Digital Commons Network^™

Characterization Of Generalized Haar Spaces, M. Bartelt, W. Li

Mathematics & Statistics Faculty Publications

We say that a subset G of C₀(T, ℝ^k) is rotation-invariant if [Qg: g ∈ G]=G for any k x k orthogonal matrix Q. Let G be a rotation-invariant finite-dimensional subspace of C₀(T, ℝ^k) on a connected, locally compact, metric space T. We prove that G is a generalized Haar subspace if and only if P_G(ƒ) is strongly unique of order 2 whenever P_G(ƒ) is a singleton.

Error Correcting Codes Associated With Complex Hadamard Matrices, I. Heng, C. H. Cooke

Mathematics & Statistics Faculty Publications

For primes p > 2, the generalized Hadamard matrix H(p,pt) can be expressed as H = x^A, where the notation means h_ij = x^aij. It is shown that the row vectors of A represent a p-ary error correcting code. Depending upon the value of t, either linear or nonlinear codes emerge. Code words are equidistant and have minimum Hamming distance d = (p − 1)t. The code can be extended so as to possess N = p²t code words of length pt …

The Adjoint Alternative For Matrix Operators, C. H. Cooke

Mathematics & Statistics Faculty Publications

The following inverse problem is considered: given a matrix B of rank r, does there exist a matrix A such that

B = T(A) = adjoint (A)

where the classical adjoint operation is intended? Conditions are determined on the rank of B which decides whether or not B lies in the range of the matrix adjoint operator.

Steady Incompressible Magnetohydrodynamic Flow Near A Point Of Reattachment, J. M. Dorrepaal, S. Moosavizadeh

Mathematics & Statistics Faculty Publications

The oblique stagnation-point flow of an electrically conducting fluid in the presence of a magnetic field is a highly nonlinear problem whose solution is of interest even in the simplest of geometries. The problem models the flow of a viscous conducting fluid near a point where a separation vortex reattaches itself to a rigid boundary. A similarity solution exists which reduces the problem to a coupled system of four ordinary differential equations which can be integrated numerically. The problem has two independent parameters, the conductivity of the fluid and the strength of the magnetic field. Solutions are tabulated for a …

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 …

On The Structure Of Graphs With Few P4s, Luitpold Babel, Stephan Olariu

Computer Science Faculty Publications

We present new classes of graphs for which the isomorphism problem can be solved in polynomial time. These graphs are characterized by containing — in some local sense — only a small number of induced paths of length three. As it turns out, every such graph has a unique tree representation: the internal nodes correspond to three types of graph operations, while the leaves are basic graphs with a simple structure. The paper extends and generalizes known results about cographs, P₄-reducible graphs, and P₄-sparse graphs.

Thermodynamic Modeling And Analysis Of Human Stress Responses, Satish C. Boregowda

Mechanical & Aerospace Engineering Theses & Dissertations

A novel approach based on the second law of thermodynamics is developed to investigate the psychophysiology and quantify human stress level. Two types of stresses (thermal and mental) are examined. A Unified Stress Response Theory (USRT) is developed under the new proposed field of study called Engineering Psychophysiology. The USRT is used to investigate both thermal and mental stresses from a holistic (human body as a whole) and thermodynamic viewpoint. The original concepts and definitions are established as postulates which form the basis for thermodynamic approach to quantify human stress level. An Objective Thermal Stress Index (OTSI) is developed by …

Buckets: Aggregative, Intelligent Agents For Publishing, Michael L. Nelson, Kurt Maly, Stewart N. T. Shen, Mohammad Zubair

Computer Science Faculty Publications

Buckets are an aggregative, intelligent construct for publishing in digital libraries. The goal of research projects is to produce information. This information is often instantiated in several forms, differentiated by semantic types (report, software, video, datasets, etc.). A given semantic type can be further differentiated by syntactic representations as well (PostScript version, PDF version, Word version, etc.). Although the information was created together and subtle relationships can exist between them, different semantic instantiations are generally segregated along currently obsolete media boundaries. Reports are placed in report archives, software might go into a software archive, but most of the data and …

Creating A Canonical Scientific And Technical Information Classification System For Ncstrl+, Melissa E. Tiffany, Michael L. Nelson

Computer Science Faculty Publications

The purpose of this paper is to describe the new subject classification system for the NCSTRL+ project. NCSTRL+ is a canonical digital library (DL) based on the Networked Computer Science Technical Report Library (NCSTRL). The current NCSTRL+ classification system uses the NASA Scientific and Technical (STI) subject classifications, which has a bias towards the aerospace, aeronautics, and engineering disciplines. Examination of other scientific and technical information classification systems showed similar discipline-centric weaknesses. Traditional, library-oriented classification systems represented all disciplines, but were too generalized to serve the needs of a scientific and technically oriented digital library. Lack of a suitable existing …

A Fast Parallel Algorithm To Recognize P4-Sparse Graphs, Rong Lin, Stephan Olariu

Computer Science Faculty Publications

A number of problems in mobile computing, group-based collaboration, automated theorem proving, networking, scheduling, and cluster analysis suggested the study of graphs featuring certain “local density” characteristics. Typically, the notion of local density is equated with the absence of chordless paths of length three or more. Recently, a new metric for local density has been proposed, allowing a number of such induced paths to occur. More precisely, a graphG is called P4-sparse if no set of five vertices inG induces more than one chordless path of length three. P4-sparse graphs generalize the well-known class of cographs corresponding to …

Ecology Of The Eastern Cottonmouth (Agkistrodon P. Piscivorus) At Back Bay National Wildlife Refuge: A Comparative Study Of Natural And Anthropogenic Marsh Habitats, Chad Lee Cross

Biological Sciences Theses & Dissertations

Mark-recapture sampling and radiotelemetry were used to investigate populations of the eastern cottonmouth, Agkistrodon p. piscivorus, in both natural and anthropogenic marsh habitats at Back Bay National Wildlife Refuge (BBNWR), Virginia Beach, Virginia from autumn 1995 to late spring 1998. Mark-recapture subjects were captured, marked by ventral scale-clipping, and released back into the population. A modified Schnabel Census estimator was used to estimate population sizes and corresponding densities in both marsh systems based on a total of 244 captures of 222 individuals. Most snakes were found >0.05 in from water, but it was apparent that proximity to water played …

Atomic Hydrogen Cleaning Of Inp(100) For Preparation Of A Negative Electron Affinity Photocathode, K. A. Elamrawi, M. A. Hafez, H. E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Atomic hydrogen cleaning is used to clean InP(100) negative electron affinity photocathodes. Reflection high-energy electron diffraction patterns of reconstructed, phosphorus-stabilized, InP(100) surfaces are obtained after cleaning at ∼400 °C. These surfaces produce high quantum efficiency photocathodes (∼8.5%), in response to 632.8 nm light. Without atomic hydrogen cleaning, activation of InP to negative electron affinity requires heating to ∼530 °C. At this high temperature, phosphorus evaporates preferentially and a rough surface is obtained. These surfaces produce low quantum efficiency photocathodes (∼0.1%). The use of reflection high-energy electron diffraction to measure the thickness of the deposited cesium layer during activation by correlating …

Modeling Electromagnetic Disturbances In Closed-Loop Computer Controlled Flight Systems, W. Steven Gray, Oscar R. Gonzalez

Electrical & Computer Engineering Faculty Publications

High intensity electromagnetic radiation has been demonstrated to be a source of computer upsets in commercially available digital flight control systems. In this paper we introduce an electromagnetic disturbance model which can be used for stability analysis and augmentation of any such digitally implemented control law. The model is composed of a Markovian exosystem supplying radiation events to a discrete-time jump linear system which models how the radiation interferes with the nominal operation of the closed-loop system. We discuss how this model can be used to characterize stability and how it can be parametrized and validated in an experimental setting.

Placement Of Piezoelectric Actuators For Active Control Of Vibration Using Modal Parameters, Xuegeng Zhu

Mechanical & Aerospace Engineering Theses & Dissertations

An equation is derived to model the piezoelectric actuators incorporation with flexible structures. This equation permits the comparison of the performance indices over the entire structure for a piezoelectric actuator with constant area, which is unachievable if the Finite Element Method is used for complicated structures.

An index has been developed for placement of piezoelectric actuator for control of vibration of a flexible structure. This index is derived from the definition of H2norm. Computation of the proposed index requires only the natural frequencies and corresponding mode shapes of the structures of interest. The method is well suited to large …

A Hierarchical Filtering-Based Monitoring Architecture For Large-Scale Distributed Systems, Ehab Salem Al-Shaer

Computer Science Theses & Dissertations

On-line monitoring is essential for observing and improving the reliability and performance of large-scale distributed (LSD) systems. In an LSD environment, large numbers of events are generated by system components during their execution and interaction with external objects (e.g. users or processes). These events must be monitored to accurately determine the run-time behavior of an LSD system and to obtain status information that is required for debugging and steering applications. However, the manner in which events are generated in an LSD system is complex and represents a number of challenges for an on-line monitoring system. Correlated events axe generated concurrently …

Structure And Dynamics Of Few-Nucleon Systems, J. Carlson, R. Schiavilla

Physics Faculty Publications

Few-nucleon physics is a field rich with high-quality experimental data and possibilities for accurate calculations of strongly correlated quantum systems. In this article the authors discuss the traditional model of the nucleus as a system of interacting nucleons and outline many recent experimental results and theoretical developments in the field of few-nucleon physics. The authors describe nuclear structure and spectra, clustering and correlations, elastic and inelastic electromagnetic form factors, low-energy electroweak reactions, and nuclear scattering and response in the quasi-elastic regime. Through a review of the rich body of experimental data and a variety of theoretical developments, a coherent description …

Factorization For High-Energy Scattering, Ian Balitsky

Physics Faculty Publications

I demonstrate that the amplitude for the high-energy scattering can be factorized into a product of two independent functional integrals over “fast” and “slow” fields which interact by means of Wilson-line operators—gauge factors ordered along the straight lines.

Factorization And Effective Action For High-Energy Scattering In Qcd, Ian Balitsky

Physics Faculty Publications

The author demonstrates that the amplitude of the high-energy scattering can be factorized in a convolution of the contributions due to fast and slow fields. The fast and slow fields interact by means of Wilson-line operators -- infinite gauge factors ordered along the straight line. The resulting factorization formula gives a starting point for a new approach to the effective action for high-energy scattering.

Corrigendum To “Post-Surgical Passive Response Of Local Environment To Primary Tumor Removal”: Mathl. Comput. Modelling, Vol. 25, No. 6, Pp. 7–17, 1997, J. A. Adam, C. Bellomo

Mathematics & Statistics Faculty Publications

The computer program that was used to generate the graphs for the concentration of inhibitor contained an error. This influenced the scaling in the original Figures 2 and 3. As an example, a sample of the corrected graphs are given below. Copies of other corrected figures can be obtained from the authors. It is important to note that the “pulse” appears for the function rC(r, t). As can be seen, it travels slowly outward with decreasing amplitude. The mathematical analysis in the paper remains unchanged.

Data Assimilation Experiments In The Gulf Stream Region: How Useful Are Satellite-Derived Surface Data For Nowcasting The Subsurface Fields?, Tal Ezer, George L. Mellor

CCPO Publications

Satellite-derived surface data have become an important source of information for studies of the Gulf Stream system. The question of just how useful these datasets are for nowcasting the subsurface thermal fields, however, remains to be fully explored. Three types of surface data-sea surface temperature (SST), sea surface height (SSH), and Gulf Stream position (GSP)-are used here in a series of data assimilation experiments to test their usefulness when assimilated into a realistic primitive equation model. The U.S. Navy's analysis fields from the Optimal Thermal Interpolation System are used to simulate the surface data and to evaluate nowcast errors. Correlation …

Tidally Driven Residual Circulation In Shallow Estuaries With Lateral Depth Variation, Chunyan Li, James O'Donnell

CCPO Publications

Tidally driven residual circulation in shallow estuaries with lateral depth variation has been studied analytically using a two-dimensional, depth-averaged model. The solution is presented for a v-shaped channel. Exchange flow is found to be correlated with the topography. The magnitude of this exchange flow depends mainly on four parameters: the ratio between the minimum depth on the shoal and the maximum depth in the channel, the ratio between the tidal amplitude at the mouth and the mean depth, the ratio between the length of the estuary and the tidal wave length, and the ratio between the tidal timescale and the …

Vertical Profiles Of Bromoform In Snow, Sea Ice, And Seawater In The Canadian Arctic, William T. Sturges, Glenn F. Cota, Paul T. Buckley

CCPO Publications

Bromoform (CHBr₃) was measured in vertical profiles from the snow surface through the snowpack, sea ice, and water column to the seafloor at Resolute Bay, Canada, in the sprig of 1992. Elevated concentrations of bromoform were observed in both the ice (32-266 ng L^-1 by liquid water volume) and seawater (~ 20 ng L^-1 ) at the ice-water interface, associated with bromoform emission from ice microalgae. A surprising finding was a second horizon of high bromoform concentrations (336-367 ng L^-1) in sea ice at the snow-ice interface. Chlorophyll and salinity were also elevated in …

Circulation, Vol. 5, No. 1, Center For Coastal Physical Oceanography, Old Dominion University

CCPO Circulation

Fall 1997 issue of CCPO Circulation featuring article "CCPO, ODU, and Internet2"

A Proposed Approach To Iso Compliance And Validation For Metrology Laboratories, J. Lyle Bagley

Engineering Management & Systems Engineering Theses & Dissertations

International competition among metrology laboratories, as well as their customers, has intensified the incentive to seek either accreditation to ISO Guide 25 or ISO 9000 quality system registration for the laboratory. The debate continues as to which is more beneficial to the laboratory and its customers once the decision is made to pursue one or the other. This study addresses the advantages and limitations of each, and how best to prepare for complying with ISO standards. The literature was reviewed and ISO certification experts were questioned about these issues. The results were combined with new applications of existing operations research …

Formal Specification Of Fragmentation And Reassembly In Ipv6, Ibrahim Sahin

Electrical & Computer Engineering Theses & Dissertations

Development and implementation of a networking standard such as the new Internet Protocol (IPv6) is a very difficult process. Different implementations of the standard must be fully compatible to allow different computers to communicate with each other. However, standards are often ambiguous, frequently a result of providing specifications in the English language. A more formal specification could assist in the design of systems. This thesis demonstrates that capability using the Prototype Verification System (PVS).

In this thesis study, a formal specification for fragmentation and reassembly in IPv6 was created to provide a tool for the standardization of IPv6 using PVS. …

Selective Cvd Growth Of Diamond Crystals On Tungsten, Charles Randal Cole

Electrical & Computer Engineering Theses & Dissertations

Typical field emitters consist of sharp metal tips which usually have a short life due to erosion and contamination. To improve the performance of regular field emitters, diamond can be placed on the emitter tip. This is done by selectively growing diamond on tungsten tips using chemical vapor deposition (CVD) processing. Diamond exhibits negative electron affinity, so that electrons will be emitted by properly biasing the tip.

To obtain single crystal growth right at the tip, a cantilever controlled nucleation method was developed which worked better than other methods. Surface preparation was also important to the growth process. An oxide …

Velocity Estimation Via A Neural Network Enhanced By Classical Detection Algorithms, Zeki Berk Hamşioğlu

Electrical & Computer Engineering Theses & Dissertations

The goal of this research is to show how to solve a velocity estimation problem using a neural network connected to an array of sensors. Motivated by biological studies involving insect vision, the neural network utilized is a member of a class of shunting neural networks. When an object moves across the face of the sensor array, the neural network's pulse response is first temporally located using classical M-ary detection techniques. Both the deterministic and stochastic cases are considered. Then the network's pulse response is post-processed via an existing velocity estimation algorithm based on a Volterra series model of the …

Building Multi-Discipline, Multi-Format Digital Libraries Using Clusters And Buckets, Michael L. Nelson

Computer Science Theses & Dissertations

Our objective was to study the feasibility of extending the Dienst protocol to enable a multi-discipline, multi-format digital library. We implemented two new technologies: cluster functionality and publishing buckets. We have designed a possible implementation of clusters and buckets, and have prototyped some aspects of the resultant digital library.

Currently, digital libraries are segregated by the disciplines they serve ( computer science, aeronautics, etc.), and by the format of their holdings (reports, software, datasets, etc.). NCSTRL+ is a multi-discipline, multi-format digital library (DL) prototype created to explore the feasibility of the design and implementation issues involved with created a …

Circulation, Vol. 4, No. 4, Center For Coastal Physical Oceanography, Old Dominion University

CCPO Circulation

Summer 1997 issue of CCPO Circulation featuring article "HF Radar: Is It Ready for Prime Time"

Simulations Of The Atlantic Ocean With A Free Surface Sigma Coordinate Ocean Model, Tal Ezer, George L. Mellor

CCPO Publications

A sigma coordinate, free surface numerical model with turbulence dynamics has been implemented for the Atlantic Ocean and the Greenland Sea, from 80°S to 80°N. It is driven at the surface by monthly mean sea surface temperature and wind stress climatologies and is executed for 30 years. This is the first time that a model of this type, previously used mostly for coastal and regional simulations, has been implemented for the entire Atlantic Ocean and run for a long period of time. The model horizontal circulation, thermohaline overturning circulation, and meridional heat fluxes are described; the results are compared with …