Digital Commons Network^™

Academic Fleet Renewal- Two Years Later, Larry Atkinson

CCPO Publications

(First paragraph) In November 2000, I wrote a Soapbox article on fleet renewal for Sea Technology. It is a little unsettling to see how slowly ideas move towards implementation. Nevertheless, we are making progress. In this editorial I will note a bit of that progress and try to guess where we will be in two more years.

Reversing Circulation Patterns In A Tropical Estuary, Arnoldo Valle-Levinson, Kathryn T. Bosley

CCPO Publications

A combination of current velocity and water density measurements was used to characterize the basic patterns of water exchange in the Gulf of Fonseca, a tropical estuary on the Pacific Ocean side of Central America. The measurements were obtained during spring and neap tides in March ( dry season) and June ( wet season) of 2001 and consisted of profiles of current velocity and density along four transects. From mid-March to mid-April a time series of hourly surface current velocity maps was also obtained with a high-frequency radar system of two antennas. The sampling transects and the radar coverage concentrated …

Inquiry In Technology Education, Philip A. Reed, Kurt R. Helgeson (Ed.), Anthony E. Schwaller (Ed.)

STEMPS Faculty Publications

Technology education involves much more than instruction of the artifacts and methods of technology. The increasing amount and complexity of technology require students to know how to use, manage, assess, and understand technology. Inquiry is a cognitive instructional strategy that can help students learn about current technologies and also provide them with tools for investigating emerging technologies as they are encountered.

Effects Of Epiphyte Load On Optical Properties And Photosynthetic Potential Of The Seagrasses Thalassia Testudinum Banks Ex König And Zostera Marina L, Lisa A. Drake, Fred C. Dobbs, Richard C. Zimmerman

OES Faculty Publications

The biomass and optical properties of seagrass leaf epiphytes were measured to evaluate their potential impact on the photosynthetic performance of the seagrasses Thalassia testudinum Banks ex König (turtlegrass) and Zostera marina L. (eelgrass). Turtlegrass was obtained from oligotrophic waters near Lee Stocking Island, Bahamas; eelgrass was collected from a eutrophic environment in Monterey Bay, California. Leaf–epiphyte loads were characterized visually and quantified using measurements of their phospholipid biomass. Light absorption and reflectance of the intact epiphyte layer were determined spectrophotometrically. Turtlegrass epiphytes from the oligotrophic site absorbed a maximum of 36% of incident light in peak chlorophyll absorption …

Anisotropy And Its Relation To Liquefaction Resistance Of Granular Material, Isao Ishibashi, Omer F. Capar

Civil & Environmental Engineering Faculty Publications

This research establishes quantitative relationships between soil's anisotropy and liquefaction resistance for granular materials. Uniform medium density (D_r = 50%) sand specimens were prepared using three different sample preparation techniques (air pluviated (AP), moist tamped (NIT), and moist vibrated (MV)) to create different initial soil fabrics. Undrained cyclic triaxial tests were then performed to determine the liquefaction resistance of each soil specimen. On the same specimens in the triaxial cell, vertical and horizontal compression wave velocities and vertical shear wave velocity (V_s) were measured using piezoelectric bender elements. Anisotropic (transversely isotropic) elastic constants of the soil specimens were …

New Evidence For Enhanced Ocean Primary Production Triggered By Tropical Cyclone, I. Lin, W. Timothy Liu, Chun-Chieh Wu, George T. F. Wong, Chuanmin Hu, Zhiqiang Chen, Wen-Der Liang, Yih Yang, Kon-Kee Liu

OES Faculty Publications

[1] New evidence based on recent satellite data is presented to provide a rare opportunity in quantifying the long-speculated contribution of tropical cyclones to enhance ocean primary production. In July 2000, moderate cyclone Kai-Tak passed over the South China Sea (SCS). During its short 3-day stay, Kai-Tak triggered an average 30-fold increase in surface chlorophyll-a concentration. The estimated carbon fixation resulting from this event alone is 0.8 Mt, or 2-4% of SCS's annual new production. Given an average of 14 cyclones passing over the SCS annually, we suggest the long-neglected contribution of tropical cyclones to SCS's annual new production may …

Sources Of Sediment Found In Sea Ice From The Western Arctic Ocean, New Insights Into Processes Of Entrainment And Drift Patterns, Dennis A. Darby

OES Faculty Publications

The geochemical fingerprint of entrained Fe oxide mineral grains in Arctic Ocean sea ice is used to determine precise sources of this sediment. This approach substantiates the importance of the Laptev Sea as a source of sea ice and even the presence of Russian ice in the Beaufort Sea off Alaska. Fe oxide grains from the Laptev Sea were found in floes in the Beaufort Sea, Chukchi Borderland, and central Arctic Ocean, demonstrating the importance of sea ice in distributing itself throughout the Arctic Ocean and the potential of transporting sediment from Russian rivers to North American shelves. Banks Island …

Extracellular Enzyme Activity And Uptake Of Carbon And Nitrogen Along An Estuarine Salinity And Nutrient Gradient, Margaret R. Mulholland, Cindy Lee, Patricia M. Gilbert

OES Faculty Publications

Amino acid oxidation (AAO) and peptide hydrolysis (PH) are processes affecting the recycling of organic material and nutrients. We compared extracellular AAO and PH rates to C and N uptake rates along estuarine gradients of salinity, nutrients and productivity in the Pocomoke River, a subestuary of the Chesapeake Bay. This estuary is seasonally depleted in inorganic N, and rich in dissolved organic material (DOM) throughout the year. AAO, PH, and N uptake rates measured in 1999 and 2000 were not limited to particular size fractions measured, or to auto- or heterotrophic groups of organisms. At a station near the turbidity …

The Role Of Physical, Chemical, And Microbial Heterogeneity On The Field-Scale Transport And Attachment Of Bacteria, Brian J. Mailloux, Mark E. Fuller, Tullis C. Onstott, James Hall, Hailiang Dong, Mary F. Deflaun, Sheryl H. Streger, Randi K. Rothmel, Maria Green, Donald J. P. Swift, Jon Radke

OES Faculty Publications

A field-scale bacterial transport experiment was conducted at the Narrow Channel Focus Area of the South Oyster field site located in Oyster, Virginia. The goal of the field experiment was to determine the relative influence of subsurface heterogeneity and microbial population parameters on flow direction, velocity, and attachment of bacteria at the field scale. The field results were compared with results from laboratory-scale column experiments to develop a method for predicting field-scale bacterial transport. The field site is a shallow, sandy, unconfined, aerobic aquifer that has been characterized by geophysical, sedimentological, and hydrogeological methods. Comamonas sp. strain DA001 and a …

Experimental Investigation Of Elemental Incorporation In The Otoliths Of Larval And Juvenile Fish: Implications For Use As Environmental Recorders, Gretchen Bath Martin

Biological Sciences Theses & Dissertations

Innovative techniques for discerning fish stocks, identifying nursery habitats, locating spawning sites, tracing larval transport pathways, and quantifying the degree of population connectivity are required to meet the goals of sustainable management of marine capture fisheries. One of the most promising techniques is the use of elemental signatures in fish otoliths (ear stones), which record valuable life history data and serve as the link between fish and their environment. To validate the assumption that otolith elemental composition is a function of water elemental concentrations, and to address the possible effects of external variables such as temperature and salinity, the composition …

New Approaches To Gortler And Tollmien-Schlichting Boundary-Layer Instabilities, Vijay Kalburgi

Mechanical & Aerospace Engineering Theses & Dissertations

A detailed understanding of the physical processes that lead to instability and transition in the external viscous boundary layers of airfoils has been the goal of researchers for decades. This study seeks to enhance our understanding of Gortler and Tollmien-Schlichting instabilities through a critical review of prior theoretical methodology and fundamental experiments, the development of dimensionally consistent disturbance equations, and novel interpretation of the resulting flow physics revealed by their solutions to explain the process of transition.

Gortler vortices arise in boundary layers along concave surfaces due to centrifugal effects and these vortices in combination with other instabilities play an …

United States Diplomacy In The Age Of The Internet, Allison S. Greene

Graduate Program in International Studies Theses & Dissertations

The dynamics of international relations are constantly changing, and the origin of an extraordinary amount of that change can be traced to what has been coined the ‘Information Revolution.’ It is a revolution as profound and as significant as Gutenberg's invention of moveable metal type, and may result in social and political consequences of comparable magnitude. One of the most significant and far-reaching implications of this phenomenon is the emergence of the Internet. Since its inception, there have been many claims and assertions about existing and potential repercussions of the Internet within the diplomatic realm.

The purpose of this work …

Report On The Third Acm/Ieee Joint Conference On Digital Libraries (Jcdl), Michael L. Nelson

Computer Science Faculty Publications

The Third ACM/IEEE Joint Conference on Digital Libraries (JCDL 2003) was held on the campus of Rice University in Houston, Texas, May 27 - 31. Regarding the merging of the ACM and IEEE conference series, in the JCDL 2002 conference report published last year in D-Lib Magazine Edie Rasmussen noted, "Perhaps by next year...no one will remember that it wasn't always so" [1]. Judging by the number of participants I met who did not know that the ACM and IEEE used to hold separate digital library conferences, Rasmussen's prediction has come to pass.

Study Of A Growth Instability Of Γ-In[Sub 2]Se[Sub 3], C. Amory, J. C. Bernede, S. Marsillac

Electrical & Computer Engineering Faculty Publications

γ-In[sub 2]Se[sub 3] thin film are deposited for various substrate temperatures in the range of 523–673 K. This study shows that at 573 and 673 K the thin films are well crystallized with grains aligned along the c axis. Between these temperatures, a domain of instability appears where the γ-In[sub 2]Se[sub 3] thin films have a randomly orientation and the c-lattice parameter increases. The presence of the metastable phase κ-In[sub 2]Se[sub 3], during the growth, can explain the existence of this domain of instability. The insertion of Zn during the preparation process allows us to stabilize the phase κ at …

Electron Bernstein Wave-X-O Mode Conversion And Electron Cyclotron Emission In Mast, Josef Preinhaelter, Pavol Pavlo, Vladimir Shevchenko, Martin Valovic, Linda L. Vahala, George Vahala

Electrical & Computer Engineering Faculty Publications

Electron cyclotron emission (ECE) from overdense plasmas can only occur due to electron Bernstein waves (EBW) mode converting near the upper hybrid region to an electromagnetic wave. Experimental data of ECE observations on MAST are studied and compared with EBW-X-O mode conversion modeling results.

Compact Supercell Method Based On Opposite Parity For Bragg Fibers, Wang Zhi, Ren Guobin, Lou Shuquin, Liang Weijun, Shangping Guo

Electrical & Computer Engineering Faculty Publications

The supercell- based orthonormal basis method is proposed to investigate the modal properties of the Bragg fibers. A square lattice is constructed by the whole Bragg fiber which is considered a supercell, and the periodical dielectric structure of the square lattice is decomposed using periodic functions (cosine). The modal electric field is expanded as the sum of the orthonormal set of Hermite-Gaussian basis functions based on the opposite parity of the transverse electric field. The propagation characteristics of Bragg fibers can be obtained after recasting the wave equation into an eigenvalue system. This method is implemented with very high efficiency …

Monte Carlo Analysis Of Gan-Based Gunn Oscillators For Microwave Power Generation, R. P. Joshi, V. Sridhara, P. Shah, R. D. Del Rosario

Electrical & Computer Engineering Faculty Publications

Monte Carlo studies of transferred electron oscillators based on bulk wurtzite GaN are presented. Two structures have been examined: (i) devices with the conventional single notch structure, and (ii) repetitive structures with serial segments to fashion a "multiple domain" device. Wurtzite material has been chosen because of the higher drift velocity and because analytical expressions for the band structure have recently become available. Performance parameters of interest such as the operating frequency, output power, and conversion efficiency are calculated. Variations due to changes in temperature, biasing voltage, and device length are also included. It is shown that multidomain Gunn diodes …

Simple Plane Wave Implementation For Photonic Crystal Calculations, Shangping Guo, Sacharia Albin

Electrical & Computer Engineering Faculty Publications

A simple implementation of plane wave method is presented for modeling photonic crystals with arbitrary shaped ‘atoms’. The Fourier transform for a single ‘atom’ is first calculated either by analytical Fourier transform or numerical FFT, then the shift property is used to obtain the Fourier transform for any arbitrary supercell consisting of a finite number of ‘atoms’. To ensure accurate results, generally, two iterating processes including the plane wave iteration and grid resolution iteration must converge. Analysis shows that using analytical Fourier transform when available can improve accuracy and avoid the grid resolution iteration. It converges to the accurate results …

Precision Measurement Of The Proton And Deuteron Spin Structure Functions G2 And Asymmetries A2, P. L. Anthony, R. G. Arnold, T. Averett, H. R. Band, N. Benmouna, W. Boeglin, H. Borel, P. E. Bosted, S. L. Bültmann, G. R. Court, C. E. Hyde-Wright, S. E. Kuhn, F. Sabatie, F. R. Wesselmann

Physics Faculty Publications

We have measured the spin struction functions g2(p) and g(2)(d) and the virtual photon asymmetries A(2)(p) and A(2)(d) over the kinetmatic range 0.02 less than or equal to x less than or equal to 0.8 and 0.7 less than or equal to Q² less than or equal to 20 GeV2 by scattering 29.1 and 32.3 GeV longitudinally polarized electrons from transversely polarized NH3 and (LiD)-Li-6 targets. Our measured g² approximately follows the twist-2 Wandzura-Wilczek calculation. The twist-3 reduced matrix elements d(2)(p) and d(2)(n) are less than two standard deviations from zero. The data are inconsistent with the Burkhardt-Cottingham …

Coulomb Sum Rule For ⁴He, J. Carlson, J. Jourdan, R. Schiavilla, I. Sick

Physics Faculty Publications

We determine the Coulomb sum for ⁴He using the world data on ⁴He(e,e′) and compare the results to calculations based on realistic interactions and including two-body components in the nuclear charge operator. We find good agreement between theory and experiment when using free-nucleon form factors. The apparent reduction of the in-medium G_Ep implied by IA-interpretation of the L/T-ratios measured in ⁴He(e,e′p) and ⁴He(e→,e′p→) is not confirmed.

Shock Wave Dispersion In Weakly Ionized Gas, Prasong Kessaratikoon

Physics Theses & Dissertations

Electrodeless microwave (MW) discharge in two straight, circular cylindrical resonant cavities in TE_1,1,1 and TM_0,1,2 modes were introduced to perform additional experimental studies on shock wave modification in non-equilibrium weakly ionized gases and to clarify the physical mechanisms of the shock wave modification process. The discharge was generated in 99.99% Ar at a gas pressure between 20 and 100 Torr and at a discharge power density less than 10.0 Watts/cm³. Power density used for operating the discharge was rather low in the present work, which was determined by evaluating the power loss inside the resonant cavity. …

Optimal Feedback Control For Ship Roll Motion Under Sea States, Anusit Anmanatarkul

Mechanical & Aerospace Engineering Theses & Dissertations

The primary influences of ship motion are roll motion. The purpose of this dissertation is to discuss a means to reduce the roll amplitude of ship motion in the case of zero forward speed using the roll mitigation device known as the flume tank, or U-tube, tank. Passive control and active control are studied. Optimal feedback control is the designated algorithm for activated roll mitigation device. The assumed model in this study is a submarine chaser. The linear coupled equation of swaying, rolling, and yawing motion of this assumed model is studied. The roll motion of this vessel is investigated …

Generalized Predictive Control Of Ship Coupling Motions Using Active Flume Tanks, Abdulkarim Mohammed Alotaiwi

Mechanical & Aerospace Engineering Theses & Dissertations

This dissertation uses the Generalized Predictive Control (GPC) approach to design a control system for a ship rolling motion coupled with the sway and yaw using an activated flume tank. GPC is a strategy based on system output prediction over finite horizon known as the prediction horizon. GPC controller is designed from the coefficients of the Autoregressive model with exogenous input (ARX) that are computed directly from input and output data. It computes the future control input based on the cost function with weighted input and output. System identification approach is implemented on the system to find the ARX coefficients …

A Relationship Between Grades Earned By Sixth Grade Core Science Students And Their End Of Year Grades, Denise Wilda Padrick

OTS Master's Level Projects & Papers

To solve this problem, the following hypothesis was tested: 1. A relationship does not exist between sixth grade level academic grades earned at the end of a first nine weeks grading period and the year end grades.

The Relationship Between Afloat Training Group Norfolk Levels Of Effectiveness To Formal Assessment/Inspections As A Predictor Of Atlantic Fleet Shipboard Engineering Readiness, Juan D. Marpuri Jr.

OTS Master's Level Projects & Papers

This research will determine if the changes made as a result of IDTC initiatives have contributed to the levels of training effectiveness and ultimately the afloat commands ability to demonstrate engineering readiness.

Effects Of Enhanced Evaluative Feedback On Student Grades, Roney A. Mcdaniel

OTS Master's Level Projects & Papers

The following hypothesis was developed to guide this study: 1. Students in the OTS 110T, Technology in Your World, class at Old Dominion University that receive enhanced evaluative feedback will earn higher grades than those students receiving normal feedback.

Parents' Definition Of Technological Literacy And Their Perceived Attitudes Toward Technological Literacy, Charles L. Thomas

OTS Master's Level Projects & Papers

The research objectives used to guide this problem were: 1. Determine parents understanding of technology 2. Determine parents' attitude towards the effect of technology on society 3. Determine the parents attitude toward technological literacy and the school curriculum.

The Attitudes Of Core Subject Teachers Toward Making Technology Education A Required Subject, Michael C. Hamby

OTS Master's Level Projects & Papers

The goals of this study were to: 1. Ascertain the definition and scope of Technology Education from the perspective of core subject teachers; 2. Gather core subject teachers' opinions concerning the ability of Technology Education to reinforce learning in their content areas; 3. Determine if Technology Education should be a core or required subject.

A Study To Determine The Relationship Between Parent's Work And Their Concern For Their Children Becoming Technologically Literate, Gerald T. Hoover

OTS Master's Level Projects & Papers

This study was used to gain an understanding of parent's concern for their children's technological literacy. The questions established for this research were: 1. Are parents who work in technical fields more concerned about their children's technological literacy than parents who work in non-technical fields? 2. Do parents who work in technical fields have a better understanding of what technology is over parents working in non-technical fields?

Development Of An Aggregation Methodology For Risk Analysis In Aerospace Conceptual Vehicle Design, Trina Marsh Chytka

Engineering Management & Systems Engineering Theses & Dissertations

The growing complexity of technical systems has emphasized a need to gather as much information as possible regarding specific systems of interest in order to make robust, sound decisions about their design and deployment. Acquiring as much data as possible requires the use of empirical statistics, historical information and expert opinion. In much of the aerospace conceptual design environment, the lack of historical information and infeasibility of gathering empirical data relegates the data collection to expert opinion.

The conceptual design of a space vehicle requires input from several disciplines (weights and sizing, operations, trajectory, etc.). In this multidisciplinary environment, the …