Engineering Commons^™

Evaluation Of A Microwave Radiative Transfer Model For Calculating Sat, Simonetta Thompson

Electronic Theses and Dissertations

Remote sensing is the process of gathering and analyzing information about the earth's ocean, land and atmosphere using electromagnetic "wireless" techniques. Mathematical models, known as Radiative Transfer Models (RTM), are developed to calculate the observed radiance (brightness temperature) seen by the remote sensor. The RTM calculated brightness temperature is a function of fourteen environmental parameters, including atmospheric profiles of temperature, pressure and moisture, sea surface temperature, and cloud liquid water. Input parameters to the RTM model include data from NOAA Centers for Environmental Prediction (NCEP), Reynolds weekly Sea Surface Temperature and National Ocean Data Center (NODC) WOA98 Ocean Salinity and …

Circuit Design And Reliability Of A Cmos Receiver, Hong Yang

Electronic Theses and Dissertations

This dissertation explores CMOS RF design and reliability for portable wireless receivers. The objective behind this research is to achieve an increase in integration level, and gain more understanding for RF reliability. The fields covered include device, circuit and system. What is under investigation is a multi-band multi-mode receiver with GSM, DCS-1800 and CDMA compatibility. To my understanding, GSM and CDMA dual-mode mobile phones are progressively investigated in industries, and few commercial products are available. The receiver adopts direct conversion architecture. Some improved circuit design methods are proposed, for example, for low noise amplifier (LNA). Except for band filters, local …

General Interference Suppression Technique For Diversity Wireless Rece, Tianyu Yang

Electronic Theses and Dissertations

The area of wireless transceiver design is becoming increasingly important due to the rapid growth of wireless communications market as well as diversified design specifications. Research efforts in this area concentrates on schemes that are capable of increasing the system capacity, providing reconfigurability/reprogrammability and reducing the hardware complexity. Emerging topics related to these goals include Software Defined Radio, Multiple-Input-Multiple-Output (MIMO) Systems, Code Division Multiple Access, Ultra-Wideband Systems, etc. This research adopts space diversity and statistical signal processing for digital interference suppression in wireless receivers. The technique simplifies the analog front-end by eliminating the anti-aliasing filters and relaxing the requirements for …

Modeling And Analysis Of Solar Arrays For Grid Connected Systems With Maximum Power Point Tracking, Adje Mensah

HIM 1990-2015

The shrinking of the world’s energy sources has prompted an unprecedented interest in renewable and clean energy sources such as photovoltaic (solar) array. Already popular in space and some industrial power system applications, photovoltaic arrays have yet to become a viable source of energy for most terrestrial applications. For several decades now, engineers have been striving to design reliable and affordable solar array based power systems. One popular approach to achieve reliability is the integration of Maximum Power Point Tracking (MPPT) technology in solar power system design. The purpose of this study was to gain more insight into the nature …

Conformal Tracking For Virtual Environments, Larry Dennis Davis Jr.

Electronic Theses and Dissertations

A virtual environment is a set of surroundings that appears to exist to a user through sensory stimuli provided by a computer. By virtual environment, we mean to include environments supporting the full range from VR to pure reality. A necessity for virtual environments is knowledge of the location of objects in the environment. This is referred to as the tracking problem, which points to the need for accurate and precise tracking in virtual environments. Marker-based tracking is a technique which employs fiduciary marks to determine the pose of a tracked object. A collection of markers arranged in a rigid …

Analysis Of Time Synchronization Errors In High Data Rate Ultrawideban, Lakesha Bates

Electronic Theses and Dissertations

Emerging Ultra Wideband (UWB) Orthogonal Frequency Division Multiplexing (OFDM) systems hold the promise of delivering wireless data at high speeds, exceeding hundreds of megabits per second over typical distances of 10 meters or less. The purpose of this Thesis is to estimate the timing accuracies required with such systems in order to achieve Bit Error Rates (BER) of the order of magnitude of 10-12 and thereby avoid overloading the correction of irreducible errors due to misaligned timing errors to a small absolute number of bits in error in real-time relative to a data rate of hundreds of megabits per second. …

Finite Element Analysis Of Left-Handed Waveguides, Balasubramaniam, Vellakkinar

Electronic Theses and Dissertations

In this work, waveguides with simultaneous negative dielectric permittivity and magnetic permeability, otherwise known as left-handed waveguides, are investigated. An approach of formulating and solving an eigenvalue problem with finite element method resulting in the dispersion relation of the waveguides is adopted in the analysis. Detailed methodology of one-dimensional scalar and two-dimensional vector finite element formulation for the analysis of grounded slab and arbitrary shaped waveguides is presented. Based on the analysis, for waveguides with conventional media, excellent agreement of results is observed between the finite element approach and the traditional approach. The method is then applied to analyze left-handed …

Hybrid And Hierarchical Image Registration Techniques, Dongjiang Xu

Electronic Theses and Dissertations

A large number of image registration techniques have been developed for various types of sensors and applications, with the aim to improve the accuracy, computational complexity, generality, and robustness. They can be broadly classified into two categories: intensity-based and feature-based methods. The primary drawback of the intensity-based approaches is that it may fail unless the two images are misaligned by a moderate difference in scale, rotation, and translation. In addition, intensity-based methods lack the robustness in the presence of non-spatial distortions due to different imaging conditions between images. In this dissertation, the image registration is formulated as a two-stage hybrid …

Stable Spatial Solitons In Semiconductor Optical Amplifiers, Erdem Ultanir

Electronic Theses and Dissertations

A spatial soliton is a shape invariant self guided beam of light or a self induced waveguide. Spatial solitons appear as a result of the balance of diffraction and nonlinear focusing in a system. They have been observed in many different conservative media in the last couple of years. Solitons are ubiquitous, because of the probability of using their interactions in optical data processing, communications etc. Up to now due to the power required to generate the solitons, and the response times of the soliton supporting media, these special waves of nature could not penetrate the applications arena. Semiconductors, with …

Nonlinear Adaptive Estimation Andits Application To Synchronization Of Lorenz System, Yufang Jin

Electronic Theses and Dissertations

Synchronization and estimation of unknown constant parameters for Lorenz-type transmitter are studied under the assumption that one of the three state variables is not transmitted and that transmitter parameters are not known apriori. An adaptive algorithm is proposed to estimate both the state and system parameters. Since Lorenz system shows the property of sensitivity to initial conditions and evolves in different mode with parameter variation, an equivalent system is introduced. The adaptive observer is designed based on this equivalent system without any requirement on initial conditions of the observer. It is shown by Lyapunov arguments and persistent excitation analysis that …

Modifications To The Fuzzy-Artmap Algorithm For Distributed Learning In Large Data Sets, Jose R. Castro

Electronic Theses and Dissertations

The Fuzzy–ARTMAP (FAM) algorithm has been proven to be one of the premier neural network architectures for classification problems. FAM can learn on line and is usually faster than other neural network approaches. Nevertheless the learning time of FAM can slow down considerably when the size of the training set increases into the hundreds of thousands. In this dissertation we apply data partitioning and network partitioning to the FAM algorithm in a sequential and parallel setting to achieve better convergence time and to efficiently train with large databases (hundreds of thousands of patterns). We implement our parallelization on a Beowulf …

Evolving Models From Observed Human Performance, Hans Karl Gustav Fernlund

Electronic Theses and Dissertations

To create a realistic environment, many simulations require simulated agents with human behavior patterns. Manually creating such agents with realistic behavior is often a tedious and time-consuming task. This dissertation describes a new approach that automatically builds human behavior models for simulated agents by observing human performance. The research described in this dissertation synergistically combines Context-Based Reasoning, a paradigm especially developed to model tactical human performance within simulated agents, with Genetic Programming, a machine learning algorithm to construct the behavior knowledge in accordance to the paradigm. This synergistic combination of well-documented AI methodologies has resulted in a new algorithm that …

Selective Mode Excitation In Specialty Waveguides Using Micro Optical, Waleed Mohammed

Electronic Theses and Dissertations

Although optical fibers and specialty waveguides are the base of majority of today's telecom and light delivery applications, fabrication deformation, nonlinearity and attenuation limit the bandwidth of the data being transmitted or the amount of power carried by these systems. One-way to overcome these limitations without changing the fibers design or fabrication is to engineer the input light in order to excite a certain mode or a group of modes with unique optical properties. Diffractive and micro optics are highly effective for selectively coupling light to specific modes. Using micro optics, mode selective coupling can be achieved through several matching …

Analysis And Modeling Of The Eds Maglev System Based On The Halbach Permanent Magnet Array, Qinghua Han

Electronic Theses and Dissertations

Electro-dynamic suspension (EDS) Magnetic levitation (Maglev) with its advantage in maintenance, safety, efficiency, speed, and noise is regarded as a leading candidate for the next generation transportation / space launch assist system. The Halbach array due to its unique magnetic field feature has been widely used in various applications. The EDS system using Halbach arrays leads to the potential EDS system without super-conductor (SC) technology. In this thesis, the Halbach array magnetic field and the dynamics of a novel Halbach array EDS Maglev system were considered. The practical Halbach array magnetic field was analyzed using both a Fourier series approach …

Monolithic Integration Of Dual Optical Elements On High Power Semicond, Laurent Vaissie

Electronic Theses and Dissertations

This dissertation investigates the monolithic integration of dual optical elements on high power semiconductor lasers for emission around 980nm wavelength. In the proposed configuration, light is coupled out of the AlGaAs/GaAs waveguide by a low reflectivity grating coupler towards the substrate where a second monolithic optical element is integrated to improve the device performance or functionality. A fabrication process based on electron beam lithography and plasma etching was developed to control the grating coupler duty cycle and shape. The near-field intensity profile outcoupled by the grating is modeled using a combination of finite-difference time domain (FDTD) analysis of the nonuniform …

Dispersion-Managed Breathing-Mode Semiconductor Mode-Locked Ring Laser, Bojan Resan

Electronic Theses and Dissertations

A novel dispersion-managed breathing-mode semiconductor mode-locked ring laser is developed. The "breathing-mode" designation derives from the fact that intracavity pulses are alternately stretched and compressed as they circulate around the ring resonator. The pulses are stretched before entering the semiconductor gain medium to minimize the detrimental strong integrating self-phase modulation and to enable efficient pulse amplification. Subsequently compressed pulses facilitate bleaching the semiconductor saturable absorber. The intracavity pulse compression ratio is higher than 50. Down chirping when compared to up chirping allows broader mode-locked spectra and shorter pulse generation owing to temporal and spectral semiconductor gain dynamics. Pulses as short …

Sub-Optimal Ultra-Wide Band Receivers, Nilesh Bhuvanendran

Electronic Theses and Dissertations

Ultra-wide Band (UWB) has sparked a lot of interest lately from the industry and academia. The growing capacity of the wireless industry is requires a new communication system that satisfies the high data rate which does not interfere with existing RF systems. UWB promises to be this new technology. UWB also promises low power, low cost and flexibility. The UWB Channel opens up a huge new wireless channel with Giga Hertz Capacities as well as the highest spatial capacities measured in bits per hertz per square meter. When properly implemented UWB channel can share spectrum with traditional radio systems without …

Ocr: A Statistical Model Of Multi-Engine Ocr Systems, Mercedes Terre Mcdonald

Electronic Theses and Dissertations

This thesis is a benchmark performed on three commercial Optical Character Recognition (OCR) engines. The purpose of this benchmark is to characterize the performance of the OCR engines with emphasis on the correlation of errors between each engine. The benchmarks are performed for the evaluation of the effect of a multi-OCR system employing a voting scheme to increase overall recognition accuracy. This is desirable since currently OCR systems are still unable to recognize characters with 100% accuracy. The existing error rates of OCR engines pose a major problem for applications where a single error can possibly effect significant outcomes, such …

Raindrop Size Distribution Retrieval And Evaluation Using An S-Band Radar Profiler, Fang Fang

Electronic Theses and Dissertations

Vertical pointing Doppler radar profilers are used to explore the vertical structure of precipitation cloud systems and to provide validation information for use in weather research. In this thesis, a theoretical radar rain-backscatter model was developed to simulate profiler Doppler spectra as a function of assumed rain parameters, of which the raindrop size distribution (DSD) is the fundamental quantity used to describe the characteristics of rain. Also, profiler observations during stratiform rain are analyzed to retrieve the corresponding rain DSD’s. In particular, a gamma distribution model is introduced, which uses Rayleigh scattering portion of the Doppler velocity spectrum to estimate …

Design And Hardware Implementation Of A Novel Scrambling Security Algorithm For Robust Wireless Local Area Networks, Mohit Jagetia

Electronic Theses and Dissertations

The IEEE802.11 standard for wireless networks includes a Wired Equivalent Privacy (WEP) protocol, which is a popular wireless secure communication stream cipher protocol approach to network security used to protect link-layer communications from eavesdropping and other attacks. It allows user to communicate with the user; sharing the public key over a network. It provides authentication and encrypted communications over unsecured channels. However, WEP protocol has an inherent security flaw. It is vulnerable to the various attacks, various experiments has proved that WEP fails to achieve its security goals. This thesis entails designing, evaluating and prototyping a wireless security infrastructure that …

Autonomous Environmental Mapping In Multi-Agent Uav Systems, Linus Jan Luotsinen

Electronic Theses and Dissertations

UAV units are by many researchers and aviation specialists considered the future and cutting edge of modern flight technology. This thesis discusses methods for efficient autonomous environmental mapping in a multi-agent domain. An algorithm that emphasizes on team work by sharing the agents local map information and exploration intentions is presented as a solution to the mapping problem. General theories on how to model and implement rational autonomous behaviour for UAV agents are presented. Three different human and tactical behaviour modeling techniques are evaluated. The author found the CxBR paradigm to be the most interesting approach. Also, in order to …

Topology And Control Investigation For Low-Voltage High-Current Isolated Dc-Dc Converters, Hong Mao

Retrospective Theses and Dissertations

High conversion efficiency and fast transient response at high switching frequency are the two main challenges for low-voltage high-current DC-DC converters, which are the motivations of the dissertation work.

To reduce the switching power loss, soft switching is a desirable technique to keep power loss under control at high switching frequencies. A Duty-Cycle-Shift (DCS) concept is proposed for half-bridge DC-DC converters to reduce switching loss. The concept of this new control scheme is shifting one of the two symmetric PWM driving signals close to the other, such that ZVS can be achieved for the lagging switch due to the shortened …

Cryptarray A Scalable And Reconfigurable Architecture For Cryptographic Applications, Michael John Lomonaco

Electronic Theses and Dissertations

Cryptography is increasingly viewed as a critical technology to fulfill the requirements of security and authentication for information exchange between Internet applications. However, software implementations of cryptographic applications are unable to support the quality of service from a bandwidth perspective required by most Internet applications. As a result, various hardware implementations, from Application-Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), to programmable processors, were proposed to improve this inadequate quality of service. Although these implementations provide performances that are considered better than those produced by software implementations, they still fall short of addressing the bandwidth requirements of most cryptographic applications …

Basic Study Of Micromachined Dep (Dielectrophoretic) Manipulator, Vivek Sundaram

Electronic Theses and Dissertations

The capability of manipulating microparticle in small volumes is fundamental to many biological and medical applications, including separation and detection of cells. The development of microtools for effective sample handling and separation in such volumes is still a challenge. DEP (dielectrophoresis) is one of the most widely used methods in handling the microparticles. In this thesis we show that forces generated by nonuniform electric field (DEP) can be used for trapping and separating the microparticles (latex beads). This work further explores the DEP force based on different electrode geometries and medium conductivity. A micromanipulator for latex bead separation was designed, …

Minimization Of Power Dissipation In Digital Circuits Using Pipelining And A Study Of Clock Gating Technique, Ranganath Panchangam

Electronic Theses and Dissertations

Power dissipation is one of the major design issues of digital circuits. The power dissipated by a circuit affects its speed and performance. Multiplier is one of the most commonly used circuits in the digital devices. There are various types of multipliers available depending upon the application in which they are used. In the present thesis report, the importance of power dissipation in today's digital technology is discussed and the various types and sources of power dissipation have been elaborated. Different types of multipliers have been designed which vary in their structure and amount of power dissipation. The concept of …

Fpga-Based Design Of A Maximum-Power-Point Tracking System For Space A, Todd Persen

Electronic Theses and Dissertations

Satellites need a source of power throughout their missions to help them remain operational for several years. The power supplies of these satellites, provided primarily by solar arrays, must have high efficiencies and low weights in order to meet stringent design constraints. Power conversion from these arrays is required to provide robust and reliable conversion which performs optimally in varying conditions of peak power, solar flux, and occlusion conditions. Since the role of these arrays is to deliver power, one of the principle factors in achieving maximum power output from an array is tracking and holding its maximum-power point. This …

Autonomous Robotic Automation Systemwith Vision Feedback, Jeffery Rosino

Electronic Theses and Dissertations

In this thesis, a full design, development and application of an autonomous robotic automation system using vision feedback is performed. To realize this system, a cylindrical manipulator configuration is implemented, using a personal computer (PC) based PID controller from National Instruments. Full autonomous control will be achieved via a programmable human machine interface (HMI) developed on a PC using Borland C++ Builder. The vision feedback position control is accomplished using an ordinary "off-the-shelf" web camera. The manuscript is organized as follows; After Chapter 1, an introduction to automation history and its role in the manufacturing industry, Chapter 2 discusses and …

The Removal Of Motion Artifacts From Non-Invasive Blood Pressure Measurements, Paresh Thakkar

Electronic Theses and Dissertations

Modern Automatic Blood Pressure Measurement Techniques are based on measuring the cuff pressure and on sensing the pulsatile amplitude variations. These measurements are very sensitive to motion of the patient or the surroundings where the patient is. The slightest unexpected movements could offset the readings of the automatic Blood Pressure meter by a large amount or render the readings totally meaningless. Every effort must be taken to avoid subjecting the body of the patient or the patient's surroundings to motion for obtaining a reliable reading. But there are situations in which we need Blood Pressure Measurements with the patient or …

Effects Of Deposition Temperature And Post Deposition Annealing On The Electrical Properties Of Barium Strontium Titanate Thin Film For Embedded Capacitor Applications, Ranganathan, Ravip Peelamedu

Electronic Theses and Dissertations

A higher degree of system level integration can be achieved by integrating the passive components into semiconductor devices, which seem to be an enabling technology for portable communication and modern electronic devices. Greater functionality, higher performance and increase in reliability can be achieved by miniaturizing and reducing the number of components in integrated circuits. The functional potential of small electronic devices can be enormously increased by implementing the embedded capacitors, resistors and inductors. This would free up surface real estate allowing either a smaller footprint or more silicon devices to be placed on the same sized substrate. This thesis focuses …

Design And Implementation Of A Digital Controller With Dsp For Half-Br, Yangyang Wen

Electronic Theses and Dissertations

DC-DC power converters play an important role in powering telecom and computing systems. With the speed improvement and cost reduction of digital control, digital controller is becoming a trend for DC-DC converters in addition to existed digital monitoring and management technology. In this thesis, digital control is investigated for DC-DC converters applications. To deeply understand the whole control systems, DC-DC converter models are investigated based on averaged state-space modeling. Considering half-bridge isolated DC-DC converter with a current doublers rectifier has advantages over other topologies especially in the application of low-voltage and high-current DC-DC converters, the thesis take it as an …