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1998

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Articles 2521 - 2550 of 2574

Full-Text Articles in Physical Sciences and Mathematics

Software Flexibility In A Web Environment, Michael Layng Jan 1998

Software Flexibility In A Web Environment, Michael Layng

Theses : Honours

Flexible software systems are designed to be able to adapt to changes in their environment without the need for programmer intervention. This allows companies and institutions to avoid the cost of hiring a programmer every time a business rule changes or a data structure is modified. The techniques of designing and implementing flexible 3GL software systems have been proven as a means of reducing the high cost of software maintenance caused by the changing of systems requirements. Such systems have been in operation in the European finance sector since the early 1980's. Edith Cowan University is participating in current research …


Good Software Development Processes Lead To Harmonious Project Teams Which In Turn Lead To Effective Project Performance, Rweyunga Kazaura Jan 1998

Good Software Development Processes Lead To Harmonious Project Teams Which In Turn Lead To Effective Project Performance, Rweyunga Kazaura

Theses : Honours

The modem world relies on computers in almost every facet of life. With the explosion of Information Technology, software development has become an important process. However, from the beginning, this process has suffered and continues to suffer from a number of problems. If these problems are not rectified, they can jeopardise projects and lead to project failure. Project failure results in a project being delivered: • without satisfying the functional and non-functional requirements requested by the user or customer • beyond the agreed schedule and/or • over budget. Research indicates that practising good software development processes (SDPs) can override these …


Vector Geometry And Applications To Three-Dimensional Computer Graphics, Rory Morrison Jan 1998

Vector Geometry And Applications To Three-Dimensional Computer Graphics, Rory Morrison

Theses : Honours

The mathematics behind algorithms involved in generating three-dimensional images on a computer has stemmed from the analysis of the processes of sight and vision. These processes have been modeled to provide methods of visualising three-dimensional data sets. The applications of such visualisations are varied. This project will study some of the mathematics that IS used in three-dimensional graphics applications


Asymptotically Tight Bounds For Performing Bmmc Permutations On Parallel Disk Systems, Thomas H. Cormen, Thomas Sundquist, Leonard F. Wisniewski Jan 1998

Asymptotically Tight Bounds For Performing Bmmc Permutations On Parallel Disk Systems, Thomas H. Cormen, Thomas Sundquist, Leonard F. Wisniewski

Dartmouth Scholarship

This paper presents asymptotically equal lower and upper bounds for the number of parallel I/O operations required to perform bit-matrix-multiply/complement (BMMC) permutations on the Parallel Disk Model proposed by Vitter and Shriver. A BMMC permutation maps a source index to a target index by an affine transformation over GF(2), where the source and target indices are treated as bit vectors. The class of BMMC permutations includes many common permutations, such as matrix transposition (when dimensions are powers of 2), bit-reversal permutations, vector-reversal permutations, hypercube permutations, matrix reblocking, Gray-code permutations, and inverse Gray-code permutations. The upper bound improves upon the asymptotic …


A Bayesian Meta-Analysis Using The Gibbs Sampler, Shannon Marie Fair Jan 1998

A Bayesian Meta-Analysis Using The Gibbs Sampler, Shannon Marie Fair

UNF Graduate Theses and Dissertations

A meta-analysis is the combination of results from several similar studies, conducted by different scientists, in order to arrive at a single, overall conclusion. Unlike common experimental procedures, the data used in a meta-analysis happen to be the descriptive statistics from the distinct individual studies.

In this thesis, we will consider two regression studies performed by two scientists. These studies have one common dependent variable, Y, and one or more independent common variables, X. A regression of Y on X with other independent variables is carried out on both studies. We will estimate the regression coefficients of X …


Tectonic Caves Of Solai In The Kenyan Rift Valley, Robert A. Davis Jan 1998

Tectonic Caves Of Solai In The Kenyan Rift Valley, Robert A. Davis

International Journal of Speleology

Tectonic caves at Solai, Kenya, were explored in 1970. These lie in a complex geological area of the Great Rift Valley in columnar-faulted ignimbrite. Fissures are presumed to have been widened by later tectonic activity -e.g. the major earthquake of January, 1928. The caves and exploration are briefly described. Questions of formation, drainage and possibilities of steam reservoirs are discussed.


"Hades" - A Remarkable Cave On Oldoinyo Lengai In The East African Rift Valley, Gordon J. Davies Jan 1998

"Hades" - A Remarkable Cave On Oldoinyo Lengai In The East African Rift Valley, Gordon J. Davies

International Journal of Speleology

Oldoinyo Lengai is the world’s only active carbonatite volcano, situated in northern Tanzania within the Eastern Rift Valley, al 2.751 degrees S, 35.902 degrees E. It forms an isolated symmetrical cone at the southern end of Lake Natron, with a summit elevation of 2,890 m (9,480 ft). Periodic eruptions of ash and lava have been recorded since about 1880, and with increasing precision during this century since 1904. In 1990 a routine expedition to monitor activity levels at the summit led to the discovery of a remarkable cave located in the crater floor, filled with numerous long delicate pale yellow …


The 1981 Eruptive Fissure On Mt. Etna: Considerations On Its Exploration And Genesis, Angelo Leotta, Marco Liuzzo Jan 1998

The 1981 Eruptive Fissure On Mt. Etna: Considerations On Its Exploration And Genesis, Angelo Leotta, Marco Liuzzo

International Journal of Speleology

This paper is targeted to an analysis of features common to various fissure caves on Mt. Etna, Sicily. The Authors report the preliminary results of the exploration carried out in the 1981 eruptive fissure, the technical problems met during the exploration, the flow trends and the different courses of the molten material inside the fissure, the particular morphologies. A genetic model is proposed, different from those characterising the lava tube cave genesis, and links are suggested between the various fissures and the main tectonic stress systems operating on Mt. Etna, as well as the morpho-structural conditions of the volcanic edifice …


Sheet Flow Caves Of Kilauea Caldera, Hawaii County, Hawaii, William R. Halliday Jan 1998

Sheet Flow Caves Of Kilauea Caldera, Hawaii County, Hawaii, William R. Halliday

International Journal of Speleology

Terminal lobes of sheet flows of pahoehoe lava sometimes form three-dimensional nests, initially separated by partitions consisting of accreted "skins” of each lobe. Melting breaks down these partitions, forming a uniform flow unit. In Kilauea Caldera we have found and mapped sizable drained cavities in low-slope sheet flows. Their general pattern includes three-dimensional nests, with partially melted septa evident in some examples. Christmas Cave is the most extensive found to date, with 632 meters surveyed on two levels. It is located at the lower end of an inflated sheet flow tongue which underwent local deflation as a result of drainage …


The Cave Exploration Group Of East Africa And Volcanic Caves In Kenya, Michael Declan Kennedy Jan 1998

The Cave Exploration Group Of East Africa And Volcanic Caves In Kenya, Michael Declan Kennedy

International Journal of Speleology

This paper looks at the history of the Cave Exploration Group of East Africa with special reference to the exploration of volcanic caves. It demonstrates that the group has concentrated on two main areas, the Chyulu HiIls and Mt. Suswa, although other areas have also been studied. The Cave Exploration Group of East Africa has had to cope with various problems. The most important of which are related to the socio-economic conditions of a developing country. These problems have not prevented the group from making a valuable contribution to vulcanospeleology.


Hollow Volcanic Tumulus Caves Of Kilauea Caldera, Hawaii County, Hawaii, William R. Halliday Jan 1998

Hollow Volcanic Tumulus Caves Of Kilauea Caldera, Hawaii County, Hawaii, William R. Halliday

International Journal of Speleology

In addition to lava tube caves with commonly noted features, sizable subcrustal spaces of several types exist on the floor of Kilauea Caldera. Most of these are formed by drainage of partially stabilized volcanic structures enlarged or formed by injection of very fluid lava beneath a plastic crust. Most conspicuous are hollow tumuli, possibly first described by Walker in 1991. Walker mapped and described the outer chamber of Tumulus E-1 Cave. Further exploration has revealed that it has a hyperthermic inner room beneath an adjoining tumulus with no connection evident on the surface. Two lengthy, sinuous hollow tumuli also are …


The Origin Of Tubular Lava Stalactites And Other Related Forms, Kevin Allred, Carlene Allred Jan 1998

The Origin Of Tubular Lava Stalactites And Other Related Forms, Kevin Allred, Carlene Allred

International Journal of Speleology

Tubular lava stalactites are often found in lava tubes. Field observations, sample analysis, and comparative studies indicate that these are segregations extruded during cooling from partially crystallized lava al about 1,070 - 1,000 °C. Retrograde boiling (gas pressure) within the lava provides a mechanism to expel the interstitial liquid. In addition to tubular lava stalactites, a variety of other lava features can also result, such as lava helictites, lava coralloids, barnacle-like stretched lava, runners, runner channels, and some lava blisters and squeeze-ups.


Chemical Deposits In Volcanic Caves Of Argentina, Carlos Benedetto, Paolo Forti, Ermanno Galli, Antonio Rossi Jan 1998

Chemical Deposits In Volcanic Caves Of Argentina, Carlos Benedetto, Paolo Forti, Ermanno Galli, Antonio Rossi

International Journal of Speleology

During the last Conference of the FEALC (Speleological Federation of Latin America and Caribbean Islands) which was held in the town of Malargue, Mendoza, in February 1997, two volcanic caves not far from that town were visited and sampled for cave mineral studies. The first cave (Cueva del Tigre) opens close to the Llancanelo lake, some 40 kms far from Malargue and it is a classical lava tube. Part of the walls and of the fallen lava blocks are covered by white translucent fibres and grains. The second visited cave is a small tectonic cavity opened on a lava bed …


Non-Volatile Dissolved Organic Iodine In Marine Water, Xianhao Cheng Jan 1998

Non-Volatile Dissolved Organic Iodine In Marine Water, Xianhao Cheng

OES Theses and Dissertations

An analytical scheme for the determination of marine DOI has been established. The concentration of DOI is estimated as total iodine (TI) minus total inorganic iodine (TII). The concentration of total iodine is determined as [special characters omitted] after DOI has been oxidized to inorganic iodine quantitatively by intensive UV-irradiation and all the inorganic iodine in the samples had been converted to [special characters omitted] by the addition of NaClO.

Production of DOI in seawater can be via both non-phytoplankton and phytoplankton related processes. In the former, iodide is converted to DOI. In the latter, most likely, iodate is converted …


Error-Correcting Codes Associated With Generalized Hadamard Matrices Over Groups, Iem H. Heng Jan 1998

Error-Correcting Codes Associated With Generalized Hadamard Matrices Over Groups, Iem H. Heng

Mathematics & Statistics Theses & Dissertations

Classical Hadamard matrices are orthogonal matrices whose elements are ±1. It is well-known that error correcting codes having large minimum distance between codewords can be associated with these Hadamard matrices. Indeed, the success of early Mars deep-space probes was strongly dependent upon this communication technology.

The concept of Hadamard matrices with elements drawn from an Abelian group is a natural generalization of the concept. For the case in which the dimension of the matrix is q and the group consists of the p-th roots of unity, these generalized Hadamard matrices are called “Butson Hadamard Matrices BH(p, q)”, …


Lava Caves Of The Republic Of Mauritius, Indian Ocean, Gregory J. Middleton Jan 1998

Lava Caves Of The Republic Of Mauritius, Indian Ocean, Gregory J. Middleton

International Journal of Speleology

In their Underground Atlas, MIDDLETON & WALTHAM (1986) dismissed Mauritius as: “very old volcanic islands with no speleological interest”. Recent investigations indicate this judgement is inaccurate; there are over 50 significant caves, including lava tube caves up to 687 m long (one 665 m long was surveyed as early as 1769) and 35 m wide. Plaine des Roches contains the most extensive system of lava tube caves with underground drainage rising at the seashore. Notable fauna includes an insectivorous bat and a cave swiftlet (Collocalia francica), the nests of which are unfortunately prized for ‘soup”. The caves …


An Alternative Method For Determining Adjusted Function Points As The Basis For Software Cost Estimating, William Alexander Eldred Jan 1998

An Alternative Method For Determining Adjusted Function Points As The Basis For Software Cost Estimating, William Alexander Eldred

Engineering Management & Systems Engineering Theses & Dissertations

As software costs become an increasingly higher percentage of total computer system costs, it becomes increasingly more important for software development managers to have the ability to predict development costs with reasonable accuracy early in the software development cycle. Software development cost estimates are based in large measure on software size. Function points are considered by many to be a de facto industry standard as a size metric. The function points technique, unlike lines-of-code, can be applied early in the software development cycle and is language independent. Critics claim that the function point “value adjustment factor,” which purports to capture …


Influence Of Growth Conditions, Inversion Domains, And Atomic Hydrogen On Growth Of (0001_) Gan By Molecular Beam Epitaxy, Michelle Richards-Babb Jan 1998

Influence Of Growth Conditions, Inversion Domains, And Atomic Hydrogen On Growth Of (0001_) Gan By Molecular Beam Epitaxy, Michelle Richards-Babb

Faculty & Staff Scholarship

Growth of GaN by rf-plasma molecular beam epitaxy leads to different surface morphologiesfor nitrogen-stable growth versus gallium-stable growth. Nitrogen-stable growth produces a granular surface morphology with many samples having a significant density of pyramidal hillocks. In contrast, gallium-stable growth results in a flat surface morphology. The hillocks were directly linked to the presence of inversion domains which originated in the nucleationlayer. Nitrogen-stable growth and growth under atomic hydrogen enhanced the growth rate of inversion domains with respect to the surrounding matrix, while growth under Ga-stable conditions resulted in a more nearly equal growth rate. Evidence is presented suggesting that hydrogen …


Κ-To-1 Darboux-Like Functions, Krzysztof Ciesielski Jan 1998

Κ-To-1 Darboux-Like Functions, Krzysztof Ciesielski

Faculty & Staff Scholarship

We examine the existence of κ-to-1 functions f : R → R in the class of continuous functions, Darboux functions, functions with perfect roads, and functions with the Cantor intermediate value property. In this setting κ denotes a cardinal number (finite or infinite). We also consider different variations on this theme.


A Computational Study Of M-M Multiple Bonding In Ph2mmph2N-, Where M = B Or Al, And N = 0, 1, Or 2, Edward L. Hamilton, Justin G. Pruis, Roger L. Dekock, Karl J. Jalkanen Jan 1998

A Computational Study Of M-M Multiple Bonding In Ph2mmph2N-, Where M = B Or Al, And N = 0, 1, Or 2, Edward L. Hamilton, Justin G. Pruis, Roger L. Dekock, Karl J. Jalkanen

University Faculty Publications and Creative Works

We have completed Hartree-Fock ab initio electronic structure calculations on the series of compounds Ph2MMPh2n, where M = B or Al, and n = 0, 1-, or 2-. The results show that the added one and two electrons upon reduction of the neutral compounds go into the M-M π bond, as expected. The canting of the rings in D2 symmetry is related to the degree of steric repulsion in the compounds. There is no evidence for preferential population of an Al-Al σ* orbital in the dianion of the aluminum compound, and hence we have no ready explanation as to why …


The Petrography Of The Buck Creek Dunite Body, Clay County, Nc: Implications About Its Origin And Emplacement, Trista L. Thornberry Jan 1998

The Petrography Of The Buck Creek Dunite Body, Clay County, Nc: Implications About Its Origin And Emplacement, Trista L. Thornberry

Honors Papers

The Buck Creek dunite body, which is part of the Chunky Gal mafic and ultramafic complex, is well exposed on Corundum Knob in Clay County, North Carolina. These ultramafic rocks are surrounded here by mafic schists and gneisses. Gradational geochemical / mineralogical contacts between the mafic and ultramafic rocks of the this complex imply the same protolith for both rock types. They may have originated as distinct parts of an ophiolitic suite beneath a mid-ocean spreading ridge. The metamorphic history of these ophiolitic rocks suggest further that they were subdued to depths of -18km before being emplaced along fault zones …


A Manifold That Does Not Contain A Compact Core, Gerard A. Venema Jan 1998

A Manifold That Does Not Contain A Compact Core, Gerard A. Venema

University Faculty Publications and Creative Works

A core of a (noncompact) manifold is a submanifold with the property that the inclusion of the submanifold into the manifold is a homotopy equivalence. It is shown by example that a manifold may fail to contain a compact core even though the manifold has the homotopy type of a finite complex.


Effects Of Physical And Chemical Properties Of Bright And Dull Coal Lithotypes On The Formation Of Char Particles, Chad G. Tomforde Jan 1998

Effects Of Physical And Chemical Properties Of Bright And Dull Coal Lithotypes On The Formation Of Char Particles, Chad G. Tomforde

Theses and Dissertations

The Energy and Environmental Research Center is working with EPRI and a consortium of companies in partnership with DOE to determine factors causing sticky ash to blind or bridge hot-gas cleanup filters. In this study, bright and dull lithotypes were separated from bituminous, subbituminous and lignitic coals to determine physical and chemical properties that may lead to the formation of different charforms, and consequently, fine and sticky ash that is problematic in coal-fired combustion systems.

Proximate and ultimate, maceral, and energy dispersive X-ray fluorescence (EDXRF) analyses were used to characterize each lithotype. A bench-scale pressurized fluidized-bed reactor (PFBR) was used …


Determining Capture Zones For Three-Dimensional, Heterogeneous, Anisotropic Aquifers By Monte Carlo Analysis, Jon Paul Jones Jan 1998

Determining Capture Zones For Three-Dimensional, Heterogeneous, Anisotropic Aquifers By Monte Carlo Analysis, Jon Paul Jones

Theses and Dissertations

Most methods of delineating capture zones for pump-and-treat remedial design and wellhead protection assume a two-dimensional, homogeneous aquifer. Aquifers, however, are three-dimensional and heterogeneous, thereby introducing uncertainty in capture zone analysis. This study used a Monte Carlo analysis of three sets of statistical parameters defining aquifer heterogeneity. Each set had a different variance for the mean natural log hydraulic conductivity, which varied among the sets by a factor of four. The ensemble means of the capture zones for each set were estimated from 10 randomly generated fields with 12 layers each which were superimposed on each other for a total …


On C^1 Robust Singular Transitive Sets For Three-Dimensional Flows, Carlos Arnoldo Morales, Maria José Pacífico, Enrique Ramiro Pujals Jan 1998

On C^1 Robust Singular Transitive Sets For Three-Dimensional Flows, Carlos Arnoldo Morales, Maria José Pacífico, Enrique Ramiro Pujals

Publications and Research

Abstract:

The main goal of this paper is to study robust invariant transitive sets containing singularities for C1 flows on three-dimensional compact boundaryless manifolds:they are partially hyperbolic with volume expanding central direction. Moreover, they are either attractors or repellers. Robust here means that this property cannot be destroyed by small C1-perturbations of the flow.

Résumé:

Le but de ce travail est d'étudier des ensembles invariants robustes ayant des singularités pour des flots C1 sur des variétés tridimensionelles : ce sont des ensembles hyperboliques singuliers. << Robuste >> veut dire ici que cette propriété ne peut être détruite par des …


Usability Of Visual Basic For Parallel Programming On Windows Nt, James Scott Barker Jan 1998

Usability Of Visual Basic For Parallel Programming On Windows Nt, James Scott Barker

Dissertations and Theses

Visual Basic is a very popular language. Many hardware engineers have learned Visual Basic because of its simplicity, but have never learned C or C++. Furthermore, people are choosing not to use C or C++ for business software development, but instead are embracing languages such as Visual Basic. Since one of the goals of the parallel programming community has been to encourage more widespread use of parallelism in software, this body of programming talent needs to be addressed. This thesis intends to prove that Visual Basic can be used for parallel programming, that using it is at least as easy …


Specification-Driven Optimization, Sheena Day Jan 1998

Specification-Driven Optimization, Sheena Day

Dissertations and Theses

Traditionally, optimizing transformations have been built into compilers. The end-user has little or no control over guiding any optimizations that may be applied by the compiler. Moreover, the compiler-writer does not have a simple way to direct the optimizations. Thus, many potentially beneficial opportunities for code optimization may be lost. We have built a system that allows the user to participate in guiding source-to-source transformations via the specification of rewrite rules. A clean separation of the rules from the strategy of applying them makes the system easier to use and modify, compared to other integrated systems. This is especially relevant …


The Green Dyadic Formulation For Radiation Problems With Arbitrary Sources Embedded In Stratified Multi-Layer Structures : Application To Molecular Fluorescence Problems, Robert Lyle Hartman Jan 1998

The Green Dyadic Formulation For Radiation Problems With Arbitrary Sources Embedded In Stratified Multi-Layer Structures : Application To Molecular Fluorescence Problems, Robert Lyle Hartman

Dissertations and Theses

The Green Dyadic method for computing fields due to current sources between parallel interfaces of dielectric materials is studied. Computer implementation of the method as presented in a well-known article leads to the conclusion that significant errors are present. Two dissimilar methods of solution lead to corrected formulations which are shown to be equivalent. The same correction is found in the research literature. For confirmation, computations are performed in examples involving an emitting dipole by both the Green dyadic method and Sommerfeld' s Hertz vector method. Finally, the computational examples are used to compute fluorescence decay rates for emitting dipoles …


Paramagnetic Nuclear Magnetic Resonance (Nmr) Studies On The Calcium Binding Site Of [Alpha]-Lactalbumin, Thomas Kurt Ritter Jan 1998

Paramagnetic Nuclear Magnetic Resonance (Nmr) Studies On The Calcium Binding Site Of [Alpha]-Lactalbumin, Thomas Kurt Ritter

Dissertations and Theses

Paramagnetic NMR has drawn interest as a technique for extending the range of systems that can be investigated. The purpose of this study was to determine whether a combination of paramagnetic two-dimensional and relaxation techniques allows for assigning resonances corresponding to residues forming the metal binding site of proteins in which the metal is coordinated exclusively by amino acid side chains and which have been previously inaccessible to assignment.

α-Lactalbumin (LA) is a calcium binding protein with relatively broad NMR signals; this broadness has prevented complete assignment. LA has been the subject of many studies, because it can form a …


Xanthones As Antimalarial Agents : Binding Interactions Between Heme Analogues And Xanthones, Jane Xu Kelly Jan 1998

Xanthones As Antimalarial Agents : Binding Interactions Between Heme Analogues And Xanthones, Jane Xu Kelly

Dissertations and Theses

Human falciparum malaria is caused by Plasmodium falciparum parasite, which digests host hemoglobin within its food vacuole, releasing toxic heme. P. falciparum detoxifies free heme to hemozoin by polymerization. This process is believed to be the target of most successful antimalarial drugs, chloroquine and quinine, which are now losing their effectiveness due to the spread of multi-drug resistant strains. Xanthones were recognized in the laboratory of Dr. M. Riscoe (Portland VA Medical Center) to bind to heme, preventing heme polymerization [Ignatushchenko, M., Winter R., and Riscoe, M. (1997) FEBS Letters 409, 67].

This thesis reports a study of the interactions …