Physical Sciences and Mathematics Commons^™

A Comparative Analysis Of Air-To-Ground Engagement Outcomes In The Joint Warfare System (Jwars) And The Jwars-Joint Semi-Automated Forces Federation, Melissa Anne St. Peter

Computational Modeling & Simulation Engineering Theses & Dissertations

Multi-resolution modeling is the process by which a single model is created by connecting multiple individual models to describe phenomena at different levels of resolution [1]. "When we change resolutions, replacing a detailed model by a more aggregate one, we must ask whether results are 'consistent'" [2].

There are many methods of determining if the results of two simulations are 'consistent'. However, they are very entailed and require a detailed understanding of the individual models including their functionality, algorithms, and inner workings. A straight forward and rapid way of assessing potential inconsistencies is through a statistical comparison of the model …

Spectral Shape As An Indicator Of Molecular Weight In Chromophoric Dissolved Organic Matter, John Robert Helms

Chemistry & Biochemistry Theses & Dissertations

Spectral slope is a term used to parameterize featureless absorbance spectra according to their shape. Spectral slope is obtained by calculating the slope of the log-linearized absorption spectrum over a given range of wavelengths. Past studies have shown that spectral slope is related to molecular size in fulvic acids. A simple method of spectral analysis that compares spectral slopes obtained from two distinct regions of the UV spectra of aquatic dissolved organic matter is demonstrated. The ratio of these slopes (R_S) shows considerable change during photo-oxidation, variation within estuaries, and substantial shifts with depth in the upper 1000 …

Running Coupling Constant And Transition From Low To High Energies In Quantum Chromodynamics, Alexander Babansky

Physics Theses & Dissertations

The remarkable feature of QCD is that the coupling constant (the strength of the interaction) depends on the energy of the interacting particles. At high energies, the coupling constant vanishes and QCD becomes asymptotically free. However, at lower energy, the running coupling constant increases, leading to the confining strong-coupling theory at energies of the order of hadron masses. We study the essential effects of the running coupling constant and analyze the transition from high to low energies in different processes.

An Analysis Of Indicator Organism Suitability For Lower James And York Rivers, Rhonda Ashonti Ford

Civil & Environmental Engineering Theses & Dissertations

The primary objectives of this thesis are (1) determine if the proper indicator organism is being utilized to determine the bacterial water quality in the State of Virginia. (2) If other environmental factors can predict the bacterial water quality. The current indicator organism of choice for bacterial water quality of waters in the State of Virginia is enterococci, for estuarine and brackish waters. E. coli is the indicator organism of choice for fresh waters in Virginia.

The study concluded (1) Enterococci are the best indicator organism for beaches located in the Hampton Roads Harbor and the Lower James River. (2) …

Development Of A Tidal Wetland Inventory And Assessment For York River, Virginia Watershed, Center For Coastal Resources Management, Virginia Institute Of Marine Science

Reports

As part of the Chesapeake 2000 agreement, the Commonwealth of Virginia pledged to a wetland policy of no net-loss. Through conscientious resource protection and management, Virginia’s non-tidal and tidal wetland permit programs, administered by the Virginia Department of Environmental Quality (DEQ) and The Virginia Marine Resources Commission (VMRC) respectfully, are committed to reaching this goal. In order to assist these agencies in realizing no-net loss of wetlands, the availability of baseline data is essential in defining our existing resources and is the basis from which future status and trends can be evaluated along with the effectiveness of permitting and management …

An Implicit Level Set Model For Firespread, Pallop Huabsomboon

Mathematics & Statistics Theses & Dissertations

The level set method is a mathematical and computational, technique for tracking a moving interface over time. It can naturally handle topological changes such as merging or breaking interfaces. Intrinsic geometric properties of the interface, such as curvature and normal direction, are easily determined from the level set function &phis;. There are many applications of the level set method, including kinetic crystal growth, epitaxial growth of thin films, image restoration, vortex dominated flows, and so forth. Most applications described in the growing literature on the applications of level sets advance the level set equation with explicit time integration. Hence, small …

Hessian Matrix-Free Lagrange-Newton-Krylov-Schur-Schwarz Methods For Elliptic Inverse Problems, Widodo Samyono

Mathematics & Statistics Theses & Dissertations

This study focuses on the solution of inverse problems for elliptic systems. The inverse problem is constructed as a PDE-constrained optimization, where the cost function is the L² norm of the difference between the measured data and the predicted state variable, and the constraint is an elliptic PDE. Particular examples of the system considered in this stud, are groundwater flow and radiation transport. The inverse problems are typically ill-posed due to error in measurements of the data. Regularization methods are employed to partially alleviate this problem. The PDE-constrained optimization is formulated as the minimization of a Lagrangian functional, formed …

Significant Tectonic And Climatic Events For The Yakutat Block Collision, Gulf Of Alaska: Pleistocene Glacial Intensification In The St. Elias Mountains And The Relationship Between The Fairweather And Transition Faults, Sean P.S. Gulick, Bryce A. Willems, Jeffrey T. Freymueller, Ross D. Powell, John M. Jaeger, Jay Kalbas, John M. Jaeger, Terry L. Pavlis, Lindsay A, Lowe, Larry A. Mayer, James V. Gardner

Center for Coastal and Ocean Mapping

No abstract provided.

Modeling And Simulation Of Value -At -Risk In The Financial Market Area, Xiangyin Zheng

Doctoral Dissertations

Value-at-Risk (VaR) is a statistical approach to measure market risk. It is widely used by banks, securities firms, commodity and energy merchants, and other trading organizations. The main focus of this research is measuring and analyzing market risk by modeling and simulation of Value-at-Risk for portfolios in the financial market area. The objectives are (1) predicting possible future loss for a financial portfolio from VaR measurement, and (2) identifying how the distributions of the risk factors affect the distribution of the portfolio. Results from (1) and (2) provide valuable information for portfolio optimization and risk management.

The model systems chosen …

สรุปกิจกรรม & สถานการณ์สิ่งแวดล้อม

Thai Environment

No abstract provided.

เจ้าแผ่นดิน...นักคิด...นักจัดการ...บริหารทรัพยากรธรรมชาติและสิ่งแวดล้อมอย่างยั่งยืน, พงศ์ศักดิ์ วัฒนสินธุ์, พันธวัศ สัมพันธ์พานิช, กัลยา ฉิมถาวร

Thai Environment

No abstract provided.

บทสัมภาษณ์ : คุณประเสริฐ บุญสัมพันธ์ กรรมการผู้จัดการใหญ่ บริษัท ปตท. จำกัด (มหาชน) ปตท. กับการมีส่วนร่วม สร้างสรรค์สังคมและสิ่งแวดล้อม, สิริพร แก่นสียา, เกษนุช ธีระภากร

Thai Environment

No abstract provided.

ภัยธรรมชาติกับภาวะโลกร้อน, สุขประโชค เอื้อกฤดาธิการ

Thai Environment

No abstract provided.

ความเสี่ยงภัยจากมลพิษในสิ่งแวดล้อม, กรองแก้ว ทิพยศักดิ์

Thai Environment

No abstract provided.

มลพิษฝุ่นละอองในบรรยากาศ, เพ็ญศรี วัจฉละญาณ, ธเรศ ศรีสถิตย์

Thai Environment

No abstract provided.

หลุมฝังกลบขยะแบบถังปฏิกิริยาชีวภาพ (Bioreactor Landfill), อิสวัต แสงมณี, นภวรรณ รัตสุข

Thai Environment

No abstract provided.

การใช้เทคนิควิศวกรรมคุณค่าเพื่อการประหยัดพลังงาน, วิสาขา ภู่จินดา

Thai Environment

No abstract provided.

การจัดการกากอุตสาหกรรม, สลิตา ปาบุตร

Thai Environment

No abstract provided.

แนะนำโครงการสถาบันวิจัยสภาวะแวดล้อม : โครงการศึกษาทบทวนโครงการอ่างเก็บน้ำใสน้อย-ใส่ใหญ่ จังหวัดปราจีนบุรี

Thai Environment

No abstract provided.

สิ่งแวดล้อมน่ารู้คู่โลกสวย

Thai Environment

No abstract provided.

Preparation And Characterization Of Hard Magnetic Nanoparticles, Daren Li

Physics Theses

Hard-magnetic nanoparticles with uniform size distribution have attracted huge attention in the past several years because of their unique magnetic properties and potential for many applications such as high density recording media, exchange-coupled nanocomposite permanent magnets and biomedical applications. In this thesis, preparation and characterization of hard magnetic nanoparticles with different sizes are reported. Monodisperse FePt nanoparticles with face-centered cubic (fcc) structure were synthesized by chemical solution method and particle diameter was tuned from 2 to 15 nm by varying reaction conditions. Monodisperse hard-magnetic FePt nanoparticles with ordered face-centered tetragonal (fct) structure were prepared by the salt-matrix annealing technique. Morphological, …

Styrenic Nanocomposites Prepared Using A Novel Biphenyl-Containing Clay, Grace Chigwada, Dongyan Wang, David D. Jiang, Charles A. Wilkie

Chemistry Faculty Research and Publications

Montmorillonite was organically modified using an ammonium salt containing 4-acetylbiphenyl. This clay (BPNC16 clay) was used to prepare polystyrene (PS), acrylonitrile butadiene styrene (ABS) and high impact polystyrene (HIPS) nanocomposites. Polystyrene nanocomposites were prepared both by in situ bulk polymerisation and melt blending processes, while the ABS and HIPS nanocomposites were prepared only by melt blending. X-ray diffraction and transmission electron microscopy were used to confirm nanocomposite formation. Thermogravimetric analysis was used to evaluate thermal stability and the flammability properties were evaluated using cone calorimetry. By thermogravimetry, BPNC16 clay was found to show high thermal stability, and by cone calorimetry, …

Thermal Degradation Of Acetate-Intercalated Hydroxy Double And Layered Hydroxy Salts, Everson Kandare, Jeanne Hossenlopp

Chemistry Faculty Research and Publications

Two hydroxy double salts (HDSs), zinc copper hydroxy acetate (ZCA) and zinc nickel hydroxy acetate (ZNA), and an analogous layered compound, zinc hydroxy acetate (ZHA), have been prepared by a coprecipitation method. The thermal degradation of these materials was characterized via thermogravimetric analysis (TGA), differential thermal analysis (DTA), and TGA coupled with Fourier transform infrared spectroscopy of gas-phase products, TGA-FTIR. Loss of physisorbed and interlayer H2O was observed between 50 and 150 °C for all compounds. Acetic acid, acetone, water, and CO2 were released at high temperatures with relative acetone yields found to be dependent on precursor identity, with very …

Polyethylene And Polypropylene Nanocomposites Based On A Three Component Oligomerically-Modified Clay, Jinguo Zhang, David D. Jiang, Charles A. Wilkie

Chemistry Faculty Research and Publications

Polyethylene and polypropylene nanocomposites were prepared using a novel oligomerically-modified clay that contains three components, styrene, lauryl acrylate and vinylbenzyl chloride. The nanocomposites were prepared by directly melt blending the polymers with the clay and they were characterized by X-ray diffraction and transmission electron microscopy, to understand their morphology, and their thermal stability, flammability and mechanical properties were evaluated using thermogravimetric analysis, cone calorimetry and mechanical testing, respectively. The reduction in peak heat release rate is about 60% at 5% inorganic clay loading and 70% at 8% inorganic clay loading.

Polystyrene Nanocomposites Based On Quinolinium And Pyridinium Surfactants, Grace Chigwada, Dongyan Wang, Charles A. Wilkie

Chemistry Faculty Research and Publications

In this paper pyridine and quinoline-containing salts were employed to modify montmorillonite. TGA analysis shows that the quinolinium modified clay has a higher thermal stability than the pyridinium modified clay. Polystyrene nanocomposites were prepared by in situ bulk polymerisation and direct melt blending using both clays. The X-ray diffraction and transmission electron microscopy results show the formation of intercalated structures. The 50% degradation temperature of the nanocomposites is increased and so is the amount of char from TGA analysis compared to the virgin polymer. Cone calorimetric results indicate that clay reduces the peak heat release rate and average mass loss …

Anonymous Signature Schemes, Guomin Yang, Duncan S. Wong, Xiaotie Deng, Huaxiong Wang

Research Collection School Of Computing and Information Systems

Digital signature is one of the most important primitives in public key cryptography. It provides authenticity, integrity and non-repudiation to many kinds of applications. On signer privacy however, it is generally unclear or suspicious of whether a signature scheme itself can guarantee the anonymity of the signer. In this paper, we give some affirmative answers to it. We formally define the signer anonymity for digital signature and propose some schemes of this type. We show that a signer anonymous signature scheme can be very useful by proposing a new anonymous key exchange protocol which allows a client Alice to establish …

Efficient Client-To-Server Assignments For Distributed Virtual Environments, Nguyen Binh Duong Ta, Suiping Zhou

Research Collection School Of Computing and Information Systems

Distributed Virtual Environments (DVEs) are distributed systems that allow multiple geographically distributed clients (users) to interact simultaneously in a computer-generated, shared virtual world. Applications of DVEs can be seen in many areas nowadays, such as online games, military simulations, collaborative designs, etc. To support large-scale DVEs with real-time interactions among thousands or more distributed clients, a geographically distributed server architecture (GDSA) is generally needed, and the virtual world can be partitioned into many distinct zones to distribute the load among the servers. Due to the geographic distributions of clients and servers in such architectures, it is essential to efficiently assign …

A Unified Log-Based Relevance Feedback Scheme For Image Retrieval, Steven Hoi, Michael R. Lyu, Rong Jin

Research Collection School Of Computing and Information Systems

Relevance feedback has emerged as a powerful tool to boost the retrieval performance in content-based image retrieval (CBIR). In the past, most research efforts in this field have focused on designing effective algorithms for traditional relevance feedback. Given that a CBIR system can collect and store users' relevance feedback information in a history log, an image retrieval system should be able to take advantage of the log data of users' feedback to enhance its retrieval performance. In this paper, we propose a unified framework for log-based relevance feedback that integrates the log of feedback data into the traditional relevance feedback …

Fisa: Feature-Based Instance Selection For Imbalanced Text Classification, Aixin Sun, Ee Peng Lim, Boualem Benatallah, Mahbub Hassan

Research Collection School Of Computing and Information Systems

Support Vector Machines (SVM) classifiers are widely used in text classification tasks and these tasks often involve imbalanced training. In this paper, we specifically address the cases where negative training documents significantly outnumber the positive ones. A generic algorithm known as FISA (Feature-based Instance Selection Algorithm), is proposed to select only a subset of negative training documents for training a SVM classifier. With a smaller carefully selected training set, a SVM classifier can be more efficiently trained while delivering comparable or better classification accuracy. In our experiments on the 20-Newsgroups dataset, using only 35% negative training examples and 60% learning …

Evaluation Of Time-Varying Availability In Multi-Echelon Spare Parts Systems With Passivation, Hoong Chuin Lau, Huawei Song, Chuen Teck See, Siew Yen Cheng

Research Collection School Of Computing and Information Systems

The popular models for repairable item inventory, both in the literature as well as practical applications, assume that the demands for items are independent of the number of working systems. However this assumption can introduce a serious underestimation of availability when the number of working systems is small, the failure rate is high or the repair time is long. In this paper, we study a multi-echelon repairable item inventory system under the phenomenon of passivation, i.e. serviceable items are passivated (“switched off”) upon system failure. This work is motivated by corrective maintenance of high-cost technical equipment in the miltary. We …