Digital Commons Network^™

Radome Depolarization Effects On Monopulse Receiver Tracking Performance, Michael A. Temple

Theses and Dissertations

Boresight Error (BSE), defined as the angular deviation between the true position and the apparent position of a target as indicated by a radar, is an important figure of merit for a tracking radar. A significant contributor to system BSE is the protective radome. This research effort employed a GO technique to investigate the effects of a radome on BSE, expanding previous ray- trace receive techniques to include: (1) a uniquely defined/developed mathematical description for each surface within arbitrary multi-layer tapered radomes, (2) an 'ideal' taper function concept for obtaining optimum BSE prediction performance, (3) a generalized technique for calculating …

Second-Order Flexoelectric Effect In Chiral Nematic Liquid Crystals, D. W. Cronin, Rolfe G. Petschek, Eugene M. Terentjev

Faculty Scholarship

A molecular-statistical model for the second-order flexoelectric effect in chiral nematics is developed, accounting for additional chiral terms in the pair intermolecular potential U(1,2). It is shown by symmetry analysis, that there are four independent chiral terms in the flexoelectric polarization, proportional to the square of director gradients, ℘∼λ∇ n∇n. A molecular-statistical theory is developed for the second-order chiral flexoelectric constants λ. Their values, obtained in the mean-field approximation, depend on molecular dimensions, interaction parameters, and the degree of molecular chirality. Possible experimental situations are discussed where this effect can be observed.

Shastra -- An Architecture For Deveopment Of Collaborative Appplications, Vinod Anupam, Chandrajit L. Bajaj

Department of Computer Science Technical Reports

No abstract provided.

Measurement Of The Microwave Dielectric Constant For Low‐Loss Samples With Finite Thickness Using Open‐Ended Coaxial‐Line Probes, G. Q. Jiang, W. H. Wong, E. Y. Raskovich, W. G. Clark, W. A. Hines, Jeff Sanny

Physics Faculty Works

This work addresses the effect of finite sample thickness on microwave dielectric constant measurements for thin, planar, low-loss samples using the open-ended coaxial-line probe method. Detailed measurements of the dielectric constant were carried out on a wide range of thicknesses of air samples which were backed by infinitely thick teflon and alumina dielectric media. The measurements were made at room temperature for various (50 Ω) coaxial-line dimensions, microwave frequencies 4-8 GHz, and power levels near a fraction of a mW. The results provide strong support for previously published theoretical calculations based on a boundary value problem which uses a spectral …

Laboratory Studies Of Filter Pack Grain-Size Distributions And Hydrophobic Treatments To Enhance The Recovery Of Free-Phase Floating Hydrocarbons, Hugh Garret Heuvelhorst

Masters Theses

Experiments were conducted in laboratory sand tanks to evaluate filter pack design criteria in an effort to improve free-product hydrocarbon recovery from sand aquifers. Filter sands were prepared and installed in the test tanks to examine the relative efficiency of two different grain sizes and two different grain-size distributions to imbibe kerosene from the formation sand and release it to their respective wells. Treatments of different chemical products were applied to other filter sands to create a hydrophobic coating on the grains. The hydrophobic coatings were tested on filter sands of different grain sizes and grain-size distributions and compared to …

Enhanced Retroreflection Of Light From Rough Metal Surfaces, Sivakumar Natarajan

Masters Theses

The optical constants n and k measured by Johnson and Christy (1972) for the noble metals (gold, silver and copper) are used to analyze the relationship between the surface characteristics and the peak height and half-width of the backscattering peak which is observed in the angular distribution of the intensity of diffusely reflected light at a vacuum-metal interface in a direction antiparallel to the original incident beam. Surfaces with surface roughness of heights less than 200 A to 300 A will be considered and a recently developed perturbation treatment will be used in these studies.

The backscattering of light from …

A Non-Human Primate Model For Evaluating A Fenestration Corticotomy Technique, Philip G. M. Khng

Loma Linda University Electronic Theses, Dissertations & Projects

A study model has been designed to evaluate the effectiveness of a new fenestration corticotomy procedure in two non-human primates Macaca fasicularis.

The objective of this study was to evaluate the efficacy of a new conservative corticotomy procedure to facilitate dental translation using fenestrations. This pilot study compared treatment and control quadrants of each individual animal's maxilla and mandible with both having the same retraction appliance and force on the 2nd premolar following extraction of the 1st molars. The null hypothesis stated that there was no significant statistical difference between the new conservative corticotomy procedure (fenestrations) when compared with …

Mixed Culture Biodegradation Of Pentachlorophenol, Hexachlorobenzene, And Tetrachloromethane Under Anaerobic Conditions, Jesse Zahn

Theses

Three chlorinated compounds, namely, Pentachlorophenol(PCP), Hexachlorobenzene (HCB), and Carbon tetrachloride were biodegraded under anaerobic conditions using a (CCl₄)mixed culture obtained from an anaerobic sewage sludge digestor in Linden, NJ.

Three sets of cultures capable of degrading each of the target compounds were established. Primary Enrichment Cultures (PECs) from the anaerobic sludge were exposed to each one of the target compounds. The cultures were able to degrade each target compound as follows: HCB, 0 to 1.2 ppm; PCP from 0 to 3-4 PPM; CCl₄, 0.5 to 15.5 PPM

One culture from each PEC group (CCl₄, …

Implementing A Tool For Designing Portable Parallel Programs, Geetha Chitti

Theses

The Implementation aspects of a novel parallel programming model called Cluster-M is presented in this thesis. This model provides an environment for efficiently designing highly parallel portable software. The two main components of this model are Cluster-M Specifications and Cluster-M Representations. A Cluster-M Specification consists of a number of clustering levels emphasizing computation and communication requirements of a parallel solution to a given problem. A Cluster-M Representation on the other hand, represents a multi-layered partitioning of a system graph corresponding to the topology of the target architecture. A set of basic constructs essential for writing Cluster-M Specifications using PCN are …

Avalanches And The Renormalization Group For Pinned Charge-Density Waves, Alan Middleton, Onuttom Narayan

Physics - All Scholarship

The critical behavior of charge-density waves (CDWs) in the pinned phase is studied for applied fields increasing toward the threshold field, using recently developed renormalization group techniques and simulations of automaton models. Despite the existence of many metastable states in the pinned state of the CDW, the renormalization group treatment can be used successfully to find the divergences in the polarization and the correlation length, and, to first order in an $\epsilon = 4-d$ expansion, the diverging time scale. The automaton models studied are a charge-density wave model and a ``sandpile'' model with periodic boundary conditions; these models are found …

Nanostructural Effects And Interface Magnetism In Co/Pd Multilayers, Ping He, Z.-S. Shan, John A. Woollam, David J. Sellmyer

David Sellmyer Publications

A series of Co/Pd multilayers were made by dc magnetron sputter deposition on Al foil substrates. For these multilayered samples, Co layer thicknesses were less than 4 Å and Pd layers were varied from 4 to 22 Å. Sputtering rates were controlled by either sputtering power (10–50 W) or Ar sputtering pressure (3–15 mTorr). In both cases, lower deposition rates yielded higher perpendicular coercivity up to 2.6 kOe. Structures of the samples were studied using conventional θ -2θ x-ray diffractometry (XRD). It has been found that magnetic properties such as coercivity and saturation magnetization are sensitive to interfacial structures. A …

Magnetization Reversal And Defects In Co/Pt Multilayers, J.X. Shen, Roger D. Kirby, K. Wierman, Z.-S. Shan, David J. Sellmyer, T. Suzuki

Roger Kirby Publications

(Co 3 Å/Pt 10 Å)× N (N=8, 16, and 30 bilayers) multilayer thin films were prepared by sputtering onto an 850-Å-thick SiN layer that had been deposited on a silicon (111) substrate. We used the polar Kerr effect to measure the time dependence of magnetization reversal over the temperature range 90–300 K. Direct domain observations were also carried out. The results show that the domain expansion process depends strongly on the number of bilayers. Uniform domain expansion was found only in the thinner samples. From the time dependence of the magnetization reversal measurements over the temperature range 90–300 …

Photochemistry Of Nitrous Acid And Nitrite Ion, Kathryn E. Shanks '93

Honors Projects

Research is currently underway to elucidate the photochemical decomposition mechanism of nitrous acid and nitrite ion in aqueous and non-aqueous media. The quantum yield of the photochemical disappearance of nitrous acid and nitrite, as a function of pH and nitrous acid/nitrite ion concentration ratios, was examined. Spectroscopic studies have been done with nitrite ion in various aprotic organic solvents. Similar work has been started with molecular nitrous acid that was produced in aqueous solution and then extracted into organic solvents. These organic solvents were employed in order to study the quantum yield with respect to NO2- and HONO without the …

The Interpolating Random Spline Cryptosystem And The Chaotic-Map Public-Key Cryptosystem, Fengi Hwu, Chung You Ho

Computer Science Technical Reports

The feasibility of implementing the interpolating cubic spline function as encryption and decryption transformations is presented. The encryption method can be viewed as computing a transposed polynomial. The main characteristic of the spline cryptosystem is that the domain and range of encryption are defined over real numbers, instead of the traditional integer numbers. Moreover, the spline cryptosystem can be implemented in terms of inexpensive multiplications and additions.

Using spline functions, a series of discontiguous spline segments can execute the modular arithmetic of the RSA system. The similarity of the RSA and spline functions within the integer domain is demonstrated. Furthermore, …

Modification Of The Eikonal Relation For Chemical Waves To Include Fluid Flow, J. W. Wilder, D. A. Vasquez, Boyd F. Edwards

All Physics Faculty Publications

Propagating wave fronts resulting from autocatalytic chemical reactions have been the focus of much recent research. For the most part, the hydrodynamics resulting from such reactions has been neglected. In this work, a relation is derived for the normal speed of a propagating wave front as a function of the local curvature when fluid motion is allowed. This ‘‘eikonal’’ equation is a generalization of one which was derived in the absence of fluid flow. It is also shown that small variations in the fluid density due to the chemical reaction do not change the form of the relation.

The Probe, Issue 132 - May 1993

The Probe: Newsletter of the National Animal Damage Control Association

CONTENTS:
Choosing a Career as a Wildlife Biologist
CALENDAR OF UPCOMING EVENTS
Arizona Legislators Reject Trap Ban
Dogs Decimate Ostriches
River Otters Impact Crawfish Producers
Rats Damage Automotive Wiring
Survey Reveals Animal Activists' Attitudes Toward ADC
USU Needs Help With Wildlife Damage Management Library

Two Dimensional Power Spectral Estimation Using Constrained Iterative Spectral Deconvolution, Jerome Leslie Coggins

LSU New Orleans Theses and Dissertations

Two-dimensional power spectral estimation is an important tool for seismic data analysis and other applications. Some datasets, however, have a limited number of points in one or both dimensions. In seismic applications, there are typically fewer points in the spatial domain as compared to the temporal domain. Conventional spectral estimation techniques suffer from poor resolution on short datasets due to inherent smoothing or bias.

Ramaswamy and loup developed a one-dimensional method for the estimation of power spectra for short datasets. Constrained Iterative Spectral Deconvolution (CISD) greatly improves the power spectral resolution using a straight-forward algorithm. In a comparison to other …

Evidence Of A Nondiffusive Transport In A Monodisperse Screened Coulomb System By A Molecular-Dynamics Simulation, Michael Wild, Ras B. Pandey

Faculty Publications

A molecular-dynamics simulation is carried out for particles (tracers) interacting with a screened Coulomb potential in three dimensions. A phase transition is observed from a liquid to an fcc solid on reducing the temperature at a fixed density, consistent with previous studies. In the liquid phase, the variation of the rms displacement R_tr of the charged particles with time seems to depend on the density and the temperature. In the short-time regime, the effective exponent k for the subdiffusive power-law behavior, i.e., R_tr∼t^k, decreases on increasing the density and lowering the temperature. A crossover from …

Preliminary Public Health Assessment: Petrochem Recycling Corporation/Ekotek Salt Lake City, Salt Lake County, Utah, Agency For Toxic Substances And Disease Registry, Divisoin Of Health Assessment And Consultation

All U.S. Government Documents (Utah Regional Depository)

The Petrochem/EkoTek site was operated by several owners as a refinery from 1953 until 1978 and as a hazardous waste storage treatment facility and a petroleum recycling facility from 1978 through 1988. Removal of essentially all petroleum products and hazardous wastes in tanks and drums was accomplished from 1988 - 1991. The process that will lead to the complete clean-up of the facility is ongoing. The site was added to the National Priorities List (NPL) in October 1992. Exposure of humans to contaminants in soil and air is thought to have occurred near Petrochem. The source(s) of those contaminants in …

Santa Clara Magazine, Volume 35 Number 2, Spring 1993, Santa Clara University

Santa Clara Magazine

9 - HOW SCU ALUMS PUT CLINTON IN THE DRIVER'S SEAT Before there was a President Clinton, there was a long-shot campaign energized by SCU grads. In Ride Around America, White House Press Sec retary Dec Dee Myers '83 details some decisive days on the road to Washington (page 10). Voting the Unthinkable: Why Silicon Valley Got on the Clinton-Gore Bus by Susan Frey describes how Apple's Dave Barram MBA '73 convinced high-tech Republicans to take a chance on Clinton (page 14).

16 - HIV-POSITIVE One of every 250 Americans is infected with the AIDS-causing human immunodeficiency virus. This chilling, …

Millikan Lecture 1992: Hypermedia And The Knowing Of Physics: Standing Upon The Shoulders Of Giants, Robert Fuller

Robert G. Fuller Publications

Hypermedia is defined and its roots briefly discussed. Models of knowing physics and of intrinsically motivating instruction are presented. Uses of hypermedia to increase the knowing of physics and the motivation of learners are proposed.

Impurity Modes In Photonic Band Structures, Yi-Fen Chang

Masters Theses

In this thesis I study a theoretical model of one-dimensional dielectric array (a layered system of dielectric slabs) which forms a periodic dielectric system in which band gaps are opened in the frequency spectrum. Specifically, we study such a one-dimensional array with linear impurities introduced in the periodic dielectric system. In these impurity structures narrow resonant modes are found in the band gaps as impurity modes and these impurity modes change with the dielectric constant. This impurity problem is similar to the donor and acceptor state problem in electronic semiconductors. The calculations presented in this thesis are based on numerically …

Improved Filter-Pack Design For Hydrocarbon Recovery Wells In Unconsolidated Aquifers, Thomas R. Barrett

Masters Theses

Laboratory sand tank experiments and two field studies were conducted to determine filter-pack designs that would increase the hydrocarbon flow rate into hydrocarbon recovery wells. Previous laboratory experiments have shown that using filter-packs of Teflon chips or sands treated with a water repellent spray will increase the rate of hydrocarbon recovery into wells in laboratory bail down test experiments.

The results of the laboratory investigations suggest that using a hydrophobic filter-pack with a median grain-size of 2.5-3.5 greater than that of the aquifer will provide the greatest rate of hydrocarbon recovery.

In two field studies, wells constructed with a hydrophobic …

Electron Microscopy Study Of Magnetosomes In A Cultured Coccoid Magnetotactic Bacterium, Fiona C. Meldrum, Stephen Mann, Brigid R. Heywood, Richard B. Frankel, D. A. Bazyllinski

Physics

Intracellular magnetite (Fe₃O₄) crystals produced by the magnetotactic bacterium MC-1 were analyzed by transmission electron microscopy (TEM). Strain MC-1 represents the first-reported isolation of a coccoid magnetotactic bacterium in axenic culture. The magnetosomes of this bacterium displayed a pseudo-hexagonal prismatic habit, were elongated along the crystallographic direction, and were truncated by {111}, {100} and {110} faces. The presence of {111} truncations represents a modification of the magnetosome morphology previously determined for those in other coccoid bacteria. Study of immature crystals produced by strain MC-1 showed that the crystal morphology was controlled even at early stages of …

Electron Microscopy Study Of Magnetosomes In Two Cultured Vibrioid Magnetotactic Bacteria, Fiona C. Meldrum, Stephen Mann, Brigid R. Heywood, Richard B. Frankel, Dennis A. Bazylinski

Physics

Magnetite (Fe₃0₄) crystals produced by two strains of cultured vibrioid magnetotactic bacteria were studied by high-resolution transmission electron microscopy (HRTEM). Both magnetotactic strains were characterized by single chains of magnetite crystals aligned along the long axes of the cells. The strains, designated as MV-2 and MV-4, produced crystals that differed markedly in size and morphology. Crystals present in MV-4 cells were generally larger than those in MV-2 cells and displayed significantly smaller aspect ratios. Crystallographic analysis of the magnetosomes of MV-2 revealed an elongated hexagonal habit based on a prism of {110} faces capped by {111} …

Development Of A Visual System Interface To Support A Domain-Oriented Application Composition System, Timothy L. Weide

Theses and Dissertations

This research designed and prototyped a visual system interface to generate, display, and modify domain-oriented application specifications. A visual system interface, called the Architect Visual System Interface (AVSI), supplements a text-based environment, called Architect, previously developed by two other students. Using canonical formal specifications of domain objects, Architect rapidly composes these specifications into a software application and executes a prototype of that application as a means to demonstrate its correctness before any programming language specific code is generated. This thesis investigates visual techniques for populating, manipulating, viewing, and composing these software application specifications within the formal object base scheme required …

A Distributed Object-Oriented Database Application Design, Hsin-Feng Edward Wu

Theses and Dissertations

The purpose of this study is to analyze and develop a distributed object-oriented database management system (DOODBMS) application to support parallel software development of the Parallel Algorithms and Applications Group (PAAG) at AFIT. By following the software lifecycle of object-oriented paradigm, this thesis investigation is intended to generate requirements analysis, design, implementation, user interface design and implementation, and integration of the database application with the user interface. ITASCA, an existing DOODBMS platform, has been chosen to prototype the application for its distribution functionalities and object-oriented modeling power. The user interface of the database application is based on X-window OSF/Motif front-end …

Characterization Of Laboratory Generated Turbulence By Optical Phase Measurements, Eric P. Magee

Theses and Dissertations

The resolution achieved by an optical imaging system in the presence of the random effects of the atmosphere is severely degraded from the theoretical diffraction limit. Techniques exist for recovering near diffraction limited performance of an imaging system in the presence of atmospheric turbulence. As opposed to laboratory testing, testing image enhancement techniques in the Earth's atmosphere imposes many limitations. Unfavorable weather conditions could result in the loss of time and money invested in conducting the experiments. With a properly characterized turbulence generator, with statistics that match those of the atmosphere, experimental testing of image enhancement techniques can be conducted …

Calculation Of Acoustic Parameters By A Filter-Correlation Method, Robert C. Courtney, Larry A. Mayer

Affiliate Scholarship

This paper presents the filter correlation method, a technique for extracting consistent and accurate estimates of attenuation parameters from acoustic waveform data. The method minimizes problems associated with short time windows and multipath secondary arrivals. The method comprises two stages: a causal passband filter stage followed by a cross-correlation step. The results of the filter-correlation estimator are compared to those of the spectral difference approach for short time series with and without a secondary multipath arrival. Preliminary analyses of acoustic data collected on cored marine silts and clays show the attenuation properties of these materials cannot be described by a …

Properties Of Photon Density Waves In Multiple-Scattering Media, Bruce J. Tromberg, Lars O. Svaasand, Tsong-Tseh Tsay, Richard C. Haskell

All HMC Faculty Publications and Research

Amplitude-modulated light launched into multiple-scattering media, e.g., tissue, results in the propagation of density waves of diffuse photons. Photon density wave characteristics in turn depend on modulation frequency (ω) and media optical properties. The damped spherical wave solutions to the homogeneous form of the diffusion equation suggest two distinct regimes of behavior: (1) a highfrequency dispersion regime where density wave phase velocity V_p has a ω dependence and (2) a low-frequency domain where V_p is frequency independent. Optical properties are determined for various tissue phantoms by fitting the recorded phase (Φ) and modulation (m) response to …