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Title: A MACHINE LEARNING APPROACH FOR OCEAN EVENT MODELING AND PREDICTION.
Creator: Muhamed, Ali Ali Abdullateef, Zhuang, Hanqi, Florida Atlantic University, Department of Computer and Electrical Engineering and Computer Science, College of Engineering and Computer Science
Abstract/Description: In the last decade, deep learning models have been successfully applied to a variety of applications and solved many tasks. The ultimate goal of this study is to produce deep learning models to improve the skills of forecasting ocean dynamic events in general and those of the Loop Current (LC) system in particular. A specific forecast target is to predict the geographic location of the (LC) extension and duration, LC eddy shedding events for a long lead time with high accuracy. Also, this...
Show moreIn the last decade, deep learning models have been successfully applied to a variety of applications and solved many tasks. The ultimate goal of this study is to produce deep learning models to improve the skills of forecasting ocean dynamic events in general and those of the Loop Current (LC) system in particular. A specific forecast target is to predict the geographic location of the (LC) extension and duration, LC eddy shedding events for a long lead time with high accuracy. Also, this study aims to improve the predictability of velocity fields (or more precisely, velocity volumes) of subsurface currents. In this dissertation, several deep learning based prediction models have been proposed. The core of these models is the Long-Short Term Memory (LSTM) network. This type of recurrent neural network is trained with Sea Surface Height (SSH) and LC velocity datasets. The hyperparameters of these models are tuned according to each model's characteristics and data complexity. Prior to training, SSH and velocity data are decomposed into their temporal and spatial counterparts.A model uses the Robust Principle Component Analysis is first proposed, which produces a six-week lead time in forecasting SSH evolution. Next, the Wavelet+EOF+LSTM (WELL) model is proposed to improve the forecasting capability of a prediction model. This model is tested on the prediction of two LC eddies, namely eddy Cameron and Darwin. It is shown that the WELL model can predict the separation of both eddies 10 and 14 weeks ahead respectively, which is two more weeks than the DAC model. Furthermore, the WELL model overcomes the problem due to the partitioning step involved in the DAC model. For subsurface currents forecasting, a layer partitioning method is proposed to predict the subsurface field of the LC system. A weighted average fusion is used to improve the consistency of the predicted layers of the 3D subsurface velocity field. The main challenge of forecasting of the LC and its eddies is the small number of events that have occurred over time, which is only once or twice a year, which makes the training task difficult. Forecasting the velocity of subsurface currents is equally challenging because of the limited insitu measurements.
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Date Issued: 2021
PURL: http://purl.flvc.org/fau/fd/FA00013727
Subject Headings: Machine learning, Loop Current, Oceanography--Forecasting
Format: Document (PDF)

Title: CYBER-PHYSICAL SYSTEMS: BUILDING A SECURITY REFERENCE ARCHITECTURE FOR CARGO PORTS.
Creator: Romero, Virginia Mendiola, Fernandez, Eduardo B., Florida Atlantic University, Department of Computer and Electrical Engineering and Computer Science, College of Engineering and Computer Science
Abstract/Description: Cyber-Physical Systems (CPS) are physical entities whose operations are monitored, coordinated, and controlled by a computing and communication core. These systems are highly heterogeneous and complex. Their numerous components and cross domain complexity make attacks easy to propagate and security difficult to implement. Consequently, to secure these systems, they need to be built in a systematic and holistic way, where security is an integral part of the development lifecycle and not just...
Show moreCyber-Physical Systems (CPS) are physical entities whose operations are monitored, coordinated, and controlled by a computing and communication core. These systems are highly heterogeneous and complex. Their numerous components and cross domain complexity make attacks easy to propagate and security difficult to implement. Consequently, to secure these systems, they need to be built in a systematic and holistic way, where security is an integral part of the development lifecycle and not just an activity after development. These systems present a multitude of implementation details in their component units, so it is fundamental to use abstraction in the analysis and construction of their architecture. In particular, we can apply abstraction through the use of patterns. Pattern-based architectural modeling is a powerful way to describe the system and analyze its security and the other non-functional aspects. Patterns also have the potential to unify the design of their computational, communication, and control aspects. Architectural modeling can be performed through UML diagrams to show the interactions and dependencies between different components and its stakeholders. Also, it can be used to analyze security threats and describe the possible countermeasures to mitigate these threats. An important type of CPS is a maritime container terminal, a facility where cargo containers are transported between ships and land vehicles; for example, trains or trucks, for onward transportation, and vice versa. Every cargo port performs four basic functions: receiving, storing, staging and loading for both, import and export containers. We present here a set of patterns that describe the elements and functions of a cargo port system, and a Reference Architecture (RA) built using these patterns. We analyze and systematically enumerate the possible security threats to a container terminal in a cargo port using activity diagrams derived from selected use cases of the system. We describe these threats using misuse patterns, and from them select security patterns as defenses. The RA provides a framework to determine where to add these security mechanisms to stop or mitigate these threats and build a Security Reference Architecture (SRA) for CPS. An SRA is an abstract architecture describing a conceptual model of security that provides a way to specify security requirements for a wide range of concrete architectures. The analysis and design are given using a cargo port as our example, but the approach can be used in other domains as well. This is the first work we know where patterns and RAs are used to represent cargo ports and analyze their security.
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Date Issued: 2021
PURL: http://purl.flvc.org/fau/fd/FA00013737
Subject Headings: Cyber-physical systems, Cooperating objects (Computer systems), Container terminals
Format: Document (PDF)

Title: Studies on information-theoretics based data-sequence pattern-discriminant algorithms: Applications in bioinformatic data mining.
Creator: Arredondo, Tomas Vidal., Florida Atlantic University, Neelakanta, Perambur S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: This research refers to studies on information-theoretic (IT) aspects of data-sequence patterns and developing thereof discriminant algorithms that enable distinguishing the features of underlying sequence patterns having characteristic, inherent stochastical attributes. The application potentials of such algorithms include bioinformatic data mining efforts. Consistent with the scope of the study as above, considered in this research are specific details on information-theoretics and entropy...
Show moreThis research refers to studies on information-theoretic (IT) aspects of data-sequence patterns and developing thereof discriminant algorithms that enable distinguishing the features of underlying sequence patterns having characteristic, inherent stochastical attributes. The application potentials of such algorithms include bioinformatic data mining efforts. Consistent with the scope of the study as above, considered in this research are specific details on information-theoretics and entropy considerations vis-a-vis sequence patterns (having stochastical attributes) such as DNA sequences of molecular biology. Applying information-theoretic concepts (essentially in Shannon's sense), the following distinct sets of metrics are developed and applied in the algorithms developed for data-sequence pattern-discrimination applications: (i) Divergence or cross-entropy algorithms of Kullback-Leibler type and of general Czizar class; (ii) statistical distance measures; (iii) ratio-metrics; (iv) Fisher type linear-discriminant measure and (v) complexity metric based on information redundancy. These measures are judiciously adopted in ascertaining codon-noncodon delineations in DNA sequences that consist of crisp and/or fuzzy nucleotide domains across their chains. The Fisher measure is also used in codon-noncodon delineation and in motif detection. Relevant algorithms are used to test DNA sequences of human and some bacterial organisms. The relative efficacy of the metrics and the algorithms is determined and discussed. The potentials of such algorithms in supplementing the prevailing methods are indicated. Scope for future studies is identified in terms of persisting open questions.
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Date Issued: 2003
PURL: http://purl.flvc.org/fau/fd/FADT12057
Subject Headings: Data mining, Bioinformatics, Discriminant analysis, Information theory in biology
Format: Document (PDF)

Title: Synchronization in digital wireless radio receivers.
Creator: Nezami, Mohamed Khalid., Florida Atlantic University, Sudhakar, Raghavan, Helmken, Henry, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: Time Division Multiple Access (TDMA) architecture is an established technology for digital cellular, personal and satellite communications, as it supports variable data rate transmission and simplified receiver design. Due to transmission bandwidth restrictions, increasing user demands and the necessity to operate at lower signal-to-noise ratio (SNR), the TDMA systems employ high order modulation schemes such as M-ary Quadrature Amplitude Modulation (M-QAM) and burst transmission. Use of such...
Show moreTime Division Multiple Access (TDMA) architecture is an established technology for digital cellular, personal and satellite communications, as it supports variable data rate transmission and simplified receiver design. Due to transmission bandwidth restrictions, increasing user demands and the necessity to operate at lower signal-to-noise ratio (SNR), the TDMA systems employ high order modulation schemes such as M-ary Quadrature Amplitude Modulation (M-QAM) and burst transmission. Use of such techniques in low SNR fading channels causes degradations of carrier frequency error, phase rotation error, and symbol timing jitter. To compensate for the severe degradation due to additive white Gaussian noise (AWGN) and channel impairments, precise and robust synchronization algorithms are required. This dissertation deals with the synchronization techniques for TDMA receivers using short burst mode transmission with emphasis on preamble-less feedforward synchronization schemes. The objective is to develop new algorithms for symbol timing, carrier frequency offset acquisition, and carrier phase tracking using preamble-less synchronization techniques. To this end, the currently existing synchronization algorithms are surveyed and analyzed. The performance evaluation of the developed algorithms is conducted through Monte-Carlo simulations and theoretical analyses. The statistical properties of the proposed algorithms in AWGN and fading channels are evaluated in terms of the mean and variance of the estimated synchronization errors and their Cramer-Rao lower bounds. Based on the investigation of currently employed feedforward symbol timing algorithms, two new symbol timing recovery schemes are proposed for 16-QAM land mobile signals operating in fading channels. Both schemes achieve better performance in fading channels compared to their existing counterparts without increasing the complexity of the receiver implementation. Further, based on the analysis of currently employed carrier offset and carrier phase recovery algorithms, two new algorithms are proposed for carrier acquisition and carrier tracking of mobile satellite systems utilizing short TDMA bursts with large frequency offsets. The proposed algorithms overcome some of the conventional problems associated with currently employed carrier recovery schemes in terms of capture range, speed of convergence, and stability.
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Date Issued: 2001
PURL: http://purl.flvc.org/fcla/dt/11947
Subject Headings: Radio--Receivers and reception, Digital communications, Time division multiple access
Format: Document (PDF)

Title: Software quality modeling and analysis with limited or without defect data.
Creator: Seliya, Naeem A., Florida Atlantic University, Khoshgoftaar, Taghi M., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: The key to developing high-quality software is the measurement and modeling of software quality. In practice, software measurements are often used as a resource to model and comprehend the quality of software. The use of software measurements to understand quality is accomplished by a software quality model that is trained using software metrics and defect data of similar, previously developed, systems. The model is then applied to estimate quality of the target software project. Such an...
Show moreThe key to developing high-quality software is the measurement and modeling of software quality. In practice, software measurements are often used as a resource to model and comprehend the quality of software. The use of software measurements to understand quality is accomplished by a software quality model that is trained using software metrics and defect data of similar, previously developed, systems. The model is then applied to estimate quality of the target software project. Such an approach assumes that defect data is available for all program modules in the training data. Various practical issues can cause an unavailability or limited availability of defect data from the previously developed systems. This dissertation presents innovative and practical techniques for addressing the problem of software quality analysis when there is limited or completely absent defect data. The proposed techniques for software quality analysis without defect data include an expert-based approach with unsupervised clustering and an expert-based approach with semi-supervised clustering. The proposed techniques for software quality analysis with limited defect data includes a semi-supervised classification approach with the Expectation-Maximization algorithm and an expert-based approach with semi-supervised clustering. Empirical case studies of software measurement datasets obtained from multiple NASA software projects are used to present and evaluate the different techniques. The empirical results demonstrate the attractiveness, benefit, and definite promise of the proposed techniques. The newly developed techniques presented in this dissertation is invaluable to the software quality practitioner challenged by the absence or limited availability of defect data from previous software development experiences.
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Date Issued: 2005
PURL: http://purl.flvc.org/fcla/dt/12151
Subject Headings: Software measurement, Computer software--Quality control, Computer software--Reliability--Mathematical models, Software engineering--Quality control
Format: Document (PDF)

Title: Self-calibration of laser tracking measurement system with planar constraints.
Creator: Motaghedi, Shui Hu., Florida Atlantic University, Zhuang, Hanqi, Roth, Zvi S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: Laser tracking coordinate measuring machines have the potential of continuously measuring three dimensional target coordinates in a large workspace with a fast sampling rate and high accuracy. Proper calibration of a laser tracking measurement system is essential prior to use of such a device for metrology. In the absence of a more accurate instrument for system calibration, one has to rely on self-calibration strategies. In this dissertation, a kinematic model that describes not only the...
Show moreLaser tracking coordinate measuring machines have the potential of continuously measuring three dimensional target coordinates in a large workspace with a fast sampling rate and high accuracy. Proper calibration of a laser tracking measurement system is essential prior to use of such a device for metrology. In the absence of a more accurate instrument for system calibration, one has to rely on self-calibration strategies. In this dissertation, a kinematic model that describes not only the motion but also geometric variations of a multiple-beam laser tracking system was developed. The proposed model has the following features: (1) Target positions can be computed from both distance and angular measurements. (2) Through error analysis it was proven that even rough angular measurement may improve the overall system calibration results. A self-calibration method was proposed to calibrate intelligent machines with planar constraints. The method is also applied to the self-calibration of the laser tracking system and a standard PUMA 560 robot. Various calibration strategies utilizing planar constraints were explored to deal with different system setups. For each calibration strategy, issues about the error parameter estimation of the system were investigated to find out under which conditions these parameters can be uniquely estimated. These conditions revealed the applicability of the planar constraints to the system self-calibration. The observability conditions can serve as a guideline for the experimental setup when planar constraint is utilized in the machine calibration including the calibration of the laser tracking systems. Intensive simulation studies were conducted to check validity of the theoretical results. Realistic noise values were injected to the system models to statistically assess the behavior of the self-calibration system under real-world conditions. Various practical calibration issues were also explored in the simulations and therefore to pave ways for experimental investigation. The calibration strategies were also applied experimentally to calibrate a laser tracking system constructed at the Robotics Center in Florida Atlantic University.
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Date Issued: 1999
PURL: http://purl.flvc.org/fcla/dt/12599
Subject Headings: Robots--Kinematics, Robotics--Calibration--Measurement, Robots--Control systems
Format: Document (PDF)

Title: Software fault prediction using tree-based models.
Creator: Seliya, Naeem A., Florida Atlantic University, Khoshgoftaar, Taghi M., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: Maintaining superior quality and reliability in software systems is of utmost importance in today's world. Early fault prediction is a proven method for achieving this. Tree based modelling is a simple and effective method that can be used to predict the number of faults in a software system. In this thesis, we use regression tree based modelling to predict the number of faults in a software module. The goal of this study is four-fold. First, a comparative study of the tree based modelling...
Show moreMaintaining superior quality and reliability in software systems is of utmost importance in today's world. Early fault prediction is a proven method for achieving this. Tree based modelling is a simple and effective method that can be used to predict the number of faults in a software system. In this thesis, we use regression tree based modelling to predict the number of faults in a software module. The goal of this study is four-fold. First, a comparative study of the tree based modelling tools CART and S-PLUS. CART yielded simpler regression trees than those built by S-PLUS. Second, a comparative study of the least squares and the least absolute deviation methods of CART. It is shown that the latter yielded better results than the former. Third, a study of the possible benefits of using principal components analysis when performing regression tree modelling. The fourth and final study is a comparison of tree based modelling with other prediction techniques namely, Case Based Reasoning, Artificial Neural Networks and Multiple Linear Regression.
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Date Issued: 2001
PURL: http://purl.flvc.org/fcla/dt/12782
Subject Headings: Software measurement, Computer software--Quality control
Format: Document (PDF)

Title: Studies on Stochastic Multi-user Scheduling in Wireless Communication.
Creator: Wang, Di, Morgera, Salvatore D., Wang, Xin, Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: We developed a cross layer design which combines retransmission diversity and multi-user diversity for wireless communication. To this end, a joint design of adaptive modulation and coding with retransmission-based automatic repeat request protocol is outlined. This design is applied to devise multi-user scheduling schemes, which can optimally capture the available multi-user and retransmission diversities. In addition, the proposed on-line scheduling algorithms can operate even when the...
Show moreWe developed a cross layer design which combines retransmission diversity and multi-user diversity for wireless communication. To this end, a joint design of adaptive modulation and coding with retransmission-based automatic repeat request protocol is outlined. This design is applied to devise multi-user scheduling schemes, which can optimally capture the available multi-user and retransmission diversities. In addition, the proposed on-line scheduling algorithms can operate even when the underl ying fading channel distribution is unknown, while asymptotically converging to the offline benchmark with guarantees on prescribed fairness and rate requirements. Numerical results are provided to verify the merits of our novel schemes for multi-user transmissions over Nakagami block fading channels.
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Date Issued: 2008
PURL: http://purl.flvc.org/fau/fd/FA00012568
Subject Headings: Stochastic processes--Data processing, Wireless communication systems, Computer network protocols, Code division multiple access, Modulation (Electronics), Signal processing--Digital techniques
Format: Document (PDF)

Title: Studies on nonlinear activity and cross-entropy considerations in neural networks.
Creator: Abusalah, Salahalddin Tawfiq., Florida Atlantic University, Neelakanta, Perambur S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: The objectives of this research as deliberated in this dissertation are two-folded: (i) To study the nonlinear activity in the neural complex (real and artificial) and (ii) to analyze the learning processe(s) pertinent to an artificial neural network in the information-theoretic plane using cross-entropy error-metrics. The research efforts envisaged enclave the following specific tasks: (i) Obtaining a general solution for the Bernoulli-Riccati equation to represent a single parameter family...
Show moreThe objectives of this research as deliberated in this dissertation are two-folded: (i) To study the nonlinear activity in the neural complex (real and artificial) and (ii) to analyze the learning processe(s) pertinent to an artificial neural network in the information-theoretic plane using cross-entropy error-metrics. The research efforts envisaged enclave the following specific tasks: (i) Obtaining a general solution for the Bernoulli-Riccati equation to represent a single parameter family of S-shaped (sigmoidal) curves depicting the nonlinear activity in the neural network. (ii) Analysis of the logistic growth of output versus input values in the neural complex (real and artificial) under the consideration that the boundaries of the sets constituting the input and output entities are crisp and/or fuzzy. (iii) Construction of a set of cross-entropy error-metrics (known as Csiszar's measures) deduced in terms of the parameters pertinent to a perceptron topology and elucidation of their relative effectiveness in training the network optimally towards convergence. (iv) Presenting the methods of symmetrizing and balancing the aforesaid error-entropy measures (in the information-theoretic plane) so as to make them usable as error-metrics in the test domain. (v) Description and analysis of the dynamics of neural learning process in the information-theoretic plane for both crisp and fuzzy attributes of input values. Relevant to these topics portraying the studies on nonlinear activity and cross-entropy considerations vis-a-vis neural networks, newer and/or exploratory inferences are made, logical conclusions are enumerated and relative discussions are presented along with the scope for future research to be pursued.
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Date Issued: 1996
PURL: http://purl.flvc.org/fcla/dt/12447
Subject Headings: Neural networks (Computer science), Entropy (Information theory), Nonlinear control theory
Format: Document (PDF)

Title: Studies on modern telecommunications planning: Technoeconomical considerations and environmental issues.
Creator: Baeza, Daniel Michael., Florida Atlantic University, Neelakanta, Perambur S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: The research addressed and presented in this dissertation can be placed within the broad scope of telecommunications technoeconomics. The relevant efforts include the subject-matter of identifying the issues posed by emerging technologies, related revenue considerations and environmental issues in modern telecommunications practice specific to service providers' perspectives. The topic-wise problems studied and analyzed are as follows: (1) A comprehensive portrayal of managerial concerns and...
Show moreThe research addressed and presented in this dissertation can be placed within the broad scope of telecommunications technoeconomics. The relevant efforts include the subject-matter of identifying the issues posed by emerging technologies, related revenue considerations and environmental issues in modern telecommunications practice specific to service providers' perspectives. The topic-wise problems studied and analyzed are as follows: (1) A comprehensive portrayal of managerial concerns and considerations on the technoeconomical perspectives vis-a-vis modern telecommunications; (2) Relevant analytical studies pertinent to: (1) "Greenfield starts" in a fresh, telecommunications deployment in a virgin service zone; (2) Embedded architectures; (3) Technology enhancements; (4) Environmental issues. The greenfield effort is analyzed to portray the feasibility of achieving technoeconomically optimal alternative designs. The embedded architecture refers to the prevailing infrastructure and their optimal usage is indicated via an arbitrated traffic-sharing technique. Concerning technology enhancements, "all-optical" technology is indicated as the ultimate goal. However, in the interim period, the optimal use of transitory technology such xDSL, MPLS, and others, is suggested and studied. Lastly, the environmental implications that coexist with technoeconomical impacts on modern telecommunications deployment are analyzed.
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Date Issued: 2000
PURL: http://purl.flvc.org/fcla/dt/12655
Subject Headings: Telecommunication systems--Management, Engineering economy, Telecommunication systems--Environmental aspects
Format: Document (PDF)

Title: Studies on transreceive diversity schemes (including "polarization-sense" antenna diversity) for wireless communication systems.
Creator: Preedalumpabut, Wichean., Florida Atlantic University, Neelakanta, Perambur S., Morgera, Salvatore D., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: The research addressed in this study and deliberated in the dissertation is broadly tied to finding hybrid methods of diversity compatible for modern wireless applications. The hybrid strategy advocated thereof involves a combined use of space- (antenna and polarization), frequency-, and time-diversity schemes in a judicious manner so as to realize a desirable BER versus Eb/No performance across RF links that face multipath and other unwanted EM artifacts. The underlying reason for the hybrid...
Show moreThe research addressed in this study and deliberated in the dissertation is broadly tied to finding hybrid methods of diversity compatible for modern wireless applications. The hybrid strategy advocated thereof involves a combined use of space- (antenna and polarization), frequency-, and time-diversity schemes in a judicious manner so as to realize a desirable BER versus Eb/No performance across RF links that face multipath and other unwanted EM artifacts. The underlying reason for the hybrid scheme as above is to replace multiple-antenna based transreceive diversity. Such multiple antennas would otherwise require large base station real estate and may not be compatible for hand-held (space-constrained) RF units. On the contrary, use of hybrid schemes would restrict multiple number of antennas and conserves the space. After analyzing a set of plausible techniques of hybrid diversity compatible for modern wireless techniques, a focused study has been done on polarization-sense (PS) antenna diversity scheme. Its fruitful application for indoor systems (like Bluetooth(TM)/ZigBee(TM)) against multipath effects is demonstrated via simulation and experimental studies. Further, the PS-antenna diversity is shown to offer improved BER versus Eb/N o performance in pilot channels used in CDMA2000 systems. Also, such PS-diversity is shown to help improving the GPS receiver performance under RFI/jamming environment. The technique and heuristics proposed towards the PS-antenna diversity scheme imply novel and hitherto unexplored efforts in wireless communications. Lastly the dissertation concludes summarizing the results and offers open-questions for further studies.
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Date Issued: 2004
PURL: http://purl.flvc.org/fcla/dt/12104
Subject Headings: Wireless communication systems, Antennas (Electronics)
Format: Document (PDF)

Title: Submicron CAD design and analysis of MOS Current Mirrors.
Creator: Rivas-Torres, Wilfredo, Florida Atlantic University, Roth, Zvi S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: Current Mirrors are widely used circuits in IC designs. They are used as current sources and loads. The proper selection of a Current Mirror configuration is therefore important. This thesis reviews critical parameters for Current Minors characterization. Six MOS Current Mirror configurations are studied, and their performance characteristics are compared. The proper selection and use of MOSFET models are presented. It is shown that CAD-based design and analysis is indispensable if realistic...
Show moreCurrent Mirrors are widely used circuits in IC designs. They are used as current sources and loads. The proper selection of a Current Mirror configuration is therefore important. This thesis reviews critical parameters for Current Minors characterization. Six MOS Current Mirror configurations are studied, and their performance characteristics are compared. The proper selection and use of MOSFET models are presented. It is shown that CAD-based design and analysis is indispensable if realistic MOS models such as BSIM3 are used. The CAD based analysis and design employs simulation parameter tuning, optimization and swept parameters. The presented CAD techniques allow a designer to make important tradeoffs for different configurations. One of the main thesis observations is that it is not always necessary to use more involved Current Mirror configurations; a Simple Current Mirror Configuration is often sufficient. The thesis also studies the adverse effects on the design caused by process variations.
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Date Issued: 2004
PURL: http://purl.flvc.org/fcla/dt/13119
Subject Headings: Metal oxide semiconductors--Computer-aided design, Integrated circuits, Metal oxide semiconductor field-effect transistors
Format: Document (PDF)

Title: Studies on carrier-free (or ultra-wideband) radar performance under clutter and stealth-target environments.
Creator: Mendivil, Edwin David., Florida Atlantic University, De Groff, Dolores F., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: This thesis is concerned with the use of ultra-wideband radar detection specific to the following target and background considerations. (1) Statistical attributes of the RCS models of stealth-targets illuminated by ultra-wideband radars. (2) Analysis of radar echo signatures of low flying stealth-targets with a background of sea-clutter and illuminated by an ultra-wideband radar. (3) Analysis of impulse echoes from simple (planar) surface(s) coated with a radar absorbing material (RAM). The...
Show moreThis thesis is concerned with the use of ultra-wideband radar detection specific to the following target and background considerations. (1) Statistical attributes of the RCS models of stealth-targets illuminated by ultra-wideband radars. (2) Analysis of radar echo signatures of low flying stealth-targets with a background of sea-clutter and illuminated by an ultra-wideband radar. (3) Analysis of impulse echoes from simple (planar) surface(s) coated with a radar absorbing material (RAM). The first problem refers to the elucidation of Swerling-Marcum type classifications of RCS fluctuation(s) to characterize the stochastical aspects of the echoes from stealth-targets illuminated by an impulse from an ultra-wideband radar. In the second analysis, performance of a radar receiver configuration, using the log-likelihood function of the signal received from a stealth target flying at low altitude over the sea-surface is predicted. The third effort addressed provides analytical representations in time-domain of echoes from planar surface(s) coated with RAM's for normal incidence of ultra-wideband short pulse illumination.
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Date Issued: 1996
PURL: http://purl.flvc.org/fcla/dt/15278
Subject Headings: Radar, Signal processing, Radar cross sections, Stealth aircraft
Format: Document (PDF)

Title: Structure and motion estimation from image sequences.
Creator: Shieh, Jen-yu., Florida Atlantic University, Zhuang, Hanqi, Sudhakar, Raghavan, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: The objective of this dissertation is to develop effective algorithms for estimating the 3-D structure of a scene and its relative motion with respect to a camera or a pair of cameras from a sequence of images acquired by the cameras, under the assumption that the relative motion of the camera is small from one frame to another. This dissertation presents an approach of computing depth maps from an image sequence, which combines the direct depth estimation method with the optical flow based...
Show moreThe objective of this dissertation is to develop effective algorithms for estimating the 3-D structure of a scene and its relative motion with respect to a camera or a pair of cameras from a sequence of images acquired by the cameras, under the assumption that the relative motion of the camera is small from one frame to another. This dissertation presents an approach of computing depth maps from an image sequence, which combines the direct depth estimation method with the optical flow based method. More specifically, optical flow on and near moving edges are computed using a correlation technique. The optical flow information is then fused with the gradient information to estimate depth not only on moving edges but also in internal regions. Depth estimation is formulated as a discrete Kalman filter problem and is solved in three stages. In the prediction stage, the depth map estimated for the previous frame, together with knowledge of the camera motion, is used to predict the depth variance at each pixel in the current frame. In the estimation stage, a vector-version of Kalman filter formulation is adapted and simplified to refine the predicted depth map. The resulting estimation algorithm takes into account the information from the neighboring pixels, and thus is much more robust than the scalar-version Kalman filter implementation. In the smoothing stage, morphological filtering is applied to reduce the effect of measurement noise and fill in uncertain areas based on the error covariance information. Since the depth at each pixel is estimated locally, the algorithm presented in this paper can be implemented on a parallel computer. The performance of the presented method is assessed through simulation and experimental studies. A new approach for motion estimation from stereo image sequences is also proposed in this dissertation. First a stereo motion estimation model is derived using the direct dynamic motion estimation technique. The problem is then solved by applying a discrete Kalman filter that facilitates the use of a long stereo image sequence. Typically, major issues in such an estimation method are stereo matching, temporal matching, and noise sensitivity. In the proposed approach, owing to the use of temporal derivatives in the motion estimation model, temporal matching is not needed. The effort for stereo matching is kept to a minimum with a parallel binocular configuration. Noise smoothing is achieved by the use of a sufficiently large number of measurement points and a long sequence of stereo images. Both simulation and experimental studies have also been conducted to assess the effectiveness of the proposed approach.
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Date Issued: 1992
PURL: http://purl.flvc.org/fcla/dt/12320
Subject Headings: Three-dimensional display systems, Imaging systems, Photography, Stereoscopic, Imaging transmission
Format: Document (PDF)

Title: Stochastical aspects of neuronal activity, neural networks, and communication.
Creator: De Groff, Dolores F., Florida Atlantic University, Neelakanta, Perambur S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: By revisiting the popular framework of depicting neuronal (collective) activities as analogous to Ising's spin-glass theory of interacting magnetic spins, the contradictions that coexist with such an analogy are extracted and discussed. To alleviate such contradictions, an alternative strategy of equating the neuronal interactions to the partially anisotropic nematic phase of disorder pertaining to liquid crystals is proposed. Hence, the extent of anisotropy in the neuronal system, quantified...
Show moreBy revisiting the popular framework of depicting neuronal (collective) activities as analogous to Ising's spin-glass theory of interacting magnetic spins, the contradictions that coexist with such an analogy are extracted and discussed. To alleviate such contradictions, an alternative strategy of equating the neuronal interactions to the partially anisotropic nematic phase of disorder pertaining to liquid crystals is proposed. Hence, the extent of anisotropy in the neuronal system, quantified in terms of an order-function, is specified to elucidate the nonlinear squashing action of the input-output relations in a neuronal cell. The relevant approach thereof, is based on Langevin's theory considerations as applied to dipole molecules. Further, in view of the stochastical properties due to the inherent disorder associated with the neuronal assembly, the progression of state-transitions across the interconnected cells is modeled as a momentum flow relevant to particle dynamics. Hence, corresponding wave mechanics attributions of such a collective movement of state-transition activity are described in terms of a probabilistic wave function. Lastly, the stochastical aspects of noise-perturbed neuronal dynamics are studied via Fokker-Planck equation representing the Langevin-type relaxational (nonlinear) process associated with the neuronal states. On each of these topics portraying the stochastical characteristics of the neuronal assembly and its activities, newer and/or more exploratory inferences are made, logical conclusions are enumerated and relevant discussions are presented along with the scope for future research to be pursued.
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Date Issued: 1993
PURL: http://purl.flvc.org/fcla/dt/12326
Subject Headings: Neurons--Mathematical models, Stochastic processes, Neural networks (Computer science)
Format: Document (PDF)

Title: Stochastical and neuromimetic aspects of modeling electromagnetic composite materials.
Creator: Park, Joseph C., Florida Atlantic University, Neelakanta, Perambur S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: This dissertation is concerned primarily with the analytical modeling of a class of electromagnetic composite materials using the concepts of stochastical mixture theory, principles of electromagnetics and neuromimetic considerations. The global behavior of the test composite is ascertained in terms of the constitutive relations of the material parameters (having stochastical attributions) and the intramaterial hierarchy is modeled as massively interconnected, interacting units depicting such...
Show moreThis dissertation is concerned primarily with the analytical modeling of a class of electromagnetic composite materials using the concepts of stochastical mixture theory, principles of electromagnetics and neuromimetic considerations. The global behavior of the test composite is ascertained in terms of the constitutive relations of the material parameters (having stochastical attributions) and the intramaterial hierarchy is modeled as massively interconnected, interacting units depicting such systems as mimetics of neural networks. Pertinent research efforts enclave the following specific tasks: (i) Modeling a multi-constituent electromagnetic composite medium in terms of the characteristics of its individual constituents and their spatial (random or orderly) dispositions. (ii) Assessment of nonspherical particulate effects (in terms of the stochastical attributes) on the global response of such composite materials. (iii) Evaluation of interparticle interactions and their implicit effects on the effective electromagnetic properties of the composite media. (iv) Assaying the transitional behavior of the test composites and, (v) modeling electromagnetic composites as neuromimetics correlating their effective material characteristics to the corresponding state-transitional response of a massively interconnected neural network. Results arising from these theoretical considerations are compared with data compiled via experimental studies performed (where feasible) or otherwise correlated with theoretical and/or experimental results available elsewhere in the literature. Specific experimental efforts carried out refer to piezoelectric rubber composites and their application in controlling acoustic beamforming via electrical 'pinch off' (which mimics the inhibitory response in a neuronal cell); as well as exclusive experimental tasks to verify the transitional lossy behavior model developed presently using a set of fast-ion conductor composites and dielectric-plus-conductor mixtures. Lastly, inferential conclusions are presented and discussed with an outline on the scope of extensions to the present work.
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Date Issued: 1994
PURL: http://purl.flvc.org/fcla/dt/12359
Subject Headings: Composite materials--Electric properties, Composite materials--Magnetic properties, Stochastic processes
Format: Document (PDF)

Title: Software development for ecological data systems.
Creator: Lostal, Sergio L., Florida Atlantic University, Larrondo-Petrie, Maria M., Solomon, Martin K., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: Software development for ecological data systems is concentrated in the description, modeling, and standardization of large amounts of ecological data. Ecological data assembled in many formats is very difficult to reuse. This thesis develops a database model that supports the storage of heterogeneous data in standardized formats. Ecological data standardization is solved with the specification of a structure conversion system. Because input formats cannot be predicted, a scientific data...
Show moreSoftware development for ecological data systems is concentrated in the description, modeling, and standardization of large amounts of ecological data. Ecological data assembled in many formats is very difficult to reuse. This thesis develops a database model that supports the storage of heterogeneous data in standardized formats. Ecological data standardization is solved with the specification of a structure conversion system. Because input formats cannot be predicted, a scientific data description language was created to control the execution of the conversion system. System analysis is based on interviews with South Florida Water Management District scientists conducting ecosystem research, and ecological data collected at Lake Okeechobee, Florida, during a five-year study. Object-oriented and structural methods were used for analysis. Development is complemented with an introduction to user interfaces.
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Date Issued: 1996
PURL: http://purl.flvc.org/fcla/dt/15344
Subject Headings: Ecology--Data processing, Information storage and retrieval systems--Ecology, Okeechobee, Lake (Fla)
Format: Document (PDF)

Title: Simulation of autonomous knowledge-based navigation in unknown two-dimensional environment with polygonal obstacles.
Creator: McKendrick, John DeMilly., Florida Atlantic University, Cheng, Linfu, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: The problem of finding optimal paths for a robot navigating in an environment where the position of each obstacle is precisely known has received much attention in the literature, however, the majority of applications problems for a robot would require it to navigate in a completely unknown. This paper focuses on an approach to solving the problem of robot navigation in an unknown, unstructured, two-dimensional environment where the positions of the polygonal obstacles were fixed in time. Few...
Show moreThe problem of finding optimal paths for a robot navigating in an environment where the position of each obstacle is precisely known has received much attention in the literature, however, the majority of applications problems for a robot would require it to navigate in a completely unknown. This paper focuses on an approach to solving the problem of robot navigation in an unknown, unstructured, two-dimensional environment where the positions of the polygonal obstacles were fixed in time. Few studies have reported on the utilization of an expert system to govern robot motion. This study relied on a knowledge-based expert system that interacted with lower-level procedures to carry out path finding and exploration functions. The expert-system shell used was OPS5 which ran on top of Lisp.
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Date Issued: 1988
PURL: http://purl.flvc.org/fcla/dt/14496
Subject Headings: Robots--Motion, Expert systems (Computer science), Robots--Motion--Computer simulation
Format: Document (PDF)

Title: Simulation-based performance evaluation of packet-switched H.264/AVC video streaming on WCDMA networks.
Creator: Murillo, Carlos A., Florida Atlantic University, Iskander, Cyril-Daniel, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: This thesis presents the simulation based performance evaluation on the transmission of multimedia services (H.264/AVC video streaming) to a mobile user over a packet-switched wireless network based on the WCDMA standard. The H.264/AVC refers to the codec, which is used as the main tool for video compression. It enables the transport of high bandwidth video data over Third Generation (3G) wireless systems by offering a high video compression rate, adaptability to the channel, and error...
Show moreThis thesis presents the simulation based performance evaluation on the transmission of multimedia services (H.264/AVC video streaming) to a mobile user over a packet-switched wireless network based on the WCDMA standard. The H.264/AVC refers to the codec, which is used as the main tool for video compression. It enables the transport of high bandwidth video data over Third Generation (3G) wireless systems by offering a high video compression rate, adaptability to the channel, and error resilience. It is transported using the RTP/UDP/IP protocol stack over the 3G wireless system. The WCDMA technology is simulated with special emphasis on the upper layers of the wireless channel. The performance of the WCDMA system is studied when transporting RTP/UDP/IP packets of H.264/AVC compressed video data under diverse configuration scenarios, namely, ARQ schemes and variable length of the transmitted frame at the link layer. These components of a packet-switched streaming service are integrated into a software simulation model, which is used to evaluate the end-to-end H.264/AVC video quality in a WCDMA wireless network.
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Date Issued: 2005
PURL: http://purl.flvc.org/fcla/dt/13291
Subject Headings: Wireless communication systems, Mobile communication systems, Global system for mobile communications, Code division multiple access, Streaming technology (Telecommunications)
Format: Document (PDF)

Title: THE STEP RECOVERY DIODE WITH APPLICATIONS AS A FREQUENCY MULTIPLIER.
Creator: STROBEL, RUSSELL ALAN., Florida Atlantic University, Gazourian, Martin G., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description: Portable UHF transceivers typically require minimal current drain frequency converters to multiply the frequencies generated by crystal controlled oscillators up to the UHF band. The step recovery diode (SRD) provides an approach to frequency multiplication that requires no d.c. bias and hence minimizes battery drain. This thesis compares the SRD to the more conventional varactor and analyzes SRD device physics and characteristics. SRD operation is explained in terms of the conduction and...
Show morePortable UHF transceivers typically require minimal current drain frequency converters to multiply the frequencies generated by crystal controlled oscillators up to the UHF band. The step recovery diode (SRD) provides an approach to frequency multiplication that requires no d.c. bias and hence minimizes battery drain. This thesis compares the SRD to the more conventional varactor and analyzes SRD device physics and characteristics. SRD operation is explained in terms of the conduction and depletion intervals. The rapid transition from the conduction to the depletion mode allows the SRD to generate high order harmonics of the input frequency. A step-by-step design procedure for a series mode frequency multiplier is presented and empirical observations are used to help explain multiplier operation. The jump phenomena and hysteresis effects previously unexplained in relation to SRD multipliers are explored. Finally, it is shown that the SRD can function as a parametric amplifier.
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Date Issued: 1979
PURL: http://purl.flvc.org/fcla/dt/13970
Subject Headings: Diodes, Switching, Diodes, Semiconductor
Format: Document (PDF)

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