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Articles 2641 - 2670 of 2904

Full-Text Articles in Engineering

Enhancement Of Pool Boiling Heat Transfer Using Thermally-Conductive Microporous Coating Techniques, Joo Han Kim Dec 2006

Enhancement Of Pool Boiling Heat Transfer Using Thermally-Conductive Microporous Coating Techniques, Joo Han Kim

Mechanical and Aerospace Engineering Dissertations - Archive

The present research is an experimental study of the enhancement of boiling heat transfer using microporous coating techniques. The current research is divided into four major phases. During the first phase, the effects of different metal particle sizes in the coating compound for thermally non-conductive microporous coating on pool boiling performance of refrigerants and water are investigated. The test surfaces, solid copper blocks with 1-cm² base, were tested at atmospheric pressure in saturated FC-72, R-123, and water. Results showed that the surface treatment by non-conductive microporous coating significantly enhanced both nucleate boiling and critical heat flux of all three refrigerants. …

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Flexible Microfluidic Circuit With Embedded In-Plane Valve, Srikar C. Paruchuri Dec 2006

Flexible Microfluidic Circuit With Embedded In-Plane Valve, Srikar C. Paruchuri

Mechanical and Aerospace Engineering Theses - Archive

Recent developments in Microfluidic systems have demonstrated many potential applications related to biology, chemistry and medical sciences. Fluidic manipulation with precise volume control is a basic function in these systems, and microvalves play an important role in control and delivery of the fluid sample. One of the key issues in such valve design is to make large membrane deflections compared to the channel dimension. This thesis reports a flexible microfluidic chip with embedded in-plane valves for fluid manipulation. Silicone elastomer (Polydimethylsiloxane - PDMS) is one of the most suitable materials to fabricate microvalve membranes, because of its low Young's modulus, …

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Computer-Aided Patient Specific Treatment Planning Of Cryosurgery For Breast Cancer, Junkyu Jung Dec 2006

Computer-Aided Patient Specific Treatment Planning Of Cryosurgery For Breast Cancer, Junkyu Jung

Mechanical and Aerospace Engineering Theses - Archive

Cryosurgery, which is to destroy tumors by use of localized freezing, is an emerging treatment modality for breast cancer as the size of detectable tumor becomes smaller due to more frequent use of various diagnostic imaging including MRI, CT and mammogram. Although general surgical guideline has been developed and its effectiveness has been demonstrated, cryosurgical protocol should be adjusted for a given patient to accommodate patient-specific variations including tumor size, location and geometry of patient's breast. In this study, a computerized treatment planning tool was developed to aid surgeons to determine surgical parameters considering patient specific diagnostic information. This tool …

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Freezing-Induced Microstructural Changes Of Collagen Scaffolds, Jeffrey David Miller Dec 2006

Freezing-Induced Microstructural Changes Of Collagen Scaffolds, Jeffrey David Miller

Mechanical and Aerospace Engineering Theses - Archive

Understanding the effects of freezing on the functional properties of tissues is critical to cryopreservation of native and artificial tissues, and prognosis after cryotherapies. Although investigations have been performed to correlate macroscopic properties such as mechanical properties with freezing parameters, the effects are typically tissue-type dependent and no physical understanding is available to explain these effects. Since the mechanical and optical properties of a tissue are based on the characteristics of its extracellular matrix (ECM), understanding and quantifying these changes could assist in predicting the response a tissue will have to freezing under different circumstances. In this study, the microstructural …

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Micromechanical Analysis Of Yielding For Particulate Filled Composites, Chih-Ta Chen Dec 2006

Micromechanical Analysis Of Yielding For Particulate Filled Composites, Chih-Ta Chen

Material Science and Engineering Theses - Archive

Particulate filled composites are hybrid materials which consist of particulates held together by a matrix. In this thesis, a simulation method to obtain overall failure criterion for particulate filled composites based on the computer software "MATHEMATICA" will be presented. The composite is assumed to fail at the matrix just outside the inclusion. By Self-Consistent Method, the composite can be imaged as an inclusion embedded within effective matrix. The Equivalent Inclusion method is then applied to stimulate the stress field within the inclusion. Stress just outside inclusion can be calculated because interfacial traction force on the boundary of inclusion is continuous. …

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Experimental Investigation Of Shear Capacity Of Precast Reinforced Concrete Box Culverts, Jarrod Clinton Burns Dec 2006

Experimental Investigation Of Shear Capacity Of Precast Reinforced Concrete Box Culverts, Jarrod Clinton Burns

Civil Engineering Theses - Archive

This study presents the experimental investigation of the shear capacity of four precast rinforced concrete box culverts. Each culvert was subjected to a monotomically increasing load through a 20-in x 10-in load plate, designed to simulate a standard HS 20-44 wheel footprint. Each box was instrumented with the following: strain gages, load cell, high-resolution laser sensor, data acquisition hardware and software, and laptop computer. The tests were conducted on 1.22 m x 1.22 m x 1.22 m (4 ft x 4 ft x 4 ft) box culverts, with load being applied at the free spigot end. The location of the …

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Spectroscopic Characterization Of Biliary Tract Tissues In-Vivo To Assist Laparoscopic Cholecystectomy, Sarita Kommera Dec 2006

Spectroscopic Characterization Of Biliary Tract Tissues In-Vivo To Assist Laparoscopic Cholecystectomy, Sarita Kommera

Bioengineering Theses - Archive

Laparoscopic Cholecystectomy is a surgical method for removal of gallbladder when it is diseased with gall stones. Almost 750,000 people are affected with this disease annually in USA. Gall bladder is removed by placing an incision on the cystic duct. This duct is totally embedded in fat (which is a few mm thick) in most of the cases and it becomes a huge problem decreasing the visual capability of the surgeon to distinctly locate the duct. Near Infrared Spectroscopy (NIRS) can solve the fuzziness as it penetrates in a few mm thick tissues. NIRS is one of the simplest techniques …

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Novel Intraocular Drug Delivery System For The Prevention Of Posterior Capsule Opacification, Brett Thomes Dec 2006

Novel Intraocular Drug Delivery System For The Prevention Of Posterior Capsule Opacification, Brett Thomes

Bioengineering Dissertations - Archive

Posterior capsule opacification (PCO) is a major complication associated with the implantation of intraocular lens (IOLs). Evidence suggests that PCO formation is caused by abnormal lens epithelial cell (LEC) migration/proliferation. We hypothesize that pharmacologic agents must target inflammatory cells in addition to LECs to inhibit PCO formation. To successfully target both inflammatory cells and LECs, a novel intraocular drug delivery system (DDS) was developed for implantation in the lens capsular bag. Such a system permits direct delivery of anti-inflammatory and anti-proliferative drugs in the lens capsule for extended periods of time resulting in reduced PCO formation. A lubricious polyurethane coating …

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A Comprehensive Study Of The Effects Of Eeg Electrode Arrays On Mri Signal-To-Noise At 3t, Aman Ish Goyal Dec 2006

A Comprehensive Study Of The Effects Of Eeg Electrode Arrays On Mri Signal-To-Noise At 3t, Aman Ish Goyal

Bioengineering Theses - Archive

Simultaneous EEG-fMRI offers much potential for gaining complementary, noninvasive information about brain function. While much effort has been devoted to the compelling problem of removing ballistocardiogram and gradient artifacts from the EEG waveforms, less attention has been paid to the impact that increasing density of electrode arrays has on the MR images. Initial work reporting the effects of EEG caps and electrodes on the MR image has been site specific, using customized EEG equipment that those research groups built in-house. Therefore these results are hard to generalize to other laboratory environments. A monotonic decrease in SNR of the images has …

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Localization Algorithms For Passive Targets In Radar Networks, Kartik Trasi Dec 2006

Localization Algorithms For Passive Targets In Radar Networks, Kartik Trasi

Electrical Engineering Theses - Archive

In this study, we propose an improved, robust algorithm for passive targets in radar networks. The main objective of this work is to improve the localization accuracy of the algorithm based on signal properties in combination with robust graphical techniques. We present a numerical approach and an experimental validation of the modified algorithm.

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Observer Synthesis For Linear/Nonlinear Dynamical Systems Subject To Measurement Delays, Praveen C. Muralidhar Dec 2006

Observer Synthesis For Linear/Nonlinear Dynamical Systems Subject To Measurement Delays, Praveen C. Muralidhar

Electrical Engineering Theses - Archive

In this research, problems associated with communication delays on the stability of formation of a group of unmanned vehicles is examined and solution to this problem is proposed. Ideally, it is required that the information transfer between the vehicles participating in a cooperative task be available immediately. But, in reality, there is always a delay between the instants at which the information is transmitted by one vehicle and the instant at which it is received by the other vehicles in the formation. A state observer is used to estimate the time delayed signal. The observer consists of two dynamic systems …

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Optimization Of The Tool Path In A Robotic Environment, Mukund Venkatachari Narasimhan Dec 2006

Optimization Of The Tool Path In A Robotic Environment, Mukund Venkatachari Narasimhan

Mechanical and Aerospace Engineering Dissertations - Archive

The rising costs and demand coupled with shrinking energy generating resources has triggered the need for optimum use of energy resources, minimizing the overhead costs and maximizing the profits. Robots have been long touted as a fit replacement of human labor force in manufacturing sectors. Slowly there is increased presence of robots in automobile and electronic industries. Typically they are used for welding, painting, ironing, assembly, pick and place, inspection, and testing. Mass production, fulfilling the ever increasing demand, can be accomplished by robots because of their precision, speed of operation and high endurance capabilities. This dissertation comprises of two …

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Analysis Of Hat Sectioned Reinforced Composite Beams Including Thermal Effects, Kashif Ali Nayyer Syed Dec 2006

Analysis Of Hat Sectioned Reinforced Composite Beams Including Thermal Effects, Kashif Ali Nayyer Syed

Civil Engineering Dissertations - Archive

A simple analytical method for analyzing fiber reinforced polymeric composite beams with hat cross-section is presented. The method includes development of closed-form expression of the axial, bending and their coupling stiffness matrices for the composite beams. The stiffness matrices are obtained by transforming the actual geometrical cross-section of the beam into an equivalent plate using transformation matrices and Parallel Axis theorem. Ply stresses due to mechanical as well as thermal load can easily be obtained at any given location of the beam section. In this approach, the effect of induced in-plane deformation due to bending for an unsymmetrical cross-section is …

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Generation Planning And Market Operation Strategies In The Southwest Power Pool Energy Imbalance Service Market, Kittipong Methaprayoon Dec 2006

Generation Planning And Market Operation Strategies In The Southwest Power Pool Energy Imbalance Service Market, Kittipong Methaprayoon

Electrical Engineering Dissertations - Archive

The transition of the Southwest Power Pool (SPP) from its traditional operation under tariff towards the new market environment has significant impact on the utilities in the SPP footprint, both in terms of planning and operations. The new market regulation creates the need for the utilities to reassess their planning strategy, primarily to ensure that operational decisions conform to the new market rules while remain profitable under the new operating regime. The utilities are referred to as Market Participants (MP) under the new market scheme. The new market environment will expose the MPs to a large amount of information with …

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Fiber Optic Scanner Using Electromagnetic Actuation With Different Ferromagnetic Materials, Pratibha C. Phuyal Dec 2006

Fiber Optic Scanner Using Electromagnetic Actuation With Different Ferromagnetic Materials, Pratibha C. Phuyal

Electrical Engineering Theses - Archive

A fiber optic scanner capable of scanning medical imaging actuated by an external magnetic field is designed and characterized using different magnetized and non magnetized ferromagnetic materials. Cobalt, Iron, Nickel, and Samarium Cobalt powders were used before and after magnetization to perform the actuation. Plastic optical fiber and a silica optical fiber are coated with 70 % enamel paint with 30 % different ferromagnetic materials mixed using brush. Due the low Young's Modulus, the plastic optical fiber could not actuate like silica optical fiber. Therefore, the silica fiber was used to conduct the experiments. The static and dynamic measurements were …

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Miniature Optical Coherence Tomography Probe, Asif Rizwan Dec 2006

Miniature Optical Coherence Tomography Probe, Asif Rizwan

Bioengineering Theses - Archive

A piezo based optical scanner for high speed optical coherence tomography (OCT) has been developed. Design of the miniature probe has been optimized to take advantages of the high speed depth scanning that can be achieved with spectral domain OCT (SD-OCT) systems. Three prototype scanning probes were constructed and tested for OCT imaging. Movies and images of tissues are presented which were taken at frame rates ranging from 50~100fps. Data were acquired at 18000 A-lines per second at an effective integration time of 55us.

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Optical Coherence Tomography Of Oral Mucosa, Nidhi Bharatbhai Mehta Dec 2006

Optical Coherence Tomography Of Oral Mucosa, Nidhi Bharatbhai Mehta

Bioengineering Theses - Archive

Oral cancer causes 120000* deaths annually around the world and 280000* new cases are diagnosed every year. Technology has developed and the death rate of oral cancer has improved over the last few decades; hence to improve the survival rate, development of a technique able to diagnose carcinomas in its early stages is very important. OCT is a non invasive imaging technique capable to provide high resolution microstructure images of tissue. A development of in vivo OCT; capable to image tissue with micrometer resolution and able to identify pre cancerous morphological changes non invasively could improve survival rate in cancer …

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Finite Element Modeling Of Carbon Nanotube Reinforced Polymer Composites And Evaluating Its Thermal Conductivities, Raghuram Basavanahalli Dec 2006

Finite Element Modeling Of Carbon Nanotube Reinforced Polymer Composites And Evaluating Its Thermal Conductivities, Raghuram Basavanahalli

Mechanical and Aerospace Engineering Theses - Archive

High thermal conductivity of carbon nanotubes has motivated us to study and understand the thermal mechanisms in nanocomposites. Though several theoretical models predict a high thermal conductivity for CNT reinforced polymer composites, the experimental validation are not so encouraging. A finite element model of MWNT reinforced nanocomposite is developed based on continuum mechanics approach. The finite element model is a representative volume element (RVE) with single MWNT inclusion. The inclusion is modeled based on the continuum model of MWNT as effective solid fiber [22].The interface resistance between the nanotube and the matrix material is modeled using thermal contact elements. The …

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Structural Analysis Of Fiber Reinforced Composite Materials, Cesar Augusto Rojas Dec 2006

Structural Analysis Of Fiber Reinforced Composite Materials, Cesar Augusto Rojas

Mechanical and Aerospace Engineering Theses - Archive

A study of fiber reinforced composite structures is conducted .This study includes laminate analysis, analysis of laminated composite beams and parametric study of composite beams. Finite element analysis for each beam model is conducted to verify the results obtained by analytical model. The analysis of the laminated beams in this study covers: 1. beam with a solid rectangular cross-section subjected to a transverse load 2. beam with a I-section under bending 3. beam with a squared tubular section under bending 4. beam with truss section under bending One of the principal purposes of this thesis is to create a user …

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Investigation On The Mechanism Of Interface Electromigration (Em) In Copper (Cu) Thin Films, Jee Yong Kim Dec 2006

Investigation On The Mechanism Of Interface Electromigration (Em) In Copper (Cu) Thin Films, Jee Yong Kim

Material Science and Engineering Dissertations - Archive

This study concerns the mechanism of the interface electromigration (EM) in copper (Cu) thin films. While EM in Cu is one of the most concerned reliability failure phenomena in Cu interconnects used microelectronic devices, its mechanism is not well understood yet. In order for better understanding of the EM mechanism, this study attempt to investigate the interface EM mechanism by examining the passivation effects on Cu EM using a cross-strip structure where Cu lines are cross-stripped with different passivation layers. From the observation of the marker polarity (hillocks and voids), the interface EM mechanism is determined whether the passivation layer …

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Trends Of Vehicular Emissions Due To The Effect Of Ethos® Fr As Fuel Additive, Shruthi Satyanarayan Dec 2006

Trends Of Vehicular Emissions Due To The Effect Of Ethos® Fr As Fuel Additive, Shruthi Satyanarayan

Civil Engineering Theses - Archive

The main objective of this research was to observe if the addition of the fuel additive Ethos Fuel Reformulator significantly reduced the emissions of CO, CO2, HC and NOX from a light duty vehicle. Data collection was carried out before and after the application of Ethos FR for both Peak and Off-peak traffic conditions, on highway as well as arterial test track. The OBS-1300 analyzed second by second concentrations of the tailpipe emissions. Data analysis was conducted and the following results were observed. 1. There was a significant reduction in NOx Emissions, with the maximum of 45% in the Arterial …

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Neural Network Solution For Fixed-Final Time Optimal Control Of Nonlinear Systems, Tao Cheng Dec 2006

Neural Network Solution For Fixed-Final Time Optimal Control Of Nonlinear Systems, Tao Cheng

Electrical Engineering Dissertations - Archive

In this research, practical methods for the design of H2 and H-Infinity optimal state feedback controllers for unconstrained and constrained input systems are proposed. The dynamic programming principle is used along with special quasi-norms to derive the structure of both the saturated and optimal controllers in feedback strategy form. The resulting Hamilton-Jacobi-Bellman (HJB) and Hamilton-Jacobi-Isaacs (HJI) equations are derived respectively. Neural networks are used along with the least-squares method to solve the Hamilton-Jacobi differential equations in the H2 case, and the cost and disturbance in the H-Infinity case. The result is a neural network unconstrained or constrained feedback controller that …

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Performance Analysis And Design Of Space-Time Codes, Chen Liao Dec 2006

Performance Analysis And Design Of Space-Time Codes, Chen Liao

Electrical Engineering Dissertations - Archive

In this dissertation, performance and design of space-time codes have been studied. The main objective of this dissertation has been to improve the performance of space-time codes. This dissertation covers a wide range of topics in space-time codes. It involves theoretical analysis, design, and implementation for space-time trellis codes, space-time turbo codes, and orthogonal space-time codes. We begin with the study of performance analysis of upper bound of pair-wise error probability (PEP) and exact PEP. The exact PEP is derived using a straightforward method. The exact PEP provides a better understanding of the performance behavior to the other range of …

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Scalar Equilibria For N-Person Games, Narakorn Engsuwan Dec 2006

Scalar Equilibria For N-Person Games, Narakorn Engsuwan

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

In this dissertation we develop a scalarization approach for one-shot, n-person games by defining the notion of Scalar Equilibria. We first show that existing solution concepts can be represented as Scalar Equlibria. For example, Regret, Disappointment, and Joint Equilibrium can be determined by defining Regret, Disappointment, and Joint Scalar Equilibria. These scalar equilibria are useful for finding pure strategies when pure Regret, Disappointment, and Joint Equilibria do not exist. Next, we present the Maximin Scalarization Equilibrium to yield maximin solution concept. In addition, we propose other Scalar Equilibria for various notions of rationality. The Aspiration Scalar Equilibrium is developed for …

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Dynamic Stability Analysis Of Large-Scale Power Systems Using A Fast Investigation Method, Ming-Tse Kuo Dec 2006

Dynamic Stability Analysis Of Large-Scale Power Systems Using A Fast Investigation Method, Ming-Tse Kuo

Electrical Engineering Dissertations - Archive

Following power market deregulation and the proposed standard market design, the activities of cross boundary power transactions are increased significantly. Traditional company based stability analysis can not satisfy today's operating environment. However, simulating the entire interconnection power system may exceed the capacity of existing commercial stability analysis software. Fortunately, most of the stability problems are started from the local level. One will be able to avoid most of the system wide stability issues by mitigating the problems in the early stage. Based on eigenvector decompositions of the Jacobian, this dissertation proposes a new algorithm for performing the dynamic stability problem …

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Fabrication, Characterization And Hall Mobility Analysis Of Mos Devices With Low-K And High-K Dielectric Materials, Rakshit Agrawal Dec 2006

Fabrication, Characterization And Hall Mobility Analysis Of Mos Devices With Low-K And High-K Dielectric Materials, Rakshit Agrawal

Electrical Engineering Theses - Archive

Scaling of MOSFETS has led to leakage current problems in SiO2 dielectric based MOSFETS. This has led to the introduction of high-k dielectric materials which can afford greater physical thickness and achieve the same capacitance with lesser equivalent oxide thickness. But the high-k devices have certain limitations like channel mobility degradation. Mobility degradation in high-k MISFETS is discussed in this work using Hall measurements. The MOS devices were fabricated with SiO2 and HfSiO, on p-type silicon substrate. The fabrication process flow used for both type of MOS devices is explained. Characterization and analysis was performed for the determination of various …

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Experimental And Finite Element Based Investigations Of Shear Behavior In Reinforced Concrete Box Culverts, Anil Kumar Garg Dec 2006

Experimental And Finite Element Based Investigations Of Shear Behavior In Reinforced Concrete Box Culverts, Anil Kumar Garg

Civil Engineering Dissertations - Archive

This study evaluates the shear behavior and capacity of the precast concrete box culverts subjected to HS 20 truck wheel load. The most critical culvert behavior was considered by studying culverts subjected to zero depth fill and placed on rigid laboratory floor without bedding material. Three major phases were considered to complete the study, which included: (1) experimental program; (2) finite element modeling; and (3) development of distribution width and the determination of shear capacity. A full-scale experimental testing program was undertaken to perform tests on 24 typical precast concrete box culverts designated as per ASTM C 1433-05 with and …

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Design And Optimization Of Heat Spreaders And Selection Of Fan In Laptop, Kranthi Kumar Manne Sambaiah Dec 2006

Design And Optimization Of Heat Spreaders And Selection Of Fan In Laptop, Kranthi Kumar Manne Sambaiah

Mechanical and Aerospace Engineering Theses - Archive

Technical advancements lead to the need for faster processors and reduced sizes in electronic systems. The urge for faster and compact systems leads to two major problems. Firstly over heating of chips which degrade the chip performance and secondly formation of heat spots on the surface which makes the user uncomfortable. Thermal management engineers, as a result have a major challenge in improving the cooling systems. In this research project simulation using the thermal modeling tool selected is Icepak. The prototype model of the laptop is designed, boundary conditions are applied and analysis is done. The results so obtained in …

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Arribot- An Enabler For Studying Mobile Wireless Sensor Networks, Jaymala Suresh Ghadigaonkar Dec 2006

Arribot- An Enabler For Studying Mobile Wireless Sensor Networks, Jaymala Suresh Ghadigaonkar

Electrical Engineering Theses - Archive

The objective of this thesis is to structure a mobile wireless sensor network using low cost, custom made robotic platforms. Over the years, several projects have proved that the performance of a static wireless sensor network (WSN) is greatly enhanced by using mobile WSN for applications like adaptive exploration or in search and rescue missions where the network topology changes with changes in the environment. A low cost, mobile wireless sensor node known as the ARRI BOT has been designed to contribute along with other robotic platforms in structuring an ingenious mobile wireless sensor network (MSWN). The ARRI BOT has …

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Physical Layer And Application Layer Issues Of Wireless Sensor Networks, Lingming Wang Dec 2006

Physical Layer And Application Layer Issues Of Wireless Sensor Networks, Lingming Wang

Electrical Engineering Dissertations - Archive

The potential for collaborative, robust networks of wireless sensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that wireless sensor networks will enable. Location sensing, environmental observation and surveillance, medical monitoring and a lot other applications are all gaining interest. However, wireless sensor network poses a large number of challenges. Among all, one of the most important challenges is design sensor networks that have long network lifetime, which will become especially difficult due to the energy-constrained nature of the sensor nodes. In this thesis, we focus on physical and …

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