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Articles 2851 - 2880 of 3180

Full-Text Articles in Engineering

An Analytical And Numerical Model For Design Of Non- Uniformly Powered Silicon Chips Based On Both Thermal And Device Clock Performance, Abhihit D. Kaisare Dec 2007

An Analytical And Numerical Model For Design Of Non- Uniformly Powered Silicon Chips Based On Both Thermal And Device Clock Performance, Abhihit D. Kaisare

Mechanical and Aerospace Engineering Dissertations - Archive

Silicon chips continue to grow in capabilities, complexity and performance. Silicon chips typically integrate functional components such as logic and level two (L2) cache memory in their architecture. This functional integration of logic and memory results in improved performance of the chip. However, the integration also introduces a layer of complexity in the thermal design and management of silicon chips. As a direct result of functional integration, the power map on a silicon chip is typically highly non-uniform and the assumption of a uniform heat flux across the chip surface has been shown to be invalid post Pentium II architecture. …

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Thermal Stresses Of Composite Beams With Rectangular And Tubular Cross-Sections, Chia-Wei Su Dec 2007

Thermal Stresses Of Composite Beams With Rectangular And Tubular Cross-Sections, Chia-Wei Su

Mechanical and Aerospace Engineering Theses - Archive

Closed-form analytical solutions for laminated composite beams with tubular and rectangular cross-sections are developed for evaluating the thermal induced stresses. The derivations are based on modified lamination theory and parallel axis theorem. The present approach includes variation of ply stiffness along the contour of the cross-section. The interlaminar shear stress of cantilever composite beam with rectangular cross-section under a transverse load is analytically proved to be independent of temperature change in uniform temperature environment. Three-dimensional finite element models for computing thermal stresses of both cross-sections are developed using commercial software package ANSYS 10. The results obtained from analytical solutions give …

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Surface Patterning Of Biodegradable Polymer In Tissue Engineering By Applying Photolithography, Lee-Chun Su Dec 2007

Surface Patterning Of Biodegradable Polymer In Tissue Engineering By Applying Photolithography, Lee-Chun Su

Material Science and Engineering Theses - Archive

The prevalence of cardiovascular disease and inherent problems with current surgical therapies has prompted major efforts in the field of vascular tissue engineering. While there have been significant advances towards creating functional blood vessel substitutes, the fabrication of a vascular graft with mechanical, structural and functional properties similar to native vessels has not yet been achieved. We have presented an observation of a new biodegradable polymer utilized on the research of tissue engineering. Our idea was to create a structure to imitate blood vessel muscles in vitro and also to guide the cells when they start spreading and trying to …

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Thermally Activated Sulfurization Scheme For Cuins2 Solar Cells, Karan Agrawal Dec 2007

Thermally Activated Sulfurization Scheme For Cuins2 Solar Cells, Karan Agrawal

Material Science and Engineering Theses - Archive

Chalcopyrite Solar Cells are now being fabricated on flexible (polymer) substrates. However, CuInS2 solar cells have not been fabricated on the polymer substrates on the commercial scale due the sulfurization temperature which limits the use of polymer substrates during fabrication. To overcome this problem a thermally activated sulfurization process for the manufacture of CuInS2 solar cells from the Cu-In bilayers is described in this work. This sulfurization process can be employed for lower temperature for the formation of the absorber layer. For the sulfurization, the Cu-In bilayer with different compositions is prepared by thermal evaporation in which the In-rich film …

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Ductile Lightweight Concrete For Lightweight Structural Application, Ake Piyamaikongdech Dec 2007

Ductile Lightweight Concrete For Lightweight Structural Application, Ake Piyamaikongdech

Civil Engineering Theses - Archive

This study developed a ductile concrete for precast wall systems which are capable of resisting high wind in excess of 500 mph. The developed concrete mix design consists of sand, cement, glass fiber, and a foaming agent to produce lightweight concrete in the range of 87 pcf (1392 kg/m3) to 90 pcf (1440 kg/m3). A comprehensive testing program for evaluation of the developed concrete material was undertaken. The mix designs were prepared both in the laboratory and in the mix truck with drum capacity of 27 ft3 (0.77 m3), and 177.6 ft3 (5 m3), respectively. The large concrete batches using …

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Localization In Noisy Environment Using Extended Kalman Filter, Aneeket Suresh Patkar Dec 2007

Localization In Noisy Environment Using Extended Kalman Filter, Aneeket Suresh Patkar

Electrical Engineering Theses - Archive

Localization is an important aspect of Wireless Sensor Networks. Information regarding the position of the sensor nodes is not always known. Without the position information of the sensors, the data reported by the sensors is of little use. Various approaches have been used to perform localization using some information about the sensor node. Potential field approach for localization, using distance information has been successfully tested with satisfactory results. However in case of noisy environment, the range measurements have greater inaccuracy. In such cases, localization using the above algorithm can provide some inaccuracy. To rectify such erroneous localization situations, Extended Kalman …

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Decoupling Of Hamiltonian System With Applications To Linear Quadratic Problem, Vishal Gupta Dec 2007

Decoupling Of Hamiltonian System With Applications To Linear Quadratic Problem, Vishal Gupta

Electrical Engineering Theses - Archive

This thesis provides a method of decoupling the Hamiltonian system with application to linear quadratic problem in control system. Resulting decoupled Hamiltonian system helps in formulating easy closed form solution to various optimal control problems. These closed form solution are improvement over the problem of solving first order nonlinear differential equations in conventional methods. Decoupling also eliminates the constraint, "Q = 0 " for certain type of optimal control.

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Multi-Objective Evaluation Of Dynamic Facility Layout Using Ant Colony Optimization, Gary Yu-Hsin Chen Dec 2007

Multi-Objective Evaluation Of Dynamic Facility Layout Using Ant Colony Optimization, Gary Yu-Hsin Chen

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

The Dynamic Facility Layout Problem (DFLP) deals with changes of facility layout throughout time. As an extension to Static Facility Layout Problem (SFLP), it has gathered increasing interests lately. Facility layouts are constantly modified over time either to meet customers' changing demands in product designs and functionalities or to keep pace with technological innovations. Manufacturers must stay flexible and agile and frequent facility layout changes are needed. Since there is often insufficient time and insufficient funding to build a new manufacturing plant, it is often necessary to rearrange the current plant layout. Even though the rearrangement of plant layout can …

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On The Study Of Multi-Channel Eeg: Lossless Compression, Signal Modeling And Classification, Yodchanan Wongsawat Dec 2007

On The Study Of Multi-Channel Eeg: Lossless Compression, Signal Modeling And Classification, Yodchanan Wongsawat

Electrical Engineering Dissertations - Archive

Recently, electroencephalogram (EEG) has become necessary for diagnosis, telemedicine, and brain computer interface (BCI). This thesis investigates three signal processing tools which can explore multi-channel structures of the EEG for different applications such as lossless compression, artifact removal, and classification. First, this thesis presents a method for approximating the Karhunen-Loeve transform (KLT) of multi-channel EEG signals. The proposed transform is further parameterized by lifting factorization by which the coefficients' dynamic range is controlled through a proposed pivoting scheme, rendering a reversible structure under quantization of coefficients called IntSKLT. A lossless coder for multi-channel EEG signals which exploits inter-channel correlation among …

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Integrated Mems Microsensors, Murali M. Chitteboyina Dec 2007

Integrated Mems Microsensors, Murali M. Chitteboyina

Electrical Engineering Dissertations - Archive

Many Micro-Electro-Mechanical Systems (MEMS) products have been commercialized at a fraction of the cost and size of conventional devices. Low cost, small sizes and multi-function are the ultimate objectives of commodity MEMS devices. An intelligent micro-system requires that the processing circuitry, sensors, and actuators be integrated on the same chip. Integrated MEMS can improve performance of the overall product in several applications. In this work integrated MEMS devices are investigated through semiconducting Yttrium Barium Copper Oxide (YBaCuO) microbolometer arrays on complementary metal oxide semiconductor (CMOS) substrates, a novel tunable infrared microspectrometer, and a novel device-level packaging technique for MEMS resonators. …

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Design And Functionality Analysis Of Operational Amplifiers With Rail-To-Rail Input And Output Capability, Mingsheng Peng Dec 2007

Design And Functionality Analysis Of Operational Amplifiers With Rail-To-Rail Input And Output Capability, Mingsheng Peng

Electrical Engineering Dissertations - Archive

The operational amplifier (op amp) is a fundamental building block in analog integrated circuit design. For low power-supply voltages, the common-mode input voltage and the output voltage of op amps are always required to be able to swing from the negative power-supply rail to the positive power-supply rail, i.e., rail-to-rail. In this dissertation, op amps with rail-to-rail input and output capability are investigated. This dissertation mainly focuses on the rail-to-rail input stage design. Two different rail-to-rail input stages with a single differential pair and a common-mode adapter are presented. The common-mode adapter is used to shift the common-mode input voltage. …

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A Potential Field Approach For Distributed Control Of Discrete Actuator And Sensor Arrays, Pritpal S. Dang Dec 2007

A Potential Field Approach For Distributed Control Of Discrete Actuator And Sensor Arrays, Pritpal S. Dang

Electrical Engineering Dissertations - Archive

This dissertation presents new methods of distributed sensing, classification and actuation using potential field and neural network approaches. Human look-a-like robot serves as an excellent tool to implement the strategies developed for sensing, classification and actuation. Achieving dexterity in human-machine interaction or human look-a-like robot helps in better understanding of dynamic and complex environment. This work deals with the issues related to gain autonomy and adaptability through distributed sensing, classification and actuation capabilities. The work presented here starts by mentioning novel strategies employed for morphing a flexible structure to achieve the desired expressions on the artificial skin and then moves …

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Sequences Of Bayes Gaussian Classifier, Jimy Shah Dec 2007

Sequences Of Bayes Gaussian Classifier, Jimy Shah

Electrical Engineering Theses - Archive

A new method for designing sequences of Bayes Gaussian Classifiers is presented in this thesis. First, a basic Bayes Gaussian Classifier is designed with an assumption of data being Gaussian. Then, we have used the Output Weight Optimization-Back Propagation (OWO-BP) technique to iteratively modify the coefficients of the classifier, resulting in less classification error. Through use of an iterative Gram-Schmidt procedure, to train linear functional link nets, input features are ordered from most useful to least useful. Another important development in this thesis is the generation of nested feature subsets. This ensures that the curve for error percentage versus the …

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Embedded System For Monitoring Human Activities Using 3-Axis Accelerometer, Himabindu Yamana Dec 2007

Embedded System For Monitoring Human Activities Using 3-Axis Accelerometer, Himabindu Yamana

Electrical Engineering Theses - Archive

The last decade has witnessed a surge of interest in new sensing and monitoring devices for health care. In several medical and non-medical applications it is necessary to measure the human activities. Detection and monitoring of human activities requires the use of external sensors around the body. The reported design provides a systematic approach for characterization of states. The design employs a 3-axis accelerometer, a microcontroller and RS232 based communication protocol for sensing the activities of a person and the output will be seen on a PC with a graphical user interface. Experiments were conducted on human test subjects and …

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The Effect Of Temperature On Fiber Composite Bridge Decks, Mahesh Gajula Nagabhushanam Dec 2007

The Effect Of Temperature On Fiber Composite Bridge Decks, Mahesh Gajula Nagabhushanam

Civil Engineering Theses - Archive

The use of Fiber composite honeycomb structure's as bridge decks gained importance, because of its low light weight and ease of installation. In this study, The Fiber composite bridge decks were subjected to thermal gradients. The Fiber composite bridge decks were fabricated in sizes of 2 feet x 8 feet x .5 feet and 4 feet x 8 feet x .5 feet specimens by Kansas structural composites Inc. The program consisted of 3 specimens of size 2 feet x 8 feet x .5 feet with ribs oriented along longitudinal direction, 3 specimens of size 2 feet x 8 feet x …

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Deep Mixing Technology For Mitigation Of Swell-Shrink Behavior Of Expansive Soils Of Moderate To Deep Active Depths, Raja Sekhar Madhyannapu Dec 2007

Deep Mixing Technology For Mitigation Of Swell-Shrink Behavior Of Expansive Soils Of Moderate To Deep Active Depths, Raja Sekhar Madhyannapu

Civil Engineering Dissertations - Archive

Expansive soils are well known for their cyclic shrink-swell behavior due to seasonal related moisture changes. These cyclic movements of expansive soils are due to physico-chemical changes at particle level that are dependent on mineralogical composition of these soils. The subsoil depths susceptible to moisture changes are known as active zones and based on previous studies vary from shallow to deep depths. Movements from these active depths reflect to the surface and cause considerable damages to overlying infrastructures. These damages are slow and time dependent as the in situ moisture fluctuations are slow and continue with time. Since the current …

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Cross-Layer Design For Wireless Ad Hoc Sensor Networks, Xinsheng Xia Dec 2007

Cross-Layer Design For Wireless Ad Hoc Sensor Networks, Xinsheng Xia

Electrical Engineering Dissertations - Archive

Cross-layer design is an efficient approach to enhance energy efficiency and Quality of Service (QoS) in wireless ad hoc sensor networks. This dissertation will focus on the cross-layer issues and approaches. It will also discuss the latency-aware and energy efficiency tadeoffs and the packets transmission in the rear part of the dissertation. Firstly, we will analyze the cross-layer design for wireless sensor networks based on the virtual MIMO techniques. We will coordinate the physical layer, the MAC layer and the network layer for cross-layer evaluation. Performance analysis and simulation results show that throughput and packet loss ratio will have different …

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Measurement And Modeling Of 1/F Noise In Mosfet Devices With High-Κ Material As The Gate Dielectric, Tanvir Hasan Morshed Dec 2007

Measurement And Modeling Of 1/F Noise In Mosfet Devices With High-Κ Material As The Gate Dielectric, Tanvir Hasan Morshed

Electrical Engineering Dissertations - Archive

A new 1/f noise model has been developed for MOSFET devices with high-? gate stack. To investigate the impacts of nitridation, MOSFETs with nitrided high-? dielectric was used. These devices were provided by Texas Instruments, having four different interfacial layer thicknesses with a stack composition of SiON/HfSiON. The dominant mechanism affecting the noise behavior of these devices was experimentally determined to be correlated number and mobility fluctuation. The impact of remote phonon scattering was investigated in the temperature range of 172K to 300K. It has been observed that the mobility characteristics of these devices were significantly affected by remote phonon …

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Diffusion-Free Back Contact Solar Cells On S-Passivated Si(100) Substrates, Guanghua Song Dec 2007

Diffusion-Free Back Contact Solar Cells On S-Passivated Si(100) Substrates, Guanghua Song

Material Science and Engineering Dissertations - Archive

A diffusion-free back contact solar cell is proposed in this work. The textured front-side of this cell is coated with ~100 nm thermal SiO2 to enhance the light trapping meanwhile reduce the surface recombination velocity (SRV). The back-side of this cell is finger-patterned, using a diffusion-free junction as its emitter region and Al-Si alloy as its base contact. The diffusion-free junction is made by a Schottky contact between low work-function metal aluminum (Al) and sulfur (S)-passivated p-type Si(100) surface. Solution-based S passivation is one of the experimental realizations of the "valence-mending concept". Previously developed MBE (molecular bean epitaxy) selenium (Se) …

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Localization Of Biliary Tree Structures By Use Of Photon Diffusion Models, Dharmendra Nadkar Dec 2007

Localization Of Biliary Tree Structures By Use Of Photon Diffusion Models, Dharmendra Nadkar

Bioengineering Theses - Archive

A novel computational methodology is proposed for the intraoperative localization of biliary tree structures by means of spectrally resolved near-infrared reflectance measurements. As these structures are embedded in fatty tissue, they cannot be visualized directly, which results in inadvertent injuries during a cholecystectomy operation. Localizing the biliary tree intraoperatively is therefore an important clinical problem. Successful clinical implementation of an imaging system which could attain this goal would reduce surgical time, improve patient safety, and minimize the risk of complications and expenses attributable to the current standard practice of intraoperative cholangiography. It is hoped that the work presented here will …

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Formulation Of Lean Six Sigma Critical Business Processes For Manufacturing Facilitites, Chaucey Chandler Dec 2007

Formulation Of Lean Six Sigma Critical Business Processes For Manufacturing Facilitites, Chaucey Chandler

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

The author desired to create a method organizing the concepts from Lean, Six Sigma, critical business processes, and simplifying the usage of these concepts to identify Lean Six Sigma Critical Business Processes. Inspired by Laura Meade (1997) and the author's passion concerning process improvements, this research was created. Lean activities eliminate waste, Six Sigma activities eliminate variation, critical business processes focus on those areas that need improvement and are critical to the process, and Analytical Network Process (ANP) models problems considering the interactions between levels. There is value for all companies to implement at least one of these tools. Since …

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Context-Aware Inference System To Capture Design Rationale From Legacy Mcad, Ganeshram Ramji Iyer Nov 2007

Context-Aware Inference System To Capture Design Rationale From Legacy Mcad, Ganeshram Ramji Iyer

Mechanical and Aerospace Engineering Dissertations - Archive

There exist numerous design rationale systems that convert captured information into structured design rationale while providing rationale representation and retrieval. These systems woefully neglect the design rationale that is present in legacy CAD such as 2D drawings and 3D models. The dissertation addresses the issues that arise when dealing with the capture, representation and retrieval of design rationale from the 2D legacy CAD data, specifically the non-form related data (e.g. text and symbols). A definition for design rationale in the CAD domain is presented which forms the basis of the proposed approach. The approach uses a unique context-aware inference system …

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Characterization Of Rf Propagation In Metal Pipes For Passive Rfid Systems, Darmindra Danaraj Arumugam Nov 2007

Characterization Of Rf Propagation In Metal Pipes For Passive Rfid Systems, Darmindra Danaraj Arumugam

Electrical Engineering Theses - Archive

In this paper we collect and extend the theory of radio frequency (RF) propagation as it relates to propagation within metal cylinders, or circular pipes. This work is motivated by a need to understand the operation of UHF radio frequency identification (RFID) systems when the tags are placed within the pipes. These circular pipes are shown to be similar to metal tube waveguides which are either hollow or filled with air. We derive the Bessel function that is used to identify the propagation constants, the different transverse electric and transverse magnetic modes, cut-off frequencies and the multi-mode attenuation. The cut-off …

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Investigation Of Power System Blackouts And Reliability Improvement For Power Distribution Systems, Hui Zheng Nov 2007

Investigation Of Power System Blackouts And Reliability Improvement For Power Distribution Systems, Hui Zheng

Electrical Engineering Dissertations - Archive

Modern power systems often consist of thousands of equipments, each of which may have an affect on the security of the system. The trend toward deregulation has forced utilities to operate their systems closer to security boundaries [1]. This has fueled the need of faster and more accurate methods of reliability and security assessment. Power system reliability is defined as the probability that the power system will perform the function of delivering electric power to customers adequately on a continuous basis and with an acceptable quality [2]. Power system security assessment deals with the system’s ability to continue to provide …

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Wireless Devices For Medical Applications, Thermpon Ativanichayaphong Nov 2007

Wireless Devices For Medical Applications, Thermpon Ativanichayaphong

Electrical Engineering Dissertations - Archive

The deployment of medical electronics in healthcare plays a significant role to overcome many problems in disease treatment and diagnosis. For advanced applications, wireless solutions are preferred. The wireless technologies offer a new dimension of therapy or diagnosis, when wires are often bulky, unsafe, uncomfortable or even impossible to be deployed in some circumstances. The wireless communication devices can be categorized into two groups, active and passive, depending on the power sources operating electronics. The active devices draw powers from a battery, while the others harvest powers from external or internal sources. In this work, two medical applications are studied …

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Comparison Of Distributed Versus Lumped Hydrologic Simulation Models Using Stationary And Moving Storm Events Applied To Small Synthetic Rectangular Basins And An Actual Watershed Basin, Michael Jay Shultz Nov 2007

Comparison Of Distributed Versus Lumped Hydrologic Simulation Models Using Stationary And Moving Storm Events Applied To Small Synthetic Rectangular Basins And An Actual Watershed Basin, Michael Jay Shultz

Civil Engineering Dissertations - Archive

The purpose of this investigation is to compare simulations using several artificial rectangular basins and a real drainage basin for distributed and lumped hydrologic models via results obtained with the U.S. Geological Survey Modular Modeling System (MMS). Impervious watershed conditions were assumed for each simulation. A critical objective of this investigation is to assess the performance of a physically-simple lumped model compared to a more physically-complex distributed model for various storm events. Knowledge gained from this investigation may be applied to the practical problem of determining when either a distributed or lumped model may be expected to function well given …

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High Grade Control Of Linear Induction Motor Drives, Haidong Yu Nov 2007

High Grade Control Of Linear Induction Motor Drives, Haidong Yu

Electrical Engineering Dissertations - Archive

Linear induction machines (LIM) have been widely utilized in military, transportation, aerospace due to the impressive advantages such as simple configuration, easy maintenance and high acceleration/deceleration. However, the existence of trailing eddy current effect and magnetic asymmetry effect undermines the expected functionality of vector control even though LIM inherent similarities from its rotary counterpart. As a result, it has been a focal research area to either improve the performance of vector control for LIM or develop a new high grade control strategy. Therefore, the in-depth knowledge of electromagnetic behavior of LIM is necessary. From both finite element analysis (FEA) and …

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Regression Model For Prioritization Of Corridors When Retiming Traffic Signals, Manjari G. Mittal Nov 2007

Regression Model For Prioritization Of Corridors When Retiming Traffic Signals, Manjari G. Mittal

Civil Engineering Theses - Archive

Traffic signals are used by transportation engineers to safely and efficiently manage vehicle, bicycle and pedestrian traffic on roadways. However, to maintain the effectiveness of traffic signals, traffic signals should be adjusted or retimed periodically to match the current traffic patterns. Traffic signal retiming is one of the most cost effective ways available to transportation engineers for reducing delays and mitigating congestion. A region may contain a large number of traffic signals all of which cannot be retimed at once due to limited availability of funds and other resources; only a subset of signals can be retimed at any given …

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Time-Varying Feedback Systems Design Via Diophantine Equation Order Reduction, Shr-Hua Wu Oct 2007

Time-Varying Feedback Systems Design Via Diophantine Equation Order Reduction, Shr-Hua Wu

Electrical Engineering Dissertations - Archive

Diophantine equation plays an important role in the design and synthesis of feedback compensators. Many methods have been developed to solve the Diophantine equation. This dissertation develops a new systematic approach of solving a linear time-varying Diophantine equation. This approach is based upon successively reducing the order of the Diophantine equation by Euclidean algorithm. Euclidean algorithm for solving for both time-invariant and time-varying Diophantine equations for directly determining both the quotient and the remainder associated with the division of one polynomial by another is presented. The coprimeness (right or left) of two Polynomial Differential Operators is needed to guarantee, in …

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Medium Access Control(Mac) Layer Design And Data Query Processing For Wireless Sensor Networks, Qingchun Ren Sep 2007

Medium Access Control(Mac) Layer Design And Data Query Processing For Wireless Sensor Networks, Qingchun Ren

Electrical Engineering Dissertations - Archive

In this dissertation, there are four main aspects included: energy reservation on MAC layer, secure improvement for DoS attacks on MAC layer, query processing with uncertainty for sensor database systems, and throughput maximization on MAC layer for ultra wideband communication systems. In energy reservation, we proposed asynchronous MAC (A-MAC) protocol and asynchronous schedule-based MAC (ASMAC) protocol. A-MAC and ASMAC protocols are attractive due to their suitabilities for multihop networks and capabilities of removing accumulative clock-drifts without any network synchronization. Moreover, we build a traffic-strength- and network-density-based model to adjust essential algorithm parameters adaptively. In secure problem, we proposed a secure …

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