Engineering Commons^™

Analysis Of Shear Banding In Plane Strain Compression Of A Bimetallic Thermally Softening Viscoplastic Body Containing An Elliptical Void, Z. G. Zhu, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We study plane strain thermomechanical deformations of a prismatic viscoplastic body of square cross-section and deformed at a nominal strain-rate of 5000 s-1. The body has two thin layers placed symmetrically about the horizontal centroidal axis and an elliptical void at the center. The major axis of the void coincides with the vertical centroidal axis and also with the direction of loading. The layer material differs from that of the body in only the value of the yield stress in a quasistatic simple compression test. The yield stress for the layer material is taken to be either one-fifth or five …

Matrix Cracking In Laminated Composites: A Review, Serge Abrate

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This article presents an overview of the problem of matrix cracking in laminated composite materials. The parameters governing the onset and accumulation of internal damage under several types of loadings are reviewed. The analysis of laminates with matrix cracks can be performed using a shear-lag model, variational, elasticity, finite element or finite difference approaches. Prediction of further cracking is based on either a fracture mechanics approach or a probabilistic failure strength theory. Continuum damage mechanics are used by some investigators to model the behavior of the cracked laminate. Recent developments in this area are summarized here, and suggestions for future …

Dynamic Adiabatic Shear Band Development In A Bimetallic Body Containing A Void, R. C. Batra, Z. G. Zhu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We study the problem of the initiation and subsequent growth of a shear band in a thermally softening viscoplaslic prismatic body of square cross-section and containing two symmetrically placed thin layers of a different viscoplastic material and an elliptical void at the center. The yield stress of the material of the thin layer in a quasistatic simple compression test is taken to be either five times or one-fifth that of the matrix material. The body is deformed in plane strain compression at a nominal strain rate of 5.000 s '. These deformations are assumed to be symmetrical about the centroidal …

Linear Interpolation Lattice, Cameron K. Coursey, John A. Stuller

Electrical and Computer Engineering Faculty Research & Creative Works

The Well-Known Analysis and Synthesis Filters of Linear Prediction Theory Are Extended Here to Include Linear Interpolation. © 1991 IEEE

Positron Study Of Defects And Diffusion Induced Grain Boundary Migration In A Pb-Sn System, A. Belaidi, Hollis P. Leighly, H. Aourag, B. Khelifa, M. Oubadi, A. Elias

Materials Science and Engineering Faculty Research & Creative Works

The Pb-Sn system discloses a remarkable effect at the intermediate α → α + β phase boundary. The observation of the sharp transient peak in the S-parameter curve which is analogous to those found in thermal capacity curves is, as far as the authors are aware, unique in such positron measurements. This effect is interpreted in terms of positron trapping in defects associated with the strains accompanying the initial stage of transformation. This short note offers a new approach to the underlying phenomenon published in J. Phys. F. Met. Phys., 12 (1982) 813 by A. Belaidi, H. P. Leighly Jr. …

Electrical Conductivity, Seebeck Coefficient And Defect Chemistry Of Ca-Doped Ycro3, G. F. Carini, Harlan U. Anderson, Don M. Sparlin, M. M. Nasrallah

Materials Science and Engineering Faculty Research & Creative Works

The electrical transport behavior and defect structure of Ca-doped YCrO₃ were studied using electrical conductivity and Seebeck coefficient measurements as a function of oxygen activity and temperature. Defect models derived from the electrical conductivity data were found to adequately relate the concentration of charge carriers to the acceptor dopant and oxygen vacancy concentrations. Thermodynamic properties were calculated and found to be consistent with the model. Activation energy and carrier mobility data were also obtained. The analysis of the electrical conductivity, Seebeck and mobility data suggest that the conduction process in Ca-doped YCrO₃ occurs via the small polaron hopping …

Defect Structure, Nonstoichiometry, And Phase Stability Of Ca-Doped Ycro3, G. F. Carini, Harlan U. Anderson, M. M. Nasrallah, Don M. Sparlin

Materials Science and Engineering Faculty Research & Creative Works

The dependence of the defect structure of Ca-doped YCrO₃ on oxygen activity and temperature was investigated by high temperature thermogravimetric measurements. Defect models developed from electrical conductivity data obtained in a previous study were used to interpret the thermogravimetric data. A correlation was found between the electrical conductivity and the thermogravimetric data which suggested that these data were concomitantly dependent on the acceptor dopant and oxygen vacancy dependance of the thermodynamic parameters. Kröger-Vink type diagrams showing the regions of stability with respect to oxygen activity and temperature were constructed. The TGA data show that Ca-doped YCrO₃ is even …

Intelligent Control Of A Robotic Arm Using Hierarchical Neural Network Systems, Xavier J. R. Avula, Luis C. Rabelo

Chemical and Biochemical Engineering Faculty Research & Creative Works

Two artificial neural network systems are considered in a hierarchical fashion to plan the trajectory and control of a robotic arm. At the higher level of the hierarchy the neural system consists of four networks: a restricted Coulomb energy network to delineate the robot arm workspace; two standard backpropagation (BP) networks for coordinates transformation; and a fourth network which also uses BP and participates in the trajectory planning by cooperating with other knowledge sources. The control emulation process which is developed using a second neural system at a lower hierarchical level provides the correct sequence of control actions. An example …

Security Assessment Using Neural Computing, Badrul H. Chowdhury, B. M. Wilamowski

Electrical and Computer Engineering Faculty Research & Creative Works

The advantage of fast computation capability of an artificial neural network (ANN) is used to introduce an iterative scheme for security assessment of power systems. Two related approaches are shown which demonstratedly work satisfactorily. The idea of feedback in a single-layer feedforward neural network is experimented yielding higher accuracy. The ANN is trained by using a set of data obtained from off-line analysis of the power network. After training, an approximate solution for a given condition may be found almost immediately. The approximate solution obtained is judged adequate for assessing the security of the power system. A case study is …

A Hybrid Optoelectronic Art-1 Neural Processor, Donald C. Wunsch, T. P. Caudell

Electrical and Computer Engineering Faculty Research & Creative Works

Summary form only given. A new implementation of ART-1 (adaptive resonance theory) has been proposed that efficiently combines optical and electronic devices. All parallel computations are performed by the optics, while serial operations are performed in electronics.

A Neural Architecture For Unsupervised Learning With Shift, Scale And Rotation Invariance, Efficient Software Simulation Heuristics, And Optoelectronic Implementation, Donald C. Wunsch, D. S. Newman, T. P. Caudell, R. A. Falk, C. David Capps

Electrical and Computer Engineering Faculty Research & Creative Works

A simple modification of the adaptive resonance theory (ART) neural network allows shift, scale and rotation invariant learning. The authors point out that this can be accomplished as a neural architecture by modifying the standard ART with hardwired interconnects that perform a Fourier-Mellin transform, and show how to modify the heuristics for efficient simulation of ART architectures to accomplish the additional innovation. Finally, they discuss the implementation of this in optoelectronic hardware, using a modification of the Van der Lugt optical correlator

A Commodity Trading Model Based On A Neural Network-Expert System Hybrid, K. Bergerson, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

Demonstrates a system that combines a neural network approach with an expert system to provide superior performance compared to either approach alone. Learning capability is provided in a software-based approach to commodity trading systems. The authors used the backpropagation network with some parameters selected experimentally. They used a human expert to implicitly define patterns, using hindsight, that an intelligent system might have been able to use for an accurate prediction. Desired outputs were found by a combination of observing the behavior of technical indices that normally precede a certain kind of market behavior, and by observing the actual market behavior …

A Technological Development Model For Strategy Formation, Halvard E. Nystrom

Engineering Management and Systems Engineering Faculty Research & Creative Works

Summary form only given, as follows. The author presents a technological development model for product and company development based on a distinction between explicit and implicit technologies. Implicit technologies are evolving technologies while explicit technologies are established technologies. Based on empirical data from Swedish companies, a number of strategic dimensions are discussed such as network interaction and combining knowledge from various sources. These concepts are then used to present an integrated model of strategy formation and product and company development. It is argued that this view of technological development facilitates the understanding and analysis of innovation and entrepreneurship in highly …

An Empirical Analysis Of Backpropagation Error Surface Initiation For Injection Molding Process Control, Alice E. Smith, Elaine R. Raterman, Cihan H. Dagli

Engineering Management and Systems Engineering Faculty Research & Creative Works

Backpropagation neural networks are trained by adjusting initially random interconnecting weights according to the steepest local error surface gradient. The authors examine the practical implications of the arbitrary starting point on the error landscape of the ensuing trained network. The effects on network convergence and performance are tested empirically, varying parameters such as network size, training rate, transfer function and data representation. The data used are live process control data from an injection molding plant

Analytical And Experimental Investigation On Vibration Control Of Piezoelectric Structures, M. J. Tzeng, W-Z Ben Wu

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Active vibration control of smart structural materials (beam and plate) has been achieved by using distributed piezoelectric actuators. Numerical simulation and experimental testing have been conducted to investigate vibration suppression of the advanced structures. Results from simulation and testing are in satisfactory agreement.

Instability And Collapse Behavior Of A Seismic Structure, Franklin Y. Cheng, Jeng Fuh Ger

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The collapse behavior of a 22-story steel building during the September 19, 1985, Mexico earthquake is investigated by studying hysteretic behavior, ductility factors of individual structural components, and overall instability of the building. The hysteresis models for truss-type girders, bracing members, and box columns to be used in the inelastic analysis of this building are developed. A series of inelastic analyses have been performed for the building by using the multicomponent seismic input of actual Mexico City earthquake records. It was found that the structural response exceeds the original design ductility of this building because most girders in the building …

Cold-Formed Steel Z-Sections With Sloping Edge Stiffness Under Axial Load, Roger A. Laboube

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

No abstract provided.

Uplift Capacity Of Z-Purlins, Roger A. Laboube

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Roof systems constructed using cold-formed steel components, i.e., Z-shaped purlins and interconnected roof panels, have become a very popular form of construction. This roof system is used extensively for single-story commercial and industrial buildings in the United States. The popularity of cold-formed steel members is due in part to their superior gravity load strength-to-weight ratio; however, because of their relatively light weight, a cold-formed member is very susceptible to wind uplift loading. The design specification in the United States for cold-formed steel construction does not provide a comprehensive analytical solution to the problem of wind uplift strength of a cold-formed …

An Industrial Application To Neural Networks To Reusable Design, Donald C. Wunsch, R. Escobedo, T. P. Caudell, S. D. G. Smith, G. C. Johnson

Electrical and Computer Engineering Faculty Research & Creative Works

Summary form only given, as follows. The feasibility of training an adaptive resonance theory (ART-1) network to first cluster aircraft parts into families, and then to recall the most similar family when presented a new part has been demonstrated, ART-1 networks were used to adaptively group similar input vectors. The inputs to the network were generated directly from computer-aided designs of the parts and consist of binary vectors which represent bit maps of the features of the parts. This application, referred to as group technology, is of large practical value to industry, making it possible to avoid duplication of design …

Applying Artificial Intelligence To The Identification Of Variegated Coloring In Skin Tumors, Scott E. Umbaugh, Randy Hays Moss, William V. Stoecker

Electrical and Computer Engineering Faculty Research & Creative Works

The importance of color information for the automatic diagnosis of skin tumors by computer vision is demonstrated. The utility of the relative color concept is proved by the results in identifying variegated coloring. A feature file paradigm is shown to provide an effective methodology for the independent development of software modules for expert system/computer vision research. An automatic induction tool is used effectively to generate rules for identifying variegated coloring. Variegated coloring can be identified at rates as high as 92% when using the automatic induction technique in conjunction with the color segmentation method

In Situ Infrared Evidence For The Electrochemical Incorporation Of Hydrogen Into Si And Ge, K. C. Mandal, F. Ozanam, J.-N. Chazalviel

Faculty Publications

No abstract provided.

In-Line Photoresist Thickness Monitor, Richard N. Savage, Tom W. Batchelder, Kenneth M. Sautter, Gary H. Memovich

Materials Engineering

An in-line photoresist thickness measuring device wherein a plurality of projection optical fibers are disposed over a wafer processing track for illuminating portions of a wafer as the wafer proceeds along the track. The light scattered back from each illuminated portion is detected by a corresponding plurality of pickup optical fibers and communicated to an optical fiber multiplexer. The multiplexer sequentially selects the optical signal from each pickup optical fiber and communicates the light from the selected pickup optical fiber to a spectrometer. The spectrometer simultaneously diffuses the scattered light into a plurality of light bands, each light band having …

The Planet Janitor: A Symbol Of Global Concerns, Florida Solar Energy Center, Public Information Office

FSEC Energy Research Center®

Meet the Planet Janitor. A kindly, yet determined gentleman. He works at the Florida Solar Energy Center where he is a spokesman for energy-related issues. He illustrates the need to sweep up all environmental messes we've made. He reminds us to maintain our home - Planet Earth. He dramatizes our role as custodians of our children's inheritance. He knows and he shows how the individual can make a difference.

Renewable Energy Activities For Middle Grades, Florida Solar Energy Center, David Lahart

FSEC Energy Research Center®

The Florida Solar Energy Center (FSEC) is a research and education arm of the State University System hosted by the University of Central Florida. The Florida legislature established FSEC in 1974 to conduct research in alternative energy technologies, to ensure the quality of solar energy equipment sold in Florida, and to educate people about renewable energy technology.

One method of disseminating research results has been through teacher education programs and the development of instructional materials. FSEC-developed materials are designed to teach science and social studies research methods and/or process skills. The units have been field-tested and correlated with student performance …

Method Of Processing Superconducting Materials And Its Products, Kenji Okazaki, Robert J. De Angelis, Charles E. Hamrin Jr.

Chemical and Materials Engineering Faculty Patents

A method for fabricating relatively dense monoliths of superconducting material and relatively dense composite monoliths of superconducting material and binder material. The method includes the steps of placing the material to be processed in a die. A relatively high pressure is then applied to the material. Substantially simultaneously, an electrical discharge is applied to the material. The discharge is of a relatively high voltage and current density to provide sharp bonding while maintaining the superconducting properties of the material in the monolith product. A product fabricated by the present method is also described.

The Calendar - December 1990, Nova University

The Calendar

No abstract provided.

Surface Flashover Of Silicon, Frank E. Peterkin, Tim Ridolfi, Lonnie L. Buresh, Brian J. Hankla, D. K. Scott, P. F. Williams, William C. Nunnally, B. L. Thomas

P. F. (Paul Frazer) Williams Publications

The development of high-voltage semiconductor devices has been hampered by the occurrence of flashover at the surface of the semiconductor. The physical mechanisms responsible for this phenomenon are not understood. We present new empirical information which clarifies the processes responsible for surface flashover in a vacuum ambient by showing clearly that in flashover current flows primarily inside the semiconductor surface rather than in the ambient. This observation is in fundamental disagreement with the standard model for vacuum flashover of insulator surfaces.

Modeling AiXGa1-XAs Optical Constants As Functions Of Composition, Paul G. Snyder, John A. Woollam, Samuel A. Alterovitz, Blaine D. Johs

Department of Electrical and Computer Engineering: Faculty Publications

Three models for the dielectric function ε_x (hv) of Ag_xGa1_1-xAs are reviewed. All are based on measured optical constants at discrete compositions. The validity of each mode1 near critical pint energies, and otherwise, is evaluated. Only the energy-shift model is appropriate over the entire available spectrum ( 1.5-6.0 eV), including the band-gap (E₀) region.

Evaluation Of Flexible Delineator Posts, Kenneth R. Agent, Jerry G. Pigman

Kentucky Transportation Center Research Report

The objective of this study was to install a small number of lightweight metal u-channel posts with a round delineator and a small number of commonly used flexible posts and evaluate their performance. Three types of flexible posts were installed. They included two posts manufactured by Carsonite and one manufactured by Safe-Hit.

The results of the limited field tests does not support widespread use of flexible posts. Substantial durability problems were encountered with the flexible posts. Future use of flexible posts should be limited to potential high-hit areas such as gores at urban interchanges. While the durability of the metal …

Performance Evaluations Of Crushed Sandstone Aggregates In Bituminous Bases, David Q. Hunsucker, R. Clark Graves

Kentucky Transportation Center Research Report

The principal objective of the research effort was to develop historical performance data for bituminous sandstone pavements and bituminous limestone pavements relative to visual distress, pavement rutting characteristics, and structural condition using deflection measurements. Data relative to Road Rater deflections, pavement rutting, condition ratings based on subjective visual surveys and objective data such as skid resistance and rideability, were collected and analyzed during the course of the study and reported herein for the routes investigated.

It was concluded, based upon information gained during the evaluation period and presented in this report, that pavements constructed with bituminous sandstone bases do not …