Electrical and Computer Engineering Commons^™

Charge Injection And Clock Feedthrough, Jonathan Yu

Master's Theses

Turning off a transistor introduces an error voltage in switched-capacitor circuits. Circuits such as analog-to-digital converters (ADC), digital-to-analog converters (DAC), and CMOS image sensor pixels are limited in performance due to the effects known as charge injection and clock feedthrough. Charge injection occurs in a switched-capacitor circuit when the transistor turns off and disperses channel charge into the source and drain. The source, which is the sampling capacitor, experiences an error in the sampled voltage due to the incoming channel charge. Simultaneously, the coupling due to gate-source overlap capacitance also contributes to the total error voltage, which is known as …

Modeling And Analysis Of Radial Flux Toroidally Wound Twin Rotor Permanent Magnet Motor, Ravi Kishore Pratapa

LSU Master's Theses

The main objective of current thesis is the study of Radial Flux Twin Rotor Permanent Magnet (RFTWTRPM) motor. The tasks were to review the literature about RFTWTPM motors and model the motor using Finite Element Method Magnetics (FEMM 4.0). Later the performance of RFTWTRPM motor as a brushless dc motor was analyzed by using MATLAB/SIMULINK package. To find the electrical and mechanical parameters of the RFTWTRPM motor, the rotor and stator dimensions of the motor were firstly optimized using linear FEMM model of the motor. The optimized dimensions were used to construct the cylindrical FEMM model. This model was later …

Spin-Strain Coupling In A 3-D Transition Metal Oxides, Ghous Bakhsh Narejo

Dissertations, Master's Theses and Master's Reports - Open

ab-initio Hartree Fock (HF), density functional theory (DFT) and hybrid potentials were employed to compute the optimized lattice parameters and elastic properties of perovskite 3-d transition metal oxides. The optimized lattice parameters and elastic properties are interdependent in these materials. An interaction is observed between the electronic charge, spin and lattice degrees of freedom in 3-d transition metal oxides. The coupling between the electronic charge, spin and lattice structures originates due to localization of d-atomic orbitals. The coupling between the electronic charge, spin and crystalline lattice also contributes in the ferroelectric and ferromagnetic properties in perovskites. The cubic and tetragonal …

A Unified Method For Detecting And Isolating Process Faults And Sensor Faults In Nonlinear Systems, Niharika Sonti

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With the increase in the complexity of control systems design and the demand for more productivity, the possibility of the occurrence of faults in control systems has also significantly increased. In this thesis, a unified method for the fault diagnosis of sensor faults and process faults is developed for a class of Lipschitz nonlinear uncertain systems. The fault detection and isolation (FDI) architecture is comprised of a fault detection estimator and a bank of fault isolation estimators (FIEs), where each FIE is designed, based on the functional structure of a particular fault, in the fault class under consideration. The output …

Fabrication Of Zinc Oxide Thin Films For Renewable Energy And Sensor Applications, Theresa Y. Hill

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Progress in commercializing renewable energy technologies is being advanced by developments in Zinc Oxide material science. The photovoltaic cell, for example, generates electricity by receiving solar energy into the cell, generating electrons, and simultaneously transporting electrical charge out of the cell. Metals are capable of removing electrical charge but block transmission of sunshine. Glass and plastics are capable of transmitting sunshine but block the removal of electrical charge. Therefore an exterior layer that is both optically transparent and electrically conductive is desirable. Transparent conductive oxides (TCOs) are the ideal material for such applications since they are capable of both functions. …

On Momentum Conservation And Thermionic Emission Cooling, Raseong Kim, Changwook Jeong, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

The possibility of increasing the performance of thermionic cooling devices by relaxing lateral momentum conservation is examined. Upper limits for the ballistic emission current are established. It is then shown that for most cases, nonconserved lateral momentum model produces a current that exceeds this upper limit. For the case of heterojunctions with a much heavier effective mass in the barrier and with a low barrier height, however, relaxing lateral momentum may increase the current. These results can be simply understood from the general principle that the current is limited by the location, well or barrier, with the smallest number of …

On Landauer Versus Boltzmann And Full Band Versus Effective Mass Evaluation Of Thermoelectric Transport Coefficients, Changwook Jeong, Raseong Kim, Mathieu Luisier, Supriyo Datta

Department of Electrical and Computer Engineering Faculty Publications

Using a full band description of electronic bandstructure, the Landauer approach to diffusive transport is mathematically related to the solution of the Boltzmann transport equation, and expressions for the thermoelectric parameters in both formalisms are presented. Quantum mechanical and semiclassical techniques to obtain from a full description of the bandstructure, E(k)E(k), the density of modes in the Landauer approach or the transport distribution in the Boltzmann solution are compared and thermoelectric transport coefficients are evaluated. Several example calculations for representative bulk materials are presented and the full band results are related to the more common effective mass formalism. Finally, given …

Simulation Of Spin Field Effect Transistors: Effects Of Tunneling And Spin Relaxation On Performance, Yunfei Gao, Tony Low, Mark S. Lundstrom, Dmitri E. Nikonov

Department of Electrical and Computer Engineering Faculty Publications

numerical simulation of spin-dependent quantum transport for a spin field effect transistor is implemented in a widely used simulator, nanoMOS. This method includes the effect of both spin scattering in the channel and the tunneling barrier between the source/drain and the channel. Accounting for these factors permits setting more realistic performance limits for the transistor, especially the magnetoresistance, which is found to be lower compared to earlier predictions. The interplay between tunneling and spin scattering is elucidated by numerical simulation. Insertion of the tunneling barrier leads to an increased magnetoresistance. Simulations are used to explore the tunneling barrier design issues.

Universality Of Non Ohmic Shunt Leakage In Thin Film Solar Cells, Sourabh Dongaonkar, J. D. Sevaites, G. M. Ford, S. Loser, J. Moore, R. M. Gelfand, H. Mohseni, H. W. Hillhouse, R. Agrawal, M. A. Ratner, T. J. Marks, Mark S. Lundstrom, Muhammad A. Alam

Department of Electrical and Computer Engineering Faculty Publications

http://dx.doi.org/10.1063/1.3518509

Abstract can be found at the above link

Detection Statistics Of Multiple-Pulse Optical Signals Through Atmospheric Turbulence, Jacob C. Brandenburg

Wayne State University Dissertations

Statistics are studied for signal detection in optical communication systems operating through the atmosphere. Optical communication systems with which this study is concerned are those that employ intensity modulation and direct detection. Atmospheric turbulence, which is fluctuations in the atmosphere's optical index of refraction, is a hindrance to optical wireless communications because of the signal fades, called scintillation, it causes at the optical receiver. In order to mitigate the deteriorative effect of turbulence on the communications system, the signal length and detection threshold for the signal detector must be properly chosen.

In this study, mathematical models for photoelectron generation in …

Using Bayesian Inference In Design Applications, Chung Yong Chan

Electronic Theses and Dissertations

This dissertation presents a new approach for solving engineering design problems such as the design of antenna arrays and finite impulse response (FIR) filters. In this approach, a design problem is cast as an inverse problem. The tools and methods previously developed for Bayesian inference are adapted and utilized to solve design problems. Given a desired design output, Bayesian parameter estimation and model comparison are employed to produce designs that meet the prescribed design specifications and requirements. In the Bayesian inference framework, the solution to a design problem is the posterior distribution, which is proportional to the product of the …

Optimization Of Inductively Coupled Plasma Dry Etching For Planar Waveguide Fabrication., Lim Weng Hong

Student Works (2010-2019)

Optimization of the Inductively Coupled Plasma (ICP) dry etching process parameters has been carried out. Seven main etching characteristics were considered in order to produce good etching quality. These characteristics are glass etching rates, selectivity of chromium to glass etching rate, channel side wall roughness, channel side wall vertical profile, channel cleanliness, critical dimension and resolution. Several ICP parameters that are affecting the etching characteristic were optimized in this work. These optimised ICP parameters obtained from this work are ICP power (880 W), bias power (45 W), operating chamber pressure (10 mtorr), reactant gas composition, reactant gas flow rate (35sccm …

Energy Reduction In Automotive Paint Shops A Review Of Hybrid/Electric Vehicle Battery Manufacturing, Claudia Patricia Arenas Guerrero

University of Kentucky Master's Theses

Automotive industry is facing fundamental challenges due to the rapid depletion of fossil fuels, energy saving and environmental concerns. The need of sustainable energy development has motivated the research of energy reduction and renewable energy sources. Efficient use of energy in vehicle manufacturing is demanded, as well as an alternative energy source to replace gasoline powered engines. In this thesis, we introduce a case study at an automotive paint shop, where the largest amount of energy consumption of an automotive assembly plant takes place. Additionally, we present a summary of recent advances in the area of hybrid and electrical vehicles …

Design And Evaluation Of An Audio-Frequency Transresistance Amplifier For Magnetic Tape Playback, Thomas R. Salvatierra

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Analog magnetic tape remains a medium of choice for high-fidelity sound recording and reproduction. Some of this fidelity is sacrificed during the tape playback process; an optimized playback preamplifier is therefore critical to the performance of the medium. Existing playback methods integrate the voltage generated across the reproduce head to obtain a signal directly proportional to the remanent magnetic flux of the tape. An alternate playback method proposes the use of a transresistance amplifier to convert flux-proportional reproduce head current directly to voltage. This eliminates the need for voltage integration and minimizes the amount of equalization performed upon playback. Circuit …

The Harmonic Distortion Reduction Of Phase-Angle Fired Scrs Feeding A Resistive Load Using Fuzzy Logic, Matthew A. Clark

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High power silicon controlled rectifiers (SCR) are used in the application of infrared radiation testing. A case study has been performed on a department of defense facility utilizing SCRs to transfer electrical energy to thermal energy. The facility is capable of generating up to 5000 °F across large cross-sectional areas, requiring tens of megawatts of power. The combination of high power, unbalanced loads, and SCR switching generate high harmonic disturbances that offer significant challenges for conventional linear control systems. In addition, unbalanced three-phase distribution systems are difficult to model, specifically during switching transients. Fuzzy logic is used to characterize the …

Development Of An Efficient Super-Resolution Image Reconstruction Algorithm For Implementation On A Hardware Platform, Pestak Thomas C.

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There is a growing demand from numerous commercial and military applications for images with ever-improving spatial resolution. However, there are resolution-limiting factors inherent in all imaging systems. Decreasing pixel sizes and/or increasing sensor arrays are not always viable. Super-Resolution (SR) Image Reconstruction is an image processing technique that restores a high-resolution (HR) image from a series of low-resolution (LR) images of a particular scene. Recently, there has been extensive research on robust SR algorithms used for post-processing. The goal of this thesis is to explore the current SR research and design computationally efficient SR algorithms for real-time processing based on …

A Direction Finding System Using Log Periodic Dipole Antennas In A Sparsely Sampled Linear Array, Jonathan Andrew Weldon

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This thesis explores the use of wide band log periodic dipole array (LPDA) antennas in direction finding systems. A wide band log periodic antenna will be constructed and tested to ensure hardware capability. A novel approach utilizing non-uniform spacing in a linear array will be used to improve the spatial resolution of the direction finding system. These specialized linear arrays are known as minimum redundancy or non-redundant linear arrays.

A Structured Asic Approach To A Radiation Hardened By Design Digital Single Sideband Modulator For Digital Radio Frequency Memories, Thomas B. Pemberton

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Digital Radio Frequency Memories (DRFM) are widely used as modules in digital signal processing. These modules can provide several forms of signal manipulation and storage capabilities. With single event effects caused by environmental radiation the need for a radiation hardened DRFM is increased. Typical radiation hardening involves the use of specialized foundries utilizing proprietary CMOS libraries that are expensive to build or adding lead packages around a chip that is expensive and add weight to the chip. An alternative radiation hardening technique is to utilize a radiation hardened by design library. This library includes digital gates that have been hardened …

Frequency Domain Processing Based Chaos Communication For Cognitive Radio, Daniel Y. Sundersingh

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Chaotic systems are deterministic non-linear dynamical systems which have intrinsic properties such as: irregularity, aperiodicity, and are impossible to predict over long periods of time. Cognitive radio on the other hand, has emerged recently as a powerful means to tackle the spectrum congestion problem. The goal of this thesis is to combine the benefits of the chaos communication system with the cognitive radio to create a robust, highly secure, flexible chaotic cognitive radio system. We first begin with a short survey of chaotic communication and cognitive radio technology. Then we compare chaotic waveforms to other conventional PN sequences and show …

Wideband, High Data Rate Ku-Band Modulator Driver Amplifier For High Reliability Spaceborne Applications, Jeremy D. Gassmann

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The increased demand for high resolution satellite imagery for government, military, and commercial applications is driving the need for high data rate, millimeter-wave transmission systems to relay imagery information to a ground-based end user. An important aspect of this system which interfaces digital information to the RF domain is the modulator driver. The current trend in miniaturization of electronics leaves systems more vulnerable to single-event radiation effects in spaceborne applications. In an effort to overcome this deficiency, a wideband, high data rate modulator driver circuit has been designed, built, and tested using only high reliability space rated electronic components. To …