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Articles 2731 - 2760 of 2977
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Approaches To The Synthesis Of Azabullvalene, Thomas Rudolph Steinheimer
Approaches To The Synthesis Of Azabullvalene, Thomas Rudolph Steinheimer
Doctoral Dissertations
"Three approaches to the synthesis of the heretofore unknown azabullvalene, the pi electron equivalent heterocyclic congener of bullvalene itself, are described. Two of the schemes are based upon the assumption that the most convenient method for the introduction of the nitrogen atom is via thermal rearrangement of the appropriate azide.
The first involved the generation of the homobarrelene carbon skeleton and sub sequent decomposition of its azide. This compound arises formally as the product of the Diels-Alder addition of acetylene to the bicyclic valence isomer of tropyl azide (cyclohepta-1, 3, 5- trienyl-7-azide). In order to achieve this goal, Diels-Alder additions …
Linear Stability Of Non-Parallel Flow In The Entrance Region Of Ducts, Francis Chung-Ti Shen
Linear Stability Of Non-Parallel Flow In The Entrance Region Of Ducts, Francis Chung-Ti Shen
Doctoral Dissertations
"An investigation is made of the linear stability of the developing flow of an incompressible fluid in the entrance region of annular ducts, circular tubes, and parallel-plate channels. Small axisymmetric disturbances for annular duct and tube flows and small two-dimensional disturbances for channel flow are considered in the analysis. In formulating the stability problems, account is taken of the transverse velocity component of the mainflow. This results in the modified Orr-Sommerfeld equations, one for annular duct and tube flows and the other for channel flow. The mainflow velocity fields utilized in the stability analysis are those from the solutions of …
Rock Fragmentation By Subsurface Thermal Inclusions - A Finite Element Study, Mahendrakumar Ramkrishna Patel
Rock Fragmentation By Subsurface Thermal Inclusions - A Finite Element Study, Mahendrakumar Ramkrishna Patel
Doctoral Dissertations
"Although rock tunneling machines are being used extensively with performance and cost advantages over traditional drill and blast methods, their usefulness for hard rock excavation is far from being practical due mainly to the inability of present day mechanical cutters to penetrate these rocks economically. Among various novel techniques that are being investigated, internal heating methods seem to be the most promising. This investigation is concerned with a feasibility study of thermal rock fragmentation using heat to create in-depth thermal inclusions.
The three-dimensional problem of in situ rock fragmentation involves parallel rows of equidistant holes drilled to a constant depth. …
A Study Of The Dynamic Loading Of Hydrodynamically Lubricated Journal Bearings, Nader Khorzad
A Study Of The Dynamic Loading Of Hydrodynamically Lubricated Journal Bearings, Nader Khorzad
Doctoral Dissertations
"The analytical and experimental investigation presented here examined the response of a full journal bearing to a unidirectional dynamic load. Frequency response of the bearing at different eccentricity ratios was investigated. It was concluded that the response of the bearing varies with eccentricity. The experimental data obtained was compared to an analytical model which considered inertial, damping, and elastic characteristics of the lubricant film. An investigation of film pressure revealed that the pressure due to journal center acceleration is smaller than the hydrodynamic and squeeze-film pressures"--Abstract, page 1.
Auger Satellites Of The L₂₃ Auger Emission Bands Of Al, Si, And P, John Junior Melles
Auger Satellites Of The L₂₃ Auger Emission Bands Of Al, Si, And P, John Junior Melles
Doctoral Dissertations
"In this study a detailed investigation of the high energy satellites of the L23 Auger emission bands of Al, Si, and P was made. The satellites are interpreted as arising from double ionization of the L23 shell rather than from a plasmon gain process. The parent-satellite energy separations, ΔE, between like structures were determined and were found to be consistently smaller than the volume plasmon energies measured for the same samples. A comparison of Si and SiO revealed no evidence that ΔE for Si is dependent on the volume plasmon energy of the sample.
The satellite threshold excitation …
Numerical Simulation Of Heat, Mass, And Momentum Transfer In An Atmospheric Boundary Layer, Darrell W. Pepper
Numerical Simulation Of Heat, Mass, And Momentum Transfer In An Atmospheric Boundary Layer, Darrell W. Pepper
Doctoral Dissertations
"Considerable interest has developed in recent years to understand transport phenomena in thermally stratified boundary layers. More complete knowledge in this field is needed to improve the prediction of the diffusion of air pollutants in the lower atmosphere as well as in forecasting air-water circulation for weather conditions.
The atmospheric boundary layer is modeled using the equations of continuity, momentum, energy, and concentration. Closure of this set of partial differential equations is hindered by the turbulence terms. Using turbulence kinetic energy, the system of equations is closed by internally determining the exchange coefficients of heat, mass, and momentum along with …
Tchebycheff Approximation On A Discrete Point Set: Algorithms Old And New, William Edward Mcbride
Tchebycheff Approximation On A Discrete Point Set: Algorithms Old And New, William Edward Mcbride
Doctoral Dissertations
"Several linear and nonlinear algorithms for solving the discrete Tchebycheff problem are compared in this study. The Lawson algorithm is compared with two more well-known methods of linear Tchebycheff approximation. A new acceleration scheme for the Lawson algorithm is introduced and its performance is tested with an already existing acceleration technique. The new version is found to be better than the previous one but not as effective as the traditional Exchange method.
A nonlinear version of Lawson's algorithm is proposed for the solution of problems having approximating functions which are varisolvent. Some linear theorems of Lawson are extended to the …
Paleozoic Stratigraphy As An Ore Control Of Hydrothermal, Base-Metal, Sulfide Deposits In New Mexico, John Samuel Sullivan Jr.
Paleozoic Stratigraphy As An Ore Control Of Hydrothermal, Base-Metal, Sulfide Deposits In New Mexico, John Samuel Sullivan Jr.
Doctoral Dissertations
"Until now the concept or regional stratigraphic control of hydrothermal ore deposits has not received much attention in the literature as a possible exploration guide for locating additional ore bodies. This concept is applied on a regional scale to Paleozoic strata in thirteen mining districts with hydrothermal base-metal deposits in a 35,300 square mile area or southwest New Mexico.
The rocks at the stratigraphic position of the ore-zones are characterized as massive- to thick-bedded with less than 5 percent chert present. The rocks are abundantly to moderately fractured. Fine- to medium-grained dolomite is the dominant host-rock in the lower Paleozoic …
A Study Of The Pulse-Height Response Of Silicon Surface-Barrier Detectors To High-Energy Heavy Ions, Gregory Dan Smith
A Study Of The Pulse-Height Response Of Silicon Surface-Barrier Detectors To High-Energy Heavy Ions, Gregory Dan Smith
Doctoral Dissertations
"The pulse-height defect (PHD) of high-energy heavy ions in silicon surface-barrier detectors can be divided into three components: (1) energy loss in the gold-surface layer, (2) a nuclear-stopping defect, and (3) a defect due to recombination of electron-hole pairs in the plasma created by the heavy ion. The plasma recombination portion of the PHD was the subject of this study using the variation of the PHD with (1) the angle of incidence of incoming heavy ions, and (2) changes in the detector bias. The Tandem Van de Graaff accelerator at Argonne National Laboratory was used to produce scattered beam ions …
Dynamic Instability And Ultimate Capacity Of Inelastic Systems Parametrically Excited By Earthquakes, Wu-Hsiung Tseng
Dynamic Instability And Ultimate Capacity Of Inelastic Systems Parametrically Excited By Earthquakes, Wu-Hsiung Tseng
Doctoral Dissertations
"A procedure of analysis is presented for determining the dynamic instability and response of framed structures subjected to pulsating axial loads, time-dependent lateral forces, or foundation movements. Included in the analytical work are the instability criterion of a structural system, the finite element technique of structural matrix formulation, and the computer solution methods.
The dynamic instability is defined by a region in relation to transverse natural frequency, longitudinal forcing frequency and the magnitude of axial dynamic force. The axial pulsating load is expressed in terms of static buckling load for ensuring that the applied load is not greater than the …
Petrography, Chemical Composition, And Stratigraphic Setting Of The Coals Of North-Central Missouri, William Keith Wedge
Petrography, Chemical Composition, And Stratigraphic Setting Of The Coals Of North-Central Missouri, William Keith Wedge
Doctoral Dissertations
"Under a grant from the National Air Pollution Control Administration, the Missouri Geological Survey undertook a core drilling program to learn more about the coals in north-central Missouri. The stratigraphic setting and chemical and petrographic characteristics of 43 complete samples of coal recovered from 13 diamond drill holes in the exploration program in north-central Missouri are major contributions of this study. These samples represent twelve different coal beds of the Atokan and Desmoinesian Series of the Pennsylvanian System of Missouri and range in thickness from 9.6 to 44.4 inches. They have an average thickness of 20.4 inches and a combined …
Prebainitic Phenomena In Aisi 86b80 And 0.8c-5.3ni Steels, Chung Lim
Prebainitic Phenomena In Aisi 86b80 And 0.8c-5.3ni Steels, Chung Lim
Doctoral Dissertations
"An ultrasonic investigation shows that the prebainitic kinetics of AISI 86B80 and 0.8C-5.3Ni steels follow t2/3 and or t1 time laws in the lower bainite temperature region. The data analysis indicates that these kinetics signal carbon segregation to dislocations. The simple time laws are interrupted at the bainite start time. It is shown that at this time the carbon depleted regions around dislocations transform martensitically. The lower bainite reaction is thus initiated by the formation of supersaturated ferrite through carbon segregation and the subsequent local martensitic transformation"--Abstract, page iii.
Nucleate Boiling From Polymer Coated Surfaces., David Franklin Warner
Nucleate Boiling From Polymer Coated Surfaces., David Franklin Warner
Doctoral Dissertations
"This study consisted of an examination of both the effects of nucleate boiling on polymer coated surfaces and the effects of the polymer coated surfaces on the nucleate boiling curve. The nucleate boiling curve (the curve resulting from plotting heat transferred per unit area versus the temperature difference between the boiling surface and the liquid pool) of the polymer coated surfaces were compared with the nucleate boiling curve of gold-plated surfaces with no polymer coat and it was found that the thicker the polymer coat, the more the curve deviated from that of the metal uncoated surfaces.
All surfaces were …
On Redei Subgroups Containing Their Centralizers, Robert Edward Mcdonald
On Redei Subgroups Containing Their Centralizers, Robert Edward Mcdonald
Doctoral Dissertations
No abstract provided.
Electromagnetic Cavity Resonances In Rotating Systems, Barbaros Celikkol
Electromagnetic Cavity Resonances In Rotating Systems, Barbaros Celikkol
Doctoral Dissertations
No abstract provided.
Triangular Block Matrix Rings, Paul Livingston Estes
Triangular Block Matrix Rings, Paul Livingston Estes
Doctoral Dissertations
No abstract provided.
Composition Operators, Raj Kishor Singh
A Normal Coordinate Analysis Of Several Acetyl And Trifluoroacetyl Halides, Alan Dennis Cormier
A Normal Coordinate Analysis Of Several Acetyl And Trifluoroacetyl Halides, Alan Dennis Cormier
Doctoral Dissertations
No abstract provided.
An Acceleration Technique For A Conjugate Direction Algorithm For Nonlinear Regression, Larry Wilmer Cornwell
An Acceleration Technique For A Conjugate Direction Algorithm For Nonlinear Regression, Larry Wilmer Cornwell
Doctoral Dissertations
"A linear acceleration technique, LAT, is developed which is applied to three conjugate direction algorithms: (1) Fletcher-Reeves algorithm, (2) Davidon-Fletcher-Powell algorithm and (3) Grey's Orthonormal Optimization Procedure (GOOP). Eight problems are solved by the three algorithms mentioned above and the Levenberg-Marquardt algorithm. The addition of the LAT algorithm improves the rate of convergence for the GOOP algorithm in all problems attempted and for some problems using the Fletcher-Reeves algorithm and the Davidon-Fletcher-Powell algorithm. Using the number of operations to perform function and derivative evaluations, the algorithms mentioned above are compared. Although the GOOP algorithm is relatively unknown outside of the …
Grain Boundary Diffusion In Ionic Crystals, Kulwant Singh Sabharwal
Grain Boundary Diffusion In Ionic Crystals, Kulwant Singh Sabharwal
Doctoral Dissertations
"The diffusion of ¹³¹I in single crystals and along the tilt grain boundaries of pure and calcium chloride doped (142±5 ppm) bicrystals of sodium chloride, grown by Czochralski technique, was investigated using a microtome sectioning technique. Results on bulk diffusion in pure NaCl agree well with the results of earlier investigators and are represented by the D=(504 cm²/sec)exp (-2.27 ev/kT). Enhanced diffusion of ¹³¹I is observed along the grain boundaries and the presence of the dopant lowers the grain boundary diffusivity over the entire temperature range of 430ºC - 570ºC studied in the present investigation. Thermal activation and electrical polarization …
An Exact Analysis Of Two-Dimensional Radiative Transfer In An Absorbing And Emitting Gray Medium, William F. Breig
An Exact Analysis Of Two-Dimensional Radiative Transfer In An Absorbing And Emitting Gray Medium, William F. Breig
Doctoral Dissertations
"The exact formulations for the radiative flux and the emissive power are presented for a two-dimensional, finite, planar, absorbing and emitting, gray medium in radiative equilibrium. Exact expressions are obtained for the medium subjected to the following types of boundary conditions: (1) cosine varying diffuse, (2) cosine varying collimated, (3) constant temperature strip, and (4) the strip illuminated by a uniform collimated flux. The solutions for the physically unrealistic cosine varying models are used to construct the solutions for the more practical finite strip models. The two-dimensional equations are reduced to one-dimensional equations by the method of separation of variables. …
The Utilization Of High Sensitivity Noble Gas Mass Spectrometry In The Detection Of Iodine-129 And Plutonium-244, Mervet S. Boulos
The Utilization Of High Sensitivity Noble Gas Mass Spectrometry In The Detection Of Iodine-129 And Plutonium-244, Mervet S. Boulos
Doctoral Dissertations
"Mass spectrometric analysis of the xenon isotopes in natural gas wells demonstrates that radioactive isotopes of element number 53 (I) and element number 94 (Pu) were present at the time of the Earth's formation. Evidence for the now extinct nuclide129I (t1/2 = 17 x 106 years) was found in CO₂ -rich gas while evidence for the now extinct 244Pu (t1/2 = 82 x 106 years) was discovered in other natural gas wells. The amounts of 129I in thyroids was measured by combining neutron activation analysis with noble gas mass spectrometry. The current …
Geochemical Anomalies In The Igneous Wall Rock At Mayflower Mine, Park City District, Utah, Zuhair Al-Shaieb
Geochemical Anomalies In The Igneous Wall Rock At Mayflower Mine, Park City District, Utah, Zuhair Al-Shaieb
Doctoral Dissertations
"Approximately 500 samples were collected from the igneous wall rock of the Mayflower Mine, Park City District, Utah. The mine is the sixth largest gold producer in the United States. The samples were analyzed for copper lead, zinc silver, manganese, sodium, potassium, calcium, magnesium and iron by atomic absorption spectrophotometry. Gold was determined by neutron activation analysis, silicon and sulfur by x-ray fluorescence spectrometery. The calculation of the mineral norm from the chemical analysis showed the wall rock to be of granodioritic composition. A study of selected vein samples indicates that the copper, silver and gold content in the veins …
Ionization Mechanisms In Cesium, Yu Bong Hahn
Ionization Mechanisms In Cesium, Yu Bong Hahn
Doctoral Dissertations
"Autoionizing states in Cs between 12 and 20 eV have been studied by electron impact. The retarding-potential-difference(RPD) method was used to obtain an electron beam with energy spread of about 0.1 eV. To determine the threshold energies, inelastically scattered electrons were analyzed by the trapped-electron method. We have been able to identify about 20 levels, and the agreement with spectroscopic data is excellent. A peak appearing at 12.80 eV is probably due to the quartet states observed by Feldman and Novick"--Abstract, page 2. "The structure in the electron impact ionization cross section in cesium can be partially accounted for by …
Time Resolved Measurements Of Droplet Growth In A Wilson Cloud Chamber, Michael Anthony Vietti
Time Resolved Measurements Of Droplet Growth In A Wilson Cloud Chamber, Michael Anthony Vietti
Doctoral Dissertations
"The growth rates of water drops in a Wilson expansion cloud chamber are measured with air, argon and helium as the carrier gas, in the size range of .5 to 10 microns. The drops growing in the supersaturated chamber exhibit oscillations in the scattered intensity as predicted by Mie theory. Scattered intensity is measured at 30 degrees to the He-Ne laser beam. Supersaturation ratios during growth range from S =1.2 to S = 3.5 for all three gases. The initial temperature is measured and the pressure is monitored continuously so that droplet growth theory can be compared with experiment. Three …
Mathematical Modeling Of River Water Temperatures, Leland Lovell Long
Mathematical Modeling Of River Water Temperatures, Leland Lovell Long
Doctoral Dissertations
"The applicability of power spectral density techniques, Fourier series analysis, and linear regression to the mathematical modeling of river water temperature is demonstrated. Consideration is also given to the problem of estimating thermal inputs to rivers from man-made sources such as electrical power plants. First, power spectral density techniques are used in the time-series analysis of water temperature records which were taken from the Missouri River. Two spectral ranges are then studied from the standpoint of their applicability to (1) mathematical model building and (2) detection and identification of cyclic thermal inputs. Next, a Fourier regression fit to the time-series …
Structure Of Zero Divisors, And Other Algebraic Structures, In Higher Dimensional Real Cayley-Dickson Algebras, Harmon Caril Brown
Structure Of Zero Divisors, And Other Algebraic Structures, In Higher Dimensional Real Cayley-Dickson Algebras, Harmon Caril Brown
Doctoral Dissertations
"Real Cayley-Dickson algebras are a class of 2ⁿ-dimensional real algebras containing the real numbers, complex numbers, quaternions, and the octonions (Cayley numbers) as special cases. Each real Cayley-Dickson algebra of dimension greater than eight (a higher dimensional real Cayley-Dickson algebra) is a real normed algebra containing a multiplicative identity and an inverse for each nonzero element. In addition, each element a in the algebra has defined for it a conjugate element ā analogous to the conjugate in the complex numbers. These algebras are not alternative, but are flexible and satisfy the noncommutative Jordan identity. Each element in these algebras can …
The Eikonal Distorted Wave Born Approximation For The Excitation Of Hydrogen By Impact With Hydrogen And Helium In The Intermediate Energy Range, Richard Homer Shields
The Eikonal Distorted Wave Born Approximation For The Excitation Of Hydrogen By Impact With Hydrogen And Helium In The Intermediate Energy Range, Richard Homer Shields
Doctoral Dissertations
"An eikonal approximation is applied to atom-atom scattering in the intermediate energy range. The theory and the form of the eikonal approximation are reviewed. Also a brief survey of previous theoretical methods for all energy ranges is included.
In particular, the differential and total cross sections for the excitation of hydrogen to the 2s and 2p states by impact on hydrogen and helium atoms have been calculated using the eikonal distorted wave Born approximation (DWBA) for the incident energy range of 2.25-100 keV. The eikonal DWBA differential cross sections are compared to the differential cross sections given by the first …
Deformation And Fracture Of Concrete Under Uniaxial Impact Loading, Esteban Eulogio Miranda
Deformation And Fracture Of Concrete Under Uniaxial Impact Loading, Esteban Eulogio Miranda
Doctoral Dissertations
"Stress wave propagation and interaction in plain concrete leading up to spall fracture was investigated experimentally with a computer numerical analysis of the bar-geometry axial-impact loading. The critical normal fracture strain energy U and mechanical energy W criteria are proposed for the spatial and time dependence explanation of spallation in concrete. The energy criteria are special cases of a more generalized cumulative damage model of the form:....
Finite-difference analyses of the wave propagation and interactions in the split Hopkinson bar showed that early failure in brittle materials limits the application of the conventional method of analysis because equilibrium in the …
The Application Of Impact Dampers To Continuous Systems, Ranjit Kumar Roy
The Application Of Impact Dampers To Continuous Systems, Ranjit Kumar Roy
Doctoral Dissertations
"A study has been made of the application of impact dampers to two types of continuous systems, a simply supported and a clamped beam. Previous efforts have included the effect of impact dampers on single degree of freedom and other systems with finite numbers of degrees of freedom.
Experimental models were tested in the laboratory and finite element computer programs were developed to calculate response. Results from calculations agree favorably with experimental tests. Further, results from the first few natural modes also compare reasonably with data published on systems with finite number of degrees of freedom.
Curves are presented which …