Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Oceanography and Atmospheric Sciences and Meteorology (1770)
- Physics (1589)
- Engineering (1477)
- Computer Sciences (1456)
- Life Sciences (1068)
-
- Oceanography (1025)
- Social and Behavioral Sciences (593)
- Electrical and Computer Engineering (569)
- Chemistry (561)
- Earth Sciences (557)
- Environmental Sciences (512)
- Climate (468)
- Marine Biology (413)
- Elementary Particles and Fields and String Theory (410)
- Nuclear (360)
- Computer Engineering (355)
- Artificial Intelligence and Robotics (334)
- Engineering Physics (327)
- Mathematics (288)
- Medicine and Health Sciences (287)
- Ecology and Evolutionary Biology (281)
- Quantum Physics (276)
- Public Affairs, Public Policy and Public Administration (258)
- Theory and Algorithms (223)
- Applied Mathematics (220)
- Information Security (211)
- Plasma and Beam Physics (204)
- Atmospheric Sciences (202)
- Statistics and Probability (185)
- Keyword
-
- Climate change (163)
- Sea level rise (143)
- Phytoplankton (117)
- Machine learning (116)
- Chesapeake Bay (111)
-
- Physics (98)
- Virginia (87)
- Cavity (76)
- Deep learning (71)
- Quantum chromodynamics (65)
- Scattering (65)
- Oceanography (61)
- Flooding (58)
- Simulation (58)
- Algorithms (51)
- Model (50)
- Artificial intelligence (49)
- Electron (47)
- Carbon (44)
- Neural networks (44)
- SRF (42)
- Computer simulation (41)
- Variability (41)
- Sea level (39)
- Temperature (39)
- Resilience (38)
- Cybersecurity (37)
- Remote sensing (37)
- Dynamics (36)
- Digital libraries (34)
- Publication Year
- Publication
-
- Physics Faculty Publications (871)
- OES Faculty Publications (481)
- OES Theses and Dissertations (392)
- CCPO Publications (344)
- Electrical & Computer Engineering Faculty Publications (314)
-
- Electrical & Computer Engineering Theses & Dissertations (305)
- Computer Science Faculty Publications (297)
- Chemistry & Biochemistry Faculty Publications (278)
- Mathematics & Statistics Faculty Publications (243)
- Biological Sciences Faculty Publications (182)
- Computer Science Theses & Dissertations (176)
- Physics Theses & Dissertations (174)
- Chemistry & Biochemistry Theses & Dissertations (144)
- Mathematics & Statistics Theses & Dissertations (128)
- Virginia Journal of Science (109)
- News Items (100)
- Biological Sciences Theses & Dissertations (90)
- Cybersecurity Undergraduate Research Showcase (90)
- CCPO Circulation (67)
- VMASC Publications (66)
- Mechanical & Aerospace Engineering Faculty Publications (62)
- Engineering Management & Systems Engineering Faculty Publications (57)
- Computational Modeling & Simulation Engineering Theses & Dissertations (56)
- Bioelectrics Publications (55)
- Engineering Technology Faculty Publications (54)
- Mechanical & Aerospace Engineering Theses & Dissertations (54)
- Engineering Management & Systems Engineering Theses & Dissertations (49)
- Civil & Environmental Engineering Faculty Publications (46)
- Civil & Environmental Engineering Theses & Dissertations (44)
- College of Sciences Posters (42)
- Publication Type
- File Type
Articles 4831 - 4860 of 5954
Full-Text Articles in Physical Sciences and Mathematics
Resolution Of Overlapping Spectra By Wavelength Modulation Spectroscopy, Audra Michiele Bullock
Resolution Of Overlapping Spectra By Wavelength Modulation Spectroscopy, Audra Michiele Bullock
Electrical & Computer Engineering Theses & Dissertations
Wavelength modulation absorption spectroscopy is a highly sensitive, non-intrusive technique for probing gaseous species, which employs the well-known principles of modulation spectroscopy in a novel way. With this technique, parameters such as velocity, density, and temperature can be measured with a high degree of precision. The research presented here shows that wavelength modulation is a convenient means of increasing the sensitivity of an absorption spectroscopy measurement because it allows for harmonic detection. The focus of the dissertation is resolution of overlapping spectra by harmonic detection and the advantages gained by performing detection at the higher harmonics, e.g., sixth and eighth. …
Advanced Atmospheric Water Vapor Dial Detection System, Tamer Refaat
Advanced Atmospheric Water Vapor Dial Detection System, Tamer Refaat
Electrical & Computer Engineering Theses & Dissertations
Measurement of atmospheric water vapor is very important for understanding the Earth's climate and water cycle. The remote sensing Differential Absorption Lidar (DIAL) technique is a powerful method to perform such measurement from aircraft and space. This thesis describes a new advanced detection system, which incorporates major improvements regarding sensitivity and size. These improvements include a low noise advanced avalanche photodiode detector, a custom analog circuit, a 14-bit digitizer, a microcontroller for on board averaging and finally a fast computer interface.
This thesis describes the design and validation of this new water vapor DIAL detection system which was integrated onto …
Routing Optimization Through Computer-Aided Simulation, Madhusudhan Akundi
Routing Optimization Through Computer-Aided Simulation, Madhusudhan Akundi
Electrical & Computer Engineering Theses & Dissertations
Routing has always been a challenging field, and the various techniques of mathematics and operations research have been developed. For commercial organizations, routing has begun to receive extensive attention because of the savings gained in terms of time, money, personnel, and the transportation fleet by developing optimized routing networks. Until recently, it was difficult to develop optimized networks due to the computational difficulties of the problem. However, with the advancement in computer technology and processing speeds, it has become possible to simulate a large number of routing scenarios and determine optimal solutions for a given set of constraints. Not only …
A Flowchart Structure For Modification Of A Modsim Process Model, Murali K. Adatrao
A Flowchart Structure For Modification Of A Modsim Process Model, Murali K. Adatrao
Electrical & Computer Engineering Theses & Dissertations
There are many software processes and software development models that support the development of a software model prior to implementation. However, more often than not, these practices are not followed resulting in a lack of documentation of the intended functionality of the software. As a result, software often becomes a black box for later developers. Even a simple bug fix can turn into an exhaustive task for the developers, as they must attempt to infer the intended system behavior. New designers cannot make any changes to the software or extend the software behavior, as the underlying model within the software …
Electroweak Structure Of Three-And Four-Body Nuclei, Laura Elisa Marcucci
Electroweak Structure Of Three-And Four-Body Nuclei, Laura Elisa Marcucci
Physics Theses & Dissertations
This work reports results for (i) the elastic electromagnetic form factors of the trinucleons; (ii) the nuclear response functions of interest in [e → e'] experiments, at excitation energies below the deuteron breakup threshold; (iii) the astrophysical S-factor for proton weak capture on 3He (the hep reaction). The initial and final state wave functions are calculated using the correlated hyperspherical harmonics method, from a realistic Hamiltonian consisting of the Argonne v18 two-nucleon and Urbana IX three-nucleon interactions. The nuclear electroweak charge and current operators include one- and many-body components. The predicted magnetic form factor of …
Phenomenological Description Of Double-Pion Photoproduction, Andry M. Rakotovao
Phenomenological Description Of Double-Pion Photoproduction, Andry M. Rakotovao
Physics Theses & Dissertations
Double pion photoproduction off proton targets is studied, in the framework of an Effective Lagrangian approach at tree level, based on the coupling of photons and pions to nucleons and resonances. We consider N, Δ(1232), N(1440), N(1520) and N(1535) as intermediate baryonic states and ρ-meson as the intermediate 2π resonance. The general form of the amplitude is presented and total cross sections of the γp → π+π− p, γp → π0π0p and γp → π +π0n processes are evaluated up to Eγ …
Investigations On The Use Of Ion Mobility Spectrometry For Clinical Chemistry Applications, Henri Parson Patten
Investigations On The Use Of Ion Mobility Spectrometry For Clinical Chemistry Applications, Henri Parson Patten
Theses and Dissertations in Biomedical Sciences
The major objective of this research is to examine ion mobility spectrometry as a rapid screening tool for specific application to clinical chemistry research and laboratory use. Methodology was developed for target analytes representing several classes of physiologically active substances, including anesthetics, illicit drugs, and their metabolites. The IMS characteristics of animal tissues and other compounds such as amino acids and proteins were determined. Quality assurance and control procedures were developed for specific quality data objectives. Criteria were established relating to use of IMS for assessing the precision and accuracy of data, qualitative screening, and semi-quantitative analyses.
It was found …
Effects Of Elevated Atmospheric Co2 On Root Growth, Turnover And Decomposition In A Scrub Oak Ecosystem, John Joseph Dilustro
Effects Of Elevated Atmospheric Co2 On Root Growth, Turnover And Decomposition In A Scrub Oak Ecosystem, John Joseph Dilustro
Biological Sciences Theses & Dissertations
Atmospheric carbon dioxide levels are increasing and predicted to double this century. The implications of this rise on vegetation structure and function are not well understood. Measurement of root growth response to elevated atmospheric carbon dioxide is critical to understanding soil carbon input. I investigated the effects of elevated carbon dioxide on fine root growth and decomposition using open top chambers with both ambient and elevated (700 PPM) CO2 treatments in an oak-palmetto scrub ecosystem at Kennedy Space Center, Florida. Minirhizotron tubes were installed in each elevated and control chamber to allow observation of roots. Each tube was sampled …
Design Of Adaptive Sliding Mode Fuzzy Control For Robot Manipulator Based On Extended Kalman Filter, Abdelrahman Aledhaibi
Design Of Adaptive Sliding Mode Fuzzy Control For Robot Manipulator Based On Extended Kalman Filter, Abdelrahman Aledhaibi
Mechanical & Aerospace Engineering Theses & Dissertations
In this work, a new adaptive motion control scheme for robust performance control of robot manipulators is presented. The proposed scheme is designed by combining the fuzzy logic control with the sliding mode control based on extended Kalman filter. Fuzzy logic controllers have been used successfully in many applications and were shown to be superior to the classical controllers for some nonlinear systems. Sliding mode control is a powerful approach for controlling nonlinear and uncertain systems. It is a robust control method and can be applied in the presence of model uncertainties and parameter disturbances, provided that the bounds of …
Buckets: Smart Objects For Digital Libraries, Michael L. Nelson
Buckets: Smart Objects For Digital Libraries, Michael L. Nelson
Computer Science Theses & Dissertations
Discussion of digital libraries (DLs) is often dominated by the merits of various archives, repositories, search engines, search interfaces and database systems. While these technologies are necessary for information management, information content and information retrieval systems should progress on independent paths and each should make limited assumptions about the status or capabilities of the other. Information content is more important than the systems used for its storage and retrieval. Digital information should have the same long-term survivability prospects as traditional hardcopy information and should not be impacted by evolving search engine technologies or vendor vagaries in database management systems.
Digital …
Circulation, Vol. 7, No. 2, Center For Coastal Physical Oceanography, Old Dominion University, Bettina Fach
Circulation, Vol. 7, No. 2, Center For Coastal Physical Oceanography, Old Dominion University, Bettina Fach
CCPO Circulation
Spring 2000 issue of CCPO Circulation featuring article "Cruising the Southern Ocean" by Bettina Fach
Binding Of Pb And Zn To Aluminium Oxide And Proton Stoichiometry, Wing H. Leung, A. Kimaro
Binding Of Pb And Zn To Aluminium Oxide And Proton Stoichiometry, Wing H. Leung, A. Kimaro
Virginia Journal of Science
The interaction of Pb and Zn with Al2O3 in aqueous solution was studied as a function of pH and metal ion concentration. Results indicated the complexation of metal ions by oxide surfaces is strongly pH dependent; the extent of adsorption is a function of pH with an abrupt change within approximately 2 pH units. The adsorption of Pb and Zn on aluminium oxide can be interpreted in terms of a surface complexation formed by association with one surface AlOH group, thus releasing one bound hydrogen ion. -AlOH + M2+ = -AlOM+ + H+ . …
The Fermat Point And The Steiner Problem, J. N. Boyd, P. N. Raychowdhury
The Fermat Point And The Steiner Problem, J. N. Boyd, P. N. Raychowdhury
Virginia Journal of Science
We revisit the convex coordinates of the Fermat point of a triangle. We have already computed these convex coordinates in a general setting. In this note, we obtain the coordinates in the context of the Steiner problem. Thereafter, we pursue calculations suggested by the problem.
Jeffress Research Grant Awards
Jeffress Research Grant Awards
Virginia Journal of Science
Announcements of the Jeffress Research Grants that have been awarded in 1999.
Wavelength Modulation Spectroscopy Of Water Vapor And Line Center Stabilization At 1.462 Μm For Lidar Applications, Colleen Marie Fitzgerald
Wavelength Modulation Spectroscopy Of Water Vapor And Line Center Stabilization At 1.462 Μm For Lidar Applications, Colleen Marie Fitzgerald
Electrical & Computer Engineering Theses & Dissertations
Wavelength modulation spectroscopy was employed to investigate water vapor absorption lines in the 1.462 µm wavelength region using an external-cavity diode laser. These measurements were necessary in the development of a lidar (light detection and ranging) instrument for differential absorption measurement of the concentration and movement of water vapor in the Earth's atmosphere. Differential absorption measurements require that the laser frequency remain stable throughout the duration of the measurement. To ensure this stability, the laser output wavelength is monitored and a feedback control loop set up to minimize laser line drift. Three lines were investigated in the 1.462 µm region. …
A Generic Object-Oriented Server Model, Brian Douglas Jones
A Generic Object-Oriented Server Model, Brian Douglas Jones
Electrical & Computer Engineering Theses & Dissertations
The purpose of this paper is to introduce a generic, object-oriented model for the simulation of networks of queues. Generic simulation modeling provides robust ways of laying out processes in stochastic, event driven simulations. The approach taken is to define a methodology that will be implementation independent, termed the Generic Server Simulation Model (GSSM); thus, leaving the implementers to choose the best (most suited for their use) means of implementation. GSSM uses many object-oriented concepts to provide its basic structure and has in its design the ability to take advantage of these object-oriented concepts, including reuse of (existing) code. GSSM …
A Digital Pressure Sensor Data Acquisition System In A Wind Tunnel Model, John J. Novakoski
A Digital Pressure Sensor Data Acquisition System In A Wind Tunnel Model, John J. Novakoski
Electrical & Computer Engineering Theses & Dissertations
Pressure measurements on wind tunnel models provide an important aid to overall aerodynamic analysis and design of aircraft and vehicles. Most pressure measurements in wind tunnels are made using analog pressure sensors with interfacing electronics that connect to an external data acquisition unit. Some of desirable features of an improved pressure measurement system are that it be: 1) model embeddable, 2) inherently digital in nature, 3) intelligent, and 4) controllable by a remote computer.
An intelligent, model-embedded, eight-channel digital pressure sensor system has been developed and tested in a wind tunnel. The implemented system consists of Micro-Electro-Mechanical System (MEMS) digital …
An Object-Oriented Algorithmic Laboratory For Ordering Sparse Matrices, Gary Karl Kumfert
An Object-Oriented Algorithmic Laboratory For Ordering Sparse Matrices, Gary Karl Kumfert
Computer Science Theses & Dissertations
We focus on two known NP-hard problems that have applications in sparse matrix computations: the envelope/wavefront reduction problem and the fill reduction problem. Envelope/wavefront reducing orderings have a wide range of applications including profile and frontal solvers, incomplete factorization preconditioning, graph reordering for cache performance, gene sequencing, and spatial databases. Fill reducing orderings are generally limited to—but an inextricable part of—sparse matrix factorization.
Our major contribution to this field is the design of new and improved heuristics for these NP-hard problems and their efficient implementation in a robust, cross-platform, object-oriented software package. In this body of research, we (1) examine …
Generalized Compton Amplitudes In Quantum Chromodynamics, Ignati Grigentch
Generalized Compton Amplitudes In Quantum Chromodynamics, Ignati Grigentch
Physics Theses & Dissertations
In this dissertation we describe results of our studies of generalized Compton amplitudes. We have calculated the one-loop corrections to the amplitude in the coordinate representation in terms of nonlocal string light-ray operators. We have also developed a consistent approach to the problem of constructing the gauge invariant Compton amplitude and obtained an expression for the explicitly gauge invariant amplitude which includes all the generalized target-mass corrections.
A Semantic-Based Middleware For Multimedia Collaborative Applications, Agustin Jose Gonzalez
A Semantic-Based Middleware For Multimedia Collaborative Applications, Agustin Jose Gonzalez
Computer Science Theses & Dissertations
The Internet growth and the performance increase of desktop computers have enabled large-scale distributed multimedia applications. They are expected to grow in demand and services and their traffic volume will dominate. Real-time delivery, scalability, heterogeneity are some requirements of these applications that have motivated a revision of the traditional Internet services, the operating systems structures, and the software systems for supporting application development. This work proposes a Java-based lightweight middleware for the development of large-scale multimedia applications. The middleware offers four services for multimedia applications. First, it provides two scalable lightweight protocols for floor control. One follows a centralized model …
Diffusion Problems In Wound Healing And A Scattering Approach To Immune System Interactions, Julia Suzanne Arnold
Diffusion Problems In Wound Healing And A Scattering Approach To Immune System Interactions, Julia Suzanne Arnold
Mathematics & Statistics Theses & Dissertations
A theoretical model for the existence of a Critical Size Defect (CSD) in certain animals is the focus of the majority of this dissertation. Adam [1] recently developed a one-dimensional model of this phenomenon, and chapters I–V address the exist the CSD in a two-dimensional model and a three-dimensional model. The two dimensional (or 1-d circular) model is the more appropriate for a study of CSD's. In that model we assume a circular wound of uniform depth and develop a time-independent form of the diffusion equation relevant to the study of the CSD phenomenon. It transpires that the range of …
Precision Measurement Of The Spin Structure Of The Proton And The Deuteron, Frank R. Wesselmann
Precision Measurement Of The Spin Structure Of The Proton And The Deuteron, Frank R. Wesselmann
Physics Theses & Dissertations
Experiment E155 at the Stanford Linear Accelerator Center measured the spin structure functions g1 and g2 of the proton and deuteron using deep inelastic scattering of 50 GeV polarized electrons from dynamically polarized, solid 15NH3 and 6LiD targets. Three independent spectrometers, covering a large kinematic region, 0.014 < xBjorken < 0.9 and 1 < Q2 < 40 (GeV /c)2, detected 200 million events. A fully self-consistent and statistically sound approach to calculating radiative corrections was developed, providing well-defined statistical errors for the E155 data set. Also, a comprehensive fit to the global data set was created which simultaneously …
Process Flow Optimization Studies Through Discrete Event Simulation, Milind Chokshi
Process Flow Optimization Studies Through Discrete Event Simulation, Milind Chokshi
Electrical & Computer Engineering Theses & Dissertations
Computer-aided simulation has begun to emerge as a powerful tool for numerical analysis of the behavior and anticipated performance of industrial systems and their optimization. Applications include materials handling, storage and controls systems, prediction of manufacturing efficiencies, and production optimization. Simulations are used to test baseline models and subsequently analyze new production concepts, operating strategies, and planned procedures prior to costly implementation.
The study of process flows in a manufacturing environment is difficult due to its inherent stochastic nature. Breakdown of the sub-systems and failures of machines is a random process and needs to be solved based on concepts of …
Modeling The Growth Dynamics Of Antarctic Krill Euphausia Superba, Eileen E. Hofmann, Cathy M. Lascara
Modeling The Growth Dynamics Of Antarctic Krill Euphausia Superba, Eileen E. Hofmann, Cathy M. Lascara
CCPO Publications
A time-dependent, size-structured, bioenergetically based model was developed to examine the growth dynamics of Antarctic krill Euphausia superba 2 to 60 mm in size. The metabolic processes included in the model are ingestion, a baseline respiration, respiratory losses due to feeding and digestion, and an activity-based respiration factor. The total of these processes, net production, was used as the basis for determining the growth or shrinkage of individuals. Size-dependent parameterizations for the metabolic processes were constructed from field and laboratory measurements. Environmental effects were included through time series of pelagic phytoplankton concentration that were derived from data sets collected west …
On The Seasonal Mixed Layer Simulated By A Basin-Scale Ocean Model And The Mellor-Yamada Turbulence Scheme, Tal Ezer
CCPO Publications
Seasonal changes and vertical mixing processes in the upper layers of the North Atlantic Ocean are simulated with a basin-scale sigma coordinate ocean model that uses the Mellor-Yamada turbulence closure scheme. The cause of insufficient surface mixing and a too shallow summertime thermocline, common problems of ocean models of this type, is investigated in detail by performing a series of sensitivity experiments with different surface forcing conditions and different turbulence parameterizations. A recent improvement in the parameterization of the dissipation term in the Mellor-Yamada turbulence scheme, which has shown a significant improvement in one-dimensional calculations, had a positive but relatively …
Blending Hf Radar And Model Velocities In Monterey Bay Through Normal Mode Analysis, B. L. Lipphardt Jr., A. D. Kirwan Jr., C. E. Grosch, J. K. Lewis, J. D. Paduan
Blending Hf Radar And Model Velocities In Monterey Bay Through Normal Mode Analysis, B. L. Lipphardt Jr., A. D. Kirwan Jr., C. E. Grosch, J. K. Lewis, J. D. Paduan
CCPO Publications
Nowcasts of the surface velocity field in Monterey Bay are made for the period August 1-9, 1994, using HF radar observations blended with results from a primitive equation model. A spectral method called normal mode analysis was used. Objective spatial and temporal filtering were performed, and stream function, velocity potential, relative vorticity, and horizontal divergence were calculated over the domain. This type of nowcasting permits global spectral analysis of mode amplitudes, calculation of enstrophy, and additional analyses using tools like empirical orthogonal functions. The nowcasts reported here include open boundary flow information from the numerical model. Nowcasts using no open …
Can An Optical Plankton Counter Produce Reasonable Estimates Of Zooplankton Abundance And Biovolume In Water With High Detritus?, X. Zhang, M. Roman, A. Sanford, H. Adolf, C. Lascara, R. Burgett
Can An Optical Plankton Counter Produce Reasonable Estimates Of Zooplankton Abundance And Biovolume In Water With High Detritus?, X. Zhang, M. Roman, A. Sanford, H. Adolf, C. Lascara, R. Burgett
CCPO Publications
The Optical Plankton Counter (OPC) has been used in oceanic and fresh waters to estimate zooplankton abundance and biovolume. However, it is not clear whether the OPC can produce accurate estimates of zooplankton abundance and biovolume in waters with high detritus. In order to test the capability of the OPC to estimate zooplankton abundance and biovolume in Chesapeake Bay, two sets of laboratory experiments were conducted using water with high detritus concentrations collected from the upper Choptank estuary of Chesapeake Bay and laboratory cultured Artemia. Our results suggest that the OPC is able to produce accurate estimates of zooplankton biovolume …
Quantitative Analysis Of Ultra-Fine Goethite In Rust Layer On Steel Using Mossbauer And X-Ray Diffraction Spectroscopy, Masato Yamashita, Toshihei Misawa, H. E. Townsend, D. C. Cook
Quantitative Analysis Of Ultra-Fine Goethite In Rust Layer On Steel Using Mossbauer And X-Ray Diffraction Spectroscopy, Masato Yamashita, Toshihei Misawa, H. E. Townsend, D. C. Cook
Physics Faculty Publications
We have proposed determination procedure of the relative amounts of rust constituents of steel. Mossbauer spectroscopy provides the relative amounts of crystalline rust constituents including ultra-fine crystals. A quantitative analysis of ultra-fine crystals is possible with the resolution of several percent by comparing the Mossbauer results with the relative amounts of rust constituents determined by X-ray diffraction spectroscopy.
Renormalons As Dilation Modes In The Functional Space, A. Babansky, I. Balitsky
Renormalons As Dilation Modes In The Functional Space, A. Babansky, I. Balitsky
Physics Faculty Publications
There are two possible sources of the factorial large-order behavior of a typical perturbative series. First, the number of different Feynman diagrams may be large; second, there may be abnormally large diagrams known as renormalons. It is well known that the large combinatorial number of diagrams is described by instanton-type solutions of the classical equations. We demonstrate that, from the functional-integral viewpoint, the renormalons do not correspond to a particular configuration but manifest themselves as dilatation modes in the functional space.
Deeply Virtual Compton Scattering At Small X, Ian Balitsky, Elena Kuchina
Deeply Virtual Compton Scattering At Small X, Ian Balitsky, Elena Kuchina
Physics Faculty Publications
We calculate the cross section of deeply virtual Compton scattering at large energies and intermediate momentum transfers.