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A Structural Investigation Of Bismuth Ferrate And The Bifeo₃-Pbzro₃-Pbtio₃ Ternary System, Gary D. Achenbach

Doctoral Dissertations

"Solid state reaction of Bi₂O₃ · Fe₂O₃ mixtures was shown to yield impure bismuth ferrate, BiFeO₃, containing Bi₂Fe₄O₉ and residual Bi₂O₃; this places the results of much of the literature based on BiFeO₃ prepared by this technique in suspect. Single phase polycrystalline BiFeO₃ was prepared by multiple nitric acid leaching of sintered samples which contained excess Bi₂O₃ to prevent the formation of Bi₂Fe₄O₉ during sintering. X-ray and neutron powder diffraction data indicate that …

An Investigation Of The Creep Characteristics Of Portland Cement Mortar Under Static And Dynamic Strain, Ikram-Ul-Haq Dar

Doctoral Dissertations

"The combined effect of static and dynamic loads on design of underground openings is currently receiving much attention. It is known that the time-dependent behavior of rock is considerably different when a dynamic load is superimposed on prestressed rock. The shape of an underground opening has a definite influence on the magnitude of the local stresses and these may be significantly larger than those due to the weight of the overlying rock alone. Under these conditions, even a small dynamic load in the form of vibrations caused by blasting, drilling and related operations may increase the stress beyond a critical …

Numerical Approximation To Performance Predictions Of Gas-Drive Reservoir With Or Without Gas-Cap And Gas Injection, Jagannath Rao Ghole

Doctoral Dissertations

"The pressure-saturation transient history for a hydrocarbon reservoir is solved for solution-gas, gas-cap and injected-gas drives assuming the saturation-pressure variations depicted by Muskat, under specific restrictive assumptions. A prototype reservoir system and its transient pressure saturation distribution under production is systemized on an IBM 360-Model 40 Computer which allows the definition of the transient behavior of saturation with pressure declination and fluid withdrawal for preassigned initial saturations of the oil, water and gas phases. This analysis is then modified for the existence of a gas-cap and for the re-injection of produced gas volumes for pressure maintenance considerations and the ensuing …

A Study Of Surface And Geometric Effects On The Nucleate Boiling Of Liquid Nitrogen And Liquid Argon From Atmospheric To The Critical Pressure, Calvin Benson Cobb

Doctoral Dissertations

"A maximum heat flux correlation was derived for corresponding states liquids and subsequently verified by the data collected in this study as well as data presented in the literature. By applying this correlation, one can predict maximum heat flux values at high pressures from maximum heat flux values measured at low pressures; however, to apply the correlation it is necessary to have at least one maximum heat flux value and the saturation temperature at which it was determined.

Contrary to existing correlations, it is shown that for any nucleate boiling heat transfer correlation to be truly general, it must include …

Small-Signal Impedance Of A Junction Diode At High Injection Levels, John E. Lundy

Masters Theses

"A mathematical expression for the driving point impedance of a junction diode at high injection levels is developed. To evaluate the impedance versus frequency characteristic of a diode, it is necessary to know the minority carrier lifetime as a function of injection level and doping density in the base (lightly doped) region, the junction area, and the base width. The interesting characteristic of the diode impedance at high injection levels is the inductive reactance displayed by the diode.

The expression is developed by solving the differential equation for charge flow in the base region of a diode assuming space-charge neutrality …

Characteristic Impedance Of Open Microstrip Transmission Lines Having Finite Thickness And Multiple Dielectric, Philip Julian Carter

Masters Theses

"A computer program is provided for determining the characteristic impedance of microstrip transmission lines having finite thickness. Infinite and finite ground planes are incorporated into the program. The programmer need only supply information in the form of a data card. This procedure is clearly outlined.

Graphical solutions of characteristic impedance for multiple dielectric microstrip transmission line problems are obtained using a discrete resistive analogue. Computer network analysis programs are viewed as having several advantages not possessed by the physical resistive analogue"--Abstract, page 2.

Collision And Pursuit Course Terminal Closures For Spacecraft To Satellite Rendezvous, John Anthony Campbell

Masters Theses

"Collision and pursuit course closure maneuvers were studied for correcting position and velocity errors in the terminal phase of spacecraft to satellite rendezvous.

Minimum values of the ratio of initial range to velocity necessary to achieve rendezvous were determined for collision closures as a function of the initial line of sight. The time and velocity increment required for rendezvous were computed as a function of initial conditions.

Pursuit closure maneuvers were analyzed and time and velocity increments defined as a function of initial range, closing velocity, line of sight angle and angular velocity.

The velocity increments required were significantly higher …

A Comparison Of Friction And Drum Hoisting Systems On An Energy-Input Basis, Hemendra Nath Kalia

Masters Theses

"The purpose of this thesis is to provide a suitable basis for comparing the relative advantages of the friction and drum hoists under various conditions of operation.

Such comparisons are mainly and necessarily based upon physical characteristics of the mechanisms for lack of appropriate economic data. It is believed, however, that this inadequacy may be alleviated to some extent by substituting comparative theoretical energy requirements of' the two hoisting systems under identical duty conditions over a practical range of mining situations involving various depths and daily productions.

This has been accomplished by adapting a computer to standard mine-hoist design techniques …

A Determination Of The Rate Of Evaporation Of Zinc At Atmospheric Pressure., Yu Ming Su

Masters Theses

"Measurements of evaporation rates of zinc in three different residual gases, e.g., argon, carbon monoxide, and hydrogen at one atmosphere pressure, were made. It was found that the rate of evaporation of zinc in one atmosphere of argon was almost the same as that in carbon monoxide, while the rate in hydrogen was almost twice the rate in argon or carbon monoxide. Measurements of evaporation rate of zinc in one atmosphere of argon-oxygen mixtures were also made. The evaporation rate was considerably reduced because the formation of the oxide film retards the zinc vapor escaping from the evaporating surface"--Abstract, page …

Film Boiling From Horizontal Plates With Low Thermal Capacity, K. M. Ragsdell

Masters Theses

"The object of this investigation was to obtain data for saturated film pool boiling from a low thermal capacity flat plate at atmospheric pressure. A test plate, constructed from resistance strip, was placed horizontally in a pool of liquid, and was heated electrically. Refrigerant-11 and nitrogen were used as the boiling liquids. Heat transfer results were obtained in both fluids over a temperature range of approximately 1200F⁰ (400-1600⁰F). Surface size, roughness and orientation effects were observed for flat horizontal heated surfaces with one dimension near the most dangerous wavelength. No surface material effect was observed. Excellent correlation of the data …

Shutdown Reactivity Worth Of Reactor Control Rods By A Subcritical Multiplication Method, Leslie Roger Conner

Masters Theses

"Two modified subcritical multiplication methods for measuring the reactivity worth of control elements were developed and investigated. The first involved the calibration of a subcritical count interval by the asymptotic period method. The second involved the calibration of a subcritical count interval by a rod interchange with the reactor regulating rod which had previously been calibrated by the asymptotic period method. The accuracy of these methods is relatively poor. this inaccuracy is due to shadowing effects and to the spatial harmonics which exist in the core. An investigation of the spatial harmonics to determine the best location for the neutron …

Compressive Creep Of High Alumina Refractories, Vernon Lee Burdick

Masters Theses

"The deformation of refractory materials consisting of 90% sintered or fused alumina plus 10% silica was measured at temperatures from 1450 to 1515⁰C and a compressive stress of 100 psi. Creep rates and activation energies were determined from the steady state portion of deformation vs. time data and correlated with the mineralogical composition. Supplemental measurements included x-ray diffraction, electron probe microanalysis, apparent porosity and tensile strength. conditions having an important effect upon the mineralolgical composition were: (1) duration of heat treatment, (2) amount of sodium oxide impurity, and (3) reactivity of the alumina grain. Prolonged heat treatment and sodium oxide …

A Class Of Pattern Recognition Machines, Shaw Yih Chung

Masters Theses

"The classification of signals through the use of pattern recognition techniques may be viewed as a statistical classification problem since at least some pattern classes are analog signals which have been contaminated by additive noise. In order to represent these signals at the input of a pattern classifier they are sampled and a vector and an m-dimensional vector space used to describe the pattern. Consequently, these pattern samples are processed to determine the parameters of the statistics. In this study the additive noise was assumed to be Gaussian in nature. This study was based on a priori knowledge of the …

Synthesis Of Filters Using Distributed Rc Networks, Mario Nader Nader

Masters Theses

"This paper deals with the problem of realizing filter and delay functions by means of distributed RC devices. The method is made possible through the use of a distributed RC network which possesses rational admittance parameters. The technique of approximating transfer functions using polynomial factors that are ration in e[superscript (a square root of s] is explained. These factors are used to approximate the magnitude and phase characteristics for a low-pass filter. This filter is then realized using the admittance functions studied by Wyndrum, the "s->W" transformation, and Richard's theorem. Those factors are then used to approximate high-pass and …

A Study Of Film Boiling Of Liquid Nitrogen And Liquid Argon Over A Wide Pressure Range With Cylindrical Heaters, V. J. Flanigan

Masters Theses

""A film boiling heat transfer study was conducted with three different diameter cylindrical copper heaters over a wide range of pressures for nitrogen and argon with the heat transfer surface in the horizontal position. The data were compared to the commonly used film boiling heat transfer relations. The common relations were found to be considerably in error for the range of variables covered in this investigation. A semi-empirical equation for corresponding states fluids which correlates the available data as a function of the reduced temperature and reduced pressure was derived and discussed"--Abstract, page iii.

Hydrologic Characteristics Of Shallow Bedrock Aquifers In The Vicinity Of Norman Creek, Central Phelps County, Missouri, Michael A. Nawrocki

Masters Theses

"Groundwater is becoming increasingly important as a source of water supply in the United States. Consequently, the prediction of well yields is a vital concern. In order to predict the quantity of water which can be reduced from a given aquifer it is necessary to know the aquifer's hydrologic characteristics. Many theoretical formulae have been derived for determining the aquifer characteristics. To date, these formulae have been tested mainly on unconsolidated and clastic rock aquifers. It has never been shown that these formulae can also be consistently applied to carbonate aquifers which underlie regions of karst terrain. This paper summarizes …

Optimum Fin Spacing For Heat Transfer Per Unit Length Of Heat Exchange Section, Glenn Ellis Miller

Masters Theses

"This thesis presents the results of an experimental study of the heat-transfer ability of a finned surface as a function of the spacing between fins. The results are expressed as heat transfer per unit length of finned section rather than the heat transfer per fin. Circumferential steel fins, seven and three-quarter inches in diameter, were used for the investigation. Data was taken for fin spacings ranging from zero to one and one-half inches. The experimental heat-transfer rate to atmospheric air was determined by measuring the volume of saturated steam which condensed in the test section over a measured time interval. …

Velocity Profiles In Viscoelastic Drag Reducing Solutions, Luis Gustavo Florez E.

Masters Theses

"Turbulent velocity profiles in viscoelastic drag reducing solutions were measured using hot-film anemometer and Pitot tube techniques. Data were obtained in a solution of one per cent aluminium [sic] dioleate in toluene and in 0.2 and 0.4 per cent solutions of polyisobutylene (PIB) L-200 in cyclohexane. Velocity profiles were also obtained for comparison in toluene and cyclohexane by both techniques. By integrating the Pitot tube velocity profiles, large flow rate discrepancies between integrated and measured flow rates were found for the drag reducing polymer and soap solutions. This discrepancy was not observed in the hot-film anemometer measurements. The hot-film anemometer …

The Economics And Design Of Desalination By Evaporation Through Porous, Water-Repellent Membranes, Kuei-Hsiung Yang

Masters Theses

"The economics of desalination by evaporation through porous, water-repellent membranes has been studied in this investigation. Using reasonable assumptions this desalination process was found to be economical with the principal advantage being the simplification of multi-stage flash-type evaporation. Based on this process, two different methods were designed and studied by means of computer calculations for a 10 million gallons product water per stream day desalting plant. One method was based on a membrane evaporator and a heat exchanger and was designated Method I; and a combined evaporation-heat exchanger system was designated at Method II. The major factors affecting the economics …

Fault Detection In Combinational Networks, Alexander Rahm

Masters Theses

"This paper presents an algorithm for locating a failure in combinational logic networks, which is a problem of importance in the maintenance of computer systems. The procedure is based on the "path sensitizing" idea for fault detection. The networks considered are non-redundant, consisting of AND, OR, and NOT elements. The class of faults investigated is that which causes a connection to appear to be logically suck-at-one or stuck-at-zero, and only single failures are treated. It is shown that the failure is generally located to a specific "fault group"--Abstract, page 2.

A Study Of Probability Of Error Calculations For Baseband Multi-Level Digital Transmission Systems Using The Fixed Threshold Decision Rule, Don J. Popp

Masters Theses

"This study is an investigation into analytical techniques used in deriving probability of error expressions for baseband multi-level digital transmission systems. A fixed-level decision rule is used to solve this statistical detection problem together with some simple concepts from probability theory. To illustrate these techniques, probability of error expressions are derived for the general uncoded system, a simple coded system, and a complex coded system. Curves of probability of error versus signal-to-noise ratio are plotted for the various systems considered"--Abstract, page ii.

Stress Analysis Of A Wall Footing Subjected To External Vertical Loads And Overturning Moments By The Finite Element Method, Adil Godiwalla

Masters Theses

"This investigation pertains to the stress analysis by the finite element method of a wall footing subjected to external vertical loads and external overturning moments. This problem has been reduced to a two-dimensional stress analysis problem by taking a unit length of the wall. A rectangular plate - element is used throughout this investigation. The development of the matrix equations is shown and the solution is performed by digital computer. Stresses in the horizontal direction show essentially linear variation which is in agreement with simple structural theory, while stresses in the vertical direction show severe perturbation near the column load. …

Mode Analysis Of The Unsymmetrically Fed Ground-Plane Aperture, John G. Hemmann

Masters Theses

"The problem of radiation from a waveguide-fed ground-plane aperture perturbed with a wedge-shaped dielectric insert was examined more carefully. The work initiated by Blumberg was continued, using a greater range of dielectric constants and smaller increments of angle.

Aperture field measurements were made over a range of dielectric constants for each wedge angle, in order to determine the change in amplitude distribution as a function of permittivity. Aperture phase measurements were also taken for selected angles. These were used with the amplitude data to predict, using numerical integration, the far-field radiation patterns of the perturbed aperture. Far-field patterns were then …

Vapor Pressure And Evaporation Coefficient Of Cadmium Oxide, R. Tom Coyle Jr.

Masters Theses

"Knudsen effusion experiments were carried out on CdO in fused silica crucibles at temperatures of 918°K, 1008°K with orifice areas from 2.742x10^-3 cm² to 30.52x10^-2 cm². The experiments were made in a molybdenum-wire, resistance-heated vacuum furnace. Several orifice areas were used at each temperature and reciprocal pressure versus orifice area plots were made. These plots yielded an upper limit to the evaporation coefficient of. 4.15x10^-2. An equilibrium constant for the vaporization reaction

CdO(s) = Cd(g) + 1/20₂ (g)

of

log Keq = 11.12 - 1.952x10⁴/T.

was obtained. Second and third …

Study Of Mass Transfer Through Porous Water-Repellent Membrane As A Function Of Membrane Thickness And Rates Of Heating, Yalamanchili Babu Rao

Masters Theses

"The object of this investigation was to study the mass transfer coefficients through porous water-repellent membranes, and their dependence on membrane thickness and rates of heating, and to compare experimental correlations with theoretically based equations. The membranes used during the experimental work were made of glass fiber treated with Teflon suspension and aluminum sulfate. The mechanism involves evaporation and condensation on opposite sides of a vapor-filled porous membrane. Salt water evaporates from one interface of a non-wettable, porous membrane, diffuses through the vapor filled pores, and condenses to fresh water at the other interface of the membrane. This transfer may …

Molecular Diffusion In Polymer Solutions By A Microinterferometric Method, Surendra V. Desai

Masters Theses

"The object of this investigation of molecular diffusion in aqueous polymer solutions was to study the effect of solute concentration on the differential diffusion coefficient and also to study the effect of polymer concentration on the mean integral diffusion coefficient. For this purpose a microinterferometric method was used. Two non-ionic, water soluble polymers, Carboxymethylcellulose (CMC) and Carboxypolymethylene (Carbopol), were used in the study with D-Glucose as a solute.

The differential diffusion coefficient was found to increase with increases in solute concentration in all cases. For CMC, the integral diffusion coefficient at first decreased with increasing polymer concentration but became constant …

Dynamic Response Of A Simply Supported Beam To An Accelerating Point Load, Joseph Victor Cusumano

Masters Theses

"An analysis based on linear theory is presented for determining the dynamic response of a simply supported beam on an elastic foundation acted upon by a moving time dependent point force with axial forces included. This thesis extends the present theory to include an analysis of a point force accelerating uniformly across the beam. In particular, it is shown that the customary resonance conditions which are prevalent for a point force moving with uniform velocity no longer exist for the case of a point force accelerating uniformly across the beam.

The basic problem and its solution are presented for a …

Centrifugal Model Study And Finite Element Analysis Of Stress Near A Fault, Christopher Haycocks

Doctoral Dissertations

"The adverse effects of faults on the stability of underground openings has long been realized. To date, however, discontinuities and most other types of geologic heterogeneities have not been amenable to mathematical analysis using the classical theories of elasticity and plasticity. This investigation examines the stress distribution around a single discontinuity and compares the experimental and numerical methods used for the analysis. The theory of elasticity, employing the equations of compatibility, equilibrium etc., was used to determine a stress function for the stress distribution around a circular hole loaded in a centrifugal field. The analysis was terminated after the stress …

Matrix Computer Analysis Of Curvilinear Grid Systems, David Leon Fenton

Doctoral Dissertations

"A general equilibrium-stiffness method of matrix structural analysis was adapted and applied to the solution of the member end forces and moments of each of the members in a curvilinear structural grid system. A structural system of this nature is commonly used as the supporting framework for a "steel-framed dome", in addition to being a basic structural component in many aerospace applications. An integral part of the development of the analysis was the development of a computer program to perform the many complex operations required to obtain the solution. The engineer, by supplying the appropriate structural data and load data …

The Amino Acid And Monosaccharide Content Of The Cell Walls Of Thiobacillus Thiooxidans, Edward Hibbert Crum

Doctoral Dissertations

"The objectives of this investigation were: (a) to culture large quantities of Thiobacillus thiooxidans cells, (b) to find an acceptable method of rupturing the cells, (c) to find an acceptable method of isolating the cell walls, and (d) to analyze the cell wall components, especially the amino acid and sugar components. The strain of T. thiooxidans used for this investigation was American Type Culture Collection Number 8085. The surface active agents Tergitol 08 and Tween 80 were investigated for their ability to reduce the lag period found in the growth of T. thiooxidans. Although a concentration of 12.5 ppm Tween …