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Articles 1801 - 1830 of 2036

Full-Text Articles in Physical Sciences and Mathematics

A Generalization Of Cayley Graphs For Finite Fields, Dawn M. Jones Aug 1998

A Generalization Of Cayley Graphs For Finite Fields, Dawn M. Jones

Dissertations

A central question in the area of topological graph theory is to find the genus of a given graph. In particular, the genus parameter has been studied for Cayley graphs. A Cayley graph is a representation of a group and a fixed generating set for that group. A group is said to be planar if there is a generating set which produces a planar Cayley graph. We say that a group is toroidal if there is a generating set that produces a toroidal Cayley graph and if there are no generating sets which produce a planar Cayley graph. Characterizations for …


Units In Integral Group Rings For Direct Products, Richard M. Low Jun 1998

Units In Integral Group Rings For Direct Products, Richard M. Low

Dissertations

Given a finite group G and the ring of integers, one can form the integral group ring ZG . A natural problem to investigate is to find a description of the group of units for this ring ZG. Since the unit problem for integral group rings arises in the contexts of algebraic topology, number theory, and algebra, it is an important question to try to answer. For this reason, it has drawn the attention of researchers from diverse areas of mathematics.

Graham Higman (circa 1940) made substantial contributions to the solution of this problem, in the case where G was …


A Study Of The Knowledge Structure Of Expert, Intermediate, And Novice Subjects In The Domain Of Physics, Jennifer L. Discenna Jun 1998

A Study Of The Knowledge Structure Of Expert, Intermediate, And Novice Subjects In The Domain Of Physics, Jennifer L. Discenna

Dissertations

The objective of this research was to investigate the knowledge structure in physics by describing the knowledge of experts, intermediates, and novices. A review of the literature on expertise, physics knowledge, and conceptual structure provided two competing representations of physics knowledge: one defined as a hierarchy of models arranged from general to specific models, the second defined by theories which link knowledge together.

In order to investigate the two representations described above, a reiterative categorization task was employed. This task resulted in a hierarchical sort with larger piles at the top of the hierarchy and smaller piles at the bottom …


Surface Models Of Finite Geometries, Ramon Manuel Figueroa-Centeno Jun 1998

Surface Models Of Finite Geometries, Ramon Manuel Figueroa-Centeno

Dissertations

The standard non-Euclidean geometries, hyperbolic geometry and elliptical geometry, both arise by negating the parallel postulate of Euclid. Both these geometries share with Euclidean geometries an infinitude of points and lines. But also possible are many finite geometries. Among these are the class of projective geometries PG(m,q) of projective dimension m (m > 2) and the k-configurations. These mathematical objects, although primarily geometric in nature, provide related structures of combinatorial interest: block designs. These have applications in scheduling problems and the design of experiments for statistical analysis. Recently, A. T. White has added a topological flavor to the study …


Perturbed Hamiltonian System Of Two Parameters With Several Turning Points, Myeong Joon Ann Jun 1998

Perturbed Hamiltonian System Of Two Parameters With Several Turning Points, Myeong Joon Ann

Dissertations

No abstract provided.


Electron Emission Following The Interaction Of Slow Highly Charged Ions With Solids, Joseph W. Mcdonald Jun 1998

Electron Emission Following The Interaction Of Slow Highly Charged Ions With Solids, Joseph W. Mcdonald

Dissertations

The interaction of highly-charged ions with surfaces involves many excitation processes of the surface atoms and the bulk material. One such process, the emission of electrons from surfaces due to the potential energy of the incident ions has been studied. The experimental results presented here confirm that the majority of electrons emitted as a result of highly-charged ions interacting with a solid surface have energies of about 20 eV. Auger processes contribute a smaller fraction of the total emitted electrons with increasing Z o f the projectile. This contribution to the total electron emission yield is found to be less …


The Intelligent Browser For Texpros, Chih-Ying Wang May 1998

The Intelligent Browser For Texpros, Chih-Ying Wang

Dissertations

Browsing is a technique, which helps users to formulate their query and retrieve information in the information retrieval system. This technique provides users with capabilities of understanding their information needs and gaining system knowledge during the course of the browsing and thus it eases the users' burden when issuing queries. The basic components of the browser provides an underlying structure which allows users to navigate and a browsing process controller which provides users with the needed assistance during each browsing session.

In this dissertation, a new infrastructure (OP-Net), transformed from the existing object network is proposed. Each object in the …


Knowledge-Based Document Filing For Texpros, Xien Fan May 1998

Knowledge-Based Document Filing For Texpros, Xien Fan

Dissertations

This dissertation presents a knowledge-based document filing system for TEXPROS. The requirements of a. personal document processing system are investigated. In order for the system to be used in various application domains, a flexible, dynamic modeling approach is employed by getting the user involved in document modeling. The office documents are described using a dual-model which consists of a document type hierarchy and a folder organization. The document type hierarchy is used to capture the layout, logical and conceptual structures of documents. The folder organization, which is defined by the user, emulates the real world structure for organizing and storing …


A Paleoclimatic Study Of The Midwestern United States From The Stable Isotope Records In Lake Sediments, Norman Alan Lovan Apr 1998

A Paleoclimatic Study Of The Midwestern United States From The Stable Isotope Records In Lake Sediments, Norman Alan Lovan

Dissertations

No abstract provided.


Groundwater Hydraulics And Slope Stability Analysis: Elements For Prediction Of Shoreline Recession, William W. Montgomery Apr 1998

Groundwater Hydraulics And Slope Stability Analysis: Elements For Prediction Of Shoreline Recession, William W. Montgomery

Dissertations

Studies documenting the roles that geologic materials and groundwater play in Great Lakes bluff recession are rare. This study reports findings concerning relationships between bluff lithology, bluff hydrology, and bluff recession along a 10-mile stretch of eastern Lake Michigan shoreline in heterogeneous Pleistocene deposes. According to a newly-developed, field-tested, GIS-based methodology, bluffs in the study area can be characterized lithologically as sand, clay, or mixed sand/clay, and can be characterized hydrologically as exhibiting either high head or low head.

Geotechnical analysis indicates that Atterberg limits, index properties, consolidation state, and drainage conditions affect the shear strength of bluff materials. Silty …


Biodegradation Of Pah Contaminated Soil And Sludge Using Non-Ionic Surfactants, Seema Narula Jan 1998

Biodegradation Of Pah Contaminated Soil And Sludge Using Non-Ionic Surfactants, Seema Narula

Dissertations

Polycyclic aromatic hydrocarbons (PAHs) are one of the most prevalent environmental pollutants contaminating a large number of industrial and Superfund sites. Low solubility and sorption to solid surfaces limit biodegradation rates of PAHs in the environment. Bioremediation of these compounds have been previously tested with partial success. In the present study, aerobic biodegradation of three PAHs (fluorene, phenanthrene, and pyrene) has been studied in shaker flasks, batch fermenter, and bioslurry reactor, in the presence of non-ionic surfactants. A mixed bacterial culture derived from both a refinery sludge and an activated sludge was used as the seed population in the degradation …


Flag : The Fault-Line Analytic Graph And Fingerprint Classification, Ching-Yu Huang Jan 1998

Flag : The Fault-Line Analytic Graph And Fingerprint Classification, Ching-Yu Huang

Dissertations

Fingerprints can be classified into millions of groups by quantitative measurements of their new representations - Fault-Line Analytic Graphs (FLAG), which describe the relationship between ridge flows and singular points. This new model is highly mathematical, therefore, human interpretation can be reduced to a minimum and the time of identification can be significantly reduced.

There are some well known features on fingerprints such as singular points, cores and deltas, which are global features which characterize the fingerprint pattern class, and minutiae which are the local features which characterize an individual fingerprint image. Singular points are more important than minutiae when …


Effects Of Surfactants And Fenton's Reagents On Extraction And Destruction Of Phenanthrene In Spiked Sand, Ming-Chin Chang Jan 1998

Effects Of Surfactants And Fenton's Reagents On Extraction And Destruction Of Phenanthrene In Spiked Sand, Ming-Chin Chang

Dissertations

In this study, surfactants and Fenton's reagents (Fe(II) and H202) ere proposed to solve contaminated site problems in situ on a lab scale. Phenanthrene is a simple PAHs (polynuclear aromatic hydrocarbons). The phenanthrene spiked ottawa sand simulated contaminated soil. HPLC was used for phenanthrene analysis because it provided excellent separation and no interference. Six surfactants (including nonionic and ionic) were tested. The operating conditions were optimized based on process and economic considerations such as reaction time, mixing speed, concentrations of surfactants and concentrations of Fenton's reagents. Surfactants could effectively dissolve phenanthrene from the spiked sand. In …


Biophysical Studies Of The Spectrin Sequence Motif, Denise M. Lusitani Jan 1998

Biophysical Studies Of The Spectrin Sequence Motif, Denise M. Lusitani

Dissertations

No abstract provided.


Mechanistic Studies Of Cation Photogeneration, Mary Frances Clifton Jan 1998

Mechanistic Studies Of Cation Photogeneration, Mary Frances Clifton

Dissertations

No abstract provided.


Collision Spectroscopy Of Low Energy Capture By Multiply Charged Ions From Atomic Targets, Kadir Akgungor Dec 1997

Collision Spectroscopy Of Low Energy Capture By Multiply Charged Ions From Atomic Targets, Kadir Akgungor

Dissertations

State-selective differential cross sections for single-electron capture processes in very slow collisions of Ar^q+ (q = 4 - 6) ions with Ne, and Ar^6+ ions with He have been studied experimentally at laboratory collision energies between 15 and 100 qeV, and at scattering angles between 0° and 8° by means of translational energy-gain spectroscopy technique. The translational energy spectra show that only a few final states are populated depending on the charge state of the projectile, the projectile laboratory scattering angle, and the collision energy. These measurements also show that the dominant reaction channels are due to capture into excited …


An Integrated Environment For Problem Solving And Program Development, Fadi Pierre Deek Oct 1997

An Integrated Environment For Problem Solving And Program Development, Fadi Pierre Deek

Dissertations

A framework for an integrated problem solving and program development environment that addresses the needs of students learning programming is proposed. Several objectives have been accomplished: defining the tasks required for program development and a literature review to determine the actual difficulties involved in learning those tasks. A comprehensive Study of environments and tools developed to support the learning of problem solving and programming was then performed, covering programming environments, debugging aids, intelligent tutoring systems, and intelligent programming environments. This was followed by a careful analysis and critique of these systems, which uncovered the limitations that have prevented them from …


Modeling Study On The Neopentyl+ O2 Reaction System And Experimental And Modeling Study On Mtbe Pyrolysis And Oxidation, Ru Wei Oct 1997

Modeling Study On The Neopentyl+ O2 Reaction System And Experimental And Modeling Study On Mtbe Pyrolysis And Oxidation, Ru Wei

Dissertations

A modeling study on neopentyl radical + O2 reaction system is conducted in this study. Thermodynamic parameters on all species and important transition states are calculated. A thermochemical kinetic analysis is performed.

Thermodynamic parameters are estimated using group additivity with HBI groups. Transition state energies are evaluated from experimental and theoretical data in the literature, combined with elementary reaction modeling to account for temperature effects. Transition state structures, vibration frequencies and entropies are determined from semi-empirical calculations, MOPAC PM3. Kinetics are analyzed with quantum RRK theory for k(E) coupled with modified strong collision analysis of Gilbert et al for …


Diffusive And Wavelike Phenomena In Thermal Processing Of Materials, John A. Pelesko Oct 1997

Diffusive And Wavelike Phenomena In Thermal Processing Of Materials, John A. Pelesko

Dissertations

Contemporary materials science abounds with novel processing methods. Devices such as lasers, microwave sources, and electron beam guns, provide unprecedented control over the deposition of energy within a material. The modern materials scientist has the ability to deposit energy volumetrically, to precisely control the location of energy deposition within a material, and to deposit energy in extremely short intervals of time. While making possible numerous thermal processing methods, these devices also push the limits of our understanding of the response of materials to energy deposition. In order to optimize and control these processing methods, it becomes necessary to further our …


Systematics Of Stable Isotopes And Radionuclides In Precipitation At Kalamazoo, Michigan, Usa, Madhav V. Machavaram Aug 1997

Systematics Of Stable Isotopes And Radionuclides In Precipitation At Kalamazoo, Michigan, Usa, Madhav V. Machavaram

Dissertations

Precipitation samples were collected at Kalamazoo from June 1992 to March 1995. The samples were analyzed for their 8D and 8lgO values. The 5D - 5I80 relationship is comparable to that of Meteoric Water Line (MWL). The monthly mean isotopic values in precipitation exhibited strong seasonality, being higher in summer and lower in winter months. This behavior is apparently a direct consequence of the temperature effect on isotope fractionation.

The summer precipitation at Kalamazoo is derived predominantly from the water vapor originated in the Gulf of Mexico. A box model calculation showed that a Rayleigh type distillation with Gulf moisture …


Localization And Transport Effects In The Disordered Materials, Vladislav Malyshkin Jun 1997

Localization And Transport Effects In The Disordered Materials, Vladislav Malyshkin

Dissertations

No abstract provided.


A Robust Estimate For An Autoregressive Time Series, Jeffrey Terpstra Jun 1997

A Robust Estimate For An Autoregressive Time Series, Jeffrey Terpstra

Dissertations

A weighted rank-based estimate for estimating the parameter of an auto-regressive time series is considered. When the weights are constant, the estimate is equivalent to using Jaeckel’s estimate and Wilcoxon scores. The estimate can be shown to be asymptotically normal at rate y/n. In a linear regression setting this estimate has the desired properties of a continuous totally bounded influence function and a positive breakdown point. It is shown via examples and Monte Carlo that these properties are preserved in an autoregressive time series setting.


Groundwater-Kalamazoo River Interaction Near The Parchment City Wellfield, Parchment, Michigan, W. Richard Laton Jun 1997

Groundwater-Kalamazoo River Interaction Near The Parchment City Wellfield, Parchment, Michigan, W. Richard Laton

Dissertations

A detailed hydrogeologic study of the Kalamazoo River and its interaction with the groundwater was completed near Parchment, Michigan. The Kalamazoo River between Portage Creek and Allegan Dam is a Federal superfund site due to PCB contamination trapped in its sediments. The City of Parchment pumps all of its drinking water from a glacial aquifer 850 feet from the Kalamazoo River. This study focused on the hydrogeology and groundwater/surface interaction of the area through the use of surface and downhole geophysics, installation of monitoring wells and peizometers, seepage meters and chemical sampling. It was determined that the Kalamazoo River is …


Domination In Digraphs, Lisa Hansen Jun 1997

Domination In Digraphs, Lisa Hansen

Dissertations

No abstract provided.


Bandwidth, Edgesum And Profile Of Graphs, Yung-Ling Lai Jun 1997

Bandwidth, Edgesum And Profile Of Graphs, Yung-Ling Lai

Dissertations

No abstract provided.


Efficient Parallel Processing With Optical Interconnections, Lili Hai May 1997

Efficient Parallel Processing With Optical Interconnections, Lili Hai

Dissertations

With the advances in VLSI technology, it is now possible to build chips which can each contain thousands of processors. The efficiency of such chips in executing parallel algorithms heavily depends on the interconnection topology of the processors. It is not possible to build a fully interconnected network of processors with constant fan-in/fan-out using electrical interconnections. Free space optics is a remedy to this limitation. Qualities exclusive to the optical medium are its ability to be directed for propagation in free space and the property that optical channels can cross in space without any interference. In this thesis, we present …


An Investigation Of The Oxygraphic Response Of Stressed Bovine Blood, Cristin Mckenna May 1997

An Investigation Of The Oxygraphic Response Of Stressed Bovine Blood, Cristin Mckenna

Dissertations

Oxygraphic profiles of stressed bovine blood in a temperature controlled 2 ml reactor vessel provide the basis for an investigation of blood's response to various conditions. This response is broken down into an initial response (within 3 seconds), the response over 1 hour and the response over 24 hours. Fast-assay runs which investigate the initial response display a dose-response relationship when chemically stressed by phenol. Phenol concentrations in the 1,000 ppm range indicate a decrease in dissolved oxygen (DO) and higher phenol concentrations of over 20,000 an increase in DO. In addition to phenol concentration, other factors investigated with respect …


Multi-Wavelength Infrared Imaging Computer Systems And Applications, Jun Li May 1997

Multi-Wavelength Infrared Imaging Computer Systems And Applications, Jun Li

Dissertations

This dissertation presents the development of three computer systems for multi-wavelength thermal imaging.

Two computer systems were developed for the multi-wavelength imaging pyrometers (M-WIPs) that yield non-contact temperature measurements by remotely sensing the surface of objects with unknown wavelength-dependent emissivity. These M-WIP computer systems represent the state-of-art development in remote temperature measurement system based on the multi-wavelength approach. The dissertation research includes M-WIP computer system integration, software development, performance evaluation, and also applications in monitoring and control of temperature distribution of silicon wafers in a rapid thermal process system.

The two M-WIPs are capable of data acquisition, signal processing, system …


High Speed Protocols For Dual Bus And Dual Ring Network Architectures, Yaling Zhou May 1997

High Speed Protocols For Dual Bus And Dual Ring Network Architectures, Yaling Zhou

Dissertations

In this dissertation, two channel access mechanisms providing fair and bandwidth efficient transmission on dual bus and dual ring networks with high bandwidth-latency product are proposed. In addition, two effective priority mechanisms are introduced to meet the throughput and delay requirements of the diverse arrays of applications that future high speed networks must support.

For dual bus architectures, the Buffer Insertion Bandwidth Balancing (BI_BWB) mechanism and the Preemptive priority Bandwidth Balancing (P_BI_BWB) mechanism are proposed. BI_BWB can significantly improve the delay performance of remote stations. It achieves that by providing each station with a shift register into which the station …


Sampling And Analysis Of Trace Level Volatile Organic Compounds From Air Via Membrane Permeation, Naihong Zhu May 1997

Sampling And Analysis Of Trace Level Volatile Organic Compounds From Air Via Membrane Permeation, Naihong Zhu

Dissertations

The objective of this study is to develop air sampling techniques using membrane permeation. Two novel techniques for sampling and analysis of trace level VOCs from air via membrane permeation are presented:

  1. selective concentration of VOCs into a canister using a membrane permeator;
  2. on-line membrane extraction for direct introduction of VOCs from air emissions into a gas chromatograph.

In the membrane permeator-canister sampling system (MPCS), the air sample containing trace level VOCs as well as some interferences such as moisture are passed through the membrane module. Polydimethyl siloxane membrane used in this research is highly permeable to organic compounds, but …