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Articles 2371 - 2400 of 2512

Full-Text Articles in Engineering

A Hydraulic Actuated Thermal Management System For Large Displacement Engine Cooling Systems, Peyton Frick Aug 2007

A Hydraulic Actuated Thermal Management System For Large Displacement Engine Cooling Systems, Peyton Frick

All Theses

The performance of automotive cooling systems can be improved by replacing the traditional mechanically driven radiator fan and water pump assemblies with computer controlled components. The introduction of electric servo-motors to drive the cooling components can improve temperature tracking, which should increase fuel efficiency and decrease tailpipe emissions. However, the power requirement for these electric motors increases with greater cooling demands if the radiator surface area remains constrained. For heavy-duty applications, where engines are subjected to significant cooling loads, electric motors may become impractical due to their increased size and power requirements; in these situations, hydraulic-based components are advantageous due …

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Comparison Of Effectiveness Of Roadway Design Treatments For Transitioning From Rural Areas To Urban Areas Using A Driving Simulator, Candice Hein Aug 2007

Comparison Of Effectiveness Of Roadway Design Treatments For Transitioning From Rural Areas To Urban Areas Using A Driving Simulator, Candice Hein

All Theses

Traffic fatalities are a leading cause of death in the United States. Rural roads are especially hazardous as they account for 60 percent of all traffic fatalities in the United States. Three main reasons for the rural road problems are high speeds, low volumes, and reduced driver awareness. This is particularly problematic where these roads navigate through communities requiring reduced speeds. Drivers who aren't alert and are driving too fast often miss the reduced speed warning signs and often don't slow until after they have entered the community. Therefore, engineers must do something to the design of the roadway environment …

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Registration Using Graphics Processor Unit, Koushik Aravalli Aug 2007

Registration Using Graphics Processor Unit, Koushik Aravalli

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Data point set registration is an important operation in coordinate metrology. Registration is the operation by which sampled point clouds are aligned with a CAD model by a 4X4 homogeneous transformation (e.g., rotation and translation). This alignment permits validation of the produced artifact's geometry. State-of-the-art metrology systems are now capable of generating thousands, if not millions, of data points during an inspection operation, resulting in increased computational power to fully utilize these larger data sets. The registration process is an iterative nonlinear optimization operation having an execution time directly related to the number of points processed and CAD model complexity. …

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Simulation Of A Backrest Moment Test For An Automotive Front Seat Using Nonlinear Contact Finite Element Analysis , Abhinand Chelikani Aug 2007

Simulation Of A Backrest Moment Test For An Automotive Front Seat Using Nonlinear Contact Finite Element Analysis , Abhinand Chelikani

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Computer aided engineering and finite element simulation are essential in order to predict accurately the safety performance of automotive structures in an event of crash. In this work, finite element simulation is used to evaluate the strength and deflection characteristics of a reference automotive front seat in an event of vehicle rear impact. Understanding the strength-deflection characteristics of front automotive seats during vehicle rear impact is important to ensure the safety function of the seat. The safety function is measured based on a moment test in accordance with government (ECE R17) regulations. Accurate finite element modeling of a reference seat …

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Wind Effects On Monosloped And Sawtooth Roofs, Bo Cui Aug 2007

Wind Effects On Monosloped And Sawtooth Roofs, Bo Cui

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Wind is one of the significant forces of nature that must be considered in the design of buildings. The actual behavior of wind is influenced not only by the surface (or boundary-layer) conditions, but also by the geometry of the building. All sorts of turbulent effects occur, especially at building corners, edges, roof eaves. Some of these effects are accounted for by the wind pressure coefficient. Wind pressure coefficients used in practice have usually been obtained from experimentally by testing models of different type of structures in wind tunnels.
In this study, a series of wind tunnel tests with scale …

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Development And Evaluation Of An Enrichment Culture For Bioaugmentation Of The P-Area Chlorinated Ethene Plume At The Savannah River Site, Elizabeth Wood Aug 2007

Development And Evaluation Of An Enrichment Culture For Bioaugmentation Of The P-Area Chlorinated Ethene Plume At The Savannah River Site, Elizabeth Wood

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The Twin Lakes chlorinated ethene plume at the Department of Energy's
Savannah River Site (SRS) emerges in a wetland in which trichloroethene (TCE) is
completely reduced to ethene and ethane. Novel strains of Dehalococcoides have been
detected from the wetland area. The objectives of this study were 1) to develop an
enrichment culture capable of completely dechlorinating TCE and tetrachloroethene
(PCE) to ethene using samples from the wetland; 2) to evaluate the use of lactate,
emulsified vegetable oil and corn syrup as possible electron donors for biostimulation of
the P-area chlorinated ethene plume at SRS that is not undergoing natural …

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Pursuit-Evasion With Acceleration, Sensing Limitation, And Electronic Counter Measures, Jing-En Pang Aug 2007

Pursuit-Evasion With Acceleration, Sensing Limitation, And Electronic Counter Measures, Jing-En Pang

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Abstract: The use of game theory to analyze the optimal behaviors of both pursuers and evaders originated with Isaac's work at the Rand Corporation in the 1950's. Although many variations of this problem have been considered, published work to date is limited to the case where both players have constant velocities. In this thesis, we extend previous work by allowing players to accelerate. Analysis of this new problem using Newton's laws imposes an additional constraint to the system, which is the relationship between players' velocities and allowed turning radius. We find that analysis of this relationship provides new insight into …

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An In Vitro Evaluation Of Dbm As A Tissue Engineered Scaffold, Stephanie Arnold Aug 2007

An In Vitro Evaluation Of Dbm As A Tissue Engineered Scaffold, Stephanie Arnold

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Over 500,000 bone graft procedures are performed each year in the United States. Bone grafting involves a surgical procedure to replace missing bone. Problems can arise with donor and defect sites during and after surgery, sometimes resulting in poor clinical results. The development and optimization of bone graft substitutes via a tissue engineering approach could markedly improve bone graft surgical outcome. Demineralized bone matrix (DBM), a bone graft material, is currently used in a clinical setting but has variable success rates.
The primary objective of the research presented in this thesis was to assess the cellular activity of D1 mouse …

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Laser-Assisted Synthesis And Optical Properties Of Bismuth Nanorods, Jason Reppert Aug 2007

Laser-Assisted Synthesis And Optical Properties Of Bismuth Nanorods, Jason Reppert

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Bismuth in the bulk form is a semimetal with a rhombohedral structure. It has a small band overlap between the conduction and valence bands and a highly anisotropic electron effective-mass tensor. Thermoelectric materials, in which one of the three dimensions is in the nanometer regime, exhibit unique quantum confinement properties and have generated much interest in recent years. Theoretical investigations have suggested that nanowires with diameters <10 nm will possess a figure-of-merit ZT>2. Prior to this research, it has been shown by the Dresselhaus group at MIT that Bi nanowires with small enough diameters (~50 nm), prepared via the template-method, undergo a transition from a semimetal …

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Performance Of Serial, Matched-Filter Packet Acquisition Algorithms With A Preamble-Sequence Acceptance Criterion, Javier Schloemann Aug 2007

Performance Of Serial, Matched-Filter Packet Acquisition Algorithms With A Preamble-Sequence Acceptance Criterion, Javier Schloemann

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In this thesis, we consider two methods to improve the acquisition performance of a packet radio system that uses serial, matched-filter acquisition: an adaptive acquisition threshold, and an acceptance criterion for the system's preamble sequences. Each packet transmission includes a fixed-length acquisition preamble, and the preamble sequence used in packet transmissions is changed at predetermined times based on a sequence-generation algorithm. It is shown that acquisition performance depends largely on the sidelobe energy of the preamble sequence, the acquisition threshold, and the signal-to-noise ratio.
The first method uses a threshold-scaling technique to account for the variation in the signal-to-noise ratio. …

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Advanced Thermal Management For Internal Combustion Engines, Thomas Mitchell Aug 2007

Advanced Thermal Management For Internal Combustion Engines, Thomas Mitchell

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The automotive cooling system has unrealized potential to improve internal combustion engine performance through enhanced coolant temperature control and reduced parasitic losses. Advanced automotive thermal management systems use controllable actuators (e.g., smart thermostat valve, variable speed water pump, and electric radiator fan) in place of conventional mechanical cooling system components to improve engine temperature tracking over most operating ranges. To optimize advanced cooling system performance, the electro-mechanical actuators must work in harmony to control engine temperature. The design and placement of cooling components should also be considered when attempting to maximize the performance.
In this research project, two distinct vehicle …

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Nonlinear Modeling Of The Adsorption-Induced Surface Stress In Piezoelectrically-Driven Microcantilever Biosensors, Mana Afshari Aug 2007

Nonlinear Modeling Of The Adsorption-Induced Surface Stress In Piezoelectrically-Driven Microcantilever Biosensors, Mana Afshari

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Microcantilever-based biosensors are rapidly becoming an enabling sensing technology for a variety of label-free biological applications due to their extreme applicability, versatility and low cost. These sensors operate through the adsorption of species on the functionalized surface of microcantilevers. The adsorption of biological species induces surface stress which originates from the molecular interactions such as adhesion forces of attraction/repulsion, electrostatic forces or the surface charge redistribution of the underlying substrate. This surface stress, consequently, alters the resonance frequency of the microcantilever beam.
This study presents a general framework towards modeling resonance frequency changes induced due to the surface stress arising …

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A Study Of Estimation Techniques And Of Mechatronic System Design And Testing, Brett Castelloe Aug 2007

A Study Of Estimation Techniques And Of Mechatronic System Design And Testing, Brett Castelloe

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This thesis is a collection of two projects that the author worked on during his master's studies at Clemson University. The first project--adaptive camera calibration--involves the design and simulation of an estimator for the calibration parameters of a camera. The second project--basket drive wear testing--includes the design of a test plan for measuring wear on a mechatronic system.

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Transmission Gate Based Dual Rail Logic For Differential Power Analysis Resistant Circuits, Srinidhi Narasimha Char Aug 2007

Transmission Gate Based Dual Rail Logic For Differential Power Analysis Resistant Circuits, Srinidhi Narasimha Char

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Cryptographic devices with hardware implementation of the algorithms are increasingly being used in various applications. As a consequence, there is an increased need for security against the attacks on the cryptographic system. Among various attack techniques, side channel attacks pose a significant threat to the hardware implementation. Power analysis attacks are a type of side channel attack where the power leakage from the underlying hardware is used to eavesdrop on the hardware operation. Wave pipelined differential and dynamic logic (WDDL) has been found to be an effective countermeasure to power analysis. This thesis studies the use of transmission gate based …

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Analyzing Relationships Between Lightning And Rain In Order To Improve Estimation Accuracy Of Rain , Justin Lapp Aug 2007

Analyzing Relationships Between Lightning And Rain In Order To Improve Estimation Accuracy Of Rain , Justin Lapp

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The remote estimation of rainfall rate R is essential for the aviation industry, agriculture, and food warning. Radar, the current means of R estimation, is not available in much of the world. In addition, this measurement involves a level of inaccuracy. Using lightning to detect rain is a relatively inexpensive alternative to radar systems and can be done from existing satellites. Previous research has revealed correlations between lightning and rain, suggesting either that it is possible to estimate R using lightning, or that it is possible to use it to correct for a portion of the radar inaccuracies. These correlations …

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Approaches To Mitigate The Impact Of Dissolved Organic Matter On The Adsorption Of Synthetic Organic Contaminants By Activated Carbon, Abhishek Yadav Aug 2007

Approaches To Mitigate The Impact Of Dissolved Organic Matter On The Adsorption Of Synthetic Organic Contaminants By Activated Carbon, Abhishek Yadav

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The main objective of this study was to conduct a systematic investigation of various approaches to mitigate the competition of dissolved organic matter (DOM) on the adsorption of synthetic organic contaminants (SOCs) by activated carbons. TCE and atrazine were selected as the target SOCs because they are known to adsorb in different pore size regions. TCE adsorbs in the primary micropore region (i.e., <10 ) which is inaccessible to the majority of the DOM components, while atrazine adsorbs in the secondary micropore region (i.e., 10-20 ) which is partially accessible to some DOM components. The adsorbents used in this study consisted of four activated carbons (OLC, CRC, F400He, and HD4000ST) and one activated carbon fiber (ACF: ACF10). All sorbents were basic and hydrophobic in nature and represented a set of activated carbons with gradually widening pore size distribution, from the extremely microporous carbons (ACF10 and OLC) to carbons with some amount of mesopores (CRC and F400He) and finally a predominantly mesoporous (HD4000ST) carbon.
Isotherms were performed as single solute and after preloading with a dissolved organic matter (5 mg DOC/L and 20 mg DOC/L) for both TCE and atrazine and using the five activated carbons. Single solute isotherm results showed …

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Fabrication And Characterization Of Cu/4h-Sic Schottky Diodes, Ruth Solomon Aug 2007

Fabrication And Characterization Of Cu/4h-Sic Schottky Diodes, Ruth Solomon

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Copper Schottky contacts to n-type 4H Silicon Carbide with nickel ohmic contacts were fabricated. The electrical and physical characteristics of these Schottky diodes were analyzed and the results are presented. I-V measurements revealed two sets of characteristics, one indicating nearly ideal Schottky behavior and the other exhibiting regions with two barrier heights. The reason for this observed phenomenon was studied and attributed to the in-homogeneity of the Silicon Carbide surface. The I-V and C-V characteristics were used to extract the electrical parameters, which include barrier height, ideality factor, reverse saturation current density, and doping concentration. The measured barrier height was …

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Development Of A Microscopic Moirž Interferometry System, Jeremy Brougher Aug 2007

Development Of A Microscopic Moirž Interferometry System, Jeremy Brougher

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The human tooth is an amazing structure that is worthy of detailed research and analysis. For over half a century, various tests have been conducted to acquire more information about the structural and material properties of dentin, enamel, and the dentin-enamel junction. Unfortunately, variations still exist in the experimental results, even in the most recently collected data. The primary focus of the majority of material property testing on human teeth has been hardness testing utilizing indentation and nanoindentation analysis. However, several limitations still exist with the indentation technique. Thus, the moirŽ fringe analysis method, specifically microscopic moirŽ interferometry, has been …

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Glycosaminoglycan Stabilization Reduces Tissue Buckling In Bioprosthetic Heart Valves, Sagar Shah Aug 2007

Glycosaminoglycan Stabilization Reduces Tissue Buckling In Bioprosthetic Heart Valves, Sagar Shah

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Currently, bioprosthetic heart valves are crosslinked with glutaraldehyde to prevent tissue degradation and to reduce tissue antigenicity. Glutaraldehyde forms stable crosslinks with collagen via a Schiff base reaction of the aldehyde with an amine group of the hydroxylysine/lysine in collagen. However, within a decade of implantation, 20-30% of these bioprostheses will become dysfunctional and over 50% will fail due to degeneration within 12-15 years post-operatively.
Gylcosaminoglycans, a major constituent of valvular tissue, play an important role in maintaining a hydrated environment necessary for absorbing compressive loads, modulating shear stresses, and resisting tissue buckling. One of the disadvantages of glutaraldehyde crosslinking …

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Control Of Nonlinear Mechatronic Systems, Enver Tatlicioglu Aug 2007

Control Of Nonlinear Mechatronic Systems, Enver Tatlicioglu

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This dissertation is divided into four self-contained chapters. In Chapter 1, an adaptive nonlinear tracking controller for kinematically redundant robot manipulators is presented. Past research efforts have focused on the end-effector tracking control of redundant robots because of their increased dexterity over their non-redundant counterparts. This work utilizes an adaptive full-state feedback quaternion based controller developed in [1] and focuses on the design of a general sub-task controller. This sub-task controller does not affect the position and orientation tracking control objectives, but instead projects a preference on the configuration of the manipulator based on sub-task objectives such as the following: …

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Manufacturable Process And Tool For High Performance Metal/High-K Gate Dielectric Stacks For Sub-45 Nm Cmos & Related Devices, Aarthi Venkateshan Aug 2007

Manufacturable Process And Tool For High Performance Metal/High-K Gate Dielectric Stacks For Sub-45 Nm Cmos & Related Devices, Aarthi Venkateshan

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Off state leakage current related power dominates the CMOS heat dissipation problem of state of the art silicon integrated circuits. In this study, this issue has been addressed in terms of a low-cost single wafer processing (SWP) technique using a single tool for the fabrication of high-κ dielectric gate stacks for sub-45 nm CMOS. A system for monolayer photoassisted deposition was modified to deposit high-quality HfO2 films with in-situ clean, in-situ oxide film deposition, and in-situ anneal capability. The system was automated with Labview 8.2 for gas/precursor delivery, substrate temperature and UV lamp. The gold-hafnium oxide-aluminum (Au-HfO2-Al) stacks processed in …

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In Situ Photopolymerized Hydrogels For Enhancing Protein Delivery, Chien-Chi Lin Aug 2007

In Situ Photopolymerized Hydrogels For Enhancing Protein Delivery, Chien-Chi Lin

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In recent years, there has been immense interest in the utilization of photopolymerized hydrogels as carriers for controlled protein delivery and cell scaffolds for tissue engineering applications. Although poly(ethylene glycol) (PEG)-based hydrogels formed from mild photopolymerization methods have been suggested as biocompatible matrices that allow for safely encapsulating biomolecules including proteins, peptides, DNA, and cells, the adverse effects of photopolymerization reactions on the encapsulated proteins have largely been overlooked. In addition, conventional hydrophilic hydrogels fail to effectively control protein delivery rates due to their high permeability. These two problems are critical since the delivery of protein therapeutics from hydrogel matrices …

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Nonlinear Control Strategies For Advanced Vehicle Thermal Management Systems, Mohammad Salah Aug 2007

Nonlinear Control Strategies For Advanced Vehicle Thermal Management Systems, Mohammad Salah

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Advanced thermal management systems for internal combustion engines can improve coolant temperature regulation and servo-motor power consumption to positively impact the tailpipe emissions, fuel economy, and parasitic losses by better regulating the combustion process with multiple computer controlled components. The traditional thermostat valve, coolant pump, and clutch-driven radiator fan are upgraded with servo-motor actuators. When the system components function harmoniously, desired thermal conditions can be accomplished in a power efficient manner. Although the vehicle's mechanical loads can be driven by electric servo-motors, the power demands often require large actuator sizes and electrical currents. Integrating hydraulically-driven actuators in the cooling circuit …

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Nonlinear Vibration And Frequency Response Analysis Of Nanomechanical Cantilever Beams, Seyed Nima Mahmoodi Aug 2007

Nonlinear Vibration And Frequency Response Analysis Of Nanomechanical Cantilever Beams, Seyed Nima Mahmoodi

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Microcantilevers are one the most commonly utilized microelectromechanical systems in a variant of the ultra-precise scanning and characterization application. Of particular interest, the problem of vibrations of microcantilevers has recently received considerable attention due to its application in several nanotechnological instruments such as atomic force microscopy, nanomechanical cantilever sensors and friction force microscopy. For applications such as these, the problem of coupled flexural-torsional nonlinear vibrations of a piezoelectrically-actuated microcantilever beam is considered in this dissertation. The actuation and sensing are both facilitated through bonding a piezoelectric layer (here, ZnO) on the microcantilever surface. The beam is considered to have simultaneous …

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Differentiation Modulation Of Adult Stem Cells In An Adipose System, Aditya Chaubey Aug 2007

Differentiation Modulation Of Adult Stem Cells In An Adipose System, Aditya Chaubey

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The need for soft tissue reconstruction or augmentation has increased continuously over the years. This need is compounded by patients suffering from post-traumatic repair and congenital soft-tissue deformities. All the current options available to treat the soft tissue deformities have inherent difficulties associated with them. Hence, more research is needed to come up with a better solution to this problem which is only going to increase in magnitude. Tissue engineering is a relatively new technique which has the potential to deliver a cell-based device which can overcome the problems associated with traditional therapies. However, before it becomes clinically viable we …

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Thermodynamic Adsorption Studies Of Peptides On Well-Defined, Surface-Confined Polymers With Applications In Membrane Bioseparations, Nripen Singh Aug 2007

Thermodynamic Adsorption Studies Of Peptides On Well-Defined, Surface-Confined Polymers With Applications In Membrane Bioseparations, Nripen Singh

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This dissertation deals with the fundamental studies of peptide adsorption on surfaces modified by surface-confined polymer films, with an application emphasis on membrane bioseparations. In order to understand protein adsorption at a fundamental level, it is important to study the specific residue-level interactions with surfaces. Keeping this idea in view, the present work describes experimental measurements of submolecular-level interaction energies involved in the process of peptide adsorption on polymer films using surface plasmon resonance spectroscopy. Gibbs energy change on adsorption (ΔGad) for tyrosine, phenylalanine, and glycine homopeptides were measured at 25 °C and pH 7 on highly uniform, nanothin polymer …

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Heuristics For Scheduling Reentrant Flexible Job Shops With Sequence-Dependent Setup Times And Limited Buffer Capacities, Jakrawarn Kunadilok Aug 2007

Heuristics For Scheduling Reentrant Flexible Job Shops With Sequence-Dependent Setup Times And Limited Buffer Capacities, Jakrawarn Kunadilok

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This research addresses the problem of scheduling complex job shops with minimizing total weighted tardiness as the objective. The complex job shop is characterized by reentrant job flow through a number of different work centers that contain one or more identical parallel machines. The processing restrictions for the complex job shop include possible non-zero ready times and sequence-dependent setup times. We categorize the complex job shop into two classes: the complex job shop with infinite or finite buffer capacities. We propose three solution methodologies for scheduling the problem with infinite buffer capacities. The first method is the use of mixed …

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Non-Boltzamann Sampling For The Accurate Calculation Of Peptide-Surface Adsorption Free Energy, Feng Wang Aug 2007

Non-Boltzamann Sampling For The Accurate Calculation Of Peptide-Surface Adsorption Free Energy, Feng Wang

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%Abstract
The objectives of this project are 1) the setup and refinement of peptide-SAM surface model systems with explicit water using CHARMM and 2) the development of up-to-date simulation protocols for the accurate calculation of adsorption free energy by incorporating the recent development of non-Boltzmann sampling methods in molecular dynamics and applying it for the calculation of adsorption free energy of short peptides onto well-characterized self-assembled monolayers, which is important for understanding protein/surface interactions.
A software package called the Simulation Template Engine for Peptides at Surfaces (STEPS) was developed for the fulfillment of the first objective. It facilitates the automatic …

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Control Techniques For Robot Manipulator Systems With Modeling Uncertainties, David Braganza Aug 2007

Control Techniques For Robot Manipulator Systems With Modeling Uncertainties, David Braganza

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This dissertation describes the design and implementation of various nonlinear control strategies for robot manipulators whose dynamic or kinematic models are uncertain. Chapter 2 describes the development of an adaptive task-space tracking controller for robot manipulators with uncertainty in the kinematic and dynamic models. The controller is developed based on the unit quaternion representation so that singularities associated with the otherwise commonly used three parameter representations are avoided. Experimental results for a planar application of the Barrett whole arm manipulator (WAM) are provided to illustrate the performance of the developed adaptive controller.
The controller developed in Chapter 2 requires the …

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Biodiesel Forming Reactions Using Heterogneous Catalysis, Yijun Liu Aug 2007

Biodiesel Forming Reactions Using Heterogneous Catalysis, Yijun Liu

All Dissertations

Biodiesel synthesis from biomass provides a means for utilizing effectively renewable resources, a way to convert waste vegetable oils and animal fats to a useful product, a way to recycle carbon dioxide for a combustion fuel, and production of a fuel that is biodegradable, non-toxic, and has a lower emission profile than petroleum-diesel. Free fatty acid (FFA) esterification and triglyceride (TG) transesterification with low molecular weight alcohols constitute the synthetic routes to prepare biodiesel from lipid feedstocks. This project was aimed at developing a better understanding of important fundamental issues involved in heterogeneous catalyzed biodiesel forming reactions using mainly model …

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