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Full-Text Articles in Engineering
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 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 …
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 …
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 …
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 …
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) …
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 …