Engineering Commons^™

Nonthermal Plasma Jet Efficacy On Candida Kefyr, Amber Marie Mattson Jackson

Electrical & Computer Engineering Theses & Dissertations

The inactivation abilities of a nonthermal plasma jet were investigated with the yeast C. kefyr, a pathogen with increasing importance in healthcare. The plasma is generated using a microhollow cathode discharge (MHCD) geometry operated with a DC voltage of 2 kV and a current of 30 mA using air as the operating gas at an airflow rate of 8 SLM. The plasma discharge approaches room temperature at a few mm away from the plasma jet allowing for the use on heat sensitive surfaces. Dry air and humid air were used as the operating gas to see if humidity plays …

Modeling Leakage Currents In Metal Insulator Metal Structures With High K Materials, Priyamvada Maleeswaran

Electrical & Computer Engineering Theses & Dissertations

Various products such as personal computers, cellular phones and mobile devices require high speed and low power consumption. Such improvements have been attained by minimizing physical dimensions of electronic devices, leading to high density integration of transistors and capacitors on integrated chips (]Cs). However, as a consequence of down-scaling device dimensions, tunneling of electrons through thin gate oxides (SiO₂) increases, leading to increased static power leakage. This constitutes wastage in power, and for the case of memory applications necessitates faster refresh cycles. In order to overcome such issues, high-k materials (such as HfO₂ and ZrO₂) …

Configuration Studies Of Electrostatic And Magnetostatic Active Space Radiation Shielding, Trac K. Nguyen

Electrical & Computer Engineering Theses & Dissertations

Developing successful and optimal solutions for mitigating the hazards of radiation in deep space is critical for the success of deep-space long duration explorations, including mission to the Moon, Mars and beyond. A recent report (Tripathi et al., 2008) had explored the feasibility of using electrostatic shielding in conjunction with state-of-the-art materials shielding technologies.

In this thesis research, we study the active electrostatic shielding strategy and examine a hybrid configuration that utilizes both electrostatic and magnetostatic fields. The main advantages of this system are shown to be: (i) much lower magnetic fields that could be below the thresholds set for …

Subnanosecond Exposure Systems For Biological Studies, Jongbong Nah

Electrical & Computer Engineering Theses & Dissertations

The research of bioelectrics has expanded to subnanosecond pulse region and entered a new domain of biophysics of cell interaction with ultra-short and intense electric fields. As subnanosecond pulses may be delivered by antennas to the human body and is very attractive to the medical community, the study of subnanosecond pulse effects calls for exposure systems for both cells and tissues. Two systems were designed in the scope of this thesis, used for cells and tissues respectively. The exposure system designed for cell exposure is a cuvette consisting of two parallel aluminum gaps. This cuvette is placed in a coaxial …

Fault Detection System For Solar Tracking Applications, Hareen Sekhar Illa

Electrical & Computer Engineering Theses & Dissertations

Oil, coal and natural gas reserves are being depleted faster than forecasted due to continued increase in demand for energy sources. We need, therefore, to develop renewable energy sources, such as solar, wind, biomass, geothermal, hydro power and tidal energy. In spite of having very high potential, harvesting solar energy has been a challenge because of the relatively low efficiency of solar cells. In the past few years different methods have been developed to increase the efficiency of the photovoltaic (PV) system: (I) improve the efficiency of solar cells (ill use a solar tracking system to increase the received solar …

Diamond This Film Patterning Technique Using Selective Nucleation Growth, Characterization And Application, Weican Xiao

Electrical & Computer Engineering Theses & Dissertations

Diamond is the hardest bulk material with the highest thermal conductivity. It is also an excellent wide band gap material; hence, diamond is suitable for electronic, mechanical and biological applications. Unfortunately, natural diamond is prohibitively expensive for most technological applications. Polycrystalline diamond, with properties close to those of natural diamond, has been synthesized since the 1950s. Among many methods employed for diamond thin film synthesis, chemical vapor deposition (CVD) using microwave plasma (MW) is quite popular for several reasons. Well-confined plasma that does not touch the reaction chamber walls can be produced directly on the substrate. Hence, contamination in the …

Dynamics Of Non-Thermal Plasma Jets Under Variable Pressure, Mehmet Arda Akman

Electrical & Computer Engineering Theses & Dissertations

Non-thermal plasma (NTP) jets driven by short DC pulses have attracted the attention of researchers within the past decade due to their promising bio-medical applications in the fields of wound healing, cancer treatment and sterilization. The ability to operate at atmospheric pressure, room temperature and simple device configuration has greatly contributed to their appeal and adoption in the plasma science community. However, the mechanisms that sustain the plasma generation and propagation in ambient air are currently a topic of debate. For instance, what appears as a continuous stream of a plasma plume extending outwards from a plasma device into the …

Performance Optimization Over Wireless Links With Operating Constraints, Shiny Abraham

Electrical & Computer Engineering Theses & Dissertations

Wireless communication is one of the most active areas of technological innovations and groundbreaking research ranging from simple cellular phones to highly complex military monitoring devices. The emergence of radios with cognitive capabilities like software defined radios has revolutionized modern communication systems by providing transceivers which can vary their output waveforms as well as their demodulation methods. This adaptability plays a pivotal role in efficient utilization of radio spectrum in an intelligent way while simultaneously not interfering with other radio devices operating on the same frequency band. Thus, it is safe to say that current and future wireless systems and …

Synthesis Of A Superlattice Structure Of Alternating Layers Of Antimony Telluride And Bismuth Telluride By Atomic Layer Deposition For Thermoelectric Applications, David Nminibapiel

Electrical & Computer Engineering Theses & Dissertations

Alloys composed of bismuth, antimony and telluride compounds exhibit very high figure of merit ZT values at relatively low temperatures, making them exceptional thermoelectric materials. Advancement in thermoelectric devices and applications hinges on increasing ZT, which is a ratio of the thermoelectric power factor to the thermal conductivity. One of the proposed avenues to achieving this goal is the use of low dimensional structures such as quantum wells, quantum dots, superlattices (SL) and nanolaminates to affect heat transport. SL structures can effectively confine charge carriers as well as scatter phonons which contribute significantly to thermal conductivity. In this thesis, the …

Optimization Framework For A Radio Frequency Gun Based Injector, Alicia S. Hofler

Electrical & Computer Engineering Theses & Dissertations

Linear accelerator based light sources are used to produce coherent x-ray beams with unprecedented peak intensity. In these devices, the key parameters of the photon beam such as brilliance and coherence are directly dependent on the electron beam parameters. This leads to stringent beam quality requirements for the electron beam source. Radio frequency (RF) guns are used in such light sources since they accelerate electrons to relativistic energies over a very short distance, thus minimizing the beam quality degradation due to space charge effects within the particle bunch. Designing such sources including optimization of its beam parameters is a complex …

Nonosecond Pulsed Electric Field Induced Changes In Dielectric Properties Of Biological Cells, Jie Zhuang

Electrical & Computer Engineering Theses & Dissertations

Nanosecond pulsed electric field induced biological effects have been a focus of research interests since the new millennium. Promising biomedical applications, e.g. tumor treatment and wound healing, are emerging based on this principle. Although the exact mechanisms behind the nanosecond pulse-cell interactions are not completely understood yet, it is generally believed that charging along the cell membranes (including intracellular membranes) and formation of membrane pores trigger subsequent biological responses, and the number and quality of pores are responsible for the cell fate. The immediate charging response of a biological cell to a nanosecond pulsed electric field exposure relies on the …

Multi-Term Approximation To The Boltzmann Transport Equation For Electron Energy Distribution Functions In Nitrogen, Yue Feng

Electrical & Computer Engineering Theses & Dissertations

Plasma is currently a hot topic and it has many significant applications due to its composition of both positively and negatively charged particles. The energy distribution function is important in plasma science since it characterizes the ability of the plasma to affect chemical reactions, affect physical outcomes, and drive various applications. The Boltzmann Transport Equation is an important kinetic equation that provides an accurate basis for characterizing the distribution function—both in energy and space.

This dissertation research proposes a multi-term approximation to solve the Boltzmann Transport Equation by treating the relaxation process using an expansion of the electron distribution function …

Creation Of Large Scale Face Dataset Using Single Training Image, Qun Wang

Electrical & Computer Engineering Theses & Dissertations

Face recognition (FR) has become one of the most successful applications of image analysis and understanding in computer vision. The learning-based model in FR is considered as one of the most favorable problem-solving methods to this issue, which leads to the requirement of large training data sets in order to achieve higher recognition accuracy. However, the availability of only a limited number of face images for training a FR system is always a common problem in practical applications. A new framework to create a face database from a single input image for training purposes is proposed in this dissertation research. …

Smart Sensing And Performance Analysis For Cognitive Radio Networks, Yanxiao Zhao

Electrical & Computer Engineering Theses & Dissertations

Static spectrum access policy has resulted in spectrum scarcity as well as low spectrum utility in today's wireless communications. To utilize the limited spectrum more efficiently, cognitive radio networks have been considered a promising paradigm for future network. Due to the unique features of cognitive radio technology, cognitive radio networks not only raise new challenges, but also bring several fundamental problems back to the focus of researchers. So far, a number of problems in cognitive radio networks have remained unsolved over the past decade. The work presented in this dissertation attempts to fill some of the gaps in the research …

Synergistic Effect Of Subnanosecond Pulsed Electric Fields And Temperature On The Viability Of Biological Cells, James Thomas Camp

Electrical & Computer Engineering Theses & Dissertations

Pulsed electric fields have been used to induce a biological response in cells, and at sufficient energy, can cause cell death. By reducing the pulse duration from presently used nanosecond to subnanosecond ranges, the electric field can be delivered to biological tissue non-invasively by the use of an antenna instead of electrodes, such as needles. Studies have previously been completed in which the aim was to determine the energy density (electric field strength, number of pulses) required to induce cell death with 800 ps pulses. Based on this data, it was concluded that for pulse durations of 200 ps, with …

Evaluation Of Ocean-Energy Conversion Based On Linear Generator Concepts, Michael Allen Stelzer

Electrical & Computer Engineering Theses & Dissertations

A turbine generator is a device that converts mechanical rotation into electrical energy. Unfortunately, the primary driving force that has been used to provide this rotation has, thus far, been fossil fuels. Although fossil fuels have proven to be a reliable resource to continually supply the growing demand for electrical power, they are not without their financial and environmental drawbacks. With the continuously increasing demand for energy, it is hypothesized that the world may, in time, exhaust this precious natural resource and/or inflict permanent environmental damage upon our planet.

However, motions that occur in nature, such as ocean waves, can …

A Vision-Based Automatic Safe Landing-Site Detection System, Yufei Shen

Electrical & Computer Engineering Theses & Dissertations

An automatic safe landing-site detection system is proposed for aircraft emergency landing, based on visible information acquired by aircraft-mounted cameras. Emergency landing is an unplanned event in response to emergency situations. If, as is unfortunately usually the case, there is no airstrip or airfield that can be reached by the un-powered aircraft, a crash landing or ditching has to be carried out. Identifying a safe landing-site is critical to the survival of passengers and crew. Conventionally, the pilot chooses the landing-site visually by looking at the terrain through the cockpit. The success of this vital decision greatly depends on the …

Super-Resolution Of Unmanned Airborne Vehicle Images With Maximum Fidelity Stochastic Restoration, Amr Yousef

Electrical & Computer Engineering Theses & Dissertations

Super-resolution (SR) refers to reconstructing a single high resolution (HR) image from a set of subsampled, blurred and noisy low resolution (LR) images. One may, then, envision a scenario where a set of LR images is acquired with sensors on a moving platform like unmanned airborne vehicles (UAV). Due to the wind, the UAV may encounter altitude change or rotational effects which can distort the acquired as well as the processed images. Also, the visual quality of the SR image is affected by image acquisition degradations, the available number of the LR images and their relative positions. This dissertation seeks …

Enhancing Spectrum Utilization In Dynamic Cognitive Radio Systems, Dusadee Treeumnuk

Electrical & Computer Engineering Theses & Dissertations

Cognitive radio (CR) is regarded as a viable solution to enabling flexible use of the frequency spectrum in future generations of wireless systems by allowing unlicensed secondary users (SU) to access licensed spectrum under the specific condition that no harmful interference be caused to the licensed primary users (PU) of the spectrum. In practical scenarios, the knowledge of PU activity is unknown to CRs and radio environments are mostly imperfect due to various issues such as noise uncertainty and multipath fadings. Therefore, important functionalities of CR systems are to efficiently detect availability of radio spectrum as well as to avoid …