Electrical and Electronics Commons^™

Analysis And Design Optimization Of Multiphase Converter, Kejiu Zhang

Electronic Theses and Dissertations

Future microprocessors pose many challenges to the power conversion techniques. Multiphase synchronous buck converters have been widely used in high current low voltage microprocessor application. Design optimization needs to be carefully carried out with pushing the envelope specification and ever increasing concentration towards power saving features. In this work, attention has been focused on dynamic aspects of multiphase synchronous buck design. The power related issues and optimizations have been comprehensively investigated in this paper. In the first chapter, multiphase DC-DC conversion is presented with background application. Adaptive voltage positioning and various nonlinear control schemes are evaluated. Design optimization are presented …

Rf Power Amplifier And Oscillator Design For Reliability And Variability, Shuyu Chen

Electronic Theses and Dissertations

CMOS RF circuit design has been an ever-lasting research field. It gained so much attention since RF circuits have high mobility and wide band efficiency, while CMOS technology has the advantage of low cost and better capability of integration. At the same time, IC circuits never stopped scaling down for the recent many decades. Reliability issues with RF circuits have become more and more severe with device scaling down: reliability effects such as gate oxide break down, hot carrier injection, negative bias temperature instability, have been amplified as the device size shrinks. Process variability issues also become more predominant as …

Investigation On Electrical Properties Of Rf Sputtered Deposited Bcn Thin Films, Adithya Prakash

Electronic Theses and Dissertations

The ever increasing advancements in semiconductor technology and continuous scaling of CMOS devices mandate the need for new dielectric materials with low-k values. The interconnect delay can be reduced not only by the resistance of the conductor but also by decreasing the capacitance of dielectric layer. Also cross-talk is a major issue faced by semiconductor industry due to high value of k of the inter-dielectric layer (IDL) in a multilevel wiring scheme in Si ultra large scale integrated circuit (ULSI) devices. In order to reduce the time delay, it is necessary to introduce a wiring metal with low resistivity and …

A Novel Nonlinear Mason Model And Nonlinear Distortion Characterization For Surface Acoustic Wave Duplexers, Li Chen

Electronic Theses and Dissertations

Surface acoustic wave (SAW) technology has been in use for well over one century. In the last few decades, due to its low cost and high performance, this technology has been widely adopted in modern wireless communication systems, to build filtering devices at radio frequency (RF). SAW filters and duplexers can be virtually found inside every mobile handset. SAW devices are traditionally recognized as passive devices with high linear signal processing behavior. However, recent deployments of third generation (3G) and fourth generation (4G) mobile networks require the handsets to handle an increasing number of frequency bands with more complex modulation …

Polymer Optical Fibers For Luminescent Solar Concentration, Esmaeil Banaei

Electronic Theses and Dissertations

Luminescent solar concentrators (LSC’s) are promising candidates for reducing the cost of solar power generation. Conventional LSC’s are slab waveguides coated or doped with luminescence materials for absorption and guiding of light to the slab edges in order to convert optical energy into electricity via attached photovoltaic (PV) cells. Exploiting the advantages of optical fiber production, a fiber LSC (FLSC) is presented in this thesis, in which the waveguide is a polymeric optical fiber. A hybrid fiber structure is proposed for an efficient two-stage concentration of incident light, first into a small doped core using a cylindrical micro-lens that extends …

Transient And Distributed Algorithms To Improve Islanding Detection Capability Of Inverter Based Distributed Generation, Mohamed Al Hosani

Electronic Theses and Dissertations

Recently, a lot of research work has been dedicated toward enhancing performance, reliability and integrity of distributed energy resources that are integrated into distribution networks. The problem of islanding detection and islanding prevention (i.e. anti-islanding) has stimulated a lot of research due to its role in severely compromising the safety of working personnel and resulting in equipment damages. Various Islanding Detection Methods (IDMs) have been developed within the last ten years in anticipation of the tremendous increase in the penetration of Distributed Generation (DG) in distribution system. This work proposes new IDMs that rely on transient and distributed behaviors to …

Distributed Extremum Seeking And Cooperative Control For Mobile Cooperative Communication Systems, Said Alabri

Electronic Theses and Dissertations

In this thesis, a distributed extremum seeking and cooperative control algorithm is designed for mobile agents to disperse themselves optimally in maintaining communication quality and maximizing their coverage. The networked mobile agents locally form a virtual multiple-input multipleoutput (MIMO) communication system, and they cooperatively communicate among them by using the decode and forward cooperative communication technique. The outage probability is used as the measure of communication quality, and it can be estimated real-time. A general performance index balancing outage probability and spatial dispersion is chosen for the overall system. The extremum seeking control approach is used to estimate and optimize …

Holistic Representations For Activities And Crowd Behaviors, Berkan Solmaz

Electronic Theses and Dissertations

In this dissertation, we address the problem of analyzing the activities of people in a variety of scenarios, this is commonly encountered in vision applications. The overarching goal is to devise new representations for the activities, in settings where individuals or a number of people may take a part in specific activities. Different types of activities can be performed by either an individual at the fine level or by several people constituting a crowd at the coarse level. We take into account the domain specific information for modeling these activities. The summary of the proposed solutions is presented in the …

Multi-Physics Model Of Key Components In High Efficiency Vehicle Drive, Shao Hua Lin

Electronic Theses and Dissertations

Hybrid Electric Vehicles (HEVs) and Electric Vehicles (EVs) are crucial technologies for the automotive industry to meet society’s demands for cleaner, more energy efficient transportation. Meeting the need to provide power which sustains HEVs and EVs is an immediate area of concern that research and development within the automotive community must address. Electric batteries and electrical motors are the key components in HEV and EV power generation and transmission, and their performance plays very important role in the overall performance of the modern high efficiency vehicles. Therefore, in this dissertation, we are motivated to study the electric batteries, interior permanent …

Monolithically Integrated Broadly Tunable Light Emitters Based On Selectively Intermixed Quantum Wells, Abdullah Zakariya

Electronic Theses and Dissertations

A monolithically integrated broadly tunable MQW laser that utilizes a combined impurity-free vacancy disordering (IFVD) of quantum wells and optical beam steering techniques is proposed and investigated experimentally. The device consists of a beam-steering section and an optical amplifier section fabricated on a GaAs/AlGaAs quantum well (QW) p-i-n heterostructure. The beam steering section forms a reconfigurable optical waveguide that can be moved laterally by applying separately controlled electrical currents to two parallel contact stripes. The active core of the gain section is divided in into selectively intermixed regions. The selective intermixing of the QW in the gain section results in …

Microstrip Patch Electrically Steerable Parasitic Array Radiators, Justin Luther

Electronic Theses and Dissertations

This dissertation explores the expansion of the Electrically Steerable Parasitic Array Radiator (ESPAR) technology to arrays using microstrip patch elements. Scanning arrays of two and three closely-coupled rectangular patch elements are presented, which incorporate no phase shifters. These arrays achieve directive radiation patterns and scanning of up to 26° with maintained impedance match. The scanning is effected by tunable reactive loads which are used to control the mutual coupling between the elements, as well as additional loads which compensate to maintain the appropriate resonant frequency. The design incorporates theoretical analysis of the system of coupled antennas with full-wave simulation. A …

Optimization And Design Of Photovoltaic Micro-Inverter, Qian Zhang

Electronic Theses and Dissertations

To relieve energy shortage and environmental pollution issues, renewable energy, especially PV energy has developed rapidly in the last decade. The micro-inverter systems, with advantages in dedicated PV power harvest, flexible system size, simple installation, and enhanced safety characteristics are the future development trend of the PV power generation systems. The double-stage structure which can realize high efficiency with nice regulated sinusoidal waveforms is the mainstream for the micro-inverter. This thesis studied a double stage micro-inverter system. Considering the intermittent nature of PV power, a PFC was analyzed to provide additional electrical power to the system. When the solar power …

Ultrafast Laser Material Processing For Photonic Applications, Mark Ramme

Electronic Theses and Dissertations

Femtosecond Laser Direct Writing (FLDW) is a viable technique for producing photonic devices in bulk materials. This novel manufacturing technique is versatile due to its full 3D fabrication capability. Typically, the only requirement for this process is that the base material must be transparent to the laser wavelength. The modification process itself is based on non-linear energy absorption of laser light within the focal volume of the incident beam. This thesis addresses the feasibility of this technique for introducing photonic structures into novel dielectric materials. Additionally, this work provides a deeper understanding of the lightmatter interaction mechanism occurring at high …

Power Quality Improvement Of Distributed Generation Integrated Network With Unified Power Quality Conditioner., Shafiuzzaman Khan Khadem

Doctoral

With the increased penetration of small scale renewable energy sources in the electrical distribution network, maintenance or improvement of power quality has become more critical than ever where the level of voltage and current harmonics or disturbances can vary widely. For this reason, Custom Power Devices (CPDs) such as the Unified Power Quality Conditioner (UPQC) can be the most appropriate solution for enhancing the dynamic performance of the distribution network, where accurate prior knowledge may not be available. Therefore, the main objective of the present research is to investigate the (i) placement (ii) integration (iii) capacity enhancement and (iv) real …

Non-Uniform Transmission Lines For Ultra Wideband: Design Optimisation And Interfacing To Antennas And Loads, Prasanth Moolakuzhy Narayanan

Theses

This thesis presents the electrical characterization of ultra-wideband non- uniform transmission lines (UWB NUTLs). Non-uniform transmission lines have been identified as a successful device for ultra-wideband pulse shaping, which can be designed to generate complex and arbitrary pulse shapes as an impulse response. The performance of a range of UWB NUTLs, with different substrate materials and load impedances, has been characterised. In addition, the possibility of interfacing NUTL with antennas and the filtering effect of antennas has been investigated. To characterise the NUTLs, knowledge of current literature related to NUTL designs is required. A detailed review of the literature published …

Vision Based Real-Time Monitoring And Control Of Metal Transfer In Laser Enhanced Gas Metal, Yan Shao

Theses and Dissertations--Electrical and Computer Engineering

Laser enhanced gas metal arc welding (GMAW) is a novel welding process where a laser is applied to provide an auxiliary detaching force to help detach the droplet such that welds may be made in gas tungsten arc welding high quality at GMAW high speeds. The current needed to generate the electromagnetic (detaching) force is thus reduced. The reduction in the current helps reduce the impact on the weld pool and over-heat fumes/smokes. However, in the previous studies, a continuous laser is applied. Since the auxiliary is only needed each time the droplet needs to be detached and the detachment …

Power Control Of Single-Stage Pv Inverter For Distribution System Volt-Var Optimization, Xiao Liu

Theses and Dissertations--Electrical and Computer Engineering

The output power variability of intermittent renewable sources can cause significant fluctuations in distribution system voltages. A local linear controller that exploits the capability of a photovoltaic inverter to provide both real and reactive power is described. This controller substitutes reactive power for real power when fluctuations in the output of the photovoltaic source are experienced. In this way, the inverter can help mitigate distribution system voltage fluctuations. In order to provide real and reactive to the grid, a three-phase grid-connected single-stage photovoltaic system with maximum power point tracking and power control is described. A method of reducing the current …

Assessing Performance Of Ncep Rapid Refresh Model To Predict Boundary Layer Properties, David Daniel

Dissertations and Theses

There is a need to be able to estimate the relative humidity in the Planetary Boundary Layer (PBL) since relative humidity can affect aerosol retrieval. Satellite retrievals of Relative Humidity are extremely complicated since they need to resolve 1km vertical resolution for temperature and water vapor. The AIRS hyperspectral sensor may be able to retrieve relative humidity with 20% RMSE but low correlations with R² – 0.4. The alternative is to explore meteorological forecasts (i.e. Rapid Refresh) to see if we can use them in the processing stream for aerosols. While the state of delay zero is assimilated, the …

Tunable Fano Resonances Based On Two-Beam Interference In Microring Resonator, Ting Hu, Ping Yu, Chen Qui, Huiye Qui, Fan Wang, Mei Yang, Xiaoqing Jiang, Hui Yu, Jianyi Yang

Electrical & Computer Engineering Faculty Research

In this paper, a resonant system is demonstrated on silicon-on-insulator wafer to achieve tunable Fano resonances. In this system, the Fano resonance originates from the interference of two beams resonant in the microring resonator. The shapes of the Fano resonances are tunable through controlling the phase difference of the two beams. Both large slope and high extinctionratio (ER) are obtained when the phase difference is 0.5π or 1.5π. Experimental results show that Fano resonances with steep slope and ER over 20 dB are achieved in the whole free spectral range by controlling the microheaters to meet the phase condition.

Estimation Of Performance Indices For The Planning Of Sustainable Transportation Systems, Alexander Paz, Pankaj Maheshwari

Electrical & Computer Engineering Faculty Research

In the context of sustainable transportation systems, previous studies have either focused only on the transportation systemor have not used a methodology that enables the treatment of incomplete, vague, and qualitative information associated with the available data. This study proposes a system of systems (SOS) and a fuzzy logic modeling approach. The SOS includes the Transportation, Activity, and Environment systems. The fuzzy logic modeling approach enables the treatment of the vagueness associated with some of the relevant data. Performance Indices (PIs) are computed for each system using a number of performance measures. The PIs illustrate the aggregated performance of each …

Framework For Simulation Of Heterogeneous Mpsoc For Design Space Exploration, Bisrat Tafesse, Venkatesan Muthukumar

Electrical & Computer Engineering Faculty Research

Due to the ever-growing requirements in high performance data computation, multiprocessor systems have been proposed to solve the bottlenecks in uniprocessor systems. Developing efficient multiprocessor systems requires effective exploration of design choices like application scheduling, mapping, and architecture design. Also, fault tolerance in multiprocessors needs to be addressed. With the advent of nanometer-process technology for chip manufacturing, realization of multiprocessors on SoC (MpSoC) is an active field of research. Developing efficient low power, fault-tolerant task scheduling, and mapping techniques for MpSoCs require optimized algorithms that consider the various scenarios inherent in multiprocessor environments. Therefore there exists a need to develop …

Elec 2110: Elements Of Electrical Engineering—A Peer Review Of Teaching Project Benchmark Portfolio, Mahmoud Alahmad

UNL Faculty Course Portfolios

I have been teaching this class for the last five years. As an introductory course to electrical engineering, there is a lot of material that needs to be covered. All the material is important and relevant, and I try to go in-depth in each topic area. This approach has resulted in overwhelming the students and made them struggle with the course content, application and utilization. As I consider this course for the peer review, I am evaluating the depth of each topic and the opportunity to adjust the approach and method used to introduce new concepts and at the same …

Integration Of Memristors With Mems For Dynamic Displacement Control, Sergio Fabian Almeida Loya

Open Access Theses & Dissertations

In recent years the demand for high-speed, lower power consumption and large-capacity non-volatile memories has increased. Promisingly the memristor can be used due to its special characteristic of having memory through resistance change. The memristor behavior is not limited to digital applications but it can be used in analog application as well including: memristors in chaotic circuits, amoeba's learning, neural synaptic emulation, reprogrammable and reconfigurable circuits, and for neuromorphic computers. On the other hand Micro Electro Mechanical Systems (MEMS) are small scale structures that can interact with the physical world due to their mechanical properties. These devices are widely used …

Reduction Of Onu Buffering For Pon/Vdsl Hybrid Access Networks, Elliott Ivan Gurrola

Open Access Theses & Dissertations

Today's growing internet traffic requires service providers to offer customers faster transmission rates. To keep up with such high transmission rates, service providers need to deploy fiber optical networks. However, due to the high cost involved in deploying the fiber media, this may not prove to be a feasible solution. Instead, service providers can deploy fiber media up to a distribution point, such as a customer's block, and continue the last few hundred feet using the already deployed legacy copper wire media.

In our study we investigate downstream/upstream transmission coordination for passive optical network (PON) / Digital Subscriber Line (DSL) …

Structural, Optical And Electrical Properties Of Yttrium-Doped Hafnium Oxide Nanocrystalline Thin Films, Abhilash Kongu

Open Access Theses & Dissertations

Hafnium oxide (HfO2) has emerged as the most promising high-k dielectric for Metal-Oxide-Semiconductor (MOS) devices and has been highlighted as the most suitable dielectric materials to replace silicon oxide because of its comprehensive performance. In the present research, yttrium-doped HfO2 (YDH) thin films were fabricated using RF magnetron sputter deposition onto Si (100) and quartz with a variable thickness. Cross-sectional scanning electron microscopy coupled with Filmetrics revealed that film thickness values range from 700 A° to 7500 A°. Electrical properties such as AC Resistivity and current-voltage (I-V) characteristics of YDH films were studied. YDH films that were relatively thin (<1500 A°) crystallized in monoclinic phase while thicker films crystallized in cubic phase. The band gap (Eg) of the films was calculated from the optical measurements. The band gap was found to be ∼5.60 eV for monoclinic while it is ∼6.05 eV for cubic phase of YDH films. Frequency dependence of the electrical resistivity (ρac) and the total conductivity of the films were measured. Resistivity decreased (by three orders of magnitude) with increasing frequency from 100 Hz to 1 MHz, attributed due to the hopping mechanism in YDH films. Whereas, while ρac∼1Ω-m at low frequencies (100 Hz), it decreased to ∼ 104 Ω-cm at higher frequencies (1 MHz). Aluminum (Al) metal electrodes were deposited to fabricate a thin film capacitor with YDH layer as dielectric film thereby employing Al-YDH-Si capacitor structure. The results indicate that the capacitance of the films decrease with increasing film thickness. A detailed analysis of the electrical characteristics of YDH films is presented.

Assessment And Evaluation Of The Dynamic Behavior Of Muscles With Special Reference To Subjects With Diabetes Mellitus, Jorge Garza-Ulloa

Open Access Theses & Dissertations

Diabetes mellitus (simply diabetes) is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced. Each year, the costs of diabetes rise. Diabetes and its complications cost our national economy. Two new methods are proposed to measure the diabetes implications in the muscles of lower body: Muscle energy expenditure analysis based on the detection of muscle transition-to-fatigue, and Natural Fuzzy logic method for differential analysis in muscle/joint. Then the results are compared with the traditional method …

Anasic Design And Test Methodology For An Undergraduate Design And Fabrication Project, Arun Joseph Kurian

Open Access Theses & Dissertations

During the 1990's the main focus of chip design methodologies was on the timings and area constraints. Power consumption was considered significant only after a drastic increase of device densities from 130nm on as well as dramatic increases in sub threshold leakage. As technology advanced from 130nm to 90nm and below there was a significant increase in leakage current due to lower threshold voltage and the influence of the deep submicron effects. High power consumption causes different problems such as increasing the cost of the product, reducing the reliability, reducing the battery life among others. Therefore EDA tools were designed …

Efficient, Scalable, Parallel, Matrix-Matrix Multiplication, Enrique Portillo

Open Access Theses & Dissertations

For the past decade, power/energy consumption has become a limiting factor for large-scale and embedded High Performance Computing (HPC) systems. This is especially true for systems that include accelerators, e.g., high-end computing devices, such as Graphics Processing Units (GPUs), with terascale computing capabilities and high power draws that greatly surpass that of multi-core CPUs. Accordingly, improving the node-level power/energy efficiency of an application can have a direct and positive impact on both classes of HPC systems.

The research reported in this thesis explores the use of software techniques to enhance the execution-time and power-consumption performance of applications executed on a …

Asynchronous Logic Design With Increased Fault Tolerance And Optimized For Subthreshold Operation, Ivan Santos

Open Access Theses & Dissertations

Synchronization has always been an essential feature in electronic circuits, in which functionality is achieved by an appropriate flow of data with respect to time. An ideal concept of logic design would require every operation to happen instantly; however, the application of this principle to electronics is governed by the laws of physics, which influence the time to execute a process. In fact, the speed at which a microprocessor can perform logic operations is determined by the time that charging and discharging capacitive loads requires, and the time that electric signals spend when traveling through the circuitry. Consequently, the variation …

3d Printed Impedance Elements By Micro-Dispensing, Ubaldo Robles Dominguez

Open Access Theses & Dissertations

Micro-dispensing allows electric circuits to be "3D printed," which can be used to give 3D printed systems electronic and electromagnetic functionality. The focus of this thesis is using micro-dispensing to fabricate capacitors and inductors. 3D printed impedance elements are capable of being more easily embedded, can be used to create structural electronics, and will have extensive applications in antennas, metamaterials, frequency selective surfaces, and more. This is the first known effort to print and measure impedance elements by micro-dispensing which holds great potential for manufacturing multi-material devices.