bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Surface Roughness by Laser Light Scatter Using Flexible Microcontroller
Authors: Moslehpour Saeid , Shetty Devdas , Cloutier Greg , Campana Claudio
Published: May 2009

This paper presents the development of a non contact surface roughness measurement instrument and its modification from a pc based system to a standalone system. Surface roughness is a measure of localized small-scale height variations or imperfections on the surface of a material. The measurement parameter of surface roughness is described as roughness number, Ra which is the average roughness expressed in micro scale. The type of surface finish under study is created by grinding applications. This surface must meet a specified pre-determined finish. One method used for non-contact measurement of an engineering surface is to measure the back-scatter of a laser light source. The amount of back-scatter is directly proportional to the Ra value [1] [2]. One drawback to pc based system is that it is not portable. A computer handles data acquisition and provides a user interface. The inspection probe is attached to the computer via a limited length of wire. In an industrial setting, it would be more efficient and flexible to bring the inspection probe to the surface in question rather than to bring the surface to the inspection probe. The procedure and the design described in this paper will eliminate the need for the wire tether and the computer altogether. The functionality for both data acquisition and user interface will be replaced by an embedded system. This embedded system will consist of a microcontroller, a multichannel analog to digital converter, an Liquid Crystal Display (LCD) and a keypad input device.
A Proposed Lexicon for Class Definition in a Product Lifecycle Model
Authors: Lingo Lowell E. , Roy Utpal
Published: May 2009

Commonly used terms such as form, function, and behavior often take on varying definitions in the literature related to product design and development. This is especially true as the point of reference moves through various stages of development from conceptual design, through product disposal. This can become problematic from the standpoint of interpretation and implementation when an information model is being created that is intended to be useful to a product throughout its entire lifecycle. A product changes throughout its useful life, so a lifecycle model of a product must also be dynamic and able to grow and age with it. If this is to be the case, descriptive terms and definitions should be specific and retain their definition throughout the life of the model. In this paper, we attempt to select a set of terminology that can be uniquely descriptive of the classes needed to define a product lifecycle model. Terms such as form, function, affordance and behavior are defined within a hierarchy of a product’s lifecycle development. Terminology as presented in this context becomes less ambiguous. An example of a home-shop built pendulum clock serves to illustrate the utility of this new design lexicon. The terminology outlined here may not be optimal and significant additions and alterations may be justifiably suggested; but it is hoped that this paper will begin a dialogue eventually resulting in the elimination of much ambiguity in product modeling terminology.
An Analysis of Laminated Piezoelectric Infinite Plate for Broadband Biomedical Ultrasound Transducer Design
Authors: Cortes Daniel H. , Mukdadi Sam M.
Published: May 2009

This work investigates the use of frequency spectrum analysis of waveguide propagation in multi-layered anisotropic piezoelectric transducers. A semi-analytical finite-element analysis (SAFE) is used to model the transducer as a piezoelectric infinite plate. Dispersion curves, group velocities and displacement frequency spectra can be obtained for any multilayered piezoelectric plate. Stress-free boundary conditions were assumed for all analyses. Results for open and closed circuit boundary conditions were analyzed. Zero-Group-Velocity (ZGV) frequencies of high-order waveguide modes were observed to provide multi-resonant displacement frequency spectrum. Comparison of numerical and experimental results shows a good agreement between peak and off-peak values of the displacement spectrum. Results showed that optimization of layered structure may provide an efficient means for generating multi-thickness (ZGV) waveguide modes, thus increasing the bandwidth of harmonic ultrasound transducers for contrast imaging.
Regime Switching Issues and Criteria for Coupled Static-Dynamic Atomistic Methods
Authors: Medyanik S. N. , Guleryuz E.
Published: May 2009

Coupled static-dynamic atomistic method may be used for coarse graining time in temporal multi-scale atomistic modeling of nano-mechanical problems. This approach can be especially effective for mechanical processes that consist of two distinct phases: the slow phase when the system resides in one local energy minimum and the fast phase associated with a rapid transition from one meta-stable state to another. In this case, the slow phase can be effectively modeled using static energy minimization technique, while the fast phase corresponding to the state transition event may be modeled dynamically. In this case, dynamic modeling is necessary to capture the dynamic effects, such as thermal and inertial, that can not be accounted for in static modeling. One of the major issues of this type of method is to determine when the transitions between the two regimes have to be done. In this presentation, issues of switching between the static and dynamic regimes are outlined and criteria that can be used for effective switching between the two regimes are proposed. In particular, a dynamic-to-static switch based on the kinetic energy and static-to-dynamic switch based on the potential energy are discussed.
Effects of Chemical Kinetics on Concurrent-Flow Flame Spread Rates Over Solids: A Comparison Between Buoyant Flow and Forced Flow Cases
Authors: Hsu Sheng-Yen , T’ien James S.
Published: May 2009

In the present study, detailed numerical models with a one-step finite-rate chemical reaction are employed to investigate the kinetic rate effect (through the variation of the pre-exponential factor) on concurrent flame spread rates. It is found that flames in forced-flow are less sensitive to the change of kinetics than flames in buoyant-flow; and narrow samples are more sensitive to the change of kinetics compared with wide samples. The rate of chemical kinetics affects the flame spread rates through its influence on the flame and the flow structures. For buoyant flames, gravity-induced velocity is affected by the flame temperature which is sensitive to kinetics. Hence the variation of upward spread rate is greater with the rate change of kinetics. This paper presents the details of a systematic investigation and comparison of the flame structures and the influence of gasphase chemical kinetics on several different types of concurrent spreading flames.
Mapping of Regional Cancerous Tissue Mechanical Property Changes Using Harmonic Motion Imaging
Authors: Maleke Caroline , Luo Jianwen , Pelegri Assimina A. , Konofagou Elisa E.
Published: May 2009

Mechanical changes in breast tissues as a result of cancer are usually detected through palpation by the physician and/or self examination. However, physicians are unable to palpate most masses under 1 cm in diameter and microscopic diseases. The goal of our study is to introduce the application of the Harmonic Motion Imaging (HMI), an acoustic radiation force technique, for reliable sensitive tumor detection and real-time monitoring of tumor ablation. Here, we applied the HMI technique using a single-element Focused Ultrasound (FUS) transducer. Due to the highly localized and harmonic nature of the response, the motion characteristics can be directly linked to the regional tissue modulus. In this experiment, a confocal transducer, combining a 4.68 MHz therapy (FUS) and a 7.5 MHz diagnostic (pulse-echo) probe, was used. The FUS beam was further modulated by a low AM continuous wave at 25 Hz. A pulser/receiver was used to drive the pulse-echo transducer at a Pulse Repetition Frequency (PRF) of 5.4 kHz. The radio-frequency (RF) signals were acquired using a standard pulse echo technique. The intensity amplitudes of the FUS beam at the focus (Ispta) were 231 W/cm2 for tumor detection and 1086 W/cm2 for FUS ablation. An analog bandpass filter was used to remove the spectrum of the FUS beam prior to displacement estimation. The resulting axial tissue displacement (i.e., HMI displacement) was estimated using an RF-based speckle tracking technique based on 1D cross-correlation. For tumor mapping, a harmonic radiation force was applied using a 2D raster-scan technique. The 3D HMI image was obtained by combining multiple 2D planes at different depths. The 2D and 3D HMI images in ex vivo breast tissues could detect a benign tumor (2×5×5mm3) surrounded by normal tissue, and a malignant tumor (8×7×5mm3) embedded in glandular and fat tissues. For FUS therapy, temperature measurements and RF signals were acquired during thermal ablation. HMI images during FUS ablation showed lower displacements, indicating thus tissue hardening due to lesion formation at temperatures higher than 50°C. A finite-element model (FEM) simulation was also used to analyze the findings of the experimental results. In conclusion, this technique demonstrates feasibility of the HMI technique for tumor detection and characterization, as well as real-time monitoring of tissue ablation based on the associated tissue elasticity changes.
The Effect of Surface Tilt on Nanoindentation Results
Authors: Saket Kashani Mahdi , Madhavan Vis
Published: May 2009

The effect of surface tilt on results of nanoindentation tests is studied for Berkovich, cube corner and conical indenters. The true projected areas are calculated as a function of tilt angle and orientation using the exact three dimensional geometry of each indenter. The true area is compared with the area when there is no tilt and the resulting error in hardness and modulus are discussed. It is found that the error increases with increasing tilt angle, and magnitude of the error increases as the equivalent cone angle of the indenter increases.
Hybrid Fiber Fabrication Using an AC Electric Field and Capillary Action
Authors: Yeo Woonhong , Chung Jae-Hyun , Lee Kyong-Hoon , Liu Yaling , Liu Wing Kam
Published: May 2009

We present a novel hybrid fiber fabrication method for nanostructured hybrid-materials, using an AC electric field and capillary action. Through this fabrication process, hybrid fibers composed of single walled carbon nanotubes (SWCNTs) and silicon carbide (SiC) nanowires were systematically manufactured. It was demonstrated that both diameter and length of hybrid nanofibers could be controlled by manipulating parameters, such as the mixing ratio of SWCNTs to SiC nanowires, concentration of solution, immersion time, volume of solution, and withdrawal rate. In the fabricated hybrid fibers, the SiC nanowires functioned as a structural frame (host filler materials), while SWCNTs were employed for their extraordinary mechanical and electrical properties as a binder or net. Using this method, the fabrication speed of the hybrid fiber was increased by 20 fold compared to the existing method[1]. According to the simulation and modeling results, the fibers are formed by the following three steps; (1) nanowire bridge formation by dielectrophoresis in solution (2) nanowire fiber formation by compression due to capillary action (3) alignment by the torque due to the capillary action. The proposed processing technology may provide an ample opportunity for fabricating a long hybrid-nanofiber.
Geometric Optimization of van der Pauw Structure Based MEMS Pressure Sensor
Authors: Law Jesse , Cassel Robert , Mian Ahsan
Published: May 2009

This paper characterizes a piezoresistive sensor under variations of both size and orientation with respect to the silicon crystal lattice for its application to MEMS pressure sensing. The sensor to be studied is a four-terminal piezoresistive sensor commonly referred to as a van der Pauw (VDP) structure. In a recent study, our team has determined the relation between the biaxial stress state and the piezoresistive response of a VDP structure by combining the VDP resistance equations with the equations governing silicon piezoresistivity and has proposed a novel piezoresistive pressure sensor. It is observed that the sensitivity of the VDP sensor is over three times higher than the conventional filament type Wheatstone bridge resistor. With MEMS devices being used in applications which continually necessitate smaller size, characterizing the effect of relative size and misalignment on the sensitivity of the VDP sensor is important. It is determined that the performance of the sensor is strongly dependent only on the longitudinal position of the sensor on the diaphragm, and is relatively tolerant of other errors in the manufacturing process such as transverse position, sensor depth, and orientation angle.
Comprehensive Modeling Study on Fuel Gas Reburn in an Opposed Wall Fired Boiler
Authors: Nguyen Q. H. , Zhou W. , Xu G. , Swanson L. W. , Moyeda D. K.
Published: May 2009

GE conducted engineering and modeling studies to evaluate the feasibility of applying gas reburn technology on Eskom’s Majuba Unit 5 (710 MWe). The key objective of the study was to evaluate the technical and economical feasibility of utilizing a low-calorific fuel gas as a reburn fuel. The fuel gas is produced from an underground gasification process of the Majuba coal deposits, which are difficult to mine. The studies include: (1) develop a conceptual gas reburn injection system that will serve as a basis for the boiler performance impact and economic studies, (2) evaluate mixing performance of the gas reburn system and evaluate impacts of gas reburn on the furnace thermal and species profiles using computational fluid dynamics (CFD) modeling, (3) evaluate impacts of gas reburn on the boiler thermal performance using heat transfer modeling, (4) evaluate NOx reduction potential of the gas reburn systems, and (5) evaluate the economical feasibility of applying gas reburn technology to the Majuba boiler. The study indicates that the proposed reburn fuel and OFA injection systems will provide adequate mixing and reasonable residence time for the reburn application. The potential impacts on boiler performance with injection of the low-calorific fuel gas include the flue gas flow rate, attemperation rate and ID fan capacity. The detailed modeling approach and results are presented in this paper.
A Python Software Module for Automated Identification of Systems Modeled With the Transfer Matrix Method
Authors: Krauss Ryan W. , Book Wayne J.
Published: May 2009

This paper presents a software module for intelligently automating system identification, especially for dynamic systems modeled with the transfer matrix method (TMM). The TMM is a modeling approach that represents the elements of a dynamic system with matrices that transfer a vector of states from one end of the element to the other. A system model is formed by multiplying element transfer matrices together to form a system transfer matrix. The TMM is capable of modeling continuous elements without discretization. Existing system identification packages cannot handle continuous models of distributed-parameter systems and therefore cannot be used to identify TMM models. This paper presents a Python software module for TMM modeling that includes integrated system identification capabilities. This software module intelligently automates the system identification process, significantly reducing the time and effort required for system identification and eliminating errors stemming from low-level details.
Self-Powered Wireless Sensor Balls for Homeland Security
Authors: Yu Jaewook , Chun Woohyung , Nejat Goldie , Noel Eric , Tang K. Wendy
Published: May 2009

In this paper, the development of affordable self-powered wireless sensor balls is proposed for environmental monitoring. Depending on the area of interest, multiple balls can be either thrown or rolled from a distance into the surrounding area of interest or placed beside the object of interest, and send sensory information back to a central base station, i.e., a laptop, for sensor fusion and processing. In order to achieve fast and robust deployment, reliable data delivery, and smart power management, the paper focuses on the potential wireless network and energy harvesting scheme of the balls. In particular, to support a large number of sensor balls, we show that shortest path routing is essential in minimizing network latency and guarantee timely delivery of critical and emergency information. Furthermore, a vibration-based electromagnetic energy harvesting technique is investigated to capture the energy from the motion of the balls. Experimental results demonstrate the potential development of a network of autonomous self-powered wireless sensor balls.
Re-Inventing Drawing Courses for Mechanical Engineers
Authors: Rodriguez Carlos F. , Polanco Ana Maria
Published: May 2009

Traditionally, drawing courses in engineering curricula have been devoted to develop drawing abilities in students. In recent years, many questions about their significance in young engineer’s education have been formulated, and many institutions decided to reduce the number of drawing courses or even to eliminate them from the compulsory syllabus. This paper presents a different concept to deal with the drawing courses in mechanical engineering education. It is based on the fundamental purpose of drawing for engineers: to allow the communication of technical ideas. The new course is focused on geometrical conception and technical specification of objects and assemblies. We propose a project based methodology in order to reinforce the links between geometrical design, drawing, manufacturing, and assembly. The structure of the course is presented including examples of class activities and proposed projects. Results of the implementation of this new course are also discussed.
Electrical and Thermal Conductivities of Carbon Nanotube-Epoxy Composites: Modeling and Characterization
Authors: Seidel Gary D. , Bisrat Yordanos , Lagoudas Dimitris C.
Published: May 2009

The motivation of this work is to develop adhesive layers from epoxy based nanocomposites using carbon nanotubes (CNTs) for use in thermal management applications in microelectronic devices. The focus of the experimental characterization is to measure the enhancement of electrical and thermal conductivities of polymeric nanocomposites consisting of XD grade CNTs as a function of a range of weight percentages. Comparison of the results obtained for these CNT-epoxy nanocomposites are made with other nanocomposite results from the literature and with initial micromechanics modeling efforts. The micromechanics model is centered on the use of the generalized self-consistent composite cylinders method in conjunction with multi-phase averaging methods, and is employed to predict the effective electrical and thermal properties of nanocomposites with randomly oriented CNTs, where the hollow nature of the CNTs and the possible presence of interphase regions precludes the direct use of the Eshelby solution. Interphase regions are identified to phenomenologically introduce nanoscale effects such as the thermal Kapitza resistance and electron hopping. It is observed that, as a result of the different character of the nanoscale effects associated with electrical and thermal properties, nanotube-polymer nanocomposites demonstrate a percolation behavior in electrical conductivity not observed in thermal conductivity.
Parameter Estimation of the Human Ankle in the Transverse Plane During the Initiation of a Turn
Authors: Glaister Brian C. , Schoen Jason A. , Orendurff Michael S. , Klute Glenn K.
Published: May 2009

In order to better rehabilitate lower limb amputees, prostheses need to provide torsional control in the transverse plane to facilitate turning. When designing prostheses, it is helpful to create mechanical models of biological behavior. This paper presented a model of transverse plane ankle function during turn initiation, the first step of a multi-step turning sequence. Motion capture data was collected from ten subjects performing left turns. Four states of stance phase were chosen based on distinct events in the power curve. Passive elements were chosen to model the ankle in each state for turn initiation. The ankle was observed to act as a quadratic torsional spring and a linear torsional damper in State 1 and as linear torsional springs in States 2–4. Damping was found only in State 4 where it was modeled as a linear torsional damper. Turn initiation stiffness coefficients were similar to straight walking in State 1 and 2, but differed in States 3 and 4. This indicates that the turn begins in the middle of stance phase when viewed in terms of transverse plane ankle function. The results of this study should assist with the mechanical design and control of a biomimetic torsional prosthesis by suggesting a finite state control system and by providing the stiffness and damping coefficients to be controlled.
On Nonlinear Dynamics of Simplified Brake Dynamical Systems
Authors: Luo Albert C. J. , Thapa Sagun
Published: May 2009

In this paper, nonlinear dynamics mechanism of a brake system under a periodical excitation is investigated. The corresponding motion for such a system is described. The conditions for motion switching and sliding on the boundary are developed. Based on the discontinuous boundaries of motion, the basic mappings are introduced and the mapping structures for periodic motions are developed. Illustrations of periodic motions will be presented from analytical predictions.
Design and Evaluation of Multi-Axis Vibration Shaker Concepts
Authors: Mauer Georg F.
Published: May 2009

Multi-axis shaker systems for the mechanical testing of components up to 2 kHz generally exhibit multiple resonances within their operating range of frequencies. Equipment testing requires the control of the shaker’s power density spectra in all axes of shaker motion. The paper describes the results of a 4-year ongoing project to develop a predictive model of 6-axis shaker dynamics, and presents a comparison between the computer model and a series of experiments on a small 6-DOF electrodynamic shaker, employing computed and experimentally recorded power density and coherence spectra, as well as modal analyses. Modifications of the shaker’s structural stiffness and damping are shown to be correctly predicted and validated by the experiments.
Ion Diffusion Upon Concentrations in Open Nanofluidic Channels
Authors: Chang Chen-Ling , Bai John Guofeng , Lee Kyong-Hoon , Chung Jae-Hyun , Liu Yaling , Liu Wing Kam
Published: May 2009

The ion flow in nanochannels is investigated by using nanochannels in an open configuration that allows the direct observation of fluid diffusion through an optical microscope. An “open nanochannel” is a channel with the top open to air such that fluidics can be introduced from both the entrance and the top of the channels. The experimental results showed that the diffusion length of the potassium chloride and phosphate buffer decreased with their concentration. The observed behaviors were analyzed by the contact angle variation due to the electrowetting phenomena involving the interaction between electrical double layer and counter-ions in the solution.
The Use of Tele-Operated Cranes for Advanced Controls Education
Authors: Singhose William , Vaughan Joshua , Danielson Jon , Lawrence Jason
Published: May 2009

Cranes provide an excellent platform for teaching advanced controls. They have a simple pendulum-type oscillation that is useful for demonstrating basic control methods. However, cranes also have additional dynamic effects such as motor dynamics, velocity limits, and nonlinear slewing dynamics that make them well suited for advanced study. If the cranes are made remotely operable, then students can also study tele-operation and control of systems with time delays. An advanced control design course taught at the Georgia Institute of Technology has integrated tele-operated cranes into both the lecture and laboratory exercises. The laboratories lead the students through the use of two tele-operated cranes. The lab component of the course culminates with a five-week team project in which the students design and implement their own research project on the cranes. The primary goal of using the cranes is to provide hands-on experiences in implementing advanced controllers on real systems. This paper describes the cranes and the complementary curriculum.
Use Direct Cyclic and Sub-Modeling Approach to Analyze Solder Joint Fatigue Reliability
Authors: Zheng Tieyu , Du Zhen-Zhong
Published: May 2009

Temperature change under the operating condition of an electronic product often leads to stress reversals and the accumulation of inelastic energy at the solder joints inside the packaging, resulting in the initiation and propagation of cracks in the solder joints. It is desired to predict the critical location of ball grid array (BGA) undergoing low-cycle fatigue and the fatigue life of the critical solder joints numerically to assess the development risks and guide the product design. This paper presents an approach by combining the direct cyclic method implemented by Abaqus and the sub-modeling method to achieve both goals with better computing efficiency than the traditional global-local approach.
Design and Analysis of a Resonating Free Liquid-Piston Engine Compressor
Authors: Riofrio Jose´ A. , Barth Eric J.
Published: May 2009

This paper presents the design and simulation of a resonating free liquid-piston compressor (FLPC) equipped with a separated combustion chamber. The FLPC is a proposed device that utilizes combustion of a hydrocarbon fuel to compress air into a high-pressure supply tank, thus potentially serving as a portable power supply candidate for untethered pneumatic systems of human-scale power. The energetic merits of the FLPC concept have been outlined and demonstrated in previous work, and this new design aims at meeting its intended power density, all while maintaining an adequate energy density in a compact and simple device. In this new design, the free “piston” consists of a slug of water (or another incompressible fluid) trapped between two high-stiffness elastomeric diaphragms, thus providing perfect blow-by sealing and near zero friction, while adequately presenting the dynamic elements needed for smooth, continuous operation at desirable resonant frequencies. The device is essentially a tuned resonator whereby the inertia of the liquid piston and the elasticity of the diaphragms are selected to achieve a given resonant frequency. The passive dynamics of the engine are exploited to achieve efficiency through over-expansion, and to enable a return stroke with the small investment made in elastic energy with each power stroke. Additionally, the implementation of a separated combustion chamber – along with built-in actuated, high-flow intake and exhaust valves – ensures the feasibility of such desirable frequencies by decoupling the injection dynamics from the free-piston dynamics. The design and implementation of the device is shown, and simulated results are discussed.
Fluid Manipulation by Bio-Mimetic Cilia
Authors: Oh Kieseok , Chung Jae-Hyun , Devasia Santosh , Riley James J.
Published: May 2009

This paper describes the fabrication and actuation of bio-mimetic cilia for fluid manipulation. High aspect ratio cilia made of polydimethylsiloxane (PDMS) were successfully assembled in a microfluidic device by our novel fabrication method. This method was to release the PDMS cilia from a Si mold and assemble the cilia in a device. All the process was performed under water in order to avoid the stiction and pairing of the PDMS cilia. The underwater assembly method enabled a high aspect ratio PDMS structure assembly in a fluidic device. The PDMS cilia were actuated in air and water by lead-zirconate-titanate (PZT) microstage. In the fabricated device, the maximum displacement of the cilia was observed at 120Hz in air and at 50Hz in de-ionized (DI) water with our experimental condition. The actuated cilia in a solution produced convective and propulsive fluid flow near the cilia structure. The developed device can be used for precise handling of small volume sample (e.g., 1 μL).
Handling Frequent Design Changes by Automatic Optimization-Constrained Updates of Parametric CAD Models
Authors: Bowman K. Eric , Mattson Christopher A.
Published: May 2009

A common difficulty in designing mechanical systems is in handling the effects that design changes in one subsystem have on another, or on the system as a whole. This is made more difficult in early engineering design, when frequent changes are required and design information is preliminary. Increased efforts have been made to capitalize on the benefits of numerical optimization methods (search methods) in early engineering design – because of the large impact early decisions have on subsequent development activities. An important step toward executing meaningful optimizations in early design is the development of a design optimization framework that can be used when objectives, constraints, variables, and other conditions are expected to change as the design progresses and new information is gained. This paper presents a design framework that considers such change by subjecting the parametric updating of CAD models to optimization criteria. Under the proposed framework, a part is generically and parametrically modeled in a CAD system; when changes are made to the design of subsystems that interact with the part, the part is then automatically updated subject to design objectives and constraints. In this way, the updated part or subassembly satisfies system and subsystem level optimization criteria. Thus reducing the need for the designer to react to design changes in one subsystem by manually correcting the affected design of another. The proposed framework carries practical implications that are demonstrated in the development of a suspension rocker for a formula SAE car designed and built at Brigham Young University, resulting in a rocker weight savings of 18%.
Thermal Tug-O-War: A Competitive, Hands-On Approach to Learning Basic Heat Exchanger Design
Authors: Cook Daniel P. , Lowe Sidney
Published: May 2009

The “Thermal Tug-o-War” is a thermal-fluid design competition in which teams of students are assigned to design and build either a heating or cooling heat exchanger. The heating and cooling teams are then pitted against each other to see which of the teams’ heat exchangers can have a larger effect on the temperature of a “thermal reservoir”. Through this competition, students get practical, hands-on exposure to convection heat transfer, Bernoulli’s equation, pumping system design, and materials selection. This paper will present details on how the competition was originally staged and how is has changed to become a more valuable learning experience for the students.
Low Cost Adaptive Optics System for Retinal Imaging
Authors: Ficocelli Maurizio , Iqbal Azhar , Ben Amara Foued
Published: May 2009

This paper presents the design of an Adaptive Optics (AO) system for retinal imaging applications. The development of retinal imaging systems allows for early diagnosis of eye diseases. Such systems can increase the quality of life of patients as well as curtail increasing health care costs through early eye disease detection and treatment. Until recently, AO systems have been prohibitively expensive and cumbersome. This has been mainly due to the size and cost of flexible membrane mirrors normally used as the aberration correction device. Recent developments in the technology of Microelectromechanical System (MEMS) based actuators allow the implementation of AO systems which would have been difficult to implement a few years ago due to exorbitant costs. The aim of this paper is to present the design of a compact and flexible low cost AO system using off the shelf components to measure and compensate for the aberrations of the eye. The design is based around the system’s main components which include a 52 channel magnetically actuated deformable membrane mirror, a Shack Hartmann wavefront sensor and a control system which runs on a single processor personal computer. All the components are commercially available. The use of the MEMS-based magnetically actuated mirror allows for increased resolution and force compared to conventional membrane mirrors designed mainly for use in astronomical applications. The performance of the closed-loop system is evaluated through experiments. Although designed as a diagnostic tool for eye diseases, such a system will find a number of applications in basic research in the visual sciences, including the study of microscopic structures in the living retina that could not be seen before. Optometrists, retinal surgeons, and ophthalmologists will also benefit from using such a system, through potential improvements on commonly used instruments such as phoropters and fundus cameras.
Metallic Structural Heat Pipes as Sharp Leading Edges for Mach 7 Vehicles
Authors: Steeves Craig A. , He Ming Y. , Valdevit Lorenzo , Kasen Scott , Haj-Hariri Hossein , Wadley Haydn N. G. , Evans Anthony G.
Published: May 2009

Sharp leading edges on hypersonic vehicles experience very large heating loads and consequent high temperatures. One strategy for for accommodating these effects is to provide very high effectively thermal conductivity which allows heat to be transferred from the hot leading edge to large cool surfaces for radiation into space. Heat pipes integrated within metallic leading edges provide this function, as well as being easy to manufacture and highly robust compared to other material choices. This paper will examine the feasibility of metallic leading edge heat pipes for hypersonic vehicles in Mach 7 flight. Using temperatures and heat fluxes calculated elsewhere, analytic approximations of the temperature distributions and stresses in a prototypical system are analyzed. The analysis is supplemented and confirmed by finite element calculations. Feasibility of the system is assessed by simple calculations on the operational limits of heat pipes.
Microscale Temperature Measurements at the Triple Line of an Evaporating Thin Film
Authors: Dhavaleswarapu Hemanth K. , Garimella Suresh V. , Murthy Jayathi Y.
Published: May 2009

Thin-film evaporation from a meniscus in a confined space, which is the basis for many two-phase cooling devices, is experimentally investigated. The meniscus formed by heptane, a highly wetting liquid, on a heated, fused quartz substrate is studied. Microscale infrared temperature measurements performed near the thin-film region of the evaporating meniscus reveal the temperature suppression caused by the intensive evaporation in this region. The high spatial resolution (∼6.3 μm) and high temperature sensitivity (∼20 mK) of the infrared camera allowed for accurate measurements. The effects of meniscus thickness and applied heat flux on the thin-film heat transfer distribution and rate are also explored.
Experimental Flow Structure Analysis in Plates With 90° Chevron Geometry by a Particle Visualization Technique
Authors: Luna Jose M. , Romero-Mendez Ricardo , Hernandez-Guerrero Abel , Rubio-Arana Jose C.
Published: May 2009

The flow structures in the cavities of parallel cross-corrugated surfaces, also called chevron geometry, are investigated in this work using an experimental visualization method. An angle of 45° between the corrugations and the main flow direction has been considered. Reviews show that a considerable amount of investigations, mainly experimental, of heat transfer and pressure drop for cross-corrugated plates has been performed, whereas for the flow field in the cavities has only been investigated numerically. The flow visualization experiments are performed inside a water tunnel using a wide range of the hydraulic diameter-based Reynolds number.
“New Technology Introduction”: Lessons From Industry Cases
Authors: Wong Jenny , Beiter Kurt , Ishii Kosuke
Published: May 2009

A Lean New Technology Introduction (NTI) methodology is critical to any company that wishes to set the pace of the market, or even those that wish to keep pace with the competition. This paper describes the social and economic demands that lead forward-thinking companies to new technology introduction, as these demands were observed at five world-class companies. Since Womack, Jones and Roos’ 1990 book, The machine that changed the world, introduced the concept of Lean Production, and changed the face of America manufacturing, companies have increasingly trended toward “Lean”. That mentality has now extended beyond manufacturing into almost all aspects of the product development cycle, and into the corporate organizational structure. When a company identifies a business need, and targets a product application for the new technology, the company must then act quickly to develop, manufacture, and market the technology at pace with competitive market introductions. Review of five case studies revealed that lack of manufacturing readiness, in the form of non-satisfactory manufacturing processes, is a big culprit in the delay of technology introduction. The questions, “when will the new technologies be ready?” and “how can we integrate the new technologies into new products in a lean fashion?” continue to challenge product developers. While we do not suggest ways to address NTI in this paper, the ultimate goal of our research is to develop a methodology to address the NTI challenge.
Modeling Permanent Mold Casting of Aluminum
Authors: Cook Daniel P. , Deshmukh Sachin S. , Carey David P.
Published: May 2009

Modeling the complex, coupled fluid flow, heat transfer and solidification phenomena taking place in metal casting is a challenging task. The quality of any metal casting depends on many parameters such as the type of mould, rate of filling, and rate of solidification. Optimization of these operational parameters is very important in reducing casting defects such as oxide inclusions and porosity. This paper addresses the first steps in validating a computational fluid dynamics (CFD) model of permanent mold casting of aluminum. A mathematical model of the casting system has been developed using the commercial CFD package StarCD. A physical model of the system has been used to validate the mold filling phenomena in the process. Comparison of the results from these models will be presented.
Effects of Non-Geometric Features and Incentive Schemes on Manual Assembly of System Variants: An Experimental Study
Authors: Lakshminarayana Ramaprasad E. , Takai Shun
Published: May 2009

Although numerous firms have been shifting toward automated assembly, most still rely on manual assembly when complex assembly operation is required for large-scaled systems. Furthermore, because firms design variants of a system to satisfy diverse customer needs, they may manufacture these system variants in the same assembly line. This type of operation, called mixed model assembly, may improve the utilization of existing manufacturing facilities; however, it may also increase assembly errors due to interchanging geometrically similar parts between system variants. Design for Assembly (DFA) is a design guideline that assists engineers in designing systems that are easier to assemble. However, because DFA guidelines group geometrically similar parts in the same part category, it may be impossible to distinguish geometrically similar but functionally different parts (modules) used in different systems. This paper proposes experimenting how cognitive effects of non-geometric part features influence the productivity and quality in mixed model assembly operations. Furthermore, because the productivity and quality of manual assembly may be influenced by the motivation of operators, this paper examines how productivity and quality may be influenced by different incentive schemes.
Single-Phase Capillary Effects in Rectangular Microchannels Heat Sinks
Authors: Rubio-Jime´nez Carlos A. , Garci´a-Gonza´lez Jesu´s , Herna´ndez-Guerrero Abel , Popescu Daniela
Published: May 2009

In this work a steady state numerical analysis of the capillary effects in channels of a microscopic scale with rectangular cross section is presented. The diameter range under analysis falls on the microchannels classification. The velocities of the fluid flow satisfy the condition We<<Re, necessary and sufficient condition to guarantee that the capillary effects are present in the fluid flow in the channel. Water is used as the cooling fluid. A constant heat flux is applied at the heat sink bottom wall with a rating typical of the generated heat flow in current electronics high-tech devices. The results of thermal resistance are compared with the experimental results of Tuckerman, and the friction coefficient is compared with Peng and Peterson experiments, showing a good approximation when the capillary effects are considered in the numerical solution at lower Reynolds numbers.
Effects of Individual and Team Competitive Rewards on Collaboration and Productivity of Team
Authors: Boggavarapu Kumar , Veluru Nanda K. , Takai Shun
Published: May 2009

In the modern system development approach, engineers with diverse discipline form teams and work together in engineering projects. An example is a cross functional team in concurrent engineering. It is important to design incentive systems that maximize team achievements; however, there is a tradeoff between rewarding individual vs. team achievements. Rewarding solely on individual achievements may hinder the overall team achievements, while rewarding solely on team achievements may lead to the phenomenon called social loafing or free riding in which individuals tend to perform worse or contribute less in group. This paper studied the effects of competitive rewards based on individual and team’s achievements by conducting experiments using prisoner’s dilemma game (PDG) in which participants face tradeoff between working more or less in hypothetical individual and team assignments. The unique approach in this paper is to decompose the overall PDG payoff matrix into payoff matrix for individual achievements and that for team achievements to test the effects of individual and team competitive rewards. The experiment results suggested that introduction of team competitive rewards resulted in higher cooperation among team members and overall productivity, compared to when individual competitive rewards were introduced.
Effect of Radial Plate Flow Field Distribution on Current Density in a Proton Exchange Membrane (PEM) Fuel Cell
Authors: Cano-Andrade S. , Herna´ndez-Guerrero A. , Von-Spakovsky M. , Rubio-Arana C.
Published: May 2009

Proton exchange membrane (PEM) fuel cells are promising candidates for power generation in transportation, portable, and stationary applications due to their high full and partload efficiencies, low operating temperatures, high power densities, fast startups, and potential system robustness. A vital component for this new technology is the bipolar plate since it supplies the fuel and oxidant, removes the products of reaction, collects the current produced, and provides mechanical support for the cells in the stack. However, the bipolar plate adds weight, volume, and cost to the fuel cell. A way to offset this, at least partially and perhaps significantly, would be by improving the bipolar plate flow field layout so that the power density of the cell or stack (parallel cell arrangement) is improved. To that end, this paper proposes an innovative radial flow field design for which a three-dimensional model of the heat, mass, and charge transport and electrochemistry in a single fuel cell has been developed and solved via a finite volume approach. This model is based on the following supposition: steady state, isothermal, single phase, isotropic materials and mass transfer in three directions. Predictions of current density as well as the pressure losses, velocities, and flow field contours are made and presented.
Towards Managing Long-Term Uncertainties in Product Development
Authors: Fowler Whitfield J. , Ishii Kos
Published: May 2009

Under increasingly uncertain environment of long term life-cycle costs arising from such causes such as material price increases and carbon regulation, product development design decision makers need an improved method for evaluating project net present value under significant risks. This paper seeks to expose this need for an interdisciplinary design method capable of proactively managing long-term uncertainties and risks. First, the paper provides an overview of trends and uncertainties in material prices and environmental regulations. Second, we highlight a variety of existing work relevant to this research. The third section describes Customer Value Chain Analysis and Quality Function Deployment exercises towards addressing the nature of the challenge at hand. The study found that the primary customers for this research are engineering managers involved in strategic product development decisions. The most important aspects of a new methodology are to identify and characterize the uncertainties specific to a project, and to facilitate modeling. The final section describes a research path leading towards the development of a new design methodology. The paper concludes that a new framework will draw upon a variety of fields including Design For Reliability, Decision Analysis, Industrial Ecology, and Informatics.
Quick Acquisition of a Control Algorithm for Small Flying Robots by a Learning System Combining an Artificial Neural Network and an Immunity Algorithm
Authors: Watanabe Tohru , Wakamatsu Hideki , Nishiwaki Hidehiko
Published: May 2009

Flying robots: small computer controlled airplanes are useful for safe and economical investigation with aerial photography. We have developed such planes using DSP boards equipped with sensors and many PID control loops. However, the tuning of their control parameters is difficult because of many state variables, interference between control loops, and the nonlinear characteristics of aviation dynamics. In this paper, the self-organization of their control algorithm is proposed. An artificial neural network is used as the controller. The control algorithm is organized by back propagation type learning to decrease the difference between the desired state variables and the estimated ones. A problem of back propagation-type learning is apt to appear in local optimum solutions. Therefore, many sets of initial values of input gains at the synapses of neurons are prepared similar to DNA codes in immune bodies for immunity process simulation. When a local optimum solution of the neural network is found, the DNA code of learned gains is memorized at the T cell of the immunity process. Cells near these having the memorized DNA are eliminated, and new cells far from them are added to the process in searching for better solutions. It is verified by computer simulation that a better control algorithm is automatically organized for small flying robots having complicated dynamics.