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Articles 2821 - 2850 of 3529

Full-Text Articles in Physical Sciences and Mathematics

Methods For The Analysis Of Developmental Respiration Patterns., Justin Tyler Peyton May 2008

Methods For The Analysis Of Developmental Respiration Patterns., Justin Tyler Peyton

Electronic Theses and Dissertations

This thesis looks at the problem of developmental respiration in Sarcophaga crassipalpis Macquart from the biological and instrumental points of view and adapts mathematical and statistical tools in order to analyze the data gathered. The biological motivation and current state of research is given as well as instrumental considerations and problems in the measurement of carbon dioxide production. A wide set of mathematical and statistical tools are used to analyze the time series produced in the laboratory. The objective is to assemble a methodology for the production and analysis of data that can be used in further developmental respiration research.

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Solitary Wave Families In Two Non-Integrable Models Using Reversible Systems Theory, Jonathan Leto Jan 2008

Solitary Wave Families In Two Non-Integrable Models Using Reversible Systems Theory, Jonathan Leto

Electronic Theses and Dissertations

In this thesis, we apply a recently developed technique to comprehensively categorize all possible families of solitary wave solutions in two models of topical interest. The models considered are: a) the Generalized Pochhammer-Chree Equations, which govern the propagation of longitudinal waves in elastic rods, and b) a generalized microstructure PDE. Limited analytic results exist for the occurrence of one family of solitary wave solutions for each of these equations. Since, as mentioned above, solitary wave solutions often play a central role in the long-time evolution of an initial disturbance, we consider such solutions of both models here (via the normal …

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Detecting Curved Objects Against Cluttered Backgrounds, Jan Prokaj Jan 2008

Detecting Curved Objects Against Cluttered Backgrounds, Jan Prokaj

Electronic Theses and Dissertations

Detecting curved objects against cluttered backgrounds is a hard problem in computer vision. We present new low-level and mid-level features to function in these environments. The low-level features are fast to compute, because they employ an integral image approach, which makes them especially useful in real-time applications. The mid-level features are built from low-level features, and are optimized for curved object detection. The usefulness of these features is tested by designing an object detection algorithm using these features. Object detection is accomplished by transforming the mid-level features into weak classifiers, which then produce a strong classifier using AdaBoost. The resulting …

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Multi-View Approaches To Tracking, 3d Reconstruction And Object Class Detection, Saad Khan Jan 2008

Multi-View Approaches To Tracking, 3d Reconstruction And Object Class Detection, Saad Khan

Electronic Theses and Dissertations

Multi-camera systems are becoming ubiquitous and have found application in a variety of domains including surveillance, immersive visualization, sports entertainment and movie special effects amongst others. From a computer vision perspective, the challenging task is how to most efficiently fuse information from multiple views in the absence of detailed calibration information and a minimum of human intervention. This thesis presents a new approach to fuse foreground likelihood information from multiple views onto a reference view without explicit processing in 3D space, thereby circumventing the need for complete calibration. Our approach uses a homographic occupancy constraint (HOC), which states that if …

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Improving Branch Prediction Accuracy Via Effective Source Information And Prediction Algorithms, Hongliang Gao Jan 2008

Improving Branch Prediction Accuracy Via Effective Source Information And Prediction Algorithms, Hongliang Gao

Electronic Theses and Dissertations

Modern superscalar processors rely on branch predictors to sustain a high instruction fetch throughput. Given the trend of deep pipelines and large instruction windows, a branch misprediction will incur a large performance penalty and result in a significant amount of energy wasted by the instructions along wrong paths. With their critical role in high performance processors, there has been extensive research on branch predictors to improve the prediction accuracy. Conceptually a dynamic branch prediction scheme includes three major components: a source, an information processor, and a predictor. Traditional works mainly focus on the algorithm for the predictor. In this dissertation, …

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A Framework For Efficient Data Distribution In Peer-To-Peer Networks., Darshan Purandare Jan 2008

A Framework For Efficient Data Distribution In Peer-To-Peer Networks., Darshan Purandare

Electronic Theses and Dissertations

Peer to Peer (P2P) models are based on user altruism, wherein a user shares its content with other users in the pool and it also has an interest in the content of the other nodes. Most P2P systems in their current form are not fair in terms of the content served by a peer and the service obtained from swarm. Most systems suffer from free rider's problem where many high uplink capacity peers contribute much more than they should while many others get a free ride for downloading the content. This leaves high capacity nodes with very little or no …

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Real-Time Realistic Rendering Of Nature Scenes With Dynamic Lighting, Kevin Boulanger Jan 2008

Real-Time Realistic Rendering Of Nature Scenes With Dynamic Lighting, Kevin Boulanger

Electronic Theses and Dissertations

Rendering of natural scenes has interested the scientific community for a long time due to its numerous applications. The targeted goal is to create images that are similar to what a viewer can see in real life with his/her eyes. The main obstacle is complexity: nature scenes from real life contain a huge number of small details that are hard to model, take a lot of time to render and require a huge amount of memory unavailable in current computers. This complexity mainly comes from geometry and lighting. The goal of our research is to overcome this complexity and to …

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Taming Crowded Visual Scenes, Saad Ali Jan 2008

Taming Crowded Visual Scenes, Saad Ali

Electronic Theses and Dissertations

Computer vision algorithms have played a pivotal role in commercial video surveillance systems for a number of years. However, a common weakness among these systems is their inability to handle crowded scenes. In this thesis, we have developed algorithms that overcome some of the challenges encountered in videos of crowded environments such as sporting events, religious festivals, parades, concerts, train stations, airports, and malls. We adopt a top-down approach by first performing a global-level analysis that locates dynamically distinct crowd regions within the video. This knowledge is then employed in the detection of abnormal behaviors and tracking of individual targets …

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Stable Optical Frequency Comb Generation And Applications In Arbitrary Waveform Generation, Signal Processing And Optical Data M, Sarper Ozharar Jan 2008

Stable Optical Frequency Comb Generation And Applications In Arbitrary Waveform Generation, Signal Processing And Optical Data M, Sarper Ozharar

Electronic Theses and Dissertations

This thesis focuses on the generation and applications of stable optical frequency combs. Optical frequency combs are defined as equally spaced optical frequencies with a fixed phase relation among themselves. The conventional source of optical frequency combs is the optical spectrum of the modelocked lasers. In this work, we investigated alternative methods for optical comb generation, such as dual sine wave phase modulation, which is more practical and cost effective compared to modelocked lasers stabilized to a reference. Incorporating these comblines, we have generated tunable RF tones using the serrodyne technique. The tuning range was ±1 MHz, limited by the …

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Digital Signal Processing Techniques For Coherent Optical Communication, Gilad Goldfarb Jan 2008

Digital Signal Processing Techniques For Coherent Optical Communication, Gilad Goldfarb

Electronic Theses and Dissertations

Coherent detection with subsequent digital signal processing (DSP) is developed, analyzed theoretically and numerically and experimentally demonstrated in various fiber-optic transmission scenarios. The use of DSP in conjunction with coherent detection unleashes the benefits of coherent detection which rely on the preservation of full information of the incoming field. These benefits include high receiver sensitivity, the ability to achieve high spectral-efficiency and the use of advanced modulation formats. With the immense advancements in DSP speeds, many of the problems hindering the use of coherent detection in optical transmission systems have been eliminated. Most notably, DSP alleviates the need for hardware …

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Meshfree Approximation Methods For Free-Form Optical Surfaces With Applications To Head-Worn Displays, Ozan Cakmakci Jan 2008

Meshfree Approximation Methods For Free-Form Optical Surfaces With Applications To Head-Worn Displays, Ozan Cakmakci

Electronic Theses and Dissertations

Compact and lightweight optical designs achieving acceptable image quality, field of view, eye clearance, eyebox size, operating across the visible spectrum, are the key to the success of next generation head-worn displays. The first part of this thesis reports on the design, fabrication, and analysis of off-axis magnifier designs. The first design is catadioptric and consists of two elements. The lens utilizes a diffractive optical element and the mirror has a free-form surface described with an x-y polynomial. A comparison of color correction between doublets and single layer diffractive optical elements in an eyepiece as a function of eye clearance …

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Solution Processible Aromatic Polyimides Via Diels Alder Precursor, Saral Shah Jan 2008

Solution Processible Aromatic Polyimides Via Diels Alder Precursor, Saral Shah

Electronic Theses and Dissertations

Aromatic polyimides are interesting materials since they possess outstanding key properties such as thermoxidative stability, high mechanical strength, high modulus, excellent electrical properties, and superior chemical resistance. However, their low solubility makes them difficult to characterize, process and obtain high molecular weight polymer. In this report, we synthesized a series of precursor polymers that contains Diels-Alder (DA) adducts of anthracene. Different dienophiles were tried. These precursor polymers are soluble in common organic solvents such as chloroform and can be easily processed to thin films. Heating the film above 215 degree induce retro-DA reaction, which generated the fully aromatic polyimides in …

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Integrability Of A Singularly Perturbed Model Describing Gravity Water Waves On A Surface Of Finite Depth, Steven Little Jan 2008

Integrability Of A Singularly Perturbed Model Describing Gravity Water Waves On A Surface Of Finite Depth, Steven Little

Electronic Theses and Dissertations

Our work is closely connected with the problem of splitting of separatrices (breaking of homoclinic orbits) in a singularly perturbed model describing gravity water waves on a surface of finite depth. The singularly perturbed model is a family of singularly perturbed fourth-order nonlinear ordinary differential equations, parametrized by an external parameter (in addition to the small parameter of the perturbations). It is known that in general separatrices will not survive a singular perturbation. However, it was proven by Tovbis and Pelinovsky that there is a discrete set of exceptional values of the external parameter for which separatrices do survive the …

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Interannual Variation In Larval Yellow Perch Abundance In Eastern South Dakota Glacial Lakes And Relation To Sympatric Walleye Populations, Andrew C. Jansen Jan 2008

Interannual Variation In Larval Yellow Perch Abundance In Eastern South Dakota Glacial Lakes And Relation To Sympatric Walleye Populations, Andrew C. Jansen

Electronic Theses and Dissertations

Yellow perch Perca flavescens are a popular sportfish in eastern South Dakota glacial lakes. In addition to their recreational importance, yellow perch serve as a prey species for predators. Thus, understanding the factors that affect yellow perch population dynamics is a top priority among fishery managers in South Dakota. The objectives of this study were to 1) estimate the magnitude and duration for a decrease in water temperature that would induce mortality of yellow perch eggs, 2) investigate the relation between climatological variables and larval perch abundance in six eastern South Dakota glacial lakes, and 3) relate long-term larval perch …

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Evaluation Of An Augmentation Of Rocky Mountain Bighorn Sheep At Badlands National Park, South Dakota, Teresa J. Zimmerman Jan 2008

Evaluation Of An Augmentation Of Rocky Mountain Bighorn Sheep At Badlands National Park, South Dakota, Teresa J. Zimmerman

Electronic Theses and Dissertations

Audubon’s (a.k.a. Badlands) bighorn (Ovis canadensis auduboni [Merriam 1901] now O. c. Canadensis [Shaw 1804]), described as a subspecies of bighorn sheep, was extirpated from its range by 1924. In 1964, 22 Rocky Mountain bighorn sheep were translocated from Pikes Peak, Colorado, to Badlands National Park (BNP) in southwestern South Dakota. Based on the estimated effective population size and analysis of molecular data, the bighorn sheep population at BNP underwent a population bottleneck at founding. Recommendations to restore genetic diversity in the BNP population included a mixed-sex augmentation (n > 30) from an outbred, native population of Rocky Mountain bighorn sheep. …

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Nesting And Brood-Rearing Success And Resource Selection Of Greater Sage-Grouse In Northwestern South Dakota, Nicholas W. Kaczor Jan 2008

Nesting And Brood-Rearing Success And Resource Selection Of Greater Sage-Grouse In Northwestern South Dakota, Nicholas W. Kaczor

Electronic Theses and Dissertations

Understanding population dynamics and resource selection is crucial in developing wildlife resource management plans, particularly for sensitive species. Greater sage-grouse (Centrocercus urophasianus) populations have declined range-wide at a rate of 2% per year from 1965 to 2003. In South Dakota, populations have generally declined. Reasons for the decline are mostly attributed to human-induced factors such as sagebrush degradation and removal, improper range management practices, oil and gas exploration, and West Nile virus infection. Sage-grouse occupy habitats at the eastern edge of their range in western South Dakota. We conducted a 2-year study to investigate the nesting and brood-rearing ecology of …

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Phase-Shifting Haar Wavelets For Image-Based Rendering Applications, Mais Alnasser Jan 2008

Phase-Shifting Haar Wavelets For Image-Based Rendering Applications, Mais Alnasser

Electronic Theses and Dissertations

In this thesis, we establish the underlying research background necessary for tackling the problem of phase-shifting in the wavelet transform domain. Solving this problem is the key to reducing the redundancy and huge storage requirement in Image-Based Rendering (IBR) applications, which utilize wavelets. Image-based methods for rendering of dynamic glossy objects do not truly scale to all possible frequencies and high sampling rates without trading storage, glossiness, or computational time, while varying both lighting and viewpoint. This is due to the fact that current approaches are limited to precomputed radiance transfer (PRT), which is prohibitively expensive in terms of memory …

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Lattice-Valued Convergence: Quotient Maps, Hatim Boustique Jan 2008

Lattice-Valued Convergence: Quotient Maps, Hatim Boustique

Electronic Theses and Dissertations

The introduction of fuzzy sets by Zadeh has created new research directions in many fields of mathematics. Fuzzy set theory was originally restricted to the lattice , but the thrust of more recent research has pertained to general lattices. The present work is primarily focused on the theory of lattice-valued convergence spaces; the category of lattice-valued convergence spaces has been shown to possess the following desirable categorical properties: topological, cartesian-closed, and extensional. Properties of quotient maps between objects in this category are investigated in this work; in particular, one of our principal results shows that quotient maps are productive under …

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Optical Solitons In Periodic Structures, Konstantinos Makris Jan 2008

Optical Solitons In Periodic Structures, Konstantinos Makris

Electronic Theses and Dissertations

By nature discrete solitons represent self-trapped wavepackets in nonlinear periodic structures and result from the interplay between lattice diffraction (or dispersion) and material nonlinearity. In optics, this class of self-localized states has been successfully observed in both one-and two-dimensional nonlinear waveguide arrays. In recent years such lattice structures have been implemented or induced in a variety of material systems including those with cubic (Kerr), quadratic, photorefractive, and liquid-crystal nonlinearities. In all cases the underlying periodicity or discreteness leads to new families of optical solitons that have no counterpart whatsoever in continuous systems. In the first part of this dissertation, a …

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Determination Of The Degradation Mechanism For Polychlorinated Biphenyl Congeners Using Mechanically Alloyed Magnesium/Palladium, Robert Devor Jan 2008

Determination Of The Degradation Mechanism For Polychlorinated Biphenyl Congeners Using Mechanically Alloyed Magnesium/Palladium, Robert Devor

Electronic Theses and Dissertations

Polychlorinated biphenyls are a ubiquitous environmental contaminant that can be found today throughout the world in soils and sediments, lakes and rivers, and flora and fauna. PCBs have percolated throughout the food chain, so that almost every human being has a detectable amount of the contaminant within their blood stream. Existing remediation methods include incineration, dredging and landfilling, and microbial degradation, but all of these methods have drawbacks that limit their effectiveness as treatment options. Recently, the use of zero-valent metals as a means of reductive dechlorination has been explored. Using a combination of zero-valent magnesium and catalytic palladium, a …

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Surface Engineering Of Gold Nanoparticles And Their Applications, Qiu Dai Jan 2008

Surface Engineering Of Gold Nanoparticles And Their Applications, Qiu Dai

Electronic Theses and Dissertations

Gold nanoparticles (AuNPs) with their unique sizes, shapes, and properties have generated much enthusiasm over the last two decades, and have been explored for many potential applications. The successful application of AuNPs depends critically on the ability to modify and functionalize their surface to provide stability, compatibility, and special chemical functionality. This dissertation is aimed at exploring the chemical synthesis and surface modification of AuNPs with the effort to (1) control the number of functional groups on the particle surface, and to (2) increase the colloidal stability at the physiological conditions. To control the functionality on the particle surface, a …

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Forensic Analysis Of Automobile Paints By Atomic And Molecular Spectroscopic Methods And Statistical Data Analyses, Erin Mcintee Jan 2008

Forensic Analysis Of Automobile Paints By Atomic And Molecular Spectroscopic Methods And Statistical Data Analyses, Erin Mcintee

Electronic Theses and Dissertations

The analysis of 110 automotive paint samples was conducted for the research presented here. Laser-induced breakdown spectroscopy (LIBS) was the central instrument utilized for analysis although scanning electron microscopy / energy dispersive x-ray spectroscopy (SEM/EDS) and Fourier transform infrared spectroscopy - attenuated total reflection (FTIR-ATR) analyses were also performed. Two separate methods of LIBS analysis of samples were used: a cross sectional analysis and a drill down analysis. SEM/EDS analysis focused on the cross section while FTIR-ATR analysis concentrated on the clearcoat layer. Several different data/statistical analyses were evaluated including principal components analysis (PCA), two tailed t-tests based on several …

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Modeling Transmission Dynamics Of Tuberculosis Including Various Latent Periods, Tracy Atkins Jan 2008

Modeling Transmission Dynamics Of Tuberculosis Including Various Latent Periods, Tracy Atkins

Electronic Theses and Dissertations

The systems of equations created by Blower et al. (1995) and Jia et al. (2007) designed to model the dynamics of Tuberculosis are solved using the computer software SIMULINK. The results are first employed to examine the intrinsic transmission dynamics of the disease through two models developed by Blower et al. (1995). The "simple transmission model" was used primarily to give insight to the behavior of the susceptible, latent, and infectious groups of individuals. Then, we consider a more detailed transmission model which includes several additional factors. This model captures the dynamics of not only the susceptible, latent and infectious …

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Approximating The Spectral Width Of Irradiance Fluctuations With Quasi-Frequency, Andrew Reel Jan 2008

Approximating The Spectral Width Of Irradiance Fluctuations With Quasi-Frequency, Andrew Reel

Electronic Theses and Dissertations

Under weak turbulence theory, we will use the random thin phase screen model and the Kolmogorov power-law spectrum to derive approximate models for the scintillation index, covariance function of irradiance fluctuations, and temporal spectrum of irradiance fluctuations for collimated beams. In addition, we will provide an expression for the quasi-frequency of a collimated beam and investigate the relationship between the quasi-frequency and the maximum width of the normalized temporal spectrum of irradiance for a collimated beam.

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Pseudoquotients: Construction, Applications, And Their Fourier Transform, Mehrdad Khosravi Jan 2008

Pseudoquotients: Construction, Applications, And Their Fourier Transform, Mehrdad Khosravi

Electronic Theses and Dissertations

A space of pseudoquotients can be described as a space of either single term quotients (the injective case) or the quotient of sequences (the non-injective case) where the parent sets for the numerator and the denominator satisfy particular conditions. The first part of this project is concerned with the minimal of conditions required to have a well-defined set of pseudoquotients. We continue by adding more structure to our sets and discuss the effect on the resultant pseudoquotient. Pseudoquotients can be thought of as extensions of the parent set for the numerator since they include a natural embedding of that set. …

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Degree Of Aproximation Of Hölder Continuous Functions, Benjamin Landon Jan 2008

Degree Of Aproximation Of Hölder Continuous Functions, Benjamin Landon

Electronic Theses and Dissertations

Pratima Sadangi in a Ph.D. thesis submitted to Utkal University proved results on degree of approximation of functions by operators associated with their Fourier series. In this dissertation, we consider degree of approximation of functions in Hα,ρ by different operators. In Chapter 1 we mention basic definitions needed for our work. In Chapter 2 we discuss different methods of summation. In Chapter 3 we define the Hα,ρ metric and present the degree of approximation problem relating to Fourier series and conjugate series of functions in the Hα,ρ metric using Karamata (Κλ) means. In Chapter 4 we present the degree of …

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Phase And Amplitude Modulated Ofdm For Dispersion Managed Wdm Systems, Andreas Eisele Jan 2008

Phase And Amplitude Modulated Ofdm For Dispersion Managed Wdm Systems, Andreas Eisele

Electronic Theses and Dissertations

Amplitude and phase modulated optical OFDM (Orthogonal Frequency Division Multiplexing) are analyzed in a 50GBit/s single channel and 40GBit/s 5 channel 512 subcarrier non-ideal dispersion-compensated fiber optic communication systems. PM-OFDM is investigated as an alternative to AM-OFDM to alleviate the problem associated with amplitude-modulated signals in a nonlinear medium. The inherent dispersion compensation capability in OFDM (using a cyclic prefix) allows transmission over a link whose dispersion map is not exactly known. OFDM also mitigates the effects of dispersion slope in wavelength-division multiplexed (WDM) systems. Moreover, the overall dispersion throughout the transmission link may vary due to environmental effects and …

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High Power Mode-Locked Semiconductor Lasers And Their Applications, Shinwook Lee Jan 2008

High Power Mode-Locked Semiconductor Lasers And Their Applications, Shinwook Lee

Electronic Theses and Dissertations

In this dissertation, a novel semiconductor mode-locked oscillator which is an extension of eXtreme Chirped Pulse Amplification (XCPA) is investigated. An eXtreme Chirped Pulse Oscillator (XCPO) implemented with a Theta cavity also based on a semiconductor gain is presented for generating more than 30ns frequency-swept pulses with more than 100pJ of pulse energy and 3.6ps compressed pulses directly from the oscillator. The XCPO shows the two distinct characteristics which are the scalability of the output energy and the mode-locked spectrum with respect to repetition rate. The laser cavity design allows for low repetition rate operation < 100MHz. The cavity significantly reduces nonlinear carrier dynamics, integrated self phase modulation (SPM), and fast gain recovery in a Semiconductor optical Amplifier (SOA). Secondly, a functional device, called a Grating Coupled Surface Emitting Laser (GCSEL) is investigated. For the first time, passive and hybrid mode-locking of a GCSEL is achieved by using saturable absorption in the passive section of GCSEL. To verify the present limitation of the GCSEL for passive and hybrid mode-locking, a dispersion matched cavity is explored. In addition, a Grating Coupled surface emitting Semiconductor Optical Amplifier (GCSOA) is also investigated to achieve high energy pulse. An energy extraction experiment for GCSOA using stretched pulses generated from the colliding pulse semiconductor mode-locked laser via a chirped fiber bragg grating, which exploits the XCPA advantages is also demonstrated. Finally, passive optical cavity amplification using an enhancement cavity is presented. In order to achieve the interferometric stability, the Hänsch-Couillaud Method is employed to stabilize the passive optical cavity. The astigmatism-free optical cavity employing an acousto-optic modulator (AOM) is designed and demonstrated. In the passive optical cavity, a 7.2 of amplification factor is achieved with a 50 KHz dumping rate.

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Automated Regression Testing Approach To Expansion And Refinement Of Speech Recognition Grammars, Raul Dookhoo Jan 2008

Automated Regression Testing Approach To Expansion And Refinement Of Speech Recognition Grammars, Raul Dookhoo

Electronic Theses and Dissertations

This thesis describes an approach to automated regression testing for speech recognition grammars. A prototype Audio Regression Tester called ART has been developed using Microsoft's Speech API and C#. ART allows a user to perform any of three tasks: automatically generate a new XML-based grammar file from standardized SQL database entries, record and cross-reference audio files for use by an underlying speech recognition engine, and perform regression tests with the aid of an oracle grammar. ART takes as input a wave sound file containing speech and a newly created XML grammar file. It then simultaneously executes two tests: one with …

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Alayzing The Effects Of Modularity On Search Spaces, Ozlem Garibay Jan 2008

Alayzing The Effects Of Modularity On Search Spaces, Ozlem Garibay

Electronic Theses and Dissertations

We are continuously challenged by ever increasing problem complexity and the need to develop algorithms that can solve complex problems and solve them within a reasonable amount of time. Modularity is thought to reduce problem complexity by decomposing large problems into smaller and less complex subproblems. In practice, introducing modularity into evolutionary algorithm representations appears to improve search performance; however, how and why modularity improves performance is not well understood. In this thesis, we seek to better understand the effects of modularity on search. In particular, what are the effects of module creation on the search space structure and how …

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