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 …

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 …

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

Toward The Development Of Decision Support Tools To Manage The Catis Project Life Cycle, Steven Wayne Mccrary

Doctoral Dissertations

"The American Public Works Administration (1987) states that communities' infrastructures are in need of repair and better management and recommends CATIS (Computer-Assisted Terraspatial Information Systems) as an excellent tool to assist in that endeavor. Small communities have several voids that CATIS technology can fill. This research reports on a life-cycle approach to CATIS adoption that will help small communities to better manage their infrastructure.

It is important for small communities to become aware of the types of systems available and what each system can do. This study presents a straightforward, understandable discussion of CATIS technologies, features, and applications. Justifying the …

Toughening Mechanisms In Weak Matrix Ceramic Composites, Jowoong Ha

Doctoral Dissertations

"Tough behavior of ceramic matrix composites is closely related to the weak interface between fiber and matrix. The weak interfaces in composites have been provided by reducing the chemical bonding and the residual thermal stresses between constituents. A new way to introduce the weak interface by induced porosity or damaged zones, so called porosity toughening or damage toughening respectively, was proposed in this study to provide the rationale for guiding development of oxide/oxide composites. The existence of porosity toughening was examined by qualitative theoretical consideration and experiments. Porous oxide/oxide composites were fabricated using alumino-silicate fibers (Nextel 440) and magnesium alumino-silicate …

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 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 Laboratory Investigation Of Electro-Optic Kerr Effect For Detection Of Electric Transmission Line Faults, Badrul H. Chowdhury, E. Grigsby, T. J. Englert

Electrical and Computer Engineering Faculty Research & Creative Works

A prototype Kerr cell has been constructed and tested for detecting and identifying faults by monitoring high voltages such as are found in electric power delivery systems. Simulated faults were generated under laboratory conditions and monitored by the Kerr cell. Preliminary analysis was done using analog-to-digital conversion of the detected waveforms with a single board microprocessor serially interfaced with a personal computer. The occurrence of faults is readily observed and results indicate that identification of fault types can be accomplished within less than one cycle of a standard sixty-cycle-per-second delivery system. With a dedicated analysis system such a technique may …

A Nuclear Fragmentation Energy Deposition Model, John W. Wilson, D. M. Ngo, T. N. Forgarty, W. W. Buck

Mining Engineering Faculty Research & Creative Works

A formalism for target fragment transport is presented with application to energy loss spectra in thin silicon devices. A nuclear database is recommended that agrees well with the measurements of P.J. McNulty et al. (1980) using surface barrier detectors. High-energy events observed by P.J. McNulty et al. (1981), which are not predicted by intranuclear cascade models, are well represented by this work

Compensation Modes In Counterdoped Rutile, M. M. Nasrallah, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

Thermogravimetric measurements were conducted on undoped, Nb⁵⁺ or Ta⁵⁺ donor-doped, and Al³⁺ acceptor doped rutile at 1000°C and 105-10-7 Pa oxygen activity. Nb⁵⁺ or Ta⁵⁺ doped rutile was counter doped by Al³⁺ in order to identify the role of Al³⁺ acceptor and its effect on donor doped rutile. Our results show that both dopants enter the lattice substitutionally for Ti⁴⁺, that Al³⁺ is as effective an acceptor as Nb⁵⁺ or that Ta⁵⁺ is effective as a donor, and the compensation occurs on a one-to-one basis. Earlier reports indicate …

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 …

Occupation Dynamics Of Trap States In An A-Si:H Thin-Film Transistor, J. N. Bullock, Cheng-Hsiao Wu

Electrical and Computer Engineering Faculty Research & Creative Works

We calculate the dynamical behavior of a-Si:H thin-film transistors with an emphasis on the occupation dynamics of trap states. The appropriate rate equation for the occupation function of trap states is included. We show the relations of filling the trap states with the switch-on time and of emptying the trap charges with the switch-off time. The occupation functions in both cases are non-Fermi distribution. The quasi-equilibrium approximation underestimates those two time constants. Thus, transit time theory cannot describe the speeds of transistors made from disordered materials.

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 …

Disintegration Of Wood, Marian Mazurkiewicz

Mining Engineering Faculty Research & Creative Works

Disintegration of a body of organic material involving subjecting the body to liquid jet action with the energy of the liquid as it impacts on the body such as to effect disintegration of the body into particles.

Decoupled Dynamics For Control And Estimation, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Decoupling of the dynamical equations in polar coordinates is used to develop a control scheme for use in target-intercept problems with passive measurements. By defining a pseudo control variable in the radial coordinate, the radial dynamics is made independent of the transverse dynamics. After solving for the radial control, the transverse control is determined through solutions to a two-point boundary value problem. Numerical results from a six degree-of-freedom simulation which used the decoupled control indicate that it is better than the completely Cartesian coordinate control for most of the cases considered. Decoupled control, though, is obtained iteratively through a two-point …

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

Mechanical and Aerospace 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 neural system participates in the delineation of the robot arm workspace and coordinates transformation and the motion decision-making process. The lower one provides the correct sequence of control actions. The capabilities, including speed, adaptability, and computational efficiency, of the developed architecture are illustrated by an example.

Effects Of Sample Orientation On The Corrosion Of Zinc In Ammonium Sulfate And Sodium Hydroxide Solutions, D. Abayarathna, Edward Boyd Hale, Thomas J. O'Keefe, Y. M. Wang, D. Radovic

Physics Faculty Research & Creative Works

The corrosion and electrochemical properties of three zinc single crystal surfaces with different orientations have been investigated. In near-neutral 1 M (NH₄)₂SO₄, the corrosion rates on all three surfaces were found to be similar. However, the SEM morphologies of the corresponding corroded surfaces were markedly different from each other, but consistent with preferential attack of {1120} surfaces. In alkaline 0.5 N NaOH solution, the three sample orientations showed significantly different reactivities, with the (1120) surface exhibiting the highest reactivity and corrosion rate. Here, passivation ultimately occurred and the difference in the corrosion performance of …

Microwave Nondestructive Detection And Evaluation Of Disbonding And Delamination In Layered-Dielectric Slabs, R. Zoughi, Sasan Bakhtiari

Electrical and Computer Engineering Faculty Research & Creative Works

A microwave nondestructive technique for detection and evaluation of disbonding and delamination in layered-dielectric-slabs backed by a conducting plate is discussed. The theoretical development begins by considering an incident wave illuminating such a medium and then formulating the characteristics of the wave reflected by the metal plate. An effective reflection coefficient is determined in this way whose phase characteristics are used in the detection and evaluation of delaminations in the media. The characteristics of this phase as a function of several parameters such as delamination dielectric constant and thickness, slab dielectric constant, and thickness and the frequency of operation are …

The Waveform Relaxation Method For Systems Of Differential/Algebraic Equations, Marija D. Ilić, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

An extension of the waveform relaxation (WR) algorithm to systems of differential/algebraic equations (DAE) is presented. Although this type of application has been explored earlier in relation to VLSI circuits, the algorithm has not been generalized to include the vast array of DAE system structures. The solvability and convergence requirements of the WR algorithm for higher-index systems are established. Many systems in robotics and control applications are modeled with DAE systems having an index greater than two. Computer simulation of these systems has been hampered by numerical integration methods which perform poorly and must be explicitly tailored to the system. …

Design Of Automotive Structural Components Using High Strength Sheet Steels Structural Strength Of Cold-Formed Steel Members Under Dynamic Loads, Chi-Ling Pan, Wei-Wen Yu

CCFSS Library (1939 - present)

INTRODUCTION During recent years, more economic and lighter vehicles have been produced by automotive manufacturers because of the high cost of fuel. High strength sheet steels have been favorably used to accomplish the construction of such automobiles. One source of the design information for using sheet steels is provided in the AISI Automotive Steel Design Manual 1. In view of the fact that material properties and stress-strain relationships of sheet steels can be influenced by the strain rate, the material properties of three different sheet steels (35XF, 50XF, and 100XF) have been studied at University of Missouri-Rolla. This study involved …

Fracture Toughening Of High Pressure Sintered Diamond And Carbide Ceramics, P. D. Ownby

Materials Science and Engineering Faculty Research & Creative Works

High pressure sintered bodies of polycrystalline diamond or carbide ceramics are rendered more resistant to cracking by establishing dispersed, localized "stress centers" of submicron size particles of lonsdaleite, diamond, or other form of metastable, high density carbon which has the capability of transforming crystallographically to graphite in situ in the body. When an incipient crack in the body approaches entrapped metastable particles along its path, the crack promotes or permits transformation of the metastable particles to graphite particles, with concomitant increase in their size, thereby resisting further propagation of the crack.

Cold-Formed Steel Products In Material Handling System Projects: Indian Experience, Manhar C. Thakkar

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

No abstract provided.

A Study Of Cold-Formed Z-Section Steel Members Under Axial Loading, Rene W. Purnadi, John L. Tassoulas, Dimos Polyzois

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

No abstract provided.

Pull-Over Strength Of Screws In Simulated Building Tests, Duane S. Ellifritt, Robert Burnette

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

No abstract provided.

Optimal Orientation Of Corrugations In Beam Webs, Vladislav Belyaev, Tatyana Mikhailova

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

No abstract provided.

A Numerical Model For Fire-Exposed Composite Steel/Concrete Slabs, Ralph Hamerlinck, Leen Twilt, Jan W. B. Stark

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

No abstract provided.

Strength Of Composite Slabs, Craig Steven Young, W. Samuel Easterling

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

No abstract provided.

Strength Evaluation Of Strut-Purlins, Gerald L. Hatch, W. Samuel Easterling, Thomas M. Murray

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

No abstract provided.

Effective Width In Elastic Post-Buckling Of Thin Flanges, Robert W. Dannemann

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

No abstract provided.