Digital Commons Network^™

An Application Of Solow's Growth Model: Case Of Sub-Saharan Africa, Maureen Sarahjane Miller

UNLV Retrospective Theses & Dissertations

This study is prompted by the growing concern over the poor economic performance of Sub-Saharan Africa (SSA) relative to the rest of the world over the past decade. The purpose of the study is to examine how a simple and predictable model like Solow's model can explain per capita income in SSA. Our study consists of cross-sectional-cum-time-series regressions using 32 SSA countries. The time span considered is a 26-year period from 1960 to 1985. The model is based on the empirical framework developed by Mankiw et al. (1992). Our results show that saving has a significantly positive impact on per …

On Line Tracking Of Moving Objects From Moving Platforms, Raveen R. K Abhishetty

UNLV Retrospective Theses & Dissertations

It is desired to position the end point of a conveyor belt, which carries material removed by a moving pavement trimmer, above the bed of a moving dump truck. The present report describes the analytical design and practical control of a tracking system for positioning the conveyor. Initial tests were conducted on a Unimation PUMA robot. The original pavement profiler has been modified to allow automatic computer control of both the soil removal and distribution systems. The distribution is performed by a two degrees of freedom moveable boom with a conveyor system. Two methods for non-contact target position detection were …

A Study Of Recognition Coating Response For Quartz Crystal Microbalances, Robert Louis Curiale

UNLV Retrospective Theses & Dissertations

Computerized molecular modeling methods supplemented with chemometric methods may be used to provide information regarding sensitivity, selectivity, and other properties of solid/vapor sorption interactions for chemically coated Quartz Crystal Microbalances (QCMs). When exposed to the individual vapors of a homologous series of carboxylic acid vapors, a QCM coated with varying thicknesses of poly(ethylenimine) (PEI) coating, produces a linear response that is sensitive and selective. The selectivity of the PEI coating toward analytes increases with aliphatic chain length probably due to dispersive interactions. A linear relationship between calculated van der Waals force values and experimental dispersion force values may exist. BET …

Quantization Of Multiresolution Transform Coefficients For High Compression Of Digital Images, Blaine L Hagstrom

UNLV Retrospective Theses & Dissertations

New developments in transformation theory have fueled interest in methods that employ transformation in the computation process. Theory from various disciplines including electrical engineering, physics, mathematics, and computer science have benefited from these advances. The greatest impact in computer science by these methods is in the area of image compression. Digital image compression is currently of high interest in computer science. The growing demand for images in computers has grown faster than the technology and thus solutions are sought. This work deals with the problem of quantization of resultant coefficients of the transforms in compression methods that perform transformation of …

Identification Of Tire Leachate Toxicants And A Risk Assessment Of Water Quality Effects Using Tire Reefs In Canals, S. M. Nelson, G. Mueller, D. C. Hemphill, U.S. Bureau Of Reclamation

Publications (WR)

Cover is an important component of aquatic habitat and fisheries management. Fisheries biologists often try to improve habitats through the addition of natural and artificial material to improve cover diversity and complexity. Habitat-improvement programs range from submerging used Christmas trees to more complex programs using sophisticated artificial habitat modules. Used automobile tires have been employed in the large scale construction of reefs and fish attractors in marine environments and to a lesser extent in freshwater and have been recognized as a durable, inexpensive and long-lasting material which benefits fishery communities.

Recent studies by the U.S. Bureau of Reclamation have quantified …

Spectral Analysis Of The Flow Behavior Of Big Spring, Kings Canyon National Park, California, Linda Urzendowski

UNLV Theses, Dissertations, Professional Papers, and Capstones

Big Spring, the resurgence of a karst aquifer in the Lilburn Cave system (Kings Canyon National Park, California), displays the uncommon phenomena of ebb and flow discharge during periods of high runoff.

Hydrograph analyses indicate that the portion of Lilburn Cave between the Z-Room and Big Spring is primarily a conduit flow aquifer. The power spectra strongly indicate a nonlinear system, with evidence of quasi-linear behavior found on a smaller scale. The transfer and kernel function indicate that no additional significant inputs or outputs to the system exist. The bench-scale model built to simulate the ebb and flow cycles in …

The Geology Of The Tuff Of Bridge Spring: Southern Nevada And Northwestern Arizona, Shirley Ann Morikawa

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Tuff of Bridge Spring (TBS) is a regionally-widespread, andesite to rhyolite (59.50 to 74.91 wt. %) ash-flow tuff of mid-Miocene age (ca. 15.2 Ma) that is exposed in the northern Colorado River extensional corridor of southern Nevada and northwestern Arizona. Determination of the areal distribution, geochronology, lithology, geochemistry, and internal stratigraphy of the TBS is important for its establishment as a reliable stratigraphic reference horizon for tectonic reconstructions of the extensional corridor during the middle Miocene. Based on reoccurring patterns of major and trace element variation, the TBS is divided into constant Cr/variable SiO₂ and variable Cr/variable SiO …

Analysis And Evaluation Of The Workplace Exposure Assessment Workbook Developed By Keith Tait Including Some Recommended Revisions, Lisa Hebberd

UNLV Theses, Dissertations, Professional Papers, and Capstones

Some risk due to the contamination of workplace environments is an inevitable part of human lives. These risks can often be reduced by improving the control of environmental pollution in the workplace. An extremely important challenge for any industry is to develop a mechanism to identify acceptable levels of safety, or "acceptable risk" in the workplace for specific situations, and to assure adequate quality control over measured or calculated exposure concentrations and their possible contributions to adverse health effects.

Observation Of Non-Isotropic Auger Angular Distribution In The C(1s) Shape Resonance Of Co, Oliver Hemmers, Franz Heiser, J. Eiben, R. Wehlitz, U. Becker

Environmental Studies Faculty Publications

Angle-resolved high-resolution C(KVV) Auger spectra of CO were taken in the vicinity of the C(1s) σ^* shape resonance. These spectra show clear evidence for the theoretically predicted anisotropic K-shell Auger emission in molecules. Complementary results from angle-resolved photoion spectroscopy show that the small size of the observed effect is, besides the varying intrinsic anisotropy of the Auger decay, also due to a smaller anisotropy in the primary absorption process than originally predicted but in good agreement with more recent calculations. Contrary to this, satellite Auger transitions show unexpectedly large anisotropies.

Variable Structure End Point Control Of A Flexible Manipulator, Shailaja Chenumalla, Sahjendra N. Singh

Electrical & Computer Engineering Faculty Research

We treat the question of control and stabilization of the elastic multibody system developed in the Phillips Laboratory, Edwards Air Force Base, California. The controlled output is judiciously chosen such that the zero dynamics are stable or almost stable. A variable structure control (VSC) law is derived for the end point trajectory control. Although, the VSC law accomplishes precise end point tracking, elastic modes are excited during the maneuver of the arm. A Linear stabilizer is designed for the final capture of the terminal state.

The Design Of 2-D Linear Phase Frequency Sampling Filters And 2-D Linear Phase Frequency Sampling Filters With Fourfold Symmetry, Peter Stubberud

Electrical & Computer Engineering Faculty Research

In this paper, the two dimensional (2-D) frequency sampling filter system function described in reference [1] is further developed for frequency sampling filters that have linear phase and frequency sampling filters that have linear phase and fourfold symmetry. The resulting system functions are computationally more efficient for implementing frequency sampling filters with linear phase and frequency sampling filters with linear phase and fourfold symmetry than the system function described in reference [1].

Optimization Of The Seating Position In A Human-Powered Vehicle, Y. Lei, Mohamed Trabia, D. Too

Mechanical Engineering Faculty Research

Until recently, most of the human-powered vehicles (HPV) were designed focusing solely on its aerodynamics characteristic. In many of these HPV designs, the rider seating position was arbitrarily chosen without consideration of its effect on the rider's comfort and cycling effectiveness. Also, there is no guarantee that the seating position is related to maximum power output. Too (1991) used an experimental approach to determine that the rider will produce the maximum anaerobic power when the seat tube angle of a bicycle is at 75° whereas Hull and Gonzalez (1990) used an engineering approach to optimize the cycling biomechanics. However several …

Multiplet-Changing Auger Transitions In Valence Double Photoionization, U. Becker, Oliver Hemmers, B. Langer, I. Lee, A. Menzel, R. Wehlitz, M. Ya Amusia

Environmental Studies Faculty Publications

The decay of valence satellite states in neon above the first double-ionization threshold has been studied experimentally and theoretically. Special emphasis was given to differentiate between two decay modes: valence Auger and valence-multiplet Auger decay. It is shown that the latter process is predominant in the low kinetic energy part of the spectrum. The main structures of this low-energy Auger spectrum could be designated by help of calculated transition energies and decay rates.

Theoretical Study Of Interacting Low Dimensional Electron Systems, Jianzhong Zheng

UNLV Retrospective Theses & Dissertations

This thesis addresses the question of a strongly interacting many-body problem: the Hubbard model on one- and two-dimensional lattices. The technique employed is the small-cluster method wherein the full many-body Hamiltonian for finite clusters with periodic boundary conditions (PBC's) is solved exactly. We first apply this technique to an extended one-dimensional chain and a two-dimensional square-lattice Hubbard model. We then construct a two-dimensional overlayer/substrate Hubbard model with first- and second-nearest-neighbor hopping, on-site and nearest-neighbor interactions, and overlayer-site orbital energy. The ground-state properties are investigated and discussed in a many-body picture.

The Status Of Speech Communication In The Clark County High Schools, Rheba C Washington-Lindsey

UNLV Retrospective Theses & Dissertations

The Clark County School District has implemented the communication strand within the high school English curriculum. Its objectives and activities provide instructional guidelines for teacher use within the classroom situation. This study surveyed high school English teachers and found that the majority of teachers did little or nothing to incorporate speech in their curriculum. The principal reasons given were lack of time, lack of materials, and inadequate university preparation. The study also found newer teachers were more receptive to changes that would allow them to include speech in the curriculum than are veteran teachers; Most teachers support speech education but …

Development Of A Gis-Based Routing Model, Xinnong Yang

UNLV Retrospective Theses & Dissertations

Route optimization models deal with multi-criteria or multi-objective optimization problems. The basic objectives of routing problems include transport cost and risk affects. An improved model presented in this thesis addresses a new optimization model, "Range Optimization Model". Although the core of the route optimization tools adopted is still the conventional "Shortest Path Algorithm", the definition of route optimization functions and the means to employ "Shortest Path Algorithm" are different from conventional procedures; Geographic Information Systems (GIS), have been widely used as a spatial database management system and a geographical analysis tool in a variety of fields related to study of …

High-Energy Behavior Of The Double Photoionization Of Helium From 2 To 12 Kev, Jon C. Levin, Ivan A. Sellin, B. M. Johnson, Dennis W. Lindle, R. D. Miller, Y. Azuma, H. G. Berry, D.-H. Lee, N. Berrah

Chemistry and Biochemistry Faculty Research

We report the ratio of double-to-single photoionization of He at several photon energies from 2 to 12 keV. By time-of-Aight methods, we find a ratio consistent with an asymptote at 1.5%±0.2%, essentially reached by h v≈4 keV. Fair agreement is obtained with older shake calculations of Byron and Joachain [Phys. Rev. 164, 1 (1967)], of Aberg [Phys. Rev. A 2, 1726 (1970)], and with recent many-body perturbation theory (MBPT) of Ishihara, Hino, and McGuire [Phys. Rev. A 44, 6980 (1991)]. The result lies below earlier MPBT calculations by Amusia et al. [J. Phys. B 8 …

Influence Of Interdisciplinary Teaming On Teachers In An Urban High School, Amy Gwendolyn Gaskins

UNLV Retrospective Theses & Dissertations

This study explored the influence of interdisciplinary teaming on high school teachers in a southwest urban high school. The influence of interdisciplinary teaming on teachers' feelings of isolation and collegiality was examined. The construction of teachers' knowledge and development of personal meaning for interdisciplinary teaming were also studied; Participants were four team teachers in three subject matter areas. The teaching experience of the teachers ranged from one year to thirty-two years. Two of the teachers had no prior experience teaching on an interdisciplinary team. The other two teachers had one year of experience teaching on an interdisciplinary team; A case …

Multiage Grouping: Interactions Among And Between Students And Teachers, Instructional Strategies, And Influences On Teachers' Constructs As Defined Through An Accelerated Schools Context, Francine Ann Mayfield

UNLV Retrospective Theses & Dissertations

This ethnographic study explored the interactions among and between students and teachers, instructional strategies and academic shifts, and the influence of those instructional strategies and academic shifts on teachers' constructs defined through a multi-age context. This eight month study was conducted in an elementary school organized under the governance structure of Accelerated Schools with all classes grouped in multi-age configurations; Participants selected were primary and intermediate teachers and students within the elementary school who had been at that site for one to three years. Participating teachers were both experienced and novice ranging from two to twenty years of experience. This …

Performance Evaluation Of Distributed Mutual Exclusion Algorithms, Kenneth B Been

UNLV Retrospective Theses & Dissertations

In any system in which concurrent processes share resources, mutual exclusion refers to the problem of guaranteeing the integrity of those resources by restricting their use to one process at a time. Due the complex nature of distributed systems, distributed mutual exclusion algorithms are often not amenable to theoretical analysis for performance or even correctness. Experimental inquiries are therefore warranted. This thesis investigates seven well known distributed mutual exclusion algorithms in detail, and uses computer simulation to evaluate the performance and applicability of these various algorithms. Toward this end, a realistic and general model for evaluating distributed algorithms is proposed. …

A Comparison Of Maximal Oxygen Uptake Achieved From A Horizontal And Inclined Treadmill Test, Cherri Nowotny Epstein

UNLV Retrospective Theses & Dissertations

The purpose of this study was to compare two protocols and the resulting VO2 max obtained. In one protocol grade only was used to impose greater workloads; in the other protocol speed only was used to impose greater workloads. In addition, maximum heart rate, perceived general fatigue, leg fatigue and cardiorespiratory fatigue between the two protocols was compared. Thirty apparently healthy subjects, 15 men and 15 women, between 18 and 35 years of age participated; The statistical treatment showed that there was no significant difference in VO2 max between inclined and horizontal running. There was no significant difference in max …

Self-Stabilizing Deadlock Algorithms In Distributed Systems, Mitchell Elliott Flatebo

UNLV Retrospective Theses & Dissertations

A self-stabilizing system is a network of processors, which, when started from an arbitrary (and possibly illegal) initial state, always returns to a legal state in a finite number of steps. Self-stabilization is an evolving paradigm in fault-tolerant computing. This research will be the first time self-stabilization is used in the areas of deadlock detection and prevention. Traditional deadlock detection algorithms have a process initiate a probe. If that probe travels around the system and is received by the initiator, there is a cycle in the system, and deadlock is detected. In order to prevent deadlocks, algorithms usually rank nodes …

Harmonic Analysis Of Transformer Excitation Currents, Xiaoqiang Gong

UNLV Retrospective Theses & Dissertations

Transformer core nonlinearity has been a subject of research in electrical power engineering for many decades. An accurate and simple transformer model that takes into account its iron saturation appears to be lacKing The objective of this thesis is to propose a voltage-dependent model of transformer core nonlinearity that predicts the exciting current waveforms at various supply voltages. The model is composed of the core loss resistance and magnetizing reactance as seen by the fundamental frequency component and a series of parallel-connected harmonic current phasors. The single-phase transformer model is extended to represent three-phase transformers under various connections, including Y/Y, …

Formal Verification Of Distributed Deadlock Detection Algorithms, Brian Matt Johnston

UNLV Retrospective Theses & Dissertations

The problem of distributed deadlock detection has undergone extensive study. Formal verification of deadlock detection algorithms in distributed systems is an area of research that has largely been ignored. Instead, most proposed distributed deadlock detection algorithms have used informal or intuitive arguments, simulation or just neglect the entire aspect of verification of correctness; As a consequence, many of these algorithms have been shown incorrect. This research will abstract the notion of deadlock in terms of a temporal logic of actions and discuss the invariant and eventuality properties. The contributions of this research are the development of a distributed deadlock detection …

On Strong Reduction In Director String Calculus, Matthew Edward Kinkenon

UNLV Retrospective Theses & Dissertations

An algebra is presented which is used in conjunction with a modified version of director string calculus (MDSC). The algebra simplifies the implementation of the MDSC while preserving the applicative structure of the originalexpression, and capturing strong reduction.

The Use Of Synthesized Images To Evaluate The Performance Of Ocr Devices And Algorithms, Frank Robert Jenkins

UNLV Retrospective Theses & Dissertations

This thesis will attempt to establish if synthesized images can be used to predict the performance of Optical Character Recognition (OCR) algorithms and devices. The value of this research lies in reducing the considerable costs associated with preparing test images for OCR research. The paper reports on a series of experiments in which synthesized images of text files in nine different fonts and sizes are input to eight commercial OCR devices. The method used to create the images is explained and a detailed analysis of the character and word confusion between the output and the true text files is presented. …

Prediction Of Performance Criteria For Passive Heating Ventilation And Air Conditioning Silencers, Mark Olen Bodie

UNLV Retrospective Theses & Dissertations

Unwanted noise is generated by the operation of heating, ventilation, and air conditioning (HVAC) systems in large buildings. The unwanted noise can be reduced by installing a passive silencer in the HVAC system. The ability to predict the performance criteria (insertion loss, regenerated sound power, and pressure drop) associated with a passive silencer is of great importance to the HVAC engineer. The purpose of this thesis is to predict the performance criteria listed above. Empirically derived regression equations are provided which calculate the performance criteria associated with 2ft x 2ft cross sectional area rectangular passive silencers for various internal geometries …

Optimal Scheduling Of Thermal Generating Units In Electric Power Systems, Narsimha Misra

UNLV Retrospective Theses & Dissertations

The Unit Commitment Problem (UCP) in electric power system problem that consists of finding the startup and shutdown schedule of generating units over a period of time (e.g., 24 hrs) so that the operating cost is minimized; The UCP is often characterized by its prohibitive computational time and memory space requirement. The thesis investigates some computational aspects of the problem in an effort to improve the CPU time as well as the quality of the solution. Two algorithms that show significant improvement over existing methods are presented: One is based on the dynamic programming approach and designed for implementation on …

A Genetic Algorithm Applied To The Fractal Inverse Problem, Hiroo Miyamoto

UNLV Retrospective Theses & Dissertations

The theory of iterated function systems (IFS) allows one to construct a fractal which depends on a finite number of parameters. The associated inverse problem, finding a set of parameters which reconstructs a given fractal, is much more difficult. This paper explores the possibility of solving the inverse program with the genetic algorithm.

A Cubic And Bicubic Method For Curve And Surface Estimation, Niki M Anagnostopoulou

UNLV Retrospective Theses & Dissertations

A deterministic cubic and bicubic method for curve and surface estimation is presented. The method presented, does not assume that the surface to be estimated, based on a given set of data in the three dimensional space, has a continuous first or second derivatives. The given data does not have to be equidistant. Also, since the method leads to parametric equations for the patches of the surface, the estimating surface does not need to be a function. Parameters {dollar}h\sb{i,j}{dollar} are used for continuity and stress.