Electrical and Electronics Commons^™

Applying Frequency-Domain Equalization To Code-Division Multiple Access And Transform-Domain Communications Systems, Alfred A. Tamayo Iii

Theses and Dissertations

This research examined the theory and application of using orthogonal frequency division multiplexing (OFDM), or discrete multi-tone (DMT), frequency domain equalization (FEQ) with two communications systems that inherently possess unused carrier frequencies, or null-tones, in their respective transmission frequencies. The fundamental DMT-FEQ property relies on null-tones to equalize a non-ideal channel and mitigate the effects of interchannel interference (ICI), intersymbol interference (ISI), and noise. The two communications systems investigated were a Hadamard encoded code division multiple access (CDMA) communications system with up to 32 synchronous users and a transform domain communications system (TDCS) with only one user. Both communications systems …

Reflection Coefficients Of P- And S-Polarized Light By A Quarter-Wave Layer: Explicit Expressions And Application To Beam Splitters, R. M.A. Azzam, F. F. Sudradjat

Electrical Engineering Faculty Publications

The complex-amplitude reflection coefficients of p- and s-polarized light by a transparent freestanding, embedded, or deposited quarter-wave layer (QWL) are derived as explicit functions of the angle of incidence and layer refractive index. This provides the basis for the design of 50%-50% beam splitters for incident s-polarized or unpolarized light that use a high-index (e.g., TiO₂ or Ge) QWL embedded in a glass cube in the visible and near infrared spectral range. These simple devices have good angular and spectral response and are insensitive to small film thickness errors to the first order.

Efficiency Of Linear-To-Circular Polarization Conversion For Light Reflection At The Principal Angle By A Dielectric-Conductor Interface, R. M.A. Azzam, A. Alsamman

Electrical Engineering Faculty Publications

The efficiency ηLC of linear-to-circular polarization conversion when light is reflected at a dielectric–conductor interface is determined as a function of the principal angle ϕ¯ and principal azimuth ψ¯ . Constant- ηLC contours are presented in the ϕ¯ ,ψ¯ plane for values of ηLC from 0.5 to 1.0 in steps of 0.05, and the corresponding contours in the complex plane of the relative dielectric function ϵ are also determined. As specific examples, efficiencies ⩾88% are obtained for light reflection by a Ag mirror in the visible and near-IR (400–1200nm) spectral range, and ≥40% for the reflection of extreme ultraviolet (EUV) …

Increasing Combat Aircraft Survivability Through Coherent Self-Protection Jammers, Soner Ozer

Theses and Dissertations

When the battlefields were within the visual range, the objective of deception tactics in warfare was to deceive the human senses. In the battlefield of electromagnetic spectrum, the objective of deception is to deceive the sensors of the enemy weapon systems. The survivability of the aircraft operating in hostile environment is of prime importance to the mission planner. If the aircraft can deny its location information to the tracking radar of the radar guided threat missile system, this, in return, may increase its survivability. The deception, a tactic which stems from the wisdom of ancient battles, incarnated in the form …

Anti-Tamper Method For Field Programmable Gate Arrays Through Dynamic Reconfiguration And Decoy Circuits, Samuel J. Stone

Theses and Dissertations

As Field Programmable Gate Arrays (FPGAs) become more widely used, security concerns have been raised regarding FPGA use for cryptographic, sensitive, or proprietary data. Storing or implementing proprietary code and designs on FPGAs could result in the compromise of sensitive information if the FPGA device was physically relinquished or remotely accessible to adversaries seeking to obtain the information. Although multiple defensive measures have been implemented (and overcome), the possibility exists to create a secure design through the implementation of polymorphic Dynamically Reconfigurable FPGA (DRFPGA) circuits. Using polymorphic DRFPGAs removes the static attributes from their design; thus, substantially increasing the difficulty …

Improvement Of Ecm Techniques Through Implementation Of A Genetic Algorithm, James D. Townsend

Theses and Dissertations

This research effective effort develops the necessary interfaces between the radar signal processing components and an optimization routine, such as genetic algorithms, to develop Electronic Countermeasure (ECM) waveforms under a Hardware-in-the-Loop (HILS) architecture. The various ECM waveforms are stored in an ECM library, where an operator selects the desired function to use against a particular system. This optimization works with modular components, compared to previous research that embedded a genetic algorithm into the Range Gate Pull-off (RGPO) waveform optimization loop, which can be interchanged based upon the operator's desired hardware/ software testing setup. The ECM library's first entries contain the …

Tailoring Metallodielectric Structures For Superresolution And Superguiding Applications In The Visible And Near-Ir Ranges, Domenico De Ceglia, Maria Antonietta Vincenti, M. G. Cappeddu, Marco Centini, Neset Akozbek, Antonella D'Orazio, Joseph W. Haus, Mark J. Bloemer, Michael Scalora

Electrical and Computer Engineering Faculty Publications

We discuss propagation effects in realistic, transparent, metallodielectric photonic band gap structures in the context of negative refraction and super-resolution in the visible and near infrared ranges. In the resonance tunneling regime, we find that for transverse-magnetic incident polarization, field localization effects contribute to a waveguiding phenomenon that makes it possible for the light to remain confined within a small fraction of a wavelength, without any transverse boundaries, due to the suppression of diffraction. This effect is related to negative refraction of the Poynting vector inside each metal layer, balanced by normal refraction inside the adjacent dielectric layer: The degree …

Digital Fingerprinting Of Field Programmable Gate Arrays, James W. Crouch

Theses and Dissertations

Commercial off-the-shelf (COTS) component usage is becoming more prevalent in military applications due to current Department of Defense (DoD) policies. The easy accessibility of COTS will give reverse engineers a higher probability of successfully tampering, coping, or reverse engineering circuits that contain critical capabilities. To prevent this and verify the trustworthiness of hardware, circuit identification tags or serials numbers can be used. However, these values can be easily obtained and forged. To protect critical DoD technologies from possible exploitation, there is an urgent need for a reliable method to confirm a circuit’s identity using a set of unique unforgettable metrics. …

Design And Optimization Of Broadband High Impedance Ground Planes (Higp) For Surface Mount Antennas, Murat Dogrul

Theses and Dissertations

Gain and bandwidth metrics of broad-band low-profile antennas severely deteriorate when they are placed conformally onto the conductive skins of air, sea, and ground platforms. This detrimental effect is primarily due to out-of-phase reflections from the conductive body interfering with the antenna’s self radiation. Furthermore, lateral waves launched by the antenna couple into the thin substrate placed between the antenna and the platform, giving rise to surface waves resulting in significant diffraction from the edges of the substrate. To remedy these two major mechanisms degrading antenna performance, high impedance ground planes (HIGP) were designed. HIGPs made of a 2-dimensional periodic …

Characterization And Implementation Of A Real-World Target Tracking Algorithm On Field Programmable Gate Arrays With Kalman Filter Test Case, Benjamin D. Hancey

Theses and Dissertations

A one dimensional Kalman Filter algorithm provided in Matlab is used as the basis for a Very High Speed Integrated Circuit Hardware Description Language (VHDL) model. The JAVA programming language is used to create the VHDL code that describes the Kalman filter in hardware which allows for maximum flexibility. A one-dimensional behavioral model of the Kalman Filter is described, as well as a one-dimensional and synthesizable register transfer level (RTL) model with optimizations for speed, area, and power. These optimizations are achieved by a focus on parallelization as well as careful Kalman filter sub-module algorithm selection. Newton-Raphson reciprocal is the …

Design And Analysis Of Scalable Scheduling Schemes For High-Speed Input-Queued Packet Switches, Chuan-Bi Lin

Dissertations

Single-stage input-queued (IQ) switches are attractive for implementation of high performance routers because they require no speedup in the used memory. It has been shown that IQ switches can provide 100% throughput under admissible traffic when using either maximum-weight matching schemes or iterative maximal-weight matching schemes with a significant speedup. These different approaches require either high computation complexity or high memory costs that can make them infeasible. Therefore, there is a need for low-complexity and fast matching schemes that provide high throughput under several admissible traffic patterns, without recurring to speedup nor multiple iterations. In this thesis. the concept of …

Architecture Design And Performance Analysis Of Practical Buffered-Crossbar Packet Switches, Ziqian Dong

Dissertations

Combined input crosspoint buffered (CICB) packet switches were introduced to relax inputoutput arbitration timing and provide high throughput under admissible traffic. However, the amount of memory required in the crossbar of an N x N switch is N²x k x L, where k is the crosspoint buffer size and needs to be of size RTT in cells, L is the packet size. RTT is the round-trip time which is defined by the distance between line cards and switch fabric. When the switch size is large or RTT is not negligible, the memory amount required makes the implementation …

Propagation And Scattering Of Beam Waves In Vegetation Using Scalar Transport Theory, Michael Yu-Chi Wu

Dissertations

Vegetation is a very complex propagation medium, and multiple scattering effects play a significant role in the propagation of microwave and millimeter (mm)-wave signals through foliage. At frequencies above 1 GHz,both the coherent and incoherent field components have to be taken into account and vegetation has to be modeled as a random medium of discrete scatterers having a wide variety of sizes and shapes. Multiscattering can be studied effectively by using transport theory. In prior studies, theories have been developed for microwave and mm-wave propagation in vegetation using transport theory for continuous wave and pulsed signals. In this study, the …

Polarization Properties Of Retroreflecting Right-Angle Prisms, R. M.A. Azzam, H. K. Khanfar

Electrical Engineering Faculty Publications

The cumulative retardance Δ_t introduced between the p and the s orthogonal linear polarizations after two successive total internal reflections (TIRs) inside a right-angle prism at complementary angles Φ and 90°−Φ is calculated as a function of Φ and prism refractive index n. Quarter-wave retardation (QWR) is obtained on retroreflection with minimum angular sensitivity when n=(√2+1)^1/2=1.55377 and Φ=45°. A QWR prism made of N-BAK4 Schott glass (n=1.55377 at λ=1303.5 nm) has good spectral response (<5° retardance error) over the 0.5-2 μm visible and near-IR spectral range. A ZnS-coated right-angle Si prism achieves QWR with an error of <±2.5° in the 9-11 μm (CO₂ laser) IR spectral range. This device functions as a linear-to-circular polarization transformer and can be tuned to exact QWR at any …

Phonon-Energy-Coupling-Enhancement Effect And Its Applications, Pang-Leen Ong

University of Kentucky Doctoral Dissertations

Silicon Oxide/Oxynitride (SiO₂/SiON) has been the mainstream material used for gate dielectric for MOS transistors for the past 30 years. The aggressive scaling of the feature size of MOS transistor has limited the ability of SiO₂/SiON to work effectively as the gate dielectric to modulate the conduction of current of MOS transistors due to excess leakage current dominated by direct quantum tunneling. Due to this constraint, alternative gate dielectric/high-k is being employed to reduce the leakage current in order to maintain the rate of scaling of MOS transistors. However, the cost involved in the implementation of …

A Multi-Objective No-Regret Decision Making Model With Bayesian Learning For Autonomous Unmanned Systems, Matthew Howard

Electronic Theses and Dissertations

The development of a multi-objective decision making and learning model for the use in unmanned systems is the focus of this project. Starting with traditional game theory and psychological learning theories developed in the past, a new model for machine learning is developed. This model incorporates a no-regret decision making model with a Bayesian learning process which has the ability to adapt to errors found in preconceived costs associated with each objective. This learning ability is what sets this model apart from many others. By creating a model based on previously developed human learning models, hundreds of years of experience …

Reducing Eddy Currents In High Magnetic Field Environments, Russell Case

Electronic Theses and Dissertations

When an electrical conducting volume is placed into the bore of an MRI undergoing an image scan, time varying magnetic gradients induce eddy currents in this conducting material. These eddy currents in turn produce a mechanical torque on this volume. It is the goal of this thesis to produce a computer simulation of eddy currents produced by placing conducting materials inside an MRI bore. The first part of the thesis establishes the physics and principles behind an MRI system along with several applications. Next, this thesis presents an analysis of eddy current effects produced on a conductor placed into an …

Comparison Of Theoretical Models Of Power Spectral Density To The Experimental Value For Spectrum Of Irradiance Fluctuations, Craig Hershberger

Electronic Theses and Dissertations

A propagation experiment was designed, assembled, and conducted on an extended range to verify theoretical temporal models for weak to strong fluctuation theory. Laser light intensity was propagated over terrain at the Kennedy Space Center (Florida), and detected using optical receivers at a distance of 13.3 Km from the optical source. The intensity data from the experiment was used to generate an experimental Power Spectral Density (PSD) function. The theoretical Mutual Coherence Function (MCF) and Wave Structure Function (WSF) as set forth by Andrews/Phillips , were evaluated to determine the effective relationship between the statistical moments of the random optical …

Bi-Directional Dcm Dc-To-Dc Converter For Hybrid Electric Vehicles, Michael Pepper

Electronic Theses and Dissertations

With the recent revival of the hybrid vehicle much advancement in power management has been made. The most popular hybrid vehicle, the hybrid electric vehicle, has many topologies developed to realize this hybrid vehicle. From these topologies, as sub set was created to define a particular group of vehicles where the converter discussed in this thesis has the most advantage. This sub set is defined by two electric sources of power coupled together at a common bus. This set up presents many unique operating conditions which can be handled seamlessly by the DC-to-DC converter when designed properly. The DC-to-DC converter …

A Time-Varying Radiometric Bias Correction For The Trmm Microwave Imager, Kaushik Gopalan

Electronic Theses and Dissertations

This dissertation provides a robust radiometric calibration for the TRMM Microwave Imager to correct systematic brightness temperature errors, which vary dynamically with orbit position (time) and day of the year. The presence of a time-varying bias in TMI is confirmed by inter-calibration with WindSat and SSMI. This time varying bias is manifested as a time of day dependent variation of the relative biases between TMI and both WindSat and SSMI. In this dissertation, we provide convincing evidence that this time-varying Tb bias in TMI is caused by variations in the physical temperature of the emissive TMI reflector antenna. This dissertation …

Design, Characterization And Compact Modeling Of Novel Silicon Controlled Rectifier (Scr)-Based Devices For Electrostatic Discha, Lifang Lou

Electronic Theses and Dissertations

Electrostatic Discharge (ESD), an event of a sudden transfer of electrons between two bodies at different potentials, happens commonly throughout nature. When such even occurs on integrated circuits (ICs), ICs will be damaged and failures result. As the evolution of semiconductor technologies, increasing usage of automated equipments and the emerging of more and more complex circuit applications, ICs are more sensitive to ESD strikes. Main ESD events occurring in semiconductor industry have been standardized as human body model (HBM), machine model (MM), charged device model (CDM) and international electrotechnical commission model (IEC) for control, monitor and test. In additional to …

Transient Response Improvement For Multi-Phase Voltage Regulators, Shangyang Xiao

Electronic Theses and Dissertations

Next generation microprocessor (Vcore) requirements for high current slew rates and fast transient response together with low output voltage have posed great challenges on voltage regulator (VR) design . Since the debut of Intel 80X86 series, CPUs have greatly improved in performance with a dramatic increase on power consumption. According to the latest Intel VR11 design guidelines , the operational current may ramp up to 140A with typical voltages in the 1.1V to 1.4V range, while the slew rate of the transient current can be as high as 1.9A/ns [1, 2]. Meanwhile, the transient-response requirements are becoming stringer and stringer. …

Design Of Polynomial-Based Filters For Continuously Variable Sample Rate Conversion With Applications In Synthetic Instrumentati, Matthew Hunter

Electronic Theses and Dissertations

In this work, the design and application of Polynomial-Based Filters (PBF) for continuously variable Sample Rate Conversion (SRC) is studied. The major contributions of this work are summarized as follows. First, an explicit formula for the Fourier Transform of both a symmetrical and nonsymmetrical PBF impulse response with variable basis function coefficients is derived. In the literature only one explicit formula is given, and that for a symmetrical even length filter with fixed basis function coefficients. The frequency domain optimization of PBFs via linear programming has been proposed in the literature, however, the algorithm was not detailed nor were explicit …

Dual Bypass Gas Metal Arc Welding Process And Control, Xiaopei Liu

University of Kentucky Doctoral Dissertations

GMAW (Gas Metal Arc Welding) is one of the most important arc welding processes being adopted in modern manufacturing industry due to its advantages in productivity, energy efficiency and automation. By monitoring and improving some of the important properties of GMAW such as production rate, metal transfer and base metal heat input, researchers could bring the process efficiency and stability to a new level. In recent years, some innovative modifications of GMAW such as Twins, Tandem and laser-MIG hybrid welding have been adopted into many industrial applications for better productivity.

In this dissertation, a novel GMAW called DB-GMAW (Dual Bypass …

Antennas For Portable Communications In The Uwb And Gps Spectra., Giuseppe Ruvio

Doctoral

The thesis describes a study of antennas for solutions in emerging systems. An account of the fundamental principles of these antennas is given together with an outline of the basic electromagnetic theory on which the designs are based. While the main focus is on antennas for Ultra Wideband (UWB) systems, some additional work was carried out on enhancing performance of circularly polarised antennas for satellite navigation systems. The study focussed on the design of highly efficient broadband antennas with particular requirements for size compactness, gain stability, phase-linearity, and the use of low-cost materials. These requirements are particularly important for UWB …

Dual Band Dual Polarized Antenna With High Efficiency For Base Transceiver Stations, F. H. Kashani, M. Shahpari, Hossein Ameri Mahabadi

Hossein Ameri Mahabadi

In this paper new array element for use in dual band dual polarized antenna will be introduced that has high efficiency (more than 95%) and has high isolation in both 900MHz and 1800MHz bands. Also radiation pattern of this antenna is according to IEC recommendation.

A Novel Bandpass Waveguide Filter Structure On Siw Technology, Z. Sotoodeh, B. Biglarbegian, F. Hojat Kashani, Hossein Ameri Mahabadi

Hossein Ameri Mahabadi

Taking the advantage of common waveguide filters and SIW technology, a new filter structure is proposed.This structure can be implemented for various microwave frequencies by choosing appropriate low loss substrates.An example of suggested structure in Ku band is presented in this paper.The filter is designed and simulated on a low loss RT/Duroid 5880 laminate.The resulted filter has a Quality factor around 150.The main advantage of the structure is low size and cost, simplicity in fabrication, and the ability of integration with other elements of the circuit

Boost-Half Bridge Single Power Stage Pwm Dc-Dc Converter For Pem-Fuel Cell Stack, Khairy F. A. Sayed Dr

Khairy F. A. Sayed Dr

This paper presents the design of 1 kW prototype high frequency link boost half bridge inverter-fed DC-DC power converter with bridge voltage-doublers suitable for small scale PEM fuel cell system and its associated control scheme. The operation principle of this converter is described using fuel cell modeling and some operating waveforms and the switching mode equivalent circuits based on simulation results and a detailed circuit operation analysis and soft-switching conditions.

Etude D'Une Centrale Hybride Photovoltaïque - Éolien - Diesel, Djamila Rekioua Pr

REKIOUA Djamila Dr

The electrical energy using renewable hybrids are known, medium-term interest thanks to their flexibility vis-à-vis the primary energy sources. The objective of this work is the study of a hybrid central power, which combines two renewable energy sources (wind, solar) with storage and an emergency generator. The management of different energy sources is ensured by a manager who controls the opening and closing switches, depending on weather conditions (illumination, wind speed).

Zinc Telluride Deposition Using Close Space Sublimation, Luis Carlos Romo

Open Access Theses & Dissertations

This thesis presents the optimization process of the close space sublimation (CSS) technique to deposit zinc telluride (ZnTe) on thin-film cadmium telluride (CdTe) solar cells. Previous research has demonstrated that creating a heavily doped ZnTe intermediate layer between the absorber-CdTe and the back contacts produces low-resistive CdTe contacts that overcome the Schottky barrier created at the interface of a metal and a semiconductor [11]. ZnTe interlayer forms a tunnel barrier at the contact interface so the positive charges created at the p-CdTe/n-cadmium sulfide (CdS) junction can be easily collected at the back contact maximizing the current collection process. However, ZnTe …