bluuebunny/crossref_metadata_2025 huggingface dataset:
Directionally Independent Failure Prediction of End Mill Cutting Tools: An Investigation of Noise Reduction Using Higher Dimensional Real Fourier Analysis
Authors: Suprock Christopher A. , Roth John T.
Published: April 2008

Accurate on-line forecasting of a tool's condition during end-milling operations is advantageous to the functionality and reliability of automated industrial processes. The ability to disengage the tool prior to catastrophic failure reduces manufacturing costs, excessive machine deterioration, and personnel hazards. Rapid computational feedback describing the system's state is critical for realizing a practical failure forecasting model. To this end, spectral analysis by fast Fourier type algorithms allows a rapid computational response. The research described herein explores the development of nontraditional real FFT (Discrete Cosine Transform) based algorithms performed in unique higher-dimensional states of observed datasets. The developed Fourier algorithm is novel since it quantifies chaotic noise rather than relying on the more traditional observation of system energy. By increasing the vector dimensionality of the DCT, the respective linear transform basis will more effectively cross-correlate the transform data into fewer (more significant) transform coefficients. Thus, a single vector in orthogonally higher-dimensional space is observed instead of multiple orthogonal vectors in single-dimensional space. More specifically, a novel noise reduction technique is utilized to track trends measured from tri-axial force dynamometer signals. This transformation effectively achieves both system noise reduction and directional independence by observing the chaotic noise instead of system energy. Algorithm output trends from six end-milling life-tests are tracked from both linear and pocketing maneuvers in order to demonstrate the technique's capabilities. In all six tests, the algorithm predicts impending tool failure with sufficient time for tool removal.
A Multi-Purpose Temperature Control Method for MEMS Microheaters Without a Separate Temperature Sensor
Authors: Bae Byunghoon , Yeom Junghoon , Flachsbart Bruce R. , Tang Yanjun , Masel Richard I. , Shannon Mark A.
Published: April 2008

In this paper, a temperature-controlled method that does not use a separate temperature sensor is presented for different MEMS electrical resistance heaters. Instead of using a Resistance Temperature Detectors (RTD) sensor or micro-thermocouple for closed-loop control of the temperature, which will have a finite distance between the heater and sensor and a response delay due to the thermal mass of the substrate on which the sensor resides, we use the change in resistance with temperature of the electrical heating element itself for the control input.
An Approach for Improving Design of System Variants
Authors: Lakshminarayana Ramaprasad E. , Takai Shun
Published: April 2008

In the past decades, firms have increased automated assembly operation to improve productivity and reduce human errors; however, manual assembling is still a necessary operation for complex and large-scaled systems that require high reliability. Furthermore, since customers demand more variety in systems, firms increasingly assemble variants of a system in a single assembly line. In this mixed model assembling operation, there are higher chances of assembly errors due to interchanging of geometrically similar parts between system variants. Design for Assembly (DFA) is a design guideline that assists engineers to design systems that are easier to assemble; however, DFA does not provide any guideline for simultaneously designing variants of system being assembled in mixed model operation. Furthermore, incentive schemes for assembly operators that may influence both assembly productivity and errors have not been the scope of DFA research. In this research, the authors conducted assembling experiments with students to investigate how non-geometric part information and incentive schemes affect the assembly productivity and quality in mixed model assembling operation.
A New Approach for Control of Linear Periodically Time Varying Systems
Authors: Kalender S. , Flashner H.
Published: April 2008

This paper proposes a new design approach for periodically time-varying systems. The approach is based on the application of point-mapping technique to obtain an equivalent linear time invariant sampled data system for the linear periodically time varying system with parameterized control vector, thus allowing the known control design techniques for sampled data systems to be applied. An extension of the approach for analysis of robustness of the control design with respect to parametric uncertainties is also presented. The extension is based on retaining linear as well as higher order terms in the uncertain parameters in the point-mapping algorithm. To illustrate the approach, stabilization of the trivial equilibrium point for a mathematical model representing the dynamics for a double inverted pendulum with periodic forcing is considered. The effectiveness of the extension of the approach for robust stability analysis is demonstrated also by considering uncertain periodic forcing parameters for the double inverted pendulum example.
SiO2-Coated Porous Anodic Alumina Membrane for Electroosmotic Pumping
Authors: Vajandar Saumitra K , Xu Dongyan , Li Deyu , Markov Dmitry , Wikswo John , Hofmeister William
Published: April 2008

Electroosmotic pumping has been extensively used in biomedical lab-on-a-chip devices and micropumps for critical applications such as microelectronic cooling. In many applications, a high flow rate is a key requirement in desired performance so constant efforts have been made to increase the pumping flow rate through unit area to achieve the compact design. We report here an attempt of using SiO2-coated anodic porous alumina membrane as the material to achieve high electroosmotic pumping flow rate. High quality porous alumina membranes of controllable pore diameter in the range of 20-300 nm and pore length of 60 - 100 μm have been fabricated with electrochemical anodization. The pores are uniform and hexagonally packed with a high porosity of up to 50% and a tortuosity of a bare minimum of unity. In addition, the inner surface of the pores could be conformally coated with a thin layer (~ 5 nm) of SiO2 with sol-gel chemistry to achieve a high zeta potential. Scanning electron microscopy of the cross section of the membrane verified these facts. Electroosmotic pumping performance of these membranes has been investigated using standard relevant aqueous electrolyte buffer solutions and results showed that SiO2-coated porous alumina could achieve a higher flow rate compared with other microporous materials such as glass frit and porous silicon reported in the literature.
Selecting System Concept by Minimizing Cost of Part Requirement Tolerances
Authors: Takai Shun
Published: April 2008

At the end of a conceptual design phase, engineers choose a single (or a small set of) system concept from a large number of concept variants. In most cases, there is not enough design information to quantitatively evaluate how a final system developed from each concept would perform and cost. Thus engineers need to first perceptually evaluate and select a concept, and then design a system. On the other hand, if engineers know analytical relationships between system and part requirements, they can specify target values of part requirements such that a system achieves its target requirements. Furthermore, if engineers know how much it will cost to control part requirements within tolerances, they can minimize the cost of a system by optimizing tolerances of part requirements. This paper proposes and illustrates an approach to select a system concept when engineers know the relationship between system and part requirements, and how much it will cost to control part requirements within tolerances. Engineers choose a concept that minimizes cost.
Energy-Based Control of a Pneumatic Oscillator With Application to Energy Efficient Hopping Robots
Authors: Zhu Yong , Barth Eric J.
Published: April 2008

This paper presents an energetically derived control methodology to specify and regulate the frequency and amplitude of oscillatory motion of a pneumatic actuation system. A lossless horizontal pneumatic actuation system with an inertia is energetically shown to represent an oscillator with a stiffness, and hence frequency, related to the equilibrium pressures in the actuator. Following from an analysis of the conservative energy storage elements in the system, a control methodology is derived to sustain a specified frequency and amplitude of oscillation in the presence of energy dissipation. The control strategy takes advantage of the natural passive dynamics of the system to provide much of the required actuation forces, while the remaining forces needed to overcome the energy dissipation present in a non-ideal system with losses are provided by a nonlinear control law for the charging and discharging of the actuator. This control methodology is demonstrated experimentally to provide accurate and repeatable frequency and amplitude control of oscillation in the presence of dissipative forces. Finally, the energetic analysis of the horizontal pneumatic system is extended to the vertical case where gravity is present. This extension provides an energetically efficient hopping control methodology for pneumatically actuated robots.
Thermomechanical Characterization and Modeling of Ni60Ti40 SMA for Actuated Chevrons
Authors: Hartl Darren , Volk Brent , Lagoudas Dimitris C. , Calkins Frederick , Mabe James
Published: April 2008

This work describes the thermomechanical characterization and preliminary FEA modeling of commercial jet engine chevrons incorporating active Shape Memory Alloy (SMA) beam components. The SMA beams, when activated, induce the necessary bending forces on the chevron structure to deflect it into the fan flow and reduce noise. The primary focus of this work is the characterization of the SMA material (Ni60Ti40 wt%) chosen to actuate these chevrons and the preliminary modeling of the active chevron system behavior. To fully understand the material and calibrate the model, various thermomechanical experiments are performed on both untrained and trained standard SMA tensile specimens. Material properties for the shape memory alloy components are derived from this tensile experimentation. By using this data, a 3-D FEA implementation of a phenomenological SMA model is calibrated and used to analyze the response of a system motivated by the active chevron. The problem modeled consists of a pre-curved SMA beam clamped firmly against a straight aluminum substrate. The model proves to be an accurate tool for predicting the mechanical response of such a system subject to defined thermal inputs.
A New Multidimensional Graph for the Einstein Refrigeration Cycle
Authors: Lara V. Araceli , Sandoval C. David , Morales G. Juan , Lo´pez C. Raymundo , Lizardi R. Arturo , Terres P. Hilario
Published: April 2008

An analysis of the exergy use in an Einstein refrigeration cycle is presented. The analysis is performed through the use of a new graphical multidimensional representation of the cycle. The Einstein refrigeration cycle works with ammonia, butane and water. These compounds are present in the cycle as several ammonia-water and ammonia-butane mixtures that have different compositions. In essence, the cycle transfers ammonia from an ammonia-water mixture to an ammoniabutane mixture in a series of processes and then it transfers ammonia back again to an ammonia-water mixture in another series of processes. The ammonia transfers involve heat absorptions and heat rejections that have as an effect the transfer of heat from a low temperature reservoir to a high temperature reservoir. The aforementioned multidimensional graph was built with equilibrium data of the ammonia-water and ammonia-butane binary systems for a 4 bar pressure and a 240 K to 350 K temperature range. The graphical representation is multidimensional because it shows in one graph values of concentration, temperature, enthalpy, entropy and exergy for ammonia-water mixtures and ammonia-butane mixtures. The thermodynamic states of all the process currents present in the cycle are showed in the graph, as well as are the different thermodynamic processes of the cycle. The exergy destruction rate of each device is clearly represented. The usefulness of this graph is similar to that of the T-s graph for a Rankine cycle.
Modeling Boundary Conditions and Thermocouple Response in a Thermal Experiment
Authors: Romero Vicente J. , Shelton Joe W. , Sherman Martin P.
Published: April 2008

A series of experiments have been conducted in an effort to support the experimental characterization and modeling of a thermally decomposing foam. The hardware consists of a stainless steel cylinder (slug) embedded in a removable epoxy foam (REF). The slug/foam assembly is pressed into a 20-mil thick 3.5-inch diameter by 3.25-inch tall stainless steel can. In the particular experiment considered in this paper, the can was heated from the top by a bank of quartz heating lamps. In modeling the experiment, several non-trivial difficulties were encountered associated with characterization and modeling of the experimental heating conditions. In the paper we share some thought processes and describe the iterative modeling approach required to model the experiment. Novel features of the effort include modeling of embedded thermocouples in our finite-element model of the test unit, and inverse analysis to solve for the magnitude of incident heat flux from the quartz lamps.
Effect of Electrical Double Layer on Electrical Conductivity and Pressure Drop in Pressure-Driven Micro-Channel Flow
Authors: Lin Bochuan , Ban Heng
Published: April 2008

The effect of electrical double layer (EDL) on micro-channel flow has been studied widely. Most research focused on flows with typical channel width or pipe diameter much greater than the thickness of EDL (Debye length). In such cases, the influence of EDL on the overall electrical conductivity is small, and a constant bulk electrical conductivity is often used in calculations. In our study of pressure-driven micropipette injection flow, the pipe size is on the same order of magnitude as the Debye length. To elucidate the effect of overlapping EDL the flow inside a micro-channel was analyzed. The governing equations for the flow, the Poisson equation for the electric potential, and the charge continuity equation for the net charge were solved analytically. The effect of overlapping EDL on the electrical conductivity and velocity distribution in the micro-channel and the pressure drop were quantified. The results showed that, the average conductivity of electrolyte solution inside the channel increased significantly, dependent on the channel width. With the modified mean electrical conductivity, the pressure drop for the pressure-driven flow was smaller than that without considering the influence of EDL on conductivity.
Effects of Ion-Water Potentials in Molecular Dynamics Simulation of Ion Distribution in Nanochannels
Authors: Xu Dongyan , Li Deyu , Leng Yongsheng , Chen Yunfei
Published: April 2008

Understanding ion and fluid transport through highly confined nanochannels is important for the study of many interesting phenomena in nature and for the design of novel nanofluidic devices. Molecular dynamics has been proved to be a powerful tool to investigate the transport of ion and fluid in nanochannels, however, the results of molecular dynamics simulation depend on the selection of intermolecular potentials in the simulation. In this work, we applied two different ionwater interaction potentials to study their effects in the molecular dynamics simulation of ion distribution in the nanochannels between two parallel charged surfaces. Water was simulated with the TIP4P and SPC/E models and the electrostatic interaction between ions, water molecules, and surface charges was modeled by using Ewald summation algorithm with the slab correction. Two different interaction potentials between the ion and water molecules, one based on simple Lennard-Jones potential and the other based on the Bounds' ion-water potential, were adopted to explore the effects of ion-water interactions on the ion distribution in nanochannels. The Bounds' model takes into account the interactions between ions and both oxygen and hydrogen atoms in the water molecules. Ion concentration profiles in nanochannels with these two different potentials were calculated and results showed that the ion-water interaction potential could significantly affect the ion distribution in nanochannels. We expect that the ion-water potential could also have important effect on modeling of electroosmotic flow through nanochannels.
A Practical Solid-Propellant Micro-Thruster
Authors: Parra E. A. , Pister K. S. J. , Fernandez-Pello C.
Published: April 2008

Miniaturization of solid-propellant thrusters is an area of active research that has been motivated by the reduction in size of aerospace systems and the advancement of micromachining techniques. Though this micro-propulsion problem seems simplistic compared to the macro-scale counterpart, an efficient and reliable device has yet to be produced. A millimeter-scale novel composite solid-propellant thruster design that builds on pervious work [1] and increases efficiency is here presented. Current designs made primarily out of silicon suffer from high thermal losses and, in extreme cases, flame quenching due to the augmented surface area to volume ratio associated with miniaturization. Moreover, the reduced device dimensions drive the combustion reaction to complete outside of the thruster, misemploying the majority of the chemical energy. This occurs because the propellant mixing and chemical time do not scale with size, while the residence time does decrease as the size of the thruster decreases [2]. A novel thruster design that increases the propellant residence time is being characterized using ammonium perchlorate/binder composite propellant. The thruster geometry recycles thermal energy to the unburned propellant grain increasing its temperature and, therefore, burning rate and combustion efficiency. In addition, propellant formulation has been optimized for the thruster minimization.
A Component-Based Parametric Reduced-Order Modeling Technique and Its Application to Probabilistic Vibration Analysis and Design Optimization
Authors: Park Keychun , Zhang Geng , Castanier Matthew P. , Pierre Christophe
Published: April 2008

In this paper, a component-based parametric reduced-order modeling (PROM) technique for vibration analysis of complex structures is presented, and applications to both structural design optimization and uncertainty analysis are shown. In structural design optimization, design parameters are allowed to vary in the feasible design space. In probabilistic analysis, selected model parameters are assumed to have predefined probability distributions. For both cases, each realization corresponding to a specific set of parameter values could be evaluated accurately based on the exact modes for the system with those parametric values. However, as the number of realizations increases, this approach becomes prohibitively expensive, especially for largescale finite element models. Recently, a PROM method that employs a fixed projection basis was introduced to avoid the eigenanalysis for each variation while retaining good accuracy. The fixed basis is comprised of a combination of selected mode sets of the full model calculated at only a few sampling points in the parameter space. However, the preparation for the basis may still be cumbersome, and the simulation cost and the model size increase rapidly as the number of parameters increases. In this work, a component-based approach is taken to improve the efficiency and effectiveness of the PROM technique. In particular, a component mode synthesis method is employed so that the parameter changes are captured at the substructure level and the analysis procedure is accelerated. Numerical results are presented for two example problems, a design optimization of a pickup truck and a probabilistic analysis of a simple L-shaped plate. It is shown that the new component-based approach significantly improves the efficiency of the PROM technique.
Spot Cooling of Local-High Heat Load by High-Velocity Thin Liquid Flow
Authors: Ohtake Hiroyasu , Koizumi Yasuo , Nemoto Ken , Sakurai Hisashi
Published: April 2008

Spot cooling of local-high heat load by high-velocity thin liquid flow was examined experimentally. Steady state experiments were conducted using a copper thin-film and rectangular sub-millimeter-channels. The width of the test channel was 2 mm. The heights of the test channel were 0.5 and 0.2 mm. The width and length of a test heater was 2 mm and 2 mm, respectively. The test liquid was degassed pure water. The liquid velocities were 1.5, 5, 10 and 15 m/s. The liquid subcooling was 20 K. Location of the heater in the test channel also was an experimental parameter: the positions of the heater from the exit of the test channel were 30 mm (middle) and 0 mm (exit). Experimental results showed that the maximum heat flux (CHF or cooling limit) during experiment with the heater at exit of the test channel was similar to that with the heater at middle of the test channel: the maximum heat flux was independent of the position of heater in the test channel. The maximum heat flux occurred when bubbles coalesced together or a dry patch appeared on the heater. The coalescence bubble covered over the heater was observed at CHF in condition of low liquid velocity. For condition of high liquid velocity, a dry patch appeared on the heater, and then the dry region extended over the heater to come around the CHF. The maximum heat flux (critical heat flux) was about 8 MW/m2 in a range of present experiments. The CHF for the present sub-millimeter channel was similar to that for conventional channel. Furthermore, models were proposed using heat transfer around a coalesced bubble and at a dry patch on a heater.
Computational Studies of Gain Modification by Serotonin in Pyramidal Neurons of Prefrontal Coxtex
Authors: Li Guoshi , Cline Harvey C. , Blier Pierre , Nair Satish
Published: April 2008

Serotonin (5-HT) is widely implicated in brain functions and diseases, but the cellular mechanisms underlying 5-HT functions in the brain are not well understood (Zhang and Arsenault, 2005). Recent experiments (Zhang and Arsenault, 2005) have shown that 5-HT substantially increased the slope (gain) of the firing rate current (F-I) curve in layer 5 pyramidal neurons of the rat prefrontal cortex and this effect was limited to the range of firing rate (0-10 Hz) that is known to behaviourally relevant. Furthermore, it was found that 5-HT mediated gain increase was due to a reduction of the afterhyperpolarization (AHP) and an induction of the slow afterdepolarization (ADP), regardless of changes in the membrane potential, the input resistance or the properties of action potentials. To investigate this frequency-dependent gain modulation of 5-HT on the prefrontal cortex neurons, conductance-based Hodgkin-Huxley type models of the regular spiking (RS) cells in the prefrontal cortex are developed using a step by step approach. We first show that a model with an A current displays a square-root form F-I curve with higher slope at low frequency. However, for the same range of current injection steps used in experiment, the frequency range goes beyond 20 Hz, suggesting the presence of other hyperpolarizing currents in the model. As suggested by the experiment (Zhang and Arsenault, 2005), AHP currents (fast AHP, medium AHP and slow AHP) are included in the model to simulate 5-HT effect. Simulations show that AHP currents effectively linearize the F-I curve and decrease the slope of F-I curve in general, thus reducing the neuronal excitability. Since the slow AHP current is a target of 5-HT, the strength of this current is reduced gradually and the F-I curves are plotted together for comparison. The results indicate that with decreasing slow AHP strength, the current thresholds for repetitive spiking decreases and the slopes of the F-I curves increase in general. A square-root form F-I curve is not evident until the slow AHP current is blocked completely. This suggests that the medium AHP current also play a role in linearizing the F-I curve besides the slow AHP current. Based on current findings, a full model with both A current and AHP currents is being constructed to match the experimental data more closely so the mechanism of 5-HT on gain modulation of prefrontal cortical neurons can be better understood.
Flexible Labview Based Experimental Modules for Teaching Engineering Fundamentals
Authors: Abou-Hanna Jeries , Abuzaid Wael , Fakheri Ahmad , Okamura Kiyohisa
Published: April 2008

A set of experimental education modules were developed as tools to be used in instrumentation and other engineering courses. These modules consist of National Instruments data acquisition system, sensors modules and Labview based software for controlling the experiments and acquiring data. The mechanical system, the focus of the experiment, consisted of a structure that is best described as a cantilevered beam, with strain gages to acquire strain signal, LVDT for acquiring deflection, and an eccentric motor to generate excitation of the free end of the beam. The experimental modules were developed with several objectives in mind, but they all use the same mechanical system to study different aspects. One was to have students use ready made Labview programs that acquire, store and display the data, like displacement and strain under either dynamic or static loading. The students would use the data to compare with theoretical bases. Other modules contain more complex requirements such as the students modifying the Labview programs to display and store the data in different formats and post process some of the output through additional programming in order to learn more about Labview programming. In a course like vibration or system dynamics, the students would utilize the same module to extract the damping characteristics of the structure, natural frequencies and steady state vibration characteristics. This educational module is an effective tool to teach instrumentation, programming and to provide data to support theoretical engineering concepts.
Parametric Studies of Constriction Resistance Effects Upon Solid Oxide Cell Transport Phenomena
Authors: Nelson George , Haynes Comas
Published: April 2008

The competition between mass transfer and electronic resistance effects arising from solid oxide cell interconnect geometry has been initially explored through parametric studies based on a design of experiments (DOE) approach. These studies have demonstrated the advantages of smaller interconnect-fuel stream total width and the increased dominance of mass transport as a limiting factor at low fuel stream hydrogen compositions. In addition to the direct effects of solid oxide fuel cell (SOFC) interconnect geometry on mass and electronic transport phenomena, the compounded effects of fuel stream concentration and cell current loading are considered. Finally, the parametric studies conducted for SOFC operation have been applied to the operation of solid oxide electrolysis cells (SOECs). These additional studies have demonstrated that interconnect designs that benefit SOFC performance are mutually beneficial for SOEC performance.
Constitutive Gradients and Pore Tolerance in Two Weldments
Authors: Boyce B. L. , Robino C. V. , Reu P. L.
Published: April 2008

The mechanical constitutive behavior of welded components is difficult to characterize at any size scale, but particularly challenging in the case of sub-millimeter welds such as produced by laser welding. Recently emerging digital image correlation (DIC) techniques provide a means for extracting local constitutive response. The tensile stress-strain response of laser welded austenitic 304L is evaluated in the present study. Weld fusion zones were found to have slightly higher yield strengths than the corresponding basemetal, and retained significant ductility (~45%). In this ductile, flaw tolerant stainless steel, the local weld ductility was essentially unaffected by the presence of weld-root porosity which was induced only by pulsed laser welding. In contrast, in a parallel study on the local constitutive properties of a welded Ni-Gd-Mo-Gd alloy with much less macroscopic ductility, the presence of weld root porosity was found to localize strain only in the vicinity of the largest pores, causing premature failure at low macroscopic strains.
Nickel-Titanium Shape Memory Alloy Motors and Electromechanical Devices
Authors: James Erik , Grant Jamil , Alberter Michael , Dasque Nastassja , Price Cynthia , Craft William J.
Published: April 2008

Shape memory alloys (SMA) have been an extensively used material for actuators in micro-electromechanical systems (MEMS) because actuation force and displacement are greatest in SMA amongst many actuator materials [1]. Of the alloys currently available for SMA actuators, the most popular system is Nitinol (or NiTi) due to its good oxidation resistance, reversible martensitic transformation, broad range of transformation temperatures (from -100 - 100 °C), and specific power density [2]. Current commercially available SMA wire has easily achieved no-load strain of 5% with medium gage SMA wires demonstrating an axial force capacity of 2 Newtons or more. While the potential use of SMA materials in a thermal-electric motor has been documented beginning in the 1980's, there are a number of new allows and fatigue-resistant materials that may lead to more general designs with a wide range of motions and applications. Shape memory alloys are a special type of material that exhibit two unique properties, pseudo-elasticity and shape memory effect (SME). SMA undergoes SME because of martensitic or diffusionless transformation where each atom has a slight displacement, creating observable changes throughout the structure as the allow changes states. This alloy has the ability, once heated, to return to its parent austenite phase where it exists at higher symmetry. Upon cooling, the material returns to one of many lower symmetry martensitic phases. This thermal cycle is shown in Figure 1. [3,4]. It is even possible for many variants of martensite to be present in the same material. Pseudo-elasticity is a rubber-like flexibility that allows the SMA to be contorted for a variety of purposes. Once contorted, the application of heat will cause the alloy to undergo martensitic transformation. Upon completion of the cycle, the alloy will have returned to its original shape. The development of SMA-based electromechanical devices delivers traditional mechanical motion with non-traditional methods. Rather than electromagnetic components rotating about a central axis to produce power, the rotary SMA motor utilizes contracting elements, and mush as spark ignition rotary engine, it can be designed to produce angular motion. Motion is accomplished with sequenced electrical signals sent across each element mounted between an eccentric crank. Rotary motion is produced during the power portion of the cycle for specific SMA elements under the application of an electrical signal. Based on this concept, our team developed a demonstration model with four active elements. We have demonstrated rotary motion of the device for an extended period of time, and we believe that macro-scale models can reduce the concept substantially and perhaps to the MEMS level.
A Novel Approach to the Teaching of Etropy Based on a Recent Single Particle Heat Engine Model
Authors: Dartnall W. John , Reizes John
Published: April 2008

In a recently developed simple particle mechanics model in which a single particle represents the working fluid (gas) in a heat engine (exemplified by a piston engine) a new approach was outlined for the teaching of concepts to thermodynamic students. By mechanics reasoning a model was developed that demonstrates the connection between the Carnot efficiency limitation of heat engines and the Kelvin-Planck statement of Second Law requiring only the truth of the Clausius statement. In this paper the model is extended to introduce entropy. Here the particle's entropy is defined as a function of its kinetic energy and the space that it occupies that is analogous to that normally found in classical macroscopic analyses.
Dynamic Model of a Plug in Hybrid Electric Vehicle
Authors: Ghorbani Reza , Bibeau Eric , Zanetel Paul , Karlis Athanassios D.
Published: April 2008

Renewable biofuels like biodiesel and bioethanol contribute only a small percentage of the overall energy mix for mobility. Electricity use for transportation has limited applications because of battery storage range issues. Recently, the trend of research leads in hybrid technologies with significant increase in vehicle efficiencies that created the Plug-in Hybrid Electrical Vehicles (PHEV) platform. A comprehensive alternative energy vehicle simulator is presently seen as an important contribution to the transportation issue, both in terms of contributing data to help policy to reduce fossil fuel use and to support research in this important area. The Renewable Energy Vehicle Simulator (REVS) allows analysing different vehicle configurations, control strategies and renewable and non-renewable fuel and electricity sources. The goal is to determine the optimal combination of fuels and grid electricity use and perform greenhouse gas calculations based on emerging protocols being developed, optimizing the efficient and proper use of renewable energy sources in a carbon constrained world. The simulation platform for REVS models the fundamental aspects of PHEV components, i.e. process control, heat transfer, chemical reactions, thermodynamics and fluid properties. In this work IDEAS simulates the internal combustion engine and chemical reactions to provide emissions out of engine. Matlab and Simulink is employed to simulate the dynamics of the vehicle.
Application of Zone Models for Under-Ventilated Compartment Fires
Authors: Mizukami T. , Utiskul Y. , Quintiere J. G.
Published: April 2008

A model is presented that explains the mass loss rate in a compartment as a function of fuel type and scale. The effect of ventilation is included in the model by the inclusion of the ambient oxygen concentration in the lower layer that results due to vent mixing. The model is executed in BRI2002, a zone model, capable of computing species and thermal conditions in the upper and lower compartment gas layers. Computations show good agreement with small-scale compartment data for heptane pools. The results can accurately portray extinction, oscillations in burning, reduction in the flaming area, and quasi-steady behaviors.
Design and Verification of a Low-Powered Pre-Programmable In-Package Temperature Controller
Authors: Kim Hyeun-Su , Liao Hsien-Hsin , Lee Byeong-hee , Kenny Thomas W.
Published: April 2008

A zero power passive temperature regulator has been studied and designed to maintain electric chip operating temperature using a variable thermal resistor. Apart from the passive temperature regulator design, we also present active variable thermal resistors using electrostatic force to actuate the device. Test samples were fabricated to verify these two designs and we observed the temperature change of a heated chip due to thermal resistance changes. This study estimated and measured the thermal contact resistance and the force required to remove it.
Van der Waals and Capillary Adhesion of Microelectromechanical Systems
Authors: DelRio Frank W. , de Boer Maarten P. , Phinney Leslie M. , Bourdon Chris J. , Dunn Martin L.
Published: April 2008

Interfacial adhesion is an important factor in determining the performance and reliability of microelectromechanical systems (MEMS). Van der Waals dispersion forces are the dominant adhesion mechanism in the low relative humidity (RH) regime. At small roughness values, adhesion is mainly due to van der Waals dispersion forces acting across extensive non-contacting areas and is related to 1/Dave2, where Dave is the average surface separation. These contributions must be considered due to the close proximity of the surfaces, which is a result of the planar deposition technology. At large roughness values, van der Waals forces at contacting asperities become the dominating contributor to the adhesion. Capillary condensation of water has a significant effect on rough surface adhesion in the moderate to high RH regime. Above a threshold RH, which is a function of the surface roughness, the adhesion jumps due to meniscus formation at the interface and increases rapidly towards the upper limit of Γ=2 γcos θ=144 mJ/m2, where γ is the liquid surface energy and θ is the contact angle.
Numerical Modeling of EM Pump Efficiency
Authors: Cook Daniel P. , Chen Yitung , Ratliff Lillian J. , Chen Huajun , Ma Jian
Published: April 2008

The pilot Molten lead-bismuth target circuit (TC-1) in University of Nevada, Las Vegas (UNLV) was designed for beam power of 1 MW accelerator driven system (ADS). The TC-1 is a liquid lead-bismuth eutectic (LBE) circulation loop. Circulation of the liquid alloy is driven by an annular linear induction pump (ALIP). Experimental measurements of system parameters have yielded a surprisingly low pump efficiency of less than 1%. A numerical study of the pump efficiency has been conducted to determine which operational parameters are responsible for this low efficiency and to give insight into future EM pump design. The numerical study has entailed incorporating algorithms which calculated the EM body force into a commercial CFD code (FEMLab). The EM body forces were calculated using both simplified analytic expressions, as well as by numerical solution of Maxwell's equations.
In-Chip Device-Layer Thermal Isolation of MEMS Resonator for Lower Power Budget
Authors: Jha Chandra M. , Hopcroft Matthew A. , Agarwal Manu , Chandorkar Saurabh A. , Candler Rob N. , Subramaniun Vijay , Melamud Renata , Bhat Suhrid , Kim Bongsang , Park Kwan K. , Kenny Thomas W.
Published: April 2008

This paper presents a thermally isolated ovenized design of MEMS resonator. Ovenization (joule heating) is done to compensate for the temperature dependence of resonator frequency. An ovenized resonator has a stable frequency over a wide temperature range of -40°C to 85°C. However, the ovenized designs lead to power consumption because of joule heating. It is therefore necessary to thermally isolate the device in order to reduce the power consumption. In this paper, we demonstrate an in-chip thermal isolation and heat delivery within the device layer of the silicon resonator that reduces the power requirement without compromising on the overall performance of the device. A power consumption of 12mW for an ovenized MEMS resonator, built within a wafer-scale encapsulation process, is reported here.
Vehicle Dynamic Simulation for Reconstruction of Rollover Crashes
Authors: Sayed Riaz A. , Delaigue Pierre , Eskandarian Azim , Digges Kennerely
Published: April 2008

Vehicle rollover crashes are the most severe in terms of occupant's fatalities and injuries. On average rollover crashes are responsible for more then 10,000 fatalities annually. Vehicle rollover is a very complex phenomenon. Simple static analysis and evidence analysis may not be sufficient to provide insight on the vehicle dynamic behavior during the pre-roll phase i.e. from the point of initiation of the crash to the beginning of the first airborne phase. 3D computer simulation provides one of the most comprehensive tools in accident analysis and reconstruction. The main objective of this research was to obtain accurate vehicle pre roll dynamics data in real life rollover crashes using commercially available vehicle dynamics and simulation programs.
A New Constitutive Modeling and Control Paradigm for Piezoelectrically-Actuated Nanostagers
Authors: Bashash Saeid , Jalili Nader
Published: April 2008

Over the decades, ultra-fine positioning through piezoelectric actuators has demonstrated limited performance due to the existence of complex, multi-path hysteresis nonlinearity in response to an applied input voltage. However, the complete underlying memory-dominant nature of hysteresis in piezoelectric materials has been recently disclosed. In this paper, the memory-based hysteresis properties are introduced and described in detail as a set of constitutive rules. Utilizing a mathematical mapping technique, a modeling and control framework is then developed for the precise representation and compensation of hysteresis nonlinearity. The model is experimentally validated for a piezoelectrically-driven nanostager equipped with sub-nanometer resolution capacitive position sensor. To investigate the performance of the model in the event of memory saturation, two strategies namely; "open" and "closed" memory-allocation structures are introduced. It is shown that the closed memory-allocation structure demonstrates an improved performance over the open structure. Using the inverse of the hysteresis model, a feedforward inverse model-based controller is then developed and successfully implemented on a 3-dimensional nanostager for surface topography tracking, typically encountered in scanning probe microscopy applications.
Numerical Analysis on Deployment Behaviors of Membrane Structure Systems
Authors: Hashimoto M. , Kishimoto N. , Miyazaki Y. , Natori M. C.
Published: April 2008

This paper shows numerical analysis on dynamic deployment behaviors of membrane structure models embedding inflatable tubes. To treat their nonlinearity, one kind of nonlinear elasto-dynamic analysis methods characterized by modified stiffness matrix is applied. Analyzed models were proposed for future membrane structure systems inspired by insects' metamorphoses. In this paper, we focus on a balance between two kinds of deployment forces: centrifugal forces due to rotation of a central satellite and extension forces due to inflation of embedded tubes. We present numerical results of deployment behaviors of rectangular and hexagonal membrane models. Details of the numerical method are also discussed. Numerical results of the rectangular membrane model provide that there exist minimum values of maximum strain energy of membrane elements at appropriate gas filling time for each rotation rate. This means that we could control deployment behaviors by regulation of inflation rate of embedded tubes and rotation rate of a central satellite bus. Numerical results of the hexagonal membrane model provide that the case of deployment with gas injection shows more smooth deployment behavior without local deformation. In the case of deployment without gas injection there appears to be local deformation with high strain energy density.
Modeling and Observer-Based Robust Tracking Control of a Nano/Micro-Manipulator for Nanofiber Grasping Applications
Authors: Saeidpourazar Reza , Jalili Nader
Published: April 2008

This paper presents the modeling and control of a nano/micro-manipulator for use in nano-fiber grasping and nano-fabric production. The RRP (Revolute-Revolute-Prismatic) manipulator considered here utilizes two rotational motors with 10-7 rad resolution and one linear Nanomotor® with 0.25nm resolution. Weighing just 30g and having short lever arms (<5cm), the manipulator is capable of achieving well-behaved kinematic characteristics without backlash and with atomic scale precision to guarantee accurate manipulation at nanoscale. A mathematical model of the micromanipulator is formulated and both direct and inverse kinematics of the system as well as dynamic equations are presented. Several controllers for manipulator positioning tracking are derived and analyzed extensively. Unlike typical macroscale manipulator models and controllers, the controller development is not trivial due to nanoscale movement and forces, coupled with unmodeled dynamics and nonlinear structural dynamics. Following the development of the controllers, numerical simulations of the proposed controllers on the manipulator are used to verify the tracking performance.
Hydrogen Environment Embrittlement of Steels and Alloys In 70 MPa Hydrogen at Room Temperature
Authors: Fukuyama Seiji , Imade Masaaki , Yokogawa Kiyoshi
Published: April 2008

Hydrogen environment embrittlement (HEE) of steels and alloys to be used in high-pressure hydrogen storage for fuel cell vehicles was investigated in 70 MPa hydrogen at room temperature. Candidate materials for high-pressure hydrogen storage, namely, stainless steels (i.e., SUS304; in the Japanese Industrial Standard (JIS), SUS316, SUS316L, SUS316LN, SUS310S, SUS630(17-4PH)), a low-alloy steel (SCM440), carbon steels (SUY, S15C, S35C, S55C and S80C), an iron-based superalloy (SUH660(A286)), Ni-based superalloys (Incoloy 800H, Inconel 718, Inconel 750, Hastelloy B2, Hastelloy C22), a copper-zinc alloy (C3771) and an aluminum alloy (A6061), were tested. SWP (piano wire), and SUS304, SUS316 and SUS631(17-7PH) wires used for springs were also tested. Tensile tests were conducted at room temperature using specially designed apparatus developed by our laboratory to measure the actual load on a specimen with an external load cell irrespective of the axial load caused by the high pressure and friction at sliding seals. In materials that contain Ni, i.e., stainless steels, and iron-based and Ni-based superalloys, HEE shows a variable Ni content dependence. We found that the effect of Ni equivalent on HEE of these materials shows a stronger dependence. HEE decreases with increasing Ni equivalent with grain boundary fracture or transgranular fracture along a martensite lath assisted by hydrogen for SUS630, SUS304, SUS316, SUS316LN and SUS316L. No HEE is observed in the given Ni equivalent range with dimple fracture for SUH660, SUS310S and Incoloy 800H; however, HEE increases with increasing Ni equivalent with transgranular fracture along a slip plane, that is along the interface between austenite and gamma', and with grain boundary fracture assisted by hydrogen for Inconel 718, Inconel 750, Hastelloy C22 and Hastelloy B2. These results and other HEE test results in high-pressure hydrogen obtained by AIST, i.e., results for 18 Ni maraging steel, low-alloy steels, high-Cr steels, Ni-based superalloys; are summarized in the AIST HEE data, which is compatible with NASA HEE data. HEE of the materials in high-pressure hydrogen is discussed. Internal reversible hydrogen embrittlement (IRHE) of some thermally hydrogen-charged austenitic stainless steels is also discussed in comparison with HEE of the steels.
Strain Measurement of Microsamples Using Laser Interferometry
Authors: Jin Helena (Huiqing) , Lu Wei-Yang
Published: April 2008

As the specimen gets smaller and thinner, traditional strain measurement method using the strain gage is impossible. In this paper, the strain is measured using non-contact laser interferometry method. Two markers are placed on the LIGA specimens along the loading direction to reflect the laser beams to generate the interferometric fringe patterns. The markers are generated using micro-hardness indentation for the LIGA specimens. A pair of CCD cameras is used to capture the interferometric fringes during each step of the loading along the longitudinal direction. Fast Fourier Transform (FFT) is then applied to calculate the frequency and phase shift of the fringes. The displacement and strain can be obtained from the phase shift of the fringe pattern. This ISDG strain measurement technique is further developed by using multi markers to obtain fringes during the whole loading when the specimen undergoes larger motion. Biaxial strain measurement using ISDG is also developed to obtain both Young's modulus and Poisson's ratio simultaneously. A third marker is located orthogonal to the first pair of markers along the loading direction. Two pairs of CCD cameras are used to acquire the digital images of the interferometric fringes patterns along both longitudinal and transverse directions. The stress-strain curves as well as the material properties are very consistent from the different tests using ISDG.