TY - CHAP TI - Calculation of Convective Heat Transfer Coefficient Using a Semi-infinite Solid Assumption AU - Ekkad, S.V. T2 - Heat-transfer calculations A2 - Kutz, Myer PY - 2006/// PB - McGraw-Hill ER - TY - CONF TI - Generation of plasma induced flow actuation by DC glow-like discharge in a supersonic flow AU - Shin, J. AU - Narayanaswamy, V. AU - Raja, L.L. AU - Clemens, N. AB - Plasma induced ∞ow fleld modiflcation is studied experimentally using non-equilibrium DC surface discharge in a Mach 3 supersonic ∞ow. An array of small pin electrodes (` = 3=32) is used in streamwise plasma discharge conflguration. The schlieren imaging shows that an oblique shock can be obtained with a volumetric glow discharge on the cathode with a relatively low current (as low as 50 mA). The actuation is found to be immediate with a time scale less than 222 „s whenever there is a noticeable volumetric glow region on the cathode in both cathode upstream and cathode downstream cases. With a laser schlieren, three identiflable modes are observed and the selected modes which have a volumetric glow on top of the cathode can give an actuation while the other mode does not show any noticeable efiect. The conditions to get an appropriate mode are dependent mostly on the stagnation pressure. Increasing the current gives a preference to have a constricted plasma while a pressure decrease gives a volumetric glow. C2 - 2006/// C3 - Collection of Technical Papers - 44th AIAA Aerospace Sciences Meeting DA - 2006/// DO - 10.2514/6.2006-169 VL - 3 SP - 2042-2051 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-34250751149&partnerID=MN8TOARS ER - TY - JOUR TI - Jet impingement heat transfer visualization using a steady state liquid crystal method AU - Esposito, E. AU - Ekkad, S.V. T2 - Journal of Heat Transfer AB - Experimental Procedure: •Blower is set appropriately for required jet Reynolds number •Heater is turned on and allowed to reach steady state •A picture is taken of the liquid crystal coated test plate and heater amperage and voltage measured •Heater power is incrementally increased and additional pictures taken to capture temperature and heater flux data at every point in the array •Pictures are converted to Hue and liquid crystal calibration curve used to determine temperature at corresponding point DA - 2006/// PY - 2006/// DO - 10.1115/1.2221301 VL - 128 IS - 8 SP - 738 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-52949104145&partnerID=MN8TOARS ER - TY - CONF TI - Film cooling predictions for cratered cylindrical inclined holes AU - Lu, Y. AU - Ekkad, S.V. AB - Film cooling is studied for cylindrical holes embedded in craters. Different crater geometries are considered for a typical crater depth. Cratered holes occur when blades are coated with thermal barrier coating layers by masking the hole area during TBC spraying. The film performance and behavior will be different for the cratered holes compared to standard cylindrical holes. FLUENT is used to simulate film cooling for the different crater geoemtries and compared to baseline uncratered cylindrical holes. Film effectiveness is reduced by the cratering compared to earlier studies which had two-dimensional trenches instead of craters. The study is performed at a single mainstream Reynolds number based on free-stream velocity and film hole diameter of 11000 at one different coolant-to-mainstream blowing ratio of 1.0. C2 - 2006/// C3 - American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD DA - 2006/// DO - 10.1115/IMECE2006-14406 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84920632974&partnerID=MN8TOARS ER - TY - JOUR TI - Film cooling measurements for novel hole configurations AU - Lu, Y. AU - Nasir, H. AU - Faucheaux, D. AU - Ekkad, S.V. T2 - Journal of Heat Transfer AB - Experimental Procedure: •Blower is set appropriately for required mainstream velocity •Heater is turned on and allowed to heat the air to a desired mainstream temperature •The coolant air is provided from separate compressed air supply and is metered for flow measurement •The mainstream and coolant are triggered at the same instant when the IR system starts taking images and saving to hard drive at set intervals •Images are saved then processed to calculate the heat transfer coefficients and film effectiveness using the theory DA - 2006/// PY - 2006/// DO - 10.1115/1.2221300 VL - 128 IS - 8 SP - 737 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84969860204&partnerID=MN8TOARS ER - TY - CONF TI - Corrugated wall jet impingement geometry for combustor liner backside cooling AU - Esposito, E.I. AU - Ekkad, S.V. AU - Dutta, P. AU - Kim, Y. AU - Greenwood, S. AB - The present study investigates alternative jet impingement geometries aimed at the reduction of detrimental crossflow effects for use in combustor liner backside cooling. Through the use of a corrugated wall design, the spent air of upstream jets is routed past downstream jets with minimal interference. Three configurations of the design are studied. First, the jet spacing is held constant, and the design of the corrugations is changed for sparse arrays. The second part of the study studied the effects of the corrugated wall on dense arrays. The average jet Reynolds number, Red, is varied and tested for 20000, 40000, and 60000. Local Nusselt number distributions were evaluated using a transient liquid crystal technique. The results show that the corrugated wall design can significantly reduce the negative effects of crossflow especially at higher jet Reynolds numbers. Further, the design of the corrugations has a substantial impact on the performance of the geometry. The corrugated wall geometries with smaller bypass channels outperformed the geometries tested with larger channels. The use of corrugated jet impingement configurations would allow larger jet impingement arrays without sacrificing heat transfer effectiveness. C2 - 2006/// C3 - American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD DA - 2006/// DO - 10.1115/IMECE2006-13300 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84920630604&partnerID=MN8TOARS ER - TY - CONF TI - Predictions of film cooling from cylindrical holes embedded in trenches AU - Lu, Y. AU - Ekkad, S.V. C2 - 2006/// C3 - Collection of Technical Papers - 9th AIAA/ASME Joint Thermophysics and Heat Transfer Conference Proceedings DA - 2006/// VL - 2 SP - 1361-1369 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33845532553&partnerID=MN8TOARS ER - TY - CONF TI - Influence of hole angle and shaping on leading edge showerhead film cooling AU - Lu, Y. AU - Allison, D. AU - Ekkad, S.V. AB - Detailed film cooling measurements are presented on a turbine blade leading edge model with three rows of showerhead holes. Experiments are run at a mainstream Reynolds number of 19,500 based on cylindrical leading edge diameter. One row of holes is located on the stagnation line and the other two rows are located at ±15° on either side of the stagnation line. The three rows have compound angle holes angled 90° in the flow direction, 30° along the spanwise direction, and the two holes on either side of the stagnation row have and additional angle of 0°, 30°, and 45° in the transverse direction. The effect of hole shaping of the 30° and 45° holes is also considered. Detailed heat transfer coefficient and film effectiveness measurements are obtained using a transient infrared thermography technique. The results are compared to determine the advantages of shaping the compound angle for rows of holes off stagnation row. Results show that, the additional compound angle in the transverse direction for the two rows adjacent to the stagnation row provide significantly higher film effectiveness than the typical leading edge holes with only two angles. Results also show that, the shaping of showerhead holes provides higher film effectiveness than just adding an additional compound angle in the transverse direction and significantly higher effectiveness than the baseline typical leading edge geometry. Heat transfer coefficients are higher as the spanwise angle for this study is larger than typical leading edge geometries with an angle of 30° compared to 20° for other studies. C2 - 2006/// C3 - Proceedings of the ASME Turbo Expo DA - 2006/// DO - 10.1115/GT2006-90370 VL - 3 PART A SP - 375-382 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33750852255&partnerID=MN8TOARS ER - TY - JOUR TI - Effect of jet pulsation and duty cycle on film cooling from a single jet on a leading edge model AU - Ekkad, S.V. AU - Ou, S. AU - Rivir, R.B. T2 - Journal of Turbomachinery AB - The effect of jet pulsation and duty cycle on film effectiveness and heat transfer was investigated on a film hole located on the circular leading edge of a blunt body. A transient infrared technique was used to measure both heat transfer coefficients and film effectiveness from a single test. Detailed Frossling number and film effectiveness distributions were obtained for all flow conditions. Jet pulsing frequencies of 5 Hz, 10 Hz, and 20 Hz have been studied. The effect of duty cycle created by the valve opening and closing times was also set at different levels of 10%, 25%, 50%, and 75% of designated 100% fully open condition for different blowing ratios from 0.25 to 2.0. The combination of pulse frequency and duty cycle was investigated for different blowing ratios on a single leading edge hole located at 22 deg from geometric leading edge. Results indicate that higher effectiveness and lower heat transfer coefficients are obtained at the reduced blowing ratios, which result from reduced duty cycles. The effect of varying the pulsing frequency from 5 Hz to 20 Hz is not discernable beyond the level of experimental uncertainty. Effective blowing ratio due to lowering of the duty cycle at a given blowing ratio seems to play a more important role in combination with pulsing, which provides improved cooling effectiveness at lower heat transfer coefficients. DA - 2006/// PY - 2006/// DO - 10.1115/1.2185122 VL - 128 IS - 3 SP - 564-571 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33845689956&partnerID=MN8TOARS ER - TY - JOUR TI - Simulation and Analysis of Unbonded Nonwoven Fibrous Structures AU - Pourdeyhimi, Behnam AU - Mazé, Benoit AU - Tafreshi, Hooman Vahedi T2 - Journal of Engineered Fibers and Fabrics AB - In this work we report on our algorithm for generating 3–D virtual structures resembling un-bonded fibrous webs. The paper discusses short and infinitely long fibers, each emulating a category of nonwoven fibrous medium. The structure Solid Volume Fraction (SVF), being the most important characteristic of a fibrous porous medium, is calculated for different fiberwebs and discussed in details. It is shown that the SVF of the fibrous structures generated by our algorithm is independent of the basis weight. In other words, the porosity of the medium is only a function of the fiber properties – this is as expected. It is also demonstrated that by decreasing the fiber diameter while keeping other properties of the virtual fiberweb constant causes the SVF to decrease almost linearly. The same is not observed for the fiber rigidity. The capability of our algorithm for generating fibrous webs made up of layers of different fibers is demonstrated and their properties are discussed. The application of such virtual fibrous structures in modeling transport phenomena in nonwoven materials and their potential applications in load-deformation studies are discussed. DA - 2006/6// PY - 2006/6// DO - 10.1177/155892500600100204 VL - 1 IS - 2 SP - 155892500600100 J2 - Journal of Engineered Fibers and Fabrics LA - en OP - SN - 1558-9250 1558-9250 UR - http://dx.doi.org/10.1177/155892500600100204 DB - Crossref ER - TY - CONF TI - Inelastic behavior and grain-boundary effects in polycrystalline materials AU - Shi, J. AU - Zikry, M. AU - Hatem, T.M. C2 - 2006/// C3 - Materials Research Society Symposium Proceedings DA - 2006/// DO - 10.1557/proc-978-0978-gg12-07-ee08-07 VL - 978 SP - 333-338 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-41549160841&partnerID=MN8TOARS ER - TY - CONF TI - In-situ failure identification in woven composites throughout impact using fiber bragg grating sensors AU - Pearson, J. AU - Prabhugoud, M. AU - Zikry, M. AU - Peters, K. AB - In this study, measurements from low-impact velocity experiments and surface mounted optical fiber Bragg grating (FBG) sensors were used to obtain detailed information pertaining to damage progression in two-dimensional laminate woven composites. The woven composites were subjected to multiple strikes at 2m/s until perforation occurred, and the impactor position and acceleration were monitored throughout each event. From these measurements, we obtained dissipated energies and contact forces. The FBG sensors were surface mounted at different critical locations near penetration-induced damaged regions. These FBG sensors were used to obtain initial residual strains and axial and transverse strains that correspond to matrix cracking and delamination. The transmission and the reflection spectra were continuously monitored throughout the loading cycles. They were used, in combination with the peak contact forces, to delineate repeatable sensor responses corresponding to material failure. From the FBG spectra, fiber and matrix damage were separated by an analysis based on the behavior of individual Bragg peaks as a function of evolving and repeated impact loads. This provided an independent feedback on the integrity of the Bragg gratings. Thus, potential sources of error such as sensor debonding were eliminated from the strain data throughout the measurements. A comparison by number of impact strikes and dissipated energies corresponding to material perforation indicates that these measurements can provide accurate failure strains. C2 - 2006/// C3 - Proceedings of SPIE - The International Society for Optical Engineering DA - 2006/// DO - 10.1117/12.657989 VL - 6174 II UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33745946683&partnerID=MN8TOARS ER - TY - CONF TI - Microstructural behavior and failure of FCC crystalline aggregates AU - Rezvanian, O. AU - Zikry, M.A. AU - Rajendran, A.M. C2 - 2006/// C3 - Materials Research Society Symposium Proceedings DA - 2006/// DO - 10.1557/proc-976-0976-ee02-02 VL - 976 SP - 78-83 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-41549153890&partnerID=MN8TOARS ER - TY - CONF TI - Local strain characterization on strained-Si/SiGe heterostructures with convergent beam electron diffraction and finite element simulation AU - Zhao, W. AU - Duscher, G. AU - Zikry, M.A. AU - Rozgonyi, G. AB - We introduce a novel and reliable method to quantify local strain variation in microelectronic device structures based on convergent beam electron diffraction (CBED) and finite element (FE) calculation. The match of the finite element calculation results with the experimental data not only validated the parameters used for the finite element simulations, but also gives us insights into the origin of high order Laue zone (HOLZ) line splitting in a lattice-mismatched heterostructure. The 2D and 3D calculations showed that the residual strain measured from clean and sharp CBED patterns deviate from the initial strain. The effect of a SiO2 layer on the strain in a TEM sample was also investigated by FE simulation and we found that a SiO2 layer can suppress some of the elastic deformation making it possible to obtain clean and sharp CBED patterns. The here proposed novel method uses the elastic deformation to determine the initial strain in microelectronic devices structures by combining FE simulations and CBED patterns. C2 - 2006/// C3 - ECS Transactions DA - 2006/// DO - 10.1149/1.2355831 VL - 3 SP - 333-338 M1 - 7 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33846976714&partnerID=MN8TOARS ER - TY - CONF TI - In-situ failure identification in woven composites throughout impact AU - Pearson, J. AU - Prabhugoud, M. AU - Zikry, M. AU - Peters, K. C2 - 2006/// C3 - American Society of Mechanical Engineers, Materials Division (Publication) MD DA - 2006/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84920632313&partnerID=MN8TOARS ER - TY - CONF TI - Computational modeling and design of adaptive thin-film composite coatings AU - Pearson, J.D. AU - Zikry, M.A. AU - Rezvanian, O. C2 - 2006/// C3 - Materials Research Society Symposium Proceedings DA - 2006/// DO - 10.1557/proc-977-0977-ff08-10 VL - 977 SP - 85-90 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-41549101067&partnerID=MN8TOARS ER - TY - CONF TI - Nanoparticle Filtration by Virtual Nonwoven Media AU - Wang, Q. AU - Maze, B. AU - Tafreshi, H.V. AU - Pourdeyhimi, B. T2 - American Filtration & Separations Society C2 - 2006/5/8/ CY - Chicago, Illinois DA - 2006/5/8/ PY - 2006/5/8/ ER - TY - CONF TI - Predicting Inlet Roundness of Hydroentangling Nozzles Using CFD Simulations AU - Anantharamaiah, N. AU - Tafreshi, H.V. AU - Pourdeyhimi, B. T2 - International Nonwoven Technical Conference (INTC 2006) C2 - 2006/9/24/ C3 - International Nonwoven Technical Conference (INTC 2006) CY - Houston, Texas DA - 2006/9/24/ PY - 2006/9/24/ ER - TY - CONF TI - Permeability of Highly Dense Nonwoven Fabrics AU - Zobel, S. AU - Maze, B. AU - Tafreshi, H.V. AU - Pourdeyhimi, B. T2 - International Nonwoven Technical Conference (INTC 2006) C2 - 2006/9/24/ C3 - International Nonwoven Technical Conference (INTC 2006) CY - Houston, Texas DA - 2006/9/24/ PY - 2006/9/24/ ER - TY - CONF TI - The Role of Waterjet Curtain in Modifying the Jet Streaks in Hydroentangling AU - Anantharamaiah, N. AU - Roempert, K. AU - Tafreshi, H.V. AU - Pourdeyhimi, B. T2 - International Nonwoven Technical Conference (INTC 2006) C2 - 2006/9/24/ C3 - International Nonwoven Technical Conference (INTC 2006) CY - Houston, Texas DA - 2006/9/24/ PY - 2006/9/24/ ER - TY - CONF TI - Hydroentangling - A Path to Technical Nonwovens AU - Anantharamaiah, N. AU - Roempert, K. AU - Tafreshi, H.V. AU - Pourdeyhimi, B. T2 - TechTextil C2 - 2006/3/29/ C3 - TechTextil CY - Atlanta, Georgia DA - 2006/3/29/ PY - 2006/3/29/ ER - TY - JOUR TI - The role of gas dynamics in operation conditions of a puised microplasma cluster source for nanostructured thin films deposition AU - Vahedi Tafreshi, H. AU - Piseri, P. AU - Benedek, G. AU - Milani, P. T2 - Journal of Nanoscience and Nanotechnology AB - This study intends to explain the fluid dynamic characteristics of a Pulsed Microplasma Cluster Source (PMCS). An axially symmetric steady state simulation is performed for modeling the real-life three-dimensional unsteady flow of hypersonic helium inside our PMCS. Hypersonic helium flow is simulated using Realizable k-epsilon turbulent model. We obtained the jet velocity, density, and pressure field inside our PMCS for the conditions considered and discussed them with respect to our experimental observations. We also presented a qualitative discussion on the formation-termination process of this hypersonic jet. In particular, simulation, in agreement with the experiment, indicates that the middle stage of the injection process, where the Mach disk stands close to the ablation target and at the same time the mass flow rate is relatively high, is almost the appropriate time for firing the electric discharge. We simulated the jet-electrode impingement and tracked the trajectory of the ablated carbon clusters, considered as rigid spheres, inside the PMCS. We noticed that the spatial distribution of the clusters inside PMCS is highly conserved during the free expansion of the cluster beam out of the nozzle (in the vacuum chambers) and is recognizable in the deposited carbon film. This indicates that the geometry of PMCS plays a significant role in the uniformity of the deposited film. DA - 2006/// PY - 2006/// DO - 10.1166/jnn.2006.139 VL - 6 IS - 4 SP - 1140-1149 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33745627534&partnerID=MN8TOARS KW - CFD KW - supersonic jet KW - nanoparticles KW - modeling ER - TY - CONF TI - Fiber dispersion in wet-lay mixing tanks AU - Latifi, M. AU - Vahedi Tafreshi, H. AU - Pourdeyhimi, B. C2 - 2006/// C3 - International Nonwovens Technical Conference, INTC 2006 DA - 2006/// SP - 384-389 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-36049022222&partnerID=MN8TOARS ER - TY - JOUR TI - Approaches for predicting collation efficiency of fibrous filters AU - Wang, Q. AU - Maze, B. AU - Vahedi Tafreshi, H. AU - Pourdeyhimi, B. T2 - Journal of Textile and Apparel, Technology and Management DA - 2006/// PY - 2006/// VL - 5 IS - 2 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33749549286&partnerID=MN8TOARS ER - TY - JOUR TI - Development of Polymeric Based Lubricant for Cold Forging Processes AU - Ngaile, Gracious AU - Stark, David AU - Cochran, Joseph T2 - Transaction of the North American Manufacturing Research Institution of SME DA - 2006/// PY - 2006/// VL - 34 SP - 563–570 ER - TY - JOUR TI - Influence of oxygen, hydrogen, helium, argon and vacuum on the surface behavior of molten InSb, other semiconductors, and metals on silica AU - Kota, Arun K. AU - Anand, Gaurav AU - Ramakrishnan, Suresh AU - Regel, Liya L. AU - Wilcox, William R. T2 - Journal of Crystal Growth AB - Sessile drop experiments were performed on molten indium antimonide on clean quartz (fused silica) surfaces. A cell was constructed through which argon, helium, oxygen, hydrogen or a mixture of these was flowed at 600 °C. Some of the InSb was doped with 0.1% Ga. The surface tension σ of oxide-free molten InSb was smaller in Ar than in He, may have increased with increasing O2 in the gas, and was not influenced by Ga or H2. The contact angle θ on silica was higher in the presence of Ar, was lowered by O2, and was not influenced by H2 or Ga. The work of adhesion W and the surface energy σsv of the silica were higher in He than in Ar. The surface remained free of solid oxide only in flowing gas containing ⩽0.8 ppm O2. This behavior is attributed to reaction of O2 at the surface of the melt to form In2O gas. When solid oxide formed on Ga-doped material, it was strongly enriched in Ga, with the Ga/In ratio increasing with the concentration of O2 in the gas. Examination of published sessile-drop results for liquid metals and semiconductors on silica revealed that W and σsv were highest for reactive melts, in which SiO2 dissolves. For non-reactive melts, W and σsv were lower and θ higher in a gas than in a vacuum, regardless of whether the experiments had been carried out in sealed ampoules, a flowing gas, or dynamic vacuum. The implication is that the surface of silica was different in a vacuum than in a gas at ∼1 bar. DA - 2006/5// PY - 2006/5// DO - 10.1016/j.jcrysgro.2006.01.044 VL - 290 IS - 2 SP - 319-333 J2 - Journal of Crystal Growth LA - en OP - SN - 0022-0248 UR - http://dx.doi.org/10.1016/j.jcrysgro.2006.01.044 DB - Crossref KW - contact angle KW - surface tension KW - growth from melt KW - metals KW - semiconducting materials ER - TY - CONF TI - A Study of the Relationship Between Buckling and Wrinkling of Membranes AU - Eischen, J.W. T2 - Ninth Pan American Congress of Applied Mechanics C2 - 2006/1// C3 - Proceedings of the Ninth Pan American Congress of Applied Mechanics CY - Merida, Yucatan, Mexico DA - 2006/1// PY - 2006/1/2/ ER - TY - CONF TI - A Hierarchical Self-tuning Fuzzy Controller for General Nonlinear Systems with Stability Analysis AU - Xu, C. AU - Shin, Y.C. T2 - 3rd International Conference on Cybernetics and Information Technologies Systems and Applications C2 - 2006/// CY - Orlando, FL DA - 2006/// PY - 2006/// ER - TY - CONF TI - Adaptive Control of Cutting Force for End Milling Processes with System Variation using Self-tuning Fuzzy Technique AU - Xu, C. AU - Shin, Y.C. T2 - ASME International Mechanical Engineering Congress and Exposition C2 - 2006/// CY - Chicago, IL DA - 2006/// PY - 2006/// ER - TY - CONF TI - Tracking Control of an Underactuated Autonomous Surface Vessel Using Switched Feedback AU - Reyhanoglu, Mahmut AU - Bommer, Ard T2 - IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics AB - This paper studies the tracking problem for an underactuated autonomous surface vessel. The research extends earlier backstepping designs for underactuated systems by constructing a switched feedback control law to achieve global tracking. The control law avoids singularities arising from coordinate transformations used to describe the surface vessel dynamics in second-order chained form. The paper provides a detailed derivation of the control law. Simulation examples are included to illustrate the effectiveness of the tracking controller C2 - 2006/11// C3 - Proceedings of IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics CY - Paris, France DA - 2006/11// PY - 2006/11/6/ DO - 10.1109/iecon.2006.347539 PB - IEEE SN - 1424403901 142440391X UR - http://dx.doi.org/10.1109/iecon.2006.347539 ER - TY - JOUR TI - Enhanced optical field intensity distribution in organic photovoltaic devices using external coatings AU - O’Connor, Brendan AU - An, Kwang H. AU - Pipe, Kevin P. AU - Zhao, Yiying AU - Shtein, Max T2 - Applied Physics Letters AB - An external dielectric coating is shown to enhance energy conversion in an organic photovoltaic cell with metal anode and cathode by increasing the optical field intensity in the organic layers. Improved light incoupling in the device is modeled using transfer matrix simulations and is confirmed by in situ measurement of the photocurrent during growth of the coating. The optical field intensity in optimized cell geometries is predicted to exceed that in analogous devices using indium tin oxide, both cell types having equivalent anode sheet resistance, suggesting a broader range of compatible substrates (e.g., metal foils) and device processing techniques. DA - 2006/12/4/ PY - 2006/12/4/ DO - 10.1063/1.2399937 VL - 89 IS - 23 SP - 233502 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.2399937 DB - Crossref ER - TY - JOUR TI - Exact solutions of incompressible Couette flow with porous walls for slightly rarefied gases AU - Fang, T. AU - Lee, C.-F.F. T2 - Heat and Mass Transfer/Waerme- und Stoffuebertragung DA - 2006/// PY - 2006/// DO - 10.1007/s00231-005-0009-2 VL - 42 IS - 3 SP - 255-262 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-28044464021&partnerID=MN8TOARS KW - transient Couette flow KW - exact solution KW - slightly rarefied gas KW - porous channel KW - micro-channel KW - slip flow KW - heat transfer KW - incompressible flow ER - TY - JOUR TI - Combustion and soot visualization of Low Temperature Combustion within an HSDI diesel engine using multiple injection strategy AU - Fang, T. AU - Coverdill, R.E. AU - Lee, C.-F.F. AU - White, R.A. T2 - SAE Technical Papers DA - 2006/// PY - 2006/// DO - 10.4271/2006-01-0078 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84877211771&partnerID=MN8TOARS ER - TY - JOUR TI - Comparisons of computed and measured results for a HSDI diesel engine operating under HCCI mode AU - Wang, R.C. AU - Fang, T. AU - Lee, C.-F.F. T2 - SAE Technical Papers DA - 2006/// PY - 2006/// DO - 10.4271/2006-01-1519 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84877438217&partnerID=MN8TOARS ER - TY - JOUR TI - A thermal actuator for nanoscale in situ microscopy testing: design and characterization AU - Zhu, Yong AU - Corigliano, Alberto AU - Espinosa, Horacio D T2 - Journal of Micromechanics and Microengineering AB - This paper addresses the design and optimization of thermal actuators employed in a novel MEMS-based material testing system. The testing system is designed to measure the mechanical properties of a variety of materials/structures from thin films to one-dimensional structures, e.g. carbon nanotubes (CNTs) and nanowires (NWs). It includes a thermal actuator and a capacitive load sensor with a specimen in-between. The thermal actuator consists of a number of V-shaped beams anchored at both ends. It is capable of generating tens of milli-Newton force and a few micrometers displacement depending on the beams' angle and their number. Analytical expressions of the actuator thermomechanical response are derived and discussed. From these expressions, a number of design criteria are drawn and used to optimize the device response. The analytical predictions are compared with both finite element multiphysics analysis (FEA) and experiments. To demonstrate the actuator performance, polysilicon freestanding specimens cofabricated with the testing system are tested. DA - 2006/2/1/ PY - 2006/2/1/ DO - 10.1088/0960-1317/16/2/008 VL - 16 IS - 2 SP - 242–253 SN - 0960-1317 1361-6439 UR - http://dx.doi.org/10.1088/0960-1317/16/2/008 ER - TY - JOUR TI - Moment-generating capacity of upper limb muscles AU - Holzbaur, K.R.S. AU - Delp, S.L. AU - Murray, W.M. T2 - Journal of Biomechanics DA - 2006/1// PY - 2006/1// DO - 10.1016/S0021-9290(06)83233-1 VL - 39 SP - S85 J2 - Journal of Biomechanics LA - en OP - SN - 0021-9290 UR - http://dx.doi.org/10.1016/S0021-9290(06)83233-1 DB - Crossref ER - TY - JOUR TI - MRI-based estimation of muscle volume and length following tendon transfer surgery AU - Holzbaur, K.R.S. AU - Gold, G.E. AU - Johanson, M.E. AU - Murray, W.M. T2 - Journal of Biomechanics DA - 2006/1// PY - 2006/1// DO - 10.1016/S0021-9290(06)83227-6 VL - 39 SP - S84 J2 - Journal of Biomechanics LA - en OP - SN - 0021-9290 UR - http://dx.doi.org/10.1016/S0021-9290(06)83227-6 DB - Crossref ER - TY - CONF TI - Switched Feedback Tracking Control of a Nonholonomic Mobile Robot AU - Reyhanoglu, Mahmut AU - Geluk, Theo T2 - IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics AB - This paper studies the tracking problem for a car-like nonholonomic mobile robot. A switched feedback control law is developed to achieve global tracking. The control law avoids singularities arising from coordinate transformations used to describe the robot kinematics in chained form. The paper provides a detailed derivation of the control law. Simulation examples are included to illustrate the effectiveness of the tracking controller C2 - 2006/11// C3 - IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics DA - 2006/11// DO - 10.1109/iecon.2006.347507 PB - IEEE SN - 1424403901 142440391X UR - http://dx.doi.org/10.1109/iecon.2006.347507 DB - Crossref ER - TY - CONF TI - State Feedback Tracking of a Nonholonomic Control Moment Gyroscope AU - Reyhanoglu, Mahmut AU - van de Loo, Jasper T2 - Proceedings of the 45th IEEE Conference on Decision and Control AB - This paper describes how to use a cascaded back-stepping approach to develop state feedback control laws for the tracking of a restricted control moment gyroscope (CMG), which constitutes a remarkable example of a nonholonomic system that arises as a consequence of its symmetry properties. A nonholonomic control system formulation is first introduced for the restricted CMG dynamics. The backstepping technique is then used to design a state feedback control law for the tracking of the CMG system. The paper provides detailed derivations along with numerical simulations and experimental results to illustrate the effectiveness of the tracking controller. C2 - 2006/// C3 - Proceedings of the 45th IEEE Conference on Decision and Control DA - 2006/// DO - 10.1109/cdc.2006.377590 PB - IEEE SN - 1424401712 UR - http://dx.doi.org/10.1109/cdc.2006.377590 DB - Crossref ER - TY - CONF TI - Rest-to-rest Maneuvering of a Nonholonomic Control Moment Gyroscope AU - Reyhanoglu, Mahmut AU - De Loo, Jasper T2 - 2006 IEEE International Symposium on Industrial Electronics AB - This paper studies a restricted control moment gyroscope (CMG), which constitutes a remarkable example of a nonholonomic system that arises as a consequence of its symmetry properties. A nonholonomic control system formulation is first introduced for the restricted CMG dynamics. The geometric phase technique is then used to design a feedback control algorithm for the control of the CMG system to a desired equilibrium. The effectiveness of the feedback control algorithm is illustrated through both numerical simulations and experimental results C2 - 2006/7// C3 - 2006 IEEE International Symposium on Industrial Electronics DA - 2006/7// DO - 10.1109/isie.2006.295585 PB - IEEE SN - 1424404975 1424404967 UR - http://dx.doi.org/10.1109/isie.2006.295585 DB - Crossref ER - TY - CONF TI - Modeling and Analysis of a Thermal Management System for Engine Calibration AU - Vermillion, Chris AU - Sun, Jing AU - Butts, Ken AU - Hall, Andy T2 - 2006 IEEE International Conference on Control Applications C2 - 2006/10// C3 - 2006 IEEE International Conference on Control Applications DA - 2006/10// DO - 10.1109/cca.2006.286181 PB - IEEE SN - 0780397967 0780397959 UR - http://dx.doi.org/10.1109/cca.2006.286181 DB - Crossref ER - TY - JOUR TI - Comparison of ultrasonic axial transmission and pQCT parameters to bone mechanical properties in vitro AU - Muller, M. AU - Moilanen, P. AU - Bosisio, M. AU - Mitton, D. AU - Talmant, M. T2 - Journal of Biomechanics DA - 2006/1// PY - 2006/1// DO - 10.1016/S0021-9290(06)84849-9 VL - 39 SP - S452 J2 - Journal of Biomechanics LA - en OP - SN - 0021-9290 UR - http://dx.doi.org/10.1016/S0021-9290(06)84849-9 DB - Crossref ER - TY - JOUR TI - Fatigue damage in cortical bone detected using nonlinear ultrasound AU - Muller, M. AU - D'Hanens, A. AU - Mitton, D. AU - Talmant, M. AU - Johnson, P. AU - Laugier, P. T2 - Journal of Biomechanics DA - 2006/1// PY - 2006/1// DO - 10.1016/S0021-9290(06)82896-4 VL - 39 SP - S8 J2 - Journal of Biomechanics LA - en OP - SN - 0021-9290 UR - http://dx.doi.org/10.1016/S0021-9290(06)82896-4 DB - Crossref ER - TY - JOUR TI - Bone micro-damage assessment using non-linear resonant ultrasound spectroscopy (NRUS) techniques: A feasibility study AU - Muller, M. AU - Tencate, J.A. AU - Darling, T.W. AU - Sutin, A. AU - Guyer, R.A. AU - Talmant, M. AU - Laugier, P. AU - Johnson, P.A. T2 - Ultrasonics AB - Non-linear resonant ultrasound spectroscopy (NRUS) is a technique exploiting the significant non-linear behavior of damaged materials, related to the presence of damage. This study shows for the first time the feasibility of this technique for damage assessment in bone. Two samples of bovine cortical bone were subjected to a progressive damage experiment. Damage accumulation was progressively induced in the samples by mechanical testing. For independent assessment of damage, X-ray CT imaging was performed at each damage step, but only helped in the detection of the prominent cracks. Synchrotron micro-CT imaging and histology using epifluorescence microscopy were performed in one of the two samples at the last damage step and allowed detection of micro-cracks for this step. As the quantity of damage accumulation increased, NRUS revealed a corresponding increase in the non-linear response. The measured change in non-linear response is much more sensitive than the change in elastic modulus. The results suggest that NRUS could be a potential tool for micro-damage assessment in bone. Further work has to be carried out for a better understanding of the physical nature of damaged bone, and for the ultimate goal of in vivo implementation of the technique where bone access will be a challenging problem. DA - 2006/12// PY - 2006/12// DO - 10.1016/j.ultras.2006.06.043 VL - 44 SP - e245-e249 J2 - Ultrasonics LA - en OP - SN - 0041-624X UR - http://dx.doi.org/10.1016/j.ultras.2006.06.043 DB - Crossref KW - bone KW - micro-damage KW - non-linear resonant ultrasound spectroscopy KW - non-destructive evaluation ER - TY - JOUR TI - Organic light-emitting device on a scanning probe cantilever AU - An, Kwang H. AU - O’Connor, Brendan AU - Pipe, Kevin P. AU - Zhao, Yiying AU - Shtein, Max T2 - Applied Physics Letters AB - Organic light-emitting devices (OLEDs) were fabricated on scanning probe cantilevers using a combination of thermally evaporated molecular organic compounds and metallic electrodes. Ion beam milling was used to define the emissive region in the shape of a ring having a diameter of less than 5μm and a narrow width. Stable light emission was observed from the device at forward bias, with a current-voltage response similar to that of archetypal OLEDs. Based on this device, a novel electrically pumped scanning optical microscopy tool is suggested. DA - 2006/9/11/ PY - 2006/9/11/ DO - 10.1063/1.2353816 VL - 89 IS - 11 SP - 111117 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.2353816 DB - Crossref ER - TY - JOUR TI - A note on the extended Blasius equation AU - Fang, Tiegang AU - Guo, Fang AU - Lee, Chia-fon F. T2 - Applied Mathematics Letters AB - In a recent paper, the Blasius equation was extended to a nonlinear equation like af‴+ff″=0 with the prime denoting differentiation with respect to the similarity variable η and a being a constant parameter. The current note will show that the solution of the extended Blasius equation can be obtained from the original Blasius equation solution with a variable transformation technique. The observed phenomena in numerical solutions of previous published work are theoretically analyzed. The equation is also discussed for an arbitrary real parameter or complex parameters. It is further shown that the extended Blasius equation is a special form of the similarity equation of momentum boundary layers over a flat plate with a temperature dependent property. DA - 2006/7// PY - 2006/7// DO - 10.1016/j.aml.2005.08.010 VL - 19 IS - 7 SP - 613-617 J2 - Applied Mathematics Letters LA - en OP - SN - 0893-9659 UR - http://dx.doi.org/10.1016/j.aml.2005.08.010 DB - Crossref KW - Blasius equation KW - boundary layer flow KW - flat plate KW - numerical solution KW - similarity equation ER - TY - JOUR TI - A new iteration method with cubic convergence to solve nonlinear algebraic equations AU - Fang, Tiegang AU - Guo, Fang AU - Lee, Chia-fon F. T2 - Applied Mathematics and Computation AB - Abstract In this paper, a new iteration scheme is proposed to solve the roots of an algebraic equation f(x) = 0. Given an initial guess, x0, the roots of the equation can be obtained using the following iteration scheme: x n + 1 = x n + - f ′ ( x n ) ± f ′ 2 ( x n ) - 2 f ( x n ) f ″ ( x n ) f ″ ( x n ) . This iteration scheme has unique convergence characteristics different from the well-known Newton’s method. It is shown that this iteration method has cubic local convergence in the neighborhood of the root. Using this scheme, real or complex roots for specific algebraic equations can be found. Because there are two iteration directions, for a given initial guess, two solutions can be found for certain algebraic equations with multiple roots. Examples are presented and compared with other methods. DA - 2006/4// PY - 2006/4// DO - 10.1016/j.amc.2005.08.020 VL - 175 IS - 2 SP - 1147-1155 J2 - Applied Mathematics and Computation LA - en OP - SN - 0096-3003 UR - http://dx.doi.org/10.1016/j.amc.2005.08.020 DB - Crossref KW - iteration method KW - algebraic equation KW - nonlinear KW - Newton's method KW - numerical method ER - TY - JOUR TI - Effects of blood flow and vessel geometry on wall stress and rupture risk of abdominal aortic aneurysms AU - Li, Z. AU - Kleinstreuer, C. T2 - Journal of Medical Engineering & Technology AB - Sudden rupture of abdominal aortic aneurysm (AAA), often without prior medical warning, is the 13th leading cause of mortality in the US. The local rupture is triggered when the elusive maximum local wall stress exceeds the patient's yield stress. Employing a validated fluid – structure interaction code, the coupled blood flow and AAA wall dynamics were simulated and analysed for two representative asymmetric AAAs with different neck angles and iliac bifurcations. It turned out that the AAA morphology plays an important role in wall deformation and stress distribution, and hence possible rupture. The neck angle substantially impacts flow fields. A large neck angle may cause strong irregular vortices in the AAA cavity and may influence the wall stress distribution remarkably. The rupture risk of lateral asymmetric AAAs is higher than for the anterior – posterior asymmetric types. The most likely rupture site is located near the anterior distal side for the anterior – posterior asymmetric AAA and the left distal side in the lateral asymmetric AAA. DA - 2006/1// PY - 2006/1// DO - 10.1080/03091900500217406 VL - 30 IS - 5 SP - 283-297 J2 - Journal of Medical Engineering & Technology LA - en OP - SN - 0309-1902 1464-522X UR - http://dx.doi.org/10.1080/03091900500217406 DB - Crossref ER - TY - JOUR TI - Near-normal-incidence extreme-ultraviolet efficiency of a flat crystalline anisotropically etched blazed grating AU - Kowalski, Michael P. AU - Heilmann, Ralf K. AU - Schattenburg, Mark L. AU - Chang, Chih-Hao AU - Berendse, Frederick B. AU - Hunter, William R. T2 - Applied Optics AB - We have measured the extreme-ultraviolet (EUV) efficiency at an angle of incidence of 10 degrees of a flat crystalline anisotropically etched blazed grating. The measured efficiencies are high for uncoated gratings and agree well with a calculated model derived from a reasonable estimate of the groove profile. The highest groove efficiencies derived from the measurements are 48.8% at 19.07 nm and 64.1% at 16.53 nm for the -2 and -3 orders, respectively, which are comparable to the best values obtained yet from a holographic ion-etched blazed grating. This presents opportunities to instrument designs for high-resolution EUV spectroscopy in astrophysics where high efficiency in high orders is desirable. DA - 2006/3/10/ PY - 2006/3/10/ DO - 10.1364/ao.45.001676 VL - 45 IS - 8 SP - 1676 J2 - Appl. Opt. LA - en OP - SN - 0003-6935 1539-4522 UR - http://dx.doi.org/10.1364/ao.45.001676 DB - Crossref ER - TY - JOUR TI - Efficiency of a grazing-incidence off-plane grating in the soft-x-ray region AU - Seely, J. F. AU - Goray, L. I. AU - Kjornrattanawanich, Benjawan AU - Laming, J. M. AU - Holland, G. E. AU - Flanagan, K. A. AU - Heilmann, R. K. AU - Chang, C.-H. AU - Schattenburg, M. L. AU - Rasmussen, A. P. T2 - Applied Optics AB - Efficiency measurements of a grazing-incidence diffraction grating in the off-plane mount were performed using polarized synchrotron radiation. The grating had 5000 grooves/mm, an effective blaze angle of 14°, and was gold coated. The efficiencies in the two polarization orientations (TM and TE) were measured in the 1.5-5.0 nm wavelength range and were compared with the efficiencies calculated using the PCGrate-SX code. The TM and TE efficiencies differ, offering the possibility of performing unique science studies of astrophysical, solar, and laboratory sources by exploiting the polarization sensitivity of the off-plane grating. DA - 2006/3/10/ PY - 2006/3/10/ DO - 10.1364/ao.45.001680 VL - 45 IS - 8 SP - 1680 J2 - Appl. Opt. LA - en OP - SN - 0003-6935 1539-4522 UR - http://dx.doi.org/10.1364/ao.45.001680 DB - Crossref ER - TY - JOUR TI - Describing isotropic and anisotropic out-of-plane deformations in thin cubic materials by use of Zernike polynomials AU - Chang, Chih-Hao AU - Akilian, Mireille AU - Schattenburg, Mark L. T2 - Applied Optics AB - Isotropic and anisotropic out-of-plane deformations induced by thin-film residual stress on thin cubic materials are studied. By transforming the compliance tensor, an analytical expression can be derived for the biaxial stiffness modulus for all directions in any given cubic crystal plane. A modified Stoney's equation, including both isotropic and anisotropic terms, can be formulated to predict the anisotropic out-of-plane deformation. The isotropic and anisotropic deformations are then described using the Zernike polynomials U21 and U22, respectively. Experimental results from (100) and (110) silicon wafers confirm the model by quantitatively comparing the changes in Z21 and Z22 coefficients due to thin-film stress. DA - 2006/1/20/ PY - 2006/1/20/ DO - 10.1364/ao.45.000432 VL - 45 IS - 3 SP - 432 J2 - Appl. Opt. LA - en OP - SN - 0003-6935 1539-4522 UR - http://dx.doi.org/10.1364/ao.45.000432 DB - Crossref ER - TY - CONF TI - An adaptive fuzzy controller for constant cutting force in end-milling processes AU - Xu, C. AU - Shin, Y.C. AB - A novel multi-level fuzzy control (MLFC) system is introduced and implemented for online force control of end-milling processes to increase machining productivity and improve workpiece quality, where the cutting force is maintained at its maximum allowable level in the presence of different variations inherent in milling processes, such as tool wear, workpiece geometry and material properties. In the controller design, the fuzzy rules are generated heuristically without any mathematical model of the milling processes. An adaptation mechanism is embedded in to tune the control parameters on-line and the resultant closed-loop system is guaranteed to be stable based on the input-output passivity analysis. In the experiment, the control algorithm is implemented using a National Instrument real-time control computer in an open architecture control environment, where high metal removal rates (MRR) are achieved and the cycle time is reduced by up to 34% over the case without any force controller, and by 22% compared with the regular fuzzy logic controller (FLC), thereby indicating its effectiveness in improving the productivity for actual machining processes. C2 - 2006/// C3 - American Society of Mechanical Engineers, Dynamic Systems and Control Division (Publication) DSC DA - 2006/// DO - 10.1115/IMECE2006-13758 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84920631460&partnerID=MN8TOARS ER - TY - JOUR TI - A p-multigrid discontinuous Galerkin method for the Euler equations on unstructured grids AU - Luo, H AU - Baum, JD AU - Lohner, R T2 - JOURNAL OF COMPUTATIONAL PHYSICS AB - A p-multigrid (p = polynomial degree) discontinuous Galerkin method is presented for the solution of the compressible Euler equations on unstructured grids. The method operates on a sequence of solution approximations of different polynomial orders. A distinct feature of this p-multigrid method is to use different time integration schemes on different approximation levels, resulting in an accurate, fast, and low memory method that can be used to accelerate the convergence of the Euler equations to a steady state for discontinuous Galerkin methods. The developed method is used to compute the compressible flows for a variety of test problems on unstructured grids. The numerical results obtained strongly indicate the order independent property of this p-multigrid method. An overall speed-up factor more than one order of magnitude for both second- and third-order solutions of all test cases in comparison with the explicit method is demonstrated. DA - 2006/1/20/ PY - 2006/1/20/ DO - 10.1016/j.jcp.2005.06.019 VL - 211 IS - 2 SP - 767-783 SN - 1090-2716 ER - TY - JOUR TI - A hybrid Cartesian grid and gridless method for compressible flows AU - Luo, H AU - Baum, JD AU - Lohner, R T2 - JOURNAL OF COMPUTATIONAL PHYSICS AB - A hybrid Cartesian grid and gridless method is presented to compute unsteady compressible flows for complex geometries. In this method, a Cartesian grid is used as baseline mesh to cover the computational domain, while the boundary surfaces are addressed using a gridless method. This hybrid method combines the efficiency of a Cartesian grid method and the flexibility of a gridless method for the complex geometries. The developed method is used to compute a number of test cases to validate the accuracy and efficiency of the method. The numerical results obtained indicate that the use of this hybrid method leads to a significant improvement in performance over its unstructured grid counterpart for the time-accurate solution of the compressible Euler equations. An overall speed-up factor of about eight and a saving in storage requirements about one order of magnitude for a typical three-dimensional problem in comparison with the unstructured grid method are demonstrated. DA - 2006/5/20/ PY - 2006/5/20/ DO - 10.1016/j.jcp.2005.10.002 VL - 214 IS - 2 SP - 618-632 SN - 1090-2716 KW - compressible flow KW - Euler equations KW - Cartesian grid metbod KW - gridless ER - TY - JOUR TI - Reply on the comments on "Initiation of pulsed corona discharge under Supercritical conditions" by C. H. Zhang, J. M. K. MacAlpine, and H. Akiyama AU - Lock, Evgeniya H. AU - Saveliev, Alexei V. AU - Kennedy, Lawrence A. T2 - IEEE TRANSACTIONS ON PLASMA SCIENCE AB - Generation of plasma under supercritical conditions is of fundamental and applied interest. In this paper, the reduced electric fields required for breakdown of gaseous and supercritical carbon dioxide are comparatively analyzed for planar and coaxial cylindrical geometries. The indirect comparison of measured breakdown voltages suggests an essential change in the ionization mechanism both for uniform and nonuniform fields DA - 2006/10// PY - 2006/10// DO - 10.1109/tps.2006.883368 VL - 34 IS - 5 SP - 2467-2468 SN - 0093-3813 KW - breakdown KW - corona KW - discharge KW - supercritical ER - TY - JOUR TI - Methanol and dimethyl sulfide removal by pulsed corona part I: Experiment AU - Lock, E. H. AU - Saveliev, A. V. AU - Kennedy, L. A. T2 - PLASMA CHEMISTRY AND PLASMA PROCESSING DA - 2006/12// PY - 2006/12// DO - 10.1007/s11090-006-9011-9 VL - 26 IS - 6 SP - 527-542 SN - 1572-8986 KW - low temperature plasma KW - pulsed corona discharge KW - VOC KW - methanol KW - dimethyl sulfide ER - TY - JOUR TI - Flame synthesis of molybdenum oxide whiskers AU - Merchan-Merchan, W AU - Saveliev, AV AU - Kennedy, LA T2 - CHEMICAL PHYSICS LETTERS AB - The spectacular growth of molybdenum oxide hollow and solid whiskers with rectangular and circular cross-section is reported. The synthesis is performed using molybdenum probes inserted in an opposed-flow methane oxy-flame. The solid rectangular and circular whiskers with characteristic cross-sectional dimensions from 100 nm to 4 μm and hollow rectangular channels with wall thickness from 50 to 100 nm are grown on 1-mm diameter probes inserted at the high temperature zone on the oxidizer side of the flame front. The shape and structural parameters of grown whisker materials strongly depend on the flame position (temperature) and probe diameter. Well-defined elongated crystal structures with a large number of facets and complex symmetry were grown on the probes with a diameter of 0.25 mm. DA - 2006/4/28/ PY - 2006/4/28/ DO - 10.1016/j.cplett.2006.02.040 VL - 422 IS - 1-3 SP - 72-77 SN - 0009-2614 ER - TY - JOUR TI - Flame nanotube synthesis in moderate electric fields: From alignment and growth rate effects to structural variations and branching phenomena AU - Merchan-Merchan, Wilson AU - Saveliev, Alexel V. AU - Kennedy, Lawrence A. T2 - CARBON AB - The flame synthesis of carbon nanotubes (CNTs) coupled with application of moderate electric fields is studied experimentally as a means to control CNTs growth rates and morphology. The nanotubes are grown on a conductive metal-based catalytic probe positioned at the fuel side of the opposed flow oxy-flame. The probe was connected to an external voltage source to generate radial electric fields on its surface. At low applied voltages (from 0.3 to 2 V), the effect of the electric field on alignment and growth rate enhancement revealed the generation of vertically aligned carbon nanotube (VACNT) arrays with uniform distribution of CNT diameters. Further increases of the applied voltage resulted in structural modifications of the generated nanotubes. In particular, helically coiled CNTs were observed at applied voltages of ∼3 V. At higher voltages the arrays contained multi-walled CNTs with fascinating modified morphologies such as Y, T, and multi-junction patterns. Analysis of the samples generated at applied voltage of 5 V showed the presence of particle sprouting and early CNT junctions in the form of small bumps extruding from the outer surface of the CNTs. Analysis of material samples synthesized at 12 and 25 V showed the presence of fully branched CNT structures. DA - 2006/12// PY - 2006/12// DO - 10.1016/j.carbon.2006.06.025 VL - 44 IS - 15 SP - 3308-3314 SN - 0008-6223 KW - carbon nanotubes KW - combustion KW - electron microscopy KW - microstructure ER - TY - JOUR TI - The effects of cellular contraction on aortic valve leaflet flexural stiffness AU - David Merryman, W. AU - Shadow Huang, Hsiao-Ying AU - Schoen, Frederick J. AU - Sacks, Michael S. T2 - Journal of Biomechanics AB - The aortic valve (AV) leaflet contains a heterogeneous interstitial cell population composed predominantly of myofibroblasts, which contain both fibroblast and smooth muscle cell characteristics. The focus of the present study was to examine aortic valve interstitial cell (AVIC) contractile behavior within the intact leaflet tissue. Circumferential strips of porcine AV leaflets were mechanically tested under flexure, with the AVIC maintained in the normal, contracted, and contraction-inhibited states. Leaflets were flexed both with (WC) and against (AC) the natural leaflet curvature, both before and after the addition of 90 mM KCl to elicit cellular contraction. In addition, a natural basal tonus was also demonstrated by treating the leaflets with 10 μM thapsigargin to completely inhibit AVIC contraction. Results revealed a 48% increase in leaflet stiffness with AVIC contraction (from 703 to 1040 kPa, respectively) when bent in the AC direction (p=0.004), while the WC direction resulted only in 5% increase (from 491 to 516.5 kPa, respectively—not significant) in leaflet stiffness in the active state. Also, the loss of basal tonus of the AVIC population with thapsigargin treatment resulted in 76% (AC, p=0.001) and 54% (WC, p=0.036) decreases in leaflet stiffness at 5 mM KCl levels, while preventing contraction with the addition of 90 mM KCl as expected. We speculate that the observed layer dependent effects of AVIC contraction are primarily due to varying ECM mechanical properties in the ventricularis and fibrosa layers. Moreover, while we have demonstrated that AVIC contractile ability is a significant contributor to AV leaflet bending stiffness, it most likely serves a role in maintaining AV leaflet tissue homeostasis that has yet to be elucidated. DA - 2006/1// PY - 2006/1// DO - 10.1016/j.jbiomech.2004.11.008 VL - 39 IS - 1 SP - 88-96 J2 - Journal of Biomechanics LA - en OP - SN - 0021-9290 UR - http://dx.doi.org/10.1016/j.jbiomech.2004.11.008 DB - Crossref KW - myofibroblast KW - cellular contraction KW - leaflet stiffness ER - TY - CONF TI - Geometric changes in heart valve interstitial cell nuclei with transvalvular pressure AU - Huang, H.-Y. S. AU - Sacks, M. S. C2 - 2006/// C3 - 5th World Congress of Biomechanics, Munich, Germany, July 29-August 4, 2006 DA - 2006/// SP - 5640 ER - TY - JOUR TI - Numerical simulation of the formation of constricted waterjets in hydroentangling nozzles - Effects of nozzle geometry AU - Anantharamaiah, N. AU - Tafreshi, H. Vahedi AU - Pourdeyhimi, B. T2 - CHEMICAL ENGINEERING RESEARCH & DESIGN AB - The role of nozzle geometry on the formation of constricted waterjets, waterjets that are detached from the wall throughout the nozzle, is considered in this paper. Such waterjets have found applications in various industries, including nonwoven processing. Due to the very small time and length scales involved in high-speed flow through micro-nozzles, experimental observation of the jet formation is cumbersome if not impossible. Computer simulation, on the other hand, can improve our understanding of the waterjet formation process under such conditions. In this paper, we report on flow simulations of water through sharp-edge cone-capillary nozzles having a diameter of 128 μm at different Reynolds numbers. Unsteady-state laminar two-phase flow is considered in axisymmetric nozzles with different capillary lengths. Our simulations show the separation of the flow from the nozzle wall as it enters the orifice. Simulations have also revealed that flow reattachment occurs in cases where the nozzle capillary length is longer than a critical length. For sharpedge nozzles operating at high Reynolds numbers, the critical capillary length is found to be about 70% of the nozzle diameter. Nozzles with a capillary length less than the above critical length produce a constricted waterjet with no apparent cavitation during the jet formation. DA - 2006/3// PY - 2006/3// DO - 10.1205/cherd.05077 VL - 84 IS - A3 SP - 231-238 SN - 1744-3563 KW - waterjet KW - flow simulation KW - reattachment length KW - hydroentangling KW - nonwovens ER - TY - BOOK TI - Smart structures and materials 2006: Smart sensor monitoring systems and applications (SPIE; 6167) AU - Inaudi, D. AU - Ecke, W. AU - Culshaw, B. AU - Peters, K. J. AU - Udd, E. DA - 2006/// PY - 2006/// PB - Bellingham, Wash.: SPIE SN - 0819462209 ER - TY - JOUR TI - The onset of convection in a suspension of gyrotactic microorganisms in superimposed fluid and porous layers: Effect of vertical throughflow AU - Avramenko, A. A. AU - Kuznetsov, A. V. T2 - TRANSPORT IN POROUS MEDIA DA - 2006/11// PY - 2006/11// DO - 10.1007/s11242-005-6086-3 VL - 65 IS - 2 SP - 159-176 SN - 1573-1634 KW - vertical throughflow KW - superimposed fluid and porous layers KW - bioconvection KW - motile microorganisms ER - TY - JOUR TI - A note on permeability simulation of multifilament woven fabrics AU - Wang, Q. AU - Maze, B. AU - Tafreshi, H. Vahedi AU - Pourdeyhimi, B. T2 - CHEMICAL ENGINEERING SCIENCE AB - A conventional approach for modeling permeability of multifilament fabrics is to consider their warps and wefts to be individual thick filament made of homogeneous porous media and solve the flow equations for such monofilament fabrics. In this work, for the first time, the full 3-D geometry of an idealized multifilament woven fabric, wherein the filaments are packed in hexagonal arrangement, is generated to compute its permeability and compare with the homogeneous anisotropic lumped model of Gebart (1992. Permeability of unidirectional reinforcements for RTM. Journal of Composite Materials 26(8), 1100–1133). While a relatively good agreement is obtained, our results indicate that Gebart's model slightly underestimate the permeability of multifilament fabrics even at high yarn's solid volume fractions. DA - 2006/12// PY - 2006/12// DO - 10.1016/j.ces.2006.09.043 VL - 61 IS - 24 SP - 8085-8088 SN - 1873-4405 KW - air permeability KW - multifilament fabrics KW - CFD simulations KW - fluid flow ER - TY - BOOK TI - Thermodynamics: an engineering approach. (5th ed.) AU - Cengel, Y. A. AU - Boles, M. A. CN - TJ265 .C43 2006b DA - 2006/// PY - 2006/// PB - Boston: McGraw-Hill Higher Education SN - 0072884959 ER - TY - JOUR TI - Nonmigrating tides inferred from the Mars Odyssey and Mars Global Surveyor aerobraking data AU - Wang, L. AU - Fritts, D. C. AU - Tolson, R. H. T2 - Geophysical Research Letters DA - 2006/// PY - 2006/// VL - 33 IS - 23 ER - TY - JOUR TI - Thermo-bio-convection in porous media AU - Kuznetsov, A. V. T2 - JOURNAL OF POROUS MEDIA DA - 2006/// PY - 2006/// DO - 10.1615/JPorMedia.v9.i6.60 VL - 9 IS - 6 SP - 581-589 SN - 1934-0508 ER - TY - JOUR TI - Thermally developing forced convection in a bidisperse porous medium AU - Kuznetsov, A. V. AU - Nield, D. A. T2 - Journal of Porous Media AB - The classical Graetz methodology is applied to investigate the thermal development of forced convection in a parallel-plate channel filled by a saturated bidispersed porous medium, with walls held at constant temperature. A two-velocity two-temperature model is employed for the porous medium. The analysis leads to an expression for the local Nusselt number as a function of the dimensionless longitudinal coordinate and parameters characterizing the porous medium (macropore volume fraction, interphase heat transfer parameter, thermal conductivity ratio, and effective permeability ratio). DA - 2006/// PY - 2006/// DO - 10.1615/jpormedia.v9.i5.10 VL - 9 IS - 5 SP - 393-402 ER - TY - JOUR TI - Probabilistic robust linear parameter-varying control of an F-16 aircraft AU - Lu, Bei AU - Wu, Fen T2 - JOURNAL OF GUIDANCE CONTROL AND DYNAMICS AB - O PERATIONAL capability at high angles of attack, especially near and at post stall regimes, is critical for next generation fighter aircrafts and uninhabited aerial vehicles [1]. However, significantly large levels of modeling uncertainty are inevitably encountered inflight control design for those regimes. The sources of uncertainty include variations in mass, inertia, and center of gravity positions, uncertainty in the aerodynamic data, etc. [2]. The maneuverability at high angles of attack poses a challenging control problem that requires guaranteeing both robust stability and robust performance in the presence of large parameter variations. Traditional robust control techniques, like H1 and -synthesis, have been proven to be capable of producing robust uncertaintytolerant controllers for next generation aircrafts [2,3]. However, those techniques focus on deterministic worst-case robust analysis and synthesis, which often lead to overly conservative stability bound estimate and high control effort. Moreover, a large number of conventional deterministic problems in robustness analysis and synthesis are shown to be NP-hard. To reduce conservatism and computational complexity, one approach is to shift the meaning of robustness from its usual deterministic sense to a probabilistic one [4]. In contrast to traditional robust control techniques, only a probabilistic solution is given, and a certain risk-level should be accepted. However, such a system may be viewed as being practically robust from an engineering point of view. Algorithms derived in the probabilistic context are based on uncertainty randomization and usually called randomized algorithms, which may be divided into two families: methods based on statistical learning theory [5], and sequential methods based on subgradient iterations [6–8] or ellipsoid iterations [9,10]. The former can deal with nonconvex synthesis problems; however, it resorts to randomized search over the controller parameters to find a candidate solution. On the other hand, the sequential methods are formulated based on convex problems, thus avoiding the controller randomization issue [4]. The probabilistic robust control approach is still in the stage of algorithm development and improvement, and has not been explored in depth for flight control. The number of implementation of probabilistic techniques is therefore rather restricted. In the late 90s, Marrison and Stengel designed a linear quadratic regulator to control the nonlinear longitudinal dynamics of a hypersonic aircraft [11]. Recently, Wang and Stengel designed a robust flight control system for the high-incidence research model problem by combining stochastic robustness with nonlinear dynamic inversion [12]. Their work was based on statistical learning theory, and controllers were searched by using generic algorithms to minimize stochastic robustness cost functions. In our earlier paper, we applied an ellipsoid algorithm to design anH1 controller for a linearized F-16 longitudinal model [13]. Good stability and performance robustness have been achieved at the chosen flight condition. The motivation for this research is twofold. First, the probabilistic control design method for linear time-invariant plants in [13] is generalized to linear parameter-varying (LPV) systems. This generalization is very important because of the relevance of LPV systems to nonlinear systems. TheLPVcontrol synthesis condition is known to be formulated as a convex problemwith a set of parameterdependent linear matrix inequalities (LMIs) [14–16]. Second, the current state of the art does not allow accurate aerodynamicmodeling in the high angle of attack region. Because of its random nature, uncertainty in the aerodynamic data can be characterized using a statistical model, which can be handled effectively by the promising probabilistic robust control approach. Note that the study in this note focuses on the robustness issue with respect to the aerodynamic uncertainty at high angles of attack, and the results would be easily generalized to other parametric uncertainties, such as variations in mass and inertial properties. Because of the convex formulation of LPV control synthesis, the sequential method is more suitable for dealing with uncertainties and designing probabilistic robust LPV controllers. An ellipsoid algorithm with a stopping rule proposed by Oishi [10] is used to determine feasible solutions to LMI synthesis conditions. The paper is organized as follows. In Sec. II, the ellipsoid algorithm is presented, which either gives a probabilistic solution with high confidence or detects that there is no deterministic solution in an approximated sense. Section III first provides a brief overview of robust control problem of an uncertain LPV system, and then discusses the computational issues when the algorithm is applied to the robust LPV control problem. In Sec. IV, a robust LPV controller is designed for an F-16 aircraft with large aerodynamic uncertainty, and the robust performance is tested through nonlinear simulations. Finally, the paper concludes with a summary in Sec. V. DA - 2006/// PY - 2006/// DO - 10.2514/1.22495 VL - 29 IS - 6 SP - 1454-1460 SN - 1533-3884 ER - TY - JOUR TI - One-step green route to narrowly dispersed copper nanocrystals AU - Wu, Chunwei AU - Mosher, Brian P. AU - Zeng, Taofang T2 - JOURNAL OF NANOPARTICLE RESEARCH DA - 2006/12// PY - 2006/12// DO - 10.1007/s11051-005-9065-2 VL - 8 IS - 6 SP - 965-969 SN - 1572-896X KW - copper nanocrystals KW - green chemistry KW - ascorbic acid KW - colloids KW - environmentally ER - TY - JOUR TI - On the role of heat and mass transport during the mutual annihilation of two premixed propane-air flames AU - Ranganath, Bhargav AU - Echekki, Tarek T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER AB - Abstract The unsteady process of mutual annihilation of two stoichiometric propane–air flames in one dimension is investigated numerically in the presence of preferential (the diffusion of heat relative to mass diffusion of species) and differential diffusion (the relative mass diffusions of species) effects. These effects are found during the early stages of mutual annihilation, corresponding to preheat layers’ interactions, as well as during the merger of the reaction layers. The diffusive mobility of heat relative to the reactants results in the preheating of the reactants and associated increases in the rates of reactants’ consumption. These rates are sustained during the merger of the reaction layers due to the relative mobility of the secondary fuels, especially H 2 , which results in the build-up of radicals in the reaction zone prior to the completion of the mutual annihilation process. Preferential and differential diffusion effects also result in the formation of products of incomplete combustion at the end of this process. DA - 2006/12// PY - 2006/12// DO - 10.1016/j.ijheatmasstransfer.2006.05.029 VL - 49 IS - 25-26 SP - 5075-5080 SN - 1879-2189 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33750358100&partnerID=MN8TOARS ER - TY - JOUR TI - Linear stability analysis of the effect of vertical vibration on bioconvection in a horizontal porous layer of finite depth AU - Kuznetsov, A. V. T2 - JOURNAL OF POROUS MEDIA DA - 2006/// PY - 2006/// DO - 10.1615/JPorMedia.v9.i6.80 VL - 9 IS - 6 SP - 597-608 SN - 1934-0508 ER - TY - JOUR TI - Cluster beam deposition: a tool for nanoscale science and technology AU - Wegner, K. AU - Piseri, P. AU - Tafreshi, H. Vahedi AU - Milani, P. T2 - JOURNAL OF PHYSICS D-APPLIED PHYSICS AB - Gas phase nanoparticle production, manipulation and deposition is of primary importance for the synthesis of nanostructured materials and for the development of industrial processes based on nanotechnology. In this review we present and discuss this approach, introducing cluster sources, nanoparticle formation and growth mechanisms and the use of aerodynamic focusing methods that are coupled with supersonic expansions to obtain high intensity cluster beams with a control on nanoparticle mass and spatial distribution. The implication of this technique for the synthesis of nanostructured materials is also presented and applications are highlighted. DA - 2006/11/21/ PY - 2006/11/21/ DO - 10.1088/0022-3727/39/22/r02 VL - 39 IS - 22 SP - R439-R459 SN - 1361-6463 UR - https://publons.com/wos-op/publon/6333204/ ER - TY - JOUR TI - Boundary layer treatment of forced convection over a wedge with an attached porous substrate AU - Kuznetsov, A. V. AU - Nield, D. A. T2 - Journal of Porous Media DA - 2006/// PY - 2006/// DO - 10.1615/jpormedia.v9.i7.70 VL - 9 IS - 7 SP - 683-694 ER - TY - JOUR TI - Mean and gravity wave structures and variability in the Mars upper atmosphere inferred from Mars Global Surveyor and Mars Odyssey aerobraking densities AU - Fritts, D. C. AU - Wang, L. AU - Tolson, R. H. T2 - Journal of Geophysical Research. Space Physics DA - 2006/// PY - 2006/// VL - 111 IS - A12 SP - A12304 ER - TY - JOUR TI - Vibration analysis for damage detection in metal-to-metal adhesive joints AU - Pandurangan, P. AU - Buckner, G. D. T2 - EXPERIMENTAL MECHANICS DA - 2006/10// PY - 2006/10// DO - 10.1007/s11340-006-8736-y VL - 46 IS - 5 SP - 601-607 SN - 1741-2765 KW - metal-to-metal adhesive joints KW - non-destructive evaluation KW - vibration analysis KW - damage detection KW - modal damping ratio ER - TY - JOUR TI - The use of functionally gradient materials in medicine AU - Narayan, Roger J. AU - Hobbs, Linn W. AU - Jin, Chunming AU - Rabiei, Afsaneh T2 - JOM DA - 2006/7// PY - 2006/7// DO - 10.1007/s11837-006-0142-5 VL - 58 IS - 7 SP - 52-56 SN - 1543-1851 ER - TY - JOUR TI - The onset of convection in a bidisperse porous medium AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER AB - The classical Rayleigh–Bénard theory, for the onset of convection in a horizontal layer uniformly heated from below, has been applied to a bidisperse porous medium. The linear stability analysis leads to an expression for the critical Rayleigh number as a function of a Darcy number, two volume fractions, a permeability ratio, a thermal capacity ratio, a thermal conductivity ratio, an inter-phase heat transfer parameter and an inter-phase momentum transfer parameter. DA - 2006/8// PY - 2006/8// DO - 10.1016/j.ijheatmasstransfer.2006.02.008 VL - 49 IS - 17-18 SP - 3068-3074 SN - 1879-2189 ER - TY - JOUR TI - Strong-field electromagnetic stirring in the vertical gradient freeze process with a submerged heater AU - Ma, Nancy AU - Walker, John S. T2 - JOURNAL OF CRYSTAL GROWTH AB - This paper treats a steady, axisymmetric melt motion due to electromagnetic (EM) stirring during vertical gradient freeze crystal growth with a submerged heater. There is a radial electric current through the melt from a graphite electrode around the crystal and melt to another graphite electrode at the center of the heater. There is a strong axial magnetic field produced by an external solenoid. Solutions are presented for the azimuthal and meridional velocities in the subregions of the melt. The melt motion depends on the electric currents through the crystal, even though the electrical conductivity of the crystal is much less than that of the melt. DA - 2006/5/15/ PY - 2006/5/15/ DO - 10.1016/j.jcrysgro.2006.02.041 VL - 291 IS - 1 SP - 249-257 SN - 1873-5002 KW - fluid flow KW - magnetic fields KW - stirring KW - gradient freeze technique KW - growth from the melt KW - single crystal growth ER - TY - JOUR TI - Rapid synthesis of gold and platinum nanoparticles using metal displacement reduction with sonomechanical assistance AU - Wu, Chunwei AU - Mosher, Brian P. AU - Zeng, Taofang T2 - CHEMISTRY OF MATERIALS AB - We present a new route for preparation of metallic nanoparticles by sonomechanical-assisted metal displacement reduction. Au and Pt nanoparticles with sizes around 10 and 6 nm, respectively, and narrow size distributions were synthesized via the displacement reduction of precursor salts of HAuCl4·3H20 and H2PtCl6·6H2O by Cu and Fe foils, respectively. DA - 2006/6/27/ PY - 2006/6/27/ DO - 10.1021/cm052400x VL - 18 IS - 13 SP - 2925-2928 SN - 1520-5002 ER - TY - JOUR TI - Processing and characterization of a new composite metal foam AU - Rabiei, Afsaneh AU - Vendra, Lakshmi AU - Reese, Nick AU - Young, Noah AU - Neville, Brian P. T2 - MATERIALS TRANSACTIONS AB - New closed cell composite metal foam has been processed using both casting and powder metallurgy (PM) techniques. The foam is comprised of steel hollow spheres packed into a dense arrangement, with the interstitial spaces between spheres occupied with a solid metal matrix. Using the casting technique, an aluminum alloy infiltrates the interstitial spaces between steel spheres. In the PM technique, steel spheres and steel powder are sintered to form a solid, closed cell structure. The measured densities of the Al-Fe composite foam, low carbon steel foam, and stainless steel foam are 2.4, 2.6, and 2.9 g/cm3 with relative densities of 42, 34, and 37%, respectively.The composite metal foams composite materials developed in this study displayed superior compressive strength as compared to any other foam being produced with similar materials. The compressive strength of the cast Al-Fe foam averaged 67 MPa over a region of 10 to 50% strain, while the low carbon steel PM foam averaged 76 MPa over the same strain region, and the stainless steel PM foam averaged 136 MPa over the same region. Densification began at approximately 50% for the cast foam and ranged from 50 to 55% for the PM foams. The strength to density ratio of the product of both techniques exceeded twice that of foams processed using other techniques with similar materials. DA - 2006/9// PY - 2006/9// DO - 10.2320/matertrans.47.2148 VL - 47 IS - 9 SP - 2148-2153 SN - 1347-5320 KW - metal foam KW - energy absorption KW - hollow spheres KW - compression strength KW - plateau stress ER - TY - JOUR TI - Parametric study of modified vertical bridgman growth in a rotating magnetic field AU - Wang, X. AU - Ma, N. AU - Bliss, D. F. AU - Iseler, G. W. AU - Becla, P. T2 - JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER AB - Using the vertical Bridgman process, a single semiconductor crystal is grown by the solidification of an initially molten semiconductor (melt) contained in a crucible. In addition to the main Bridgman heater, a submerged heater is added that separates the melt into two zones, i.e., an upper melt and a lower melt that is continuously replenished with fluid from the upper melt to offset the rejection of species along the crystal-melt interface. As crystal growth progresses, the crucible is slowly lowered to maintain a constant lower melt depth. An externally applied rotating magnetic field produced by a synchronous motor stator is used to control the transport of the electrically conducting molten semiconductor. This paper treats the flow of a molten semiconductor and the dopant transport during the vertical Bridgman process with a submerged heater and with a transverse rotating magnetic field. This paper also investigates the effects of the crystal radius, the melt depth, the strength of the magnetic field, and the number of poles in the inductor on the dopant distributions in the crystal. DA - 2006/// PY - 2006/// DO - 10.2514/1.19572 VL - 20 IS - 3 SP - 384-388 SN - 1533-6808 ER - TY - JOUR TI - One-Dimensional Turbulence-based closure for turbulent non-premixed flames AU - Ranganath, Bhargav AU - Echekki, Tarek T2 - PROGRESS IN COMPUTATIONAL FLUID DYNAMICS AB - A new One-Dimensional Turbulence (ODT) based closure model for turbulent non-premixed flames is proposed. The model is based on the tabulation of scalar statistics based on two parameters, which measure the extent of mixing and entrainment. The table is generated using different realisations of stand-alone ODT simulations of turbulent jet diffusion flames. The table look-up process is coupled with a Reynolds-Averaged Navier-Stokes (RANS) computation. The scope of the ODT formulation is to predict thermo-chemical scalars statistics in sample space; while its coupling with RANS reproduces these statistics in 3D space. The resulting formulation yields reasonably good agreement with experimental data. DA - 2006/// PY - 2006/// DO - 10.1504/PCFD.2006.010966 VL - 6 IS - 7 SP - 409-418 SN - 1741-5233 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33845486306&partnerID=MN8TOARS KW - One-Dimensional Turbulence (ODT) KW - turbulent combustion modelling KW - the flamelet model KW - turbulent non-premixed combustion ER - TY - JOUR TI - Modeling of grain-boundary effects and intergranular and transgranular failure in polycrystalline intermetallics AU - Kameda, T. AU - Zikry, M. A. AU - Rajendran, A. M. T2 - METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE DA - 2006/7// PY - 2006/7// DO - 10.1007/BF02586131 VL - 37A IS - 7 SP - 2107-2115 SN - 1073-5623 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33745933649&partnerID=MN8TOARS ER - TY - JOUR TI - Microstructural study of titanium-palladium-nickel base thin film shape memory alloys AU - Lee, JW AU - Thomas, B AU - Rabiei, A T2 - THIN SOLID FILMS AB - Abstract A new generation of thin film shape memory alloys has been developed with 1.65 μm thickness for micro-actuator applications. In this work, the microstructure of thin film Titanium–Palladium–Nickel (TiPdNi) shape memory alloys deposited using ion beam assisted deposition from a Ti50Pd30Ni20 target is studied. The TiPdNi thin films were deposited with and without substrate heating during deposition. As-deposited films without substrate heating were found to be amorphous. Deposition on heated substrate produced a dense, columnar crystalline structure. Microstructures of bulk TiPdNi thin films as well as the interfacial region between the film and substrate were characterized by various techniques including transmission electron microscope, scanning transmission electron microscope, scanning electron microscope-energy dispersive X-ray spectroscopy and scanning transmission electron microscope-energy dispersive X-ray spectroscopy. A transition layer with 70 nm thickness is observed at the interface between the bulk film and silicon substrate. It is composed of three layers; two amorphous layers above the silicon substrate and a 50 nm thick twin absent layer, which was identified as B2 austenite phase by Fourier spectra analysis. In the bulk film, nano-scale grains in the range of 80–200 nm were observed. The width of twin band of the film was very narrower in the range of ∼5 nm. DA - 2006/4/3/ PY - 2006/4/3/ DO - 10.1016/j.tsf.2005.11.027 VL - 500 IS - 1-2 SP - 309-315 SN - 0040-6090 KW - shape memory alloy KW - deposition process KW - transmission electron spectroscopy KW - crystallization ER - TY - JOUR TI - Laminar airflow and nanoparticle or vapor deposition in a human nasal cavity model AU - Shi, H. AU - Kleinstreuer, C. AU - Zhang, Z. T2 - JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME AB - The transport and deposition of nanoparticles, i.e., dp = 1-2 nm, or equivalent vapors, in the human nasal cavities is of interest to engineers, scientists, air-pollution regulators, and healthcare officials alike. Tiny ultrafine particles, i.e., dp < or = 5 nm, are of special interest because they are most rapidly absorbed and hence have an elevated toxic or therapeutic impact when compared to larger particles. Assuming transient laminar 3-D incompressible flow in a representative human nasal cavity, the cyclic airflow pattern as well as local and overall nanoparticle depositions were computationally simulated and analyzed. The focus was on transient effects during inhalation/exhalation as compared to the steady-state assumption typically invoked. Then, an equation for a matching steady-state inhalation flow rate was developed that generates the same deposition results as cyclic inhalation. Of special interest is the olfactory region where the narrow channel surfaces receive only about one-half of a percent of the inhaled nanoparticles because the airflow bypasses these recesses located in the superior-most portions in the geometrically complex nasal cavities. DA - 2006/10// PY - 2006/10// DO - 10.1115/1.2244574 VL - 128 IS - 5 SP - 697-706 SN - 1528-8951 ER - TY - JOUR TI - Investigation of feasibility of developing intelligent firefighter-protective garments based on the utilization of a water-injection system AU - Chitrphiromsri, P AU - Kuznetsov, AV AU - Song, G AU - Barker, RL T2 - NUMERICAL HEAT TRANSFER PART A-APPLICATIONS AB - ABSTRACT This research develops a new approach to designing and creating a prototype of an intelligent firefighter thermal-protective garment. During a flash fire exposure, this intelligent garment will absorb a significant amount of the incident heat flux due to evaporation of the injected water, thus limiting the temperature increase and the total heat flux to the firefighter's skin. A comprehensive mathematical model of heat and mass transport in the fabric layer during the flash fire exposure is suggested and numerically implemented using a finite-volume technique. A computational investigation is performed to optimize the performance of this novel garment system in terms of the activation temperature and the necessary amount of injected water. DA - 2006/9/15/ PY - 2006/9/15/ DO - 10.1080/10407780500359869 VL - 49 IS - 5 SP - 427-450 SN - 1521-0634 ER - TY - CHAP TI - Friction clutches AU - Dow, T. A. T2 - Mechanical design handbook: measurement, analysis, and control of dynamic sysytems A2 - Rothbart, H. A. A2 - Brown, T. H., Jr. PY - 2006/// PB - New York, NY: McGraw-Hill SN - 0071466363 ER - TY - CHAP TI - Friction brakes AU - Dow, T. A. T2 - Mechanical design handbook: measurement, analysis, and control of dynamic sysytems A2 - Rothbart, H. A. A2 - Brown, T. H., Jr. PY - 2006/// PB - New York, NY: McGraw-Hill SN - 0071466363 ER - TY - JOUR TI - Computational analysis of type II endoleaks in a stented abdominal aortic aneurysm model AU - Li, Z. AU - Kleinstreuer, C. T2 - JOURNAL OF BIOMECHANICS AB - Insertion of a stent-graft into an aneurysm to form a new (synthetic) blood vessel and prevent the weakened artery wall from rupture is an attractive surgical intervention when compared to traditional open surgery. However, focusing on a stented abdominal aortic aneurysm (AAA), post-operative complications such as endoleaks may occur. An endoleak is the net influx of blood during the cardiac cycle into the cavity (or sac) formed by the stent-graft and the AAA wall. A natural endoleak source may stem from one or two secondary branches leading to and from the aneurysm, labeled types IIa and IIb endoleaks. Employing experimentally validated fluid-structure interaction solvers, the transient 3-D lumen and cavity blood flows, wall movements, pressure variations, maximum wall stresses and migration forces were computed for types IIa and IIb endoleaks. Simulation results indicate that the sac pressure caused by these endoleaks depends largely on the inlet branch pressure, where the branch inlet pressure increases, the sac pressure may reach the systemic level and AAA-rupture is possible. The maximum wall stress is typically located near the anterior-distal side in this model, while the maximum stent-graft stress occurs near the bifurcating point, in both cases, due to local stress concentrations. The time-varying leakage rate depends on the pressure difference between AAA sac and inlet branch. In contrast, the stent-graft migration force is reduced by type II endoleaks because it greatly depends on the pressure difference between the stent-graft and the aneurysm cavity. DA - 2006/// PY - 2006/// DO - 10.1016/j.jbiomech.2005.09.002 VL - 39 IS - 14 SP - 2573-2582 SN - 1873-2380 KW - abdominal aortic aneurysm KW - stent-graft KW - type II endoleaks KW - computational fluid-structure interaction analysis KW - sac pressure KW - wall stress KW - estimation of aneurysm-rupture risk KW - theoretical stent-graft migration ER - TY - JOUR TI - A sensor placement strategy for the hybrid adaptive feedforward observer AU - Tran, CM AU - Southward, SC T2 - JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME AB - A sensor placement technique is proposed for implementing the hybrid adaptive feedforward observer. The observer is a conventional dynamic observer augmented with an adaptive feedforward component for estimating the effect of persistent, nonstationary disturbances. The placement technique searches for the least possible number of sensors that satisfy two criteria, the observability of the plant, and the lowest condition number of the error dynamic system's state matrix. Demonstration was performed on a one-dimensional acoustic duct. The results show that the proposed technique is an effective guideline for identifying the optimal sensor locations. DA - 2006/6// PY - 2006/6// DO - 10.1115/1.2196421 VL - 128 IS - 2 SP - 449-452 SN - 0022-0434 ER - TY - JOUR TI - Variable turbulent Schmidt-number formulation for scramjet applications AU - Xiao, X AU - Edwards, , JR AU - Hassan, HA AU - Cutler, AD T2 - AIAA JOURNAL AB - In high speed engines, thorough turbulent mixing of fuel and air is required to obtain high performance and high efficiency. Thus, the ability to predict turbulent mixing is crucial in obtaining accurate numerical simulation of an engine and its performance. Current state of the art in CFD simulation is to assume both turbulent Prandtl number and Schmidt numbers to be constants. However, since the mixing of fuel and air is inversely proportional to the Schmidt number, a value of 0.45 for the Schmidt number will produce twice as much diffusion as that with a value of 0.9. Because of this, current CFD tools and models have not been able to provide the needed guidance required for the efficient design of a scramjet engine. The goal of this investigation is to develop the framework needed to calculate turbulent Prandtl and Schmidt numbers as part of the solution. This requires four additional equations: two for the temperature variance and its dissipation rate and two for the concentration variance and its dissipation rate. In the current investigation emphasis will be placed on studying mixing without reactions. For such flows, variable Prandtl number does not play a major role in determining the flow. This, however, will have to be addressed when combustion is present. The approach to be used is similar to that used to develop the k-zeta model. In this approach, relevant equations are derived from the exact Navier-Stokes equations and each individual correlation is modeled. This ensures that relevant physics is incorporated into the model equations. This task has been accomplished. The final set of equations have no wall or damping functions. Moreover, they are tensorially consistent and Galilean invariant. The derivation of the model equations is rather lengthy and thus will not be incorporated into this abstract, but will be included in the final paper. As a preliminary to formulating the proposed model, the original k-zeta model with constant turbulent Prandtl and Schmidt numbers is used to model the supersonic coaxial jet mixing experiments involving He, O2 and air. DA - 2006/3// PY - 2006/3// DO - 10.2514/1.15450 VL - 44 IS - 3 SP - 593-599 SN - 0001-1452 ER - TY - JOUR TI - Shear punch tests for a bulk metallic glass AU - Guduru, R. K. AU - Darling, K. A. AU - Scattergood, R. O. AU - Koch, C. C. AU - Murty, K. L. AU - Bakkal, M. AU - Shih, A. J. T2 - INTERMETALLICS AB - A shear punch test technique was used for characterization of the mechanical properties of Zr–5Ti–17.9Cu–14.6Ni–10Al bulk metallic glass. The ultimate shear stress values matched very closely with values derived from uniaxial compression tests reported in the literature. This is consistent with a lack of pressure sensitivity in compression reported for this particular metallic glass. Deformation response was strain rate insensitive up to a critical rate, beyond which softening occurred. The latter was attributed to thermal heating effects. DA - 2006/12// PY - 2006/12// DO - 10.1016/j.intermet.2006.01.052 VL - 14 IS - 12 SP - 1411-1416 SN - 1879-0216 KW - glasses metallic KW - mechanical properties at ambient temperature KW - fracture stress KW - mechanical properties, theory KW - mechanical testing ER - TY - JOUR TI - Residual stresses in TiPdNi base thin film shape memory alloys AU - Baldwin, E. AU - Thomas, B. AU - Lee, J. W. AU - Rabiei, A. T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING AB - TiPdNi thin films with less than 2 μm thickness were produced using ion beam assisted deposition (IBAD) on heated and unheated substrates. Films deposited on unheated substrates were found to be amorphous, and subsequently annealed to induce crystallization. Residual stresses in the films were evaluated using the Stoney equation after deposition, and after annealing. Films deposited using IBAD on unheated substrates were found to have slight compressive stress (−22.4 MPa) while films deposited on heated substrates had a moderate tensile stress (176.2 MPa). Annealed films experienced extensive tensile stress (598.3 MPa), resulting in film failure. DA - 2006/10/25/ PY - 2006/10/25/ DO - 10.1016/j.msea.2006.06.123 VL - 434 IS - 1-2 SP - 124-130 SN - 0921-5093 KW - thin film KW - residual stress KW - shape memory alloys KW - annealing KW - ion beam assisted deposition ER - TY - JOUR TI - Numerical investigation of thinning of the intercellular bridge during cell cytokinesis AU - Kuznetsov, A. V. AU - Xiang, Ping T2 - INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER AB - This paper develops a numerical model for intercellular bridge dynamics during the final stages of cell division known as cell cytokinesis. The aim of this research is to provide understanding as well as a quantitative description of transport processes during formation and thinning of the intercellular bridge. From a microfluidic standpoint, intercellular bridge is a squeezing microchannel or a squeezing pump. The rate of pumping based on squeezing increases with increased squeezing tension, which is determined by the number of myosin-II molecular motors recruited into the intercellular bridge region. DA - 2006/11// PY - 2006/11// DO - 10.1016/j.icheatmasstransfer.2006.05.005 VL - 33 IS - 9 SP - 1071-1078 SN - 1879-0178 KW - cytokinesis KW - capillary thinning KW - intercellular bridge KW - numerical modeling ER - TY - JOUR TI - Microstructural modeling of grain subdivision and large strain inhomogeneous deformation modes in f.c.c. crystalline materials AU - Rezvanian, O. AU - Zikry, M. A. AU - Rajendran, A. M. T2 - MECHANICS OF MATERIALS AB - In this study, evolution equations related to a heterogeneous microstructure that is physically representative of the densities and dimensions of dislocation-cells and walls have been formulated and coupled to a multiple-slip crystal plasticity formulation. Specialized finite-element methodologies have then been used to investigate how an imbalance in shear-strain amplitudes can result in deformation band formation in a cube-oriented aluminum single crystal subjected to strains of up to 30% under rolling deformation. It has been shown that a change in the microstructural morphology from matrix to transition bands occurs as the dislocation-cell size increases with decreases in the stored dislocation density and as a function of slip-system structure and orientation. Comparisons with experimental measurements and observations clearly indicate that the transition and matrix bands can occur in cube orientations as a consequence of shear strain imbalance on active slip-systems. DA - 2006/12// PY - 2006/12// DO - 10.1016/j.mechmat.2005.12.006 VL - 38 IS - 12 SP - 1159-1169 SN - 0167-6636 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33746933462&partnerID=MN8TOARS KW - grain subdivision KW - deformation band KW - rolling deformation KW - dislocation density KW - inhomogeneous microstructure KW - shear amplitude imbalance ER - TY - JOUR TI - Isotonic and hypertonic saline droplet deposition in a human upper airway model AU - Zhang, Zhe AU - Kleinstreuer, Clement AU - Kim, Chong S. T2 - JOURNAL OF AEROSOL MEDICINE-DEPOSITION CLEARANCE AND EFFECTS IN THE LUNG AB - The evaporative and hygroscopic effects and deposition of isotonic and hypertonic saline droplets have been simulated from the mouth to the first four generations of the tracheobronchial tree under laminar-transitional-turbulent inspiratory flow conditions. Specifically, the local water vapor transport, droplet evaporation rate, and deposition fractions are analyzed. The effects of inhalation flow rates, thermodynamic air properties and NaCl-droplet concentrations of interest are discussed as well. The validated computer simulation results indicate that the increase of NaCl-solute concentration, increase of inlet relative humidity, or decrease of inlet air temperature may reduce water evaporation and increase water condensation at saline droplet surfaces, resulting in higher droplet depositions due to the increasing particle diameter and density. However, solute concentrations below 10% may not have a very pronounced effect on droplet deposition in the human upper airways. DA - 2006/// PY - 2006/// DO - 10.1089/jam.2006.19.184 VL - 19 IS - 2 SP - 184-198 SN - 0894-2684 KW - aerosol deposition KW - computational fluid-particle dynamics KW - droplet vaporization and hygroscopicity KW - isotonic and hypertonic saline droplets ER - TY - JOUR TI - Forced convection with laminar pulsating flow in a saturated porous channel or tube AU - Kuznetsov, A. V. AU - Nield, D. A. T2 - TRANSPORT IN POROUS MEDIA DA - 2006/12// PY - 2006/12// DO - 10.1007/s11242-006-6791-6 VL - 65 IS - 3 SP - 505-523 SN - 1573-1634 KW - forced convection KW - pulsating flow KW - parallel-plates channel KW - circular duct ER - TY - JOUR TI - Finite element model for embedded fiber Bragg grating sensor AU - Prabhugoud, M AU - Peters, K T2 - SMART MATERIALS AND STRUCTURES AB - This paper presents an integrated formulation for the calculation of the spectral response of a fiber Bragg grating sensor embedded in a host material system, as a function of the loading applied to the host structure. In particular, the calculation of the transverse strain sensitivity of a fiber Bragg grating sensor through the calculation of the change in effective index (or indices) of refraction of the fiber cross-section due to the applied load is presented in detail. For the calculation of the fiber propagation constants, a two-step finite element formulation is used incorporating the optical, geometric and material properties of the cross-section. Once the propagation constants and principal optical axes are known along the fiber, a modified transfer matrix method is applied to calculate the spectral response of the FBG. It is shown that the FE formulation yields close agreement with previous methods for benchmark diametrical compression cases. However, the current method provides the potential to evaluate the effects of high strain gradients across the optical fiber core present in some loading applications. DA - 2006/4// PY - 2006/4// DO - 10.1088/0964-1726/15/2/038 VL - 15 IS - 2 SP - 550-562 SN - 1361-665X ER - TY - JOUR TI - Estimating model uncertainty using confidence interval networks: Applications to robust control AU - Buckner, Gregory D. AU - Choi, Heeju AU - Gibson, Nathan S. T2 - JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME AB - Robust control techniques require a dynamic model of the plant and bounds on model uncertainty to formulate control laws with guaranteed stability. Although techniques for modeling dynamic systems and estimating model parameters are well established, very few procedures exist for estimating uncertainty bounds. In the case of H∞ control synthesis, a conservative weighting function for model uncertainty is usually chosen to ensure closed-loop stability over the entire operating space. The primary drawback of this conservative, “hard computing” approach is reduced performance. This paper demonstrates a novel “soft computing” approach to estimate bounds of model uncertainty resulting from parameter variations, unmodeled dynamics, and nondeterministic processes in dynamic plants. This approach uses confidence interval networks (CINs), radial basis function networks trained using asymmetric bilinear error cost functions, to estimate confidence intervals associated with nominal models for robust control synthesis. This research couples the “hard computing” features of H∞ control with the “soft computing” characteristics of intelligent system identification, and realizes the combined advantages of both. Simulations and experimental demonstrations conducted on an active magnetic bearing test rig confirm these capabilities. DA - 2006/9// PY - 2006/9// DO - 10.1115/1.2199855 VL - 128 IS - 3 SP - 626-635 SN - 1528-9028 ER - TY - JOUR TI - Electromagnetic stirring in crystal growth processes AU - Ma, N. AU - Walker, J. S. T2 - Fluid Dynamics & Materials Processing : FDMP DA - 2006/// PY - 2006/// VL - 2 IS - 2 SP - 119-125 ER - TY - JOUR TI - Comparing modified vertical gradient freezing with rotating magnetic fields or with steady magnetic and electric fields AU - Wang, X AU - Ma, N AU - Bliss, DF AU - Iseler, GW AU - Becla, P T2 - JOURNAL OF CRYSTAL GROWTH AB - This investigation treats the flow of molten gallium-antimonide and the dopant transport during the vertical gradient freezing process using submerged heater growth. A rotating magnetic field or a combination of steady magnetic and steady electric fields is used to control the melt motion. This paper compares the effects of these externally applied fields on the transport in the melt and on the dopant segregation in the crystal. Crystal growth in a combination of steady magnetic and electric fields produces a crystal with more radial and axial dopant homogeneity than growth in a rotating magnetic field. DA - 2006/1/25/ PY - 2006/1/25/ DO - 10.1016/j.jcrysgro.2005.11.036 VL - 287 IS - 2 SP - 270-274 SN - 1873-5002 KW - fluid flows KW - magnetic fields KW - segregation KW - growth from melt KW - VGF technique ER - TY - JOUR TI - The onset of thermo-bioconvection in a shallow fluid saturated porous layer heated from below in a suspension of oxytactic microorganisms AU - Kuznetsov, AV T2 - EUROPEAN JOURNAL OF MECHANICS B-FLUIDS AB - The aim of this paper is to present a continuum model for thermo-bioconvection of oxytactic bacteria in a porous medium and investigate the combined effects of microorganisms' upswimming and heating from below on the stability of bioconvection in a horizontal layer filled with a fluid saturated porous medium. Different from traditional bioconvection, thermo-bioconvection has two destabilizing mechanisms that contribute to creating the unstable density stratification. This problem may be relevant to a number of geophysical applications, such as the investigation of the dynamics of oxytactic species of thermophiles (heat loving microorganisms) living in hot springs, microbial-enhanced oil recovery, and modeling oil- and gas-bearing sedimentary basins. The utilization of the Galerkin method to solve a linear stability problem leads to a correlation between the critical value of the bioconvection Rayleigh number and the traditional “thermal” Rayleigh number. DA - 2006/// PY - 2006/// DO - 10.1016/j.euromechflu.2005.06.003 VL - 25 IS - 2 SP - 223-233 SN - 1873-7390 KW - bioconvection KW - oxytactic microorganisms KW - porous media KW - stability ER - TY - JOUR TI - Solute segregation during modified vertical gradient freezing of alloyed compound semiconductor crystals with magnetic and electric fields AU - Wang, X. AU - Ma, N. AU - Bliss, D. F. AU - Iseler, G. W. T2 - INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER AB - Single crystals of gallium–aluminum–antimonide are solidified from a solution of molten gallium–antimonide and aluminum–antimonide. Electromagnetic stirring can be induced in the melt by applying a weak electric field together with a weak axial magnetic field. This paper presents a numerical model which uses a Chebyshev spectral collocation method with a second-order implicit time integration scheme with Gauss–Lobatto collocation points. This investigation models the unsteady motion and solute transport during vertical gradient freezing by submerged heater growth with electromagnetic stirring. The radial homogeneity in the crystal improves as the solute’s concentration increases. DA - 2006/9// PY - 2006/9// DO - 10.1016/j.ijheatmasstransfer.2006.03.008 VL - 49 IS - 19-20 SP - 3429-3438 SN - 1879-2189 ER - TY - JOUR TI - Progressive die sequence design for deep drawing round cups using finite element analysis AU - Altan, T AU - Jain, NT AU - Shi, , XX AU - Ngaile, G AU - Pax, B AU - Harman, B AU - Homan, G T2 - JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME AB - A methodology for progressive die sequence design for forming round cups using finite element method (FEM) based simulations is discussed. The process sequence design developed was applied to forming of an automotive part and was compared with the design obtained from past experience. The methodology proposed in this paper has shown that the integration of design experience and FEM simulations can enhance the robustness of the procedure for die design sequence and reduces the die development cost considerably. DA - 2006/2// PY - 2006/2// DO - 10.1115/1.2039942 VL - 128 IS - 1 SP - 366-369 SN - 1528-8935 ER - TY - JOUR TI - Particle-reinforced water-based organic-inorganic nanocomposite coatings for tailored applications AU - Mosher, Brian P. AU - Wu, Chunwei AU - Sun, Tao AU - Zeng, Taofang T2 - JOURNAL OF NON-CRYSTALLINE SOLIDS AB - We report the synthesis and characterization of three particle-reinforced water-based nanocomposite coatings. The films are sol–gel derived using non-ionic surfactant, with aluminum perchlorate (Al(ClO4)3) as a catalyst and 3-glycidoxypropyltrimethoxysilane (GPTMS) as precursor. Through the aid of nanoparticle colloids and a minute amount of catalyst, dense, hard and monolithic materials are obtained. Incorporating metal oxide nanoparticles brings forth unique properties, such as absorbing harmful UV radiation. Silica colloid composites provide greatly enhanced mechanical properties without modifying the unique optical properties of inorganic materials. Water-based synthesis of these coatings is straightforward and produces very few harmful byproducts, making them ideal materials in industry. The materials presented are relatively hard and abrasion resistant with very good adhesion; two of the coatings are UV absorbent. Various colloids can be employed in our methods to tailor properties and resulting materials may serve applications such as optical, protective, catalytic, guest-host, and multifunctional coatings. DA - 2006/9/1/ PY - 2006/9/1/ DO - 10.1016/j.jnoncrysol.2006.05.026 VL - 352 IS - 30-31 SP - 3295-3301 SN - 1873-4812 KW - films and coatings KW - nanocomposites KW - organic-inorganic hybrids KW - sol gels (xerogels) ER - TY - JOUR TI - Numerical simulation of injection of supercritical ethylene into nitrogen AU - Star, Ana M. AU - Edwards, Jack R. AU - Lin, Kuo-Cheng AU - Cox-Stouffer, Susan AU - Jackson, Thomas A. T2 - JOURNAL OF PROPULSION AND POWER AB - A procedure for simulating the injection of supercritical ethylene into nitrogen is used to investigate aspects of the injection of supercritical fuels, considered to be an enabling technology in the design of hydrocarbons-fueled scramjet engines. The method solves the compressible Navier-Stokes equations for an ethylene/nitrogen mixture, with the thermodynamic behavior of ethylene described using the Peng-Robinson equation of state. Homogeneous equilibrium and finite-rate phase-transition models are used to describe the growth of a condensed ethylene phase in several axisymmetric and three-dimensional injector nozzles. Predictions are compared with shadowgraph and direct-lighting imaging data, mass flow rate measurements, mole-fraction and temperature measurements in the jet mixing zone, and wall pressure distributions. Qualitative trends relating to jet structure, the appearance of a condensed phase, and the effects of back pressure and injectant temperature are in good agreement with experimental results but indicate the need for improved characterization of the nozzle flow before injection and the inclusion of a better turbulence model for the jet mixing zone. For conditions where both are applicable, a nucleation/ growth phase transition model provides a similar bulk fluid response as a homogeneous equilibrium model but also yields predictions of number density and average droplet size. DA - 2006/// PY - 2006/// DO - 10.2514/1.16621 VL - 22 IS - 4 SP - 809-819 SN - 1533-3876 ER - TY - JOUR TI - Low-velocity impact damage accumulation in woven S2-glass composite systems AU - Baucom, J. N. AU - Zikry, M. A. AU - Rajendran, A. M. T2 - COMPOSITES SCIENCE AND TECHNOLOGY AB - The objective of this experimental investigation is to obtain a detailed understanding of damage accumulation in two-dimensional (2D) and three-dimensional (3D) woven glass-fiber-reinforced composite panels under repeated transverse drop-weight impact loading conditions. Measurements were obtained for impact force and energy dissipation. The radial spread of damage was smallest for the 2D laminates and largest for the 3D woven composites. The 3D composites had the greatest resistance to penetration and dissipated more total energy than the laminate system. This damage tolerance is due to unique energy absorption mechanisms, which involve the crimped portion of z-tows in the 3D composites. This is significant, since 3D architectures can provide both an inherent capability to dissipate energy over a large radial area and a greater perforation strength than comparable 2D laminate systems. DA - 2006/8// PY - 2006/8// DO - 10.1016/j.compscitech.2005.11.005 VL - 66 IS - 10 SP - 1229-1238 SN - 1879-1050 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33747351080&partnerID=MN8TOARS KW - impact behavior KW - textile composites KW - debonding KW - matrix cracking KW - delamination ER - TY - JOUR TI - Characterization of focused high frequency ultrasonic, removal of thermally fused toner from paper surfaces - an experimental study AU - Ramasubramanian, M. K. AU - Madanshetty, S. I. AU - Suwan-Acksorn, P. T2 - Appita Journal DA - 2006/// PY - 2006/// VL - 59 IS - 4 SP - 306- ER - TY - JOUR TI - A study on flow through hydroentangling nozzles and their degradation AU - Anantharamaiah, N. AU - Tafreshi, H. Vahedi AU - Pourdeyhimi, B. T2 - CHEMICAL ENGINEERING SCIENCE AB - Abstract Hydroentangling is a technique for mechanically bonding loose filaments or fibers arranged in a web. The efficiency with which the web is entangled depends on the peculiar properties of laminar high-speed waterjets used. The characteristics of such waterjets strongly depend on the operating pressure and the nozzle inlet sharpness which influence the dynamics of fluid flow. In this study, we report on experiments and CFD simulations aimed at improving our knowledge of such two-phase flows. In particular, we simulate the formation and growth of the cavitation cloud inside a sharp-edge hydroentangling nozzle at pressures ranging from 10 to 200 bars ( 5700 Re 25 600 ) . Our experimental results run at the same pressures, confirm that nozzle cavitation will cause “hydraulic flip”. Once hydraulic flip occurs, atomizing waterjets will turn into constricted laminar waterjets with long intact lengths—a necessary condition for hydroentangling. It has been observed that the nozzle inlet deteriorates under high pressures. Our CFD simulations show a striking similarity between the contours of shear stress at the nozzle inlet and the nozzle wear pattern. These findings together with the SEM elemental analysis at the nozzle inlet reveal the potential for metal oxidation around the inlet, implicating stress-induced corrosion as a major contributor to the nozzle wear. Cavitation might also be one of the mechanisms responsible for the above-mentioned wear at the inlet edge. Additionally, our water-borne solid particle tracking, confirms SEM experimental results that particle deposition can potentially play a considerable role in the deterioration of the nozzle inlet shape. DA - 2006/7// PY - 2006/7// DO - 10.1016/j.ces.2006.01.038 VL - 61 IS - 14 SP - 4582-4594 SN - 1873-4405 KW - watedet KW - hydroentangling KW - corrosion KW - fluid mechanics KW - hydrodynamics KW - multiphase flow ER - TY - JOUR TI - A case study of simulating submicron aerosol filtration via lightweight spun-bonded filter media AU - Wang, Q. AU - Maze, B. AU - Tafreshi, H. Vahedi AU - Pourdeyhimi, B. T2 - CHEMICAL ENGINEERING SCIENCE AB - The most common method of filtration is via fibrous nonwoven media. Fibrous filters are generally characterized by their collection efficiency and pressure drop. Traditional computational studies in this area are typically based on unrealistic 2-D geometries with the fibers simply placed in a lattice (regular array) perpendicular to the flow. The traditional approaches however, do not permit studying the relation between the 3-D structure of a filter media and its performance. In this study, for the first time, a virtual 3-D web is generated based on the fiber orientation information obtained from analyzing microscopic images of lightweight spun-bonded filter media. Pressure drop and collection efficiency of our virtual filter are simulated and compared with the previous 2-D analytical and numerical models as well as experiment. Our pressure drop calculation, unlike the previous models, showed a perfect agreement with the predictions of the Davies’ empirical equation. The collection efficiencies obtained from simulating a thin spun-bonded filter media challenged with submicron particles having diameters ranging from 50 to 500 nm showed a similar trend as that of the previous 2-D models. For the solid volume fraction (SVF), filter thickness, and the fiber and particle diameters considered in this study, we found collection efficiencies higher than that of the above mentioned 2-D models with a relatively good agreement with experimental data obtained from a TSI 8130 filter tester. DA - 2006/8// PY - 2006/8// DO - 10.1016/j.ces.2006.03.039 VL - 61 IS - 15 SP - 4871-4883 SN - 1873-4405 KW - aerosol KW - filtration KW - product design KW - fluid mechanics KW - modeling ER - TY - JOUR TI - Turbulent lifted flames in the hysteresis regime and the effects of coflow AU - Terry, S. D. AU - Lyons, K. M. T2 - JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME AB - A study of the characteristics of turbulent lifted-jet flames in the hysteresis regime was performed using methane and ethylene fuels in laminar and turbulent air coflows. Reattachment velocities and lifted flame heights just prior to reattachment vary linearly as for laminar flames in coflow. The flow regime of the coflow (i.e., laminar or turbulent) did not appear to affect the behavior of these flames. These observations are of utility in designing maximum turndown burners in air coflow, especially for determining stability criteria in low fuel-flow applications. DA - 2006/12// PY - 2006/12// DO - 10.1115/1.2358147 VL - 128 IS - 4 SP - 319-324 SN - 0195-0738 ER - TY - JOUR TI - The onset of bio-thermal convection in a suspension of gyrotactic microorganisms in a fluid layer: Oscillatory convection AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - INTERNATIONAL JOURNAL OF THERMAL SCIENCES AB - A linear stability analysis is applied to investigate the onset of bioconvection in a horizontal layer of fluid containing a suspension of motile microorganisms with heating or cooling from below. With cooling from below the stabilizing effect of the thermal stratification is opposed to the destabilizing effect resulting from the congregation of the microorganisms, and oscillatory convection is possible in certain circumstances. The stability criterion is found in terms of a thermal Rayleigh number, a bioconvection Rayleigh number, a bioconvection Péclet number, a gyrotactic number, and a measure of the cell eccentricity, together with (in the case of oscillatory convection) a Prandtl number and a Lewis number. DA - 2006/10// PY - 2006/10// DO - 10.1016/j.ijthermalsci.2006.01.007 VL - 45 IS - 10 SP - 990-997 SN - 1778-4166 KW - oscillatory bioconvection KW - gyrotactic microorganisms KW - heated layer ER - TY - JOUR TI - Poststall Prediction of Multiple-Lifting-Surface Configurations Using a Decambering Approach AU - Mukherjee, Rinku AU - Gopalarathnam, Ashok T2 - Journal of Aircraft AB - A novel scheme is presented for an iterative decambering approach to predict the post-stall characteristics of wings using known section data as inputs. The new scheme differs from earlier ones in the details of how the residual is computed. With this scheme, multiple solutions at high angles of attack are brought to light right during the computation of the residual for the Newton iteration. As with earlier schemes, multiple solutions are obtained for wings at high angles of attack and the resulting converged solution depends on the initial conditions used for the iteration. In general, the new scheme is found to be more robust at achieving convergence. Results are presented for a rectangular wing with two different airfoil lift curves and for a wing-tail configuration. DA - 2006/5// PY - 2006/5// DO - 10.2514/1.15149 VL - 43 IS - 3 SP - 660-668 J2 - Journal of Aircraft LA - en OP - SN - 0021-8669 1533-3868 UR - http://dx.doi.org/10.2514/1.15149 DB - Crossref ER - TY - JOUR TI - Numerical modeling of in vivo plate electroporation thermal dose assessment AU - Becker, SM AU - Kuznetsov, AV T2 - JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME AB - Electroporation is an approach used to enhance the transport of large molecules to the cell cytosol in which a targeted tissue region is exposed to a series of electric pulses. The cell membrane, which normally acts as a barrier to large molecule transport into the cell interior, is temporarily destabilized due to the development of pores in the cell membrane. Consequently, agents that are ordinarily unable enter the cell are able to pass through the cell membrane. Of possible concern when exposing biological tissue to an electric field is thermal tissue damage associated with joule heating. This paper explores the thermal effects of various geometric, biological, and electroporation pulse parameters including the blood vessel presence and size, plate electrode configuration, and pulse duration and frequency. A three-dimensional transient finite volume model of in vivo parallel plate electroporation of liver tissue is used to develop a better understanding of the underlying relationships between the physical parameters involved with tissue electroporation and resulting thermal damage potential. DA - 2006/2// PY - 2006/2// DO - 10.1115/1.2132375 VL - 128 IS - 1 SP - 76-84 SN - 1528-8951 ER - TY - JOUR TI - Evaluating tolerances and process capability when using truncated probability density functions AU - Sweet, AL AU - Tu, JF T2 - INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH AB - Abstract An approach is presented on the evaluation of tolerances for the fit between a bore and a shaft, based on the construction of a statistical model of the fit, using truncated probability density functions. The model yields relationships between the probabilities that the bore, shaft and fit meet their specifications, and thus relates the parameters that define the probability density functions. Equations are presented in sufficient detail so that numerical values of capability indices, operating characteristics and Taguchi loss functions can be computed using currently available software. As an example, truncated normal distributions are used to illustrate the capabilities of the model. Keywords: Fit conditionProcess capability indexQuality controlTaguchi loss functionToleranceTruncated probability density function Acknowledgement Research was supported in part by NSF Award # DMI-0355125 and 0355214. DA - 2006/9/1/ PY - 2006/9/1/ DO - 10.1080/00207540500521576 VL - 44 IS - 17 SP - 3493-3508 SN - 0020-7543 KW - fit condition KW - process capability index KW - quality control KW - Taguchi loss function KW - tolerance KW - truncated probability density function ER - TY - JOUR TI - Enhancing tribological conditions in tube hydroforming by using textured tubes AU - Ngaile, Gracious AU - Gariety, Mark AU - Altan, Taylan T2 - JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME AB - The effects of textured tubes on the tribological performance in tube hydroforming (THF) are discussed. Textured surfaces, namely sand blasted, knurled, electrical discharge machined (EDM), and as rolled surfaces, were tested under various interface pressure conditions. Sand blasted textured tubes were found to have the best tribological performance. The study has demonstrated that the increase in the interface pressure between the tube and the die can result in either lower or higher interface friction depending on the surface texture conditions. The study has also shown that different surface texture treatment methods can alter the hardness of the tube surface with significant influence on the tribological performance. DA - 2006/7// PY - 2006/7// DO - 10.1115/1.2197849 VL - 128 IS - 3 SP - 674-676 SN - 0742-4787 KW - tube hydroforming KW - lubrication KW - surface texture ER - TY - JOUR TI - Effects of major endoleaks on a stented abdominal aortic aneurysm AU - Li, Z AU - Kleinstreuer, C T2 - JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME AB - Insertion of a stent-graft into an aneurysm, especially abdominal aortic aneurysms (AAAs), is a very attractive surgical intervention; however, it is not without major postoperative complications, such as endoleaks. An endoleak is the transient accumulation of blood in the AAA cavity, which is formed by the stent-graft and AAA walls. Of the four blood pathways, a type I endoleak constitutes the major one. Thus, focusing on both proximal and distal type I endoleaks, i.e., the minute net influx of blood past the attachment points of a stent-graft into the AAA cavity, the transient three-dimensional interactions between luminal blood flow stent-graft wall, leakage flow, and AAA wall are computationally simulated. For different type I endoleak scenarios and inlet pressure wave forms, the impact of type I endoleaks on cavity pressure, wall stress, and stent-graft migration force is analyzed. The results indicate that both proximal type I-a and distal type I-b endoleaks may cause cavity pressures close to a patient's systemic pressure; however, with reduced pulsatility. As a result, the AAA-wall stress is elevated up to the level of a nonstented AAA and, hence, such endoleaks render the implant useless in protecting the AAA from possible rupture. Interestingly enough, the net downward force acting on the implant is significantly reduced; thus, in the presence of endoleaks, the risk of stent-graft migration may be mitigated. DA - 2006/2// PY - 2006/2// DO - 10.1115/1.2132376 VL - 128 IS - 1 SP - 59-68 SN - 1528-8951 KW - abdominal aortic aneurysm KW - stent-graft KW - type I endoleaks KW - computational analysis KW - sac pressure KW - hypertension KW - aneurysm rupture risk KW - stent-graft migration KW - wall stress ER - TY - JOUR TI - Direct numerical simulation of settling of a large solid particle during bioconvection AU - Geng, P. AU - Kuznetsov, A. V. T2 - INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS AB - Abstract Settling of a large solid particle in bioconvection flow caused by gyrotactic microorganisms is investigated. The particle is released from the top of the bioconvection chamber; its settling pattern depends on whether it is released in the centre of the bioconvection plume or at its periphery. The Chimera method is utilized; a subgrid is generated around a moving particle. The method suggested by Liu and Wang ( Comput. Fluid 2004; 33 :223–255) is further developed to account for the presence of a moving boundary in the streamfunction‐vorticity formulation using the finite‐difference method. A number of cases for different release positions of the particle are computed. It is demonstrated that bioconvection can either accelerate or decelerate settling of the particle depending on the initial position of the particle relative to the plume centre. It is also shown that the particle impacts bioconvection plume by changing its shape and location in the chamber. Copyright © 2005 John Wiley & Sons, Ltd. DA - 2006/6/20/ PY - 2006/6/20/ DO - 10.1002/fld.1125 VL - 51 IS - 5 SP - 511-530 SN - 1097-0363 KW - bioconvection KW - Chimera method KW - large particle KW - motile microorganisms KW - moving boundary KW - streamfunction-vorticity formulation KW - subgrid ER - TY - JOUR TI - Direct numerical simulation of premixed flame kernel-vortex interactions in hydrogen-air mixtures AU - Kolera-Gokula, Hemanth AU - Echekki, Tarek T2 - COMBUSTION AND FLAME AB - Abstract The unsteady interaction between a vortex pair and a premixed flame kernel in 2D is investigated numerically using direct numerical simulations with a detailed reaction mechanism for hydrogen chemistry. The simulations are based on variations of the vortex size and strength with respect to a base case and in comparison with an unperturbed premixed flame kernel. The simulations result in two different regimes for flame kernel–vortex interactions, which, based on the parameter range considered, are consistent with experimental observations. The first regime, the global extinction regime, is characterized by an interaction that is initiated when the kernel is still small compared to the vortex pair core size. The second regime corresponds to an interaction later in time when the kernel size is larger than the vortex pair core size, which results primarily in a wrinkling effect on the flame kernel. Computations of different global quantities show that the vortex-pair causes an enhancement in the flame surface area and the volumetric fuel consumption rate in the break through regime. However, there is a reduction in the global consumption speed during the interaction associated with the effect of stretch on flame structure. A rescaling of the time scale, taking into consideration the vortex-pair translational velocity, is derived, which represents the main effect of the vortex-induced stretch on the flame surface area. Moreover, a new parameter is derived to evaluate the fraction of mutually interacting flames. Downstream interactions, which correspond to the proximity of flames from their burned gas side, are the dominant contribution to flame–flame interactions. DA - 2006/7// PY - 2006/7// DO - 10.1016/j.combustflame.2006.04.002 VL - 146 IS - 1-2 SP - 155-167 SN - 1556-2921 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33745213127&partnerID=MN8TOARS KW - direct numerical simulations KW - flame extinction KW - flame-vortex interactions KW - flame kernel-vortex interactions KW - premixed flames ER - TY - JOUR TI - Damage imaging of reinforced concrete structures using electromagnetic migration algorithm AU - Nojavan, Saeed AU - Yuan, Fuh-Gwo T2 - INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES AB - Reconstructing damage geometry with computationally efficient algorithms is of primary importance in establishing a robust structural health monitoring system (SHMS). In this paper electromagnetic migration, a linearized imaging algorithm, is adopted to image the damages in reinforced concrete structures. This algorithm is formulated in time-domain for 3-D inhomogeneous isotropic and lossy structures. In order to reduce the computational cost and to examine the damage resolution of this imaging algorithm, different imaging conditions are introduced. Numerical simulations in 2-D transverse magnetic (TM) wave for a reinforced concrete slab with multiple damages are performed to test the effectiveness of the algorithm. All synthetic sensor data, incident field, and migration field are computed via a finite difference time-domain (FDTD) method. It is concluded that the proposed imaging algorithm is capable of efficiently identifying the damages geometries, is robust against measurement noise, and may be employed in a SHMS. DA - 2006/9// PY - 2006/9// DO - 10.1016/j.ijsolstr.2005.08.017 VL - 43 IS - 18-19 SP - 5886-5908 SN - 0020-7683 KW - electromagnetic migration algorithm KW - structural health monitoring KW - damage imaging KW - prestack KW - poststack KW - finite difference method ER - TY - JOUR TI - Calculating mass transfer from vertical wet fabrics using a free convection heat transfer correlation AU - Tafreshi, H. Vahedi AU - Ercan, E. AU - Pourdeyhimi, B. T2 - HEAT AND MASS TRANSFER DA - 2006/7// PY - 2006/7// DO - 10.1007/s00231-005-0050-1 VL - 42 IS - 9 SP - 767-769 SN - 1432-1181 ER - TY - JOUR TI - A study on hydroentangling waterjets and their impact forces AU - Anantharamaiah, N. AU - Tafreshi, H. Vahedi AU - Pourdeyhimi, B. T2 - EXPERIMENTS IN FLUIDS DA - 2006/7// PY - 2006/7// DO - 10.1007/s00348-006-0162-5 VL - 41 IS - 1 SP - 103-113 SN - 1432-1114 ER - TY - JOUR TI - A finite element analysis of orthogonal rubber cutting AU - Yan, Jun AU - Strenkowski, John S. T2 - JOURNAL OF MATERIALS PROCESSING TECHNOLOGY AB - An explicit plane strain FE model using ABAQUS/Explicit was developed to analyze rubber cutting using high-speed steel (HSS) tools. The initial and deformed meshes, as the cutting reaches steady state condition, are first described. The neo-Hookean constitutive model for the hyperelastic material considering the effective stress failure criterion is then introduced. The advantages of applying explicit method on the simulation of rubber cutting process over its implicit counterpart are discussed. The model was used to predict cutting forces, chip shape, stress and strain fields, and strain energy distribution in the chip and workpiece. Orthogonal cutting experiments were conducted for several rake angles and feeds to validate the FE model. Good agreement was found between the predicted and measured cutting forces. Favorable cutting conditions for formation of a smooth machined surface were identified by both simulations and experiments. The finite element model provides new insight into the chip formation process of rubber cutting. DA - 2006/5/25/ PY - 2006/5/25/ DO - 10.1016/j.jmatprotec.2005.02.265 VL - 174 IS - 1-3 SP - 102-108 SN - 1097-6787 KW - finite element analysis KW - rubber KW - orthogonal cutting ER - TY - JOUR TI - Adhesion interactions between poly(vinyl alcohol) and iron-oxide surfaces: The effect of acetylation AU - Uner, B AU - Ramasubramanian, MK AU - Zauscher, S AU - Kadla, JF T2 - JOURNAL OF APPLIED POLYMER SCIENCE AB - Abstract Atomic force microscopy with chemically functionalized colloidal probes was used to study “acid–base” interactions between poly(vinyl alcohol) (PVA) and a metal surface. By using well‐defined model surfaces, we have studied the adhesion forces between a hydroxylated surface and cantilever tips with varying hydroxyl content. Decreasing the amount of available hydroxyl groups dramatically reduced the observed adhesion force. The calculated bond energy for each cantilever tip was found to be in the range of typical hydrogen bond energies, i.e., 10–40 kJ/mol, suggesting that the acid–base interactions are predominately hydrogen bonding. Similarly, the force versus distance curves using PVA functionalized colloidal probes showed a strong dependence on the chemical functionality of the tip and the degree of acetylation of the intervening PVA. It was observed that, with an increase in the acetyl content of the PVA, the adhesion force decreased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3528–3534, 2006 DA - 2006/3/15/ PY - 2006/3/15/ DO - 10.1002/app.22980 VL - 99 IS - 6 SP - 3528-3534 SN - 1097-4628 KW - adhesion KW - atomic force microscopy (AFM) KW - FTIR KW - poly(vinyl alcohol) ER - TY - JOUR TI - Water vapor transport and its effects on the deposition of hygroscopic droplets in a human upper airway model AU - Zhang, Z AU - Kleinstreuer, C AU - Kim, CS T2 - AEROSOL SCIENCE AND TECHNOLOGY AB - The fundamentals of 3-D airflow as well as heat and water vapor transport and droplet vaporization (or hygroscopicity) are described for a human upper airway model under steady laminar-transitional-turbulent inspiratory flow conditions. Water vapor distributions from the mouth to the first four generations of the tracheobronchial tree are given in terms of relative humidity or mass fraction. The mass transfer coefficients of water vapor are correlated as a function of local flow rate and temperature-dependent diffusivity, which can be readily used for estimating the regional water loss or moisture variations in the human upper airways. Furthermore, the dynamics of hygroscopicity and deposition of isotonic saline droplets have been simulated as an example, applying the basic theory. Specifically, droplet evaporation rates and deposition pattern are analyzed and the effects of inhalation flow rates and thermodynamic air properties are discussed. DA - 2006/1// PY - 2006/1// DO - 10.1080/02786820500461154 VL - 40 IS - 1 SP - 1-16 SN - 1521-7388 ER - TY - JOUR TI - Prediction of foam growth and its nucleation in free and limited expansion AU - Mao, DM AU - Edwards, , JR AU - Harvey, A T2 - CHEMICAL ENGINEERING SCIENCE AB - The influence volume approach (IVA) is often utilized for modeling the mass transfer process dictating bubble growth dynamics in physical foaming. However, the assumed concentration profile in the IVA method is only valid when the changes in dissolved gas concentration are small (less than 5%). In addition, the validity of the IVA method is difficult to justify in chemical foaming applications because of the difficulties involved in defining the dissolved gas concentration profile. In the present work, we define two distinct stages of bubble growth for physical foaming. These two stages are termed as free and limited expansion and are controlled by the bubble nucleation rate. Bubble nucleation is assumed to occur only in the free expansion stage. In this stage, the bubble pressure drops substantially from an initially high pressure in the supersaturated state while the dissolved gas concentration changes very little. The second stage of our two-stage mass transfer model is termed the limited expansion stage and accounts for bubble growth in the late stages of foam evolution, when the pressure changes become small. However, in the limited stage of bubble growth the dissolved gas concentration drops significantly, as the available dissolved gas is depleted. To summarize our two-stage mass transfer model of foam expansion, the pressure difference between the bubble phase and the liquid phase is the primary mechanism for driving mass transfer in the early (free) stages of foam growth and the concentration difference is the driver for bubble growth in the late (limited) stages of growth. The first stage can be regarded as the nucleation stage and it is relatively short; while the second stage can be regarded as the bubble growth stage and is much longer. Most of the bubble volume expansion takes place in the second stage. The concentration gradient at the bubble edge, which is often ignored in other models, is analyzed in detail in this paper. The details of our novel mass transfer model are also presented. DA - 2006/3// PY - 2006/3// DO - 10.1016/j.ces.2005.07.026 VL - 61 IS - 6 SP - 1836-1845 SN - 1873-4405 KW - foam bubble growth KW - bubble nucleation KW - influence volume approach KW - Lagrangian foam growth model ER - TY - JOUR TI - Analysis of biomechanical factors affecting stent-graft migration in an abdominal aortic aneurysm model AU - Li, Z. AU - Kleinstreuer, C. T2 - JOURNAL OF BIOMECHANICS AB - Focusing on a representative abdominal aortic aneurysm (AAA) with a bifurcating stent-graft (SG), a fluid–structure interaction (FSI) solver with user-supplied programs has been employed to solve for blood flow, AAA/SG deformation, sac pressure and wall stresses, as well as the downward forces acting on the SG. Simulation results indicate that implanting a SG can significantly reduce sac pressure, mechanical stress, pulsatile wall motion, and maximum diameter change in AAAs; hence, it may restore normal blood flow and prevent AAA rupture effectively. The transient SG drag force is similar in trend as the cardiac pressure. Its magnitude depends on multi-factors including blood flow conditions, as well as SG and aneurysm geometries. Specifically, AAA neck angle, iliac bifurcation angle, neck aorta-to-iliac diameter ratio, SG size, and blood waveform play important roles in generating a fluid flow force potentially leading to SG migration. It was found that the drag force can exceed 5 N for an AAA with a large neck or iliac angle, wide aortic neck and narrow iliac arteries, large SG size, and/or abnormal blood waveform. Thus, the fixation of self-expandable or balloon-expandable SG contact may be inadequate to withstand the forces of blood flowing through the implant and hence means of extra fixation should be considered. A comprehensive FSI analysis of the coupled SG–AAA dynamics provides physical insight for evaluating the luminal hemodynamics, and maximum AAA-stresses as well as biomechanical factors leading potentially to SG migration. DA - 2006/// PY - 2006/// DO - 10.1016/j.jbiomech.2005.07.010 VL - 39 IS - 12 SP - 2264-2273 SN - 1873-2380 KW - stented abdominal aortic aneurysm KW - stent-graft migration KW - blood flow KW - stent-graft and aneurysm-wall interactions KW - computational parametric sensitivity analyses ER - TY - JOUR TI - A unified framework for modeling hysteresis in ferroic materials AU - Smith, RC AU - Seelecke, S AU - Dapino, M AU - Ounaies, Z T2 - JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS AB - This paper addresses the development of a unified framework for quantifying hysteresis and constitutive nonlinearities inherent to ferroelectric, ferromagnetic and ferroelastic materials. Because the mechanisms which produce hysteresis vary substantially at the microscopic level, it is more natural to initiate model development at the mesoscopic, or lattice, level where the materials share common energy properties along with analogous domain structures. In the first step of the model development, Helmholtz and Gibbs energy relations are combined with Boltzmann theory to construct mesoscopic models which quantify the local average polarization, magnetization and strains in ferroelectric, ferromagnetic and ferroelastic materials. In the second step of the development, stochastic homogenization techniques are invoked to construct unified macroscopic models for nonhomogeneous, polycrystalline compounds exhibiting nonuniform effective fields. The combination of energy analysis and homogenization techniques produces low-order models in which a number of parameters can be correlated with physical attributes of measured data. Furthermore, the development of a unified modeling framework applicable to a broad range of ferroic compounds facilitates material characterization, transducer development, and model-based control design. Attributes of the models are illustrated through comparison with piezoceramic, magnetostrictive and shape memory alloy data and prediction of material behavior. DA - 2006/1// PY - 2006/1// DO - 10.1016/j.jmps.2005.08.006 VL - 54 IS - 1 SP - 46-85 SN - 1873-4782 KW - ferroic materials KW - unified models KW - hysteresis KW - constitutive nonlinearities ER - TY - JOUR TI - Transport and uptake of MTBE and ethanol vapors in a human upper airway model AU - Zhang, Z AU - Kleinstreuer, C AU - Kim, CS T2 - INHALATION TOXICOLOGY AB - Potential human exposure to vapors of methyl tertiary-butyl ether (MTBE) and ethanol is of increasing concern because these materials are widely used as gasoline additives. In this study we analyzed numerically the transport and deposition of MTBE and ethanol vapors in a model of the human upper respiratory airway, consisting of an oral airway and the first four generations of the tracheobronchial tree. Airflow characteristics and mass transfer processes were analyzed at different inspiratory flow conditions using a three-dimensional computational fluid and particle dynamics method. The deposition data were analyzed in terms of regional deposition fractions (DF = regional uptake/mouth concentration) and deposition enhancement factors (DEF = local DF/average DF) at local micro surface areas. Results show that DF in the entire upper airway model is 21.9%, 12.4%, and 6.9% for MTBE and 67.5%, 51.5%, and 38.5% for ethanol at a flow rate of 15, 30, and 60 L/min, respectively. Of the total DF, 65–70% is deposited in the oral airway for both vapors. Deposition is localized at various sites within the upper airway structure, with a maximum DEF of 1.5 for MTBE and 7.8 for ethanol. Local deposition patterns did not change with inhalation conditions, but DF and the maximum DEF increased with diffusivity, solubility, and the degree of airway wall absorption of vapors, as shown by a greater deposition of ethanol than MTBE. The vapor deposition efficiency as expressed by the dimensionless mass transfer coefficient correlated well with a product of Reynolds (Re) and Schmidt (Sc) numbers. In conclusion, MTBE and ethanol vapors deposit substantially in the upper airway structure with a marked enhancement of dose at local sites, and the deposition dose may be reasonably estimated by a functional relationship with dimensionless fluid flow and diffusion parameters. DA - 2006/3// PY - 2006/3// DO - 10.1080/08958370500434172 VL - 18 IS - 3 SP - 169-184 SN - 1091-7691 ER - TY - JOUR TI - Proper orthogonal decomposition analysis of autoignition simulation data of nonhomogeneous hydrogen-air mixtures AU - Danby, SJ AU - Echekki, T T2 - COMBUSTION AND FLAME AB - The proper orthogonal decomposition (POD) method is implemented on unsteady 2D direct numerical simulation of autoignition in nonhomogeneous hydrogen–air mixtures. The analysis is implemented to evaluate requirements for the reproduction of transient, multidimensional and multiscalar processes in combustion. Data reduction is implemented on a set of 30 snapshots of 2D fields of a passive scalar, the mixture fraction, and a reactive scalar, the mass fraction of the intermediate species, HO2. The snapshots cover the evolution of the hydrogen–air mixture from induction to the early stages of high-temperature combustion. The standard method by which the POD technique is measured, the cumulative energy criterion, based on the sum of the largest eigenvalues, suggests that the bulk of this energy may be represented by the first three to four modes for the reactive scalars. However, this criterion may not be sufficient to characterize the performance of the POD reduction approach. Therefore the number of required eigenmodes for each data set is tested. A number of preprocessing strategies of the scalar fields are explored to reduce the number of required eigenmodes. The strategies are designed to reduce the temporal and spatial spans of scalar values. The results show that different preprocessing strategies may yield different outcomes for the passive scalars, represented by the mixture fraction, and reactive scalars, represented by the intermediate species, HO2 mass fraction. More importantly, there are different requirements to reproduce passive and reactive scalars during the autoignition process. The mixture fraction, which is affected by the mixing process only, requires the least number of eigenmodes, and yields a sufficient representation of the original data with only two to three eigenmodes. The reactive scalar reduction improves significantly with preprocessing, which reduces the required number of eigenmodes to approximately six. DA - 2006/1// PY - 2006/1// DO - 10.1016/j.combustflame.2005.06.014 VL - 144 IS - 1-2 SP - 126-138 SN - 1556-2921 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-29244446801&partnerID=MN8TOARS KW - premixed laminar flames KW - laminar flame quenching KW - proper orthogonal decomposition (POD) KW - computation and theory ER - TY - JOUR TI - The modeling of the shock response of powdered ceramic materials AU - Rajendran, AM AU - Ashmawi, WM AU - Zikry, MA T2 - COMPUTATIONAL MECHANICS DA - 2006/6// PY - 2006/6// DO - 10.1007/s00466-005-0712-3 VL - 38 IS - 1 SP - 1-13 SN - 1432-0924 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33646550239&partnerID=MN8TOARS KW - powdered ceramic KW - alumina KW - shock response KW - wave propagation KW - computational formulation KW - plate impact KW - two-cap model KW - inelastic yielding KW - shock-dependent plasticity ER - TY - JOUR TI - An adaptive system identification model of the biomechanical response of the human trunk during sudden loading AU - Lawrence, BM AU - Buckner, GD AU - Mirka, GA T2 - JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME AB - Sudden loading injuries to the low back are a concern. Current models are limited in their ability to quantify the time-varying nature of the sudden loading event. The method of approach used six males who were subjected to sudden loads. Response data (EMG and kinematics) were input into a system identification model to yield time-varying torso stiffness estimates. The results show estimates of system stiffness in good agreement with values in the literature. The average root mean square error of the model's predictions of sagittal motion was equal to 0.1 deg. In conclusion, system identification can be implemented with minimal error and used to gain more insight into the time-dependent trunk response to sudden loads. DA - 2006/4// PY - 2006/4// DO - 10.1115/1.2165696 VL - 128 IS - 2 SP - 235-241 SN - 0148-0731 KW - sudden loading KW - system identification KW - lumbar ER - TY - JOUR TI - A study on functionally graded HA coatings processed using ion beam assisted deposition with in situ heat treatment AU - Rabiei, A AU - Thomas, B AU - Jin, C AU - Narayan, R AU - Cuomo, J AU - Yang, Y AU - Ong, JL T2 - SURFACE & COATINGS TECHNOLOGY AB - A new generation of calcium phosphate coatings with less than 1 μm thickness and graded crystallinity through the thickness of the film has been processed using ion beam assisted deposition (IBAD) and in situ heat treatment. Microstructural analysis of the film confirmed a gradual decrease of the grain size and crystallinity towards the surface, leading to nano-scale grains and eventually amorphous layer at the surface. The mechanical properties and adhesion bonding of the film have been evaluated using microscratch and nanoindentation tests and, in general, functionally graded HA films deposited using our IBAD system together with in situ heat treatment demonstrated higher modulus and hardness values than sputter-deposited films with the same thickness as well as those appearing in the literature for sintered HA. Scratch test results of both sets of samples revealed that crack formation is more common in sputter-deposited HA film than in the functionally graded HA film deposited using IBAD and in situ heat treatment. We anticipate that the functionally graded hydroxyapatite films will provide improved tissue–implant interfaces for orthopedic and dental implants. DA - 2006/5/22/ PY - 2006/5/22/ DO - 10.1016/j.surfcoat.2005.09.027 VL - 200 IS - 20-21 SP - 6111-6116 SN - 0257-8972 KW - hydroxyapatite KW - graded crystallinity KW - ion beam assisted deposition KW - nanoindentation KW - scratch adhesion test KW - sputtering ER - TY - JOUR TI - Thermionic-tunneling multilayer nanostructures for power generation AU - Zeng, TF T2 - APPLIED PHYSICS LETTERS AB - A method for power generation based on nanoengineered interface design with partially filled gap is presented. The proposed device allows a substantial temperature difference to exist between heat source and heat sink or two electrodes, thereby maximizing heat source utilization. A unified model and detailed analyses are provided for the solid device operating either as a power generator or as a cooler. Our analyses show that efficiency of about 50% of the corresponding Carnot efficiency can be achieved. DA - 2006/4/10/ PY - 2006/4/10/ DO - 10.1063/1.2192973 VL - 88 IS - 15 SP - SN - 1077-3118 ER - TY - JOUR TI - A new method to quantify radial error of a motorized end-milling cutter/spindle system at very high speed rotations AU - Nakkiew, Wasawat AU - Lin, Chi-Wei AU - Tu, Jay F. T2 - INTERNATIONAL JOURNAL OF MACHINE TOOLS & MANUFACTURE AB - The radial error motion of a machine tool cutter/spindle system is critical to the dimensional accuracy of the parts to be machined. The spindle's radial error motions can be measured by mounting a sphere target onto the spindle as a reference. A set of sensors is used to measure displacements of the reference sphere in various directions to determine spindle error motions. This measurement technique can be reliably carried out when the spindle is at rest or at low rotational speeds. However, at very high speeds, the reference sphere must be carefully centered and balanced to avoid introducing additional error motions. In addition, the sensors must be held with very rigid mounts in order to avoid measurement errors caused by vibrations. For high-speed end milling spindles, the spindle is operated with a cutter. The cutter must be removed when mounting a reference sphere. Because the cutter itself can introduce errors due to centering and unbalancing effects, the error motions measured by the reference sphere method do not include the error caused by the cutter. This paper introduces a new and practical method to provide an indicator of the radial error of a motorized end-milling cutter/spindle system at very high speed rotations without the need of a reference sphere. This indicator of the radial error is based on the size of the cutting marks produced by the end mill, which is attached to the spindle. The cutting marks are circular, and their diameters are related to the radial error of the cutter/spindle system. Quantitative precision analysis was carried out to confirm the accuracy and repeatability of this new measurement technique. This technique has been implemented in order to determine the effects of the spindle speed, the level of unbalanced mass, and the spindle stiffness on the cutter/spindle's radial error. The results reveal that the centrifugal force generated by the unbalanced mass is the main factor causing the increase in radial error. One way to compensate for the effect of unbalanced mass is to increase the spindle stiffness. Experimental results confirm that a higher front bearing preload can render the spindle stiffer, thus reducing the radial error of the cutter/spindle system. Finally, it should be pointed out that the proposed cutting mark measurement cannot replace the sphere method because it cannot provide time-resolved or angle-resolved information as those obtained from polar charts. However, the proposed cutting mark measurement can provide the characterization of the spindle with the cutter attached. As a result, both methods can complement each other to provide a more complete picture of the behavior of the cutter/spindle system at high speeds. DA - 2006/6// PY - 2006/6// DO - 10.1016/j.ijmachtools.2005.04.021 VL - 46 IS - 7-8 SP - 877-889 SN - 1879-2170 ER - TY - JOUR TI - Investigation of the onset of bioconvection in a suspension of oxytactic microorganisms subjected to high-frequency vertical vibration AU - Kuznetsov, AV T2 - THEORETICAL AND COMPUTATIONAL FLUID DYNAMICS DA - 2006/4// PY - 2006/4// DO - 10.1007/s00162-006-0007-0 VL - 20 IS - 2 SP - 73-87 SN - 1432-2250 KW - bioconvection KW - oxytactic microorganisms KW - vertical vibration KW - averaging method ER - TY - CHAP TI - Effects of electric fatigue on piezoelectric ceramics AU - Lee, K. L. AU - Soh, A. K. T2 - Fracture and strength of solids, proceedings of the Sixth International Conference on Fracture & Strength of Solids (Key engineering materials; 306-308) PY - 2006/// VL - 306-308 SP - 91-96 ER - TY - JOUR TI - Bridgman-Stockbarger growth of binary alloyed semiconductor crystals with steady magnetic fields AU - Wang, X AU - Ma, N T2 - JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER AB - Single crystals of alloyed compound semiconductor crystals such as gallium‐aluminum‐antimonide are needed for optoelectronic devices. These crystals are solidified from a solution of molten gallium‐antimonide and aluminum‐antimonide in a Bridgman‐Stockbarger furnace. During the growth of alloyed semiconductor crystals, the solute’s concentration is not small so that the density differences in the melt are very large. These compositional variations drive compositionally driven buoyant convection, or solutal convection, in addition to thermally driven buoyant convection. These buoyant convections drive convective species transport, which produce nonuniformities in the concentration in both the melt and the crystal. A numerical model is presented for the unsteady transport for the growth of alloyed semiconductor crystals during the vertical Bridgman‐Stockbarger process with a steady axial magnetic field. Predictions of alloy concentration in the crystal and in the melt at several different stages during crystal growth are presented. DA - 2006/// PY - 2006/// DO - 10.2514/1.15584 VL - 20 IS - 2 SP - 313-319 SN - 1533-6808 ER - TY - JOUR TI - Forced convection with slip-flow in a channel or duct occupied by a hyper-porous medium saturated by a rarefied gas AU - Nield, D. A. AU - Kuznetsov, A. V. T2 - TRANSPORT IN POROUS MEDIA DA - 2006/8// PY - 2006/8// DO - 10.1007/s11242-005-2341-x VL - 64 IS - 2 SP - 161-170 SN - 1573-1634 KW - forced convection KW - rarefied gas KW - slip-flow KW - hyper-porous medium KW - parallel-plates channel KW - circular duct ER - TY - JOUR TI - Optimization problems for bioheat equation AU - Kuznetsov, A. V. T2 - INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER AB - The minimum principal of Pontryagin is used solve an optimal control problem for heating a layer of tissue in order to destroy a cancerous tumor. Distributions of temperature and thermal dose in the tissue at different moments of time are computed numerically. The influence of the cool-off period on thermal dose accumulation is investigated. DA - 2006/5// PY - 2006/5// DO - 10.1016/j.icheatmasstransfer.2006.01.012 VL - 33 IS - 5 SP - 537-543 SN - 1879-0178 KW - bioheat equation KW - hyperthermia KW - cancer treatment KW - thermal dose optimization ER - TY - JOUR TI - Measurement of smoke point in velocity-matched coflow laminar diffusion flames with pure fuels at elevated pressures AU - Berry, T. L. AU - Roberts, W. L. T2 - COMBUSTION AND FLAME AB - Using a coflow burner, a quartz chimney, and a pressure vessel with good optical access, smoke points of pure fuels were measured in a laminar jet diffusion flame. The smoke point is a fundamental kinetic parameter, as this is the point where production of soot is exactly offset by its oxidation. Ethylene and methane, burning in a velocity-matched, overventilated coflow of air, were tested over a range of pressures from 1 to 16 atm. Fuel flow rate and air coflow rate were iteratively increased, keeping the exit velocity equal, until the smoke point was reached. The volumetric fuel flow and flame height were measured as a function of pressure to determine the functional relationship between these parameters and pressure. The volumetric fuel flow at the smoke point is observed to scale as a power law with pressure, while the smoke point height is best described by a log law with pressure. The residence time, based on flame height and exit velocity, was also calculated as a function of pressure and found to have a nonmonotonic behavior, with a peak at lower pressures. DA - 2006/5// PY - 2006/5// DO - 10.1016/j.combustflame.2005.12.010 VL - 145 IS - 3 SP - 571-578 SN - 1556-2921 KW - diffusion flame KW - smoke point KW - soot KW - high pressure ER - TY - JOUR TI - All-speed time-accurate underwater projectile calculations using a preconditioning algorithm AU - Neaves, MD AU - Edwards, , JR T2 - JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME AB - An algorithm based on the combination of time-derivative preconditioning strategies with low-diffusion upwinding methods is developed and applied to multiphase, compressible flows characteristic of underwater projectile motion. Multiphase compressible flows are assumed to be in kinematic and thermodynamic equilibrium and are modeled using a homogeneous mixture formulation. Compressibility effects in liquid-phase water are modeled using a temperature-adjusted Tait equation, and gaseous phases (water vapor and air) are treated as an ideal gas. The algorithm is applied to subsonic and supersonic projectiles in water, general multiphase shock tubes, and a high-speed water entry problem. Low-speed solutions are presented and compared to experimental results for validation. Solutions for high-subsonic and transonic projectile flows are compared to experimental imaging results and theoretical results. Results are also presented for several multiphase shock tube calculations. Finally, calculations are presented for a high-speed axisymmetric supercavitating projectile during the important water entry phase of flight. DA - 2006/3// PY - 2006/3// DO - 10.1115/1.2169816 VL - 128 IS - 2 SP - 284-296 SN - 1528-901X KW - compressible multiphase flows KW - supercavitation KW - high-speed water entry ER - TY - JOUR TI - Renormalization group model of large-scale turbulence in porous media AU - Avramenko, AA AU - Kuznetsov, AV T2 - TRANSPORT IN POROUS MEDIA DA - 2006/4// PY - 2006/4// DO - 10.1007/s11242-005-4425-z VL - 63 IS - 1 SP - 175-193 SN - 1573-1634 KW - large-scale turbulence KW - renormalization group method KW - turbulent viscosity ER - TY - JOUR TI - Gain-scheduling control of LFT systems using parameter-dependent Lyapunov functions AU - Wu, F AU - Dong, K T2 - AUTOMATICA AB - In this paper, we propose a new control design approach for linear fractional transformation (LFT) systems using parameter-dependent Lyapunov functions. Instead of assuming parameter dependency in LFT fashion, we consider general parameter-dependent controllers to achieve better closed-loop performance. Using full-block multipliers, new LPV synthesis conditions have been derived in terms of finite number of linear matrix inequalities (LMIs). Both continuous- and discrete-time cases are discussed. A ship steering example has been used to demonstrate advantages and benefits of the proposed approach. DA - 2006/1// PY - 2006/1// DO - 10.1016/j.automatica.2005.08.020 VL - 42 IS - 1 SP - 39-50 SN - 1873-2836 KW - linear fractional transformation system KW - parameter-dependent Lyapunov function KW - full-block multiplier KW - L-2 gain KW - linear matrix inequality ER -