Electrical and Electronics Commons^™

Scalability And Connectivity Challenges For The Future Of Digital Radio Communication, Christopher Bayliss

Honors Program: Senior Projects (Public)

This thesis explores future challenges in digital radio communication, particularly focusing on scalability and connectivity issues that could impede technological advancements. With the increasing production of digital technology and reliance on radio frequencies, there is a need for innovative solutions to overcome limitations in spectrum availability, interference management, and bandwidth constraints. This work evaluates current modulation techniques, spectrum allocation strategies, and advanced communication technologies such as cognitive radio systems and reconfigurable intelligent surfaces. Through a comprehensive literature review and analysis, this thesis identifies promising developments, including dynamic spectrum sharing and symbiotic radio systems, that could significantly enhance spectrum efficiency and …

Dynamic Modeling And Control Of A Solid State Semiconductor-Based Transformer, Microgrid And Storage Systems, Rubén Darío Viñán-Velasco

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

Smart Grids are power grid models designed with the idea of including the growing new technologies, from generation to storage devices, and are a response to the growing demands from consumers and the presence of electronic components being commonplace in the modern devices. The design requires a dynamic alternative in order to build an independent grid that can also work in cooperation with other micro-grids and the power grid in an integrated way. Smart-grids present several advantages over the traditional power grid scheme, but the economic costs of the components required to implement smart-grids is currently a great limitation. This …

Low-Power, Event-Driven System On A Chip For Charge Pulse Processing Applications, Joseph A. Schmitz

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

This dissertation presents an electronic architecture and methodology capable of processing charge pulses generated by a range of sensors, including radiation detectors and tactile synthetic skin. These sensors output a charge signal proportional to the input stimulus, which is processed electronically in both the analog and digital domains. The presented work implements this functionality using an event-driven methodology, which greatly reduces power consumption compared to standard implementations. This enables new application areas that require a long operating time or compact physical dimensions, which would not otherwise be possible. The architecture is designed, fabricated, and tested in the aforementioned applications to …

A Portable, Low Power Radiation Detection And Identification System For High Count Rate, Long Term Monitoring, Samuel J. Murray

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

This dissertation presents the design of a novel radiation detection and identification system that can operate continuously over a period of 8 days while detecting at 30,000 counts per second, consuming a total of 11 mW. The entire system is highly integrated, containing a gamma ray detector, a high voltage detector power supply, and a multichannel analyzer (MCA) system-on-a-chip (SoC), which are all combined into a compact form using a multi-level, configurable printed circuit board design. The MCA SoC, fabricated using a 65 nm CMOS technology, features two enabling resources to allow low power detections at high count rates for …

Low Power Multi-Channel Interface For Charge Based Tactile Sensors, Samuel Hansen

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

Analog front end electronics are designed in 65 nm CMOS technology to process charge pulses arriving from a tactile sensor array. This is accomplished through the use of charge sensitive amplifiers and discrete time filters with tunable clock signals located in each of the analog front ends. Sensors were emulated using Gaussian pulses during simulation. The digital side of the system uses SAR (successive approximation register) ADCs for sampling of the processed sensor signals.

Adviser: Sina Balkır

Low-Noise, Low-Power Analog Front End For Dual Detector, Event-Driven Radioactive Isotope Identification, Joseph Medinger

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

An analog front end (AFE) design for a low-noise, low-power, event-driven radioactive spectroscopy system is implemented in a 65 nm CMOS technology. The AFE is optimized for use with two scintillation based detectors, CsI(Na) and LaBr3(Ce), that utilize photo-multiplier tubes for charge amplification. The amplification within the AFE is accomplished through charge sensitive amplifier designs that are tailored to each detector type. The AFE includes adjustable bias generation circuits to allow amplifier tuning for process, voltage, and temperature variations. The presented AFE is implemented along with analog to digital acquisition circuits and a microcontroller to provide a single-chip radioactive spectroscopy …

Tunable Compact Thz Devices Based On Graphene And Other 2d Material Metasurfaces, Tianjing Guo

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

Since the isolation of graphene in 2004, a large amount of research has been directed at 2D materials and their applications due to their unique characteristics. Compared with the noble metal plasmons in the visible and near-infrared frequencies, graphene can support surface plasmons in the lower frequencies of terahertz (THz) and midinfrared. Especially, the surface conductivity of graphene can be tuned by either chemical doping or electrostatic gating. As a result, the idea of designing graphene metasurfaces is attractive because of its ultra-broadband response and tunability.

It has been demonstrated theoretically and experimentally that the third-order nonlinearity of graphene at …

Research Tools And Their Uses For Determining The Thermal Inactivation Kinetics Of Salmonella In Low-Moisture Foods, Soon Kiat Lau

Department of Food Science and Technology: Dissertations, Theses, and Student Research

The reputation of low-moisture foods as safe foods has been crumbling over the past decade due to repeated involvement in foodborne illness outbreaks. Although various pasteurization technologies exist, a majority are thermal processes and have not been well-characterized for pasteurizing low-moisture foods. In addition, the nature of a low-moisture food matrix introduces various experimental complications that are not encountered in high-moisture foods. In this dissertation, the development, building instructions, and characterization of various open source tools for studying the inactivation kinetics of microorganisms in low-moisture foods are described. The first tool is the TDT Sandwich, a dry heating device for …

Cmos Radioactive Isotope Identification With Multichannel Analyzer And Embedded Neural Network, Samuel Murray

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

A radiation detection and identification system is designed and implemented to perform gamma ray spectroscopy on radioactive sources and identify which isotopes are present in the sources. A multichannel analyzer is implemented on an ASIC to process the signal produced from gamma rays detected by a scintillator and photomultiplier tube and to quantize the gamma ray energies to build a histogram. A fast, low memory embedded neural network is implemented on a microcontroller ASIC to identify the isotopes present in the gamma ray histogram produced by the multichannel analyzer in real time.

Advisors: Sina Balkir and Michael W. Hoffman

Harmonics Elimination In Three Phase Cascade H-Bridge Multilevel Inverter Using Virtual Stage Pwm, Amro Quedan

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

The multilevel inverters are one of the great solutions that are proposed to satisfy the demand for high-power application and the significant integration of renewable energy. The conversion process from DC to AC must be done at high efficiency to decrease the energy loss and to ensure the electric grid power quality. The Total Harmonic Distortion (THD) is the most important feature that indicates the efficiency of the conversion process. In this research, due to the advantages of the cascade H-bridge inverter over other topologies, it has been used with the virtual stage PWM technique to investigate two different methods …

Femtosecond Laser Micromachining Of Low-Temperature Co-Fired Ceramic And Glass Fiber Reinforced Polymer Printed Circuit Boards Materials, Raif Farkouh

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

Low-temperature co-fired ceramic (LTCC), and glass fiber reinforced polymer (GFRP) printed circuit boards (PCBs) are two materials used for the packaging of electronics. The excellent mechanical and electrical properties of LTCC, combined with the ability to embed passive components offer superior radio frequency (RF) performance and device miniaturization for high-frequency applications. Due to its unique properties, LTCC provides superior performance in applications as diverse as military radar, imaging systems, advanced automotive sensing, telecommunications, and satellites. The use of LTCC in these applications has created a demand for the micromachining of holes, channels, and cavities with specific geometries and structures. Likewise, …

Event And Time-Triggered Control Module Layers For Individual Robot Control Architectures Of Unmanned Agricultural Ground Vehicles, Tyler Troyer

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Automation in the agriculture sector has increased to an extent where the accompanying methods for unmanned field management are becoming more economically viable. This manifests in the industry’s recent presentation of conceptual cab-less machines that perform all field operations under the high-level task control of a single remote operator. A dramatic change in the overall workflow for field tasks that historically assumed the presence of a human in the immediate vicinity of the work is predicted. This shift in the entire approach to farm machinery work provides producers increased control and productivity over high-level tasks and less distraction from operating …

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 …

Real-Time Internal Temperature Estimation And Health Monitoring For Igbt Modules, Ze Wang

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

Field experiences have demonstrated that power semiconductor devices, such as insulated-gate bipolar transistors (IGBTs), are among the most fragile components of power electronic converters. Thermomechanical stresses produced by temperature variations during operational and environmental loads are the major causes of IGBT degradation. As the devices are often operated under complex working conditions, temperature variations and the associated damage are difficult to predict during the converter design stage. A promising approach—online health monitoring and prognosis for power semiconductor devices—that can avoid device failure and effectively schedule maintenance has attracted much interest.

This dissertation research focused on real-time accurate internal temperature estimation …

Design And Implementation Of Reconfigurable Patch Antennas For Wireless Communications, Fei He

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

Reconfigurable patch antennas have drawn a lot of research interest for future wireless communication systems due to their ability to adapt to changes of environmental conditions or system requirements. The features of reconfigurable patch antennas, such as enhanced bandwidths, operating frequencies, polarizations, radiation patterns, etc., enables accommodation of multiple wireless services.

The major objective of this study was to design, fabricate and test two kinds of novel reconfigurable antennas: a dual-frequency antenna array with multiple pattern reconfigurabilities, and a pattern and frequency reconfigurable Yagi-Uda patch antenna. Comprehensive parametric studies were carried out to determine how to design these proposed patch …

Comparing Various Hardware/Software Solutions And Conversion Methods For Controller Area Network (Can) Bus Data Collection, Samuel E. Marx, Joe D. Luck, Santosh Pitla, Roger M. Hoy

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Various hardware and software solutions exist for collecting Controller Area Network (CAN) bus data. Digital data accuracy could vary based upon different data logging methods (e.g., hardware/software timing, processor timing, etc.). CAN bus data were collected from agricultural tractors using multiple data acquisition solutions to quantify differences among collection methods and demonstrate potential data accumulation rates. Two types of data were observed for this study. The first, CAN bus frame data, represents data collected for each line of hex data sent from an ECU. One issue with frame data is the resulting large file sizes, therefore a second logging format …

Design Optimization Of A Linear Generator With Dual Halbach Array For Human Motion Energy Harvesting, Wenjia Zhao

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

A linear generator for human motion energy harvesting is designed and optimized in this study. The linear generator can be used to convert human motion energy to electrical energy to charge portable electronics, such as cellular phones, wireless internet devices, etc. The use of dual Halbach magnet arrays in the proposed generator provides a significant improvement in power density. Different dual Halbach arrays were studied, and a novel Halbach array with nonuniform magnet blocks is proposed to enhance the air-gap flux density in the linear generator for a given size and weight of permanent magnet material. Sensitivity analyses were performed …

A Stand-Alone Dna Hybridization Detection System, Sinan S. Sayood

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

The goal of this project was to design a portable device that can quickly and accurately detect the difference between single and double stranded DNA. This was accomplished by analyzing the capacitive properties of DNA solutions and implementing a charge-based capacitive monitoring system to detect and analyze the solutions. The detection system was designed without reliance on expensive functionalized electrodes, and instead is able to detect the properties of free- oating DNA. This approach greatly reduces the cost of the materials needed to construct the device. It also decouples the main sensor apparatus from the bulk of the electronics, reducing …

Low-Power Analog Processing, Daniel J. White

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

This dissertation presents the analog harmonic transform (AHT) and a first implementation in an integrated circuit. The transform is designed for a regular and simple hardware structure. It provides coefficients relating to an input signal's spectrum. These coefficients also have a simple relationship to the signal's Fouri\'er series coefficients.

The AHT is defined in its ideal form and evaluated for two example signal classification applications. Both military vehicle and bearing fault classification tasks are presented which validate the ability of a neural network to use the AHT coefficients to correctly classify the input signals. Because any real use of the …

A Low-Power Compact Nuclear Quadrupole Resonance (Nqr) Based Explosive Detection System, Xinwang Zhang

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

Abandoned landmines and terrorist bomb attacks are severe issues threatening our society. These issues necessitate the development of prompt and accurate explosive detection systems. The detection mechanisms commonly-used nowadays usually search for explosive containers, which suffer numerous false alarms caused by external detection circumstance changes. Alternatively, explosive substances inside the bombs and landmines can be detected by means of biology, chemistry and physics techniques. Nuclear Quadrupole Resonance (NQR) detection technology has proven to be a highly effective solution for detecting explosives unambiguously.

In this work, a portable NQR-based explosive detection system that employs state-of-the-art semiconductor technologies is presented. This system …

Uv Laser-Assisted Diamond Deposition, Mengxiao Wang

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

Diamond, due to its unique properties, has been studied for decades. Many diamond synthesis methods have been developed as well. As one of the synthesis methods, combustion flame chemical vapor deposition (CVD) is considered as the most flexible way. Combined with laser irradiation, laser-assisted combustion flame CVD can enhance the deposition process of diamond films. In this thesis work, efforts were made to explore the capability of a laser-assisted combustion flame CVD technique with krypton fluoride (KrF) excimer laser irradiation for improving diamond thin film quality and deposition rate. The research efforts mainly focus on following activities, including: 1) studying …

Security Analysis Of Phasor Measurement Units In Smart Grid Communication Infrastructures, Mehrnaz Sharifian

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

Phasor Measurement Units (PMUs), or synchrophasors, are rapidly being deployed in the smart grid with the goal of measuring phasor quantities concurrently from wide area distribution substations. By utilizing GPS receivers, PMUs can take a wide area snapshot of power systems. Thus, the possibility of blackouts in the smart grid, the next generation power grid, will be reduced. As the main enabler of Wide Area Measurement Systems (WAMS), PMUs transmit measured values to Phasor Data Concentrators (PDCs) by the synchrophasor standard IEEE C37.118. IEC 61850 and IEC 62351 are the communication protocols for the substation automation system and the security …

Theoretical Modeling Of Laser-Induced Absorption Phenomena In Optical Materials, Chris Ferris

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

For over five decades, laser-induced damage and breakdown in optical materials has been an active field of research. As laser systems continually advance, new opportunities to study laser/material interactions arise. This thesis begins by presenting the damage mechanisms and absorption phenomena that lead to laser-induced breakdown. An in depth understanding of these processes led to the development of rate equations that describe electron density growth in a material exposed to a strong electromagnetic wave. These rate equations laid the foundation for the construction of a theoretical model. By using variable laser and material parameter inputs, the model calculates the laser-induced …

Position/Speed Sensorless Control For Permanent-Magnet Synchronous Machines, Yue Zhao

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

Permanent-magnet synchronous machines (PMSMs) are widely used in industrial applications owing to their distinctive advantages, such as high efficiency, high power density, and wide constant power region. To achieve high-performance field oriented control, accurate rotor position information, which is usually measured by rotary encoders or resolvers, is indispensable. However, the use of these sensors increases the cost, size, weight, and wiring complexity and reduces the mechanical robustness and the reliability of the overall PMSM drive systems. The goal of the research for this dissertation was to develop a rotor position/speed sensorless control system with performance comparable to the sensor-based control …

Physical Design Of A Smart Camera With Integrated Digital Pixel Sensors Using A 0.13Μm 8-Layer Metal Cmos Process, Mahir K. Gharzai

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

The design of cameras has historically kept imagery and computational circuitry isolated in an attempt to maximize image quality by improving pixel pitch and routing density. Although this technique has worked in creating high density arrays of pixels for large resolution imagers, it has never been able to achieve high framerate computational operations.

A radical approach is introduced to solve this dilemma by creating compact, low- power pixel elements with built-in analog-to-digital converters that directly interface with digital logic. These pixels are capable of integrating alongside logic cells and to create an array of pixels inside the processor that can …

Fea Estimation And Experimental Validation Of Solid Rotor And Magnet Eddy Current Loss In Single-Sided Axial Flux Permanent Magnet Machines, Xu Yang

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

The rotor and magnet loss in single-sided axial ux permanent magnet (AFPM) machines with non-overlapped windings is studied in this dissertation. Finite element analysis (FEA) estimations of the loss are carried out using both 2D and 3D modeling. The rotor and magnet losses are determined separately for stator slot passing and MMF space harmonics from currents in the stator. The segregation of loss between the solid rotor plate and the magnet is addressed. The eddy current loss reduction by magnet segmentation is discussed as well. Two prototype 24 slot/22 pole single-sided AFPMs, fabricated with both single layer (SL) and double …

Elec 2110: Elements Of Electrical Engineering—A Peer Review Of Teaching Project Benchmark Portfolio, Mahmoud Alahmad

UNL Faculty Course Portfolios

I have been teaching this class for the last five years. As an introductory course to electrical engineering, there is a lot of material that needs to be covered. All the material is important and relevant, and I try to go in-depth in each topic area. This approach has resulted in overwhelming the students and made them struggle with the course content, application and utilization. As I consider this course for the peer review, I am evaluating the depth of each topic and the opportunity to adjust the approach and method used to introduce new concepts and at the same …

Online Nonintrusive Condition Monitoring And Fault Detection For Wind Turbines, Xiang Gong

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

The goal of this dissertation research is to develop online nonintrusive condition monitoring and fault detection methods for wind turbine generators (WTGs). The proposed methods use only the current measurements that have already been used by the control and protection systems of WTGs; no additional sensors or data acquisition devices are needed. Current-based condition monitoring and fault detection techniques have great economic benefits and the potential to be adopted by the wind energy industry. However, there are challenges in using current measurements for wind turbine condition monitoring and fault detection. First, it is a challenge to extract WTG fault signatures …

Conductive Concrete For Electromagnetic Shielding – Methods For Development And Evaluation, Aaron P. Krause

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

This research investigates the development and evaluation innovative methods for the use of conductive concrete as an electromagnetic shield. New testing methods are developed to determine the best conductive components to use in the design of a concrete mixture for shielding that shows the best promise. The conductive concrete mixture has the potential to provide electromagnetic shielding that is cost-effective in terms of construction, operation, and maintenance compared to conventional approaches. Two testing methods, Small Sample Testing and Large Slab Testing, are developed based on standardized testing methods that have been modified for the testing of conductive concrete mixtures. As …

Fiber-Tip Fabry–Perot Interferometric Sensor Based On A Thin Silver Film, Fawen Guo

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

Fiber-optic sensors have many advantages, including small size, light weight, immunity to electromagnetic interference, and the capability of remote sensing. Fiber- tip sensors are fabricated on a fiber tip and are the smallest type of fiber-optic sensor. The fiber-tip sensors have attracted a great deal of attention in past years for pressure, temperature, and acoustic sensing.

In this thesis, a fiber-tip sensor based on an ultra-thin silver film was proposed and demonstrated for highly sensitive and high frequency ultrasonic detection. The film is prepared by the vacuum thermal deposition method and then transferred to the fiber tip. The sensor has …