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Articles 1621 - 1650 of 2584

Full-Text Articles in Engineering

Examination Of The Effectiveness Of Bioretention Cells And Porous Paving Practices In Aiken, Sc, Casey Johnson Dec 2012

Examination Of The Effectiveness Of Bioretention Cells And Porous Paving Practices In Aiken, Sc, Casey Johnson

All Theses

This work seeks to quantify the impact and effectiveness of green infrastructure practices, specifically bioretention cells and porous asphalts, for the reduction of peak flow and volume of stormwater that discharges into the headwaters of the Sand River watershed in Aiken, SC. Stormwater runoff flows and volumes were monitored in the upper Sand River watershed that includes the urban Aiken area, along with two nested subwatersheds, prior to, during, and after the construction of the bioretention cells and porous asphalt sites. Flow data from these monitoring stations were analyzed and the data suggested that there was no significant reduction in …

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Composite Sandwich Structures With Honeycomb Core Subjected To Impact, Lei He Dec 2012

Composite Sandwich Structures With Honeycomb Core Subjected To Impact, Lei He

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Composite sandwich structures constructed with honeycomb core can be an effective means of absorbing impact in many engineer applications. Conventional hexagonal honeycomb exhibit an effective positive Poisson's ratio, are commonly employed due to their lightweight and high axial stiffness properties. In contrast, auxetic honeycombs offer high in-plane shear stiffness, and exhibit negative Poisson's ratios with lateral extension, instead of contraction, when stretched axially.
In this study, the dynamic response of an aluminum composite panel with a honeycomb core constrained within two thin face sheets is investigated undergoing impact with a rigid ball. The finite element models used to simulate impact …

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Characterization And Restoration Of Historic Rosendale Cement Mortars For The Purpose Of Restoration, Stephanie Hart Dec 2012

Characterization And Restoration Of Historic Rosendale Cement Mortars For The Purpose Of Restoration, Stephanie Hart

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Mortar was a very common building material in today's historic sites. Before Portland cement was manufactured at a global level, Rosendale cement was commonly used in these mortars. Over time, these mortars in historic sites have begun to break down and wear away. With Rosendale cement in production again, measures can be taken to restore and repair the historic mortars. However, little testing has been done to establish durability of modern Rosendale cement mortars. This presentation highlights the common mix techniques used at the time, and undergoes experiments to establish general properties and predict future durability. Six different mortar mixes …

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An Examination Of The Influence Of Cement Paste On Pervious Concrete Mixtures, Donald Singer Dec 2012

An Examination Of The Influence Of Cement Paste On Pervious Concrete Mixtures, Donald Singer

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Pervious concrete has many environmental benefits, but with these benefits come additional hurdles unseen in conventional concrete. The main focus of pervious concrete is the maintenance of the interconnected pore structure, leading to porosity values between 15 and 25%, while still developing adequate strength. Due to these inherent properties of pervious concrete, development of a systematic optimum mix design method is challenging. Currently, there is a need to develop a systematic optimum mix design for pervious concrete, but it has yet come to fruition. This research focuses on the influence of cement paste on the performance of pervious concrete, and …

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In Situ Ground Freezing And Sampling Of A Pleistocene Sand Deposit In The South Carolina Coastal Plain, Michael Esposito Iii Dec 2012

In Situ Ground Freezing And Sampling Of A Pleistocene Sand Deposit In The South Carolina Coastal Plain, Michael Esposito Iii

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The procedures used to freeze and sample a Pleistocene sand deposit at the Coastal Research and Education Center near Charleston, South Carolina to preserve and study the effects of diagenesis are presented in this thesis. An initial feasibility study was conducted to target a layer of clean sand at the CREC site with little to no frost heave potential. To freeze the sand deposit, a ground freezing system with a central freezing pipe was installed to target a column of sand 1-m in radius and 2.3-m long. Liquid nitrogen was continuously supplied to the large steel freezing pipe, which was …

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Analysis Of Energy Savings Through The Use Of Displacement Ventilation In Domestic Buildings, Patrick Daffin Dec 2012

Analysis Of Energy Savings Through The Use Of Displacement Ventilation In Domestic Buildings, Patrick Daffin

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This study investigates the conditions under which it might be possible to implement a displacement ventilation system in a residential building. An experimental study of the impact on a mechanical air conditioning system of the vertical location of the inlet and outlet vents was performed. The four ventilation configurations of low inlet high outlet, low inlet low outlet, high inlet high outlet, and high inlet low outlet were compared. These four configurations were compared under 13 different heat load scenarios in a full scale instrumented model room. It was found that, for higher heat loads, the low inlet high outlet …

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Preliminary Investigation Into The Design Of Thermally Responsive Forster Resonance Energy Transfer Colloids, Monte Bedford Dec 2012

Preliminary Investigation Into The Design Of Thermally Responsive Forster Resonance Energy Transfer Colloids, Monte Bedford

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While nuclear imaging techniques (Magnetic Resonance Imaging, Computed Tomography, and Positron Emission Tomography) have proven effective for diagnosis and treatment of disease in the human body, fluorescence-enhanced optical imaging offers additional benefits. Fluorescent imaging provides high resolution with real-time response, persistent lifetime (hours to days), cell targeting, and transdermal penetration with minimal physical encumbrance. Malignant cells can be targeted by absorbance of exogenous fluorescent nanoprobe contrast agents. Imaging is improved by fluorescent enhancement, especially by energy transfer between attached dyes. Also for use against cancer are heat-active treatments, such as hyperthermal, photothermal, and chemothermal therapies. Helpful to these treatments is …

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Study Of Cell Viability During Laser Direct Writing Of Cell-Alginate Suspension, Hemanth Gudapati Dec 2012

Study Of Cell Viability During Laser Direct Writing Of Cell-Alginate Suspension, Hemanth Gudapati

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Laser-assisted cell printing, developed based on Matrix-assisted pulsed-laser evaporation direct-write (MAPLE DW), a typical LIFT (laser-induced forward transfer) practice, has been emerging as one of the most promising biofabrication techniques. Alginate, particularly sodium alginate, is extensively used as the constituent of bioink in laser-assisted cell printing. However, thus far, studies investigating the effect of alginate gelation on cell viability in laser-assisted cell printing are lacking. The objective of this study is to investigate the effects of gelation, gelation time, sodium alginate concentration, and the effect of operating conditions such as the laser fluence on post-transfer cell viability during laser-assisted cell …

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Durability Of Reinforced Concrete Incorporating Crushed Waste Brick As Coarse Aggregate, Matthew Adamson Dec 2012

Durability Of Reinforced Concrete Incorporating Crushed Waste Brick As Coarse Aggregate, Matthew Adamson

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Using crushed bricks as aggregates in concrete is of particular interest to preserve natural aggregate sources as well as to reduce waste, as it has been estimated that 10% to 30% of all waste in landfills in the united States comes from construction and demolition wastes. By recycling some of these wastes, the sustainability of a project can be improved. However, it is important concrete incorporating these wastes is as durable or more durable then conventional concrete, or will it have a shorter service life. Durability of concrete is its ability to resist deterioration from its external environment such as …

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Bioswellable Amphiphilic Copolymers, David Ingram Dec 2012

Bioswellable Amphiphilic Copolymers, David Ingram

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The suture is one of the most commonly used medical devices, consisting of a fiber, a surgical needle and the packaging in which it is stored. The fiber itself remains after implantation for a defined time and is responsible for the approximation of the wound during the healing process. The needle merely serves to aid in insertion, and preferably has a diameter larger than the diameter of the fiber .
The 1970's marked the birth of a new family of fibrous materials for the approximation of wounds: synthetic absorbable sutures. This family has the ability to provide wound support during …

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Investigation Of Auxiliary Winding Harmonic Resonance Phenomena In Single Phase Induction Motors, Gaurav Singh Dec 2012

Investigation Of Auxiliary Winding Harmonic Resonance Phenomena In Single Phase Induction Motors, Gaurav Singh

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In recent years, the proliferation of single phase power electronics based loads has given rise to a number of power quality issues in the power grid. Harmonics in voltage and current waveforms are one of the biggest problems in this family of power quality issues. Until some years back, power system utilities did not consider harmonics due to small single phase loads to be a big problem. In fact, only large loads were considered as potential hotspots for power quality problems. However, the advent of compact fluorescent lamps (CFLs), personal computers and consumer electronic devices, which utilize rectifier front ends, …

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Reverse Osmosis Desalination With Integrated Compressed Air Energy Storage: Conceptual Design And Modeling, Pooja Mahajan Dec 2012

Reverse Osmosis Desalination With Integrated Compressed Air Energy Storage: Conceptual Design And Modeling, Pooja Mahajan

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Growing fresh water needs have led to an interest in water desalination using reverse osmosis (RO) membranes. Energy consumption has a large share in the expenses incurred to drive a reverse osmosis desalination system. With depleting fossil fuel reserves, tapping renewable sources of energy is a promising alternative to meet the energy requirements. Wind power coupled to an RO desalination system is a potential means of delivering clean water using sustainable energy. This work investigates modeling of a conceptual wind-energy-driven RO desalination system that is made possible because of an air-pressure energy storage mechanism. Bench-scale experiments were performed on an …

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Estimating Water Flux And Storage Using Displacement Measurements In Saprolite At Depth, Clay Freeman Dec 2012

Estimating Water Flux And Storage Using Displacement Measurements In Saprolite At Depth, Clay Freeman

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Water storage in the soil is important for many hydrologic problems, but measuring how the storage changes at an appropriate scale remains a challenge. The objective of this thesis is to evaluate the feasibility of estimating change in water content in soil by measuring vertical displacement in underlying soils. This approach is appealing because the averaging volume of the displacement scales with the depth at which the measurements are taken. This should result in measurements of changes in soil moisture that are averaged over regions 10s to 100s of meters across, a measurement scale that is much larger than that …

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Updated Force Model For Milling Nickel-Based Superalloys, Andrew Henderson Dec 2012

Updated Force Model For Milling Nickel-Based Superalloys, Andrew Henderson

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Nickel-based superalloys are commonly used in applications which require high strength and resistance to creep and oxidation in extreme conditions. All nickel-based superalloys are considered difficult to machine; however, cast gamma-prime-strengthened nickel-based superalloys are more difficult to machine than common nickel-based superalloys. Machining comprises a significant portion of manufacturing processes and with advancements in technology and material properties, the methods and models used must be adapted in order to keep pace.
In this research, correlations are made, using fundamental principles, between measurements made with on-machine touch probes and the cutting tool's wear state, those correlations are used in an adaptive …

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Assessment Of Fidelity To Data And Robustness To Uncertainty To Assure Credible Predictions In The Modeling Of Wind Turbine Blades, Kendra Van Buren Dec 2012

Assessment Of Fidelity To Data And Robustness To Uncertainty To Assure Credible Predictions In The Modeling Of Wind Turbine Blades, Kendra Van Buren

All Dissertations

In the field of wind energy, modeling and simulation techniques provide an efficient and economical alternative to experimentation for studying the behavior of wind turbines. Numerical models however are approximations of reality, thusly making it crucial to evaluate various sources of uncertainties that influence the model predictions. Credibility of a numerical model rests on the model's ability to replicate existing experimental data, widely known as fidelity-to-data. This dissertation advocates that fidelity-to-data, while necessary, is insufficient to claim credibility of a numerical model. Herein, the objective is to develop numerical models that not only provide agreement to experimental data, but also …

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Integrated Production And Distribution Problem With Single Perishable Product, Wennian Li Dec 2012

Integrated Production And Distribution Problem With Single Perishable Product, Wennian Li

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This dissertation investigated the extension of the Integrated Production and Distribution Scheduling Problem (IPDSPP) using a variety of perishable products, applying the JIP principle and make-to-order strategy to integrate the production and distribution schedules. A single perishable product with a constant lifetime after production was used in the model discussed here. The objective of the problem was to find the solution that results in minimal system total transportation costs while satisfying customer demand within a fixed time horizon. In the solution, the fleet size, vehicle route and distribution schedule, plant production batch size and schedule were determined simultaneously. This research …

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Supply Chain Network Design: Risk-Averse Vs. Risk-Neutral Decision Making, Alireza Madadi Dec 2012

Supply Chain Network Design: Risk-Averse Vs. Risk-Neutral Decision Making, Alireza Madadi

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Recent events, such as the Heparin tragedy, highlight the necessity for designers and planners of supply chain networks to consider the risk of disruptions in spite of their low probability of occurrence. One effective way to hedge against supply chain network disruptions is to have a robustly designed supply chain network. This involves strategic decisions, such as choosing which markets to serve, which suppliers to source from, the location of plants, the types of facilities to use, and tactical decisions, such as production and capacity allocation. In this dissertation, we focus on models for designing supply chain networks that are …

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Develop Novel Frap Techniques For Determining Anisotropic Solute Diffusion In Cartilaginous Tissues, Changcheng Shi Dec 2012

Develop Novel Frap Techniques For Determining Anisotropic Solute Diffusion In Cartilaginous Tissues, Changcheng Shi

All Dissertations

Cartilaginous tissue is a connective tissue composed of specialized cells (e.g., chondrocytes and fibroblasts) that produce a large amount of extracellular matrix (ECM), which is comprised mostly of collagen fibers, abundant ground substance rich in proteoglycan, and elastic fibers. It is characterized by its avascular structures within the tissue, implying that nutrition for normal tissue cells, for maintaining a healthy ECM, is mainly supplied through diffusion from nearby vascularized tissues and synovial fluid. Poor nutritional supply to the cartilaginous tissue is believed to be an important factor leading to tissue degeneration. Moreover, due to the complex collagen fiber structures, the …

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Phase Transformation In Ti-Mo-O, Herbert Boeckels Dec 2012

Phase Transformation In Ti-Mo-O, Herbert Boeckels

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The present dissertation has investigated the effect of oxygen on the ù and á phase stability in metastable Ti-Mo â titanium alloys using thermal analysis, hardness measurements, electron microscopy, and x-ray diffraction.
Single crystal x-ray diffraction has shown that oxygen atoms are located in the tetrahedral interstitial lattice sites in the rapidly cooled bcc Ti crystal structure, interfering directly with the reversible displacive formation of ù, with this transformation involving collapse of the bcc lattice along â. Subsequent thermal exposure of reversible ù, as occurring during slower cooling, heating, and aging, prompts short range diffusion and the formation of chemical …

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Network Traffic Analysis Using Stochastic Grammars, Chen Lu Dec 2012

Network Traffic Analysis Using Stochastic Grammars, Chen Lu

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Network traffic analysis is widely used to infer information from Internet
traffic. This is possible even if the traffic is encrypted. Previous work uses
traffic characteristics, such as port numbers, packet sizes, and frequency,
without looking for more subtle patterns in the network traffic. In this work,
we use stochastic grammars, hidden Markov models (HMMs) and probabilistic
context-free grammars (PCFGs), as pattern recognition tools for traffic
analysis.
HMMs are widely used for pattern recognition and detection. We use a HMM
inference approach. With inferred HMMs, we use confidence intervals (CI) to
detect if a data sequence matches the HMM. To …

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Stochastic Tools For Network Security: Anonymity Protocol Analysis And Network Intrusion Detection, Lu Yu Dec 2012

Stochastic Tools For Network Security: Anonymity Protocol Analysis And Network Intrusion Detection, Lu Yu

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With the rapid development of Internet and the sharp increase of network crime, network security has become very important and received a lot of attention.
In this dissertation, we model security issues as stochastic systems. This allows us to find weaknesses in existing security systems and propose new solutions. Exploring the vulnerabilities of existing security tools can prevent cyber-attacks from taking advantages of the system weaknesses. We consider The Onion Router (Tor), which is one of the most popular anonymity systems in use today, and show how to detect a protocol tunnelled through Tor. A hidden Markov model (HMM) is …

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Phoneme Weighting And Energy-Based Weighting For Speaker Recognition, Eric Fang Dec 2012

Phoneme Weighting And Energy-Based Weighting For Speaker Recognition, Eric Fang

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This dissertation focuses on determining specific vowel phonemes which work best for speaker identification and speaker verification, and also developing new algorithms to improve speaker identification accuracy. Results from the first part of our research indicate that the vowels /i/, /E/ and /u/ were the ones having the highest recognition scores for both the Gaussian mixture model (GMM) and vector quantization (VQ) methods (at most one classification error). For VQ, /i/, /I/, /e/, /E/ and /@/ had no classification errors. Persons speaking /E/, /o/ and /u/ have been verified well by both GMM and VQ methods in our experiments. For …

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Improving Accuracy In Ultra-Wideband Indoor Position Tracking Through Noise Modeling And Augmentation, Salil Banerjee Dec 2012

Improving Accuracy In Ultra-Wideband Indoor Position Tracking Through Noise Modeling And Augmentation, Salil Banerjee

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The goal of this research is to improve the precision in tracking of an ultra-wideband (UWB) based Local Positioning System (LPS). This work is motivated by the approach taken to improve the accuracies in the Global Positioning System (GPS), through noise modeling and augmentation. Since UWB indoor position tracking is accomplished using methods similar to that of the GPS, the same two general approaches can be used to improve accuracy.
Trilateration calculations are affected by errors in distance measurements from the set of fixed points to the object of interest. When these errors are systemic, each distinct set of fixed …

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Application Of Carbon Dioxide Towards The Development Of Smart Materials, Green Reaction Schemes And Metallic Nanoparticle Synthesis, Fiaz Mohammed Dec 2012

Application Of Carbon Dioxide Towards The Development Of Smart Materials, Green Reaction Schemes And Metallic Nanoparticle Synthesis, Fiaz Mohammed

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Global carbon dioxide (CO2) emissions have steadily risen over the last 50 years, with 34 billion tons of CO2 released in 2009 alone. Its potential as a greenhouse gas has negatively affected of our lives and environment by the resulting ocean acidification and climate change. To mitigate atmospheric CO2, various strategies have been implemented for CO2 separation, capture, storage and use as a chemical feedstock. The use of CO2 in various chemical industries is attractive as its non-flammable, non-toxic, and relatively inert properties have made it an inherently safer alternative to traditional organic …

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On-Line Transient Stability Studies Incorporating Wind Power, Zhenhua Wang Dec 2012

On-Line Transient Stability Studies Incorporating Wind Power, Zhenhua Wang

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Transient stability is a major concern in power system security and reliability because it is the most common type of instability and its impacts can cause greatest economic losses. For enhancing the energy security, it requires the power system operation to be evaluated during both the planning and the operation stage. Many online/offline transient stability assessment techniques have already been developed for this purpose. However, due to the increase in energy demand, the modern power system has grown to a very sophisticated and large system for which extent transient stability assessment methods may not be able to handle. In addition, …

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A Process Analysis Of Engineering Problem Solving And Assessment Of Problem Solving Skills, Sarah Grigg Dec 2012

A Process Analysis Of Engineering Problem Solving And Assessment Of Problem Solving Skills, Sarah Grigg

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In the engineering profession, one of the most critical skills to possess is accurate and efficient problem solving. Thus, engineering educators should strive to help students develop skills needed to become competent problem solvers. In order to measure the development of skills, it is necessary to assess student performance, identify any deficiencies present in problem solving attempts, and identify trends in performance over time. Through iterative assessment using standard assessment metrics, researchers/instructors are able to track trends in problem solving performance across time, which can serve as a gauge of students' learning gains.
This research endeavor studies the problem solving …

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Synthesis And Characterization Of Nanoscale Fluorescent Polymer Films, Maryus Chyasnavichyus Dec 2012

Synthesis And Characterization Of Nanoscale Fluorescent Polymer Films, Maryus Chyasnavichyus

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Performance of the chemical sensing devices is based sensitivity to the targeted analytes and accuracy of the measurements. Of many different types of chemical sensors, fluorescence based sensing devices draw much attention as efficient yet small and straightforward devices, capable of detection of various analytes at extremely small quantities.
Polymeric materials provide support for the fluorescent materials and usually serve as a host for the chromophores, protecting them from harsh environments, and serve as a transport media for the analyte.
In the present study thin fluorescent polymer films, sensitive to the environment are synthesized and studied. Poly(glycidyl methacrylate) was used …

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Induced Elastic Matrix Synthesis Within 3-Dimensional Collagen Constructs, Lavanya Venkataraman Dec 2012

Induced Elastic Matrix Synthesis Within 3-Dimensional Collagen Constructs, Lavanya Venkataraman

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Elastin, a primary component of elastic arteries, maintains structural stability of the cyclically recoiling artery, and critically regulates vascular cell behavior. Accelerated degradation of elastic matrix, such as that seen in vascular pathologies like abdominal aortic aneurysms (AAA), can therefore severely compromise vessel homeostasis. Tissue engineering and in-situ matrix repair strategies evaluated so far are primarily limited in inducing adult vascular cells to replicate the complex elastic matrix assembly process, and restore lost matrix integrity. Previously, our lab established the elastogenic benefits of concurrent delivery of TGF-β1 and HA-oligomers (together termed elastogenic factors, EFs), within 2D cultures of rat aortic …

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Towards Trustworthy, Efficient And Scalable Distributed Wireless Systems, Ze Li Dec 2012

Towards Trustworthy, Efficient And Scalable Distributed Wireless Systems, Ze Li

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Advances in wireless technologies have enabled distributed mobile devices to connect with each other to form distributed wireless systems. Due to the absence of infrastructure, distributed wireless systems require node cooperation in multi-hop routing. However, the openness and decentralized nature of distributed wireless systems where each node labors under a resource constraint introduces three challenges: (1) cooperation incentives that effectively encourage nodes to offer services and thwart the intentions of selfish and malicious nodes, (2) cooperation incentives that are efficient to deploy, use and maintain, and (3) routing to efficiently deliver messages with less overhead and lower delay. While most …

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Photo-Thermal Processing Of Semiconductor Fibers And Thin Films, Nishant Gupta Dec 2012

Photo-Thermal Processing Of Semiconductor Fibers And Thin Films, Nishant Gupta

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Furnace processing and rapid thermal processing (RTP) have been an integral part of several processing steps in semiconductor manufacturing. The performance of RTP techniques can be improved many times by exploiting quantum photo-effects of UV and vacuum ultraviolet (VUV) photons in thermal processing and this technique is known as rapid photo-thermal processing (RPP). As compared to furnace processing and RTP, RPP provides higher diffusion coefficient, lower stress and lower microscopic defects. In this work, a custom designed automated photo assisted processing system was built from individual parts and an incoherent light source. This photo-assisted processing system is used to anneal …

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