Engineering Commons^™

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.

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.

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 …

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.

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. …

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.

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 …

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 …

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.

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 …

Use Of Time Varying Dynamics In Neural Network To Solve Multi-Target Classification, S. N. Balakrishnan, J. Rainwater

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Several types of solutions exist for multiple target tracking. These techniques are computation-intensive and in some cases very difficult to operate online. The authors report on a backpropagation neural network which has been successfully used to identify multiple moving targets using kinematic data (time, range, range-rate and azimuth angle) from sensors to train the network. Preliminary results from simulated scenarios show that neural networks are capable of learning target identification for three targets during the time period used during training and a time period shortly after. This effective classification period can be extended by the use of networks in coordination …

Moving Object Recognition And Guidance Of Robots Using Neural Networks, Abhijit Neogy, S. N. Balakrishnan, Cihan H. Dagli

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The design of a robust guidance system for a robot is discussed. The two major tasks for this guidance system are the online recognition of a moving object invariant to rotation and translation, and tracking the moving object using a neural-network-driven vision system. This system included computer software ported to the IBM PC and interfaced with an IBM 7535 robot. The operation of this guidance system involved recognition of a moving object and the ability to track it till the robot and effector was in close proximity of the object. It was found that the robot was able to track …

Machining Of Composite Materials. Part Ii: Non-Traditional Methods, Serge Abrate, D. Walton

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Machining of composite materials is difficult due to the heterogeneity and heat sensitivity of the material and the high abrasiveness of the reinforcing fibers. This results in damage being introduced into the workpiece and very high tool wear. The use of traditional machining methods was reviewed in Part I of this paper. Here new methods are considered: laser, waterjet, electro-discharge, electro-chemical spark, and ultrasonic machining. These various techniques have been applied to organic matrix composites with aramid, glass, graphite fiber reinforcement but also to metal matrix and ceramic matrix composites. © 1992.

Effect Of Temperature On The Ultimate Strength And Modulus Of Whisker‐Reinforced Ceramics, Douglas R. Carroll, Lokeswarappa R. Dharani

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Whiskers are a very attractive means of reinforcing a ceramic material. It has been shown that the whiskers dramatically improve the ultimate strength and modulus of the materials at room temperature. However, recent studies indicate that at high temperatures the improvement is less pronounced, or there is no improvement at all. In this paper a model is developed to explain why the properties are degraded at high temperature. The parameters which seem most important for high‐temperature performance are the coefficients of thermal expansion and Poisson's ratios for the constituents, the heat treatment temperature, and the coefficient of friction between the …

Analysis Of Shear Bands In Simple Shearing Deformations Of Nonpolar And Dipolar Viscoplastic Materials, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

During the past few years, we have studied numerically the initiation and growth of shear bands in nonpolar and dipolar viscoplastic materials being deformed in simple shear, and in nonpolar materials undergoing plane strain deformations. We summarize here our work for the former problem. © 1992 American Society of Mechanical Engineers.

Genericity And Singularities Of Robot Manipulators, Ming-Chuan Leu, D. K. Pai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The kinematic singularities of robot manipulators are studied from the point of view of the theory of singularities. The notion of a "generic'' kinematic map, whose singularities form smooth manifolds of prescribed dimension in the joint space of the manipulator, is examined. For three-joint robots, an equivalent algebraic condition for genericity using the Jacobian determinants is derived. This condition lends itself to symbolic computation and is sufficient for the study of decoupled manipulators. Orientation and translation singularities of manipulators are studied in detail. A complete characterization of orientation singularities of robots with any number of joints is given. The translation …

A Complete Model Characterization Of Brushless Dc Motors, N. Hemati, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The authors address the modeling problem associated with brushless DC motors (BLDCMs) with nonuniform air gaps that operate in a range where magnetic saturation may exist. The mathematical model includes the effects of reluctance variations as well as magnetic saturation to guarantee proper modeling of the system. An experimental procedure is developed and implemented in a laboratory environment to identify the electromagnetic characteristics of a BLDCM in the presence of magnetic saturation. It is demonstrated that the modeling problem associated with the class of BLDCMs can be formulated in terms of mathematically modeling a set of multidimensional surfaces corresponding to …

Machining Of Composite Materials. Part I: Traditional Methods, Serge Abrate, D. A. Walton

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Composite materials are more difficult to machine than metals mainly because they are anisotropic, non-homogeneous and their reinforcing fibers are very abrasive. During machining, defects are introduced into the workpiece, and tools wear rapidly. Traditional machining techniques such as drilling or sawing can be used with proper tool design and operating conditions. A review of traditional machining methods applied to organic and metal matrix composites is presented in this article. The use of non-traditional machining methods such as waterjet, laser and ultrasonic machining will be discussed in the second part. © 1992.

Hydration Behavior Of Laser Dye Aerosols Of Mixed Composition Having High Critical Supersaturations, Max B. Trueblood, Donald E. Hagen, Darryl J. Alofs

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This Study Concerns Aerosol Particles of Mixed Composition. the Particles Contain a Water Insoluble Core (Polystyrene Latex), Surrounded by a Water Soluble Shell (Various Fluorescent Dyes). a Collison Nebulizer and an Electrostatic Aerosol Classifier Are Used to Prepare the Aerosol; its Critical Supersaturation Spectrum is Measured with a Diffusion Cloud Chamber. Experiments Were Done using Four Different Dyes (Disodium Fluorescein, Sulforhodamine 640, Sulforhodamine B and Rhodamine 560 Chloride) with Five Different Polystyrene Latex Sphere Sizes. the Results Indicate that a Kohler-Type Behavior is Obeyed. This Technique of Putting a Soluble Coating Onto an Insoluble Core is Found to Be a …

Hierarchical Neurocontroller Architecture For Robotic Manipulation, Xavier J. R. Avula, Luis C. Rabelo

Chemical and Biochemical Engineering Faculty Research & Creative Works

A hierarchical neurocontroller architecture consisting of two artificial neural network systems for the manipulation of a robotic arm is presented. The higher-level network system participates in the delineation of the robot arm workspace and coordinates transformation and the motion decision-making process. The lower-level network provides the correct sequence of control actions. A straightforward example illustrates the architecture''s capabilities, including speed, adaptability, and computational efficiency

Extension Of Vlasov’S Semi-Membrane Theory To Reinforced Composite Shells, Victor Birman

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Governing equations for the statics and dynamics of reinforced composite shells are developed based on Vlasov's semi-membrane shell theory. These equations have closed-form solutions illustrated for buckling and free vibration problems. The buckling solution converges to the known result for unstiffened isotropic shells. © 1992 by ASME.

Consideration Of Phase Transformations In The Study Of Shear Bands In A Dynamically Loaded Steel Block, Z. G. Zhu, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We study plane strain thermomechanical deformations of a square block made of steel and model a material defect in it by a rigid non-heat-conducting ellipsoidal inclusion located at the center of the block. The boundaries of the block are presumed to be thermally insulated, and its top and bottom surfaces compressed vertically at a prescribed rate. The loading pulse is assumed to be made up of three parts; an initial segment in which the speed increases from zero to the steady value, the steady part, and the third part in which the speed decreases gradually to zero and is maintained …

Planning And Control Of A Robotic Manipulator Using Neural Networks, Xavier J. R. Avula, Heng Ma, Anil Malkani, Jay-Shinn Tsai, Luis C. Rabelo

Chemical and Biochemical Engineering Faculty Research & Creative Works

An architecture which utilizes two artificial neural systems for planning and control of a robotic arm is presented. The first neural network system participates in the trajectory planning and the motion decision-making process. The second neural network system provides the correct sequence of control actions with a high accuracy due to the utilization of an unsupervised/supervised neural network scheme. The utilization of a hybrid hierarchical/distributed organization, supervised/unsupervised learning models, and forward modeling yielded an architecture with capabilities of high level functionality.

Transition From Laminar To Turbulent Flow Around An Airfoil, Chang-Ren Chen

Doctoral Dissertations

"A computational fluid dynamics (CFD) code has been developed for two-dimensional incompressible turbulent flows and employed to solve the Navier Stokes equations around an airfoil of arbitrary shape. A low-Reynolds-number k — e turbulence model including curvature effect was used to consider the gain and loss of turbulent kinetic energy. To include laminar sublayer into the computational domain, a multi-layer grid and a cubic-slpine grid were introduced through a conservative form of coordinate transformation. The flow structure varies with the Reynolds numbers. For an airfoil at low Reynolds numbers (below ten thousand), distinct vortex shedding patterns can be found in …