Department of Electrical and Computer Engineering
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Item A deep convolutional neural network approach for biomedical applications.(December 2022) Nguyen, Hanh Hong, 1991-; Schubert, Keith Evan.Deep learning is a subset of machine learning that uses multi layer neural networks to perform desired tasks by using trained models. Neural networks are nonlinear mapping systems whose structure and function are loosely modeled on the physical structure of the nervous systems in humans and animals. In deep learning, convolutional neural networks (CNNs) have been used to analyze visual tasks for more than 40 years. Since the mid-2000s, they have revolutionized image processing and analysis. The goal of this dissertation is designing a deep CNN approach for biomedical applications, including automation of the process of colon polyps classification as well as single particle identification in radiation therapy.Item A model of clocked electric field inputs for molecular quantum-dot cellular automata.(2019-11-08) Henry, Jackson Alan, 1994-; Blair, Enrique Pacis.Quantum-dot cellular automata (QCA) is a low-power, high-speed, beyond- CMOS approach to general-purpose computing [1]. Elementary devices called “cells” are implemented using mixed-valence molecules with redox centers having a few quan- tum dots. These support three distinct localized electronic states labeled “0”, “1”, and “Null”. Cells can be clocked to either the “Null” state or an active (“0” or “1”) state using the vertical component of an applied electric field. Clocking provides power gain for restoring weakened signals and allows synchronous control of QCA circuits. In this paper, clocked molecular QCA circuits are simulated in the presence of an applied input field, using the intercellular Hartree-Fock approximation [2]. In- put circuits and down-stream circuits function in the presence of the input field and unwanted field fringing from electrodes. This emphasizes that widely-available fabri- cation techniques may be used to form electrodes for writing bits to molecular QCA circuits.Item A neural inspired grid cell aid for robot intertial navigation.(2018-05-08) Martinez, Moises, 1993-; Koziol, Scott M.Accurate position information is needed for a robot's guidance and control systems. Therefore, the navigation system is foundational for a robot's interactions with the world. This thesis explores a biologically inspired method of navigation with the goal of improving navigational accuracy. The desire to integrate brain-inspired methods with conventional signal processing methods is based on animals' innate ability to successfully navigate through habitats. Therefore, it is reasonable to explore the way animals process brain signals to navigate and leverage it for robot navigation. This thesis uses a combinatorial model of map formation and localization with grid cells to aid dead reckoning with an accelerometer and gyroscope to show grid cells are a viable aid in idiothetic navigation. The results show that the grid cell aided navigation systems shows better performance with longer paths and higher noise values with an improvement of 57.24 cm for a 32 m path with 3 σ noise.Item Ab-initio models of quantum dot cellular automata molecules.(December 2022) Liza, Nishat Tasnim, 1993-; Blair, Enrique Pacis.Molecular quantum-dot cellular automata (QCA) is a charge based, low-power, energy-efficient alternative to transistor-based, general-purpose computation. In molecular QCA, redox centers of a mixed-valence (MV) molecule function as coupled quantum dots, and localized charge states of the molecule encode binary information useful for classical computing. Molecular QCA promises ultra-high device densities, THz-scale switching speeds and room temperature readout. While the fundamental principle of molecular QCA have been tested and established, major challenges must be overcome to successfully implement molecular QCA. This work applies ab-initio techniques in the design and modeling of candidate MV molecules for QCA. Here, we study and characterize ∼ 1-nm-scale MV QCA molecules using first principle calculations. The structural and electronic properties of QCA molecules are calculated utilizing Hartree-Fock, Post-Hartree-Fock and Density functional theory (DFT) methods. Asymmetric, cationic, MV molecules are designed for spectroscopic state readout of QCA devices at room temperature. Tip-enhanced Raman spectroscopy is proposed to detect the state of QCA devices in a circuit if the QCA molecules have slightly dissimilar quantum dots. Clocked zwitterionic three-dot QCA molecules with built-in counterions at the center of the molecules are modeled. The choice and design of the central linkers of these molecules determines number of mobile charges in the molecules for encoding the device states on the three quantum dots. These molecules show different device responses to applied clocking electric field based on different central linkers designed and used, similar to the complementary responses of PMOS and NMOS transistors to gated voltage control. Counterion effects on QCA candidate molecules are also explored in terms of electron transfer parameters. The complete active space self consistent field (CASSCF) method is used to calculate electron transfer (ET) matrix element and inner-sphere reorganization energy of the molecules in the presence of nearby counterions. Results demonstrate that randomly placed externel counterions may degrade device states by causing mobile charge to localize in undesirable ways on the QCA molecule. New zwitterionic molecules with a built-in counterion are proposed to eliminate unpredictable effects of external counterions in QCA circuits. Novel organometallic zwitterionic QCA molecules with ferrocene dots are designed and proposed for synthesis. The chemical stability of these ferrocene based molecules are evaluated by theoretical calculations. The synthesis of these stable zwitterionic molecules by collaborating experimental chemists is in progress and may open a new path to realize molecular QCA computing. A new machine-learning-based DFT functional, DM21 is investigated and benchmarked against traditional methods by comparing the calculated ET matrix elements of several QCA molecules. Preliminary results calculated from DM21 functional did not show significant improvements in accuracy and computational cost. Modification and improvement of the neural network used in the development of the functional, as well as the underlying code is proposed which might open new path to computationally inexpensive QCA calculations.Item Accelerating path planning algorithms with high level synthesis tools and FPGAs.(2013-05-15) Trower, John W.; Duren, Russell Walker.; Electrical and Computer Engineering.; Baylor University. Dept. of Electrical and Computer Engineering.Accelerating path planning algorithms with field programmable gate arrays (FPGA) allows the designer to achieve significant performance increases over using a traditional central processing unit (CPU). Converting an algorithm to run on an FPGA is a complicated and time consuming process. This thesis develops and verifies a design framework that demonstrates how to design a path planning algorithm in a high level language, then convert the algorithm into hardware description languages using high level synthesis tools. This design framework will be used to demonstrate the acceleration of a genetic algorithm.Item Adaptive load impedance optimization for power amplifiers in reconfigurable radar transmitters.(2013-05-15) Martin, Joshua Lee.; Baylis, Charles Passant, 1979-; Electrical and Computer Engineering.; U.S. Naval Research Laboratory.; Baylor University. Dept. of Electrical and Computer Engineering.A fundamental tradeoff exists in radar transmitter design between linearity and efficiency due to the signal amplification. These transmitters are driven into saturation in order to increase efficiency, but may potentially violate regulatory spectral mask limitations. An adaptive method for optimizing linearity and efficiency for power amplifiers in radar transmitters is presented. This approach uses intelligent search techniques with load-pull measurements for power-added efficiency (PAE) and adjacent channel power ratio (ACPR) to dynamically maximize the PAE while meeting spectral requirements. Using load-tuning, an algorithm performs a steepest ascent search for the PAE optimum load reflection coefficient, followed by a steepest descent search for ACPR. The steepest descent search, when begun at the PAE optimum, approximates the Pareto optimal frontier between the two objectives. This trace enables PAE to be maximized for an imposed limit on ACPR, optimizing the performance of adaptive radar transmitters under spectral mask constraints.Item Algorithmic specified complexity.(2013-09-24) Ewert, Winston.; Marks, Robert J., II (Robert Jackson), 1950-; Electrical and Computer Engineering.; Baylor University. Dept. of Electrical and Computer Engineering.Information theory is a well developed field, but does not capture the essence of what information is. Shannon Information captures something in its definition of improbability as information. But not all improbable events convey information. Kolmogorov complexity captures the idea of information as something easily described. But not all easily described objects are information. The proposed Algorithmic Specified Complexity takes into account both Shannon Information and Kolmogorov complexity to gain a fuller evaluation of information. We demonstrate this concept and develop several examples. We show the low probability of high Algorithmic Specified Complexity. We apply the concept to both images and functional machines from the Game of Life.Item Algorithms for fast power amplifier load impedance and input power optimization using the Power Smith Tube.(2016-04-08) Barkate, Joseph G., 1991-; Baylis, Charles Passant, 1979-The increasing number of devices occupying the finite wireless broadband spectrum has led to serious concerns regarding spectral congestion. To facilitate radar and communication spectral coexistence, reconfigurable, adaptive amplifiers are expected to be a critical component in future cognitive radar transmitters. This work details a method to visualize and simultaneously optimize the load reflection coefficient and input power of a power amplifier device in order to achieve the highest possible efficiency while meeting a predefined spectral spreading constraint. The proposed vector-based search utilizes gradients as well as momentum in the Power Smith Tube in order to optimize accurately with as few experimental queries as possible. This method is proven to be feasible in higher dimensions, allowing for future implementation in real-time reconfigurable power amplifiers.Item Ambiguity function magnitude inversion and applications of morphological dilation in POCS.(2018-11-15) Yu, Albert Reynold, 1984-; Marks, Robert J., II (Robert Jackson), 1950-This dissertation examines morphological dilation for applications in Projection onto Convex Sets (POCS) as well as the inversion of ambiguity function magnitude. In general, POCS solvers implement Least-Squares (LS) algorithms which intuitively minimize the Euclidean distance or L^2-norm of a proposed solution. However, there are situations where other error metrics can be advantageous. One such metric is the weighted minimized-maximum error, or minimax which minimizes the L^∞-norm. Multiple methods for evaluating the weighted, minimax error are investigated, and this dissertation will introduced a modified alternating projections algorithm utilizing morphological dilation on context sets to solve for the minimax. This is shown to have notable improvements over standard POCS solvers for selective signal synthesis applications, including Fresnel diffraction synthesis and Computed Tomography (CT) and associative memory image reconstruction. When multiple, conflicting objective functions are present, minimax solvers can be demonstrated to be an unbiased solver among conflicting constraints, avoiding the Least-Squares tendency to shift a solution towards the centroid. In addition, the ambiguity function magnitude inversion is shown to be possible and a regularized method for quickly inverting a given function to a valid family of source signals is detailed. The ambiguity function is a fundamental aspect of radar signal processing that is frequently described as non-invertible from its magnitude as the transform is not one-to-one. In the past, an inversion to constant phase shift is possible with the full magnitude and phase of the function, but the phase information is frequently stripped as extraneous for analysis. Unfortunately this practice prevents a clear inversion. However, this paper demonstrates that an inversion to a valid spawning signal is possible, and outlines a regularized method for achieving the desired magnitude response. This will give radar designers direct control over crafting ambiguity functions with mission-critical characteristics.Item An algorithmic solution to mission planning via auto-routing algorithms.(2016-04-08) Furgerson, Jase Lloyd.; Thompson, Michael Wayne.Mission planning for radar jamming escort missions is a tedious and complex problem to solve. For years this type of mission planning has taken many hours to solve and used multiple pilots to develop a solution. This thesis discusses the development of a MATLAB solution for auto-routing aircraft for a mission planning scenario. The unique contribution of this work involves the development and implementation of an auto-router algorithm called the Augmented Mission Planning (or AMP) algorithm. The AMP algorithm is developed by combining techniques for Jamming Acceptability Region (JAR) construction, weighted map creation from DTED data, and an augmented version of the A* path finding algorithm. This auto-router preforms within a typical mission planning system framework and we demonstrate the effectiveness of this approach for determining mission planning in a timely manner.Item An electromagnetic sensor and method for extraction of transient vapor fraction in dynamic systems.(2019-11-06) Faulkner, Christopher David, 1990-; Jean, B. Randall.The capture of transient steam quality provides valuable insight into the operational conditions needed for process control and design of saturated steam systems. Acquisition of accurate fluid phase or composition before the system reaches steady-state operation poses technical challenges preventing the use of most existing commercial and experimental methods. An electromagnetic sensing method in the microwave frequency band enables this capture of compositional data at over 200 samples per second. The planar microwave sensing element allows for the in-situ measurement of a two species fluid to be taken, without the usual requirement of laminar flow found in many density-based approaches. Harsh environmental conditions presented in typical saturated steam processes dictated special design considerations to enable survivability of the sensor. Effective medium models for both pure and polluted saturated steam were implemented to compensate for contamination of the working fluid to provide estimated bounds for a mass fraction of the liquid to vapor content. The addition of pressure and temperature data enables an estimate of enthalpy made for saturated fluid cases and applications.Item An explicit electron-vibron model for olfactory inelastic electron transfer spectroscopy.(2019-04-01) Liza, Nishattasnim, 1993-; Blair, Enrique Pacis.The vibrational theory of olfaction was posited to explain subtle effects in the sense of smell inexplicable by models in which molecular structure alone determines an odorant’s smell. Amazingly, behavioral and neurophysiological evidence suggests that humans and some insects can be trained to distinguish isotopologue molecules related by isotope substitution. How is it possible to smell a neutron? Inelastic electron transfer spectroscopy (IETS) is a proposed mechanism to explain such subtle olfactory effects: the vibrational spectrum of an appropriately-quantized odorant molecule may enhance a transfer rate in a discriminating electron transfer (ET) process. In contrast to existing models of olfactory IETS, the model presented here explicitly treats the dynamics of the dominant odorant vibrational mode. Power is dissipated directly from electron to environment and indirectly via damped odorant vibrations. The spectroscopic behavior in ET rate is unmasked if the direct-path dissipation is negligible. This may support olfactory isotopomer discrimination.Item An investigation of observed Algorithmic Specified Complexity.(2017-11-16) Nemati, David C., 1989-; Marks, Robert J., II (Robert Jackson), 1950-Two experiments were carried out to investigate how Algorithmic Specified Complexity (ASC) might serve as a tool, specifically in the area of classification AI, and how well the theory around it predicts the characteristics of random numbers. One evaluated an approach to measuring ASC in pictures by how well it helped in classification, and the other compared predictions and observations of the compressibility of random bitstrings. The ASC of MNIST pictures was estimated by saving concatenations of samples as PNG. The expected ASC of random bitstrings was compared to average observed ASC (OASC) values from LZ78 Huffman codes. Observed ASC of MNIST pictures helped to identify them, and as predicted, expectations of ASC were higher than those of OASC. ASC shows value in AI applications, and while generic compression algorithms show some promise, the best way to measure ASC is by functionality.Item Application of coordinated control strategies to tubular solid oxide fuel cell models.(2019-07-17) Holden III, Joseph Elliott, 1993-; Lee, Kwang Y.Solid oxide fuel cell (SOFC) power plants have been demonstrated to produce power efficiently in theory and in practice. However, popular control methods have not accounted for controlling the SOFC and the connecting power inverter in tandem. In addition, the literature often used an elegant but erroneous model to test SOFC control methods. Inspired by classical control of conventional power plants, this paper develops coordinated controls for a corrected simple model and a separate detailed model. Testing these models with these controls results in satisfactory performance comparable to the original tests with the original model.Item Applied IMU image registration for super resolution on mobile devices.(2017-03-29) Hartwig, Tyler, 1994-; Schubert, Keith Evan.Mobile phones and cameras are incredibly popular and the hardware is becoming very impressive. The photos these devices are currently able to take are already of high quality, however it is possible to improve these cameras in software. It is possible to take burst-shot photos and utilize the phase offsets to realize a higher resolution signal. While this takes a large amount of computation, it is possible to reduce that computation by using the IMU devices on mobile phones. This research explores that idea, as well as investigating what signal resolving algorithms produce the highest quality image in combination with the IMU data. IMU sensors are shown to help in reducing the time it takes to register photos to sub-pixel accuracy. It is also shown that the results by using the sensors are comparable to not using these sensors.Item Artificial materials and the Zenneck surface wave.(2020-11-23) Brighton, David A., 1996-; Jean, B. Randall.Spatial control of electromagnetic energy has, and will continue to be, one of the preeminent factors in any electromagnetic design. This control is made possible by energy storage, which in turn comes about as a result of geometry and material properties. The end goal of the manipulation of fields is, however, severely limited by natural material properties. As a result, artificial materials have been extensively researched. New use cases, nevertheless, will be created that require original or more specific analysis. One such area is the launching of the Zenneck surface wave. The use of anisotropic high permeability materials is suggested as a means to achieve modal matching. Similar research in artificial material has been aimed mainly at either low to negative anisotropic, or high isotropic permeabilities. The resulting void must therefore be addressed. This thesis provides an analysis of the surface mode and anisotropic high permeability use case for the purpose of launching a Zenneck surface wave.Item Asynchronous image reconstruction.(2021-12-13) Cai, Ritchie Zongqi, 1982-; Schubert, Keith Evan.Algebraic Reconstruction Technique, also known as ART, is the go-to method for medical image reconstruction. For more than 50 years, since the original paper about ART is published, various reconstruction methods based on ART emerged for faster runtime performance. These methods are designed to suit different types of hardware. However, none of these methods is ART equivalent. In this work, I introduce a new implementation method that is ART equivalent, has a very fast runtime performance, and is very scalable on today and future hardware. It opens a brand new door to how we should implement ART in the future.Item Automated medical image segmentation.(2017-12-04) Nguyen, Hanh Hong, 1991-; Schubert, Keith Evan.Computed Tomography (CT) is one of the most common medical diagnostic imaging techniques. Since the first clinical CT scanner was installed in the 1970s, there are about 30,000 CT scanners installed worldwide. Despite of the vast number of scanners and the improvement in image quality, the demand of accuracy in differentiating different region and type of tissue in the treatment area of the patient body is still remains. Some materials are easy to identify while some are not due to their thin shape and/or the limited resolution of the scans. This thesis addresses the problem by investigating several image segmentation techniques to achieve fast performance and better quality tissue assignment.Item Brillouin and transverse mode instabilities in fiber amplifiers for high-energy laser systems.(December 2022) Young, Joshua T., 1995-; Hu, Jonathan.High-energy fiber lasers have developed a lot of interest due to their applications in industry, medicine, and defense. Recent advances enabled an explosive growth in operating power to the scale of multi-kilowatts. However, nonlinear effects such as the Brillouin instability (BI) and the transverse mode instability (TMI) impose limits on the power of high-energy fiber amplifiers. This dissertation focuses on the theoretical modeling of these nonlinear effects. The goal is to model these effects and further propose new mitigation techniques to increase the operating powers and advance the techniques for high-energy fiber amplifiers. The nonlinear effects in optical fibers often involve mode coupling. Avoided crossings occur when two modes are strongly coupled to each other and share similar propagation constants. We start with a tutorial to study avoided crossings in one-dimensional slab waveguides in both index guiding and antiresonant waveguides. We use simple one-dimensional slab waveguides as examples to illustrate the physics and properties of avoided crossings in more complicated specialty optical fibers. We study the TMI in an Yb-doped fiber amplifier in the presence of a single higher-order mode (HOM). Current modeling techniques for TMI require that the longitudinal discretization be substantially smaller than the beat length between the fundamental mode and HOM. We formulate the phase-matched model for TMI, which only considers the phase-matched terms that contribute to the coupling between the fundamental mode and HOMs. By doing so, the number of sections in the longitudinal discretization may be greatly decreased, which leads to a large computational win with no loss of accuracy. The BI may be modeled as a three-wave mixing process where two optical modes interact with a resonant acoustic mode. We consider phase modulation of the input pump as a suppression technique for BI. We show that piecewise parabolic phase waveforms like sawtooth and triangle phase may provide larger power thresholds compared to that of the more commonly used pseudorandom bitstream (PRBS) modulation. Because of the nearly rectangular spectrum associated with piecewise parabolic phase modulation, these modulation schemes are better fitted for power scaling such as spectral beam combining. Recently, our piecewise parabolic phase idea that was published was experimentally demonstrated. We further consider a single computational model that models BI and TMI together. A multi-time-scale approach must be used since these nonlinear effects evolve over drastically different time scales. Both BI and TMI depend differently on the core diameter of the fiber. At and under the pump power threshold for the combined BI-TMI model, the pump power threshold closely follows that of the individual BI and TMI models. However, BI may trigger TMI when strong BI leads to stochastic oscillations in the fundamental mode amplitude. This feature cannot be predicted by modeling either BI or TMI alone. At the end, we discuss the future prospects for high-energy laser fiber amplifiers and give a summary.Item Calibration methodology for a microwave non-invasive glucose sensor.(2008-06-09T15:41:02Z) McClung, Melanie J.; Jean, B. Randall.; Engineering.; Baylor University. Dept. of Electrical and Computer Engineering.Non-invasive measuring techniques for determining biological parameters are more heavily researched with the growth of the biomedical industry. One of the top areas in non-invasive research deals with diabetes. This disease affects more than 20 million people in the United States, and there is an increasing desire to find a testing process that is non-invasive, easy to use, and safe for users. Microwave technology has improved greatly during recent years and is now seen more often in conjunction with biomedical research. Microwaves are capable of taking measurements of materials inside of a closed volume without the need to come into contact with the material. This makes them ideal for measuring biological parameters, specifically glucose concentrations in the blood. This thesis expands on the development of a microwave sensor to non-invasively measure blood glucose levels and will examine the possibility of developing a calibration for a device using the microwave sensor.