Digital Commons Network^™

Impact On Laminated Composite Materials, Serge Abrate

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laminated composite materials are used extensively in aerospace and other applications. With their high specific modulus, high specific strength, and the capability of being tailored for a specific application, these materials offer definite advantages compared to more traditional materials. However, their behavior under impact is a concern, since impacts do occur during manufacture, normal operations, or maintenance. The situation is critical for impacts which induce significant internal damage, undetectable by visual inspection, that cause large drops in the strength and stability of the structure. Impact dynamics, including the motion of both the impactor and the target and the force developed …

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 …

Synthesis And Characterization Of Barium Lanthanum Titanates, Jyoti P. Guha

Materials Science and Engineering Faculty Research & Creative Works

Ternary compounds in the system BaO—TiO₂—La₂O₃ were prepared by the solid‐state reaction technique at temperatures between 1300° and 1400°C using precursor oxides as the starting materials. In an alternative processing technique, BaTiO₃ was reacted with appropriate proportions of prefabricated lanthanum titanates at 1350°C to obtain the compounds. Two compounds were identified in the TiO₂‐rich region of the system. The X‐ray powder diffraction pattern of a compound with a chemical composition BaLa₂Ti₃O₁₀ (BaO·La₂O₃·3TiO₂) is indexed on the basis of an orthorhombic unit …

Feq⁺+ H, H2and He Electron Loss And He2++ H(N = 1, 2) Electron Capture Cross Sections: Processes Of Interest In Fusion Plasmas, D. R. Schultz, L. Meng, C. O. Reinhold, Ronald E. Olson

Physics Faculty Research & Creative Works

Cross sections have been calculated utilizing the classical trajectory Monte Carlo method for collisional processes of special interest to plasma fusion research. Specifically, H₁H₂and He total electron loss cross sections for the impact by Fe^q+(1 < q < 26) impurity ions, in the energy range of 50 to 500keV/u, are presented. These results illustrate a clear departure for low charge states (q < 10) from scaling of the cross section with projectile charge (q). Further, cross sections for electron capture from both the ground and n = 2 states of H by 30 to lOOkeV/u He²⁺impact are tabulated as function of final n-level, yielding information for neutral beam heating models. © 1991 IOP Publishing Ltd.

Fault-Tolerant Parallel Matrix Multiplication With One Iteration Fault Detection Latency, Chul Eui Hong, Bruce M. Mcmillin

Computer Science Faculty Research & Creative Works

The checksum technique is a low-cost method to detect errors in matrix operations performed by processor arrays. The fault detection of this method is done only at problem termination, so this method is not an effective fault tolerance technique for large scale matrix multiplication. This paper presents a new algorithm, the ID algorithm, which minimizes the fault-detection latency, In the ID algorithm, a fault is detected as soon as the fault occurs instead of at problem termination. For n2 processors, the fault-latency time of the ID algorithm is l/n of that of checksum algorithm with a run-time penalty of O(nlog2n) …

A Model-Based Approach For Organizing Quantitative Computations, J. Sticklen, A. Kamel, William E. Bond

Computer Science Faculty Research & Creative Works

Model based reasoning (MBR) is currently receiving wide spread attention because it offers a way to circumvent the brittleness of reasoning systems built solely on associational knowledge. To date, most MBR approaches have focused on the use and manipulation of qualitative models. The authors report their experience in applying techniques of functional reasoning to the general problem of organizing quantitative calculations. As a testbed, they have solved a problem initially posed at the Model-Based Diagnosis workshop (Paris, July, 1989): representing an automotive cruise control system. The results show that the principles of the functional reasoning approach can provide leverage in …

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 …

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.

Deriving Clinical Prediction Rules From Stroke Outcome Research, Daniel B. Hier, Gilda Edelstein

Chemistry Faculty Research & Creative Works

Background and Purpose. Our Purpose Was to Determine Whether Clinical Prediction Rules Could Be Derived from Current Stroke Outcome Research. Summary of Report. We Reviewed 92 Articles on Stroke Outcome Research to Determine their Suitability for Implementation as a Clinical Prediction Rule. Methodological Problems in Many of These Studies Made Implementation of their Results as a Clinical Prediction Rule Difficult. Conclusions. Implementation of Stroke Outcome Research as Clinical Prediction Rules Would Be Facilitated by Description of Patient Population Demographics; Precise Definitions of Predictor and Outcome Measures; Stratification of Patients by Stroke Mechanism; Use of Adequate Patient Sample Sizes; and Description …

A Seismic Analysis Of Black Creek And Wabumun Salt Collapse Features, Western Canadian Sedimentary Basin, Neil Lennart Anderson, Robert James Sidford Brown

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

These salt remnants and their associated collapse features are often associated with structural or stratigraphic traps. As a result of the relationships between dissolution and hydrocarbon entrapment, the distribution (areal extent and thickness) of these salt remnants is of significant interest to the explorationist. Seismic information about the thickness and the extent of these salts should be used together with well log control to generate subsurface distribution maps. These maps will facilitate both the delineation of prospective structural and stratigraphic play fairways and the determination of the timing of salt dissolution. In addition, an appreciation of regional salt distribution will …

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 …

An Optoelectronic Adaptive Resonance Unit, Donald C. Wunsch, T. P. Caudell, R. A. Falk, C. David Capps

Electrical and Computer Engineering Faculty Research & Creative Works

The authors demonstrate a hardware implementation of the adaptive resonance theory ART 1 neural network architecture. The optoelectronic ART1 unit, is a novel application of an old device. This device-the 4-f or Van der Lugt correlator-has historically been used as a fast pattern classifier. Usually the correlation operation is employed as a matched filter, so that a maximum correlation peak corresponds to a well-matched pattern. The device described also uses the large peaks, but takes specific advantage of the fact that a zero-shift correlation is mathematically equivalent to a two-dimensional inner product. The authors describe a promising method for emulating …

Faculty Senate Minutes 1990 - 1991, Missouri University Of Science And Technology Faculty Senate

Minutes & Agendas

No abstract provided.

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. …

Reduced Order H∞ Controller Design, Seng Chu Chow

Masters Theses

"The problem formulation and the development of the H_∞ optimal control theory are reviewed. Various H_∞ robust controller design techniques, including both state and output feedback cases, together with a brief comparison and some remarks on these methodologies arc presented. Also included are a review of the controller order reduction alternatives and various balanced truncation model reduction methods.

A new model reduction technique with reduced error bound is proposed. This proposed technique introduces a new parameter which can be used to select the spectral norm of the model reduction error at low and high frequency ranges according to …

Coordinated Strategic Planning Of Hydroelectric Energy Usage Using Stochastic Dynamic Programming With Decoupled Production Cost Simulation, Duane David Highley

Masters Theses

"The method of Stochastic Dynamic Programming is applied to the problem of Long-term hydrothermal coordination for a five-reservoir system in the Midwest. The model that has been developed will optimize the monthly reservoir elevations to produce the lowest expected energy production cost. The production cost calculations are decoupled from the Dynamic Programming loop, resulting in shorter execution times. Constraints are included for maximum and minimum reservoir elevations, maximum monthly reservoir rise and drop, and maximum and minimum monthly energy production. These constraints help to reduce the state space and shorten execution time. An additional constraint is modeled to control the …

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 …

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 …

Dose Rate Determination Of The Highly-Enriched Uranium Fuel At The University Of Missouri-Rolla Reactor In Preparation For Transportation, Alice Ann Netzer

Masters Theses

"An analytical model was developed in order to accurately estimate the dose rates in air of the highly-enriched uranium (HEU) fuel at the University of Missouri - Rolla Reactor. Based upon these results, a method is proposed to remove the fuel from the reactor.

First thermoluminescent dosimeters (TLDs) were exposed under water to each of the fuel elements in the reactor pool, except for the four control rodded elements. A model was developed to use the in-water TLD readings to calculate the dose rate of the fuel elements in air at 1 foot and 3 feet. The fuel was modeled …

New Bio-Analytical Separations Utilizing Chiral Mobile Phase Additives In Thin Layer Chromatography And Chiral Stationary Phases In High Performance Liquid Chromatography, Jo Dee Duncan

Doctoral Dissertations

"The problem addressed by this dissertation is the separation of optical isomers in commercial as well as biological samples. The chromatographic separation of enantiomers is an important and rapidly developing field of study. Chiral separations of pharmaceutical compounds and important organic intermediates in high performance liquid chromatography (HPLC) and thin layer chromatography (TLC) were achieved. Two methods were employed for the direct liquid chromatographic resolution of chiral analytes: chiral stationary phases (CSPs) and chiral mobile phase additives (CMAs). Native and derivatized ß-cyclodextrins (ß-CD) were used as chiral stationary phases in reverse phase and normal phase HPLC, respectively. This study marked …