Electrical and Computer Engineering Commons^™

Home Automation Via Smart Technology, Christian Griggs, Audrey Morrisette, James Pepper

Capstone Design Expo Posters

Problem Statement The idea of an ‘Internet of Everything’ has been floating around for a while, but beyond mere buzzword this concept carries with it immense, and unfortunately as of yet untapped potential. The idea of complete interconnectivity most typically conjures images of home automation; smart appliances capable of self-regulation, self-setting thermostats, etc., but with this connectivity comes with it not only the capacity to remotely monitor an existing system but to control it as well (be it with a smart phone, online application, what have you). There exists ‘smart technologies’ which incorporate user’s smart phones in the operation and …

Small Scale Wide Band Radio Frequency Spectrum Analyzer, Ali Aldajaei, Ryan Littleton, Matthew Thomas

Capstone Design Expo Posters

The project being proposed has to deal the processing and identification of radio frequencies. As more and more frequencies are being used on the radio spectrum, noise and interference have become a problem. Currently spectrum analyzers can be used to identify this noise and interference but they require manpower and specialized equipment. Our project will focus on automating the process of analyzing multiple frequencies and identifying signals from interference. This will be done by first taking an input from a radio antenna to acquire radio signals at various frequencies and storing the values. These values will then be analyzed to …

Human-Machine Interfacing Via Epidermal Electronic Systems, Michael Flynn, Matthew Nelson, Stefan Sharpley, Drew Simmons

Capstone Design Expo Posters

Surface electromyography (EMG) is rapidly becoming a viable control source for interfacing with machines. By measuring the electric potential generated by the contractions of skeletal muscles, systems can be controlled with a mere flick of the wrist, allowing intuitive and versatile control to the wielder. As sensors and classification algorithms become more sophisticated, EMG control has increasing potential to revolutionize the way we interact with and utilize technology. Prosthetics in particular have benefited the most from these recent advances, with one research team successfully returning ambulation to a leg amputee last year. However, this technology is not yet suitable for …

Wind Energy Harvesters For Urban Small Scale Power Generation, James Mcnamee, Zachary Gartrell, Andrew Krupacs

Capstone Design Expo Posters

The energy demands of society are increasing, and the ability to produce this energy from renewable sources such as wind must also increase to meet these demands. Large wind turbines are a great way to harvest renewable wind power, but they are often too large to use in an urban environment.

This project focuses on designing wind energy harvesters, based on existing iterations that produce output power per area comparable to that of an efficient wind turbine, approximately 3 watts per harvester that is 1 meter long. In order to reach this target power level, two innovative designs are under …

Automated Magnetic Field Scanning System, George Bakirtzis, Tim Owen, Tara Powell

Capstone Design Expo Posters

One of Jefferson Laboratory’s research areas is in Superconducting Radio Frequency (SRF) science and technology. SRF cavities are tested in the Vertical Testing Area (VTA) at Jefferson Laboratory, within a series of large cylindrical dewars. The measured quality factor (Q factor) of the SRF cavity is directly influenced by any existing magnetic field. Because the VTA previously housed a cyclotron, all the rebars within the building have residual magnetic fields emanating from them. This magnetic field effect of the building renders the measurements of Q factor on the devices inaccurate and the testing data unreliable. A magnetic field scanning system …

Automotive Object Detection Training System, Lucas Cerully, Salima Fenaoui, Derek Mccubbin

Capstone Design Expo Posters

With a constant rise in the automobile industry, there is a demand for more advanced integratable technology along with it. With the consumer’s safety always in mind, automobile companies are adding more to their systems to help detect and prevent collisions. Among these technologies is the object detection system. In summary, this component warns or reacts to oncoming objects that could put the driver in danger. As with any piece of technology, there are problems and bugs that the object detection system can come across that would cause it to act irregularly. In turn, this requires the availability of technicians …

Non-Causal Autonomous Parking System For Driverless Vehicles, Ngoc Hue Vo, Swarna Chowdhuri, Ivo Yotov

Capstone Design Expo Posters

According to an Audi Urban Future Initiative study, the average person spends 106 days over their life-time searching for parking spaces. Whether it is on the side of a busy city street or a shopping center car park, the issue of parking private vehicles poses a substantial logistical challenge that scales in complexity along with population density. As modern populations trend towards urbanization it becomes imperative to develop more efficient parking structures. With the inevitable shift towards driverless vehicles, there exists a need to establish a control system to mitigate these complications. One embodiment of such a solution is a …

Reversible Strain-Induced Magnetization Switching In Fega Nanomagnets: Pathway To A Rewritable, Non-Volatile, Non-Toggle, Extremely Low Energy Straintronic Memory, Hasnain Ahmad, Jayasimha Atulasimha, Supriyo Bandyopadhyay

Electrical and Computer Engineering Publications

We report reversible strain-induced magnetization switching between two stable/metastable states in ~300 nm sized FeGa nanomagnets delineated on a piezoelectric PMN-PT substrate. Voltage of one polarity applied across the substrate generates compressive strain in a nanomagnet and switches its magnetization to one state, while voltage of the opposite polarity generates tensile strain and switches the magnetization back to the original state. The two states can encode the two binary bits, and, using the right voltage polarity, one can write either bit deterministically. This portends an ultra-energy-efficient non-volatile “non-toggle” memory.

Temperature Measurement Of Server Room, Eric Cobbinah, Faida Matabaro, Michael Tu, James Mcadams

Capstone Design Expo Posters

In this project we will be developing a system to help monitor temperature in data centers. This system will include software and a circuit to route resistive temperature devices (RTDs) (Figure 1) to a microchip which will output their readings as data. The system should be able to connect with 64 RTDs, read the temperatures from them, and make the data accessible over a network. This system could also be used in other situations besides data centers. The user would decide where to place the devices and how to use the temperature data. This system will allow more RTDs to …

Head-Tracking Wireless Streaming Device, Christopher Foster, Kyle Arpe, Zachary Somers

Capstone Design Expo Posters

In various businesses and services, there is a need for tight integration between visual media, human response to that media, and coordination of that response. For example, emergency responders may need information from a separate perspective using robotically controlled cameras in order to improve coordination efforts. The aim of this project is to design a low cost, high performance video streaming device. The essential feature of our design is to wirelessly send a video stream from a webcam to a micro-display and remotely control the orientation of the webcam using head movements. There are many future applications for this project …

Automated Disc Kiosks, Kal Stankov, Allen Woods, Yaw Amoatin

Capstone Design Expo Posters

Our improved automated disc kiosks are designed with two purposes in mind: to improve the inventory management and agility of current automated media rental services and to simplify and consolidate the storage and distribution of installation media in an IT environment. The kiosks combine the ability to store and dispense optical discs (CDs, DVDs, Blu-Ray Discs, etc.) with the ability to burn newer content pushed out via a network connection from a company’s servers. Designed and built with commonly available components to minimize costs, the prototype consists of a Digilent Zybo FPGA board powered by a Xilinx processor. A tablet …

A Study On False Information Injection Attack On Dynamic State Estimation In Multi-Sensor Systems, Jingyang Lu

Theses and Dissertations

In this thesis, the impact of false information injection is investigated for linear dynamic systems with multiple sensors. It is assumed that the Kalman filter system is unaware of the existence of false information and the adversary is trying to maximize the negative effect of the false information on the Kalman filter's estimation performance. First, a brief introduction to the Kalman filter is shown in the thesis. We mathematically characterize the false information attack under different conditions. For the adversary, many closed-form results for the optimal attack strategies that maximize the Kalman filter's estimation error are theoretically derived. It is …

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.

Spatio-Temporal Modeling Of Anatomic Motion For Radiation Therapy, Elizabeth Zachariah

Theses and Dissertations

In radiation therapy, it is imperative to deliver high doses of radiation to the tumor while reducing radiation to the healthy tissue. Respiratory motion is the most significant source of errors during treatment. Therefore, it is essential to accurately model respiratory motion for precise and effective radiation delivery. Many approaches exist to account for respiratory motion, such as controlled breath hold and respiratory gating, and they have been relatively successful. They still present many drawbacks. Thus, research has been expanded to tumor tracking.

The overall goal of 4D-CT is to predict tumor motion in real time, and this work attempts …

Censoring And Fusion In Non-Linear Distributed Tracking Systems With Application To 2d Radar, Armond S. Conte Ii

Theses and Dissertations

The objective of this research is to study various methods for censoring state estimate updates generated from radar measurements. The generated 2-D radar data are sent to a fusion center using the J-Divergence metric as the means to assess the quality of the data. Three different distributed sensor network architectures are considered which include different levels of feedback. The Extended Kalman Filter (EKF) and the Gaussian Particle Filter (GPF) were used in order to test the censoring methods in scenarios which vary in their degrees of non-linearity. A derivation for the direct calculation of the J-Divergence using a particle filter …

Strain Controlled Ultra-Low-Energy Magnetic Tunneling Junction, Hasnain Ahmad, Supriyo Bandyopadhyay, Jayasimha Atulasimha

Graduate Research Posters

We are experimenting on designing a voltage-controlled ultra-low-energy Magnetic Tunneling Junction (MTJ) device using a soft single domain magnetostrictive layer (i.e. Galfenol: Fe_1-xGa_x , x = 20 At%) coupled to a piezoelectric layer (i.e. PMN-PT). Special metal pads have been designed using photolithography to generate stress in the PMN-PT layer by applying electric field. The patterns of different shape anisotropic nano-magnets are designed using e-beam lithography and we have successfully fabricate FeGa nanomagnets with only 12 to 13 nanometer thickness by sputter deposition. These nanomagnets have been characterized by magnetic force microscopy for observing their switching capabilities. …

Coherent Spin Transport In Nanowire Spin Valves And Novel Spintronic Device Possibilities, Md Iftekhar I. Hossain, Supriyo Bandyopadhyay, Jayasimha Atulasimha, Saumil Bandyopadhyay

Graduate Research Posters

We have proposed a spintronic infrared photodetector backed by experimental evidence and matched with theoretical prediction obtained in our labs. Unlike conventional photodetectors, it can work at room temperature with ideally infinite light-to-dark contrast ratio, infinite detectivity and zero dark current. The proposed idea is based on smart implementation of spin polarized transport. Electrons while travelling through one-dimensional channel show long spin relaxation length if they can be confined to a single conduction subband because of the elimination of major spin relaxation mechanism, namely the D’yakonov-Perel’ mechanism. With infrared light, electrons can be excited to higher subbands, resulting in the …

Proactive Conversation, 3d Printing, And An Old Nintendo, Tesha C. Ellis

Undergraduate Research Posters

Abstract

One hundred years from now, it would be a true historical treat to be able to showcase 20th and 21st century digital entertainment by presenting video game consoles in mint condition for interactive, educational, play. Arguably, it would be more enlightening and informative for future audiences to be able to physically engage with the electronic artifacts instead of simply observing them behind glass. With the use of 3D technology, components of video game systems can be preserved, and then printed as needed for repairs. It will help keep them functional for future researchers, educators, and enthusiasts.

Energy-Efficient Magnetoelastic Non-Volatile Memory, Ayan K. Biswas, Supriyo Bandyopadhyay, Jayasimha Atulasimha

Electrical and Computer Engineering Publications

We propose an improved scheme for low-power writing of binary bits in non-volatile (multiferroic) magnetic memory with electrically generated mechanical stress. Compared to an earlier idea [N. Tiercelin et al., J. Appl. Phys. 109, 07D726 (2011)], our scheme improves distinguishability between the stored bits when the latter are read with magneto-tunneling junctions. More importantly, the write energy dissipation and write error rate are reduced significantly if the writing speed is kept the same. Such a scheme could be one of the most energy-efficient approaches to writing bits in magnetic non-volatile memory. (C) 2014 AIP Publishing LLC.

Critical Analysis And Remedy Of Switching Failures In Straintronic Logic Using Bennett Clocking In The Presence Of Thermal Fluctuations, Kuntal Roy

Electrical and Computer Engineering Publications

Straintronic logic is a promising platform for beyond Moore's law computing. Using Bennett clocking mechanism, information can propagate through an array of strain-mediated multiferroic nanomagnets, exploiting the dipolar coupling between the magnets without having to physically interconnect them. Here, we perform a critical analysis of switching failures, i.e., error in information propagation due to thermal fluctuations through a chain of such straintronic devices. We solved stochastic Landau-Lifshitz-Gilbert equation considering room-temperature thermal perturbations and show that magnetization switching may fail due to inherent magnetization dynamics accompanied by thermally broadened switching delay distribution. Avenues available to circumvent such issue are proposed. (C) …

Nanowire-Based Frequency-Selective Capacitive Photodetector For Resonant Detection Of Infrared Radiation At Room Temperature, Saumil Bandyopadhyay

Electrical and Computer Engineering Publications

Characteristics of a capacitive infrared photodetector that works at room temperature by registering a change in capacitance upon illumination are reported. If used in an ideal resonant inductor-resistor-capacitor circuit, it can exhibit zero dark current, zero standby power dissipation, infinite detectivity, and infinite light-to-dark contrast ratio. It is also made frequency-selective by employing semiconductor nanowires that selectively absorb photons of energies close to the nanowire's bandgap. Based on measured parameters, the normalized detectivity is estimated to be ∼3 × 10⁷ Jones for 1.6 μm IR wavelength at room temperature.

Excitonic Recombination Dynamics In Non-Polar Gan/Algan Quantum Wells, D. Rosales, B. Gil, T. Bretagnon, B. Guizal, F. Zhang, S. Okur, M. Monavarian, N. Izyumskaya, V. Avrutin, Ü Özgür, H. Morkoç, J. H. Leach

Electrical and Computer Engineering Publications

The optical properties of GaN/Al0.15Ga0.85N multiple quantum wells are examined in 8 K–300 K temperature range. Both polarized CW and time resolved temperature-dependent photoluminescence experiment are performed so that we can deduce the relative contributions of the non-radiative and radiative recombination processes. From the calculation of the proportion of the excitonic population having wave vector in the light cone, we can deduce the variation of the radiative decay time with temperature. We find part of the excitonic population to be localized in concert with the report of Corfdir et al. (Jpn. J. Appl. Phys., Part 2 52, 08JC01 (2013)) in …

Properties Of The Main Mg-Related Acceptors In Gan From Optical And Structural Studies, B. Monemar, P. P. Paskov, G. Pozina, C. Hemmingsson, J. P. Bergman, S. Khromov, V. N. Izyumskaya, V. Avrutin, X. Li, H. Morkoç, H. Amano, M. Iwaya, I. Akasaki

Electrical and Computer Engineering Publications

The luminescent properties of Mg-doped GaN have recently received particular attention, e.g., in the light of new theoretical calculations, where the deep 2.9 eV luminescence band was suggested to be the main optical signature of the substitutional Mg Ga acceptor, thus, having a rather large binding energy and a strong phonon coupling in optical transitions. We present new experimental data on homoepitaxial Mg-doped layers, which together with the previous collection of data give an improved experimental picture of the various luminescence features in Mg-doped GaN. In n-type GaN with moderate Mg doping (<10¹⁸ cm⁻³), the 3.466 eV …

Spectroscopy Studies Of Straincompensated Mid-Infrared Qcl Active Regions On Misoriented Substrates, Gregory Edward Triplett, Justin Grayer, Charles Meyer, Emily Cheng, Denzil Roberts

Electrical and Computer Engineering Publications

In this work, we perform spectroscopic studies of AlGaAs/InGaAs quantum cascade laser structures that demonstrate frequency mixing using strain-compensated active regions. Using a three-quantum well design based on diagonal transitions, we incorporate strain in the active region using single and double well configurations on various surface planes (100) and (111). We observe the influence of piezoelectric properties in molecular beam epitaxy grown structures, where the addition of indium in the GaAs matrix increases the band bending in between injector regions and demonstrates a strong dependence on process conditions that include sample preparation, deposition rates, mole fraction, and enhanced surface diffusion …

Orientation-Dependent Pseudomorphic Growth Of Inas For Use In Lattice-Mismatched Mid-Infrared Photonic Structures, Gregory Edward Triplett, Charles Meyer, Emily Cheng

Electrical and Computer Engineering Publications

In this study, InAs was deposited on GaAs (100) and GaAs (111)B 2 degrees towardssubstrates for the purpose of differentiating the InAs growth mode stemming from strain and then analyzed using in-situ reflection high energy electron diffraction, scanning electron microscopy, Raman spectroscopy, reflectance spectroscopy, and atomic force microscopy. The procession of InAs deposition throughout a range of deposition conditions results in assorted forms of strain relief revealing that, despite lattice mismatch for InAs on GaAs (approximately 7%), InAs does not necessarily result in typical quantum dot/wire formation on (111) surfaces, but instead proceeds two-dimensionally due primarily to the surface orientation.

Mobile Indoor Positioning For Augmented Reality Systems, Robert B. Glass

Theses and Dissertations

This thesis explores the creation and setup of a prototype that allows users of the device to interact within an indoor real world environment and a virtual environment simultaneously using high-tech common technology. The prototype is comprised of a small mobile device such as a cellular mobile phone, Raspberry Pi computer, a battery powered handheld Pico projector, and software developed for the Android OS. The software can easily be ported to other mobile and non-mobile operating systems. The mobile device must contain accelerometer, magnetometer, and gyroscope embedded sensors as well as 802.11 wireless network chip. The prototype software implements an …

Optical Characterization Of Ingan Heterostructures For Blue Light Emitters And Vertical Cavity Lasers: Efficiency And Recombination Dynamics, Serdal Okur

Theses and Dissertations

OPTICAL CHARACTERIZATION OF INGAN HETEROSTRUCTURES FOR BLUE LIGHT EMITTERS AND VERTICAL CAVITY LASERS: EFFICIENCY AND RECOMBINATION DYNAMICS

By Serdal Okur, Ph.D.

A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University.

Virginia Commonwealth University, 2014.

Major Director: Ümit Özgür, Associate Professor, Electrical and Computer Engineering

This thesis explores radiative efficiencies and recombination dynamics in InGaN-based heterostructures and their applications as active regions in blue light emitters and particularly vertical cavities. The investigations focus on understanding the mechanism of efficiency loss at high injection as well as developing designs to mitigate …

Quantum Efficiency Enhancement For Gan Based Light-Emitting Diodes And Vertical Cavity Surface-Emitting Lasers, Fan Zhang

Theses and Dissertations

This thesis explores the improvement of quantum efficiencies for InGaN/GaN heterostructures and their applications in light-emitting diodes (LEDs) and vertical cavity surface-emitting lasers (VCSELs). Different growth approaches and structural designs were investigated to identify and address the major factors limiting the efficiency. (1) Hot electron overflow and asymmetrical electron/hole injection were found to be the dominant reasons for efficiency degradation in nitride LEDs at high injection; (2) delta p-doped InGaN quantum barriers were employed to improve hole concentration inside the active region and therefore improve hole injection without sacrificing the layer quality; (3) InGaN active regions based on InGaN multiple …

Electron – Phonon Interaction In Multiple Channel Gan Based Hfets: Heat Management Optimization, Romualdo A. Ferreyra

Theses and Dissertations

New power applications for managing increasingly higher power levels require that more heat be removed from the power transistor channel. Conventional treatments for heat dissipation do not take into account the conversion of excess electron energy into longitudinal optical (LO) phonons, whose associated heat is stored in the channel unless such LO phonons decay into longitudinal acoustic (LA) phonons via a Ridley path. A two dimensional electron gas (2DEG) density of ~5×10¹²cm^-2 in the channel results in a strong plasmon–LO phonon coupling (resonance) and a minimum LO phonon lifetime is experimentally observed, implying fast heat removal from …

Degradation In Algan/Gan Heterojunction Field Effect Transistors Upon Electrical Stress: Effects Of Field And Temperature, C. Y. Zhu, F. Zhang, Romualdo A. Ferreyra, U. Ozgur, Hadis Morkoç

Electrical and Computer Engineering Publications

AlGaN/GaN heterojunction field effect transistors (HFETs) with 2 μm gate length were subjected to on-state-high-field (high drain bias and drain current) and reverse-gate-bias (no drain currentand reverse gate bias) stress at room and elevated temperatures for up to 10 h. The resulting degradation of the HFETs was studied by direct current and uniquely phase noise before and after stress. A series of drain and gate voltages was applied during the on-state-high-field and reverse-gate-bias stress conditions, respectively, to examine the effect of electric field on degradation of the HFET devices passivated with SiNx. The degradation behaviors under these two types of …