bluuebunny/crossref_metadata_2025 huggingface dataset:
Machinability Research and Workpiece Microstructure Characterization in Turning of Ultrafine Grained Copper
Authors: Morehead Mason , Huang Yong
Published: April 2008

Various methods for production of bulk ultrafine grained/nanostructured materials have been developed. They can be classified into two categories based on their approaches: the bottom-up and top-down approaches. Recently, a top-down approach named equal channel angular extrusion (ECAE), a form of severe plastic deformation (SPD), has been gaining more and more attention in making bulk ultrafine grained/nanostructured materials. Such bulk materials are favored for there high strength, wear resistance, ductility, and high strain-rate superplasticity, which makes them suitable for light weight engineering and medical applications. Further precision machining work is normally indispensable for structural applications after bulk ultrafine grained/nanostructured materials are manufactured from any SPD processes. While researchers are increasingly interested in commercially producing SPD-processed bulk ultrafine grained/nanostructured materials and characterizing their chemical and physical properties, the machinability and microstructure stability issues in precision machining such materials are frequently ignored. Using an ECAE processed bulk ultrafine grained copper bar as an example, this study investigates the machinability as well as machining-induced workpiece microstructure variation of such ECAE processed materials in precision turning. Tool cutting performance in turning the ultrafine grained copper bar is also compared with that of the regular copper bar.
Nano-Imprint Patterning of Nanowire Structures for Interconnect Study
Authors: Li Bin , Mavrokefalos Anastassios , Zhou Jianhua , Shi Li , Ho Paul S. , Zide Joshua , Gossard Arthur C.
Published: April 2008

A thermal nano-imprint method has been developed to pattern sub-40 nm polymer lines of Hydrogensilsesquioxane (HSQ) and electron beam resist ZEP 520A. The imprint template was the cross section surface of a selectively etched GaAs/AlGaAs heterostructure wafer. Silicon nanowires were formed using reactive ion etching (RIE) of a silicon-on-insulator wafer with the polymer nanolines as an etching mask. The obtained Si nanowires were well defined and continuous for a length up to hundreds of microns. Reaction of the silicon lines with a metal can lead to the formation of silicide interconnect lines, which is used to investigate the size effects on the transport and electromigration properties of interconnects for future microelectronics.
Optimal Support Locations for a Printed Circuit Board Loaded With Heavy Components
Authors: Chen Kun-Nan
Published: April 2008

In the design of printed circuit boards (PCBs), it is preferable to increase their fundamental frequency so as to reduce the effects of the dynamic loading on them. The dynamic characteristics of a PCB carrying various electronic components and modulus are most significantly affected by the geometrical and material properties of the bare board and by the boundary conditions supporting the loaded PCB. In this research, a PCB carrying a heavy CPU cooling fan and supported by 6 fastening screws is investigated by the modal testing experiment and analyzed by the finite element method. After the finite element model of the PCB is verified by the experimental results, the locations of the 6 supporting screws are optimized to achieve a maximum fundamental frequency for the loaded PCB. The position of each fastening screw can be determined by two design variables, i.e., x and y coordinates. Two cases are studied: the symmetric case (6 design parameters) with the symmetric constraint on the support locations imposed, and the asymmetric case (12 design parameters) without the constraint imposed. Finally, verification experiments are performed on the two PCBs supported by screws located at the optimal positions. Although relatively large differences between the calculated, optimized fundamental frequencies and the experimental values are observed, the experiments confirm a very significant improvement in frequency for both cases.
Thermal Management of a Notebook Computer
Authors: Chiang S. B. , Chien K. H. , Yang K. S. , Wu S. K. , Wang C. C.
Published: April 2008

In this study, simulations are made to resolve a 100 W heat dissipating capacity of a portable PC in (with a CPU IHS size of 31 mm × 31 mm). The problem is investigated via a commercially available software (Icepak version 4.1). The present design incorporates heat pipe to convey heat from the hot spot towards the heat sinks. The heat sinks are optimized subject to heat loads and their locations. The calculated results of a double heat sinks design show a 30 °C less temperature when compared to a single heat sink module. This is because double heat sinks design provides much more uniform temperature and eliminates the edge effect. Moreover, the effect of fin pitches is also examined in this study. It is found that the best performance is at a fin thickness of 0.2 mm and at a fin pitch of 2.4 mm. Depending on the optimal parameters of the thermal module, the chip temperature can be reduced to approximately 75 °C.
Effect of Inclination of Condensing Cover and Water Depth in Solar Still for Maximum Yield: In Winter Climatic Condition
Authors: Tiwari Anil Kr , Tiwari G. N.
Published: April 2008

In this communication, an effect of inclination of condensing cover and water depth in still, on convective mass transfer coefficient in passive solar still has been studied. Three solar stills with effective basin area of 1 m2 for three inclinations of condensing cover namely 15°, 30° and 45° have been considered. Another still with same effective area but fixed cover inclination of 30° is considered to see the effect of water depths on still performance for water depths 0.04m, 0.08m, 0.12m, 0.16m and 0.18m. Outdoor experiments have been conducted for Delhi climatic condition. Hourly variations of water, vapor, and cover temperatures along with yield have been measured. Regression analysis is used to determine the convective heat and mass transfer coefficient for outdoor condition. The 45° condensing cover is found giving maximum yield and lower water depth responded for higher yield in winter climatic condition.
Dynamic Behavior Characterization of Lead at High Strain Rates Using High Speed Photography for Finite Element Simulation
Authors: Sohoni G. S. , Walame M. V. , Tandon V. , Mahajan R. S. , Raju S.
Published: April 2008

This paper reviews experimental as well as computational techniques for determining stress-strain characteristics of materials at high strain rates. Quasi-static and dynamic compression tests were performed on standard Lead (Pb) specimens of three different L/D ratios, 0.8, 2 and 3. A Drop tower system was used to achieve different strain rates along with high-speed camera to capture the vertical and radial deformation of specimen and accelerometers to capture load data. The results obtained from the experiments were processed to generate dynamic stress-strain curve for Lead under different strain rate conditions. It was observed that the dynamic stress increases with increasing strain rate. The information gained is valuable for validating constitutive models.
A Microelectronics-Compatible Process for Surface Micromachining of MEMS and MOEMS
Authors: Goyal Meetul , Anderson Robert C. , Berg Jordan M. , Gale Richard O. , Holtz Mark , Temkin Henryk
Published: April 2008

Many fabrication steps for micro electromechanical and micro optoelectromechanical systems (MEMS and MOEMS) are carried out on specialized or highly customized tools that are not part of a standard microelectronics process flow. This paper presents a surface micromachining process for electrostatically-actuated MEMS devices using standard microelectronics tools, materials, and process conditions. The result should facilitate MEMS development in university laboratories with a microelectronics focus, and encourage the transfer of MEMS production to aging or underutilized industrial facilities. Aluminum structures, with silicon dioxide or silicon nitride dielectric layers, are built upon a silicon or glass wafer substrate. Shipley SC1827 photoresist provides a 2.7 μm thick sacrificial layer. The release etch is the critical fabrication step. This must be a dry process to avoid stiction, should be isotropic to minimize the etch time, and should be capable of large undercut distances to minimize the need for etch holes. Finally, the etch must be sufficiently selective to allow for the necessary release etch time without significantly impacting non-sacrificial structures. An O2/CHF3 plasma etch has been developed to meet these requirements. Using this process we have designed, fabricated and tested structures with moveable mirrors suspended over multiple drive and sense electrodes.
Numerical Investigation of Internal Vortex Structure in Two-Dimensional, Incompressible Richtmyer-Meshkov Flows
Authors: Mueschke Nicholas J. , Kraft Wayne N. , Andrews Malcolm J. , Jacobs Jeffrey W.
Published: April 2008

Richtmyer-Meshkov (RM) instability occurs when one fluid is impulsively accelerated into a second fluid, such that ρ1 ≠ ρ2. This research numerically investigates RM instabilities between incompressible media, similar to the experiments reported by Niederhaus & Jacobs [1]. A two-dimensional, finite-volume numerical algorithm has been developed to solve the variable density Navier-Stokes equations explicitly on a Cartesian, co-located grid. In previous calculations, no physical viscosity was implemented; however, small scale fluctuations were damped by the numerical algorithm. In contrast, current simulations incorporate the physical viscosities reported by Niederhaus & Jacobs [1] and are explicitly used. Calculations of volume fraction and momentum advections are second-order accurate in space. Unphysical oscillations due to the higher-order advection scheme are minimized through the use of a Van Leer flux limiting algorithm. An initial velocity impulse [2] has been used to model the impulsive acceleration history found in the experiments of Niederhaus & Jacobs [1]. Both inviscid and viscous simulations result in similar growth rates for the interpenetration of one fluid into another. However, the inviscid simulations (i.e. no explicit viscosity) are unable to capture the full dynamics of the internal vortex structure that exists between the two fluids due to the absence of viscous effects.
Surface Plasmon Assisted Laser Nanolithography Using Metalic Mask
Authors: Shao Dongbing , Chen Shanchen
Published: April 2008

Traditional photolithography has a resolution at wavelength scale due to optical diffraction. In this paper, a high-density direct photolithography method beyond diffraction limit by utilizing surface plasmons (SPs) was developed on virtually any substrate. Simulation results by Finite Different Time Domain (FDTD) method have shown that surface plasmon excited on both the mask and the substrate helps to confine the light behind the apertures of the mask. Numerical simulations have demonstrated that very high density sub-wavelength patterns can be transferred using this method. In experiments, a polarized laser beam of 355nm wavelength was used as a light source to photo-initiate a 80nm-thick photoresist on a silicon substrate with 50nm Ti coating. 100nm line aperture patterns were made on gold film on quartz substrate as mask. Experimental results showed that illumination intensity control is crucial to the lithography results. The feature size using such method could be further scaled down, limited theoretically by the validity of dielectric function of the material, and practically by the fabrication of mask.
The Body of Knowledge in Mechanical Engineering Technology
Authors: Danielson Scott , Hartin John R.
Published: April 2008

In November 2004, the ASME Council on Education promulgated a vision of the future of mechanical engineering education based on the work of the ASME Body of Knowledge Taskforce. Unfortunately, the vision gave only a cursory nod to Mechanical Engineering Technology (MET) as a part of the educational and professional spectrum. This paper presents an amended vision for the future of mechanical engineering technology education and a discussion of the body of knowledge as applied to engineering technology. A case is made for how the vision of the future for MET educational programs differs from mechanical engineering (ME) programs. In this, the relation of MET education to the practitioner and industry is a recurring theme. A vision is proposed speaking to the strength of MET graduates as engineering practitioners and as implementers of technology; job-ready, and focused on applied engineering. A discussion of the body of knowledge appropriate for an engineering practitioner and the impact of that perspective on mechanical engineering technology education is offered. The challenges facing MET as a result of the perceptions and misconceptions regarding its graduates and their strengths are discussed. Following the lead of the ASME vision for ME education, considerations for reshaping MET education are also proposed. A positive view of the strengths of an MET education is taken and a dialog is opened on the challenges facing MET education.
Electrical, Micro-Power Generation Using a Fluidic Oscillator
Authors: Macia Narciso F. , Nguyen Ha Van
Published: April 2008

This paper presents a fluidic device capable of generating electrical micro-power from a steady air pressure source. The Fluidic Driven Piezoelectric Generator (FDPG) relies on a fluidic pressure-controlled oscillator, a fluidic linear proportional amplifier with its output ports connected to its input ports, to convert a steady air pressure into an oscillating air pressure. The piezoelectric device then converts the oscillating air pressure into an AC electrical voltage that is available for rectification and subsequent source of electrical power. This project has demonstrated that the FDPG produces 0.55W of electrical power, with an air pressure supply of 2.0 psig. This translates to an efficiency of 35%. This paper compares the predicted power level output of an analytical model to the proof-of-concept plastic model. The fluidic oscillator model was implemented in an equivalent electrical circuit using PSPICE. This approach has applications in remote or portable pneumatic applications where intelligent instrumentation and control are needed yet no battery or auxiliary electrical power is available to drive an electronic microcontroller.
A Study of the Use of Heat Pipes in Thermal Storage for Cooling
Authors: Tardy Franc¸ois , Sami Samuel
Published: April 2008

Thermal storage is a popular method of shifting cooling loads to off-peak regions. A new method of discharge is proposed via use of a group of heat pipes inserted in a cold storage tank filled with ice, initially frozen by a separate vapor-compression system. The latent heat of the ice assures circulation in the pipes and heat exchange between warm air and the tank for several hours at a time. An experiment has been conducted by using mixtures of ice and water as phase change material inside the tank. The system is exposed to inlet air at various states of temperature, humidity and varying velocity. The system provides cooling for over 8 hours, and correlations of the system are discussed.
Noise Abatement From Large Size Electric Generators
Authors: Tong Wei
Published: April 2008

Growing environmental sound concerns and recognition that lengthy unprotected exposure to high industrial noise levels can be detrimental to man have resulted in increased attention to reducing industrial noise. In the United States, it is required by law that all turbomachinery manufacturers must provide acoustic guarantees to their customers. For instance, for majority of generators, the near field sound pressure level is usually guaranteed not to exceed 85 dBA. To accomplish this goal, a number of methods of noise reduction have been developed in power industry. As one of the most practical and cost-effective solutions, acoustic blankets have been designed and tested for using on large size electric generators to efficiently reduce their sound pressure levels. This work has successfully demonstrated the potential of acoustic blankets for improve the passive acoustic transmission characteristics from generators. The acoustic data obtained from a field test have shown that the blankets can reduce the overall sound pressure level from large size generators about 4 to 6 dBA.
Numerical Approach to the Optimization of Operating Conditions for Hydrogen Polymer Electrolyte Fuel Cells
Authors: Wu Junxiao , Liu Qingyun , Fang Hongbing
Published: April 2008

An efficient and systematic approach for finding the optimal operating conditions of hydrogen polymer electrolyte fuel cells has been developed by combining an efficient optimization method and a validated multi-resolution fuel cell simulation tool. Four control parameters including cell temperature, cathode stoichiometry, cathode pressure and cathode relative humidity are used to build the optimization objective, which is defined as the maximum overall efficiency of the fuel cell system under ideal or realistic system assumptions. Through the design of experiment method, a set of sample simulations are first carried out using the fuel cell simulation tool. An analytic metamodel is then constructed using the radial basis function approach based on the simulation results. A feasible sequential quadratic programming scheme is then employed to optimize the metamodel to achieve the global optimal solutions. The study shows that different optimal solutions exist for different system assumptions, as well as different current loading levels, classified into small, medium and large current densities. The approach adopted in this study is generic and can be readily applied to more control parameters and further to the fuel cell design optimizations.
Engine Testing of Advanced Materials for Hypersonic Applications
Authors: Bur Michael J.
Published: April 2008

This paper describes the use of a ground based gaseous hydrogen/oxygen rocket engine to test advanced materials for rocket engine and hypersonic propulsion applications. The types of materials that have been tested include ceramic composites, metallic alloys and ceramic and metallic foams. There are various configurations in which these materials can be tested. A “square” engine is used for testing flat rectangular panels by placing the panel downstream of the rocket nozzle in the exhaust path. A more traditional “round” rocket engine is used to test axisymmetric engine components such as nozzle inserts and combustion chambers that are fabricated from either ceramic composites or metal alloys. Besides hydrogen, other engine fuels such as methane are being evaluated in order to expose test materials to a hydrocarbon environment. Various organizations from industry, academia and other government agencies have used this test cell to facilitate the development of advanced materials for use in both rocket engine and hypersonic propulsion applications.
Static Recrystallization Modeling With a Cellular Automata Algorithm
Authors: Wu Yujie , Yu Qiang , Esche Sven K.
Published: April 2008

This paper reports on one part of a research project supported by NSF, which aims at developing a multi-scale methodology for systematic microstructure prediction in thermo-mechanical processing of metals. Based on combining mesoscopic microstructure models with macroscopic process formulations, the methodology is expected to provide universally applicable and accurate microstructure prediction capabilities. Cellular Automata (CA) models have been widely used in scientific studies of various microstructural phenomena. This paper discusses the modeling of the static recrystallization phenomenon by employing a regular CA algorithm. The recrystallization processes of single-phase systems under different nucleation conditions are simulated followed by the recrystallization kinetics analysis for 200 × 200 two-dimensional lattice. The performed simulations of static recrystallization confirm that the recrystallized volume fractions are time dependent. Furthermore, the simulated microstructures validate the following Johnson-Mehl-Avrami-Kolmogorov (JMAK) model according to which the recrystallized volume fraction is a sigmoidal function of time, and their evolution matches the JMAK equation with the expected exponents.
An Experimental Study of Catalyst-Assisted Premixed Methane/Air Combustion in a Stagnation-Point Flow
Authors: Wiswall James T. , Wooldridge Margaret S. , Im Hong G.
Published: April 2008

Micro-scale combustion is an attractive alternative as a power source for numerous applications. The high-energy densities of hydrocarbon fuels make micro-scale combustors particularly appealing in comparison to fuel cells, batteries and other power generation devices. One of the major difficulties in the development of a micro-scale reactor is to sustain stable combustion in a small device with a high surface-to-volume ratio. To this end, catalytic combustion is considered a viable means to extend the operating range of combustors. In this work, a new stagnation-point flow burner facility has been developed to provide a canonical framework to study the interactions between fluid dynamics and chemical reactions in the gas-phase and heterogeneous modes. The stagnation-point flow burner is used to study extinction limits of catalyst-assisted premixed methane combustion. Basic characterization of the burner is performed and preliminary experimental data for extinction limits are presented as a function of the flow strain rate, mixture equivalence ratio, and the level of catalytic activity.
Integrated Eco-Thermal Management for Aerospace
Authors: Reznikov Lev
Published: April 2008

Thermal Management System developed for aerospace carriers (missile, aircraft, space station), bounds processes of generation and dissipation, transfer and conversion of power, refrigeration, and of bio-metabolism related substances. Local ecosystem of the carrier combines technological and biological subsystems, interacting with internal and outer spaces. The conceptual IETM System performs recovery of waste thermal energy, generation of “free” refrigeration, and recovery of byproducts into safe coolants (ammonia - water). Thermal Management solutions include novel technologies of intensification of the heat transfer and of conversion of the waste resources into refrigeration for extension of cooling capabilities for high heat radars, lasers and microwave generators. The IETM includes Vacuum-Evaporative Refrigeration (VER) utilizing “free natural” vacuum and waste heat-activated refrigeration circuits. VER generates ~1000 Btu of “free” cold per pound of wastewater or ammonia. The introduced high performance microstructure of compound electrohydrodynamic (EHD) boundary microsystems intensifies nucleate boiling, preventing dryout. The coils of the microwires adjoin to the boiling surface and form precision microstructure of heat sink with microchannels between the coils and the surface. The microcavities form the active bubbling nucleation sites along the spiral zones of contacts of the microwires and basic surfaces. The fins-microelectrodes develop additional heat transfer surface and evenly distributed spiral zones of the nucleation sites. Like fibers of a fine wick, the electric forces in EHD capillary structures of the microelectrodes retain the liquid and push out generated vapor bubbles from the surface. Good manufacturability and performance of novel MEMS are based on well-developed materials and common winding technology “borrowed” from electrotechnical industry. Conversion of waste resources into refrigeration and EHD activation of boiling allow meeting strong limitations in weight, reliability and consumption of energy. These conceptual approaches provide diversities in refrigeration capabilities for IETM.
Development of an Analog Controller for Tuning an Adaptive-Passive Control Device
Authors: Johnson Marty , Diggs Edward C.
Published: April 2008

Adaptive-passive devices such as adaptive Helmholtz Resonators (HR) and tunable vibration absorbers have been shown to be suitable for controlling both narrowband disturbances and lightly damped structural/acoustic modes driven by broadband disturbances. In order to track changes in the disturbance or changes in the modes, the natural frequency of the absorber, ωn, is tuned to match the observed signals. This is achieved by altering some physical parameter of the control device such as the stiffness of a vibration absorber or the neck cross-sectional area of a Helmholtz resonator. In order to automatically adjust these devices, control systems and tuning algorithms have been developed, most of which involve a digital controller. However, this paper looks specifically at the development of a simple analog controller used to drive a DC motor in order to tune a mechanical device. A two sensor dot product method is employed where one sensor is placed inside of the control device, such as a Helmholtz Resonator, and the other on/in the system under control, such as in a room. The outputs from the two sensors are multiplied together and subsequently low passed in order to extract a low frequency “DC” voltage which acts as an error signal. The error signal is related to the relative phase of the two sensor signals and determines the direction in which the device should be tuned. When the two signals are 90° apart, the system is tuned (i.e. the inner product produces zero DC level). If the drive frequency ω is different than the tuned frequency, then the system is mis-tuned. The relationship between the mis-tuning, ωn-ω, and the error is not linear, but for small perturbations a linear approximation can be used to investigate the stability and performance of the system. The gradient of the function is shown to be largest when the mis-tuning error is zero and is inversely proportional to the damping level in the control device. Once stability of the system has been ensured the ability of the system to track changes in drive frequency is investigated experimentally. The control system is demonstrated using an adaptive Helmholtz resonator which has a variable cross-sectional neck via an iris diaphragm. The iris is controlled using a small DC motor; two microphones (one mounted internally and one externally) are used to supply the driving signal to the circuit.
Product Platform Development: Considering Product Maturity and Morphology
Authors: Yang Tae G. , Beiter Kurt A. , Ishii Kosuke
Published: April 2008

In this paper we continue our development of a structured methodology for product platform development suited to the early design stages. In addition to the previous focus on differences between new and mature products, we now consider how platform development is influenced by the morphology of a product. Purely physical products (e.g., a vacuum cleaner) often pose fewer challenges when undergoing platform design. However, products such as software, service offerings, or process-oriented solutions require adapting previous platform methods in order to accommodate the “amorphous” nature of the system. This paper includes a review of the recent literature in this area, and presents the authors latest platform methodology from the perspective of product morphology and maturity. Illustrative examples are used throughout.
Hydrodynamic Study of a Water-Propelled Rocket: An Undergraduate Experiment in Fluid Mechanics
Authors: Thorncroft Glen E. , Pascual Christopher C.
Published: April 2008

An undergraduate experiment has been developed to measure the performance of a pressurized water rocket and compare test data to an analytical model developed from fluid momentum. A rocket and test stand were developed to measure the net thrust of the rocket, as well the air pressure and temperature inside the rocket, as a function of time. The model compares well to test data from four conditions, combinations of two initial water heights and two initial air pressures. The air in the rocket was assumed to under go polytropic expansion, and a value of 1.1 for the polytropic exponent was found to best fit the model to all experimental conditions. Experimental observations also reveal that, at higher air pressures, the air mixes with the expelled water, resulting in a two-phase flow that reduces the net thrust of the rocket. A pedagogical approach is also developed for the experiment and is described indetail.
Probabilistic Mapping for Unmanned Rotorcraft Using Point-Mass Targets and Quadtree Structures
Authors: Caveney Derek S. , Kang Yeonsik , Hedrick J. Karl
Published: April 2008

In this paper, the authors present a technique for constructing probabilistic occupancy maps for unmanned rotorcraft. The mapping technique is Bayesian and assumes that a ranging sensor positioned on the rotorcraft is providing noisy target measurements in the presence of clutter. By running a multiple-model Kalman filter-based algorithm, all measurements are used to provide point-mass target state estimates and associated state covariances. Furthermore, the multiple-model algorithm provides probabilities that indicate whether each target is a true target or a false alarm. These three attributes of each target (the state, covariance, and true target probability) are used to build and update the occupancy map. The map is built upon a quadtree structure that allows for higher map resolution in occupied areas of the operating environment and quick access of obstacle locations. This aspect of a quadtree-structured map is particularly useful when transferring obstacle information to obstacle avoidance and route planning routines. The construction of occupancy maps resulting from this quadtree-based, probabilistic technique is demonstrated through simulations of a low-flying rotorcraft travelling through an urban landscape.
Experimental Investigation and Mechanistic Modeling of the Effects of Tool Edge Hone Effects in Turning Operations
Authors: Ranganath Santosh , Campbell Albert B. , Hwang Jihong
Published: April 2008

Cutting force predictions from machining process models are generally accurate to within 20% for a specific tool and work material combination over a wide range of cutting conditions when calibrations are accurately performed. The calibration implicitly assumes that the tool used in the cut has a sharp cutting edge (zero radius) or identical (and maybe unknown) cutting edge radius. Significantly higher errors (more than 20%) in force calculations are seen when the same calibration data is used for predictions across a wide range of edge radii, also referred to as an edge hone. This paper describes the preliminary experimental work done to understand the impact of a honed cutting edge on the calibration of the force coefficients used by mechanistic models. Tube turning tests were performed on gray cast iron using tools of varying edge radii, and the cutting and thrust forces measured. Useful correlations between the edge radius and the machining force were observed although some of the results were confounded by variations in the temperature at the cutting edge. A new mechanistic calibration approach is applied to obtain the force coefficients from the measured forces that gives accurate results when the ratio of chip thickness to edge radius is used to calibrate the forces. This method has the advantage of being dependent only on the geometric size of the honed edge in relation to the thickness of the chip that is being removed. This allows the calibration to be performed with lesser experimental effort, while still being valid for predictions over a wide range of edge radii. Validation of this approach was performed using a range of edge hone sizes with peak force prediction errors less than 17%.
Direct-Write Fabrication of Microchannel in Epoxy Matrix
Authors: Ghafar-Zadeh Ebrahim , Sawan Mohamad , Therriault Daniel
Published: April 2008

This paper describes the fabrication of microchannels by direct-write assembly and their integration into CMOS circuit technologies. A robotic apparatus was used to deposit a fugitive ink filament on glass and CMOS chip substrates. An epoxy and a nanocomposite matrix were both used to enclose the ink which was subsequently removed under heat and pressure in order to form a microchannel. Here, we demonstrate the fabrication of a microchannel by direct-write assembly on top of a CMOS chip for potential laboratory-on-chip applications such as bioparticle detection and manipulation.
CFD Simulation of Debris Transport in a PWR Reactor Sump Following a Loss of Coolant Event
Authors: Cain Stuart A. , Gartland Fariba , Johansson Andrew E.
Published: April 2008

High Energy Line Breaks (HELBs) inside nuclear reactor containment are recognized as challenges to Pressurized Water Reactor (PWR) nuclear power plants arising from the collateral damage due to insulation, fireproofing, coatings, and other miscellaneous materials (such as tags, stickers, signs, etc) which are shredded and transported during the event. These materials, as well as latent debris (dirt and dust) will be washed towards the containment floor and the recirculation sump screens by flow from both the HELB and the containment spray headers. This debris, if washed towards the recirculation pumps, could potentially impede the performance of the ECCS system. To evaluate transport of material towards the sump and the potential for degradation in performance of the ECCS system, Computational Fluid Dynamics (CFD) has been used to predict the flow patterns and energy levels in the containment pool during the recirculation phase of the event. Further, a unique methodology has been applied to correlate the CFD results with material-specific laboratory flume data and predict the volume of material transported to the sump screens. The predicted volume of debris transported to the sump screens is then used to determine if there is sufficient suction head for the pumps to operate without the potential for cavitation. In this paper, the CFD-based methodology used to predict material transport to the sump screens is discussed and the results of a prototype containment analysis are presented. Of particular interest is the analytical method for introducing the HELB flow into the containment pool and the quasi-steady treatment of the water surface to simulate the gradual filling of the pool. Coupling of the velocity and kinetic energy fields from the CFD simulations with material-specific incipient tumbling velocities (as predicted during a series of laboratory flume tests) are presented and used to demonstrate overall material transport to the sump screens.
Modeling Heat Transfer From a Vertical Isothermal Plate Using a One-Dimensional Turbulence Stochastic Mixing Model of Turbulence
Authors: Shihn Harmanjeet , DesJardin Paul E.
Published: April 2008

A turbulent natural convection boundary layer along a vertical isothermal flat plate in air is investigated based on the one-dimensional turbulence (ODT) modeling approach of Kerstein. The advantage of this approach is that near-wall conduction process can be treated without approximation. The effects of multi-dimensional turbulent mixing processes are modeled using a stochastic process description via triplet mapping stirring events. Adapting the ODT model to the problem of an isothermal plate includes modifying the local characteristic eddy time scale to account for the effects of buoyancy induced mixing mechanisms. Both a Lagrangian and Eulerian implementations of the ODT model are presented. Profiles of time-averaged and RMS velocity and temperature are compared to experimental data and existing self-similarity theory for thermal boundary layer along with Nusselt number predictions.
Simulation Study of Static and Dynamic Characteristics of Piezoelectric Thin Film Coated Polymer Tube
Authors: Jayatissa Ahalapitiya H. , Gadupudi Himabindu
Published: April 2008

A novel piezoelectrically actuated micropump was designed and its characteristics were simulated. The proposed structure of micropump consists of a polymer pipe coated with three curved piezoelectric strips, which actuate the polymer pipe walls using an external power source. A three dimensional finite element analysis (FEA) was used to study the deformation in the polymer pipe. The pump prototype comprises three semi-cylindrical discs made of PZT-5H and a polyimide pipe; PZT discs are placed on the opposite sides of a polyimide pipe. The structure was simulated for a wide range of voltages and frequencies. The stroke volume of the micropump was calculated using the deformation profiles obtained from the FEA. The results indicated that the change of stroke volume of pipe was functions of both voltage and frequency of power. Also there were few peak points of stroke volume associated with bending mode of piezoelectric strips. At the lower frequency (<1 KHz) and voltage regions (<100 V), a flow rate of few μl/min could be achieved for a pump designed with check values at the end of the pipe.
Fluid-Structure Simulations for a 2D Fire Applications
Authors: Xie Wei , Luo Changsong , DesJardin Paul E.
Published: April 2008

This study is on the development of numerical algorithms and models for simulation of a structure response in a fire. The flow field from the fire plume is modeled using the 2D Navier-Stokes equations supplemented with a transport equation for thermal energy and solved using a vorticity-streamfunction approach. Coupling of the fluid to the FEM based structure model is based on the use of a level set method describing the structure geometry in the fluid domain. The level set function allows for computation of normal gradients at the fluid-solid interface to enforce local boundary conditions of heat and mass transfer at prescribed fluid-structure coupling time increments. Numerical simulations of a two-dimensional composite cantilever beam subject to convection heat loading from a fire plume are presented requiring coupling of both the thermal and mass transfer processes at the fluid-structure interface. Results are presented showing the thermal response of a composite beam to a fire plume and the sensitivity of the heating to fire location.
Numerical Study of The Interference Effects in Small Vertical Axis Wind Turbines
Authors: Sato Yuko , Kawamura Tetuya
Published: April 2008

Two dimensional flows around multiple small wind turbines installed in a line are investigated by numerical simulation. The turbines which studied in this research are cross-flow type with vertical axis. Incompressible Navier-Stokes equation is solved by the finite difference method based on the Fractional Step method. Overset grid system is employed in this simulation. A rotating coordinate system, which rotates at the same speed of the turbines, is used for a vicinity of the rotor and a stationary coordinate system is used for the other area. The interference among lined cross-flow wind turbines is investigated for their urban area use.
Optimal Design of an Acoustic Enclosure for Minimal Broadband Sound Radiation
Authors: Lee Dongjai , Koopmann Gary H. , Belegundu Ashok D.
Published: April 2008

Reducing unwanted noise radiating from a vibrating structure continues to be a major challenge in engineering design. In this paper, high impedance structures characterized with uniquely identifiable resonance modes are considered for sound power reduction using an enclosing surface. An optimization strategy for the thin enclosure design is presented. A close-fitting and equipment-mounted enclosure is attached to the vibrating structure with translational springs. To model the coupled system, a new compact and symmetric system matrix analysis using component modal synthesis and fluid displacement potential to deal with the coupled system is developed. This leads to a new application of optimization to the coupled system to reduce the radiated sound power. Numerical optimizations are performed for a plate enclosure. It is shown that large reductions in radiated sound power are possible with optimally positioned and rated attachment springs.
Numerical Predictions and Experiment Results for a 1m Diameter Methane Fire
Authors: Black Amalia R.
Published: April 2008

Comparisons between numerical predictions and experimental data for a methane fire have been performed. Vertical velocity and turbulent kinetic energy measurements along the centerline of the fire were used to validate the models in the SIERRA/Fuego fire code. Two different turbulence treatments, a steady RANS solution with a model for buoyancy generated turbulence, and an unsteady solution with closure models based on a temporal filter width were used. Solution sensitivity to grid size has been examined for both approaches. The results indicate strong sensitivities to the turbulence model.
Thermal Characterization of Two Opposing Carbon Nanotube Arrays Using Diffraction-Limited Infrared Microscopy
Authors: Hu Xuejiao , Panzer Matt , Goodson Kenneth E.
Published: April 2008

Due to their extremely high thermal conductivity, carbon nanotubes (CNTs) have received many research interests for thermal management applications. An advanced thermal interface structure made by two opposing, partially over-lapped CNT arrays is designed for thermally connecting two contact surfaces. The performance of this interface structure is thermally characterized using diffraction-limited infrared microscopy. Significant temperature discontinuities are found at the end of the CNT-CNT contact region, which indicates a large thermal resistance between CNTs. Due to this inter-tube resistance, the thermal performance of the CNT-based interface structure is far below expectation, with a thermal resistance value of about 3.8 × 10−4 K·m2/W. Possible mechanisms of heat transfer between CNTs, which result in the large inter-tube resistance, are discussed.
Experimental and Analytical Study of the Crashworthiness for the 2005 Ford GT Aluminum Spaceframe
Authors: Caliskan Ari G. , Jeryan Richard A. , Mees Huibert , Iregbu Simon
Published: April 2008

The use of aluminum structures in the automobile industry have been increasing in the past decade due partly to the demand for light-weight vehicles, and in some instances, lower investment costs. In the case of the 2005 Ford GT, an aluminum spaceframe architecture was chosen. The spaceframe structure consists mainly of extruded 6xxx series aluminum profiles with aluminum castings acting as suspension attachment points. The aluminum castings, located at both the front and rear of the vehicle, also act as nodes to which a number of extrusions are welded. This architecture resulted in a very stiff, yet light-weight vehicle. In addition to stiffness and weight advantages, the use of both aluminum members and the spaceframe construction proved to have good crashworthiness properties for all impact modes. In this paper, the crash performance of the front end of the vehicle consisting of an extruded bumper and double-cell rail system is shown. Once the components were manufactured, specimen level tests were conducted to measure the stress-strain behavior of the extruded material. This information, along with the geometric data of the bumper and rails, was used to create models of the front-end of the vehicle. A series of analyses were conducted using a rigid barrier impact to determine crush loads as well as mode of collapse. Concurrently, the components were assembled and tested using a sled impact facility at speeds comparable to full vehicle impact speeds. The results of the component tests and the analyses showed that the models predicted both the crush loads as well as the crush modes accurately. This validation exercise proved to be key in creating accurate full vehicle models for all the crash modes that are required for certification of the vehicle. As such, development time as well as the number of full vehicle tests was reduced.
Air-Car
Authors: Anwar Mahmood
Published: April 2008

The name of my proposing project is “air-car”. Now a day’s traffic jam is common problem of the mega city, especially in third world countries. so, if we design the traffic system such that the light vehicles like car will flies over certain height from the ground level about 100-200 ft and the heavy vehicle like bus, truck, lorry, etc. will run on the road simultaneously then the traffic jam will be minimize with a large scale. Let us introduce with the concept “air-car”. Air car is the vehicle which can run in both way of air and road. That means that it can fly over a certain height from the ground and also run in the road as usual. We know that for the car design is such the lift force is minimized than the drag force. I want to design for the car such that, when the car has to fly lift force will be increase as much as it can fly for the required height. The body of the car also be a stream line body and the flap, aileron, rudder also be added. But this should be hidden at the time of running in the road.
A Preliminary Evaluation and Analysis of Technologies for Eliminating Railway Insulated Joints
Authors: Ahmadian Mehdi , Dillard David A.
Published: April 2008

This paper will investigate the feasibility of adopting innovative design concepts that could decrease the dependence on bonded insulated joints for railway track monitoring. First, the purpose of insulated joints and their historical usage are examined. Next, designs that utilize track circuits are discussed. This will be followed by a section on acoustic methods, reflectometry, and robotics.
Nonlinear Dynamics and Control of the Scan Process in Noncontacting Atomic Force Microscopy
Authors: Hornstein S. , Gottlieb O. , Ioffe L.
Published: April 2008

The focus of this paper is on the nonlinear dynamics and control of the scan process in noncontacting atomic force microscopy. An initial-boundary-value problem is consistently formulated to include both nonlinear dynamics of a microcantilever with a localized atomic interaction force for the surface it is mapping, and a horizontal boundary condition for a constant scan speed and its control. The model considered is obtained using the extended Hamilton’s principle which yields two partial differential equations for the combined horizontal and vertical motions. Isolation of a Lagrange multiplier describing the microbeam fixed length enables construction of a modified equation of motion which is reduced to a single mode dynamical system via Galerkin’s method. The analysis includes a numerical study of the strongly nonlinear system leading to a stability map describing an escape bifurcation threshold where the tip, at the free end of the microbeam, ‘jumps-to-contact’ with the sample. Results include periodic ultrasubharmonic and quasiperiodic solutions corresponding to primary and secondary resonances.
Thermomigration Induced Strain Field Simulation for Microelectronic Lead Free Solder Joints
Authors: Li Shidong , Lin Minghui , Abdulhamid Mohd F. , Basaran Cemal
Published: April 2008

Many factors such as high intensity current, thermal load, shock load, vibration load and etc., can induce the failure in electronic equipment. It is common for electronic equipment to be subjected to a combination of the loads mentioned above simultaneously. In this paper, qualitative finite element simulations of thermomigration induced strain fields in lead free solders are conducted using a fully coupled displacement-diffusion model [1] with nonlinear mechanical material properties. The solutions are discussed and compared to experimental data as well as theoretical developments from literature.