bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation of Pulverized Coal Injection in a Blast Furnace
Authors: Gu Mingyan , Chen Zumao , Selvarasu Naresh K. , Huang D. , Chaubal Pinakin , Zhou Chenn Q.
Published: April 2008

A three-dimensional multiphase CFD model using an Eulerian approach is developed to simulate the process of pulverized coal injection into a blast furnace. The model provides the detailed fields of fluid flow velocity, temperatures, and compositions, as well as coal mass distributions during the devolatilization and combustion of the coal. This paper focuses on coal devolatilization and combustion in the space before entering the raceway of the blast furnace. Parametric studies have been conducted to investigate the effect of coal properties and injection operations.
Design Space Exploration of Multi-Phase Layered Phononic Materials via Natural Evolution
Authors: El-Beltagy Mohammed A. , Hussein Mahmoud I.
Published: April 2008

A phononic material is commonly characterized by its dispersive frequency spectrum. With appropriate spatial distribution of the constituent material phases, spectral stop bands could be generated. Moreover, it is possible to control the number, the width, and the location of these bands within a frequency range of interest. This study aims at exploring the relationship between the unit cell configuration and its frequency spectrum characteristics. Focusing on 1D layered phononic materials, and longitudinal wave propagation in the direction normal to the layering, the unit cell features of interest are the number of layers and the material phase and relative thickness of each layer. An evolutionary search for multi-phase cell designs exhibiting a wide stop band, or a series of wide stop bands, is conducted using a specially formulated representation and set of operators that break the symmetries in the problem. An array of optimal designs for a range of ratios in Young's modulus and density are obtained and the corresponding objective values are plotted as a function of the ratios of the phase properties. Structures composed of the designed phononic materials are excellent candidates for use in a wide range of applications including vibration and sound isolation.
Effect of Superposition on Spanwise Film-Cooling Effectiveness Distribution on a Gas Turbine Blade
Authors: Mhetras Shantanu , Han Je-Chin
Published: April 2008

The effect of film cooling holes placed along the span of high pressure turbine blade in a 5 bladed linear cascade on film cooling effectiveness is studied using the Pressure Sensitive Paint (PSP) technique. Four rows of film cooling holes are provided on the pressure side while two such rows are provided on the suction side of the blade. Around 22 cylindrical holes with a diameter of 0.65mm are drilled in each row at a compound angle of 45° to the blade span in the radial direction and at 45° in the axial direction. Film cooling effectiveness over the entire blade region is determined from full coverage film cooling with coolant blowing from all rows and from each individual row. The effect of superposition of film cooling effectiveness from each individual row is then compared with full coverage film cooling. The coolant is injected at four different average blowing ratios of 0.6, 0.9, 1.2 and 1.5. The free stream Reynolds number, based on the axial chord length and the exit velocity, is 750,000 and the inlet and the exit Mach numbers are 0.27 and 0.44, respectively resulting in a blade pressure ratio of 1.14. Turbulence intensity level at the cascade inlet is 6% with an integral length scale of around 5cm. Results show that the effectiveness magnitudes from superposition of effectiveness data from individual rows are comparable with that from full coverage film cooling. Varying blowing ratios can have a significant impact on film-cooling effectiveness distribution with a blowing ratio of 0.6 showing highest effectiveness immediately downstream of the holes.
Thermal Issues in Lithium-Ion Batteries
Authors: Alavi-Soltani S. R. , Ravigururajan T. S. , Rezac Mary
Published: April 2008

This paper reviews various studies carried out on thermal issues in lithium-ion batteries. Although thermal behavior of Li-ion batteries plays an important role in performance, life cycle and safety of these batteries, it has not been studied as intensely as chemical characteristics of these batteries. In this review paper, studies concerning thermal issues on Li-ion batteries are classified based on their methodologies and the battery components being investigated. The methodologies include mathematical thermal modeling, calorimetry, electrochemical impedance spectroscopy and thermal management system method. The battery components that have been studied include anode, cathode, electrolyte and the whole cell.
Vision Based Force Sensing for Nanorobotic Manipulation
Authors: Gupta Abhishek , Patoglu Volkan , O'Malley Marcia K.
Published: April 2008

Over the last decade, considerable interest has been generated in building and manipulating nanoscale structures. Applications of nanomanipulation include study of nanoparticles, molecules, DNA and viruses, and bottom-up nanoassembly. We propose a Nanomanipulation System using the Zyvex S100 nanomanipulator, which operates within a scanning electron microscope (SEM), as its primary component. The primary advantage of the S100 setup over standard scanning probe microscopy based nanomanipulators is the ability to see the object during manipulation. Relying on visual feedback alone to control the nanomanipulator is not preferable due to perceptual limitations of depth and contact within the SEM. To improve operator performance over visual feedback alone, an impedance-controlled bilateral teleoperation setup is envisioned. Lack of on-board force sensors on the S100 system is the primary hindrance in the realization of the proposed architecture. In this paper, we present a computer vision based force sensing scheme. The advantages of this sensing strategy include its low cost and lack of requirement of hardware modification(s). Force sensing is implemented using an atomic force microscopy (AFM) probe attached to the S100 end-effector. Deformation of the cantilever probe is monitored using a Hough transform based algorithm. These deformations are mapped to corresponding end-effector forces following the Euler-Bernoulli beam mechanics model. The forces thus sensed can be used to provide force-feedback to the operator through a master manipulator.
An Investigation of Evaporation Heat Transfer in Sintered Copper Wicks With Microgrooves
Authors: Zhao Yuan , Chen Chung-Lung
Published: April 2008

This paper presents an experimental study on the parameters that determine the thermal performance of sintered copper wicks with longitudinal micro grooves for heat pipe applications. The grooves, which provide passages to vent vapor, have a width in a range from 150 μm to 500 μm. The copper powder used here has a nominal diameter of 50 μm, which produces an effective pore radius of approximately 13 μm. The main wicks composed of pores and grooves present characteristics of bi-dispersed wick structures. Unlike traditional bi-dispersed wick structures, the sintered grooved wick structures provide undisrupted longitudinal liquid delivery passages and thus improve the boiling limit. Performance of the wick structures with distilled water was examined and the effects of the heat flux and groove geometries on the evaporation/boiling heat transfer performance were studied.
Failure Mechanisms of MEMS Thermal Actuators
Authors: Paryab Nasim , Jahed Hamid , Khajepour Amir
Published: April 2008

Predicting and eliminating failure modes of MEMS polysilicon thermal actuators as one of the elementary bricks of a more complicated device can save months of time as well as money to repair, reproduce, or even redesign the device. There are validated reports of time-dependent failure in flexural polysilicon MEMS actuators. MEMS thermal actuators are under high temperature and cyclic loads. Therefore, fatigue and creep are suitable candidates in determining failure mechanisms. Here, both fatigue and creep failure mechanisms are studied theoretically and experimentally. A comprehensive finite element modeling is employed to find temperature and stress distribution in the actuators. It is shown, that polysilicon MEMS thermal actuator are less prone to fatigue failure and creep is the main cause of failure in MEMS thermal actuators.
Ballistic Impact Response of Composite Systems
Authors: Elbella Abdalla , Saride Santosh Kumar
Published: April 2008

Composite materials are widely used in many engineering applications and are an attractive for armor design because of their increased high toughness, impact resistance, stiffness, and strength-to-weight ratios and the ability to tailor their designs to applications. In this paper, numerical simulation of impact on composites is being performed to predict ballistic limit velocities and evaluate the delamination behavior of different composite systems. The normal impact and penetration of blunt rigid projectile on laminated composite targets was developed to estimate the velocity for which the projectile has complete penetration, the ballistic limits and energy absorbed while perforating a given piece of armor. A non-linear, explicit, three dimensional finite element commercial code (ABAQUS) is used to simulate the response of armor targets at V50 impact velocities. The armor test panel is modeled as a multi-layered laminated plate with different composite systems, thickness, and stacking sequence. The three failure modes that represent the three stages of the penetration process namely transverse shear, tensile fiber breakage, and delamination are identified. The ballistic limit curves for different materials, thickness, and orientations are determined. The target interlaminar stress distributions along the thickness are graphically represented. Strain energy, Plastic dissipation and Kinetic dissipation energy curves for the whole model were obtained including thickness effects.
Robust Control of a Hydraulic Metering Valve and Pump System Model
Authors: Bax Brian , Dean Patrick , Fales Roger
Published: April 2008

In this work modern robust control systems are designed and compared to standard techniques for a hydraulic implement system. The system includes a four orifice metering valve in an H-bridge configuration and a variable displacement pump. The four valve orifices are coupled so that there is only one input for the valves. There are two control inputs, one for the valve and one for the pump displacement. The complexity of the system makes classic control methods difficult to design. Parameter variations and unmodeled dynamics can cause sluggish performance and instability in some cases. By applying modern control, robustness can be improved relative to classical and single-input/single-output (SISO) control design techniques. Techniques such as H∞ control have been proven effective in many multiple-input/multiple-output (MIMO) applications. Linear analysis shows improvement in robustness characteristics of the system over a conventional PID control scheme. Nonlinear simulations show favorable system response and similarly positive robustness traits for the modern control design.
Analysis of Vehicle Longitudinal Dynamics for Longitudinal Ride Comfort
Authors: Koo Shiang-Lung , Tan Han-Shue , Tomizuka Masayoshi
Published: April 2008

Longitudinal ride comfort is one of the most crucial features to most advanced vehicle control systems. Literature review shows that the ride comfort analysis in vehicle longitudinal motion can be divided into two categories: time domain and frequency domain. Most vehicle longitudinal control designs incorporate jerk and acceleration constraints from the time-domain comfort criterion. However, the vehicle longitudinal characteristics in the frequency range important to passenger ride comfort are rarely discussed in the vehicle control literature. This paper proposes an improved vehicle longitudinal model that captures tire and suspension modes accurately and investigates the impact of these often-ignored vehicle resonant modes to ride comfort. This study shows that the "tire-mode switching behavior" affects longitudinal ride comfort of a stopping vehicle rather than the suspension. A passenger car was tested as an example, and the collected data verified the analytical prediction from the improved vehicle longitudinal model.
Modeling Molecular Interactions Arising From Adsorbed Biological Species on the Microcantilever Biosensor Surface
Authors: Afshari Mana , Jalili Nader
Published: April 2008

This paper presents a general framework for modeling resonance frequency changes induced due to the surface stress arising from the adsorption of biological species on the surface of the microcantilever biosensors. Very few works have dealt with the effect of surface stress on the resonance frequency shifts of microcantilevers and mainly assume a simple model for the vibrating microcantilever beam. In the proposed modeling framework, the nonlinear terms due to beam's flexural rigidity from macro- to micro-scale as well as varying nature of the longitudinal force resulting from the surface stress are considered. It is demonstrated that through applying the mathematical expression formulated in this paper, desired biological species can be easily and accurately detected.
Model Mediated Telemanipulation
Authors: Mitra Probal , Niemeyer Gu¨nter
Published: April 2008

A telemanipulation system allows a human user to manipulate a remote environment using a local interface (master robot) to control a remote (slave) robot. In doing so, it is desirable to provide users with appropriate sensory feedback, most often taking the form of visual and force information. In the presence of communication delays, however, a force feedback telemanipulation system must overcome detrimental effects caused by the delay, both on the quality of feedback to the user and the stability of the control system. For large delays, like those experienced in space telerobotics, the user's perceptive abilities are distorted and challenged by the lag between action and response. With this paper, a user-centered approach is proposed which seeks to simultaneously provide stable master-slave interaction as well as a natural user experience, tolerant of large delays. Rather than directly sending sensory information from the slave robot to the user, the goal is to use this information to create a real-time virtual model of the remote environment, which then serves as the user's interface. Maintaining a dynamic, virtual model locally at the master-side, the user is provided with immediate visual and haptic responses to his/her actions through the master device. At the remote site, the slave robot tracks the user's continuous and natural motion commands, while providing new information needed to update the virtual model. This method abstracts the data transmitted between the sites and creates greater delay tolerance. The basic principles of the approach are demonstrated on a simple one-degree of freedom telerobotic system, with a rigid, stationary slave environment.
Measurement of Specific Heat Using Bayesian Inference to Account for Uncertainties in the Calorimeter Performance
Authors: Emery A. F. , Abernethy K.
Published: April 2008

One way of estimating thermal conductivity is to measure the temperature history for transient conduction. Unfortunately, the property estimated is usually not the conductivity but the thermal diffusivity, α = k/ρcp. While α can often be estimated with good precision, and ρ is usually well defined, the specific heat is often poorly known. As a consequence the uncertainty in the conductivity can be large. This paper reports the use of a calorimeter designed to measure the specific heat with high accuracy. The accuracy depends upon a precise characterization of the thermal performance of the calorimeter. Even when much care is taken, the calorimeter's behavior introduces uncertainty in the measured specific heat. The effects of these uncertainties are accounted for by using Bayesian inference to estimate the confidence intervals of the specific heat.
A Physically Based Two-State Model for Controlling Exhaust Recompression HCCI in Gasoline Engines
Authors: Ravi Nikhil , Roelle Matthew J. , Jungkunz Adam F. , Gerdes J. Christian
Published: April 2008

Homogeneous Charge Compression Ignition (HCCI) presents several advantages over conventional IC engines, including improved efficiency and emissions. It is, however, difficult to implement and control due to the lack of an external combustion trigger. One way to achieve HCCI is to trap and recompress a portion of the exhaust in the cylinder to increase the sensible energy of the air-fuel mixture. Such a strategy, however, introduces a cyclic coupling through the exhaust gas retained from cycle to cycle, making dynamic control non-trivial. In order to develop model-based controllers for HCCI, the authors present a physically motivated two-state model of the HCCI process. This model specifically captures the behavior of a direct inject gasoline engine with an exhaust-recompression strategy used to achieve HCCI. As the trapped exhaust is pivotal in setting up the cyclic coupling, its temperature and the amount of oxygen present in it are selected as the states of the system. The system's dynamics are developed through these states to give a discrete-time nonlinear model that can be validated against a more complex continuous-time model. In this form, the model represents a control-oriented description of the HCCI engine as a thermodynamic system, and can therefore be used as a platform to synthesize various control strategies. As a demonstrative example, a linear representation of the system is derived and used to synthesize an LQR controller to track a desired state trajectory in simulation.
Sizing Study and Validation of a Hybridized Fuel Cell NEV With Bi-Directional Grid Inter-Connect for Sustainable Local Transportation
Authors: Guezennec Yann G. , Choi Ta-Young Gabriel , Marusiak Jeffrey , Yurkovich Benjamin , Choi Woongchul
Published: April 2008

Due to sharply increasing oil price, tremendous efforts are being made to reduce the dependencies on the petroleum based fuels in the field of automotive power trains. As one of the promising alternatives, fuel cell hybrid system has been studied for many different vehicle types from SUV to low speed vehicle. To establish systematic ways to achieve the optimized system configuration, in this paper, we introduce a methodology which combines energy analysis over typical drive cycles with a parametric sizing study for the various powertrain components as well as supervisory energy management parameters. For a practical and demonstrative implementation of the suggested methodology with a limited resource available at hand, a Neighborhood Electric Vehicle (NEV) for urban transportation is considered for a detailed analysis, design and optimization. Two major supervisory control strategies, namely, charge-sustaining and charge-depleting are carefully investigated to illustrate the versatility of our proposed methodology. Our study shows that the systems could be modeled and optimized either in a charge sustaining case or in a charge depleting case (plug-in hybrid electric vehicle) to meet vehicle purposes and usages, respectively. Not only because of the usage of the FC power system as a range extender for an EV, but also the possibility of using the plug-in configuration with renewable energy generation systems, as a personal eco-system, the proposed plug-in FC-NEV may be a solution for a local urban transportation system in this demanding era of sustainable mobility.
Growth of Carbon Nanotubes on Metallic Catalyst by CVD
Authors: Guo Kun , Jayatissa Ahalapitiya H.
Published: April 2008

The growth of carbon nanotubes was investigated using a filament assisted atmospheric CVD system. The scope of this study is two fold: (i) control the growth of carbon nanotubes by chemical treatment of catalysis surface and temperatures and (ii) study of nanotubes growth for gas sensor applications. We have conducted the growth of carbon nanotubes on surfaces by treatment of metal catalyst surface with different acids and plasma. The treated surfaces were kept in a furnace tube CVD and the nanotubes were grown using a hot filament assisted decomposition of methane (CH4) and argon (Ar) gas mixture. It was found that the growth of carbon nanotubes could be controlled by the catalysts, filament and furnaces temperature.
Design of Spring Coupling for High Q, High Frequency MEMS Filters
Authors: Shalaby Mohammed , Abdelmoneum Mohammed , Saitou Kazuhiro
Published: April 2008

This paper presents the design optimization of the coupling beam of wine glass (WG) mode micromechanical disk filters using the simulated annealing algorithm. The filter under consideration consists of two identical wine-glass mode disk resonators, mechanically coupled by a flexural mode beam. Such coupled two-resonator system exhibits two mechanical resonance modes with closely spaced frequencies that define the filter passband. The frequencies of the constituent resonators determine the center frequency of the filter, while the bandwidth is determined by the stiffness and location of attachment of the coupling beam. The goal is to design a filter with a commonly used bandwidth, namely 100 kHz. The design variables that control the bandwidth value are the beam length, the beam width, and the location of attachment of the coupling beam from the center. The simulated annealing algorithm is used to solve the optimization problem, since the governing dynamic equations of the resonator-coupling system are highly nonlinear. The resulting optimum design is simulated using the finite element method, which confirms the achievement of the desired center frequency and bandwidth.
An Optimal Vehicle Stability Enhancement Strategy for Articulated Vehicles
Authors: Goodarzi Avesta , Esmailzadeh Ebrahim
Published: April 2008

Rollover and jack-knifing of articulated heavy trucks are serious threats for motorists. Active safety technologies have been demonstrated to have potential to reduce or prevent the occurrence of these types of accidents. The vehicle dynamic control (VDC) system utilizes differential braking to affect vehicle response and has been shown to be quite effective in controlling vehicle yaw response. A VDC system that improves the yaw and lateral motions of an articulated vehicle has been developed. For this purpose, an optimal yaw-moment control law has been designed and the optimal values of the controller gains have been determined. The results of the numerical computer simulation show that very good performance of the proposed control system could be achieved.
Condition-Based Assessment of Damage Progression During Mechanical Shock in Electronic Assemblies
Authors: Lall Pradeep , Choudhary Prakriti , Gupta Sameed , Suhling Jeff
Published: April 2008

Electronic products may be subjected shock and vibration during shipping, normal usage and accidental drop. High-strain rate transient bending produced by such loads may result in failure of fine-pitch electronics. Current experimental techniques rely on electrical resistance for determination of failure. Significant advantage can be gained by prior knowledge of impending failure for applications where the consequences of system-failure may be catastrophic. This research effort focuses on an alternate approach to damage-quantification in electronic assemblies subjected to shock and vibration, without testing for electrical continuity. The proposed approach can be extended to monitor product-level damage. In this paper, statistical pattern recognition and leading indicators of shock-damage have been used to study the damage initiation and progression in shock and drop of electronic assemblies. Statistical pattern recognition is currently being employed in a variety of engineering and scientific disciplines such as biology, psychology, medicine, marketing, artificial intelligence, computer vision and remote sensing [Jain, et. al. 2000]. The application quantification of shock damage in electronic assemblies is new. Previously, free vibration of rectangular plates has been studied by various researchers [Leissa 1969, Young 1950, Gorman 1982, Gurgoze 1984, Wu 2003] for development of analytical closed-form models. In this paper, closed-form models have been developed for the eigen-frequencies and mode-shapes of electronic assemblies with various boundary conditions and component placement configurations. Model predictions have been validated with experimental data from modal analysis. Pristine configurations have been perturbed to quantify the degradation in confidence values with progression of damage. Sensitivity of leading indicators of shock-damage to subtle changes in boundary conditions, effective flexural rigidity, and transient strain response have been quantified. A damage index for Experimental Damage Monitoring has been developed using the failure indicators. The above damage monitoring approach is not based on electrical continuity and hence can be applied to any electronic assembly structure irrespective of the interconnections. The damage index developed provides parametric damage progression data, thus removing the limitation of current failure testing, where the damage progression can not be monitored. Hence the proposed method does not require the assumption that the failure occurs abruptly after some number of drops and can be extended to product level drops.
Thermo-Elastohydrodynamic Analysis of Elastomer Radial Lip Seals
Authors: Maoui A. , Hajjam M. , Bonneau D.
Published: April 2008

This paper aims to study a fully coupled thermal effect in the contact parts - lip surface, rotary shaft and lubricant film - on the elastohydrodynamic behaviour of radial lip seals. The results obtained show that most operating characteristics such as reverse pumping, minimal thickness and power loss are strongly influenced by the temperature distribution in the contact zone. Therefore, all operating characteristics computed by using the local approach are lower than those obtained by using the global approach.
A New Periodic Cellular Metal With Kagome Trusses and Its Performance
Authors: Lee Yong-Hyun , Choi Ji-Eun , Kang Ki-Ju
Published: April 2008

Periodic cellular metals (PCM), especially truss PCM's seem promising as new materials in 21 century. Various works have been performed for the mechanical and thermal performance. However, only a number of papers have been published regarding fabrication techniques of PCM, even though the techniques should determine whether PCM's is survived in the future market, or not. In this work a new type of PCM with Kagome trusses is presented. Continuous metal wires as the raw materials are assembled in six directions with least deflection, which gives very high specific strength and stiffness. The mechanical behavior under compression and bending of hand-made specimens is presented. Also, the benefits and features are discussed.
Visualization of Vertical Bubble Coalescence and Detachment Under the Influence of a Nonuniform Electric Field
Authors: Liu Z. , Herman C. , Mewes D.
Published: April 2008

The effect of a nonuniform electric field on the formation, coalescence and detachment of air bubbles injected into a stagnant, isothermal liquid through an orifice is studied to identify characteristic bubble behavior patterns. The results of the experimental visualization suggest significant differences in bubble shape and size caused by the electric field. The electric field was applied between a flat, circular and horizontal ground electrode and a spherical, off-axis top electrode. During formation the bubble was tilted towards or away from the upper electrode under the influence of the electric field. The direction of the tilt alternated (even in a single experiment), however, in the majority of the cases the bubble trajectory tilted towards the top electrode. The detachment frequency increased under the influence of the electric field, which indicates decreased bubble volume for lower volume flow rates. The effect of the electric field on vertical bubble coalescence was analyzed and quantified in terms of the detachment time.
Molecular Dynamics Simulations of Interactions at the Interface Between Functionalized Carbon Nanofibers and Polymer Resins
Authors: Gou J. , Anumakonda K.
Published: April 2008

The discovery of vapor grown carbon nanofibers has created a significant opportunity to develop high performance and cost-effective nanocomposite materials. However, significant challenges in the development of such composite materials lie in the poor dispersion of carbon nanofibers into polymer resins and the weak interfacial bonding between carbon nanofibers and polymer resins. These critical issues have to be addressed by chemical functionalization of carbon nanofibers. Understanding molecular interactions between functionalized carbon nanofibers and polymer resins is a crucial step towards their potential use in nanocomposites. In this work, the effects of surface functional groups on the molecular interactions between carbon nanofibers and polymer resins have been studied by using molecular dynamics simulations. It was found that chemical functionalization of vapor grown carbon nanofibers increased the amount of surface functional groups which disturbed the original smooth graphitic planes of carbon nanofibers. The functionalization of vapor grown carbon nanofibers decreased the amount of π-bonds on the nanofiber surface, which resulted in the weaker interaction with polymer resins. The simulation results provided fundamental information for the rational functionalization of vapor grown carbon nanofibers to manipulate their nanoscale properties in a predicative manner.
Direct Adaptive Tracking Control of Quadrotor Aerial Vehicles
Authors: Morel Yannick , Leonessa Alexander
Published: April 2008

This paper presents a novel adaptive control algorithm solving the trajectory tracking problem for quadrotor aerial vehicles. A model reference approach is used, such that the vehicle tracks the trajectory of a reference system, which itself tracks a specified desired trajectory. The control law is derived using a backstepping procedure. A technique derived from dynamic surface control is used to simplify the expression of the obtained control algorithm, with no significant loss in terms of performance. Proof of stability is obtained using Lyapunov theory. Results from numerical simulations illustrate the performance of the obtained controller.
Thermomechanical Effects in Packaging: Matching CTE or Not?
Authors: Pryputniewicz Ryszard J. (Rich) , Pryputniewicz Dariusz R.
Published: April 2008

Development of effective packages for microelectronics, MEMS, as well as for other microsystems and advanced modern devices, is usually based on minimization of thermomechanical effects and maximization of the useful life of a package. Such extremization-analysis depends on the effects that coefficients of thermal expansion (CTEs) have on the design of packages. This paper examines thermomechanics of a package and evaluates the effects that matching (or not) of CTEs may have on a package and its life. This examination is illustrated with representative examples.
Modeling and Simulation of Body-on-Frame Vehicles for Frontal Impact Sensing Tests
Authors: Lin Chin-Hsu , Wang J. T.
Published: April 2008

A capability for modeling and simulating frontal impact tests required by the crash sensing calibration task during the development process of a new motor vehicle is presented. The capability is applicable to the body-on-frame (BOF) vehicles such as light trucks and sport utility vehicles. Critical modeling techniques and guidelines for building a high fidelity frontal impact finite element BOF vehicle model were developed and validated using 15 full vehicle crash tests. The modeling techniques and guidelines can be used to model and simulate a suite of frontal impact sensing tests for BOF vehicles. Such a math-based capability could significantly reduce the development time and cost of a new light truck or sport utility vehicle.
Actuation Using Protein Transporters Driven by Proton Gradient
Authors: Sundaresan Vishnu Baba , Leo Donald J.
Published: April 2008

A new mechanical actuation concept is demonstrated based on the controlled transport of fluid across semipermeable membranes. This concept is based on the pressurization of cells similar to the process that plants use to maintain homeostasis and regulate cell function. In all plant systems, the transport of ions and fluid produce localized pressure changes (called turgor pressure) that perform many cell functions, such as maintaining cell integrity and controlling plant growth. In this paper we demonstrate that the concept of fluid transport caused by protein transporters can be used to control the actuation properties of a mesoscale device. The device considered in this work consists of two chambers separated by a semipermeable membrane substrate that contains protein transporters suspended in a lipid bilayer. The protein transporters convert biochemical energy in the form of ATP into a protein gradient across the semipermeable membrane. The proton gradient, in turn, induces a flow of fluid across the porous substrate and pressurizes a closed volume. The experimental demonstration uses a directly applied gradient The pressurization of the closed volume produces a deformation in the coverplate of the chamber, thus transforming the chemical energy of the ATP into a measurable motion in the actuator. Experiments on the device demonstrate that micron-scale displacements can be induced in a millimeter-scale actuator. The time constant of the response is on the order of tens of seconds, and results clearly demonstrate that the amount of ATP and ATPase control the actuation properties of the device. To our knowledge this is the first demonstration of using natural protein transporters as the active component of a mechanical actuator.
Spontaneous Liquid-Liquid Slug Flow in Microchannels
Authors: Hernandez Joseph E. , Allen Jeffrey S.
Published: April 2008

Spontaneous liquid-liquid slug (bislug) flow in microchannels has been observed for both circular and square cross sections. Flow is induced via an imbalance in interfacial tensions and curvatures between the two gas-liquid surfaces and the liquid-liquid surface. Bislug flow in square cross-section microchannels is generally much quicker than bislug flow in circular capillaries for a variety of reasons; including the self-wetting nature of the microchannel and the decrease in viscous resistance in the corners.
Mechanical Design Using Quantum-Behaved Particle Swarm Optimizer With Exponential Mutation Operator
Authors: Coelho Leandro dos Santos , Mariani Viviana Cocco
Published: April 2008

Particle swarm optimization (PSO) is a population-based swarm intelligence algorithm that shares many similarities with evolutionary computation techniques. However, the PSO is driven by the simulation of a social psychological metaphor motivated by collective behaviours of bird and other social organisms instead of the survival of the fittest individual. Inspired by the classical PSO method and quantum mechanics theories, this work presents new Quantum-behaved PSO (QPSO) approaches using mutation operator with exponential probability distribution. The simulation results demonstrate good performance of the QPSO in solving a well-studied continuous optimization problem of mechanical engineering design.
Micro and Nano Thin Film Devices as Bio-Assays for Cancer Diagnosis
Authors: Klein Kevin M. , Ostrowicki Gregory T. , Gerwitz Andrew , Sitaraman Suresh K.
Published: April 2008

Micro and nano Au/Cr and Al thin film devices have been fabricated using DC sputtering and e-beam evaporation in combination with e-beam and photo lithography. These devices can be coated with specific reagents to detect and measure the presence of particular antigens and/or complementary DNA sequences with a smaller sample size and at much earlier stages of disease progression compared to current medical diagnostic technologies. Using the device material stack (Au/Cr/Si), we have assessed the binding affinity of Au, Cr, and Si with Protein G, and antibodies for Prostate Specific Antigen (PSA) and Cancer Antigen 125 (CA125), an ovarian cancer-associated antigen. Based on our experiments, we see that the thin gold layer of the Au/Cr/Si samples, provides increased bio-material binding affinity, and the chromium layer has a similar, if not less, binding affinity compared to the silicon chip alone.
Experimental and Numerical Study of Evaporative Heat Transfer From Ten- Micro Microchannels
Authors: Lee Hoki , Quy T. A. , Richards C. D. , Bahr D. F. , Richards R. F.
Published: April 2008

Experimental and numerical results are presented for evaporative heat transfer from ten-micron square open-top channels. The radial channels are fabricated in epoxy photoresist on a two micron thick silicon membrane. The working fluid is pumped by capillary forces from a reservoir at the edge of the silicon membrane into the channels where it evaporates. The electrical power dissipated in a thin-film heater in the center of the membrane, the conduction heat transfer rate radially out of the membrane, and the rate of evaporation of the working fluid are measured. A three-dimensional finite difference, time-domain integration is used to predict sensible and latent heat transfer rates. Only 5-10% of the energy dissipated as heat in the thin film heater is carried away as latent heat by the evaporating working fluid. Computed temperatures and heat transfer rates are shown to match the experimental results.
Numerical Study of Natural Convection in a Partially Open Environment With a Heat Generating Source
Authors: Mariani Viviana Cocco , da Silva Adriano
Published: April 2008

A numerical study of the thermal and fluid dynamic behavior of air in a partially open two-dimensional enclosure is presented The enclosure has an opening on the right-hand vertical wall, which is kept at a low given temperature, while the opposite wall has a high given temperature. The natural convection in the enclosure is influenced simultaneously by the difference in temperature between the vertical walls, represented by the Rayleigh number (Rae) and by the internal heating source in the enclosure, represented by the Rayleigh number (Rai). The internal heat source is located on the lower horizontal wall, occupying three different positions. The numerical simulations were executed for 103 ≤ Rae ≤ 106 while the intensity of the two effects - the difference in temperature of the vertical walls and the internal heating source - was evaluated based on the relation R = Rai/Rae, which assumed the values of 400, 1000 and 2500. The results obtained in this study are compared with the results reported in the literature, showing a good congruence.
Linkage Between Learning Styles and Design Engineering Perceptions of Undergraduate Students
Authors: Manglik Raj M. , Jog Milind A. , Liu Yijun
Published: April 2008

The debate on inculcating effective design engineering learning - its fundamental conceptualization, application of theoretical constructs to model physical devices/systems, and development of tools for solving unstructured problems - and associated critical thinking has primarily focused on curricula issues. Little effort has been made to understand the cognitive underpinning of students that lends to success in this direction. This paper presents the findings of a transverse study to assess learning styles of undergraduate mechanical engineering students and their perceptions about design engineering. Survey results from a batch of sophomores and seniors are analyzed to ascertain: (i) aspects of learning styles that are conducive to design comprehension, and (ii) perceptions about design engineering that aid or impede such learning.
Constitutive Modeling of SMA in Constrained Recovery Mode
Authors: Daghia Federica , Viola Erasmo , Seigler Thomas M. , Inman Daniel J.
Published: April 2008

Shape memory alloys (SMA) can develop large stresses in the constrained recovery mode. Heating generates tension in the material, depending upon the cooling temperature some residual stress may remain after actuation. Brinson's one dimensional phenomenological model can be used to predict the stress/temperature loading paths in constrained recovery; however the model shows some discrepancies with experimental data when the SMA is cooled at low temperatures. This paper examines this behavior and proposes a modification to the Brinson model that better represents constrained recovery at low temperatures.
Heat Transfer and Fluid Dynamics Measurements in the Expansion Space of a Stirling Cycle Engine
Authors: Jiang Nan , Simon Terrence W.
Published: April 2008

The heater (or acceptor) of a Stirling engine, where most of the thermal energy is accepted into the engine by heat transfer, is the hottest part of the engine. Almost as hot is the adjacent expansion space of the engine. In the expansion space, the flow is oscillatory, impinging on a two-dimensional concavely-curved surface. Knowing the heat transfer on the inside surface of the engine head is critical to the engine design for efficiency and reliability. However, the flow in this region is not well understood and support is required to develop the CFD codes needed to design modern Stirling engines of high efficiency and power output. The present project is to experimentally investigate the flow and heat transfer in the heater head region. Flow fields and heat transfer coefficients are measured to characterize the oscillatory flow as well as to supply experimental validation for the CFD Stirling engine design codes. Presented also is a discussion of how these results might be used for heater head and acceptor region design calculations.
High-Sensitivity Mass Sensing Based on Enhanced Nonlinear Dynamics and Attractor Morphing Modes
Authors: Yin Shih-Hsun , Epureanu Bogdan I.
Published: April 2008

This paper demonstrates two novel methods for identifying small parametric variations in an experimental system based on the analysis of sensitivity vector fields (SVFs) and probability density functions (PDFs). The experimental system includes a smart sensing beam excited by a nonlinear feedback excitation through two PZT (lead zirconate titanate) patches symmetrically bonded on both sides at the root of the beam. The nonlinear feedback excitation requires the measurement of the dynamics (e.g. velocity of one point at the tip of the beam) and a nonlinear feedback loop, and is designed such that the beam vibrates in a chaotic regime. Changes in the state space attractor of the dynamics due to small parametric variations can be captured by SVFs which, in turn, are collected by applying point cloud averaging (PCA) to points distributed in the attractors for nominal and changed parameters. Also, the PDFs characterize statistically the distribution of points in the attractors. The differences between the PDFs of the attractors for different changed parameters and the baseline attractor can provide different attractor morphing modes for identifying variations in distinct parameters. The experimental results based on the proposed approaches show that very small amounts of added mass at different locations along the beam can be accurately identified.
FEA Thermal Stress Analysis of Concentrating Photovoltaic (CPV) Cell
Authors: Cao M. , Butler S. , Benoit J. T. , Jiang Y. , Radhakrishnan R. , Bendapudi S.
Published: April 2008

Steady-state and residual FEA thermal stress analysis of a Concentrating Photovoltaic (CPV) cell module is performed in this study. This investigation covers the nominal and extreme operating conditions, including system startup and shutdown. The physical properties of different epoxies were substituted into the model and the model results were used to identify the optimal bonding materials. Different thermal boundary conditions were evaluated for optimal performance. As the first step of module life prediction, residual stresses corresponding to different temperatures were calculated. The analysis revealed that the thermal expansion mismatch between the bonded materials is a major design concern, since it can cause structural failure at critical interface locations.
Rate-Controlled Constrained-Equilibrium Calculations of Ethanol-Oxygen Mixture
Authors: Janbozorgi Mohammad , Gao Yue , Metghalchi Hameed , Keck James C.
Published: April 2008

The Rate-Controlled Constrained-Equilibrium method (RCCE) is a powerful technique for simplifying the treatment of chemical reactions in complex systems. The method is based on the assumption that slow chemical reactions impose constraints on the allowed composition of such systems. Since the number of constraints can be very much smaller than the number of species, the number of rate equations to be integrated can be considerably reduced. In the present work, a kinetic scheme with 55 species and 366 reactions has been used to investigate stoichiometric Ethanol-oxygen mixture in a constant energy constant volume chamber. The state of the system was determined by three fixed elemental constraints: elemental carbon, elemental oxygen and elemental hydrogen and six variable constraints: moles of fuel, moles of fuel radicals, total number of moles, moles of free valence, moles of free oxygen, moles of OH+O+H. The 9 rate equations for the constraint potentials (LaGrange multipliers associated with the constraints) were integrated over a range of 1400 K-1700 K for initial temperature and 1atm-10atm for initial pressure. The RCCE calculations were in good agreement with detailed calculations and were faster than detailed calculations, which required integration of 55 species rate equations.
A Simple Finite Element Coupled Model for the Stress Analysis of Rotating Parts
Authors: Rencis Joseph J. , Immaneni Dinesh
Published: April 2008

A new coupled line finite element model is proposed that can be used to carry out a stress analysis of rotating parts. The rotating part consists of a disk modeled with axisymmetric line elements and blades modeled with axial line elements. An example is presented to demonstrate the accuracy of the proposed technique. The coupled finite element model is compared with a newly developed analytical solution and a solid finite element model.