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1997

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Articles 1 - 30 of 198

Full-Text Articles in Mechanical Engineering

Numerical Study Of Three-Dimensional Free Convection From Semi-Enclosed Geometry And Discontinuous Heat Sources, Aklilu T.G. Giorges Dec 1997

Numerical Study Of Three-Dimensional Free Convection From Semi-Enclosed Geometry And Discontinuous Heat Sources, Aklilu T.G. Giorges

Dissertations

Three-dimensional natural convection from three-by-three array of isoflux heat sources mounted on one vertical wall of semi-enclosed region has been numerically investigated. Detailed thermal information of this important engineering configuration is currently not available. The major objective of this study was to obtain this needed thermal and velocity information.

The semi-enclosed geometry can be viewed as a thin rectangular region with four closed and two open sides. The open surfaces are located at the top and adjacent side. For the fluid air, Pr = 0.71, the study covered a heat flux based Rayleigh number (Ra) range of (102 ≤ R ...


Kinematic Analysis Of A Swash-Plate Mechanism Using Transformation Matrices, David Edgar Evans Dec 1997

Kinematic Analysis Of A Swash-Plate Mechanism Using Transformation Matrices, David Edgar Evans

Theses

The swash-plate mechanism is used to transfer rotational motion into translational motion and vice versa. Using transformation matrices to describe each joint, the displacements of the swash-plate mechanism were analyzed. The general transformation matrix model for the plane joint, not previously developed using transformation matrices, was presented. The solution was tested using a computer program. Examples of three different swash-plate angles; 10, 45, and 25' were considered. The solution was found to agree with previous solutions while offering a more complete description of the mechanism. Future work in this area could include a complete static, velocity, and/or dynamic analysis ...


Dynamic Friction Measurement, Modeling, And Compensation For Precise Motion Control, Simon Cohn Dec 1997

Dynamic Friction Measurement, Modeling, And Compensation For Precise Motion Control, Simon Cohn

Theses

In this thesis, measurements of dynamic friction in a hydrodynamic journal bearing were performed for varying sinusoidal velocity excitations, loads, and lubricants. The results indicate that the friction data displays a negative slope in the mixed region of friction vs. velocity (f-v) curves, and also shows that the dynamic friction is not just a function of current velocity, but also a function of velocity history (hysteresis). These results are in agreement with previous experimental investigations by other investigators in lubricated friction.

Secondly, a dynamic friction model is fully explored and partially extended to provide quantitative agreement to measured friction values ...


Optimal Synthesis Of A Planar Four-Bar Function Generator Based On Imderect Measure Of Structural Error, Robert Ellis Dec 1997

Optimal Synthesis Of A Planar Four-Bar Function Generator Based On Imderect Measure Of Structural Error, Robert Ellis

Theses

A novel technique for optimal synthesis of a planar four-bar function generator is presented. An indirect measure of structural error is used to formulate an objective function which, along with its derivatives, is straightforward to evaluate and results in an elegant and robust algorithm. Lagrange multipliers are used to incorporate the loop closure constraint into the objective function.

In this thesis, the formulation of the objective function and the minimization algorithm are described, examples are presented, and the virtues and shortcomings of the algorithm are discussed.


Parameter Optimization For Curl Distortion In Building Parts Using 3-D Laser Stereolithography, Laurel A. Hanesian Dec 1997

Parameter Optimization For Curl Distortion In Building Parts Using 3-D Laser Stereolithography, Laurel A. Hanesian

Theses

The curl distortions in rapid prototyping using 3-D laser stereo lithography occur as the top layers shrink after being drawn and attaching to the bottom layers. The amount of curl is dependent upon the how much shrinkage the layer has finished prior to adhesion. It is also dependent on how deep the cure of the top layer amounts to as it adheres into the bottom layer. This thesis investigated the effect of build parameters on the distortions associated with the diagnostic 'Letter-H' shaped test part. The same parameters were also considered in a time optimization study, using calculated, predicted results ...


Statistical Continuum Theory For Inelastic Behavior Of A Two-Phase Medium, Brent L. Adams, H. Garmestani, S. Lin Dec 1997

Statistical Continuum Theory For Inelastic Behavior Of A Two-Phase Medium, Brent L. Adams, H. Garmestani, S. Lin

Faculty Publications

This work was supported in part (B.L. Adams) by the MRSEC Program of the National Science Foundation under Award no. DMR-9632556. Further support was provided by the Center for Materials Research and Technology (MARTECH at FSU) and Center for Nonlinear and Nonequilibrium Sciences (CENNAS at FAMU). A statistical contiuum mechanics formulation is presented to predict the inelastic behavior of a medium consisting of two isotropic phases. The phase distribution and morphology are represented by a two-point probability function. The isotropic behavior of the single phase medium is represented by a power law relationship between the strain rate and the ...


Development And Experimental Verification Of A Three-Dimensional Model Of Left Ventricular Flow Dynamics, Tong Ding Dec 1997

Development And Experimental Verification Of A Three-Dimensional Model Of Left Ventricular Flow Dynamics, Tong Ding

FIU Electronic Theses and Dissertations

Ischemic heart disease, which results from the insufficient coronary artery blood flow is a leading cause of mortality in developed countries. It manifests itself by abnormal left ventricular wall motion during systole.

A three dimensional numerical model was developed to simulate the flow patterns in the left ventricle. Numerical solutions were obtained by discretizing the Navier-Stokes equations for viscous, incompressible, steady flow using finite element method.

A diagnostic index Central Ejection Region (CER) as well as its quantitative version CER coefficient which are based on the flow patterns were defined as the region in which velocity vectors were aligned 5 ...


Investigation And Demonstration Of A Rich Combustor Cold Start Device For Alcohol Fueled Engines, David Kim Irick Dec 1997

Investigation And Demonstration Of A Rich Combustor Cold Start Device For Alcohol Fueled Engines, David Kim Irick

Doctoral Dissertations

Alcohols (methanol and ethanol) have been identified as having the potential to improve air quality when used to replace conventional gasoline. This potential is primarily due to the different organic species that are emitted by alcohol-fueled engines. The use of "near neat" alcohols gives greater benefits than fuels containing lower levels of alcohol, but neat alcohols present a significant cold starting problem.

The primary objective of this study was to develop a rich combustor device which will extend the cold start range of alcohol fueled engines to -30°C while reducing cold start emissions. In support of this objective a ...


Tractor Test Museum Commttee Minutes November 19th, 1997, Tractor Museum Nov 1997

Tractor Test Museum Commttee Minutes November 19th, 1997, Tractor Museum

Museum Planning and Development Documents

Update on Roof Progress Big Red Club State Fair Project


Maine Guide To Energy Efficient Residential Construction : A Manual Of Accepted Practices, State Of Maine Energy Conservation Division Nov 1997

Maine Guide To Energy Efficient Residential Construction : A Manual Of Accepted Practices, State Of Maine Energy Conservation Division

Maine Collection

Maine Guide to Energy Efficient Residential Construction : A Manual of Accepted Practices

State of Maine Energy Conservation Division, Department of Economic and Community Development, 59 State House Station, Augusta, Maine 04333-0059

Second Edition - November, 1997

Contents: Dedication / Acknowledgements / Introduction / Part 1. Summary of Maine's Residential Energy Standards / Part 2. Siting and Initial Design Considerations / Part 3. Important Considerations for the Design Phase / Part 4. Recommended Construction Practices / Appendixes


Nonlinear Optimal Control Of A Hydraulically Actuated Positioning System, Timothy Mclain, Randal W. Beard Nov 1997

Nonlinear Optimal Control Of A Hydraulically Actuated Positioning System, Timothy Mclain, Randal W. Beard

Faculty Publications

In this paper, the nonlinear optimal control problem is formulated for the position control of an electrohydraulic servo system. The optimal control is given by the solution to the Hamilton-Jacobi-Bellman equation, which in this case cannot be solved explicitly. An alternative method, based upon successive Galerkin approximation, is used to obtain an approximate optimal solution. Preliminary simulation results, demonstrating the application of this approach to the position control of a hydraulically actuated device, are presented.


Extracting The Relative Grain Boundary Free Energy And Mobility Functions From The Geometry Of Microstructures, Brent L. Adams, D. Kinderlehrer, W. W. Mullins, Anthony D. Rollett, Shlomo Ta'asan Nov 1997

Extracting The Relative Grain Boundary Free Energy And Mobility Functions From The Geometry Of Microstructures, Brent L. Adams, D. Kinderlehrer, W. W. Mullins, Anthony D. Rollett, Shlomo Ta'asan

Faculty Publications

This work was supported primarily by the MRSEC Program of the National Science Foundation under Award Number DMR-9632556. This paper describes a method for extracting, from measurements of a polycrystal, the relative excess free energy and the relative mobility of the grain boundaries as functions of the crystallographic type (five degrees of freedom) and relevant thermodynamic variables. The method requires the simultaneous measurement of both the geometry and the crystallography of a large number of grain boundary intersections; the crystallographic information may be obtained from orientation imaging microscopy (OIM). For simplicity, the intersections will be assumed to be triple junctions ...


Robotic Tcf And Rigid-Body Calibration Methods, Edward Red, Xuguang Wang Nov 1997

Robotic Tcf And Rigid-Body Calibration Methods, Edward Red, Xuguang Wang

Faculty Publications

For off-line programming to work, systematic methods must be developed to account for non-ideal performance of the parts and devices in the manufacturing cell. Although much of the literature focuses on robot inaccuracy, this paper considers practical methods for the tool control frame (TCF) calibration and rigid-body compensation required to close the inverse kinematics loop for target driven tasks.


Automobile Air Bag Inflation System Based On Fast Combustion Reaction, Yacoob Tabani Oct 1997

Automobile Air Bag Inflation System Based On Fast Combustion Reaction, Yacoob Tabani

Dissertations

Current automobile air bag inflator technology is complex, expensive and environmentally unsafe. A new and novel air bag inflator based on fast combustion reactions of methane-oxygen mixtures has been developed and studied. The thermodynamics and mass flow parameters of this new inflator have been modeled and found to be in agreement with experimental results.

The performance of the fast combustion inflator was evaluated in terms of pressure-time relationships inside the inflator and in a receiving tank simulating an air bag as well as the temperature-time relationship in the tank.

In order to develop this fast combustion inflator, several critical issues ...


Electrocatalytic Control Of Exhaust Soot, Victor L. Callahan Oct 1997

Electrocatalytic Control Of Exhaust Soot, Victor L. Callahan

Dissertations

The feasibility of combining electrostatic precipitation and use of a catalytic wall in a straight tube reactor as a means of destroying soot particles was investigated. Enhanced particle diffusion to the wall by an applied electric field provided the means of particle capture for subsequent catalytic oxidation at the active surface in a small length tube.

Soot particles flowing in a gas stream are influenced by the following transport mechanisms: convective flux as a result of bulk flow, diffusion flux as a result of particle concentration or number density gradient, and an electrostatic flux from the coulombic attraction as charged ...


Computational Determination Of Laminar Flow Loss Coefficients In 90° Channel Bend, Leonard Paul Parkin Oct 1997

Computational Determination Of Laminar Flow Loss Coefficients In 90° Channel Bend, Leonard Paul Parkin

Theses

Loss coefficients for laminar two dimensional incompressible channel (or duct) flow in a 90° bend are investigated using FEM software, FIDAP. This problem consists of a two dimensional duct with a 90° bend of constant radius flowing with water, at 70°F and atmositeno conditions. The bend radius to duct width ratios examined were 1.5 and 1.0. Both bend radius to duct width ratios were analyzed for Reynolds Number ranging from 50 to 1800. The pressure and velocity distributions were found and used to determine the pressure due to the bend. The results show the pressure loss effect ...


Modeling Of Deformed Swept Volumes With Sde And Its Applications To Nc Simulation And Verification, Feng Lu Oct 1997

Modeling Of Deformed Swept Volumes With Sde And Its Applications To Nc Simulation And Verification, Feng Lu

Theses

Representation of swept volumes has important applications in NC simulation and verification as well as robot-motion planning. Most research on .the representation of swept volumes has been limited to rigid objects. In this study, a sweep deferential equation (SDE) approach is presented for the representation of deformed swept volumes generated by flexible objects.

The deformed swept volume analysis is integrated with machining physics to account for tool deformation/deflection for the NC simulation. End milling is modeled and analyzed and the tool deformations are calculated and integrated with the SDE program. A program is developed in C++ for the generation ...


Multi-Lifecycle Assessment Of Cathode Ray Tubes, Devendra Jayant Badwe Oct 1997

Multi-Lifecycle Assessment Of Cathode Ray Tubes, Devendra Jayant Badwe

Theses

Over the past few years environmental issues and concerns have become more and more important, as they become a common part of most people's personal experience. In these regards, the electronics industry is facing substantial problems in terms of end-of-life management of its products, televisions and monitors in particular. The building blocks of this industry are usually viewed as relatively "clean". However, manufacturing by­products of the electronics industry and the disposition of electronics are becoming increasingly important technical, financial, and environmental issues.

Within the context of the above issues, environmentally responsible disposal of Cathode Ray Tubes (CRT's ...


Mechanical Design Of An Experimental Parallel Robot, Philip Song Oct 1997

Mechanical Design Of An Experimental Parallel Robot, Philip Song

Theses

OSCAR, or Operational Space Controlled Adjustable Robot, is a parallel-actuated manipulator, also known as Stewart Platform or platform manipulator. The apparatus consists of two platforms (base and top) and six prismatic actuators in between. The main advantage of a platform manipulator is the fact that it can out-perform serial manipulators in both load capacity and precision. However, there are disadvantages and weaknesses such as limited mobility. A platform manipulator has reduced workspace compared to serial manipulators. The problem of limited workspace is solved by enabling OSCAR to change its prismatic leg positioning about the base platform.

During the course of ...


Electrode Performance Test On Single Ceramic Fuel Cells Using As Electrolyte Sr‐ And Mg‐Doped Lagao3, Kevin Huang, Man Feng, John B. Goodenough, Christopher Milliken Oct 1997

Electrode Performance Test On Single Ceramic Fuel Cells Using As Electrolyte Sr‐ And Mg‐Doped Lagao3, Kevin Huang, Man Feng, John B. Goodenough, Christopher Milliken

Faculty Publications

The electrode performance of a single solid oxide fuel cell was evaluated using a 500 μm thick La0.9Sr0.1Ga0.8Mg0.2O2.85 (LSGM) as the electrolyte membrane. Comparison of La0.6Sr0.4CoO3-δ (LSCo) and La0.9Sr0.1MnO3 (LSM) as cathodes showed LSCo gave an exchange current density two orders of magnitude higher than that of LSM. Comparison of CeO2/Ni and LSGM/Ni as anodes showed a degradation of the latter with time, and studies of the anode‐electrolyte ...


Ole Miss Engineer 1997 Oct 1997

Ole Miss Engineer 1997

The Ole Miss Engineer

No abstract provided.


Optimization Of Microstructure Development During Hot Working Using Control Theory, James C. Malas Iii, W. Garth Frazier, S. Venugopal, Enrique A. Medina, Steven Madeiros, Raghavan Srinivasan, R. Dennis Irwin, W. M. Mullins, Anil Chaudhary Sep 1997

Optimization Of Microstructure Development During Hot Working Using Control Theory, James C. Malas Iii, W. Garth Frazier, S. Venugopal, Enrique A. Medina, Steven Madeiros, Raghavan Srinivasan, R. Dennis Irwin, W. M. Mullins, Anil Chaudhary

Mechanical and Materials Engineering Faculty Publications

A new approach for controlling microstructure development during hot working processes is proposed. This approach is based on optimal control theory and involves state-space type models for describing the material behavior and the mechanics of the process. The effect of process control parameters such as strain, strain rate, and temperature on important microstructural features can be systematically formulated and then solved as an optimal control problem. This method has been applied to the optimization of grain size and process parameters such as die geometry and ram velocity during the extrusion of plain carbon steel. Experimental results of this investigation show ...


Applying Virtual Reality Techniques To Sensitivity-Based Structural Shape Design, Tsung-Pin Yeh, Judy M. Vance Sep 1997

Applying Virtual Reality Techniques To Sensitivity-Based Structural Shape Design, Tsung-Pin Yeh, Judy M. Vance

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Virtual reality (VR) provides a design space consisting of three-dimensional computer images where participants can interact with these images using natural human motions in real time. In the field of engineering design, prototyping and design verification have provided the initial application areas for VR. The research presented in this paper takes the scenario one step further by incorporating free-form deformation techniques and sensitivity analysis into the virtual world such that the designer can easily implement analysis-based shape design of a structural system where stress considerations are important. NURBSbased free-form deformation (NFFD) methods and direct manipulation techniques are used as the ...


High-Frequency Response Of Atomic-Force Microscope Cantilevers, Joseph A. Turner, Sigrun Hirsekorn, Ute Rabe, Walter Arnold Aug 1997

High-Frequency Response Of Atomic-Force Microscope Cantilevers, Joseph A. Turner, Sigrun Hirsekorn, Ute Rabe, Walter Arnold

Faculty Publications from the Department of Engineering Mechanics

Recent advances in atomic-force microscopy have moved beyond the original quasistatic implementation into a fully dynamic regime in which the atomic-force microscope cantilever is in contact with an insonified sample. The resulting dynamical system is complex and highly nonlinear. Simplification of this problem is often realized by modeling the cantilever as a one degree of freedom system. This type of first-mode approximation (FMA), or point-mass model, has been successful in advancing material property measurement techniques. The limits and validity of such an approximation have not, however, been fully addressed. In this article, the complete flexural beam equation is examined and ...


Rapid Analysis Of Wood Using Transient Infrared Spectroscopy And Photoacoustic Spectroscopy With Pls Regression, Stanley J. Bajic, Roger W. Jones, John F. Mcclelland, Bonnie R. Hames, Robert R. Meglen Aug 1997

Rapid Analysis Of Wood Using Transient Infrared Spectroscopy And Photoacoustic Spectroscopy With Pls Regression, Stanley J. Bajic, Roger W. Jones, John F. Mcclelland, Bonnie R. Hames, Robert R. Meglen

Ames Laboratory Conference Papers, Posters, and Presentations

In the forest products industry, improved methods are needed for rapid analysis of wood and paper products. Currently, the best methods for determining chemical and physical properties of wood-based materials require considerable sample preparation and analysis time. Consequently, quantitative information is often not obtained on a time scale suitable for process monitoring, control, and quality assurance. The primary barriers to practical utilization of conventional infrared methods are the opaqueness and poor reflection properties of the wood-based materials. This paper demonstrates how photoacoustic and transient infrared spectroscopies have been combined with chemometric techniques to overcome the limitations of conventional infrared spectroscopies ...


The Lagrangian Spectral Relaxation Model Of The Scalar Dissipation In Homogeneous Turbulence, Rodney O. Fox Aug 1997

The Lagrangian Spectral Relaxation Model Of The Scalar Dissipation In Homogeneous Turbulence, Rodney O. Fox

Rodney O. Fox

Lagrangian pdf methods are employed to extend the spectral relaxation (SR) model of the scalar dissipation of an inert, passive scalar (1⩽Sc) in homogeneous turbulence. The Lagrangian spectral relaxation (LSR) model divides wavenumber space into a finite number (the total number depending on the Taylor-scale Reynolds numberRλ and the Schmidt number Sc) of wavenumber bands whose time constants are determined from the mean turbulent kinetic energy and instantaneous turbulent energy dissipation rate. The LSR model accounts for the evolution of the scalar spectrum (viz., pdf) from an arbitrary initial shape to its fully developed form. The effect of turbulent-frequencyfluctuations ...


The Study Of Wave-Blocking And Current Effects On Nonlinear Interactions Of Shallow-Water Waves Using Advanced Boussinesq Models, Qin Chen Jul 1997

The Study Of Wave-Blocking And Current Effects On Nonlinear Interactions Of Shallow-Water Waves Using Advanced Boussinesq Models, Qin Chen

Civil & Environmental Engineering Theses & Dissertations

The first part of this work focuses on the derivation of enhanced Boussinesq-type equations for the combined motion of waves and currents in shallow water areas.

The strategy proposed in this work is to couple two known methods which are the sponge layer concept suitable for short waves and Sommerfeld radiation condition for currents. This coupling method provides satisfactory non-reflective boundaries for the simulation of fully coupled wave/current motion as demonstrated by the numerical experiments. We verify the model against the well known solutions based on the existing theories and good agreement has been observed. The numerical results confirm ...


High-Order Finite-Difference Schemes And Their Application To Computational Acoustics, Joe Leo Manthey Jul 1997

High-Order Finite-Difference Schemes And Their Application To Computational Acoustics, Joe Leo Manthey

Mathematics & Statistics Theses & Dissertations

The primary focus of this study is upon the numerical stability of high-order finite-difference schemes and their application to duct acoustics. Since acoustic waves are known to be non-dissipative and non-dispersive, high-order schemes are favored for their low dissipation and low dispersion relative to the low-order schemes. The primary obstacle to the the development of explicit high-order finite-difference schemes is the construction of boundary closures which simultaneously maintain the formal order of accuracy and the numerical stability of the overall scheme. In this thesis a hybrid seven-point, fourth-order stencil for computing spatial derivatives is presented and the time stability is ...


Computer-Aided Design Of Coupler-Driven Watt I And Tolerance Synthesis For Four-Bar Linkages, Haitao Li Jul 1997

Computer-Aided Design Of Coupler-Driven Watt I And Tolerance Synthesis For Four-Bar Linkages, Haitao Li

Mechanical & Aerospace Engineering Theses & Dissertations

Theory to rectify circuit defects in rocker-crank and double-rocker at the synthesis level is described based on the angular joint displacements. It complements the crank-rocker and double-crank circuit rectification to complete the circuit rectification of four-bar linkages. The procedure utilizes the algebraic method where special points followed by a line construction procedure are employed to validate the range of the critical angle that can identify the circuit defects as a function of the design positions prior to the completion of the linkage.

A complete procedure of the rectified synthesis of the coupler-driven Watt I six-bar linkage to pass through the ...


Development Of A Mechatronics Design Studio, Sema E. Alptekin Jun 1997

Development Of A Mechatronics Design Studio, Sema E. Alptekin

Industrial and Manufacturing Engineering

Mechatronics is a combination of mechanics, electronics and information technology intended to raise the intelligence level and flexibility of products and devices. There is a need to develop programs and laboratories in Mechatronics to create an understanding of how new technologies influence the traditional methods of designing products and manufacturing systems. A model "Mechatronics Design Studio" has recently been developed to support the Mechatronics and Manufacturing Automation courses offered at Cal Poly's Industrial and Manufacturing Engineering Department. Laboratory experiments have been developed and several student projects have been completed. In this paper, an overview of the design studio and ...