Engineering Commons^™

Humidity Sensor Circuit Using Real Time Operating System (Freertos) Kernel, Bojie Chen

Theses and Dissertations--Electrical and Computer Engineering

A humidity sensor can be used to measure the moisture content of the environment. The physical change of the sensor expresses as the change of electrical property like capacitance, resistance, voltage, current, frequency, etc. In order to process these analog signals digitally, microprocessor is involved in the measurement. This thesis presents design of a circuit to measure low moisture levels. The 16-bit RISC mixed signal microcontroller MSP430F249 from Texas Instruments will be used. The circuit has good performance at extremely low humidity levels.

Meanwhile, a small real time operating system kernel FreeRTOS, a market leading RTOS from Real Time Engineer …

A New Design Of Dc-Dc Converter For Capacitive Deionization Process, Zhiao Li

Theses and Dissertations--Electrical and Computer Engineering

The shortage of clean water has become a significant global problem, and capacitive deionization (CDI) is a technology that can be used to help relieve the problem. A Ćuk converter system that can recover energy from CDI cells is described. This converter transfers energy between two CDI cells when a cell is in its desorption period, allowing energy that would otherwise be lost to be recovered and improving overall system efficiency. In order to control the states of the MOSFET switches in the converter, a self boost charge pump is used. In this way, the microcontroller can control system duty …

A Multi-Physics Computational Approach To Simulating Thz Photoconductive Antennas With Comparison To Measured Data And Fabrication Of Samples, Darren Ray Boyd

Theses and Dissertations--Electrical and Computer Engineering

The frequency demands of radiating systems are moving into the terahertz band with potential applications that include sensing, imaging, and extremely broadband communication. One commonly used method for generating and detecting terahertz waves is to excite a voltage-biased photoconductive antenna with an extremely short laser pulse. The pulsed laser generates charge carriers in a photoconductive substrate which are swept onto the metallic antenna traces to produce an electric current that radiates or detects a terahertz band signal. Therefore, analysis of a photoconductive antenna requires simultaneous solutions of both semiconductor physics equations (including drift-diffusion and continuity relations) and Maxwell’s equations. A …

Coordinated Voltage And Reactive Power Control Of Power Distribution Systems With Distributed Generation, Esa A. Paaso

Theses and Dissertations--Electrical and Computer Engineering

Distribution system voltage and VAR control (VVC) is a technique that combines conservation voltage reduction and reactive power compensation to operate a distribution system at its optimal conditions. Coordinated VVC can provide major economic benefits for distribution utilities. Incorporating distributed generation (DG) to VVC can improve the system efficiency and reliability. The first part of this dissertation introduces a direct optimization formulation for VVC with DG. The control is formulated as a mixed integer non-linear programming (MINLP) problem. The formulation is based on a three-phase power flow with accurate component models. The VVC problem is solved with a state of …

Toward Polymer Coating With Easy Ice Release, Chenyu Wang

Theses and Dissertations

Minimizing adhesion of ice has been the subject of extensive studies for applications such aircraft wings, wind turbine blades spacecraft, power transmission wires, while a growing interest concerns coatings for aerospace applications. The work described here describes progress for coatings and ice release test method development over the last few years. Major achievements include: (1) New Rigid Adherent-Resistant Elastomers (RARE), (2) A new Epoxied Cylinder (EC) adhesion test, (3) Validation of an ice release test, and (4) Study of ice adhesion strength on coating thickness for a PDMS elastomer. Rigid Adhesion-Resistance Elastomers (RARE) are comprised of 3F 1 terminated with …

Dynamic Aspects Of Articulating With A Virtual Vocal Tract In Dysarthria, Jeffrey J. Berry, Cassandra North, Michael T. Johnson

Speech Pathology and Audiology Faculty Research and Publications

No abstract provided.

Full Wave Electromagnetic Simulations Of Terahertz Wire Grid Polarizers And Infrared Plasmonic Wire Gratings, John Cetnar

Browse all Theses and Dissertations

This dissertation is a study of the interaction of terahertz (THz) and long-wave infrared (LWIR) radiation with various periodic sub-wavelength metallic structures in free-space and on dielectric substrates. There are many new and useful applications for both THz and LWIR radiation. Unfortunately, heavy attenuation by the Earth's atmosphere and low output power from THz sources combine to make THz radiation weak and difficult to detect. LWIR is not as prone to atmospheric attenuation as THz radiation. Nevertheless, the detection of LWIR can be improved upon by strengthening the coupling between incoming radiation and LWIR detector systems.

Light passing through periodic …

Validation Studies Of Sc/Tetra Code In 2d And 3d Simulations, Shuo Mao

Browse all Theses and Dissertations

In this thesis, 2D CFD simulations, 3D CFD simulations, and one 2D Fluid-Structure Interaction (FSI) problem were investigated using combined CFD and an FEA (Finite Element Analysis) tool. Discussions focused on turbulence models, mesh sizes, prism layer sizes, under-relaxation-factor, etc. The solution of CFD simulation and FSI simulation was validated using the results of previous CFD solvers and experimental data presented in the literature. The SST model results for the 2D mixing layer, 2D airfoil near-weak, axisymmetric subsonic jet, and 2D convex curvature boundary layer studies agree with previous CFD results within a 1% error. The k-e model with wall …

Peroxisome Proliferator-Activated Receptor Alpha: Insight Into The Structure, Function And Energy Homeostasis, Dhawal P. Oswal

Browse all Theses and Dissertations

Peroxisome proliferator-activated receptor alpha (PPAR alpha) belongs to the family of ligand-activated nuclear transcription factors and serves as a lipid sensor to regulate nutrient metabolism and energy homeostasis. The transcriptional activity of PPAR alpha is thought to be regulated by the binding of exogenous ligands (example, fenofibrate, TriCor), as well as endogenous ligands including fatty acids and their derivatives. Although long-chain fatty acids (LCFA) and their thioesters (long-chain fatty acyl-CoA; LCFA-CoA) have been shown to activate PPAR alpha of several species, the true identity of high-affinity endogenous ligands for human PPAR alpha (hPPAR alpha) has been more elusive. This two …

Autonomous Capabilities For Small Unmanned Aerial Systems Conducting Radiological Response: Findings From A High-Fidelity Discovery Experiment, Brittany Duncan, Robin Murphy

School of Computing: Faculty Publications

This article presents a preliminary work domain theory and identifies autonomous vehicle, navigational, and mission capabilities and challenges for small unmanned aerial systems (SUASs) responding to a radiological disaster. Radiological events are representative of applications that involve flying at low altitudes and close proximities to structures. To more formally understand the guidance and control demands, the environment in which the SUAS has to function, and the expected missions, tasks, and strategies to respond to an incident, a discovery experiment was performed in 2013. The experiment placed a radiological source emitting at 10 times background radiation in the simulated collapse of …

Yeast Pheromone Pathway Modeling Using Petri Nets, Stephen D. Scott, Abhishek Majumdar, Jitender S. Deogun, Steven D. Harris

School of Computing: Conference and Workshop Papers

Background: Our environment is composed of biological components of varying magnitude. The relationships between the different biological elements can be represented as a biological network. The process of mating in S. cerevisiae is initiated by secretion of pheromone by one of the cells. Our interest lies in one particular question: how does a cell dynamically adapt the pathway to continue mating under severe environmental changes or under mutation (which might result in the loss of functionality of some proteins known to participate in the pheromone pathway). Our work attempts to answer this question. To achieve this, we first propose a …

A Comparison Of A Campus Cluster And Open Science Grid Platforms For Protein- Guided Assembly Using Pegasus Workflow Management System, Natasha Pavlovikj, Kevin Begcy, Sairam Behera, Malachy Campbell, Harkamal Walia, Jitender S. Deogun

School of Computing: Conference and Workshop Papers

Scientific workflows are a useful tool for managing large and complex computational tasks. Due to its intensive resource requirements, the scientific workflows are often executed on distributed platforms, including campus clusters, grids and clouds. In this paper we build a scientific workflow for blast2cap3, the protein-guided assembly, using the Pegasus Workflow Management System (Pegasus WMS). The modularity of blast2cap3 allows us to decompose the existing serial approach on multiple tasks, some of which can be run in parallel. Afterwards, this workflow is deployed on two distributed execution platforms: Sandhills, the University of Nebraska Campus Cluster, and the Open Science …

Transforming Web Tables To A Relational Database, David W. Embley, George Nagy, Sharad C. Seth

School of Computing: Conference and Workshop Papers

HTML tables represent a significant fraction of web data. The often complex headers of such tables are determined accurately using their indexing property. Isolated headers are factored to extract category hierarchies. Web tables are then transformed into a canonical form and imported into a relational database. The proposed processing allows for the formulation of arbitrary SQL queries over the collection of induced relational tables.

Daily Area Of Snow Melt Onset On Arctic Sea Ice From Passive Microwave Satellite Observations 1979–2012, Angela C. Bliss, Mark R. Anderson

Department of Earth and Atmospheric Sciences: Faculty Publications

Variability in snow melt onset (MO) on Arctic sea ice since 1979 is examined by determining the area of sea ice experiencing the onset of melting during the melt season on a daily basis. The daily MO area of the snow and ice surface is determined from passive microwave satellite-derived MO dates for the Arctic Ocean and sub-regions. Annual accumulations of MO area are determined by summing the time series of daily MO area through the melt season. Daily areas and annual accumulations of MO area highlight inter-annual and regional variability in the timing of MO area, which is sensitive …

A Ga-Svm Hybrid Classifier For Multiclass Fault Identification Of Drivetrain Gearboxes, Dingguo Lu, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

This paper presents a genetic algorithm (GA)- support vector machine (SVM) hybrid classifier for multiclass fault identification of drivetrain gearboxes in variable-speed operational conditions. An adaptive feature extraction algorithm is employed to effectively extract the features of gearbox faults from the stator current signal of an AC machine connected to the gearbox. The multiclass GA-SVM classifier is used to identify the faults in the gearbox according to the fault features extracted. A GA is designed to find the optimal parameters of the SVM to obtain the best classification accuracy. The proposed hybrid classifier is validated on a gearbox connected with …

Optimal Energy Scheduling For A Smart Entity, Amin Fakhrazari, Hamid Vakilzadian, F. Fred Choobineh

Department of Electrical and Computer Engineering: Faculty Publications

Real-time availability of electricity prices via a smart power grid has a potential bilateral benefit to electricity users and suppliers. The users can reduce their costs by consuming energy during low-price hours and balancing their energy usage during other hours. This in turn benefits energy utility companies by reducing their peak power demand. This article describes an optimal shrinking horizon model for electricity-consuming units based on user preferences. The proposed model optimizes the end user’s electricity cost while meeting preferred comfort levels. The user can set preferences in the model using a tristate flexibility parameter for each electric-power-consuming unit. The …

A Security Protocol For Advanced Metering Infrastructure In Smart Grid, Feng Ye, Yi Qian, Rose Qingyang Hu

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, we propose a security protocol for advanced metering infrastructure (AMI) in smart grid. AMI is one of the important components in smart grid and it suffers from various vulnerabilities due to its uniqueness compared with wired networks and traditional wireless mesh networks. Our proposed security protocol for AMI includes initial authentication, secure uplink data aggregation/recovery, and secure downlink data transmission. Compared with existing researches in such area, our proposed security protocol let the customers be treated fairly, the privacy of customers be protected, and the control messages from the service provider be delivered safely and timely.

Free Space Optical Data Center Architecture Design With Fully Connected Racks, Abdelbaset S. Hamza, Jitender S. Deogun, Dennis R. Alexander

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, we propose a novel design of a data center (DC) using free space optical (FSO) technology. The proposed FSO-DC design is based on fixed, non-mechanical, FSO links facilitating the realization of fully connected FSO racks and rows/columns of racks. Each rack becomes a point of intersection of three fully connected sub-networks. We investigate requirements, advantages and challenges of the proposed design. We develop and analyze a switch-free, fully connected FSO rack, present its link budget analysis and validate it by simulation. Results establish the feasibility of a switch-free FSO rack based on the proposed FSO-DC design. A …

Enhanced Pool-Boiling Heat Transfer And Critical Heat Flux Using Femtosecond Laser Surface Processing, Corey M. Kruse, Troy P. Anderson, Chris Wilson, Craig A. Zuhlke, Dennis R. Alexander, George Gogos, Sidy Ndao

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, we present the experimental investigation of pool boiling heat transfer on multiscale (micro/nano) functionalized metallic surfaces. The multiscale structures were fabricated via a femtosecond laser surface process (FLSP) technique which forms mound-like microstructures covered by layers of nanoparticles. Using a pool boiling experimental setup with deionized water as the working fluid, both the heat transfer coefficient and critical heat flux were investigated. The polished reference sample was found to have a critical heat flux of 91 W/cm² at 40 °C of superheat and a maximum heat transfer coefficient of 23,000 W/m²-K. The processed sample …

Fault Diagnosis For Drivetrain Gearboxes Using Pso-Optimized Multiclass Svm Classifier, Dingguo Lu, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

A novel method consisting of an adaptive feature extraction scheme and a particle swarm optimization (PSO)- optimized multiclass support vector machine (SVM) classifier is proposed for condition monitoring and fault diagnosis of drivetrain gearboxes in variable-speed operational conditions. The adaptive feature extraction scheme consists of an adaptive signal resampling algorithm, a frequency tracker, and a feature generation algorithm for effective extraction of the features of gearbox faults from the stator current signal of the AC electric machine connected to the gearbox. The multiclass SVM classifier is designed to identify different faults in the gearbox according to the fault features extracted. …

Characterizing The Rf Performance Of The Ez430-Chronos Wrist Watch, Francisco J. Mora-Becerra, Pedro Sathler, Jay D. Carlson, Eric T. Psota, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

The Texas Instruments eZ430-Chronos development kit is a popular wireless platform for researchers, commercial developers, and hobbyists. Built into the form factor of a standard wrist watch, the Chronos is ideal for wireless body area networks (WBANs), indoor localization, and activity detection. Many of these applications requires knowledge of the RF performance of the platform, which has never been characterized by Texas Instruments nor any third parties. Here, we provide experimental data characterizing the RF performance of the eZ430-Chronos watch in various configurations, including when worn by a person while sitting, standing, and reaching. The RF performance of the Chronos …

Steganography Attack Based On Discrete Spring Transform And Image Geometrization, Qilin Qi, Aaron Sharp, Yaoqing Lamar Yang, Dongming Peng, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications

In order to prevent harmful secret information sharing by steganography, a new active-warden countermeasure approach against steganography is proposed in this paper. Differently from the other countermeasure approaches presented in current literature which need to have some knowledge of the steganographic algorithms to be attacked, our proposed method is a generic method which is independent of any particular steganography methods being utilized. In other words, our approach blindly attacks the steganography without any prior knowledge of the used algorithms or their existence. In general, the hidden information is embedded in a carrier by adjusting the coefficients of the audio or …

Study On Case Temperature Distribution For Condition Monitoring Of Multidie Igbt Modules, Bo Tian, Ze Wang, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

The parasitic and proximity effects in multidie insulated-gate bipolar transistor (IGBT) modules lead to nonuniform distributions of junction temperature (T_J) and case temperature (T_C) among different dies. This feature can be used to monitor the operating and health condition of multidie IGBT modules. This paper reports a comprehensive study on the distribution of T_C and its influence on T_J estimation using a thermal network model for a multidie IGBT module before and after aging. Specifically, experimental studies using accelerated aging tests are conducted for a 9-die IGBT module. Results demonstrate that the …

Modeling Molecular Communications At Nano-Scale With Applications In Medicine And Microbiology, Tadeusz A. Wysocki

Department of Electrical and Computer Engineering: Faculty Publications

No abstract provided.

An Isolated Multiport Bidirectional Dc-Dc Converter For Pv-Battery-Dc Microgrid Applications, Jianwu Zeng, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a new isolated, multiport, bidirectional DC-DC converter with the least number of switches for photovoltaic (PV)-battery-DC microgrid applications. The proposed converter is able to perform the maximum power point tracking (MPPT) control for the PV system when solar energy is available as well as control the charge and discharge of the battery with the PV system and the DC microgrid. Simulation and experimental studies are carried out and validate the proposed converter for simultaneous power management of a PV-battery system connected to a DC microgrid.

A Low-Power Compact Nqr Based Explosive Detection System, Xinwang Zhang, Nathan Schemm, Sina Balkır, Michael W. Hoffman

Department of Electrical and Computer Engineering: Faculty Publications

Nuclear quadruple resonance (NQR) has been studied for explosive detection for years. Some prototype NQR-based detection systems have been reported, but were all designed from the laboratory perspective, with bulky sizes and high power consumption. To achieve a portable NQR-based detection system for field applications, a low-power compact system utilizing state-of-the-art semiconductor technologies is presented in this paper. Several novel circuits for the key modules are proposed, including a Class-D type power amplifier, a power multiplexing and matching network, a customized IC with integrated analog signal processing chain, and a microcontroller-based logic control unit. An advanced digital signal processor platform …

A Sliding-Mode Duty-Ratio Controller For Dc/Dc Buck Converters With Constant Power Loads, Yue Zhao, Wei Qiao, Daihyun Ha

Department of Electrical and Computer Engineering: Faculty Publications

Incorporating a medium-voltage dc (MVDC) integrated power system is a goal for future surface combatants and submarines. In an MVDC shipboard power system, dc/dc converters are commonly employed to supply constant power to electric loads. These constant power loads have a characteristic of negative incremental impedance, which may cause system instability during disturbances if the system is not properly controlled. This paper proposes a sliding-mode duty-ratio controller (SMDC) for dc/dc buck converters with constant power loads. The proposed SMDC is able to stabilize the dc power systems over the entire operating range in the presence of significant variations in the …

A Comparison Between Uwb And Tdoa Systems For Smart Space Localization, Lianlin Zhao, Eric T. Psota, Lance C. Pérez

Department of Electrical and Computer Engineering: Faculty Publications

A comparison between two different systems for smart space localization is presented. A smart space implemented at the University of Nebraska-Lincoln was designed for automated and intelligent assistance for elderly and disabled people, and also for astronauts in space. Localization is a critical component of the smart space since it provides the system with the movement patterns and location of its inhabitants. Two systems have been deployed and evaluated for the purpose of localizing people in the smart space: the Ubisense ultra-wide band (UWB) system and the Cricket indoor localization system. Both systems support three-dimensional localization within the smart space. …

Simulation Supported Estimation Of End-To-End Transmission Parameters In Non-Viral Gene Delivery, Beata Wysocki, Timothy M. Martin, Tadeusz A. Wysocki, Angela K. Pannier

Department of Electrical and Computer Engineering: Faculty Publications

Communications, in general, involve delivery of information from a source to a sink. At nano-scale, an example of a man-made communications involving interfacing with biological systems at intra-cellular level is non-viral gene delivery. From a telecommunications engineering perspective, important end-to-end parameters of such a system are: the endto- end delay, system capacity, and packet loss rate. There are neither known methods to estimate those parameters theoretically nor they are ready available from standard measurements. The paper provides estimates for those parameters based on the simulation of non-viral gene delivery system based on the queuing theory. The simulator used has bee

Whole Genome Sequence Of A Turkish Individual, Haluk Dogan, Handan Can, Hasan H. Otu

Department of Electrical and Computer Engineering: Faculty Publications

Although whole human genome sequencing can be done with readily available technical and financial resources, the need for detailed analyses of genomes of certain populations still exists. Here we present, for the first time, sequencing and analysis of a Turkish human genome. We have performed 35x coverage using paired-end sequencing, where over 95% of sequencing reads are mapped to the reference genome covering more than 99% of the bases. The assembly of unmapped reads rendered 11,654 contigs, 2,168 of which did not reveal any homology to known sequences, resulting in,1 Mbp of unmapped sequence. Single nucleotide polymorphism (SNP) discovery resulted …