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Articles 1 - 18 of 18
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Metal-Insulator-Insulator-Metal Plasmonic Waveguides And Devices, Jing Chen
Metal-Insulator-Insulator-Metal Plasmonic Waveguides And Devices, Jing Chen
Electrical and Computer Engineering ETDs
Metal-insulator-metal (MIM) plasmonic waveguides have been proposed for highly integrated subwavelength structures. In this work, waveguiding and coupling of surface plasmon polaritons (SPPs) within finite planar MIM plasmonic waveguides are examined both theoretically and experimentally. Gain (dye-doped polymer)-assisted MIM waveguides and terahertz quantum cascade laser MIM waveguides are numerically analyzed. The numerical analysis of finite planar MIM waveguides using the transfer matrix formalism reveals both bound and leaky SP modes: three lowest energy bound modes and the highest energy mode consisting of non-radiative (bound) and radiative (leaky) portions separated by a spectral gap at the light line. The leaky regime …
Distributed Load Balancing Over Directed Network Topologies, Alejandro Gonzalez Ruiz
Distributed Load Balancing Over Directed Network Topologies, Alejandro Gonzalez Ruiz
Electrical and Computer Engineering ETDs
Due to the increasing demand for high performance computing and the increasing availability of high speed networks, it has become possible to interconnect various geographically distributed computational elements (nodes) so that they can work cooperatively and obtain a performance not attainable by individual nodes. In the literature, distributing the total computation load across available processors is referred to as load balancing. This thesis considers the problem of distributed load balancing over directed graphs that are not fully connected. The impact of network topology on the stability and balance of distributed computing is studied. Furthermore, Informed Load Balancing (I-LB) is proposed. …
High-Speed Dynamic Partial Reconfiguration For Field Programmable Gate Arrays, John Hoffman
High-Speed Dynamic Partial Reconfiguration For Field Programmable Gate Arrays, John Hoffman
Electrical and Computer Engineering ETDs
With dynamically and partially reconfigurable designs, it is necessary that the speed of the reconfiguration be accomplished in a time that is sufficiently small such that the operation of reconfiguration is not the limiting factor in the process. Therefore, the communication between the source of configuration and the configurable unit must be made as fast as possible. The aim of this work is to use an embedded controller internal to the FPGA to control the reconfiguration process and obtain the maximum speed at which reconfiguration can occur, with current FPGA technology. The use of Direct Memory Access (DMA) driven operations …
Control For An Optically Powered Firing Set Using Miniature Photovoltaic Arrays, Todd Plichta
Control For An Optically Powered Firing Set Using Miniature Photovoltaic Arrays, Todd Plichta
Electrical and Computer Engineering ETDs
The optically powered firing set looks to revolutionize the design of future electrical firing sets. Optically powered devices have many features that make them attractive, such as immunity to noise problems from Electromagnetic Interference (EMI) and Electromagnetic Radiation (EMR). Also, optically powered devices provide additional safety to prevent unintended usage and are small in volume in comparison to their electrical equivalent. These advancements have led to the design of a prototype firing set developed at Sandia National Laboratories. The main components are comprised of a miniature photovoltaic array (MPA) that transforms light energy to electrical energy and a capacitive discharge …
Control And Filtering Of Time-Varying Linear Systems Via Parameter Dependent Lyapunov Functions, Renato Alves Borges
Control And Filtering Of Time-Varying Linear Systems Via Parameter Dependent Lyapunov Functions, Renato Alves Borges
Electrical and Computer Engineering ETDs
The main contribution of this dissertation is to propose conditions for linear filter and controller design, considering both robust and parameter dependent structures, for discrete time-varying systems. The controllers, or filters, are obtained through the solution of optimization problems, formulated in terms of bilinear matrix inequalities, using a method that alternates convex optimization problems described in terms of linear matrix inequalities. Both affine and multi-affine in different instants of time (path dependent) Lyapunov functions were used to obtain the design conditions, as well as extra variables introduced by the Finsler's lemma. Design problems that take into account an H-infinity guaranteed …
Rectangular Waveguide Narrow-Wall Longitudinal-Aperture Antenna Arrays For High-Power Applications, Naga Ravi Kanth Devarapalli
Rectangular Waveguide Narrow-Wall Longitudinal-Aperture Antenna Arrays For High-Power Applications, Naga Ravi Kanth Devarapalli
Electrical and Computer Engineering ETDs
This work deals with the design and bench test of rectangular waveguide narrow-wall longitudinal-aperture antenna arrays for high power applications. The best narrow-wall longitudinal-aperture array designs in the work are called the double-narrow-wall-slot-HPB-array and the double-split-waveguide-HPB-array. The double-narrow-wall-slot-HPB-array (double-split-waveguide-HPB-array) consists of two identical narrow-wall-slot-HPB-arrays (split-waveguide-HPB-arrays) with a common broad wall. All elements of the split-waveguide-HPB-array are identical and are called H-plane-bend-radiators (HPB-radiators). An HPB-radiator is an H-plane bend terminating in a radiating aperture with the narrow dimension of the waveguide flaring out. Optimizing the HPB-radiators performance involves designing its aperture dimensions and the function that determines the H-plane taper to …
Optimal Spectral Reconstructions From Deterministic And Stochastic Sampling Geometries Using Compressive Sensing And Spectral Statistical Models, Oliver Jeromin
Optimal Spectral Reconstructions From Deterministic And Stochastic Sampling Geometries Using Compressive Sensing And Spectral Statistical Models, Oliver Jeromin
Electrical and Computer Engineering ETDs
This dissertation focuses on the development of high-quality image reconstruction methods from a limited number of Fourier samples using optimized, stochastic and deterministic sampling geometries. Two methodologies are developed: an optimal image reconstruction framework based on Compressive Sensing (CS) techniques and a new, Spectral Statistical approach based on the use of isotropic models over a dyadic partitioning of the spectrum. The proposed methods are demonstrated in applications in reconstructing fMRI and remote sensing imagery. Typically, a reduction in MRI image acquisition time is achieved by sampling K-space at a rate below the Nyquist rate. Various methods using correlation between samples, …
Automating The Moderation Process In Geo Using Trust Metrics, Harihar Shankar
Automating The Moderation Process In Geo Using Trust Metrics, Harihar Shankar
Electrical and Computer Engineering ETDs
Distributed knowledge bases offer novel and fascinating ways to build, integrate and process knowledge. In these distributed knowledge bases, many users collaborate and contribute content. Verification and validation of the user's contributions become imperative for the success of these knowledge bases, especially if it is a scientific knowledge base. However, manually verifying and moderating the contributions become a bottleneck for an up-to-date system. In this thesis, we propose an algorithm to automate the moderation process and we implement the algorithm in an open scientific knowledge base application called Global Energy Observatory (GEO). Using Trust Metrics, user's contributions can be automatically …
Circuit Designs For Low-Power And Seu-Hardened Systems, Vallabh Srikanth Devarapalli
Circuit Designs For Low-Power And Seu-Hardened Systems, Vallabh Srikanth Devarapalli
Electrical and Computer Engineering ETDs
The desire to have smaller and faster portable devices is one of the primary motivations for technology scaling. Though advancements in device physics are moving at a very good pace, they might not be aggressive enough for now-a-day technology scaling trends. As a result, the MOS devices used for present day integrated circuits are pushed to the limit in terms of performance, power consumption and robustness, which are the most critical criteria for almost all applications. Secondly, technology advancements have led to design of complex chips with increasing chip densities and higher operating speeds. The design of such high performance …
End-To-End Provisioning In Multi-Domain/Multi-Layer Networks, Tannous Frangieh
End-To-End Provisioning In Multi-Domain/Multi-Layer Networks, Tannous Frangieh
Electrical and Computer Engineering ETDs
The last decade has seen many advances in high-speed networking technologies. At the Layer 1 fiber-optic level, dense wavelength division multiplexing (DWDM) has seen fast growth in long-haul backbone/metro sectors. At the Layer 1.5 level, revamped next-generation SONET/SDH (NGS) has gained strong traction in the metro space, as a highly flexible sub-rate' aggregation and grooming solution. Meanwhile, ubiquitous Ethernet (Layer 2) and IP (Layer 3) technologies have also seen the introduction of new quality of service (QoS) paradigms via the differentiated services (Diff-Serv) and integrated services (Intserv) frameworks. In recent years, various control provisioning standards have also been developed to …
Single Event Upset Hardened Cmos Combinational Logic And Clock Buffer Design, Aahlad Mallajosyula
Single Event Upset Hardened Cmos Combinational Logic And Clock Buffer Design, Aahlad Mallajosyula
Electrical and Computer Engineering ETDs
A radiation strike on semiconductor device may lead to charge collection, which may manifest as a wrong logic level causing failure. Soft errors or Single Event Upsets (SEU) caused by radiation strikes are one of the main failure modes in a VLSI circuit. Previous work predicts that soft error rate may dominate the failure rate in VLSI circuit compared to all other failure modes put together. The issue of single event upsets (SEU) need to be addressed such that the failure rate of the chips dues to SEU is in the acceptable range. Memory circuits are designed to be error …
Double-Interval Technique For Higher Order Harmonic Generation Of A Quantum Dot Mode-Locked Laser, Furqan Chiragh
Double-Interval Technique For Higher Order Harmonic Generation Of A Quantum Dot Mode-Locked Laser, Furqan Chiragh
Electrical and Computer Engineering ETDs
As the speed barrier is reached in traditional integrated circuits, the need to produce ultra-fast optical pulses is of growing importance. By using optical pulses as clock sequence generators, it is possible to overcome the bottlenecks due to RC delays and the excessive power consumption of todays technology. In this thesis a quantum dot mode-locked laser is passively locked and using the double-interval technique achieves higher order harmonics. The double-interval technique is commonly used with musicians to create false harmonics while they strum their instruments. When a violinist places his finger upon a string he creates a node that changes …
Am-Fm Methods For Image And Video Processing, Victor Manuel Murray Herrera
Am-Fm Methods For Image And Video Processing, Victor Manuel Murray Herrera
Electrical and Computer Engineering ETDs
This dissertation is focused on the development of robust and efficient Amplitude-Modulation Frequency-Modulation (AM-FM) demodulation methods for image and video processing (there is currently a patent pending that covers the AM-FM methods and applications described in this dissertation). The motivation for this research lies in the wide number of image and video processing applications that can significantly benefit from this research. A number of potential applications are developed in the dissertation. First, a new, robust and efficient formulation for the instantaneous frequency (IF) estimation: a variable spacing, local quadratic phase method (VS-LQP) is presented. VS-LQP produces much more accurate results …
Investigation Into The Use Of High-Efficiency Switched-Mode Class E Power Amplifiers For High-Dynamic Range Pulse-Mode Applications, Jesse Lai
Electrical and Computer Engineering ETDs
In typical communication and radar systems, the transmitter is operated in either a continuous wave or a pulsed mode where the transmitter is periodically turned on for a portion of time. These systems commonly use a power amplifier in the transmitter to raise the power level of the transmitted signal to a value sufficient to meet system sensitivity requirements. In high-dynamic range systems, the power amplifier pulse must turn off at a rate compatible with the system noise floor at the receive time. Some high-dynamic range systems are sensitive to signals greater than 120 dB below the transmit power level, …
Analysis, Design, And Implementation Of A Reconfigurable Fractal Volumetric Left-Handed Metamaterial, Teofilo Max De La Mata Luque
Analysis, Design, And Implementation Of A Reconfigurable Fractal Volumetric Left-Handed Metamaterial, Teofilo Max De La Mata Luque
Electrical and Computer Engineering ETDs
At the present time, one of the greatest goals to exploit the advantages of Volumetric Left-handed Metamaterials (LHM) is overcoming their very narrow operational bandwidth. This thesis proposes two schemes to efficiently solve this difficulty: 1) a mechanism which reconfigures, at will, the frequency the LHM operates at, and 2) a novel arrangement of Split Ring Resonators (SRR) based on the Sierpi\u0144ski carpet fractal pattern with two SRR sizes. Reconfigurability is implemented by cutting two splits of different widths in each ring of the SRRs. These SRRs are simulated with switches in the ON and OFF states inside an ideal …
Development Of Indium Arsenide Quantum Dot Solar Cells For High Conversion Efficiency, Mohamed El-Emawy
Development Of Indium Arsenide Quantum Dot Solar Cells For High Conversion Efficiency, Mohamed El-Emawy
Electrical and Computer Engineering ETDs
Sunlight is the largest energy source available on earth. Under clear conditions there is approximately 1,000 watts per directly incident square meter, which reaches the earth everyday. Solar cells are devices that can be used to collect such abundant form of energy and convert it into electrical energy for daily consumption. Therefore, it is important to research this subject in order to obtain high efficiency solar cells. In this thesis InAs quantum dot (QD) solar cells are studied and investigated. The theory of using QDs as an intermediate band in GaAs-based solar cells is introduced. Three samples are grown for …
Electromagnetic Modeling Of Hot-Wire Detonators Using Analytical And Numerical Methods With Comparison To Experiment, Michael Lambrecht
Electromagnetic Modeling Of Hot-Wire Detonators Using Analytical And Numerical Methods With Comparison To Experiment, Michael Lambrecht
Electrical and Computer Engineering ETDs
The electromagnetic (EM) characteristics of hot-wire detonators are determined in order to quantify more precisely their response to EM illumination. The analyses include a comprehensive study of detonators physical characteristics, which is then used to model detonators using transmission line theory. The theoretical analysis treats the detonator as a cascaded transmission line incorporating several different dielectrics, and examines both differential and common mode excitation for a generic detonator model. This 1-D analytical model is implemented in MatLAB and used to determine the input impedance of the detonator for a frequency range spanning DC to 9 GHz. This program can then …
Synthesis And Characterization Of Cerium-Doped Lanthanum Halide Colloidal Nanocrystals, Krishnaprasad Sankar
Synthesis And Characterization Of Cerium-Doped Lanthanum Halide Colloidal Nanocrystals, Krishnaprasad Sankar
Electrical and Computer Engineering ETDs
Cerium-doped bulk lanthanum halide compounds are attractive in the field of high-energy radiation detection due to their interesting properties that include efficient radiation absorption, highly luminescent activator (cerium) emission through atomic transitions, host lattice protecting activators to prevent luminescence quenching, and fast decay-time radiative transitions between cerium levels. Cerium-doped bulk lanthanum bromide is reported to have a light yield of 60,000 photons/MeV, 2.5% full-width-to-half-maximum energy resolution (variation in emission light yield to absorbed gamma energy) for 662 keV gamma rays, 25 ns short decay time, and a density of 5.3 g/cm3 with 22 mm attenuation length for 511 keV gamma …