Engineering Commons^™

Optimized Techniques For Real-Time Microwave And Millimeter Wave Sar Imaging, Joseph T. Case

Doctoral Dissertations

"Microwave and millimeter wave synthetic aperture radar (SAR)-based imaging techniques, used for nondestructive evaluation (NDE), have shown tremendous usefulness for the inspection of a wide variety of complex composite materials and structures. Studies were performed for the optimization of uniform and nonuniform sampling (i.e., measurement positions) since existing formulations of SAR resolution and sampling criteria do not account for all of the physical characteristics of a measurement (e.g., 2D limited-size aperture, electric field decreasing with distance from the measuring antenna, etc.) and nonuniform sampling criteria supports sampling below the Nyquist rate. The results of these studies demonstrate optimum sampling given …

Improving Life Cycle Management Plans For Power Plant Components, Srinath Raghavan

Masters Theses

"Life cycle management (LCM) combines a set of technical and economic activities with the specific goal of improving the long term economic value of an asset. It is necessary to perform a sound LCM exercise on the utility or industrial asset to maintain the profitability of a plant. In most industries, the maintenance budget is either higher than optimal or lower than required, that result in expensive outages, damages and accidents. An LCM plan is a guide to make operational decision for a component over its life cycle. LCM typically consists of a preventive maintenance schedule, condition monitoring, inspection activities, …

Topics In Voice Echo Cancellation, Pratik Vijay Shah

Doctoral Dissertations

"Acoustic echo cancellation (AEC) is a well studied problem. The underlying assumption in most echo cancellation solutions is that the echo path following the reference signal is completely linear. However, in many handheld devices, the echo path following the reference signal is nonlinear. The reason for this nonlinearity in the echo path is the use of smaller and cheaper loudspeakers. In order to cut the manufacturing cost, device manufactures use cheaper loudspeakers such that they satisfy the carrier specifications. Such loudspeaker can be easily over driven in to their nonlinear region and thus add nonlinearities to the downlink path. This …

Harmonic Compensation In A Grid Using Doubly Fed Induction Generators, Omkar Amol Ghatpande

Masters Theses

"Ideally, electric utilities are expected to deliver a sinusoidal voltage with a constant rated frequency, while customers are expected to draw a sinusoidal current with unity power factor. The recent widespread use of harmonic producing equipment in industrial applications, especially non-linear loads, has increased the distortion of electric currents and voltages in transmission and distribution systems. This thesis proposes a method of using multiple reference frame theory for measuring and mitigating harmonic currents of nonlinear loads using a doubly fed induction generator. The most significant low-order harmonics to be compensated are calculated using a multiple reference frame harmonic observer. This …

Fluidic Sensor Devices Utilizing Dry Film Resist As Main Structural Materials, Sijia Gong

Masters Theses

"In this thesis, two types of fluidic sensor devices are demonstrated. The first device utilizes a dry film resist (DFR) as the main structural material of fluidic device utilizing the photolithography process. The second one involves a simple, low-cost sensor platform composed of ubiquitous materials such as polymer tubing and metal wires. Both devices are prepared to measure the dissolved oxygen content, as a model target analyte, based on the oxygen quenching reaction of a ruthenium complex fluorophore as the reporting agent. Characterization of sensors is conducted based on the fluorescence lifetime measurement. The first type of sensor is constructed …

Wideband Characterization Of Printed Circuit Board Materials Up To 50 Ghz, Aleksei Rakov

Masters Theses

"A traveling-wave technique developed a few years ago in the Missouri S&T EMC Laboratory has been employed until now for characterization of PCB materials over a broad frequency range up to 30 GHz. This technique includes measuring S-parameters of the specially designed PCB test vehicles. An extension of the frequency range of printed circuit board laminate dielectric and copper foil characterization is an important problem. In this work, a new PCB test vehicle design for operating up to 50 GHz has been proposed. As the frequency range of measurements increases, the analysis of errors and uncertainties in measuring dielectric properties …

Systems And Image Database Resources For Uav Search And Rescue Applications, David Christopher Macke Jr.

Masters Theses

"Aerial search and rescue applications using unmanned aerial vehicles (UAVs) can incorporate image processing technologies to locate targets faster and with a higher degree of accuracy. The task of developing such systems involves the development of both hardware and software components. Examples of both hardware and software approaches in the design process for an aerial imaging system are shown for small UAV applications. This project contains resources to help facilitate the incorporation of UAV applications into educational ventures and design projects. A power supply design is done for a lightweight imaging system and a large database of aerial images is …

Direct - Drive Permanent Magnet Synchronous Generator Design For Hydrokinetic Energy Extraction, Amshumaan Raghunatha Kashyap

Masters Theses

"Hydrokinetic turbines deliver lower shaft speeds when compared to both steam and wind turbines. Hence, a water wheel generator must operate at speeds as low as 150 - 600 rpm. This thesis describes a permanent magnet synchronous generator (PMSG) that was designed, built, and tested to serve a low speed hydrokinetic turbine. The design methodology was emphasized since designing an application specific generator poses various design and hardware construction issues. These are torque, speed, power and start-up requirements. This generator was built to operate without a speed increaser, implying very low speeds. FEA and performance results from the simulation done …

A Calibration Free Vector Network Analyzer, Arpit Kothari

Masters Theses

"Recently, two novel single-port, phase-shifter based vector network analyzer (VNA) systems were developed and tested at X-band (8.2 - 12.4 GHz) and Ka-band (26.4 - 40 GHz), respectively. These systems operate based on electronically moving the standing wave pattern, set up in a waveguide, over a Schottky detector and sample the standing wave voltage for several phase shift values. Once this system is fully characterized, all parameters in the system become known and hence theoretically, no other correction (or calibration) should be required to obtain the reflection coefficient, (Γ), of an unknown load. This makes this type of VNA "calibration …

Detecting And Locating Electronic Devices Using Their Unintended Electromagnetic Emissions, Colin Stagner

Doctoral Dissertations

"Electronically-initiated explosives can have unintended electromagnetic emissions which propagate through walls and sealed containers. These emissions, if properly characterized, enable the prompt and accurate detection of explosive threats. The following dissertation develops and evaluates techniques for detecting and locating common electronic initiators. The unintended emissions of radio receivers and microcontrollers are analyzed. These emissions are low-power radio signals that result from the device's normal operation. In the first section, it is demonstrated that arbitrary signals can be injected into a radio receiver's unintended emissions using a relatively weak stimulation signal. This effect is called stimulated emissions. The performance of stimulated …

Dynamic Modeling, Stability Analysis, And Controller Design For Dc Distribution Systems, Reza Ahmadi

Doctoral Dissertations

"The dc distribution systems or dc microgrids are known to be best suited for integration of renewable energy sources into the current power grid and are considered to be the key enabling technology for the development of future smart grid. Dc microgrids also benefit from better current capabilities of dc power lines, better short circuit protection, and transformer-less conversion of voltage levels, which result in higher efficiency, flexibility, and lower cost. While the idea of using a dc microgrid to interface distributed energy sources and modern loads to the power grid seems appealing at first, several issues must be addressed …

Data Fusion Techniques For Nondestructive Evaluation And Medical Image Analysis, Soumya De

Doctoral Dissertations

"Data fusion is a technique for combining data obtained from multiple sources for an enhanced detection or decision. Fusion of data can be done at the raw-data level, feature level or decision level. Applications of data fusion include defense (such as battlefield surveillance and autonomous vehicle control), medical diagnosis and structural health monitoring. Techniques for data fusion have been drawn from areas such as statistics, image processing, pattern recognition and computational intelligence. This dissertation includes investigation and development of methods to perform data fusion for nondestructive evaluation (NDE) and medical imaging applications. The general framework for these applications includes region-of-interest …

Parallel-Connected Solar Arrays, Majed Meshal Alabbass

Masters Theses

"The purpose of this thesis is to investigate the advantages of having various series-parallel configurations of solar arrays and make a comparison between them. The objective is to determine the best PV system configuration and thus improve the overall efficiency of a solar array. The primary focus of this thesis is to study the parallel connection of PV panels for achieving maximum efficiency while extracting maximum energy from the solar radiation. A comparison between a series connected and a parallel connected solar PV array justifies the need for installing a parallel configured solar PV array to achieve optimum performance. The …

High Temperature Sensor Based On Fabry-Perot Interferometer In Ceramic Coaxial Cable, Kenneth Paul Smith Jr.

Masters Theses

"In this thesis, the application of a coaxial cable Fabry-Perot interferometer (CCFPI) as a high temperature sensor is analyzed. Coaxial cable sensors provide the advantages of fiber optic sensors, such as the ability to be embedded and multiplexed, while overcoming the limitations created by the fragility of fibers. The fabrication process of the CCFPI, using a computer controlled drill system to create holes in the cable is discussed. By analyzing the amplitudes of the created reflections, the diameter of the holes is optimized. A new fabrication process, in which holes are drilled 180⁰ apart from each other to create a …

Advances In Blind Source Separation, Christopher Osterwise

Doctoral Dissertations

"Blind Source Separation (BSS) is a classic problem that attempts to separate unknown sources from observed mixtures. A common framework of this is the Cocktail Party problem, where multiple individuals speaking in a noisy room are recorded by a configuration of microphones, with the challenge being to split the observed signals into individual conversations. This dissertation covers the evaluation of an existing algorithm known as Cascaded ICA with Intervention Alignment (CICAIA), the establishment of a new parameter for characterizing blind mixtures, and three new algorithms, of which two are capable of separating any number of sources given more microphones than …

Integration Of Nanoporous Zeolite With Optical Fiber Devices For Chemical Sensing, Xinwei Lan

Doctoral Dissertations

"Label-free optical fiber chemical sensors have provoked significant research interest in recent years due to their unique advantages of small size, low cost, potential for distributed sensing, capability of in situ and remote operation, and tolerance to harsh environments. However, existing optical fiber chemical sensors lack the desired sensitivity and specificity for many applications such as chemical and biological analysis, industrial process control, environmental monitoring, and national security.

The dissertation summarizes our research efforts and results in functional integration of nanoporous zeolites with optical fiber devices for development of label-free optical fiber chemical sensors with high sensitivity and selectivity. Fundamental …

Inverter Design And Analysis Using Multiple Reference Frame Theory, Luke Dale Watson

Doctoral Dissertations

"Multiple reference frame theory allows for periodically time varying signals to be represented as a set of dc signals. In other words, every periodic signal can be expanded into a Fourier series representation. By modeling an inverter connected to a boost maximum power point tracker (MPPT) in this manner, frequency transfer properties can be preserved and harmonics throughout the system can be predicted. A state space model taking into account the dc and fundamental grid frequency is presented and used to optimize the controller gains of the system. Using information from the dq-axis values of the measured grid current and …

Finite-Horizon Optimal Control Of Linear And A Class Of Nonlinear Systems, Qiming Zhao

Doctoral Dissertations

"Traditionally, optimal control of dynamical systems with known system dynamics is obtained in a backward-in-time and offline manner either by using Riccati or Hamilton-Jacobi-Bellman (HJB) equation. In contrast, in this dissertation, finite-horizon optimal regulation has been investigated for both linear and nonlinear systems in a forward-in-time manner when system dynamics are uncertain. Value and policy iterations are not used while the value function (or Q-function for linear systems) and control input are updated once a sampling interval consistent with standard adaptive control. First, the optimal adaptive control of linear discrete-time systems with unknown system dynamics is presented in Paper I …

Fabry-Perot Interferometer Based Co₂ Sensor Using Ionic-Liquid, Mujahid Abdul

Masters Theses

"Anthropogenic greenhouse gas emission has become an eminent problem today especially CO₂ gas emission is of major importance. Statistics show that CO₂ concentration is consistently increasing in atmosphere every year. Having cognizance of this problem, better CO₂ absorbents, ionic liquids, has been suggested through this thesis. To prove Ionic liquid's efficiency, a unique sensor was developed by a sophisticated fabrication using Femto-second (fs) laser. Sensor is built to work as an extrinsic Fabry-Perot Interferometer (EFPI) to sense CO₂. EFPI sensor consists of a glass tube fused between two single mode fibers, and a miniature hole is fabricated in the tube …

New Sensorless, Efficient Optimized And Stabilized V/F Control For Pmsm Machines, Seyed Hesam Jafari

Masters Theses

"With the rapid advances in power electronics and motor drive technologies in recent decades, permanent magnet synchronous machines (PMSM) have found extensive applications in a variety of industrial systems due to its many desirable features such as high power density, high efficiency, and high torque to current ratio, low noise, and robustness. In low dynamic applications like pumps, fans and compressors where the motor speed is nearly constant, usage of a simple control algorithm that can be implemented with least number of the costly external hardware can be highly desirable for industry. In recent published works, for low power PMSMs, …

Feature Extraction Through K-Means Segmentation For Melanoma Detection, Snigdha Priya Bommadevara

Masters Theses

"Malignant melanoma is responsible for 75% of the deaths caused due to skin cancer annually. However, melanoma detection can be possible through feature extraction and pattern classification, which can lower the risk, if the melanoma is detected at an early stage. Clustering is one of the most useful tools used to differentiate features that can contribute to melanoma. This research work uses the k-means clustering algorithm for implementation of color segmentation. However, k-means clustering requires a predefined value of k, i.e., the number of clusters must be specified at the beginning of the run. This research uses a predefined value …

A Study Of Clustering Rssi And Lqi From Wireless Network Communications, Yanwen Wang

Masters Theses

"In today's information world, different wireless sensor network topologies are permitted to exist in the same geographical region. For example, a city contains thousands of enterprise networks; a school might include different wireless network topologies used by students and faculties respectively. Even within a building, there might be multiple companies that use their own wireless networks. These networks might cause interference to other networks. How to detect, determine and locate the unknown wireless topologies in the same geographical area becomes quite significant in the wireless industry, especially in military use, such as spy-nodes detection and communication orientation systems. In this …

Constructing Conducted Emission Models For Integrated Circuits, Shuai Jin

Masters Theses

"Conducted emissions, noise conducted out of integrated circuit pins, play an important role in determining the system level EMC performance. Characterizing conducted emissions from ICs is investigated and the corresponding noise models are developed in this thesis. Both simulation IBIS and measurement based methods for noise-model construction are studied. The constructed noise source model for a test IC is applied in system-level simulations and the calculated far field radiation is validated with measurements. The agreement in the simulated and measured results demonstrates the effectiveness of the constructed model for characterizing the conducted emissions from an IC I/O pin"--Abstract, page iii.

Design And Analysis Of An Open-Ended Waveguide Probe For Material Characterization, Matthew Alan Kempin

Masters Theses

"Nondestructive evaluation of stratified (layered) composite structures at microwave and millimeter wave frequencies is of great interest in many applications where simultaneous determination of the complex dielectric properties and thicknesses of multiple layers is desired. Open-ended rectangular waveguide probes are effective tools for this purpose. The technique requires a full-wave electromagnetic model that accurately calculates the complex reflection coefficient as a function of frequency and material properties. Subsequently, this information is used in conjunction with the measured complex reflection coefficient to evaluate the sought for material properties. This thesis presents simulated and measured data to investigate the influence that measurement …

Feature Extraction Through Median-Split Algorithm Segmentation For Melanoma Detection, Venkata Sai Narasimha Kaushik Ghantasala

Masters Theses

""Detection of melanoma remains an empirical clinical science. New tools for automatic discrimination of melanoma from benign lesions in digitized dermoscopy images may allow an improvement in early detection of melanoma. This research implements a fast version of the median split algorithm in an open source format and applied to four-color splitting of the lesion area to capture the architectural disorder apparent in melanoma colors. This version of the median split algorithm splits colors along the color axis with maximum range". For a dermoscopy set of 888 images, K-means clustering algorithm is compared with a median split algorithm to find …

A Conforming Method For Regional Marginal Loss Surplus Allocation, Xiaolong Wang

Masters Theses

"The marginal transmission loss model is used in electricity markets across the United States to measure a resource's marginal contribution to system loss. This model prices loss into the locational marginal price as a marginal loss component. Marginal loss pricing will render a net revenue surplus within an energy balanced system. This marginal loss surplus (MLS) is typically allocated back to scheduling coordinators in proportion to the measured demand on a system-wide basis. However, when the system experiences heterogeneous loss across different regions, the system-wide allocation method fails to recognize the regional differences in actual loss costs. As a result, …

Fiber Inline Pressure And Acoustic Sensor Fabricated With Femtosecond Laser, Yinan Zhang

Doctoral Dissertations

"Pressure and acoustic measurements are required in many industrial applications such as down-hole oil well monitoring, structural heath monitoring, engine monitoring, study of aerodynamics, etc. Conventional sensors are difficult to apply due to the high temperature, electromagnetic-interference noise and limited space in such environments. Fiber optic sensors have been developed since the last century and have proved themselves good candidates in such harsh environment. This dissertation aims to design, develop and demonstrate miniaturized fiber pressure/acoustic sensors for harsh environment applications through femtosecond laser fabrication. Working towards this objective, the dissertation explored two types of fiber inline microsensors fabricated by femtosecond …

Quantization Noise Analysis Of A Closed-Loop Pwm Controller That Includes Σ-Δ Modulation, Anupama Balakrishnan

Masters Theses

"Σ-Δ modulation is a popular noise shaping technique which is used to move the quantization noise out of the frequency band of interest. Recently, a number of authors have applied this technique to a pulse width modulation (PWM) controller for switching power converters. However, previous analysis has not incorporated the effects of analog-to-digital converter (ADC) resolution or feedback control on the Σ-Δ modulator. In this work, quantization due to ADC resolution and PWM resolution are analyzed, considering the effects of noise-shaping and feedback. A number of simulations have been performed to explore the impact of various design choices on output …

Technical Modeling And Control System Development Of Hybrid Energy System Using Coal, Nuclear, Wind And Diesel, Uday Guntupalli

Masters Theses

"Addressing the growing energy concerns of the modern world is a challenging problem. Traditional carbon intensive fuel sources like coal, diesel which are instrumental in meeting today's grid demand are struggling to meet the stringent environmental regulations. Operations of independent renewable energy sources despite reducing costs are not comparable to existing costs of electricity. A sustainable approach to address these concerns is proposed in this work. A hypothetical hybrid system involving traditional fuel sources like coal, small modular nuclear reactor and renewable energy source wind is analyzed through dynamic modeling using various tools.

Various simulation tools were analyzed and the …

Source Reconstructions For Ic Radiated Emissions Based On Magnitude-Only Near-Field Scanning, Ji Zhang

Doctoral Dissertations

"In this dissertation, a source reconstruction method is proposed to model the emission behavior of an IC by using magnitude-only information during near-field scanning. The phase-retrieval is accomplished during the back-forth iterations between two scanning planes of different heights. The magnitudes of fields on two planes of different heights are recorded and used to constrain the amplitude of the calculated fields during iterations. Three essential transformations among dipoles and fields are continued at each iteration step, until the convergence condition is achieved. The proposed algorithm has been verified by using a set of dipole-array as the original emitting sources, and …