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Articles 2251 - 2280 of 2584

Full-Text Articles in Engineering

Human Microvasculature Fabrication Using Thermal Inkjet Printing Technology, Xiaofeng Cui Dec 2008

Human Microvasculature Fabrication Using Thermal Inkjet Printing Technology, Xiaofeng Cui

All Dissertations

The current tissue engineering paradigm is that successfully engineered thick tissues must include vasculature. As biological approaches alone such as VGEF have fallen short of their promises, one may look for an engineering approach to build microvasculature. With the advent of cell printing, one may be able to build precise human microvasculature with suitable bio-ink. Human Microvascular Endothelial Cells (HMVEC) and fibrin were studied as bio-ink for microvasculature construction. Endothelial cells are the only cells to compose the human capillaries and also the major cells of blood vessel intima layer. Fibrin has been already widely recognized as tissue engineering scaffold …

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Optimal Maintenance Crew Composition And Enhancement Of Crew Productivity, Robert Schober Dec 2008

Optimal Maintenance Crew Composition And Enhancement Of Crew Productivity, Robert Schober

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The South Carolina Department of Transportation (SCDOT) dedicates a large portion of its budget and other resources to the maintenance of the State's transportation infrastructure. In order to maximize the efficiency and productivity of the State's highway maintenance workforce, the SCDOT partnered with Clemson University to research the performance of these maintenance crews. The goal of this research is to identify optimal crew compositions, if possible, and to suggest potential crew productivity enhancement methods.
Data was collected from the SCDOT Highway Maintenance Management System (HMMS) and crew rankings were developed based on several pre-determined performance criteria. These rankings were then …

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Analysis Of In-Flight Vibration For A Turbo Propeller Aircraft, Kyle Dunno Dec 2008

Analysis Of In-Flight Vibration For A Turbo Propeller Aircraft, Kyle Dunno

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A data recorder was utilized to record in-flight vibration of a turbo propeller aircraft. The data recorded produced power spectral density (PSD) profiles which are currently used in laboratory settings to drive vibration tables in order to simulate a particular vehicle type. Overall Grms values from the averaged data were then statistically compared to published standards and other studies to determine if there were differences in overall Grms values.
The data recorder was rigidly mounted to the cargo area of the turbo propeller aircraft. Thirty flights were recorded which varied in flight time from less than one hour to greater …

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Circuit Modules For Six-Port Reflectometer On Chip, Chaojiang Li Dec 2008

Circuit Modules For Six-Port Reflectometer On Chip, Chaojiang Li

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Broadband signal generator is an indispensable module for broadband Six-Port Reflectometer (SPR). To integrate a whole SPR system on a chip, the source must be compact. In this thesis, a three-stage voltage-controlled oscillator (VCO), using two parallel weak invertor-chain oscillators and sense amplifiers, is proposed and designed in a 0.13 µm CMOS process. These two parallel weak inverter-chain oscillators extend the low frequency operating range and the sense amplifiers expand the high frequency operation. The measurement results show that the oscillator can be tuned from 430 MHz to 12 GHz, which satisfies the targeted SPR operating frequency range.
In order …

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Optimal And Heuristic Resource Allocation Policies In Serial Production Systems, Ramesh Arumugam Dec 2008

Optimal And Heuristic Resource Allocation Policies In Serial Production Systems, Ramesh Arumugam

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We have studied the optimal server allocation policies for a tandem queueing system under different system settings. Motivated by an industry project, we have studied a two stage tandem queueing system with arrival to the system and having two flexible servers capable of working at either of the stations. In our research, we studied the system under two different circumstances: modeling the system to maximize throughput without cost considerations, modeling the system to include switching and holding costs along with revenue for finished goods. In the maximizing throughput scenario, we considered two different types of server allocations: collaborative and non-collaborative. …

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The Effect Of Montmorillonite Nanoclay On Mechanical And Barrier Properties Of Mung Bean Starch Films, Bianca Stiller Dec 2008

The Effect Of Montmorillonite Nanoclay On Mechanical And Barrier Properties Of Mung Bean Starch Films, Bianca Stiller

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Starch is an interesting biodegradable polymer due to its excellent film forming properties, availability, and low cost. On the other hand, starch films are often limited by their poor mechanical properties, and water resistance. The addition of montmorillonite clays have improved these properties in both petroleum and biodegradable films.
The objective of the research was to determine the effect of montmorillonite clay on the mechanical and barrier properties on mung bean starch films.
The addition of 5% clay yielded the optimum balance between mechanical and barrier properties of these composite films with improved tensile strength (TS) of 20.8763± 0.789 MPa, …

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Computational Analysis Of Input-Shaping Control Of Microelectromechanical Mirrors, Thomas Starling Dec 2008

Computational Analysis Of Input-Shaping Control Of Microelectromechanical Mirrors, Thomas Starling

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Advances in micromachining technology have enabled the design and development of high performance microelectromechanical systems (MEMS). There is a pressing need for control techniques that can be used to improve the dynamic behavior of MEMS such as the response speed and precision. In MEMS applications, open-loop control is attractive as it computes a priori the required system input to achieve desired dynamic behavior without using feedback, thus eliminating the problems associated with closed-loop MEMS control. While the input-shaping control is attractive due to its simplicity, the effectiveness of this control approach depends on the accuracy of the model that is …

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P-M Characteristics Of Reinforced Concrete Sections, Paul Johnson Dec 2008

P-M Characteristics Of Reinforced Concrete Sections, Paul Johnson

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This manuscript presents two parametric studies which were performed to evaluate a provision which originated in the 1994 Uniform Building Code (UBC). This provision states that if gravity-induced axial loads carried by a reinforced concrete member are greater than 35% of the pure axial load-carrying capacity (Po) of that member, then the member cannot be used as part of the lateral force resisting system (LRFS). Along with the UBC provision, the Structural Engineers Association of California's (SEAOC) Blue Book states that the value of 0.35Po corresponds to the level of axial load representing a balanced state of strain, i.e., the …

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Finite Element Analysis Of Carbon Fiber Composite Ripping Using Abaqus, Joy Pederson Dec 2008

Finite Element Analysis Of Carbon Fiber Composite Ripping Using Abaqus, Joy Pederson

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An energy dissipation system is proposed for use on consumer passenger automotive vehicles and auto racing stock cars. This system will be utilized to protect the occupants from frontal impacts with stationary or near stationary objects. The system will be affixed to the front of the car's primary structure. It is proposed to replace the traditional steel bumper currently in use. This system will not increase the weight of the car, nor will it adversely affect the aerodynamics of the body. The system will improve the crashworthiness of the vehicle. Advanced composites will be the primary sacrificial element in the …

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An Integrated Routing And Distributed Scheduling Approach For Hybrid Ieee 802.16e Mesh Networks For Vehicular Broadband Communications, Rahul Amin Dec 2008

An Integrated Routing And Distributed Scheduling Approach For Hybrid Ieee 802.16e Mesh Networks For Vehicular Broadband Communications, Rahul Amin

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An integrated routing and distributed scheduling approach for fast deployable IEEE 802.16e networks is presented where distributed base stations with dual radios form a mesh backhaul and subscriber stations communicate through these base stations. The mesh backhaul is formed via an IEEE 802.16e mesh mode radio on each base station, while the subscriber stations communicate with base stations via PMP mode radios. The proposed routing scheme divides the deployed network into several routing zones. Each routing zone contains several base stations that form the mesh backhaul with one base station equipped with either a fiber, satellite or any other point-to-point …

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Transmission Error Analysis And Avoidance For Ieee 802.15.4 Wireless Sensors On Rotating Structures, Jobin Jacob Dec 2008

Transmission Error Analysis And Avoidance For Ieee 802.15.4 Wireless Sensors On Rotating Structures, Jobin Jacob

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Wireless sensors are increasingly adopted in manufacturing and vehicular systems for monitoring critical components under continuous operation. Many such components move rapidly and frequently in metallic containments with challenging radio propagation characteristics.
For wireless sensors mounted on rotating structures, previous studies identified an eminent increase in packet transmission errors at higher rotation speeds. Such errors were found to occur at specific locations around the rotating spindle's periphery and such locations depended sensitively on sensor location and surrounding geometry. This thesis presents a systematic study of the expected packet error rates due to such errors, and analytically derives the first transmission …

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Development Of A Quadrotor Testbed For Control And Sensor Development, Abhishek Bhargava Dec 2008

Development Of A Quadrotor Testbed For Control And Sensor Development, Abhishek Bhargava

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A quadrotor is an under actuated unmanned aerial vehicle (UAV) which uses thrust from four rotors to provide six degrees of freedom. This thesis outlines the development of a general purpose test bed that can be used for sensor and control algorithm development. The system includes the means to simulate a proposed controller and then a hardware in the loop implementation using the same software. The test bed was assembled and verified with a linear controller for both attitude and position control using feedback from an IMU (Inertial measurement Unit) and a Global Position System (GPS) sensor.
The linear controller …

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Synchrophasor's Application In State Estimation, Linwood Ross Dec 2008

Synchrophasor's Application In State Estimation, Linwood Ross

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This thesis presents an investigation into the effect of synchrophasor measurements on the accuracy of a state estimator. Two state estimation algorithms have been developed in Matlab and tested on several systems. The first state estimator is the traditional non-linear estimator that is currently being used by most utilities. The second estimator is a hybrid linear state estimator. A bad data detection algorithm has been developed as well to determine the effect of synchrophasor measurements in bad data detection. A total of seven different systems are used for testing the proposed algorithms. Six systems are used in testing the bad …

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Analysis Of Speed-Related Crashes Using Event Data Recorder Data, Swathi Korpu Dec 2008

Analysis Of Speed-Related Crashes Using Event Data Recorder Data, Swathi Korpu

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Safety in general is defined as 'the absence of unintended harm to living creatures or inanimate objects' (Evans, 2004). Traffic safety is measured in terms of motor vehicle crashes. A crash is an unplanned event which results in either fatality, or injury or property damage. Of all the factors that contribute to a crash, speed is a major issue, as more than 31 percent of all fatal crashes involve speeding (NHTSA, 2007). The speed-safety relationship can be determined by knowing the effect of speed on the frequency and severity of crashes. The relationship between speed and frequency of crashes is …

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'Fabrication And Characterization Of Polymer Blends And Composites Derived From Biopolymers', Suraj Sharma Dec 2008

'Fabrication And Characterization Of Polymer Blends And Composites Derived From Biopolymers', Suraj Sharma

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This research focuses on fabricating blends and composites from natural polymers especially from proteins and natural epoxy, and describing the properties of plastics made from them. Specifically, plastic samples from partially denatured feathermeal and bloodmeal proteins, derived from the animal co-products (rendering) industry, were successfully produced through a compression molding process. The modulus (stiffness) of the material obtained was found to be comparable with that of commercial synthetic materials, such as polystyrene, but was found to have lower toughness characteristics, which is a common phenomenon among plastics produced from animal and plant proteins. Therefore, this study explored blending methods for …

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Real-Time Automatic Linear Feature Detection In Images, Guang Zeng Dec 2008

Real-Time Automatic Linear Feature Detection In Images, Guang Zeng

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Linear feature detection in digital images is an important low-level operation in
computer vision that has many applications. In remote sensing tasks, it can be used
to extract roads, railroads, and rivers from satellite or low-resolution aerial images,
which can be used for the capture or update of data for geographic information and
navigation systems. In addition, it is useful in medical imaging for the extraction of
blood vessels from an X-ray angiography or the bones in the skull from a CT or MR
image. It also can be applied in horticulture for underground plant root detection in
minirhizotron images. …

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Characterization Of Vascular Smooth Muscle Cell Mechanical And Frictional Properties Using Atomic Force Microscopy, Jason Hemmer Dec 2008

Characterization Of Vascular Smooth Muscle Cell Mechanical And Frictional Properties Using Atomic Force Microscopy, Jason Hemmer

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A working hypothesis within the Laboratory of Vascular Research is that mechanical loading on vascular smooth muscle cells (VSMCs), especially due to solid contact from endovascular devices, contributes to the development of restenosis. In order to better understand the role of mechanical loading on VSMCs in vascular disease development, it is imperative to understand the mechanical properties of VSMCs themselves. To measure the viscoelastic and frictional properties of living VSMCs in an in vitro setting, an atomic force microscope (AFM) was utilized, thereby allowing for mechanical testing of living cells in a fluid environment. In the first phase of research, …

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Effect Of Clinically Relevant Mechanical Forces On Smooth Muscle Cell Response In Model Of Balloon Angioplasty, Kara Acampora Dec 2008

Effect Of Clinically Relevant Mechanical Forces On Smooth Muscle Cell Response In Model Of Balloon Angioplasty, Kara Acampora

All Dissertations

Restenosis remains a common problem affecting the patency of endovascular intervention such as balloon angioplasty and stent placement as treatments for atherosclerosis. Denudation of the endothelial layer and the increased injury from balloon deployment can cause phenotypic changes in surrounding vascular smooth muscle cells (SMCs) in vivo. The presented work modeled this mechanical environment in vitro to investigate the role of the altered mechanical environment on the phenotypic response of SMCs. Through the system design and CFD channel characterization, a six-independent-channel system providing low oscillating wall shear stress (WSS) was manufactured to apply concurrent shear and tensile forces with uniform …

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Aperture Coupling And Penetration In Various Configurations, Jason Keen Dec 2008

Aperture Coupling And Penetration In Various Configurations, Jason Keen

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The problem of a slot in a perfectly conducting surface is addressed for a variety of configurations using both integral equation and transmission line techniques. The use of Bethe hole theory to model short slots is discussed and utilized where appropriate. Primary problems of discussion are a slot array, wires coupling through slots in a ground plane, and wires coupling through slots in a bent ground plane. Additionally, the use of the extended BLT formulation for incorporation of slot effects in a transmission line problem is addressed. In this manuscript, the work of Bethe is extended to include cross-aperture coupling …

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Modeling And Control Of Piezoactive Micro And Nano Systems, Saeid Bashash Dec 2008

Modeling And Control Of Piezoactive Micro And Nano Systems, Saeid Bashash

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Piezoelectrically-driven (piezoactive) systems such as nanopositioning platforms, scanning probe microscopes, and nanomechanical cantilever probes are advantageous devices enabling molecular-level imaging, manipulation, and characterization in disciplines ranging from materials science to physics and biology. Such emerging applications require precise modeling, control and manipulation of objects, components and subsystems ranging in sizes from few nanometers to micrometers. This dissertation presents a comprehensive modeling and control framework for piezoactive micro and nano systems utilized in various applications.
The development of a precise memory-based hysteresis model for feedforward tracking as well as a Lyapunov-based robust-adaptive controller for feedback tracking control of nanopositioning stages are …

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Development And Characterization Of Moisture- And Heat- Activated Oxygen Scavenging Nanoparticle, Youngjae Byun Dec 2008

Development And Characterization Of Moisture- And Heat- Activated Oxygen Scavenging Nanoparticle, Youngjae Byun

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Alpha-tocopherol and a transition metal, iron, mixture was evaluated as a possible oxygen scavenger. The effects of moisture, amount of transition metal, and thermal processing on oxygen scavenging capability were also investigated. Results showed that alpha-tocopherol and transition metal had 6.72 cc oxygen per gram of oxygen scavenging capacity and 0.11 cc oxygen per gram per day of oxygen scavenging rate.
Nanoencapsulation technology was adopted for the possible oxygen scavenging activation system. Alpha-tocopherol-loaded poly caprolactone (PCL) nanoparticles were prepared by oil in water (O/W) emulsion solvent evaporation with ultrasonification. The effects of PCL concentration, solvent in oil phase, and ultrasonification …

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Experimental And Modeling Studies For Optimizing Flocculant-Aided Sediment Retention Ponds, Byung Joon Lee Dec 2008

Experimental And Modeling Studies For Optimizing Flocculant-Aided Sediment Retention Ponds, Byung Joon Lee

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Attempts to control sediment-containing runoff and associated water quality problems have involved the establishment of many small to medium sediment retention ponds and the injection of nonionic and anionic polyacrylamide (PAM) flocculants to enhance colloid removal. However, to date use has been driven more by practicing engineers and trial-and-error approaches than by logical and consistent design approaches. Therefore, the purpose of this research was to optimize colloidal clay removal in PAM-aided sediment retention ponds by applying experimental and theoretical methodologies.
Initially, simple measurement techniques for the molecular weight (MW) and charge density (CD) of various PAMs were tested and their …

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Vascular Tissue Engineering: The Creation Of Living, Non-Thrombogenic, Functional Blood Vessels Based On Elastin Scaffolds, Aditee Kurane Dec 2008

Vascular Tissue Engineering: The Creation Of Living, Non-Thrombogenic, Functional Blood Vessels Based On Elastin Scaffolds, Aditee Kurane

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Cardiovascular diseases are the leading cause of death worldwide. Blood vessel replacement is a common treatment for vascular diseases such as atherosclerosis, restenosis and aneurysm, with over 300,000 bypass procedures performed each year. However, vein grafts are limited due to their availability. Although synthetic vascular replacements have been successful for large diameter arteries, they have shown minimal success in arteries with diameters <6mm. This is because most synthetic materials induce thrombus formation which, within a few months of implantation, causes failure of the vascular graft due to occlusion. Tissue engineering is a promising approach to the fabrication of non-thrombogenic vascular grafts, but a reliable and expandable cell source for tissue-engineered vascular graft (TEVG) has not been established.
The work presented here is motivated by the current unavailability of an ideal tissue engineered blood vessel replacement. Our overall goal is to create a living tissue engineered vascular graft that is biodegradable, non-thromobogenic, presents low antigenicity and …

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Ecm Stabilization Strategies For Bioprosthetic Heart Valves For Improved Durability, Devanathan Raghavan Dec 2008

Ecm Stabilization Strategies For Bioprosthetic Heart Valves For Improved Durability, Devanathan Raghavan

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Abstract
Approximately 85,000 heart valve replacement surgeries are performed every year in United States and about 300,000 surgeries worldwide. It is estimated that half of them are mechanical valve replacements and the other half bioprosthetic valve replacements. The use of bioprosthetic heart valves is slowly increasing. Bioprosthetic heart valves are made from porcine aortic valves or bovine pericardium. Commercially these bioprostheses are currently crosslinked using glutaraldehyde (GLUT) to prevent tissue degradation and reduce tissue antigenicity. GLUT crosslinks these bioprostheses by stabilizing the collagen present in the tissue via a Schiff base reaction of the aldehyde with the hydroxylysine / lysine …

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Effective Vr: Interplay Of Presence, Perception, Fidelity And Transfer Effects In The Development Of Inspection Training Simulators, Sajay Sadasivan Dec 2008

Effective Vr: Interplay Of Presence, Perception, Fidelity And Transfer Effects In The Development Of Inspection Training Simulators, Sajay Sadasivan

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Increased emphasis on aircraft inspection to ensure aviation safety has resulted in the need for a better trained workforce of aircraft maintenance personnel. Aircraft inspection is mostly visual in nature. Thus it has led to the development of computer simulators to train human inspectors performing the inspection task. However, the lack of immersion and interaction in such simulators has led to limited effectiveness and adoption. Using advances in graphics and virtual reality technology, there is an increase the sense of involvement in using these simulators. Though technology is available to provide higher levels of immersion, it is expensive. It is …

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Computional Modeling Of Precision Molding Of Aspheric Glass Optics, Balajee Ananthasayanam Dec 2008

Computional Modeling Of Precision Molding Of Aspheric Glass Optics, Balajee Ananthasayanam

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In this dissertation, research in two parallel directions is presented; the first involves the prediction of the final size and shape of a glass lens during a precision glass lens molding process and the second introduces a method to compute and quantify the importance of higher order terms in fracture mechanics for different modes of fracture.
The process of precision lens molding has received attention in recent years due to its potential to mass produce aspherical lenses. Aspherical lenses have significantly better optical properties and conventional lens making techniques are limited to manufacturing of spherical lenses only. The conventional technique …

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Design Of An Ic Controller For A Light Emitting Diode Stack, Andrew Alleman Oct 2008

Design Of An Ic Controller For A Light Emitting Diode Stack, Andrew Alleman

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An integrated circuit (IC) powering up to nine series connected high brightness light emitting diodes (HBLED's) was designed. The LED's are split into three groups by color (RGB), and the average current through each group is independently varied using a separate microprocessor in conjunction with the IC controller. Integrated comparators compare the voltage across each LED group with internally generated references to check for open or short circuit diodes. In the event of an open circuit failure, the IC controller switches in a SCR to bypass the open circuit device thus maintaining light output at reduced intensity.
Silvaco CAD tools …

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Effect Of Nitrification On Lead Corrosion In Chloraminated Distribution Systems, Michael Shade Sep 2008

Effect Of Nitrification On Lead Corrosion In Chloraminated Distribution Systems, Michael Shade

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Water treatment facilities have been shifting from using chlorination to chloramination as a primary disinfectant since 2004, when the EPA enacted the Disinfectants/Disinfection By-Products (D/DBP) Rule mandating the decrease of DBPs. After the switch to chloramination, an unexpected lead concentration increase was detected in the Washington, D. C., and Greenville, NC water systems. These increases may be associated with the switch from chlorination to chloramination. Decomposition of chloramines results in higher ammonia loading to drinking water distribution systems, which may increase nitrification. Nitrifying bacteria may facilitate lead corrosion via two mechanisms: use of nitrite or nitrate as an alternative electron …

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Modeling Of Space-Charge-Limited Current Injection Incorporating An Advanced Model Of The Poole-Frenkel Effect, Satoshi Takeshita Sep 2008

Modeling Of Space-Charge-Limited Current Injection Incorporating An Advanced Model Of The Poole-Frenkel Effect, Satoshi Takeshita

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The current flow due to Space-Charge-Limited (SCL) emission is well known and the associated current-voltage power law relationship can be observed in many materials, particularly in insulators and semiconductors. Under an applied field, the space-charge effect occurs due to the carrier injection, and the resulting current due to the presence of the space-charge effect is referred to as SCL current. In the SCL current theory, the presence of localized traps in a material has a significant effect on the transport of injected carriers; however, in the first order SCL model, the trap barrier height is assumed to be constant for …

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Ultracapacitor Assisted Powertrains: Modeling, Control, Sizing, And The Impact On Fuel Economy, Dean Rotenberg Sep 2008

Ultracapacitor Assisted Powertrains: Modeling, Control, Sizing, And The Impact On Fuel Economy, Dean Rotenberg

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This thesis investigates possible fuel economy gains attainable by a combination of high-power density ultracapacitors (also called supercapacitors) and an induction motor integrated into a conventional vehicle powertrain for power assistance.
Periods of quick acceleration require a much higher power output from an automobile than what is encountered under more typical driving conditions. A simple kinetic energy calculation can show that accelerating a 2000 kg vehicle (roughly the size of a Ford Explorer SUV) from 0 to 60 mph in 10 seconds requires almost 70 kW of power, in addition to the power needed to overcome road and air drag …

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