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Articles 241 - 270 of 360
Full-Text Articles in Electrical and Electronics
Data Communication With A Nano-Satellite Using Satellite Personal Communication Networks (S-Pcns), Khudeja Khan
Data Communication With A Nano-Satellite Using Satellite Personal Communication Networks (S-Pcns), Khudeja Khan
Electronic Theses and Dissertations
Satellites typically communicate with locations on the ground to receive commands and send data back. Establishing reliable communications generally requires dedicated ground stations, which in turn require hardware and expertise. Developers of nano-satellites, however, may not have the expertise or resources necessary for establishing a dedicated ground station. Therefore, the use of an existing communication system, such as the Satellite Personal Communication Networks (S-PCNs), is attractive. Another shortcoming of the fixed ground stations, already available, is that they are normally only able to communicate with Low Earth Orbit (LEO) nano-satellites four times per day (two10-minute windows separated by 90 minutes, …
A Multi-Objective No-Regret Decision Making Model With Bayesian Learning For Autonomous Unmanned Systems, Matthew Howard
A Multi-Objective No-Regret Decision Making Model With Bayesian Learning For Autonomous Unmanned Systems, Matthew Howard
Electronic Theses and Dissertations
The development of a multi-objective decision making and learning model for the use in unmanned systems is the focus of this project. Starting with traditional game theory and psychological learning theories developed in the past, a new model for machine learning is developed. This model incorporates a no-regret decision making model with a Bayesian learning process which has the ability to adapt to errors found in preconceived costs associated with each objective. This learning ability is what sets this model apart from many others. By creating a model based on previously developed human learning models, hundreds of years of experience …
Novel Complex Adaptive Signal Processing Techniques Employing Optimally Derived Time-Varying Convergence Factors With Applicatio, Raghuram Ranganathan
Novel Complex Adaptive Signal Processing Techniques Employing Optimally Derived Time-Varying Convergence Factors With Applicatio, Raghuram Ranganathan
Electronic Theses and Dissertations
In digital signal processing in general, and wireless communications in particular, the increased usage of complex signal representations, and spectrally efficient complex modulation schemes such as QPSK and QAM has necessitated the need for efficient and fast-converging complex digital signal processing techniques. In this research, novel complex adaptive digital signal processing techniques are presented, which derive optimal convergence factors or step sizes for adjusting the adaptive system coefficients at each iteration. In addition, the real and imaginary components of the complex signal and complex adaptive filter coefficients are treated as separate entities, and are independently updated. As a result, the …
A Low Phase Noise K-Band Oscillator Utilizing An Embedded Dielectric Resonator On Multilayer High Frequency Laminates, Ajay Subramanian
A Low Phase Noise K-Band Oscillator Utilizing An Embedded Dielectric Resonator On Multilayer High Frequency Laminates, Ajay Subramanian
Electronic Theses and Dissertations
K-Band (18 to 26 GHz) dielectric resonator oscillators are typically used as a local oscillator in most K-Band digital transmitter/receiver topologies. Traditionally, the oscillator itself is made up of an active device, a dielectric resonator termination network, and a passive load matching network. The termination network embodies a cylindrical high permittivity dielectric resonator that is coupled on the same plane as a current carrying transmission line. This configuration provides an adequate resonance needed for oscillation but has some limitations. In order to provide a high Q resonance the entire oscillator is placed in a metal box to prevent radiation losses. …
A Time-Varying Radiometric Bias Correction For The Trmm Microwave Imager, Kaushik Gopalan
A Time-Varying Radiometric Bias Correction For The Trmm Microwave Imager, Kaushik Gopalan
Electronic Theses and Dissertations
This dissertation provides a robust radiometric calibration for the TRMM Microwave Imager to correct systematic brightness temperature errors, which vary dynamically with orbit position (time) and day of the year. The presence of a time-varying bias in TMI is confirmed by inter-calibration with WindSat and SSMI. This time varying bias is manifested as a time of day dependent variation of the relative biases between TMI and both WindSat and SSMI. In this dissertation, we provide convincing evidence that this time-varying Tb bias in TMI is caused by variations in the physical temperature of the emissive TMI reflector antenna. This dissertation …
Integration Of A Nanostructure Embedded Thermoresponsive Polymer For Microfluidic Applications, Ghanashyam Londe
Integration Of A Nanostructure Embedded Thermoresponsive Polymer For Microfluidic Applications, Ghanashyam Londe
Electronic Theses and Dissertations
This work describes the modeling, synthesis, integration and characterization of a novel nanostructure embedded thermoresponsive material for microfluidic applications. The innumerable applications of thermoresponsive surfaces in the recent years have necessitated the development of a rigorous mathematical treatment for these surfaces to understand and improve their behavior. An analytical model is proposed to describe the transfer characteristic (variation of contact angle versus temperature) of a unique switchable, nanostructured, thermoresponsive surface consisting of silica nanoparticles and the thermoresponsive polymer, Poly(N-isopropylacrylamide ) (PNIPAAm) which changes its wetting angle upon heating. Important metrics such as the absolute lower critical solution temperature, threshold & …
Real-Time Trajectory Planning For Groundand Aerial Vehicles In A Dynamic Environment, Jian Yang
Real-Time Trajectory Planning For Groundand Aerial Vehicles In A Dynamic Environment, Jian Yang
Electronic Theses and Dissertations
In this dissertation, a novel and generic solution of trajectory generation is developed and evaluated for ground and aerial vehicles in a dynamic environment. By explicitly considering a kinematic model of the ground vehicles, the family of feasible trajectories and their corresponding steering controls are derived in a closed form and are expressed in terms of one adjustable parameter for the purpose of collision avoidance. A collision-avoidance condition is developed for the dynamically changing environment, which consists of a time criterion and a geometrical criterion. By imposing this condition, one can determine a family of collision-free paths in a closed …
Numerical Modeling Of Wave Propagation In Nonlinear Photonic Crystal Fiber, Md. Kaisar Khan
Numerical Modeling Of Wave Propagation In Nonlinear Photonic Crystal Fiber, Md. Kaisar Khan
Electronic Theses and Dissertations
In this dissertation, we propose numerical techniques to explain physical phenomenon of nonlinear photonic crystal fiber (PCF). We explain novel physical effects occurred in PCF subjected to very short duration pulses including soliton. To overcome the limitations in the analytical formulation for PCF, an accurate and efficient numerical analysis is required to explain both linear and nonlinear physical characteristics. A vector finite element based model was developed to precisely synthesize the guided modes in order to evaluate coupling coefficients, nonlinear coefficient and higher order dispersions of PCFs. This finite element model (FEM) is capable of evaluating coupling length of directional …
Ultra-Wideband Orthogonal Frequency Coded Saw Correlators, Daniel Gallagher
Ultra-Wideband Orthogonal Frequency Coded Saw Correlators, Daniel Gallagher
Electronic Theses and Dissertations
Ultra-wideband (UWB) communication new technology with ability to share the FCC allocated frequency spectrum, large channel capacity and data rate, simple transceiver architecture and high performance in noisy environments. Such communication advantages have paved the way for emerging wireless technologies such as wireless high definition video streaming, wireless sensor networks and more. This thesis examines orthogonal frequency coded surface acoustic wave (SAW) correlators for use in advanced UWB communication systems. Orthogonal frequency coding (OFC) and pseudo-noise (PN) coding provides a means for UWB spreading of data. The use of OFC spectrally spreads a PN sequence beyond that of CDMA because …
Simulation And Study Of The Stokes Vector In A Precipitating Atmosphere, Ian Adams
Simulation And Study Of The Stokes Vector In A Precipitating Atmosphere, Ian Adams
Electronic Theses and Dissertations
Precipitation is a dominating quantity in microwave radiometry. The large emission and scattering signals of rain and ice, respectively, introduce large contributions to the measured brightness temperature. While this allows for accurate sensing of precipitation, it also results in degraded performance when retrieving other geophysical parameters, such as near-surface ocean winds. In particular, the retrieval of wind direction requires precise knowledge of polarization, and nonspherical particles can result in a change in the polarization of incident radiation. The aim of this dissertation is to investigate the polarizing effects of precipitation in the atmosphere, including the existence of a precipitation signal …
Modeling And Analysis Of The Eds Maglev System With The Halbach Magnet Array, Wonsuk Ko
Modeling And Analysis Of The Eds Maglev System With The Halbach Magnet Array, Wonsuk Ko
Electronic Theses and Dissertations
The magnetic field analysis based on the wavelet transform is performed. The Halbach array magnetic field analysis has been studied using many methods such as magnetic scalar potential, magnetic vector potential, Fourier analysis and Finite Element Methods. But these analyses cannot identify a transient oscillation at the beginning stage of levitation. The wavelet transform is used for analyzing the transient oscillatory response of an EDS Maglev system. The proposed scheme explains the under-damped dynamics that results from the cradle's dynamic response to the irregular distribution of the magnetic field. It suggests this EDS Maglev system that responds to a vertical …
Design, Modeling, And Control Of Three-Port Converters For Solar Power Applications, Justin M. Reese
Design, Modeling, And Control Of Three-Port Converters For Solar Power Applications, Justin M. Reese
Electronic Theses and Dissertations
This paper describes the results of research into multi-port converter design and control, specifically a pair of three-port topologies based on the half-bridge and full-bridge topologies. These converters are capable of simultaneous and independent regulation of two out of their three ports, while the third port provides the power balance in the system. A dynamic model was developed for each topology to aid in testing and for designing the control loops. The models were then used to design the control structures, and the results were tested in Simulink. In addition, a basic outline of a system level architecture to control …
Advanced Coding And Modulation For Ultra-Wideband And Impulsive Noises, Libo Yang
Advanced Coding And Modulation For Ultra-Wideband And Impulsive Noises, Libo Yang
Electronic Theses and Dissertations
The ever-growing demand for higher quality and faster multimedia content delivery over short distances in home environments drives the quest for higher data rates in wireless personal area networks (WPANs). One of the candidate IEEE 802.15.3a WPAN proposals support data rates up to 480 Mbps by using punctured convolutional codes with quadrature phase shift keying (QPSK) modulation for a multi-band orthogonal frequency-division multiplexing (MB-OFDM) system over ultra wideband (UWB) channels. In the first part of this dissertation, we combine more powerful near-Shannon-limit turbo codes with bandwidth efficient trellis coded modulation, i.e., turbo trellis coded modulation (TTCM), to further improve the …
Modeling,Design,And Characterization Of Monolithic Bi-Directional Power Semiconductor Switch, Yue Fu
Modeling,Design,And Characterization Of Monolithic Bi-Directional Power Semiconductor Switch, Yue Fu
Electronic Theses and Dissertations
Bidirectional power switching devices are needed in many power management applications, particularly in lithium-ion battery protection circuitry. A monolithic bidirectional power switch fabricated with a simplified CMOS technology is introduced in this dissertation. Throughout the design process, ISE TCAD tool plays an important role. Design variables are carefully analyzed to improve the device performance or yield the best trade off. Optimization is done with the help of TCAD simulation and theoretical calculations. The device has been successfully fabricated using simplified 0.5 micron CMOS process. The experimental result shows a breakdown voltage of 25V. Due to the interdigitated source to source …
Investigation Of Reactively Sputtered Silicon Carbon Boron Nitride (Sicbn) Thin Films For High Temperature Applications, Arun Vijayakumar
Investigation Of Reactively Sputtered Silicon Carbon Boron Nitride (Sicbn) Thin Films For High Temperature Applications, Arun Vijayakumar
Electronic Theses and Dissertations
The increasing demand for efficient energy systems in the last decade has brought about the development of advanced sensor systems that utilize advance detection methods to help in preventive maintenance of these essential systems. These usually are needed in hard to access environments where conditions are extreme and unfit for human interaction. Thin film based sensors deposited directly on the surfaces exposed to harsh environments can serve as ideal means of measuring the temperature of the component during operation. They provide the basic advantage of proximity to the surface and hence accurate measurement of the surface temperature. The low mass …
Integrated Topologies And Digital Control For Satellite Power Management And Distribution Systems, Hussam Al-Atrash
Integrated Topologies And Digital Control For Satellite Power Management And Distribution Systems, Hussam Al-Atrash
Electronic Theses and Dissertations
This work is focused on exploring advanced solutions for space power management and distribution (PMAD) systems. As spacecraft power requirements continue to increase, paralleled by the pressures for reducing cost and overall system weight, power electronics engineers will continue to face major redesigns of the space power systems in order to meet such challenges. Front-end PMAD systems, used to interface the solar sources and battery backup to the distribution bus, need to be designed with increased efficiency, reliability, and power density. A new family of integrated single-stage power converter structures is introduced here. This family allows the interface and control …
Four Terminal Junction Field-Effect Transistor Model For Computer-Aided Design, Hao Ding
Four Terminal Junction Field-Effect Transistor Model For Computer-Aided Design, Hao Ding
Electronic Theses and Dissertations
A compact model for four-terminal (independent top and bottom gates) junction field-effect transistor (JFET) is presented in this dissertation. The model describes the steady-state characteristics with a unified equation for all bias conditions that provides a high degree of accuracy and continuity of conductance, which are important for predictive analog circuit simulations. It also includes capacitance and leakage equations. A special capacitance drop-off phenomenon at the pinch-off region is studies and modeled. The operations of the junction fieldeffect transistor (JFET) with an oxide top-gate and full oxide isolation are analyzed, and a semi-physical compact model is developed. The effects of …
Signal Processing Of An Ecg Signal In The Presence Of A Strong Static Magnetic Field, Aditya Gupta
Signal Processing Of An Ecg Signal In The Presence Of A Strong Static Magnetic Field, Aditya Gupta
Electronic Theses and Dissertations
This dissertation addresses the problem of elevation of the T wave of an electrocardiogram (ECG) signal in the magnetic resonance imaging (MRI). In the MRI, due to the strong static magnetic field the interaction of the blood flow with this strong magnetic field induces a voltage in the body. This voltage appears as a superimposition at the locus of the T wave of the ECG signal. This looses important information required by the doctors to interpret the ST segment of the ECG and detect diseases such as myocardial infarction. This dissertation aims at finding a solution to the problem of …
Gate Stack And Channel Engineering: Study Of Metal Gates And Ge Channel Devices, Ravi Todi
Gate Stack And Channel Engineering: Study Of Metal Gates And Ge Channel Devices, Ravi Todi
Electronic Theses and Dissertations
The continued scaling of device dimensions in complementary metal oxide semiconductor (CMOS) technology within the sub-100 nm region requires an alternative high dielectric constant (high-k) oxide layer to counter high tunneling leakage currents, a metallic gate electrode to address polysilicon depletion, boron penetration and high polysilicon sheet resistance, and high mobility channel materials to boost the CMOS performance. Metal gates can also offer improved thermal and chemical stability, but their use requires that we improve our understanding of how the metal alloy phase, crystallographic orientation, and composition affect the electronic properties of the metal alloy-oxide interface. To replace n++ and …
A Comparison And Evaluation Of Common Pid Tuning Methods, Justin Youney
A Comparison And Evaluation Of Common Pid Tuning Methods, Justin Youney
Electronic Theses and Dissertations
The motivation behind this thesis is to consolidate and evaluate the most common Proportional Integral Derivative (PID) controller tuning techniques used in industry. These are the tuning techniques used when the plant transfer function is not known. Many of these systems are poorly tuned because such consolidated information is not easily found in one single source such as this thesis. Once one of the tuning methods are applied almost always there will be further fine tuning needed to bring the system into the required design criteria. The purpose here is to find out which tuning technique will yield the lowest …
Negative Bias Temperature Instability And Charge Trapping Effects On Analog And Digital Circuit Reliability, Yixin Yu
Electronic Theses and Dissertations
Nanoscale p-channel transistors under negative gate bias at an elevated temperature show threshold voltage degradation after a short period of stress time. In addition, nanoscale (45 nm) n-channel transistors using high-k (HfO2) dielectrics to reduce gate leakage power for advanced microprocessors exhibit fast transient charge trapping effect leading to threshold voltage instability and mobility reduction. A simulation methodology to quantify the circuit level degradation subjected to negative bias temperature instability (NBTI) and fast transient charge trapping effect has been developed in this thesis work. Different current mirror and two-stage operation amplifier structures are studied to evaluate the impact of NBTI …
Novel Facial Image Recognition Techniques Employing Principal Component Analysis, Moataz Mahmoud Abdelwahab
Novel Facial Image Recognition Techniques Employing Principal Component Analysis, Moataz Mahmoud Abdelwahab
Electronic Theses and Dissertations
Recently, pattern recognition/classification has received considerable attention in diverse engineering fields such as biomedical imaging, speaker identification, fingerprint recognition, and face recognition, etc. This study contributes novel techniques for facial image recognition based on the Two dimensional principal component analysis in the transform domain. These algorithms reduce the storage requirements by an order of magnitude and the computational complexity by a factor of 2 while maintaining the excellent recognition accuracy of the recently reported methods. The proposed recognition systems employ different structures, multicriteria and multitransform. In addition, principal component analysis in the transform domain in conjunction with vector quantization is …
Soft Switching Multi-Resonant Forward Converter Dc To Dc Application For Communications Equipment, David Marlin Bills
Soft Switching Multi-Resonant Forward Converter Dc To Dc Application For Communications Equipment, David Marlin Bills
Electronic Theses and Dissertations
In the field of power electronics there is always a push to create smaller and more efficient power conversion systems. This push is driven by the industry that uses the power systems, and can be realized by new semiconductor devices or new techniques. This examination describes a novel technique for a small and highly efficient method of converting relatively high DC voltage to a very low voltage for use in the telecommunications industry. A modification to the standard Forward Resonant converter results in improvements in component stress, system efficiency, response time, and control circuitry. This examination describes background information needed …
Comparison Of Single Stage And Two Stage Stage Grid-Tie Inverters, Keith Mansfield
Comparison Of Single Stage And Two Stage Stage Grid-Tie Inverters, Keith Mansfield
Electronic Theses and Dissertations
This thesis compares two methods of designing grid-tie inverters. The first design topology is a traditional two stage approach consisting of an isolated DC-DC converter on the input followed by a high switching frequency SPWM (Sinusoidal Pulse Width Modulation) stage to produce the required low frequency sine wave output. The novel second design approach employs a similar DC-DC input stage capable of being modulated to provide a rectified sine wave output voltage/current waveform. This stage is followed by a simple low frequency switched Unfolding Stage to recreate the required sine wave output. Both of the above designs have advantages and …
Knowledge Based Measurement Of Enhancing Brain Tissue In Anisotropic Mr Imagery, Eric Leach
Knowledge Based Measurement Of Enhancing Brain Tissue In Anisotropic Mr Imagery, Eric Leach
Electronic Theses and Dissertations
Medical Image Analysis has emerged as an important field in the computer vision community. In this thesis, two important issues in medical imaging are addressed and a solution for each is derived and synergistically combined as one coherent system. Firstly, a novel approach is proposed for High Resolution Volume (HRV) construction by combining different frequency components at multiple levels, which are separated by using a multi-resolution pyramid structure. Current clinical imaging protocols make use of multiple orthogonal low resolution scans to measure the size of the tumor. The highly anisotropic data result in difficulty and even errors in tumor assessment. …
Anchoring Energy And Pretilt Angle Effects On Liquid Crystal Response Time, Xiangyi Nie
Anchoring Energy And Pretilt Angle Effects On Liquid Crystal Response Time, Xiangyi Nie
Electronic Theses and Dissertations
This dissertation covers some important topics on the liquid crystal-substrate surface effects, including theoretical derivations and confirming experimental results. The research work is expected to make important impacts on liquid crystal device designs and to open new doors for further research along these topics. In this dissertation, a novel high-electric-field technique is developed to characterize the anchoring energy of vertically-aligned liquid crystal cells. Both theoretical analyses and confirming experimental results are presented. Vertically-aligned liquid crystal cells with buffed polyimide alignment layers are used to validate the measurement techniques. Based on the voltage-dependent transmittance of the liquid crystal cells, a linear …
A Study Of Equatorial Ionopsheric Variability Using Signal Processing Techniques, Xiaoni Wang
A Study Of Equatorial Ionopsheric Variability Using Signal Processing Techniques, Xiaoni Wang
Electronic Theses and Dissertations
The dependence of equatorial ionosphere on solar irradiances and geomagnetic activity are studied in this dissertation using signal processing techniques. The statistical time series, digital signal processing and wavelet methods are applied to study the ionospheric variations. The ionospheric data used are the Total Electron Content (TEC) and the critical frequency of the F2 layer (foF2). Solar irradiance data are from recent satellites, the Student Nitric Oxide Explorer (SNOE) satellite and the Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED) satellite. The Disturbance Storm-Time (Dst) index is used as a proxy of geomagnetic activity in the equatorial region. The results are summarized …
Design And Modeling Of Radiation Hardened Ldmosfet For Space Craft Power Systems, Patrick Shea
Design And Modeling Of Radiation Hardened Ldmosfet For Space Craft Power Systems, Patrick Shea
Electronic Theses and Dissertations
NASA missions require innovative power electronics system and component solutions with long life capability, high radiation tolerance, low mass and volume, and high reliability in space environments. Presently vertical double-diffused MOSFETs (VDMOS) are the most widely used power switching device for space power systems. It is proposed that a new lateral double-diffused MOSFET (LDMOS) designed at UCF can offer improvements in total dose and single event radiation hardness, switching performance, development and manufacturing costs, and total mass of power electronics systems. Availability of a hardened fast-switching power MOSFET will allow space-borne power electronics to approach the current level of terrestrial …
Modeling And Digital Control Of High Frequency Dc-Dc Power Converters, Yangyang Wen
Modeling And Digital Control Of High Frequency Dc-Dc Power Converters, Yangyang Wen
Electronic Theses and Dissertations
The power requirements for leading edge digital integrated circuits have become increasingly demanding. Power converter systems must be faster, more flexible, more precisely controllable and easily monitored. Meanwhile, in addition to control process, the new functions such as power sequencing, communication with other systems, voltage dynamic programming,load line specifications, phase current balance, protection, power status monitoring and system diagnosis are going into today's power supply systems. Digital controllers, compared withanalog controllers, are in a favorable position to provide basic feedback control as well as those power management functions with lower cost and great flexibility. The dissertation gives an overview of …
Maximum Energy Harvesting Control Foroscillating Energy Harvesting Systems, John Elmes
Maximum Energy Harvesting Control Foroscillating Energy Harvesting Systems, John Elmes
Electronic Theses and Dissertations
This thesis presents an optimal method of designing and controlling an oscillating energy harvesting system. Many new and emerging energy harvesting systems, such as the energy harvesting backpack and ocean wave energy harvesting, capture energy normally expelled through mechanical interactions. Often the nature of the system indicates slow system time constants and unsteady AC voltages. This paper reveals a method for achieving maximum energy harvesting from such sources with fast determination of the optimal operating condition. An energy harvesting backpack, which captures energy from the interaction between the user and the spring decoupled load, is presented in this paper. The …