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Articles 2011 - 2040 of 3180

Full-Text Articles in Engineering

Comparative Analysis Of Widely Used Air Containment Systems In Commercial Data Centers For Maximum Cooling Performance, Kasturi Rangan Rajagopalan Jan 2013

Comparative Analysis Of Widely Used Air Containment Systems In Commercial Data Centers For Maximum Cooling Performance, Kasturi Rangan Rajagopalan

Mechanical and Aerospace Engineering Theses - Archive

Many data centers implement containment systems to improve cooling system performance. Literature review shows that Hot Aisle Containment System (HACS) have higher supply air temperature set point than Cold Aisle Containment Systems (CACS) [1]. CACS in data centers have claims to support higher density loads when compared to HACS systems [2]. Data center owners suggest that containment of a group of racks can be a very effective technique to improve cooling performance. On the other hand, others suggest that fewer area for containment is better than no containment in data centers that favours the partially contained architectures of HACS and …

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Real Time Temperature Prediction In A Data Center Environment Using An Adaptive Algorithm, Vishok Amar Kumar Jan 2013

Real Time Temperature Prediction In A Data Center Environment Using An Adaptive Algorithm, Vishok Amar Kumar

Mechanical and Aerospace Engineering Theses - Archive

Most organizations around the world rely on information systems to run their operations. Data centers are hence a crucial aspect of most organizational operations to ensure business continuity. Disruption in the working of a system can impair the business largely and hence optimizing the environment in which the servers and storage devises of a data center are housed becomes extremely challenging. Most industries design the data center infrastructure to handle peak load conditions thus ensuring a continual functionality of its hosted environment. However, the cost of maintaining such a system is very high. This gives rise to the need of …

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A Computational Model To Characterize Different Flow Regimes For Microscale Re-Entry Satellites, Sudharsan Thiruvenkadam Jan 2013

A Computational Model To Characterize Different Flow Regimes For Microscale Re-Entry Satellites, Sudharsan Thiruvenkadam

Mechanical and Aerospace Engineering Theses - Archive

Atmospheric re-entry vehicles experience different flow regimes during flight due to the change in atmospheric density along the re-entry trajectory. This change in density creates non-equilibrium regions on the order of mean free path, called Knudsen layer. In the design of atmospheric re-entry vehicles, the flux variations near the wall of the re-entry vehicles are of critical importance. Traditional CFD simulations that use Navier-Stokes equations fail to predict the flow in the Knudsen layer. The Direct Simulation Monte Carlo (DSMC) method is accurate for all flow regimes, and correctly models the Knudsen layer but is computationally expensive. The computational cost …

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Fabrication And Characterization Of Single Electron Device And Study Of Energy Filtering In Single Electron Transport, Liang-Chieh Ma Jan 2013

Fabrication And Characterization Of Single Electron Device And Study Of Energy Filtering In Single Electron Transport, Liang-Chieh Ma

Material Science and Engineering Dissertations - Archive

Single electron devices, in which transport of single electrons is precisely controlled, hold a great promise as important components of future electronic devices and sensors. However, technical challenges have prevented their implementations to practical electronic and sensing systems. First of all, the fabrication of single electron devices requires their components to be defined and arranged in nanoscale precision, a great challenge for a large-scale fabrication. Secondly, for room temperature operation, the single-electron charging energy should be much larger than the room-temperature thermal energy, ~25 meV, requiring use of extremely small Coulomb island, which is difficult to control. This has limited …

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Corrosion And Hydrogen Embrittlement Of Nanocrystalline Nickel, Tapas Desai Jan 2013

Corrosion And Hydrogen Embrittlement Of Nanocrystalline Nickel, Tapas Desai

Material Science and Engineering Theses - Archive

Nanocrystalline (nc) materials have attracted the interest of the scientific community because of their unique physical and mechanical properties. However, limited research has been performed to analyze their electrochemical behavior. The majority of research in the field of electrochemical and corrosion behavior exists for electrodeposited nanocrystalline metals.This research studies the behavior of sputter-deposited nc Nickel films in corrosive and hydrogen environment by potentiodynamic polarization and microindentation. The surface morphology and composition of the samples was examined by Scanning Electron Microscopy and Energy Dispersive X-Ray spectroscopy. Bulk Ni samples exhibit mild passivation in 3.5 % NaCl solution. The surface reveals a …

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Improving Productivity Of Tunnel Boring Machines, Nicholas Jencopale Jan 2013

Improving Productivity Of Tunnel Boring Machines, Nicholas Jencopale

Civil Engineering Theses - Archive

Tunneling with tunnel boring machines (TBMs) is one of the most mechanized and sophisticated processes within the construction industry. However, there are risks when venturing down several hundred feet where the conditions cannot be accurately determined in advance. Months and years of planning, engineering, profiling, researching, and scheduling go into a typical tunneling project before any ground breaking event. This thesis will discuss in detail the growing technologies of the tunneling process using tunnel boring machines (TBM). First, some background information on tunneling and the use of a TBM will be provided to introduce the process and the industry being …

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Corrosion Potentials Of Lightweight Concrete Wrapped With Fiber Reinforced Polymers (Frp), Eric Goucher Jan 2013

Corrosion Potentials Of Lightweight Concrete Wrapped With Fiber Reinforced Polymers (Frp), Eric Goucher

Civil Engineering Theses - Archive

The purpose of this research was to investigate the effects of Fiber Reinforced Polymer wraps on corrosion protection of lightweight concrete. Many studies have been undertaken for normal density concrete, but there are very few studies regarding lightweight concrete and externally bonded FRP wraps. This experiment involved the use of an accelerated corrosion test to determine the corrosion protection that FRP would afford lightweight concrete, while making a comparison with a similarly proportioned normalweight mix. 42 cylinders were subject to a constant 12 V power from a DC Power Supply while being immersed in a 5% NaCl for a period …

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Structural And Material Performance Of Rubberized And Hybrid Concrete Pipes, Mohammad Mohammadagha Jan 2013

Structural And Material Performance Of Rubberized And Hybrid Concrete Pipes, Mohammad Mohammadagha

Civil Engineering Theses - Archive

This study investigates how the combination of steel fiber, crumb rubber, synthetic fiber, and conventional steel cage will improve the ductility of regular concrete pipes and thin-walled semi-rigid concrete pipes. In this study, pipes with four different concrete mixtures were produced and tested: (1) Steel Bar Reinforced Concrete Pipe (SBRCP), (2) Crumb Rubber Reinforced Concrete Pipe (CRRCP), (3) Steel Fiber Reinforced Concrete Pipe (SFRCP), and (4) Synthetic Fiber Reinforced Concrete Pipe (SNFRCP). This study investigates how the variation of the fiber volume fraction and crumb rubber content in concrete mix affects the behavior of pipes with diameters ranging from 24in. …

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Ensemble Streamflow Forecasting For The Upper Trinity River Basin In Texas, Manabendra Saharia Jan 2013

Ensemble Streamflow Forecasting For The Upper Trinity River Basin In Texas, Manabendra Saharia

Civil Engineering Theses - Archive

By allowing for routine use of longer-lead quantitative precipitation forecast (QPF) in hydrologic prediction, ensemble forecasting offers hope for extending the lead time for short-range streamflow forecasting. In this work, this potential is assessed by comparatively evaluating ensemble streamflow hindcasts forced by Day 1-3 QPF with those forced by Day 1 QPF for five headwater basins in the Upper Trinity River Basin in North Texas. The hindcasts are generated for a 7-year period of 2004 to 2010 using the Hydrologic Ensemble Forecast Service (HEFS), which operates on the Community Hydrologic Prediction System (CHPS) of the National Weather Service (NWS). HEFS …

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The Relation Between Freeway Average Speed And Speed Noise, Bahar Zarin Jan 2013

The Relation Between Freeway Average Speed And Speed Noise, Bahar Zarin

Civil Engineering Theses - Archive

A significant amount of energy could be saved by applying traffic management policies. Many factors affect the fuel consumption rate, and the most important traffic-related ones include variables such as speed, number of stops, the speed noise, and the acceleration noise. Fuel consumption models for both urban and highway traffic are used to evaluate the effect of these factors. Previous literature shows the speed and the acceleration of the individual vehicles as well as the aero-dynamic effects are the most considered parameters in highway fuel consumption models. However, the existing models are based on the average or cruising speed and …

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Nanomaterials For Photo-Based Diagnostic And Therapeutic Applications, Baohong Yuan, Jyothi Unnikrishna Menon, Khanh Vu, Parth V. Jadeja, Kytai Truong Nguyen, Pranjali P. Tambe Jan 2013

Nanomaterials For Photo-Based Diagnostic And Therapeutic Applications, Baohong Yuan, Jyothi Unnikrishna Menon, Khanh Vu, Parth V. Jadeja, Kytai Truong Nguyen, Pranjali P. Tambe

Bioengineering Faculty Publications - Archive

Photo-based diagnosis and treatment methods are gaining prominence due to increased spatial imaging resolution, minimally invasive modalities involved as well as localized treatment. Recently, nanoparticles (NPs) have been developed and used in photo-based therapeutic applications. While some nanomaterials have inherent photo-based imaging capabilities, others including polymeric NPs act as nanocarriers to deliver various fluorescent dyes or photosensitizers for photoimaging and therapeutic applications. These applications can vary from Magnetic Resonance Imaging (MRI) and optical imaging to photothermal therapy (PTT) and chemotherapy. Materials commonly used for development of photo-based NPs ranges from metal-based (gold, silver and silica) to polymer- based (chitosan, dextran, …

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A Cmos Conductometric Circuit For Chemical Sensing Using Nanowire Sensor Arrays, Sujith S. Dermal Jan 2013

A Cmos Conductometric Circuit For Chemical Sensing Using Nanowire Sensor Arrays, Sujith S. Dermal

Electrical Engineering Theses - Archive

In this thesis, a readout circuit for conductometric electrochemical sensor array is designed and implemented. It is designed to work with the output range of a Carbon Nanotube Chemiresistive Sensor Array. The sensor arrays are designed to measure the Volatile Organic Compounds (VOCs) in the environment. The circuit reads out the outputs of the sixteen conductometric sensor arrays and calculates the change in conductance during the interaction with the chemicals present in the environment. A constant voltage is applied to the sensor arrays and when the sensor detects the VOCs, it changes the conductance and a change in current through …

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Distributed Data Dimensionality Reduction And Denoising, Abiodun T. Aduroja Jan 2013

Distributed Data Dimensionality Reduction And Denoising, Abiodun T. Aduroja

Electrical Engineering Theses - Archive

With the recent upsurge in the amount of data transmission and use, giving rise to the era of big data, research has put a lot of emphasis on designing efficient methods to extract useful information by reducing the size of a large set of data to a much smaller set. This is the main idea in data dimensionality reduction which is a critical step in applications that involve a constantly increasing data size, and limited computational and communication resources. Such a situation appears in sensor networks where there is a large number of sensors acquiring data. However, the informative part …

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Eutectic Diffusion Brazing Process For Joining Aluminum Laminae With Macro- And Micro- Scale Features, Paul Wilson Jan 2013

Eutectic Diffusion Brazing Process For Joining Aluminum Laminae With Macro- And Micro- Scale Features, Paul Wilson

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

Eutectic brazing occurs when two metals, such as aluminum and copper, react and diffuse together at a temperature lower than either material would melt separately. Commonly used in electronics manufacturing, this brazing method provides the basis for a new process of joining a laminated device with micro fluidic features. The proposed process overcomes the challenges of aluminum oxidation resulting from traditional diffusion bonding of aluminum laminae and does not require flux or caustic material pre-treatments. The process also protects surface geometries and avoids warpage, which is common with other higher-temperature joining processes such as welding. This research provides a foundation …

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Outcome And State Transition Modeling For Adaptive Interdisciplinary Pain Management, Aera Kim Leboulluec Jan 2013

Outcome And State Transition Modeling For Adaptive Interdisciplinary Pain Management, Aera Kim Leboulluec

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

Pain management is a major global health problem. The World Health Organization estimates that, globally, 1 in 5 adults suffer from chronic pain and in the United States alone, chronic pain affects nearly 100 million adults resulting in an estimated annual cost of $560 to $635 billion. The University of Texas at Arlington and the Eugene McDermott Center for Pain Management at the University of Texas Southwestern Medical Center at Dallas (The Center) are collaborating to seek adaptive treatment strategies for interdisciplinary pain management in a two-stage program. Interdisciplinary pain management combines multiple disciplines of professionals to understand the biological …

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Development Of Optimal Decision Model For Multi-System Process Capability Improvements Through A Personnel Environment And Integration (Pei) Framework Utilizing Radio Frequency Identification (Rfid) Technology, Maurice Dwayne Cavitt Jan 2013

Development Of Optimal Decision Model For Multi-System Process Capability Improvements Through A Personnel Environment And Integration (Pei) Framework Utilizing Radio Frequency Identification (Rfid) Technology, Maurice Dwayne Cavitt

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

This research describes a framework that minimizes uncertainty and risk in lead time and excessive costs associated with multi-automating systems in very complex and dynamic environments. Further, by seeking to reduce risk by increasing the reliability component of the system, crucial inventories levels are maintained and leveraged in complex an environment that provides additional organization cost savings and enhanced flexibility by enhancing their ability to optimize inventories. Inventory control is crucial for any supply chain as it drives the costs which influence business decision models. The reliability of the systems that maintain the important inventories in complex operations is crucial …

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Multistep Second Order Training For The Multilayer Perceptron, Melvin Deloyd Robinson Jan 2013

Multistep Second Order Training For The Multilayer Perceptron, Melvin Deloyd Robinson

Electrical Engineering Dissertations - Archive

Training a feedforward multilayer perceptron (MLP) requires obtaining train- ing data and solving a non-convex optimization problem to calculate the network's weights. Various problems can arise during training that ultimately can limit a MLP's usefulness such as slow convergence and high computational complexity. Additionally, when training one needs to have confidence that the chosen algorithm is working optimally for the chosen coordinate system.We introduce novel second order training algorithms to overcome these difficulties. In the process, a piecewise affine model of the multilayer perceptron is introduced which shows that objective functions for training are poorly modeled by quadratic functions of …

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A Study Of The Characteristics And Limitations Of Various Platings On Cylindrical Electrical Conductors, Robert C. Scully Jan 2013

A Study Of The Characteristics And Limitations Of Various Platings On Cylindrical Electrical Conductors, Robert C. Scully

Electrical Engineering Dissertations - Archive

This work explores the impedance characteristics of copper wires plated with tin, silver, or nickel, the most common type of wiring used in the computer, communications, and aerospace industries. The background of plated wires and a brief review of related research is provided. This is followed by a detailed development of the theory of plated wires, accompanied by a MAPLE code in the appendix that can be used for the numerical analysis of plated wires having two or more plating layers. The code was used to generate a series of curves predicting the impedance behavior of both solid, "pure" metals, …

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Capacity Fading Induced On Electrochemical Energy Storage Cells As A Result Of High C Discharge, Biju Shrestha Jan 2013

Capacity Fading Induced On Electrochemical Energy Storage Cells As A Result Of High C Discharge, Biju Shrestha

Electrical Engineering Dissertations - Archive

A number of electrochemical energy storage devices have been developed and used widely to power portable electronic systems. Lithium-ion batteries are extremely popular for use in portable devices as a result of their high energy density, which is higher than almost all other similar technologies available. Despite their high energy density, most commercial off-the-shelf (COTS) cells are only modestly power dense, limiting them from being used to drive high power or pulsed power applications. Recently, improvements in the electrode structures and electrolytes have led to the development of lithium-ion batteries which have a higher combined power and energy density than …

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Optimizing The Use Of Systems Engineering On Proposals, Clement Douglas Smartt Jan 2013

Optimizing The Use Of Systems Engineering On Proposals, Clement Douglas Smartt

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

Organizations whose primary business is executing contracts must be able to capture contracts to survive. When the contracts involve engineering complex systems, systems engineering often plays a significant role in the proposal process, sometimes leading the technical effort. This research seeks to find an optimal use of systems engineering in proposal management to maximize the probability that a supplier organization will be awarded contracts. A number of systems engineering related factors that can potentially be used to predict contract awards are identified that pertain to the organization, the skill levels of employees, the competitive environment, the proposal project, the contract, …

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Elevated Recharge Of Electrochemical Cells, Peter Novak Jan 2013

Elevated Recharge Of Electrochemical Cells, Peter Novak

Electrical Engineering Dissertations - Archive

Electrochemical cells are energy dense storage devices used to power everything from small portable electronics such as cell phones, to larger systems including electric and hybrid-electric vehicles or even electric utility backup supplies. In recent years, the electrochemical community has analyzed many aspects of cell performance with papers covering the influence of temperature, humidity, pressure, and various other factors on the aging of different types of cells. Despite the abundance of information on various issues, very little work has been presented in the area of high rate elevated charge and even less work regarding high rate pulsed elevated charge. This …

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Internal Structure And Dynamic Decisions For Coalitions On Graphs, Muhammad Aurangzeb Jan 2013

Internal Structure And Dynamic Decisions For Coalitions On Graphs, Muhammad Aurangzeb

Electrical Engineering Dissertations - Archive

The notions of collaboration, advantage, cost and impact are investigated in this dissertation, following are the details. Contribution to Cooperation between Agents for Routing in an Unknown Graph Using Reinforcement LearningFirst of all this work investigates the cooperation between agents to achieve a common goal. The problem of steering a swarm of autonomous agents out of an unknown maze to some goal located at an unknown location is discussed in this context. The routing algorithm given here provides a mechanism for storing data based on the experiences of previous agents visiting a node that results in routing decisions that improve …

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Wireless Power Transmission Based On Retro-Reflective Antenna Array, Shaoshu Sha Jan 2013

Wireless Power Transmission Based On Retro-Reflective Antenna Array, Shaoshu Sha

Electrical Engineering Dissertations - Archive

In recent years, there is a lot of research on wireless power transmission (WPT) for various applications, such as mobile devices, electric vehicles, implanted medical devices, sensors, RFID, etc. Compared to wired power transmission, WPT is more convenient and allows the devices to move more freely. Microwave beamforming WPT has been investigated extensively because its fast tracking capability, multiple target tracking capability and so on. A retro-reflective antenna array based on novel phase-conjugate method is proposed in this dissertation. The phase of the received signal is detected individually and simultaneously at each antenna and the conjugated phase is applied to …

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Rfid And Rtls Enhancement For Retained Surgical Instrument In The Body, Ida Lumintu Jan 2013

Rfid And Rtls Enhancement For Retained Surgical Instrument In The Body, Ida Lumintu

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

Retained surgical items (e.g., sponges, needles, and instruments) are classified as preventable medical errors that cost the United States about $17 to $29 billion each year and the most frequently reported sentinel events in 2011 as reported by the Joint Commission. This research proposes a new approach to decrease such preventable medical errors by developing a Radio Frequency Identification-based Real Time Locating System (RTLS) for surgical operations (RfSurg). Patient safety concern, e.g. the excessive exposure of x-ray to the patient after the surgery, is a major motivation behind the need of RTLS in this research. The use of RTLS techniques …

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Multiport Dc Energy Conversion Systems, Hamid Behjati Jan 2013

Multiport Dc Energy Conversion Systems, Hamid Behjati

Electrical Engineering Dissertations - Archive

Sustainable energy sources and power electronic systems for utilizing such energy sources are becoming indispensible components of the modern power grid. The ability of multiport converters to mitigate the intermittency issues associated with these energy sources have made them attractive candidates for renewable energy conversion systems. Two single-stage multiport dc-dc converters, with independent and series outputs, are proposed in this dissertation. The advantages and applications of the proposed topologies are discussed. The ability of the proposed converters to regulate the input powers, coming from different energy sources, in addition to regulating the output voltages stands out. Specific switching schemes are …

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Investigation Of Degradation In Advanced Analog Mos Technologies, Md. Iqbal Mahmud Jan 2013

Investigation Of Degradation In Advanced Analog Mos Technologies, Md. Iqbal Mahmud

Electrical Engineering Dissertations - Archive

The focus of this work is to study the noise and degradation in advanced high and low voltage analog Metal Oxide Semiconductor Field Effect Transistors (MOSFET). Medium and high voltage transistors, especially lateral double diffused MOS (LDMOS) FETs have numerous practical applications. Although the LDMOS concept dates back some years, importance of low-frequency noise (also known as 1/f noise) characteristics of these devices have attracted attention only recently, due to some major reliability concerns. As an example, 1/f noise can cause a severe impact in System-on-Chip (SOC) applications when the LDMOS transistor is coupled with other devices or circuits through …

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Design And Fabrication Of Guided-Mode Resonant Tunable Optical Filters, Mohammad Jalal Uddin Jan 2013

Design And Fabrication Of Guided-Mode Resonant Tunable Optical Filters, Mohammad Jalal Uddin

Electrical Engineering Dissertations - Archive

Tunable optical filters have many applications in optical communication, multispectral and hyper-spectral imaging, bio-sensing, and display application. In optical communication, tunable optical filters (TOF) are used extensively in different wavelength division multiplexed (WDM) related applications. In display applications TOFs have been being used as color filters (CF) to separate primary colors from incident white light. In this study, two types of TOFs have been designed and fabricated: 1) thermo-optic tunable optical filters (TOTOF) working in optical communication bands and 2) tunable color filters (TCF) working in visible wavelength range.TOTOFs with deep (120 nm grating depth) and shallow (20 nm grating …

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Nanogap Break Junctions And Solid-State Micropores As Electronic Biosensors, Azhar Ilyas Jan 2013

Nanogap Break Junctions And Solid-State Micropores As Electronic Biosensors, Azhar Ilyas

Electrical Engineering Dissertations - Archive

Cancer has been the top ranked fatal disease for the last several decades. Most of the cancers remain silent at its earlier stage and are usually diagnosed at advanced and incurable phase. Early detection of cancer can have immediate and far reaching impact on better prognosis of cancer patients. Diseases are initially expressed at molecular and cellular scale and identification of these deadly diseases at such small scales would be a great step toward early detection. The study of biological molecules and diseased cells require efficient fabrication techniques to develop sensing devices with molecular size entrapment. Bio-nanotechnology and BioMEMs promise …

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Compressive Sensing For Wireless And Sensor Systems, Ji Wu Jan 2013

Compressive Sensing For Wireless And Sensor Systems, Ji Wu

Electrical Engineering Dissertations - Archive

Compressive sensing (CS) is an emerging field based on the revelation that a small collection of linear projections of a sparse signal contains enough information for stable, sub-Nyquist signal acquisition. It provides a potential way to acquire the sparse data efficiently, or equivalently, highly accurate recovery of sparse data from undersampled measurements. Huffman coding and compressive sensing are adopted to compress real-world wind tunnel data. Both uniform and non-uniform Huffman coding are evaluated in terms of the number of quantization levels, mean square error, codeword length and compression ratio. The main drawback of Huffman coding is that it requires calculating …

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Cooperative Control Of Multi-Agent Systems; Stability, Optimality And Robustness, Kristian Hengster Movric Jan 2013

Cooperative Control Of Multi-Agent Systems; Stability, Optimality And Robustness, Kristian Hengster Movric

Electrical Engineering Dissertations - Archive

In this work design methods are given for distributed synchronization control of multi-agent systems on directed communication graphs. Conditions are derived based on the relation of the graph eigenvalues to a region in a complex plane that depends on the single-agent system and the solution of the local Riccati equation. The synchronizing region concept is used. Cooperative observer design, guaranteeing convergence of the local estimates to their true values, is also proposed. The notion of convergence region for distributed observers is introduced. A duality principle is shown to hold for distributed observers and controllers on balanced graph topologies. Application of …

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