Digital Commons Network^™

A Comparison Between The Success Of Technological Literacy Programs At Landstown High School And Academy And Chantilly Academy, Vanessa Barger

OTS Master's Level Projects & Papers

This research project sought to determine answers for each of the following research objectives: Discover the difference in curriculum offering between the two schools; Find the total enrollment numbers for both schools for courses offered; Find the program completion totals for each school per year; and Summarize the factors necessary for the creation of superior technological literacy programs for high school students.

The Effectiveness Of Employing Content Area Writing Strategies On Student Knowledge And Concept Retention As Measured By Performance On An Examination Based On The Comptia A+ Certification Objectives, Timothy A. Mcleod

OTS Master's Level Projects & Papers

To guide this study, the following hypotheses were established: 1. The employment of content area writing exercises in the Information Technologies Pathways course will result in increased retention of basic computer knowledge and concepts; 2. The employment of content area writing exercises in the Information Technologies Pathways course will result in an increased percentage of students achieving passing scores on the CompTIA A+ Certification practice examination.

Analysis Of Determinants In Neighborhood Satisfaction Between Defended And Defensible Communities Within The General And Urban Housing Environments, David William Chapman

School of Public Service Theses & Dissertations

The purpose of this study is to provide a detailed examination and analysis of neighborhood satisfaction determinants among residents living within defended and defensible gated communities in the United States. The study considers whether there are significant differences in the determinants at national or regional levels and whether there are significant differences within the components of individual household characteristics, neighborhood quality characteristics, or both.

The theoretical framework and model for neighborhood satisfaction used with this study is based on a modified model of Lu's work on neighborhood satisfaction (1999, pp. 78-79) and residential mobility (1996) that were based on Speare's …

Investigation Of A Possible Lead-Lag Relationship Between The Innuitian And Laurentide Ice Sheets, Arctic Canada, Paula Zimmerman

OES Theses and Dissertations

Peaks of iron-rich grains in Arctic Ocean sediment cores matched to the Laurentide and Innuitian Ice Sheets appear to show a lead-lag relationship during the Late Pleistocene when grain abundances are plotted against time and depth below sea floor. Cores from across the Arctic have been analyzed to determine if this is the case. Of the six IRD events identified, the Innuitian leads 68% of the time with 26% of events in all cores occurring simultaneously. The Innuitian seems to lead 33.3% of the time when peaks from the Innuitian and Laurentide occur within close proximity (less than 1 cm), …

Development Of A Coupled Fluid/Structure Aeroelastic Solver With Applications To Vortex Breakdown-Induced Twin Tail Buffeting, Steven J. Massey

Mechanical & Aerospace Engineering Theses & Dissertations

Simulation of tail buffet is studied for several delta wing-vertical tail configurations. Flow conditions are chosen such that the wing primary-vortex cores experience vortex breakdown and the resulting turbulent wake flow impinges on the vertical tail. The dimensions and material properties of the vertical tails are chosen such that the deflections are large enough to insure interaction with the flow, and the natural frequencies are high enough to facilitate a practical computational solution. This multi-disciplinary problem is solved sequentially for the fluid flow, the elastic deformations and the grid displacements. The flow is simulated by time accurately solving the laminar, …

Sonic Boom Focusing Prediction And Delta Wing Shape Optimization For Boom Mitigation Studies, Nitin Khasdeo

Mechanical & Aerospace Engineering Theses & Dissertations

Supersonic travel over land would be a reality if new aircraft are designed such that they produce quieter ground sonic booms, no louder than 0.3 psf according to the FAA requirement. An attempt is made to address the challenging goal of predicting the sonic boom focusing effects and mitigate the sonic boom ground over pressure for delta wing geometry.

Sonic boom focusing is fundamentally a nonlinear phenomenon and can be predicted by numerically solving the nonlinear Tricomi equation. The conservative time domain scheme is developed to carry out the sonic boom focusing or super boom studies. The computational scheme is …

Stochastic Models For Enhancing Agility Of Supply Chains, Alok K. Verma

Engineering Technology Faculty Publications

This paper deals with the application of stochastic inventory model to the three-tier supply chain and verifying the values obtained by mathematical model with discrete event simulation. We investigate three-stage serial supply chain with stochastic demand and fixed replenishment lead-time. Inventory holding costs are charged at each stage, and each stage may incur a consumer backorder penalty cost charged by primary supplier to secondary supplier. The customer-demand follows Poisson distribution. We implement Base Stock model for inventory control at both suppliers. Computer simulation is then designed in such a way that it satisfied all the assumptions for mathematical model. Simulation …

Application Of Maldis-Ms To Identification Of Phytoplankton In Ballast Water, Dana Woodruff, Karen L. Wahl, Nancy B. Valentine, Fred Dobbs

OES Faculty Publications

Non-native invasive species are increasingly evident in marine and estuarine environments, largely because of the intake and release of ballast water from sea vessels. Innovative methods are needed to quickly and accurately detect and speciate non-native and/or harmful phytoplankton in ballast water. Recent advances in ionization techniques such as matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) have allowed detection of intact biomolecules within ballast samples. Statistically-based algorithms are used to discern "fingerprints" of phytoplankton species and to discern individual species from mixtures. MALDI-MS is particularly attractive for field applications because of the speed of analysis, minimal liquids/consumables required, and femtomole (10-15) …

Grazing Impacts Of Diverse Zooplankton Taxa On Thin Layers, Alexander Bochdansky

OES Faculty Publications

The US Navy needs to know how distributions and abundances of light-scattering and sound-scattering organisms in the ocean vary in space and time, particularly in the vertical dimension. Recent field observations have shown that many biological properties may vary substantially over small e.g. centimeter scales, commonly referred to as thin layers e.g. Cowles et al. 1998, 1999, Hanson Donaghay 1998, Holliday et al. 1999, Dekshenieks et al. 2001, Alldredge et al. 2002, Rines et al. 2002. Our previous ONR-funded research has allowed us to begin to understand how zooplankton interact with thin layers and how they can take advantage of …

The Fate Of Nitrogren Fixed By Diazotrophs In The Ocean, Margaret R. Mulholland

OES Faculty Publications

While we now know that N₂ fixation is a significant source of new nitrogen (N) in the marine environment, little is known about the fate of this N (and associated C), despite the importance of diazotrophs to global carbon and nutrient cycles. Specifically, does N fixed during N₂ fixation fuel autotrophic or heterotrophic growth and thus facilitate carbon (C) export from the euphotic zone, or does it contribute primarily to bacterial productivity and respiration in the euphotic zone? For Trichodesmium, the diazotroph we know the most about, the transfer of recently fixed N₂ (and C) appears …

Impact Of Anthropogenic Combustion Emissions On The Fractional Solubility Of Aeroosol Iron: Evidence From The Sargasso Sea, Peter N. Sedwick, Edward R. Sholkovitz, Thomas M. Church

OES Faculty Publications

We report empirical estimates of the fractional solubility of aerosol iron over the Sargasso Sea during periods characterized by high concentrations of Saharan dust (summer 2003) and by low concentrations of aerosols in North American/maritime North Atlantic air masses (spring 2004 and early summer 2004). We observed a strong inverse relationship between the operational solubility of aerosol iron (defined using a flow-through deionized-water leaching protocol) and the total concentration of aerosol iron, whereby the operational solubility of aerosol iron was elevated when total aerosol iron loadings were low. This relationship is consistent with source-dependent differences in the solubility characteristics of …

Response Of Eelgrass Zostera Marina To Co2 Enrichment: Possible Impacts Of Climate Change And Potential For Remediation Of Coastal Habitats, Sherry L. Palacios, Richard C. Zimmerman

OES Faculty Publications

Projected increases in dissolved aqueous concentrations of carbon dioxide [CO_2(aq)] may have significant impacts on photosynthesis Of CO₂-limited organisms such as seagrasses. Short-term CO_2(aq) enrichment increases photosynthetic rates and reduces light requirements for growth and survival of individual eelgrass Zostera marina L. shoots growing in the laboratory under artificial light regimes for at least 45 d. This study examined the effects of long-term CO_2(aq) enrichment on the performance of eelgrass growing under natural light-replete (33% surface irradiance) and light-limited (5% surface irradiance) conditions for a period of 1 yr. Eelgrass shoots were grown at …

Simulations Of Phytoplankton Species And Carbon Production In The Equatorial Pacific Ocean 1. Model Configuration And Ecosystem Dynamics, Baris Salihoglu, Eileen E. Hofmann

OES Faculty Publications

The primary objective of this research is to investigate phytoplankton community response to variations in physical forcing and biological processes in the Cold Tongue region of the equatorial Pacific Ocean at 0N, 140W. This research objective was addressed using a one-dimensional multicomponent lower trophic level ecosystem model that includes detailed algal physiology, such as spectrally-dependent photosynthetic processes and iron limitation on algal growth. The ecosystem model is forced by a one-year (1992) time series of spectrally-dependent light, temperature, and water column mixing obtained from a Tropical Atmosphere-Ocean (TAO) Array mooring. Autotrophic growth is represented by five algal groups, which have …

Otolith Chemistry Reflects Frontal Systems In The Antarctic Circumpolar Current, J. R. Ashford, A. I. Arkhipkin, C. M. Jones

OES Faculty Publications

Pronounced environmental trends across fronts suggest that the otolith chemistry of oceanic fish can resolve zones on either side, promoting application to population questions at similar spatial scales. Trace and minor elements laid down immediately prior to capture - along the edges of otoliths from Patagonian toothfish Dissostichus eleginoides - discriminated frontal zones in the Antarctic Circumpolar Current in the Southwestern Atlantic Ocean. Mean values differentiated sampling areas by up to 2.6 standard deviations, suggesting: (1) otolith Mg/Ca enrichment related to fish activity around the Burdwood Bank; (2) Mn/Ca enrichment associated with South America; (3) Sr/Ca linked to the presence …

Co2 Control Of Trichodesmium N-2 Fixation, Photosynthesis, Growth Rates, And Elemental Ratios: Implications For Past, Present, And Future Ocean Biogeochemistry, D. A. Hutchins, F.-X. Fu, Y. Zhang, M. E. Warner, Y. Feng, K. Portune, P. W. Bernhardt, M. R. Mulholland

OES Faculty Publications

Diazotrophic marine cyanobacteria in the genus Trichodesmium contribute a large fraction of the new nitrogen entering the oligotrophic oceans, but little is known about how they respond to shifts in global change variables such as carbon dioxide (CO₂) and temperature. We compared Trichodesmium dinitrogen (N₂) and CO₂ fixation rates during steady-state growth under past, current, and future CO₂ scenarios, and at two relevant temperatures. At projected CO₂ levels of year 2100 (76 Pa, 750 ppm), N₂ fixation rates of Pacific and Atlantic isolates increased 35-100%, and CO₂ fixation rates increased 15-128% …

Light Environment And Seasonal Dynamics Of Microalgae In The Annual Sea Ice At Terra Nova Bay, Ross Sea, Antarctica, L. Lazzara, I. Nardello, C. Ermanni, O. Mangoni, V. Saggiomo

OES Faculty Publications

We investigated the physical conditions of the Spring pack ice environment at Terra Nova Bay to understand their influence on the structure and physiology of sympagic microalgae. Bio-optical methods were used to study the availability and spectral quality of solar radiation, both inside and underneath the ice cover. Pack ice thickness was around 2.5 m, with a temperature between -2 and -7°C. On average, only 1.4% of surface PAR penetrated to the bottom ice and less than 0.6% below platelet ice level. Surface UV-B radiation under the bottom ice was 0.2-0.4%. Biomass concentrations up to 2400 mg Chl a m- …

An Evaluation Of Supercritical Drying And Peg/Freeze Drying Of Waterlogged Archaeological Wood, Eric Schindelholz, Robert Blanchette, Desmond C. Cook, Michael Drews, Steve Hand, Benjamin Held, Joel Jurgens, Betty Seifert

Physics Faculty Publications

This study was undertaken to evaluate the physical effects of drying waterlogged archaeological wood using supercritical carbon dioxide as compared to air drying and the popular polyethylene glycol (PEG)/freeze drying method. Previous studies have shown supercritical drying to be a potentially advantageous alternative to current methods of drying waterlogged wood through reduced processing time, minimal shrinkage, and increased success for reversibility. Samples in the form of blocks and planks of a few centimeters in size were prepared from two archaeological waterlogged wood sources and grouped into three treatment sets: one for air drying, one for PEG/freeze drying, and the other …

Tio2 Breakdown Under Pulsed Conditions, G. Zhao, R. P. Joshi, V. K. Lakdawala, E. Schamiloglu, H. Hjalmarson

Electrical & Computer Engineering Faculty Publications

Model studies of current conduction and breakdown in TiO₂ were carried out. Our simulation results indicate that electrical breakdown of TiO₂ under multiple-pulsed conditions can occur at lower voltages as compared to quasi-dc biasing. This is in agreement with recent experimental data and is indicative of a cumulative phenomena. We demonstrate that the lower breakdown voltages observed in TiO₂ under pulsed conditions is a direct rise-time effect, coupled with successive detrapping at the grain boundaries. 2007 American Institute of Physics.

Exploration Of Computational Methods For Classification Of Movement Intention During Human Voluntary Movement From Single Trial Eeg, Ou Bai, Peter Lin, Sherry Vorbach, Jiang Li, Steve Furlani, Mark Hallett

Electrical & Computer Engineering Faculty Publications

Objective: To explore effective combinations of computational methods for the prediction of movement intention preceding the production of self-paced right and left hand movements from single trial scalp electroencephalogram (EEG).

Methods: Twelve naïve subjects performed self-paced movements consisting of three key strokes with either hand. EEG was recorded from 128 channels. The exploration was performed offline on single trial EEG data. We proposed that a successful computational procedure for classification would consist of spatial filtering, temporal filtering, feature selection, and pattern classification. A systematic investigation was performed with combinations of spatial filtering using principal component analysis (PCA), independent component analysis …

Using Pareto Fronts To Evaluate Polyp Detection Algorithms For Ct Colonography, Adam Huang, Jiang Li, Ronald M. Summers, Nicholas Petrick, Amy K. Hara

Electrical & Computer Engineering Faculty Publications

We evaluate and improve an existing curvature-based region growing algorithm for colonic polyp detection for our CT colonography (CTC) computer-aided detection (CAD) system by using Pareto fronts. The performance of a polyp detection algorithm involves two conflicting objectives, minimizing both false negative (FN) and false positive (FP) detection rates. This problem does not produce a single optimal solution but a set of solutions known as a Pareto front. Any solution in a Pareto front can only outperform other solutions in one of the two competing objectives. Using evolutionary algorithms to find the Pareto fronts for multi-objective optimization problems has been …

Validating Pareto Optimal Operation Parameters Of Polyp Detection Algorithms For Ct Colonography, Jiang Li, Adam Huang, Nicholas Petrick, Jianhua Yao, Ronald M. Summers, Maryellen L. Giger (Ed.), Nico Karssemeijer (Ed.)

Electrical & Computer Engineering Faculty Publications

We evaluated a Pareto front-based multi-objective evolutionary algorithm for optimizing our CT colonography (CTC) computer-aided detection (CAD) system. The system identifies colonic polyps based on curvature and volumetric based features, where a set of thresholds for these features was optimized by the evolutionary algorithm. We utilized a two-fold cross-validation (CV) method to test if the optimized thresholds can be generalized to new data sets. We performed the CV method on 133 patients; each patient had a prone and a supine scan. There were 103 colonoscopically confirmed polyps resulting in 188 positive detections in CTC reading from either the prone or …

Formation Of In- (2×1) And In Islands On Si (100) - (2×1) By Femtosecond Pulsed Laser Deposition, M. A. Hafez, H. E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

The growth of indium on a vicinal Si (100) - (2×1) surface at room temperature by femtosecond pulsed laser deposition (fsPLD) was investigated by in situ reflection high-energy electron diffraction (RHEED). Recovery of the RHEED intensity was observed between laser pulses and when the growth was terminated. The surface diffusion coefficient of deposited In on initial two-dimensional (2D) In- (2×1) layer was determined. As growth proceeds, three-dimensional In islands grew on the 2D In- (2×1) layer. The RHEED specular profile was analyzed during film growth, while the grown In islands were examined by ex situ atomic force microscopy. The full …

Entopic Lattice Boltzmann Representations Required To Recover Navier Stokes Flows, Brian Keating, George Vahala, Jeffrey Yepez, Min Soe, Linda L. Vahala

Electrical & Computer Engineering Faculty Publications

There are two disparate formulations of the entropic lattice Boltzmann scheme: one of these theories revolves around the analog of the discrete Boltzmann H function of standard extensive statistical mechanics, while the other revolves around the nonextensive Tsallis entropy. It is shown here that it is the nonenforcement of the pressure tensor moment constraints that lead to extremizations of entropy resulting in Tsallis-like forms. However, with the imposition of the pressure tensor moment constraint, as is fundamentally necessary for the recovery of the Navier-Stokes equations, it is proved that the entropy function must be of the discrete Boltzmann form. Three-dimensional …

Gis-Based Integration Of Swat And Remm For Estimating Water Quality Benefits Of Riparian Buffers In Agricultural Watersheds, Y. Liu, Wanhong Yang, Xixi Wang

Civil & Environmental Engineering Faculty Publications

The Soil and Water Assessment Tool (SWAT) is a process-based, watershed-scale model with a hydrologic response unit (HRU) as the basic computation element, which makes it difficult to accurately represent riparian buffers using their physical parameters (e.g., vegetation structure). On the other hand, the field-scale Riparian Ecosystem Management Model (REMM) provides the opportunity to consider details of hydrologic processes within a riparian buffer zone. However, the runoff and its associated constituents from the upland area that is hydraulically connected to the riparian buffer zone must be provided as inputs into REMM. The rationale proposed here is that the integration of …

Scaling Tests Of The Cross Section For Deeply Virtual Compton Scattering, C. Muñpz Camacho, A. Camsonne, M. Mazouz, C. Ferdi, G. Gavalian, E. Kuchina, M. Amaryan, K. A. Aniol, M. Beaumel, H. Benaoum, D. Hayes, C. E. Hyde-Wright, H. Ibrahim, P. E. Ulmer, L. B. Weinstein

Physics Faculty Publications

We present the first measurements of the ep → epγ cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region. The Q² dependence (from 1.5 to 2.3 GeV²) of the helicity-dependent cross section indicates the twist-2 dominance of DVCS, proving that generalized parton distributions (GPDs) are accessible to experiment at moderate Q². The helicity-independent cross section is also measured at Q²=2.3 GeV². We present the first model-independent measurement of linear combinations of GPDs and GPD integrals up to the twist-3 approximation.

A Simplified Model For Growth Factor Induced Healing Of Wounds, F. J. Vermolen, E. Van Baaren, J. A. Adam

Mathematics & Statistics Faculty Publications

A mathematical model is developed for the rate of healing of a circular or elliptic wound. In this paper the regeneration, decay and transport of a generic 'growth factor', which induces the healing of the wound, is taken into account. Further, an equation of motion is derived for radial healing of a circular wound. The expressions for the equation of motion and the distribution of the growth factor are related in such a way that no healing occurs if the growth factor concentration at the wound edge is below a threshold value. In this paper we investigate the influence of …

Why I Blog: Part 1, Michael Benton (Compiler)

Reconstruction: Studies in Contemporary Culture

No abstract provided.

A Study Correlating Entropy Generation To Parameters Characterizing Thermal Comfort In A Conditioned Room, Sai Shrinivas Sreedharan

Mechanical & Aerospace Engineering Theses & Dissertations

Although significant advances have been made to analyze and study a room as an open thermodynamic system experiencing indoor airflow and heat exchanges with surroundings, studies incorporating entropy generation in the analysis have been sparse. This study focuses on correlating indoor thermal comfort with entropy generation, which hopefully will result in efficient utilization of energy supplied to the system. The problem that this thesis attempts to solve involves calculation of entropy production in conditioned space and its correlation to parameters that characterize thermal comfort. Thermal comfort in a conditioned space is governed by many thermal, mechanical and psychrometric parameters. The …

2004 Jeffress Research Grant Awards

Virginia Journal of Science

List of winners of the 2004 Jeffress Research Grant Awards.

Minutes: Council Meeting

Virginia Journal of Science

Minutes of the VAS Council meeting Friday May 26, 2006, 8 - 9:40 AM, at Skelton Conference Center Inn, Virginia Tech, Blacksburg VA. Minutes were edited for publication.