Physical Sciences and Mathematics Commons^™

A Case Study In Software Reuse: The Rntds Architecture, Barry J. Stevens

Computer Science Theses & Dissertations

It has been asserted that the most significant gains in software productivity will come from increased levels of software reuse. Some economic models for predicting savings through software reuse exist, but none are based on actual project experience. This paper surveys those models and presents the results of a case study, the Restructured Naval Tactical Data Systems (RNTDS) architecture, in the light of those models. According to the models, software reuse via the RNTDS architecture has enabled the production of fourteen major computer programs at five to twenty-one percent of the cost to create them without software reuse. Organizational characteristics …

Study Of The Heavy Fermion/Spin-Glass System, Ce1-X GdX Al3, Using 155Gd Mossbauer Spectroscopy, Nicholas G. Ruggiero

Physics Theses & Dissertations

The magnetic properties of Ce_1-xGd_x.Al₃ have been studied using ¹⁵⁵Gd Mossbauer spectroscopy. It has been shown that the magnetic moments of the host GdAl₃ are constrained to the basal plane. The magnetic properties of GdAl₃ can best be described in the framework of RKKY theory. Prior studies of Ce_1-xGd_xAl₃, have revealed complex magnetic behavior throughout the series. As observed with Mossbauer spectroscopy magnetic ordering occurs for x ≥ 0.5, though not at the reported spin glass temperatures. For x = 0.23 and x = 0.18, the …

Vorticity Dynamics Of Seasonal Variations Of The Antarctic Circumpolar Current From A Modeling Study, John M. Klinck

CCPO Publications

A one-layer numerical model was developed to analyze the vorticity dynamics of the seasonal variations of currents in the Southern Ocean. The model includes the continental geometry and bathymetry of the Southern Ocean and is forced by monthly climatological wind stress. Five cases are considered that compare (i) circulation over a flat bottom to that with bathymetry, (ii) effects of zonally averaged wind stress forcing versus the climatological forcing and (iii) anomaly wind stress (winds with the annual mean removed) versus the full stress. The individual terms in the vorticity conservation equation are calculated from the model solution along two …

Domain Limitations And Interface Requirements For Expert Developed Knowledge Based Systems, Bernard Lee Lewis

Engineering Management & Systems Engineering Theses & Dissertations

The expanded use of graphical, case-based and object oriented techniques in expert systems creation has made it more practical for domain experts to develop their own applications. This thesis focuses on the elements necessary in an expert/developer interface and looks at various forms and techniques that exemplify such an approach. The spreadsheet metaphor is used for an interface or managed set of interfaces that a domain expert can use in building his own expert system or prototype. criteria are established for such interfaces and recent commercial offerings that make expert-created knowledge-bases more practical are reviewed for techniques that qualify. Approaches …

Thermal Characterization Of Carbon Monoxide Oxidation Catalysts Using Thermogravimetric Analysts And Differential Scanning Calorimetry, Rene A. Bartgis

Chemistry & Biochemistry Theses & Dissertations

Catalysts composed of platinum and/or palladium on tin (IV) oxide supports, with and without silica gel, as well as catalysts composed of gold on manganese oxide, have been developed for the recombination of carbon monoxide and oxygen to form carbon dioxide for use in carbon dioxide lasers. A thermogravimetric method and a differential scanning calorimetric method have been developed for the thermal characterization of these catalysts. The mass loss data and the enthalpy changes determined as the catalysts lost water were then related to existing activity data for these catalysts. No relationship was found between the thermal data and the …

Approaches To High Speed Networks, Frank Charles Paterra

Computer Science Theses & Dissertations

This work investigates possible methods by which existing potentially available communication bandwidth can be used by communication intensive applications. Presently fiber optic media are available that can provide multiple gigabits of throughput. Unfortunately, because of the computation overhead required to insure that data are reliably transmitted this capacity has not been tapped.

A survey of work toward enabling the use of the potential bandwidth is presented. The parallel paradigm is identified as a strong candidate for providing significant increases in system usable bandwidth. Performing communication processing in parallel, however, presents the developer with several implementation options. These options are considered …

Reactions Of Aqueous Chlorine With Valine In Model Solutions And In Wastewater, Erika Forrer Mccormick

Chemistry & Biochemistry Theses & Dissertations

Solutions of the amino acid valine were chlorinated to seven chlorine-to-nitrogen mole (Cl/N) ratios and analyzed by high performance liquid chromatography, gas chromatography/mass spectroscopy, infrared spectroscopy, and nuclear magnetic resonance spectroscopy. The chlorination products found were N-chlorovaline, isobutyraldehyde, isobutyronitrile, and N-chloroisobutyraldimine. Their product distribution depends on the level of chlorination and pH. The main products identified at the lower CI/N mole ratios were N-chlorovaline and isobutyraldehyde, whereas at the higher CI/N mole ratios isobutyronitrile and N-chloroisobutyraldimine were identified as the main products. The concentration and the chlorination products of valine in municipal wastewater were also determined. The chlorination products of …

Processes Affecting The Behavior Of Redox-Sensitive Elements In Chesapeake Bay, Maria Lourdes San Diego-Mcglone

OES Theses and Dissertations

Several processes can affect variations in the chemical composition of an estuary, including (1) biogeochemical reactions in the water column, (2) advective transport, and (3) diffusion from underlying sediments.

The purpose of the study was to establish whether estuarine redox reactions are controlled by a complex interaction of processes 1 to 3. Short-term and long-term studies were conducted in Chesapeake Bay. Redox species involved in redox cycling include oxygen, iron, manganese, hydrogen sulfide, nitrogen species, arsenic and antimony species, while phosphate is indirectly involved in redox cycles. Silicate was used as a non-redox tracer.

For the short-term study, a Lagrangian …

Community Structure Of The Macrobenthos In Back Bay, Virginia, Michael F. Lane

Biological Sciences Theses & Dissertations

A study of the subtidal macrobenthos in Back Bay, Virginia was conducted to examine community structure in relation to sedimentary and water quality characteristics. Samples were collected in August and November of 1987 and February and May of 1988 at ten stations.

Three site groups and three temporal groups were identified by cluster analyses of species abundance. Species composition between site groups was relatively homogeneous and eight species accounted for most of the variation between site groups. A comparison of plots of the biological and physical data in discriminant space suggested that variations in the biological data between site groups …

Computer Simulation Techniques To Assess Bias And Precision In The Roving Creel Survey Estimator, David L. Wade

Biological Sciences Theses & Dissertations

Fisheries scientists use roving creel survey methods to estimate total catch and total effort of recreational fisheries. Bias in the roving creel estimators had been known to the scientific community, but it had not been quantified. I developed a roving-creel-survey computer simulation model to investigate the bias and precision of roving creel estimators, and estimated parameters for the model based on field observations from the blue crab (Callinectes sapidus) fishery of the Chesapeake Bay. The computer model was used to identify bias in roving-creel effort and catch estimators and to demonstrate survey methods that will reduce this bias. …

The Geomorphology Of Alluvial Fan Deposits On The West Flank Of The Blue Ridge, Augusta County, Virginia, Debra Lynn Duffy

OES Theses and Dissertations

Large coalescing alluvial fans mantle the carbonate and shale formations west of the Blue Ridge mountains near Stuarts Draft, Virginia. Fan sediments are predominantly boulder and cobble gravels derived from the Antietam Quartzite, The fan complex consists of three alluvial units of significantly different ages. The surface of each fan unit was mapped using relative geomorphic position, soil color, clay content and thickness of Bt horizons, clast weathering, and degree of removal of depositional surfaces by stream incision. A five-category quartzite clast weathering scale developed for this study was very effective as a measure to distinguish map units. Stratigraphic data …

Lava-Seawater Interactions At Shallow-Water Submarine Lava Flows, Francis J. Sansone, Joseph A. Resing, Gordon W. Tribble, Peter N. Sedwick, Kevin M. Kelly, Ken Hon

OES Faculty Publications

Hydrothermal plumes associated with nearshore lava flows from Kilauea Volcano, Hawaii were studied on five occasions during 1989-1990 to address the current lack of data on direct lava-seawater interactions. The following enrichments were found in the sea-surface hydrothermal plumes above the active underwater lava flows: H₂, 15,000x ambient seawater concentrations; Mn, 250x; and Si, 20x. Water temperatures reached 46°C. Lower concentrations and temperatures were observed in the plumes with increasing distance from shore, with H₂, Si, and Mn concentrations linearly related to seawater temperature. Unlike deep sea spreading center hydrothermal plumes, no CH₄ enrichment was …

On Shock Capturing For Liquid And Gas Media, Tze Jang Chen

Mathematics & Statistics Theses & Dissertations

The numerical investigation of shock phenomena in gas or liquid media where a specifying relation for internal energy is absent poses special problems. Classically, for gas dynamics the usual procedure is to employ a splitting scheme to remove the source terms from the Euler equations, then up-wind biased shock capturing algorithms are built around the Riemann problem for the system which remains. However, in the case where the Euler equations are formulated in the term of total enthalpy, a technical difficulty associated with equation splitting forces a pressure time derivative to be treated as a source term. This makes it …

A Robust Approach To Human-Computer Interface Design Using The Taguchi Method, Billie Mitchell Reed

Engineering Management & Systems Engineering Theses & Dissertations

The application of Dr. Genichi Taguchi's approach for design optimization, called Robust Design, to the design of human-computer interface software is investigated. The Taguchi Method is used to select a near optimum set of interface design alternatives to improve user acceptance of the resulting interface software product with minimum sensitivity to uncontrollable noise caused by human behavioral characteristics.

Design alternatives for interaction with personal micro-computers are identified. Several important and representative alternatives are chosen as design parameters for the Taguchi matrix experiment. A noise field with three human behavioral characteristics as noise factors were chosen as a representative noise array. …

The Solution Of A Singular Integral Equation Arising From A Lifting Surface Theory For Rotating Blades, Mark H. Dunn

Mathematics & Statistics Theses & Dissertations

A technique is presented for the solution of a linear, two dimensional, singular, Volterra integral equation of the first kind. The integral equation, originally developed by Farassat and Myers, is derived from the basic equations of linearized acoustics and models the lifting force experienced by an infinitesimally thin surface moving tangent to itself. As a particular application, the motion of modern high speed aircraft propellers (Advanced Technology Propellers) is considered. The unknown propeller blade surface pressure distribution is approximated by a piecewise constant function and the integral equation is solved numerically by the method of collocation. Certain simplifying assumptions applied …

Fast Parallel Algorithms For Basic Problems, Zhaofang Wen

Computer Science Theses & Dissertations

Parallel processing is one of the most active research areas these days. We are interested in one aspect of parallel processing, i.e. the design and analysis of parallel algorithms. Here, we focus on non-numerical parallel algorithms for basic combinatorial problems, such as data structures, selection, searching, merging and sorting. The purposes of studying these types of problems are to obtain basic building blocks which will be useful in solving complex problems, and to develop fundamental algorithmic techniques.

In this thesis, we study the following problems: priority queues, multiple search and multiple selection, and reconstruction of a binary tree from its …

Stable N-Chloraldimines And Other Chlorination Products Of Phenylalanine In Model Solutions And In A Wastewater, Barbara L. Conyers

Chemistry & Biochemistry Theses & Dissertations

Model solutions of the amino acid phenylalanine were chlorinated to seven Cl/N mole ratios. The by-products were characterized using gas chromatography, high performance liquid chromatography, GC/MS, infrared spectroscopy, and nuclear magnetic resonance spectroscopy. At the lower Cl/N ratios N-chlorophenylalanine and phenylacetaldehyde were identified as the main products while phenylacetonitrile and N-chlorophenylacetaldimine were the major products at Cl/N ratios of 2.0 and beyond. The concentration of phenylalanine in a municipal wastewater was determined. Using a radiotracer the chlorination products of phenylalanine in the wastewater at the 7 Cl/N ratios were identified as those seen in the model solutions. The distribution of …

A Diffuse Reflectance Infrared Fourier Transform Spectroscopic Study Of Platinum/Tin (Iv) Oxide Low-Temperature Carbon Monoxide Oxidation Catalysts, Donna Sue Duarte

Chemistry & Biochemistry Theses & Dissertations

Platinum-coated tin(IV) oxide catalysts have been developed for the recombination of carbon monoxide and oxygen at 55°C and 1 atmosphere of pressure in closed-cycle carbon dioxide lasers. A diffuse reflectance infrared fourier transform spectroscopic (DRIFTS) study of four of these catalysts during 5% carbon monoxide pretreatment at temperatures of 30°C, 100°c, 125°c, and 150°C has been performed. Evidence for the development of surface carbonate, bicarbonate, and formate species during pretreatment has been found. Dehydroxylation of the surface and loss of a partially charged hydrogen-bonded hydroxyl species have also been found to result from elevated temperature pretreatment. The four catalysts have …

Indifference Graphs And The Single Row Routing Problem, Peter J. Looges

Computer Science Theses & Dissertations

This thesis investigates the subclass of interval graphs known as indifference graphs. New optimal algorithms for recognition, center, diameter, maximum matching, Hamiltonian path and domination in indifference graphs are presented. The recognition algorithm produces a linear order with properties which allow the solution of the other problems in linear time. Indifference graphs are further applied to the single row routing problem which results in both sequential,. and parallel routing algorithms.

A Study Of The Reactions Of P-Dipiperidino Benzene And Its Synthesis From 1,4-Dicyano-1,4-Dipiperidinocyclohexane, Ilias Konstantinos Dorziotis

Chemistry & Biochemistry Theses & Dissertations

Following a classical synthesis of PCP² Williams attempted to prepare l,4-diphenyl-1,4-dipiperidino cyclohexane 4¹ . This approach involved the preparation of 1,4- dicyano-1,4-dipiperidinocyclohexane 7 and the subsequent decyanation of the compound with phenylmagnesium bromide to produce 4. This attempt failed, however, as only the monophenylated product, 8, was thought to be obtained. This product had unique reactivity, producing a blue intermediate upon treatment with halogen in both aqueous and non aqueous media. The same intermediate was produced upon irradiation of a chloroform solution of this product with sunlight or UV light in a UV chamber, with the …

Computer Use In The Scientific Office, Douglas L. Miller

Psychology Theses & Dissertations

Over the past two decades computers in research and development organizations have become a complex and integral part of the work process. Yet to date only a handful of systematic investigations have addressed issues involving scientists' or other professionals' use of computers, and very little is known about factors influencing use (Bikson and Gutek, 1983; Blacker and Brown, 1986; Collopy, 1988; Gasser, 1986; Helander, 1985; Nickolson, 1985; Pope, 1985). As a result, this research was designed to address four objectives. The first was to develop and evaluate a descriptive model of variables influencing scientists' computer use. The second objective was …

Effectiveness Analysis Of Knowledge Bases, Shensheng Zhao

Computer Science Theses & Dissertations

Knowledge base systems (expert systems) are entering a critical stage as interest spreads from university research to practical applications. If knowledge base systems are to withstand this transition, special attention must be paid to checking their effectiveness. The issue of effectiveness analysis of knowledge base systems has been largely ignored and few works have been published in this field. This dissertation shows how the effectiveness of a knowledge base system can be defined, discussed and analyzed at the knowledge base system level and the knowledge base level. We characterize the effectiveness of a knowledge base system in terms of minimality, …

Kinematic Synthesis Of Deployable-Foldable Truss Structures Using Graph Theory, Dirk B. Warnaar

Mechanical & Aerospace Engineering Theses & Dissertations

A graph theoretic approach is applied to the conceptual design of deployable truss structures. The characteristics that relate to the inter-connectivity of the elements of a deployable truss structure can be captured in a schematic representation, called a graph. A procedure is presented that enables the exhaustive generation of these graphs for structures of any given number of nodes and links and which are foldable onto a plane or onto a line.

A special type of truss structures, called truss modules, is presented. Graphs of this class of structures form a subset of the graphs of truss structures. Two procedures …

Rotationally Resolved Laser Spectroscopy Of The 3s2Σ+ ← 2p2ii Transition In 6li20ne And 7li20ne Van Der Waals Molecules, Chang Jae Lee

Physics Theses & Dissertations

The rotationally resolved absorption spectrum of the ⁶Li²⁰Ne and ⁷Li²⁰Ne 3s²Σ⁺ ← 2p² II transition has been observed. For each isotope, thirteen vibrational transitions from four vibrational levels (v"=0, 1, 2, and 3) of the lower 2p² II to six (v’=0, 1, 2, 3, 4, and 5) of the upper 3s*Σ⁺ electronic state have been rotationally analyzed. Adiabatic potentials and dissociation energies for both states have been obtained through an inverse perturbation analysis. For the 2p²II state, a well depth of 212(5) cm^-1 and an …

Distribution Of Terrestrially Derived Dissolved Organic Matter On The Southeastern United States Continental Shelf, Mary Ann Moran, Lawrence R. Pomeroy, Edward S. Sheppard, Larry P. Atkinson, Robert E. Hodson

CCPO Publications

Dissolved lignin-derived compounds in seawater indicate the presence of organic matter originating from vascular plants and therefore from terrestrial (upland and coastal marsh) ecosystems. We used a hydrophobic resin to concentrate lignin-rich humic substances and to determine concentrations of lignin oxidation products (vanillyl lignin phenols) for waters of the continental shelf of the southeastern U.S. Lignin phenol concentrations ranged from 0.05 to 4.2µg liter‒1 and accounted for 0.002–0.13% of the total dissolved organic carbon (DOC) pool in continental shelf waters. Dissolved lignin concentrations were generally highest near the shore and in those areas receiving greatest river and marsh …

On A Unique Tree Representation For P4-Extendible Graphs, B. Jamison, S. Olariu

Computer Science Faculty Publications

Several practical applications in computer science and computational linguistics suggest the study of graphs that are unlikely to have more than a few induced paths of length three. These applications have motivated the notion of a cograph, defined by the very strong restriction that no vertex may belong to an induced path of length three. The class of P₄-extendible graphs that we introduce in this paper relaxes this restriction, and in fact properly contains the class of cographs, while still featuring the remarkable property of admitting a unique tree representation. Just as in the case of cographs, the …

Assessment Of Organic And Metal Contaminants In Lower Back Bay And Upper Currituck Sound, Kate Benkert

V. Poster Abstracts

Studies were conducted at Mackay Island National Wildlife Refuge in 1988 and 1989 to provide baseline data for an assessment of organic chemicals and metal contaminants in the aquatic ecosystem. Longnose gar, gizzard shad, snapping turtles, common rangia clams and sediments were collected from sites in lower Back Bay and upper Currituck Sound for contaminant analyses.

Composite sediment samples were analyzed for the presence of metals, organochlorine pesticides and polycyclic aromatic hydrocarbons (PAHs). Organochlorine pesticides were not detected in the sediments. Various PAH compounds were detected in the sediments, although at trace concentrations which just exceeded the analytical detection limit …

Environmental Education: A Chance For The Future, Ben Mathias

V. Poster Abstracts

The U.S. Fish and Wildlife Service is committed to providing environmental education opportunities for the Nation's student body. Local, regional and national educators are invited to investigate and utilize the resources of Back Bay National Wildlife Refuge with their colleagues and students. Teacher workshops at the Refuge provide orientation to Refuge lands, outdoor classroom sites, trails, interpretive facilities and equipment, and potential field activities. Refuge staff members are available to assist with: • Preliminary planning • Group scheduling • Library research • Workshop registration • Trip logistics and • On-site group orientation. Most classroom sites, associated trails/boardwalks, and Visitor Contact …

Observations Of The Phytoplankton Standing Crop At The Shelf Margin Of The Mid Atlantic Bight, Bruce B. Wagoner, Harold G. Marshall

Biological Sciences Faculty Publications

A comparison of the total percentage cell abundance and cell biovolume relationships of major phytoplankton categories was made between two station sets across the shelf margin. Diatom values for abundance and biovolume were greater at oceanic stations compared to the outer shelf stations, with dinoflagellates having the reverse pattern. The composite contributions to biovolume and abundance in the standing crop from other phytoplankton categories were greater over the outer shelf than beyond the shelf margin. The major source of biovolume (biomass) from the outer shelf and these oceanic stations came from the diatoms and dinoflagellates, with an average mean of …

Electric Field Induced Emission As A Diagnostic Tool For Measurement Of Local Electric Field Strengths, A. N. Dharamsi, K. H. Schoenbach

Bioelectrics Publications

The phenomenon of electric field induced (EFI) emission is examined in several diatomic and polyatomic molecules. The possibility of using this phenomenon as a diagnostic tool to measure, nonintrusively, the strength and direction of local electric fields in plasmas is discussed. An estimate of the EFI signal emitted in a typical application plasma is given. This yields a lower bound on the detector sensitivity necessary to exploit EFI emission in practical applications. It is concluded that, at present, the EFI signal could be measured by some very sensitive infrared detection schemes available. Current progress in infrared detector technology, if maintained, …