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Electrical and Computer Engineering ETDs

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Full-Text Articles in Engineering

Identification Of The Corona Point In Point-To-Plane Geometries In Atmospheric Air, Leonardo Rossetti Jul 2019

Identification Of The Corona Point In Point-To-Plane Geometries In Atmospheric Air, Leonardo Rossetti

Electrical and Computer Engineering ETDs

The minimum sustaining electric field for streamer propagation is directly correlated to the minimum electric field at the corona point. Corona is a product of non-uniform electric fields; the onset of corona occurs before electrical breakdown. As electric fields become increasingly uniform the required field strength to produce corona is increased as well. The field uniformity can be increased until a critical point in which electrical breakdown coincides with the onset of a positive corona, this is known as the corona point.

An experimental setup with a point to plane configuration allows precise changes in electric field uniformity, by gradually ...


Design And Fabrication Of Peel-Off And Stick Antennas, Jayakrishnan Vijayamohanan Jul 2019

Design And Fabrication Of Peel-Off And Stick Antennas, Jayakrishnan Vijayamohanan

Electrical and Computer Engineering ETDs

Antennas on multiple platforms with the capability to be reused is a novel concept in antenna technologies. This thesis explores the idea of such a flexible antenna that can be stuck on any surface using certain adhesives and be peeled off for reuse for a different purpose. This thesis specifically focuses on the application of being used on small Unmanned Aircraft Systems (sUAVs). Three basic designs are fabricated and investigated. One of them is a reconfigurable meandering monopole, consisting of a PIN diode which resonates at two different frequencies depending on the applied external voltage. A challenge that is addressed ...


The Importance Of The Instantaneous Phase In Detecting Faces With Convolutional Neural Networks, Luis Armando Sanchez Tapia Jul 2019

The Importance Of The Instantaneous Phase In Detecting Faces With Convolutional Neural Networks, Luis Armando Sanchez Tapia

Electrical and Computer Engineering ETDs

Convolutional Neural Networks (CNN) have provided new and accurate methods for processing digital images and videos. Yet, training CNNs is extremely demanding in terms of computational resources. Also, for simple applications, the standard use of transfer learning also tends to require far more resources than what may be needed. Furthermore, the final systems tend to operate as black boxes that are difficult to interpret.

The current thesis considers the problem of detecting faces from the AOLME video dataset. The AOLME dataset consists of a large video collection of group interactions that are recorded in unconstrained classroom environments. For the thesis ...


Verification Of Stochastic Reach-Avoid Using Rkhs Embeddings, Adam J. Thorpe Jul 2019

Verification Of Stochastic Reach-Avoid Using Rkhs Embeddings, Adam J. Thorpe

Electrical and Computer Engineering ETDs

A solution to the terminal-hitting and first-hitting stochastic reach-avoid problem for a Markov control process is presented. This solution takes advantage of a nonparametric representation of the stochastic kernel as a conditional distribution embedding within a reproducing kernel Hilbert space (RKHS). Because the disturbance is modeled as a data-driven stochastic process, this representation avoids intractable integrals in the dynamic recursion of the reach-avoid problem since the expectations can be calculated as an inner product within the RKHS. An example using a high-dimensional chain of integrators is presented, as well as for Clohessy-Wiltshire-Hill (CWH) dynamics.


Large Scale Electronic Health Record Data And Echocardiography Video Analysis For Mortality Risk Prediction, Alvaro Emilio Ulloa Cerna Jul 2019

Large Scale Electronic Health Record Data And Echocardiography Video Analysis For Mortality Risk Prediction, Alvaro Emilio Ulloa Cerna

Electrical and Computer Engineering ETDs

Electronic health records contain the clinical history of patients. The enormous potential for discovery in such a rich dataset is hampered by their complexity. We hypothesize that machine learning models trained on EHR data can predict future clinical events significantly better than current models. We analyze an EHR database of 594,862 Echocardiography studies from 272,280 unique patients with both unsupervised and supervised machine learning techniques.

In the unsupervised approach, we first develop a simulation framework to evaluate a family of different clustering pipelines. We apply the optimized approach to 41,645 patients with heart failure without providing any ...


Nonpolar Gan-Based Vcsels With Lattice-Matched Nanoporous Distributed Bragg Reflector Mirrors, Saadat M. Mishkat-Ul-Masabih Jul 2019

Nonpolar Gan-Based Vcsels With Lattice-Matched Nanoporous Distributed Bragg Reflector Mirrors, Saadat M. Mishkat-Ul-Masabih

Electrical and Computer Engineering ETDs

Wide-bandgap optoelectronic devices have undergone significant advancements with the advent of commercial light-emitting diodes and edge-emitting lasers in the violet-blue spectral region. They are now ubiquitous in several lighting, communication, data storage, display, and sensing applications. Among the III-nitride emitters, vertical-cavity surface-emitting lasers (VCSELs) have attracted significant attention in recent years due to their inherent advantages over edge-emitting lasers. The small active volume enables single-mode operation with low threshold currents and high modulation bandwidths. Their surface-normal device geometry is conducive to the cost-effective formation of high-density 2D arrays while simplifying on-chip wafer testing. Furthermore, the low beam divergence and circular ...


Non-Invasive Beam Monitoring With Harmonic Cavities, Brock F. Roberts Apr 2019

Non-Invasive Beam Monitoring With Harmonic Cavities, Brock F. Roberts

Electrical and Computer Engineering ETDs

NON INVASIVE BEAM MONITORING WITH HARMONIC CAVITIES

by

Brock Franklin Roberts

B.S PHYSICS, UNIVERSITY OF CALIFORNIA DAVIS, 1992

DOCTOR OF PHILOSOPHY IN ELECTRICAL ENGINEERING

UNIVERSITY OF NEW MEXICO, 2019

ABSTRACT

A cavity designed to have multiple harmonic TM0N0 modes can be used to accurately measure the longitudinal profile of a bunched charged particle beam passing through its bore, non-invasively, and in real time.

Multi-harmonic TM0N0 cavities were designed, constructed, and beamline tested in a variety of experiments at the Thomas Jefferson National Accelerator Facility (TJNAF or Jlab). Measurements with a sampling oscilloscope provided signals that resemble the profile of ...


Transport In Mid-Wavelength Infrared (Mwir) P- And N-Type Inassb And Inas/Inassb Type-Ii Strained Layer Superlattices (T2sls) For Infrared Detection, Lilian K. Casias Apr 2019

Transport In Mid-Wavelength Infrared (Mwir) P- And N-Type Inassb And Inas/Inassb Type-Ii Strained Layer Superlattices (T2sls) For Infrared Detection, Lilian K. Casias

Electrical and Computer Engineering ETDs

In order to tackle vertical transport, lateral transport must be better understood. There are added challenges to determining the lateral bulk carrier concentration in narrow bandgap materials due to the potential for electron accumulation at the surface of the material and at its interface with the layer grown directly below it. Electron accumulation layers form high conductance electron channels that can dominate both resistivity and Hall-Effect transport measurements. Therefore, to correctly determine the lateral bulk concentration and mobility, temperature- and magnetic-field-dependent transport measurements in conjunction with Multi-Carrier Fit (MCF) analysis were utilized on a series of p-doped InAs0 ...


Detection And Classification Of Vibrating Objects In Sar Images, Francisco German Perez Venegas Apr 2019

Detection And Classification Of Vibrating Objects In Sar Images, Francisco German Perez Venegas

Electrical and Computer Engineering ETDs

The vibratory response of buildings and machines contains key information that can be exploited to infer their operating conditions and to diagnose failures. Furthermore, since vibration signatures observed from the exterior surfaces of structures are intrinsically linked to the type of machinery operating inside of them, the ability to monitor vibrations remotely can enable the detection and identification of the machinery.

This dissertation focuses on developing novel techniques for the detection and M-ary classification of vibrating objects in SAR images. The work performed in this dissertation is conducted around three central claims. First, the non-linear transformation that the micro-Doppler return ...


Optimizing Interconnectivity Among Networks Under Attacks, Pankaz Das Jan 2019

Optimizing Interconnectivity Among Networks Under Attacks, Pankaz Das

Electrical and Computer Engineering ETDs

Networks may need to be interconnected for various reasons such as inter-organizational communication, redundant connectivity, increasing data-rate and minimizing delay or packet-loss, etc. However, the trustworthiness of an added interconnection link cannot be taken for granted due to the presence of attackers who may compromise the security of an interconnected network by intercepting the interconnections. Namely, an intercepted interconnection link may not be secured due to the data manipulations by attackers. In the first part of this dissertation, the number of interconnections between the two networks is optimized for maximizing the data-rate and minimizing the packet-loss under the threat of ...


Noise And Gain Characterization Of Interband Cascade Infrared Photodetectors, Eli A. Garduño Dec 2018

Noise And Gain Characterization Of Interband Cascade Infrared Photodetectors, Eli A. Garduño

Electrical and Computer Engineering ETDs

Infrared (IR) detectors are an enabling technology for a broad and growing list of applications including gas detection, night vision, and space-based missile warning. There are ongoing efforts in IR detector research to explore the potential of new material systems and energy band structures in addition to continuously improving their sensitivity through increasing their quantum efficiency and lowering their dark current and noise. This dissertation examines an emerging class of IR detectors known as Interband Cascade Infrared Photodetectors (ICIPs).

ICIPs contain multiple regions to facilitate the collection of photogenerated electrons and to limit unwanted dark current. Theory regarding their performance ...


Frequency Domain Decomposition Of Digital Video Containing Multiple Moving Objects, Victor M. Stone Nov 2018

Frequency Domain Decomposition Of Digital Video Containing Multiple Moving Objects, Victor M. Stone

Electrical and Computer Engineering ETDs

Motion estimation has been dominated by time domain methods such as block matching and optical flow. However, these methods have problems with multiple moving objects in the video scene, moving backgrounds, noise, and fractional pixel/frame motion. This dissertation proposes a frequency domain method (FDM) that solves these problems. The methodology introduced here addresses multiple moving objects, with or without a moving background, 3-D frequency domain decomposition of digital video as the sum of locally translational (or, in the case of background, a globally translational motion), with high noise rejection. Additionally, via a version of the chirp-Z, fractional pixel/frame ...


Scalable Stochastic Reachability: Theory, Computation, And Control, Abraham Puthuvana Vinod Nov 2018

Scalable Stochastic Reachability: Theory, Computation, And Control, Abraham Puthuvana Vinod

Electrical and Computer Engineering ETDs

Guaranteeing safety and performance are crucial components in any control system, and particularly relevant in light of growing interest in reliable autonomy. In safety-critical applications like biomedical devices, spacecraft applications, and self-driving cars, the cost of failure can be severe. Verification provides these guarantees by characterizing the ``good'' initial states or configurations from which a state can be driven to remain within a collection of pre-specified safe sets, while respecting the system dynamics, bounds on control authority, and additive uncertainties. We also wish to design controllers to achieve this objective. This dissertation proposes novel theory and scalable algorithms for tractable ...


Carrier Lifetime Vs. Proton Radiation In Prototype Iii-V And Ii-Vi Space-Based Infrared Detectors, Geoffrey D. Jenkins Nov 2018

Carrier Lifetime Vs. Proton Radiation In Prototype Iii-V And Ii-Vi Space-Based Infrared Detectors, Geoffrey D. Jenkins

Electrical and Computer Engineering ETDs

Researchers have spent over 50 years improving the performance of HgCdTe infrared (IR) detectors and it is currently the dominant technology in the field; however, further improvement may be limited due to devices reaching the intrinsic limits of their constituent materials. To further improve the state-of-the-art in space-based IR detection, alternative material systems are being considered. The focus of this work is testing the space-environment viability of innovative device structures, namely unipolar barriers with Type-II superlattice (T2SL) absorbers, made from the 6.1 Å family of III-V elements which are theoretically superior performers while being less costly.

Sensitive IR photo-detection ...


A Novel Indoor Positioning System For Firefighters In Unprepared Scenarios, Vamsi Karthik Vadlamani Oct 2018

A Novel Indoor Positioning System For Firefighters In Unprepared Scenarios, Vamsi Karthik Vadlamani

Electrical and Computer Engineering ETDs

Situational awareness and indoor positioning of firefighters are types of information of paramount importance to the success of search and rescue operations. GPS units are undependable for use in Indoor Positioning Systems due to their associated mar- gins of error in position and their reliance on satellite communication that can be interrupted inside large structures. There are few other techniques like dead reck- oning, Wifi and bluetooth based triangulation, Structure from Motion (SFM) based scene reconstruction for Indoor positioning system. However due to high temper- atures, the rapidly changing environment of fires, and low parallax in the thermal images, the ...


A Narrow-Wall Complementary-Split-Ring Slotted Waveguide Antenna For High-Power-Microwave Applications, Xuyuan Pan Oct 2018

A Narrow-Wall Complementary-Split-Ring Slotted Waveguide Antenna For High-Power-Microwave Applications, Xuyuan Pan

Electrical and Computer Engineering ETDs

A narrow-band, rugged, complementary-split-ring (CSR) slotted waveguide antenna (SWA) with significant size reduction is presented. The antenna is to be vertically front mounted on a land vehicle, with a horizontally polarized fan-beam radiation pattern. The radiation characteristics of a CSR slot in the narrow-wall of a rectangular waveguide are studied for the first time in this work. Both simulation and experimental results show that the complementary-split-ring slot radiates a linearly polarized wave with a total efficiency and gain close to those of conventional longitudinal slots, while the proposed CSR slots have a maximal outer diameter of 0.23λ0, much ...


Oxygen And Silver-Oxygen Defects In Ge2se3 Electrochemical Metallization Bridge Memristors, Jau-Tzuoo Chen Sep 2018

Oxygen And Silver-Oxygen Defects In Ge2se3 Electrochemical Metallization Bridge Memristors, Jau-Tzuoo Chen

Electrical and Computer Engineering ETDs

We present density functional theory (DFT) calculations of oxygen and silver defects in a crystalline model of amorphous Ge2Se3. We studied defects arising from atomic oxygen and dioxygen, as well as interstitial silver and silver displacing germanium, following Campbell's conjecture on the mechanism of dendrite formation. For oxygen defect concentrations below 2%, we show that O2 dissociates in Ge2Se3, oxygen atoms are immobile, and oxygen atoms do not cluster. Within this model, the most preferred oxygen defect in intrinsic Ge2Se3 is Ge-O-Ge bridge. We conclude that oxygen defects will ...


Characterization Of Gallium Nitride Photoconductive Semiconductor Switches In The Nonlinear Regime, Joseph D. Teague Jul 2018

Characterization Of Gallium Nitride Photoconductive Semiconductor Switches In The Nonlinear Regime, Joseph D. Teague

Electrical and Computer Engineering ETDs

The energy demands of an increasingly electrified world have caused a renewed interest in once dormant fields of research. Photoconductive Semiconductor switches (PCSS) are one of these fields. They theoretically offer high voltage, high current switching in sub cm3 packaging, without the shot to shot variation and bulk of current high-power DC switches such as spark gaps. PCSS are capable of power densities of 109-1010 W/cm3, with electric fields ranging from 105-106 V/cm and current densities from 104-106 A/cm2 [1].

Most PCSS make a trade-off ...


Hand Movement Detection In Collaborative Learning Environment Videos, Callie J. Darsey Jul 2018

Hand Movement Detection In Collaborative Learning Environment Videos, Callie J. Darsey

Electrical and Computer Engineering ETDs

Human activity detection in digital videos is currently attracting significant research interest. This problem is especially challenging for video datasets that have a lot of human activity, illumination noise, and structural noise. The video dataset associated with the Advancing Out of School Learning in Mathematics and Engineering (AOLME) project has these challenges. ALOME videos have been used in the study of human activities “in the wild”.

This thesis explores detection of hand movement using color and optical flow. Exploratory analysis considered the problem component wise on components created from thresholds applied to motion and color. The proposed approach uses patch ...


Capacitive Pcb Security For Active Tamper And Alteration Detection, Casey Petersen Jul 2018

Capacitive Pcb Security For Active Tamper And Alteration Detection, Casey Petersen

Electrical and Computer Engineering ETDs

The purpose of the research presented is to establish the viability of using capacitive based sensors for the purpose of hardware security at the Printed Circuit Board (PCB) level. Capacitive sensors are traditionally used to sense changes to the areas surrounding the sensing pads in applications such as sensing proximity, position, humidity, fluid levels and much more.

The specific sensor used for this research is an inductor-capacitor (LC) based Capacitance-to-Digital Converter. This configuration is virtually immune to EM noise because it is a tank circuit and therefore filters out the noise which, in the past, caused reliability issues with these ...


Pulse Sharpening Circuit For Explosive Emission Cathode Driver, Nicholas D. Kallas Jul 2018

Pulse Sharpening Circuit For Explosive Emission Cathode Driver, Nicholas D. Kallas

Electrical and Computer Engineering ETDs

Explosive field emission cathodes (EEC), used for the generation of relativistic electron beams, require short rise-time high-voltage pulses in order to minimize the extraction of off-energy electrons. To this end, a rise-time sharpening circuit has been developed at the Los Alamos National Laboratory (LANL). The circuit consists of a 7 nF water-filled peaking capacitor with an integrated self-breakdown switch designed to operate up to -300 kV. This unit is intended to reduce the rise-time of a 4-stage Type-E PFN Marx Generator that will be used to study operational characteristics of velvet cathodes. Simulations of the peaking circuit show a reduction ...


Selected Applications Of Silicon Nanopillar Arrays., Behnam Kheyraddini Mousavi Jul 2018

Selected Applications Of Silicon Nanopillar Arrays., Behnam Kheyraddini Mousavi

Electrical and Computer Engineering ETDs

Interaction of optical waves with nanostructures made of various material systems has been the subject of intensive research for many years. These researches have been mainly driven by the need to make smaller optical devices and exploiting the functionalities offered by light-matter interaction in nanoscale. Majority of the nanostructures are fabricated using electron beam (e-beam) lithography that is slow and expensive. As such alternative methods have been developed to enable nanoscale fabrication faster and less expensive. Among these interferometric lithography (IL) is a relatively simple method for quick fabrication of nanostructures. As IL method generates periodic patterns, exploring the potential ...


Intelligent Computational Transportation, Yuming Zhang Jul 2018

Intelligent Computational Transportation, Yuming Zhang

Electrical and Computer Engineering ETDs

Transportation is commonplace around our world. Numerous researchers dedicate great efforts to vast transportation research topics. The purpose of this dissertation is to investigate and address a couple of transportation problems with respect to geographic discretization, pavement surface automatic examination, and traffic ow simulation, using advanced computational technologies. Many applications require a discretized 2D geographic map such that local information can be accessed efficiently. For example, map matching, which aligns a sequence of observed positions to a real-world road network, needs to find all the nearby road segments to the individual positions. To this end, the map is discretized by ...


Synchronization In An Externally Driven Mechanical Oscillators Experiment, Sumit Chhabria Jul 2018

Synchronization In An Externally Driven Mechanical Oscillators Experiment, Sumit Chhabria

Electrical and Computer Engineering ETDs

Our experimental system studies the effects of externally controlled oscillation on directly and indirectly driven system of metronomes. This is analogous to many practical systems such as pacemaker effect on heart cells, the external light effect on the suprachiasmatic nucleus in the brain. Here the pacemaker can be compared to an external driving force to the system where the heart cells are our oscillating system. Also, in the suprachiasmatic nucleus cell system, the external input is external light which synchronizes the cell. We explore the synchronization of directly and indirectly driven metronomes due to externally provided forcing.

We designed an ...


High-Performance Testbed For Vision-Aided Autonomous Navigation For Quadrotor Uavs In Cluttered Environments, Shakeeb Ahmad Jul 2018

High-Performance Testbed For Vision-Aided Autonomous Navigation For Quadrotor Uavs In Cluttered Environments, Shakeeb Ahmad

Electrical and Computer Engineering ETDs

This thesis presents the development of an aerial robotic testbed based on Robot Operating System (ROS). The purpose of this high-performance testbed is to develop a system capable of performing robust navigation tasks using vision tools such as a stereo camera. While ensuring the computation of robot odometery, the system is also capable of sensing the environment using the same stereo camera. Hence, all the navigation tasks are performed using a stereo camera and an inertial measurement unit (IMU) as the main sensor suite. ROS is used as a framework for software integration due to its capabilities to provide efficient ...


Multirate Frequency Transformations: Wideband Am-Fm Demodulation With Applications To Signal Processing And Communications, Wenjing Liu Jul 2018

Multirate Frequency Transformations: Wideband Am-Fm Demodulation With Applications To Signal Processing And Communications, Wenjing Liu

Electrical and Computer Engineering ETDs

The AM-FM (amplitude & frequency modulation) signal model finds numerous applications in image processing, communications, and speech processing. The traditional approaches towards demodulation of signals in this category are the analytic signal approach, frequency tracking, or the energy operator approach. These approaches however, assume that the amplitude and frequency components are slowly time-varying, e.g., narrowband and incur significant demodulation error in the wideband scenarios. In this thesis, we extend a two-stage approach towards wideband AM-FM demodulation that combines multirate frequency transformations (MFT) enacted through a combination of multirate systems with traditional demodulation techniques, e.g., the Teager-Kasiser energy operator demodulation ...


Characterization Of Wideband U-Slot Patch Antennas Through Characteristic Modal Analysis And Coupled Mode Theory, Tyler Lapointe May 2018

Characterization Of Wideband U-Slot Patch Antennas Through Characteristic Modal Analysis And Coupled Mode Theory, Tyler Lapointe

Electrical and Computer Engineering ETDs

Microstrip patch antennas (MPAs) are utilized in many applications as they are easy to produce and are thin, versatile, light weight, cheap, and reliable. One of the drawbacks of MPAs, however, is their narrow bandwidth, typically three to ten percent. Fortunately, a perturbation exists capable of resolving this issue known as the U-slot which can increase the operational bandwidth of a single layer MPA to around 30 percent. Often it is reported that the wideband performance of this structure results from the existence of two resonators, the patch and the U-shaped slot. While this is true, the very nature of ...


On Improved Accuracy Chirp Parameter Estimation Using The Dfrft With Application To Sar-Based Vibrometry, Satish Mandal May 2018

On Improved Accuracy Chirp Parameter Estimation Using The Dfrft With Application To Sar-Based Vibrometry, Satish Mandal

Electrical and Computer Engineering ETDs

The Discrete Fractional Fourier Transform (DFRFT) has in recent years, become a useful tool for multicomponent chirp signal analysis. Chirp signals are transformed into spectral peaks in the chirp rate versus center frequency representation, whose coordinates are related to the underlying chirp parameters via a computed empirical peak to parameter mapping incorporated into the Santhanam-Peacock algorithm.

In this thesis, we attempt to quantify the accuracy of the DFRFT approach by first studying the discretization error sources that arise from the transitioning of the continuous FRFT to DFRFT. Then, we refine prior work by Ishwor Bhatta to develop analytical expressions for ...


Optimization Of Supersingular Isogeny Cryptography For Deeply Embedded Systems, Jeffrey Denton Calhoun May 2018

Optimization Of Supersingular Isogeny Cryptography For Deeply Embedded Systems, Jeffrey Denton Calhoun

Electrical and Computer Engineering ETDs

Public-key cryptography in use today can be broken by a quantum computer with sufficient resources. Microsoft Research has published an open-source library of quantum-secure supersingular isogeny (SI) algorithms including Diffie-Hellman key agreement and key encapsulation in portable C and optimized x86 and x64 implementations. For our research, we modified this library to target a deeply-embedded processor with instruction set extensions and a finite-field coprocessor originally designed to accelerate traditional elliptic curve cryptography (ECC). We observed a 6.3-7.5x improvement over a portable C implementation using instruction set extensions and a further 6.0-6.1x improvement with the addition of ...


Split-Ring Resonator Waveguide Structure Characterization By Simulations, Measurements And Linear Time-Invariant Modeling, Mohamed Aziz Hmaidi May 2018

Split-Ring Resonator Waveguide Structure Characterization By Simulations, Measurements And Linear Time-Invariant Modeling, Mohamed Aziz Hmaidi

Electrical and Computer Engineering ETDs

Interest in Metamaterials has been rising drastically in the recent years as they have been used in several optical and RF applications, from antennas to perfect lenses and pulsed power devices. Nevertheless, the time-behavior of metamaterials remains opaque and poorly understood.

In this research work, characterization of a metamaterial structure in time and frequency-domain was made through simulations and experiments. The structure consists in a series of edge-side coupled Split Ring Resonators (SRRs) in a below cutoff waveguide. A linear time invariant model of distributed elements has been elaborated as well in an attempt to approach the structure’s behavior ...