Electrical and Electronics Commons^™

Growth And Characterization Of Anisotropic Gase Semiconductor For Radiation Detection And Thz Applications, Haseeb Nazir

Theses and Dissertations

Anisotropic wide-bandgap gallium selenide (GaSe) crystals were grown using high purity (7N) Ga and zone refined (ZR) Se precursor materials. The crystal growth was performed using a modified vertical Bridgman method (VBM) with a slow crystallization from the melt and with a pre-determined temperature profile. The structure, surface morphology, and the composition of the grown crystals were characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive analysis by x-rays (EDAX), respectively. Optical absorption and transmission properties were characterized and optical bandgap was determined. Electrical resistivity has been determined using current-voltage (I V) measurements using van der Pauw …

Cable Health Monitoring System Built Into Power Converter Using Time Domain Reflectometry, Hossein Baninajar

Theses and Dissertations

Aging cables are a critical reliability concern for many electrical systems. Cables run over long distances, are often exposed to harsh environments and are intended to work for several decades. Cable faults can be a serious problem because cables are usually hard to repair or replace. Condition based maintenance is a popular approach that provides high reliability and low maintenance cost at the same time. This is a non-destructive method that collects information about the health condition of the cable under test without causing any potential damage.

Nowadays, in several applications power cables are connected to power converters and it …

Software Modelling For Real World Faults On Ac Transmission Protective Systems Analysis And Effects, Iandale Tualla

Theses and Dissertations

The Electric Power Utilities serves many diverse customers from regular households to major processing plants that develop parts for gasoline vehicles. Those varying customer usages has adverse effects on the Electric Grid in many ways, that requires continuing analysis by the engineers and technical skills specialists who keep the Electric Grid stable. Several papers have been written about harmonics and Non- Sinusoidal waveforms and its effect on the Electric Grid. This thesis will exam a realworld fault event on a transmission line, its effects on the AC Transmission Protection Systems (TPS) that provides electrical energy to a nonlinear load, specifically …

Integrated Circuit Wear-Out Prediction And Recycling Detection Using Radio-Frequency Distinct Native Attribute Features, Randall D. Deppensmith

Theses and Dissertations

Radio Frequency Distinct Native Attribute (RF-DNA) has shown promise for detecting differences in Integrated Circuits(IC) using features extracted from a devices Unintentional Radio Emissions (URE). This ability of RF-DNA relies upon process variation imparted to a semiconductor device during manufacturing. However, internal components in modern ICs electronically age and wear out over their operational lifetime. RF-DNA techniques are adopted from prior work and applied to MSP430 URE to address the following research goals: 1) Does device wear-out impact RF-DNA device discriminability?, 2) Can device age be continuously estimated by monitoring changes in RF-DNA features?, and 3) Can device age state …

Electromagnetic Characterization Of Materials Using A Dual Chambered High Temperature Waveguide, Jeffrey S. Sovern

Theses and Dissertations

Measurement of the electromagnetic properties of materials at high temperatures is important for industrial, scientific, medical, and aerospace applications [1]. Current high-temperature electromagnetic material characterization is a time consuming process that typically requires three days to collect data from one material specimen. For example, the standard high-temperature process involving rectangular waveguides [2] requires measurements of the sample (1), the empty waveguide (2), and a metal short standard (3) completed in separate heated runs over three days to perform the Nicolson-Ross-Weir inversion algorithm for computing permittivity and permeability. The technique developed here will reduce the high-temperature measurement process from three days …

Simulation Of Gan Based Mis Varactor, Bojidha Babu

Theses and Dissertations

This work deals with novel microwave switches based on III-Nitride varactors. RF switches, power limiters and other control devices are important components of various RF systems, such as wireless modules of laptops, tablets, cell phones etc., satellites communication systems, radars, multi-band wireless and aerospace communications, phased array antennas and so worth. Traditional RF switches are fabricated using pin diodes or MEMS, Si MOSFETs or GaAs HEMTs. These devices have a number of fundamental limitations. Si or GaAs based devices suffer from a low breakdown voltage and cannot handle high RF power. Pin-diodes require large forward currents and do not allow …

Applications Of Impedance Identification To Electric Ship System Control And Power Hardware-In-The-Loop Simulation, Jonathan Siegers

Theses and Dissertations

Recent advances in semiconductor technology, controls, and switching converter topologies have resulted in the increasing application of power electronics in power distribution systems. Power electronic enabled distribution systems have inspired a renewed interest in DC distribution architectures as an appealing alternative to traditional AC methods due to the significant performance and efficiency gains they offer. However, the notional power electronic based DC distribution system is a complex and extensively interconnected system consisting of multiple power converters. As a result, a number of system-level challenges related to stability arise due to interaction among multiple power converters. In addition, the power distribution …

Beyond Conventional C-Plane Gan-Based Light Emitting Diodes: A Systematic Exploration Of Leds On Semi-Polar Orientations, Morteza Monavarian

Theses and Dissertations

Despite enormous efforts and investments, the efficiency of InGaN-based green and yellow-green light emitters remains relatively low, and that limits progress in developing full color display, laser diodes, and bright light sources for general lighting. The low efficiency of light emitting devices in the green-to-yellow spectral range, also known as the “Green Gap”, is considered a global concern in the LED industry. The polar c-plane orientation of GaN, which is the mainstay in the LED industry, suffers from polarization-induced separation of electrons and hole wavefunctions (also known as the “quantum confined Stark effect”) and low indium incorporation efficiency that …

Hybrid Straintronics-Spintronics: Energy-Efficient Non-Volatile Devices For Boolean And Non-Boolean Computation, Ayan K. Biswas

Theses and Dissertations

Research in future generation computing is focused on reducing energy dissipation while maintaining the switching speed in a binary operation to continue the current trend of increasing transistor-density according to Moore’s law. Unlike charge-based CMOS technology, spin-based nanomagnetic technology, based on switching bistable magnetization of single domain shape-anisotropic nanomagnets, has the potential to achieve ultralow energy dissipation due to the fact that no charge motion is directly involved in switching. However, switching of magnetization has not been any less dissipative than switching transistors because most magnet switching schemes involve generating a current to produce a magnetic field, or spin transfer …

Pattern Recognition In Class Imbalanced Datasets, Nahian A. Siddique

Theses and Dissertations

Class imbalanced datasets constitute a significant portion of the machine learning problems of interest, where recog­nizing the ‘rare class’ is the primary objective for most applications. Traditional linear machine learning algorithms are often not effective in recognizing the rare class. In this research work, a specifically optimized feed-forward artificial neural network (ANN) is proposed and developed to train from moderate to highly imbalanced datasets.

The proposed methodology deals with the difficulty in classification task in multiple stages—by optimizing the training dataset, modifying kernel function to generate the gram matrix and optimizing the NN structure. First, the training dataset is extracted …

Estimating Local Average Power In A Line-Of-Sight Indoor Channel: Spatial Sampling And Processing, Israt Jahan Disha

Theses and Dissertations

Modeling of indoor radio channels has been a dynamic area of research in recent years because of the increasing demand for indoor wireless communications. In order to efficiently deploy such indoor systems, a good knowledge of the indoor wireless channel’s characteristics are required. One important characteristic is an accurate propagation path loss model. For developing such models various measurements have been carried out. In modeling propagation path loss in complex indoor environments, accurate and fast algorithms for estimating the local mean signal level are essential; these are also of use for power control and handoff decisions. These local mean power …

High Gain Pattern Reconfigurable Antenna Arrays For Portable And Body-Centric Wireless Applications, Nowrin Hasan Chamok

Theses and Dissertations

Wireless devices such as smartphones, tablet computers, smartwatches etc. have become ubiquitous. With that, the demand for high speed data has increased tremendously. Designing antennas for such applications is challenging because of limited availability of space, shadowing or blockage from the human body, and signal loss from multipath fading. Conventional broad, fixed beam low gain antennas result in poor reception, faster battery drainage, and low data rate. Compressed footprint high gain pattern reconfigurable antenna arrays can solve these problems which is the focus of this dissertation. Two innovative high gain pattern reconfiguration techniques, the switched beam parasitic array and the …

Engineering Model Of Iii-Nitride Power Heterostructure Field Effect Transistor On Silicon Substrate, Mohammad Mirwazul Islam

Theses and Dissertations

In modern society, the demand for power consumption is increasing rapidly and the need of energy savings is now an issue of global importance. Highly efficient power converters and power conditioning systems operating with wide range of traditional as well as novel renewable and clean energy sources, are playing crucial role in energy saving. Si converters have already reached their limitation in terms of switching frequency and breakdown voltage/on-resistance ratio. Research is going on all around the world and it is now well accepted that significant improvement in power conversion efficiency and speed can only be achieved using beyond Si …

Distributed Optimization And Control Of Islanded Microgrids, Md Rishad Hossain

Theses and Dissertations

A microgrid may have numerous multi-functional power electronic converters connecting sources, loads, and storage to the system. Systems where converters are the interface between many of the main sources of energy and load centers have the ability to direct the flow of energy if the control of the converters is coordinated. The influence of energy flow in a microgrid by coordinated action of converters is referred to here as ‘energy routing’. Energy routing allows for reduction of systems losses by optimizing source operating points and reducing transmission and distribution path losses. Energy ramp rates at various points in the system …

System Level Analysis And Design For Wireless Inter-Chip Interconnection Communication Systems By Applying Advanced Wireless Communication Technologies, Xin Zheng

Theses and Dissertations

As the dramatic development of high speed integrated circuits has progressed, the 60 GHz silicon technology has been introduced to enable much faster computer systems and their corresponding applications. However, when signals are propagating at 60 GHz or higher frequencies on a PCB (Printed Circuit Board), the crosstalk among signal buses and devices, trace losses, and introduced parasitic capacitance and inductance between high density traces, become significant and may be severe enough such that the inter-chip communications will not be able to meet computer system signal specifications. High speed circuit signal integrity researchers in both electronic industries and academia have …

Miniaturized Rf Components With A Novel Tunable Engineered Substrate For Wireless Communication Systems, Yujia Peng

Theses and Dissertations

There is an increasing demand for reliable sensor system capable of remote sensing and measuring interesting data. Although large communication range can be achieved, active wireless communication systems are still suboptimal in longtime applications due to their harmful battery supply. Inductively coupled passive devices, with the advantages in safe long-term implanting, structural simplicity, small fabrication footprint and low-cost production, are preferred in chronic monitoring, but little work has been done to optimize the performance of these systems, especially under some design constraints.

The model and optimization of an inductively coupled wireless pressure sensor system is presented in this dissertation. With …

A Comparison Of Fpga Implementation Of Latency-Based Solvers For Power Electronic System Real-Time Simulation, Matthew Aaron Milton

Theses and Dissertations

In the design of power systems, real-time simulation is a powerful tool to evaluate and validate designs before dedicating resources to develop such systems. Through use of real-time simulation, one can study the behavior of a power system in interaction with real, physical elements, all while avoiding the cost and risk in constructing and testing such systems before a design is finalized. In recent decades, effort has been made in the industry and academia to apply real-time simulation to that of switching power converters through use of high-speed digital signal processors (DSPs) and field programmable gate array (FPGA) devices. With …

Wireless Channel Modeling For Networks On Chips, William Rayess

Theses and Dissertations

The advent of integrated circuit (chip) multiprocessors (CMPs) combined with the continuous reduction in device physical size (technology scaling) to the sub-nanometer regime will result in an exponential increase in the number of processing cores that can be integrated within a single chip. Today’s CMPs already support tens to low hundreds of cores and both industry and academic roadmaps project that future chips will have thousands of cores. Therefore, while there are open questions on how to harness the computing power offered by CMPs, the design of power-efficient and compact on-chip interconnection networks that connects cores, caches and memory controllers …

Investigation Of Wide Bandgap Semiconductor Devices For Radiation Detection Applications, Rahmi Orhon Pak

Theses and Dissertations

Radioactive materials, as they decay, generate different high-frequency electromagnetic radiation such as alpha particles, beta particles, x-rays, gamma-rays, and neutrons. Nuclear detectors could stop these high-energy ionizing radiations, collect and transport the charges generated to an external circuit, and produce an electrical signal which is amplified by readout electronics to measure the energy of nuclear interaction. Thus, nuclear detectors are important tools for accounting of radioactive materials and have widespread applications in nuclear power plants, nuclear waste management, in national security, in medical imaging such as x-ray mammography, digital chest radiography, CT scan, and in high energy astronomy for NASA …

Investigation Of Electromagnetic Signatures Of A Fpga Using An Aprel Em-Isight System, Karynn A. Sutherlin

Theses and Dissertations

Large military platforms have encountered major performance and reliability issues due to an increased number of incidents with counterfeit electronic parts. This has drawn the attention of Department of Defense (DOD) leadership making detection and avoidance of counterfeit electronic parts a top issue for national defense. More defined regulations and processes for identifying, reporting, and disposing of counterfeit electronic parts are being revised to raise awareness for this aggregating issue, as well as enhance the detection of these parts. Multiple technologies are currently employed throughout the supply chain to detect counterfeit electronic parts. These methods are often costly, time-consuming, and …

Novel Applications Of A Thermally Tunable Bistable Buckling Silicon-On-Insulator (Soi) Microfabricated Membrane, Robert A. Lake

Theses and Dissertations

Buckled membranes are commonly used microelectromechanical systems (MEMS) structures. Recent work has demonstrated that the deflection and stiffness of these membranes can be tuned through localized joule heating. These devices were implemented into the design and fabrication of two novel device applications, a tunable pressure sensor and a steerable micromirror. A differential pressure across the membrane causes de reflection, up or down, which can be measured and related to a specific pressure. By tuning the stiffness of the membrane, its pressure response is varied providing a wider range of application for the pressure sensor. A 2.0mm by 2.0mm square membrane …

Multi-Mode Analysis Of Dual Ridged Waveguide Systems For Material Characterization, Jason G. Crosby

Theses and Dissertations

In this dissertation, two nondestructive dual ridged waveguide (DRWG) material characterization systems are investigated. The single and clamped DRWG probe geometries were analyzed in previous work; however, that research only incorporated the dominant DRWG mode. Here, that restriction is removed and the existence of evanescent higher- order modes is considered. Theoretical analysis of the single and clamped DRWG probes is presented and discussed. The approach taken here is similar to that presented in previous research: Love's equivalence theorem is used to remove the DRWG apertures which are replaced with equivalent magnetic currents radiating in the presence of the background parallel-plate …

Urban Environment Navigation With Real-Time Data Utilizing Computer Vision, Inertial, And Gps Sensors, Johnathan L. Rohde

Theses and Dissertations

The purpose of this research was to obtain a navigation solution that used real data, in a degraded or denied global positioning system (GPS) environment, from low cost commercial o the shelf sensors. The sensors that were integrated together were a commercial inertial measurement unit (IMU), monocular camera computer vision algorithm, and GPS. Furthermore, the monocular camera computer vision algorithm had to be robust enough to handle any camera orientation that was presented to it. This research develops a visual odometry 2-D zero velocity measurement that is derived by both the features points that are extracted from a monocular camera …

Initial Implementation And Testing Of A Tightly-Coupled Imu/Pseudolite System, James E. C. Kawecki

Theses and Dissertations

Currently, the 746th Test Squadrons (746th TS) Central Inertial and GPS Test Facility (CIGTF) operates one of the most accurate truth reference systems, called the CIGTF Reference System (CRS). CIGTF will be replacing the CRS with a new references system called UHARS (Ultra High Accuracy Reference System). UHARS will differ from CRS by adding the ability to use a non-GPS pseudolite system, as a new measurement source. This research effort describes the design of the extended Kalman filter which is developed in AFIT's SPIDER filter framework which implements a tightly-coupled pseudolite/INS filter.

Gate-Level Commercial Microelectronics Verification With Standard Cell Recognition, Leleia A. Hsia

Theses and Dissertations

Within the past two decades, the problem of counterfeit hardware has gained significant attention within the Department of Defense (DoD). Counterfeit electronics compromise national security systems as they may fail to meet durability requirements and/or contain malicious circuits [6, 16, 17]. This necessitates the development of methods to detect counterfeit electronics and prevent the counterfeit electronics from entering DoD systems. The DARPA TRUST program was established to address the need to verify integrated circuit (IC) electronics. This research describes the development of standard cell recognition (SCR) software intended to resolve conflicts in prior TRUST related applications of commercial software to …

Unique Two-Way Field Probe Concept Utilizing A Geodesic Sphere And Quad-Rotor, Travis A. Albee

Theses and Dissertations

Surveying the test volume of a radar range normally involves utilizing an antenna field probe to measure the electromagnetic field in that volume of space. Today, field probes vary in size and shape and can be difficult and time consuming to setup. They also have a limited range of motion due to their support structure and translational mechanism, which also has scattering mechanisms that can perturb the field they are measuring. Field probes are useful, but because of these shortcomings they can provide limited characterization of the field illuminating the measurement area. Leveraging quad-rotor technology, coupled with a two-way probe …

Materials Characterization And Microelectronic Implementation Of Metal-Insulator Transition Materials And Phase Change Materials, Alexander H. Gwin

Theses and Dissertations

Vanadium dioxide (VO²) is a metal-insulator transition (MIT) material, and germanium telluride (GeTe) is a phase change material (PCM), both of which undergo several orders of magnitude increase in electrical conductivity from room temperature to their transition temperatures. They are candidates for many important technologies, including ultra-fast electronic memory, optical switches and filters, and active layers in terahertz metamaterials, among others. The physical mechanisms causing the phase transitions in these materials are explained and investigated experimentally. These materials were incorporated into six types of microelectronic devices, which were designed, fabricated, and tested at the Air Force Institute of …

Characterizing Multiple Wireless Sensor Networks For Large-Scale Radio Tomography, Tan Van

Theses and Dissertations

Radio Tomographic Imaging (RTI) is an emerging Device-Free Passive Localization (DFPL) technology that uses a collection of cheap wireless transceivers to form a Wireless Sensor Network (WSN). Unlike device-based active localization, DFPL does not require a target of interest to be wearing any kind of device. The basic concept of RTI utilizes the changes in Received Signal Strength (RSS) between the links of each transceiver to create an attenuation image of the area. This image can then be used for target detection, tracking, and localization. Each transceiver in the WSN must transmit sequentially to prevent collisions. This is not a …

Verification And Validation Of Monte Carlo N-Particle 6 For Computing Gamma Protection Factors, William J. Erwin

Theses and Dissertations

This thesis examined the suitability of a particle simulator known as "Monte Carlo n-Particle 6" (MCNP6) to determine how well U.S. Army vehicles shield their occupants from gamma radiation. MCNP6 compared favorably to three alternate modeling approaches and another particle simulator. In a validation experiment, MCNP6 was found to produce a gamma protection factor within 5% of the experimental result with 95% confidence. Further evaluations validated MCNP6's ability to produce reliable results with simplified or approximated inputs, model different sources, and position those sources in different shielding geometries. MCNP6 is suitable for evaluating gamma protection of Army vehicles and further …

Design Of An All-In-One Embedded Flight Control System, Joel D. Elmore

Theses and Dissertations

This thesis describes an all-in-one flight control system (FCS) that was designed for unmanned aerial vehicles (UAVs). The project focuses on the embedded hardware aspect of a stand-alone system with low-cost and reliability in mind.