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Articles 2461 - 2490 of 2512

Full-Text Articles in Engineering

Optimizing Production Methods For Artifical Silk Proteins Through Bioreactor And Purification Studies Of Recombinant Proteins Expressed From Pichia Pastoris, Aaron Ramey Dec 2006

Optimizing Production Methods For Artifical Silk Proteins Through Bioreactor And Purification Studies Of Recombinant Proteins Expressed From Pichia Pastoris, Aaron Ramey

All Theses

Advancements in the field of biomaterials are being made to produce an artificial silk fiber. A gene was constructed which utilized components from both the dragline silk of Nephila clavipes and nematode collagen. For this engineered protein, the yeast strain Pichia pastoris was chosen to be the host organism. Previous research has shown P. pastoris to have comparatively low amounts of specific protein productivity. Therefore, this problem must be compensated for by obtaining extremely high cell densities. The main focus of this study was to optimize the fermentation parameters of transgenic yeast cultures within a bioreactor in order to increase …

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Influence Of Temperature And Polymer/ Mold Surface Interactions On Micro-Feature Replication At Ambient Pressure In Micro Injection Molding, Varun Thakur Dec 2006

Influence Of Temperature And Polymer/ Mold Surface Interactions On Micro-Feature Replication At Ambient Pressure In Micro Injection Molding, Varun Thakur

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This study assesses micro-feature replication at elevated mold temperature and ambient pressure using a variety of polymers. Moldings were made on the surface of stainless steel and silicon wafers containing features as small as 130 nm under isothermal conditions in a heated chamber by allowing polymer to spread over the features at ambient pressure. Feature replication was analyzed via AFM and SEM. Polymer behavior was characterized via melt contact angle and melt viscosity. While feature detail was well replicated, the moldings exhibited poor dimensional accuracy due to shrinkage. In general, polymers with low viscosity and surface tension comparable to the …

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Tannic Acid Crosslinked Collagens And Potential For Breast Tissue Engineering, Cheryl Parzel Dec 2006

Tannic Acid Crosslinked Collagens And Potential For Breast Tissue Engineering, Cheryl Parzel

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The purpose of this study was to develop and assess a potential key feature in a minimally-invasive breast reconstruction device and to collect information for an in vitro tissue test system. Tannic acid is a hydrolysable plant tannin, and it has been determined that tannic acid functions as a collagen crosslinking agent through both hydrogen bonding mechanisms and hydrophobic effects. Additionally, current research suggests that tannic acid may have anti-tumor properties. Therefore, it has been proposed that tannic acid can be used as an agent to induce apoptotic processes in any transplanted adult stem cells that are inclined to spontaneously …

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Emission Reduction In Small Displacement Diesel Engines Using Cooled Exhaust Gas Recirculation, Chris Simoson Dec 2006

Emission Reduction In Small Displacement Diesel Engines Using Cooled Exhaust Gas Recirculation, Chris Simoson

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A reduced-order dynamic model is presented and experimentally validated to demonstrate the use of cooled exhaust gas recirculation to alleviate the tradeoff between nitric oxide reduction and performance preservation in a small displacement diesel engine. Exhaust gas recirculation (EGR) is an effective method for internal combustion engine oxides of nitrogen (NOx) reduction, but its thermal throttling diminishes power efficiency. The capacity to cool exhaust gases prior to merging with intake air may achieve the desired pollutant effect while minimizing engine performance losses.
Simulation and experimental results revealed significant NOx reductions throughout all testing scenarios using EGR, but also experienced a …

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Haptics In Robotics And Automotive Systems, Erhun Iyasere Dec 2006

Haptics In Robotics And Automotive Systems, Erhun Iyasere

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Haptics is the science of applying touch (tactile) sensation and control to interaction with computer applications. The devices used to interact with computer applications are known as haptic interfaces. These devices sense some form of human movement, be it finger, head, hand or body movement and receive feedback from computer applications in form of felt sensations to the limbs or other parts of the human body. Examples of haptic interfaces range from force feedback joysticks/controllers in video game consoles to tele-operative surgery. This thesis deals with haptic interfaces involving hand movements. The first experiment involves using the end effector of …

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Hierarchical State Estimation For Wide Area Power Systems, Srivatsan Lakshminarasimhan Dec 2006

Hierarchical State Estimation For Wide Area Power Systems, Srivatsan Lakshminarasimhan

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This thesis presents the application of hierarchical state estimation techniques to consolidate the state output of a wide area power system network. In a wide area network a large number of interconnections exist between various utilities of the wide area. Power transactions between areas occur over large distances and hence for better security there is a need to monitor the state of the entire wide area systems. Hierarchical state estimation is preferred over integrated state estimation, due to the reduced computational time.
Using existing state estimators of the member utilities of the wide area in the bottom level of hierarchical …

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Development Of Fatigue Predictive Models Of Rubberized Asphalt Concrete (Rac) Containing Reclaimed Asphalt Pavement (Rap) Mixtures, Feipeng Xiao Dec 2006

Development Of Fatigue Predictive Models Of Rubberized Asphalt Concrete (Rac) Containing Reclaimed Asphalt Pavement (Rap) Mixtures, Feipeng Xiao

All Dissertations

In recent years, some by-products such as crumb rubber has been used to save money, protect the environment, and extend the life of asphalt pavements. In addition, the utilization of reclaimed asphalt pavement (RAP) is an acceptable practice in many states around the United States and many countries all over the world. However, the use of RAP containing crumb rubber has not been investigated in great detail, so it is essential to explore whether these materials have a positive effect on the fatigue life of asphalt pavement. In general, previous experience shows that the use of RAP has proven to …

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A Multidimensional Scaling And Participatory Design Approach To Classify Open Ended Aircraft Maintenance Data, Kunal Kapoor Dec 2006

A Multidimensional Scaling And Participatory Design Approach To Classify Open Ended Aircraft Maintenance Data, Kunal Kapoor

All Dissertations

The quality assurance data to be analyzed by the web-based surveillance and auditing tool (WebSAT) is both qualitative and quantitative. The forced responses to checklist questions provide a definitive outcome identifying the effectiveness of the four quality assurance work functions. On the other hand, open-ended responses, the second type of response for capturing maintenance errors, are qualitative in nature since they reflect what the auditors and quality assurance representatives observe during their interactions at vendor locations. This research proposes to apply the statistical technique of multidimensional scaling (MDS) and the User centered Design (UCD) method of Participatory Design (PD) to …

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Dielectric Properties And Method Of Characterizing Ceramic Powders And Multiphase Composites, Ravi Kiran Kota Dec 2006

Dielectric Properties And Method Of Characterizing Ceramic Powders And Multiphase Composites, Ravi Kiran Kota

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Barium Titanate was the first developed ferroelectric ceramic material and even today it is widely used. It is also a well-known material used for capacitors. The only reason behind a wide range of applications is that barium titanate boasts of high dielectric properties. A phase transition from cubic to tetragonal at normal working temperatures provides enhanced dielectric properties in this electronic material. For any application and design, the most inquired property is the dielectric constant. Predicting the dielectric constant is very much required as it is the pre-requisite. This is the major objective of the present work. To estimate the …

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Development Of A Cellular Fiber Spinning Technology For Regenerative Medicine, Willie Jones Dec 2006

Development Of A Cellular Fiber Spinning Technology For Regenerative Medicine, Willie Jones

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In order to prove that our textile hollow fiber spinning apparatus was adequate for cellular encapsulation, we confirmed the viability and metabolic activity of green fluorescent protein (GFP) labeled bovine mammary epithelial cells (MAC-Ts) that were encapsulated in either the wall or lumen of alginate fibers. After a 21 day in vitro macroscopic evaluation, no decrease in fluorescence was observed; and it was determined that MAC-Ts encapsulated under both methods produced lactic acid and consumed glucose. Histomorphological analyses revealed that the diameter of the MAC-Ts increased under both encapsulation scenarios, with little to no evidence of cell cluster propagation. Based …

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Modeling Of The Transient Behavior Of Heat Pipes With Room-Temperature Working Fluids, Pascal Brocheny Dec 2006

Modeling Of The Transient Behavior Of Heat Pipes With Room-Temperature Working Fluids, Pascal Brocheny

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The heat pipe is a capillary-driven and two-phase flow device, capable of transporting and converting large amounts of energy with minimal losses. As a means of thermal management, uses of heat pipe technology not only include thermal control of satellites and spacecrafts in aerospace applications, but also the cooling of electronic components for ground applications. Recently, there has been a flourishing interest in exploring the use of heat pipe technology in the automotive field. However, in many thermal control applications, heat pipes using room-temperature working fluids, such as water or ammonia, with operating temperatures between 200 K (-73ºC) and 550 …

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Investigation Of Flow And Microstructure In Rheometric And Processing Flow Conditions For Liquid Crystalline Pitch, Santanu Kundu Dec 2006

Investigation Of Flow And Microstructure In Rheometric And Processing Flow Conditions For Liquid Crystalline Pitch, Santanu Kundu

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A fundamental understanding of flow and its influence on the microstructure is required to obtain carbon materials with desired properties. The objective of this research was to investigate the flow and microstructural behavior of a synthetic mesophase pitch (AR-HP) in rheometric and processing flow conditions. In addition, simulation studies were performed to establish a frame work for modeling the flow behavior of this complex material in different flow situations.
The steady-shear viscosities obtained from a cone-plate rheometer during increasing rate-sweep experiments exhibited a shear-thinning region (Region I) with a slope of about -0.2 and a plateau (Region II) region. The …

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Use Of Personas For User Interface Design: Results Of Field And Experimental Studies , Pallavi Dharwada Dec 2006

Use Of Personas For User Interface Design: Results Of Field And Experimental Studies , Pallavi Dharwada

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Persona is a fictitious user serving as a role model for designers, helping them make difficult decisions from the users' perspective during the interface design process. This concept, which was introduced by Alan Cooper in 1999, has been found to be a powerful tool for engaging the designers with the users. Although personas do not replace the rich data acquired through user testing, they enhance the interface development process by focusing the designers' attention on the target user until the interface qualifies for testing. Recognizing the benefits of persona, many companies, including the Fortune 500 have embraced this concept as …

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Best Practices For Developing The Engineer's Estimate, Karl Niedzwecki Dec 2006

Best Practices For Developing The Engineer's Estimate, Karl Niedzwecki

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The research project 'Best Practices for Developing the Engineering Estimate' was executed by Clemson University on behalf of the South Carolina Department of Transportation (SCDOT). The primary objective of this research project was to investigate the strengths and weaknesses of two types of estimating methods being utilized today by state department of transportations (DOT) nationwide. These two types of estimating methods are the unit cost line item approach, which the SCDOT utilizes, and the cost-based estimating approach. This research report identifies accuracy obtained, resources expended, and methodologies utilized when implementing either type of estimating approach. This was done so the …

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Simulation And Characterization Of Tire Nonuniformity-Induced Steering Nibble Vibrations Through Integrated Subsystems Modeling, Derek Mangun Dec 2006

Simulation And Characterization Of Tire Nonuniformity-Induced Steering Nibble Vibrations Through Integrated Subsystems Modeling, Derek Mangun

All Theses

Periodic force variations produced by nonuniform tire/wheel assemblies are known root causes of torsional steering wheel vibrations known as 'nibble'. Previous studies have sought to investigate this issue through modeling or experimentation involving the entire vehicle or specific subsystems, however a direct link between objectively measured tire force variations and the vibration levels perceived by vehicle occupants has yet to be established. Analytical models of a nonuniform tire, double-wishbone suspension system, and rack and pinion steering system are sourced from literature and integrated into a single subsystem-level model validated against experimental data obtained as part of a collaborative effort. The …

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Nonlinear Control Techniques For Robot Manipulators, Nitendra Nath Dec 2006

Nonlinear Control Techniques For Robot Manipulators, Nitendra Nath

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This Masters thesis describes the design and implementation of control strategies for the following topics of research: i) Whole Arm Grasping Control for Redundant Robot Manipulators, ii) Neural Network Grasping Controller for Continuum Robots and, iii) Coordination Control for Haptic and Teleoperator Systems.

An approach to whole arm grasping of objects using redundant robot manipulators is presented. A kinematic control which facilitates the encoding of both the end-effector position, as well as body self-motion positioning information as a desired trajectory signal for the manipulator joints is developed.

An approach is presented to whole arm grasping control for continuum robots. The …

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Tribological Systems For The Evaluation Of Supercritical Carbon Dioxide Sterilized Ultra-High Molecular Weight Polyethylene, John Desjardins Dec 2006

Tribological Systems For The Evaluation Of Supercritical Carbon Dioxide Sterilized Ultra-High Molecular Weight Polyethylene, John Desjardins

All Dissertations

Polymeric biomaterials are especially susceptible to changes in mechanical and surface material properties as a result of sterilization processes that involve heat, moisture and/or irradiation. This is problematic for polymeric materials used in total joint replacement bearings, as these constructs must retain their superior mechanical and tribological properties over their expected 10-20 years of implantation. A younger more active patient population has now exacerbated this longevity issue with service lifetimes of 20+ years now being expected. Supercritical phase carbon dioxide (SC-CO2) is an industrial solvent that has shown great promise as a sterilizing agent in the food industry. Recently, SC-CO2 …

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Developing A Benchmark Suite For The Evaluation Of Orientation Sensors, Kelly Waller Dec 2006

Developing A Benchmark Suite For The Evaluation Of Orientation Sensors, Kelly Waller

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This paper examines the problem with the lack of standardization through which MEMS orientation sensors are evaluated. These sensors are sold with data sheets that outline their performance, but lack the conditions under which the testing takes place. In this research, a testing apparatus was developed, and testing routines were designed to evaluate the different characteristics of orientation sensors under different motion conditions. Three orientation sensors, each in a different price range, were evaluated with the benchmark suite. The testing apparatus is a turntable that can precisely spin an orientation sensor via a stepper motor, and can record its exact …

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Modeling Long-Term Plutonium Transport In The Savannah River Site Vadose Zone, Deniz Demirkanli Dec 2006

Modeling Long-Term Plutonium Transport In The Savannah River Site Vadose Zone, Deniz Demirkanli

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Improved understanding of flow and radionuclide transport in vadose zone sediments is fundamental to future planning involving radioactive materials. Long-term experiments were conducted at the Savannah River Site (SRS), where a series of lysimeters containing sources of different Pu oxidation states were placed in the shallow subsurface and exposed to the environment for 2 to 11 years. After the experiments, Pu activity concentrations were measured along vertical cores. The distributions were anomalous in nature, with irregular downward migration and unexpected upward migration. Previous studies suggested that surface-mediated, oxidation/reduction (redox) reactions may be responsible for the anomalies. This hypothesis is tested …

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A Robust Conjugate Heat Transfer Methodology With Novel Turbulence Modeling Applied To Internally-Cooled Gas Turbine Airfoils, William York Dec 2006

A Robust Conjugate Heat Transfer Methodology With Novel Turbulence Modeling Applied To Internally-Cooled Gas Turbine Airfoils, William York

All Dissertations

Computational fluid dynamics and heat transfer (CFD) has become a viable, physics-based analysis tool for complex flow and/or heat transfer problems in recent years due, in large part, to rapid advances in computing power. CFD based on the Reynolds-averaged Navier-Stokes (RANS) equations is starting to enter the mainstream design environment in certain industries where rapid and reliable predictive capability is necessary. One such application is the gas turbine industry, where thermal management of airfoils at extremely high temperatures is one of the most critical components in engine design for reliability. The problem is complicated by the need for advanced airfoil …

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Optimizing The Project Team's Contribution To Business Objectives, Chad Rowland Dec 2006

Optimizing The Project Team's Contribution To Business Objectives, Chad Rowland

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The traditional expectations of the project team are for the processes of engineering, procurement, construction, and start-up to be expertly administered. However, these performance criteria can be satisfied yet still not meet the ultimate business needs of the owner. The purpose of this thesis was to determine ways to improve the likelihood of achieving owner's business objectives. Fifty-one questionnaire survey forms were analyzed to obtain data for thirty-three pre-project planning activities. A data analysis concluded with a degree of statistical significance that for thirteen of the thirty-three activities, the more successful projects, as defined by the satisfaction of the business …

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A Cross-Layer Approach To Increase Spatial Reuse And Throughput For Ad Hoc Networks, Steven Boyd Dec 2006

A Cross-Layer Approach To Increase Spatial Reuse And Throughput For Ad Hoc Networks, Steven Boyd

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Ad hoc networks employing adaptive-transmission protocols can alter transmission parameters to suit the channel environment. Channel-access mechanisms are used to govern temporal use of the transmission medium amongst nodes. Effective operation of a channel-access mechanism can improve the ability of an adaptive-transmission protocol to accommodate changing channel conditions. The interoperability of these two mechanisms motivates cross-layer design of adaptive-transmission protocols.
In this thesis we examine the integration of a new channel-access mechanism with a physical-layer adaptive-transmission protocol to create a cross-layer protocol with enhanced capabilities. We derive specific physical-layer measurements which are used to control channel-access behavior in a distributed …

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Using A Spline To Model The Motion Of A 4-Man Fireteam During Building Clearing Exercises, Marshall Werner Dec 2006

Using A Spline To Model The Motion Of A 4-Man Fireteam During Building Clearing Exercises, Marshall Werner

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This paper examines the problem of tracking positions of a fireteam (4-5 men) as they perform building clearing exercises in order to predict future motion od the team. This was done by examining the team as a single entity rather than 4 or 5 separate entities. A team model was used under the assumption that the team stays together as a group and moves in specific patterns. The model chosen for this experiment was a spline curve. This spline curve allowed for movement in straight lines through hallways as well as curving around corners.

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A Comparison Of The Zns(Ag) Scintillation Detector To The Silicon Semiconductor Detector For Quantification Of Alpha Radioactivity In Aqueous Solutions, Jennifer Foster Dec 2006

A Comparison Of The Zns(Ag) Scintillation Detector To The Silicon Semiconductor Detector For Quantification Of Alpha Radioactivity In Aqueous Solutions, Jennifer Foster

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A ZnS(Ag) detector was successfully used in the direct detection of alpha particles from aqueous solutions and the results were compared to the passivated ion implanted planar silicon (PIPS) continuous air monitor (CAM) detector. The ZnS(Ag) detector is recommended for on-line detection of gross alpha radioactivity from high-level liquid waste process streams; however, the detector suffers from limitations due to variations in detection efficiency with alpha energies. The beta and gamma interference did not significantly spillover into the alpha region of interest of the ZnS(Ag) detector which provided absolute detection efficiencies of 7.19 ± 0.13%, 5.37 ± 0.02%, and 4.21 …

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Evaporation Estimation Using A Floating Pan, Michael Klink Dec 2006

Evaporation Estimation Using A Floating Pan, Michael Klink

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Almost all regions in the United States must accurately estimate evaporation to have effective water management programs. The purpose of this study is to develop a better method for measuring evaporation. Lake evaporation along with meteorological data are measured directly from a floating pan. The floating pan is specifically designed to account for one of the most sensitive parameters of evaporation, the water surface temperature, which the design achieves. However, other design factors such as air movement, solar radiation, stability, heat transfer, wave action, water level range, and site location were also taken into consideration. The evaporation measured from the …

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Investigation Of The Effects Of Subgrid-Scale Turbulence On Resolvable-Scale Statistics, Qinglin Chen Dec 2006

Investigation Of The Effects Of Subgrid-Scale Turbulence On Resolvable-Scale Statistics, Qinglin Chen

All Dissertations

The effects of the subgrid-scale (SGS) turbulence on the resolvable-scale statistics and the effects of SGS models on large-eddy simulation (LES) are studied. It is shown that the SGS turbulence evolves the resolvable-scale joint probability density function (JPDF) through the conditional means of the SGS stress, the SGS scalar flux, and their production rate, which must be reproduced by the SGS model for LES to predict correctly the one-point resolvable-scale statistics, a primary goal of LES. This necessary condition is used as the basis for studying SGS physics and for testing SGS models. Theoretical predictions, measurements data obtained in a …

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Stabilization Of Vascular Elastin By Treatment With Tannins, Jason Isenburg Dec 2006

Stabilization Of Vascular Elastin By Treatment With Tannins, Jason Isenburg

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Elastin is an important component of the extracellular matrix that endows cardiovascular tissue with the ability to extend and recoil repetitively. It has been shown that elastin may be vulnerable to enzymatic degradation and calcification in certain pathological cases. As a result, elastin degeneration may be associated with the failure of tissue-derived cardiovascular devices, such as bioprosthetic heart valves, as well as the development and progression of aortic aneurysms, a disease associated with progressive connective tissue degeneration of the arterial wall. Therefore, an elastin stabilizing agent may be beneficial for both applications. As such, our objectives for elastin stabilization are …

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Investigation Into Compatibility Between Repair Material And Substrate Concrete Using Experimental And Finite Element Method, Rashmi Pattnaik Dec 2006

Investigation Into Compatibility Between Repair Material And Substrate Concrete Using Experimental And Finite Element Method, Rashmi Pattnaik

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The failure of concrete repairs is mainly due to improper selection of repair material based on individual repair material properties, without investigating the compatibility between repair material and substrate concrete. In this dissertation the compatibility between eight repair materials and substrate concrete was investigated in three stages. First, individual properties of the repair materials such as setting time, flow, compressive strength, flexural strength, split tensile strength, bond strength, drying shrinkage, freeze-thaw resistance, and permeability, were determined using standard ASTM test procedures. Second, the compatibility was investigated using a composite beam under third point loading. Third, the correlation of repair material …

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Modeling And Simulation Of Friction-Limited Continuously Variable Transmissions, Nilabh Srivastava Dec 2006

Modeling And Simulation Of Friction-Limited Continuously Variable Transmissions, Nilabh Srivastava

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Over the last few decades, a lot of research effort has increasingly been directed towards developing vehicle transmissions that accomplish the government imperatives of increased vehicle efficiency and lower exhaust (greenhouse gaseous) emissions. These exhaust emissions can be regulated or lowered by increasing the fuel economy of a vehicle, and CVTs (continuously variable transmissions), indubitably, play a crucial role in this plan to improve the fuel economy. A continuously variable transmission is an emerging automotive transmission technology that offers a continuum of gear ratios between desired limits. A CVT offers numerous advantages over the conventional multi-step gear transmissions such as …

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Channel-Access And Routing Protocols For Wireless Ad Hoc Networks With Directional Antennas, Arvind Swaminathan Dec 2006

Channel-Access And Routing Protocols For Wireless Ad Hoc Networks With Directional Antennas, Arvind Swaminathan

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Medium-access control (MAC) and multiple-hop routing protocols are presented that exploit the presence of directional antennas at nodes in a wireless ad hoc network. The protocols are designed for heterogeneous networks in which an arbitrary subset use directional antennas. It is shown that the new protocols improvement the network`s performance substantially in a wide range of scenarios.
A new MAC protocol is presented that employs the RTS/CTS mechanism. It accounts for the constraints imposed by a directional antenna system, and it is designed to exploit the capabilities of a directional antenna. It is shown that the receiver blocking problem is …

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