Electromagnetics and Photonics Commons^™

Gui For Mri-Compatible Neural Stimulator And Recorder, Soo Han Soon, Nishant Babaria, Ranajay Mandal, Zhongming Liu

The Summer Undergraduate Research Fellowship (SURF) Symposium

Functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) are useful tools to analyze brain activities given active stimulation. However, the electromagnetic noise from the MRI distorts the brain signal recording and damages the subject with excessive heat generated on the electrodes attached to the skin. MRI-compatible recording and stimulation systems previously developed at LIBI lab were capable of removing the electromagnetic noise during the imaging process. Previously, the hardware systems had required the integrative software that could control both circuits simultaneously and enable users to easily change recording and stimulation parameters. Graphical user interface (GUI) programmed with computer language informed …

Two Senior Projects: 2.4 Ghz, 40% Efficiency Radio Frequency Amplifier, Ieee Design Contest, & Design And Implementation Of A Software Costas Loop For Audio Frequencies, Robert J. Tong

Electrical Engineering

How to Read this Document:

This document combines two senior project reports. The first senior project documents designing a class AB RF amplifier. The second, discusses the design and implementation of a software Costas loop for audio frequencies. The first report begins on the next page, while the Costas loop report starts on page 24. The two reports are orthogonal from one another. It is not a prerequisite to read the RF amplifier report before reading the Costas loop report. This document is merely two reports combined into one document. The second report, about the Costas loop, was written as …

On-Chip Training Of Memristor Crossbar Based Multi-Layer Neural Networks, Raqibul Hasan, Tarek M. Taha, Christopher Yakopcic

Electrical and Computer Engineering Faculty Publications

Memristor crossbar arrays carry out multiply-add operations in parallel in the analog domain, and so can enable neuromorphic systems with high throughput at low energy and area consumption. On-chip training of these systems have the significant advantage of being able to get around device variability and faults. This paper presents on-chip training circuits for multi-layer neural networks implemented using a single crossbar per layer and two memristors per synapse. Using two memristors per synapse provides double the synaptic weight precision when compared to a design that uses only one memristor per synapse. Proposed on-chip training system utilizes the back propagation …

Time-Modulated Array Testbed Prototype For Multibeam Spectrometry, Addison J. Ford

Doctoral Dissertations and Master's Theses

The radio spectrum is becoming increasingly crowded. Researchers are putting efforts into finding ways to increase spectrum utilization. The National Science Foundation (NSF) is funding research to study various methods to improve utilization of the spectrum and reduce the influence of interference. In the Radar & Microwaves Laboratory at Embry-Riddle, research is being conducted for the applications of passive radar and radio astronomy. As interference is a major threat to both of these applications, interference mitigation is a requirement. More commonly, antenna arrays are used for research in both applications as they can improve performance and reduce cost.

The focus …

Si-Based Germanium Tin Semiconductor Lasers For Optoelectronic Applications, Sattar H. Sweilim Al-Kabi

Graduate Theses and Dissertations

Silicon-based materials and optoelectronic devices are of great interest as they could be monolithically integrated in the current Si complementary metal-oxide-semiconductor (CMOS) processes. The integration of optoelectronic components on the CMOS platform has long been limited due to the unavailability of Si-based laser sources. A Si-based monolithic laser is highly desirable for full integration of Si photonics chip. In this work, Si-based germanium-tin (GeSn) lasers have been demonstrated as direct bandgap group-IV laser sources. This opens a completely new avenue from the traditional III-V integration approach. In this work, the material and optical properties of GeSn alloys were comprehensively studied. …

Optimization Of Miniaturized Resonant Microwave Cavities For Use In Q-Thrusters, Joshua Steven Pennington

Graduate Theses and Dissertations

A gedankenexperiment was considered to compare a hypothetical thruster that used no reaction mass to propulsion methods currently in use. A brief discussion of previous research work done on closed resonant cavity thrust devices was conducted. Using the previous work as a template, a simulation plan was devised. Computational models of resonant microwave cavities were constructed and investigated using COMSOL software. These COMSOL simulations were verified against known analytical solutions using Matlab software as a computational tool. Multiphysics simulations were created to study the microwave heating environment of the resonant cavities. From the COMSOL study outputs, the electromagnetic field magnitude, …

Microwave Interferometry Diagnostic Applications For Measurements Of Explosives, Loren A. Kline

Master's Theses

Microwave interferometry (MI) is a Doppler based diagnostic tool used to measure the detonation velocity of explosives, which has applications to explosive safety. The geometry used in existing MI experiments is cylindrical explosives pellets layered in a cylindrical case. It is of interest to Lawrence Livermore National Labs to measure additional geometries that may be overmoded, meaning that the geometries propagate higher-order transverse electromagnetic waves. The goal of my project is to measure and analyze the input reflection from a novel structure and to find a good frequency to use in an experiment using this structure. Two methods of determining …

Laser-Assisted Metal Organic Chemical Vapor Deposition Of Gallium Nitride, Hossein Rabiee Golgir

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Due to its unique properties, gallium nitride is of great interest in industry applications including optoelectronics (LEDs, diode laser, detector), high power electronics, and RF and wirelss communication devices. The inherent shortcomings of current conventional deposition methods and the ever-increasing demand for gallium nitride urge extended efforts for further enhancement of gallium nitride deposition. The processes of conventional methods for gallium nitride deposition, which rely on thermal heating, are inefficient energy coupling routes to drive gas reactions. A high deposition temperature (1000-1100 °C) is generally required to overcome the energy barriers to precursor adsorption and surface adatom migration. However, there …

Agenda: Second International Workshop On Thin Films For Electronics, Electro-Optics, Energy And Sensors (Tfe3s), University Of Dayton Research Institute

Electro-Optics and Photonics Faculty Publications

University of Dayton’s Center of Excellence for Thin Film Research and Surface Engineering (CETRASE) is delighted to organize its second international workshop at the University of Dayton’s Research Institute (UDRI) campus in Dayton, Ohio, USA. The purpose of the new workshop is to exchange technical knowledge and boost technical and educational collaboration activities within the thin film research community through our CETRASE and the UDRI.

Measuring The Reflection Matrix Of A Rough Surface, Kenneth W. Burgi, Michael A. Marciniak, Mark E. Oxley, Stephen E. Nauyoks

Faculty Publications

Phase modulation methods for imaging around corners with reflectively scattered light required illumination of the occluded scene with a light source either in the scene or with direct line of sight to the scene. The RM (reflection matrix) allows control and refocusing of light after reflection, which could provide a means of illuminating an occluded scene without access or line of sight. Two optical arrangements, one focal-plane, the other an imaging system, were used to measure the RM of five different rough-surface reflectors. Intensity enhancement values of up to 24 were achieved. Surface roughness, correlation length, and slope were examined …

Implementation Of Range Autofocus For Sar Radar Imaging, Nicholas J. Testin, Philip Davis

KSU Journey Honors College Capstones and Theses

The range calculation for an FMCW radar depends on accurate linear modulation. In some circumstances, linear modulation may not be available and must be corrected for. This paper describes an autofocus technique used to correct for phase error due to non-linearities in the components of a FMCW radar. Also described here is the algorithm used in calculating the phase error and application of the phase correction with triangle modulation. Known errors were calculated at certain distances and applied to correcting the phase of data taken at similar distances. The results given were generated using a SAR working outside linear ranges.

Comparing Multiple Turbulence Restoration Algorithms Performance On Noisy Anisoplanatic Imagery, Michael Armand Rucci, Russell C. Hardie, Alexander J. Dapore

Electrical and Computer Engineering Faculty Publications

In this paper, we compare the performance of multiple turbulence mitigation algorithms to restore imagery degraded by atmospheric turbulence and camera noise. In order to quantify and compare algorithm performance, imaging scenes were simulated by applying noise and varying levels of turbulence. For the simulation, a Monte-Carlo wave optics approach is used to simulate the spatially and temporally varying turbulence in an image sequence. A Poisson-Gaussian noise mixture model is then used to add noise to the observed turbulence image set. These degraded image sets are processed with three separate restoration algorithms: Lucky Look imaging, bispectral speckle imaging, and a …

Development Of Intermediate Band Solar Cell Through Ingan Quantum Well Structures, Kelly Mckenzie

Electrical Engineering Undergraduate Honors Theses

In the search for high-efficiency solar cells, In_xGa_1-xN has come under scrutiny as a unique material with high potential. This is due to characteristics including an easily tunable bandgap, large range of potential bandgap values, and high heat resistance. However, one factor limiting its adaptation is the high density of crystal defects. In this thesis, the qualities of InGaN are discussed and the intermediate band solar cell structure is introduced. Additionally, the growth and characterization of two sets of InGaN-based solar cell devices are reported and evaluated.

On The Simulation And Mitigation Of Anisoplanatic Optical Turbulence For Long Range Imaging, Russell C. Hardie, Daniel A. Lemaster

Electrical and Computer Engineering Faculty Publications

We describe a numerical wave propagation method for simulating long range imaging of an extended scene under anisoplanatic conditions. Our approach computes an array of point spread functions (PSFs) for a 2D grid on the object plane. The PSFs are then used in a spatially varying weighted sum operation, with an ideal image, to produce a simulated image with realistic optical turbulence degradation. To validate the simulation we compare simulated outputs with the theoretical anisoplanatic tilt correlation and differential tilt variance. This is in addition to comparing the long- and short-exposure PSFs, and isoplanatic angle. Our validation analysis shows an …

Novel Methods For The Time-Dependent Maxwell’S Equations And Their Applications, Sidney Shields

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation investigates three different mathematical models based on the time domain Maxwell's equations using three different numerical methods: a Yee scheme using a non-uniform grid, a nodal discontinuous Galerkin (nDG) method, and a newly developed discontinuous Galerkin method named the weak Galerkin (WG) method. The non-uniform Yee scheme is first applied to an electromagnetic metamaterial model. Stability and superconvergence error results are proved for the method, which are then confirmed through numerical results. Additionally, a numerical simulation of backwards wave propagation through a negative-index metamaterial is given using the presented method. Next, the nDG method is used to simulate …

Investigation Of Fes2 Nanoparticles For Use In Optoelectronic And Thermoelectric Applications, Rick Tefal Eyi Nkoghe

Graduate Theses and Dissertations

Iron pyrite (FeS2) is the most abundant sulfide material on earth. This material has been widely investigated by researchers because of its optical properties. However, it has been difficult to produce High efficiency FeS2 based solar cells. This is due to many different impurities that arise when making the materials. The ability to synthesize pure pyrite FeS2 material is therefore critical for applications.

Pure Iron pyrite nanocrystals were synthesized using hot injection by mixing sulfur with an iron precursor in the presence of an amine. To improve the stability, shorter ligands replaced the native amines ligands. The stability of the …

Smart Feedback Control For Fiber-Optics Acoustic Emission Sensor System, Xiangyu Luo

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Optical fiber sensors for ultrasonic detection have become a subject of much research in recent years. In this thesis, a fiber-optic acoustic emission (AE) sensor system that is capable of performing AE detection, even when the sensor is experiencing large quasi-static strains, is first described. The system consists of a smart selection of a wavelength notch to which a distributed feedback (DFB) laser is locked for high sensitivity AE signal demodulation. A smart feedback control unit for the DFB laser, which is the focus of this thesis, is designed and investigated. The smart control ensures that the AE signal is …

Rural Broadband Mobile Communications: Spectrum Occupancy And Propagation Modeling In Western Montana, Erin Wiles

Graduate Theses & Non-Theses

Fixed and mobile spectrum monitoring stations were implemented to study the spectrum range from 174 to 1000 MHz in rural and remote locations within the mountains of western Montana, USA. The measurements show that the majority of this spectrum range is underused and suitable for spectrum sharing. This work identifies available channels of 5-MHz bandwidth to test a remote mobile broadband network. Both TV broadcast stations and a cellular base station were modelled to test signal propagation and interference scenarios.

Engineered Nanocomposite Materials For Microwave/Millimeter-Wave Applications Of Fused Deposition Modeling, Juan De Dios Castro

USF Tampa Graduate Theses and Dissertations

A variety of high-permittivity (high-k) and low-loss ceramic-thermoplastic composite materials as fused deposition modeling (FDM) feedstock, based on cyclo-olefin polymer (COP) embedded with sintered ceramic fillers, have been developed and investigated for direct digital manufacturing (DDM) of microwave components. The composites presented in this dissertation use a high-temperature sintering process up to 1500°C to further enhance the dielectric properties of the ceramic fillers. The electromagnetic (EM) properties of these newly developed FDM composites were characterized up to the Ku-band by using the cavity perturbation technique. Several models for prediction of the effective relative dielectric permittivity of composites based …

Block Matching And Wiener Filtering Approach To Optical Turbulence Mitigation And Its Application To Simulated And Real Imagery With Quantitative Error Analysis, Russell C. Hardie, Michael Armand Rucci, Barry K. Karch, Alexander J. Dapore

Electrical and Computer Engineering Faculty Publications

We present a block-matching and Wiener filtering approach to atmospheric turbulence mitigation for long-range imaging of extended scenes. We evaluate the proposed method, along with some benchmark methods, using simulated and real-image sequences. The simulated data are generated with a simulation tool developed by one of the authors. These data provide objective truth and allow for quantitative error analysis. The proposed turbulence mitigation method takes a sequence of short-exposure frames of a static scene and outputs a single restored image. A block-matching registration algorithm is used to provide geometric correction for each of the individual input frames. The registered frames …