Engineering Commons^™

Solutions Of The Heat Conduction Equation In Multilayers For Photothermal Deflection Experiments, William A. Mcgahan, Kevin D. Cole

Department of Mechanical and Materials Engineering: Faculty Publications

Exact expressions are presented for the deflection of a laser beam passing parallel to and above the surface of a sample heated by a periodically modulated axisymmetric laser beam. The sample may consist of any number of planar films on a thick substrate. These exact expressions are derived from a local Green’s function treatment of the heat conduction equation, and contain an exact analytical treatment of the absorption of energy in the multilayered system from the heating laser. The method is based on calculation of the normal component of the heat fluxes across the layer boundaries, from which either the …

Neural Modeling And Control Of A Distillation Column, James Edward Steck, K. Krishnamurthy, Bruce M. Mcmillin, Gary G. Leininger

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Control of a nine-stage three-component distillation column is considered. The control objective is achieved using a neural estimator and a neural controller. The neural estimator is trained to represent the chemical process accurately, and the neural controller is trained to give an input to the chemical process which will yield the desired output. Training of both the neural networks is accomplished using a recursive least squares training algorithm implemented on an Intel iPSC/2 multicomputer (hypercube). Simulated results are presented for a numerical example.

Runge-Kutta Upwind Multigrid Multi-Block Three-Dimensional Thin Layer Navier-Stokes Solver, Frank E. Cannizzaro

Mechanical & Aerospace Engineering Theses & Dissertations

A state-of-the-art computer code has been developed that incorporates a modified Runge-Kutta time integration scheme, Upwind numerical techniques, Multigrid acceleration, and Multi-block capabilities (RUMM). A three-dimensional thin-layer formulation of the Navier-Stokes equations is employed. For turbulent flow cases, the Baldwin-Lomax algebraic turbulence model is used. Two different upwind techniques are available, van Leer's flux-vector splitting and Roe's flux-difference splitting. Full approximation multigrid plus implicit residual and corrector smoothing were implemented to enhance the rate of convergence. Multi-block capabilities were developed to provide geometric flexibility. This feature allows the developed computer code to accommodate any grid topology or grid configuration with …

Experimental Investigation Of Crossflow Instability Waves In Rotating Disk Flow, Alan E. Blanchard

Mechanical & Aerospace Engineering Theses & Dissertations

For the past 40 years, the crossflow (or inflectional) instability associated with rotating disk flow has been generally assumed to be a pure vortex that is fixed with respect to the disk; however, the terms "wave" and "vortex" have also been used interchangeably throughout the computational and experimental literature to describe this instability. Through the use of both hot-wire surveys and smoke-wire flow visualizations in the present investigation, the existence of crossflow instability waves prior to vortex formation has been shown. The results of the hot-wire surveys and smoke-wire flow visualizations for both a "clean" disk case and a disk …

Dynamics And Control Of A Five Degree-Of-Freedom Magnetic Suspension System, Anwar Mohammed Haj

Mechanical & Aerospace Engineering Theses & Dissertations

A large-gap magnetic suspension system with five degrees-of-freedom is presented. The system is multi-input multi-output with coupling between degrees-of-freedom. Simulation was performed on this multi degree-of-freedom system in order to control each degree-of-freedom separately. Two types of controllers are considered by adding white noise to a single degree-of-freedom system in order to test their behavior and determine which is the best choice for the system. The responses of the system are produced in continuous and discrete time where a sample interval and delay time was introduced. Using these responses, a comparison between each degree-of-freedom was made and the maximum value …

Laminar And Turbulent Natural Convection Heat Transfer In Trombe Wall Channels, Tony D. T. Chen

Mechanical & Aerospace Engineering Theses & Dissertations

The natural convective heat transfer and air movement in a Trombe wall solar passive system has been studied analytically and numerically. Three Trombe wall channel geometries including the parallel channel with axial inlet and exit, parallel channel with side vents and Trombe wall channel coupled to the room have been considered. Several models representing these Trombe wall geometries have been formulated. For the parallel channel with axial inlet and exit geometry, a momentum-integral method has been used to solve parabolic governing equations for two-dimensional laminar flow. This formulation leads to a second order ordinary differential equation for pressure defect in …

Measurement Of Thermal-Energy Charge-Transfer Rate Coefficient Of Mo6+ And Argon, Victor H.S. Kwong, Z. Fang, Yingtao Jiang, T. T. Gibbons, L. D. Gardner

Electrical & Computer Engineering Faculty Research

The charge-transfer rate coefficient of Mo6+ and argon has been measured at mean ion energies of 8.8 and 1.4 eV using a laser-ablation ion source and an ion trap. The rate coefficient deduced from these measurements is 1.02(0.10)×10-10 cm3 s-1 and appears to be independent of the mean ion energy at this energy range. However, the measured value is an order of magnitude smaller than the Langevin rate coefficient.

Fsec 3.0: Florida Software For Enervironment Computation: V3.0 Draft User's Manual. 01-92, Florida Solar Energy Center, Alp Kerestecioglu

FSEC Energy Research Center®

FSEC 3.0 was developed to support research. It is a general-purpose software package especially designed to simulate complex building science problems. The program offers several unique features.

The major feature is its ability to solve user-defined systems of governing equations. Up to 250 coupled differential equations and their corresponding boundary conditions may be either selected from libraries or defined by the user. The equations may be linear or nonlinear; spatially-lumped or spatially-distributed; steady-state or transient; ordinary or partial. The structure of the software also allows users to incorporate their own routines or programs. Thus, researchers may define their specific problem …

Experimental Measurement Of Rov Tether Tension, Tim W. Mclain, S M. Rock

Faculty Publications

In the undersea operation of a tethered ROV system, the pilot's ability to control precisely the ROV is often limited by disturbance forces generated by drag due to currents that act either directly on the ROV or indirectly on the ROV through the tether. The objective of this research, which was conducted at the Monterey Bay Aquarium Research Institute (MBARI), was to characterize the magnitude and dynamics of tether forces by measuring them during operation. To achieve this, a tether tension sensor and data logging system were developed. This system was used to measure the forces in the tether of …

A Virtual-System Concept For Exergy Analysis Of Flow Network Plant; Part I: Principles, Jim Mcgovern, Francis O'Toole

Conference Papers

A new type of virtual system, named a flow constraint system (FCS), is proposed to facilitate, clarify, and simplify exergy analyses of plant that involve material flow networks. The need for the virtual system is outlined and the concept is demonstrated by applying it to a CHP steam cycle. The FCS concept allows the physical constraints on the exergy interactions associated with flow streams to be taken into account fully. It also simplifies the treatment of bifurcations in material flows and considerably reduces the need for absolute exergy evaluations. The new concept follows from the work already published by the …

A Virtual-System Concept For Exergy Analysis Of Flow Network Plant; Part Ii: Exergetic And Exergonomic Analysis Illustration, Jim Mcgovern, Francis O'Toole

Conference Papers

This paper is a continuation of Part I — Principles, to which it refers extensively. The virtual system concept and the methodology introduced in Part I are illustrated by means of a numerical example. This is an exergetic and exergoeconomic analysis of the CHP steam plant that was described in Part I without operating values and parameters. Matrix methods developed by Valero et al. (1986) are adapted to the new concept. It is shown that these methods are made simpler and less subjective. Bond-graph-type diagrams for exergetic and economic costs are presented.

Interface Cavitation Damage In Polycrystalline Copper, Brent L. Adams, David P. Field

Faculty Publications

The authors acknowledge the support of the Office of Basic Energy Sciences of the United States Department of Energy. Determination of an interface damage function (IDF) from a stereological procedure similar to that presented by Hilliard is described. The mathematical and experimental simplicity of the method is utilized in measuring an IDF for polycrystalline copper crept at 0.6T sub m under uniaxial tension. Whereas previous work focused on a five parameter description of the local state of a grain boundary, the domain of the IDF is increased to eight degrees of freedom in the present study to include the complete …

Investigation Of Waterjet-Workpiece Interaction, Hung-Yuan Li

Dissertations

The objective of this research is to develop new knowledge related to the fundamental physical phenomena of waterjet machining of ductile materials, and to use this knowledge to construct a numerical analysis model. The resulting knowledge will enable enhancement of waterjet cutting efficiency.

Experimental study of fundamental mechanisms and the acquisition of the data detailing micro and macro scale phenomena which occur during the machining process is carried out. It is shown that the material damage mechanism associated with waterjet machining is erosion cavitation which initiates ultrasonic stress wave propagation in the workpiece. Fatigue, an important element in producing material …

Development Of Prediction Technique For The Geometry Of The Abrasive Waterjet Generated Kerf, Yichung Chung

Dissertations

This study is concerned with the development of a practical and accurate technique for off-line determination of the variables characterizing the macro-geometry of the kerf generated in the course of abrasive waterjet (AWJ) machining of ductile materials. The study involved generation and processing of a database relating operational conditions with kerf dimensions. The total number of generated samples exceeded 1500.

A physical model relating the process results with operational conditions was constructed and used for the selection of a statistical technique for analysis of the acquired experimental information. The semiempirical model developed here is based on a simple theoretical model …

Particle Dynamics Modeling Of Boundary Effects In Granular Couette Flow, Hyeong-Jin Kim

Dissertations

This study provides insights in understanding boundary effects on the flow of dry granular materials composed of identical, smooth, inelastic spheres between parallel, bumpy walls in the absence of gravity. The results of this study are useful in providing a basis upon which developing theories can be modified as well as substantiating previous and current experiments. This in turn has a major importance in many industries which are concerned with handling of particulates, such as coal, mineral processing, powder metallurgy, and agriculture.

The particle dynamics or discrete element method is used to model this flow, thereby providing a means of …

Structural Reliability Using Finite Element Method, Che-Chen Liou

Dissertations

During the last decade, structural reliability theory has been treated in a large number of research papers; therefore, from being a subject only well known by a relatively small number of researchers, it has become an important engineering discipline. From the application point of view, many practical applications have been made successfully.

In this dissertation some important fundamental concepts in statistics and in reliability theory are presented. The concept of failure mode can be defined as: A set of failed elements turn a structure into a mechanism. Usually, a structure has many possible failure modes; therefore, it will be necessary …

Local Stress Due To A Radial Loading At Nozzle-Pipe Connection With Different Thickness, Guosheng Lu

Theses

This thesis presents an analysis using the finite element method of the local stress at the nozzle and pipe connection subjected to a radial loading.

In this study, the local stress factor (for membrane and bending stresses) is presented in a series of plots with beta (nozzle radius/pipe radius) values ranging from 0.1 to 1.0 and gamma (pipe radius/wall thickness) values ranging from 10 to 100. The membrane and bending stresses in longitudinal and circumferential directions of the run pipe are computed as a function of the dimensionless parameters, beta and gamma.

For a given external radial loading with different …

Computational Aspects Of A Three Dimensional Non-Intrusive Particle Motion Tracking System, Avadhani S. Ashok

Theses

Development of a technique for non-intrusive particle motion tracking in three dimensions is considered. This technique is based on the principle of magnetic induction. In particular, the determination of the position and onentation of the particle from the information gathered is the pnncipal focus of this thesis. The development of such a system is motivated by the need to understand the flow patterns of granular material. This is of cntical importance in dealing with problems associated with bulk solids flows which occur in almost all industries and in natural geological events. A study of the current diagnostic techniques reveals the …

Design Of A Material Handling System For The Automatic Assembly Of A Shower Head, Irshad Meherally

Theses

The design of a Material Handling System for the Shower Head assembly is proposed. The working principle of complete automation and individual workstation is presented using "I-DEAS" software. Alternative equipments and their usage in the automation of the assembly is also proposed. Custom made fixtures, workcarriers, orienters, magazines, part feeders are designed for the assembly. Analysis of design for assembly in terms of cost and efficiency is performed by generating a Coding System Technique.

Effectiveness Of Additive Correction Multigrid In Numerical Heat Transfer Analysis When Implemented On An Intel Ipsc2, James D. Padgett

Dissertations and Theses

The effectiveness of the Additive Correction Multigrid (ACM) algorithm, a line-byline Tri-diagonal Matrix Algorithm (TDMA), and simple Gauss-Seidel (GS) iteration in numerical heat transfer analysis is investigated on a conventional single processor computer and on a distributed memory parallel computer. The performance of these methods is studied by solving a two-dimensional, steady heat conduction problem. The execution time of ACM on a single processor is proportional to the number of unknowns to the 1.5 power. This is in contrast to the execution time of the TDMA for which the execution time is proportional to the number of unknowns to the …

The Simulation Of Tool Path Generation In Milling For Machining Processes, Rickey W. Jennings

Opportunities for Undergraduate Research Experience Program (OURE)

This paper is a report on the progress of this project to create a complete CAD/CAM system. The paper describes the introduction to the simulation package called Vericut. It also discusses the integration of the three packages: AutoCad version 11, PCAPT with APTGEN, and Vericut. The progress of the project to this point is only to the integration of the three packages. The paper also indicates the work which still needs to be completed. The key point of which is the menu system which is the final step in the project.

Member Stiffness And Contact Pressure Distribution Of Bolted Joints, Matthew L. Mckay

Opportunities for Undergraduate Research Experience Program (OURE)

Member stiffness and the stress distributions in the bolts and members of bolted joints have been calculated for various bolt sizes, as well as thicknesses and materials of the members. The finite element method has been used to calculate the displacements and the stress distributions in the components of the bolted joint Using axisymmetric elements, the bolted joint could be analyzed as a two dimensional problem. Member stiffness ratios were calculated from the finite element results and compared with those calculated by an existing commonly used theory. The values were comparable for conditions where the theory could be applied. In …

Head-Spine Finite Element Computer Model On A Work-Station, Kay F. Schilli

Opportunities for Undergraduate Research Experience Program (OURE)

In this project, the head-cervical spine finite element computer model has been modified and made portable on the Apollo work-station. The program was developed to aid the researcher in analyzing the simulated behavior of the human spine. The modifications in the computer program have been made in order to utilize the finite element code for continuation of further research.

Static And Dynamic Testing Of Serpentine Belt Drive Tensioners, John W. Minor

Opportunities for Undergraduate Research Experience Program (OURE)

Serpentine belt drive tensioners are used in virtually every model of automobile produced today. Limited testing has been done to see how the tensioner performs under certain situations. In each case outside influences were either not accounted for or considered not to influence the way the tensioner performed in a given situation. By developing new ways of testing tensioners for static and dynamic characteristics separately, the influence each trait has on the performance of the tensioner can be exactly gauged.

Computer Modeling Of A Liquid Fuel Spray, Clement R. Goodin Jr.

Opportunities for Undergraduate Research Experience Program (OURE)

This project was designed to find an accurate and convenient method of computing fuel spray parameters. The project centers around an experimental setup which basically fires a laser beam through a fuel spray mist. A concentric ring detector then measures energy from the scattered light.

A computer code was written which solves a governing equation to give computed values of the energy from scattered light. Comparison of the experimental energy and the computed energy tells how well the fuel parameters of the computer model matches those of the real spray of the experiment. An iteration technique then manipulates the computer …

Behavior Of Composites For The Nasp Project, Robert B. Stone

Opportunities for Undergraduate Research Experience Program (OURE)

It is well known that ceramics are strong, highly heat resistant, refractory materials. Unfortunately, they are brittle and fail catastrophically. However, the strength as well as fracture toughness of ceramics can be greatly improved with the addition of continuous fibers, thus obtaining ceramic matrix composites (CMC). Normally the addition of aligned continuous fibers to a matrix degrades the transverse (the direction 90° to the fiber axes) properties while greatly improving the longitudinal properties. It has been shown that the addition of whiskers to a continuous fiber CMC will improve moduli and strength properties in both the transverse and longitudinal directions. …

Thermal Buckling Of Composite Tubes, S. Fulkerson

Opportunities for Undergraduate Research Experience Program (OURE)

The object was to design and initiate the use of a fixture capable of testing for pre-buckling deflections in a composite tube under thermal loading. The fixture is to be used on a continuing basis to test three types of composites: (1) glass/epoxy, (2) Kevlar/epoxy, and (3) graphite/epoxy. The course of action chosen was to adapt a fixture designed by Tim Streb and Steve Fulkerson in the spring of 1991. The fixture was completed, and one test was performed. An added responsibility was to initiate a course of action such that the volumetric percentage of fiber in the composite may …

Thermally Induced Stresses In Micro-Chip Mounting Devices, K. J. Mikulcik

Opportunities for Undergraduate Research Experience Program (OURE)

Microchip thermal stress due to the temperature change related to the mounting of a chip to its lead frame was investigated by moire interferometry. Large scale models were made, and the problems of applying a grating to this model at high temperature were addressed without success. Further possibilities, however, remain to be attempted. Moire interferometry was successfully used at room temperature by examining mechanically relieved residual stresses. The results agreed with an analytical approach to stress analysis and also to a finite element analysis. A practical solution to the problem of peeling was found.

Instant Centers Of Velocity In A Kinematically Intelligent Blackboard Environment, R. Jeff Fensterman

Opportunities for Undergraduate Research Experience Program (OURE)

This project was part of a continuing expansion of a graphical software environment called "Skimp”, originally developed by Dr. J. K. Nisbett.[l] The final version of this software package will allow the kinematic concepts of an introductory machine dynamics class to be taught exclusively on a blackboard sized projected computer screen. This software package will be used as a teaching aid in the classroom as well as a tutorial for students outside the classroom.

The scope of this project was limited to the concept of instant centers of velocity. This portion is a subroutine accessible during the regular execution of …

Simplified Sizing Procedure For Solar Domestic Hot Water Systems, Florida Solar Energy Center, Public Information Office

FSEC Energy Research Center®

This procedure was developed to size residential solar water heating systems in Florida.