bluuebunny/crossref_metadata_2025 huggingface dataset:
Shear Driven Liquid Film in a Duct: Comparison With Measured Results
Authors: Thiruvengadam M. , Armaly B. F. , Drallmeier J. A.
Published: April 2008

Two-dimensional flow simulations of shear driven liquid film by turbulent air flow in a duct is performed using the Reynolds Averaged Navier Stokes and continuity equations along with the k-ε turbulence model and the Volume of Fluid (VOF) model that are part of the FLUENT-CFD code. The purpose of this effort is to determine the suitability of using this model for predicting the measured results of Wittig et al. [1, 2]. In these studies, optical means are used to measure shear driven liquid film velocities along with the liquid film thickness, and measurements are reported for different air velocities and liquid film flow rates. The simulated results will be compared with measured values, and the suitability of the VOF model for simulating such flow will be assessed in this study.
Demineralized Bone Matrix Incorporated PLGA Matrices
Authors: Jayasuriya A. Champa , Michels Elisabeth , Ebraheim Nabil A.
Published: April 2008

Poly(lactic-co-glycolic acid)-PLGA (85:15) films incorporated with demineralized bone matrix (DBM) powder with the weight ratio of polymer: DBM (75:25) were investigated for release of agents including osteoinductive (OI) factors during the 80 day period exposing to Phosphate Buffered Saline (PBS) at 37 °C. The release amount of agents including OI factors from DBM/PLGA matrices were more than 2-fold higher at 70 days than at 10 days, respectively. This result demonstrated that controlled release of OI factors can be achieved for extended time period at target site using PLGA as a carrier for DBM powder. Murine Bone Marrow Stromal Cell (BMSC) attachment was studied with different time points at 30 min, 1 h, 2 h, 4 h, 6 h and 24 h for DBM/PLGA and PLGA control matrices. Significantly higher number of BMSCs was attached to the DBM/PLGA matrices at each time points compared with controls. This result suggests that BMSCs favor to attach the surfaces having OI properties. If DBM is incorporated into biodegradable 3-D polymer scaffolds and culture with BMSCs, those scaffolds could be potentially used for bone tissue engineering applications.
Cracking During the Installation of Interference Fit Fasteners and Bucked Rivets in 7050-T7XXX Machined Aluminum Parts
Authors: Brady Brian G.
Published: April 2008

This test program evaluated the effect of the installation of solid rivets and interference fit Hi-Tigue bolts on machined 7050 longerons (HiTigue is a registered trademark of the Hi-Shear Corporation of Torrance, (CA). Two simulated longeron specimens were machined from both 7050-T7451 and 7050-T7651 plate. Titanium Hi-Tigues and solid aluminum and Monel rivets were then installed with a pneumatic riveting hammer in sections of various thicknesses in the four machined longeron specimens. After all fasteners were installed, each fastener was subjected to a simulated mishap by applying the pneumatic riveting hammer to the installed fastener without support from an underlying bucking bar. Dye penetrant inspections to detect cracks were performed after the fastener installations and simulated mishaps. All fasteners were then removed and the open holes subjected to eddy current inspection. Visual observations concerning deformation of the machined longeron specimens during fastener installations and simulated mishaps were recorded. Cracking was noted in 0.063 inch thick longeron sections, compelling additional testing involving Hi-Tigues. Recommendations concerning the use of Hi-Tigues and solid rivets in 7050-T7XXX machined parts were made based on the results of the testing.
Micro-Embossing of Polymeric Substrates for Fluidic Self-Assembly
Authors: Srinivasan Visvanathan , Reddy Nayan , Brasoava Adriana , Wells David L.
Published: April 2008

Fluidic Self-Assembly™ (FSA)™ has become a routine manufacturing process in the production of radio-frequency identification tags. FSA operates through the self-positioning of micro-devices into pre-prepared matching receptor sites in a substrate. Research at North Dakota State University has focused on extending the applications of FSA well-beyond the current production routine. This pursuit requires, among other modifications, substantive extrapolation of the size, depth, configuration, spacing and spatial density of receptor sites. Three different test wafer patterns (see Figure 5 for patterns having nominal sizes of 1050μ, 1500μ, μ2150 and 3050μ square receptors with different spacing between them) took into account the corner compensation structure dimensions, which are based on thickness of silicon mold wafer feature to be etched (see Figure 2). The embossing tool (silicon wafer) was patterned photo-lithographically and subsequently wet etched in a KOH 2:1 solution. Experiments suggest shorter tool life in the case of closely packed features (spacing ~ 0.5mm). Receptor profiles evaluated using both optical and mechanical inspection (see Figures 3 and 4) suggest that features having larger size (up to nominal size of 3050μ square) and thickness (nominal depths of 110μ and 210μ) can be embossed accurately for use in FSA by slightly increasing the embossing time in case of deeper receptors. It was also noticed that the relative receptor depths attained with respect to the thickness of the feature on the mold wafer was lower while embossing deeper receptor sites, leading to the conclusion that mold wafers must be etched longer in such cases. The embossed receptor sites were subsequently filled with micro-devices in accordance with the standard operating parameters of Fluidic Self-Assembly process. These sample experimental runs suggest receptors slightly deeper than the micro-devices facilitate higher yields (or fill rates) in FSA. However, in cases where the receptors are too deep relative to the micro-device (> 5μ), air-entrapment occurred between the micro-device and the bottom of the receptor site, which caused problems in post-FSA processes due to air expansion. This paper presents comprehensive guidelines for embossing larger and deeper receptors for effective use in FSA.
Characterization and Modeling Magnetorheological By-Pass Porous Damper Exploiting Flow Through a Porous Media
Authors: Hu Wei , Cook Eugene , Wereley Norman M.
Published: April 2008

A magnetorheological (MR) fluid bypass damper exploiting flow through porous media is developed utilizing a valve filled with porous media instead of regular uniform channels to adaptively regulate damping force. The MR damper includes a cylinder containing an MR fluid, a movable piston and a bypass valve. The bypass valve filled with porous media is used to provide a magnetically energizable passageway. A stationary magnetic coil is wrapped around the bypass valve, isolated from the MR fluid and external to the device. The axis of the bypass valve is collinear with the center of the magnetic coil such that the magnetic flux return guide of the coil can be either empty (air) or any high permeability steel material which provides flexibility for damper design. The damper is applied with sinusoidal excitations. Equivalent viscous damping is used to characterize the damper. It is shown that the MR damper exploiting flow through porous media can provide high controllable damping force using a compact damper configuration. To describe the behavior of the MR damper, the flow path in the porous media is considered as a multiple-pipe system. Using quantitative and empirical analysis of the magnetic and rheological properties of MR fluid flowing through the porous media in the bypass valve, the controllable damping performance of the damper is well predicted using the model, and the force-displacement hysteresis behavior of the damper can also be described by the analytical model. The model is validated by the experimental data at different frequencies and applied currents.
Determining Orthotropic Coefficients From, and Thermoelastic Stress Analysis of, Diametrally Loaded Composite Disk
Authors: Quinn Simon , Lin Shiang-Jiun , McCabe Jonathan , Rowlands Robert E.
Published: April 2008

Thermoelastic stress analysis measures temperature variations in loaded solids and relates these to associated stresses. For orthotropic materials, the measured signal is proportional to a linear combination of the normal stress changes in the directions of material symmetry, and K1 and K2 are thermo-mechanical coefficients. Quantitative thermoelastic stress analysis of orthotropic composites necessitates (i) determination of the above two thermo-mechanical coefficients (i.e. calibration), and (ii) separation of the stresses. Although calibration procedures can take different forms, K1 and K2 can be experimentally determined most reliably and easily from calibration specimens of the same material, paint coating, loading frequency and ambient conditions as the test structure. Such calibration specimens typically employ a geometry and loading for which the state of stress or strain is known theoretically, or independently determined. Loaded beams, a diametrically-compressed disk, or uniaxial tensile coupons have been used for isotropic materials. Orthotropic materials usually necessitate testing two calibration specimens, with their principal material directions interchanged respectively. The present paper demonstrates the ability to determine both K1 and K2 from a single diametrally-loaded orthotropic composite (graphite/epoxy) disk. To be able to determine both coefficients from a single calibration specimen is advantageous. Disks are also easy to machine and load, rendering them very convenient for calibration.
Dielectrophoretic Particle Manipulation in Ridged Microchannels
Authors: Smith A. Ezekiel , Hawkins Benjamin G. , Baldasaro Nicholas G. , Syed Yusef A. , Simmons Blake A. , Cummings Eric B. , Kirby Brian J.
Published: April 2008

This work presents continuous-flow particle sorting at low applied fields (30 V/cm) using electrodeless dielectrophoresis [2–7] in ridged polymeric microstructures. Particle manipulation and sorting is critical in analysis of cellular systems and subpopulations, water monitoring, soil analysis, and colloidal synthesis. This technique is developed with a view toward sorting of cellular systems, and offers advantages over other particle processing techniques in its ability to sort particles over small (~100 μm) spatial scales and rapid (<1s) time scales while operating under the low electric fields required when using solutions of physiological salinity.
Product Design Success Through Early Application of Design for Manufacturing and Assembly Workshops
Authors: Parker Bradley C.
Published: April 2008

Declining budgets and shortened schedules leave engineers little room for error in choosing a successful and profitable design concept. A redesign at any point in the program will destroy the product schedule, budget, and design cost goals. One tool for choosing a cost effective, fully compliant design is the Design for Manufacturing and Assembly (DFMA) Workshop. Although DFMA Workshops are most frequently applied to existing products, the process is most effective when applied during the initial design phase eliminating the need for costly redesigns. The DFMA Workshop involves a team that includes all the stakeholders in the success of the design, including customers and suppliers. During the Workshop, the team applies the 11 DFMA Principles and brainstorms ideas to meet the product requirements. The team then evaluates the ideas for technical risk and feasibility and then choosing the most promising ideas to be implemented into the design.
A Regression-Based Energy Method for Estimating Engine Noise in the Automobile Passenger Compartment
Authors: Sung Shung H. , Nefske Donald J.
Published: April 2008

A regression-based energy method is developed for estimating the overall interior noise (dBA) and Articulation Index (AI) in the automobile passenger-compartment for engine operation at idle, 2500 rpm, and wide-open-throttle speeds. The method is developed for use in the early vehicle design stage for evaluating the effect of different vehicle and powertrain architecture designs on engine noise performance. Regression analyses from a database of standard vehicle chassis dynamometer tests are used to estimate the effect of vehicle and powertrain architectures on the acoustic energy response and resulting interior noise. Comparisons of the estimated versus measured dBA and AI responses show reasonable agreement for different powertrain types. However, the inclusion of only limited architecture details somewhat underestimates the actual response for certain engines and operating conditions.
Development of CFD Model for a Swirl Stabilized Spray Combustor
Authors: Perisetty Jyothi S. , Panchagnula Mahesh V. , Cui Jie
Published: April 2008

Swirling jet characteristics in a commercial burner are studied computationally. The analysis includes a 2D axisymmetric model of the burner which is extended to three dimensions with some preliminary results. In the current study, k-ε and RSM turbulence models were used to simulate the flow field. Specific computational strategies that were adopted to model the swirling flow are also discussed. It was found that the swirl component in the flow caused a flow reversal along the axis resulting in the formation of centretoroidal zone. Case studies ranging from low swirl number of 1.28 to swirl number 3.75 are presented. The vortex size seems to exhibit two types of behavior. For low swirl numbers, the vortex size takes discrete sizes depending on various ranges of swirl numbers. For large swirl numbers, the vortex size seems to demonstrate a continuous increase.
Gear Condition Monitoring and Classification Using Wireless Sensor Networks
Authors: Xue Xin , Sundararajan V. , Gonzalez Luis
Published: April 2008

Current research in wireless sensor networks has chiefly focused on environmental monitoring applications. Wireless sensors are emerging as viable instrumentation techniques for industrial applications because of their flexibility, non-intrusive operation, safety and their low cost, low power characteristics. We describe a prototype gear condition monitoring system incorporating wireless sensors. Measurements of strain on gear teeth, vibration and temperature were undertaken using strain gage, accelerometer, and thermistors, respectively. The sensors interface to a sensor board that is connected to a microprocessor and a radio. Gear faults diagnosis using conventional classification techniques such as principle component analysis (PCA), Fisher linear discriminant analysis (LDA) and Nearest-Neighbor Rule (NNR) is studied in this paper. Two sets of vibration data, one set of strain data, and three sets of temperature data are used to classify a running gear under normal condition and a running gear with simulated crack teeth. Feature level data fusion is used to test the classification performance of simple but less effective features to study the fusion effects. The results show high performance of strain features, high quality of the classifier and obvious fusion effect which increases the classification performance.
Axial Temperature Profile in a Cylindrical Tensile Bar Carrying a Large Electric Current During a Tensile Test
Authors: Warley Russell L. , Roth John T.
Published: April 2008

Recent research has shown that passing DC electric current through a metallic tensile test specimen during deformation decreases the energy required to deform a specimen to a greater extent than that expected due to resistive heating. Prior resistive heating models have been successful in predicting temperatures in the absence of test sample deformation. In this work a 1D transient thermal model of a cylindrical cross section tensile bar is solved for the case where the sample is carrying a large DC electric current while simultaneously being deformed to fracture. The model uses a simplified representation of the necking process to provide geometrical information to the heat transfer model during the latter phases of deformation. Simulation results are compared to experimental surface temperature data.
Commercial Integrated Energy Systems Provide Data That Advance Combined Cooling, Heating, and Power
Authors: Petrov Andrei Y. , Berry Jeanette B. , Zaltash Abdolreza
Published: April 2008

The Department of Energy (DOE), though Oak Ridge National Laboratory (ORNL), has worked in partnership with industry to develop highly-efficient Integrated Energy Systems (IES) that provide combined cooling, heating, and power (CHP). Equipment configurations and performance have been optimized and system construction has been simplified, resulting in lower design and installation costs. Consequently, government-industry partnerships are achieving the goal of promoting replication of these advanced systems. This paper describes and presents data collected during the operation of on-site power generation systems developed and implemented by DOE/ORNL-industry teams: (1) Burns & McDonnell and (2) Honeywell Labs. The Burns & McDonnell IES is operated by Austin Energy, the municipal utility in Austin, Texas. The gas turbine produces 4.5-MW of electricity, and its exhaust drives a 2,500-ton absorption chiller. The featured project implements a modular system design that is being used to construct a medical district utility at Dell Children's Medical Center of Central Texas-another government-industry project carried out in partnership with Austin Energy. The Honeywell IES at Ft. Bragg, North Carolina, is anchored by 5.7-MW natural-gas turbine that uses turbine exhaust to drive a 1,000-ton absorption chiller and/or an 80,000-lb/h heat recovery steam generator. An optimization software program provides system operators with hour-by-hour information on system costs associated with various operating scenarios. The project developed reference designs for 1.2-5.7 MW turbine-based systems to better communicate options for system design and facilitate feasibility studies. These systems demonstrate the thermal and economic value of "waste heat" by providing space heating and/or cooling with no additional fuel use. Field data confirms that the fuel use efficiency of these combined cooling, heating and power systems approaches 80% based on the higher heating value (HHV) of natural gas.
Matrix Vibration Formulation of Damped Multi-Span Beams
Authors: Claeyssen Julio R. , Copetti Rosemaira Dalcin , Tsukazan Teresa
Published: April 2008

In this work we consider segmented Euler-Bernoulli beams that can have an internal damping of the type Kelvin-Voight and external viscous damping at the discontinuities of the sections. In the literature, the study of this kind of beams has been sufficiently studied with proportional damping only, however the effects of non-proportional damping has been little studied in terms of modal analysis. The obtaining of the modes of segmented beams can be accomplished with a the state space methodology or with the classical Euler construction of responses. Here, we follow a newtonian approach with the use of the impulse response of beams subject both types of damping. The use of the dynamical basis, generated by the fundamental solution of a differential equation of fourth order, allows to formulate the eigenvalue problem and the shapes of the modes in a compact manner. For this, we formulate in a block manner the boundary conditions and intermediate conditions at the beam and values of the fundamental matrix at the ends of the beam and in the points intermediate. We have chosen a basis generated by a fundamental response and it derivatives. The elements of this basis has the same shape with a convenient translation for each segment. This choice reduce computations with the number of constants to be determined to find only the ones that correspond to the first segment. The eigenanalysis will allow to study forced responses of multi-span Euler-Bernoulli beams under classical and non-classical boundary conditions as well as multi-walled carbon nanotubes (MWNT) that are modelled as an assemblage of Euler-Bernoulli beams connected throughout their length by springs subject to van der Waals interaction between any two adjacent nanotubes.
Interface Instability and Morphology Evolution of Thin Films Induced by Electrostatic Interaction
Authors: Kim Dongchoul , Lu Wei
Published: April 2008

Experiments have shown that a thin polymer film subjected to an electrostatic field may lose stability at the polymer-air interface, leading to uniform self-organized pillars emerging out of the film surface. This paper presents a three dimensional model to account for this behavior. Attention is focused on a fully nonlinear evolution simulation to reveal the dynamic process from an early perturbation to late structure formation. Energetic components involving the interface energy and dielectric effect, and kinetics of coupled viscous flow and diffusion are incorporated into a phase field framework. The semi-implicit Fourier spectral method and preconditioned biconjugate-gradient method are applied for high efficiency and numerical stability. The simulations reveal rich dynamics of the pattern formation process, and show that the kinetic constraint of the substrate can essentially limit structure coarsening. The pillar size is insensitive to the film thickness while the distance between pillars and the growth rate are significantly affected. The study also suggests an approach to control structural formation in thin films with a designed electric field.
Closed Form Solutions for the Motion of Electrically Excited Micro-Cantilever Beams
Authors: Oskouei Seyed Babak Ghaemi , Ahmadian Mohammad Taghi
Published: April 2008

The differential equation governing the motion of an electrically excited capacitive microcantilever beam is a nonlinear PDE [1]. Accurate analysis about its motion is of great importance in MEMS' dynamical response. In this paper first the nonlinear 4th order 2 point boundary value problem (ODE) governing the static deflection of the system is solved using three methods. 1. The nonlinear part is linearized and its exact solution is obtained. 2. For low applied DC voltages (not near pull-in) the solutin is found using the direct straight forward perturbation analysis. 3. Numerical computer solutions which are used for the previous solution's verifications. The next parts are devoted to the dynamic solution. The nonlinear time variant 4th order PDE governing the dynamic deflection of an electrically excited microbeam is scrutinized. First using the Galerkin Method the mode shapes and the first three mode temporal equations of the linearized equation are found. Considering no damping, using the perturbations method the temporal equations are solved in three states: far from resonance, near 1:1 resonance and near 1:2 resonance. Finally the damped equation is solved using the aforementioned method. In the literature no closed form solution for this problem is presented.
Influence of Individual and Team Rewards on Collaboration and Productivity of Team
Authors: Veluru Nanda Kishore , Takai Shun
Published: April 2008

Due to an increased globalization in modern system development, there is a growing need for engineers to collaborate with other engineers in distant locations, in different organizations, and across different disciplines. An effective collaboration among engineers is the key to successful system development and engineering projects. A cross-functional team is an example. The need for collaboration in real engineering environment has resulted in increasing numbers of team-based projects in undergraduate and graduate programs. This paper uses an economic prisoner's dilemma game to investigate how students decide to collaborate in hypothetical team projects under different individual and team reward schemes. Experiment results suggest that individual rewards may significantly reduce students' intention to collaborate with their teammates. Lack of collaboration resulted in lower productivity in the prisoner's dilemma framework.
Designed Formation of Nanocomposites via Dipole Interaction
Authors: Salac David , Lu Wei
Published: April 2008

The formation of designed nanocomposites by multiple layers of adsorbate molecules is studied. We consider the presence of two types of molecules in each layer, which are characterized by different dipole moments. The nanostructures are characterized by the non-uniform distribution of the two molecules. A phase field model is developed to simulate the molecular diffusion and patterning under the combined actions of dipole moments, intermolecular forces, entropy, and external electric field. The study reveals self-alignment, structure conformation and the possibility to reduce the domain sizes via a layer by layer approach. It is also shown that the structure in a layer may define the roadway for molecules to travel on top it. This combined with electrodes embedded in the substrate gives much flexibility to guide the molecular organization and fabrication of designed nanocomposites.
Reactive Ion Etching of Light Emitting MEH-PPV and Conducting PEDOT:PSS Polymer Materials
Authors: Raut Brijesh , Chambers David Keith , O'Neal Chad B. , Selmic Sandra
Published: April 2008

In this paper the selective patterning of poly [2-methoxy-5-(2'-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV) and poly (3, 4-ethylenedioxythiophene) poly (styrenesulfonate) (PEDOT: PSS) based on reactive ion etching for device fabrication is examined. These polymers were anisotropically etched using RIE in a helium plasma. Results show clearly that RIE using helium gas is effective at etching the polymers from the selected areas without physical damage to the working device. Further results show the electroluminescence spectra of etched and unetched devices have almost identical emission spectra, when these devices are operated as an LED. The external quantum efficiency (EQE) for these photodetectors was calculated and EQE peak values reached at 580nm are consistent between etched devices and unetched controls. Test devices show no decrease in EQE performance from RIE.
Experimental Study of Flow in Micropipette
Authors: Song Zhuorui , Lin Bochuan , Heng Heng , Liu Suyi
Published: April 2008

Micropipette injection has wide applications in genetic, physiological, pharmacological and micro-chemical research at pico-liter or sub-pico liter level. Micropipettes are generally tapered glass tubes with the inner exit diameter of 0.2 to a few microns. The quantitative relationship describing the injection volume and the operational parameters and pipette geometry in the microinjection process, however, has never established. This paper experimentally studied the injection flow rate as a function of injection pressure as well as the pipette geometry and fluid properties for the hydrophilic glass surface. It was found that the experimental pressure drop for the pressure-driven flow was always less than that was predicted by the classical theory with no slip boundary conditions. A model with slip boundary condition was developed for the axisymmetric conical flow and the result agreed well with computational simulation with slip boundary and the experimental data. The analysis indicated that the slip length was about 0.12 μ for water flow through micropipette of exit diameter 0.94 ~ 4.48 μm, half cone angle 3.3 ~ 5.2°, surface roughness 2.1 ~3.8 nm with shear rate ranging from 106 to 107 s-1.
Proton Conductive Strontium Cerate Thin Films Processed Using Flame-Assisted Chemical Vapor Deposition
Authors: Xu Zhigang , Young Gregory , Rajaram Gukan , Sankar Jag
Published: April 2008

Thin films of SrCe0.95Y0.05O3 have been successfully prepared on Si(100) substrates using flame-assisted chemical vapor deposition. XRD characterization shows the inclusion of fluorite phase of CeO2 in the perovskite phases, which may be caused by strontium depletion during deposition. The effects of total-metal concentration in the solution and substrate temperature on the surface morphology and think thickness growth of the coatings have been explored. It was found that both the intermediate concentration and temperature produces smoothest films and increasing the concentration had more significant effect on enhancement of the film thickness growth.
Wear of Involute Spur Gears With Asymmetric Teeth Under Dynamic Loading
Authors: Karpat F. , Ekwaro-Osire S.
Published: April 2008

Spur gears with asymmetric teeth have a significant potential for some applications requiring extreme performance like in the aerospace industry. In this study, the influence of tooth wear on the dynamic behavior of involute spur gears with asymmetric teeth is analyzed. The Archard's wear model was adopted in formulating and accounting for wear. Effects of gear parameters such as gear contact ratio, tooth height, mesh stiffness, and pressure angles on tooth wear are considered. These parameters are used to describe the relationship between dynamic tooth load and tooth wear. A comparison of symmetric and asymmetric teeth is also presented with respect to tooth wear. Sample simulation results, which were obtained by using an in-house developed computer program, are illustrated with numerical examples. The numerical results match well with the practical and analytical results which are available in literature. For asymmetric teeth, it was shown that the wear depth decreased with increasing pressure angle on drive side.
A MEMS-Based Micro Heat Engine With Integrated Thermal Switch
Authors: Weiss L. W. , Cho J. H. , Morris D. J. , Bahr D. F. , Richards C. D. , Richards R. F.
Published: April 2008

This work details the effect of top membrane compliance on the performance of a MEMS based micro-heat engine and integrated thermal switch at operating speeds of 20, 40, and 100Hz and heat inputs of up to 60mJ per cycle. The engine consists of two flexible membranes encapsulating a volume of saturated working fluid. A thermal switch is used to intermittently reject heat from the engine to a constant temperature cooling sink. Mechanical work output is measured based on the engine's top membrane deflection and internal operating pressure. Three top membranes are considered; a 2micron thick silicon membrane, a 300nm thick silicon-nitride membrane, and a 3micron thick corrugated silicon membrane. The engine is shown to produce 1.0mW of mechanical power when operated at 100Hz.
Product Composition Selection Problem: A Fuzzy-Goal Programming Approach
Authors: Choudhury Abhijit K. , Allada V.
Published: April 2008

In order to achieve mass customization, companies focus on the effective usage of the Modules-of-the-shelf (MOTS) as opposed to purely relying on developing Product Specific Modules (PSM). Hence, there is a need to develop a proper methodology to evaluate the "develop PSM vs. use MOTS" decisions. This decision holds greater significance for the modular architecture, as increase in the PSM leads to decrease in the degree of the modularization of the product architecture. The compatibility issue of the MOTS and PSM has been explicitly defined in the present paper. While making the abovementioned decision, information pertaining to suppliers providing the components/modules is critical. In this study, in addition to the common criteria like cost and performance, we have also included risk assessment of the suppliers while selecting them for providing the modules. This leads to the development of a multi-objective design optimization formulation to determine the amount of MOTS and PSM in the product. To cope with the vagueness inherent in the various decision parameters, a fuzzy goal programming based approach has been applied. The design problem of a TV receiver circuit has been taken from the literature to show the efficacy of the proposed methodology.
Design of Phononic Materials/Structures Using Toplogy Optimization
Authors: Rupp Cory J. , Evgrafov Anton , Maute Kurt , Dunn Martin L.
Published: April 2008

We develop a topology optimization approach to design two- and three-dimensional phononic materials/structures. Whereas most phononic crystals are based on ideas of periodicity, our approach relieves us of this constraint and allows for the creation of much more complex and efficient designs. It also enables us to go beyond simple filters and waveguides to the point of creating phononic devices. We focus on surface wave devices which carry the energy of the wave near and along the surface of the device. The design of surface wave devices is particularly attractive given recent advances in nano- and micro-manufacturing processes, such as thin-film deposition, etching, and lithography, which make it possible to precisely place thin film materials on a substrate with sub-micron feature resolution. The thin films can be made thick enough to affect most of the energy propagating in the surface wave and therefore a patterned thin film is all that is needed to create a surface wave device. It is the role of topology optimization to determine this pattern.
Molecular Dynamics Simulation of Ion Distribution in Nanochannels
Authors: Xu Dongyan , Li Deyu , Leng Yongsheng , Chen Yunfei
Published: April 2008

Ion distribution in nanochannels with overlapped electric double layers is important for understanding many interesting phenomena in nature and designing novel nanofluidic devices for different applications. Molecular Dynamics has been proved to be a powerful tool to study the ion distribution and electroosmotic flow inside nanochannels. However, a big problem in molecular dynamics simulation is the assignment of the number of ions in the simulation domain since no theory is available to determine the number of ions in the nanochannel, which is directly related to the chemical potential of the bulk electrolyte. In the literature, attention has been paid mainly to meet the requirement of the overall neutrality among surface charges and mobile ions. However, since both positive and negative ions may exist in the solution, the exact number of positive and negative ions corresponding to certain bulk concentration was unknown and assigned somewhat arbitrarily. We believe that this arbitrary assignment may lead to artificial results and tries to attack this fundamental problem in molecular dynamics simulation by extending the simulation domain to include two bulk regions sandwiching the nanochannel of interest. This way, when the system reaches equilibrium, the concentration of the electrolyte in the bulk region and the number of ions in the center region will emerge naturally instead of artificially assigned. It was shown that both cation and anion concentrations in the nanochannel could be significantly different from the ion concentration in the bulk region.
Verification and Validation Studies for a Laminar Non-Premixed Methane/Air Flame
Authors: Gokaltun S. , Skudarnov P. V. , Lin C. X.
Published: April 2008

In this paper, verification and validation analysis for a nonpremixed methane/air laminar flame is presented. Numerical results were obtained using the finite volume method on structured grids. The verification of the numerical solutions was performed by using the Grid Convergence Index (GCI) and Richardson extrapolation techniques. A set of three different grids is used to calculate the error due to discretization where each grid was generated by doubling the number of cells in each direction of the coarser grid. The local value of GCI was used to calculate the observed order of convergence of the numerical method for local values of temperature and mass fractions of reaction products at various points along the flow domain. The largest error band at the finest grid solution was observed to be 4.6% for the static temperature, 0.5% for the mass fraction of methane and 2.9% for the mass fraction of water vapor. Finally the numerical results were validated with experimental data using the local measurements of temperature and species mass fractions. The results indicate that there is relatively good agreement between the present results and experimental data although a simple one-step reaction model was used for the methane/air combustion. The average deviation was found to be around 25%, 21% and 10% for temperature, methane mass fraction and water vapor mass fraction respectively.
Film Cooling Effectiveness Distributions on a Turbine Blade Cascade Platform With Stator-Rotor Purge and Discrete Film Hole Flows
Authors: Wright Lesley M. , Blake Sarah A. , Han Je-Chin
Published: April 2008

An experimental investigation has been completed to obtain detailed film cooling effectiveness distributions on a cooled turbine blade platform within a linear cascade. The platform has a labyrinth-like seal upstream of the blades to model a realistic stator-rotor seal configuration. Additional coolant is supplied to the downstream half of the platform via discrete film cooling holes. The coolant flow rate through the upstream seal varies from 0.5% to 2.0% of the mainstream flow, while the blowing ratio of the coolant through the discrete holes varies from 0.5 to 2.0 (based on the mainstream velocity at the exit of the cascade). Detailed film cooling effectiveness distributions are obtained using the pressure sensitive paint (PSP) technique under a wide range of coolant flow conditions and various freestream turbulence levels (0.75% or 13.4%). The PSP technique clearly shows how adversely the coolant is affected by the passage induced flow. With only purge flow from the upstream seal, the coolant flow rate must exceed 1.5% of the mainstream flow in order to adequately cover the entire passage. However, if discrete film holes are used on the downstream half of the passage, the platform can be protected while using less coolant (i.e. the seal flow rate can be reduced).
Modulation of PFC Pyramidal Cell Excitability by Clonidine: A Computational Modeling Study
Authors: Jang T. S. , Nair J. , Nair S. , Lavin A.
Published: April 2008

The prefrontal cortex (PFC) is critically involved in cognitive processes underlying working memory (WM), attention, and inhibition of responses to non-relevant stimuli (Fuster, 2000; Goldman-Rakic, 1996). In this context, catecholaminergic inputs have proven to be critical for the regulation of these cognitive processes (Levitt et al., 1984; Lewis et al., 1987; Lewis and Morrison, 1989; Porrino and Goldman-Rakic, 1982). Aston-Jones and Bloom (1981a, b) showed that, in addition to dopamine (DA) the norepinephrine (NE) neurons located in the locus coeruleus (LC) and terminating in the PFC are important in mediating selective and sustained attention and vigilance. Moreover, stimulation of the LC increases the discrimination of incoming external stimuli to the PFC by reducing the background noise, therefore enhancing the cortical signal-to-noise ratio (Aston-Jones et al., 1985; Berridge and Waterhouse, 2003; Foote et al., 1980, 1983; Waterhouse et al., 1980; Robbins, 2000). More recently, several studies have shown that adrenergic agonists, especially specific alpha-2 agonists, are very effective in enhancing WM and attention. Indeed, administration of alpha-2 agonists can ameliorate some of the negative effects on cognition produced by NE depletion due to aging in monkeys (Arnsten and Goldman-Rakic, 1985; Arnsten et al., 1988; Arnsten and Leslie, 1991) and improve performance in WM-related tasks in young monkeys with NE depletion (Arnsten and Goldman-Rakic, 1985; Cai et al., 1993). Moreover, the therapeutic effects of the specific alpha-2 agonists, clonidine and guanfacine in treating disorders related to dysfunction of WM in patients have been proved (Fields et al., 1988; Mair and McEntree 1986, 1988; Hunt et al., 1985, 1990, 1995).
Optimal Architecture of Shack Hartmann Wave-Front Sensor for Microfluidic Applications
Authors: Cyca M. J. , Spiewak S. A.
Published: April 2008

Means of measuring temperature and fluid flow in microelectromechanical systems (MEMS) continue to show limitations. This paper discusses the development of a noninvasive optical based temperature mapping technique for use in microsystems. The technique employs the Shack-Hartmann wave-front sensor (SHWFS), with documented accuracy in macroscale applications of ±0.7°C [1]. Microscale models indicate the potential to collect data with the same accuracy. With continued development, fluid flow monitoring by thermally seeding an element of fluid and using the SHWFS to detect the location of this heated element will be possible. This measurement technique can be applied to a variety of microfluidic devices, including biomedical devices, since the temperature "seed" can be small enough to prevent damage to sensitive biological systems.
Vehicle State Estimation Using Dynamic 7 Degree-of-Freedom Observer
Authors: Pylypchuk Valery N. , Moshchuk Nikolai K. , Chen Shih-Ken
Published: April 2008

This paper presents a dynamic Luenberger's observer design with wheel dynamics as an essential component. 7DOF model of the vertical vehicle dynamics is modified for the case of independent-solid axle suspension and applied to predicting the vehicle body and wheel states. The observer greatly reduces the effect of uncertainty even with unknown road inputs. The design is verified through Carsim simulation and vehicle testing under variety of maneuvers including Fishhook and frequency response on a flat surface, straight line driving on a rough road, and on a cross-slope roads.
Measurements of Mechanical Properties of Human Red Blood Cells
Authors: Park Choongbae , Wereley Steven T. , Campanella Osvaldo H. , Nivens David E. , Little Kenneth M. , Sumali Hartono
Published: April 2008

We developed a novel method to measure the rheological properties of single red blood cells (RBC) using the atomic force microscope (AFM). A spherical bead at the AFM cantilever tip compressed and relaxed the RBC. The force and displacement were converted into effective stress and strain. The impulse viscoelastic technique was used to compute the effective storage (E') and loss (E") moduli and phase lag (δ). Unfixed and fixed red blood cells were tested. Both cells were on glass coated with poly-l-lysine and then kept in phosphate buffered saline (PBS) until the experiment was finished. Measurements were done with height change and force up to 451nm and 64nN. The cells were found to be quite elastic, with phase lag on the order of 10-2 to 10-1 rad. Stepped changes in oscillation rate from 0.5Hz to 2.5Hz did not result in significant change in the measured results. To improve accuracy, we also design a bimaterial cantilever which consists of a gold layer on silicon with controlled thermal stresses such that the cantilever is curved. The curvature allows the root to fits the angle of the AFM head and the tip to be parallel to the substrate so that the RBC is squeezed between two parallel surfaces.
Daily Management: The Foundation for Equipment Reliability
Authors: Edwards Dennis C.
Published: April 2008

Many manufacturing firms take on a variety of improvement initiatives without having first successfully mastered the various aspects of Daily Management. Daily Management, while simple in its concept, is typically difficult to master and requires an organization to undergo a cultural transformation. For "best-in-class" performance, the various elements that make up Daily Management must become embedded in the new manufacturing culture. Failing to fully learn & sustain the individual elements of Daily Management leads to organizational frustration and becomes the overriding factor with unsuccessful implementations of Quantum Leap Management initiatives. Daily Management must be an integral "tool kit" while traveling the reliability roadmap to manufacturing excellence. Several examples of significant performance results using only Daily Management principles will be shared with conference attendees.
Fuel Dynamics Model for Engine Coldstart
Authors: Zavala J. Carlos , Gu¨nther Dietmar , Sanketi Pannag , Wilcutts Mark , Hedrick Karl
Published: April 2008

Different strategies have been used in the past to improve the performance of hydrocarbon emissions controllers in SI engines. One of them relies on the use of the model-based control design scheme, which offers the possibility of automating the controller design-to-implementation phase. It also gives the chance to update the model with a potential reduction in required experiments if physical changes are made to the plant. Under the model-based scheme, an accurate plant model can greatly enhance the development of an effective control systems. In particular, acquiring a correct fuel-dynamics model can be crucial in developing a good hydrocarbon emissions controller for coldstart. During this period, the factory AFR (air-fuel ratio) sensor is not active and the engine experiences an abrupt transient, which makes modeling difficult. In this paper, a model that describes fuel dynamics for coldstart is developed. The model uses mainly two parameters: one of them accounts for the fraction of injected fuel that runs directly into the cylinders and the other represents the time constant of fuel vaporization from the wall-wetting film formed in the intake port. Two discretized versions of the model are evaluated and compared. The parameters are calculated at different intake port temperatures. To implement the proposed model, experiments are carried out using a 4-cylinder SI MPFI combustion engine connected to a Simulink interface with capabilities of automatic code generation. Factory controller measurements and other external measurements such as intake port temperature and broadband AFR sensor measurements are used to fit the model parameters. Parameter identification techniques are used to identify the values of the parameters. Both versions of the fuel dynamics model are then tested during coldstart cycles and the results are analyzed.
Characterizing 2-D Topographic Mappings of Roads
Authors: Kern Joshua V. , Ferris John B.
Published: April 2008

Load data representing severe customer usage is needed throughout a chassis development program; the majority of these chassis loads originate with the excitation from the road. These chassis loads are increasingly derived from vehicle simulations, however simulating a vehicle traversing long roads is impractical and a method to produce short roads with given characteristics must be developed. The first step is to consider the road to be a realization of an underlying stochastic process. There are many methods currently available to characterize roads when they are assumed to be homogeneous. The issue of non-stationarity that arises when a vehicle traverses a homogenous road at a varying speed has also been discussed. This work develops of method of characterizing non-stationary road profile data using a pure autoregressive process. The model is developed utilizing the sample autocorrelation and partial autocorrelation functions. The adequacy of the model is evaluated through statistical diagnostic checks performed on synthetic road data generated by the autoregressive model parameters. Use of these parameters to classify roads is also discussed as possible future work. Any synthetic road realized from a given class of model parameters will represent all roads in that set.