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Articles 601 - 630 of 656

Full-Text Articles in Electrical and Computer Engineering

Electromagnetic Wave Scattering From Vegetation, Xiaoyan Huang Aug 2006

Electromagnetic Wave Scattering From Vegetation, Xiaoyan Huang

Electrical Engineering Dissertations - Archive

This dissertation contains the theoretical study of microwave scattering from vegetated media and the development of microwave scattering models with applications to these media. A vegetation canopy may consist of deciduous or coniferous leaves, branches, and trunks with certain size and orientation distributions. The formulation of the scattering model for each element of the canopy is carried out and its scatter patterns versus its size and orientation for like and cross polarizations are computed and presented. In particular, an extension is made where vegetation with a compound-leaf pattern is considered. For this type of vegetation, several leaves that form a …

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Device Level Vacuum Packaged Microbolometers On Flexible Substrates, Aamer Mahmood Aug 2006

Device Level Vacuum Packaged Microbolometers On Flexible Substrates, Aamer Mahmood

Electrical Engineering Dissertations - Archive

Micromachined microbolometers on flexible substrate have been fabricated and characterized. Liquid polyimide PI5878G made by HD Microsystems has been used to form the flexible substrate. Semiconducting Yttrium-Barium-Copper-Oxide (commonly referred to as YBCO) is the temperature sensitive material. These detectors are supported by thin micromachined layers of silicon nitride on flexible polyimide PI5878G. The devices were characterized for temperature dependent resistance (R(T)), the temperature coefficient of resistance (TCR, ), responsivity , detectivity (D*) and thermal conductance (Gth). A typical device had a resistance of 3.76 MI and a TCR of -2.63 %/K at 301 K. The measured thermal conductance was W/K. …

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Nonlinear Control Of Microelectromechanical Systems (Mems) Devices, Kwadwo Osei Owusu Aug 2006

Nonlinear Control Of Microelectromechanical Systems (Mems) Devices, Kwadwo Osei Owusu

Electrical Engineering Theses - Archive

Different actuation principles have been developed for MEMS but electrostatic actuators are the most common. A significant drawback in the use of electrostatic actuators for some applications is their nonlinear voltage to position characteristics. Analog operation of these devices requires the use of feedback to stabilize and linearize them. Controlling and optimizing the operation of electrostatic controllers using feedback requires the establishment of the complete and accurate dynamical model of the device. In this thesis, we show how an optical switch driven by a MEMS electrostatic comb drive is controlled to guarantee its performance, stability and reliability for use in …

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3d Interconnects For Die And Wafer Stacks, Rachita Dewan Aug 2006

3d Interconnects For Die And Wafer Stacks, Rachita Dewan

Electrical Engineering Theses - Archive

3D integration results from the ever demanding trend towards smaller and lower-profile, lighter and lower cost packaged devices requires further package miniaturization. With the present System-on-chip (SOC) technology reaching its limitation in terms of functionality and cost, effort are being concentrated on exploring the third dimension, i.e. 3D integration. It provides a volumetric packaging solution for higher integration and performance and results in size and weight reduction. Approaches to achieve 3D integration are die and wafer stacking. A key technology to realize the potential of stacking is implementation of vertical electrical interconnects between die and wafer stacks. This thesis discusses …

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The Design And Analysis Of Optical Scanners For Optical Coherence Tomography, Naresh Dhaubanjar Aug 2006

The Design And Analysis Of Optical Scanners For Optical Coherence Tomography, Naresh Dhaubanjar

Electrical Engineering Theses - Archive

A miniature fiber optic scanner capable of two-dimensional scanning for medical imaging is designed and developed. The scanner is actuated externally using an electromagnet. Nickel gel, a soft ferromagnetic material, is coated on the optical fiber. The performance of the scanner is characterized. Finite element analysis is performed to validate the theoretical and experimental results. A design and analysis of a cantilever type electrostatic zipping actuator and a bidirectional vertical thermal actuator are presented. The actuation principle, lumped modeling analysis, experimental results, and finite element analysis of both actuators are presented. The actuators are characterized statically and dynamically using the …

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Modeling And Performance Evaluation Of A Power Electronic-Based Controlled Fuel Cell System, Yashar Ehsan Kenarangui Aug 2006

Modeling And Performance Evaluation Of A Power Electronic-Based Controlled Fuel Cell System, Yashar Ehsan Kenarangui

Electrical Engineering Theses - Archive

In fuel cell applications, design of an appropriate controller and selection of an Ultra-Capacitor require a suitable model of fuel-cell-systems that can adequately represent the significant characteristics of the system. Such a model, using lumped circuit elements, was developed in this thesis via a simple method without requiring fuel cell design parameters. To validate the model, simulation results from the model were compared against the results from experimental setups and satisfactory results were obtained. Later, this model was used in order to design a controller that meets the control objectives, namely, regulation of output voltage and attenuation of load current …

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Analysis Of Electromagnetic Field In A Switched Reluctance Machine From An Energy Conversion Perspective, Wei Jiang Jul 2006

Analysis Of Electromagnetic Field In A Switched Reluctance Machine From An Energy Conversion Perspective, Wei Jiang

Electrical Engineering Theses - Archive

With the recent advancement in power electronics and digital signal processors, switched reluctance machine (SRM) attracts more attention in high speed and harsh environment applications due to its rugged and robust structure. Despite considerable progress in the development of power electronics based control of the SRM, relatively small changes in the magnetic design has been observed. A physically insightful analysis of the electromechanical energy conversion process, origins and spatial distribution of electromagnetic field quantities at a microscopic level can shed light on the process of SRM design, which in turn could create new opportunities for substantial improvement of SRM performance …

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Web-Based Real-Time Monitoring System To Enhance The Participation Of An Industrial Power System In A Restructured Utility Industry, Shun-Hsien Huang Jul 2006

Web-Based Real-Time Monitoring System To Enhance The Participation Of An Industrial Power System In A Restructured Utility Industry, Shun-Hsien Huang

Electrical Engineering Dissertations - Archive

The opening of the Electric Reliability Council of Texas (ERCOT) grid to wholesale competition began in 1996 that initiated the first stage of deregulation in Texas. In order to relieve generation and transmission constraints, load reduction is considered as a form of available energy and spinning reserve. Afterward, power system becomes more dynamic and creates more opportunities for both electricity suppliers and consumers. Currently, both power supplier and demand consumer can participate in the energy and ancillary services (AS) markets to bid/offer for their energy, capacity, and demand in the ERCOT markets. In order to act as an effective market …

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An Emission Model For Lunar Regolith Surfaces Based On Matrix Doubling Method, Darshan Shrestha Jul 2006

An Emission Model For Lunar Regolith Surfaces Based On Matrix Doubling Method, Darshan Shrestha

Electrical Engineering Theses - Archive

An emission model based on Matrix Doubling Method is implemented for the calculation of emission signatures from the lunar regolith surfaces. The matrix doubling method is used to solve the radiative transfer equations which encompass the volume and surface scattering properties of the medium. The layer and surface are characterized by their corresponding phase matrices which contain adequate information on how the amplitude, phase and polarization of the incident Stokes vector change on being incident in that medium. Emissivity signatures are calculated by solving the transfer equations using matrix doubling method and taking these phase matrices as "boundary conditions". The …

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Fpga Prototyping For Fast And Efficient Verification Of Asic H.264 Decoder, Basavaraj Mudigoudar May 2006

Fpga Prototyping For Fast And Efficient Verification Of Asic H.264 Decoder, Basavaraj Mudigoudar

Electrical Engineering Theses - Archive

To improve compression efficiency, recent video compression standards such as H.264 use complex algorithms and various modes that demand more computational power. Consumer electronics industry requires a low power, compact and cost-effective implementation of video codec for most of the products. ASIC implementation of these video codecs is a logical choice to meet these requirements. Functional verification of an ASIC implementation consumes a major part of design cycle time and lot of resources. Because of large design, various modes and options, functional verification of an ASIC H.264 video codec is a challenging, resource intensive and time consuming process. In this …

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Simulation And Characterization Of Znse/Bete Resonant Tunneling Diode On Silicon, Moshe Davis May 2006

Simulation And Characterization Of Znse/Bete Resonant Tunneling Diode On Silicon, Moshe Davis

Electrical Engineering Theses - Archive

ZnSe/BeTe resonant tunneling diodes were grown on silicon with a ZnxBe1-xTe buffer layer using MBE (Molecular Beam epitaxy).These devices were processed and characterized. The devices showed multiple NDR (negative differential resistance) regions at room temperature with PVR (Peak to valley ratios) between 1.01 to 1.23. Variations to the structure were made in growth and their corresponding current-voltage characteristics were studied. The ZnSe/BeTe resonant tunneling diode showed asymmetrical current voltage characteristics for positive and negative biases. The sources of asymmetry were investigated during fabrication and with the help of simulations. The Al/ZnSe contact was confirmed to be ohmic contact when the …

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Real-Time Data Monitoring And Manipulation For Wireless Sensor Networks, Sankar Bhanu Gorthi May 2006

Real-Time Data Monitoring And Manipulation For Wireless Sensor Networks, Sankar Bhanu Gorthi

Electrical Engineering Theses - Archive

The growth of Wireless Sensor Network research has brought about the need for tools to help developers rapidly develop applications for various platforms. In the pursuit of these capabilities, this work deals with the design of a graphical approach to development of Wireless Sensor Network applications for implementation in the LabVIEW Graphical Development Environment. The work done also covers the implementation and development of the Sound and Vibration Toolkit for LabVIEW. The implementation of these tools in developing a novel test-bed at the Distributed Intelligence and Automation Laboratory at the ARRI at UT Arlington is also shown. This work is …

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Structural Similarity Based Image Quality Assessment: Pooling Strategies And Applications To Image Compression And Digit Recognition, Xinli Shang May 2006

Structural Similarity Based Image Quality Assessment: Pooling Strategies And Applications To Image Compression And Digit Recognition, Xinli Shang

Electrical Engineering Theses - Archive

This thesis studies a recently proposed perceptual image similarity measure: the structural similarity (SSIM) index. Although still in its early stage, the SSIM index has demonstrated superior performance in a large number of tests as compared to the currently most widely used image distortion/quality measures, the mean squared error (MSE) and the peak signal-to-noise-ratio (PSNR). This motivates us to further investigate the SSIM method and extend it to other image processing and pattern recognition applications. Specifically, three topics have been studied in this thesis: spatial pooling strategies for perceptual image quality assessment, structural similarity-guided perceptual image compression, and handwritten digit …

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Design And Hardware Implementation Of A Soft-Switched Converter For Fuel Cell Applications, Shiju Wang May 2006

Design And Hardware Implementation Of A Soft-Switched Converter For Fuel Cell Applications, Shiju Wang

Electrical Engineering Theses - Archive

The focus of this thesis is to design a DC-DC quasi-soft switched boost converter suitable for fuel cell applications. Study of electrical output characteristics of fuel cells was necessary for this purpose. A number of experiments were conducted to study the steady-state and transient response of fuel cell system under various load dynamics. The results of these findings were necessary for the next phase of the project which was to design a reliable and high-performance regulated DC-DC converter. The design goals were realized with a soft-switching boost converter (implementation of zero voltage switching (ZVS) and zero current switching (ZCS) schemes) …

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Design Of An Enhanced Translinear Variable Floating Resistor And Its Application In A Vga, Nithya Jagannathan May 2006

Design Of An Enhanced Translinear Variable Floating Resistor And Its Application In A Vga, Nithya Jagannathan

Electrical Engineering Theses - Archive

An improved current controlled floating resistor is designed based on translinear loops for application in a Variable Gain Amplifier (VGA). This work compares the use of two different devices and evaluates the difference based on the model parameters and circuit performance. The different architectures employed clearly demarcate the performance variations. The translinear variable resistor exhibits a dynamic range greater than 60 mV. The resistance value lies in the range of 3 K? to few Ohms. A Current Feedback Operational Amplifier (CFOA) is also designed to have an f -3dB of 250 MHz. The CFOA together with the variable resistor in …

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Generalization Of Widely Linear Filtering Concepts For Equalization And Interference Suppression In Pam/Qam Systems, Kiran Kumar Kuchi May 2006

Generalization Of Widely Linear Filtering Concepts For Equalization And Interference Suppression In Pam/Qam Systems, Kiran Kumar Kuchi

Electrical Engineering Dissertations - Archive

In PAM/QAM transmission systems, standard Minimum Mean Square Error (MMSE) linear (LE) or Decision Feedback Equalization (DFE) equalization methods are often used to suppress the detrimental effects inter-symbol and/or co-channel interference (ISI/CCI) effects of the channel. In this thesis we show the benefits of a new signal processing concept called Widely Linear (WL) filtering for equalization applications in wireless systems. In particular, we introduce generalized WL MMSE/MMSE-DFE equalization structures for both PAM systems that use real constellations and QAM (that use complex modulation alphabets) with multiple antennas and multiple co-channel interferers. In this thesis we first show that WL equalizers …

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Design And Fabrication Of Optically-Pumped Guided-Mode Resonance Surface-Emitting Lasers, Preston Phillip Young May 2006

Design And Fabrication Of Optically-Pumped Guided-Mode Resonance Surface-Emitting Lasers, Preston Phillip Young

Electrical Engineering Dissertations - Archive

This dissertation describes the design and fabrication of guided-mode resonance (GMR) structures and their applications to laser devices. These include tunable Ti:Sapphire lasers as well as semiconductor lasers with integrated light emitting layers. The resonance characteristics of GMR structures are determined by the designed and fabricated waveguide-grating parameters. The primary tool for the design and simulation analysis of GMR devices is rigorous coupled-wave analysis (RCWA). This numerical method is used to provide diffraction efficiency calculations as well as simulations of the electric fields within GMR structures. RCWA-based field analysis is used to design an optically pumped GMR surface-emitting laser (GMR-SEL) …

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Self-Organization And Resource Allocation In Wireless Sensor Networks, Liang Zhao May 2006

Self-Organization And Resource Allocation In Wireless Sensor Networks, Liang Zhao

Electrical Engineering Dissertations - Archive

In this dissertation, we utilize clustering to organize wireless sensors into an energy-efficient hierarchy. We propose a Medium-Contention Based ClusterHeadship Auction (MCCHA) scheme, through which sensors self-organize themselves into energy-efficient clusters by bidding for cluster headship. This scheme is based on a new criterion that can be used by each sensor node to make a distributed decision on whether electing to be a cluster head or a non-head member, which is a fully distributed approach. Although MCCHA uses only local information, it achieves better performance in terms of effective lifetime and Data/Energy Ratio compared with native LEACH, which relies on …

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A Physics Based Multi-Resolution Technique For Extraction Of Finite Duration Time Responses In Radar Images, Nancy Lanett May 2006

A Physics Based Multi-Resolution Technique For Extraction Of Finite Duration Time Responses In Radar Images, Nancy Lanett

Electrical Engineering Theses - Archive

This paper presents a wavelet multi-resolution technique for examination of scattering phenomena in radar images. Through multi-resolution frequency domain analysis, range gating is implemented for extraction of wave medium interaction phenomena. To analyze the data, a sliding range gate is implemented by applying a phase shift to the spectral domain far field data prior to wavelet analysis. A method for efficient removal of window effects, which occur due to the finite nature of the data, is demonstrated through reconstruction of the decomposed waveform following removal of the lowest resolution. A correlation of the physical meaning of the multi-resolution data to …

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Design Of A Cmos Vco And Frequency Divider For 5 Ghz Applications, Prithvi Shylendra May 2006

Design Of A Cmos Vco And Frequency Divider For 5 Ghz Applications, Prithvi Shylendra

Electrical Engineering Theses - Archive

This thesis presents the design of a new CMOS Voltage Controlled Oscillator and a frequency divider, both of which form important blocks in the design of a PLL synthesizer. These components are important because they operate at the highest frequencies within the PLL and also consume most of the power as compared to the other components. Both these circuits have been an active topic of research in recent years especially with the scaling of technology bringing hopes of complete system-on-chip (SOC) integration at RF frequencies. The circuits in this thesis are designed for 5 GHz applications, mainly for the IEEE …

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Design And Development Of Embedded Dsp Controllers For Power Electronic Applications, Raman Nair Harish Gopala Pillai May 2006

Design And Development Of Embedded Dsp Controllers For Power Electronic Applications, Raman Nair Harish Gopala Pillai

Electrical Engineering Theses - Archive

Power applications like motor drives, inverters have complex algorithms that can be used to improve their efficiency. More often reduced manufacturing cost takes precedence over better efficiency. DSPs with their high computational power can provide reduced cost and higher efficiency. Though the cost of a standalone DSP chip has reduced, its integration to form a complete embedded product is an area often overlooked. High frequency of operation, reduced package size, and sensitivity to component placement are some of the factors that affect the interface between input/output devices and the DSP. This thesis presents the design and development of an embedded …

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Feasibility Study Of Options For Aging Hydro-Power Generation Facility, Sandip R. Sharma Apr 2006

Feasibility Study Of Options For Aging Hydro-Power Generation Facility, Sandip R. Sharma

Electrical Engineering Theses - Archive

Most of the hydro generation facilities are operating under derated capacity due to various factors. The availability of generation facilities is decreasing, the cost for maintenance is going up and plants are crippled with severe faults leading to outages. The feasibility study for aging hydro-power plant is carried out with an objective to find out the best possible alternative both with respect to reliability of operation and benefit to cost ratio. The multi-criterion weighted average condition evaluation of hydro-electric generator is carried out. A Visual Basic and Microsoft Excel based condition evaluation program is implemented for possible condition decision making …

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Parallel Interference Cancellation Multiuser Detectors For Ds-Cdma Communication Systems, Feng Liu Apr 2006

Parallel Interference Cancellation Multiuser Detectors For Ds-Cdma Communication Systems, Feng Liu

Electrical Engineering Dissertations - Archive

A non-linear sub-optimal multiuser detector in the form of parallel interference cancellation (PIC) has been studied. The main objective of this thesis is to develop an analytical model for PIC performance analysis and propose new near-optimum approach. Since the exact performance analysis of PIC is difficult to derive due to its nonlinear decision function, previous work tends to adopt computer simulation method or evaluate through Gaussian approximation (GA) method. For PIC detector, the GA method may not apply since there may exist a dominate interference signal. In addition, the central limit theorem is not applicable to model the residual MAI …

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Multi-Area Unit Commitment And Economic Dispatch With Market Operation Components, Chitra Yingvivatanapong Apr 2006

Multi-Area Unit Commitment And Economic Dispatch With Market Operation Components, Chitra Yingvivatanapong

Electrical Engineering Dissertations - Archive

Unit commitment and economic dispatch, when combined together, is a useful tool to find the most economical generation schedule with which demand and spinning reserve requirement are supplied and all generating unit constraints, such as unit ramp rates, unit minimum and maximum generation capabilities, and unit minimum up-time and down-time, are satisfied over a time horizon. For systems consisting of multiple areas, area import/export capabilities and tie line capacity constraints also need to be taken into account. Enhanced Lagrangian relaxation, unit decommitment and lambda-iteration methods are applied in this dissertation to determine the optimal unit commitment and economic dispatch schedule …

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Adaptive Sampling With Mobile Wsn, Koushil Sreenath Dec 2005

Adaptive Sampling With Mobile Wsn, Koushil Sreenath

Electrical Engineering Theses - Archive

The spatiotemporally varying network topology of mobile sensor networks makes it very suitable for applications such as reconstruction of environmental fields through sampling at locations that maximally reduce the largest uncertainty in the field estimate. Mobile sensor networks comprise of multiple heterogeneous resources and a deadlock-free resource scheduling in the presence of shared and routing resources becomes necessary to schedule the most efficient (cost / energy / time) resource for a task. Location information is imperative in sensor networks for most applications for localized sensing where localizing the network adaptively with no additional hardware is important. Adaptive sampling approaches for …

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Data-Logging & Supervisory Control In Wireless Sensor Networks, Choudhury Aditya Narayan Das Dec 2005

Data-Logging & Supervisory Control In Wireless Sensor Networks, Choudhury Aditya Narayan Das

Electrical Engineering Theses - Archive

This thesis mainly emphasizes on the inclusion and implementation of the Supervisory control unit in the wireless sensor networks with a brief overlook on the cross-bow sensors and mobile sentry robots. The aim of this research has been to design an application module which would be able to manipulate the data effectively and support the Discrete Event Controller in generating the rule-based tasks by solving major issues like data-logging, alarm and event reporting and security concerns. The PC-based data logging systems provide the most flexibility, customization, and integration to the Wireless Sensor Network research project. This work has been supported …

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Efficient Transcoding Of An Mpeg-2 Bit Stream To An H.264 Bit Stream, Rochelle B. Pereira Dec 2005

Efficient Transcoding Of An Mpeg-2 Bit Stream To An H.264 Bit Stream, Rochelle B. Pereira

Electrical Engineering Theses - Archive

Low complexity fast transcoding of an MPEG-2 elementary stream to an H.264 elementary stream. Objective: MPEG-2 has been a widely accepted video coding standard for various applications ranging from DVD to digital TV broadcast. The new H.264 AVC standard has an even broader perspective to support high and low bit rate multimedia applications on existing and future networks. The advantage in terms of better quality at a lower bit rate is why H.264 is fast replacing MPEG-2. However, the user end hardware had previously been adapted for MPEG-2 streams. This gives rise to a need for portability between MPEG-2 and …

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Analysis And Characterization Of Thermal Effects In Analog Circuits, Abhijit Avinash Chaugule Dec 2005

Analysis And Characterization Of Thermal Effects In Analog Circuits, Abhijit Avinash Chaugule

Electrical Engineering Theses - Archive

Dielectrically Isolated Bipolar Junction Transistors (DIBJTs) are used in industry for high speed and high power applications. These devices suffer from thermal heating and are subjected to change in their characteristics. This thesis explores the thermal effects involving the self heating and inter-device heating (thermal coupling) at the device as well as at the circuit level. Systematic analysis of individual device heating characteristics in a particular Current feedback operational amplifier (CFOA) design is carried out, using the VBIC (Vertical Bipolar Inter-company) model in the the Cadence SpectreS simulator. A diagnostic and design procedure is established for circuit designers to determine …

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Human Performance Multimeter: Investigation Of The Fourth Generation Prototype, Rahul Mulukutla Dec 2005

Human Performance Multimeter: Investigation Of The Fourth Generation Prototype, Rahul Mulukutla

Electrical Engineering Theses - Archive

The focus of this thesis is the development and investigation related to the newest prototype version of the Human Performance MultiMeter (HPMM). Version 4 is a technologically advanced, compact, portable and self-contained unit that is the result of an on-going effort in human performance measurement covering a 25 year history at the Human Performance Institute involving the conception, development, and evaluation of over four hundred different measures. Such measurements are applicable in areas ranging from medical diagnosis and rehabilitation to ergonomics and athletic proficiency. The work included verification of the functionality of a new hardware platform, modification of previously developed …

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Wavelet Domain Diversity Method For Transmission Of Images Over Wireless Sytems Using Hybrid (Ofdm-Cdma-Sfh) Concept And Its Real Time Implementation In Tms320c6713 Dsp Development Board, Madhu Rangappagowda Dec 2005

Wavelet Domain Diversity Method For Transmission Of Images Over Wireless Sytems Using Hybrid (Ofdm-Cdma-Sfh) Concept And Its Real Time Implementation In Tms320c6713 Dsp Development Board, Madhu Rangappagowda

Electrical Engineering Theses - Archive

In this thesis a new OFDM based wavelet domain diversity combining method is proposed to combat errors during image transmission on wireless channels. A novel concept of utilizing OFDM sub-carriers to attain diversity is designed and analyzed. For images represented in the wavelet domain, diversity is used to obtain multiple data streams using OFDM symbols corresponding to the transmitted image at the receiver. These individual image data streams are combined to form a composite image with higher perceptual quality. Both uncompressed and compressed images are considered. The SPIHT algorithm is used for image compression. Diversity combining methods for both uncompressed …

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