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Articles 3301 - 3330 of 4194
Full-Text Articles in Physical Sciences and Mathematics
High Power Mode-Locked Semiconductor Lasers And Their Applications, Shinwook Lee
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.
Ultrashort Laser Pulse Interaction With Photo-Thermo-Refractive Glass, Leo Siiman
Ultrashort Laser Pulse Interaction With Photo-Thermo-Refractive Glass, Leo Siiman
Electronic Theses and Dissertations
Photo-thermo-refractive (PTR) glass is an ideal photosensitive material for recording phase volume holograms. It is a homogeneous multi-component silicate glass that demonstrates all the advantages of optical glass: thermal stability, high laser damage threshold, and a wide transparency range. Moreover the ability to record phase patterns (i.e. spatial refractive index variations) into PTR glass has resulted in the fabrication of volume holograms with diffraction efficiency greater than 99%. The conventional method of recording a hologram in PTR glass relies on exposure to continuous-wave ultraviolet laser radiation. In this dissertation the interaction between infrared ultrashort laser pulses and PTR glass is …
Design And Optimization Of Nanostructured Optical Filters, Jeremiah Brown
Design And Optimization Of Nanostructured Optical Filters, Jeremiah Brown
Electronic Theses and Dissertations
Optical filters encompass a vast array of devices and structures for a wide variety of applications. Generally speaking, an optical filter is some structure that applies a designed amplitude and phase transform to an incident signal. Different classes of filters have vastly divergent characteristics, and one of the challenges in the optical design process is identifying the ideal filter for a given application and optimizing it to obtain a specific response. In particular, it is highly advantageous to obtain a filter that can be seamlessly integrated into an overall device package without requiring exotic fabrication steps, extremely sensitive alignments, or …
Controlled Deposition Of Magnetic Molecules And Nanoparticles On Atomically Flat Gold Surfaces, Md. Firoze Haque
Controlled Deposition Of Magnetic Molecules And Nanoparticles On Atomically Flat Gold Surfaces, Md. Firoze Haque
Electronic Theses and Dissertations
In this thesis I am presenting a detailed study to optimize the deposition of magnetic molecules and gold nanoparticles in atomically flat surfaces by self-assembling them from solution. Epitaxially grown and atomically flat gold surface on mica is used as substrate for this study. These surfaces have roughness of the order one tenth of a nanometer and are perfect to image molecules and nanoparticles in the 1-10 nanometers range. The purpose of these studies is to find the suitable parameters and conditions necessary to deposit a monolayer of nano-substance on chips containing gold nanowires which will eventually be used to …
Meshfree Approximation Methods For Free-Form Optical Surfaces With Applications To Head-Worn Displays, Ozan Cakmakci
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 …
The Development Of A "Genetic Eyewitness" Profiling System For Low Template Forensic Specimens: Identification Of Novel Protein, Rna, And Dna Biomarkers, Erin Hanson
Electronic Theses and Dissertations
In many criminal investigations, valuable information regarding the physical appearance of suspected perpetrators or the time and order of events that transpired are provided by eyewitness accounts. However, the information obtained from eyewitnesses is often constrained by human recollection or subjective accounts and provides a biased description of the perpetrator's appearance or an inaccurate time line of events. Additionally, in numerous situations eyewitness accounts may not be available. An increasing reliance therefore is placed on the biological evidence recovered during criminal investigations to act as a silent witness, providing unbiased and scientific information that may aid in the resolution of …
The Identification Of Ignitable Liquids In The Presence Of Pyrolysis Products: Generation Of A Pyrolysis Product Database, Joseph Castelbuono
The Identification Of Ignitable Liquids In The Presence Of Pyrolysis Products: Generation Of A Pyrolysis Product Database, Joseph Castelbuono
Electronic Theses and Dissertations
The fire debris analyst is often faced with the complex problem of identifying ignitable liquid residues in the presence of products produced from pyrolysis and incomplete combustion of common building and furnishing materials. The purpose of this research is to investigate a modified destructive distillation methodology provided by the Florida Bureau of Forensic Fire and Explosive Analysis to produce interfering product chromatographic patterns similar to those observed in fire debris case work. The volatile products generated during heating of substrate materials are extracted from the fire debris by passive headspace adsorption and subsequently analyzed by GC-MS. Low density polyethylene (LDPE) …
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 …
Integrability Of A Singularly Perturbed Model Describing Gravity Water Waves On A Surface Of Finite Depth, Steven Little
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 …
Solution Processible Aromatic Polyimides Via Diels Alder Precursor, Saral Shah
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 …
A Numerical Analysis Approach For Estimating The Minimum Traveling Wave Speed For An Autocatalytic Reaction, Erika Blanken
A Numerical Analysis Approach For Estimating The Minimum Traveling Wave Speed For An Autocatalytic Reaction, Erika Blanken
Electronic Theses and Dissertations
This thesis studies the traveling wavefront created by the autocatalytic cubic chemical reaction A + 2B → 3B involving two chemical species A and B, where A is the reactant and B is the auto-catalyst. The diffusion coefficients for A and B are given by DA and DB. These coefficients differ as a result of the chemical species having different size and/or weight. Theoretical results show there exist bounds, v* and v*, depending on DB/DA, where for speeds v ≥ v*, a traveling wave solution exists, while for speeds v < v*, a solution does not exist. Moreover, if DB ≤ DA, and v* and v* are similar to one another and in the order of DB/DA when it is small. On the other hand, when DA ≤ DB there exists a minimum speed vmin, such that there is a traveling wave solution if the speed v > vmin. The determination of vmin is very important in determining …
Fractal Interpolation, Gayatri Ramesh
Fractal Interpolation, Gayatri Ramesh
Electronic Theses and Dissertations
This thesis is devoted to a study about Fractals and Fractal Polynomial Interpolation. Fractal Interpolation is a great topic with many interesting applications, some of which are used in everyday lives such as television, camera, and radio. The thesis is comprised of eight chapters. Chapter one contains a brief introduction and a historical account of fractals. Chapter two is about polynomial interpolation processes such as Newton s, Hermite, and Lagrange. Chapter three focuses on iterated function systems. In this chapter I report results contained in Barnsley s paper, Fractal Functions and Interpolation. I also mention results on iterated function system …
Pseudoquotients: Construction, Applications, And Their Fourier Transform, Mehrdad Khosravi
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. …
Degree Of Aproximation Of Hölder Continuous Functions, Benjamin Landon
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 …
Phase And Amplitude Modulated Ofdm For Dispersion Managed Wdm Systems, Andreas Eisele
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 …
Development And Forensic Application Of Dye Probe Fluorescence Resonance Energy Transfer For Improved Detection Of Changes In Dn, Micah Halpern
Development And Forensic Application Of Dye Probe Fluorescence Resonance Energy Transfer For Improved Detection Of Changes In Dn, Micah Halpern
Electronic Theses and Dissertations
Discovering, screening, and associating changes in DNA sequence are important to a broad range of disciplines and play a central role in Forensic Science. The typical types of changes include sequence variations [single nucleotide polymorphisms (SNP)] and length variations [short tandem repeats (STR)]. The steps for forensic DNA sample processing are similar for both types of changes but diverge at the point of detection. A number of approaches are being explored for SNP genotyping while STR analysis primarily consists of size-based analysis by capillary electrophoresis. Limitations exist for all current detection methods that pose significant impacts to forensic analysis. Bi-allelic …
Real-Time Realistic Rendering Of Nature Scenes With Dynamic Lighting, Kevin Boulanger
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 …
Modeling Transmission Dynamics Of Tuberculosis Including Various Latent Periods, Tracy Atkins
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 …
Comparing Assessment Methods As Predictors Of Student Learning In Undergraduate Mathematics, Nichole Shorter
Comparing Assessment Methods As Predictors Of Student Learning In Undergraduate Mathematics, Nichole Shorter
Electronic Theses and Dissertations
This experiment was designed to determine which assessment method: continuous assessment (in the form of daily in-class quizzes), cumulative assessment (in the form of online homework), or project-based learning, best predicts student learning (dependent upon posttest grades) in an undergraduate mathematics course. Participants included 117 university-level undergraduate freshmen enrolled in a course titled "Mathematics for Calculus". Initially, a multiple regression model was formulated to model the relationship between the predictor variables (the continuous assessment, cumulative assessment, and project scores) versus the outcome variable (the posttest scores). However, due to the possibility of multicollinearity present between the cumulative assessment predictor variable …
Chromatographic And Mass Spectral Analyses Of Oligosaccharides And Indigo Dye Extracted From Cotton Textiles With Manova And Ano, Jessica Frisch
Chromatographic And Mass Spectral Analyses Of Oligosaccharides And Indigo Dye Extracted From Cotton Textiles With Manova And Ano, Jessica Frisch
Electronic Theses and Dissertations
Research was conducted on thirteen 100% cotton denim samples using an acid wash, established by Murray, to extract oligosaccharides from the cellulosic material. The oligosaccharide ion groups (+, +, and +) for molecules with degrees of polymerization between two and seven (DP2-DP7) were analyzed using liquid chromatography coupled to mass spectrometry with an electrospray ionization interface (LC-ESI-MS). The results were compared using the least-squares means in a Multivariate ANOVA (MANOVA) test followed by Univariate ANOVA and Tukey HSD tests and demonstrated that the method could correctly determine that two samples were statistically different 85.9% of the time when analyzing the …
Multi-View Approaches To Tracking, 3d Reconstruction And Object Class Detection, Saad Khan
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 …
Interannual Variation In Larval Yellow Perch Abundance In Eastern South Dakota Glacial Lakes And Relation To Sympatric Walleye Populations, Andrew C. Jansen
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 …
Semantic Video Retrieval Using High Level Context, Yusuf Aytar
Semantic Video Retrieval Using High Level Context, Yusuf Aytar
Electronic Theses and Dissertations
Video retrieval - searching and retrieving videos relevant to a user defined query - is one of the most popular topics in both real life applications and multimedia research. This thesis employs concepts from Natural Language Understanding in solving the video retrieval problem. Our main contribution is the utilization of the semantic word similarity measures for video retrieval through the trained concept detectors, and the visual co-occurrence relations between such concepts. We propose two methods for content-based retrieval of videos: (1) A method for retrieving a new concept (a concept which is not known to the system and no annotation …
Geoarchaeological Investigations Along The Tambo-Ilo Coast Of Southern Peru, Louis Fortin
Geoarchaeological Investigations Along The Tambo-Ilo Coast Of Southern Peru, Louis Fortin
Electronic Theses and Dissertations
The south coast of Peru has had a long history of cultural occupancy from the Preceramic through Chiribaya periods, and into Spanish Colonial / Post-Colonial periods. Procurement and modification of lithic material was an important activity throughout each of these periods but remains an under-explored dataset for late Prehispanic and Colonial populations in the region. Analysis at the Cola de Zorro archaeological site and within the Tambo-Ilo region examined the relation cultures have with their environment through a geoarchaeological analysis of the local geology and the distribution of lithics. Surveys were completed at Cola de Zorro in the quebrada drainage, …
Investigating The Factors Affecting Faculty Members' Decision To Teach Or Not To Teach Online In Higher Education, Yurui Zhen
Electronic Theses and Dissertations
This study investiaged the important factors influencing faculty members' decision to use or not to use any form of online course management applications (OCMA) in higher education. Today, with the rapid growth of the internet, many higher educational institutions are using technology in courses or offering online courses and programs. With training and support, many faculty members use some form of OCMA in their teaching, but some faculty members choose not to. Administrators may benefit from understanding faculty use of general technology in teaching in higher education by exploring how faculty members make their decisions in the use of specific …
Comparison Of Career Statistics And Season Statistics In Major League Baseball, Mark Joseph Ammons
Comparison Of Career Statistics And Season Statistics In Major League Baseball, Mark Joseph Ammons
Electronic Theses and Dissertations
This is a comparison of statistics for some of the best seasons and careers of players from Major League Baseball; using data collected on batting average, at bat to homerun ratio, and earned run average. Two teams were created, composed of season leaders and career leaders, chosen for their outstanding offensive and pitching abilities, and were pitted against one another to determine superiority. These two teams also compared against a team from each era of major league baseball. The season and career leaders challenged, the 1918 Boston Red Sox, 1927 New York Yankees, 1955 Brooklyn Dodgers, 1961 New York Yankees, …
Toward A New Social Contract: A Tripartite Mixed-Methods Analysis Of Social Sustainability At Three Land-Grant Universities, Lyndsay Josephine Agans
Toward A New Social Contract: A Tripartite Mixed-Methods Analysis Of Social Sustainability At Three Land-Grant Universities, Lyndsay Josephine Agans
Electronic Theses and Dissertations
Increasingly, colleges and universities in the United States are adapting toward a model of behavior that incorporates issues of sustainability. This adaptation in universities and in society has implications on the organizational and nation-state level, the very core of which may serve to reshape the social contract between the two. In addition to supplying a strong counter-hegemonic argument that alters the competitive economic agenda-setting paradigm, this study serves as a tripartite comparative case study analysis of university adaptation toward social sustainability. By employing a social capital lens to understanding social sustainability in higher education, this study seeks to examine the …
Integrated Optical Spr (Surface Plasmon Resonance) Sensor Based On Optoelectronic Platform, Hyungseok Bang
Integrated Optical Spr (Surface Plasmon Resonance) Sensor Based On Optoelectronic Platform, Hyungseok Bang
Electronic Theses and Dissertations
Current major demands in SPR sensor development are system miniaturization and throughput improvement. Structuring an array of integrated optical SPR sensor heads on a semiconductor based optoelectronic platform could be a promising solution for those issues, since integrated optical waveguides have highly miniaturized dimension and the optoelectronic platform enables on-chip optical-to-electrical signal conversion. Utilizing a semiconductor based platform to achieve optoelectronic functionality poses requirements to the senor head; the sensor head needs to have reasonably small size while it should have reasonable sensitivity and fabrication tolerance. This research proposes a novel type of SPR sensor head and demonstrates a fabricated …
Cholesteric Liquid Crystal Photonic Crystal Lasers And Photonic Devices, Ying Zhou
Cholesteric Liquid Crystal Photonic Crystal Lasers And Photonic Devices, Ying Zhou
Electronic Theses and Dissertations
This dissertation discusses cholesteric liquid crystals (CLCs) and polymers based photonic devices including one-dimensional (1D) photonic crystal lasers and broadband circular polarizers. CLCs showing unique self-organized chiral structures have been widely used in bistable displays, flexible displays, and reflectors. However, the photonic band gap they exhibit opens a new way for generating laser light at the photonic band edge (PBE) or inside the band gap. When doped with an emissive laser dye, cholesteric liquid crystals provide distributed feedback so that mirrorless lasing is hence possible. Due to the limited surface anchoring, the thickness of gain medium and feedback length is …
Digital Signal Processing Techniques For Coherent Optical Communication, Gilad Goldfarb
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 …