In this research, a continuous analog generalized impedance converter (GIC) 4th order band pass filter is investigated in detail. Various classroom software aids such as MATLAB, P-SPICE and MAPLE are utilized to simulate varies circuit parameter changes in ideal and non-ideal GIC filter, such as network sensitivity, effects of resistor value, capactor value and reduction of gain bandwidth product (GBWP), on the center frequency and Q factor. All simulated results are used to evaluate the actual circuit implementation prior to future GIC filter chip fabrication. A composite operational amplifier utilizing the BiCMOS standard operational amplifier that was designed and introduced in a previous thesis is presented and its improved performance is investigated. The composite amplifier (C20A2) is designed using Silvaco EXPERT and simulated with Silvaco SmartSpice. The results show the gain bandwidth product (GBWP), common mode rejection ratio (CMRR), and open loop gain are considerably improved. This sets the basic foundation for future students to incorporate the newly designed composite operational amplifier into the GIC filter to further enhance filter performance.

The purpose of this thesis is to implement the CAF-Map method of geolocation in MATLAB. This method is a modification to the traditional Cross Ambiguity Function (CAF) based TDOA, FDOA geolocation where TDOA and FDOA are determined by locating the peak in the CAF plane and then the peak's information is fed to a Least Squares like geolocation tool to determine the emitters geolocation. This method omits the step in which the geolocation is determined with the "post processed" CAF peak information and instead maps the CAF surface directly to the earth's surface. In this thesis, the traditional CAF based geolocation is explained and the limitations are discussed. After this, the development of the CAF-Map method is explained and the algorithm is presented. This thesis explores the use of the CAF-Map method as a geolocation alternative to the traditional TDOA, FDOA methods and demonstrates its ability to geolocate co-channel emitters.

Recent military applications have demanded photodetectors with high sensitivity, high selectivity and multispectral capability for detection and identification of the target. These characteristics have been found in quantum well infrared photodetectors (QWIP). Driven by these applications, a QWIP photodetector capable of detecting simultaneously infrared emissions within near infrared (NIR), mid wavelength infrared (MWIR) and long wavelength infrared (LWIR) was studied, modeled, designed and characterized. Using the envelope function approximation, the mathematical model of the quantum phenomena in semiconductor heterostructures was derived. A computational tool was developed to solve self-consistently the Schodinger-Poisson equation using the shooting method, allowing the theoretical evaluation of the absorption coefficient. A three-color (NIR, MWIR and LWIR) GaAs-based QWIP sample and a two-color (NIR and MWIR) InP-based QWIP sample were designed, both comprised of stacks of uncoupled wells for each band detection. The 67 layers of the GaAs sample was grown using molecular beam epitaxy (MBE). Intersubband absorption in the sample was measured for the MWIR and LWIR using Fourier transform spectroscopy (FTIR) and the measured peak positions, found at 5.3 æm , 8.7 æm , and 13.8 æm are within 0.3 æm of the theoretical values, indicating that the model accurately predicts the absorption wavelengths. A twodimensional ordered grating pattern was selected and optimized separately for both MWIR and LWIR desired peaks. Finally the photodetector device configurations were designed to permit to the measurement of the NIR band through photocurrent spectroscopy and performance analysis. The fabrication and characterization of the prototypes are a matter for future work.

The primary objective of this these was to study the feasibility of using a MEMS accelerometer to monitor vibration signatures of a machine to determine if the machine is operating properly. The secondary objective was to investigate the self test features of the accelerometer used in the vibration monitoring. An Efector Octavis accelerometer sensor was used in this study. It was used to monitor a small air pump and an air conditioning (AC) system. The sensor provided the amplitude for the frequency spectrum of the motor vibration. A reference signal was calculated by taking an average of the spectrum over 30 seconds. Two methods (a ratio of cross-correlation coefficients and a spectral distance) were used to compare the reference to the sensor data. The spectral distance method proved to be the better of the two. Using this method, the system could sense when the pump or the AC unit were malfunctioning. The self test feature involved exciting the Built in Self Test (BIST) pin of the accelerometer with a signal generator. Then the impulse response of the accelerometer was measured from the output pin using an oscilloscope.

This thesis studies the performance of Multiple-Input, Multiple Output (MIMO) systems that use Space-Time Block Coding (STBC). Such systems can be employed to improve the bit error rate (BER) performance of wireless communication systems and counter the detrimental effects of channel fading and other distortion phenomena. We propose a systematic method for designing a space-time orthogonal MIMO scheme that employs an arbitrary number of transmitting and receiving antennas, and we evaluate (through simulation) the performance improvements that can be attained by employing our design approach. We present a general formula for determining the rate (i.e., the ratio of the number of symbols transmitted to the number of symbol intervals required) of systems that employ our design. Additionally, this thesis analyzes the relationship between channel correlation and antenna spacing for the case of MIMO systems that use a linear antenna configuration, and, through simulation studies, we show how such systems can take the advantage of the multipath phenomenon to reduce the detrimental effects of channel correlation.

<p> The NASA Independent Verification and Validation (IV&amp;V) Program has been tasked with performing testing for the Consultative Committee for Space Data Systems (CCSDS) Space Data Link Security (SDLS) Extended Procedure (EP) protocol. This testing has allowed for both the expansion of inter-agency collaboration and the publishing of the SDLS-EP Standard. This protocol is a &ldquo;data processing method for space missions that need to apply authentication and/or confidentiality to the contents of Transfer Frames used by the Space Data Link Protocols over a space link&rdquo; (CCSDS) . The interest for security on satellites stems from threats including but not limited to data corruption, interception, access control, and physical attacks.</p><p> Protocol testing has been performed in the cloud between the European Space Agency and NASA. The flight software used on-board the simulated spacecraft was the Core Flight System (cFS). A cFS cryptography library, named Crypto, was developed to implement the SDLS-EP procedures and allow for easy integration into existing command ingest and telemetry output applications via a single security function. This library allows the spacecraft to communicate using the standardized Telecommand and Telemetry protocols while still publishing received CCSDS messages to the cFS software bus for application processing. The cFS Crypto library is currently undergoing the NASA release process to become open-source software. The sole designer, developer, and tester is looking to expand and increase current development speed by leveraging the community. </p>

<p> Investigation of abnormal behavior of light induced degradation (LID) in cost-effective industrial aluminum back surface field (Al-BSF) silicon solar cells. (Under the direction of DR. ABASIFREKE EBONG) In this research, the p-type boron-doped (B-doped) Czochralski (Cz) mono crystalline silicon (c-Si) Al-BSF solar cell was studied because of its large market share, high efficiency potential (~20%) and cost-effectiveness. The main problem of the p-type B-doped Cz silicon is the unstable efficiency due to the light induced degradation (LID). </p><p> In order to resolve this unstable-efficiency problem, this thesis work investigated the causes and mitigation of LID. The major cause of LID is the formation of boron-oxygen defect in the silicon bandgap under irradiation. The reduced lifetime due to recombination in the bandgap can be recovered by two methods including (i) ~200&deg;C low temperature anneal or (ii) rapid thermal anneal at 630-850&deg;C. LID can be prevented with alternative base-doping such as Ga, P, or the use of high base resistivity in boron doped Si. However, the latter is still in the research stage while the majority of the commercial solar cell is boron doped with resistivity ranging from 0.5-2 &Omega;-cm. Therefore, there is a greater need to fully understand how to get rid of the LID in the finished cells. </p><p> This thesis work focuses on regeneration of cells after the contact co-firing step or/and degraded state. Regeneration is a stable recovery, which encompasses degradation, recovery and stability. Two experimental set ups were conducted by controlling (i) the carrier injection (~1 sun), (ii) the temperatures (70-100&deg;C), and (iii) time (> 24 hours). The cells went through degradation, recovery and stabilization under irradiation. </p><p> The recombination centers constituted of the boron-oxygen related defect are passivated by the effusion of hydrogen existing in the anti-reflection coating (ARC) of a solar cell. During the contact co-firing process after the screen printing, hydrogen enable to diffuse from ARC into the bulk. If the cooling rate is fast in the co-firing, then the future LID degradation is less because some of the hydrogen is retained at the recombination sites. </p><p> Regeneration is based on hydrogenation. First, the hydrogen from ARC diffuses into the bulk during the contact co-firing. Subsequently, through the regeneration process, the hydrogen in the bulk transfers to atomic and mobile hydrogen at excited states, and finally passivates defect into equilibrium. The regeneration process requires simultaneous (i) the carrier injection (> 0.1 suns), (ii) elevated temperatures (65-400&deg;C) and (iii) the sufficient time. </p><p> Hydrogenation through regeneration process results in stable solar cells. In comparison between the results in this thesis and previous studies in literature, it can be concluded that the faster regeneration rate primarily depends on the temperatures. The higher the temperature in a proper range, the shorter the time required for regeneration.</p>

<p> Power plants are generally far away from the distributing center. Transmission line is employed to transfer energy to a city. Transmission line is a complex system, so the transmission line&rsquo;s overload is always a challenging problem for utilities protection engineers. As a result, a series compensating capacitor (SCC) is placed along the transmission line to make the power factor correction, and increase the load capability. However, adding the SCC to the transmission line increases the potential risk of subsynchronous resonance (SSR) at a low frequency oscillation, which may lead to a possible torsional interaction and damages the turbine generator shaft when the mechanical frequency falls below the electrical frequency of the grid. To study the SSR phenomenon, the mathematical model of the IEEE second benchmark (SBM) is utilized and computed at the system operating point, and then compensated with an analog proportional integral and derivative (PID) controller to the linearized and controllable transformed model of the system. The extended discrete PID controller is developed from an analog PID controller via bilinear transformation, which yields similar result. This extended discrete PID controller is a preferred method in preventing the SSR in the power system for its flexibility in updating parameters of the nonlinear system to tolerate variation in different operational conditions.</p>

<p> Watermarking is the process of embedding information into a carrier signal such as audio, video, and images. It is widely used to protect proprietary information in the signal to prevent information theft or duplicity. In this project, an audio watermarking system with dual layer security has been implemented. The entire system is divided into two sections that are independent, but have been combined, to make a unique system that provides increased levels of robustness. The first part of the project involves encrypting an embedded image (watermark) using the XOR method of symmetric key cryptography. Encryption is then followed by watermarking. The digital wavelet transform (DWT) algorithm was used to embed the encrypted image into an audio signal. This ensures that even if this image is removed during an attack to the carrier signal, it cannot be interpreted or used. Though encryption combined with watermarking is unconventional, it proves to be an effective technique when implemented correctly.</p>

<p> Due to continuously increasing traffic on highways and roads, the congestion level on the nation&rsquo;s roadways is spiraling out of control. Current implementations for the traffic detection used in the United States utilize inductive loop technologies placed during road construction, or they are sawed and placed in after. These inductive-loop traffic detectors are primarily used for the detection of vehicles; however, more advanced systems can classify vehicles in addition to detection as well as save large amounts of power. To improve the traffic system and make it more advanced, in this thesis, an in-node microprocessor-based vehicle classification approach to analyze and determine the types of vehicles passing over a 3-axis magnetometer sensor is proposed. This approach for vehicle classification utilizes the J48 classification algorithm implemented in Waikato Environment for Knowledge Analysis (WEKA), a machine learning software suite, and the logistic regression model implemented in MATLAB (MATrix LABoratory) as well. The J48 is a Quinlan's C4.5 algorithm, an extension of the decision tree machine learning based on the ID3 (Iterative Dichotomiser 3) algorithm. The decision tree model is generated from a set of features extracted from the data of the vehicles passing over the 3-axis sensor. The features are attributes provided with correct classifications to the J48 training algorithm to generate a decision tree model with varying degrees of classification rates based on cross-validation. Ideally, using fewer attributes to generate the model allows for the highest computational efficiency due to fewer features needed to be calculated while minimizing the tree with fewer branches. The generated tree model can then be easily implemented using nested if-loops in any language on a multitude of microprocessors. In addition, setting an adaptive baseline to negate the effects of the background magnetic field allows reuse of the same tree model in multiple environments. In addition to the J48, the binary logistic regression model is also used here to estimate the probability of a binary response (0 or 1) based on one or more predictors (or independent) variables (features). The reason the binary logistic model is used in this thesis is because only two classes of the vehicles are being analyzed here. A Sedan is taken as logic 0, and a Sports Utility Vehicle (SUV) is taken as logic 1; both of these vehicle types are the main concern as these two types are quite difficult to differentiate from their magnetic signature.</p><p> The logistic regression measures the relationship between the categorical dependent variable and one or more independent variables by estimating the probabilities using a logistic function. The logistic regression is a special case of the Generalized Linear Model (GLM) and is based on the relationship between dependent (either Sedan or SUV) and independent variables (features). This model predicts the probability of a car being a Sedan or an SUV. If the probability of a car exceeds the required amount, it classifies the car type as either a Sedan or an SUV. The result of this experiment shows that the vehicle classification system is effective and efficient.</p>