Engineering Commons^™

An Analysis Of Mill Sound Levels To Aid In The Control And Understanding Of The Grinding Process, Scott Douglas Morrison

Doctoral Dissertations

“An experimental study has been made to evaluate the relationships between grinding parameters and the directional sound levels emitted from the collision of the grinding media with the mill wall for a laboratory batch ball mill.

Discrete frequency and single frequency band sound pressure level measurements were performed to investigate the changes in sound levels with grind time. It was demonstrated that the reduction in sound levels with grind time observed for a narrow sized feed can be used to indicate optimum breakage rates, overall time-based particle size distribution, and ore character.

The relationships established with the discrete frequency and …

Dissolution Of Multi-Component Systems, Robin Ashley Murphy

Doctoral Dissertations

"The validity of ideal barrier layer diffusion kinetics was examined in the NaCl/KCl - glycerol and Al₂O₃-CaO-Al₂O₃-SiO₂/slag corrosion systems. Single crystals and dense polycrystalline plates of pure NaCl or KCl exhibit steady-state corrosion rates within 10%, of calculated theoretical values, while dense mixtures of the two salts corrode at rates higher than either pure material. The results are compared to the grooving phenomena of NaCl/KCl bicrystals.

Polycrystalline Al₂O₃ is shown to corrode at the same rate as single crystal sapphire at 1400°C in CaO-SiO₂-Al_{2 …}

Electrochemical Evaluation Of Zinc Electrolyte, Rajesh Kumar Singh

Doctoral Dissertations

"The polarization characteristics of acidified zinc sulfate electrolyte with varying solution chemistries were examined by cyclic voltammetry. An attempt was made to correlate the polarization results with the morphological and current efficiency data in order to develop a better understanding of the more fundamental aspects of impurity and additive behavior during the zinc electrodeposition process.

A statistical screening design program was conducted to determine the effects of certain operating parameters on the nucleation potential of zinc from sulfate electrolyte. The variables studied included: solution temperature, H₂SO₄ and Zn concentration, and scan rate. The solution temperature was found to be the …

Mass Transport Considerations In Electrometallurgical Reactions, Jose Rolando Sami Cuzmar

Doctoral Dissertations

"The research program described is divided into three segments. In the first part, the morphology and kinetic studies of Cd²⁺ removal from ZnSO₄ solutions using Zn dust as a reducing agent are presented. In the absence of impurities, the morphology of the Cd deposit shows the formation of two-dimensional or leaf-like dendrites capable of interlocking and forming agglomerates or balls. The size and strength of the agglomerates depend on the initial Cd²⁺ concentration to Zn metal surface area ratio, the rate of Cd ²⁺ removal, and the reactor geometry. The presence of additives, like Cu²⁺ and …

A Study Of The Permeability Of Clays Subjected To Organic And Inorganic Permeants, Janardanan O. Uppot

Doctoral Dissertations

"Two types of clays, a magnesium montrnorillonite and a kaolinite, were subjected to precise permeability tests in specially designed triaxial permeameters, using organic and inorgani c permeants, to study the changes in permeability due to the reaction between clays and permeants. The organic permeants were an acid (acetic acid), a base (aniline), a neutral polar fluid (methanol), a neutral nonpolar fluid (xylene), as well as EDTA and its sodium salt. The inorganic permeants were aqueous solutions of aluminum, magnesium, sodium, calcium, barium and strontium.

The clay samples were prepared by consolidating from slurry; they were subjected to back-pressure saturation and …

The Modeling And Control Of Freeze Dryers, Martin James Millman

Doctoral Dissertations

"Two models of the freeze drying process were constructed and used to study various operational policies in order to determine the policy that would provide the shortest drying times.

The sublimation model which accounts only for the removal of frozen water, is found to predict shorter times for the free water removal phase than the sorption-sublimation model which properly accounts for the removal of frozen and bound water.

This study shows that the policy which produces the shortest free water removal phase, also produces the shortest overall drying time. This policy, predicted by both models, holds the chamber pressure at …

Thermogravimetric And Electrical Conductivity Studies Of Mg-Doped Lacro₃ And La-Doped Srtio₃, Brian Keith Flandermeyer

Doctoral Dissertations

"Mg-doped LaCrO₃ and La-doped SrTiO₃ are perovskite compounds that display electrical conductivity which is a function of partial pressure of oxygen (po2). It has been proposed that acceptor-doped LaCrO₃ becomes highly resistive at low po2's due to ionic compensation of the acceptor-dopant present by oxygen vacancies. SrTiO₃ has been thought to absorb O₂ into a crystallographic shear structure and exsolve strontium vacancies which can then ionically compensate the La present and give a high resistance at high po2's.

Given these models, relationships between weight loss and conductivity vs. po₂ are developed for both these …

Fixed Bed Sorption With Recycle, John Thomas Casey

Doctoral Dissertations

"A mathematical model that describes single and multicomponent recycle-sorption systems is constructed. The model accounts for the generation of species by chemical reactions occurring in a single perfectly mixed tank, in the bulk fluid of the sorbent bed, and in the pores of the adsorbent particles.

Results are shown for single zeroth, first and second order reversible reactions as well as a network consisting of two first or second order reactions which may occur in series or parallel. For systems in which a single reaction occurs, both linear and non-linear equilibrium adsorption isotherms are considered. If multiple reactions occur, then …

Applications Of Finite And Wave Envelope Element Approximations To Acoustic Radiation From Turbofan Engine Inlets In Flight, A. V. Parrett

Doctoral Dissertations

"The problem of acoustic radiation from turbofan engine inlets in flow has not lent itself fully to analysis by numerical means because of the large domains and high frequencies involved. This project has extended the use of finite elements and wave envelope elements, elements which simulate decay and wavelike behaviour in their interpolation functions, from the no-flow case in which they have been proven, to cases incorporating mean flow. By employing an irrotational mean flow assumption, the acoustics problem has been posed in an axisymmetric formulation in terms of acoustic velocity potential, thus minimising computer solution storage requirements. The wave …

Unsteady-State Cylindrical, Spherical And Linear Flow In Porous Media, Allan Jeffrey Anthony Joseph

Doctoral Dissertations

"The general problem of unsteady flow phenomena in porous media as considered in this investigation. Emphasis was placed upon the short-term flow characteristics within cylindrical, spherical and linear reservoir geometries, and practical analysis methods were developed for each problem. Additionally, nonlinear unsteady flow behavior in infinite reservoirs was considered. Each solution obtained could optionally be implemented by hand or computer, and several FORTRAN subprograms were also presented.

At present, the only way to analyze pressure transient data prior to the development of the "semi log straight line" is by type curve matching techniques. However, this study indicated that a reliable …

The Performance Of Full Response Multi-H Modems In Practical Environments, Mark Alan Wickert

Doctoral Dissertations

The power and bandwidth efficiency of multi-h continuous- phase modulation (CPM) schemes in practical environments are considered. Specific impairments considered are transmitter filtering, amplitude limiting, and receiver symbol timing, phase error, and decision depth sensitivities. A coherent receiver model is employed which uses the Viterbi algorithm (VA) to perform maximum likelihood sequence estimation. For (2/4,3/4), ll (3/8,4/8) and (4/8,5/8) linear phase codes, a signal-to noise ratio (SNR) power gain of 1.85 dB, 1.9 dB, and 2.4 dB at a bit error rate (BER) of 10^-5 over differentially coded minimum-shift keyed (MSK) modulation are obtained, respectively. With transmitter filtering the …

The Influence Of Additives And Their Interactions On Copper Electrorefining, Chwan-Tsann Wang

Doctoral Dissertations

"Protein colloid (glue), thiourea, Avitone and chloride ion are the most common additives used electrorefining copper. The polarization behavior of these additives, single and combined, was studied by cyclic voltammetry techniques in conjunction with stationary and rotating disc electrodes. In the stationary electrode work, different protein colloids give substantially different results in polarization or interaction with other additives. The role played by Avitone is not clear, but it does somewhat modify other additives in the electrolyte. Thiourea can cause a depolarized peak and a polarized plateau depending on the concentration, the other additives present and the potential selected. Chloride ion …

Chemical Corrosion Of Ag Films On Glass, Hyun Soo Park

Doctoral Dissertations

"The chemical corrosion of chemically, vacuum and sputter deposited Ag films on an aluminoborosilicate and a soda lime glass was investigated in wet HCl and saturated water vapor as a function of concentration, temperature and time. The higher corrosion resistance of chemically deposited Ag films in comparison to evaporated or sputtered Ag films is attributed to their lower microvoid density and higher adhesion strength. Ag films on the more chemically durable aluminoborosilicate glass had a higher corrosion resistance. Furthermore, films which received a moderate thermal annealing (80 to 140° C) or were deposited on a glass surface washed with HN0 …

Gaseous Reactions In Heteroporous Media, Elmer Anthony Klavetter

Doctoral Dissertations

"A modified dusty-gas model which accounts for the effects the pore-size and tortuosity distributions have on the mass fluxes in heteroporous media is presented. The behavior of the dusty-gas model (homoporous model) can be obtained from the modified model when the pressure is either very low or very high as well as for intermediate pressures when the characteristic parameter of the introduced tortuosity function has a very small value. When the pressure is very high or very low, all pores in the porous medium are almost in a single transport regime of either molecular or Knudsen diffusion.

Comparisons of the …

Comparative Study Of The Boundary Element Technique And The Finite Element Method In Two Dimensional Eigenvalue Problem, Farough Baradari

Doctoral Dissertations

"In this work we investigate the applicability of a "Boundary Element method 11 for the numerical solution of the Liouville and Helmholtz eigenvalue problem for different two-dimensional geometries including a typical reactor configuration. The method is based on the discretization of the unknown along the boundary and Green's function representation of the governing equation.

To compare the capability of this method with the finite element method, a finite element code which uses quadratic quadrilateral isoperimetric elements was developed. A boundary element code was also written. These codes were used to determine the fundamental eigenvalue for several two-dimensional geometries -- square, …

Load And Resistance Factor Design Of Cold-Formed Steel Structural Members, Boonsong Supornsilaphachai

Doctoral Dissertations

"In a traditional design, the Allowable Stress method has long been used for the design of cold-formed steel structures. In this design approach, the allowable stress is always used to prevent the possible structural failure by using an appropriate factor of safety selected primarily on the basis of engineering judgment and long-time experience.

Recently, the concepts of risk and reliability analysis have been successfully applied to many fields of engineering. By applying the theories of probability and statistics, the load and resistance design criteria for steel structures have been developed for the design of hot-rolled steel shapes and built-up members. …

An Alternate High Pressure Injection System For Pressurized-Water Reactors, Gary Edward Mueller

Doctoral Dissertations

"To evaluate the In-Core Injection System (ICIS) performance during a loss-of-coolant accident (LOCA) due to a major rupture in the primary system of a pressurized water reactor (PWR), tests were conducted using the thermal-hydraulic computer code RELAP4/MOD5.

The results for the overall plant system show that the maximum core average fuel cladding temperature reached during an intermediate size cold-leg break in a Combustion Engineering PWR with ICIS is equal to the initial operating temperature of 335°c (636°F). The maximum core average fuel cladding temperature reached during a large size cold-leg break with ICIS is 478°c (893°F). This temperature is approximately …

Thermally Stimulated Polarization And Depolarization Current (Tspc/Tsdc) In Glass, Chi-Ming Hong

Doctoral Dissertations

"The feasibility of studying ionic motion in glass using thermally stimulated polarization (TSPC)/depolarization current (TSDC) techniques was investigated with 4Na₂O·96SiO₂ and 30PbO·70SiO₂ (mol%) glasses. The TSDC peaks in these glasses were dependent on glass composition and attributed to bulk polarization. The high temperature background TSPC is shown to be due to dc conductivity, whereas the TSPC/TSDC peaks in the 4Na₂O glass are attributed to shorter range Na⁺ motion.

The electrical conductivity of glasses determined by TSPC agrees well with that measured by conventional ac or dc techniques. The TSPC technique is a rapid and easy method of measuring the …

The Effect Of Availability Improvement Of A Nuclear Power Plant On The Cost Of Generating Electricity, Seyyed Mohammad Reza Nejat

Doctoral Dissertations

"The objective of this investigation is to study the economic benefits in operating a nuclear power plant as a result of improving the availability of the secondary (steam) loop of the plant. A new method has been developed to obtain availability, frequency of failure, probability and frequency of operation, cycle time, and uptime for different capacity states of a parallel-series system having components with failure and repair rates distributed exponentially. The method has been applied to different subsystems, systems, and the secondary loop as a whole. The effect of having spare parts for several components, as measured by savings in …

A Development Of Regression Models For Predicting Two-Phase Relative Permeability In Consolidated Rock, Mehdi Honarpour

Doctoral Dissertations

"The primary objective of this study was the development of prediction equations for the water-oil imbibition relative permeability and gas-oil drainage relative permeability from experimental data.

Laboratory relative permeability data along with the corresponding rock and fluid properties were collected, and stepwise linear regression analysis was applied. Relative permeability models were developed in terms of rock and fluid properties.

The prediction models were tested against laboratory values and previously published correlations. It was found that the models developed in this study yield results that are generally in better agreement with experimental values than the previously published correlations"--Abstract p. ii

Phase Equilibria In Aqueous Magnesium Chloride, Sulfate, Chromate And Phosphate Systems, Ladawan Urwongse

Doctoral Dissertations

"In the first part of the present study, which is presented in Paper I, solubility of MgO in aqueous HCl solutions at 23° ± 3°C was measured and combined with analyses of neat magnesium oxychloride cements to construct an equilibrium phase diagram for the system MgO-MgCl₂-H₂O. Invariant liquids in equilibrium with Mg(OH)₂ and 5Mg(OH)₂·MgCl₂·8H₂O (5.1.8), with 5·1·8 and 3Mg(OH)₂·MgCl₂·8H₂O (3·1·8), and with 3·1·8 and MgCl₂·6H₂O were located at 0.8 ± 0.2 MgO, 17.0 ±0.5 MgCl₂; at 1.0 …

Web Crippling Strength And A Combination Of Bending And Web Crippling Of Cold-Formed Steel Beams, Nipon Hetrakul

Doctoral Dissertations

"The web crippling strength of cold-formed steel beams was investigated experimentally. In this investigation, due consideration was given to the possible influence of bending moment and shear force on the web-crippling loads.

For the subject of web crippling strength, the study involved the testing of 140 built-up beams having single unreinforced webs and 152 I-beams having double webs. In addition, 66 beam tests were conducted for the case of combined bending moment, shear and web crippling.

The experimental results obtained from the beam tests conducted at the University of Missouri-Rolla and the early tests performed previously at Cornell University were …

The Effects Of Certain Impurities And Their Interactions On Zinc Electrowinning, Donald R. Fosnacht

Doctoral Dissertations

“The effects of germanium, antimony, arsenic, cobalt, glue, and free acid concentration were studied on both commercial and synthetic electrolytes. The effects of a single factor and the combined effects of multiple factors were elucidated. The temperature, zinc concentration, and current density were also varied. It was found that the acid concentration was the most critical factor when impurity levels were at normal plant solution concentrations. The ranges where the effect of the impurity became apparent were: greater than 20 ppb for antimony; 40 ppb for germanium; 120 ppb for arsenic; and 7-8 mg/l for cobalt for a solution containing …

Adaptive Control Of A Cloud Simulation Chamber Expansion System, Katiya Greigarn

Doctoral Dissertations

"This dissertation describes the design and construction of a closed-loop computer controlled expansion system for a cloud simulation chamber. The chamber is used to simulate atmospheric phenomena for the study of microphysical processes. In order to accomplish this, the sample gas inside the chamber must be expanded adiabatically. This means the wall temperature and the gas temperature must be made to agree as closely as possible. The wall is cooled by thermoelectric modules, and the temperature is controlled by analog controllers. The gas is cooled by the adiabatic expansion, and the corresponding pressure is controlled by a laboratory minicomputer, a …

Cellulase Production By Fermentation With Trichoderma Viride On Cellulose And Wood Wastes, Nguyen Huu Kho

Doctoral Dissertations

"Cellulase production by the fungus Trichoderma viride QM 6a and the use of this cellulase for cellulose hydrolysis were studied using Solka Floc cellulose and waste wood (oak) as substrates. The fermentation produced higher enzyme concentration solutions with media containing additional amounts of soy peptone and KH₂PO₄.

The kinetics of fermentation in fermentors and shake flasks of Solka Floc and sawdust were investigated, and equations were selected to express the relationship of the rates of growth and enzyme production with cell mass, enzyme concentration and substrate remaining in the media.

Agitation and aeration decrease the enzyme …

Theoretical And Experimental Investigation Of Oil Recovery By The Electrothermic Technique, Samy Abdel-Hakeem El-Feky

Doctoral Dissertations

"This work investigates the feasibility of increasing oil recovery from petroleum reservoirs by the electrothermic technique. A mathematical model was developed for the prediction of reservoir response to heating by alternating electric current flow through the oil-bearing formations. The mathematical model was programmed in FORTRAN for solution on the IBM 370/168. The model used the finite difference technique to represent the differential equations that describe the system, and the sets of difference equations were solved by the Strongly Implicit Procedure (SIP) and Successive Overrelaxation (SOR).

In order to verify the mathematical model, a set of experiments was conducted to determine …

Strength Of Cold-Formed Steel Beam Webs In Bending, Shear, And A Combination Of Bending And Shear, Roger A. Laboube

Doctoral Dissertations

"An extensive experimental investigation has been conducted to study the load-carrying capacity of cold-formed steel web elements subjected to bending stress, shear stress, and a combination of bending and shear stresses. Emphasis has been concentrated on the instability and postbuckling strength of beam webs.

In the study of beam webs subjected only to bending, the postbuckling strength of web elements and the effect of the compression flange on the moment capacity have been carefully evaluated for beams having stiffened and unstiffened flanges. Based on 84 test results, formulas have been developed to predict the ultimate moment capacity of cold-formed steel …

Optimal Process Overdesign With A Flowsheet Simulator, Frank Joseph Doering

Doctoral Dissertations

"Overdesign is applied to chemical processes to include additional equipment for improved process reliability or to account for deviations from average conditions. An efficient method to optimize the overdesign of a complex chemical process is developed for use on a flowsheet simulation program. The effectiveness of the method is demonstrated by simulating the sulfuric acid process with metallurgical feed gas on the flowsheet program PROPS. The process is optimized for reliable and variable performance by the adaptive random search algorithm"-- Abstract, p. xi

Electrical Degradation In High Purity Barium Titanate, Jeffrey Duncan Keck

Doctoral Dissertations

"The stability of BaTiO₃-type insulators to DC fields has long been recognized as one of the important factors in determining the quality of a capacitor which uses such a material as its dielectric. The slow increase of the electrical conductivity of an insulator which is stressed by DC fields at levels below the breakdown strength is normally termed degradation. Since degradation is a very common malady to the ceramic capacitor manufacturers, many studies have been conducted over the past two decades in efforts to learn how to remedy the problem.

The results of previous studies have shown that …

Application Of Laser Holographic Interferometry To The Analysis Of Ground Movement Above Underground Openings, Duk-Won Park

Doctoral Dissertations

"A laser holographic interferometric technique has been recently developed and applied to research in several engineering fields. The technique has many possible applications in earth science and engineering. In this study it was shown that laser holographic ii interferometry can be used to study surface ground movements resulting from subsurface cavity collapse.

One of the most important advantages of the holographic interferometric technique is a rapid three-dimensional displacement measurement of a surface without contact or emplacement of instruments. The surface does not have to be flat or smooth allowing deflection contours to be generated on a granular surface. applied in …