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Articles 2941 - 2970 of 3180

Full-Text Articles in Engineering

An Evaluation Of Using Component Mode Synthesis For Structural Models, Richard Lynn Scott May 2007

An Evaluation Of Using Component Mode Synthesis For Structural Models, Richard Lynn Scott

Mechanical and Aerospace Engineering Theses - Archive

Structural analysts have used component mode synthesis (CMS), also known as substructuring, for decades to divide large structural models into smaller, more manageable models, and to reduce the size of the associated mathematical problem. Applying CMS can also reduce the front-end effort to build models, even models that are smaller than those for which CMS has typically been applied. This paper presents an evaluation of the accuracy of two smaller substructured models so that analysts might feel confident in applying CMS to gain the benefits. The evaluation starts with an introduction to CMS. Then, CMS is applied to a small, …

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Control And Simulation Of Relative Motion For Aerial Refueling In Racetrack Maneuver, Eunyoung Kim May 2007

Control And Simulation Of Relative Motion For Aerial Refueling In Racetrack Maneuver, Eunyoung Kim

Mechanical and Aerospace Engineering Theses - Archive

This thesis addresses the problem of controlling the receiver aircraft to achieve a successful aerial refueling. For the performance verification of the controller, a new set of nonlinear, 6-DOF, rigid body equations of motion for the receiver aircraft has been used. The equations are written in terms of state variables that are relative to the reference frame that is attached to, translates and rotates with the tanker aircraft. Furthermore, the nonlinear equations contain the wind effect terms and their time derivatives to represent the aerodynamic coupling involved between the two aircraft. These wind terms are obtained using an averaging technique …

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H-Infinity Output Feedback Control: Application To Unmanned Aerial Vehicle, Jyotirmay Gadewadikar May 2007

H-Infinity Output Feedback Control: Application To Unmanned Aerial Vehicle, Jyotirmay Gadewadikar

Electrical Engineering Dissertations - Archive

This dissertation presents new necessary and sufficient conditions for static output-feedback control of linear time-invariant systems using the H-Infinity approach. Simplified conditions are derived which only require the solution of two coupled matrix design equations. It is shown that the static output-feedback H-Infinity solution does not generally yield a well-defined saddle point for the zero sum differential game; conditions are given under which it does. This work presents a simplified parameterization of all H-Infinity static state-feedback controllers in terms of a single algebraic Riccati equation and a free parameter matrix. As a special case, necessary and sufficient conditions for the …

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Ccbdi Readout Circuit For Ybacuo Micromachined Microbolometers, Sandeep Kumar May 2007

Ccbdi Readout Circuit For Ybacuo Micromachined Microbolometers, Sandeep Kumar

Electrical Engineering Dissertations - Archive

Semiconducting YBaCuO (Yttrium-Barium-Copper-Oxide) as a new uncooled microbolometer material is evaluated for CMOS compatibility. By not requiring cryogenic cooling, the self-supporting semiconducting YBaCuO micromachined microbolometers have found an attractive application for thermal detection with substantial reduction in system cost, size, weight and power consumption as compared to cooled photon detectors. The lower thermal conductance of the microbolometers to the substrate provides good sensitivity for infrared detection. The CCBDI (Constant Current Buffered Direct Injection) readout circuit is designed to work with a traditional frame rate of 30Hz and as a novel approach improves the performance of uncooled IR cameras by a …

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New Equilibria For Noncooperative Games, Phantipa Insuwan May 2007

New Equilibria For Noncooperative Games, Phantipa Insuwan

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

In this dissertation we present an alternative to the Nash Equilibrium (NE), which is regarded as the fundamental solution concept in game theory. An NE provides a solution in which no player can improve his payoff by unilaterally changing strategies. However, the NE has weaknesses as exemplified by the paradoxical Prisoner's Dilemma game, where the unique NE is dominated by another possible outcome. Moreover, an NE assumes all players select their strategies according to the same NE so equilibrium holds. For multiple NE's, no standard approach exists for selecting a single one, though various refinements such as perfect Nash equilibria …

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Design, Fabrication And Assembly Of 3-D Microstructures, Ping Zhang May 2007

Design, Fabrication And Assembly Of 3-D Microstructures, Ping Zhang

Electrical Engineering Dissertations - Archive

The primary goal of a micro-electro-mechanical system (MEMS) is to integrate electronics, sensors and actuators into a tiny system, which can be easily fabricated and packaged. Currently there is no standard process for manufacturing all the sub-components since a lot of them are made from different materials and fabrication technologies. Therefore, there is a great interest to develop a reliable manufacturing approach that allows for the integration of multiple micro devices on a single chip. This work describes two approaches to achieve this heterogeneous integration: (1) hybrid material integration by introducing new materials into a well-known self-assembly platform (PolyMUMPs) to …

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Runway Incursion Mitigation, Capacity Enhancement, And Safety Improvements With Perimeter Taxiway Operations At Dallas Fort Worth International Airport, Satyamangalam D. Satyamurti May 2007

Runway Incursion Mitigation, Capacity Enhancement, And Safety Improvements With Perimeter Taxiway Operations At Dallas Fort Worth International Airport, Satyamangalam D. Satyamurti

Civil Engineering Dissertations - Archive

A perimeter taxiway (PT) or end-around taxiway (EAT) operation is a new concept being developed at several airports around the country to eliminate active departure runway incursions during peak periods. PTs will enhance capacity by permitting uninterrupted, safe, continuous takeoffs and landings within the operations framework and guidelines established by the Federal Aviation Administration (FAA). For this research, the Dallas/Fort Worth International Airport's (DFW) proposed PT operations are considered for analysis and evaluation. This concept is tested using actual historical flight data at DFW for simulation and analytical modeling based on the FAA safety factors available in the Visual SIMMOD …

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Thermal Effects On Analog Integrated Circuit Design, Md Mahbub Hossain May 2007

Thermal Effects On Analog Integrated Circuit Design, Md Mahbub Hossain

Electrical Engineering Dissertations - Archive

Analog Integrated Circuit design (IC) is a big challenge in this modern age. Thermal effect has a substantial role in analog ICs performance. Thermal effects on analog IC design have been investigated in this dissertation project. National Semiconductor Corporation's Vertical Bipolar Inter-Company (VBIC) model of dielectrically isolated bipolar junction transistors (DIBJT) with VIP10 and VIP11 processes have been used for the research. These devices are used for the high speed IC design. Self-heat generated inside these devices is confined within the device and degrades the device performance. In addition, the thermal characteristic of a device surrounded by the multiple adjacent …

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Analysis Of Tapered Laminated Composite Tubes Under Tension And Torsion, Chethana Shankara Rao May 2007

Analysis Of Tapered Laminated Composite Tubes Under Tension And Torsion, Chethana Shankara Rao

Mechanical and Aerospace Engineering Theses - Archive

Closed form expressions for determining the displacement and twisting angle of tapered composite tubes are developed. The analytical expressions are developed based on the modified laminated plate theory which includes the tubular wall curvature of the laminate. It is found that the axial deformation and the twisting angle calculated by the current method agree well with the results obtained from the finite element method. The effect of stacking sequence, taper angle and fiber orientations on the axial deformation and twisting angle are studied by using the developed method. It is found that the taper angle plays a significant role on …

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Permeability Of Municipal Solid Waste In Bioreactor Landfill With Degradation, Kiran Kumar Penmethsa May 2007

Permeability Of Municipal Solid Waste In Bioreactor Landfill With Degradation, Kiran Kumar Penmethsa

Civil Engineering Theses - Archive

Bioreactor landfills are operated and controlled to accelerate refuse decomposition, gas production and biological stabilization of the municipal solid waste (MSW). Leachate recirculation in bioreactor landfill creates a favorable environment for rapid microbial decomposition of the biodegradable components of solid waste. Therefore, clear understanding of the mechanism of moisture movement within the solid waste would be necessary for successful design and operation of the bioreactor landfill. Permeability is an important parameter during the design of leachate collection and recirculation system. In the current study an experimental program was designed to determine the variation of coefficient of permeability of MSW with …

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Autotrophic Denitrification Of Groundwater In A Granular Sulfur-Packed Up-Flow Reactor, Shih-Hui Pan May 2007

Autotrophic Denitrification Of Groundwater In A Granular Sulfur-Packed Up-Flow Reactor, Shih-Hui Pan

Civil Engineering Dissertations - Archive

Autotrophic denitrification is an effective treatment technique for nitrate removal from groundwater. Six basic elements are required for the growth of autotrophic denitrifiers: (1) electron donor, (2) electron acceptor, (3) active bacteria, (4) anoxic/anaerobic environment, (5) micronutrients, and (6) optimum pH and temperature. In this research, granular sulfur is an electron donor; nitrate is an electron acceptor; anoxic and anaerobic environment was maintained in the reactor, and micronutrients were added; pH was controlled between 6 and 9, and temperature was maintained at the room temperature (20 + 2 oC). Batch reactor and continuous up-flow reactor experiments were carried out to …

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Improved Refinement Coefficients' Coding In Scalable H.264, Rahul Panchal Apr 2007

Improved Refinement Coefficients' Coding In Scalable H.264, Rahul Panchal

Electrical Engineering Theses - Archive

This thesis proposes to replace the adaptation used to select VLC table for coding of the refinement coefficient by signaling to the decoder which table should be used for which macroblock type (Inter or Intra) in scalable H.264. This part of the proposal aims at reducing decoder complexity and ensuring proper table selection when both macroblock types are present within one slice. The contribution further proposes to extend the method used in SVC to increase coding efficiency of CABAC refinement coefficient coding to "VLC" refinement coefficients coding. All the coding tools are integrated into JSVM_7_10 and the performance is tested. …

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Multiplexing H.264 Video With Aac Audio Bit Streams, Demultiplexing And Achieving Lip Synchronization During Playback, Harishankar Murugan Apr 2007

Multiplexing H.264 Video With Aac Audio Bit Streams, Demultiplexing And Achieving Lip Synchronization During Playback, Harishankar Murugan

Electrical Engineering Theses - Archive

H.264, MPEG-4 part-10 or AVC [5], is the latest digital video codec standard which has proven to be superior than any early standards in terms of compression ratio, quality, bit rates and error resilience. However, the standard just defines a video codec and has no mention of any audio compression. In order to have a meaningful delivery of the video to the end user, we need to associate an audio stream along with it. AAC (advanced audio coding) [1] is the latest digital audio codec standard defined in MPEG-2 and later in MPEG-4 with few changes. The audio quality of …

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Transcoding From H264 Bitstream To Mpeg-2 Bitstream, Sreejana Sharma Apr 2007

Transcoding From H264 Bitstream To Mpeg-2 Bitstream, Sreejana Sharma

Electrical Engineering Theses - Archive

H.264/AVC was recently developed by the JVT (Joint Video Team). This new standard fulfills significant coding efficiency, simple syntax specifications and seamless integration of video coding into all current protocols and multiplex architectures. The H.264 specification represents a significant advancement in the field of video coding technology by providing MPEG-2 comparable video quality at an average of half the required bandwidth. Since widespread use of H.264 is anticipated, many legacy systems including all Digital TVs and home receivers use MPEG-2. This leads to the need for an efficient architecture that significantly employs the lower cost of H.264 video and does …

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A Piecewise Linear Classifier, Abdul Aziz Abdurrab Apr 2007

A Piecewise Linear Classifier, Abdul Aziz Abdurrab

Electrical Engineering Theses - Archive

A piecewise linear network is discussed which classifies N-dimensional input vectors. The network uses a distance measure to assign incoming input vectors to an appropriate cluster. Each cluster has a linear classifier for generating class discriminants. A training algorithm is described for generating the clusters and discriminants. A pruning algorithm is also described. The algorithm is applied after the network has grown completely, i.e, it has achieved the maximum number of clusters. The pruning algorithm eliminates the least important clusters, one at a time, leading to a more compact network. Theorems are given which relate the network's performance to that …

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Operations-Oriented Performance Measures For Freeway Management Systems: Year 1 Report, Robert E. Brydia, William H. Schneider, Stephen P. Mattingly, Melanie L. Sattler, Auttawit Upayokin Apr 2007

Operations-Oriented Performance Measures For Freeway Management Systems: Year 1 Report, Robert E. Brydia, William H. Schneider, Stephen P. Mattingly, Melanie L. Sattler, Auttawit Upayokin

Civil Engineering Faculty Publications - Archive

This report describes the year 1 activities on the project titled “Using Operations-Oriented Performance Measures to Support Freeway Management Systems.” Work activities included a comprehensive statewide survey on the use of performance measurement, as well as the initial recommendation on both operations and emissions-oriented performance measures to use in support of daily operations.

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Stated Preference Modeling And Analysis Of Managed Lanes, Kaveh Farokhi Sadabadi Apr 2007

Stated Preference Modeling And Analysis Of Managed Lanes, Kaveh Farokhi Sadabadi

Civil Engineering Theses - Archive

The thesis deals with the Managed Lanes demand estimation problem in the state of Texas. Managed Lanes are a general type of High Occupancy Toll roads, whose lane management and operational features may be dynamically adjusted. A stated preference survey is designed in both English and Spanish to collect the required data. Each survey taker is presented with up to four scenarios. Scenarios are defined in terms of travel times in Managed Lanes versus General Purpose Lanes, as well as, the toll charged for access to the Managed Lane. Respondents were asked to choose among three modes and two lane …

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A Functional Link Network Using Ordered Basis Functions, Saurabh Sureka Apr 2007

A Functional Link Network Using Ordered Basis Functions, Saurabh Sureka

Electrical Engineering Theses - Archive

A new function approximation and classification network based on Functional Link Network (FLN) with orthonormal Polynomial Basis Functions (PBF) is presented. By using an iterative Gram-Schmidt procedure, the PBF's are orthonormalized, ordered and selected based on their contribution to minimize the Mean Square Error (MSE). Linearly dependent and less useful PBF are detected and eliminated at an early stage thereby improving the approximation capabilities and reducing the possibility of combinatorial explosion. The number of passes through the data during network training is minimized through the use of correlations. A one-pass method is used for validation and network sizing. Equivalent function …

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Rf Sputtered Sixge1-X And Sixge1-Xoy Thin Films For Uncooled Infrared Detectors, Mukti M. Rana Mar 2007

Rf Sputtered Sixge1-X And Sixge1-Xoy Thin Films For Uncooled Infrared Detectors, Mukti M. Rana

Electrical Engineering Dissertations - Archive

The objective of this work is to find a suitable combination of radio frequency (RF) sputtered SixGe1-x and SixGe1-xOy thin films for uncooled infrared detection. Thus, fabricating and characterizing microbolometers with SixGe1-x and SixGe1-xOy thin films as the sensing material are the ultimate goal of this work. Thin films of SixGe1-x and SixGe1-xOy were deposited by RF magnetron sputtering at room temperature from a single target of SixGe1-x in Ar or Ar : O2 environment. The silicon and oxygen concentrations were varied in a parametric investigation of the dependence of the electrical and optical characteristics of the thin films on …

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Dynamic Voltage Restorer For Sensitive Equipment, Yea Zong Kuo Mar 2007

Dynamic Voltage Restorer For Sensitive Equipment, Yea Zong Kuo

Electrical Engineering Dissertations - Archive

Voltage sags are considered to be the most frequent type of disturbances in the field based on recent power disturbances studies. Their impact on sensitive loads is severe. The impact ranges from load disruptions to substantial economic losses. Despite the technical advances in electronics, there are still some pieces of equipment that are so sensitive that they are unable to withstand voltage sags. An example is the equipment in semiconductor manufacturing. As a result, there is still a search for different ways to manage voltage sags. There are many different methods to mitigate voltage sags, but a CUstom Power Supply …

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Issues In Front-End Engineering Of Cmos Nanoelectronics, Xiaolong Yang Mar 2007

Issues In Front-End Engineering Of Cmos Nanoelectronics, Xiaolong Yang

Electrical Engineering Dissertations - Archive

Several issues exist in current CMOS front-end engineering such as interfacial layer formation at high-k/Si interface, high metal/Si contact resistance in source and drain regions, and absence of a quantitative model for silicon-germanium alloy growth. In this dissertation, monolayer Se passivation is employed to create a Si (100) surface free of dangling bonds. Since dangling bonds are the origins of surface reaction sites and surface states, interfacial layer formation at high-k/Si interface can be suppressed and metal/Si contact resistance can be lowered by Se passivation. Firstly, results on interface engineering between HfO2 and n-type Si (100) with Se passivation are …

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Surface Modification Of 6h-Sic Under Vacuum Annealing Studied By Time Of Flight Positron Annihilation Induced Auger Electron Spectroscopy, Saurabh Mukherjee Jan 2007

Surface Modification Of 6h-Sic Under Vacuum Annealing Studied By Time Of Flight Positron Annihilation Induced Auger Electron Spectroscopy, Saurabh Mukherjee

Material Science and Engineering Theses - Archive

This thesis presents the first study of vacuum annealing of 6H- SiC surface using Time-of-Flight-Positron Annihilation induced Auger Electron Spectroscopy(TOF-PAES) . The study was the first application of a TOF-PAES spectrometer to the SiC. The increased efficiency of the TOF-PAES allows us to see simultaneously for the first time Si-LVV, C-KVV, O-KVV peaks in the PAES spectrum for SiC. The top layer surface concentrations of C, O and Si were monitored by TOF-PAES surface. The results indicate that the SiC surface was initially covered with a layer containing oxygen but largely devoid of Si which was subsequently removed as a …

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Simulation And Development Of Nanoscale Deposition Techniques Using Kinetic Monte Carlo, Corey Clark Jan 2007

Simulation And Development Of Nanoscale Deposition Techniques Using Kinetic Monte Carlo, Corey Clark

Electrical Engineering Dissertations - Archive

Modeling of deposition processes has become of extreme importance due to the small scale of devices and features as well as the reduction of time to market required by industry. Current modeling procedures have focused on individual aspects of growth as well as made assumptions that cause simplification of the problem to the point the models usefulness is limited. The Kinetic Monte Carlo (KMC) model developed in this work combines rate transitions that have been commonly found in KMC simulation along with energy density equations that help explain the transitions and formations of island in alloy deposition. Specifically the model …

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A Weighted Residual Parabolic Acceleration Time Integration Method For Problems In Structural Dynamics, Ali Abolmaali, S.H. Razavi, M. Ghassemieh Jan 2007

A Weighted Residual Parabolic Acceleration Time Integration Method For Problems In Structural Dynamics, Ali Abolmaali, S.H. Razavi, M. Ghassemieh

Civil Engineering Faculty Publications - Archive

In the proposed method, the variation of displacement in each time step is assumed to be a fourth order polynomial in time and its five unknown coefficients are calculated based on: two initial conditions from the previous time step; satisfying the equation of motion at both ends of the time step; and the zero weighted residual within the time step. This method is non-dissipative and its dispersion is considerably less than in other popular methods. The stability of the method shows that the critical time step is more than twice of that for the linear acceleration method and its convergence …

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Thermal Failure Mechanism And Voltammetry Metrology For Cu/Barrier/Low K Integration, Dongmei Meng Dec 2006

Thermal Failure Mechanism And Voltammetry Metrology For Cu/Barrier/Low K Integration, Dongmei Meng

Material Science and Engineering Dissertations - Archive

The present study investigates the thermal stability of Cu/barrier/porous low κ (PLK) integration first, and then a new characterization method based on voltammetry is developed to characterize quality of diffusion barrier and pore structure in low κ materials and its thermal stability. The study of thermal stability reveals that Cu/barrier/PLK interconnect fails by Cu out-diffusion through the defects of diffusion barrier into the PLK structure, which is driven by oxidation and stress gradient within the interconnect structure. The failure appears to be triggered by defects in diffusion barrier, however, such defects are not effectively detected by TEM observation due to …

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Preparation And Characterization Of Properties Of Electrodeposited Copper Oxide Films, Longcheng Wang Dec 2006

Preparation And Characterization Of Properties Of Electrodeposited Copper Oxide Films, Longcheng Wang

Material Science and Engineering Dissertations - Archive

Copper oxides, including cuprous oxide and cupric oxide, are prepared by electrochemical deposition. The structural, optical and electrical properties of as-deposited copper oxides are evaluated, based on which cuprous oxide is selected as a promising material for photovoltaic applications. Electrodeposited cuprous oxide is a p-type semiconductor with a direct band gap of 2.06 eV. The mechanism of how pH affects the structural and electrical properties of electro-deposited cuprous oxide films is studied. In the pH range of 7.5 to 12.0, there are three different preferred crystal orientations: (100), (110) and (111). With different orientations, cuprous oxide shows different surface morphology …

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Multi-Sensor Fusion Based Control For Autonomous Operations: Rendezvous And Docking Of Spacecraft, Jonathan Bryan Mcdonald Dec 2006

Multi-Sensor Fusion Based Control For Autonomous Operations: Rendezvous And Docking Of Spacecraft, Jonathan Bryan Mcdonald

Mechanical and Aerospace Engineering Theses - Archive

The project considers the problem of motion synchronization of free flying robotic spacecraft and serviceable floating objects in space. The synchronization maneuvers are based on sample and hold nonlinear translational and attitude control laws. GPS pseudorange signals and a vision based sensor unit are modeled to give position measurements; position and velocity estimates are extracted from the measurements based on Extended Kalman Filter models. A sensor data fusion algorithm in the form of a Federated Extended Kalman Filter is implemented that blends the estimates of the individual filters into a global estimate. Nonlinear simulations where a Pursuer spacecraft attempted to …

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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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