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1999

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Articles 1 - 30 of 167

Full-Text Articles in Mechanical Engineering

Experimental Studies And Modeling Of Mechanical Properties And Morphologies Of In Situ Polymer Composites, Zhigang Li Dec 1999

Experimental Studies And Modeling Of Mechanical Properties And Morphologies Of In Situ Polymer Composites, Zhigang Li

Dissertations

In this study, a series of experiments was set up in order to analyze the morphology development and mechanical properties of poly(ethylene terephthalate) (PET)/ liquid crystalline polymer (LCP) blends. Simulations of the injection molded blends at various process conditions were performed using CMOLD. In order to determine the effect of the processing parameters on the deformation of the LCP domains during the injection molding, a new analytical method to analyze the melt flow in the advancing melt front (AMF) region was developed. By combining the simulations of the injection molding and analysis of the melt flow in the AMF ...


Reconfiguration And Tool Path Planning Of Hexapod Machine Tools, Zhenqun Li Dec 1999

Reconfiguration And Tool Path Planning Of Hexapod Machine Tools, Zhenqun Li

Dissertations

Hexapod machine tools have the potential to achieve increased accuracy, speed, acceleration and rigidity over conventional machines, and are regarded by many researchers as the machine tools of the next generation. However, their small and complex workspace often limits the range of tasks they can perform, and their parallel structure raises many new issues preventing the direct use of conventional tool path planning methods. This dissertation presents an investigation of new reconfiguration and tool path planning methods for enhancing the ability of hexapods to adapt to workspace changes and assisting them in being integrated into the current manufacturing environments.

A ...


Segregation And Flow Characterization In Vibrated Hopper, Thottiam P. Ravichandran Dec 1999

Segregation And Flow Characterization In Vibrated Hopper, Thottiam P. Ravichandran

Theses

Experiments and numerical simulation studies were carried. out on vertically vibrated wedge-type hoppers containing binary mixtures for the present research. The studies focussed on segregation analysis of the hopper discharge and the characterization of flow pattern of the binary mixtures in sealed hoppers, over wide ranges of frequency and amplitude of acceleration to determine the effect of these parameters.

The results of segregation study show that vibration promotes segregation of the binary mixtures. However, increase in frequency was found to make the contents of segregated discharge more uniform. Also, increase in wedge angle seemed to help in reducing segregation.

The ...


General Parallel-Leg Mechanism : Position Analysis, Hans Buus Gangwar Dec 1999

General Parallel-Leg Mechanism : Position Analysis, Hans Buus Gangwar

Theses

This thesis proposes to analytically express the positions of the legs (each leg has a length and two spin orientations) for a parallel leg mechanism in terms of a single variable. The only limitations imposed are the leg bases are all on the same reference plane and the tool orientation is normal to the mobile upper plate. This is done for a parallel leg mechanism having any number of legs. The variable chosen is the first leg's vertex position on the upper plate.

The state space is the space the configuration can occupy. By looking at a planar slice ...


United States Patent: Method And System For Estimating The Tenderness Of A Meat Product, Maria Victoria Spadaro, Rosana Moreira, Jimmy Keeton, D. H. Allen Dec 1999

United States Patent: Method And System For Estimating The Tenderness Of A Meat Product, Maria Victoria Spadaro, Rosana Moreira, Jimmy Keeton, D. H. Allen

Faculty Publications from the Department of Engineering Mechanics

A method for estimating the tenderness of a meat product is provided. The method includes determining the stress relaxation coefficient of a meat sample. One or more physical parameters of the meat sample are then determined from the stress relaxation coefficient. Diagnostic sensory characterization data, such as a numerical estimation of the meat's overall tenderness, is then determined for the meat sample. The physical parameters are then correlated to the diagnostic sensory characterization data, to allow the diagnostic sensory characterization data to be estimated solely from the measured physical parameters.


Development Of Rear-End Collision Avoidance In Automobiles, Uttamkumar Dravidam Dec 1999

Development Of Rear-End Collision Avoidance In Automobiles, Uttamkumar Dravidam

FIU Electronic Theses and Dissertations

The goal of this work is to develop a Rear-End Collision Avoidance System for automobiles. In order to develop the Rear-end Collision Avoidance System, it is stated that the most important difference from the old practice is the fact that new design approach attempts to completely avoid collision instead of minimizing the damage by over-designing cars. Rear-end collisions are the third highest cause of multiple vehicle fatalities in the U.S. Their cause seems to be a result of poor driver awareness and communication. For example, car brake lights illuminate exactly the same whether the car is slowing, stopping or ...


Internally Constrained Mixtures Of Elastic Continua, Stephen M. Klisch Dec 1999

Internally Constrained Mixtures Of Elastic Continua, Stephen M. Klisch

Mechanical Engineering

A treatment of internally constrained mixtures of elastic continua at a common temperature is developed. Internal constraints involving the deformation gradient tensors and the common mixture temperature are represented by a constraint manifold, and an internally constrained mixture of elastic continua is associated with each unique equivalence class of unconstrained mixtures. The example of intrinsic incompressibility of each constituent first proposed by Mills is discussed.


Development Of Cfd Algorithms For Transient And Steady Aerodynamics, Fergal Boyle [Thesis] Dec 1999

Development Of Cfd Algorithms For Transient And Steady Aerodynamics, Fergal Boyle [Thesis]

Other Resources

Research carried out in the United States and in Europe over the last 20 years has led to the development of the advanced propeller, a small-diameter, highly-loaded, multi-bladed, swept, variable-pitch propeller, that can achieve potential fuel savings of 30% over an equivalent technology turbofan engine at competitive speed and altitudes.

In this work an implicit finite-volume algorithm is developed for predicting the transient flow around an advanced propeller under asymmetric inflow conditions. The development of the unsteady propeller algorithm evolves from a family of methods for progressively more complex applications. In total six algorithms are developed: three steady and three ...


Spherical Mechanism Synthesis In Virtual Reality, T. J. Furlong, Judy M. Vance, Pierre M. Larochelle Dec 1999

Spherical Mechanism Synthesis In Virtual Reality, T. J. Furlong, Judy M. Vance, Pierre M. Larochelle

Mechanical Engineering Publications

This paper presents a new approach to using virtual reality (VR) to design spherical mechanisms. VR provides a three-dimensional (3-D) design space where a designer can input design positions using a combination of hand gestures and motions and view the resultant mechanism in stereo using natural head movement to change the viewpoint. Because of the three-dimensional nature of the design and verification of spherical mechanisms, VR is examined as a new design interface in this research. In addition to providing a VR environment for design, the research presented in this paper has focused on developing a “design in context” approach ...


Assessing The Effectiveness Of Traditional And Virtual Reality Interfaces In Spherical Mechanism Design, P. T. Evans, Judy M. Vance, Veronica J. Dark Dec 1999

Assessing The Effectiveness Of Traditional And Virtual Reality Interfaces In Spherical Mechanism Design, P. T. Evans, Judy M. Vance, Veronica J. Dark

Mechanical Engineering Publications

Virtual reality (VR) interfaces have the potential to enhance the engineering design process, but before industry embraces them, the benefits must be understood and documented. The current research compared two software applications, one which uses a traditional human-computer interface (HCI) and one which uses a virtual reality HCI, that were developed to aid engineers in designing complex three-dimensional spherical mechanisms. Participants used each system to design a spherical mechanism and then evaluated the different interfaces. Participants rated their ability to interact with the computer images, their feelings about each interface, and their preferences for which interface device to use for ...


Development Of A Near-Perfect Lens Surface Generation Advisor (Nplsga), Victor De Rossi Nov 1999

Development Of A Near-Perfect Lens Surface Generation Advisor (Nplsga), Victor De Rossi

FIU Electronic Theses and Dissertations

The Near-Perfect Lens Surface Generation Advisor is a software program designed to optimize manufacturing conditions of acrylic lenses. The program numerically minimizes the total manufacturing cost of machining and hand polishing by choosing the optimal feed rate, tool diameter and step size. Derivations of mathematical equations plus neural networks estimations were used to calculate the total cost as a function of these given variables. Machining time was found from values obtained from feed rate and tool displacement. Polishing time was estimated based on the scallop height, and the total polished surface area. Scallop height was calculated from geometrical expressions depending ...


Simtrainer: A Management Training Tool, Wade Stark, Sema E. Alptekin Nov 1999

Simtrainer: A Management Training Tool, Wade Stark, Sema E. Alptekin

Industrial and Manufacturing Engineering

Abstract published of poster paper presented at conference.


Collaborative Undergraduate Research, Hamid Davoodi, Frederick Just, Ali Saffar, Mohammad Noori, William W. Durgin Nov 1999

Collaborative Undergraduate Research, Hamid Davoodi, Frederick Just, Ali Saffar, Mohammad Noori, William W. Durgin

Office of the Provost and Vice President of Academic Affairs Scholarship

A joint undergraduate research project between University of Puerto Rico at Mayagüez (UPRM) and Worcester Polytechnic Institute (WPI) started four years ago. Each year a group of students, varying between six and ten, from WPI will come to Puerto Rico to work with a group of students, varying from six to ten, from UPRM on a well defined research project. Although the topics of the projects have been different but all follow the same goal, Vibration Control of Structures by Utilizing Shape Memory Alloys. Each year the project starts on January and ends on May. Both groups of the students ...


An Evaluation Of Ploughing Models For Orthogonal Machining, Daniel J. Waldorf, Richard E. Devor, Shiv G. Kapoor Nov 1999

An Evaluation Of Ploughing Models For Orthogonal Machining, Daniel J. Waldorf, Richard E. Devor, Shiv G. Kapoor

Industrial and Manufacturing Engineering

An analytical comparison is made between two basic models of the flow of workpiece material around the edge of an orthogonal cutting tool during steady-state metal removal. Each has been the basis for assumptions in previous studies which attempt to model the machining process, but no direct comparison had been made to determine which, if either, is an appropriate model. One model assumes that a separation point exists on the rounded cutting edge while the other includes a stable build-up adhered to the edge and assumes a separation point at the outer extreme of the build-up. Theories of elastic-plastic deformation ...


Scheduling Semiconductor Device Test Operations On Multihead Testers, Tali Freed, Robert C. Leachman Nov 1999

Scheduling Semiconductor Device Test Operations On Multihead Testers, Tali Freed, Robert C. Leachman

Industrial and Manufacturing Engineering

Past attempts to devise scheduling methods for the device test operations of semiconductor manufacturing firms fail to address a significant characteristic of multiple-head test systems—the dependency of processing rates on the lots processed simultaneously on the testers. Since the problem has never been modeled accurately in the scheduling literature, feasibility and performance of previously proposed scheduling methodologies for multihead testers may not be accurately assessed. In this paper, we describe the multihead tester scheduling problem, present an enumeration solution procedure, and illustrate the problems of previously suggested tester scheduling algorithms.


Gauge Repeatability & Reproducibility Study For A 3-D Solder Paste Inspection System, Jianbiao Pan, Gregory L. Tonkay, Robert H. Storer, Ronald M. Sallade, David J. Leandri Oct 1999

Gauge Repeatability & Reproducibility Study For A 3-D Solder Paste Inspection System, Jianbiao Pan, Gregory L. Tonkay, Robert H. Storer, Ronald M. Sallade, David J. Leandri

Industrial and Manufacturing Engineering

Due to the increased use of Ball Grid Arrays (BGAs) and fine pitch and ultra fine pitch Quad Flat Packages (QFPs), there is a dramatic increase in demand for solder paste inspection after the stencil printing process. The important response variables of the printing process are deposited solder paste volume, area, height and position. To identify and remove defects at the earliest possible process step, a 3-D solder paste inspection system should be used to monitor solder paste deposited on all pads on every board before component placement. An example is a fully automatic laser-based 3-D triangulation solder paste inspection ...


Critical Variables Of Solder Paste Stencil Printing For Micro-Bga And Fine Pitch Qfp, Jianbiao Pan, Gregory L. Tonkay, Robert H. Storer, Ronald M. Sallade, David J. Leandri Oct 1999

Critical Variables Of Solder Paste Stencil Printing For Micro-Bga And Fine Pitch Qfp, Jianbiao Pan, Gregory L. Tonkay, Robert H. Storer, Ronald M. Sallade, David J. Leandri

Industrial and Manufacturing Engineering

Stencil printing continues to be the dominant method of solder deposition in high volume surface mount assembly. Control of the amount of solder paste deposited is critical for fine pitch and ultra-fine pitch SMT assembly. The process is still not well understood as indicated by the fact that industry reports 52-71% of SMT defects are related to the solder paste stencil printing process. The purpose of this paper is to identify the critical variables that influence the deposited solder paste volume, area, and height. An experiment was conducted to investigate the effects of relevant process parameters on the amount of ...


Application Of A Fiber-Reinforced Continuum Theory To Multiple Deformations Of The Annulus Fibrosus, Stephen M. Klisch, Jeffrey C. Lotz Oct 1999

Application Of A Fiber-Reinforced Continuum Theory To Multiple Deformations Of The Annulus Fibrosus, Stephen M. Klisch, Jeffrey C. Lotz

Mechanical Engineering

Accurate tissue stress predictions for the annulus fibrosus are essential for understanding the factors that cause or contribute to disc degeneration and mechanical failure. Current computational models used to predict in vivo disc stresses utilize material laws for annular tissue that are not rigorously validated against experimental data. Consequently, predictions of disc stress resulting from physical activities may be inaccurate and therefore unreliable as a basis for defining mechanical–biologic injury criteria. To address this need we present a model for the annulus as an isotropic ground substance reinforced with two families of collagen fibers, and an approach for determining ...


The Microchannel Flow Of A Micropolar Fluid, Guohua Liu Oct 1999

The Microchannel Flow Of A Micropolar Fluid, Guohua Liu

Doctoral Dissertations

Micro-channel flows have been computed to investigate the influence of Navier-Stokes formulation for the slip-flow boundary condition, and a micro-polar fluid model, respectively.

The results of the slip boundary condition show that the current methodology is valid for slip-flow regime (i.e., for values of Knudsen number less than approximately 0.1). Drag reduction phenomena apparent in some micro-channels can be explained by slip-flow theory. These results are in agreement with some computations and experiments.

An ad hoc micro-polar fluid model is developed to investigate the influence of micro effects, such as micro-gyration, in micro-scale flows. The foundation of the ...


Ole Miss Engineer 1999 Oct 1999

Ole Miss Engineer 1999

The Ole Miss Engineer

No abstract provided.


Effect Of Interfacial Mobility On Flexural Strength And Fracture Toughness Of Glass/Epoxy Laminates, T. W. H. Wang, Frank D. Blum, Lokeswarappa R. Dharani Oct 1999

Effect Of Interfacial Mobility On Flexural Strength And Fracture Toughness Of Glass/Epoxy Laminates, T. W. H. Wang, Frank D. Blum, Lokeswarappa R. Dharani

Chemistry Faculty Research & Creative Works

Mechanical testing and surface fractography were used to characterize the fracture of E-glass fiber reinforced epoxy composites as a function of the silane coupling agent used. gamma-Aminopropyltriethoxysilane (APS) and delta-aminobutyltriethoxysilane (ABS) were used because these have been shown to have different interfacial mobilities at multilayer coverage. The values of the properties studied generally increased from untreated c, as determined from a Mode I translaminar fracture toughness tests, for the untreated composites (10.5 ± 0.4 kJ/m2) was lower than that for the ABS-treated composites (14.3 ± 2.1 kJ/m2) which was lower than that for the APS-treated composites ...


The Mechtech Program: An Education And Training Model For The Next Century, Robert Forrant Sep 1999

The Mechtech Program: An Education And Training Model For The Next Century, Robert Forrant

New England Journal of Public Policy

The small-firm metalworking industry is routinely characterized by cutthroat competition and fierce privacy. Yet, since the late 1980s, the members of the western Massachusetts chapter of the National Tooling and Machining Association have participated in an education, training, and technology diffusion network characterized by a high degree of interfirm cooperation. Hundreds of workers and managers have take part in group training sessions and seminars. The reconstruction of the skill base is central to the MechTech apprenticeship program through which apprentices spend four years in participating firms, exiting the program as licensed machinists, tool and die makers, or moldmakers. In an ...


Sept 1999, Tractor Museum Sep 1999

Sept 1999, Tractor Museum

Museum Planning and Development Documents

Director's Report Curator's Report Friend's Letterhead and Logo


Screen Printing Process Design Of Experiments For Fine Line Printing Of Thick Film Ceramic Substrates, Jianbiao Pan, Gregory L. Tonkay, Alejandro Quintero Sep 1999

Screen Printing Process Design Of Experiments For Fine Line Printing Of Thick Film Ceramic Substrates, Jianbiao Pan, Gregory L. Tonkay, Alejandro Quintero

Industrial and Manufacturing Engineering

Screen printing has been the dominant method of thick film deposition because of its low cost. Many experiments in industry have been done and many models of the printing process have been developed since the 1960's. With a growing need for denser packaging and a drive for higher pin count, screen printing has been refined to yield high resolution prints. However, fine line printing is still considered by industry to be difficult. In order to yield high resolution prints with high first pass yields and manufacturing throughput, the printing process must be controlled stringently.

This paper focuses on investigating ...


Visualization Of Post-Processed Cfd Data In A Virtual Environment, Vishant J. Shahnawaz, Judy M. Vance, Sasikumar V. Kutti Sep 1999

Visualization Of Post-Processed Cfd Data In A Virtual Environment, Vishant J. Shahnawaz, Judy M. Vance, Sasikumar V. Kutti

Mechanical Engineering Conference Presentations, Papers, and Proceedings

This paper discusses the development of a virtual reality (VR) interface for the visualization of Computational Fluid Dynamics (CFD) data. The application, VR-CFD, provides an immersive and interactive graphical environment in which users can examine the analysis results from a CFD analysis of a flow field in three-dimensional space. It has been tested and implemented with virtual reality devices such as the C2, head mounted display (HMD) and desktop VR. The application is designed to read PLOT3D structured grid data and to display the flow field parameters using features such as streamlines, cutting planes, iso-surfaces, rakes, vector fields and scalar ...


Galnnas Resonant-Cavity-Enhanced Photodetector Operating At 1.3 Μm, J. B. Heroux, Xiaodong Yang, W. I. Wang Sep 1999

Galnnas Resonant-Cavity-Enhanced Photodetector Operating At 1.3 Μm, J. B. Heroux, Xiaodong Yang, W. I. Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We demonstrate a GaAs-based p-i-n resonant-cavity-enhanced (RCE) GalnNAs photodetector operating near 1.3 µm. The device design was optimized using a transfer matrix method and experimental absorption spectra obtained from p-i-n structures grown without a resonant cavity. The RCE photodetector was fabricated in a single growth step by using GaAs/AlAs distributed Bragg reflectors for the top and bottom mirrors. A 72% quantum efficiency was obtained with a full width at half maximum of 11 nm.


Interventions Of Water Jet Technology On Skin Surgery, Kittipat Vichyavichien Aug 1999

Interventions Of Water Jet Technology On Skin Surgery, Kittipat Vichyavichien

Theses

The perfect and precise surgical cut, similar to today's laser one, is very important in many surgeries, especially in dissection and to recanaize arterial occlusive lessions. Causing no coagulation is one of the advantages of water jet because it generates no heat. It also provides omni-directional cutting capabilities at very high speeds, resulting edge quality that is usually superior to other existing conventional cutting processes. Debris is always carried away from incisions by jet stream and less damaged tissue, than mechanical incisions. In addition, water jet exerts minimal contact pressure on the tissue being cut due to the small ...


Biomechanical Study Of Performance Of A Plugged Femoral Implant Coupled With A Trochanter Cable System Using Finite Element Analysis, Deanna Yvonne Carstarphen Aug 1999

Biomechanical Study Of Performance Of A Plugged Femoral Implant Coupled With A Trochanter Cable System Using Finite Element Analysis, Deanna Yvonne Carstarphen

Theses

A Finite Element Analysis was conducted to determine the effect of a plug on the performance of the critical section of a femoral implant coupled with a trochanter cable grip system. The critical section was defined near the proximal end of the stem where a hole was designed for the purpose of attaching the cable grip system. Two models were generated for the analysis. One consisted of the critical section with the grip cables and a plug filled in the hole and the other was without the plug. The models were based on design specifications provided by Howmedica Incorporated. Two ...


Active Local Volume Displacement Cancellation Of A Vibrating Baffled Beam, Marcellin Zahui Aug 1999

Active Local Volume Displacement Cancellation Of A Vibrating Baffled Beam, Marcellin Zahui

Dissertations

An active noise control apparatus is developed. The device reduces the sound radiated from a vibrating clamped beam. The attenuation of the sound field is obtained through minimization of local volume displacements of the vibrating beam. Two single-input/single-output cancellation devices are used. Each device employs a motion sensor and an acoustic actuator. The actuator is a loudspeaker equipped with a pressure sensor to detect its volume displacement. The motion sensor signal is related to the local volume displacement of the structure which is then reduced by a loudspeaker driven with an equal but opposing volume displacement. The volume displacement ...


Nonlinear Robust Missile Autopilot Design Using Successive Galerkin Approximation, Timothy Mclain, Randal W. Beard Aug 1999

Nonlinear Robust Missile Autopilot Design Using Successive Galerkin Approximation, Timothy Mclain, Randal W. Beard

Faculty Publications

The application of a new nonlinear robust control strategy to the design of missile autopilots is presented. The control approach described and demonstrated here is based upon the numerical solution of the Hamilton-Jacobi-Isaacs equation by Successive Galerkin Approximation. Using this approach, feedback controllers are computed by an iterative application of a numerical Galerkin-type PDE solver. Application of this approach to the design of a pitch-axis autopilot for a missile having uncertain pitch moment and lift force is described.