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Articles 301 - 330 of 427

Full-Text Articles in Electrical and Computer Engineering

Physical Layer Secrecy Channel Coding, Bandali K. Akkawi Jan 2008

Physical Layer Secrecy Channel Coding, Bandali K. Akkawi

LSU Master's Theses

Wireless communications is expanding and becoming an indispensable part of our daily life. However, due to its channel open nature, it is more vulnerable to attacks, such as eavesdropping and jamming which jeopardize the confidentiality of wireless data, compared to its counter-part, wireline communications. Security in wireless communication is thus a very important factor that should be perfected to accommodate the rapid growth of wireless communication today. Motivated by information theoretic secrecy definitions, we adopt a simple way to define the secrecy of a system by looking at its Bit-Error-Rate (BER) curves, the correlation of error vectors and Log Likelihood …

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Quiescent Current Testing Of Cmos Data Converters, Siva Yellampalli Jan 2008

Quiescent Current Testing Of Cmos Data Converters, Siva Yellampalli

LSU Doctoral Dissertations

Power supply quiescent current (IDDQ) testing has been very effective in VLSI circuits designed in CMOS processes detecting physical defects such as open and shorts and bridging defects. However, in sub-micron VLSI circuits, IDDQ is masked by the increased subthreshold (leakage) current of MOSFETs affecting the efficiency of I¬DDQ testing. In this work, an attempt has been made to perform robust IDDQ testing in presence of increased leakage current by suitably modifying some of the test methods normally used in industry. Digital CMOS integrated circuits have been tested successfully using IDDQ and IDDQ methods for physical defects. However, testing of …

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Channel Modeling And Resource Allocation In Ofdm Systems, Xiang Gao Jan 2007

Channel Modeling And Resource Allocation In Ofdm Systems, Xiang Gao

LSU Doctoral Dissertations

The increasing demand for high data rate in wireless communication systems gives rise to broadband communication systems. The radio channel is plagued by multipath propagation, which causes frequency-selective fading in broadband signals. Orthogonal Frequency-Division Multiplexing (OFDM) is a modulation scheme specifically designed to facilitate high-speed data transmission over frequency-selective fading channels. The problem of channel modeling in the frequency domain is first investigated for the wideband and ultra wideband wireless channels. The channel is converted into an equivalent discrete channel by uniformly sampling the continuous channel frequency response (CFR), which results in a discrete CFR. A necessary and sufficient condition …

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Computer Model Of Hybrid Compensator Of Fast Varying Loads, Veronica Bohorquez Jan 2007

Computer Model Of Hybrid Compensator Of Fast Varying Loads, Veronica Bohorquez

LSU Doctoral Dissertations

A computer model of the hybrid compensator of fast varying loads was developed in this dissertation. The computer model was implemented in MFC Visual C++ compiler version 6.0. The classification of fast varying loads and effects of their operation in distribution systems were described in this dissertation. The power properties of fast varying loads were expressed in terms of the Currents' Physical Components Theory. Therefore, the Currents' Physical Components Theory was applied to systems with non-periodic voltages and currents. The supply current of the fast varying loads was decomposed into the useful and the useless components using an algorithm based …

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Comparative Study On Double-Rotor Pm Brushless Motors With Cylindrical And Disc Type Slot-Less Stator, Pavani Gottipati Jan 2007

Comparative Study On Double-Rotor Pm Brushless Motors With Cylindrical And Disc Type Slot-Less Stator, Pavani Gottipati

LSU Master's Theses

Among brushless permanent magnet machines, the torus motors (also called Axial Flux Double-Rotor Permanent Magnet (AFTR PM) motors) are most compact and highly efficient. A cylindrical counterpart of this motor is a newly proposed Radial Flux Double-Rotor Permanent Magnet (RFTR PM) motor. The objectives of this thesis are to optimize the magnetic circuit of both AFTR PM and RFTR PM motors and to compare their electromechanical parameters on the basis of the results obtained from magnetic field simulation using Finite Element Method (FEM). To reach these objectives, FEM models are developed for both the motors, for particular given data. Applying …

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A Novel Template Stage With Superior Alignment Capability For Nanoimprint And Step And Flash Lithography, Yunmi Jeon Jan 2007

A Novel Template Stage With Superior Alignment Capability For Nanoimprint And Step And Flash Lithography, Yunmi Jeon

LSU Master's Theses

The high-resolution capabilities of imprinting and step and flash lithography make these techniques strong contenders for the next generation lithography. Unfortunately, alignment remains an area of concern for nanoimprint because it must be completed before the template is moved into contact with the wafer. The large forces on the template during the process, even for step and flash, place additional demands on the stiffness as well as the reproducibility of the template stage. In this thesis, a prototype flexure stage has been developed to meet these demands. A compressive load, slightly below the Euler's limit, is used to produce relatively …

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A Liquid Lens Based On Electrowetting, Jihwan Park Jan 2007

A Liquid Lens Based On Electrowetting, Jihwan Park

LSU Master's Theses

A primary goal of this work is to develop and characterize a novel liquid lens based on electrowetting. A droplet of silicone oil confined in an aqueous solution works as a lens. Electrowetting then controls the shape of the confined silicone oil, and the focal length may be varied upon an applied electric potential. The planar lens design is employed for easy integration of a lens system into a microfluidic device. The achievements of this work are to develop an electrowetting-based planar liquid lens without an off-the-plane electrode structure and to demonstrate the planar liquid lens with variable focal length …

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Data Compression With Application To Geo-Location, William Perkins Jan 2007

Data Compression With Application To Geo-Location, William Perkins

LSU Master's Theses

A common way to locate an emitter within a wireless sensor network requires the estimation of time-difference-of-arrival (TDOA) parameters using data collected by a set of spatially separated sensors. Compressing the data that is shared among the sensors can provide tremendous savings in terms of the energy and transmission latency. Traditional MSE and perceptual based data compression schemes fail to accurately capture the effects of compression on the TDOA estimation task; therefore, it is necessary to investigate compression algorithms suitable for TDOA parameter estimation. This thesis explores the effects of data compression on TDOA parameter estimation accuracy. The first part …

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Optimum Energy Allocation For Detection In Wireless Sensor Networks, Krishna Kishore Gunturu Jan 2007

Optimum Energy Allocation For Detection In Wireless Sensor Networks, Krishna Kishore Gunturu

LSU Master's Theses

The problem of binary hypothesis testing in a wireless sensor network is studied in the presence of noisy channels and for non-identical sensors. We have designed a mathematically tractable fusion rule for which optimal energy allocation for individual sensors can be achieved. In this thesis we considered two methods for transmitting the sensor observations; binary modulation and M-ary modulation. In binary modulation we are able to allocate the energy among the sensors and protect the individual quantized bits where as the M-ary modulation provides optimum energy allocation only among the sensors. The goal is to design a fusion rule and …

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Predictive Data Compression Using Adaptive Arithmetic Coding, Claudio Jose Iombo Jan 2007

Predictive Data Compression Using Adaptive Arithmetic Coding, Claudio Jose Iombo

LSU Master's Theses

The commonly used data compression techniques do not necessarily provide maximal compression and neither do they define the most efficient framework for transmission of data. In this thesis we investigate variants of the standard compression algorithms that use the strategy of partitioning of the data to be compressed. Doing so not only increases the compression ratio in many instances, it also reduces the maximum data block size for transmission. The partitioning of the data is made using a Markov model to predict if doing so would result in increased compression ratio. Experiments have been performed on text files comparing the …

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Sigma-Delta Modulation Based Distributed Detection In Wireless Sensor Networks, Dimeng Wang Jan 2007

Sigma-Delta Modulation Based Distributed Detection In Wireless Sensor Networks, Dimeng Wang

LSU Master's Theses

We present a new scheme of distributed detection in sensor networks using Sigma-Delta modulation. In the existing works local sensor nodes either quantize the observation or directly scale the analog observation and then transmit the processed information independently over wireless channels to a fusion center. In this thesis we exploit the advantages of integrating modulation as a local processor into sensor design and propose a novel mixing topology of parallel and serial configurations for distributed detection system, enabling each sensor to transmit binary information to the fusion center, while preserving the analog information through collaborative processing. We develop suboptimal fusion …

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Performance Analysis Of Intel Core 2 Duo Processor, Tribuvan Kumar Prakash Jan 2007

Performance Analysis Of Intel Core 2 Duo Processor, Tribuvan Kumar Prakash

LSU Master's Theses

With the emergence of thread level parallelism as a more efficient method of improving processor performance, Chip Multiprocessor (CMP) technology is being more widely used in developing processor architectures. Also, the widening gap between CPU and memory speed has evoked the interest of researchers to understand performance of memory hierarchical architectures. As part of this research, performance characteristic studies were carried out on the Intel Core 2 Duo, a dual core power efficient processor, using a variety of new generation benchmarks. This study provides a detailed analysis of the memory hierarchy performance and the performance scalability between single and dual …

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Differential Space Time Modulation And Demodulation For Time Varying Multiple Input Multiple Output Channels, Chetan Neginhal Chitnis Jan 2007

Differential Space Time Modulation And Demodulation For Time Varying Multiple Input Multiple Output Channels, Chetan Neginhal Chitnis

LSU Master's Theses

Over the last decade there has been considerable interest in wireless communication using multiple transmit and receive antennas. Several literatures exists that show that these multiple link support very high data rates with low error probabilities when the channel state information is available at the receiver. However when multiple antennas are employed or when the mobile environments change rapidly, it is not always possible to have apriori knowledge of the channel state matrices which calls for Differential Space-Time modulation techniques. Differential modulation is used in conjunction with Unitary Space-Time codes to evaluate their performance over time varying channels. Jakes model …

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A Collaborative High Performance And Grid Computing Portal, Prathyusha Akunuri-Venkata Jan 2007

A Collaborative High Performance And Grid Computing Portal, Prathyusha Akunuri-Venkata

LSU Master's Theses

The world of high performance and grid computing is so vast that it always poses constant challenges and high learning curves to researchers and scientists. A Portal-based solution facilitates a simple web-based graphical user interface that helps the non computer science users take advantage of highly evolving, on-demand, distributed computing to carry out their research activities. A collaborative portal brings together various resources, applications and services under one roof and provides a single point of entry and access to the users. This thesis work endeavors to build a unique High Performance and Grid Computing Portal that combines two existing high …

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A Study On Buckled-Beam Actuators For Rf Mems Applications, Seunghoon Park Jan 2007

A Study On Buckled-Beam Actuators For Rf Mems Applications, Seunghoon Park

LSU Master's Theses

When combined with MEMS actuators, a mechanical lock is a useful device for various applications including memory cells, micro-relays, micro-valves, optical switches, and digital micro-mirrors. It allows removal of actuation force during idle periods without affecting an actuated state of a device, which makes standing power consumption completely unnecessary. In this thesis, a bistable buckled-beam actuator for RF MEMS switch applications has been examined. The buckled-beam geometry was designed based upon theoretical analysis. It was fabricated by SU-8 lithography and copper pulse electroplating. It was actuated by the Lorentz force using external magnet and current flow through the beam. Measured …

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Quasi Group Based Crypto-System, Maruti Venkat Kartik Satti Jan 2007

Quasi Group Based Crypto-System, Maruti Venkat Kartik Satti

LSU Master's Theses

For electronic commerce and other applications it is required to encrypt data that is transmitted over an unsecured channel. The data is encrypted/randomized using a key. Algorithms such as DES and ECC randomize the data such that un-authorized user cannot decrypt it .This thesis presents a practical implementation of a quasi group based multilevel, indexed scrambling transformation for use in signal encryption. Results of experiments with text and speech scrambling are presented. It is shown that the quasi group transformation maximizes the entropy at the output, which is desirable for a good system. This system provides extremely large group of …

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Characterization And Analysis Of Hybrid Electronic Materials For Molecular Based Devices, Sathish Thiruvengadam Jan 2007

Characterization And Analysis Of Hybrid Electronic Materials For Molecular Based Devices, Sathish Thiruvengadam

LSU Master's Theses

The goal of this work is to characterize and to analyze hybrid electronic materials (HEMs) using fluorescence (FL) spectroscopy and conductive probe-atomic force microscopy (CP-AFM) in order to investigate the electrical and optical properties of these materials. Currently, research efforts to characterize novel organic materials for the determination of molecular level transport properties are of great interest.[6] One of the most interesting organic materials is the porphyrin molecule, which exhibits behavior useful for memory applications.[4] Colloidal CdS quantum dots (Q-CdS) capped with dioctyl sulfosuccinate (AOT) and thiol functionalized porphyrin molecules are explored for their potential application to next-generation hybrid electronic …

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Oblivious Transfer For Secure Communication, Abhishek Parakh Jan 2007

Oblivious Transfer For Secure Communication, Abhishek Parakh

LSU Master's Theses

Over the past four decades, computational power and algorithmic strategies have advanced tremendously resulting in an enormous increase in the key sizes required for secure cryptosystems such as RSA. At the same time, the electronic devices have grown smaller and portable requiring algorithms running on them to be optimized in size and efficiency while providing security, at least, equivalent to that provided on a typical desktop computer. As a result, the industry is moving towards newer cryptosystems such as ECC and NTRU that are well suited for resource constrained environments. While, ECC claims to provide security equivalent to that of …

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Fabrication Of Single Walled Carbon Nanotube (Sw-Cnt) Cantilevers For Chemical Sensing, Jui-Ching Hsu Jan 2007

Fabrication Of Single Walled Carbon Nanotube (Sw-Cnt) Cantilevers For Chemical Sensing, Jui-Ching Hsu

LSU Master's Theses

With the discovery of carbon nanotubes (CNTs), many applications have been implemented based on their unique electronic, mechanical, chemical and optoelectronic properties. One area of applications is in gas sensors for detecting, oxygen, flammable and toxic gases. In our work, the focus is on the fabrication of carbon nanotube (CNT) cantilever sensors for integration with CMOS readout chip which offer increased sensitivity. The higher surface-to-bulk ratio enhances the property and performance of the gas sensor by nanocantilevers. In this work, we present the detection method based on the change in capacitance of the single walled carbon nanotube (SWCNT) cantilever. Carbon …

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Monolithic Integration Of High-Aspect-Ratio Microstructures With Cmos Circuitry, Tinghui Xin Jan 2007

Monolithic Integration Of High-Aspect-Ratio Microstructures With Cmos Circuitry, Tinghui Xin

LSU Doctoral Dissertations

This work involves developing processing techniques for monolithically integrating a high-aspect-ratio microstructures with CMOS circuitry. A microsystem comprising of a microprobe array and signal processing circuitry is utilized as a test vehicle to demonstrate this fabrication process. One potential application of this microsystem is for recording neural signals from the central nervous system. The main results include thick photoresist processing, DC and pulse electroplating to form high-aspect-ratio microprobes, microprobe sharpening and developing a post-IC monolithic integration process. SU-8 is utilized for thick photoresist application. This work focuses on realization of a deep microrecess array in thick resists rather than traditional …

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Intercarrier Interference Suppression For The Ofdm Systems In Time-Varying Multipath Fading Channels, Xiaozhou Huang Jan 2006

Intercarrier Interference Suppression For The Ofdm Systems In Time-Varying Multipath Fading Channels, Xiaozhou Huang

LSU Doctoral Dissertations

Due to its spectral efficiency and robustness over the multipath channels, orthogonal frequency division multiplexing (OFDM) has served as one of the major modulation schemes for the modern communication systems. In the future, the wireless OFDM systems are expected to operate at high carrier-frequencies, high speed and high throughput mobile reception, where the fasting time-varying fading channels are encountered. The channel variation destroys the orthogonality among the subcarriers and leads to the intercarrier interference (ICI). ICI poses a significant limitation to the wireless OFDM systems. The aim of this dissertation is to find an efficient method of providing reliable communication …

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Mimo-Ofdm Communication Systems: Channel Estimation And Wireless Location, Zhongshan Wu Jan 2006

Mimo-Ofdm Communication Systems: Channel Estimation And Wireless Location, Zhongshan Wu

LSU Doctoral Dissertations

In this new information age, high data rate and strong reliability features our wireless communication systems and is becoming the dominant factor for a successful deployment of commercial networks. MIMO-OFDM (multiple input multiple output-orthogonal frequency division multiplexing), a new wireless broadband technology, has gained great popularity for its capability of high rate transmission and its robustness against multi-path fading and other channel impairments. A major challenge to MIMO-OFDM systems is how to obtain the channel state information accurately and promptly for coherent detection of information symbols and channel synchronization. In the first part, this dissertation formulates the channel estimation problem …

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Optical Control Plane: Theory And Algorithms, Stefan Alexandru Pascu Jan 2006

Optical Control Plane: Theory And Algorithms, Stefan Alexandru Pascu

LSU Doctoral Dissertations

In this thesis we propose a novel way to achieve global network information dissemination in which some wavelengths are reserved exclusively for global control information exchange. We study the routing and wavelength assignment problem for the special communication pattern of non-blocking all-to-all broadcast in WDM optical networks. We provide efficient solutions to reduce the number of wavelengths needed for non-blocking all-to-all broadcast, in the absence of wavelength converters, for network information dissemination. We adopt an approach in which we consider all nodes to be tap-and-continue capable thus studying lighttrees rather than lightpaths. To the best of our knowledge, this thesis …

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Data-Driven Fault Detection Using Trending Analysis, Min Luo Jan 2006

Data-Driven Fault Detection Using Trending Analysis, Min Luo

LSU Doctoral Dissertations

The objective of this research is to develop data-driven fault detection methods which do not rely on mathematical models yet are capable of detecting process malfunctions. Instead of using mathematical models for comparing performances, the methods developed rely on extensive collection of data to establish classification schemes that detect faults in new data. The research develops two different trending approaches. One uses the normal data to define a one-class classifier. The second approach uses a data mining technique, e.g. support vector machine (SVM) to define multi class classifiers. Each classifier is trained on a set of example objects. The one-class …

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Exploring The Hot-Carrier Effect On The Wireless Transceivers, Sameer R. Herlekar Jan 2006

Exploring The Hot-Carrier Effect On The Wireless Transceivers, Sameer R. Herlekar

LSU Doctoral Dissertations

Phase noise can be regarded as the most severe cause of performance degradation in the wireless communication systems. The hot-carriers (HCs), found in the CMOS synchronization circuits, are the high-energy charge carriers that degrade the MOSFET devices’ performance by increasing the threshold voltage required to operate the MOSFETs. The HC effect manifests itself as the phase noise whose level increases with the continued MOSFET operation and such increases result in the performance degradation of the voltage-controlled oscillator (VCO) built on the MOSFETs. The HC effect is particularly evident in the short-channel MOSFET devices. In this dissertation, we analyze the wireless …

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A State-Space Approach To Blind Estimation Of Mimo Wireless Channels, Hesham Mahmoud Zarif Amin Badr Jan 2006

A State-Space Approach To Blind Estimation Of Mimo Wireless Channels, Hesham Mahmoud Zarif Amin Badr

LSU Doctoral Dissertations

This dissertation focuses on blind channel estimation in wireless communications such that the estimated channel admits the minimum phase property. It assumes only the second order statistics of the transmitted signal at the receive side. Our proposed approach is based on the generalized spectral factorization because of the deficient normal rank for the power spectral density (PSD) function of the received signal. We will show the relationship between the generalized spectral factorization and inner-outer factorizations where the inner is square with smaller size. The inner-outer factorization is in turn related to the generalized Kalman filtering in which the dimension of …

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Compiler Optimization Techniques For Scheduling And Reducing Overhead, Tong-Chai Wang Jan 2006

Compiler Optimization Techniques For Scheduling And Reducing Overhead, Tong-Chai Wang

LSU Doctoral Dissertations

Exploiting parallelism in loops in programs is an important factor in realizing the potential performance of processors today. This dissertation develops and evaluates several compiler optimizations aimed at improving the performance of loops on processors. An important feature of a class of scientific computing problems is the regularity exhibited by their access patterns. Chapter 2 presents an approach of optimizing the address generation of these problems that results in the following: (i) elimination of redundant arithmetic computation by recognizing and exploiting the presence of common sub-expressions across different iterations in stencil codes; and (ii) conversion of as many array references …

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Instantaneously Trained Neural Networks With Complex And Quaternion Inputs, Adityan V. Rishiyur Jan 2006

Instantaneously Trained Neural Networks With Complex And Quaternion Inputs, Adityan V. Rishiyur

LSU Master's Theses

Neural network architectures such as backpropagation networks, perceptrons or generalized Hopfield networks can handle complex inputs but they require a large amount of time and resources for the training process. This thesis investigates instantaneously trained feedforward neural networks that can handle complex and quaternion inputs. The performance of the basic algorithm has been analyzed and shown how it provides a plausible model of human perception and understanding of images. The motivation for studying quaternion inputs is their use in representing spatial rotations that find applications in computer graphics, robotics, global navigation, computer vision and the spatial orientation of instruments. The …

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Designing Switches For Routing In Circuit-Switched Trees, Dinesh Prasad Venkat Rao Jan 2006

Designing Switches For Routing In Circuit-Switched Trees, Dinesh Prasad Venkat Rao

LSU Master's Theses

Reconfigurable computing provides a fast and flexible solution for intensive computing processes. Thus, it acts as a bridge between software controlled and hardware based processors. The self–reconfigurable gate array (SRGA) is a reconfigurable architecture that allows fast switching between operations on a reconfigurable device. It consists of a 2-dimensional array of processing elements (PEs) connected using a binary tree structure, called a circuit-switched tree (CST). A CST is a balanced binary tree in which leaves represent processing elements (PE) and internal nodes represent switches. The PEs in the CST communicates with each other by configuring the appropriate switches in the …

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A Configurable Decoder For Pin-Limited Applications, Matthew Collin Jordan Jan 2006

A Configurable Decoder For Pin-Limited Applications, Matthew Collin Jordan

LSU Master's Theses

Pin limitation is the restriction imposed on an IC chip by the unavailability of a sufficient number of I/O pins. This impacts the design and performance of the chip, as the amount of information that can be passed through the boundary of the chip becomes limited. One area that would benefit from a reduction of the effect of pin limitation is reconfigurable architectures. In this work, we consider reconfigurable devices called Field Programmable Gate Arrays (FPGAs). Due to pin limitation, current FPGAs use a form of 1-hot decoder to select elements (one frame at a time) during partial reconfiguration. This …

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