bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Conductivity of Ultra Thin Single Crystal Silicon Layers: Part II — Experimental Data and Modeling at High Temperatures
Authors: Liu Wenjun , Asheghi Mehdi , Goodson K. E.
Published: April 2008

Simulations of the temperature field in Silicon-on-Insulator (SOI) and strained-Si transistors can benefit from experimental data and modeling of the thin silicon layer thermal conductivity at high temperatures. This work presents the first experimental data for 20 and 100 nm thick single crystal silicon layers at high temperatures and develops algebraic expressions to account for the reduction in thermal conductivity due to the phonon-boundary scattering for pure and doped silicon layers. The model applies to temperatures range 300–1000 K for silicon layer thicknesses from 10 nm to 1 μm (and even bulk) and agrees well with the experimental data. In addition, the model has an excellent agreement with the predictions of thin film thermal conductivity based on thermal conductivity integral and Boltzmann transport equation, although it is significantly more robust and convenient for integration into device simulators. The experimental data and predictions are required for accurate thermal simulation of the semiconductor devices, nanostructures and in particular the SOI and strained-Si transistors.
Dynamics of Temperature Gradient Focusing
Authors: Huber David , Santiago Juan G.
Published: April 2008

Temperature gradient focusing (TGF) is a promising new type of field gradient focusing that simultaneously concentrates and separates charged species according to their electrophoretic mobilities. We develop a simple control volume analysis and leverage a previously reported dispersion model to describe the dynamics of TGF. We experimentally verify the prediction of linear growth in area averaged intensity, and briefly examine the effects of dispersion and Joule heating on peak intensity.
Design of a Microfabricated Device for the Ligase Detection Reaction (LDR)
Authors: Barrett Dwhyte O. , Maha Amit , Wang Yun , Soper Steven A. , Nikitopoulos Dimitris E. , Murphy Michael C.
Published: April 2008

The Ligase Detection Reaction (LDR) is a mutation detection technique used to identify point mutations in deoxyribonucleic acid (DNA). A microscale Ligase Detection Reaction (LDR) device was designed and manufactured in polycarbonate. There are at least two mixing stages involved in the LDR identification process. Various micromixers were simulated in Fluent (v5.4, Lebanon, NH) and several test geometries were selected for fabrication. Passive diffusional micromixers were made with aspect ratios from 7 to 20. The mixers were made by SU-8 lithography, LIGA, laser ablation and micromilling to characterize each fabrication method. It was found that LIGA was best for making the micromixers, but was the longest process. The micromixers were fabricated and are being tested using fluorescent dyes. For a successful reaction temperatures of 0°C, 95°C and 65°C were needed. A stationary chamber method was used with thermal cycling in which the sample held while the temperature is cycled. Finite element analysis showed uniform temperatures in the rectangular 1.5 μl chambers and that air slits can effectively separate the thermal cycle zone from the 0°C cooling zone and the mixing region. A test device was laid out and micromilled with the temperature zones. A commercial thin film heater and a thermoelectric module were used with a PID controller to obtain the required process temperatures. Heating from 65°C to 95°C took 10 seconds, while cooling from 95°C to 65°C also took 10 seconds. The residence times at the required temperatures can adapt to changes in the LDR as parameters and reactant concentrations are varied.
The Effect of Occupant Behavior on Residential House Energy Consumption
Authors: Emery A. F. , Kippenhan C. J.
Published: April 2008

Space conditioning energy needs are strongly affected by occupant behavior. Generally, simulations ignore the behavior of the occupants in estimating the energy needed for heating and cooling. During winter heating, it is reasonable to assume that the electricity associated with appliances contributes to the space heating needs. This paper describes the monitoring of energy used for space heating over a 15 year period. The data suggest that estimates of energy savings can be based upon envelope thermal resistance for moderate occupant behavior. For these occupants space heating is well characterized by the daily average difference between house average space temperature and outside air temperature. Characterizing in terms of indoor temperature, outdoor air temperature, wind speed, and insolation gives a slightly better representation but requires more information than is usually available. However, vigorous conservation tactics can lead to substantially different energy needs and no correlation could be established when aggressive conservation made use of thermostat setback at every opportunity.
Thermal Characterization of Cu/CoFe Multilayer for Giant Magnetoresistive (GMR) Head Applications
Authors: Yang Y. , Asheghi M.
Published: April 2008

Giant Magnetoresistance (GMR) head technology is one of the latest advancement in hard disk drive (HDD) storage industry. The GMR head superlattice structure consists of alternating layers of extremely thin metallic ferromagnet and paramagnet films. A large decrease in the resistivity from antiparallel to parallel alignment of the film magnetizations can be observed, known as giant magnetoresistance (GMR) effect. The present work characterizes the in-plane electrical and thermal conductivities of Cu/CoFe GMR multilayer structure in the temperature range of 50 K to 340 K using Joule-heating and electrical resistance thermometry in suspended bridges. The thermal conductivity of the GMR layer monotonously increased from 25 Wm−1K−1 (at 55 K) to nearly 50 Wm−1K−1 (at room temperature). We also report the GMR ratio of 17% and a large negative magnetothermal resistance effect (GMTR) of 33% in Cu/CoFe superlattice structure. The Boltzmann transport equation (BTE) is used to estimate the GMR ratio, and to investigate the effect of repeats, as well as the spin-dependent interface and boundary scatting on the transport properties of the GMR structure. Aside from the interesting underlying physics, these data can be used in the predictions of the Electrostatic Discharge (ESD) failure and self-heating in GMR heads.
Elucidating Water-Droplet Removal in Polymer Electrolyte Fuel Cells
Authors: Noble D. R. , Chen K. S.
Published: April 2008

The process of removing liquid water droplets in polymer electrolyte fuel cells (PEFC) is examined using a simple analytical model and two-dimensional simulations. Specifically, the stability of a droplet adhering to the wall of the cathode flow channel is examined as a function of the geometry of the flow channel, the applied pressure gradient, and the wetting properties. The result is a prediction of the critical droplet size as a function of the difference between the advancing and receding contact angles, or contact angle hysteresis. The analytical model is shown to qualitatively predict this stability limit when compared to two-dimensional simulation results. The simulations are performed using both Arbitrary Lagrangian Eulerian (ALE) methods and level set methods. The ALE and level set predictions are shown to be in good agreement.
Design of Machine Vision Systems for Improving Solder Paste Inspection
Authors: Reynolds Matthew R. , Campana Claudio , Shetty Devdas
Published: April 2008

The quality of solder joints is a crucial aspect on circuit card assemblies containing fine-pitch, surface mount technology (SMT) components. Modern aerospace equipment manufacturers are therefore implementing machine vision systems for the inspection of their electronic products. These methodologies offer many process improvements including faster cycle times, early defect detection, and the ability to efficiently track statistical data. This paper discusses machine vision systems for dimensional verification of solder paste deposited on printed circuit boards. The intent is to show that by focusing on vision inspection early in the assembly process, defects can be detected prior to component placement and solder reflow. Example vision systems and methodologies will be described for applications involving SMT assembly processing. Specifically, various cost-effective techniques for measuring solder paste height and volume will be presented as a means of maintaining solder joint quality. Verification of the aforementioned dimensional attributes is currently very important in the aerospace electronics industry as smaller SMT package and lead sizes are migrating to production.
A Frequency-Tunable Comb Resonator Using Spring Tension and Compression Effects
Authors: Lee Ki Bang , Pisano Albert P. , Lin Liwei
Published: April 2008

A 2μm-thick frequency-tunable microresoantor capable of either increasing or decreasing its resonant frequency by a combination of Joule heating and electrostatic force has been successfully demonstrated for the first time. For the heating voltage increase from 0 to 2V under fixed bias voltage of 40V, the resonant frequency changes from 22.2kHz to 16.2kHz, resulting in the 27% reduction in the resonant frequency. For the bias voltage change from 20V to 40V under the heating voltage of 0V, the resonant frequency increase from 19.0kHz to 23.6kHz, resulting in the 24.2% increase in the resonant frequency. As such, this surface-micromachined microactuator could assist complicated frequency tuning for applications of microsensors and microactuators.
Investigation of the Injury Behavior in Thermal Therapy of Human Renal Cell Carcinoma Cells Using a Non-Isothermal Method
Authors: He Xiaoming , Bischof John C.
Published: April 2008

In this study, the thermal injury behavior of both suspended and attached human renal cell carcinoma (RCC) SN12 cells under thermal therapy conditions (i.e., heating cells to elevated temperature for seconds to minutes) was investigated using a non-isothermal method. This non-isothermal method entailed heating the cells using a programmable heating stage from room temperature at 130°C min−1 to various peak temperatures from 45 to 70°C, held for 0 to 10 minutes, and then cooled down to room temperature at 65°C min−1. It was found that the suspended SN12 cells are more heat susceptible than attached ones. The non-isothermal portions (i.e., the heat-up and cool-down portions) of the thermal histories were found to be able to cause significant injury (>10%) in both suspended and attached SN12 cells when the peak temperature is above 60°C. Therefore, a new non-isothermal method, which accounts for both the isothermal and non-isothermal portions of the thermal histories, was used to extract the kinetic parameters (i.e., the activation energy and frequency factor) in the Arrhenius injury model for SN12 cells. Furthermore, these results suggest that this non-isothermal method can be used to extract kinetic parameters from in vivo heating studies using minimally invasive surgical probes, where it is very difficult to get a thermal history in tissue with a dominant isothermal portion.
Analysis of Thermal Stress in Cryosurgery of Kidneys
Authors: He Xiaoming , Bischof John C.
Published: April 2008

In this study, the thermal stress distribution in cryosurgery of kidney was investigated using a multi-physics finite element model developed in ANSYS (V7.0). The thermal portion of the model was verified using experimental data and the mechanics portion of the model (elastic) was verified using classic analytical solutions. Temperature dependent thermal and mechanical properties were used in the model. Moreover, the model accounts for thermal expansion due to both temperature change and volumetric expansion associated with phase change of tissue water to ice. For a clinical cylindrical cryoprobe inserted into the renal cortex from the top-middle renal capsule, it was found that the thermal stress distributions along the radial position are very different at different depths from the top renal capsule. The thermal stress is much higher at both ends than in the middle of the cryoprobe surface. It was found that there might be more tissue next to the top renal capsule which undergoes microcrack formation or plastic deformation. Furthermore, it was found that macrocrack formation is more likely to occur in tissue adjacent to the cryoprobe surface (especially on the sharp point tip) and during the thawing phase of cryosurgery. Because the thermal stress adjacent to the cryoprobe is much higher than the yield stress of frozen renal tissue, a plastic stress model is required for better modeling of the thermal stress distribution in cryosurgery of kidney in future although the computational effort will be drastically increased due to the strong nonlinear nature of the plastic model and more studies are required to understand the mechanical properties of frozen tissue.
Product Platform Development: An Approach for Products in the Conceptual Stages of Design
Authors: Yang Tae G. , Beiter Kurt A. , Ishii Kosuke
Published: April 2008

Most design for Manufacturing (dfM) applications to date have focused on a particular model of a product. Recent drive for faster times-to-market are drawing attention of companies like ABB, BMW, Ebara, Nissan and Toshiba to product architecture, i.e., achieving platforms that cover diverse market segments over multiple generations. The trend in industry also has shown two major types of platform development activity: architecture innovation and platform refinement. Architecture innovation addresses new products as well as amorphous products such as system and service products. Platform refinement concerns mostly existing products and involves identifying current platform base, and optimizing its structure. The critical steps in platform design are the definition of specific drivers, and the identification of complexity and requirement metrics. Complexity and requirement metrics contribute to developing the value model under specific drivers for the desired platform. This paper discusses the past platform related work from academia in these perspectives, proposes a 5-step methodology co-developed with Toshiba along with their pilot examples, and a future research agenda.
Mechanical Performance of Silicon Diaphragm for Space Application
Authors: Zhao Yi , Li Biao , Ludlow Daryl , Zhang Xin
Published: April 2008

In micro satellites, delicate instrumentations are compacted into a limited space. It raises concerns of active cooling and remote cooling. Silicon based micro-pump arrays are employed thanks to manufacturing simplicity, a small cryogen charge, etc., which keeps the instrumentations within a narrow cryogenic temperature range. The mechanical performance of the silicon diaphragm, the key component of the micro-pump, is critical in terms of heat balance calculation and life time evaluation. This paper examines the mechanical performance of the silicon diaphragm under cryogenic temperature for micro satellite applications. In this work, differential pressure was used for the actuation of a single-crystal silicon diaphragm. Diaphragm deflection and stress distribution were achieved using interferometry and micro Raman spectroscopy, respectively. As a result, a higher elastic modulus was associated with the diaphragm under cryogenic temperature, comparing to that under room temperature, indicating a stiffer material. From stress mapping, the edge centers were believed to be the most vulnerable to fracture, which was further validated by analyzing the fracture diaphragm. Moreover, a fatigue testing was conducted for 1.8 million cycles with no damage found, verifying thin film silicon as a viable material for long time operation in a cryogenic environment.
Bubble Based Microfluidic Sensors
Authors: Ateya Daniel A. , Shah Ashish A. , Hua Susan Z. , Sachs Frederick
Published: April 2008

A microfluidic sensor using an electrolytic bubble sensing element has been developed and characterized. Impedance measurements in a microfluidic channel are used to monitor the volume changes of an electrolytic bubble. Parameters affecting bubble volume are identified and provide the basis for detection of properties such as pressure, flow rate and chemical content in a microfluidic channel. A finite element simulation illustrates the sensitivity of impedance measurements to bubble volume in a channel. Furthermore, prototype chips of various configurations were fabricated and are presented to illustrate the design considerations for different sensor applications. The sensor was tested and experimental results are presented characterizing its use as a pressure sensor. Results on surface modification experiments give evidence to support the extension of the bubble based sensor to use in chemical detection in microfluidic channels.
Development of a Compact and Mobile Scissor Lift to Transfer a Wheelchair User to and From the Deck of a Pool
Authors: Manuel Josh , Clement Phil , Pakulski Erik , Godiciu Robert , Hefzy Mohamed Samir , Nemunaitis Gregory
Published: April 2008

The purpose of this project was to design and construct a unit that will allow an individual using a wheelchair to move herself from the wheelchair to the deck of a pool and vice-versa, independently and as comfortably as possible. A small compact scissor lift was designed and constructed for this purpose. The lift uses one linear actuator to lower the scissor frame to 51/2 inches from the pool deck and raise the frame to the height of the wheelchair. Two twelve-volt rechargeable batteries were used to power the linear actuator. Two 24 inch wheels were added in the rear and two small wheelchairs caster wheels were added to the front of the unit. Locking brakes were added to the rear wheels of the unit to prevent it from moving during transfer. The unit itself functions fully as a manual wheelchair and as a powered lifting device as shown in Figures 1 and 2.
Using MEMS Accelerometers to Improve Automobile Handwheel State Estimation for Force Feedback
Authors: Switkes Joshua P. , Coe Ian A. , Gerdes J. Christian
Published: April 2008

This paper explores the possibility of combining solid state accelerometers with a low resolution position sensor to provide clean estimates of automobile handwheel position, velocity and acceleration for use in force feedback. Typically determining the acceleration and velocity of the handwheel requires differentiating a position sensor such as an encoder or potentiometer. Unless expensive high-resolution sensors are used, this differentiation leads to a noisy signal, requiring significant filtering which leads to significant phase lag. With a direct measurement of acceleration, we circumvent many of the problems associated with differentiation and filtering. This work uses a Kalman filter to combine a pair of MEMS accelerometers with a low-resolution potentiometer to estimate handwheel states. This measurement scheme is effective in this application because of the low frequency nature of the force feedback and because of the structural robustness of the handwheel system. Initial in-vehicle experimental results show the setup can provide smooth acceleration and velocity signals in a moving vehicle.
Tackling the Transition: A Multi-Mode Combustion Model of SI and HCCI for Mode Transition Control
Authors: Roelle Matthew J. , Shaver Gregory M. , Gerdes J. Christian
Published: April 2008

Homogeneous charge compression ignition (HCCI) offers a promising way to improve efficiency and emissions. However, when HCCI is induced by reinducting exhaust gases, less power is produced. A possible solution is to couple HCCI with spark ignition (SI) operation at higher loads. This requires a way to smoothly switch between combustion modes. The authors present a multi-cycle, multi-mode combustion model to aid in understanding and controlling the mode transition. The model captures early ignition and low work after a switch from SI to HCCI. Furthermore, the model reveals a need to coordinate intake and exhaust valve timing to correct the HCCI phase and work. To demonstrate the model, the paper concludes with an example trajectory that maintains constant work and ignition phasing after a switch from SI to HCCI.
Flow Visualization of Flow Pattern Within Aneurysm Induced in Anterior Communicating Artery
Authors: Haida Sayaka , Torisu Akihiro , Kudo Susumu , Yamaguchi Ryuhei
Published: April 2008

In the present paper, the flow structure within the anterior communicating artery (ACoA) with the initial, the progressive, and the developed aneurysm has been visualized by PIV in laminar steady flow. Since the vascular disease such as an aneurysm is apt to occur at the site where the artery bifurcates and joins, the flow pattern is closely related to the initiation and the development of the aneurysm. The ACoA composing the circle of Willis is one of the predilection sites of the cerebral aneurysm. The relation between the flow pattern and the aspect ratio AR (=depth/ neck diameter of aneurysm) is studied by the flow visualization from the viewpoint of hemodynamics.
Post-Deposition Porous Etching of Polysilicon: Fabrication and Characterization of Free-Standing Structures
Authors: He Rihui , Kim Chang-Jing
Published: April 2008

In this paper, we explored the development of porous polysilicon as a free-standing structure in MEMS. Being turned porous by electrochemical porous etching “after” it is deposited on typical insulators, the process is well suited for integration with many processes including typical polysilicon surface micromachining. Free-standing porous polysilicon microstructures have been successfully fabricated. Stress in porous polysilicon thin film, generated in porous etching, can be released by short time annealing at 700°C. Etching rate and Young’s modulus of porous polysilicon are characterized. As a demonstration of the applicability of porous polysilicon in MEMS, two types of self-closed microchannels are fabricated using porous polysilicon as the channel wall.
Fabrication of Three-Dimensional SU-8 Microstructures for MEMS Applications
Authors: Yu Hui , Li Biao , Zhao Yi , Zhang Xin
Published: April 2008

In this paper, a novel method to realize three-dimensional microstructures is presented. The presented technology is based on a direct write technique using a scanning laser system to pattern thick-film SU-8. This technique combines the best features of photolithography techniques in multi-layer processing with the versatility of existing 3D prototyping technologies. It enables laser pulsing spot-by-spot for both in-plane and in-depth processing. The results presented here represent the first step towards the realization of categories of MEMS devices with mechanical, optical, and/or biological functionalities.
A Computational Optimal Control Approach to the Design of a Flexible Rotating Beam With Active Constrained Layer Damping
Authors: Lee Y. C. E. , Fung E. H. K. , Zou J. Q. , Lee H. W. J.
Published: April 2008

In this paper, a computational approach is adopted to solve the optimal control and optimal parameter selection problems of a rotating flexible beam fully covered with active constrained layer damping (ACLD) treatment. The beam rotates in a vertical plane under the gravitational effect with variable angular velocity and carries an end mass. Tangent coordinate system and the moving coordinate system are used in the system modeling. Due to the highly nonlinear and coupled characteristics of the system, a relative description method is used to represent the motion of the beam and the motion equations are set up by using relative motion variables. Finite element shape functions of a cantilever beam [1] are used as the displacement shape functions in this study. Lagrangian formulation and Raleigh-Ritz approach [2] are employed to derive the governing equations of motion of the nonlinear time-varying system. The problem is posed as a continuous-time optimal control problem. The control function parameters are the control gains. The two system parameters are the thickness of the constraining layer and the viscoelastic material layer. The software package MISER3.2, which is based on the Control Parametrization and the Control Parametrization Enhancing Transform (CPET) techniques is used to solve the combined problems. The optimal solution takes the end deflection, control voltage and the total weight into account. Results show that substantial improvements are obtained with ACLD as compared to the passive constrained layer damping (PCLD) treatment.
Singular Superposition/BEM Inverse Technique for Reconstruction of Multi-Dimensional Heat Flux Distributions With Application to Film-Cooling Slots
Authors: Siliety Mahmood , Divo Eduardo , Kassab Alain J.
Published: April 2008

A hybrid singularity superposition/boundary element-based inverse problem method for the reconstruction of multi-dimensional heat flux distributions is developed. Cauchy conditions are imposed at exposed surfaces that are readily reached for measurements while convective boundary conditions are unknown at surfaces that are not amenable to measurements such as the edges of cooling slots. The purpose of the inverse analysis is to determine the heat flux distribution along cooling slot surfaces. This is accomplished in an iterative process by distributing a set of singularities at the vicinity of the cooling slot surface inside a fictitious extension of the physical domain with a given initial strength distribution. A forward steady-state heat conduction problem is solved using the boundary element method (BEM), and an objective function is defined to measure the difference between the heat flux measured at the exposed surfaces and the heat flux predicted by the BEM under the current strength distribution of the singularities. A genetic algorithm iteratively alters the strength distribution of the singularities until the measuring surfaces heat fluxes are matched, thus, satisfying Cauchy conditions. Subsequent to the solution of the inverse problem, the heat flux at the inaccessible surface is computed using the BEM. The hybrid singularity superposition/BEM approach thus eliminates the need to mesh the surface of the film cooling slot and the need to parametrize the heat flux over that surface. Rather, the heat flux is determined in a post-processing stage after the inverse problem is solved. This constitutes a tremendous advantage in solving the inverse problem, particularly in three-dimensional applications.
Evaluation of Residual Thermal Stresses of Fibrous Composites
Authors: Karami G. , Schwingler Eric , Nazari G. H.
Published: April 2008

A micromechanical model for fibrous materials is used for determination of thermoelastic properties and the residual stresses of continuous fiber composites with straight or wavy fibers. The fibrous composite material is assumed to be of periodic type and is composed of circular fibers distributed within the matrix. Following a thermoelastic finite element analysis of the unit cell under a temperature change, the stress and strain components are volume-averaged to obtain the continuum components of the thermal stress and strain at a typical material point represented by the unit cell. The coefficient of thermal expansion (CTE) is then measured using the constitutive relations. In the numerical examples, the fiber is assumed transversely isotropic and the matrix is taken as an isotropic material. The composite is therefore, transversely isotropic with straight fibers, but becomes orthotropic for the case of wavy fibers. The thermal residual stresses generated per unit temperature change are studied in detail by volume averaging over slices (to be called sub-volumes) of the representative volume element (RVE) along the length of the fiber. The sub-volume averaging scheme shows the variation of the internal stresses and strains within the RVE. It is shown the created thermal stresses will play a significant role on the composite failure.
Finding an Optimal Set of Cutter Radii for 2D Pocket Machining
Authors: Nadjakova Irena , McMains Sara
Published: April 2008

We describe an approach to finding an optimal (within a requested approximation ratio) set of cutter radii for machining a given 2-dimensional pocket. We do not assume that there is a pre-determined set of cutter radii to choose from or a predetermined number of cutters to use. Given an initial set of cutters to choose from, we derive an upper bound on the approximation ratio of what is achievable choosing from this set compared to the ideal set. We then use this bound to subdivide the intervals between the given radii until the requested approximation ratio is achieved. We also look at the machinable area as a function of the tool radius. We show that this area is continuous everywhere, except at a certain set of radii determinable by constructing the Voronoi diagram of the pocket. This lets us avoid subdividing the intervals around the points of discontinuity, improving both running time and the size of the output tool set.
Design for Crashworthiness of Vehicle Structures via Equivalent Mechanism Approximations and Crush Mode Matching
Authors: Hamza Karim , Saitou Kazuhiro
Published: April 2008

This paper presents a 3D extension to our previous work on vehicle crashworthiness design that utilizes “equivalent” mechanism models of vehicle structures as a tool for the early design exploration. An equivalent mechanism (EM) is a network of rigid links with lumped masses connected by prismatic and revolute joints with nonlinear springs, which approximate aggregated behaviors of structural members during crush. A number of finite element (FE) models of thin-walled beams with typical cross sections and wall thicknesses are analyzed to build a surrogate model that maps the beam dimensions to nonlinear spring properties. Using the surrogate model, an EM model is optimized for given design objectives by selecting the nonlinear springs among the ones realizable by thin-walled beams. The optimum EM model serves to identify a good crash mode (CM), the time history of collapse of the structural members, and to suggest the dimensions of the structural members to attain it. After the optimization, the FE model of an entire structure is “assembled” from the suggested dimensions, which is further modified to attain the good CM identified by the optimum EM model. A case study of a 3D vehicle front half body demonstrates that the proposed approach can help obtain good designs with far less computational resources than the direct optimization of a FE model.
Performance Similarity Based Method for Enhanced Prediction of Manufacturing Process Performance
Authors: Liu Jianbo , Djurdjanovic Dragan , Ni Jun , Lee Jay
Published: April 2008

Full realization of all potentials in predictive and proactive maintenance highly depends on the accuracy of long-term predictions of the remaining useful life of manufacturing equipment. Parametric linear prediction techniques, such as Autoregressive Moving Average modeling (ARMA), are routinely used to trend and predict future behavior of any time series, but are frequently not appropriate for long-term prediction because of the highly complicated and non-stationary nature of manufacturing processes. In this paper, we propose a novel method that is capable of achieving high long-term prediction accuracy by comparing signatures from two degradation processes using measures of similarity that form a Match Matrix. Through this concept, we can effectively include large amounts of historical information into the prediction of the current degradation process. Similarities with historical records are used to generate possible future distributions of features, which is then used to predict probabilities of failure over time by evaluating overlaps between predicted feature distributions and feature distributions related to unacceptable equipment behavior. Experimental results show that the proposed method results in a significant improvement of long-term prediction accuracy compared with ARMA modeling-based prediction.
Electric-Field-Driven Fluid Flow Around Nano Particles
Authors: Chung Jaehyun , Lee Kyong-Hoon , Ruoff Rodney S. , Lee Junghoon
Published: April 2008

Recently there has been significant progress in assembling an array of individual carbon nanotubes (CNTs) on microfabricated electrodes using the Composite Electric-field Guided Assembly (CEGA) method. This technology allows for integrating individual nano components with micro/nano systems, and should find application in areas such as sensors and NEMS devices. For realizing this as a viable technology, it is crucial to understand the electric-field-driven flow around the nanostructures being deposited. We previously discovered that the flow patterns that are present can lead to deposition of a periodic array CNTs. Here, we present recent experimental observations and the results of modeling/simulation on the electric-field-driven flow around CNTs. The results suggest that this method of assembling nanostructures be used for integration with an accuracy approaching tens of nanometers.
Fabrication of a Micro/Nano Integrated Roughened Structure Using Nanosphere Lithography (NSL)
Authors: Thangawng Abel L. , Lee Junghoon
Published: April 2008

This paper presents a fabrication technology to create a double roughened PDMS structure for a superhydrophobic surface. The fabricated surface has many application potentials, including on-chip micro liquid processor and water repellent coating. Similar structure can be found in nature on a lotus leaf (Fig. 1.) Due to its superhydrophobic surface, lotus leaf repels water and in the process performs self-cleaning [1]. In this paper, we show the combination of Nanosphere Lithography (NSL), plasma etching, and molding technique to create the micro/nano integrated double structure using PDMS. Also described is the design procedure and experimental results for the double-structured superhydrophobic surface.
Bio/Chemical Sensing by Thin Membrane Transducers
Authors: Rodriguez Raquel , Chung Jaehyun , Lee Kyonghoon , Lee Junghoon
Published: April 2008

This paper reports the successful design, fabrication and testing of thin membrane transducers that can monitor biochemical reactions through chemical-mechanical transduction. Two different membrane materials were chosen: Silicon Nitride (Si3N4) and polydimethylsiloxane (PDMS). In both configurations, a specific molecular binding event on the surface of the diaphragm causes a deflection detected by the capacitance change across a gap between the membrane and a substrate. Preliminary tests presented in this paper demonstrate in-situ monitoring of the formation of a self assembled monolayer (SAM) and biotin-streptavidin binding. The reported mechanism is the first demonstration of a capacitive chemical sensor using a membrane element.
Design of Micro-Gripper With Topology Optimal Compliant Mechanisms
Authors: Huang Shyh-Chour , Chiu Chien-Ching
Published: April 2008

The objective of this paper describes a new method to design a micro-gripper. In the paper, we use compliant mechanism actuated by micro combined V-shape electrothermal actuator to design a microgripper that the claw can clip the micro object. The compliant mechanism employs flexible to generate movement without any hinge; therefore, it is suitable for MEMS manufacture. The design of micro-gripper is accomplished in compliant mechanism with topology optimum and solved by sequential linear programming (SLP) methods. The design considerations, the analysis method, and the design results are discussed.
Condition Monitoring of an Electrohydraulic Position Control System Using Artificial Neural Networks
Authors: Pollmeier K. , Burrows C. R. , Edge K. A.
Published: April 2008

This paper investigates the condition monitoring of a servo-valve-controlled linear actuator system using artificial neural networks (NNs). The aim is to discuss techniques for the identification of failure characteristics and their source. It is shown that neural networks can be trained to identify more than one fault but these are larger and require more training patterns than networks for single fault diagnosis. This leads to much longer training times and to problems with scaleability. Therefore a modular approach has been developed. Several networks were trained each to identify an individual fault. The parallel outputs of these nets were then used as inputs to another network. This additional network was able to identify not only the correct faults but also the actual fault levels.
Stereoscopic PIV Measurements of Flow in a Model Left Ventricle with Prosthetic Valves
Authors: Taylor Donal J. , Quinlan Nathan J. , Eaton John A.
Published: April 2008

Fluid dynamic phenomena are fundamentally important in the function of the heart, and consequently in the design of prosthetic heart valves. Experimental study is complicated by the strongly unsteady and three-dimensional character of flow in the chambers and valves of the heart, and the difficulty of access for instrumentation, even in a laboratory model. This paper describes the novel application of Stereoscopic Particle Image Velocimetry (SPIV) to measure the three-component velocity vector field in a model of the left ventricle with mechanical prosthetic valves. The results illustrate key functional differences between the two prosthetic mitral valves tested. These experiments demonstrate the powerful capability of SPIV as a tool for investigation of the complex flows which occur in biology and medicine.
Effects of Particle Rotation on the Hydrodynamic Modeling of Segregation in Gas-Fluidized Beds
Authors: Sun Jin , Battaglia Francine
Published: April 2008

A multi-fluid Eulerian model has been improved by incorporating particle rotation using a simple kinetic theory for rapid granular flow of slightly frictional spheres. The model was implemented without changing the current kinetic theory framework by introducing an effective coefficient of restitution to account for additional energy dissipation due to frictional collisions. Simulations with and without particle rotation were performed to study the bubble dynamics in a monodispersed gas-solid fluidized bed and the segregation phenomena in a bidispersed gas-solid fluidized bed. Results were compared between simulations with and without particle rotation and with corresponding experimental results. It was found that the multi-fluid model with particle rotation better captures the bubble dynamics and time-averaged bed behavior. The model predicted lower segregation percentages and a lower segregation rate due to increased bubble intensity.
Scanning Probe Microscopy of Carbon Nanotube Electronic Devices
Authors: Zhou Jianhua , Shi Li
Published: April 2008

Electron transport and dissipation mechanisms in single-walled carbon nanotube electronic devices are intriguing. In the past, electrostatic force microscopy and scanning thermal microscopy methods have been employed to obtain respectively the voltage and temperature profiles in carbon nanotube electronic devices. The measurement results have suggested weak electron-acoustic phonon scattering at low bias and intense optical phonon emission at high bias. However, because the thermal probe was in direct contact with the nanotubes during thermal imaging, the probe could disturb charge transport. Further, it was difficult to quantify the thermal contact between the probe and the nanotube, making it difficult to quantify the actual temperature rise in the device. We have recently overcome these problems by coating the nanotube device with a 5–10 nm thick polystyrene film. The ultra-thin uniform coating can effectively protect the nanotube device during thermal imaging without reducing the signal level. It can potentially allow us to quantify the temperature rise of the nanotube devices by calibrating the thermal probe using a nanometer scale resistance thermometer covered by the same coating. Our recent results reveal diffusive and dissipative charge transport in a possibly double wall carbon nanotube with a semiconducting outer wall. We have also observed uniform heat dissipation in a metallic single-walled carbon nanotube at an applied bias above 0.2 V. Measurements on metallic and semiconducting single wall carbon nanotubes of different lengths are currently underway in order to improve our understanding of the transport and dissipation mechanisms in carbon nanotube electronics at low biases.
Formation of Through-Silicon-Vias by Laser Drilling and Deep Reactive Ion Etching
Authors: Hon Ronald , Zhang Shawn X. D. , Lee S. W. Ricky
Published: April 2008

The focus of this study is on the fabrication of through silicon vias (TSV) for three dimensional packaging. According to IPC-6016, the definition of microvias is a hole with a diameter of less than or equal to 150 μm. In order to meet this requirement, laser drilling and deep reactive ion etching (but not wet etching) are used to make the microvias. Comparisons between these two different methods are carried out in terms of wall straightness, smoothness, smallest via produced and time needed for fabrication. In addition, discussion on wafer thinning for making through silicon microvias is given as well.
Influence of In-Plane Modes of a Rotor to Brake Noise
Authors: Lee Heewook
Published: April 2008

In the effort of improving brake noise, recent studies showed increasing encounters with in-plane modes of a rotor for a root cause of a brake noise. Although studies about in-plane modes of a rotor or a disc have been done a lot, a study about the influence of in-plane modes to brake noise has rarely been done. This paper explored the relationship between unstable eigenvalues and rotor mode shapes, focusing on explaining why unstable eigenvalue excited by in-plane modes behaved differently from one caused by out-of-plane modes. Complex eigenvalue analysis was used to assess the instability of a brake corner. This paper showed the way of analytically calculating the sensitivities of unstable eigenvalues about out-of-plane and inplane modes of a rotor. By using the results of sensitivity analysis, it was first discovered that one of the rotor in-plane doublet modes has the opposite sign to the other in the real parts of the sensitivity, and this precludes eliminating the unstable eigenvalues, which are dominated by rotor in-plane modes. However, it was also found that the corresponding unstable eigenvalues could be eliminated if we could separate the frequencies of these modes. Frequency separation of in-plane doublet modes due to disk rotation was examined.
System Architecture Analysis of a Hydrogen Enhanced IC Engine
Authors: Smaling Rudolf M.
Published: April 2008

This paper presents a quantitative analysis of potential system architectures for a hydrogen enhanced spark ignited, homogeneous charge, internal combustion engine. The proposed concepts all revolve around a plasma fuel reformer, a compact, fast response partial oxidation fuel reformer that can real-time convert a fraction of the fuel stream to the engine into a mixture of hydrogen, carbon monoxide and nitrogen. The intent of this work was to analyze the different engine-reformer architecture options in the context of the objectives of fuel consumption, engine out NOx emissions and system add-on cost.
Imperfection Sensitivity of Laminated Cylindrical Shells by Full and Initial Post-Buckling Analyses
Authors: Sheinman Izhak , Jabareen Mahmood
Published: April 2008

Laminated cylindrical shells are already commonly used in structural engineering, and their buckling and post-buckling behavior is of vital importance in the design of such structures. The validity of linear buckling analysis in this context, has been questioned because of the discrepancy observed between theoretical prediction and test results. The cause of this discrepancy is the fact that the nonlinear behavior of shell-like structures is generally characterized by a limit point rather than by a bifurcation point. For such structures, the load-carrying capacity depends on the level of imperfection (hence the concept “imperfection sensitivity”). The motivation is, therefore, to reduce the sensitivity rather than preventing the imperfection. For that purpose insight into the post-buckling state is called for.
Optimal Integration of a Microturbine-Absorption Chiller Cooling, Heating and Power System for Highest Overall CHP System Value
Authors: Sahm Michael K. , Zhang Jifeng , Wagner Timothy , Jung Sunghan
Published: April 2008

System level integration of an electrical power generating prime mover with a waste heat recovery thermally activated cooling technology is analyzed. Component and system level metrics for quantifying efficiency, performance and value are defined. Trades between component level metrics and system level metrics are performed and optimal integrated cooling, heating and power configuration characteristics and value sensitivity to integration parameters are quantified. Methods developed are extensible to other integrated prime mover and thermally activated technology system approaches.
Laminar Heat Transfer in a Parallel Plate Channel With Solid and Porous Baffles
Authors: de Lemos Marcelo J. S. , Santos Nicolau B.
Published: April 2008

Simulations are presented for laminar flow in a channel containing fins made with solid (impermeable) and porous materials. The equations of mass continuity, momentum and energy are written for an elementary representative volume yielding a set of equations valid for the entire computational domain. These equations are discretized using the control volume method and the resulting system of algebraic equations is relaxed with the SIMPLE method. The presented numerical results for the friction factor f and the Nusselt number Nu were compared with available data indicating that results herein differ by less than 5% in relation to published results. Further simulations comparing the effectiveness of the porous material used showed that no advantages are obtained for using low porosity baffles in the laminar flow regime.
Meeting Human Needs While Reducing Human Drudgery
Authors: Tesar Delbert
Published: April 2008

In the late 1400’s, Leonardo da Vinci advised his future readers to study the science of machines to reduce the burden (drudgery) on humanity. Today, the question remains—what technologies can best meet the needs of mankind? This paper will outline the ability of the discipline of mechanical engineering to satisfy a spectrum of these needs and its potential to match the excitement and vitality of its neighboring disciplines (electronics, computer science, etc.). First, a representative selection of needs will be described along with a listing of technologies (present and future) that may be associated with the discipline of mechanical engineering. Then, a matrix of these needs and technologies will be used to establish the relative importance of the discipline’s development capacity and to prioritize five possible future areas for development of multi-disciplinary programs. Having done so, an example of a near-term utilization of these technologies (fully integrated and cost effective fettling cells) will be described which could dramatically reduce human drudgery associated with value-added manufacturing.
Considerations for Planning and Running Educational Engineering Contests
Authors: Bedore Daniel B. , Crivelli Paul , Shah Nip
Published: April 2008

Educational goals and other requirements to successfully run design contests for university engineering students are discussed. The authors held human powered submarine design contests and races in Escondido, California in the summers of 2000, 2002 and 2004. These events were specifically designed to expose university engineering students to the types of decisions and processes an engineer in industry would face 5–10 years after receiving a bachelor’s degree in engineering. In building a submarine for this contest, students gained technical expertise in conceptual and detail design and manufacturing, experience in teamwork and time management, and exposure to gaining funding and controlling expenditures. At the contest, oral presentations simulate industrial final design reviews, and races simulate functional tests and demonstrations for customers. Lessons and examples drawn from planning and running HPS2000, HPS2002, and HPS2004 are included and may be useful to persons planning similar educational engineering contests, and to contestants in such events.