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Full-Text Articles in Engineering

Probing The Mechanisms Of Platelet Adhesion To Adsorbed Plasma Proteins, Balakrishnan Sivaraman Aug 2010

Probing The Mechanisms Of Platelet Adhesion To Adsorbed Plasma Proteins, Balakrishnan Sivaraman

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Despite over three decades of research in blood-material interactions, the biomaterials field has been unsuccessful in developing a truly non-thrombogenic biomaterial. This is due to an incomplete understanding of the factors underlying biomaterial-associated thrombosis, especially the mechanisms mediating the interactions of platelets with the adsorbed plasma protein layer(s) on the implant surface. The work presented here is motivated by the primary goal of delineating these mechanisms, and understanding the platelet receptors involved, as well as the domains/amino acid sequences they bind to in the protein molecules.
It is critical to differentiate between the amount and the conformation of the adsorbed …


Modeling Of Cell Transfer And Process-Induced Cell Damage In Laser-Assisted Cell Direct Writing, Wei Wang Aug 2010

Modeling Of Cell Transfer And Process-Induced Cell Damage In Laser-Assisted Cell Direct Writing, Wei Wang

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Laser-assisted cell direct-write technique has been obtaining more and more attention in different biomaterial direct writing applications. A typical laser-assisted cell direct-write process can be divided into two main stages: the cell droplet ejection and cell droplet landing. The objective of this study is to model the cell mechanical profile during the cell droplet ejection and cell landing and further model the cell damage.
The possible cell damage during the droplet ejection process in laser-assisted cell direct writing may come from two different sources: the phase explosion-induced bubble expansion and the thermoelastic stress wave. The bubble expansion-induced stress wave is …


Protocols For Dynamic Spectrum Access In Cognitive Radio Networks, Steven Boyd Aug 2010

Protocols For Dynamic Spectrum Access In Cognitive Radio Networks, Steven Boyd

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Spectrum access protocols permit secondary users to transmit on frequency bands that are not being utilized by the primary owners. A cognitive radio that wishes to transmit in a band must first decide if the band is available (i.e., not being used by the owner) and then it must periodically re-evaluate the band's availability once it begins transmitting in the band to ensure that a signal from a primary owner has not emerged. To accomplish these tasks, spectrum access protocols employ periodic sensing of the channel. Frequent sensing intervals are required to ensure that cognitive radios wishing to access the …


Robust Analysis Of Electromagnetic Responses Of Resonant Structures Using Early-Time And Low-Frequency Data, James Frye, Jr. Aug 2010

Robust Analysis Of Electromagnetic Responses Of Resonant Structures Using Early-Time And Low-Frequency Data, James Frye, Jr.

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The rapid increase of affordable computing resources combined with the continued development and refinement of computational electromagnetic (CEM) methods has yielded a wide range of accurate and well-verified EM modeling tools; however, improvements are required to keep pace with the current and future requirements of EM systems. One such need is the development of robust, computationally-efficient methods which provide one the means to understand complex resonant systems through the by analyzing EM responses. The characteristics of resonant systems often make the determination of a wideband response with CEM methods computationally very intensive. Also, a numerical solution may not directly provide …


Simulation And Mathematical Modeling To Support Community-Wide Evacuation Decisions For Multiple Population Groups, Jun Duanmu Aug 2010

Simulation And Mathematical Modeling To Support Community-Wide Evacuation Decisions For Multiple Population Groups, Jun Duanmu

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Evacuating a large population from an at-risk area has been the subject of extensive research over the past few decades. In order to measure trip completion and total evacuation times accurately, most researchers have implemented some combination of simulation and optimization methods to provide vehicular flow and congestion data. While the general at-risk population comprises the majority of travelers on the road network, there are often specific groups to consider when assessing the ability to evacuate an entire population. In particular, healthcare facilities (e.g., hospitals) may require evacuation, and the trip times may become an important health issue for patients …


Principal Component Analysis Based Image Fusion Routine With Application To Stamping Split Detection, Yi Zhou Aug 2010

Principal Component Analysis Based Image Fusion Routine With Application To Stamping Split Detection, Yi Zhou

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This dissertation presents a novel thermal and visible image fusion system with application in online automotive stamping split detection. The thermal vision system scans temperature maps of high reflective steel panels to locate abnormal temperature readings indicative of high local wrinkling pressure that causes metal splitting. The visible vision system offsets the blurring effect of thermal vision system caused by heat diffusion across the surface through conduction and heat losses to the surroundings through convection. The fusion of thermal and visible images combines two separate physical channels and provides more informative result image than the original ones.
Principal Component Analysis …


Prediction Of Liquid Crystalline Content And Molecular Structures Present In Carbonaceous Pitches, Ward Burgess Aug 2010

Prediction Of Liquid Crystalline Content And Molecular Structures Present In Carbonaceous Pitches, Ward Burgess

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ABSTRACT
Previous research at Clemson has shown that multistage, packed column, supercritical extraction (also called dense-gas extraction, or DGE) of petroleum pitches is a promising technique for the production of carbonaceous precursors that can be processed into a variety of carbon products, including activated carbons and high thermal conductivity carbon fibers. As the existence (or lack thereof) of a liquid crystalline phase, or mesophase, plays a key role in establishing the suitability of a potential precursor material for a given application, we developed the SAFT-LC (liquid crystal) equation of state by combining Maier-Saupe theory for multicomponent mixtures with the SAFT …


Development Of Tissue Engineered Test Systems To Study Mammary Cell Interactions In Vitro, Cheryl Cass Aug 2010

Development Of Tissue Engineered Test Systems To Study Mammary Cell Interactions In Vitro, Cheryl Cass

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The work described in this dissertation was conducted in the interdisciplinary research environment of the Clemson University Institute for Biological Interfaces of Engineering. A note at the beginning of each chapter acknowledges, as relevant, collaborating doctoral students and reminds the reader where work from each chapter has been presented or published. The overall goal of this work was to develop tissue engineered test system methodologies to allow the study of mammary cell interactions in vitro. The background, as described in Chapter 1, was published in part in Philosophical Transactions of the Royal Society A in 2010. The studies were designed …


Development Of A Finite Element Model To Predict The Behavior Of A Prototype Wheel On Lunar Soil, Marisa Orr Aug 2010

Development Of A Finite Element Model To Predict The Behavior Of A Prototype Wheel On Lunar Soil, Marisa Orr

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The All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) is a mobile lunar lander under development by the National Aeronautics and Space Administration's Lunar Architecture Team. While previous lunar missions have lasted only a few days, the ATHLETE is designed to last for 10 years, which will enable a sustained U.S. presence on the moon and exploration of the more treacherous regions which are not suitable for landing. Because the ATHLETE will carry entire astronaut habitats, its six wheels must be carefully designed to support a large load on soft lunar soil efficiently.
The purpose of this thesis is to develop a finite …


Nonlinear Control And Estimation Techniques With Applications To Vision-Based And Biomedical Systems, Nitendra Nath Aug 2010

Nonlinear Control And Estimation Techniques With Applications To Vision-Based And Biomedical Systems, Nitendra Nath

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This dissertation is divided into four self-contained chapters. In Chapter 1, a new estimator using a single calibrated camera mounted on a moving platform is developed to asymptotically recover the range and the three-dimensional (3D) Euclidean position of a static object feature. The estimator also recovers the constant 3D Euclidean coordinates of the feature relative to the world frame as a byproduct. The position and orientation of the camera is assumed to be measurable unlike existing observers where velocity measurements are assumed to be known. To estimate the unknown range variable, an adaptive least squares estimation strategy is employed based …


Investigation Of Subgrid-Scale Mixing And Turbulence-Chemistry Interaction In Turbulent Partially Premixed Flames Using Experimental Data, Jian Cai Aug 2010

Investigation Of Subgrid-Scale Mixing And Turbulence-Chemistry Interaction In Turbulent Partially Premixed Flames Using Experimental Data, Jian Cai

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The filtered mass density function (FMDF) of mixture fraction, temperature and species used in large eddy simulation (LES) of turbulent combustion is studied experimentally using line images obtained in turbulent partially premixed methane flames (Sandia flames D and E). Cross-stream filtering is employed to obtain the FMDF and other filtered variables. The mean of the FMDF conditional on the subgrid-scale (SGS) scalar variance at a given location are found to vary from unimodal to bimodal, corresponding to quasi-equilibrium distributed reaction zones and laminar flamelets (including extinguished flamelets), respectively. The conditionally filtered mixture fraction dissipation for small SGS variances has a …


Development Of Experimental Methods To Assess Adsorption Free Energy For Peptide-Surface Interactions, Yang Wei Jul 2010

Development Of Experimental Methods To Assess Adsorption Free Energy For Peptide-Surface Interactions, Yang Wei

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Because of its governing role in cellular response to implants and substrates for biomedical applications, the understanding and control of protein adsorption to material surfaces has been one of the major topics of research in the field of biomaterials. Unfortunately, it has proven to be extremely difficult to quantitatively understand and control these types of interactions because of the complexities involved, and existing methods that have been developed and used to characterize protein-surface interactions have proved to be inadequate to provide the level of detail necessary to achieve this understanding. New, more fundamental methods, both experimental and computational, are needed …


Cell-Mediated Elastic Matrix Regeneration Toward Regression Of Abdominal Aortic Aneurysms, Carmen Gacchina Jun 2010

Cell-Mediated Elastic Matrix Regeneration Toward Regression Of Abdominal Aortic Aneurysms, Carmen Gacchina

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Abdominal aortic aneurysms (AAAs) are typically fusiform (symmetric) dilations of the aortic wall most commonly arising below the renal arteries. The progression is typically associated with an activated smooth muscle cell (SMC) phenotype, diminished density of mature medial elastic fibers, and an elevated presence of matrix-degrading enzymes (e.g., matrix-metalloproteases; MMPs), which may ultimately lead to vessel rupture. Currently, no surgical or non-surgical methods are available to regress AAAs via regeneration of new elastin matrices to regain normal vessel contour, particularly due to the inherently poor elastin synthesis by adult vascular cells and absence of methods to stimulate the same. Previously, …


Fabrication Of Transparent Ceramic Laser Media For High Energy Laser Applications, Karn Serivalsatit May 2010

Fabrication Of Transparent Ceramic Laser Media For High Energy Laser Applications, Karn Serivalsatit

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Sesquioxides of yttrium, scandium, and lutetium, i.e., Y2O3, Sc2O3, and Lu2O3, have received a great deal of recent attention as potential high power solid state laser hosts. These oxides are receptive to lanthanide doping, including trivalent Er, Ho and Tm which have well known emissions at eye-safe wavelengths that can be excited using commercial diode lasers. These sesquioxides are considered superior to the more conventional yttrium aluminum garnet (YAG) due to their higher thermal conductivity, which is critical for high power laser system. Unfortunately, these oxides possess high …


Occurrence And Formation Of Disinfection By-Products In Indoor Swimming Pools Water, Amer Kanan May 2010

Occurrence And Formation Of Disinfection By-Products In Indoor Swimming Pools Water, Amer Kanan

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Chlorination is used to prevent the spread of waterborne infectious diseases from swimming pools. This required disinfection practice also results in the formation of undesirable disinfection by-products (DBPs) from the reactions of chlorine with the organic matter (released by swimmers or present in the filling water of the pool) and bromide. Some of these DBPs have important adverse public health effects; as a result their concentrations in drinking waters are regulated. Unfortunately, DBPs formation and control in swimming pools have not been studied and investigated to the same extent as their formation and control in drinking water.
The main objective …


Software Algorithms To Coordinate And Improve Voltage Sag Ridethrough Capabilities Of Networked Industrial Processes, Owen Parks May 2010

Software Algorithms To Coordinate And Improve Voltage Sag Ridethrough Capabilities Of Networked Industrial Processes, Owen Parks

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For those who design, operate, and troubleshoot industrial processes, electric power quality is a subject that requires much consideration. Processes that use electronic sensors, actuators, and computation devices are heavily reliant on a stable, consistent input power source. When a power quality event such as a voltage fluctuation occurs, automation equipment often behaves unpredictably and causes process malfunction or failure.
Because industrial power consumers often blame their electric utility for these events, some utilities offer process susceptibility studies as a service for their customers. During a typical study, utility technicians and engineers perform in-house tests on suspect components or systems …


Vehicle Steering Systems - Hardware-In-The-Loop Simulator, Driving Preferences, And Vehicle Intervention, Jesse Black May 2010

Vehicle Steering Systems - Hardware-In-The-Loop Simulator, Driving Preferences, And Vehicle Intervention, Jesse Black

All Dissertations

The steering system is a critical component of all ground vehicles regardless of their propulsion source. Chassis directional control is provided by the steering system, which in turn relays valuable feedback about the road and vehicle behavior. As the primary feedback channel to the driver, the steering system also delivers the initial perception of a vehicle's handling and responsiveness to the consumer. Consequently, the steering system is an important aspect of the vehicle's evaluation and purchasing process, even if drivers are unaware of its direct influence in their decision making. With automobile purchases potentially hinging on the steering system, a …


Layer-By-Layer Assembly Of {Nanoclay-(Sol-Gel Oxide)}N And {Nanoclay-(Oxide Nanoparticle)}N Multilayers: Synthesis And Growth Mechanisms, Hao Chen May 2010

Layer-By-Layer Assembly Of {Nanoclay-(Sol-Gel Oxide)}N And {Nanoclay-(Oxide Nanoparticle)}N Multilayers: Synthesis And Growth Mechanisms, Hao Chen

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Two new classes of all-inorganic nanostructured multilayers, {MMTx-(sol-gel oxide)}n and {MMTx-(oxide nanoparticle)}n, have been successfully synthesized for the first time. They were made by adapting a layer-by-layer (LbL) assembly method initially developed to synthesize polyelectrolyte-based multilayers. In most previous studies, this electrostatic-assisted LbL assembly method used polyelectrolytes/polymers as the 'structural glue' to prepare multilayers. The synthesis of {MMTx-(sol-gel ZrO2)}n multilayers demonstrates for the first time the feasibility of making sol-gel oxide 'glued' all-inorganic multilayers, thereby introducing an innovative nanoscale fabrication concept. The synthesis of {MMTx-(oxide nanoparticle)}n multilayers further illustrates the versatility of LbL assembly technique by achieving a second new …


Cross-Layer Scheduling Protocols For Mobile Ad Hoc Networks Using Adaptive Direct-Sequence Spread-Spectrum Modulation, Brian Wolf May 2010

Cross-Layer Scheduling Protocols For Mobile Ad Hoc Networks Using Adaptive Direct-Sequence Spread-Spectrum Modulation, Brian Wolf

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We investigate strategies to improve the performance of transmission schedules for mobile ad hoc networks (MANETs) employing adaptive direct-sequence spread-spectrum (DSSS) modulation. Previously, scheduling protocols for MANETs have been designed under the assumption of an idealized, narrowband wireless channel. These protocols perform poorly when the channel model incorporates distance-based path loss and co-channel interference. Wideband communication systems, such as DSSS systems, are more robust in the presence of co-channel interference; however, DSSS also provides multiple-access capability that cannot be properly leveraged with a protocol designed for narrowband systems. We present a new transmission scheduling protocol that incorporates link characteristics, spreading …


Energy And Nutrient Recovery From Anaerobic Treatment Of Organic Wastes, Christian-Dominik Henrich May 2010

Energy And Nutrient Recovery From Anaerobic Treatment Of Organic Wastes, Christian-Dominik Henrich

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The objective of the research was to develop a complete systems design and predictive model framework of a series of linked processes capable of providing treatment of landfill leachate while simultaneously recovering nutrients and bioenergy from the waste inputs. This proposed process includes an 'Ammonia Recovery Process' (ARP) consisting of: 1) ammonia de-sorption requiring leachate pH adjustment with lime or sodium hydroxide addition followed by, 2) ammonia re-absorption into a 6-molar sulfuric acid spray-tower followed by, 3) biological activated sludge treatment of soluble organic residuals (BOD) followed by, 4) high-rate algal post-treatment and finally, 5) an optional anaerobic digestion process …


Grain Boundary Premelting And Activated Sintering In Binary Refractory Alloys, Xiaomeng Shi May 2010

Grain Boundary Premelting And Activated Sintering In Binary Refractory Alloys, Xiaomeng Shi

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Quasi-liquid intergranular film (IGF) which has been widely observed in ceramic systems can persist into sub-solidus region whereby an analogy to Grain boundary (GB) premelting can be made.
In this work, a grain boundary (GB) premelting/prewetting model in a metallic system was firstly built based on the Benedictus' model and computational thermodynamics, predicting that GB disordering can start at 60-85% of the bulk solidus temperatures in selected systems. This model quantitatively explains the long-standing mystery of subsolidus activated sintering in W-Pd, W-Ni, W-Co, W-Fe and W-Cu, and it has broad applications for understanding GB-controlled transport kinetics and physical properties. Furthermore, …


Isolating Petroleum Pitch Oligomers Via Multistage Supercritical Extraction, Eduardo Cervo May 2010

Isolating Petroleum Pitch Oligomers Via Multistage Supercritical Extraction, Eduardo Cervo

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Petroleum pitches are carbonaceous materials that serve as precursors for advanced carbon products. Because of their highly graphitic nature, such pitches are of particular interest for producing high thermal conductivity carbon fibers for thermal management applications, such as microelectronics packaging for hybrid and plug-in vehicles.
Even though the properties of the final carbon products are impacted by the molecular composition of the starting pitch precursor, a fundamental understanding of this relationship has yet to be established. To this end, dense-gas extraction (DGE), a fractionation technique that allows for the production of pitches of controlled composition for both analytical and rheological …


Osteoclast-Mediated Cell Therapy As An Attempt To Treat Elastin-Specific Vascular Calcification, Chartrisa Simpson May 2010

Osteoclast-Mediated Cell Therapy As An Attempt To Treat Elastin-Specific Vascular Calcification, Chartrisa Simpson

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Vascular calcification occurs during physiological aging and is clinically recognized as a major risk factor for myocardial infarction, systolic hypertension, heart failure and coronary insufficiency caused by loss of aortic recoil. Medial arterial calcification is an active remodeling process that involves the deposition of bone-specific matrix in close association with elastic fibers. Elastin, a major structural protein in the extracellular matrix of arterial walls, provides elastic recoil to the arteries. Increasing evidence suggests that vascular calcification share features with skeletal bone formation such as bone matrix deposition and bone resorption. Bone morphogenetic proteins and bone cells have been found in …


Biodegradation And Bioremediation Of Hexachlorocyclohexane Isomers, Chlorinated Ethenes, Chlorinated Benzenes And Benzene, Vijaikrishnah Elango May 2010

Biodegradation And Bioremediation Of Hexachlorocyclohexane Isomers, Chlorinated Ethenes, Chlorinated Benzenes And Benzene, Vijaikrishnah Elango

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ABSTRACT
Groundwater at an industrial site is contaminated with γ -hexachlorocyclohexane (HCH) and α-HCH (i.e., lindane) (0.3-0.5 ppm). Other contaminants in the 1-15 ppm range include 1,2,4-trichlorobenezene (TCB), 1,2-dichlorobenzene (DCB), 1,3-DCB, 1,4-DCB, chlorobenzene (CB), benzene, trichloroethene (TCE) and cis-1,2-dichloroethene (cDCE). The aquifer consists of a shallow layer of soil over fractured dolomite, where most of the contaminant mass resides. The objective of this study was to compare 1) anaerobic reductive dechlorination of the polychlorinated contaminants, followed by aerobic biodegradation of the daughter products (mainly DCBs, CB, and benzene); and 2) aerobic biodegradation of α- and γ-HCH, TCB, DCBs, CB and …


A Lyapunov Based Approach To Energy Maximization In Renewable Energy Technologies, Erhun Iyasere May 2010

A Lyapunov Based Approach To Energy Maximization In Renewable Energy Technologies, Erhun Iyasere

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This dissertation describes the design and implementation of Lyapunov-based control strategies for the maximization of the power captured by renewable energy harnessing technologies such as (i) a variable speed, variable pitch wind turbine, (ii) a variable speed wind turbine coupled to a doubly fed induction generator, and (iii) a solar power generating system charging a constant voltage battery.
First, a torque control strategy is presented to maximize wind energy captured in variable speed, variable pitch wind turbines at low to medium wind speeds. The proposed strategy applies control torque to the wind turbine pitch and rotor subsystems to simultaneously control …


The Development Of A Mesenchymal Stem Cell Based Biphasic Osteochondral Tissue Engineered Construct, Scott Maxson Jan 2010

The Development Of A Mesenchymal Stem Cell Based Biphasic Osteochondral Tissue Engineered Construct, Scott Maxson

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The ability of human articular cartilage to respond to injury is poor. Once cartilage damage has occurred, an irreversible degenerative process can occur and will often lead to osteoarthritis (OA). An estimated 26.9 million of U.S. adults are affected by OA. Osteochondral grafting is currently used to treat OA and osteochondral defects; however, complications can develop at the donor site and defect area. Osteochondral tissue engineering provides a potential treatment option and alternative to osteochondral grafting. The long term goal of this work is to develop a tissue engineered mesenchymal stem cell (MSC) based osteochondral construct to repair cartilage damage. …


Production And Characterization Of Novel Air Filtration Media, Elizabeth Skomra Jan 2010

Production And Characterization Of Novel Air Filtration Media, Elizabeth Skomra

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HEPA and ULPA filtration systems have proven to be an advantageous instrument in removing common contaminants from the air. However, an increased pressure drop due to the build-up of particulates on the filters results in its inevitable decrease in performance. Improving current filtration systems would include increasing collection efficiency all the while either maintaining or reducing the differential pressure drop in order to extend the life of the filter. One method of improving collection efficiency would be viable by increasing the amount of surface area within the filter media by glass fibers because of their inherent quality of being smaller …