Engineering Commons^™

Subsolidus Equilibria And Metastable Phase Development In The System Zro₂-Al₂O₃-Sio₂, Charles Christopher Sorrell

Bachelors Theses

"Subsolidus equilibria in the low silica portion of the system ZrO₂-Al₂O₃-SiO₂ were studied by X-ray diffraction of quenched samples fired at 1300°, 1400°, and 1480°C. Samples prepared as powders from combinations of a-Al₂O₃, Al(OH)₃, silicic acid, ZrO₂, and kaolinite reacted very slowly at 1300° and 1400°C and the trends toward equilibria are not apparent. A mixture of zircon and Al(OH)₃ reacted slowly at 1480°C to form mullite and ZrO₂, indicating that the latter phases are the stable assemblage rather than zircon and alumina. A gel prepared from aluminum nitrate, zirconyl nitrate, and colloidal silica reacted at 1480°C to form alumina, …

Decoupled Explosive Charge Effects On Blasting Performance, Roberto Ucar

Masters Theses

"This investigation was performed to determine the burden at which hard rock would break utilizing decoupled and unstemmed charges when the free surface parallel to the borehole was the wall of an open hole. This open hole was created by burn cuts and by drilling holes of 7-7/8 in. and 12 in. diameter. Additional tests were performed using partially stemmed charges where the stemming was the same size as the explosive charge.

The explosive used was a 0.75 lb. slurry charge, 1.5 in. diameter and 10 in. long. The diameter and depth of the borehole were 2 in. and …

Characterization Of Two Mexican Raw Dolomites For Refractory Brick Production, Rodolfo Trevino Cantu

Masters Theses

"Two Mexican dolomites were characterized in order to discover their suitability for production of refractory brick.

The results were compared with other dolomites from American Companies. Some samples were burned in a gas fired Laboratory Furnace and others were obtained in the burned state after processing in Industrial Rotary Kilns.

The characterization procedures included X-Ray Diffraction, Scanning Auger Microprobe, DTA and TGA techniques, Chemical Analysis and Bulk Density measurements.

The procedure to control the quality of the dead-burned dolomite at the industrial level was established taking as the main criteria, bulk density, hydration susceptibility, and impurity levels"--Abstract, page ii.

Denitrification Of A Synthetic Waste With A Submerged Filter, Dominic Joseph Grana

Masters Theses

"The facultative anaerobic submerged filter is a plug flow, packed bed, column type reactor in which the facultative microorganisms responsible for nitrate reduction are attached to the filter media. The objective of this study was to evaluate filter performance and the kinetic equations of the process under variable conditions of flow rate, nitrate nitrogen concentration, and organic loading.

Two 0.5 cu ft (14.25 1) laboratory filters were operated for 144 days at 35°C using a synthetic waste as the substrate. Filter media consisted of smooth quartzite stone, 1 to 1.5 in. (2.54-3.82 cm) in diameter. Each filter had a porosity …

Experimental Study Of Electron Density And Confinement Time In An Electrostatically-Plugged Cusp Device Using A Microwave Interferometer, Robert Louis Hayward

Masters Theses

"The average electron density and electron confinement time in an electrostatically plugged magnetic spindle cusp device are studied using a 20 GHz microwave interferometer. The results are compared with the predictions from approximate theoretical equations. With a magnetic induction in the point cusp of 5000 Gauss, a plasma is produced by injecting a 5 mA, 500 eV electron beam into hydrogen gas at 10^-5 Torr. The measured electron density is 2 x 10^-10 cm^-3 and the measured confinement time is 80 ysec, which agree to within a factor of two with values predicted by theory"--Abstract, page ii.

Application Of Voltammetry To Copper Electrodeposition, Louis Francis Toth Jr.

Doctoral Dissertations

"A study was undertaken to determine the feasibility of using voltammetry and scanning electron microscopy techniques to characterize copper deposition from an acid-sulfate electrolyte. The main process variables investigated were temperature and addition agents (chloride ion, glue, separan or thiourea) at different concentrations, over a range of current densities. Cathodes employed were either polycrystalline titanium or copper. Some long-time copper deposits were also made using Ti cathodes and the orientations of these deposits were determined by x-ray diffraction.

Observations of copper crystals produced during voltammetry scans, on a Ti cathode, indicated that a characteristic morphology was associated with each type …

Design, Fabrication, And Application Of Uniformly Distributed Rc Networks For Use In Electronic Circuits, Michael Flynn Kavanaugh

Doctoral Dissertations

"In the design of electronic circuits, both linear and non-linear, one of the goals is the reduction of the number of elements needed to complete the design. By using distributed RC networks a reduction in the number of elements by at least 50% is usually possible. This dissertation discusses several distributed RC networks, develops detailed design procedures for each, and applies them in the design of electronic circuits.

The indefinite admittance matrix (IAM) for the DRURC (double-resistive uniformly distributed RC network) and the URC (single-resistive uniformly distributed RC network) , which have been previously derived, are used as the starting …

Optimizing Underground, Trackless Loading And Hauling Systems, Richard Lee Bullock

Doctoral Dissertations

"Determining the optimum system and equipment to be utilized in today's underground trackless haulage mine is a complex problem which was dealt with in this research by systems simulation. The computer program developed by the Caterpillar Tractor Company served as the starting point for simulating the equipment's capabilities to move material over a course in a prescribed time. Extensive time studies of the unsimulated events lead to structuring this program in the deterministic mode since it was felt to be more acceptable to the operating management which would eventually use the technique. Every phase of the simulation was successfully validated …

Influence Of Initial Turbulence Intensity On The Heat And Moisture Transfer Through A Recirculated Air Curtain, Nguyen Quang Van

Doctoral Dissertations

"An air curtain is a directed jet of air separating a controlled space from an environment of different temperature and humidity. This investigation describes the development and verification of an eddy viscosity model which accounts for the influence of the initial turbulence intensity on the transfer of heat and moisture across a recirculated air curtain. The control of the turbulence intensity at the nozzle exit of an air curtain permits control of heat and moisture transfer and therefore the energy required to operate the air curtain.

Both theoretical and experimental studies were made of the recirculated air curtain. An explicit …

Bit Penetration Into Rock - A Finite Element Study, Jaw-Kuang Wang

Doctoral Dissertations

"A finite element approach has been developed to simulate bit penetration from bit-rock interaction to chip formation. A mathematical rock failure model, based on a review of the existing literature on rock tests, has been proposed to represent post-failure rock behavior and applied in the penetration simulations. The finite element program has been developed for two dimensional plane strain problems with non-linear material properties, geometrical nonlinearities and fracture. An anisotropic element as well as variable stiffness and stress release methods have been used. An iteration method, using an incremental approach, has been applied for continuous penetration and modifications of material …

Variables Affecting The Rate Of Solution Of Mold Inoculants In Cast Iron, Jose Osorno Fonnegra

Masters Theses

"The purpose of this investigation was to measure the effectiveness of an inoculant alloy reacting with molten cast iron in a reaction chamber properly located in the gating system.

The chemical composition of the gray iron was held constant while several metallurgical factors were varied to produce test samples with different cementite thicknesses. These chill depths were measured as an indication of the inoculation effectiveness.

Appreciable differences in chilling tendency were observed within the different variables studied. The results indicate that pouring temperature, as well as the other variables studied, are of considerable importance when dealing with inoculation of gray …

Development Of Helicopter Flight Path Models Utilizing Modern Control Techniques, Alfred Fermelia

Doctoral Dissertations

"The nonlinear set of equations which represents helicopter motion are linearized about a prescribed nominal state. Once the linearized system is obtained it is validated by comparing the output of the nonlinear system to that of its linearized counterpart. Having obtained a linear model, linear system theory may then be applied in order to investigate the stability and control characteristics of the aircraft.

General techniques for simulating helicopter pilot response for inclusion in a flight path simulation program have been devised. To provide the desired flight goal, a nominal flight trajectory is obtained from an existing nonlinear model. With this …

Effect Of Photoneutrons On Transients Of Beryllium Reflected Reactors, Safdar Ahmad Ali

Doctoral Dissertations

"An analytical model is developed to account for the photoneutron sources present in a beryllium reflector. The time-dependent, two- dimensional and three energy-group diffusion equations are written with an additional photoneutron source term. Then an approximate flux composed of two spatial shapes chosen beforehand, each having an unknown time coefficient, is inserted into time-dependent multigroup equations and the weighted residual criterion is applied. This yielded multimode kinetics equations with generalized definitions for conventional matrix parameters: generation time, reactivity, delayed neutron and delayed photoneutron fraction matrices.

Two transients are analyzed for the University of Missouri Research Reactor: simulation of rod drop …

Corrosion And Electrochemical Behavior Of Indium And Indium-Bismuth Alloys In Hydrochloric Acid, Yar Ming Wang

Doctoral Dissertations

"The corrosion of In-Bi alloys was studied using X-ray, scanning electron microscopy, atomic absorption spectroscopy, and cyclic voltammetry techniques.

Calculated activation energy values indicated that the corrosion of In-Bi alloys was activation controlled. The effect of amine mixtures on the corrosion of In and In₂Bi (ß₁ phase) was studied. Morphological studies revealed that the porosity of the resulting physical surface structure was influential in determining the corrosion rate. In deaerated 3N HCl solutions, the selective dissolution of indium was the predominant mechanism in the corrosion of In-Bi alloys. The corrosion was always accompanied by a phase change …

Excitation Of Source Electromagnetic Waves At Microwave Frequencies Using Optical Techniques, M. Davarpanah

Doctoral Dissertations

"The coupling efficiencies for the excitation of surface electromagnetic waves (SEW} for both the prism and the grating techniques have been studied experimentally in the microwave frequency range. The grating experiments included studies of the SEW coupling efficiencies as functions of the frequency, the angle of incidence, the grating constant, the number of grating bars, and the position of the grating bar at which the maximum radiation field of the antenna was aimed. For the prism coupling technique, the coupling efficiency was studied as functions of the angle of incidence, the aiming point of the transmitting antenna on the prism …