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Articles 631 - 656 of 656

Full-Text Articles in Electrical and Computer Engineering

Cmos Optical Transimpedance Amplifier Design For Pam Signaling Application, Hemalatha Shanmugasundaram Dec 2005

Cmos Optical Transimpedance Amplifier Design For Pam Signaling Application, Hemalatha Shanmugasundaram

Electrical Engineering Theses - Archive

The advent of Internet telephony and the surge in data communication field necessitate the use of broadband communication systems. The Optical communication systems has been suggested as an attractive solution to cope with the high speed data rate and large throughput bottleneck of the long haul communication systems due to their cheaper deployment cost. In the world of miniaturization, CMOS circuits have been widely used to develop the opto-electronic components. However, the intricacy involved in the design of high speed optical front-end is higher due to the poor noise performance of CMOS circuits compared to their bipolar counter parts. Despite …

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A Cmos Ultra-Wideband Differential Low Noise Amplifier, Timothy Bryan Merkin Nov 2005

A Cmos Ultra-Wideband Differential Low Noise Amplifier, Timothy Bryan Merkin

Electrical Engineering Theses - Archive

In this thesis, a CMOS Ultra-wideband (UWB) Low noise Amplifier (LNA) was designed and simulated. In the design, specific architecture decisions were made in consideration of ultimately including this LNA in a system-on-chip implementation of an Ultra-wideband communication system. The basic architecture of the LNA designed herein exhibits a differential amplifier core with active input and output impedance matching, minimizing the number of expensive space consuming passive inductors necessary for passive impedance matching networks. The LNA maintains a gain of 16.4dB with a ±0.25dB ripple over the band of 3.1-6.2GHz. Despite the use of an active input matching stage, the …

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Cmos 5th Derivative Gaussian Impulse Generator For Uwb Application, Shin-Chih Chang Nov 2005

Cmos 5th Derivative Gaussian Impulse Generator For Uwb Application, Shin-Chih Chang

Electrical Engineering Theses - Archive

A complete impulse generating system was designed and simulated which generates the fifth order derivative of the Gaussian pulse intended for use in an impulse-type ultra-wideband wireless communication system. By using a continuous-time FIR impulse shaping filter, the system transforms a normal Gaussian pulse signal obtained from an existing CMOS Gaussian pulse generator into its fifth derivative. The transformation filtering was accomplished without lengthening the time duration of the original pulse or causing any noticeable ringing effects. The final output waveform closely resembles the fifth derivative of the Gaussian pulse, and also satisfies the spectral mask emission requirements specified by …

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A Simulation Tool Suite For The Modeling And Optimization Of Multiple Quantum Well Structures, Jeffery Wayne Allen Nov 2005

A Simulation Tool Suite For The Modeling And Optimization Of Multiple Quantum Well Structures, Jeffery Wayne Allen

Electrical Engineering Theses - Archive

This thesis aims to develop a suite of computational tools for design, analysis, and simulation of semiconductor multiple quantum well structures with a user-friendly GUI. The research project focuses on the electrical and optical aspects of user defined quantum well structures, and allows the user to vary design parameters to optimize the structure for different device applications and functionality. Specifically the thesis delves into the design and analysis of different quantum well structures as they relate to band gap engineering. Key features of this computational suite include relationship to electrical field, doping profiles and optical transitions. The quantum well structures …

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Optimization Of H.264 Baseline Decoder On Arm9tdmi Processor, Sandya B. Sheshadri Nov 2005

Optimization Of H.264 Baseline Decoder On Arm9tdmi Processor, Sandya B. Sheshadri

Electrical Engineering Theses - Archive

With the newly introduced features and advancements to the pre-existing features, the emerging H.264 video coding standard achieves significant improvements in coding performance over all existing standards, in a wide variety of applications. The coding-efficiency advantages of H.264, however, come at the expense of higher computational complexity. H.264 decoders can exhibit more than double the complexity of H.263 decoders. Furthermore, previous studies have shown that fractional-pixel motion-compensation interpolation and the loop filtering consume a significant amount of computational power in emerging H.264 decoders. Since these operations are part of the baseline profile of H.264, there is a need to evaluate …

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Region Of Interest (Roi) Based Rate Control For H.263 Compatible Video Conferecing, Lin Tong Nov 2005

Region Of Interest (Roi) Based Rate Control For H.263 Compatible Video Conferecing, Lin Tong

Electrical Engineering Dissertations - Archive

This dissertation presents a region of interest (ROI) based H.263 [10] [13] compatible video codec, which integrates the idea of object-based coding from MPEG-4 Visual [9] [15] into the traditional block-based H.263 codec. A face detection and tracking scheme with very low complexity is proposed to segment human face region from video conferencing sequences in real-time. For intra frames, the proposed detection method is a hybrid skin color and mosaic-rule based face detection and for inter frames the face tracking method uses motion vectors only. With the segmentation information, the ROI based codec and its associated rate control schemes are …

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Error-Resilient Image And Video Coding Over Lossy Networks, Yilong Liu Nov 2005

Error-Resilient Image And Video Coding Over Lossy Networks, Yilong Liu

Electrical Engineering Dissertations - Archive

The rapid growth of the Internet and increasing bandwidth in the past decade has heightened the interest in robust transmission of image and video signals over error-prone links. Recent literatures highlight the multiple description (MD) coding as a promising approach to solve this problem. MD coding is a source coding technique that provides a graceful quality degradation in the presence of packet losses during transmission. Topics of interest to construct MD coders with high coding efficiency and robustness are studied in this thesis. First, to minimize the overall distortion of reconstructed image, an edge-adaptive estimation algorithm is employed, which can …

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Eigenspace Model Based Error Concealment And Low Bit Rate Coding Of Face Sequences, Xuejun Hu Nov 2005

Eigenspace Model Based Error Concealment And Low Bit Rate Coding Of Face Sequences, Xuejun Hu

Electrical Engineering Dissertations - Archive

The emerging multimedia applications address the increasing demand for novel video coding systems to provide higher compression ratio while maintaining the high quality of the reconstruction. This research makes an effort under such context to investigate the application of principal component analysis (PCA) in the video coding area, especially for error concealment and very low bit rate face coding. PCA is a well known optimal linear scheme for dimension reduction in data analysis. The central idea of PCA is to reduce the dimensionality of a data set while retaining as much as possible the variation in the data set. Since …

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Modeling And Feedback Control Of Mems Devices, Bruno Borovic Nov 2005

Modeling And Feedback Control Of Mems Devices, Bruno Borovic

Electrical Engineering Dissertations - Archive

As MEMS actuators reach maturity and emerge from the research lab into commercial applications, their increased reliability, speed, and performance accuracy is needed. MEMS are typically driven directly in an open-loop fashion by applying simple actuating signals. The requirements for better dynamical behavior, however, have resulted in the gradual introduction of improved actuation approaches, such as pre-shaped open-loop driving and closed-loop control. Unlike macro mechanical systems where the implementation of the feedback is relatively simple, it is quite problematic in the MEMS case. The presence of fast system dynamics, and physical area efficiency requirements have introduced additional challenges for feedback …

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Optimization Of H.264 High Profile Decoder For Pentium 4 Processor, Tarun Bhatia Nov 2005

Optimization Of H.264 High Profile Decoder For Pentium 4 Processor, Tarun Bhatia

Electrical Engineering Theses - Archive

H.264 is an emerging video coding standard, which aims at compressing high-quality video content at low-bit rates. While the basic idea behind the encoding and decoding process still remains the same as in the previous standards, many new and innovative tools have been added to provide higher compression capabilities with high perceptual quality. These capabilities have also contributed to the increase in complexity of implementation of H.264 significantly compared to the previous generation of video coding standards. In this thesis, the performance analysis of the H.264 decoder for decoding of high profile high definition data is done for the Pentium …

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Integrated High Speed Intelligent Utility Tie Unit For Disbursed/Renewable Generation Facilities, Worakarn Wongsaichua Nov 2005

Integrated High Speed Intelligent Utility Tie Unit For Disbursed/Renewable Generation Facilities, Worakarn Wongsaichua

Electrical Engineering Dissertations - Archive

After experiencing the price hikes and rotating blackouts in California, the disbursed or distributed generation (DG) is considered as one of the most attractive alternatives for future utility industry. In addition to the conventional DG that uses fossil-fuel to generate power, the DG via renewable energy is of interest due to the environmental concern. Fuel cell and photovoltaic are the most promising technologies for the urban residential and small commercial users. For economic and reliability purposes, it is desirable for these facilities to be interconnected with the utility grid to perform peak shaving, demand reduction, and to serve as emergency …

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Improving The Quality Of Low Bitrate Lpc Speech Codec Using Gamma-Chirp Filterbank, Amin Khajeh Djahromi Sep 2005

Improving The Quality Of Low Bitrate Lpc Speech Codec Using Gamma-Chirp Filterbank, Amin Khajeh Djahromi

Electrical Engineering Theses - Archive

In this thesis, two methods for getting higher speech quality in low bit-rate LPC coder in comparison with the original LPC coder were presented. In order to improve the quality of the speech, the embedded method which can take the place of the traditional synthesis algorithm in LPC coders and the post-processing method that also can be used as the last stage in the LPC-coder based systems were proposed. In the embedded method, the result of MOS test of the synthesized speech increased by 0.8 and in the post-processing method the result of MOS test of the synthesized speech increased …

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Modeling And Characterization Of A Fabry Perot Pressure Sensor, Shruthika Prasanna Aug 2005

Modeling And Characterization Of A Fabry Perot Pressure Sensor, Shruthika Prasanna

Electrical Engineering Theses - Archive

Fabry-Perot interferometers (FPIs) have been used as sensing elements for pressure transducers in many applications. Most of the current FPI pressure sensors measure amplitude changes of the reflected signals from a deformable diaphragm. A new technique to design an FPI pressure sensor has been proposed in this thesis. The proposed methodology aims to maximize the sensitivity by measuring frequency shifts and optimize the dimensions of the sensors for various materials and applications. The sensor diaphragm is built directly on the end surface of an optical fiber with a sacrificial layer introducing the required FPI cavity height. The resulting sensor detects …

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Physics Based Time-Frequency Analysis To Reduce Multi-Bounce And Clutter In Radar Imaging, Anilkumar Kollipara Aug 2005

Physics Based Time-Frequency Analysis To Reduce Multi-Bounce And Clutter In Radar Imaging, Anilkumar Kollipara

Electrical Engineering Theses - Archive

The concept of time-frequency analysis of the scattered far field data from multiple targets is presented. The scattered data from the target is collected using a mono-static antenna configuration. The hardware system and the data acquisition system used in the process are discussed in detail. The results obtained using the ISAR imaging algorithm are presented and the effect of different non-point and dispersive scattering phenomena on these images are discussed. A physics based time-frequency analysis using wavelets is done on this scattered data to reduce the inter-target interactions and thereby produce cleaner images of the target under consideration. The results …

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Optical Amplifiers For 10 Gb/S Wdm Recirculating Loop Testbed, Sravanthi Thotakura Aug 2005

Optical Amplifiers For 10 Gb/S Wdm Recirculating Loop Testbed, Sravanthi Thotakura

Electrical Engineering Theses - Archive

This Master's thesis deals with building experimental setup for characterization of novel nonlinear optical devices for fiber communication. The first part of the thesis deals with the description of the theoretical basis for operation of a particular type of such nonlinear optical devices, namely a parametric amplifier. Document includes deriving and solving the equations for parametric amplification in optical fiber when signal, idler and pump beams are linearly co-polarized. We consider both non-degenerate and degenerate pump cases for arbitrary phase mismatch. In the second part of the thesis we present the design and experimental implementation of electrical interface between commercial …

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Time Synchronization In Network-Centric Sensor Networks, Sejal D. Raje Aug 2005

Time Synchronization In Network-Centric Sensor Networks, Sejal D. Raje

Electrical Engineering Theses - Archive

Time synchronization is a crucial component of infrastructure for wireless sensor networks (WSN). Most applications of WSNs make extensive use of time synchronization, for accurate timestamping of events, coordinate activities of the network, data fusion, object tracking or TDMA scheduling. The unique requirements of sensor networks in terms of precision, lifetime, energy and scope of the synchronization achieved, calls for design of new synchronization methods for WSNs. In this thesis, we describe the design of three novel techniques for achieving synchronization in network centric scenario of sensor networks: sequential least squares, Kalman filter and fuzzy logic systems. The strength of …

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Collision Response For Virtual Laparoscopic Surgery, Jitesh Devidas Butala Aug 2005

Collision Response For Virtual Laparoscopic Surgery, Jitesh Devidas Butala

Electrical Engineering Theses - Archive

During laparoscopic surgery the surgeon operates inside the abdomen guided by the 2D imagery of the operating area. This image is obtained via a camera inserted through a small incision. Laparoscopic surgery, in contrast to open surgery, results in low pain and recovery time for the patient. However, the surgeons have some difficulty, as the training required for this type of surgery is more intense and rigorous than that for conventional open surgery. Hence, surgical trainers for laparoscopic surgery are important. The main difference in the different types of surgical trainers is the degree to which the actual environment of …

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Structure & Decision In Mobile Wireless Sensor Networks, Prasanna Mohan Ballal Aug 2005

Structure & Decision In Mobile Wireless Sensor Networks, Prasanna Mohan Ballal

Electrical Engineering Theses - Archive

This work concerns the development of a novel structure of Discrete Event Controller (DEC) for mobile wireless sensor networks consisting of mobile robots and stationary wireless sensing nodes known as Unattended Ground Sensors (UGS). These are the three contributions: 1. Decision-making systems such as Fuzzy Logic and Dempster Shafer Theory for sensor fusion are implemented. 2. Decision-making is used for a special case of routing of resources for multiple tasks performed by different resources. 3. The DEC was actually implemented in the Mobile Wireless Sensor Networks lab at Automation & Robotics Research Institute. This work was supported by ARO grant …

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Nonlinear H2/H∞ Constrained Feedback Control: A Practical Design Approach Using Neural Networks, Murad Abu-Khalaf Aug 2005

Nonlinear H2/H∞ Constrained Feedback Control: A Practical Design Approach Using Neural Networks, Murad Abu-Khalaf

Electrical Engineering Dissertations - Archive

In this research, practical methods for the design of H2 and H8 optimal state feedback controllers for constrained input systems are proposed. The dynamic programming principle is used along with special quasi-norms to derive the structure of both the saturated H2 and H8 optimal controllers in feedback strategy form. The resulting Hamilton-Jacobi-Bellman (HJB) and Hamilton-Jacobi-Isaacs (HJI) equations are derived respectively. It is shown that introducing quasi-norms on the constrained input in the performance functional allows unconstrained minimization of the Hamiltonian of the corresponding optimal control problem. Moreover, it is shown how to obtain nearly optimal minimum-time and constrained state controllers …

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Low Phase Noise Voltage-Controlled Oscillator Design, Zhipeng Zhu Aug 2005

Low Phase Noise Voltage-Controlled Oscillator Design, Zhipeng Zhu

Electrical Engineering Dissertations - Archive

Two kinds of voltage-controlled oscillators (VCO) - active inductor based VCO and LC cross-coupled VCO - are studied in this work. Although the phase noise performance is not competitive, the proposed active inductor based VCO provide an alternative method to VCO design with very small chip area and large tuning range. The measurement shows a test oscillator based on active inductor topology successfully oscillates near 530MHz band. The phase noise of the widely used LC cross-coupled VCO is extensively investigated in this work. Under the widely used power dissipation and chip area constraints, a novel optimization procedure in LC oscillator …

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Power Management Integrated Circuits Design, Functionality Analysis And Applications, Zheng Li Aug 2005

Power Management Integrated Circuits Design, Functionality Analysis And Applications, Zheng Li

Electrical Engineering Dissertations - Archive

Power management is playing a significant role in modern electronics. Good power management is especially important for portable devices that rely on batteries. By smartly managing how the power is directed to different components of a system, e.g., reducing power to components that are not being used, the efficiency as well as the battery lifetime can be doubled or tripled. There exists a large family of integrated circuits (IC) that are used for power management, e.g., linear regulators, switching regulators, power controllers, hot swap controllers, etc. The voltage reference is one of the key components in this family. For high …

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The Operation Platform Recommendation For The Deregulated Utility Industry In Thailand, Chai Chompoo-Inwai Aug 2005

The Operation Platform Recommendation For The Deregulated Utility Industry In Thailand, Chai Chompoo-Inwai

Electrical Engineering Dissertations - Archive

Transmission Congestion Management (TCM) plays a significant role in power system operation under today deregulated environment. It has two major functions of an apparatus to keep power system running within acceptable security limits, and of a tool allocating financial obligation to market participants then paying back to transmission grid investors. TCM issue has been widely debating during a past decade, until now, it is still an opened issue extensively discussed in the current structure of competitive environment. In the United State, there are existing two successful stories of TCM under different operation schemes, the former is PJM with Nodal Congestion …

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Shared Data Acquisition System For Real-Time Power Systems Applications, Yi-Fang Hsu Aug 2005

Shared Data Acquisition System For Real-Time Power Systems Applications, Yi-Fang Hsu

Electrical Engineering Theses - Archive

Digital signal processing chip (DSP's) can be used to perform data analysis computation and have very good performance in real-time system. Digital filters can be designed with consideration of both magnitude and phase responses for digital re-sampling in power system applications. The design consists of two parts: magnitude approximation and group delay compensation. It compromises between the amount of calculation needed to implement the filters and the performance of the filters, which makes the filters good candidates for both real-time and offline applications.

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Analysis And Modeling Of A Micro Variable Capacitance Electromechanical Energy Converter, Amita Jindal Aug 2005

Analysis And Modeling Of A Micro Variable Capacitance Electromechanical Energy Converter, Amita Jindal

Electrical Engineering Theses - Archive

Research and development in microelectromechanical systems (MEMS) have made remarkable progress since 1988. Micro-machines are an integral part of MEMS. However, these machines are not often discussed in most electric machines, power electronics and drive forums due to the relative newness of these machines. This thesis provides an in-depth analysis of a variable capacitance micro-machine (VCM). It gives an insight into the effects of machine geometry, on capacitance and torque profiles of the machine. Tangential and radial components of the electrostatic forces in the air gap of the machine have been investigated to study the effects of mutual flux. These …

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Deformable Haptic Models For Surgical Simulation, Xiuzhong Wang Jul 2005

Deformable Haptic Models For Surgical Simulation, Xiuzhong Wang

Electrical Engineering Dissertations - Archive

Surgical simulation is in great need for surgical training, analysis, planing and rehearsal. The core of this simulation is the deformable models for the organs. The deformable model must provides both realistic visual effects (graphics) and high fidelity force feedback (haptics) in real time, without distractive visual artifacts and misleading tactile clues. In view of the requirement of physical accuracy, physically based deformable models are favorable for surgical simulation. Physically based deformable modeling has been a serious research topic for about twenty years in the computer graphics community. For computer animation, a great deal of work has been done so …

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Effects Of Base Station Power Control And Soft Handoff On The Outage And Capacity In The Forward Link Of Cdma Systems, Dongdong Li Jul 2005

Effects Of Base Station Power Control And Soft Handoff On The Outage And Capacity In The Forward Link Of Cdma Systems, Dongdong Li

Electrical Engineering Dissertations - Archive

This thesis focuses on the capacity analysis of the forward link of code division multiple access (CDMA) systems by characterizing the base station (BS) power distribution. With the rapid growth of data and multi-media traffic, the forward link becomes the system bottleneck. How to design an efficient call admission algorithm in the forward link to effectively use the limited base station power while guaranteeing certain quality of service is important to increase the forward link capacity. To effectively use the limited BS power, we need to understand the BS power distribution given a certain traffic pattern. However, the characterization of …

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