Electrical and Electronics Commons^™

Protection And Disturbance Mitigation Of Next Generation Shipboard Power Systems, Marounfa Djibo

Electrical & Computer Engineering Theses & Dissertations

Today, thanks to modern advances mainly in the power electronics field, megawatt-level electric drives and magnetic levitation are being integrated into the marine power grids. These technologies operate based on Direct Current (DC) power which require Alternating Current (AC) to DC conversion within the current grid. Medium-voltage Direct Current (MVDC) and Flywheel Energy Storage Systems (FESS) are the next state-of-the-art technologies that researchers are leaning on to produce, convert, store, and distribute power with improved power quality, reliability, and flexibility. On the other hand, with the extensive integration of high-frequency power electronic converters, system stability analysis and the true system …

A Correlational Study Of Sansec Sensors’ Electric Field Distribution On Lightning Attachment, Kayla M. Farrow

Electrical & Computer Engineering Theses & Dissertations

Old Dominion University and the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) Aviation Safety Program Atmospheric Environmental Safety Technologies Project team conducted research in using SansEC (Sans Electric Connection) sensors to provide lightning strike protection (LSP) and damage mitigation for composite aircraft. SansEC sensors are simplistic devices consisting of an open circuit conductive trace, shaped in a planar geometric spiral [1], [2], [3]. SansEC sensors can be designed in various shapes and sizes depending on the application. For applications on exterior aircraft surfaces, the sensor must be designed to perform the required lightning strike protection [1], [3]. …

A Study Of The Sensitivity Of Energy Conversion Efficiency To Load Variation In Class-E Resonant Power Inverter, Richard Samuel Jennings

Electrical & Computer Engineering Theses & Dissertations

In this thesis the sensitivity of energy conversion efficiency (ECE) and output power of a class-E resonant inverter under variable resistive and inductive load assignments is examined for wireless power transfer (WPT) applications. By performing simulation and mathematical analysis, it was found that the on-resistance of the switching device has minor effect on the design’s efficiency. Additional comparisons between the simulation and mathematical analysis show reasonable output power and ECE load variation performance for the design, but with unique load impedances where zero voltage switching (ZVS) and zero derivative switching (ZDS) are achieved. These comparisons also expose inaccurate mathematical assumptions. …

Study Of A High-Efficient Wide-Bandgap Dc-Dc Power Converter For Solar Power Integration, Yashwanth Bezawada

Electrical & Computer Engineering Theses & Dissertations

This research focuses on the design and analysis of a Boost cascaded Buck-Boost (BoCBB) power converter with super high efficiency in electric power conversion. The BoCBB power converter is based on emerging wide-bandgap silicon-carbide (SiC) MOSFETs and Schottky diodes, which have only 1/6 times of power loss in traditional silicon power semiconductor devices. The BoCBB power converter can be widely applied in solar harvesting for the National Aeronautics and Space Administration (NASA), military bases and electric utilities, as well as high-power DC motor drives for the electric vehicles, robotics, and manufacturing and product lines.

This research analyzed the topology and …

Simulation, Measurement, And Emulation Of Photovoltaic Modules Using High Frequency And High Power Density Power Electronic Circuits, Yunas Erkaya

Electrical & Computer Engineering Theses & Dissertations

The number of solar photovoltaic (PV) installations is growing exponentially, and to improve the energy yield and the efficiency of PV systems, it is necessary to have correct methods for simulation, measurement, and emulation. PV systems can be simulated using PV models for different configurations and technologies of PV modules. Additionally, different environmental conditions of solar irradiance, temperature, and partial shading can be incorporated in the model to accurately simulate PV systems for any given condition.

The electrical measurement of PV systems both prior to and after making electrical connections is important for attaining high efficiency and reliability. Measuring PV …

Object Tracking From Multiple Multi-Axis Platforms In Four Dimensions, Theodore A. Teates

Electrical & Computer Engineering Theses & Dissertations

Object handoff in free space requires a sound framework between at least two optical sensors and one object. Previous work developed an algorithm that can determine the ap­ propriate time to initiate handoff of object tracking responsibilities from one optical sensor with an object in view to another optical sensor with the same object in view. In order to maintain persistent tracking of objects in this work, gimbal movements of optical sensors are determined by calculations using the Lagrange method to determine the trackability measures between the moving object and the handoff cone for the appropriate optical sensor. The rotation …

Numerical Studies Of The A6 Relativistic Magnetron Using Particle-In-Cell Simulations, Vineetha Jujjavarapu

Electrical & Computer Engineering Theses & Dissertations

The magnetron became a major component in radar systems around the time of the World War II. More recent radar techniques require short microwave pulses (with nanosecond pulse-widths for ultra wideband operations) and high peak power in the Giga-Watt range. In order to achieve these specifications for the military, the magnetron needs to have both a fast start and the rapid growth rate of oscillations in order to serve as a microwave source for the short-pulse applications. These two factors depend on the geometry of the cathode. Other requirements include high conversion efficiency and low leakage current (in order to …

The Study Of Electrostatic And Magnetostatic Active Space Radiation Shielding For Deep Space Missions, Leroy A. Fung

Electrical & Computer Engineering Theses & Dissertations

A goal of the National Aeronautics and Space Administration (NASA) has been to develop technologies that will enable deep space explorations. Such missions include a prolonged stay on the Moon and the ability to sustain a long duration of travel time to Mars and beyond. Long-term human exposures to radiation are a crucial concern. Recent research has taken focus on active and passive shielding methods as a way of eliminating the hazard posed by radiation particles. Passive shielding involves the use of materials that has the ability to withstand radiation particles and reduce the dose by stopping or slowing the …

Generation Of Bipolar Nanosecond Pulses, Sambasiva Rao Rajulapati

Electrical & Computer Engineering Theses & Dissertations

Bipolar pulse generation has been studied using transmission line technology, which was mainly used for monopolar pulse generation. In this thesis, low impedance, high current, nanosecond pulse generators were designed, constructed and tested. Five transmission lines were connected in parallel, so the impedance was 10 n. The transmission lines were switched by a spark gap switch operated in air. The closing of the switch creates a matched condition on one side of the transmission lines and a short circuit on the other side of the transmission lines. When the transmission lines are precharged, one of the two waves in opposite …

Photovoltaic Tracker Optimization With Unique Fault Detection And Enhanced Combiner System, Caitlin Nicole Conway

Electrical & Computer Engineering Theses & Dissertations

Renewable energy resources are rapidly becoming extremely important as the world's energy consumption continues to rise. The most popular of these resources is solar energy and more specifically photovoltaic energy. Currently, solar modules on the market are still not highly efficient. In order to increase the productivity of solar energy systems, larger fixed-panel photovoltaic systems or tracking photovoltaic systems are utilized. The major disadvantage of larger photovoltaic systems is the increased space requirements. Therefore, tracking photovoltaic systems are the best alternative to achieve higher solar energy yields.

To date, the only method of monitoring tracking photovoltaic systems is with the …

Control System Of An Atomic Layer Deposition (Ald) Machine, Nitin Vishnu Hegde

Electrical & Computer Engineering Theses & Dissertations

Atomic Layer Deposition is one of the most efficient deposition processes for obtaining ultrathin films. The deposition by this process happens one atomic layer at a time. ALD is known for its precision and ability to develop quality films with great thickness control. ALD machines simultaneously control DC and AC currents, low pressure operations, temperature control and heating (up to 500'C), precision flow control, precision timing intervals for deposition (milli-second intervals) and constantly monitor temperature. Such a high control comes at a high price. Furthermore, at the university level, the capacity to modify or enhance a machine is critical but …

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 …

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) …

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 Analysis For Wimax Wireless Systems With Multiple Receive Antennas, Selcuk Taskin

Electrical & Computer Engineering Theses & Dissertations

Broadband wireless access has become the best way to meet the growing demand for fast Internet connections. WiMAX is one of the most promising broadband access technologies that allows fast deployment as well as low maintenance costs. WiMAX allows efficient use available bandwidth by using orthogonal frequency division multiplexing (OFDM) which is an efficient multi-carrier modulation technique. Diversity is a method for improving the reliability of a signal in fading environments by using two or more communication channels and is usually achieved by multiple antenna techniques.

In this thesis, receiver side diversity combining methods are studied and the performance of …

Video Stabilization Based On Speeded-Up Robust Features, Minqi Zhou

Electrical & Computer Engineering Theses & Dissertations

With the advancement of science and technology, portable devices using video cameras are becoming more popular. Videos captured by ordinary commercial cameras always suffer from undesired motion which results from human hand shaking and mobile platform vibration. The undesired motion would not only blur the image degrading the image quality leading to inaccurate results in automatic object recognition and tracking, but also make it difficult for people to focus on specific object regions. It is also a possibility that one may feel dizzy while watching shaky video for a long time. Many hardware and software methodologies have been developed by …

Economic Optimization Of Offshore Wind Farms Using The Geometric Algorithm, Mahidhar Nandigam

Electrical & Computer Engineering Theses & Dissertations

The research project related to this thesis focuses on the optimization of electrical systems for offshore wind farms for a given capacity. The optimal design and planning is a critical issue for developing cost effectively Offshore Wind Farms in energy systems. The Geometric Optimization Algorithms approach has been adopted to develop an optimization program, where the main components of the electrical system of an offshore wind farm and key technical specifications are used as parameters to be optimized for a minimum cost with necessary constraints. The effectiveness of the optimization program can be evaluated with real-time comparison between offshore wind …

Electric Field Analysis In Insulating Films For Complex Electrode Systems, Anusha Jambula

Electrical & Computer Engineering Theses & Dissertations

Complex electrode systems with thin insulating materials demand careful examination of field distribution near the electrodes to improve the breakdown characteristics of dielectrics and optimal utilization of the space. The present work contributes to an extended research of physical electrode systems, namely axi-symmetric and non-uniform field systems. In an attempt to optimize the dimensions of the electrode system for subsequent use in electrical measurements, such as electroluminescence, capacitance and conduction current, field values at key points (sharp edges and triple junctions) in an axi-symmetric electrode system are simulated as a function of clearances between low voltage and guard electrodes. Since …

Electric Field Computation Of Wet Insulating Surfaces, Bhargavi Sarang

Electrical & Computer Engineering Theses & Dissertations

High voltage outdoor insulators form the backbone of modem power systems and therefore play a pivotal role in reliable supply of power. The presence of water droplets/films due to rain, fog, etc. enhances the electric field intensity and leads to electrical breakdown subsequently affecting the longevity of the insulator. The magnitude of surface E-fields necessary for initiation of electrical breakdown is a function of water repellent characteristic of an insulator called hydrophobicity. Thus, knowledge of field distribution around water droplets/films at various hydrophobic levels is significant in designing a better insulating material.

The current research analyzed electric field distributions on …

Analysis Of Partial Discharge Pulse Height Distribution Parameters, Vinay N. Nimbole

Electrical & Computer Engineering Theses & Dissertations

Partial Discharges (PD) have been traditionally used to assess the state of any insulation system and its remnant life. In earlier work, Perspex (PMMA) samples with a needle plane gap have been aged with AC voltage. Their tree growth was monitored simultaneously by collecting PD at regular intervals of time and taking microphotographs in real time without interrupting the aging voltage. The obtained partial discharge pulse amplitude records were clustered together into groups of class intervals. The sequence of PD pulse height records was quantified as a time series of shape (η), and scale (σ) parameters of a Weibull distribution. …

A Systematic Study On Structural And Optical Properties In Conjugated Polymer Photovoltaic Devices, Sri Sabarinadh Sunkavalli

Electrical & Computer Engineering Theses & Dissertations

Conjugated polymer/fullerene based solar cells represent an exciting alternative to inorganic ones because of their low production costs, flexibility and low weight. At present, commercialization of organic photovoltaic (OPV) cells is limited due to their relatively low efficiency in comparison to silicon ones. In order to understand the operation of OPV cells and to increase their efficiency, more information about the structure of the absorber layer is needed. In particular, the connection between structure and properties of the absorber layer is of great importance. Performance of bulk heterojunction organic solar cells based on poly (3-hexylthiophene) as donor and a soluble …

Performance Of Adaptive Wireless Systems With Feedback, Sirisha Koduri

Electrical & Computer Engineering Theses & Dissertations

Future generations of wireless systems will employ versatile transmitters and receivers based on software defined radios that are capable of adapting in response to changes in the operating environment to meet the specified quality of service requirements. In adaptive wireless systems, transmitters use feedback from the receiver to update characteristics of the transmitted signal to changing patterns of interference. In this thesis, the performance of transmitter adaptation algorithms with limited feedback and the system performance as a function in which the interference information is quantized for transmission over the feedback channel are analyzed. The results of this thesis were presented …

Detecting Portable Electronic Devices Onboard Commercial Aircraft, Randy Woods

Electrical & Computer Engineering Theses & Dissertations

The need to detect unauthorized usage of intentionally transmitting portable electronic devices (PEDs) onboard commercial aircraft is growing while still allowing passengers to use selected unintentionally transmitting devices, such as laptop computers and CD players, during non-critical stages of flight. This thesis presents the development and testing of an installed system for detecting PEDs over multiple frequency bands. Additionally, the advantages of a fixed versus mobile system are discussed.

Data is presented to cover the frequency range of 20 MHz to 6.5 GHz with special attention given to the cellular and PCS telephone bands, Bluetooth, and the family radio service …

Modeling And Simulations Of Electrical Breakdown And Thermal Failure In Zinc Oxide And Titanium Dioxide For High-Voltage Dielectric Applications, Guogang Zhao

Electrical & Computer Engineering Theses & Dissertations

The development of transmission lines with higher energy storage capabilities is an important goal for compact pulsed power systems. In this context, ceramic dielectrics are promising candidates from the standpoint of high dielectric constants and breakdown strength. Though such materials look promising, their breakdown response characteristics have not been well studied, nor adequately understood. The electrical response of dielectrics also seems to depend on the internal structure and its granularity. For example, the breakdown strength of nano-crystalline insulators such as titania and zinc oxide have been observed to depend on the internal grain size. In general, the hold-off voltage increases …

Ozone Concentration In An Atmospheric Pressure Air Plasma Jet, Srinivas Reddy Suddala

Electrical & Computer Engineering Theses & Dissertations

A stable micro-plasma jet in air was generated from a direct current discharge between two molybdenum electrodes (0.25 mm thick) that were separated by an alumina insulator of the same thickness. The after-glow plasma jet was generated by blowing air through the space between the electrodes. A change from laminar to turbulent flow was observed at a gas flow rate of 140 ml/min. The length of the plasma jet increased with flow rate in the laminar mode to approximately 15 mm and decreased in the turbulent mode.

Increasing the gas flow rate up to 200 ml/min at a constant discharge …

Design And Implementation Of One And Two-Degree-Of-Freedom Magnetic Suspension And Balance Systems, Mark W. Adams

Electrical & Computer Engineering Theses & Dissertations

The main objectives of this research were to design and implement one and two-degree-of-freedom (1 DOF and 2-DOF) magnetic levitation systems to levitate permanent magnet cores contained in PVC pipes, 8.4 cm and 76.2 cm in length, respectively. This project used the components of a Magnetic Suspension and Balance System (MSBS) that is being built to provide obstruction free positioning of test models in six degrees of freedom (6-DOF) inside the Princeton University/Office of Naval Research High Reynolds Number Test Facility (HRTF). The HRTF, a specialized wind tunnel designed to simulate undersea conditions by creating a low-speed, 3500 PSI air …

Modeling Nerve Electro-Stimulation In The Nanosecond Regime, Feng Chen

Electrical & Computer Engineering Theses & Dissertations

Numerical simulations of electrical stimulation of frog gastrocnemius muscles have been carried out for pulse durations in the nanosecond regime. There are a number of potential advantages in using ultra-short pulses for neural stimulation, and no previous electro-stimulation work in the sub-microsecond regime has been reported. A timedependent, three-dimensional analysis model was developed and implemented for three distinct situations: (i) direct stimulation via electrode contact, (ii) indirect excitation based on electrodes immersed in a saline-filled bath, and (iii) remote electromagnetic stimulation through vacuum. The simulations yielded strength-dm ation (S-D) curves with pulse durations as short as 5 ns. Good agreement …

Real-Time Measurements On The Effects Of Ultra-Short High Voltage Pulses On Hl-60 Cells, Michalis C. Artemiou

Electrical & Computer Engineering Theses & Dissertations

The application of high voltage microsecond pulses that are above a critical value, to biological cells, has been shown to cause electroporation (Neumann, 1989). In addition, ultra-short pulses of several tens to hundreds of nanoseconds duration have been recently shown to affect intracellular structures without disturbing the plasma membrane (Schoenbach, 2001). However, such ultra-short intense pulses are expected to cause deformation of cells due to Maxwell stresses. This deformation was studied by means of an imaging technique with 10 ns temporal resolution on HL-60 cells. The imaging system consists of an inverted microscope where a spark light source was used …

Fuzzy Modeling Of Electromagnetic Emissions From Portable Electronic Devices Onboard Commercial Aircraft, Madiha Jamil Jafri

Electrical & Computer Engineering Theses & Dissertations

The use of Portable Electronic Devices (PEDs) is prohibited during take-off and landing of an aircraft because PEDs may emit signals that can interfere with the aircraft's navigation and communication systems. The electromagnetic interference (EMI) on the aircraft's electronics due to PEDs emissions is examined for Boeing 737 and 747 aircraft. This work, funded by the NASA Graduate Researchers Program, uses Interference Path Loss (IPL) data, collected by researchers from NASA Langley Research Center, Eagles Wings Inc. and United Airlines on several out-of-service United B737 and B747 airplanes.

B737 and B747 IPL data has been analyzed using a graphical analysis …

A Pipelined Architecture For Real Time Correction Of Barrel Distortion In Wide-Angle Camera Images, Hau Trung Ngo

Electrical & Computer Engineering Theses & Dissertations

Images captured by wide-angle cameras show barrel type spatial distortion due to wide-angle configuration of the camera lens where image regions farther from the center are compressed in a nonlinear fashion. The barrel distortion correction technique based on least squares estimation attempts to correct a distorted image by expanding it nonlinearly so that straight lines in the object space remain straight in the image space. The intensity value of a pixel in the expanded image is calculated by back mapping its position to the corresponding position in the distorted image and performing linear interpolation on the neighboring pixels. Distorted images …