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Articles 2371 - 2400 of 3180

Full-Text Articles in Engineering

The Pmu-Based Parameter Identification For Synchronous Generator Dynamic Model, Chin-Chu Tsai Jan 2011

The Pmu-Based Parameter Identification For Synchronous Generator Dynamic Model, Chin-Chu Tsai

Electrical Engineering Dissertations - Archive

Power systems have become more complex and are found to be consistently operating closer to their stability limits under the deregulated environment. Power system dynamic simulation, which provides significant insight into the dynamic characteristics of system, is one of the most important tools for both planning and operation engineers. Since it heavily relies on the simulation result to make decisions related to operation strategies, grid expansion plain, facility maintenances schedules, an accurate simulation result can avoid unnecessary facility investment and improve the security of the system operation. However, the simulation result is affected by the model and parameters of the …

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Intelligent Control And Cooperation For Mobile Robots, Petru Emanuel Stingu Jan 2011

Intelligent Control And Cooperation For Mobile Robots, Petru Emanuel Stingu

Electrical Engineering Dissertations - Archive

The topic discussed in this work addresses the current research being conducted at the Automation & Robotics Research Institute in the areas of UAV quadrotor control and heterogenous multi-vehicle cooperation. Autonomy can be successfully achieved by a robot under the following conditions: the robot has to be able to acquire knowledge about the environment and itself, and it also has to be able to reason under uncertainty. The control system must react quickly to immediate challenges, but also has to slowly adapt and improve based on accumulated knowledge. The major contribution of this work is the transfer of the ADP …

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Mode Structure Of A Noiseless Phase-Sensitive Image Amplifier, Muthiah Annamalai Jan 2011

Mode Structure Of A Noiseless Phase-Sensitive Image Amplifier, Muthiah Annamalai

Electrical Engineering Dissertations - Archive

Optical parametric amplifiers (OPAs) configured as phase-sensitive amplifiers (PSAs) can be used for noiseless optical image amplification, generation of non-classical states of light, and, in particular, for multimode squeezed light generation. For all these applications and for effective use of the quantum properties of the multimode PSA, we need to know its independently squeezed (or amplified) eigenmodes. First we present the quantum theory of a spatially multimode traveling-wave PSA pumped by a high-power pump beam with arbitrary spatial profile. To quantitatively identify the Green's function of the PSA, we have developed a semi-analytical coupled-mode-theory of the PSA using 2D Hermite-Gaussian …

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The Design Of Cmos Impulse Generators For Ultra-Wideband Communication And Radar Systems, Ju-Ching Li Jan 2011

The Design Of Cmos Impulse Generators For Ultra-Wideband Communication And Radar Systems, Ju-Ching Li

Electrical Engineering Dissertations - Archive

Impulse generators play an important role in the ultra-wideband (UWB) systems. Particularly in the transmitter, impulse generator performs an interface between input data and the antenna determining the overall performance of the transmitter. After the federal communication commission (FCC) revised the rules for UWB systems usages, the design of impulse generators has been pursued and yet challenging especially using CMOS technology. In this dissertation, three impulse generators are presented with analytical explanations, simulations, and measurements. First, the design and simulation of an impulse generator using TSMC 0.18 ìm CMOS technology is presented. The operating frequency band of the impulse generator …

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Radar Sensor Networks: Waveform Design, Mimo And Compressive Sensing, Lei Xu Jan 2011

Radar Sensor Networks: Waveform Design, Mimo And Compressive Sensing, Lei Xu

Electrical Engineering Dissertations - Archive

In this dissertation, we have studied totally eight topics which are focused on but not limited to radar sensor networks (RSN) from a signal processing perspective. We propose the definitions of ZCZ/LCZ (Zero Correlation Zone/Low Correlation Zone) sequence-pair sets, provided three methods to construct optimized optimized punctured LCZ/ZCZ sequence-pair sets and study their properties in chapter 2 and 3. We further investigate the waveform design problem for radar system, radar sensor network, sonar sensor network and MIMO radar system from chapter 4 to chapter 7. In addition, we study radar sensor network from the view of information theory in chapter …

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Numerical Modeling Of Microwave Emission From Irregular Layer, Luis Manuel Camacho-Velazquez Jan 2011

Numerical Modeling Of Microwave Emission From Irregular Layer, Luis Manuel Camacho-Velazquez

Electrical Engineering Dissertations - Archive

A numerical approach to model the microwave emission from an irregular layer is developed. The phase matrix of the layer components as well as the emission characteristics are estimated using a numerical approach, namely the Finite-Difference Time-Domain (FDTD) method. The phase matrix is then integrated into a layer model that accounts for the scattering between the layer and ground, using the radiative transfer theory. The effects of interface roughness on emission are incorporated into the model through the surface phase matrices, which are computed using the Integral Equation Model (IEM).The validity of the phase matrices computation is tested against theoretical …

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The Complex Gaussian Scale Mixtures Of Complex Wavelet Coefficients And Applications, Yothin Rakvongthai Jan 2011

The Complex Gaussian Scale Mixtures Of Complex Wavelet Coefficients And Applications, Yothin Rakvongthai

Electrical Engineering Dissertations - Archive

In this thesis, the complex Gaussian scale mixture (CGSM), which is an extension of the Gaussian scale mixture (GSM) for real-valued random variables to the complex case, is presented to model the complex wavelet coefficients. Along with some related propositions and miscellaneous results, the probability density functions (pdf) of the magnitude and phase of the complex random variable are presented. Specifically, the closed forms of the magnitude pdf for the case of complex generalized Gaussian distribution (CGGD) and the phase pdf for the general case are presented. Subsequently, the pdf of the relative phase is derived.Moreover, parameter estimation methods in …

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Miniature Wireless Gastrostimulator, Sanchali Deb Jan 2011

Miniature Wireless Gastrostimulator, Sanchali Deb

Electrical Engineering Dissertations - Archive

Gastroparesis is a common disorder caused to patients suffering from diabetes, cancer and Parkinson's disease. Gastric electrical stimulation (GES) has attracted significant attention in the treatment for Gastroparesis. GES inflicts electrical pulses to the stomach tissues to help regain normal motility and hence reduces Gastroparesis symptoms like vomiting, nausea, abdominal bloating etc. Conventional gastric stimulator needs a long surgery to be implanted and it is a big pacemaker like device that runs by a non-rechargeable battery. It has to be replaced once the battery gets exhausted. Hence another round of surgery is done when these devices are needed to be …

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Localization Of Short Circuit Faults In The Power Distribution Networks, Omkar Deepak Limaye Jan 2011

Localization Of Short Circuit Faults In The Power Distribution Networks, Omkar Deepak Limaye

Electrical Engineering Theses - Archive

This thesis summarizes the research efforts on localizing short-circuit faults in power distribution networks. Specifically, an experimental testbed is constructed to emulate realistic power distribution networks; various short-circuit faults are artificially created in the testbed; voltages/currents are measured over the testbed; and finally, fault localization is achieved by analyzing the measurement data.Two types of power distribution networks are analyzed: serial/radial and grid/mesh networks. In the serial network, a scheme based on terminal voltage and current measurements is developed. Two voltage profiles, namely "forward voltage profile" and "backward voltage profile," are plotted and their intersection is estimated as the fault location. …

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Bridge Monitoring System Using Embedded Computer Vision, Kenan Modi Jan 2011

Bridge Monitoring System Using Embedded Computer Vision, Kenan Modi

Electrical Engineering Theses - Archive

The bridges and overpass are integral part of road network. These structures deteriorate the moment the construction is over. The factors of deterioration are impact loads of vehicles, natural factors such as wind, rain, earthquake, floods, etc. These deterioration leads to structural failures. In order to prevent failures these structure should be periodically monitored and maintained. In this research project a novel method for early detection of bridge failure using computer vision application and 3D road profiling system is proposed. The objective of this research work to check the feasibility of this bridge monitoring system for any structural movement detection. …

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Development Of Prosthetic Skin, Rohit Kilaru Jan 2011

Development Of Prosthetic Skin, Rohit Kilaru

Electrical Engineering Theses - Archive

The objective of this research was to embed tactile sensors in polyimides. This novel method could be utilized to realize prosthetic skin for sensing different kinds of mechanical stimuli. Tactile sensors have an increasing demand in medical sectors: upper and lower-limb prosthetics and in the industrial sectors: robot end-effectors, grippers and manipulators. The sensors developed are targeted for prosthetic arm tactile sensing applications. Current work presents piezoresistive differential pressure sensors fabricated on flexible polyimide film or substrate.A unique technique to bond a flexible superstrate polyimide layer to a MEMS tactile sensor array is presented in this thesis. The sensor is …

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Investigating The Implementation Of Usaf Damage Tolerant Risk Analysis With A Structural Health Monitoring System, Jeffrey Scott Tippey Jan 2011

Investigating The Implementation Of Usaf Damage Tolerant Risk Analysis With A Structural Health Monitoring System, Jeffrey Scott Tippey

Electrical Engineering Theses - Archive

The recent improvements in micro fabrication, power management, and distributed sensor networks have made Structural Health Monitoring (SHM) an appealing solution for decreasing costs, decreasing risk of catastrophic failure, and improving overall aircraft health and maintenance (Mukkamala, 2000). A SHM system uses non-destructive inspection (NDI) to provide on-demand updates on the health of a structure, such that the integrity of the structure can be quantified and accounted for (Achenback, 2009). In order to provide an accurate representation of a structure's health, a distributed network of sensors must work in unison to detect a distribution of cracks and damage present on …

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Temperature And Frequency Dependence Of Thermal Impedance In Dielectrically Isolated Sige Hbts, Valay Dineshbhai Shah Jan 2011

Temperature And Frequency Dependence Of Thermal Impedance In Dielectrically Isolated Sige Hbts, Valay Dineshbhai Shah

Electrical Engineering Theses - Archive

Silicon Germanium (SiGe) heterojunction bipolar transistors (HBTs) have been designed to cater the demand of high speed circuits having applications in wireless and optical communication. Due to higher cut-off frequencies and high speed applications, self heating plays a significant role in the performance of SiGe HBTs. This thesis paper does an extensive analysis on the effect of self heating and used different DC, time domain and frequency domain methods to extract the self heating parameters thermal resistance (Rth) and thermal capacitance (Cth). The VBIC (Vertical Bipolar Inter Company) model is used for all the simulations. Simulations are performed using ICCAP …

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Comparison Of Brain Activity In The Prefrontal Cortex During Digit Span Task Between Student Veterans With Post Traumatic Stress Disorder And Controls Using Functional Near Infrared Spectroscopy, Bejoy Mathai Jan 2011

Comparison Of Brain Activity In The Prefrontal Cortex During Digit Span Task Between Student Veterans With Post Traumatic Stress Disorder And Controls Using Functional Near Infrared Spectroscopy, Bejoy Mathai

Bioengineering Theses - Archive

Near Infrared Spectroscopy (NIRS) is an optical non-invasive imaging technique which makes use of infrared light at particular wavelengths to measure the changes in concentrations of oxygenated blood haemoglobin (HbO) as well as the deoxygenated blood haemoglobin (HbR). Making use of this technique to acquire measurements during different functional activities subcategorises it into the novel and fast developing field of Functional Near Infrared Spectroscopy (fNIRS). In my study I have made use of this novel imaging technique to study the pre-frontal cortex while the subject performs the functional task of digit span task consisting of the forward digit span and …

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Flexural Behavior Of Steel Fiber Reinforced Prestressed Concrete Beams And Double Punch Test For Fiber Reinforced Concrete, Netra Bahadur Karki Jan 2011

Flexural Behavior Of Steel Fiber Reinforced Prestressed Concrete Beams And Double Punch Test For Fiber Reinforced Concrete, Netra Bahadur Karki

Civil Engineering Dissertations - Archive

Steel fibers have widely been used in the past to reinforce brittle materials in many nonstructural applications such as pavement, tunneling lining, etc. On the basis of numerous previous studies, ACI 318-11 [2011] has recently accepted steel fiber as a minimum shear reinforcement replacement with minimum 0.75% volume fraction for both reinforced concrete and prestressed concrete members. However, not much previous research has talked about the flexural behavior of fiber reinforced concrete (FRC). As per ACI 318-11 for tension-controlled sections, the net tensile strains in the outermost layer of steel, εt, should be greater than or equal to 0.005 and …

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Evaluation Of Training Needs For Building Information Modeling (Bim), German Pena Jan 2011

Evaluation Of Training Needs For Building Information Modeling (Bim), German Pena

Civil Engineering Theses - Archive

The basic premise of Building Information Modeling (BIM) is to use and share the digital model of a project as a source of information for all participants, in order to simulate and analyze potential problems during the project's life-cycle, from conception to operation. BIM is a relatively new technology praised by all participants in the Architecture-Engineering-Construction (AEC) industry for its innovative tools, and the promise of a high return of investment and productivity increase. The construction industry experimented little growth in productivity in the last decades, and is heavily relying on technology rather than intense labor in order to boost …

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Effect Of Pavement Type On Fuel Consumption In City Driving, Palinee Sumitsawan Jan 2011

Effect Of Pavement Type On Fuel Consumption In City Driving, Palinee Sumitsawan

Civil Engineering Dissertations - Archive

Vehicular fuel consumption and emissions are two increasingly important measures of effectiveness of sustainable transportation systems, particularly considering that mobile sources in the U.S. account for the largest consumption of energy and generation of air pollution. Improving the energy efficiency of the transportation sector including improving vehicle shape, weight, engine size, and tire quality could play a vital role in reducing fuel consumption and exhaust gas emissions. Pavement surface type and other surface characteristics such as skid resistance and roughness affect vehicular fuel consumption. The main objective of this study has been to investigate any differences that might exist in …

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Development Of A Model Of Productivity For Horizontal Directional Drilling (Hdd), Mohmd Sarireh Jan 2011

Development Of A Model Of Productivity For Horizontal Directional Drilling (Hdd), Mohmd Sarireh

Civil Engineering Dissertations - Archive

Horizontal Directional Drilling (HDD) is a growing method for installation of pipes in urban areas and where ever trenching is impossible or undesirable; such as in crossing rivers, lakes, and railways, and special areas such as airports. This technique utilizes downhole cutting heads to create a pilot borehole before it is enlarged with back reamers to allow pulling back of a product pipe. The utilization of HDD for the installation of underground infrastructure (i.e., water, oil and gas pipes, telecommunication, power conduits, in some cases gravity pipes, and so on), has shown a rapid growth compared to other trenchless technologies. …

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Impact Of Transit-Oriented Infrastructure Investments On Property Valuations, Francis Amodu Smith Jan 2011

Impact Of Transit-Oriented Infrastructure Investments On Property Valuations, Francis Amodu Smith

Civil Engineering Dissertations - Archive

The population explosion of the second half of the last century brought about increased human activity. Much of the attendant increased access to activities has been facilitated by the incredible technological advances in the automobile, which depends almost entirely on fossil fuels. Supplies of fossil fuel are limited and the automobile has led to urban sprawl, traffic congestion, and reduced quality to life in cities (1). This type of development is unsustainable. Transit-oriented development (TOD) is one of the neo-urbanism response instruments. The question is: "How well do these urban forms perform in North-Central Texas? In response, this study has …

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Nano-Modified Cement Composites And Its Applicability As Concrete Repair Material, Tanvir Manzur Jan 2011

Nano-Modified Cement Composites And Its Applicability As Concrete Repair Material, Tanvir Manzur

Civil Engineering Dissertations - Archive

Nanotechnology or Nano-science, considered the forth industrial revolution, has received considerable attention in the past decade. The physical properties of a nano-scaled material are entirely different than that of bulk materials. With the emerging nanotechnology, one can build material block atom by atom. Therefore, through nanotechnology it is possible to enhance and control the physical properties of materials to a great extent. Composites such as concrete materials have very high strength and Young's modulus but relatively low toughness and ductility due to their covalent bonding between atoms and lacking of slip systems in the crystal structures. However, the strength and …

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Multivariate Adaptive Regression Spline Based Framework For Statistically Parsimonious Adaptive Dynamic Programming, Subrat Sahu Jan 2011

Multivariate Adaptive Regression Spline Based Framework For Statistically Parsimonious Adaptive Dynamic Programming, Subrat Sahu

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

Central to Dynamic Programming (DP) is the `cost-to-go' or `future value' function, which is obtained via actually solving the Bellman's equation and central to Approximate Dynamic Programming (ADP) is the use of an approximation of the future value function. The exact DP algorithm seeks to compute and store a table consisting of one cost-to-go value for each point in the state space and its usefulness is limited by the curse of dimensionality, which renders the methodology computationally intractable in the face of real life problems with high dimensional state space and in the face of continuous state variables. ADP methodology …

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Parametric Analysis Of A Detonation-Type Turbofan, Yashwanth M. Swamy Jan 2011

Parametric Analysis Of A Detonation-Type Turbofan, Yashwanth M. Swamy

Mechanical and Aerospace Engineering Theses - Archive

A new type of turbofan which detonates a fuel-air mixture was theoretically found to perform better than a conventional turbofan. A continuous detonation process is described and considered inside the core of the turbofan. The detonation-type turbofan needs certain modifications to detonate the fuel-air mixture at the core of the turbofan, namely, an annular detonation chamber to achieve continuous detonation. A parametric analysis of the new detonation-type turbofan was developed and used to calculate the performance parameters.

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Numerical Study Of Drop Formation From Dripping To Jetting, Allouah Kadjo Jan 2011

Numerical Study Of Drop Formation From Dripping To Jetting, Allouah Kadjo

Mechanical and Aerospace Engineering Theses - Archive

The formation of liquid droplet from a capillary tube has been examined using numerical simulations. The dimensions of the capillary tube and the flow velocity have been varied to observe the regimes of drop formation. There are three main regimes of drop formation, which are the periodic dripping, the dripping faucet and the jetting regimes. The mechanism of drop formation changes from one regime to another and involves different parameters. A particular emphasis has been placed on the velocity limits between the different regimes and the critical role played by instabilities in the generation of satellite drops. The algorithm used …

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Numerical Modeling Of A Parallel Plate Electrowetting-On-Dielectric (Ewod) Device, Kevin Tully Jan 2011

Numerical Modeling Of A Parallel Plate Electrowetting-On-Dielectric (Ewod) Device, Kevin Tully

Mechanical and Aerospace Engineering Theses - Archive

Numerical modeling and simulations have been performed in this study that focuses on modeling the fluid dynamics of an Electrowetting-on-Dielectric (EWOD) device. The case to be modeled in the present study is a droplet cutting problem where a droplet is sandwiched between two plates of Teflon and an electrical actuation will cause the droplet to cut or split into two smaller droplets. A finite difference method has been used to solve the Navier-Stokes equations, along with the continuity equation. An algorithm used for tracking the free surface is the Volume of Fluid (VOF) method. Along with using the VOF method …

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A Highly Linear Voltage Controlled Oscillator With Low Power Dissipation, Sourabh Sharma Jan 2011

A Highly Linear Voltage Controlled Oscillator With Low Power Dissipation, Sourabh Sharma

Electrical Engineering Theses - Archive

A voltage controlled oscillator using 90 nm CMOS technology has been presented with the extremely low power dissipation of 1.35 mW and provides 1.45 mW (with use of buffers) output AC power. It has highly linear voltage to frequency transformation, with only 4.85% of maximum error this VCO Works in the long range from 5.1 to 9.099 GHz while the controlling voltage varies from 0 to .5 volts, The oscillator is powered by a 1 volt power supply.

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Improvement In The Performance Of 3g Wireless Communications Systems Using An Ica Based Signal Processing Block, Winston Dsouza Jan 2011

Improvement In The Performance Of 3g Wireless Communications Systems Using An Ica Based Signal Processing Block, Winston Dsouza

Electrical Engineering Theses - Archive

In this thesis, we have implemented a signal processing block in the receiver of a third generation (3G) cellular system to provide improvement in the quality of service. Each block of the cellular system, including the complete transmitter, channel and the receiver is implemented in Matlab. The multiplexing scheme is implemented using wideband code division multiple access (WCDMA). The signal processing block is based on the concept of independent component analysis (ICA), and a rake receiver is used at the receiver to mitigate inter symbol interference due to the multi-paths. The signal processing block (SPB) is further extended to a …

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Microarray Image Denoising Using Complex Gaussian Scale Mixtures Of Complex Wavelets, Lakshmi Srinivasan Jan 2011

Microarray Image Denoising Using Complex Gaussian Scale Mixtures Of Complex Wavelets, Lakshmi Srinivasan

Electrical Engineering Theses - Archive

The scientific world has witnessed an explosion in the development of comprehensive and high-throughput methods for molecular biology experimentation. High density DNA microarray technology, allows researchers to monitor the expression levels of thousands of genes in an organism simultaneously, to characterize geneticdiseases at the molecular level and to direct new treatment for specific cellular aberrations. The microarray analysis is rapidly becoming a standard research tool. But, the images produced by microarray experiments, are not perfect and includes noisysources, that contaminate them during the various stages of its formation. These microarray images need to be denoised to ensure reliable and accurate …

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Online Learning Algorithms For Differential Dynamic Games And Optimal Control, Kyriakos G. Vamvoudakis Jan 2011

Online Learning Algorithms For Differential Dynamic Games And Optimal Control, Kyriakos G. Vamvoudakis

Electrical Engineering Dissertations - Archive

Optimal control deals with the problem of finding a control law for a given system that a certain optimality criterion is achieved. It can be derived using Pontryagin's maximum principle (a necessary condition), or by solving the Hamilton-Jacobi-Bellman equation (a sufficient condition). Major drawback of optimal control is that it is offline. Adaptive control involves modifying the control law used by a controller to cope with the facts that the system is unknown or uncertain. Adaptive controllers are not optimal. Adaptive optimal controllers have been proposed by adding optimality criteria to an adaptive controller, or adding adaptive characteristics to an …

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Compressive Sensing And Wireless Network Capacity With Performance Analysis, Davis Kirachaiwanich Jan 2011

Compressive Sensing And Wireless Network Capacity With Performance Analysis, Davis Kirachaiwanich

Electrical Engineering Dissertations - Archive

This dissertation contains five reseach topics. In chapter 1, the performances of a noncoherent slow frequency-hopping system with M-ary frequency-shift-keyed modulation (NC-FH/MFSK) under various hostile jamming strategies are studied. Then, the knowledge obtained is used in developping a new "combined-jamming" interference model. The model can be used in analyzing the performance of NC- FH/MFSK networks, where transmissions from each network node can interfere with one another. An example application of the proposed model is the channel assignment in a multiradio FH/MFSK wireless mesh network (MR-FH/MFSK WMN). In chapter 2, the multiradio frequency-hopping wireless mesh networks (MR- WMN) is still being …

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Guided-Mode Resonance Devices: Omnidirectional Reflectors, Wideband Absorbers, Sensors And Narrowband Filters, Wenhua Wu Jan 2011

Guided-Mode Resonance Devices: Omnidirectional Reflectors, Wideband Absorbers, Sensors And Narrowband Filters, Wenhua Wu

Electrical Engineering Theses - Archive

In this thesis, a series of guided-mode resonance (GMR) devices are developed and optimized in the optical spectral region. Some of these devices are designed by inverse algorithms such as genetic algorithm and particle swarm optimization. One-dimensional subwavelength silicon and germanium gratings providing high omnidirectional reflectivity within specific band are designed respectively for TE and TM polarization. A simple amorphous silicon waveguide grating is proposed to enhance the absorbance for solar cells by 60% comparing with unpatterned structure. Another presented grating absorbs light nearly totally in the ~ 0.3-0.6 ìm wavelength band for all incidence angles independent of polarization, namely …

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