - 1873-2429 KW - Billiard KW - Gravity KW - Chaos KW - Dissipation KW - Rotation KW - Simulation ER - TY - CONF TI - Design and hardware implementation of gen-1 silicon based solid state transformer AU - Wang, G. Y. AU - Baek, S. AU - Elliott, J. AU - Kadavelugu, A. AU - Wang, F. AU - She, X. AU - Dutta, S. AU - Liu, Y. AU - Zhao, T. F. AU - Yao, W. X. AU - Gould, R. AU - Bhattacharya, S. AU - Huang, A. Q. AB - This paper presents the design and hardware implementation and testing of 20kVA Gen-1 silicon based solid state transformer (SST), the high input voltage and high voltage isolation requirement are two major concerns for the SST design. So a 6.5kV 25A dual IGBT module has been customized packaged specially for this high voltage low current application, and an optically coupled high voltage sensor and IGBT gate driver has been designed in order to fulfill the high voltage isolation requirement. This paper also discusses the auxiliary power supply structure and thermal management for the SST power stage. C2 - 2011/// C3 - Annual ieee conference on applied power electronics conference and DA - 2011/// DO - 10.1109/apec.2011.5744766 SP - 1344-1349 ER - TY - JOUR TI - Compressible-Flow Simulations Using a New Large-Eddy Simulation/Reynolds-Averaged Navier-Stokes Model AU - Gieseking, Daniel A. AU - Choi, Jung-Il AU - Edwards, Jack R. AU - Hassan, Hassan A. T2 - AIAA JOURNAL AB - A new hybrid large-eddy simulation/Reynolds-averaged Navier–Stokes simulation (LES/RANS) method is presented in this work. In this approach, the resolved turbulence kinetic energy, ensemble-averaged modeled turbulence kinetic energy and turbulence frequency, and time-resolved turbulence frequency are used to form an estimate of an outer-layer turbulence length scale that is nearly Reynolds-number-independent. The ratio of this outer-layer scale with an inner-layer length scale (proportional to the wall distance) is used to construct a blending function that facilitates the shift between an unsteady RANS formulation near solid surfaces and a LES formulation away from the wall. The new model is tested through simulations of compressible flat-plate boundary layers over a widerangeofReynoldsnumbersandMach2.86 flowoverasmoothcompressionramp.Theresultsshowthatthenew modelpredicts mean andsecond-moment statistics that arein goodagreement withexperiment andare comparable with those obtained using an earlier model (Edwards, J. R., Choi, J-I., and Boles, J. A., “Hybrid Large-Eddy/ Reynolds-Averaged Navier–Stokes Simulation of a Mach-5 Compression Corner Interaction,” AIAA Journal, Vol. 464, 2008, pp. 977–991.) which required a case-by-case calibration of a model constant. DA - 2011/10// PY - 2011/10// DO - 10.2514/1.j051001 VL - 49 IS - 10 SP - 2194-2209 SN - 1533-385X ER - TY - JOUR TI - Anisotropic Structure and Charge Transport in Highly Strain-Aligned Regioregular Poly(3-hexylthiophene) AU - O'Connor, Brendan AU - Kline, R. Joseph AU - Conrad, Brad R. AU - Richter, Lee J. AU - Gundlach, David AU - Toney, Michael F. AU - DeLongchamp, Dean M. T2 - ADVANCED FUNCTIONAL MATERIALS AB - Abstract A novel method of strain‐aligning polymer films is introduced and applied to regioregular poly(3‐hexylthiophene) (P3HT), showing several important features of charge transport. The polymer backbone is shown to align in the direction of applied strain resulting in a large charge‐mobility anisotropy, where the in‐plane mobility increases in the applied strain direction and decreases in the perpendicular direction. In the aligned film, the hole mobility is successfully represented by a two‐dimensional tensor, suggesting that charge transport parallel to the polymer backbone within a P3HT crystal is strongly favored over the other crystallographic directions. Hole mobility parallel to the backbone is shown to be high for a mixture of plane‐on and edge‐on packing configurations, as the strain alignment is found to induce a significant face‐on orientation of the originally highly edge‐on oriented crystalline regions of the film. This alignment approach can achieve an optical dichroic ratio of 4.8 and a charge‐mobility anisotropy of 9, providing a simple and effective method to investigate charge‐transport mechanisms in polymer semiconductors. DA - 2011/10/7/ PY - 2011/10/7/ DO - 10.1002/adfm.201100904 VL - 21 IS - 19 SP - 3697-3705 SN - 1616-3028 ER - TY - JOUR TI - Analytical solution of magnetohydrodynamic sink flow AU - Zhang, Ji AU - Fang, Tie-gang AU - Zhong, Yong-fang T2 - APPLIED MATHEMATICS AND MECHANICS-ENGLISH EDITION DA - 2011/10// PY - 2011/10// DO - 10.1007/s10483-011-1495-9 VL - 32 IS - 10 SP - 1221-1230 SN - 0253-4827 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80855139343&partnerID=MN8TOARS KW - similarity solution KW - Falkner-Skan equation KW - stretching surface KW - magnetohydrodynamic (MHD) KW - analytical solution KW - sink flow ER - TY - JOUR TI - A fracture criterion for finitely deforming crystalline solids-The dynamic fracture of single crystals AU - Elkhodary, K. I. AU - Zikry, M. A. T2 - JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS AB - The major objective of this work has been to develop, within a continuum framework, a microstructurally-based computational theory to investigate dynamic failure in metals. To model the nucleation and propagation of failure surfaces at the microstructural scale, under large deformations and dynamic loading conditions, general finite-deformation theory, as relating to the decomposition of the deformation gradient, was tailored to monitor displacement incompatibilities and fracture in crystalline solids subjected to large deformations. Based on this proposed decomposition, a general fracture criterion for finitely deforming crystals, using the integral law of incompatibility, was developed. The analyses indicate that this newly proposed fracture formulation and criterion can be validated with experimental results, and can be used to accurately predict brittle and ductile failure modes for the large deformation of single crystals. As part of the newly proposed decomposition of the deformation gradient, sub-problems can also be solved for lattice distortions, such as twinning and geometrically necessary dislocation (GND) densities. Accordingly, the interactions of GND densities with cracks were investigated for single crystals. GND densities were shown to form as loops for stationary crack tips, but no loops formed for propagating cracks. DA - 2011/10// PY - 2011/10// DO - 10.1016/j.jmps.2011.07.004 VL - 59 IS - 10 SP - 2007-2022 SN - 0022-5096 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80052335624&partnerID=MN8TOARS KW - Dynamic fracture KW - Crack propagation and arrest KW - Crystal plasticity KW - Finite strain KW - Finite elements ER - TY - CONF TI - A Scalable microfluidic device for the mass production of microencapsulated islets AU - Tendulkar, S. AU - McQuilling, J. P. AU - Childers, C. AU - Pareta, R. AU - Opara, E. C. AU - Ramasubramanian, M. K. C2 - 2011/// C3 - Transplantation Proceedings DA - 2011/// VL - 43 SP - 3184-3187 M1 - 9 ER - TY - JOUR TI - Transverse Heterogeneity Effects in the Dissipation-Induced Instability of a Horizontal Porous Layer AU - Barletta, A. AU - Celli, M. AU - Kuznetsov, A. V. T2 - JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME AB - The linear stability of a parallel flow in a heterogeneous porous channel is analyzed by means of the Darcy law and the Oberbeck–Boussinesq approximation. The basic velocity and temperature distributions are influenced by the effect of the viscous dissipation, as well as, by the boundary conditions. A horizontal porous layer bounded by impermeable and infinitely wide walls is considered. The lower boundary is assumed to be thermally insulated, while the upper boundary is assumed to be isothermal. A transverse heterogeneity for the permeability and for the thermal conductivity is taken into account. The main task of this work is to investigate the role of this heterogeneity in changing the threshold for the onset of instability. A linear stability analysis by means of the normal modes method is performed. The onset of instability against oblique rolls is studied. The eigenvalue problem is solved numerically. DA - 2011/12// PY - 2011/12// DO - 10.1115/1.4004371 VL - 133 IS - 12 SP - SN - 0022-1481 KW - porous medium KW - heterogeneity KW - linear stability KW - convection KW - viscous dissipation ER - TY - JOUR TI - The multi-dimensional limiters for solving hyperbolic conservation laws on unstructured grids AU - Li, Wanai AU - Ren, Yu-Xin AU - Lei, Guodong AU - Luo, Hong T2 - JOURNAL OF COMPUTATIONAL PHYSICS AB - Novel limiters based on the weighted average procedure are developed for finite volume methods solving multi-dimensional hyperbolic conservation laws on unstructured grids. The development of these limiters is inspired by the biased averaging procedure of Choi and Liu [10]. The remarkable features of the present limiters are the new biased functions and the weighted average procedure, which enable the present limiter to capture strong shock waves and achieve excellent convergence for steady state computations. The mechanism of the developed limiters for eliminating spurious oscillations in the vicinity of discontinuities is revealed by studying the asymptotic behavior of the limiters. Numerical experiments for a variety of test cases are presented to demonstrate the superior performance of the proposed limiters. DA - 2011/9/1/ PY - 2011/9/1/ DO - 10.1016/j.jcp.2011.06.018 VL - 230 IS - 21 SP - 7775-7795 SN - 1090-2716 KW - Weighted biased averaging procedure KW - Shock capturing KW - Unstructured grids ER - TY - JOUR TI - Static Friction between Silicon Nanowires and Elastomeric Substrates AU - Qin, Qingquan AU - Zhu, Yong T2 - ACS NANO AB - This paper reports the first direct measurements of static friction force and interfacial shear strength between silicon (Si) nanowires (NWs) and poly(dimethylsiloxane) (PDMS). A micromanipulator is used to manipulate and deform the NWs under a high-magnification optical microscope in real time. The static friction force is measured based on “the most-bent state” of the NWs. The static friction and interface shear strength are found to depend on the ultraviolet/ozone (UVO) treatment of PDMS. The shear strength starts at 0.30 MPa without UVO treatment, increases rapidly up to 10.57 MPa at 60 min of treatment and decreases for longer treatment. Water contact angle measurements suggest that the UVO-induced hydrophobic-to-hydrophilic conversion of PDMS surface is responsible for the increase in the static friction, while the hydrophobic recovery effect contributes to the decrease. The static friction between NWs and PDMS is of critical relevance to many device applications of NWs including NW-based flexible/stretchable electronics, NW assembly and nanocomposites (e.g., supercapacitors). Our results will enable quantitative interface design and control for such applications. DA - 2011/9// PY - 2011/9// DO - 10.1021/nn202343w VL - 5 IS - 9 SP - 7404-7410 SN - 1936-086X KW - nanowire KW - PDMS KW - static friction KW - interfacial shear strength KW - adhesion KW - UVO treatment ER - TY - JOUR TI - Multi-objective control optimization for semi-active vehicle suspensions AU - Crews, John H. AU - Mattson, Michael G. AU - Buckner, Gregory D. T2 - JOURNAL OF SOUND AND VIBRATION AB - In this paper we demonstrate a method for determining the optimality of control algorithms based on multiple performance objectives. While the approach is applicable to a broad range of dynamic systems, this paper focuses on the control of semi-active vehicle suspensions. The two performance objectives considered are ride quality, as measured by absorbed power, and thermal performance, as measured by power dissipated in the suspension damper. A multi-objective genetic algorithm (MOGA) is used to establish the limits of controller performance. To facilitate convergence, the MOGA is initialized with popular algorithms such as skyhook control, feedback linearization, and sliding mode control. The MOGA creates a Pareto frontier of solutions, providing a benchmark for assessing the performance of other controllers in terms of both objectives. Furthermore, the MOGA provides insight into the remaining achievable gains in performance. DA - 2011/11/7/ PY - 2011/11/7/ DO - 10.1016/j.jsv.2011.05.036 VL - 330 IS - 23 SP - 5502-5516 SN - 1095-8568 ER - TY - JOUR TI - Mechanical and electrical property improvement in CNT/Nylon composites through drawing and stretching AU - Wang, Xin AU - Bradford, Philip D. AU - Liu, Wei AU - Zhao, Haibo AU - Inoue, Yoku AU - Maria, Jon-Paul AU - Li, Qingwen AU - Yuan, Fuh-Gwo AU - Zhu, Yuntian T2 - COMPOSITES SCIENCE AND TECHNOLOGY AB - The excellent mechanical properties of carbon nanotubes (CNTs) make them the ideal reinforcements for high performance composites. The misalignment and waviness of CNTs within composites are two major issues that limit the reinforcing efficiency. We report an effective method to increase the strength and stiffness of high volume fraction, aligned CNT composites by reducing CNT waviness using a drawing and stretching approach. Stretching the composites after fabrication improved the ultimate strength by 50%, 150%, and 190% corresponding to stretch ratios of 2%, 4% and 7%, respectively. Improvement of the electrical conductivities exhibited a similar trend. These results demonstrate the importance of straightening and aligning CNTs in improving the composite strength and electrical conductivity. DA - 2011/9/30/ PY - 2011/9/30/ DO - 10.1016/j.compscitech.2011.07.023 VL - 71 IS - 14 SP - 1677-1683 SN - 1879-1050 KW - Carbon nanotubes KW - Nanocomposites KW - Polymer-matrix composites (PMCs) KW - Mechanical properties KW - Electrical properties ER - TY - JOUR TI - Intrinsic Room-Temperature Ferromagnetic Properties of Ni-Doped ZnO Thin Films AU - Jin, C. AU - Aggarwal, R. AU - Wei, W. AU - Nori, S. AU - Kumar, D. AU - Ponarin, D. AU - Smirnov, A. I. AU - Narayan, J. AU - Narayan, R. J. T2 - METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE DA - 2011/11// PY - 2011/11// DO - 10.1007/s11661-010-0479-9 VL - 42A IS - 11 SP - 3250-3254 SN - 1073-5623 ER - TY - JOUR TI - Forced Convection in a Channel Partly Occupied by a Bidisperse Porous Medium: Symmetric Case AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME AB - An analytic solution is obtained for the problem of fully developed forced convection in a channel between parallel plane walls, partly occupied by a bidisperse porous medium (BDPM) and partly by a fluid clear of solid material, the distribution of material being symmetrical with the BDPM forming either the core or the sheath portion of the channel. The case of uniform flux boundaries is considered. For the porous medium, a two-velocity two-temperature model based on Darcy’s law is employed and the Beavers–Joseph interface condition is imposed. In each case, Nusselt number values are obtained in terms of various parameters. DA - 2011/7// PY - 2011/7// DO - 10.1115/1.4003667 VL - 133 IS - 7 SP - SN - 1528-8943 KW - bidisperse porous medium KW - forced convection KW - channel KW - Beavers-Joseph condition ER - TY - JOUR TI - Advances in Plastic Forming of Metals AU - Ngaile, Gracious AU - Kinsey, Brad T2 - JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME DA - 2011/12// PY - 2011/12// DO - 10.1115/1.4005461 VL - 133 IS - 6 SP - SN - 1087-1357 ER - TY - JOUR TI - Site-specific sonoporation of human melanoma cells at the cellular level using high lateral-resolution ultrasonic micro-transducer arrays AU - Thein, Myo AU - Cheng, An AU - Khanna, Payal AU - Zhang, Chunfeng AU - Park, Eun-Joo AU - Ahmed, Daniel AU - Goodrich, Christopher J. AU - Asphahani, Fareid AU - Wu, Fengbing AU - Smith, Nadine B. AU - Dong, Cheng AU - Jiang, Xiaoning AU - Zhang, Miqin AU - Xu, Jian T2 - BIOSENSORS & BIOELECTRONICS AB - We developed a new instrumental method by which human melanoma cells (LU1205) are sonoporated via radiation pressures exerted by highly-confined ultrasonic waves produced by high lateral-resolution ultrasonic micro-transducer arrays (UMTAs). The method enables cellular-level site-specific sonoporation within the cell monolayer due to UMTAs and can be applicable in the delivery of drugs and gene products in cellular assays. In this method, cells are seeded on the biochip that employs UMTAs for high spatial resolution and specificity. UMTAs are driven by 30-MHz sinusoidal signals and the resulting radiation pressures induce sonoporation in the targeted cells. The sonoporation degree and the effective lateral resolution of UMTAs are determined by performing fluorescent microscopy and analysis of carboxylic-acid-derivatized CdSe/ZnS quantum dots passively transported into the cells. Models representing the transducer-generated ultrasound radiation pressure, the ultrasound-inflicted cell membrane wound, and the transmembrane transport through the wound are developed to determine the ultrasound-pressure-dependent wound size and enhanced cellular uptake of nanoparticles. Model-based calculations show that the effective wound size and cellular uptake of nanoparticles increase linearly with increasing ultrasound pressure (i.e., at applied radiation pressures of 0.21, 0.29, and 0.40 MPa, the ultrasound-induced initial effective wound radii are 150, 460, and 650 nm, respectively, and the post-sonoporation intracellular quantum-dot concentrations are 7.8, 22.8, and 29.9 nM, respectively) and the threshold pressure required to induce sonoporation in LU1205 cells is ∼0.12 MPa. DA - 2011/9/15/ PY - 2011/9/15/ DO - 10.1016/j.bios.2011.05.026 VL - 27 IS - 1 SP - 25-33 SN - 0956-5663 KW - Biochip KW - Cell membrane wound KW - Piezoelectric-based transducer KW - Quantum dot, Radiation pressure KW - Transmembrane transport ER - TY - JOUR TI - Flow and heat transfer over a generalized stretching/shrinking wall problem-Exact solutions of the Navier-Stokes equations AU - Fang, Tiegang AU - Yao, Shanshan AU - Pop, Loan T2 - INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS AB - In this paper, we investigate the steady momentum and heat transfer of a viscous fluid flow over a stretching/shrinking sheet. Exact solutions are presented for the Navier–Stokes equations. The new solutions provide a more general formulation including the linearly stretching and shrinking wall problems as well as the asymptotic suction velocity profiles over a moving plate. Interesting non-linear phenomena are observed in the current results including both exponentially decaying solution and algebraically decaying solution, multiple solutions with infinite number of solutions for the flow field, and velocity overshoot. The energy equation ignoring viscous dissipation is solved exactly and the effects of the mass transfer parameter, the Prandtl number, and the wall stretching/shrinking strength on the temperature profiles and wall heat flux are also presented and discussed. The exact solution of this general flow configuration is a rare case for the Navier–Stokes equation. DA - 2011/11// PY - 2011/11// DO - 10.1016/j.ijnonlinmec.2011.04.014 VL - 46 IS - 9 SP - 1116-1127 SN - 1878-5638 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80051548371&partnerID=MN8TOARS KW - Navier-Stokes equation KW - Similarity equation KW - Stretching surface KW - Shrinking sheet KW - Exact solution KW - Analytical solution KW - Heat transfer ER - TY - JOUR TI - Damage Identification After Impact in Sandwich Composites Through Embedded Fiber Bragg Sensors AU - Hackney, D. AU - Peters, K. T2 - JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES AB - Based on the full-spectral response of fiber Bragg grating sensors, embedded at the facesheet-core interface, we identify the progression of failure modes in foam core sandwich composites during multiple, low-velocity impacts. By considering the characteristic shape of the reflected spectrum from the FBG sensor in the post-impact, residual strain state, it is shown that we can classify the extent of damage into one of three states. Unlike the previous FBG peak wavelength measurements; this identification does not require the full strain history to identify the current state of damage in the composite. The disparate material properties between the facesheet and core materials, which create significant challenges for conventional non-destructive evaluation methods, enhance the damage detection through large deformations in the core at the impact location with sharp strain gradients. DA - 2011/8// PY - 2011/8// DO - 10.1177/1045389x11414220 VL - 22 IS - 12 SP - 1305-1316 SN - 1530-8138 KW - sandwich composite KW - fiber Bragg grating sensor KW - low-velocity impact KW - non-destructive evaluation ER - TY - JOUR TI - Control of room-temperature defect-mediated ferromagnetism in VO2 films AU - Yang, Tsung-Han AU - Nori, Sudhakar AU - Mal, Siddhartha AU - Narayan, Jagdish T2 - ACTA MATERIALIA AB - We report interesting ferromagnetic properties and their control in a vanadium-based oxide system driven by stoichiometric defects. Vanadium oxide (VO2) thin films were grown on c-plane sapphire substrates by a pulsed laser deposition technique under different ambient conditions. The ferromagnetism of the epitaxial VO2 films can be switched on and off by altering the cooling ambient parameters. In addition, the saturated magnetic moments and coercivity of the VO2 films were found to be a function of the oxygen partial pressure during the growth process. The room-temperature ferromagnetic properties of VO2 films were correlated with the nature of the microstructure and the growth parameters. The origin of the induced magnetic properties are qualitatively understood to stem from intrinsic structural and stoichiometric defects. DA - 2011/9// PY - 2011/9// DO - 10.1016/j.actamat.2011.06.047 VL - 59 IS - 16 SP - 6362-6368 SN - 1359-6454 KW - Ferromagnetic KW - Vanadium dioxide KW - Semiconductor to Metal Transition (SMT) ER - TY - JOUR TI - Analytical investigation of various regimes of retrograde trafficking of neurotropic viruses in axons AU - Kuznetsov, Andrey V. T2 - CENTRAL EUROPEAN JOURNAL OF PHYSICS AB - Abstract A model of retrograde axonal transport of neurotropic viruses is developed. The model accounts for active viral transport by dynein motors as well as for passive transport by diffusion; the destruction of the virus as it propagates toward the neuron soma is modeled utilizing a first-order decay rate process. The effect of a limited time during which the axonal synapse is exposed to the virus is incorporated. An analytical solution is obtained. The obtained solution makes it possible to identify four different regimes of viral transport in the axon that correspond to the following situations: (1) Small viral diffusivity and small rate of viral destruction; (2) Large viral diffusivity and small rate of viral destruction; (3) Small viral diffusivity and large rate of viral destruction; (4) Large viral diffusivity and large rate of viral destruction. Characteristic features of these regimes are discussed. DA - 2011/10// PY - 2011/10// DO - 10.2478/s11534-011-0051-2 VL - 9 IS - 5 SP - 1372-1378 SN - 1895-1082 KW - neurotropic virus KW - retrograde axonal transport KW - molecular motors KW - virus trafficking ER - TY - JOUR TI - Self-repairing polymer optical fiber sensor AU - Song, Young AU - Peters, Kara T2 - 21ST INTERNATIONAL CONFERENCE ON OPTICAL FIBER SENSORS AB - This article presents experimental demonstrations of a self-repairing strain sensor waveguide created by self-writing in a photopolymerizable resin system. The sensor fabricates between two multi-mode optical fibers via lightwaves in the ultraviolet (UV) wavelength range and operates as a sensor through interrogation of the power transmitted through the waveguide in the infrared (IR) wavelength range. After failure of the sensor occurs due to loading, the waveguide rebridges the gap between the two optical fibers through the UV resin. The response of the original sensor and the selfrepaired sensor to strain are measured and show similar behaviors. DA - 2011/// PY - 2011/// DO - 10.1117/12.885147 VL - 7753 SP - SN - 1996-756X KW - polymer waveguide KW - strain sensor KW - self-writing waveguide ER - TY - JOUR TI - Investigation of the role of diffusivity on spreading, rate, and merging of the bell-shaped waves in slow axonal transport AU - Kuznetsov, A. V. AU - Avramenko, A. A. AU - Blinov, D. G. T2 - INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING AB - This paper investigates the role of diffusivity on spreading, rate, and merging of two waves transporting the same type of cytoskeletal elements (CEs) in slow axonal transport. The two waves (each wave physically represents the total probability density function for the CEs) can be generated by simultaneous microinjections of radiolabeled CEs in two different locations. Alternatively, two waves, one behind another, can be produced by injecting CEs at the same location twice, with a time interval between the injections. Since the waves become wider as they propagate downstream, the two waves eventually merge; this results in the formation of a single wave that moves down the axon. The amplitudes of the waves (before as well as after they merge) decrease as the waves propagate downstream; in addition, the waves spread out during their propagation. The waves spread out faster when diffusivity of free CEs is increased; this agrees with experimental data for the transport of neurofilaments, which are characterized by smaller diffusivity, versus transport of tubulin oligomers, which are characterized by larger diffusivity. The average velocity of CE transport first increases (which is explained by the effect of the initial condition; this effect is somewhat artificial) and then attains an asymptotic value. The case of merging of three waves is also briefly investigated. Copyright © 2010 John Wiley & Sons, Ltd. DA - 2011/7// PY - 2011/7// DO - 10.1002/cnm.1417 VL - 27 IS - 7 SP - 1040-1053 SN - 2040-7939 KW - molecular motors KW - motor-assisted transport KW - neurons KW - axons KW - slow axonal transport KW - stop-and-go hypothesis ER - TY - JOUR TI - General selection criteria of patients for radioembolization of liver tumors an international working group report AU - Coldwell, D. AU - Sangro, B. AU - Wasan, H. AU - Salem, R. AU - Kennedy, A. T2 - American Journal of Clinical Oncology-Cancer Clinical Trials DA - 2011/// PY - 2011/// VL - 34 IS - 3 SP - 337-341 ER - TY - JOUR TI - Full-spectral interrogation of fiber Bragg grating sensors for damage identification AU - Webb, S. AU - Noevere, A. AU - Peters, K. AU - Zikry, M. A. AU - Vella, T. AU - Chadderdon, S. AU - Selfridge, R. AU - Schultz, S. T2 - SMART SENSOR PHENOMENA, TECHNOLOGY, NETWORKS, AND SYSTEMS 2011 AB - In this study we evaluate the measurements of a fiber Bragg grating (FBG) sensor subjected to a non-uniform static strain state and simultaneously exposed to vibration loading. The full spectral response of the sensor is interrogated in reflection at 100 kHz during two loading cases: with and without an added vibration load spectrum. The static tensile loading is increased between each test, in order to increase the magnitude of the non-uniform strain field applied to the FBG sensor. The spectral distortion due to non-uniform strain is observed to change once the sensor is exposed to a non-transient 150 Hz vibration spectrum. With high-speed full spectral interrogation, it is potentially possible to separate this vibration-induced spectral change from spectral distortions due to non-uniform strain. Such spectral distortion contains valuable information on the static damage state of the surrounding host material. DA - 2011/// PY - 2011/// DO - 10.1117/12.881093 VL - 7982 SP - SN - 1996-756X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79956068726&partnerID=MN8TOARS KW - fiber Bragg grating sensors KW - non-uniform strain KW - full spectral interrogation KW - vibration monitoring ER - TY - JOUR TI - Coupling a dynein transport model with a model of anterograde and retrograde transport of intracellular organelles AU - Kuznetsov, A. V. T2 - INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER AB - Abstract A model of fast axonal transport of organelles that accounts for dynein transport in an inactive state toward the axonal synapse is developed. It is assumed that anterograde transport of inactive dynein in an axon is powered by kinesin motors. It is further assumed that the probability of organelle attachment to a dynein motor is directly proportional to the concentration of free dynein motors available at a particular location in the axon. The results predicted by two models (the first one is that which incorporates dynein transport and the second one is the traditional model that does not incorporate dynein transport) are compared. The obtained results suggest that the availability of dynein motors in a particular location in an axon can be a factor limiting fast axonal transport. DA - 2011/8// PY - 2011/8// DO - 10.1016/j.icheatmasstransfer.2011.04.024 VL - 38 IS - 7 SP - 833-837 SN - 0735-1933 KW - Fast axonal transport KW - Molecular motors KW - Anterograde and retrograde transport KW - Modeling KW - Kinesin and dynein motors ER - TY - JOUR TI - Carbon nanotube yarn sensors for structural health monitoring of composites AU - Zhao, Haibo AU - Yuan, Fuh-Gwo T2 - NONDESTRUCTIVE CHARACTERIZATION FOR COMPOSITE MATERIALS, AEROSPACE ENGINEERING, CIVIL INFRASTRUCTURE, AND HOMELAND SECURITY 2011 AB - With increasing application of composite materials, real time monitoring of composite structures becomes vital for maintenance purpose as well as prevention of catastrophic failure. It has been reported that carbon nanotubes (CNTs) have excellent piezoresistive properties, which may enable a new generation of sensors in nano or micro scales. We report here a novel prototype of carbon nanotube yarn sensors with excellent repeatability and stability for in-situ structural health monitoring. The CNT yarn is spun directly from CNT arrays, and its electrical resistance increases linearly with tensile strain, which makes it an ideal strain sensor. Importantly, it shows repeatable piezoresistive behavior under repetitive straining and unloading. Yarn sensors show stable resistances at temperatures ranging from -196° to 110°. Neat yarn sensors are also embedded into resin to monitor the loading conditions of the composites. With multiple yarn sensor elements aligned in the composite, the crack initiation and propagation could be monitored. Yarn sensors could be easily incorporated into composite structures with minimal invasiveness and weight penalty to enable the structure has self-sensing capabilities. DA - 2011/// PY - 2011/// DO - 10.1117/12.880938 VL - 7983 SP - SN - 0277-786X KW - Carbon nanotube KW - yarns KW - sensors KW - nanocomposites KW - structural health monitoring ER - TY - JOUR TI - Analysis of fiber Bragg grating spectral features for in-situ assessment of Composites AU - Peters, Kara T2 - SMART SENSOR PHENOMENA, TECHNOLOGY, NETWORKS, AND SYSTEMS 2011 AB - Embedded sensors provide a high sensitivity to sub-surface damage due to their proximity to the damage features. In particular, fiber Bragg gratings (FBG) are easily embedded into laminates with a minimum of perturbation to the surrounding material microstructure. This paper summarizes some recent advances derived from full-spectral interrogation of FBG sensors for structural health monitoring and damage identification in composites. In particular we will present signals from the FBG reflected spectra that have been correlated to stress concentrations near crack tips, curing conditions during processing of composite laminates and the progression of delamination due to multiple low-velocity impacts in woven composite laminates and foam-core sandwich composites. Recent advances in interrogation systems for these sensors will also be discussed which have permitted dynamic evaluation of these parameters. Finally, spectral distortion can lead to errors in the interpretation of strain values from the peak wavelength measurement when peak waveforms are assumed. This distortion is highly dependent upon the local microstructure surrounding the sensor and therefore cannot be compensated a-priori through a calibration factor. This article demonstrates that full-spectral interrogation can provide sensor specific error compensation for these measurements. These results demonstrate the richness of information that can be obtained from full-spectral interrogation of FBG sensors in a complex, multiple stress component environment. DA - 2011/// PY - 2011/// DO - 10.1117/12.881149 VL - 7982 SP - SN - 1996-756X KW - fiber Bragg sensor KW - full-spectral measurements KW - composites KW - damage identification ER - TY - JOUR TI - An adsorption air conditioning system to integrate with the recent development of emission control for heavy-duty vehicles AU - Zhong, Yongfang AU - Fang, Tiegang AU - Wert, Kevin L. T2 - ENERGY AB - The recent development to control the emissions of large diesel engines has provided opportunities for heat-driven cooling methods in vehicles. An adsorption air conditioning system is therefore proposed in this work for heavy-duty truck application. This system is powered by engine waste heat when the engine of a truck is running. When the engine is off, it can be operated by fuel fired heaters, a newly implemented technology to reduce truck idling. Hence, this system can not only reduce engine emissions but also improve the overall energy efficiency. A lumped parameter model of the system using zeolite-water as its working pair is developed, and the adsorption capacity of zeolite is simulated with the linear driving force model. The dynamic performance of the system and a parametric study on adsorbent mass transfer, operating temperatures and cycle operating periods are presented. Alternative working pairs and the potential to commercialize the system are also discussed. This system may be designed to satisfy the cooling requirement for idle reduction of long-haul trucks. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.energy.2011.04.032 VL - 36 IS - 7 SP - 4125-4135 SN - 1873-6785 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79959378897&partnerID=MN8TOARS KW - Adsorption systems KW - Waste heat recovery KW - Vehicle HAVC KW - Emission control KW - Design and performance prediction KW - Dynamic analysis ER - TY - JOUR TI - A High Temperature Piezoelectric Sensor for Structure Health Monitoring AU - Kim, Kyungrim AU - Jiang, Xiaoning AU - Zhang, Shujun T2 - NONDESTRUCTIVE CHARACTERIZATION FOR COMPOSITE MATERIALS, AEROSPACE ENGINEERING, CIVIL INFRASTRUCTURE, AND HOMELAND SECURITY 2011 AB - High temperature sensors play a significant role in aerospace, automotive and energy industries. In this paper, a shearmode piezoelectric accelerometer using YCa4O(BO3)3 single crystals (YCOB) was designed and fabricated for high temperature sensing applications. The prototype sensor was tested at the temperature ranging from room temperature to 1000°C. The sensitivity of the sensor was found to be 1.9±04 pC/g throughout the tested frequency and temperature range. Moreover, YCOB piezoelectric accelerometers remained stable performance at 1000°C for a dwell time of three hours. DA - 2011/// PY - 2011/// DO - 10.1117/12.880163 VL - 7983 SP - SN - 1996-756X KW - high temperature KW - piezoelectric sensor KW - shear-mode accelerometer KW - YCOB KW - structure health monitoring ER - TY - JOUR TI - YCa4O(BO3)(3) (YCOB) high temperature vibration sensor AU - Kim, Kyungrim AU - Zhang, Shujun AU - Huang, Wenbin AU - Yu, Fapeng AU - Jiang, Xiaoning T2 - JOURNAL OF APPLIED PHYSICS AB - A shear-mode piezoelectric accelerometer using YCa4O(BO3)3 (YCOB) single crystal was designed, fabricated and successfully tested for high temperature vibration sensing applications. The prototyped sensor was tested at temperatures ranging from room temperature to 1000 °C and at frequencies ranging from 80 Hz to 1 kHz. The sensitivity of the sensor was found to be 5.7 pC/g throughout the tested frequency and temperature range. In addition, YCOB piezoelectric accelerometers remained the same sensitivity at 1000 °C for a dwell time of four hours, exhibiting high stability and reliability. DA - 2011/6/15/ PY - 2011/6/15/ DO - 10.1063/1.3598115 VL - 109 IS - 12 SP - SN - 1089-7550 ER - TY - JOUR TI - Tuning the compressive mechanical properties of carbon nanotube foam AU - Bradford, Philip D. AU - Wang, Xin AU - Zhao, Haibo AU - Zhu, Y. T. T2 - CARBON AB - A post-growth chemical vapor deposition (CVD) treatment was used to tune the compressive mechanical properties of carbon nanotube (CNT) arrays. Millimeter tall CNT arrays with low compressive resilience were changed to a foam-like material with high compressive strength and almost complete recovery upon unloading. The foam was tuned to provide a range of compressive properties for various applications. The treated arrays demonstrated compressive strength up to 35× greater than the as-grown CNT array. Unlike polymeric foams, the CNT foam did not decompose after exposure to high temperatures. Investigation of the foam structure revealed that the CVD treatment increased CNT diameter through radial growth, while increasing the CNT surface roughness. The morphological changes help to explain the increase in CNT array compressive strength and the transition from permanent array deformation to foam-like recovery after compressive loading. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.carbon.2011.03.012 VL - 49 IS - 8 SP - 2834-2841 SN - 1873-3891 ER - TY - JOUR TI - The boundary layers of an unsteady incompressible stagnation-point flow with mass transfer AU - Fang, Tiegang AU - Lee, Chia-fon F. AU - Zhang, Ji T2 - INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS AB - In the current work, the boundary layers of an unsteady incompressible stagnation-point flow with mass transfer were further investigated. Similarity transformation technique was used and the similarity equation group was solved using numerical methods. Interesting observation is that there are multiple solutions seen for negative unsteadiness parameters, β. The influences of mass transfer, unsteadiness parameter, and Prandtl numbers on velocity and temperature profiles, wall drag, and wall heat fluxes were investigated and analyzed. The asymptotic behaviors for the similarity equations in limiting situations were theoretically analyzed. It is found that solutions exist for all mass transfer parameters for β≥−1. For a certain mass transfer parameter, there are two solutions when βc<β<0; there is one solution for (β=βc)∪(β≥0); there is no solution for β<βc, where βc is a critical unsteadiness parameter dependent on mass transfer parameter. DA - 2011/9// PY - 2011/9// DO - 10.1016/j.ijnonlinmec.2011.04.007 VL - 46 IS - 7 SP - 942-948 SN - 0020-7462 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79957829352&partnerID=MN8TOARS KW - Similarity solution KW - Mass transfer KW - Unsteady boundary layer KW - Stagnation-point flow ER - TY - JOUR TI - The Onset of Convection in a Heterogeneous Porous Medium with Vertical Throughflow AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - TRANSPORT IN POROUS MEDIA DA - 2011/6// PY - 2011/6// DO - 10.1007/s11242-011-9742-9 VL - 88 IS - 2 SP - 347-355 SN - 0169-3913 KW - Permeability heterogeneity KW - Throughflow KW - Thermal instability KW - Horizontal layer ER - TY - JOUR TI - The Effect of Vertical Throughflow on Thermal Instability in a Porous Medium Layer Saturated by a Nanofluid AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - TRANSPORT IN POROUS MEDIA DA - 2011/4// PY - 2011/4// DO - 10.1007/s11242-011-9717-x VL - 87 IS - 3 SP - 765-775 SN - 0169-3913 KW - Throughflow KW - Nanofluid KW - Porous medium KW - Instability KW - Natural convection ER - TY - JOUR TI - Radioembolization for Hepatocellular carcinoma a review of the evidence and treatment recommendations AU - Sangro, B. AU - Salem, R. AU - Kennedy, A. AU - Coldwell, D. AU - Wasan, H. T2 - American Journal of Clinical Oncology-Cancer Clinical Trials DA - 2011/// PY - 2011/// VL - 34 IS - 4 SP - 422-431 ER - TY - JOUR TI - Osteoblast adhesion to functionally graded hydroxyapatite coatings doped with silver AU - Sandukas, Stefan AU - Yamamoto, Akiko AU - Rabiei, Afsaneh T2 - JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A AB - Abstract Silver‐doped functionally graded hydroxyapatite (Ag‐FGHA) coatings have been prepared on glass and titanium substrates by ion beam assisted deposition (IBAD) method with in situ heat treatment, and the biological response and dissolution properties of the coatings have been examined. Three Ag‐FGHA coatings with different percentages of silver (1, 3, and 6.6 wt % Ag) were compared with pure FGHA (without Ag) as a control. MC 3T3‐E1 murine osteoblast cells were cultured on FGHA and Ag‐FGHA coating surfaces, and the number of adhered cells after 1, 4, and 7 days was counted. Micromanipulation of live single cells was performed to quantitatively compare cell affinity among the four coating compositions. Results showed that FGHA‐Ag1 coating (with 1 wt % Ag) had the highest number of adhered cells after each incubation period, as well as the highest cell affinity after 24‐h incubation. Surface profilometry was performed to determine surface roughness average ( R a ) of coating surfaces before and after immersion in high‐purity water, showing that all surfaces initially had roughness averages below 200 nm, while after immersion, roughness average of FGHA‐Ag1 surface was significantly increased ( R a = 404 +/− 100.8 nm), attributed to the highest rate of dissolution. Release rate of Ag + ions in solution was measured, showing release rates of silver ions for all Ag‐doped coatings were initially high and then gradually decreased to a minimum over time, which is the expected dissolution of functionally graded coatings. It is concluded that FGHA‐Ag1 coating promoted the highest degree of osteoblast adhesion because of optimal dissolution rate and nontoxic Ag percentage. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011. DA - 2011/6// PY - 2011/6// DO - 10.1002/jbm.a.33081 VL - 97A IS - 4 SP - 490-497 SN - 1552-4965 KW - hydroxyapatite coating KW - osteoblast KW - biological response KW - functionally graded KW - silver ER - TY - JOUR TI - Modeling instantaneous pressure drop of pleated thin filter media during dust loading AU - Fotovati, S. AU - Hosseini, S. A. AU - Tafreshi, H. Vahedi AU - Pourdeyhimi, B. T2 - CHEMICAL ENGINEERING SCIENCE AB - In this paper, we present a modeling methodology for studying the effects of dust loading on the pressure drop across pleated filters. Our simulations demonstrate that there exists an optimum pleat count for clean filters at which pressure drop reaches a minimum regardless of the in-plane or through-plane orientation of the fibers. With the particle deposition included in the analysis, our results indicated that the rate of increase in pressure drop decreases with increase in the pleat count. We demonstrated that a higher pleat count results in a higher flow velocity inside the pleat channels causing more non-uniformity in the dust deposition across the pleat. Especially when particles are sufficiently large, the dust cake tends to form deeper inside the pleated channel when the pleat count is high. This effect is observed to be less pronounced when the pleats have a triangular shape. We also showed that if the dust cake permeability is higher than that of the filters fibrous media, the rate of increase in pressure drop does not always decrease with increase in the pleat count. Finally, by comparing filters having 15 pleats per inch, we observed that rectangular pleats are preferred over the triangular pleats when the particles are highly inertial, i.e., filtering high-speed large particles. When particle's inertia is small, our results indicate that triangular pleats cause less pressure drop, and so are recommended. DA - 2011/9/15/ PY - 2011/9/15/ DO - 10.1016/j.ces.2011.05.038 VL - 66 IS - 18 SP - 4036-4046 SN - 1873-4405 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79960251378&partnerID=MN8TOARS KW - Aerosol KW - Filtration KW - Fluid mechanics KW - Porous media KW - Separation KW - CFD simulation ER - TY - JOUR TI - Microstructural Characterization of a High-Strength Aluminum Alloy Subjected to High Strain-Rate Impact AU - Lee, W. M. AU - Zikry, M. A. T2 - METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE DA - 2011/5// PY - 2011/5// DO - 10.1007/s11661-010-0476-z VL - 42A IS - 5 SP - 1215-1221 SN - 1543-1940 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79954431266&partnerID=MN8TOARS ER - TY - JOUR TI - Measuring efficiency of positive and negative ionic wind devices for comparison to fans and blowers AU - June, Michael S. AU - Kribs, James AU - Lyons, Kevin M. T2 - JOURNAL OF ELECTROSTATICS AB - Many industries are pursuing alternate air moving devices to reduce the power consumption of their air cooled products. The literature suggests that ionic AMDs have low efficiency. The literature, however, does not define efficiency the same way the computer industry defines it for rotary AMDs. In this study, static efficiency of ionic AMDs was evaluated similar to rotary AMDs. Various emitter to collector distances and various ring lengths, were evaluated for positive and negative coronas. By controlling emitter to collector distance and collector length, efficiencies were obtained more reasonably compared to rotary devices. DA - 2011/8// PY - 2011/8// DO - 10.1016/j.elstat.2011.04.010 VL - 69 IS - 4 SP - 345-350 SN - 1873-5738 KW - Ion-driven gas flow KW - Air moving device KW - Static efficiency KW - Fan performance curve KW - Airflow bench KW - Positive and negative corona discharge ER - TY - JOUR TI - MODELING OF AN ABLATION-FREE ELECTROTHERMAL PLASMA PELLET ACCELERATOR AU - Winfrey, A. Leigh AU - Abd Al-Halim, Mohamed AU - Gilligan, John G. AU - Saveliev, Alexei V. AU - Bourham, Mohamed A. T2 - FUSION SCIENCE AND TECHNOLOGY AB - Electromagnetic and electrothermal launch devices can provide high acceleration and inject pellets with speeds in excess of 3 km/s for masses up to 3gm. However, the ablation of the bore adds impurities to the plasma. An ablation-free electrothermal pellet accelerator is a concept that utilizes an ablation-free capillary discharge in which a quartz capillary is coated with a nanocrystalline diamond film (NCD). The ablation-free capillary connects to an extension tube, which is also an ablation-free quartz tube coated with NCD that serves as the acceleration barrel. An ablation-free capillary discharge computer code has been developed to model plasma flow and acceleration of pellets for fusion fueling in magnetic fusion reactors. The code incorporates ideal and non-ideal conductivity models and has a set of governing equations for the capillary, the acceleration tube, and the pellet. The capillary generates the plasma from hydrogen/deuterium gas when the discharge current flows through the capillary. The pellet starts moving in the extension tube when the pressure of the plasma flow from the capillary reaches the release limit. The code results show an exit velocity of 2.7 km/s for a 20 mg deuterium pellet when using a capillary and barrel each 9 cm long where the source and barrel diameters are 0.4cm and 0.6cm, respectively, with a discharge current of 20 kA over a 300 both the capillary and the barrel to 12 cm increases the pellet exit velocity to 2.9 km/s, and a further increase to 18cm results in a 3.15km/s pellet exit velocity. Increasing the barrel length to 36 cm, while keeping the source length at 18 cm, results in an increase in the pellet velocity to 3.32 km/s. The pellet starts moving at 35 μs reaches 3.32 km/s in 100 this velocity until exiting the acceleration tube. DA - 2011/8// PY - 2011/8// DO - 10.13182/fst60-480 VL - 60 IS - 2 SP - 480-485 SN - 1536-1055 ER - TY - JOUR TI - Increasing the solar cell power output by coating with transition metal-oxide nanorods AU - Kuznetsov, I. A. AU - Greenfield, M. J. AU - Mehta, Y. U. AU - Merchan-Merchan, W. AU - Salkar, G. AU - Saveliev, A. V. T2 - APPLIED ENERGY AB - Photovoltaic cells produce electric current through interactions among photons from an ambient light source and electrons in the semiconductor layer of the cell. However, much of the light incident on the panel is reflected or absorbed without inducing the photovoltaic effect. Transition metal-oxide nanoparticles, an inexpensive product of a process called flame synthesis, can cause scattering of light. Scattering can redirect photon flux, increasing the fraction of light absorbed in the thin active layer of silicon solar cells. This research aims to demonstrate that the application of transition metal-oxide nanorods to the surface of silicon solar panels can enhance the power output of the panels. Several solar panels were coated with a nanoparticle-methanol suspension, and the power outputs of the panels before and after the treatment were compared. The results demonstrate an increase in power output of up to 5% after the treatment. The presence of metal-oxide nanorods on the surface of the coated solar cells is confirmed by electron microscopy. DA - 2011/11// PY - 2011/11// DO - 10.1016/j.apenergy.2011.04.033 VL - 88 IS - 11 SP - 4218-4221 SN - 0306-2619 KW - Silicon solar cell KW - Light scattering KW - Nanoparticles KW - Transition metal-oxide nanorods ER - TY - JOUR TI - Gas-driven displacement of a liquid in a partially filled radial Hele-Shaw cell AU - Ward, T. AU - White, A. R. T2 - Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics DA - 2011/// PY - 2011/// VL - 83 IS - 4 ER - TY - JOUR TI - Experimental and theoretical studies of nanofluid thermal conductivity enhancement: a review AU - Kleinstreuer, Clement AU - Feng, Yu T2 - NANOSCALE RESEARCH LETTERS AB - Correction to Kleinstreuer C, Feng Y: Experimental and theoretical studies of nanofluid thermal conductivity enhancement: a review. Nanoscale Research Letters 2011, 6:229. DA - 2011/3/16/ PY - 2011/3/16/ DO - 10.1186/1556-276x-6-229 VL - 6 SP - SN - 1556-276X ER - TY - JOUR TI - Effects of thermal radiation on the boundary layer flow of a Jeffrey fluid over an exponentially stretching surface AU - Nadeem, Sohail AU - Zaheer, Shehla AU - Fang, Tiegang T2 - NUMERICAL ALGORITHMS DA - 2011/6// PY - 2011/6// DO - 10.1007/s11075-010-9423-8 VL - 57 IS - 2 SP - 187-205 SN - 1572-9265 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79955881202&partnerID=MN8TOARS KW - Jeffrey fluid KW - Porous stretching surface KW - Thermal radiations KW - Boundary layer flow KW - Series solutions ER - TY - JOUR TI - Effect of processing parameters on the microstructure and mechanical properties of Al-steel composite foam AU - Vendra, L. J. AU - Brown, J. A. AU - Rabiei, A. T2 - JOURNAL OF MATERIALS SCIENCE DA - 2011/7// PY - 2011/7// DO - 10.1007/s10853-011-5356-4 VL - 46 IS - 13 SP - 4574-4581 SN - 1573-4803 ER - TY - JOUR TI - Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers prepared by atmospheric plasma treatment and electrospinning AU - Shi, Quan AU - Vitchuli, Narendiran AU - Nowak, Joshua AU - Caldwell, Jane M. AU - Breidt, Frederick AU - Bourham, Mohamed AU - Zhang, Xiangwu AU - McCord, Marian T2 - EUROPEAN POLYMER JOURNAL AB - Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers were prepared by atmospheric plasma treatment and electrospinning. Atmospheric helium plasma treatment was first used to reduce the AgNO3 precursor in pre-electrospinning solutions into metallic silver nanoparticles, followed by electrospinning into continuous and smooth nanofibers with Ag nanoparticles embedded in the matrix. SEM, TEM, and EDX spectra were used to study the structure and surface elemental composition of the nanofibers. Silver nanoparticles, with diameters ranging between 3 and 6 nm, were found to be uniformly dispersed in the nanofiber matrix. The Ag/PAN nanofibers exhibited slow and long-lasting silver ion release, which provided robust antibacterial activity against both Gram-positive Bacillus cereus and Gram-negative Escherichia coli microorganisms. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.eurpolymj.2011.04.002 VL - 47 IS - 7 SP - 1402-1409 SN - 1873-1945 KW - Atmospheric plasma KW - Electrospinning KW - Nanofibers KW - Ag nanoparticles KW - Antibacterial activity ER - TY - JOUR TI - Double-diffusive natural convective boundary-layer flow of a nanofluid past a vertical plate AU - Kuznetsov, A. V. AU - Nield, D. A. T2 - INTERNATIONAL JOURNAL OF THERMAL SCIENCES AB - The double-diffusive natural convective boundary-layer flow of a nanofluid past a vertical plate is studied analytically. The model used for the binary nanofluid incorporates the effects of Brownian motion and thermophoresis. In addition the thermal energy equations include regular diffusion and cross-diffusion terms. A similarity solution is presented. Numerical calculations were performed in order to obtain correlation formulas giving the reduced Nusselt number as a function of the various relevant parameters. DA - 2011/5// PY - 2011/5// DO - 10.1016/j.ijthermalsci.2011.01.003 VL - 50 IS - 5 SP - 712-717 SN - 1290-0729 KW - Nanofluid KW - Double-diffusive natural convection KW - Cross-diffusion KW - Boundary layer KW - Vertical plate ER - TY - JOUR TI - Distribution characteristics of exhaust gases and soot particles in a wall-flow ceramics filter AU - Wu, Guojiang AU - Kuznetsov, Andrey V. AU - Jasper, Warren J. T2 - JOURNAL OF AEROSOL SCIENCE AB - An inhomogeneous soot distribution in a diesel particulate filter may deteriorate its behavior and result in higher pressure drops and fuel consumption. This will cause mechanical stresses on the filter due to temperature gradients resulting from the non-uniformly burning of soot during regeneration. The purpose of this paper is to investigate the flow distribution of the exhaust gas entering into a diesel particulate filter, the turbulent motion of diesel soot particles in the inlet header, and their deposition and distribution in the front surface of a diesel particulate filter. A Lagranian continuous random walk (CRW) model is developed to simulate soot particulate motion, which considers a succession of uncorrelated random forcing and drift corrections. The effects of particle inertia, turbulent fluctuation, and lift on the particle motion and trajectory are analyzed. Correlations of the uniformity index of the exhaust gas and soot particles with the flow rate, soot loading, and inlet expansion angle are evaluated. The results show that there is a two-peak phenomenon in the soot distribution at the front entrance of the filter, which is comprised of a peak in the central area due to inertia and a second peak in the periphery owing to diffusion and recirculation action. Exhaust flow rates and the inlet expansion angle have a major influence on the flow uniformity and soot uniformity, while soot loading has a slightly smaller effect on soot uniformity. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.jaerosci.2011.04.003 VL - 42 IS - 7 SP - 447-461 SN - 1879-1964 KW - Filtration KW - Multiphase flow KW - Diesel particulate filters KW - Nanoparticle KW - Flow maldistribution KW - Continuous random walk ER - TY - JOUR TI - Development of Instrumented Manikin Hands for Characterizing the Thermal Protective Performance of Gloves in Flash Fire Exposures AU - Hummel, Alexander AU - Barker, Roger AU - Lyons, Kevin AU - Deaton, A. Shawn AU - Morton-Aslanis, John T2 - FIRE TECHNOLOGY DA - 2011/7// PY - 2011/7// DO - 10.1007/s10694-010-0190-9 VL - 47 IS - 3 SP - 615-629 SN - 0015-2684 KW - Flame protection KW - Thermal protection KW - Protective clothing KW - Protective gloves KW - Skin burns KW - Instrumented manikin fire test systems ER - TY - JOUR TI - Airflow analysis in the alveolar region using the lattice-Boltzmann method AU - Li, Z. AU - Kleinstreuer, C. T2 - MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING DA - 2011/4// PY - 2011/4// DO - 10.1007/s11517-011-0743-1 VL - 49 IS - 4 SP - 441-451 SN - 1741-0444 ER - TY - JOUR TI - A three-velocity three-temperature model for a tridisperse porous medium: Forced convection in a channel AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - International Journal of Heat and Mass Transfer AB - A three-velocity three-temperature model for tridisperse porous media is formulated. Using the model, an analytic solution is obtained for the problem of forced convection in a channel between parallel plane walls that are held either at uniform temperature or uniform heat flux. In each case, Nusselt number values are given as functions of conductivity ratios, velocity ratios, volume fractions, and internal heat exchange parameters. DA - 2011/// PY - 2011/// DO - 10.1016/j.ijheatmasstransfer.2011.02.013 VL - 54 IS - 11-12 SP - 2490-2498 ER - TY - JOUR TI - Validation of a single-mode polymer optical fiber sensor and interrogator for large strain measurements AU - Abdi, Omid AU - Peters, Kara AU - Kowalsky, Mervyn AU - Hassan, Tasnim T2 - MEASUREMENT SCIENCE AND TECHNOLOGY AB - A single-mode polymer optical fiber (POF) in a Mach–Zehnder interferometer configuration is validated for the measurement of tensile nominal elongation of the POF up to 10%. The single-mode POF sensors were unmounted and surface mounted on aluminum tensile coupons for strain measurements. The measured strains from the POF sensors were compared to extensometer measurements for validation. The phase response of the interferometer was measured with a 3 × 3 coupler interrogator. The coupler arrangement was configured to permit the extraction of potential intensity changes in the sensor arm. The phase-shift–strain response of the POF sensors was repeatable for the loading and unloading measurements. The nonlinearity of the phase-shift–strain response was greater than that measured during pure tensile loading of the POF, presumably due to the behavior of the adhesive between the optical fiber and the aluminum coupons. DA - 2011/7// PY - 2011/7// DO - 10.1088/0957-0233/22/7/075207 VL - 22 IS - 7 SP - SN - 1361-6501 KW - strain sensor KW - polymer optical fiber KW - large deformation ER - TY - JOUR TI - Unsteady stagnation-point flow over a plate moving along the direction of flow impingement AU - Zhong, Y. AU - Fang, Tiegang T2 - International Journal of Heat and Mass Transfer AB - Unsteady plane and axisymmetric stagnation flow of an incompressible viscous fluid on the body that moves along the oncoming flow with a time-dependent velocity is studied in this work. Similarity solutions for the full Navier–Stokes equations are obtained and the results of the flow velocity, shear stress and stream lines are reported for both plane two dimensional flow and axisymmetric flow. The results show that the features of the similar boundary flow highly depends on a characteristic parameter β. There exists a critical value βc below which no similarity solution to the flow is found. When βc < β < 0, two solution branches exist and different flow patterns appear for each branch. Flow with monophonically growing velocity, reversed flow and flow with S-shaped velocity are obtained for various values of β. The boundary layer thickness of the plane and axisymmetric flows is tabulated, the streamlines of the flow are demonstrated, and the shear stress over the boundary layer is also discussed. DA - 2011/// PY - 2011/// DO - 10.1016/j.ijheatmasstransfer.2011.04.024 VL - 54 IS - 15-16 SP - 3103-3108 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79956195087&partnerID=MN8TOARS KW - Similarity solutions KW - Unsteady boundary layer KW - Stagnation point flow KW - Moving body ER - TY - JOUR TI - The onset of double-diffusive convection in a nanofluid layer AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW AB - The onset of double-diffusive convection in a horizontal layer of a nanofluid is studied analytically. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. In addition the thermal energy equations include regular diffusion and cross-diffusion terms. The stability boundaries for both non-oscillatory and oscillatory cases have been approximated by simple analytical expressions. Physical significance of the obtained results is discussed. DA - 2011/8// PY - 2011/8// DO - 10.1016/j.ijheatfluidflow.2011.03.010 VL - 32 IS - 4 SP - 771-776 SN - 1879-2278 ER - TY - JOUR TI - The onset of convection in a tridisperse porous medium AU - Kuznetsov, A. V. AU - Nield, D. A. T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER AB - This paper develops a theory of mass, momentum, and heat transfer in a tridisperse porous medium. Coupling between three different scales present in this medium is accounted for by introducing momentum and interphase heat transfer coupling coefficients. The developed theory is then applied to solve the classical Rayleigh–Bénard problem, for the onset of convection in a horizontal layer uniformly heated from below, for this new type of a porous medium. The formulation uses the Darcy law, which now results in three different filtration velocities in three porosity scales present in this medium. The linear stability analysis leads to an expression for the critical Rayleigh number as a function of three volume fractions, two permeability ratios, two thermal capacity ratios, two thermal conductivity ratios, two inter-phase heat transfer parameters and two inter-phase momentum transfer parameters. The dependence of the critical Rayleigh number on these parameters is investigated. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.ijheatmasstransfer.2011.04.021 VL - 54 IS - 15-16 SP - 3120-3127 SN - 0017-9310 KW - Tridisperse medium KW - Three-velocity KW - Three-temperature KW - Natural convection KW - Horizontal layer KW - Stability ER - TY - JOUR TI - The Cheng-Minkowycz problem for natural convection about a vertical plate embedded in a tridisperse porous medium AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER AB - The classical Cheng–Minkowycz study of convection past a vertical plate embedded in a porous medium has been extended to the case of a tridisperse porous medium (TDPM). The boundary-layer analysis leads to expressions for the velocity and temperature fields in terms of two geometrical parameters, two inter-phase momentum transfer parameters, two thermal diffusivity ratios, two permeability ratios, two thermal conductivity ratios, and two inter-phase heat transfer parameters. For the leading edge region, and for an inner layer, a similarity solution is obtained. This involves the first eight parameters, each of which is a characteristic of the TDPM. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.ijheatmasstransfer.2011.03.037 VL - 54 IS - 15-16 SP - 3485-3493 SN - 0017-9310 KW - Tridisperse porous medium KW - Cheng-Minkowycz problem KW - Natural convection KW - Boundary layer ER - TY - JOUR TI - Rye-derived powdery mildew resistance gene Pm8 in wheat is suppressed by the Pm3 locus AU - McIntosh, Robert A. AU - Zhang, Peng AU - Cowger, Christina AU - Parks, Ryan AU - Lagudah, Evans S. AU - Hoxha, Sami T2 - THEORETICAL AND APPLIED GENETICS DA - 2011/8// PY - 2011/8// DO - 10.1007/s00122-011-1589-5 VL - 123 IS - 3 SP - 359-367 SN - 1432-2242 ER - TY - JOUR TI - Numerical studies on flame inclination in porous media combustors AU - Zheng, Chenghang AU - Cheng, Leming AU - Saveliev, Alexei AU - Luo, Zhongyang AU - Cen, Kefan T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER AB - Inclinational instability developing during propagation of a filtration combustion wave in an inert porous medium is studied using two-dimensional numerical model. Stable and unstable combustion waves are generated by varying combustion parameters such as pressure, equivalence ratio, filtration velocity, effective conductivity of porous media, pellet diameter and combustor scale. The wave propagation velocity of inclinational flame is studied and compared with flat flame. The growth and reduction of inclinational instability are analyzed at different conditions. The numerical results show that a development of inclinational instability causes essential flow non-uniformity and can result in a separation of the flame front in the multiple flame zones. The limited conductive and radiant heat transfer in the solid phase, small pellet diameter of packed bed, high inlet velocity, large combustor scale and low equivalence ratio promote the instability growth. The inclinational instability is suppressed in a reciprocal combustor. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.ijheatmasstransfer.2011.02.066 VL - 54 IS - 15-16 SP - 3642-3649 SN - 0017-9310 KW - Porous media KW - Filtration combustion KW - Inclinational instability ER - TY - JOUR TI - Modeling of retrograde nanoparticle transport in axons and dendrites AU - Kuznetsov, A. V. T2 - INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER AB - This paper presents a pioneering modeling study on nanoparticle internalization and transport in neurons. The model developed in this paper is based on recent experimental results that indicate that after entering a neurite by endocytosis, nanoparticles are transported toward the neuron soma in endocytic vesicles by retrograde molecular-motor-driven transport. Experimental results also indicate that nanoparticles enter axons at axon terminals while in dendrites they enter through the entire plasma membrane. The model equations developed in this paper are based on these experimental observations. The analytical solution of these equations is obtained; the solution predicts the distribution of the concentration of nanoparticles associated with free nanoparticle-loaded vesicles (NLVs) (not transported on microtubules (MTs)) as well as the distribution of the concentration of nanoparticles associated with NLVs transported on MTs by dynein motors. The fluxes of nanoparticles by diffusion and motor-driven transport as well as the total (combined) flux of nanoparticles are also predicted. DA - 2011/5// PY - 2011/5// DO - 10.1016/j.icheatmasstransfer.2011.03.015 VL - 38 IS - 5 SP - 543-547 SN - 0735-1933 KW - Nanoparticle transport KW - Neurons KW - Axons and dendrites KW - Nanomedicine KW - Molecular motors KW - Fast axonal transport ER - TY - JOUR TI - Investigations of Lift-Based Pitch-Plunge Equivalence for Airfoils at Low Reynolds Numbers AU - McGowan, Gregory Z. AU - Granlund, Kenneth AU - Ol, Michael V. AU - Gopalarathnam, Ashok AU - Edwards, Jack R. T2 - AIAA JOURNAL AB - The limits of linear superposition in two-dimensional high-rate low-Reynolds-number aerodynamics are examined by comparing the lift-coefficient history and flowfield evolution for airfoils undergoing harmonic motions in pure pitch, pure plunge, and pitch―plunge combinations. Using quasi-steady airfoil theory and Theodorsen's formula as predictive tools, pitching motions are sought that produce lift histories identical to those of prescribed plunging motions. It follows that a suitable phasing of pitch and plunge in a combined motion should identically produce zero lift, canceling either the circulatory contribution (with quasi-steady theory) or the combination of circulatory and noncirculatory contributions (with Theodorsen's formula). Lift history is measured experimentally in a water tunnel using a force balance and is compared with two-dimensional Reynolds-averaged Navier―Stokes computations and Theodorsen's theory; computed vorticity contours are compared with dye injection in the water tunnel. Theodorsen's method evinces considerable, and perhaps surprising, resilience in finding pitch-to-plunge equivalence of lift-coefficient―time history, despite its present application to cases in which its mathematical assumptions are demonstrably violated. A combination of pitch and plunge motions can be found such that net lift coefficient is nearly identically zero for arbitrarily high reduced frequency, provided that amplitude is small. Conversely, cancellation is possible at large motion amplitude, provided that reduced frequency is moderate. The product of Strouhal number and nondimensional amplitude is therefore suggested as the upper bound for when superposition and linear predictions remain valid in massively unsteady two-dimensional problems. DA - 2011/7// PY - 2011/7// DO - 10.2514/1.j050924 VL - 49 IS - 7 SP - 1511-1524 SN - 0001-1452 ER - TY - JOUR TI - Investigation of lifted jet flames stabilization mechanism using RANS simulations AU - Wang, Wei AU - Echekki, Tarek T2 - FIRE SAFETY JOURNAL AB - The mean structure, stability and the lift-off heights of lifted methane-air flames in a turbulent round jet are computed using the Reynolds-averaged Navier-Stokes (RANS) approach coupled with the Eddy-Dissipation Model (EDM) for combustion. The computations are based on a 5-step methane-air reduced mechanism. The simulation results show that the EDM model reproduces a mean partially-premixed flame structure at the leading edge of the lifted flame. The fine-tuning of the main EDM parameter for experimental lifted flames with co-flow also results in very good predictions of the lift-off height for lifted flames without co-flow. Implications of the use of the EDM concept for partially premixed flames are discussed. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.firesaf.2011.02.007 VL - 46 IS - 5 SP - 254-261 SN - 1873-7226 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79956106844&partnerID=MN8TOARS KW - Lift-off KW - Stability KW - CFX KW - EDM KW - RANS KW - Triple flames ER - TY - JOUR TI - Impact analysis of natural convection on thermal conductivity measurements of nanofluids using the transient hot-wire method AU - Hong, Sung Wook AU - Kang, Yong-Tae AU - Kleinstreuer, Clement AU - Koo, Junemo T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER AB - Significant deviations between published results have been reported measuring the effective thermal conductivity of nanofluids with the transient hot-wire method (THWM). This may be attributed to a poor selection of the temperature data range, which should meet the following conditions. The start time should be chosen after the conductive heat flux delay time, while the end time should be selected before a crossover point when natural convection becomes significant. Considering an EG-based 1.06 vol.% ZnO nanofluid, the thermal conductivity was measured to increase by 5.4% over that of the base fluid. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.ijheatmasstransfer.2011.03.041 VL - 54 IS - 15-16 SP - 3448-3456 SN - 1879-2189 KW - Transient hot-wire method (THWM) KW - Thermal conductivity KW - Natural convection KW - Nanofluids ER - TY - JOUR TI - Hysteretic neural network modeling of spring-coupled piezoelectric actuators AU - Lien, J. P. AU - Fang, Tiegang AU - Buckner, Gregory D. T2 - SMART MATERIALS AND STRUCTURES AB - This paper discusses the development of a high-fidelity, computationally efficient model for spring-coupled piezoelectric stack actuators. The model is based on a hysteretic recurrent neural network (HRNN), and aims to balance computational tractability with physical intuition. Previous work has detailed the development and experimental validation of an HRNN model for unloaded piezoelectric actuators. This paper extends the modeling approach to incorporate coupling with linear springs, and discusses training techniques based on genetic algorithms, which provide advantages over the previously employed Levenberg–Marquardt methods in terms of accuracy and model complexity. The resulting models are computable in real time. Model validity is established by comparison with a rate-dependent threshold-discrete Prandtl–Ishlinskii model. DA - 2011/6// PY - 2011/6// DO - 10.1088/0964-1726/20/6/065007 VL - 20 IS - 6 SP - SN - 1361-665X UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79956193310&partnerID=MN8TOARS ER - TY - JOUR TI - Electrothermomechanical Finite-Element Modeling of Metal Microcontacts in MEMS AU - Shanthraj, Pratheek AU - Rezvanian, Omid AU - Zikry, Mohammed A. T2 - JOURNAL OF MICROELECTROMECHANICAL SYSTEMS AB - Three-dimensional fractal representations of surface roughness are incorporated into a finite-element framework to obtain the electrothermomechanical behavior of ohmic contacts in radio frequency (RF) microelectromechanical systems (MEMS) switches. Fractal surfaces are generated from the Weierstrass-Mandelbrot function and are representatives of atomic force microscope surface roughness measurements of contact surfaces in fabricated RF MEMS switches with metal contacts. A specialized finite-element scheme is developed, which couples the thermomechanical asperity creep deformations with the electromechanical contact characteristics to obtain predictions of contact parameters and their evolution as a function of time and loading. A dislocation-density-based crystal plasticity framework is also used to investigate microstructure evolution at microcontacts and its effects on contact parameters. Using this approach, simulations are made to investigate how surface roughness, initial residual strains, and operating temperature can affect asperity contact behavior. Based on these predictions, tribological design guidelines can be obtained to increase the lifetime of low-contact-resistance RF MEMS switches by limiting stiction and electrical resistance increase. DA - 2011/4// PY - 2011/4// DO - 10.1109/jmems.2010.2100020 VL - 20 IS - 2 SP - 371-382 SN - 1941-0158 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79953737151&partnerID=MN8TOARS KW - Creep KW - crystal plasticity KW - electrical contact KW - finite element KW - microelectromechanical systems (MEMS) KW - microcontact KW - residual strain KW - RF MEMS ER - TY - JOUR TI - Elasticity and stress relaxation of a very small vocal fold AU - Riede, Tobias AU - York, Alexander AU - Furst, Stephen AU - Mueller, Rolf AU - Seelecke, Stefan T2 - JOURNAL OF BIOMECHANICS AB - Across mammals many vocal sounds are produced by airflow induced vocal fold oscillation. We tested the hypothesis that stress–strain and stress-relaxation behavior of rat vocal folds can be used to predict the fundamental frequency range of the species' vocal repertoire. In a first approximation vocal fold oscillation has been modeled by the string model but it is not known whether this concept equally applies to large and small species. The shorter the vocal fold, the more the ideal string law may underestimate normal mode frequencies. To accommodate the very small size of the tissue specimen, a custom-built miniaturized tensile test apparatus was developed. Tissue properties of 6 male rat vocal folds were measured. Rat vocal folds demonstrated the typical linear stress–strain behavior in the low strain region and an exponential stress response at strains larger than about 40%. Approximating the rat's vocal fold oscillation with the string model suggests that fundamental frequencies up to about 6 kHz can be produced, which agrees with frequencies reported for audible rat vocalization. Individual differences and time-dependent changes in the tissue properties parallel findings in other species, and are interpreted as universal features of the laryngeal sound source. DA - 2011/7/7/ PY - 2011/7/7/ DO - 10.1016/j.jbiomech.2011.04.024 VL - 44 IS - 10 SP - 1936-1940 SN - 1873-2380 KW - Larynx KW - Viscoelastic properties KW - Bioacoustics KW - Anisotropy ER - TY - JOUR TI - Design, modeling, fabrication, and evaluation of the air amplifier for improved detection of biomolecules by electrospray ionization mass spectrometry AU - Robichaud, Guillaume AU - Dixon, R. Brent AU - Potturi, Amarnatha S. AU - Cassidy, Dan AU - Edwards, Jack R. AU - Sohn, Alex AU - Dow, Thomas A. AU - Muddiman, David C. T2 - INTERNATIONAL JOURNAL OF MASS SPECTROMETRY AB - Through a multi-disciplinary approach, the air amplifier is being evolved as a highly engineered device to improve detection limits of biomolecules when using electrospray ionization. Several key aspects have driven the modifications to the device through experimentation and simulations. We have developed a computer simulation that accurately portrays actual conditions and the results from these simulations are corroborated by the experimental data. These computer simulations can be used to predict outcomes from future designs resulting in a design process that is efficient in terms of financial cost and time. We have fabricated a new device with annular gap control over a range of 50 to 70 μm using piezoelectric actuators. This has enabled us to obtain better aerodynamic performance when compared to the previous design (2× more vacuum) and also more reproducible results. This is allowing us to study a broader experimental space than the previous design which is critical in guiding future directions. This work also presents and explains the principles behind a fractional factorial design of experiments methodology for testing a large number of experimental parameters in an orderly and efficient manner to understand and optimize the critical parameters that lead to obtain improved detection limits while minimizing the number of experiments performed. Preliminary results showed that several folds of improvements could be obtained for certain condition of operations (up to 34 folds). DA - 2011/3/1/ PY - 2011/3/1/ DO - 10.1016/j.ijms.2010.04.006 VL - 300 IS - 2-3 SP - 99-107 SN - 1873-2798 KW - Air amplifier KW - Electrospray ionization KW - Modeling KW - Detection limits ER - TY - JOUR TI - Computational analysis of airflow and nanoparticle deposition in a combined nasal-oral-tracheobronchial airway model AU - Zhang, Zhe AU - Kleinstreuer, Clement T2 - JOURNAL OF AEROSOL SCIENCE AB - In light of the exponentially increasing industrial production and consumer use of ultrafine particles, deposition in the human lung is of great environmental and biomedical concern, especially for children, asthmatics and the elderly. Considering spherical nanoparticles in the 1–100 nm mean-diameter range and different breathing routes with Qtotal=30 and 60 L/min, local deposition fractions and global surface concentrations were predicted employing an experimentally validated computer simulation model. It was found that the change in breathing route (from nasal to oral breathing) not only significantly influences nanoparticle deposition in the regions of nasal and oral cavities, nasopharynx and oropharynx, but also measurably affects depositions from pharynx to bronchial airways for tiny nanoparticles (≤5 nm). The effect of breathing routes on deposition of larger nanoparticles (>5 nm) after the pharynx tends to be minor. The impact of different outlet flow-rate ratios generated by downstream resistances, e.g., caused by airway inflammation or tumors, is discussed in this study as well. Specifically, different outlet pressures primarily influence the velocity profiles and nanoparticle deposition fractions at that particular branch and adjacent bifurcations. In addition, the impact of change in outlet flow rate ratio on total deposition is confined to all same-level bifurcations and direct upstream-level bifurcations. The mass transfer coefficients of depositing nanoparticles (in terms of Sherwood number) can be well correlated as a function of Reynolds number and Schmidt number. The influence of downstream resistance on the Sherwood number in bronchial airways is smaller than intra-subject effects, i.e., variations of bifurcation levels and geometric parameters. DA - 2011/3// PY - 2011/3// DO - 10.1016/j.jaerosci.2011.01.001 VL - 42 IS - 3 SP - 174-194 SN - 1879-1964 KW - Breathing routes KW - Computational analysis KW - Laminar-to-turbulent airflow KW - Nanoparticle deposition efficiencies KW - Downstream resistances KW - Mass transfer correlation ER - TY - JOUR TI - Bio-thermal convection induced by two different species of microorganisms AU - Kuznetsov, A. V. T2 - INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER AB - This paper develops a theory of bio-thermal convection in a suspension that contains two species of microorganisms exhibiting different taxes, gyrotactic and oxytactic microorganisms. The developed theory is applied to investigating the onset of bio-thermal convection in such a suspension occupying a horizontal layer of finite depth. A linear stability analysis is utilized to derive the equations for the amplitudes of disturbances. The obtained eigenvalue problem is solved by the Galerkin method. The case of non-oscillatory instability in a layer with a rigid lower boundary and a stress-free upper boundary is investigated. The resulting eigenvalue equation relates three Rayleigh numbers, the traditional Rayleigh number (Ra) and two bioconvection Rayleigh numbers, one for gyrotactic (Rbg) and one for oxytactic (Rbo) microorganisms. The neutral stability boundary is presented in the form of a diagram showing that boundary in the (Ra, Rag) plane for different values of Rao. DA - 2011/5// PY - 2011/5// DO - 10.1016/j.icheatmasstransfer.2011.02.006 VL - 38 IS - 5 SP - 548-553 SN - 1879-0178 KW - Thermo-bioconvection KW - Gyrotactic and oxytactic microorganisms KW - Natural convection KW - Horizontal layer ER - TY - JOUR TI - A self-repairing polymer waveguide sensor AU - Song, Young J. AU - Peters, Kara J. T2 - SMART MATERIALS AND STRUCTURES AB - This paper presents experimental demonstrations of a self-repairing strain sensor waveguide created by self-writing in a photopolymerizable resin system. The sensor is fabricated between two multi-mode optical fibers via lightwaves in the ultraviolet (UV) wavelength range and operates as a sensor through interrogation of the power transmitted through the waveguide in the infrared (IR) wavelength range. After failure of the sensor occurs due to loading, the waveguide re-bridges the gap between the two optical fibers through the UV resin. The response of the original sensor and the self-repaired sensor to strain are measured and show similar behaviors. DA - 2011/6// PY - 2011/6// DO - 10.1088/0964-1726/20/6/065005 VL - 20 IS - 6 SP - SN - 1361-665X ER - TY - JOUR TI - A note on the Blasius and Sakiadis flow of a non-Newtonian power-law fluid in a constant transverse magnetic field AU - Pantokratoras, Asterios AU - Fang, Tiegang T2 - ACTA MECHANICA DA - 2011/4// PY - 2011/4// DO - 10.1007/s00707-010-0406-6 VL - 218 IS - 1-2 SP - 187-194 SN - 0001-5970 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79953028742&partnerID=MN8TOARS ER - TY - JOUR TI - Wavelength hopping due to spectral distortion in dynamic fiber Bragg grating sensor measurements AU - Webb, S AU - Peters, K AU - Zikry, M AU - Vella, T AU - Chadderdon, S AU - Selfridge, R AU - Schultz, S T2 - Measurement Science and Technology AB - We demonstrate the measurement of wavelength hopping in dynamic fiber Bragg grating (FBG) sensor measurements and its effect on the interpretation of the dynamic behavior of a composite laminate. Strain measurements are performed with FBG sensors embedded in laminates, subjected to low-velocity impacts, with data acquired using a commercial peak wavelength following controller and a high-speed full-spectral interrogator recently developed by the authors. The peak follower response is theoretically predicted from the full-spectral interrogator measurements. We demonstrate that dynamic wavelength hopping does occur, that it changes the apparent dynamic behavior of the composite and that it can be directly predicted from the dynamic spectral distortion. We also demonstrate that full-spectral data acquisition at speeds lower than those required to fully resolve the dynamic event creates apparent measurement errors due to wavelength hopping as well. DA - 2011/5/4/ PY - 2011/5/4/ DO - 10.1088/0957-0233/22/6/065301 VL - 22 IS - 6 SP - 065301 J2 - Meas. Sci. Technol. OP - SN - 0957-0233 1361-6501 UR - http://dx.doi.org/10.1088/0957-0233/22/6/065301 DB - Crossref KW - fiber Bragg grating sensor KW - dynamic sensing KW - spectral distortion KW - wavelength hopping ER - TY - JOUR TI - Thermal analysis of an annular fin with (a) simultaneously imposed base temperature and base heat flux and (b) fixed base and tip temperatures AU - Aziz, Abdul AU - Fang, Tiegang T2 - ENERGY CONVERSION AND MANAGEMENT AB - The performance of an annular fin with uniform thickness losing heat by convection to its surroundings is studied analytically for two sets of boundary conditions: (a) simultaneously prescribed base temperature and base heat flux, (b) specified base and tip temperatures. For (a) analytical expressions are derived for the temperature distribution, the tip heat flow, and the Biot number at the tip. For the fin tip to be insulated, a relationship between the base heat flow, the radii of the fin, and the fin parameter must be satisfied. Based on the base heat flow for the insulated tip, an expression is derived for the tip temperature. For part (b), analytical solutions are presented for the temperature distribution, base heat flow, and tip heat flow. For the adiabatic tip condition, a relation between the tip temperature, the fin parameter, and the radii of the fin must be satisfied. The condition under which the fin tip can be freely exposed to the environment is established. The graphical results provide a comprehensive picture of the thermal performance of the annular fin under both cooling and heating conditions. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.enconman.2011.02.004 VL - 52 IS - 7 SP - 2467-2478 SN - 1879-2227 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79952802659&partnerID=MN8TOARS KW - Heat conduction KW - Annular fins KW - Thermosyphon KW - Condensation KW - Analytical solutions ER - TY - JOUR TI - THE EFFECT OF LOCAL THERMAL NONEQUILIBRIUM ON THE ONSET OF CONVECTION IN A POROUS MEDIUM LAYER SATURATED BY A NANOFLUID: BRINKMAN MODEL AU - Kuznetsov, A. V. AU - Nield, D. A. T2 - JOURNAL OF POROUS MEDIA AB - The onset of convection in a horizontal layer of a porous medium saturated by a nanofluid is studied analytically. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. For the porous medium the Brinkman model is employed. Three cases of free-free, rigid-rigid, and rigid-free boundaries are considered. The effect of local thermal nonequilibrium between the particle, fluid, and solid-matrix phases is investigated using a three-temperature model. The analysis reveals that in some circumstances the effect of local thermal nonequilibrium (LTNE) can be significant, but for a typical dilute nanofluid (with large Lewis number and with small particle-to-fluid heat capacity ratio) the effect is small. DA - 2011/// PY - 2011/// DO - 10.1615/jpormedia.v14.i4.10 VL - 14 IS - 4 SP - 285-293 SN - 1934-0508 KW - local thermal nonequilibrium KW - LTNE KW - nanofluid KW - porous medium KW - instability KW - natural convection ER - TY - JOUR TI - Syngas production in hybrid filtration combustion AU - Toledo, Mario AU - Vergara, Eduardo AU - Savelieu, Alexei V. T2 - INTERNATIONAL JOURNAL OF HYDROGEN ENERGY AB - Rich and ultrarich combustion of butane inside porous media composed of aleatory wood pellets and alumina spheres is studied experimentally to evaluate the suitability of the concept for syngas production. Temperature, velocity, and chemical products of the combustion waves were recorded experimentally at a range of equivalence ratios from stoichiometry (φ = 1.0) to φ = 2.6. It is observed that hydrogen and carbon monoxide are dominant partial oxidation products for ultrarich hybrid combustion waves of butane and wood pellets. Syngas yield in hybrid filtration combustion is found to be essentially higher than for butane filtration combustion in an inert porous medium. DA - 2011/3// PY - 2011/3// DO - 10.1016/j.ijhydene.2010.11.060 VL - 36 IS - 6 SP - 3907-3912 SN - 1879-3487 KW - Syngas production KW - Partial oxidation KW - Hybrid filtration combustion KW - Porous media ER - TY - JOUR TI - Nanofluid bioconvection in water-based suspensions containing nanoparticles and oxytactic microorganisms: oscillatory instability AU - Kuznetsov, Andrey V. T2 - NANOSCALE RESEARCH LETTERS AB - The aim of this article is to propose a novel type of a nanofluid that contains both nanoparticles and motile (oxytactic) microorganisms. The benefits of adding motile microorganisms to the suspension include enhanced mass transfer, microscale mixing, and anticipated improved stability of the nanofluid. In order to understand the behavior of such a suspension at the fundamental level, this article investigates its stability when it occupies a shallow horizontal layer. The oscillatory mode of nanofluid bioconvection may be induced by the interaction of three competing agencies: oxytactic microorganisms, heating or cooling from the bottom, and top or bottom-heavy nanoparticle distribution. The model includes equations expressing conservation of total mass, momentum, thermal energy, nanoparticles, microorganisms, and oxygen. Physical mechanisms responsible for the slip velocity between the nanoparticles and the base fluid, such as Brownian motion and thermophoresis, are accounted for in the model. An approximate analytical solution of the eigenvalue problem is obtained using the Galerkin method. The obtained solution provides important physical insights into the behavior of this system; it also explains when the oscillatory mode of instability is possible in such system. DA - 2011/// PY - 2011/// DO - 10.1186/1556-276x-6-100 VL - 6 SP - SN - 1556-276X ER - TY - JOUR TI - High temperature deformation characteristics of Zirlo (TM) tubing via ring-creep and burst tests AU - Seok, C. S. AU - Marple, B. AU - Song, Y. J. AU - Gollapudi, S. AU - Charit, I. AU - Murty, K. L. T2 - NUCLEAR ENGINEERING AND DESIGN AB - Abstract Fuel cladding tubing acting as a barrier between coolant and radioactive fuel pellets in light water reactors undergo a combination of mechanical and thermal effects along with corrosive conditions during normal operations as well as accident situations, such as LOCA, etc. Therefore, the mechanical integrity of the cladding tubing is of critical importance. In this study, high temperature deformation characteristics of niobium-containing zirconium alloy cladding materials (Zirlo™) have been evaluated via both ring-creep and burst tests. Creep-rupture data are presented in terms of Larson–Miller parameters (LMP). Data (creep rate vs. stress) from ring-creep and burst tests are analyzed, and operating deformation mechanisms are elucidated. This study demonstrates that the hoop creep data obtained from ring-creep and burst tests are equivalent, and one can be replaced with the other, if needed, in order to evaluate creep life. DA - 2011/3// PY - 2011/3// DO - 10.1016/j.nucengdes.2010.04.017 VL - 241 IS - 3 SP - 599-602 SN - 0029-5493 ER - TY - JOUR TI - Effect of the flow in a printing nip on paper runnability during sheetfed offset printing AU - Diaz, F. J. AU - Kuznetsov, A. V. T2 - Appita Journal DA - 2011/// PY - 2011/// VL - 64 IS - 2 SP - 158- ER - TY - JOUR TI - Thickness shear mode quartz crystal resonators with optimized elliptical electrodes AU - Ting-Feng, Ma AU - Chao, Zhang AU - Xiao-Ning, Jiang AU - Guan-Ping, Feng T2 - CHINESE PHYSICS B AB - Quartz crystal resonators (QCRs) with circular electrodes have been widely used for various liquid and gas sensing applications. In this work, quartz crystal resonators with elliptical electrodes were studied and tested for liquid property measurement. Mindlin's theory was used to optimize the dimension and geometry of the electrodes and a 5-MHz QCR with minimum series resistance and without any spurious modes was obtained. A series of AT-cut QCRs with elliptical electrodes of different sizes were fabricated and their sensing performances were compared to devices with circular electrodes. The experimental result shows that the device with elliptical electrodes can obtain lower resonance impedance and a higher Q factor, which results in a better loading capability. Even though the sensitivities of devices with elliptical and circular electrodes are found to be similar, the sensor with elliptical electrodes has much higher resolution due to a better frequency stability. The study indicates that the performance of QCRs with elliptical electrodes is superior to that of traditional QCRs with circular electrodes. DA - 2011/4// PY - 2011/4// DO - 10.1088/1674-1056/20/4/047701 VL - 20 IS - 4 SP - SN - 1674-1056 KW - quartz crystal resonator KW - elliptical electrode KW - liquid sensing ER - TY - JOUR TI - Response to "Patient selection and activity planning guide for selective internal radiotherapy with Yttrium-90 resin microspheres." AU - Lau, W. Y. AU - Kennedy, A. S. AU - Kim, Y. H. AU - Lai, H. K. AU - Lee, R. C. AU - Leung, T. W. T. AU - Liu, C. S. AU - Salem, R. AU - Sangro, B. AU - Shuter, B. AU - Wang, S. C. AU - Wang, S. C. T2 - International Journal of Radiation Oncology, Biology, Physics DA - 2011/// PY - 2011/// VL - 80 IS - 4 SP - 1280-1281 ER - TY - CONF TI - Process control model for tube hydroforming AU - Kilonzo, O. C2 - 2011/// C3 - Proceedings of the ASME International Manufacturing Science and Engineering Conference 2010, vol 2 DA - 2011/// SP - 131-139 ER - TY - JOUR TI - Nonlinear vibration energy harvester using diamagnetic levitation AU - Liu, L. AU - Yuana, F. G. T2 - Applied Physics Letters DA - 2011/// PY - 2011/// VL - 98 IS - 20 ER - TY - JOUR TI - Modeling bidirectional transport of quantum dot nanoparticles in membrane nanotubes AU - Kuznetsov, A. V. T2 - MATHEMATICAL BIOSCIENCES AB - This paper develops a model of transport of quantum dot (QD) nanoparticles in membrane nanotubes (MNTs). It is assumed that QDs are transported inside intracellular organelles (called here nanoparticle-loaded vesicles, NLVs) that are propelled by either kinesin or dynein molecular motors while moving on microtubules (MTs). A vesicle may have both types of motors attached to it, but the motors are assumed to work in a cooperative fashion, meaning that at a given time the vesicle is moved by either kinesin or dynein motors. The motors are assumed not to work against each other, when one type of motors is pulling the vesicle, the other type is inactive. From time to time the motors may switch their roles: passive motors can become active motors and vice versa, resulting in the change of the vesicle’s direction of motion. It is further assumed that QDs can escape NLVs and become free QDs, which are then transported by diffusion. Free QDs can be internalized by NLVs. The effects of two possible types of MT orientation in MNTs are investigated: when all MTs have a uniform polarity orientation, with their plus-ends directed toward one of the cells connected by an MNT, and when MTs have a mixed polarity orientation, with half of MTs having their plus-ends directed toward one of the cells and the other half having their plus-ends directed toward the other cell. Computational results are presented for three cases. The first case is when organelles are as likely to be transported by kinesin motors as by dynein motors. The second case is when organelles are more likely to be transported by kinesin motors than by dynein motors, and the third case is when NLVs do not associate with dynein motors at all. DA - 2011/8// PY - 2011/8// DO - 10.1016/j.mbs.2011.04.008 VL - 232 IS - 2 SP - 101-109 SN - 0025-5564 KW - Tunneling nanotubes KW - Quantum dots KW - Nanoparticle transport KW - Microtubules KW - Molecular motors ER - TY - JOUR TI - Influence of Geometry on Starting Vortex and Ejector Performance AU - Zheng, Fei AU - Kuznetsov, Andrey V. AU - Roberts, William L. AU - Paxson, Daniel E. T2 - JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME AB - For many propulsion devices, the thrust may be augmented considerably by adding a passive ejector, and these devices are especially attractive for unsteady propulsion systems such as pulse detonation engines and pulsejets. Starting vortices from these unsteady devices dominate the flowfield and control to a great extent the level of the thrust augmentation. Therefore, it is of fundamental interest to understand the geometric influences on the starting vortex and how these manifest themselves in augmenter/ejector performance. An unsteady Reynolds averaged Navier–Stokes calculation was used to study the physics of a starting vortex generated at the exit of a pulsed jet and its interaction with an ejector. A 50 cm long pulsejet (typical hobby scale, allowing comparison with experimental data) with a circular exit was modeled as the resonant driving source and used to suggest an optimal ejector geometry and relative position. Computed limit-cycle thrust augmentation values compared favorably to experimentally obtained values for the same ejector geometries. Results suggest that the optimal diameter of the ejector is related to its relative position, dictated by the trajectory of the vortex toroid. The effect of the length of the ejector (which determines the natural frequency of the ejector, related to the acoustic processes occurring in the ejector) on overall performance was also investigated and shown to be less important than the ejector diameter. DA - 2011/5// PY - 2011/5// DO - 10.1115/1.4004082 VL - 133 IS - 5 SP - SN - 0098-2202 KW - ejector KW - pulsejet KW - thrust argumentation KW - vortex KW - constant volume combustion KW - numerical simulation ER - TY - JOUR TI - Flame Hysteresis Effects in Methane Jet Flames in Air-Coflow AU - Moore, N. J. AU - Terry, S. D. AU - Lyons, K. M. T2 - JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME AB - Presented are the results of experiments designed to investigate flame lift-off behavior in the hysteresis regime for low Reynolds number turbulent flows. The hysteresis regime refers to the situation where the jet flame has dual positions favorable to flame stabilization: attached and lifted. Typically, a jet flame is lifted off of a burner and stabilized at some downstream location at a pair of fuel and coflow velocities that is unique to a flame at that position. Since the direction from which that condition is arrived at is important, there is an inherent hysteretic behavior. To supplement previous research on hysteretic behavior in the presence of no coflow and low coflow velocities, the current research focuses on flames that are lifted and reattached at higher coflow velocities, where the flame behavior includes an unexpected downstream recession at low fuel velocities. Observations on the flame behavior related to nozzle exit velocity and coflow velocity are made using video imaging of flame sequences. The results show that a flame can stabilize at a location downstream despite a decrease in the local excess jet velocity and assist in determining the effect of coflow velocity magnitude on hysteretic behavior. These observations are of utility in designing maximum turndown burners in air coflow, especially for determining stability criteria in low fuel-flow applications. DA - 2011/6// PY - 2011/6// DO - 10.1115/1.4003806 VL - 133 IS - 2 SP - SN - 0195-0738 ER - TY - JOUR TI - Effect of cytoskeletal element degradation on merging of concentration waves in slow axonal transport AU - Kuznetsov, Andrey V. AU - Avramenko, Andriy A. AU - Blinov, Dmitry G. T2 - CENTRAL EUROPEAN JOURNAL OF PHYSICS AB - Abstract The aim of this paper is to investigate, by means of a numerical simulation, the effect of the half-life of cytoskeletal elements (CEs) on superposition of several waves representing concentrations of running, pausing, and off-track anterograde and retrograde CE populations. The waves can be induced by simultaneous microinjections of radiolabeled CEs in different locations in the vicinity of a neuron body; alternatively, the waves can be induced by microinjecting CEs at the same location several times, with a time interval between the injections. Since the waves spread out as they propagate downstream, unless their amplitude decreases too fast, they eventually superimpose. As a result of superposition and merging of several waves, for the case with a large half-life of CEs, a single wave is formed. For the case with a small half-life the waves vanish before they have enough time to merge. DA - 2011/8// PY - 2011/8// DO - 10.2478/s11534-010-0116-7 VL - 9 IS - 4 SP - 898-908 SN - 1895-1082 KW - molecular motors KW - neurons KW - axons KW - slow axonal transport KW - stop-and-go hypothesis KW - numerical modeling ER - TY - JOUR TI - Economic implications of imputation in agricultural economic data: Discussion AU - Ghosh, S. K. T2 - American Journal of Agricultural Economics DA - 2011/// PY - 2011/// VL - 93 IS - 2 SP - 627-628 ER - TY - JOUR TI - Deformation mechanisms of an Omega precipitate in a high-strength aluminum alloy subjected to high strain rates AU - Elkhodary, K. AU - Lee, W. AU - Sun, L. P. AU - Brenner, D. W. AU - Zikry, M. A. T2 - JOURNAL OF MATERIALS RESEARCH DA - 2011/2// PY - 2011/2// DO - 10.1557/jmr.2010.29 VL - 26 IS - 4 SP - 487-497 SN - 0884-2914 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-80054905299&partnerID=MN8TOARS ER - TY - JOUR TI - Defect-mediated ferromagnetism and controlled switching characteristics in ZnO AU - Mal, Siddhartha AU - Nori, Sudhakar AU - Narayan, Jagdish AU - Prater, John T. T2 - JOURNAL OF MATERIALS RESEARCH DA - 2011/5// PY - 2011/5// DO - 10.1557/jmr.2011.74 VL - 26 IS - 10 SP - 1298-1308 SN - 2044-5326 ER - TY - CONF TI - Database for real-time loading path prediction for tube hydroforming using multidimensional cubic spline interpolation AU - Ghosh, A. AU - Deshmukh, K. AU - Ngaile, G. AB - Tube Hydroforming (THF) is a metal-forming process that uses a pressurized fluid in place of a hard tool to plastically deform a given tube into a desired shape. In addition to the internal pressure, the tube material is fed axially toward the die cavity. This process has various applications in the automotive, aerospace, and bicycle industries. Accurate coordination of the fluid pressure and axial feed, collectively referred to as a loading path, is critical to THF. Workable loading paths are currently determined by trial and error, which can be time consuming. This paper discusses an innovative technique for developing an interactive, real-time database that would be able to predict loading paths for typical classes of THF products and hence, reduce the computational time required. By classifying most of the commercial THF parts into families, parameters such as material properties, part geometry, and tribological factors were simulated by category and stored in the database. Multidimensional cubic spline interpolation was implemented to enable an end user to request from the database a loading path for a wide range of conditions. Test results from the database for different THF families were shown to approximate the simulated results. In addition, by reducing the computation time, the use of interpolation techniques eliminates the need for carrying out multiple simulations for similar THF parts. C2 - 2011/// C3 - Proceedings of the ASME International Manufacturing Science and Engineering Conference 2010, vol 1 DA - 2011/// DO - 10.1115/msec2010-34099 SP - 609-618 ER - TY - JOUR TI - The properties of dry-spun carbon nanotube fibers and their interfacial shear strength in an epoxy composite AU - Deng, Fei AU - Lu, Weibang AU - Zhao, Haibo AU - Zhu, Yuntian AU - Kim, Byung-Sun AU - Chou, Tsu-Wei T2 - CARBON AB - Continuous fibers composed of carbon nanotubes have been adopted as reinforcements for polymeric composites. This paper presents several fundamental studies relevant to the mechanical behavior of CNT fibers, including fiber tensile behavior; in situ SEM observation of fiber deformation mechanisms; and fiber modulus, ultimate strength and fracture strain measurements. A modified Weibull strength distribution model that takes into account the flaw density variation with fiber diameter has been adopted for the statistical strength analysis. The interfacial shear strength between the carbon nanotube fiber and the epoxy matrix has been measured using fragmentation tests of single-fiber composites. DA - 2011/4// PY - 2011/4// DO - 10.1016/j.carbon.2010.12.061 VL - 49 IS - 5 SP - 1752-1757 SN - 1873-3891 ER - TY - JOUR TI - System-Level Airworthiness Tool AU - Burke, David A. AU - Hall, Charles E., Jr. AU - Cook, Stephen P. T2 - JOURNAL OF AIRCRAFT AB - One of the pillars of aviation safety is assuring sound engineering practices through airworthiness certification. As unmanned aircraft systems grow in popularity, the need for airworthiness standards and verification methods tailored for unmanned aircraft systems becomes critical.While airworthiness practices for large unmanned aircraft systemsmay be similar to manned aircraft, it is clear that small unmanned aircraft systems require a paradigm shift from the airworthiness practices of manned aircraft. Although small in comparison with manned aircraft these aircraft are not merely remote-controlled toys. Small unmanned aircraft systems may be complex aircraft flying in the national airspace system over populated areas for extended durations and beyond line of sight of the operators. A comprehensive systems engineering framework for certifying small unmanned aircraft systems at the system level is needed. This work presents a point-based tool that evaluates small unmanned aircraft systems by rewarding good engineering practices in design, analysis, and testing. The requirements scale with vehicle size and operational area, while allowing flexibility for new technologies and unique configurations. DA - 2011/// PY - 2011/// DO - 10.2514/1.c031022 VL - 48 IS - 3 SP - 777-785 SN - 0021-8669 ER - TY - JOUR TI - Optimal Drug-Aerosol Delivery to Predetermined Lung Sites AU - Kleinstreuer, Clement AU - Zhang, Zhe T2 - JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME AB - This review summarizes computer simulation methodologies of air-particle flow, results of drug-aerosol transport/deposition in models of the human respiratory system, as well as aspects of drug-aerosol targeting and associated inhalation devices. After a brief introduction to drug delivery systems in general, the required modeling and simulation steps for optimal drug-aerosol delivery in the lung are outlined. Starting with medical imaging and file conversion of patient-specific lung-airway morphologies, the air-particle transport phenomena are numerically solved for a representative inhalation flow rate of Qtotal=30 l/min. Focusing on microspheres and droplets, the complex airflow and particle dynamics, as well as the droplet heat and mass transfer are illustrated. With this foundation as the background, an overview of present inhaler devices is presented, followed by a discussion of the methodology and features of a new smart inhaler system (SIS). With the SIS, inhaled drug-aerosols can be directly delivered to any predetermined target area in the human lung. DA - 2011/1// PY - 2011/1// DO - 10.1115/1.4002224 VL - 133 IS - 1 SP - SN - 1528-8943 KW - subject-specific lung airways KW - air-particle flow KW - computer simulation results KW - inhaler devices KW - optimal drug-aerosol targeting KW - smart inhaler system ER - TY - JOUR TI - Note on the Heat Transfer of Flows over a Stretching Wall in Porous Media: Exact Solutions AU - Fang, Tiegang AU - Zhang, Ji T2 - TRANSPORT IN POROUS MEDIA DA - 2011/1// PY - 2011/1// DO - 10.1007/s11242-010-9640-6 VL - 86 IS - 2 SP - 609-614 SN - 1573-1634 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79953180000&partnerID=MN8TOARS KW - Similarity equation KW - Stretching surface KW - Analytical solution KW - Heat transfer KW - Porous medium ER - TY - JOUR TI - Non-oscillatory and oscillatory nanofluid bio-thermal convection in a horizontal layer of finite depth AU - Kuznetsov, A. V. T2 - EUROPEAN JOURNAL OF MECHANICS B-FLUIDS AB - The onset of bio-thermal convection in a suspension containing both nanoparticles and gyrotactic microorganisms, such as algae, is considered. Physical mechanisms responsible for the slip velocity between the nanoparticles and the base fluid, such as Brownian motion and thermophoresis, are included in the model. The suspension occupies a horizontal layer of finite depth. The lower boundary of the layer is assumed rigid while at the upper boundary both cases of either rigid or stress-free top boundaries are considered. A linear instability analysis is performed and the resulting eigenvalue problem is solved analytically using the Galerkin method. The cases of oscillatory and non-oscillatory convection are studied. Investigation of the dependence of the thermal Rayleigh number on the nanoparticle Rayleigh number and the bioconvection Rayleigh number is performed. The boundaries of oscillatory and non-oscillatory instability are established. The effect of nanoparticles can be either stabilizing or destabilizing, depending on whether the basic nanoparticle distribution is bottom-heavy or top-heavy. The effect of upswimming microorganisms is generally destabilizing. DA - 2011/// PY - 2011/// DO - 10.1016/j.euromechflu.2010.10.007 VL - 30 IS - 2 SP - 156-165 SN - 1873-7390 KW - Nanofluid bioconvection KW - Gyrotactic microorganisms KW - Brownian motion KW - Thermophoresis KW - Natural convection KW - Horizontal layer ER - TY - JOUR TI - Modeling Bidirectional Transport of New and Used Organelles in Fast Axonal Transport in Neurons AU - Kuznetsov, A. V. T2 - JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME AB - This paper develops a model for simulating transport of newly synthesized material from the neuron body toward the synapse of the axon as well as transport of misfolded and aggregated proteins back to the neuron body for recycling. The model demonstrates that motor-assisted transport, much similar to diffusion, can occur due to a simple concentration difference between the cell body and the synapse; organelles heading to the synapse do not need to attach preferably to plus-end-directed molecular motors, same as organelles heading to the neuron body for recycling do not need to attach preferably to minus-end-directed molecular motors. The underlying mechanics of molecular-motor-assisted transport is such that organelles would be transported to the right place even if new and used organelles had the same probability of attachment to plus-end-directed (and minus-end-directed) motors. It is also demonstrated that the axon with organelle traps and a region with a reversed microtubule polarity would support much smaller organelle fluxes of both new and used organelles than a healthy axon. The flux of organelles is shown to decrease as the width of organelle traps increases. DA - 2011/1// PY - 2011/1// DO - 10.1115/1.4002304 VL - 133 IS - 1 SP - SN - 0022-1481 KW - molecular motors KW - fast axonal transport KW - neurons KW - axons and dendrites KW - intracellular organelles KW - vesicle traps KW - traffic jams ER - TY - JOUR TI - Heat transfer of a generalized stretching/shrinking wall problem with convective boundary conditions AU - Yao, Shanshan AU - Fang, Tiegang AU - Zhong, Yongfang T2 - COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION AB - In this paper, we investigate the heat transfer of a viscous fluid flow over a stretching/shrinking sheet with a convective boundary condition. Based on the exact solutions of the momentum equations, which are valid for the whole Navier–Stokes equations, the energy equation ignoring viscous dissipation is solved exactly and the effects of the mass transfer parameter, the Prandtl number, and the wall stretching/shrinking parameter on the temperature profiles and wall heat flux are presented and discussed. The solution is given as an incomplete Gamma function. It is found the convective boundary conditions results in temperature slip at the wall and this temperature slip is greatly affected by the mass transfer parameter, the Prandtl number, and the wall stretching/shrinking parameters. The temperature profiles in the fluid are also quite different from the prescribed wall temperature cases. DA - 2011/2// PY - 2011/2// DO - 10.1016/j.cnsns.2010.05.028 VL - 16 IS - 2 SP - 752-760 SN - 1878-7274 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-77956060446&partnerID=MN8TOARS KW - Navier-Stokes equation KW - Similarity equation KW - Stretching surface KW - Shrinking sheet KW - Exact solution KW - Analytical solution KW - Heat transfer ER - TY - JOUR TI - Deposition of naphthalene and tetradecane vapors in models of the human respiratory system AU - Zhang, Zhe AU - Kleinstreuer, Clement T2 - INHALATION TOXICOLOGY AB - Jet-propulsion fuel (particularly JP-8) is currently being used worldwide, exposing especially Air Force personnel and people living near airfields to JP-8 vapors and aerosols during aircraft fueling, maintenance operations, and/or cold starts. JP-8 is a complex mixture containing >200, mostly toxic, aliphatic and aromatic hydrocarbon compounds of which tetradecane and naphthalene were chosen as two representative chemical markers for computer simulations. Thus, transport and deposition of naphthalene and tetradecane vapors have been simulated in models of the human respiratory system. The inspiratory deposition data were analyzed in terms of regional deposition fractions (DFs) and deposition enhancement factors (DEF). The vapor depositions are affected by vapor properties (e.g. diffusivity), airway geometric features, breathing patterns, inspiratory flow rates, as well as airway-wall absorption parameter. Specifically, the respiratory uptake of vapors is greatly influenced by the degree of airway-wall absorption. For example, being an almost insoluble species in the mucus layer, the deposition of tetradecane vapor is nearly zero in the extrathoracic and tracheobronchial (TB) airways, that is, the DF is <1%. The remaining vapors may penetrate further and deposit in the alveolar airways. The DF of tetradecane vapors during inhalation in the alveolar region can range from 7% to 24%, depending on breathing waveform, inhalation rate, and thickness of the mucus layer. In contrast, naphthalene vapor almost completely deposits in the extrathoracic and TB airways and hardly moves downstream and deposits in the respiratory zone. The DFs of naphthalene vapor in the extrathoracic airways from nasal/oral to trachea under normal breathing conditions (Q = 15–60 L/min) are about 12–34%, although they are about 66–87% in the TB airways. In addition, the variation of breathing routes (say, from nasal breathing to oral breathing) may influence the vapor deposition in the regions of nasal and oral cavities, nasopharynx and oropharynx, but hardly affects the deposition at and beyond the larynx. The different deposition patterns of naphthalene and tetradecane vapors in the human respiratory system may indicate different toxic and hence health effects of these toxic jet-fuel components. DA - 2011/1// PY - 2011/1// DO - 10.3109/08958378.2010.540261 VL - 23 IS - 1 SP - 44-57 SN - 1091-7691 KW - Computational analysis KW - toxic vapor deposition KW - lung airway model ER - TY - JOUR TI - Adaptive control design for uncertain polynomial nonlinear systems with parametric uncertainties AU - Zheng, Qian AU - Wu, Fen T2 - INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING AB - In this paper, we will develop an adaptive ℋ︁∞ control approach for a class of polynomial nonlinear systems with parametric uncertainties. Motivated by the dissipation theory and the vector projection technique, we propose a nonlinear adaptive ℋ︁∞ controller and its associated parameter adaptation law. The proposed adaptive control strategy is capable of identifying unknown parameter values quickly and minimizing the effect of estimation error. To further improve adaptive controlled performance, the Lyapunov function will be relaxed from quadratic to higher-order forms and the controller gains are generalized from constant to parameter-dependent. All of the synthesis conditions are formulated in the framework of polynomial/constant linear matrix inequalities and solvable using available software packages. Copyright © 2010 John Wiley & Sons, Ltd. DA - 2011/6// PY - 2011/6// DO - 10.1002/acs.1215 VL - 25 IS - 6 SP - 502-518 SN - 0890-6327 KW - uncertain nonlinear system KW - adaptive control KW - H-infinity performance KW - higher-order Lyapunov function KW - SOS programming ER - TY - JOUR TI - A Relation Between Near-Wall Particle-Hemodynamics and Onset of Thrombus Formation in Abdominal Aortic Aneurysms AU - Basciano, C. AU - Kleinstreuer, C. AU - Hyun, S. AU - Finol, E. A. T2 - ANNALS OF BIOMEDICAL ENGINEERING AB - A novel computational particle-hemodynamics analysis of key criteria for the onset of an intraluminal thrombus (ILT) in a patient-specific abdominal aortic aneurysm (AAA) is presented. The focus is on enhanced platelet and white blood cell residence times as well as their elevated surface-shear loads in near-wall regions of the AAA sac. The generalized results support the hypothesis that a patient's AAA geometry and associated particle-hemodynamics have the potential to entrap activated blood particles, which will play a role in the onset of ILT. Although the ILT history of only a single patient was considered, the modeling and simulation methodology provided allow for the development of an efficient computational tool to predict the onset of ILT formation in complex patient-specific cases. DA - 2011/7// PY - 2011/7// DO - 10.1007/s10439-011-0285-6 VL - 39 IS - 7 SP - 2010-2026 SN - 0090-6964 KW - Patient-specific AAA KW - Computational analysis KW - ILT onset criteria ER - TY - JOUR TI - The Cheng-Minkowycz problem for the double-diffusive natural convective boundary layer flow in a porous medium saturated by a nanofluid AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER AB - The paper presents an analytical treatment of double-diffusive nanofluid convection in a porous medium. The problem treated is natural convection past a vertical plate when the base fluid of the nanofluid is itself a binary fluid such as salty water. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis, while the Darcy model is used for the porous medium. In addition the thermal energy equations include regular diffusion and cross-diffusion terms. A similarity solution is presented. DA - 2011/1/15/ PY - 2011/1/15/ DO - 10.1016/j.ijheatmasstransfer.2010.09.034 VL - 54 IS - 1-3 SP - 374-378 SN - 1879-2189 KW - Nanofluid convection KW - Porous media KW - Brownian motion KW - Thermophoresis KW - Natural convection KW - Vertical plate ER - TY - JOUR TI - Solid support flame synthesis of 1-D and 3-D tungsten-oxide nanostructures AU - Merchan-Merchan, Wilson AU - Saveliev, Alexei V. AU - Jimenez, Walmy Cuello T2 - PROCEEDINGS OF THE COMBUSTION INSTITUTE AB - In this paper we report the growth of 1-D and 3-D tungsten-oxide nanostructures on tungsten wire probes inserted in an opposed-flow oxy-fuel flame. The probe diameter and oxygen content in the oxidizer were varied to study their influence on the growth of tungsten-oxide nanostructures. The introduction of a 1-mm diameter W probe into the flame environment with an oxidizer composition of 50%O2 + 50%N2, resulted in the formation of 1-D nanorods on the upper surface of the probe. The formation of triangular, rectangular, square, and cylindrical 3-D channels with completely hollow or semi-hollow morphology was achieved by reducing the probe diameter to 0.5 mm. Whereas, the increase of the O2 content to 100% and the employment of a 1-mm probe resulted in the growth of ribbon-like micron-sized structures. The lattice spacing of ∼0.38 nm measured for the 1-D W-oxides closely matches a monoclinic WO3 structure. X-ray photoelectron spectroscopy analysis revealed that the larger 3-D structures also consist of WO3 confirming that the chemical composition of the structures remains the same while varying the probe and flame parameters. The proposed growth mechanism states that the 3-D WO3 structures are formed through the lateral coalescence of 1-D W-oxide nanorods. DA - 2011/// PY - 2011/// DO - 10.1016/j.proci.2010.06.122 VL - 33 SP - 1899-1908 SN - 1873-2704 KW - Nanorods KW - Tungsten-oxide nanostructures KW - Counter-flow flame KW - Combustion KW - Synthesis ER - TY - JOUR TI - Optimal Targets for the Bank Shot in Men's Basketball AU - Silverberg, Larry M. AU - Tran, Chau M. AU - Adams, Taylor M. T2 - JOURNAL OF QUANTITATIVE ANALYSIS IN SPORTS AB - The purpose of this study was to gain an understanding of the bank shot and ultimately determine the optimal target points on the backboard for the bank shot in men’s basketball. The study used over one million three-dimensional simulations of basketball trajectories. Four launch variables were studied: launch height, launch speed, launch angle, and aim angle. The shooter’s statistical characteristics were prescribed to yield a 70 percent free throw when launching the ball seven feet above the ground with 3 Hz of back spin. We found that the shooter can select a bank shot over a direct shot with as much as a 20 percent advantage. The distribution over the court of preferences of the bank shot over the direct shot was determined. It was also shown that there is an aim line on the backboard independent of the shooter’s location on the court. We also found that at 3.326 inches behind the backboard, there exists a vertical axis that aids in finding the optimal target point on the backboard. The optimal target point is the crossing of the vertical axis and the aim line that is in the shooter’s line of sight. DA - 2011/1// PY - 2011/1// DO - 10.2202/1559-0410.1299 VL - 7 IS - 1 SP - SN - 1559-0410 KW - basketball KW - bank shot KW - optimal KW - backboard ER - TY - JOUR TI - Glycerol combustion and emissions AU - Bohon, Myles D. AU - Metzger, Brian A. AU - Linak, William P. AU - King, Charly J. AU - Roberts, William L. T2 - PROCEEDINGS OF THE COMBUSTION INSTITUTE AB - With the growing capacity in biodiesel production and the resulting glut of the glycerol by-product, there is increasing interest in finding alternative uses for crude glycerol. One option may be to burn it locally for combined process heat and power, replacing fossil fuels and improving the economics of biodiesel production. However, due to its low energy density, high viscosity, and high auto-ignition temperature, glycerol is difficult to burn. Additionally, the composition of the glycerol by-product can change dramatically depending upon the biodiesel feedstock (e.g., vegetable oils or rendered animal fats), the catalyst used, and the degree of post-reaction cleanup (e.g., acidulation and demethylization). This paper reports the results of experiments to (1) develop a prototype high-swirl refractory burner designed for retrofit applications in commercial-scale fire-tube package boilers, and (2) provide an initial characterization of emissions generated during combustion of crude glycerol in a laboratory-scale moderate-swirl refractory-lined furnace. We report a range of emissions measurements, including nitrogen oxides, total hydrocarbons, and particle mass for two grades of crude glycerol (methylated and demethylated) and compare these to No. 2 fuel oil and propane. We also present preliminary data on the emissions of select carbonyls (by cartridge DNPH). Results indicate that a properly designed refractory burner can provide the thermal environment to effectively combust glycerol, but that high particulate emissions due to residual catalysts are likely to be an issue for crude glycerol combustion. DA - 2011/// PY - 2011/// DO - 10.1016/j.proci.2010.06.154 VL - 33 SP - 2717-2724 SN - 1540-7489 KW - Glycerol combustion KW - Emission characterization KW - Bio-fuels KW - Burner development KW - Waste fuels ER - TY - JOUR TI - Gas and solid phase temperature measurements of porous media combustion AU - Zheng, Chenghang AU - Cheng, Leming AU - Saveliev, Alexei AU - Luo, Zhongyang AU - Cen, Kefa T2 - PROCEEDINGS OF THE COMBUSTION INSTITUTE AB - This work introduces a novel method to determine gas and solid phase temperature profiles in a packed bed porous media combustor. Bare and coated thermocouple junctions were installed in the centerline of the porous combustor and the temperatures of solid phase and bare junctions were recorded simultaneously. Gas phase temperature was obtained considering the influence of flow velocity around the hot junction and the average solid temperature of the hot junction surroundings using the empirical formula for the Nusselt number based on the energy balance for the hot junction. Results show that the junction placement has a lot of influence on hot junction temperature measurement, which leads to a large uncertainty of gas temperature correction. The preheating procedure is used to reduce the effect of the junction placement. It is found that the flow velocity over junction, average solid temperature of the junction surroundings and empirical formula for the Nu number have limited influence on the gas phase temperature correction due to opposite compensating effects of these factors. The temperature profiles measured by thermocouples provide a complete temperature distribution in porous combustor, while a time-based method offers detail gas and solid temperature distributions near the reaction zone. Temperature profiles recorded for solid and gas phases vary for combustion waves propagating upstream and downstream. For all recorded regimes, the temperature gap between gas and solid has maximum and minimum points in the reaction and preheating zones, respectively. DA - 2011/// PY - 2011/// DO - 10.1016/j.proci.2010.05.037 VL - 33 SP - 3301-3308 SN - 1540-7489 KW - Porous media KW - Premixed combustion KW - Temperature measurement KW - Temperature correction ER - TY - JOUR TI - Fatigue crack fusion in thin-sheet aluminum alloys AA7075-T6 using low-speed fiber laser welding AU - Tu, J. F. AU - Paleocrassas, A. G. T2 - Journal of Materials Processing Technology AB - Reinforcing cracked aluminum structures with composite patches have been recognized as an efficient and economical method to extend the service life of cracked aluminum components. To further enhance the effectiveness of composite patches, it is envisioned that the crack can be first fused by laser welding to remove the high stress concentration at the crack front before applying the composite patch. In this paper, the feasibility of the envisioned fusion repair is investigated. A systematic approach for the fusion process design is proposed to overcome challenges related to alloy strength recovery, crack tracing, focusing position, welding speed, plate flatness, shielding gas pressure, thin-sheet factors, and skewed cracks. A thick-sheet, partial penetration model is first used to determine the starting point of laser welding conditions. A systematic approach to transfer the thick-sheet condition to successful thin-sheet welding is then presented. Based on successfully fused crack samples of AA 7075-T6, the ultimate tensile strength tests show that in average 74% of the alloy's original strength was recovered for a single-pass repair and 68% for a double-pass repair and the results are highly repeatable. It should be clear to see the benefit of the crack fusion because without crack fusion, the composite patch is bonded to a part with zero UTS at the crack region and with a high stress intensity factor at the crack front. DA - 2011/// PY - 2011/// DO - 10.1016/j.jmatprotec.2010.09.001 VL - 211 IS - 1 SP - 95-102 ER - TY - JOUR TI - Controlled 3D Buckling of Silicon Nanowires for Stretchable Electronics AU - Xu, Feng AU - Lu, Wei AU - Zhu, Yong T2 - ACS NANO AB - Silicon (Si) nanowire (NW) coils were fabricated on elastomeric substrates by a controlled buckling process. Si NWs were first transferred onto prestrained and ultraviolet/ozone (UVO)-treated poly(dimethylsiloxane) (PDMS) substrates and buckled upon release of the prestrain. Two buckling modes (the in-plane wavy mode and the three-dimensional coiled mode) were found; a transition between them was achieved by controlling the UVO treatment of PDMS. Structural characterization revealed that the NW coils were oval-shaped. The oval-shaped NW coils exhibited very large stretchability up to the failure strain of PDMS (∼104% in our study). Such a large stretchability relies on the effectiveness of the coil shape in mitigating the maximum local strain, with a mechanics that is similar to the motion of a coil spring. Single NW devices based on coiled NWs were demonstrated with a nearly constant electrical response in a large strain range. In addition to the wavy shape, the coil shape represents an effective architecture in accommodating large tension, compression, bending, and twist, which may find important applications for stretchable electronics and other stretchable technologies. DA - 2011/1// PY - 2011/1// DO - 10.1021/nn103189z VL - 5 IS - 1 SP - 672-678 SN - 1936-0851 KW - silicon nanowire KW - buckling KW - coil KW - stretchable electronics KW - local strain ER - TY - JOUR TI - Ultra-low-emission steam boiler constituted of reciprocal flow porous burner AU - Barcellos, William M. AU - Souza, Luis Carlos E. O. AU - Saveliev, Alexei V. AU - Kennedy, Lawrence A. T2 - EXPERIMENTAL THERMAL AND FLUID SCIENCE AB - This experimental study examined a low-emission steam boiler in which the filtration combustion technology was employed. This new boiler concept is consisted of a reciprocal flow porous burner, in which a combustion wave propagates along the reactor length. The boiler’s burner is filled up by an inert porous material, which leads to a stable burning of ultra-lean fuel/air mixtures, operating below flammability limits of conventional burners. In reciprocal filtration combustion, the reaction zone travels back and forth along the length of the burner, maintaining a typical trapezoidal temperature distribution favorable to the energy extraction. Embedding heat exchangers into the ends of the porous bed results in an alternative low-emission high-efficiency boiler. The heat re-circulation inside the porous matrix and the low degree of thermal non-equilibrium between the gas and the solid phases result in ultra-low levels of CO and NOx. Over an equivalence ratio range from 0.20 to 1.0 and a gas flow velocity range from 0.2 to 0.6 m/s, burning the technical methane, the developed prototype has reached efficiencies superior to 90% and NOx and CO emission levels lower than 1.0 and 0.5 ppm, respectively. DA - 2011/4// PY - 2011/4// DO - 10.1016/j.expthermflusci.2010.11.005 VL - 35 IS - 3 SP - 570-580 SN - 1879-2286 KW - Filtration combustion KW - Reciprocal flow burner KW - Ultra-low NOx and CO emissions ER - TY - JOUR TI - The Onset of Convection in a Strongly Heterogeneous Porous Medium with Transient Temperature Profile AU - Kuznetsov, A. V. AU - Nield, D. A. AU - Simmons, Craig T. T2 - TRANSPORT IN POROUS MEDIA DA - 2011/2// PY - 2011/2// DO - 10.1007/s11242-010-9657-x VL - 86 IS - 3 SP - 851-865 SN - 1573-1634 KW - Heterogeneity KW - Transient heating KW - Thermal instability KW - Horizontal layer ER - TY - JOUR TI - Strain-Release Assembly of Nanowires on Stretchable Substrates AU - Xu, Feng AU - Durham, John W., III AU - Wiley, Benjamin J. AU - Zhu, Yong T2 - ACS NANO AB - A simple yet effective method for assembly of highly aligned nanowires (NWs) on stretchable substrates is reported. In this method, NWs were first transferred to a strained stretchable substrate. After the strain was released, the NWs aligned in the transverse direction and the area coverage of the NWs on the substrate increased. This method can be applied to any NWs deposited on a stretchable film and can be repeated multiple times to increase the alignment and density of the NWs. For silver (Ag) and silicon (Si) NWs on poly(dimethylsiloxane) (PDMS) substrates, the probability of NW alignment increased from 29% to 90% for Ag NWs, and from 25% to 88% for Si NWs after two assembly steps; the density increased by 60% and 75% for the Ag and Si NWs, respectively. The large-strain elasticity of the substrate and the static friction between the NWs and the substrate play key roles in this assembly method. We find that a model that takes into account the volume incompressibility of PDMS reliably predicts the degree of NW alignment and NW density. The utility of this assembly method was demonstrated by fabricating a strain sensor array composed of aligned Si NWs on a PDMS substrate, with a device yield of 95%. DA - 2011/2// PY - 2011/2// DO - 10.1021/nn103183d VL - 5 IS - 2 SP - 1556-1563 SN - 1936-086X KW - nanowire KW - assembly KW - alignment KW - strain KW - static friction ER - TY - JOUR TI - Method of modelling intracellular transport in branching neurites: application to axons and dendrites of Drosophila sensory neurons AU - Kuznetsov, A. V. T2 - COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING AB - Abstract This paper develops a method of calculating the transport of intracellular organelles in neurons with branching neurites which is based on the Smith–Simmons equations of motor-assisted transport. The method is aimed at understanding the effects of microtubule (MT) polarity orientation in branching neurites on transport of organelles at the fundamental level. The method is applied to calculating the organelle transport in axons and dendrites of Drosophila neurons, using the map of MT orientation in such neurons developed by Stone et al. (Mol Biol Cell 19:4122–4129, 2008). The proximal dendrite is assumed to branch and form two distal dendrites. Two different MT polarity arrangements in a proximal dendrite are considered, and implications of these MT arrangements on organelle transport are analysed. It is demonstrated that the MT arrangement found in Drosophila dendrites (MTs have their minus ends out in a proximal dendrite) results in much more efficient motor-driven transport than the structure with a mixed MT orientation in proximal dendrites. Keywords: mathematical modellingmolecular motorsmicrotubulesfast axonal transportneuronsaxons and dendrites DA - 2011/// PY - 2011/// DO - 10.1080/10255841003664727 VL - 14 IS - 3 SP - 239-251 SN - 1476-8259 KW - mathematical modelling KW - molecular motors KW - microtubules KW - fast axonal transport KW - neurons KW - axons and dendrites ER - TY - JOUR TI - Low sooting combustion of narrow-angle wall-guided sprays in an HSDI diesel engine with retarded injection timings AU - Fang, Tiegang AU - Lee, Chia-fon F. T2 - FUEL AB - An optically accessible single-cylinder high speed direct-injection (HSDI) diesel engine was used to investigate the spray and combustion processes with narrow-angle wall-guided sprays. Influences of injection timings and injection pressure on combustion characteristics and emissions were studied. In-cylinder pressure was measured and used for heat release analysis. High-speed spray and combustion videos were captured. NOx emissions were measured in the exhaust pipe. With significantly retarded post-top dead center (TDC) injections, smokeless combustion was achieved for wall-guided diesel spray. Premixed-combustion was observed from the heat release rates and the combustion images. Natural luminosity was found significantly lower for smokeless combustion case. However, NOx emissions were higher for the low sooting combustion cases. In addition, retarding injection timing lead to more complete combustion with more heat released from the same amount of fuel. Spray images revealed significant fuel impingement for all the conditions and the spray development was controlled and guided by the piston bowl curvature. NOx and natural luminosity trade-off trend was observed for these conditions. However, quite different from conventional diesel combustion, retarding post-TDC injection timing leads to lower natural luminosity and higher NOx emissions for narrow-angle wall-guided spray combustion. For the smokeless combustion case under moderate operating load, both homogeneous combustion and low-luminosity pool fires were observed during combustion process and the latter was due to fuel-piston impingement. The findings in this study could be used to solve the smoke issues associated with narrow-angle injection technique under high load conditions. With narrow-angle injectors, ignition could occur for significantly retarded post-TDC injections, which provides a unique mixing approach for diesel engines. DA - 2011/4// PY - 2011/4// DO - 10.1016/j.fuel.2010.12.031 VL - 90 IS - 4 SP - 1449-1456 SN - 0016-2361 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-79951942114&partnerID=MN8TOARS KW - Diesel combustion KW - Wall-guided spray KW - Natural luminosity KW - Mie-scattering KW - HCCI combustion ER - TY - JOUR TI - Intra-arterial brachytherapy of hepatic malignancies: Watch the flow AU - Morgan, B. AU - Kennedy, A. S. AU - Lewington, V. AU - Jones, B. AU - Sharma, R. A. T2 - Nature Reviews. Clinical Oncology DA - 2011/// PY - 2011/// VL - 8 IS - 2 SP - 115-120 ER - TY - JOUR TI - Database for real-time loading path prediction for tube hydroforming using multidimensional cubic spline interpolation AU - Ghosh, Angshuman AU - Deshmukh, Karan AU - Ngaile, Gracious T2 - JOURNAL OF MATERIALS PROCESSING TECHNOLOGY AB - Tube hydroforming (THF) is a metal-forming process that uses a pressurized fluid in place of a hard tool to plastically deform a given tube into a desired shape. In addition to the internal pressure, the tube material is fed axially toward the die cavity. This process has various applications in the automotive, aerospace, and bicycle industries. Accurate coordination of the fluid pressure and axial feed, collectively referred to as a loading path, is critical to THF. Workable loading paths are currently determined by trial and error, which can be time consuming. This study discusses an innovative technique for developing an interactive, real-time database that would be able to predict loading paths for many THF components and hence reduce the computational time required. By classifying most of the commercial THF parts into families, parameters such as material properties, part geometry, and tribological factors were simulated by category and stored in the database. Multidimensional cubic spline interpolation was implemented to enable an end user to request from the database a loading path for a wide range of conditions. Test results from the database for different THF families were shown to approximate the simulated results. In addition to reducing the computation time, the use of interpolation techniques eliminates the need for carrying out multiple simulations for similar THF parts. DA - 2011/1/1/ PY - 2011/1/1/ DO - 10.1016/j.jmatprotec.2010.09.012 VL - 211 IS - 1 SP - 150-166 SN - 0924-0136 KW - Tube hydroforming KW - Loading path KW - Interpolation ER - TY - JOUR TI - A Parallel, Reconstructed Discontinuous Galerkin Method for the Compressible Flows on Arbitrary Grids AU - Luo, Hong AU - Luo, Luqing AU - Ali, Amjad AU - Nourgaliev, Robert AU - Cai, Chunpei T2 - COMMUNICATIONS IN COMPUTATIONAL PHYSICS AB - Abstract A reconstruction-based discontinuous Galerkin method is presented for the solution of the compressible Navier-Stokes equations on arbitrary grids. In this method, an in-cell reconstruction is used to obtain a higher-order polynomial representation of the underlying discontinuous Galerkin polynomial solution and an inter-cell reconstruction is used to obtain a continuous polynomial solution on the union of two neighboring, interface-sharing cells. The in-cell reconstruction is designed to enhance the accuracy of the discontinuous Galerkin method by increasing the order of the underlying polynomial solution. The inter-cell reconstruction is devised to remove an interface discontinuity of the solution and its derivatives and thus to provide a simple, accurate, consistent, and robust approximation to the viscous and heat fluxes in the Navier-Stokes equations. A parallel strategy is also devised for the resulting reconstruction discontinuous Galerkin method, which is based on domain partitioning and Single Program Multiple Data (SPMD) parallel programming model. The RDG method is used to compute a variety of compressible flow problems on arbitrary meshes to demonstrate its accuracy, efficiency, robustness, and versatility. The numerical results demonstrate that this RDG method is third-order accurate at a cost slightly higher than its underlying second-order DG method, at the same time providing a better performance than the third order DG method, in terms of both computing costs and storage requirements. DA - 2011/2// PY - 2011/2// DO - 10.4208/cicp.070210.020610a VL - 9 IS - 2 SP - 363-389 SN - 1991-7120 KW - Discontinuous Galerkin methods KW - least-squares reconstruction methods KW - compressible Navier-Stokes equations ER - TY - JOUR TI - Polymer optical fiber sensors-a review AU - Peters, Kara T2 - SMART MATERIALS AND STRUCTURES AB - Polymer optical fibers (POFs) have significant advantages for many sensing applications, including high elastic strain limits, high fracture toughness, high flexibility in bending, high sensitivity to strain and potential negative thermo-optic coefficients. The recent emergence of single-mode POFs has enabled high precision, large deformation optical fiber sensors. This article describes recent advances in both multi-mode and single-mode POF based strain and temperature sensors. The mechanical and optical properties of POFs relevant to strain and temperature applications are first summarized. POFs considered include multi-mode POFs, solid core single-mode POFs and microstructured single-mode POFs. Practical methods for applying POF sensors, including connecting and embedding sensors in structural materials, are also described. Recent demonstrations of multi-mode POF sensors in structural applications based on new interrogation methods, including backscattering and time-of-flight measurements, are outlined. The phase–displacement relation of a single-mode POF undergoing large deformation is presented to build a fundamental understanding of the response of single-mode POF sensors. Finally, this article highlights recent single-mode POF based sensors based on polymer fiber Bragg gratings and microstructured POFs. DA - 2011/1// PY - 2011/1// DO - 10.1088/0964-1726/20/1/013002 VL - 20 IS - 1 SP - SN - 1361-665X ER - TY - JOUR TI - One-dimensional turbulence model simulations of autoignition of hydrogen/carbon monoxide fuel mixtures in a turbulent jet AU - Gupta, Kamlesh G. AU - Echekki, Tarek T2 - COMBUSTION AND FLAME AB - The autoignition of hydrogen/carbon monoxide in a turbulent jet with preheated co-flow air is studied using the one-dimensional turbulence (ODT) model. The simulations are performed at atmospheric pressure based on varying the jet Reynolds number and the oxidizer preheat temperature for two compositions corresponding to varying the ratios of H2 and CO in the fuel stream. Moreover, simulations for homogeneous autoignition are implemented for similar mixture conditions for comparison with the turbulent jet results. The results identify the key effects of differential diffusion and turbulence on the onset and eventual progress of autoignition in the turbulent jets. The differential diffusion of hydrogen fuels results in a reduction of the ignition delay relative to similar conditions of homogeneous autoignition. Turbulence may play an important role in delaying ignition at high-turbulence conditions, a process countered by the differential diffusion of hydrogen relative to carbon monoxide; however, when ignition is established, turbulence enhances the overall rates of combustion of the non-premixed flame downstream of the ignition point. DA - 2011/2// PY - 2011/2// DO - 10.1016/j.combustflame.2010.09.003 VL - 158 IS - 2 SP - 327-344 SN - 1556-2921 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-78650171975&partnerID=MN8TOARS KW - Turbulent flames KW - Autoignition KW - The one-dimensional turbulence model KW - Differential diffusion ER - TY - JOUR TI - Atmospheric Plasma Treatment of Pre-Electrospinning Polymer Solution: A Feasible Method to Improve Electrospinnability AU - Shi, Quan AU - Vitchuli, Narendiran AU - Nowak, Joshua AU - Lin, Zhan AU - Guo, Bingkun AU - McCord, Marian AU - Bourham, Mohamed AU - Zhang, Xiangwu T2 - JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS AB - Abstract The electrospinnability of polyethylene oxide (PEO) was manipulated by atmospheric plasma treatment of pre‐electrospinning solutions. Conductivity, viscosity, and surface tension of PEO solutions increased after plasma treatment, and the plasma effect remained longer when the solution concentrate increased. Both untreated and treated solutions were then electrospun, and the morphology of the resultant nanofibers was observed by SEM. Atmospheric plasma treatment improved the electrospinnability of PEO solutions and led to less beads and finer diameter distribution in the resultant nanofibers. Additionally, plasma treatment of the pre‐electrospinning solutions affected the crystal structure of resultant nanofibers. These results suggest that atmospheric plasma treatment is a feasible approach to improve the electrospinnability of polymer solutions and can used to control the structure of electrospun nanofibers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 DA - 2011/1/15/ PY - 2011/1/15/ DO - 10.1002/polb.22157 VL - 49 IS - 2 SP - 115-122 SN - 1099-0488 KW - atmospheric plasma KW - electrospinning KW - fibers KW - melting point KW - nanofibers KW - poly(ethylene oxide) ER - TY - JOUR TI - A Novel Shape Memory Alloy Annuloplasty Ring for Minimally Invasive Surgery: Design, Fabrication, and Evaluation AU - Purser, Molly F. AU - Richards, Andrew L. AU - Cook, Richard C. AU - Osborne, Jason A. AU - Cormier, Denis R. AU - Buckner, Gregory D. T2 - ANNALS OF BIOMEDICAL ENGINEERING AB - A novel annuloplasty ring with a shape memory alloy core has been developed to facilitate minimally invasive mitral valve repair. In its activated (austenitic) phase, this prototype ring has comparable mechanical properties to commercial semi-rigid rings. In its pre-activated (martensitic) phase, this ring is flexible enough to be introduced through an 8-mm trocar and easily manipulated with robotic instruments within the confines of a left atrial model. The core is constructed of 0.50 mm diameter NiTi, which is maintained below its martensitic transition temperature (24 °C) during deployment and suturing. After suturing, the ring is heated above its austenitic transition temperature (37 °C, normal human body temperature) enabling the NiTi core to attain its optimal geometry and stiffness characteristics indefinitely. This article summarizes the design, fabrication, and evaluation of this prototype ring. Experimental results suggest that the NiTi core ring could be a viable alternative to flexible bands in robot-assisted minimally invasive mitral valve repair. DA - 2011/1// PY - 2011/1// DO - 10.1007/s10439-010-0126-z VL - 39 IS - 1 SP - 367-377 SN - 1573-9686 KW - Mitral valve repair KW - Robotic surgery KW - Annuloplasty ring KW - Nitinol ER - TY - JOUR TI - Special Issue on Heat and Mass Transfer in Biosystems AU - Vadasz, Peter AU - Kuznetsov, Andrey V. T2 - JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME AB - The involvement of the heat transfer community in the research related to heat and mass transfer in biosystems increases rapidly and covers a wide variety of applications. While the past involved mainly topics of cryogenics and other related fields the current involvement is substantially wider and covers diverse biological fields and applications. The present special issue dedicated to heat and mass transfer in biosystems captures only a portion of this wide topical potential for biosystems research. The objective of this special issue is to report the state of the art on some of the research conducted in this field and motivate the heat transfer community, which is uniquely qualified to make a valuable contribution in providing fundamental understanding of transport of heat, mass, and momentum occurring in biological and biologically inspired systems, to become more involved in this field of research. In particular, applying the engineering way of thinking can be especially useful in developing the fundamental understanding, the governing principles, mechanistic explanations, and predictive modeling for functioning of biological systems. Application of the engineering point of view (through identification, formulation, and solution to bioengineering problems as well as designing machines and systems based on fundamental conservation laws) can usefully complement many biological research efforts and lead to new breakthroughs in this area. Among the topics covered in this special issue are targeted drug delivery, heat generation in nanoparticles with potential application to cancer treatment, tissue engineering by using irreversible electroporation to minimize tissue damage due to Joules heating, temperature distribution in cryosurgery, facilitating transdermal drug delivery via skin electroporation, modeling of microorganism growth including the lag phase, human eye response to thermal disturbances, modeling of bioheat transfer, formation of organelle traps in an axon providing a mechanistic explanation of the onset of Alzheimers disease, the use of micro-cantilever biosensors for detection of microorganisms, and the application of the constructal theory to biophysical systems.The issue starts with a general topic of applications of the constructal law (this law postulates that the direction of systems evolution is such that it obtains easier access to currents that flow through it) in a paper by Bejan and Lorente. The paper considers applications of the constructal law to various biophysical systems. A novel method of targeted drug delivery (of an anti-cancer drug for example) to lung sites via utilization of a new smart inhaler system is then introduced by Kleinstreuer and Zhang. A correlation between the heat generation rate in nanoparticles (due to applying an alternative current at a specific frequency to a water-cooled coil, which thus generates an alternating magnetic field) and the density of the micro-CT images is presented by Attaluri et al. This correlation is important for understanding basic issues of using nanoparticles for cancer treatment. Evidence that parameters for irreversible electroporation can be chosen in such a way that minimizes the damage due to Joule heating to the tissue is demonstrated with the help of numerical modeling by Phillips et al.. Shitzer presents a comprehensive review of analytical and numerical studies on temperature distributions in cryosurgery; in vitro and in vivo experimental data used for validating these results are also discussed. The situations involving both surface application as well as insertion of cryoprobes are analyzed. Results of analytical modeling of biological media or heat management devices with a nonuniform geometry as a combination of convergent, uniform, and/or divergent configurations is presented by Mahjoob and Vafai. Kuznetsov develops a new model for the formation of organelle traps in an axon with regions where microtubule polarity has been reversed by the formation of microtubule swirls. Biological data link the formation of such microtubule swirl regions to traffic jams in axons that lead to various neurological disorders, such as Alzheimers disease. The developed theory demonstrates how the reversal of microtubule polarity results in the formation of organelle traps for both newly synthesized and used organelles, thus providing a mechanistic explanation of the onset of Alzheimers disease. Vadasz and Vadasz present a generic theoretical mechanism for microbial growth, including the lag phase that reveals the profound impact of the metabolic process on the growth. The theoretical model provides excellent matching to experimental data of microbial growth. Systematical reviews of four existing models of a human eye response to thermal disturbances are presented by Shafahi and Vafai. The physical phenomena included in the models, strengths and limitations of the models in simulating eye thermal response to various ambient conditions, blood temperature, and various thermophysical and biological parameters are discussed. Different models of bioheat transfer are introduced by Wang and Fan. Different approaches for obtaining constitutive relations for the heat flux, including Fourier law, Cattaneo−Vernotte theory, and dual-phase lagging theory are presented. The strengths and limitations of various bioheat models, including Pennes, Wulff, Klinger, Chen and Holmes, dual-phase-lagging, as well as some other models are discussed. A comprehensive overview of existing mathematical models of skin electroporation, which is a promising technique of causing a structural alternation in the uppermost skin layer, the stratum corneum, with the aim of facilitating transdermal drug delivery is presented by Becker. Special attention is given to developing a thermodynamic model of electroporation, which is based on the idea that a large current density through the pore causes lipids composing the stratum corneum to undergo a phase transition. Application of microcantilever biosensors for detection of microorganism is investigated experimentally by Tzeng et al. They explored the use of specific carbohydrate receptors for the functionalization of nanoparticles and demonstrated their binding specificities and their ability to mediate aggregations of targeted bacteria.We would like to extend our special thanks to the authors of the special issue and to the reviewers for helping to elevate the quality of the papers. We are also thankful to the Editor, Professor Yogesh Jaluria, for providing this forum to discuss this emerging field. Special thanks to the Editorial Assistant, Shefali Patel, for the help in organizing this special issue. DA - 2011/1// PY - 2011/1// DO - 10.1115/1.4002222 VL - 133 IS - 1 SP - SN - 0022-1481 ER - TY - JOUR TI - Multiobjective fault detection and isolation for flexible air-breathing hypersonic vehicle AU - Cai, Xuejing AU - Wu, Fen T2 - JOURNAL OF SYSTEMS ENGINEERING AND ELECTRONICS AB - An application of the multiobjective fault detection and isolation (FDI) approach to an air-breathing hypersonic vehicle (HSV) longitudinal dynamics subject to disturbances is presented. Maintaining sustainable and safe flight of HSV is a challenging task due to its strong coupling effects, variable operating condi- tions and possible failures of system components. A common type of system faults for aircraft including HSV is the loss of effective- ness of its actuators and sensors. To detect and isolate multiple actuator/sensor failures, a faulty linear parameter-varying (LPV) model of HSV is derived by converting actuator/system compo- nent faults into equivalent sensor faults. Then a bank of LPV FDI observers is designed to track individual fault with minimum error and suppress the effects of disturbances and other fault signals. The simulation results based on the nonlinear flexible HSV model and a nominal LPV controller demonstrate the effectiveness of the fault estimation technique for HSV. DA - 2011/2// PY - 2011/2// DO - 10.3969/j.issn.1004-4132.2011.01.006 VL - 22 IS - 1 SP - 52-62 SN - 1004-4132 KW - fault detection and isolation (FDI) KW - hypersonic vehicle (HSV) KW - actuator and sensor faults KW - multiobjective optimization ER - TY - JOUR TI - Influence of ultrasonic vibration on micro-extrusion AU - Bunget, Cristina AU - Ngaile, Gracious T2 - ULTRASONICS AB - Micro-forming is a miniaturization technology with great potential for high productivity. Some technical challenges, however, need to be addressed before micro-forming becomes a commercially viable manufacturing process. These challenges include severe tribological conditions, difficulty in achieving desired tolerances, and short tool-life due to inability of available die materials to withstand the forces exerted on miniature dies and punches. Some of these problems can be mitigated using ultrasonic technology. The principal objectives of this work were to investigate the possibility of applying ultrasonic vibrations in the micro-forming process, to design a set of tooling for ultrasonic micro-extrusion and to observe experimentally how ultrasonic oscillations influences the forming load and the surface finish. The test results showed a significant drop on the forming load when ultrasonic vibrations were imposed, and also a significant improvement in the surface of the micro-formed parts. Based on the preliminary test results, the study demonstrated high potential for using ultrasonic oscillations as a way to overcome the difficulties brought by the miniaturization. DA - 2011/7// PY - 2011/7// DO - 10.1016/j.ultras.2011.01.001 VL - 51 IS - 5 SP - 606-616 SN - 1874-9968 KW - Ultrasonic forming KW - Micro-forming KW - Micro-extrusion KW - Tribology ER - TY - JOUR TI - Analytical solution of equations describing slow axonal transport based on the stop-and-go hypothesis AU - Kuznetsov, Andrey V. T2 - CENTRAL EUROPEAN JOURNAL OF PHYSICS AB - Abstract This paper presents an analytical solution for slow axonal transport in an axon. The governing equations for slow axonal transport are based on the stop-and-go hypothesis which assumes that organelles alternate between short periods of rapid movement on microtubules (MTs), short on-track pauses, and prolonged off-track pauses, when they temporarily disengage from MTs. The model includes six kinetic states for organelles: two for off-track organelles (anterograde and retrograde), two for running organelles, and two for pausing organelles. An analytical solution is obtained for a steady-state situation. To obtain the analytical solution, the governing equations are uncoupled by using a perturbation method. The solution is validated by comparing it with a high-accuracy numerical solution. Results are presented for neurofilaments (NFs), which are characterized by small diffusivity, and for tubulin oligomers, which are characterized by large diffusivity. The difference in transport modes between these two types of organelles in a short axon is discussed. A comparison between zero-order and first-order approximations makes it possible to obtain a physical insight into the effects of organelle reversals (when organelles change the type of a molecular motor they are attached to, an anterograde versus retrograde motor). DA - 2011/6// PY - 2011/6// DO - 10.2478/s11534-010-0066-0 VL - 9 IS - 3 SP - 662-673 SN - 1895-1082 KW - molecular motors KW - neurons KW - axons KW - slow axonal transport KW - stop-and-go hypothesis KW - analytical solution ER - TY - JOUR TI - A Facile Approach to Fabricate Porous Nylon 6 Nanofibers Using Silica Nanotemplate AU - Shi, Quan AU - Vitchuli, Narendiran AU - Ji, Liwen AU - Nowak, Joshua AU - McCord, Marian AU - Bourham, Mohamed AU - Zhang, Xiangwu T2 - JOURNAL OF APPLIED POLYMER SCIENCE AB - Abstract Porous Nylon 6 nanofibers were prepared using silica nanoparticles as the template. Firstly, Nylon 6/silica composite nanofibers were prepared as precursors by electrospinning Nylon 6 solutions containing different contents of silica nanoparticles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the surface morphology and the inner structure of composite nanofibers; where it was found that silica nanoparticles were distributed both inside and on the surface of nanofibers. Analytical techniques [Fourier transform infrared (FTIR), differential scanning calorimetry, thermal gravimetric analysis (TGA), and wide‐angle X‐ray diffraction) were used to study the structure and properties of these composite nanofibers. The glass transition, melting, and crystallization processes of the fibers were affected by the addition of silica nanoparticles. Secondly, porous Nylon 6 nanofibers were obtained by removing silica nanoparticles via hydrofluoric acid treatment. The removal of silica nanoparticles was confirmed using FTIR and TGA tests. SEM and TEM observations revealed the formation of the porous structure in these nanofibers. After the formation of the porous structure, Brunauer–Emmett–Teller specific surface areas of nanofibers were increased as compared to solid Nylon 6 and composite nanofibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 DA - 2011/4/5/ PY - 2011/4/5/ DO - 10.1002/app.33161 VL - 120 IS - 1 SP - 425-433 SN - 1097-4628 KW - electrospinning KW - nanocomposite KW - porous nanofibers KW - Nylon 6 ER - TY - JOUR TI - A four kinetic state model of fast axonal transport: Model formulation and perturbation solution AU - Kuznetsov, Andrey V. T2 - CENTRAL EUROPEAN JOURNAL OF PHYSICS AB - Abstract This paper formulates a four kinetic state model for fast axonal transport. The paper further develops the Smith-Simmons model that is based on equations governing intracellular molecular-motor-assisted transport; these equations are extended by considering four rather than three kinetic states for organelles. The model considers plus-end and minus-end-oriented organelles that can be either free (suspended in the cytosol) or attached to microtubules (MTs) (in the latter case organelles are transported by molecular motors). The paper then develops a method for uncoupling differential equations of the proposed model. A perturbation solution of this problem is obtained. The effect of transition between plus-end-oriented and minus-end oriented organelles is discussed. The accuracy of the obtained perturbation solution is evaluated by comparing the zero-order and the first-order results with a high-accuracy numerical solution. DA - 2011/2// PY - 2011/2// DO - 10.2478/s11534-010-0032-x VL - 9 IS - 1 SP - 146-156 SN - 1895-1082 KW - molecular motors KW - fast axonal transport KW - intracellular organelles KW - perturbation solution ER -