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Topology And Control Investigation For Low-Voltage High-Current Isolated Dc-Dc Converters, Hong Mao

Retrospective Theses and Dissertations

High conversion efficiency and fast transient response at high switching frequency are the two main challenges for low-voltage high-current DC-DC converters, which are the motivations of the dissertation work.

To reduce the switching power loss, soft switching is a desirable technique to keep power loss under control at high switching frequencies. A Duty-Cycle-Shift (DCS) concept is proposed for half-bridge DC-DC converters to reduce switching loss. The concept of this new control scheme is shifting one of the two symmetric PWM driving signals close to the other, such that ZVS can be achieved for the lagging switch due to the shortened …

Forecasting The Onset Of Cloud-Ground Lightning Using S-Pol And Nldn Data, Kartik Ramakrishnan

Electronic Theses and Dissertations

The maximum number of thunderstorms in the United States occur in Central Florida. The cloud-ground lightning from these storms is responsible for extensive damage to life and property. The lightning from these storms is also responsible for delays and cancellations of space shuttle launch attempts at the Kennedy Space Center (KSC) and the 45th Space Wing unmanned launches at Cape Canaveral launch facilities. For these and other reasons accurate forecasting of cloud-ground lightning is of crucial importance. The second phase of NASA's Tropical Rainfall Measuring Mission Texas and Florida Underflights project (TEFLUN-B) was conducted between 1st August and 30th September, …

George Liska's Realist Alliance Theory, And The Transformation Of Nato, Sergey Kireyev

Electronic Theses and Dissertations

In many aspects, political theory forms a subjective structure of this abstract science. Perhaps, it is due to the fact that unlike natural sciences or mathematics, social sciences often lack the privilege of testing the theories in absolute and unadulterated conditions. Nonetheless, such nature of the science allows for a certain degree of flexibility, when applying political theories to real-world phenomena. Alliances and coalitions in international relations form the backbone of the theory, concerning IR scholars with two main questions: Why do alliances and coalitions form? And, what keeps alliances and coalitions together? As the core of my research, I …

Measuring The Effect Of Erratic Demandon Simulated Multi-Channel Manuf, Nancy Kohan

Electronic Theses and Dissertations

To handle uncertainties and variabilities in production demands, many manufacturing companies have adopted different strategies, such as varying quoted lead time, rejecting orders, increasing stock or inventory levels, and implementing volume flexibility. Make-to-stock (MTS) systems are designed to offer zero lead time by providing an inventory buffer for the organizations, but they are costly and involve risks such as obsolescence and wasted expenditures. The main concern of make-to-order (MTO) systems is eliminating inventories and reducing the non-value-added processes and wastes; however, these systems are based on the assumption that the manufacturing environments and customers' demand are deterministic. Research shows that …

Evaluation Of The Photo-Induced Structural Mechanisms In Chalcogenide, Cedric Lopez

Electronic Theses and Dissertations

Chalcogenide glasses and their use in a wide range of optical, electronic and memory applications, has created a need for a more thorough understanding of material property variation as a function of composition and in geometries representative of actual devices. This study evaluates compositional dependencies and photo-induced structural mechanisms in As-S-Se chalcogenide glasses. An effective fabrication method for the reproducible processing of bulk chalcogenide materials has been demonstrated and an array of tools developed, for the systematic characterization of the resulting material's physical and optical properties. The influence of compositional variation on the physical properties of 13 glasses within the …

Damage Modeling Method For Turbine Compressor Blade Tuning, Gennadiy Afanasiev

Electronic Theses and Dissertations

The thesis presents a method of evaluation for blade damage in Combustion Turbine Compressor Section. This method involves use of multiple domains within a single Finite Element Model to predict the effect of damage on the blade properties. This approach offers significant time and effort savings when compared to traditional evaluation methods of similar problems. It is demonstrated via examples that the multi-domain modeling approach yields acceptable accuracy results. The economical implications of described method are readily applicable to both the industrial and the aerospace Combustion Turbine fields. It is economically impractical to replace the blade at each damage occurrence. …

Sub-Optimal Ultra-Wide Band Receivers, Nilesh Bhuvanendran

Electronic Theses and Dissertations

Ultra-wide Band (UWB) has sparked a lot of interest lately from the industry and academia. The growing capacity of the wireless industry is requires a new communication system that satisfies the high data rate which does not interfere with existing RF systems. UWB promises to be this new technology. UWB also promises low power, low cost and flexibility. The UWB Channel opens up a huge new wireless channel with Giga Hertz Capacities as well as the highest spatial capacities measured in bits per hertz per square meter. When properly implemented UWB channel can share spectrum with traditional radio systems without …

Exploring Life Through The Depths Of The Subconscious Mind, Urszula Blaszak

HIM 1990-2015

The animation short I have produced is very personal on the subconscious level. There is no single theme; the narrator is the viewer. It is a dream sequence aiming to achieve Kafkaesque quality. About four minutes long, combined with dynamic music this piece of work is my reaction to society, to my life, ever changing surroundings, my traveling, childhood memories, and man-woman relationships, education, feelings, everyday worries, and everything else that I at the moment of producing felt like adding. It is suppose to be a portrait of me inside. I tried to recreate the everyday chaos of thoughts, emotions, …

Camera System Support For Highway Transportation Using Mobile Devices, Le Minh

Electronic Theses and Dissertations

With the very fast growing technology in wireless, advancement in hardware and the dramatically falling cost of mobile computing devices such as PDA, handheld device, People nowadays can have a personal device that fits in their hand but has computing power as a desktop did few years ago. The same device now is able to communicate over a wireless network and view office document at the same time. The combination of size, power and flexibility makes the personal devices increasingly appear in many aspects of life. In this proposal, we focus on a simple yet useful application of mobile devices …

Extensions Of Operators, D. Han, D. Larson, Z. Pan, W. Wogen

Faculty Bibliography 2000s

We introduce the concept of the extension spectrum of a Hilbert space operator. This is a natural subset of the spectrum which plays an essential role in dealing with certain extension properties of operators. We prove that it has spectral-like properties and satisfies a holomorphic version of the Spectral Mapping Theorem. We establish structural theorems for algebraic extensions of triangular operators which use the extension spectrum in a natural way. The extension spectrum has some properties in common with the Kato spectrum, and in the final section we show how they are different and we examine their inclusion relationships.

Direct Detection Differential Polarization-Phase-Shift Keying Based On Jones Vector, Yan Han, Guifang Li

Faculty Bibliography 2000s

In this paper, differential polarization-phase-shift keying (DPolPSK) is proposed for digital lightwave communication, in which information is encoded in both polarization and phase. The DPolPSK symbols are demodulated by optical delayed interference and electrical multilevel detection, without using any polarization control or polarization selection at the receiver. Simulation results show that single-channel error-free transmission at 20 Gb/s (10 Gsymbol/s) through 25 spans of 100 km standard single-mode fiber is possible. Unlike for DPSK, the Gaussian BER estimation method is found to be reasonably accurate for this new modulation format. The constellation diagram of DPolPSK can be represented by a set …

Thermodynamic Model Of Electric-Field-Induced Pattern Formation In Binary Dielectric Fluids, M. D. Johnson, X. Duan, Brett Riley, Aniket Bhattacharya, Weili Luo

Faculty Bibliography 2000s

An electric-field-induced phase transition and pattern formation in a binary dielectric fluid layer are studied using a coarse-grained free-energy functional. The electrostatic part of the free energy is a nonlinear functional of the dielectric function, which depends in turn on the local colloidal concentration. We determine the phase coexistence curve and find that beyond a critical electric field the system phase separates. Accompanying the phase separation are patterns similar to those observed in a spinodal decomposition of an ordinary binary fluid. The temporal evolution of the phase separating patterns are discussed both analytically and numerically by integrating a Cahn-Hilliard type …

Model For A Partially Coherent Gaussian Beam In Atmospheric Turbulence With Application In Lasercom, Olga Korotkova, Larry C. Andrews, Ronald L. Phillips

Faculty Bibliography 2000s

Analytic expressions for the mutual coherence function (MCF) and the scintillation index of a partially coherent lowest order Gaussian beam wave propagating through the atmosphere (based on Kolmogorov spectrum model) are developed for the pupil plane of a receiving system. Partial coherence of the beam is modeled as a thin (complex) phase screen with Gaussian spectrum (Rytov theory and ABCD ray matrices are applied). The relation between the second- and fourth-order statistics for a beam with any degree of coherence in the atmosphere is introduced with the help of "effective" beam parameters, deduced from the free-space MCF. In particular, the …

Using Noninvasive Wearable Computers To Recognize Human Emotions From Physiological Signals, Christine Laetitia Lisetti, Fatma Nasoz

Faculty Bibliography 2000s

We discuss the strong relationship between affect and cognition and the importance of emotions in multimodal human computer interaction (HCl) and user modeling. We introduce the overall paradigm for our multimodal system that aims at recognizing its users' emotions and at responding to them accordingly depending upon the current context or application. We then describe the design of the emotion elicitation experiment we conducted by collecting, via wearable computers, physiological signals from the autonomic nervous system (galvanic skin response, heart rate, temperature) and mapping them to certain emotions (sadness, anger, fear, surprise, frustration, and amusement). We show the results of …

Variable Optical Attenuator Based On Polymer Stabilized Twisted Nematic Liquid Crystal, Yan-Qing Lu, Fang Du, Yi-Hsin Lin, Shin-Tson Wu

Faculty Bibliography 2000s

A variable optical attenuator (VOA) based on polymer stabilized twisted nematic (PSTN) liquid crystal (LC) is demonstrated. Comparing with the normal twisted nematic LC-based VOA, PSTN exhibits a much faster response time. Moreover, the polymer networks effectively eliminate the backflow effect which exists in the normal TNLC cell. The attenuation mechanism of the PSTN LC was studied. Both polarization rotation and light scattering effects are found to contribute to the optical attenuation. The ratio between these two mechanisms can be adjusted by changing the polymer concentration and polymer network domain size.

Polarization Switch Using Thick Holographic Polymer-Dispersed Liquid Crystal Grating, Yan-Qing Lu, Fang Du, Shin-Tson Wu

Faculty Bibliography 2000s

Theoretical study of the optical diffraction properties of holographic polymer-dispersed liquid crystal (HPDLC)-based thick volume grating was presented. It is found that the HPDLC grating can selectively diffract the s-polarized light only, p-polarized light only, or both s and p beams by selecting suitable grating parameters. When an electric field is applied, the s- and p-polarized lights exhibit different diffraction behaviors and, thus, the tunable dual-state or three-state polarization switching could be realized.

Model Of Wide-Angle Optical Field Propagation Using Scalar Diffraction Theory, Vesselin Shaoulov, Ravi Vijaya Satya, Guy Schiavone, Eric Clarkson, Jannick Rolland

Faculty Bibliography 2000s

A generalized nonparaxial theoretical framework based on the scalar diffraction theory is developed to describe the propagation of an optical field through a linear optical system with quasi-monochromatic spatially incoherent illumination. Software implementation of this theoretical framework on single and multiple processor platforms was developed and simulated results of the imaging process through optical aberration-corrected optics are presented for both in-focus and out-of-focus imaging, validating the first-order nonparaxial model.

New Grayscale Hit-Miss Operator, Arthur R. Weeks, Lloyd J. Sartor, Samuel S. Richie

Faculty Bibliography 2000s

The morphological binary hit-miss operator has been used extensively to locate features within a binary image. We propose a grayscale hit-miss operator that detects signal shapes and is applicable to scalar-valued functions on one, two, or more dimensions. The hit and miss structuring elements define the lower and upper bounds of the signal: If a signal lies between the hit and miss templates, then the hit-miss operator will produce a one output; otherwise, it will respond with zero. We incorporate a fuzzy logic element to the hit-miss operator to indicate how strongly the signal matches the hit-miss templates.

All-Optical Multiphoton Absorption Figures Of Merit: Polydiacetylene Poly (Bis Para-Toluene Sulfonate) Of 2,4-Hexadiyne-1,6 Diol, Fumiyo Yoshino, Sergey Polyakov, George I. Stegeman

Faculty Bibliography 2000s

The all-optical switching figures of merit are reported for the single crystal PTS (polydiacetylene poly (bis para-toluene sulfonate) of 2,4-hexadiyne-1,6 diol). Included are the effects of the absorption mechanisms from linear up to four-photon over the wavelength range 1.2-2.2 mum.

Optical Nonresonance And Two-Photon Resonance Breathers In Anisotropic Media, G. T. Adamashvili, D. J. Kaup

Faculty Bibliography 2000s

Anisotropic optical crystals with two-photon resonance impurity atoms are shown to have three different mechanisms of the formation of breathers depending on the direction of the wave propagation and on the symmetry of the medium. Explicit analytic expressions for the parameters of nonresonance and resonance two-photon breathers of extraordinary waves are obtained. It is shown that, unlike one-photon breathers, for two-photon breathers in the media with quadratic susceptibilities and the crystal classes 3, 3m, 4, 4mm, 6, 6mm, and Kerr media two different structures of the breathers zones are realized.

In Situ Synthesis Of Carbon Nanotubes Decorated With Palladium Nanoparticles Using Arc-Discharge In Solution Method, Debasis Bera, Suresh C. Kuiry, Matthew Mccutchen, Sudipta Seal, Helge Heinrich, Grady C. Slane

Faculty Bibliography 2000s

A unique, simple, inexpensive, and one-step synthesis route to produce carbon nanotubes (CNTs) decorated with palladium nanoparticles using a simplified dc arc-discharge in solution is reported. Zero-loss energy filtered transmission electron microscopy and scanning transmission electron microscopy confirm the presence of 3 nm palladium nanoparticles. Such palladium nanoparticles form during the reduction of palladium tetra-chloro-square-planar complex. The deconvoluted x-ray photoelectron spectroscopy envelope shows the presence of palladium on the decorated CNTs. The energy dispersive spectroscopy suggests no functionalization of atomic chlorine to the sidewall of the CNTs. The presence of dislodged graphene sheets with wavy morphology supports the formation of …

Generalized Optical Theorem For Reflection, Transmission, And Extinction Of Power For Scalar Fields, P. Scott Carney, John C. Schotland, Emil Wolf

Faculty Bibliography 2000s

We present a derivation of the optical theorem that makes it possible to obtain expressions for the extinguished power in a very general class of problems not previously treated. The results are applied to the analysis of the extinction of power by a scatterer in the presence of a lossless half space. Applications to microscopy and tomography are discussed.

Three-Wave Solitons And Continuous Waves In Media With Competing Quadratic And Cubic Nonlinearities, Min Chen, D. J. Kaup, Boris A. Malomed

Faculty Bibliography 2000s

We formulate a general model of three-wave optical interactions (in the spatial domain), which combines quadratic (chi((2))) and cubic (chi((3))) nonlinearities, the latter including four-wave mixing. The model can be realized in chi((2)) materials where an effective chi((3)) nonlinearity is engineered by means of the quasi-phase-matching technique. Both self-focusing and self-defocusing chi((3)) nonlinearities are considered. The birefringence of the two fundamental-frequency (FF) waves is taken into regard. Several types of solitons in this system are found, by means of the variational approximation and numerical methods. These are exact single-component solitons and generic three-wave (3W) ones, which are classified by relative …

The Use Of Pyrosequencing For The Analysis Of Y Chromosome Single Nucleotide Polymorphisms, Jeremy Charles Fletcher

Electronic Theses and Dissertations

The potential value of the Y chromosome for forensic applications has been recognized for some time with the current work dedicated to Short Tandem Repeat analysis and Single Nucleotide Polymorphism (SNP) discovery. This study examined the ability of two different SNP analysis methods to determine if they could be utilized in forensic applications and ultimately be developed into an established system for Y chromosome SNP analysis. This study examined two principle SNP analysis systems: single base extension and Pyrosequencing. Pyrosequencing was determined to be superior to single base extension, due to the wealth of information provided with sequencing and the …

Nonlinear Adaptive Estimation Andits Application To Synchronization Of Lorenz System, Yufang Jin

Electronic Theses and Dissertations

Synchronization and estimation of unknown constant parameters for Lorenz-type transmitter are studied under the assumption that one of the three state variables is not transmitted and that transmitter parameters are not known apriori. An adaptive algorithm is proposed to estimate both the state and system parameters. Since Lorenz system shows the property of sensitivity to initial conditions and evolves in different mode with parameter variation, an equivalent system is introduced. The adaptive observer is designed based on this equivalent system without any requirement on initial conditions of the observer. It is shown by Lyapunov arguments and persistent excitation analysis that …

The Wave Structure Function And Temporal Frequency Spread In Weak To Strong Optical Turbulence, Aaron J. Masino

Electronic Theses and Dissertations

This paper presents analytic expressions for the wave structure function, frequency spread of the temporal frequency spectrum, and the temporal frequency spectrum of optical signals propagating through a random medium, specifically the Earth’s atmosphere. The results are believed to be valid for all optical turbulence conditions. These expressions are developed using the Rytov approximation method. Generally, the validity of statistical quantities obtained via this method is restricted to conditions of weak optical turbulence. However, in this work, by using a modification of the effective atmospheric spectral model presented by Andrews et al. for scintillation index, wave structure function expressions have …

Method For Determination Of Singlet Oxygen Quantum Yields For New Fluorene-Based Photosensitizers In Aqueous Media For The Advancement Of Photodynamic Therapy, Wade William Grabow

Electronic Theses and Dissertations

Photodynamic therapy (PDT) has been investigated over the past three decades and is currently an approved therapeutic modality for skin cancer, the treatment of superficial bladder, early lung and advanced esophageal cancers, and age-related macular degeneration in a number of countries. In PDT, the absorption of light by a chromophore generates cytotoxic species such as reactive singlet oxygen, leading to irreversible destruction of the treated tissue. The measurement of the singlet oxygen quantum yield is an important determinant used to evaluate the efficiency of new photodynamic therapy agents developed in the laboratory, to screen potential photosensitizers in aqueous media.The singlet …

Chemical Structure - Nonlinear Optical Property Relationships For A Series Of Two-Photon Absorbing Fluorene Molecules, Joel Mccajah Hales

Electronic Theses and Dissertations

This dissertation reports on the investigation of two-photon absorption (2PA) in a series of fluorenyl molecules. Several current and emerging technologies exploit this optical nonlinearity including two-photon fluorescence imaging, three-dimensional microfabrication, site-specific photodynamic cancer therapy and biological caging studies. The two key features of this nonlinearity which make it an ideal candidate for the above applications are its quadratic dependence on the incident irradiance and the improved penetration into absorbing media that it affords. As a consequence of the burgeoning field which exploits 2PA, it is a goal to find materials that exhibit strong two-photon absorbing capabilities. Organic materials are …

Effects Of Voluntary Control On Performance Response Under Stress., Christina Shawn Morris

Electronic Theses and Dissertations

Recent stressful environments within military and non-military domains are producing a new challenge for the lab-based study of stress on task performance, one that requires knowledge of underlying cognitive-motivational and goal orientation factors. Results of recent stress on task performance research traditionally employ metaphorical explanations (i.e., resource theory) in order to rapidly apply stimulus-response outcomes to the real world counterparts. This dissertation provides an alternative perspective about these metaphorical, or black box, interpretations and reveals how they may be confounded with respect to the intended real world counterpart. To examine how voluntary human control can influence traditional stress/no-stress research findings, …

The Effects Of Differential Item Functioning On Predictive Bias, Damon Bryant

Electronic Theses and Dissertations

The purpose of this research was to investigate the relation between measurement bias at the item level (differential item functioning, dif) and predictive bias at the test score level. Dif was defined as a difference in the probability of getting a test item correct for examinees with the same ability but from different subgroups. Predictive bias was defined as a difference in subgroup regression intercepts and/or slopes in predicting a criterion. Data were simulated by computer. Two hypothetical subgroups (a reference group and a focal group) were used. The predictor was a composite score on a dimensionally complex test with …