Engineering Commons^™

The Morphology Of Cellular Precipitation In Aluminum Rich Aluminum-Silver Alloys, Santiago Ibarra Jr.

Doctoral Dissertations

"The morphology of cellular precipitation in Al-29.8wt%Ag alloy has been investigated in bulk specimens by transmission electron microscopy and in solution treated specimens by means of hot stage microscopy. Both cellular and general precipitation were observed to occur simultaneously in quench-aged and isothermally aged alloys. By studying the early stages of precipitation in the hot stage, the mechanism for the growth of cells in Al-Ag alloys was developed. According to this mechanism, the grain boundary allotriomorphs begin to form, the boundary then interacts with the allotriomorphs by bowing, and then either trailing precipitation forms on the allotriomorphs or new lamellae …

An Asynchronous Circuit Design Language System, Gregory Martin Bednar

Doctoral Dissertations

"This paper presents a system for specifying the behavior of asynchronous sequential circuits. The system consists of a special purpose Asynchronous Circuit Design Language (ACDL), a translator and a flow table generation algorithm. The language includes many special features which permit quick and precise specification of terminal behavior. It is best suited for problems originating from a word description of the circuit's operation. The translator is written with the XPL Translator Writing System and is a syntax-directed compilation method. From the translated ACDL specifications, the flow table algorithm generates a primitive flow table which is the required input for the …

Distributed-Network Realizations For The Simulation Of Partial Differential Equations, Roy Dale Hensley

Doctoral Dissertations

"A method is developed for the simulation of the partial differential equation

-u_xx + k_ou_tt + k_lu_t +k₂u = g(t)

for various boundary conditions. The boundary conditions are used to classify the problems into types and the Laplace transformed solution of the most general problem of each type is obtained.

Synthesis techniques are presented for the realization of circuits containing distributed networks that can be used to simulate the partial differential equation for given boundary conditions. Several heat flow and vibrating string examples are included to illustrate the application of the …

Determination Of Thermal Contact Resistance Between Metals Using A Pulse Technique, William Edward Stewart Jr.

Doctoral Dissertations

"This dissertation reports the results of an experimental and analytical investigation to determine the thermal contact resistance of several metal specimen pairs using a relatively new pulse technique. Metal specimens were aluminum 2024-T3, aluminum 6061-T6, aluminum 7075-T6, copper 110, stainless steel 304, molybdenum, and Armco iron. Thermal contact resistance was also determined for dissimilar metal specimen pairs of aluminum 6061-T6 - copper 110 and aluminum 7075-T6 - copper 110. Aluminum 7075-T6, copper 110, and stainless steel 304 specimens were tested to determine the variance of contact resistance with time after loading.

Specimens were circular cylindrical disks between .033 and .061 …

Digital Spectrum Analyzer Systems: A Model And System Implementation, Richard Ray Kuenzer

Doctoral Dissertations

"This thesis introduces digital spectrum analyzer systems and presents a generalized model which can be used to implement new systems. The model is presented using the Digital Design Language (DDL) to facilitate system programming. Three hardware systems are defined and their merits are considered. Procedures are given to aid in implementing an analyzer system on a wide range of hardware configurations. A digital spectrum analyzer system which was implemented at the University of Missouri - Rolla and is presently being used by electrical engineering students is presented. This system utilizes the IBM 360/SO computer located in the Computer Center at …

Mass Transfer With Second-Order Chemical Reaction Inside Circulating Fluid Droplets, Roy James Brunson

Doctoral Dissertations

"The solution of a mathematical model is presented which describes mass transfer accompanied by a second-order chemical reaction inside a circulating, fluid sphere for the laminar flow region. The values for eight different mass transfer indices are presented as a function of the Peclet number, reaction number, diffusivity ratio, concentration ratio, and the dimensionless contact time. The results of this work are compared with the film and penetration theories for mass transfer with reaction as modified to apply inside a fluid sphere. This work corrects the three factors which limit the accuracy of applying previous theories to fluid spheres: geometrical …

A Learning Receiver For Communication In Three-Component Multipath Channels, Richard Paul Brueggemann

Doctoral Dissertations

"An adaptive receiver is designed for transmissions through a time-varying multipath channel which may include both specular and diffuse components. The design is based on the theory of unsupervised learning machines and the receiver is a recursive structure which does not grow in complexity with each new observation, but is Bayes' optimal at each instant of time. The multipath medium is modelled as an aggregate of L conditionally independent transmission paths, each consisting of random and/or fixed reflections, and is identified in terms of three components: (1) indirect diffuse scatter, (2) indirect specular reflection, and (3) direct transmission. The channel …

The Effect And Compensation Of Time-Base Perturbations In Analog Recording Systems, Clifford D. Skouby

Doctoral Dissertations

"The mean square error between recorded and reproduced signals is used as an error measure to determine the effects of time-base perturbations on an analog singal. The mean square error caused by time-base perturbations is shown to be proportional to the product of the square of the signal bandwidth and the time-base error variance for the case of low pass signal. When the signal is band pass, there is shown to be an additional error term which is proportional to the square of the signal center frequency and the time-base error variance.

Calculations are also carried out to determine the …

Iicads--Integrated Interactive Computer Aided Design System, Archie Golden Lambert

Doctoral Dissertations

"This research has three goals. The first goal is to develop a software interface (supervisor) to support and control a variety of interactive subsystem modules; thus eliminating manual scheduling of interactive jobs. The second goal is to develop a common methodology for interactive subsystem design. The third goal is to develop a linear systems analysis package using the facilities developed under the first two goals. A software interface (supervisor) to support and control a variety of interactive subsystem modules is described. The supervisor operates under the constraints of a large multiprogramming variable task operating system as opposed to a time …

Computer Assisted Teaching Of Steel Design, Wendelin Henry Mueller Iii

Doctoral Dissertations

"A method for use in creating a university level course is presented. The specifics of each of the steps is given in general terms to allow its application to as many different topics as possible. This method is then specifically applied in the formation of a fundamental steel design course using the American Institute of Steel Construction Specification. The reasoning utilized in each phase of development is documented. A lecture style presentation complemented by a series of student oriented computer programs was chosen for use. The details of the course material in outline form is given along with the computer …

Synthesis And Properties Of Cadmium Manganese Ferrites, B. W. Jong

Doctoral Dissertations

"The formation sequence of (Cd,Mn,Fe) (Mn,Fe)₂O₄ from the individual oxides,x CdO + (1-x) MnCO₃ + α-Fe₂O₃,was found by X-Ray diffraction. Cd(Mn,Fe)₂O₄ was formed completely from CdO·Fe₂O₃ and CdO·Fe₂O₄ at 900°C and reacted with MnFe₂O₄ for 0 < x < 0.5 and with α-Fe₂O₃ for 0.5 < x < 1.0 to form a single phase of (Cd,Mn,Fe) (Mn,Fe)₂O₄ at 1150°C. This is the first time that the details involved in the formation sequence of CdMn-ferrite have been shown. A mixture of 0.5 CdO + 0.5 MnCO₃ + α-Fe₂O₃ was calcined at 900°C for 2 hrs forming Cd(Mn,Fe)₂O₄ with no Cd present in the other phases. Sintering was accomplished at 1150°C for 30 minutes forming a single phase of Cd₀.₅Mn₀.₅Fe₂O₄ with a bulk sintered density of 98-99% of the X-Ray density. The rate of changing density followed the relationship, p = K ln t + c, at temperatures between 1050°C and 1300°C. Magnetic properties of CdₓMn₁₋ₓFe₂O₄ were affected by composition x. A relationship, B = gx + h, was found between maximum magnetic flux density B and composition x at room temperature for 0 <̲ x <̲ 0.3. This was rationalized by a modification of Néel's theory. The maximum magnetic flux density decreased with increasing cadmium concentration for 0.3 < x <̲ 0.5. This decrease was attributed to the changing direction of the magnetic moment in the octahedral site sub-lattice according to the superexchange theory. No magnetic properties were observed due to the formation of a compensated antiferromagnetic phase for 0.5 < x <̲ 1.0. Maximum magnetic flux density increased with bulk density, while the coercive force decreased with the grain growth and the initial permeability increased with the bulk density and grain size. A stator core used for a-c electric motor application was formed by pre-sintering at 900⁰C for 2 hrs. Slots were then sawed with a tungsten carbide blade and final sintering was accomplished at 1150⁰C for 1 hr"--Abstract, pages iii-iv.

Methods And Applications Of Systems Identification, Allen Glenn Behring

Doctoral Dissertations

"A "Schmidt filter" is proposed to compute an optimal orthonormal basis for a set of "noisy" filter input functions. Procedures for determining the transfer function and inverse transfer function of the filter are given. The Schmidt filter is applied to the problem of determining mathematical models of discrete, stationary, linear, dynamic systems for the case where measurements may be corrupted by noise of unknown statistics. The identification problem is reconsidered for the case where noise and signal moments are specified. Procedures are given which insure unbiased, adaptive estimates of system order and parameters for this case. These theoretical propositions are …

Hydro-Thermal Generation Unit Commitment And Dispatch Using A Dynamic Programming Approach, Warren Dean Graham

Doctoral Dissertations

"The problem of thermal unit commitment is solved with dynamic programming. A practical example is given which solves the problem for a six generator system over a one year time span. This long range solution is used with a hydro optimization procedure to give an optimized hydro-thermal unit commitment solution. From this, a worth of hydro value is computed for each month, which may be used in the daily dispatching of thermal units and hydro. Applications of the program are also shown for aiding in generator maintenance scheduling and evaluating purchase power contracts with neighboring utilities. Error analysis is made …

Effects Of Cr-Plating And Environment On The Cracking Of Low Alloy Steels At High Temperatures, Robert C. Tooke

Doctoral Dissertations

"The cracking of low alloy Cr-Mo-V steels under cyclic stress at 1000-1100°C. was studied using a specially designed test apparatus. The results obtained from specimens plated with hard chromium are compared to those of unplated specimens. Tests conducted in gas mixtures of carbon monoxide and carbon dioxide showed that a high CO/CO₂ ratio retards cracking in both plated and unplated specimens. Both external and internal oxidation are used to explain these results. Inherent microcracks in the hard chromium plating promoted cracking in all CO/CO₂ environments. It was also found that these steels are severely embrittled in the presence …

An Experimental Investigation Of The Effects Of Ambient And Heated Steady Flow And Intense Sound Levels On The Response Of Acoustic Filter Elements, Raymond H. Schaffart

Doctoral Dissertations

"The primary purpose of this research was to investigate the effects of flow and finite amplitude waves on the response of acoustic elements. A further purpose was to evaluate the effects of elevated temperatures and cross-sectional dimensions on element performance. As an integral part of this work various laboratory techniques were explored for their suitability.

Empirical models for the acoustic impedance of side branch resonators were developed for the two operational modes, i.e., flow past the resonator and finite amplitude wave inputs. A description of the complex variation of the acoustic resistance of the resonator with flow past and variable …

Performance Of Self Bit Synchronizers For Binary Overlapping Signals, Chung-Tao David Wang

Doctoral Dissertations

"This research is concerned with the optimum and suboptimum ways of providing self bit synchronization for binary overlapping signals. A maximum likelihood synchronizer is derived as the optimum approach. The suboptimum ways are those employing decision-directed feedback and matched derivative filter techniques which are proposed for treating the overlapping signals. Combining the two suboptimum techniques along with the bandlimited version of the overlapping signal, a suboptimum synchronizer is derived. The performance of the above synchronizer is evaluated by Monte Carlo simulation techniques. Finally, a bit synchronizer using nonlinear filtering theory is considered. The performance of a nonlinear bit synchronizer is …

The Electrochemical Reduction Of Fumaric Acid On Hg-Bi Cathodes, Chen Hwei Chi

Doctoral Dissertations

"The electrochemical reduction of fumaric acid was studied on Hg, Hg/1%Bi amalgam, and Bi at 60ºC in acidic solutions of various pH ranging from 0.3 to 3.7. The fumaric acid was reduced to succinic acid with high efficiency on each electrode. The steady state kinetic parameters included Tafel slopes of ca. 2.3 RT/F and first order concentration dependences for both undissociated fumaric acid and H⁺. Transient measurements indicated low coverages of adsorbed fumaric acid and no adsorbed hydrogen species in the potential region of the reaction. A reaction mechanism is proposed which involves a chemical rate determining step between an …

A Study Of The Solid Regions In The System Zr-Te, Frances Dolores Jenkins

Doctoral Dissertations

"Relative intensity measurements of X-ray powder diffraction lines were made of compositions in the region ZrTe₀.₅ to ZrTe₂.₀, fired between 600º and 817ºC in evacuated sealed tubes. The experimental relative intensities of samples between ZrTe and ZrTe₂ were compared with values calculated for several theoretical models with different Zr vacancy ordering schemes and Te vacancy concentrations. The most probable structural model for compositions in the range ZrTe to ZrTe₁.₅ is one in which the number of Zr vacancies located at z = 0 ranges from 0% to 30%, with the concentration of Te vacancies ranging from 0 to 35%. A …

A Yield And Fracture Model For Ti-6al-4v Titanium And 7075-T6 Aluminum, Richard L. Pendleton

Doctoral Dissertations

"The objective of the research being reported in this thesis was to conduct a series of experiments on two commonly used structural metals in several different environmental pressures so that a graphical representation of the material response both to yielding and fracture could be ascertained. It was further intended to show that parameters herein defined and called effective stress, effective strain, and pressure are useful parameters for graphically representing the material response. The final goal of this research was to show that the graphical representation does, in fact, predict the yield and fracture for a simple forming process. The forming …

Probabilistic Models For Construction Estimating And Bidding, James E. Spooner

Doctoral Dissertations

"Two probabilistic models are offered as a means for quantitatively determining contingency in a lump-sum bid. The first model is based on the isolated project and requires subjective evaluation of probabilities associated with the individual elements of the estimate. Contingency is defined as a function of the standard deviation of project field costs. Procedures are developed to obtain the variance of the total field cost from three-value estimates of the primary quantities. The second model considers the business as a stochastic process with an initial risk reserve and a positive risk loading, and contingency in this model is a function …

A Numerical, Time Domain Solution For The Response Of A Gimbal Supported Gyro, Floyd Stanley Hall

Doctoral Dissertations

"This paper develops an algorithm to generate a numerical solution for the response of a gimbal supported gyro to arbitrary forcing functions and base motion, and includes the normal parasitic effects of bearing friction, viscous pivot damping, and pivot spring constants. There are relatively few restrictions on gyro and gimbal structure geometry. Solution accuracy is limited only by the computing machine accuracy; the algorithm being an explicit function of the input data. The algorithm is fast and requires only a moderate amount of computer memory"--Abstract, page ii.

The Average Dissipation Curve Of An Attenuative Layered Earth Medium, Joong Hee Chun

Doctoral Dissertations

"A feasible method of estimating the attenuative properties of a layered earth medium from a reflection seismogram has been developed. An average attenuation factor of n layers in the least squares sense is designated as ß and its usefulness in real applications is investigated. Techniques of extracting dissipation factors from both noise free and noisy reflection seismic traces are discussed. In order to describe the change of the factors with an increase of depth, an average dissipation curve the form of which is similar to the average velocity of layered medium is also introduced. Both the ß and the average …

A Comparison Of Analytical And Experimental Approaches In Determining The Thermoelastic Stresses Around A Cylindrical Inclusion Of Elliptical Cross-Section, Kenneth Byron Oster

Masters Theses

"Three approaches are used to determine the principal stress differences in an infinite elastic medium containing a cylindrical inclusion of elliptic cross-section due to a uniform temperature change. First, the two-dimensional equations of thermoelasticity are solved resulting in equations for the stress components anywhere in the medium material. Second, boundary displacements based on stress-strain relations are used as input displacements in a finite element program of the medium. Third, these same boundary displacements are used as input displacements on a photoelastic model simulating the medium. The problem is treated as one of plane strain in the first approach and one …

Continuous Interfacial Polycondensation Of Nylon 6-6, Chandrakant A. Patel

Theses

Nylon 6-6 has been prepared by continuous interfacial polycondensation from hexamethylene diamine and adipyl chloride in a stirred system. The effect of monomer concentration and stirring on the intrinsic viscosity of polyamide 6-6 solution in formic acid (90%) was determined.

As stirring rate and monomer ratio increased, the intrinsic viscosity and polymer yield went through a maximum. Diffusion coefficient (D_AB) for hexamethylene diamine was calculated and from that J_D and mass transfer coefficient /D_AB were calculated. A relation between Reynolds number and J_D factor was established by correlation curve.

A Monte Carlo Calculation Of Neutron Reflection From Various Curved Surfaces, Charles Jack Kalter

Doctoral Dissertations

"Plane parallel neutron beams normally incident upon the curved surface of a solid reflector are studied with the Monte Carlo method. The geometries studied are cylindrical, parabolic, and hemispherical. It is shown that when the curved surface is cylindrical, a small "focusing effect" occurs in the reflected neutron beam. Parabolic and hemispherical surfaces do not show "focusing". A study of the factors which determine the spatial dependence of the reflected flux shows that the probability of emergence of a neutron, traveling a fixed distance from a point inside the reflector, depends upon the curvature of the surface. It is only …

Comprehensive Calculations Of The Parameters Describing Proton Energy Loss In Matter, Joseph F. Janni

Nuclear Engineering ETDs

Extensive calculations have been made of the mean energy loss, pathlength, range, multiple scattering, and pathlength straggling of protons in many materials. Emphasis has been placed on obtaining accurate results, especially for heavy materials and protons of very low energy. Values of the energy loss between .01 and 1.0 Mev were obtained by smoothing and interpolating experimental information. Above 1.0 Mev, the Bethe equation with all the necessary shell corrections has been used. Values of the adjusted ionization potential have been determined by least squares fitting the Bethe equation to all available energy loss data. The polarization effect has been …

Theoretical And Experimental Study Of Explosive Closures Of 6061-0 Aluminum Pipes, Lyle E. Edwards

Mechanical Engineering ETDs

This thesis examines the use of explosives to collapse metal pipes from an applications point-of-view. A particular system is studied, both theoretically and experimentally, in order to facilitate the future design of such closures with the least possible physical testing. The calculations are based on a rigid-perfectly plastic model of the observed deformations of the tubes, and on various assumed am derived properties of the metal and sheet explosives under the dynamic conditions of closure. A computer program has been devised which simulates the actual motion of a pipe during collapse. Experimental work involved actual test firing of aluminum cylinders …

Free Vibration Of Plates Stiffened By Parallel Ribs., Charles Edward Bacchus

Civil Engineering ETDs

A method is presented to obtain the natural frequencies and related mode shapes of certain types of stiffened plate systems. Dynamic stiffness matrices, based on ordinary assumptions in beam and plate theory, are derived to relate the displacements at the edges of a system element to the edge forces. Both in-plane and transverse forces and displacements are considered. Compatibility and equilibrium conditions at the intersections of plate panels and stiffening elements are employed to derive the governing equations of the system.

For general systems, the result is a set of linear homogeneous algebraic equations which must be solved by trial-and-error. …

Techniques For Active 3he Activation Analysis For Carbon And Oxygen, William Mort Sanders

Nuclear Engineering ETDs

The surface and body concentrations of carbon and oxygen have been measured in various materials using ³He activation. Channeling techniques have been used to differentiate between interstitial and substitutional location of these impurities.

Thin target excitation functions were determined for (³He,p) reactions with carbon and oxygen over a ³He energy range from 2.5 to 9.0 MeV. These data were used to calculate the activation curves for various combinations of incident particle energy, impurity distributions, and material.

Information on several computer codes used during this study is presented.

Computer Solution To Inverse Problems Of Elliptic Form: V²U(X,Y) = G(A,U,X,Y), Frederick Alvin Jeter

Dissertations and Theses

One important aspect of our present age of monolithic high speed computers is the computer's capability to solve complex problems hitherto impossible to tackle due to their complexity. This paper explains how to use a. digital computer to solve a specific type of problem; specifically, to find the inverse solution of a in the elliptical equation V²U(x,y) = g(a,U,x,y), with appropriate boundary conditions. This equation is very useful in the electronics field. The knowns are the complete set of boundary values of U(x,y) and a set of observations taken on internal points of U(x,y). Given this information, plus …