Digital Commons Network^™

Collisional Excitation Of N+ At 50 Kev, D. H. Crandall, G. York, V. Pol, John T. Park

Physics Faculty Research & Creative Works

The excitation spectrum of N+ has been observed by examining the energy lost by a 50- keV N+ beam passing through a He target. The spectrum exhibits dramatic features with large cross sections. Determination of the approximate ratio of metastable to ground-state ions in the primary ion beam has permitted measurement of excitation cross sections from both ground-state and metastable N+ ions colliding with He target atoms. © 1972 The American Physical Society.

An Aircraft, Aerosol Sampling Program: Some Preliminary Results, J. F. Stampfer

Chemistry Faculty Research & Creative Works

An aircraft sampling program to determine the vertical and size distributions of that part of the atmospheric aerosol with radius greater than 0.25 μ is described. The feasibility of using a single engine aircraft and a light scattering particle analyzer, for this work, is shown. Examples of the data are given and preliminary conclusions are drawn about the normal size distribution, effect of lapse rate on the vertical aerosol concentration gradient, effect of relative humidity on the size distribution, and the possibility of producing high concentrations of giant particles aloft. © 1972.

Adsorption Of Rare Gas Atoms On Xenon, Donald E. Hagen

Physics Faculty Research & Creative Works

The problem of adsorption of rare gas atoms on solids is treated for the case of submonolayer films. An energy spectrum calculation method which is suitable for band structure or heat capacity calculations is discussed. It is particularly useful for adsorbate-substrate systems in the region intermediate between "tight binding" and "plane wave" behavior. The method employs a technique introduced by Kohn and Luttinger of using the eigenfunctions corresponding to a particular point in the Brillouin zone as a basis set. The cases of He and Ne adsorbed on Xe are discussed.

Proceedings Of The 2nd International Symposium On Lower-Cost Housing Problems, Oktay Ural

International Symposia on Low Cost Housing Problems

To protect and improve the total human environment is a major concern of all the nations of the world. This is well noted in the recent activities of the United Nations. The provision of decent homes for every family of our world is an integral part of the human environment. It is this belief which generated the initial interest for the planning of the International Symposia on Lower-Cost Housing Problems.

The purpose of the Second International Symposium is many sided: to generate concern on the housing problems around the world as they exist today; to gather people who share mutual …

Thomson's E/M Experiment Revisited, Michael Glascock, Don M. Sparlin

Physics Faculty Research & Creative Works

The objective of this experiment is to familiarize the student with the impulse theorem, electron dynamics, and magnetic field contours. He is challenged to obtain accurate as well as precise measurements with suboptimum apparatus through correct analysis. He also investigates the influence of various systematic errors using model calculations on a small computer. © 1972, American Association of Physics Teachers. All rights reserved.

An Inexpensive Electrical Vacuum Feedthrough, D. R. Kastelein, Richard A. Anderson, Kaare J. Nygaard

Physics Faculty Research & Creative Works

No abstract provided.

A Study Of Phosphorus Adsorption And Desorption Kinetics On Silicon (111) Surfaces, L. E. Davis, L. L. Levenson, J. J. Melles

Physics Faculty Research & Creative Works

Low energy electron diffraction (LEED) and Auger electron spectroscopy (AES) methods were used to characterize the (111) surface of Si wafers before and after the deposition of P2 molecules. Before deposition, the well-known Si(111)-7 LEED pattern was easily obtained by thermal cleaning at 1200 °C. Cleaning was done by electron bombardment in a vacuum chamber with a base pressure of ∼ 10-10 Torr. After cleaning, AES showed that about 10-2 atomic layer of carbon was the only surface contaminant. The sensitivity of our cylindrical AES apparatus for phosphorus was about 10-3 atomic layer. We found that ∼5x10-2 atomic layer of …

A Correction To Classical Homogeneous Nucleation Theory For Polar Molecules Exhibiting An Electric Double Layer At The Liquid Surface, Daniel R. White, James L. Kassner

Physics Faculty Research & Creative Works

An oriented dipole surface layer is added to the classical liquid drop model of nucleation to account for the surface behavior of substances having polar nonsymmetrical molecules. The preliminary treatment of the change in free energy as given by Abraham is modified to include Fletcher's exponential decay of the degree of orientation. An additional correction for the excess binding energy due to the presence of a foreign molecule in the prenucleation cluster is included to account for the inflections observed in the experimental results of Allen and Kassner. The resulting free energy of formation is combined with the kinetic treatment …

Excited-Ion Lifetimes Using Penning-Ionizing Collisions, William F. Parks, Laird D. Schearer

Physics Faculty Research & Creative Works

We show that in the Penning-ionizing collision He(23S1)+X→He(11S0)+(X+)*+e the precession of the Hem spin at its Larmor frequency forces the J polarization of the Penning ion to rotate at the same frequency but shifted in phase. The tangent of the phase shift is proportional to the lifetime of the ionic state and presents a unique method for measuring excited-ion lifetimes. © 1972 The American Physical Society.

Application Of The Weiss Molecular Field Theory To The B‐Site Spinel, W. E. Holland, Harry A. Brown

Physics Faculty Research & Creative Works

A molecular field treatment of the B‐site spinel was used to determine the ordering temperatures and the asymptotic Curie temperature in terms of the exchange integrals. The theory was developed from a 16‐sublattice model and took into account interactions between an atom and its nearest to fourth‐nearest neighbors. Experimental values of the ordering temperatures and the asymptotic Curie temperature were then used to determine the exchange integrals for the systems Hg1−xCdx Cr2 S4, CdCr2S4(1−y)Se4y, and Zn1−xCdxCr2Se4. Copyright © 1972 WILEY‐VCH Verlag GmbH & Co. KGaA

Wind Tunnel Modeling Of The Atmospheric Boundary Layer, Sreemanth Pagadala

Masters Theses

"The importance of simulating atmospheric flows in wind tunnels has been well established. Experiments were conducted in the Modified Aerodynamic Wind Tunnel to determine the suitability of this wind tunnel for simulating atmospheric flows and the degree to which various aspects of modeling could be fulfilled. A temperature profile to simulate the inversion aloft was generated inside the test section, and then an appropriate velocity profile was built in by means of screen mesh arrangements. The turbulence characteristics of the flow were measured. The validity of the temperature, velocity and turbulence fields were examined. It was found that while the …

Effects Of Cold Working Under Pressure On Subsequent Yield, J. G. Hoeg, Robert L. Davis

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A method utilizing high pressure fluid environments is described whereby a three-dimensional subsequent yield surface was determined for 304 stainless steel cylindrical parent specimens of this material were prestrained in axial compression under fluid pressure and then small sub specimens were sectioned from these parent specimens. Finite element techniques were used to optimize the parent specimen size so that a zone of uniform axial stress woidd result during the prestraining. Longitudinal strains in this zone were monitored during the prestraining and the subspecimens were cut from this region in a manner that did not allow the machining to appreciably affect …

A Strain Energy Comparison Of Discrete Modeling For Vibrating Continuous Systems, S. K. Tolani, Richard Dale Rocke

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Lumped parameter models commonly used to describe continuous one-dimensional and Bernoulli-Elder beam vibration problems have been compared on the basis of maximum system, strain energy. The consistent mass matrix approach has been included in the comparison. Standard matrix techniques have been employed to mathematically obtain desired solutions. Closed form solutions and solutions via the models to Ike system strain energy were obtained for all systems in three dynamic states: Free vibrations, constant base acceleration, and half sine base acceleration. Behavior of the strain energy errors, in general, were found to be similar to those of the frequency root errors. © …

Studies On The Mechanism Of Action Of Nerve Growth Factor., D. (Daniel) B. Hier, B. G. Arnason, M. Young

Chemistry Faculty Research & Creative Works

No abstract provided.

The Plasma Polymerization Of Vinyl Monomers. Ii. A Detailed Study Of The Plasma Polymerization Of Styrene, L. F. Thompson, Kenneth G. Mayhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

A study has been made on the plasma polymerization of styrene monomer in a cold, low‐power, inductively coupled RF plasma. Styrene monomer 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 at the time of polymerization …

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 …

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. …

Assumptions In Forrester's Urban Dynamics Model And Their Implications, Daniel L. Babcock

Engineering Management and Systems Engineering Faculty Research & Creative Works

Forrester's Urban Dynamics model is examined in terms of 1) his assumptions about complex dynamic systems, 2) the a priori bias revealed using a "normalized" model, 3) equilibrium changes when the model is modified to fit urban data, and 4) policy predictions of such a modified model. Copyright © 1972 by The Institute of Electrical and Electronics Engineers, Inc.

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.

A Study Of Some Complexometric Titrations In Nonaqueous Solvents, Ngo The Hung

Masters Theses

"Complexometric titrations of calcium, zinc and lead with polyaminocarboxylic acids: ethylenediaminetetraacetic acid (EDTA), 1,2-diaminocyclohexanetetraacetic acid (DCTA), ethyleneglycol-bis(2-aminoethylether)tetraacetic acid (EGTA) and tetraethylenepentamine (tetren) have been investigated and compared in the following organic solvents: methanol, dimethyl formamide, dimethyl sulfoxide and methyl ethyl ketone. Various end point detection methods have been used: direct visual titration with metallochromic indicators and instrumental detection by photometry, potentiometry (mercury electrode and lead ion selective electrode) and amperometry. Calcium, zinc and lead can be determined up to trace levels (ppm) under specific conditions. A concrete application of this thesis is the determination of zinc or calcium in a …

Experimental Studies Of Supporting Wire Disturbances In The Near Viscous Wakes Of Slender Supersonic Bodies, Kenneth Anthony Mirly

Masters Theses

"Wires have often been used as a means of mechanically supporting a model so that its wake will be relatively free of support interference. Such support systems have many advantages over stings and are less costly than magnetic suspension systems. Investigations into the disturbances caused by these supporting wires have been carried out with the use of a two-dimensional flat plate and a wire supported slender cone. The tests were conducted in the University of Missouri-Rolla axisymmetric, supersonic wind tunnel at Mach 3.15, and at a Reynolds number of 2.14 X 10⁶ per inch. Schlieren photography, pitot and static pressure …

Performance Comparison Of Receivers Designed To Combat Intersymbol Interference Due To Specular Multipath, George H. Smith

Masters Theses

"Bit error probabilities for biphase transmission have been computed for a known two-component multipath channel with a variety of suboptimum receivers. Performance curves are presented for each receiver, and the relative performance is summarized. Degradation due to imperfect channel knowledge is calculated, and the feasibility of countering this interference with these specially designed receivers is discussed"--Abstract, page ii.

Computer-Aided Circuit Optimization Including The Adjoint Method Of Calculating Network Sensitivities, John Walter Olson

Masters Theses

"A complete discuss ion of the optimization of a circuit, including modeling and programming difficulties encountered, is presented. A three transistor bandpass filter is used in order to study various methods of optimization. The adjoint method of calculating the network error gradient vector is compared to the perturbation method. The adjoint method proves to have decided advantages over the other method. A generalized computer program is presented to carry out the Fletcher-Powell optimization algorithm with specialized subroutines which include a network equation solver and both methods of finding the gradient vector. The program proved very effective in realizing a desired …

A Study Of Fmfb Demodulator Operation In The Presence Of Radio Frequency Interference And Gaussian Noise, Terry D. Wormington

Masters Theses

"A digital computer model of an FMFB demodulator has been used to study the effects of radio frequency interference on the detection of a sinusoidally modulated carrier. The effectiveness of selecting the feedback factor to suppress the interference for three values of modulation index is investigated. Also, the required IF bandwidth for the minimization of the mean-square error of the loop output between a signal corrupted by interference and the same signal without interference was investigated. More work is required before the effects of Gaussian noise plus interference on loop operation can be ascertained"--Abstract, page ii.

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 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

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 …

Quasi-Pseudometrics Over Tikhonov Semifields And Fixed Point Theorems, Ronald Evans Satterwhite

Doctoral Dissertations

"It has been shown that topological spaces are characterized as quasi-pseudometric spaces over some Tikhonov semifield.

Sufficient conditions are given for a T₁ space to be metrizable over some Tikhonov semifield.

Completely regular (uniform) spaces are characterized as pseudornetric spaces over some Tikhonov semifield.

Certain metric, pseudornetric, quasi-metric, quasipseudometric spaces over a Tikhonov semifield are shown to be respectively metric, pseudometric, quasi-metric, quasipseudometric spaces in the usual sense.

Several results from fixed point theory in the metric space setting are generalized to the setting of completely regular (uniform) Hausdorff spaces."--Abstract, page ii.

Statistical Studies Of Various Time-To-Fail Distributions, James Addison Eastman

Doctoral Dissertations

"Three models are considered that have U-shaped hazard functions, and a fourth model is considered that has a linear hazard function. Several methods for estimating the parameters are given for each of these models. Also, various tests of hypotheses are considered in the case of the model with the linear hazard function. One of the models with a U-shaped hazard function has a location and a scale parameter, and it is proved in general that any other parameters in a distribution of this type are distributed independently of the location and scale parameters.

A new method used to estimate the …

Modal Truncation Of Substructures Used In Vibration Analysis, Suresh Kumar Tolani

Doctoral Dissertations

"The objective of this study is to describe in a unified manner a group of structural dynamics analyses using the substructures technique. An additional effort is to provide a consistent basis for the selection of substructure principal modes as required by this method. Substructure principal mode frequency roots and strain energy are two criteria evaluated for the selection of substructure principal modes. System eigenvalues and system strain energy are investigated for the comparison of results in the principal modes. System strain energy should provide more rational results since it is proportional to the stress times the strain in the system …