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Electrical Parasitic Bandwidth Limitations Of Oxide-Free Lithographic Vertical-Cavity Surface-Emitting Lasers, Xu Yang
Electronic Theses and Dissertations
Nowadays, Vertical-Cavity Surface-Emitting Lasers (VCSELs) are the most popular optical sources in short-reach data communications. In the commercial oxide VCSEL technology, an oxide aperture is created inside resonant cavity in realizing good mode and current confinement, however, high electrical resistance comes along with forming the oxide aperture and the electrical parasitic bandwidth becomes the main limitation in modulation speed. In this report, electrical bandwidths of oxide-free lithographic VCSELs have been studied along with their general lasing properties. Due to the new ways of fabricating the aperture, record low resistances have been achieved in oxide-free lithographic VCSELs with various sizes, while …
High Average Power Nanosecond Pulsed Tm:Fiber Laser For Pumping An Optical Parametric Oscillator, Ali Abdulfattah
High Average Power Nanosecond Pulsed Tm:Fiber Laser For Pumping An Optical Parametric Oscillator, Ali Abdulfattah
Electronic Theses and Dissertations
Thulium-doped fiber lasers operating with wavelengths in the vicinity of 2 µm are useful for several emerging applications including generating mid-IR light via nonlinear frequency conversion. In this study we describe the design and construction of a thulium fiber laser system comprising a master oscillator and a power amplifier. The first stage is a Q-switched, thulium-doped photonic crystal fiber oscillator utilizing an acousto-optic modulator to produce 65-80 nanosecond pulses. A diffraction grating in the cavity provides wavelength tunability from 1.8 – 2µm. The oscillator produced up to 3 W of average power and 150 µJ pulse energies, corresponding to 2.3 …
Smart Grid Demonstration: Distributed Active And Reactive Power Control, Siddarth Vellakovil Rajamani
Smart Grid Demonstration: Distributed Active And Reactive Power Control, Siddarth Vellakovil Rajamani
Electronic Theses and Dissertations
The present infrastructure of energy delivery was designed over 60 years ago with the goal to be centralized. However, it is aging and is under-utilized, which will potentially limit the world's ability to achieve its energy objective. The lack of vibrant control on the grid makes it difficult to stop cascading power failure, and to achieve high penetration of renewable energy resources, such as wind and solar thus resulting in grid instability. A decentralized and distributed control mechanism implemented with a definite communication protocol solves the issues mentioned above. The electric power grid going into the future is expected to …
Smart Grasping Using Laser And Tactile Array Sensors For Ucf-Manus- An Intelligent Assistive Robotic Manipulator, Kiran Prakash
Smart Grasping Using Laser And Tactile Array Sensors For Ucf-Manus- An Intelligent Assistive Robotic Manipulator, Kiran Prakash
Electronic Theses and Dissertations
This thesis presents three improvements in the UCF MANUS Assistive Robotic Manipulator's grasping abilities. Firstly, the robot can now grasp objects that are deformable, heavy and have uneven contact surfaces without undergoing slippage during robotic operations, e.g. paper cup, filled water bottle. This is achieved by installing a high precision non-contacting Laser sensor1 that runs with an algorithm that processes raw-input data from the sensor, registers smallest variation in the relative position of the object with respect to the gripper. Secondly, the robot can grasp objects that are as light and small as single cereal grain without deforming it. To …
Performance Evaluation Of Connectivity And Capacity Of Dynamic Spectrum Access Networks, Osama Al-Tameemi
Performance Evaluation Of Connectivity And Capacity Of Dynamic Spectrum Access Networks, Osama Al-Tameemi
Electronic Theses and Dissertations
Recent measurements on radio spectrum usage have revealed the abundance of under- utilized bands of spectrum that belong to licensed users. This necessitated the paradigm shift from static to dynamic spectrum access (DSA) where secondary networks utilize unused spectrum holes in the licensed bands without causing interference to the licensed user. However, wide scale deployment of these networks have been hindered due to lack of knowledge of expected performance in realistic environments and lack of cost-effective solutions for implementing spectrum database systems. In this dissertation, we address some of the fundamental challenges on how to improve the performance of DSA …
Broad Bandwidth Optical Frequency Combs From Low Noise, High Repetition Rate Semiconductor Mode-Locked Lasers, Anthony Klee
Broad Bandwidth Optical Frequency Combs From Low Noise, High Repetition Rate Semiconductor Mode-Locked Lasers, Anthony Klee
Electronic Theses and Dissertations
Mode-locked lasers have numerous applications in the areas of communications, spectroscopy, and frequency metrology. Harmonically mode-locked semiconductor lasers with external ring cavities offer a unique combination of benefits in that they can produce high repetition rate pulse trains with low timing jitter, achieve narrow axial mode linewidths, have the potential for entire monolithic integration on-chip, feature high wall-plug efficiency due to direct electrical pumping, and can be engineered to operate in different wavelength bands of interest. However, lasers based on InP/InGaAsP quantum well devices which operate in the important telecom C-band have thus far been relatively limited in bandwidth as …
Microgrid Control And Protection: Stability And Security, Morteza Keshavarztalebi
Microgrid Control And Protection: Stability And Security, Morteza Keshavarztalebi
Electronic Theses and Dissertations
When the microgrid disconnects from the main grid in response to, say, upstream disturbance or voltage fluctuation and goes to islanding mode, both voltage and frequency at all locations in the microgrid have to be regulated to nominal values in a short amount of time before the operation of protective relays. Motivated by this, we studied the application of intelligent pinning of distributed cooperative secondary control of distributed generators in islanded microgrid operation in a power system. In the first part, the problem of single and multi-pinning of distributed cooperative secondary control of DGs in a microgrid is formulated. It …
Enhanced Hardware Security Using Charge-Based Emerging Device Technology, Yu Bi
Enhanced Hardware Security Using Charge-Based Emerging Device Technology, Yu Bi
Electronic Theses and Dissertations
The emergence of hardware Trojans has largely reshaped the traditional view that the hardware layer can be blindly trusted. Hardware Trojans, which are often in the form of maliciously inserted circuitry, may impact the original design by data leakage or circuit malfunction. Hardware counterfeiting and IP piracy are another two serious issues costing the US economy more than $200 billion annually. A large amount of research and experimentation has been carried out on the design of these primitives based on the currently prevailing CMOS technology. However, the security provided by these primitives comes at the cost of large overheads mostly …
Deposition And Characterization Studies Of Boron Carbon Nitride (Bcn) Thin Films Prepared By Dual Target Sputtering, Adithya Prakash
Deposition And Characterization Studies Of Boron Carbon Nitride (Bcn) Thin Films Prepared By Dual Target Sputtering, Adithya Prakash
Electronic Theses and Dissertations
As complementary metal-oxide semiconductor (CMOS) devices shrink to smaller size, the problems related to circuit performance such as critical path signal delay are becoming a pressing issue. These delays are a result of resistance and capacitance product (RC time constant) of the interconnect circuit. A novel material with reduced dielectric constants may compromise both the thermal and mechanical properties that can lead to die cracking during package and other reliability issues. Boron carbon nitride (BCN) compounds have been expected to combine the excellent properties of boron carbide (B4C), boron nitride (BN) and carbon nitride (C3N4), with their properties adjustable, depending …
Design And Characterization Of System Level Electrostatic Discharge (Esd) Protection Solutions, Yunfeng Xi
Design And Characterization Of System Level Electrostatic Discharge (Esd) Protection Solutions, Yunfeng Xi
Electronic Theses and Dissertations
Electrostatic Discharges (ESD) are one of the main reliability threats in modern electronics. Design, implementation, and characterization of ESD and transient protection of these modern electronics are increasingly challenging due to the process, packaging and cost constraints. Growing communication between ‘objects’ to be sensed and controlled remotely is creating opportunities for greater integration with computer systems, resulting in improved efficiency, accuracy and economic benefits across existing and emerging network infrastructures. This tendency is driving an expansion in data communication as well as industrial applications environment. To keep up with the interconnectivity expansion, the industry requires new devices to support more …
Uncooled Infrared Detector Featuring Silicon Based Nanoscale Thermocouple, Mohammad Modarres-Zadeh
Uncooled Infrared Detector Featuring Silicon Based Nanoscale Thermocouple, Mohammad Modarres-Zadeh
Electronic Theses and Dissertations
The main focus of this dissertation is to improve the performance of thermoelectric (TE) infrared (IR) detectors. TE IR detectors are part of uncooled detectors that can operate at room temperature. These detectors have been around for many years, however, their performance has been lower than their contesting technologies. A novel high-responsivity uncooled thermoelectric infrared detector is designed, fabricated, and characterized. This detector features a single standalone polysilicon-based thermocouple (without a supporting membrane) covered by an umbrellalike optical-cavity IR absorber. It is proved that the highest responsivity in the developed detectors can be achieved with only one thermocouple. Since the …
On-Orbit Inter-Satellite Radiometric Calibration Of Cross-Track Scanning Microwave Radiometers, Hamideh Ebrahimi
On-Orbit Inter-Satellite Radiometric Calibration Of Cross-Track Scanning Microwave Radiometers, Hamideh Ebrahimi
Electronic Theses and Dissertations
This dissertation concerns the development of an improved algorithm for the inter-satellite radiometric calibration (XCAL) for cross track scanning microwave radiometers in support of NASA's Global Precipitation Mission (GPM). This research extends previous XCAL work to assess the robustness of the CFRSL "double difference" technique for sounder X-CAL. In this work, using a two-year of observations, we present a statistical analysis of radiometric biases performed over time and viewing geometry. In theory, it is possible to apply the same X-CAL procedure developed for conical-scanning radiometers to cross-track scanners; however the implementation is generally more tedious. For example, with the cross-track …
Stochastic-Based Computing With Emerging Spin-Based Device Technologies, Yu Bai
Stochastic-Based Computing With Emerging Spin-Based Device Technologies, Yu Bai
Electronic Theses and Dissertations
In this dissertation, analog and emerging device physics is explored to provide a technology platform to design new bio-inspired system and novel architecture. With CMOS approaching the nano-scaling, their physics limits in feature size. Therefore, their physical device characteristics will pose severe challenges to constructing robust digital circuitry. Unlike transistor defects due to fabrication imperfection, quantum-related switching uncertainties will seriously increase their susceptibility to noise, thus rendering the traditional thinking and logic design techniques inadequate. Therefore, the trend of current research objectives is to create a non-Boolean high-level computational model and map it directly to the unique operational properties of …
Multi-Purpose Device For Analyzing And Measuring Ultra-Short Pulses, Naman Anilkumar Mehta
Multi-Purpose Device For Analyzing And Measuring Ultra-Short Pulses, Naman Anilkumar Mehta
Electronic Theses and Dissertations
Intensity auto correlator is device to measure pulse widths of ultrashort pulses on the order of picoseconds and femtoseconds. I have built an in-house, compact, portable, industry standard intensity auto correlator for measuring ultrashort pulse-widths. My device is suitable for pulse-widths from 500 ps to 50 fs. The impetus for developing this instrument stemmed from our development of a multicore-fiber laser for high power laser applications, which also produces very short pulses that cannot be measured with an oscilloscope. As techniques for measuring short pulse-widths have been well studied, what made my journey exciting was the process of taking an …
Compressive And Coded Change Detection: Theory And Application To Structural Health Monitoring, Omid Sarayanibafghi
Compressive And Coded Change Detection: Theory And Application To Structural Health Monitoring, Omid Sarayanibafghi
Electronic Theses and Dissertations
In traditional sparse recovery problems, the goal is to identify the support of compressible signals using a small number of measurements. In contrast, in this thesis the problem of identification of a sparse number of statistical changes in stochastic phenomena is considered when decision makers only have access to compressed measurements, i.e., each measurement is derived by a subset of features. Herein, we propose a new framework that is termed Compressed Change Detection. The main approach relies on integrating ideas from the theory of identifying codes with change point detection in sequential analysis. If the stochastic properties of certain features …
Work Function Extraction Of Indium Tin Oxide Used As Transparent Gate Electrode For Mosfet., Shraddha Nehate
Work Function Extraction Of Indium Tin Oxide Used As Transparent Gate Electrode For Mosfet., Shraddha Nehate
Electronic Theses and Dissertations
Recent commercialization has peaked interest in transparent conducting oxides being implemented in display technology. Indium Tin Oxide (ITO) is a popular transparent conducting oxide which has been utilized as high work function electrode in liquid crystal displays, solar cells, gas sensors and heat reflecting films. Indium Tin Oxide films exhibit excellent transmission characteristics in the visible and infrared spectrum while maintaining high electrical conductivity. High work function electrodes are used to inject holes into organic materials. In majority applications the ITO work function has an impact on the device performance as it affects the energy barrier height at the hetero-junction …
Study Of Novel Power Semiconductor Devices For Performance And Reliability., Karthik Padmanabhan
Study Of Novel Power Semiconductor Devices For Performance And Reliability., Karthik Padmanabhan
Electronic Theses and Dissertations
Power Semiconductor Devices are crucial components in present day power electronic systems. The performance and efficiency of the devices have a direct correlation with the power system efficiency. This dissertation will examine some of the components that are commonly used in a power system, with emphasis on their performance characteristics and reliability. In recent times, there has a proliferation of charge balance devices in high voltage discrete power devices. We examine the same charge balance concept in a fast recovery diode and a MOSFET. This is crucial in the extending system performance at compact dimensions. At smaller device and system …
Investigation Of The Effect Of Rain On Sea Surface Salinity, Andrea Santos Garcia
Investigation Of The Effect Of Rain On Sea Surface Salinity, Andrea Santos Garcia
Electronic Theses and Dissertations
The Aquarius/SAC-D mission provided Sea Surface Salinity (SSS), globally over the ocean, for almost 4 years. As a member of the AQ/SAC-D Cal/Val team, the Central Florida Remote Sensing Laboratory has analyzed these salinity measurements in the presence of precipitation and has noted the high correlation between the spatial patterns of reduced SSS and the spatial distribution of rain. It was determined that this is the result of a cause and effect relation, and not SSS measurement errors. Thus, it is important to understand these salinity changes due to seawater dilution by rain and the associated near-surface salinity strati?cation. This …
Content-Based Information Retrieval Via Nearest Neighbor Search, Yinjie Huang
Content-Based Information Retrieval Via Nearest Neighbor Search, Yinjie Huang
Electronic Theses and Dissertations
Content-based information retrieval (CBIR) has attracted significant interest in the past few years. When given a search query, the search engine will compare the query with all the stored information in the database through nearest neighbor search. Finally, the system will return the most similar items. We contribute to the CBIR research the following: firstly, Distance Metric Learning (DML) is studied to improve retrieval accuracy of nearest neighbor search. Additionally, Hash Function Learning (HFL) is considered to accelerate the retrieval process. On one hand, a new local metric learning framework is proposed - Reduced-Rank Local Metric Learning (R2LML). By considering …
Rf Circuit Designs For Reliability And Process Variability Resilience, Ekavut Kritchanchai
Rf Circuit Designs For Reliability And Process Variability Resilience, Ekavut Kritchanchai
Electronic Theses and Dissertations
Complementary metal oxide semiconductor (CMOS) radio frequency (RF) circuit design has been an ever-lasting research field. It has gained so much attention since RF circuits offer high mobility and wide-band efficiency, while CMOS technology provides the advantage of low cost and high integration capability. At the same time, CMOS device size continues to scale to the nanometer regime. Reliability issues with RF circuits have become more challenging than ever before. Reliability mechanisms, such as gate oxide breakdown, hot carrier injection, negative bias temperature instability, have been amplified as the device size shrinks. In addition, process variability becomes a new design …
Model Selection Via Racing, Tiantian Zhang
Model Selection Via Racing, Tiantian Zhang
Electronic Theses and Dissertations
Model Selection (MS) is an important aspect of machine learning, as necessitated by the No Free Lunch theorem. Briefly speaking, the task of MS is to identify a subset of models that are optimal in terms of pre-selected optimization criteria. There are many practical applications of MS, such as model parameter tuning, personalized recommendations, A/B testing, etc. Lately, some MS research has focused on trading off exactness of the optimization with somewhat alleviating the computational burden entailed. Recent attempts along this line include metaheuristics optimization, local search-based approaches, sequential model-based methods, portfolio algorithm approaches, and multi-armed bandits. Racing Algorithms (RAs) …
Applied Advanced Error Control Coding For General Purpose Representation And Association Machine Systems, Bowen Dai
Electronic Theses and Dissertations
General-Purpose Representation and Association Machine (GPRAM) is proposed to be focusing on computations in terms of variation and flexibility, rather than precision and speed. GPRAM system has a vague representation and has no predefined tasks. With several important lessons learned from error control coding, neuroscience and human visual system, we investigate several types of error control codes, including Hamming code and Low-Density Parity Check (LDPC) codes, and extend them to different directions. While in error control codes, solely XOR logic gate is used to connect different nodes. Inspired by bio-systems and Turbo codes, we suggest and study non-linear codes with …
Design And Optimization Of Superjunction Vertical Dmos Power Transistors Using Sentaurus Device Simulation, Raul Mendoza Macias
Design And Optimization Of Superjunction Vertical Dmos Power Transistors Using Sentaurus Device Simulation, Raul Mendoza Macias
Electronic Theses and Dissertations
Vertical double-diffused metal oxide semiconductor (VDMOS) power transistor has been studied. The use of superjunction (SJ) in the drift region of VDMOS has been evaluated using three-dimensional device simulation. All relevant physical models in Sentaurus are turned on. The VDMOS device doping profile is obtained from process simulation. The superjunction VDMOS performance in off-state breakdown voltage and specific on-resistance is compared with that in conventional VDMOS structure. In addition, electrical parameters such as threshold voltage and charge balance are also examined. Increasing the superjunction doping in the drift region of VDMOS reduces the on-resistance by 26%, while maintaining the same …
Impact Of Wireless Channel Uncertainty Upon M-Ary Distributed Detection Systems., Zahra Hajibabaei Najafabadi
Impact Of Wireless Channel Uncertainty Upon M-Ary Distributed Detection Systems., Zahra Hajibabaei Najafabadi
Electronic Theses and Dissertations
We consider a wireless sensor network (WSN), consisting of several sensors and a fusion center (FC), which is tasked with solving an $M$-ary hypothesis testing problem. Sensors make $M$-ary decisions and transmit their digitally modulated decisions over orthogonal channels, which are subject to Rayleigh fading and noise, to the FC. Adopting Bayesian optimality criterion, we consider training and non-training based distributed detection systems and investigate the effect of imperfect channel state information (CSI) on the optimal maximum a posteriori probability (MAP) fusion rules and detection performance, when the sum of training and data symbol transmit powers is fixed. Our results …
Advanced Blue Phase Liquid Crystal Displays, Daming Xu
Advanced Blue Phase Liquid Crystal Displays, Daming Xu
Electronic Theses and Dissertations
Thin-film transistor (TFT) liquid crystal displays (LCDs) have become indispensable in our daily lives. Their widespread applications range from smartphones, laptops, TVs to navigational devices, data projectors and wearable displays. Over past decades, massive efforts have been invested in device development, material characterization and manufacturing technology. As a result, the performance of LCDs, such as viewing angle, contrast ratio, color gamut and resolution, have been improved significantly. Nonetheless, there are still urgent needs for fast response time and low power consumption. Fast response time helps reduce motion image blurs and enable color sequential displays. The latter is particularly attractive since …
Passive, Wireless Saw Ofc Strain Sensor And Software Defined Radio Interrogator, James Humphries
Passive, Wireless Saw Ofc Strain Sensor And Software Defined Radio Interrogator, James Humphries
Electronic Theses and Dissertations
Surface acoustic wave (SAW) devices have exhibited unique capabilities to meet the demands for many applications due to the inherent properties of SAW devices and piezoelectric materials. In particular, SAW devices have been adapted as sensors that can be configured to operate both passively and wirelessly. SAW sensors can be operated in harsh environmental extremes where typical sensor technologies are not able to operate. Because the sensors are passive, a radio transceiver is required to interrogate the sensor and receive the reflected response that has been modulated by the SAW device. This dissertation presents the design of a passive, wireless …
A New Path Planning Guidance Law For Improved Impact Time Control Of Missiles And Precision Munitions, Mark Snyder
A New Path Planning Guidance Law For Improved Impact Time Control Of Missiles And Precision Munitions, Mark Snyder
Electronic Theses and Dissertations
A new missile guidance law is proposed for the control of impact time which provides an improved time-to-go calculation by removing error due to trajectory curvature and also provides a family of trajectories for trajectory planning purposes. Unlike conventional optimal guidance laws, the proposed law is non explicit in time-to-go and the linearization of the engagement kinematics in order to gain a closed form solution is not necessary.
Sensing Using Specialty Optical Fibers, Amy Van Newkirk
Sensing Using Specialty Optical Fibers, Amy Van Newkirk
Electronic Theses and Dissertations
Fiber optic based sensing is a growing field with many applications in civil and aerospace engineering, oil and gas industries, and particularly in harsh environments where electronics are not able to function. Optical fibers can be easily integrated into structures, are immune to electromagnetic interference, can be interrogated from remote distances, and can be multiplexed for distributed measurements. Because of these properties, specialty fiber designs and devices are being explored for sensing temperature, strain, pressure, curvature, refractive index, and more. Here we show a detailed analysis of a multicore fiber (MCF) for sensing, including its design and optimization in simulation, …
Three-Dimensional Simulation Study Of Low Voltage (<100v) Superjunction Lateral Dmos Power Transistors, Jhonatan Garcia
Three-Dimensional Simulation Study Of Low Voltage (<100v) Superjunction Lateral Dmos Power Transistors, Jhonatan Garcia
Electronic Theses and Dissertations
A new revolutionary concept was presented two decades ago, known as "semiconductor Superjunction (SJ) theory" to enhance the trade-off relationship between specific on resistance, Rsp, and off-state breakdown voltage, BV, in medium to high voltages (more than 100 V) power MOSFETs. The SJ concept was first applied and commercialized to vertical structures, but it hasn't been used yet in low voltage MOSFETs with lateral structures. This thesis provides a review of the most common structures, principles and design techniques for discrete power MOSFETs. It also presents a simulation study of the application of these SJ concepts in the design of …
Modeling And Compensation For Efficient Human Robot Interaction, Nicholas Paperno
Modeling And Compensation For Efficient Human Robot Interaction, Nicholas Paperno
Electronic Theses and Dissertations
The purpose of this research is to first: identify the important human factors to performance when operating an assistive robotic manipulator, second: develop a predictive model that will be able to determine a user's performance based on their known human factors, and third: develop compensators based on the determined important human factors that will help improve user performance and satisfaction. An extensive literature search led to the selection of ten potential human factors to be analyzed including reaction time, spatial abilities (orientation and visualization), working memory, visual perception, dexterity (gross and fine), depth perception, and visual acuity of both eyes …