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An Sem Surface Study Of Nucleate Pool Boiling Heat Transfer To Saturated Liquid Nitrogen Reduced Pressures From 0.1 To 0.9, David Virgil Porchey

Doctoral Dissertations

"This study constituted an examination of both nucleate boiling and maximum heat flux characteristics of liquid nitrogen boiling from characterized surfaces. Several textures of gold plated copper surfaces were studied in addition to silver and silver oxide surfaces. Data were taken over a wide range of reduced pressures. All surfaces were examined using a Scanning Electron Microscope (SEM). Data and micrograph comparison revealed that both surface chemistry and surface roughness affect the nucleate boiling characteristics of liquid nitrogen. These effects are separated from each other showing that nucleate boiling is a function of both surface chemistry and topography. Surface roughness …

Structures And Relationships Of Some Perovskite-Type Compounds, Christian Michel

Doctoral Dissertations

"A model for crystallographic transitions in perovskites is proposed. The model consists of regular octahedra sharing corners and topologically able to rotate without distortion around their three-fold axes. This model, with R3̄c symmetry (18e position) can be described in terms of a continuous rotation of angle, w, of octahedra from two ideal symmetry forms: the hexagonal close-packed and the cubic face-centered configurations. A parametric relation is derived between w and the rhombohedral cell angle, α, or the corresponding hexagonal axial ratio c/a . A wide range of atomic structures based on a framework of regular or slightly distorted octahedra sharing …

The Deformation Mechanisms In Sublimed Magnesium Under Cyclic Loading, Babu Narian Thakur

Doctoral Dissertations

"A detailed study of the deformation processes in sublimed magnesium under reverse bending fatigue in air at room temperature has been undertaken utilizing the light, scanning and transmission electron microscopy. The Principal deformation modes are the basal slip and {10Ī2} twinning. The proportion of twinning increases markedly with the increasing stress level and the number of cycles. The evidence for cross slip is seen on the basal slip bands. The extrusions are seen not only along the basal slip lines but also along the {10Ī2} twin boundaries. In the later stages of fatigue, the extrusions chip off producing a notch …

Voids In Neutron Irradiated Aluminum, Nicholas H. Packan

Doctoral Dissertations

"Void formation in high purity aluminum resulting from irradiation to fluences between 1.5 x 10¹⁹ and 1.6 x 10²² neutrons/cm² (E > 0 .1 MeV) at a temperature of 55 ± 5ºC was studied, primarily by means of transmission electron microscopy. In particular the effects of neutron fluence and flux were examined, as well as the possible influences of both preexisting and transmutation-produced impurities. A very low concentration of voids (about 10¹²/cm³) resulted from irradiation to 1.5 x 10¹⁹ neutrons/cm²; they averaged about 150 Å in diameter. Void concentrations and sizes increased with fluence, reaching values of 6 x 10¹⁴ voids/cm³ …

Radiative Lifetime Of The A¹Π State And The Transition Moment Variation Of The Fourth Positive Band System Of Carbon Monoxide, Joseph George Chervenak

Doctoral Dissertations

"The lifetime of the A¹π state of carbon monoxide has been measured using a pulsed invertron excitation source and delayed coincidence measurement technique on the fourth positive system. Eighteen bands, originating from the upper states v' = 0 to 5, were examined at pressures between 500 and 50 microns, with no pressure dependence noted. The data were corrected for photon "pile up" and least-squares fitted to the sum of two exponentials. The transition moment was found to vary and was expanded about the r-centroid of the v' = 0 to v" = 0 transition. Oscillator strengths are calculated and compared …

Development And Application Of Cartesian Tensor Mathematics For Kinematic Analysis Of Spatial Mechanisms, Robert Myrl Crane

Doctoral Dissertations

"The complexity of spatial mechanisms in themselves and the absence of an attractive analytical tool for their study has left this field of engineering analysis largely unexplored. In recent years several analytic methods have emerged. One of the most attractive of these is the tensor method. Literature surveys reveal that the tensor method is largely unexploited in the U.S.A., with regard to spatial mechanisms as well as simpler kinematic problems. The purpose of this work is to develop tensor mathematics for application to the kinematic analysis of spatial mechanisms. Methods are developed for position solutions and the determination of velocities …

The Cathodic Reduction Of Maleic Acid, Show Yih Hsieh

Doctoral Dissertations

"The electrochemical reduction of maleic acid (0.0003 to 0.3 M) was studied on Hg, 0.5% Bi(Hg) amalgam, 5.0% Bi(Hg) amalgam, and Bi cathodes in 1 n H₂SO₄-K₂SO₄-KOH electrolytes (pH 0.3 to 4.0) at 60°C. The maleic acid was converted to succinic acid with high efficiencies (86 to 100%) on all cathodes. Polarization curves with linear Tafel sections were found. All the cathodes had similar kinetic parameters...A reaction mechanism consistent with the experimental observations is proposed..."--Abstract, pages ii-iii.

An Experimental And Theoretical Study Of The Nucleation Of Water Vapor On Ions In Helium And Argon, Daniel R. White

Doctoral Dissertations

"The nucleation of water vapor on ions in atmospheres of helium and argon was studied using an expansion type cloud chamber. Separation of the positive and negative ions was achieved so that the nucleation could be studied as a function of both the sign of the ionic charge and the supersaturation. A semiphenominological theory was developed as an extension of the classical theory to include the effects of the ionic charge on the nucleation process. The theoretical model of the prenucleation embryo was assumed to possess an oriented dipole surface layer with the direction of orientation dependent on the sign …

A Study Of The Anodic Oxidation Of 1, 3-Butadiene On Platinum And Gold Electrodes, Arun Kumar Agrawal

Doctoral Dissertations

"The anodic oxidation of 1,3-butadiene on Pt and Au electrodes was studied at 70°C in solutions of H₂SO₄, K₂SO₄, K₂CO₃, and KOH with pH's ranging from 0.35 to 12.5. Reaction rates (current) were measured as a function of potential, pH, temperature, and butadiene partial pressure. A transition region (apparently a shift in the rate determining step) in case of Pt was observed in the Tafel plots. The coulombic efficiencies of oxidation to CO₂ were 85 percent in 1 N H₂SO₄ on Pt, 93 percent in 1 N KOH on Pt, and 72 percent in 1 N KOH on Au"--Abstract, Page …

Absolute Excitation Cross Sections Of He⁺ In 20-100 Kev He⁺-He Collisions Using Energy-Loss Spectrometry, Donald Roy Schoonover

Doctoral Dissertations

"Application of positive-ion energy-loss spectrometry has been extended to include experimental determination of absolute excitation cross sections of ground state helium ions. Helium ion-atom collisions were studied for impact energies ranging between 20-100 keV, in 10 keV intervals. The data were taken with an apparatus resolution between 0.6-o.8 eV FWHM. Cross sections for transitions from ground state to the second and third principal quantum levels of the ion plotted as a function of impact energy were still rapidly increasing at 100 keV. The cross sections at this energy were 1.64(± 0.28) x 10⁻¹⁸cm² for He⁺(l²s_1/2) -> He⁺(n = …

Investigation Into The Monotonic Magnetostriction And Magnetic Breakdown In Cadmium, James Milo Carter

Doctoral Dissertations

"Observations of the monotonic magnetostriction of cadmium at 4.2 K and in fields of 65 kilogauss have been made. The angular dependence of an extremal point (H_m) in the monotonic magnetostriction is found to follow inverse cosine behavior. The magnitude of H_m (27 kG) for fields parallel to [0001] is in fair agreement with the onset of γ_1/3 from the breakdown of the trifoliate orbit, γ. The range of observation of h_m coincides with the reported range of the trifoliate orbit. A "klink" in the monotonic magnetostriction is demonstrated. The "klink" field, H_k, …

Completeness And Related Topics In A Quasi-Uniform Space, John Warnock Carlson

Doctoral Dissertations

"Completions and a strong completion of a quasi-uniform space are constructed and examined. It is shown that the trivial completion of a T₀ space is T₀ . Examples are given to show that a T₁ space need not have a T₁ strong completion and a T₂ space need not have a T₂ completion. The nontrivial completion constructed is shown to be T₁ if the space is T₁ and the quasi-uniform structure is the Pervin structure. It is shown that a space can be uniformizable and admit a strongly complete quasi-uniform structure and not admit a complete uniform structure. Several counter-examples …

A Quasi-Lattice Model Of Simple Liquids, Jesse Herbert Collins

Doctoral Dissertations

"A cellular model of simple liquids is proposed which eliminates the objectionable feature of long range order found in other cell models. The volume is divided into N identical spherically symmetric cells, each occupied by one molecule. The cell-center density distribution relative to an average given cell center forms a series of Gaussian peaks whose width is proportional to the square root of the distance from the given cell center. The number of cell centers and average radial distance represented by each of the peaks correspond to a face-centered cubic lattice. The molecular pair distribution function is determined for several …

Diffusion And Internal Friction In Sodium-Rubidium Silicate Glasses, Gary L. Mcvay

Doctoral Dissertations

"The internal friction and self diffusion coefficients of sodium and rubidium ions for (1 - X) Na₂O·X Rb₂O·3 SiO₂ glasses have been measured. The diffusion measurements employed radioactive isotopes and a thin sectioning technique and extended from 350 to 500°C. Internal friction measurements were made from -150 to 500°C and at frequencies of 0.05 to 6000 Hz. The maximum height for the mixed alkali internal friction peak occurs at the composition where the sodium and rubidium diffusion coefficients are equal. It is concluded that the mechanism responsible for the mixed alkali peak is a cooperative rearrangement of sodium-rubidium ions and …

Heuristic Algorithms For The Generalized Vehicle Dispatch Problem, Leland Ray Miller

Doctoral Dissertations

"A heuristic algorithm, called the sweep algorithm, is developed for the vehicle dispatch problem with distance and load constraints for each vehicle. A mathematical development and a step procedure for the sweep algorithm is given. Also given are eight problems and their solutions derived by the sweep algorithm. The solutions for this algorithm are compared with solutions from other vehicle dispatch algorithms, and the sweep algorithm is found to give better results for almost every problem. Various modifications are also presented for the sweep algorithm. A mathematical formulation is given for the vehicle dispatch problem with arbitrary cost functions at …

Some Effects Of Oh Groups On Sodium Silicate Glasses, Mokhtar Sayed Maklad

Doctoral Dissertations

"Glasses of various compositions in the Na₂O-SiO₂ system were prepared with different levels of OH concentration. Phase separation kinetics, thermal expansion, radiation induced optical absorption, and internal friction of these glasses were studied. The increase in OH content in these glasses was found to (a) enhance the rate of phase separation; (b) increase thermal expansion above the glass temperature and change the dilatometric softening temperature in a way that depends on microstructure; (c) increase the radiation induced optical absorption bands associated with positive hole centers and decrease those associated with electron trap centers; and, (d) decrease the low temperature alkali …

Theory Of Shallow Donor Impurity Surface States, Vidal Emmanuel Godwin

Doctoral Dissertations

"A variational approach has been used to solve the effective-mass equation, when the impurity ion is located at a depth d from the surface of a semiconductor, where 0 < d < d_b and d_b represents the case when the impurity ion is in the bulk of the semiconductor. The ground state and the excited state having the largest electric dipole coupling to the ground state have been determined. We have plotted the energy dependence on the depth of the impurity ion from the surface of the semiconductor. The energy has also been calculated as a function of the orientation of the …

Temperature Variation In Distribution Of Relaxation Times In Aluminosilicate Glasses, David Wayne Moore

Doctoral Dissertations

"The distribution of relaxation times for the alkali peak in a Li₂ O·A1₂O₃ ·2.0SiO₂ glass and for the mixed alkali peak in a 0.5Li₂O·0.5Na₂O·A1₂O₃·2.OSiO₂ glass was studied using the internal friction technique. A lognormal distribution of relaxation times provided the best agreement with the experimental data. The ß parameter of the lognormal distribution function, which is related to the half-height peak width, varied with temperature, indicating that the distribution of relaxation times is dependent upon the activation energy and the activation entropy of the relaxation mechanism. The major contributor to the distribution of relaxation times is a wide distribution in …

The Electrochemical Oxidation Of 1-Pentyne On Platinum And Gold, Michael Jensen Danielson

Doctoral Dissertations

"The anodic oxidation of 1-pentyne was studied at 70°C on Pt and Au electrodes in solutions of H₂SO₄, K₂SO₄, K₂CO₃, and KOH. Pt was studied in a pH range of 0.35 - 12.7 and Au in a range of 10.9 - 12.7. Reaction rates were measured as a function of potential, pH, temperature, and 1-pentyne partial pressure. The coulombic efficiencies for the oxidation to CO₂ were 77 percent in 1 N H₂SO₄ and 69 percent in 1 N KOH on Pt and 43 percent in 1 N KOH on Au. The kinetic parameters on Pt were [partial derivative]V/[partial derivative]log i …

Thermochemical Hydrogen-Deuterium Isotope Effects, Wayne C. Duer

Doctoral Dissertations

"The heats of solution at 25.0 ± 0. 1°C for each member of hydrogen-deuterium isotopic pairs (chloroform/chloroform-d, acetone/acetone-d₆, methanol/methanol-d₁, ethanol/ethanol-d₁, and water/heavy water) have been determined as a function of molality in a variety of solvents. The heats for most of the systems could be described as a linear function of average molality with an average deviation in fit of less than one per cent. Using these linear equations, heats of solution at infinite dilution were obtained by extrapolation to zero molality. The heats of solution at infinite dilution of the hydrogen containing compounds were subtracted from those of the …

Electrode Reactions In Zinc Electrolysis, Ernest R. Cole

Doctoral Dissertations

"The effects of temperatures from 0°C to 50°C and current densities from 10 asf to 200 asf on the current efficiency in the electrolysis of pure zinc sulfate solutions (65 gpl Zn⁺⁺ - 200 gpl H₂SO₄) were determined. Pure platinum and platinum coated titanium anodes were used with an aluminum cathode. Platinum anodes were not inert at certain combinations of temperature and current density, and platinum acted as a low overvoltage impurity causing resolution of the cathode deposit. Orientation of the zinc deposits was found to vary with temperature and to have a distinct relationship to current efficiency. Preconditioning of …

Extension Of Some Theorems Of Complex Functional Analysis To Linear Spaces Over The Quaternions And Cayley Numbers, James E. Jamison

Doctoral Dissertations

"In this work certain aspects of Functional Analysis are considered in the setting of linear spaces over the division rings of the real Quaternions and the real Cayley algebra. The basic structure of Banach spaces over these division rings and the rings of bounded operators on these spaces is developed. Examples of finite and infinite dimensional spaces over these division rings are given. Questions concerning linear functionals, the Hahn-Banach Theorem and Reflexivity are considered. The Stone-Weierstrass Theorem is proven for functions with values in a real Cayley Dickson algebra of dimension n. The concepts of inner product spaces and Hilbert …

The Oxidation Kinetics Of Liquid Lead And Lead Alloys, Thomas Edward Weyand

Doctoral Dissertations

"Liquid lead and lead-silver alloys were investigated to determine the rates and products of oxidation in pure oxygen at temperatures of 350 to 600°C. The kinetic data were determined using a Cahn electro-balance. Liquid lead was found to follow a cubic rate of oxidation between 350 and 400°C. A parabolic rate was found at temperatures above 400°C. 0.496% silver and 2.258% silver alloys followed a cubic rate of oxidation from 350 to 550°C and tended to approach a parabolic rate of oxidation above this temperature. Silver additions were found to increase the rate of oxidation as compared to the pure …

Higher Space Mode Analysis Of A Large Cylindrical Pulsed H₂O System, Harold David Hollis

Doctoral Dissertations

"By utilizing a geometrically centered pulsed source internal to a large (B²_g) ≈ 0.002) cylindrical H₂O system, the neutron flux was measured as a function of position and time. A least square fit of the data yielded the fundamental and five higher decay constants and amplitudes of the thermal neutron flux. Symmetrical and enhanced neutron densities were obtained as a result of the internal source. Long waiting times were unnecessary and data acquisition was accelerated.

The decay constants were found to be independent of position, pulse width, counting time and rates, method of normalization, or waiting time. …

Synthesis Heuristics For Large Asynchronous Sequential Circuits, Robert Judson Smith

Doctoral Dissertations

"Many well-known synthesis procedures for asynchronous sequential circuits produce minimal or near-minimal results, but are practical only for very small problems. These algorithms become unwieldy when applied to "large" circuits with, for example, three or more input variables and twenty or more internal states. New heuristic procedures are described which permit the synthesis of very large machines. Although the resulting designs are generally not minimal, the heuristics are able to produce near-minimal solutions orders of magnitude more rapidly than the minimal algorithms. A method for specifying sequential circuit behavior is presented. Input-output sequences define submachines or modules. When properly interconnected, …

Model-Referenced Adaptive Control Of Plants With Noise And Inaccessible State Vector, Donald James Schooley

Doctoral Dissertations

"The problems of process noise, measurement noise, and inaccessible process state vector in the model-referenced system of Shackcloth-Butchart-Parks (SBP) are investigated. Since the system no longer possesses a static equilibrium point, the concept of asymptotic stability does not apply. However, by using Liapunov-like ideas, the error between the plant (process plus controller) and the model is shown to enter a region about the origin if certain bounds are known. A possible technique for reducing the size of this region is to feedback a function of the error into the plant's input. Several methods of circumventing the inaccessible state vector problem …

Use Of The Turbulence Kinetic Energy Equation In Prediction Of Nonequilibrium Turbulent Boundary Layers, William Madison Byrne Jr.

Doctoral Dissertations

"A differential method is proposed for the prediction of a broad range of turbulent boundary layers of engineering and scientific interest. A digital computer program is presented which is applicable to boundary layers with positive, negative, and zero pressure gradient in the main-stream direction as well as boundary layers with suction, blowing or zero mass addition at the wall. The turbulence kinetic energy equation is solved simultaneously with the longitudinal momentum and continuity equations to provide an independent means for determining the effective viscosity which makes allowance for "history" effects in the flow. It is shown that the prediction method …

A Fundamental Investigation Of The Gas Phase Polymerization Of Styrene And Vinyl Type Monomers In A Low Power Inductively Coupled 4 Mhz Rf Plasma, L. F. Thompson

Doctoral Dissertations

"A study has been made on the plasma polymerization of styrene and vinyl type monomers in a cold, low power, inductively-coupled RF plasma. All vinyl type monomers yielded an insoluble, crosslinked film which was slightly colored. A kinetic study is reported for styrene. The effects of power level, bleed rate of monomer, pressure and reactor geometry on the rate of polymer formation are reported. A mechanism is postulated for plasma polymerization. It was found that the initiation step was the rate controlling step and that the reaction followed a cationic polymerization scheme. Both crosslinking and discoloration of the polymers occur …

Upper Cretaceous And Lower Cenozoic Foraminifera Of Three Oil Wells In Northwestern Iraq, Farouk Sunallah Al-Omari

Doctoral Dissertations

"Seventy-five samples of well cuttings and cores from the Iraq Petroleum Company Butmah Well No. 9, Ain Zalah Well No. 16 and Ain Zalah Well No. 17, in northwestern Iraq at approximately 36° 37' north latitude and 42° 41' east longitude, have been examined in detail. The lithologic descriptive term "marl" is replaced by calcareous shale or argillaceous limestone, and the term "globigerinal limestone" is not considered applicable. The foraminiferal fauna from the upper part of the Shiranish Formation prove to be of Maestrichtian age. The Mesozoic-Cenozoic boundary is recognized on the basis of "smaller foraminiferal" faunal assemblages; it is …

A Coordinate Oriented Algorithm For The Traveling Salesman Problem, Joseph Sidney Greene

Doctoral Dissertations

"The traveling salesman problem may be stated as follows: "A salesman is required to visit each of n given cities once and only once, starting from any city and returning to the original place of departure. What route should be chosen in order to minimize the total distance traveled?" A new algorithm is developed which gives a good approximation to the solution for a large number of cities using reasonable computer time and which will converge to the exact solution if allowed to continue. This algorithm is a branch and bound technique which utilizes the distance between cities in its …