Physical Sciences and Mathematics Commons^™

Applications Of Operations Research In Domestic Electric Utilities, Jametta Myers

Theses and Dissertations

Since its inception in the 1950s, operations research has been used in a number of industries, including the energy industry. Documentation of its use in exploration, production, gasoline blending, oil spill management, coal mining, coal handling, and coal mixing is extensive. However, considerably less documented research exists for one significant customer of many of these products: the electric utility. This work reviews refereed literature from United States operations research journals that document the use of operations research in United States electric utility operations. Applications that centered specifically on the areas of thermal energy generation, transmission, distribution, capacity planning, electric power …

Energy Efficient Embedded System Design For Medical Care System Using Wireless Sensor Network, Qi Li

Theses and Dissertations

Recent surveys on medical service systems show that the cost of patient monitoring has grown significantly. The widespread use of portable digital medical device makes it possible to provide a more comprehensive tracking of patient conditions. However, the development of a full scale, distributed health monitoring system is much delayed due to the lack of efficient wireless communication in a large distributed network. This becomes a challenging research topic which is to find a way to provide accurate and real time patient information to medical experts in a fast, efficient and cost effective fashion. This paper proposes a novel solution …

Wireless Intelligent Structural Health Monitoring System, Belle Ashwin

Theses and Dissertations

Metal structures are susceptible to various types of damages, including corrosion, stress damage, pillowing deformation, cracks etc. These kinds of damages in the metal structures occur mainly due to operational conditions and exposure to the environment. Our research involves a portable integrated wireless sensor system with video camera and ultrasound capabilities which is being developed to investigate corrosion damage on real structures in real time. This system uses images of the metal surfaces, which are captured from an integrated wireless sensor and then quantified and analyzed using computational intelligence. The quantification of the obtained images is done with specialized component …

Performance Analysis Of A Light Weight Packet Scanner, Paras Gandhi

Theses and Dissertations

The growth of networks around the world has also given rise to threats like viruses and Trojans. This rise in threats has resulted in counter measures for these threats. These counter measures are in the form of applications called firewalls or IDS. The incorporation of these applications in the network results in some delay in communications. The aim of the experiment in this thesis is to measure the delay introduced by such a firewall in the best case and compare it with the communication done on a network without such an application. These experiments are done using a special miniature …

Tolerance Intervals In Random-Effects Models, Kakotan Sanogo

Theses and Dissertations

In the pharmaceutical setting, it is often necessary to establish the shelf life of a drug product and sometimes suitable to assess the risk of product failure at the desired expiry period. The current statistical methodology use confidence intervals for the predicted mean to establish the expiry period and prediction intervals for a predicted new assay value or a tolerance interval for a proportion of the population for use in a risk assessment. A major concern is that most methodology treat a homogeneous subpopulation, say batch, either as a fixed effect and therefore uses a fixed-effects regression model (Graybill, 1976) …

Computer-Aided Trauma Decision Making Using Machine Learning And Signal Processing, Soo-Yeon Ji

Theses and Dissertations

Over the last 20 years, much work has focused on computer-aided clinical decision support systems due to a rapid increase in the need for management and processing of medical knowledge. Among all fields of medicine, trauma care has the highest need for proper information management due to the high prevalence of complex, life-threatening injuries. In particular, hemorrhage, which is encountered in most traumatic injuries, is a dominant factor in determining survival in both civilian and military settings. This complication can be better managed using a more in-depth analysis of patient information. Trauma physicians must make precise and rapid decisions, while …

Applications Of The Bivariate Gamma Distribution In Nutritional Epidemiology And Medical Physics, Jolene Barker

Theses and Dissertations

In this thesis the utility of a bivariate gamma distribution is explored. In the field of nutritional epidemiology a nutrition density transformation is used to reduce collinearity. This phenomenon will be shown to result due to the independent variables following a bivariate gamma model. In the field of radiation oncology paired comparison of variances is often performed. The bivariate gamma model is also appropriate for fitting correlated variances. A method for simulating bivariate gamma random variables is presented. This method is used to generate data from several bivariate gamma models and the asymptotic properties of a test statistic, suggested for …

Variable Selection In Competing Risks Using The L1-Penalized Cox Model, Xiangrong Kong

Theses and Dissertations

One situation in survival analysis is that the failure of an individual can happen because of one of multiple distinct causes. Survival data generated in this scenario are commonly referred to as competing risks data. One of the major tasks, when examining survival data, is to assess the dependence of survival time on explanatory variables. In competing risks, as with ordinary univariate survival data, there may be explanatory variables associated with the risks raised from the different causes being studied. The same variable might have different degrees of influence on the risks due to different causes. Given a set of …

Using Simulation Optimization To Construct Efficient Screening Strategies For Cervical Cancer, Christodoulos Foufoulides

Theses and Dissertations

Cervical cancer is the second most common type of cancer in women worldwide. Because cervical cancer is usually asymptomatic until the disease is in its advanced stages, cervical screening is of central importance towards combating cervical cancer. Alternative screening strategies are evaluated from an economic point of view through cost-effectiveness analysis. In the literature however, studies perform cost-effectiveness analysis on a limited number of de facto or predetermined screening policies. At present, no attempt has been made to construct efficient screening strategies through optimization, before cost-effectiveness analysis is applied. In this study simulation optimization is used to construct efficient screening …

Generalized Second Price Auctions With Hierarchical Bidding, Kevin Bryan

Theses and Dissertations

The sale of text advertisements on search engines using an auction format called Generalized Second Price (GSP) has become increasingly common. GSP is unique in that it allows bidders to revise their bid if they are unhappy with the result of the auction, and because the auction sells multiple units of a related good simultaneously. We model this sale as a hierarchical game with complete information, allowing one potential bidder to bid in each stage. The hierarchical game has an entirely different set of equilibria from the simultaneous bid game studied in earlier research on this auction. Under hierarchical bidding, …

Mechanistic Studies On The Electrochemistry Of Glutathione And Homocysteine, Olufemi Oyesanya

Theses and Dissertations

This research work has investigated the electrochemistry of glutathione (GSH)and homocysteine (HCSH) in order to develop sensors for these biological thiols.Ru(bpy)₃³⁺ and IrCl₆²⁻ have been used as mediators for the electrooxidation of GSH andHCSH because direct oxidation of these thiols is slow at most conventional electrodes.The electrochemical detection of GSH and HCSH has been pursued because of their biological roles.

Concerted proton electron transfer (CPET) and stepwise proton electron transfer(PT/ET) pathways have been observed in the electrooxidation of GSH and HCSH.Oxidation of GSH by Ru(bpy)₃³⁺ carried out in deuterated and undeuterated buffered (pH= pD …

Magnetic Properties Of La 0.6 Sr 0.4 Mno 3 Thin Films On Srtio 3 And Buffered Si Substrates With Varying Thickness, A. K. Pradhan, D. Hunter, T. Williams, B. Lasley-Hunter, R. Bah, H. Mustafa, R. Rakhimov, J. Zhang, D. J. Sellmyer, E. E. Carpenter, D. R. Sahu, J. -L. Huang

Chemistry Publications

La0.60Sr0.40MnO3 (LSMO) thin films of varying thickness from 12 to 55 nm were deposited using the pulsed-laser deposition technique onto single-crystalline SrTiO3 (STO) and STO-buffered Si substrates. The Tc of LSMO filmsgrown on STO-buffered Si substrates decreases faster than films directly grown on STO with decreasing film thickness. The LSMO/STO film with thickness of 55 nm shows Tc at about 360 K, which is close to the bulk value, whereas TcLSMO film on STO-buffered Si film of similar thickness is reduced to 320 K. This difference is attributed to the strain and interfacial disorders in LSMO film on STO/Si. The …

Transverse Susceptibility Study Of The Effect Of Varying Dipolar Interactions On Anisotropy Peaks In A Three-Dimensional Assembly Of Soft Ferrite Nanoparticles, Pankaj Poddar, Marienette B. Morales, Natalie A. Frey, Shannon A. Morrison, Everett E. Carpenter, Hariharan Srikanth

Chemistry Publications

Collective magnetization dynamics in nanoparticle assemblies is of current interest as it forms the basis of high density storage media. It is important to understand how interparticle interactions in a three-dimensional (3D) arrangement of superparamagnetic nanoparticles would affect the overall effective magnetic anisotropy of the system. We have studied the influence of varying strengths of dipolar interaction on the static and dynamic magnetic properties of surfactant-coated monodispersed manganese zinc ferrite nanoparticles using reversible transverse susceptibility. We track the evolution of the anisotropy peaks with varying magnetic field, temperature, and interaction strength. The blocking temperature shows an increase from 28 to …

Meteorology And Cimatology: On-Line Weather Studies, J. A. Mulvany, M. Bentley, E. Pyle

Journal of Mathematics and Science: Collaborative Explorations

Through the Virginia Earth Science Collaborative (VESC), a partnership of nine institutes of higher education, non-profit organizations, and eighty-three school divisions, a 3-credit, graduate-level meteorology course was offered six times between Spring 2006 and Fall 2007. The course, entitled Meteorology, was offered at three locations (Richmond, Abingdon, and Harrisonburg), and a local instructor facilitated each section. Funding for the course development, instructor stipends, and participant expenses (including travel, meals, and tuition) was provided through a competitive Mathematics and Science Partnership (MSP) grant funded through the federal No Child Left Behind legislation of 2001. The framework of the course was the …

Poly(D,L-Lactide-Co-Glycolide) Microcomposite Containing Magnetic Iron Core Nanoparticles As A Drug Carrier, Sweta Naik, Everett E. Carpenter

Chemistry Publications

Today many potent anticancer drugs like cisplatin are available which carry a number of side effects. A promising way of reducing the side effects is to target the drug to tissue sites by coating it with biocompatible materials like Poly (dl-lactide-co-glycolide) (PLGA) polymer where controlled drug release is achieved during the biodegradation of the polymer. Also the efficacy of anticancer drugs like cisplatin increases at elevated temperatures, so if local heating can be achieved where the drug is targeted. Local heating can be achieved by introducing iron core nanoparticles in the composites along with the drug, which can be heated …

First-Principles Study Of Interaction Of Molecular Hydrogen With Li-Doped Carbon Nanotube Peapod Structures, Li Chen, Yiming Zhang, Nikhil Koratkar, Puru Jena, Saroj K. Nayak

Physics Publications

Using first-principles density functional theory based on gradient corrected approach, we have studied interaction of H2 molecule with Li-doped carbon nanotube and nanotube based peapod structures. We find that H2 physisorbs on pure carbon nanotube, which is in agreement with earlier studies, and this binding increases when H2 binds to Li-decorated on carbon nanotube surfaces: the binding is further enhanced with Li atoms deposited on C60 doped nanotube peapod structures. The increase in binding in the latter structures arises due to charge transfer between the nanotube and C60, which further facilitates charge transfer from Li to the nanotube. Encapsulating fullerene …

Li- And B-Decorated Cis-Polyacetylene: A Computational Study, S. Li, Puru Jena

Physics Publications

By using density functional theory and the generalized gradient approximation, we show that Li-decorated cis-polyacetylene meets some of the requirements of an ideal hydrogen storage material. Unlike Ti-doped cis-polyacetylene, Li resists clustering and can reversibly store up to 10.8 wt %hydrogen in molecular form. However, molecular dynamics simulations show that Li can retain hydrogen only at cryogenic temperatures. On the other hand, B-doped cis-polyacetylene can store up to 7.5 wt % hydrogen, but it binds to hydrogen too strongly to be suitable for room temperature applications. The results are compared to those in Ti-doped cis-polyacetylene.

Stability And Magnetic Properties Of T2sin (T=Cr,Mn,1≤N≤8) Clusters, R. Robles, Shiv N. Khanna, A. W. Castleman Jr

Physics Publications

First-principles studies on the geometry, electronic structure, and magnetic properties of neutral and anionic Cr2Sin and Mn2Sin (1≤n≤8) have been carried out within a gradient corrected density-functional framework. We find that Cr2Sin clusters containing up to five Si atoms and Mn2Sin clusters containing up to eight Si atoms are all marked by finite local spin moments at the transition-metal site that order ferromagnetically or antiferromagnetically depending on the size and the charged state. Our studies of the variation in the binding energy upon addition of successive Si atoms and the gap between the highest occupied molecular orbital and the lowest …

Anisotropy In The Electronic Structure Of V2gec Investigated By Soft X-Ray Emission Spectroscopy And First-Principles Theory, Martin Magnuson, Ola Wilhelmsson, Maurizio Mattesini, Sa Li, Rajeev Ahuja, Olle Eriksson, Hans Högberg, Lars Hultman, Ulf Jansson

Physics Publications

The anisotropy of the electronic structure of ternary nanolaminate V2GeC is investigated by bulk-sensitive soft x-ray emission spectroscopy. The measured polarization-dependent emission spectra of V L2,3, C K, Ge M1, and Ge M2,3 in V2GeC are compared with those from monocarbide VC and pure Ge. The experimental emission spectra are interpreted with calculated spectra using ab initio density-functional theory including dipole transition matrix elements. Different types of covalent chemical bond regions are revealed: V 3d-C 2p bonding at −3.8 eV, Ge 4p-C 2p bonding at −6 eV, and Ge 4p-C 2sinteraction mediated via the V 3d orbitals at −11 eV …

Photoelectron Spectroscopic And Theoretical Studies Of Fem−(Coronene)N (M=1,2, N=1,2) Complexes, Xiang Li, Soren Eustis, Kit H. Bowen, Anil K. Kandalam, Puru Jena

Physics Publications

Fem(coronene)n (m=1,2, n=1,2) cluster anions were generated by a laser vaporization source and studied by anion photoelectron spectroscopy. Density functional theory was used to calculate the structures and the spin multiplicities of those clusters as well as the electron affinities and photodetachment transitions. The calculated magnetic moments of Fe1(coronene)1 and Fe2(coronene)1 clusters suggest that coronene could be a suitable template on which to deposit small iron clusters and that these in turn might form the basis of an iron cluster-based magnetic material. Fe1(coronene)2 and Fe2(coronene)2 cluster anions and their corresponding neutrals prefer the sandwich-type structures, and the ground state structures …

Interaction Of Gas Molecules With Ti-Benzene Complexes, G. Chen, P. Jena, Y. Kawazoe

Physics Publications

Using first-principles calculations based on gradient corrected density functional theory, we have studied the interaction of NH3, H2, and O2 with Ti-benzene complexes [Ti(Bz)2 and Ti2(Bz)2]. The energy barriers as the gas molecules approach the Ti-benzene complexes as well as the geometries of the ground state of these interacting complexes were obtained by starting with several initial configurations. While NH3 and H2 were found to physisorb on the Ti(Bz)2 complex, the O2 reacts with it strongly leading to dissociative chemisorption of the oxygen molecule. In contrast all the gas molecules react with the Ti2(Bz)2 complex. These studies indicate that the …

Photoelectron Spectroscopy And Theoretical Studies Of [Com(Pyrene)N]− (M=1,2 And N=1,2) Complexes, Anil K. Kandalam, Puru Jena, Xiang Li, Soren N. Eustis, Kit H. Bowen

Physics Publications

Anion photoelectron spectroscopic experiments and density functional theory based calculations have been used to investigate the structural, electronic, and magnetic properties of neutral and anionic [Com(pyrene)n] (m,n=1–2) complexes. The calculated electron affinities and vertical transition energies of Com(pyrene)n are in good agreement with the measured values. Our results provide clear evidence for dimerization of Co atoms and formation of sandwich structures in these complexes. While the calculated spin magnetic moments of neutral Co2(pyrene)n complexes suggest a preference for ferromagnetic coupling between Co atoms, the spin magnetic moment of Co atom in Co(pyrene) and Co(pyrene)2 complexes was reduced to 1μB.

Ligand Induced Ferromagnetism In Zno Nanostructures, Qian Wang, Qiang Sun, P. Jena

Physics Publications

Complementary to the experimental finding that ZnO nanoparticles become ferromagnetic when coated with N and S containing ligands such as dodecylamine and dodecanethiol [Garcia et al., Nano Lett.7, 1489 (2007)], we provide the first theoretical understanding of the origin of magnetism in ligated ZnO nanoparticles as well as the structural properties of the ligated systems by using density functional theory and generalized gradient approximation for exchange and correlation, and a cluster model for the nanoparticles. We show that N or S atoms of the ligand bind to the Zn sites. The accompanying changes in the Zn–O bond length, hybridization …

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Journal of Mathematics and Science: Collaborative Explorations

No abstract provided.

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Journal of Mathematics and Science: Collaborative Explorations

No abstract provided.

Oceanography Professional Development In Virginia Via Collaboration, Field Integration, And Inquiry, K. St. John

Journal of Mathematics and Science: Collaborative Explorations

Seventy-nine in-service teachers completed one of six sections of a grant-funded, graduate-level, summer course entitled, Oceanography, that was offered at four different locations in Virginia between 2005 and 2007. The majority of the teachers enrolled with the objective of obtaining their add-on earth science endorsement through the Virginia Earth Science Collaborative (VESC). Oceanography was designed to integrate the following: 1) the ocean science disciplines of geology, chemistry, physics, and biology; 2) inquiry-based learning strategies, quantitative activities, and technology; and, 3) Virginia Institute of Marine Science (VIMS) field experience with classroom experiences. These design themes were informed by ocean science content …

Two Boats, Three Summers, Five Universities, One Dozen Instructors, And Sixty-Five Teachers: A Collaborative Oceanography Field Program For Earth Science, V. Clark, C. Hopper-Brill, C. Petrone

Journal of Mathematics and Science: Collaborative Explorations

A three-day field workshop was an integral component of the graduate-level course entitled, Oceanography, that was offered by Virginia Earth Science Collaborative Project (VESC) to help Virginia educators earn the earth science teaching endorsement. The VESC partner institutions that offered Oceanographngeorge Mason University, James Madison University, the University of Virginia Southwest Center, and Virginia Commonwealth University-lacked direct access to research and education facilities en the coast. The College of William & Mary, another VESC partner, provided this resource through the Virginia Institute of Marine Science’s (VIMS) Eastern Shore Laboratory in Wachapreague, Virginia. The field program agenda and activities were developed …

Virginia Earth Science Collaborative: Developing Highly Qualified Earth Science Teachers, J. Cothron

Journal of Mathematics and Science: Collaborative Explorations

A collaborative of seven institutes of higher education and two non-profit organizations developed and implemented five earth science courses totaling eighteen credits that enabled secondary teachers to acquire an add-on earth science endorsement: Geology 1: Physical Geology (4), Geology II: Geology of Virginia (4), Oceanography (4), Astronomy (Space Science for Teachers) (3), and Meteorology (3). These courses were collaboratively developed and included rigorous academic content, research-based instructional strategies, and intense field experiences. The thirty-three sections offered statewide served 499 participants. Three courses were offered to strengthen the skills of earth science teachers: Teaching Eath Science Topics to Special Education Students …

Maximizing The Impact Of Professional Development For Earth Science Teachers, W. M. Frazier, D. R. Sterling

Journal of Mathematics and Science: Collaborative Explorations

This study examines the extent to which follow-up sessions can provide support for earth science teachers as they apply what they learn from professional development coursework during the academic year with their own students. Data include direct observation of follow-up sessions of courses for teachers; interviews with course co-instructors and teacher participants; and, document analysis of teacher products with a focus on the lesson plans, laboratory/activity sheets for students, and virtual field trips that teacher participants submitted and shared during follow-up sessions. Strategies are recommended to assist earth science content faculty in increasing the impact of their work with teachers …

Virginia Earth Science Collaborative Astronomy Course For Teachers, E. M. Murphy, H. Geller, M. Bentley

Journal of Mathematics and Science: Collaborative Explorations

We describe the development and implementation of a professional development course for teachers of grades 4-12 designed to increase their content knowledge in astronomy, space science, and the nature of science using interactive presentations, and hands-on and inquiry-based lessons. The course, Space Science for Teachers, encompasses the astronomy and nature of science components of the Virginia Standards of Learning for grades 4-12 [1]. In addition to increasing their content knowledge, teachers gain experience using innovative teaching technologies, such as an inflatable planetarium, planetarium computer software, and computer controlled telescopes. The courses included evening laboratory sessions where teachers learned the constellations, …