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Electronic Theses and Dissertations

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Articles 3421 - 3450 of 4194

Full-Text Articles in Physical Sciences and Mathematics

Graph Theoretic Modeling: Case Studies In Redundant Arrays Of Independent Disks And Network Defense, Sanjeeb Nanda Jan 2007

Graph Theoretic Modeling: Case Studies In Redundant Arrays Of Independent Disks And Network Defense, Sanjeeb Nanda

Electronic Theses and Dissertations

Graph theoretic modeling has served as an invaluable tool for solving a variety of problems since its introduction in Euler's paper on the Bridges of Königsberg in 1736 . Two amongst them of contemporary interest are the modeling of Redundant Arrays of Inexpensive Disks (RAID), and the identification of network attacks. While the former is vital to the protection and uninterrupted availability of data, the latter is crucial to the integrity of systems comprising networks. Both are of practical importance due to the continuing growth of data and its demand at increasing numbers of geographically distributed locations through the use …


Electrical Capacitance Volume Tomography Of High Contrast Dielectrics Using A Cuboid Geometry, Mark Nurge Jan 2007

Electrical Capacitance Volume Tomography Of High Contrast Dielectrics Using A Cuboid Geometry, Mark Nurge

Electronic Theses and Dissertations

An Electrical Capacitance Volume Tomography system has been created for use with a new image reconstruction algorithm capable of imaging high contrast dielectric distributions. The electrode geometry consists of two 4 x 4 parallel planes of copper conductors connected through custom built switch electronics to a commercially available capacitance to digital converter. Typical electrical capacitance tomography (ECT) systems rely solely on mutual capacitance readings to reconstruct images of dielectric distributions. This dissertation presents a method of reconstructing images of high contrast dielectric materials using only the self capacitance measurements. By constraining the unknown dielectric material to one of two values, …


Design And Demonstration Of Meanderline Retarders At Infrared Frequencies, Jeffrey Scott Tharp Jan 2007

Design And Demonstration Of Meanderline Retarders At Infrared Frequencies, Jeffrey Scott Tharp

Electronic Theses and Dissertations

Meanderline structures are widely used as engineered birefringent materials for waveplates and retarders at radiofrequencies, and have been previously demonstrated at frequencies up to 90 GHz in the millimeter-wave band. In this dissertation, we present results related to the modeling, fabrication, and experimental characterization of meanderlines across the range from 30 to 100 THz, in the long-wave and mid-wave infrared bands. Specific issues addressed in these new designs include spectral dispersion and angular dependence of the retardance, as well as axial ratio and throughput. The impact resulting from the infrared properties of the metals and dielectrics is explicitly included throughout. …


Mac Layer And Routing Protocols For Wireless Ad Hoc Networks With Asymmetric Links And Performance Evaluation Studies, Guoqiang Wang Jan 2007

Mac Layer And Routing Protocols For Wireless Ad Hoc Networks With Asymmetric Links And Performance Evaluation Studies, Guoqiang Wang

Electronic Theses and Dissertations

In a heterogeneous mobile ad hoc network (MANET), assorted devices with different computation and communication capabilities co-exist. In this thesis, we consider the case when the nodes of a MANET have various degrees of mobility and range, and the communication links are asymmetric. Many routing protocols for ad hoc networks routinely assume that all communication links are symmetric, if node A can hear node B and node B can also hear node A. Most current MAC layer protocols are unable to exploit the asymmetric links present in a network, thus leading to an inefficient overall bandwidth utilization, or, in the …


Optical And Physical Properties Of Ceramic Crystal Laser Materials, Jed Simmons Jan 2007

Optical And Physical Properties Of Ceramic Crystal Laser Materials, Jed Simmons

Electronic Theses and Dissertations

Historically ceramic crystal laser material has had disadvantages compared to single crystal laser material. However, progress has been made in the last decade and a half to overcome the disadvantages associated with ceramic crystal. Today, because of the promise of ceramic crystal as a high power laser material, investigation into its properties, both physical and optical, is warranted and important. Thermal expansion was measured in this thesis for Nd:YAG (yttrium aluminum garnet) ceramic crystal using an interferometric method. The interferometer employed a spatially filtered HeNe at 633 nm wavelength. Thermal expansion coefficients measured for the ceramic crystal samples were near …


Resource-Constraint And Scalable Data Distribution Management For High Level Architecture, Pankaj Gupta Jan 2007

Resource-Constraint And Scalable Data Distribution Management For High Level Architecture, Pankaj Gupta

Electronic Theses and Dissertations

In this dissertation, we present an efficient algorithm, called P-Pruning algorithm, for data distribution management problem in High Level Architecture. High Level Architecture (HLA) presents a framework for modeling and simulation within the Department of Defense (DoD) and forms the basis of IEEE 1516 standard. The goal of this architecture is to interoperate multiple simulations and facilitate the reuse of simulation components. Data Distribution Management (DDM) is one of the six components in HLA that is responsible for limiting and controlling the data exchanged in a simulation and reducing the processing requirements of federates. DDM is also an important problem …


Image-Space Approach To Real-Time Realistic Rendering, Musawir Shah Jan 2007

Image-Space Approach To Real-Time Realistic Rendering, Musawir Shah

Electronic Theses and Dissertations

One of the main goals of computer graphics is the fast synthesis of photorealistic image of virtual 3D scenes. The work presented in this thesis addresses this goal of speed and realism. In real-time realistic rendering, we encounter certain problems that are difficult to solve in the traditional 3-dimensional geometric space. We show that using an image-space approach can provide effective solutions to these problems. Unlike geometric space algorithms that operate on 3D primitives such as points, edges, and polygons, image-space algorithms operate on 2D snapshot images of the 3D geometric data. Operating in image-space effectively decouples the geometric complexity …


Medium Access Control Protocols And Routing Algorithms For Wireless Sensor Networks, Anirban Bag Jan 2007

Medium Access Control Protocols And Routing Algorithms For Wireless Sensor Networks, Anirban Bag

Electronic Theses and Dissertations

In recent years, the development of a large variety of mobile computing devices has led to wide scale deployment and use of wireless ad hoc and sensor networks. Wireless Sensor Networks consist of battery powered, tiny and cheap "motes", having sensing and wireless communication capabilities. Although wireless motes have limited battery power, communication and computation capabilities, the range of their application is vast. In the first part of the dissertation, we have addressed the specific application of Biomedical Sensor Networks. To solve the problem of data routing in these networks, we have proposed the Adaptive Least Temperature Routing (ALTR) algorithm …


Far-Infrared/Millimeter Wave Source And Component Development For Imaging And Spectroscopy, Todd Du Bosq Jan 2007

Far-Infrared/Millimeter Wave Source And Component Development For Imaging And Spectroscopy, Todd Du Bosq

Electronic Theses and Dissertations

The far-infrared and millimeter wave (FIR/mmW) (wavelength 75 micrometer to 10 mm) portion of the electromagnetic spectrum is fairly underdeveloped technologically, owing to the large amount of atmospheric attenuation in that range. At present, the FIR/mmW region is lacking in compact, high-brightness radiation sources and practical imaging systems. This dissertation focuses on development of two complementary technologies in this area - an active mmW imaging system and high-reflectivity Bragg mirrors for the FIR p-Ge laser. The imaging system uses a vector network analyzer in the frequency range of 90-140 GHz as the radiation source and receiver. Raster scanning is used …


Impulse Formulations Of The Euler Equations For Incompressible And Compressible Fluids, Victor David Pareja Jan 2007

Impulse Formulations Of The Euler Equations For Incompressible And Compressible Fluids, Victor David Pareja

Electronic Theses and Dissertations

The purpose of this paper is to consider the impulse formulations of the Euler equations for incompressible and compressible fluids. Different gauges are considered. In particular, the Kuz'min gauge provides an interesting case as it allows the fluid impulse velocity to describe the evolution of material surface elements. This result affords interesting physical interpretations of the Kuz'min invariant. Some exact solutions in the impulse formulation are studied. Finally, generalizations to compressible fluids are considered as an extension of these results. The arrangement of the paper is as follows: in the first chapter we will give a brief explanation on the …


All-Optical Regeneration For Phase-Shift Keyed Optical Communication Systems, Kevin Croussore Jan 2007

All-Optical Regeneration For Phase-Shift Keyed Optical Communication Systems, Kevin Croussore

Electronic Theses and Dissertations

All-optical signal processing techniques for phase-shift keyed (PSK) systems were developed theoretically and demonstrated experimentally. Nonlinear optical effects in fibers, in particular four-wave mixing (FWM) that occurs via the ultra-fast Kerr nonlinearity, offer a flexible framework within which numerous signal processing functions can be accomplished. This research has focused on the regenerative capabilities of various FWM configurations in the context of processing PSK signals. Phase-preserving amplitude regeneration, phase regeneration, and phase-regenerative wavelength conversion are analyzed and demonstrated experimentally. The single-pump phase-conjugation process was used to regenerate RZ-DPSK pulse amplitudes with different input noise distributions, and the impact on output phase …


Two-Dimensional Guided Mode Resonant Structures For Spectral Filtering Applications, Sakoolkan Boonruang Jan 2007

Two-Dimensional Guided Mode Resonant Structures For Spectral Filtering Applications, Sakoolkan Boonruang

Electronic Theses and Dissertations

Guided mode resonant (GMR) structures are optical devices that consist of a planar waveguide with a periodic structure either imbedded in or on the surface of the structure. The resonance anomaly in GMR structures has many applications as dielectric mirrors, tunable devices, sensors,and narrow spectral band reflection filters. A desirable response from a resonant grating filter normally includes a nearly 100% narrowband resonant spectral reflection (transmission), and a broad angular acceptance at either normal incidence or an oblique angle of incidence. This dissertation is a detailed study of the unique nature of the resonance anomaly in GMR structures with two-dimensional …


Optimizing The High Dynamic Range Imaging Pipeline, Ahmet Oguz Akyuz Jan 2007

Optimizing The High Dynamic Range Imaging Pipeline, Ahmet Oguz Akyuz

Electronic Theses and Dissertations

High dynamic range (HDR) imaging is a rapidly growing field in computer graphics and image processing. It allows capture, storage, processing, and display of photographic information within a scene-referred framework. The HDR imaging pipeline consists of the major steps an HDR image is expected to go through from capture to display. It involves various techniques to create HDR images, pixel encodings and file formats for storage, tone mapping for display on conventional display devices and direct display on HDR capable screens. Each of these stages have important open problems, which need to be addressed for a smoother transition to an …


Modeled And Observed N2 Lyman-Birge-Hopfield Band Emissions Earth's Dayglow: A Comparison, Donald Murray Jan 2007

Modeled And Observed N2 Lyman-Birge-Hopfield Band Emissions Earth's Dayglow: A Comparison, Donald Murray

Electronic Theses and Dissertations

Ultraviolet (UV) spectra obtained from Earth’s dayglow contain important information for understanding the thermosphere, and the N2 Lyman-Birge-Hopfield (LBH) bands are possibly the most useful emission. To be useful, a thorough understanding of how the LBH band emission varies with altitude and latitude is essential to present and future use of this emission by space-based remote sensors. Excited by photoelectron impact on N2 leading to transitions from the a 1Πg state to the ground state, the LBH emissions radiate between 1270 and 2400 Å. In addition to being populated by electron impact excitation, the a 1Πg state is populated by …


Discrete Surface Solitons, Sergiy Suntsov Jan 2007

Discrete Surface Solitons, Sergiy Suntsov

Electronic Theses and Dissertations

Surface waves exist along the interfaces between two different media and are known to display properties that have no analogue in continuous systems. In years past, they have been the subject of many studies in a diverse collection of scientific disciplines. In optics, one of the mechanisms through which optical surface waves can exist is material nonlinearity. Until recently, most of the activity in this area was focused on interfaces between continuous media but no successful experiments have been reported. However, the growing interest that nonlinear discrete optics has attracted in the last two decades has raised the question of …


Effects Of Polarization And Coherence On The Propagation And The Detection Of Stochastic Electromagnetic Beams, Mohamed Fouad Salem Jan 2007

Effects Of Polarization And Coherence On The Propagation And The Detection Of Stochastic Electromagnetic Beams, Mohamed Fouad Salem

Electronic Theses and Dissertations

Most of the physically realizable optical sources are radiating in a random manner given the random nature of the radiation of a large number of atoms that constitute the source. Besides, a lot of natural and synthetic materials are fluctuating randomly. Hence, the optical fields that one encounters, in most of the applications are fluctuating and must be treated using random or stochastic functions. Within the framework of the scalar-coherence theory, one can describe changes of the properties of any stochastic field such as the spectral density and the spectral degree of coherence on propagation in any linear medium, deterministic …


Early Life Stage Characteristics Of Six Acadian Conifer Species: Germination And Seedling Development In A Changing Climate, Jason D. Schatz Jan 2007

Early Life Stage Characteristics Of Six Acadian Conifer Species: Germination And Seedling Development In A Changing Climate, Jason D. Schatz

Electronic Theses and Dissertations

Global climate change will drastically alter regional climates. The influence of these changes on the distribution and relative abundance of forest trees is both critically important and subject to substantial uncertainty. It will be particularly important to understand the effects of different climate scenarios on the early life stages of major tree species, because: 1) Early life stage performance and survival strongly influence the abundance of mature trees of a given species, 2) Trees are most sensitive to environmental variation during their early life stages, and 3) Our knowledge of the response of Acadian Forest tree species to environmental variation …


Raman Spectroscopic Study Of Single Red Blood Cells Infected By The Malaria Parasite Plasmodium Falciparum, William Carter Jan 2007

Raman Spectroscopic Study Of Single Red Blood Cells Infected By The Malaria Parasite Plasmodium Falciparum, William Carter

Electronic Theses and Dissertations

Raman micro-spectroscopy provides a non-destructive probe with potential applications as a diagnostic tool for cellular disorders. This study presents micro-Raman spectra of live erythrocytes infected with a malaria parasite and investigates the potential of this probe to monitor molecular changes which occur during differentiation of the parasite inside the cell. At an excitation wavelength of 633 nm the spectral bands are dominated by hemoglobin vibrations yielding information the on structure and spin state of the heme moiety. It also demonstrates the novel use of silica capillaries as a viable method for studying the erythrocytes in an environment that is much …


Scalable Volumetric Three-Dimensional Up-Conversion Display Medium, Jung-Hyun Cho Jan 2007

Scalable Volumetric Three-Dimensional Up-Conversion Display Medium, Jung-Hyun Cho

Electronic Theses and Dissertations

There are many different techniques to display 3D information. However, not many of them are able to provide sufficient depth cues to the observers to sense or feel the images as real three-dimensional objects. Volumetric three-dimensional displays generate images within a real 3D space, so they provide most of the depth cues automatically. This thesis discusses the basic notions required to understand three-dimensional displays. Also discussed are different techniques used to display 3D information and their advantages and disadvantages as well as their current limitations. Several rare-earth doped fluoride crystals that are excited to emit visible light by sequential two …


Studies Of A Quantum Scheduling Algorithm And On Quantum Error Correction, Feng Lu Jan 2007

Studies Of A Quantum Scheduling Algorithm And On Quantum Error Correction, Feng Lu

Electronic Theses and Dissertations

Quantum computation has been a rich field of study for decades because it promises possible spectacular advances, some of which may run counter to our classically rooted intuitions. At the same time, quantum computation is still in its infancy in both theoretical and practical areas. Efficient quantum algorithms are very limited in number and scope; no real breakthrough has yet been achieved in physical implementations. Grover's search algorithm can be applied to a wide range of problems; even problems not generally regarded as searching problems can be reformulated to take advantage of quantum parallelism and entanglement leading to algorithms which …


Real-Time Tree Simulation Using Verlet Integration, Bobak Manavi Jan 2007

Real-Time Tree Simulation Using Verlet Integration, Bobak Manavi

Electronic Theses and Dissertations

One of the most important challenges in real-time simulation of large trees and vegetation is the vast number of calculations required to simulate the interactions between all the branches in the tree when external forces are applied to it. This paper will propose the use of algorithms employed by applications like cloth and soft body simulations, where objects can be represented by a finite system of particles connected via spring-like constraints, for the structural representation and manipulation of trees in real-time. We will then derive and show the use of Verlet integration and the constraint configuration used for simulating trees …


Dissipative Solitons In The Cubic-Quintic Complex Ginzburg-Landau Equation:Bifurcations And Spatiotemporal Structure, Ciprian Mancas Jan 2007

Dissipative Solitons In The Cubic-Quintic Complex Ginzburg-Landau Equation:Bifurcations And Spatiotemporal Structure, Ciprian Mancas

Electronic Theses and Dissertations

Comprehensive numerical simulations (reviewed in Dissipative Solitons, Akhmediev and Ankiewicz (Eds.), Springer, Berlin, 2005) of pulse solutions of the cubic--quintic Ginzburg--Landau equation (CGLE), a canonical equation governing the weakly nonlinear behavior of dissipative systems in a wide variety of disciplines, reveal various intriguing and entirely novel classes of solutions. In particular, there are five new classes of pulse or solitary waves solutions, viz. pulsating, creeping, snake, erupting, and chaotic solitons. In contrast to the regular solitary waves investigated in numerous integrable and non--integrable systems over the last three decades, these dissipative solitons are not stationary in time. Rather, they are …


Learning Geometry-Free Face Re-Lighting, Thomas Brendan Moore Jan 2007

Learning Geometry-Free Face Re-Lighting, Thomas Brendan Moore

Electronic Theses and Dissertations

The accurate modeling of the variability of illumination in a class of images is a fundamental problem that occurs in many areas of computer vision and graphics. For instance, in computer vision there is the problem of facial recognition. Simply, one would hope to be able to identify a known face under any illumination. On the other hand, in graphics one could imagine a system that, given an image, the illumination model could be identified and then used to create new images. In this thesis we describe a method for learning the illumination model for a class of images. Once …


Analytical Potential Of Polymerized Liposomes Bound To Lanthanide Ions For Qualitative And Quantitative Analysis Of Proteins, Marina Santos Jan 2007

Analytical Potential Of Polymerized Liposomes Bound To Lanthanide Ions For Qualitative And Quantitative Analysis Of Proteins, Marina Santos

Electronic Theses and Dissertations

One of the intriguing features of biological systems is the prevalence of highly selective and often very strong interactions among different cellular components. Such interactions play a variety of organizational, mechanical, and physiological roles at the cellular and organism levels. Antigen-antibody complexes are representative examples of highly selective and potent interactions involving proteins. The marked specificity of protein-antibody complexes have led to a wide range of applications in cellular and molecular biology related research. They have become an integral research tool in the present genomic and proteomic era. Unfortunately, the production of selective tools based on antigen-antibody interactions requires cumbersome …


Experimental Study Of Profiles Of Implanted Species Into Semiconductor Materials Using Secondary Ion Mass Spectrometry, Fatma Salman Jan 2007

Experimental Study Of Profiles Of Implanted Species Into Semiconductor Materials Using Secondary Ion Mass Spectrometry, Fatma Salman

Electronic Theses and Dissertations

The study of impurity diffusion in semiconductor hosts is an important field that has both fundamental appeal and practical applications. Ion implantation is a good technique to introduce impurities deep into the semiconductor substrates at relatively low temperature and is not limited by the solubility of the dopants in the host. However ion implantation creates defects and damages to the substrate. Annealing process was used to heal these damages and to activate the dopants. In this study, we introduced several species such as alkali metals (Li, Na, K), alkali earth metals (Be, Ca,), transition metals (Ti, V, Cr, Mn) and …


Three-Dimensional Micron-Scale Metal Photonic Crystals Via Multi-Photon Direct Laser Writing And Electroless Metal Deposition, Amir Tal Jan 2007

Three-Dimensional Micron-Scale Metal Photonic Crystals Via Multi-Photon Direct Laser Writing And Electroless Metal Deposition, Amir Tal

Electronic Theses and Dissertations

Three-dimensional (3D) metal photonic crystals (MPCs) can exhibit interesting electromagnetic properties such as ultra-wide photonic or "plasmonic" band gaps, selectively tailored thermal emission, extrinsically modified absorption, and negative refractive index. Yet, optical-wavelength 3D MPCs remain relatively unexplored due to the challenges posed by their fabrication. This work explores the use of multi-photon direct laser writing (DLW) coupled with electroless metallization as a means for preparing MPCs. Multi-photon DLW was used to prepare polymeric photonic crystal (PC) templates having a targeted micron-scale structure and form. MPCs were then created by metallizing the polymeric PCs via wet-chemical electroless deposition. The electromagnetic properties …


Investigating Student Understanding Of Sound As A Longitudinal Wave, Earl C. Coombs Jan 2007

Investigating Student Understanding Of Sound As A Longitudinal Wave, Earl C. Coombs

Electronic Theses and Dissertations

The field of physics education research (PER) has highlighted the discrepancy between what is taught during traditional instruction in physics, and what students understand afterward. PER has also provided alternatives to traditional instruction that are research-based and have been shown to be more effective in bringing students’ level of understanding of physics more in line with that of the scientific community. One topic that has received attention is the propagation of sound. We confirmed that students in the introductory algebra-based and calculus-based physics courses at the University of Maine have difficulties with sound propagation similar to those documented by others. …


Effect Of Coyotes And Release Site Selection On Survival And Movement Of Translocated Swift Foxes In The Badlands Ecosystem Of South Dakota, Greg M. Schroeder Jan 2007

Effect Of Coyotes And Release Site Selection On Survival And Movement Of Translocated Swift Foxes In The Badlands Ecosystem Of South Dakota, Greg M. Schroeder

Electronic Theses and Dissertations

Success of different release strategies for swift fox (Vulpes velox) translocation was evaluated in the Badlands Ecosystem in southwestern South Dakota. Release site selection (outside coyote [Canis latrans] core-use areas compared to random release sites) and release method (i.e., hard, semi-hard, and soft) were examined to determine effects on swift fox survival and movements at 50 days post-release. I hypothesized that swift foxes released outside of coyote core-use areas would survive at a higher rate than foxes released at random sites. From 2003-2006, 16 adult coyotes were fitted with Global Positioning System (GPS) radio collars and monitored during the pup …


Methods For The Translocation Of The Yellow Lampmussel (Lampsilis Cariosa) And The Tidewater Mucket (Leptodea Ochracea) In The Fort Halifax Dam Impoundment Of The Sebasticok River, Maine, Jennifer Elaine Kurth Jan 2007

Methods For The Translocation Of The Yellow Lampmussel (Lampsilis Cariosa) And The Tidewater Mucket (Leptodea Ochracea) In The Fort Halifax Dam Impoundment Of The Sebasticok River, Maine, Jennifer Elaine Kurth

Electronic Theses and Dissertations

Translocation from areas where habitat alterations are proposed can be an important mussel conservation tool. Pending removal of the Fort Halifax dam on the Sebasticook River in Maine potentially would result in extensive mortality of two statelisted threatened species of mussels, yellow lampmussels (Lampsilis cariosa) and tidewater muckets (Leptodea ochracea), which occur in the impoundment above the dam. My study assessed populations of these two species in the impoundment, and determined the effects of within- and between-waterbody translocations on survival. I conducted a qualitative survey of the Fort Halifax dam impoundment in 2004 to determine locations …


Indoor Air Quality: Determination Of Voc's In A Reproductive Clinic., Miriam Rachel Trivette Dec 2006

Indoor Air Quality: Determination Of Voc's In A Reproductive Clinic., Miriam Rachel Trivette

Electronic Theses and Dissertations

The purpose of this study was to perform an indoor air quality (IAQ) investigation at the Center for Applied Reproductive Science (CARS) to assess whether VOCs exist at levels dangerous to embryo. Formaldehyde, n-hexane, benzene, and styrene concentrations were measured at six locations. Formaldehyde concentrations were comparable to office and residential indoor air. N-hexane, benzene, and styrene were not detected. In addition, acetaldehyde, ethanol, and isopropyl alcohol were detected. IAQ parameters (carbon dioxide, temperature, humidity, pressure, and particulates) were measured at 22 sites monthly for one year. Temperature and humidity readings were within Environmental Protection Agency recommendations. Particulate concentrations were …