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2007

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Articles 3031 - 3060 of 3831

Full-Text Articles in Engineering

Level Basin Approaches To Improve Water Management In Surface Irrigation For Northeast Louisiana, Luis R. Ocampo Briceno Jan 2007

Level Basin Approaches To Improve Water Management In Surface Irrigation For Northeast Louisiana, Luis R. Ocampo Briceno

LSU Master's Theses

In the state of Louisiana surface irrigation is widely used due to the low start-up cost, typically high rainfall, and soil conditions. Irrigation scheduling is an important practice to achieve water use efficiency in agriculture. The objectives of this study were to compare three different methods to determine crop evapotranspiration (ETc) for soybeans in addition to, evaluate a computer based irrigation scheduling program using real scale fields. Weather variables, soil moisture and irrigation water use collected during the summer months of 2005 and 2006 at a production agriculture farm in northeast Louisiana were studied. The ETc estimates obtained using atmometers …

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An Optimal Operational Policy For An Integrated Production-Delivery System Under Continuous Price Decrease, Deniz Mungan Jan 2007

An Optimal Operational Policy For An Integrated Production-Delivery System Under Continuous Price Decrease, Deniz Mungan

LSU Master's Theses

In today’s competitive world, the unit cost of a high-tech product declines significantly over its life cycle. An integrated inventory model for products experiencing continuous decrease in unit cost is studied in this research. In this integrated model a manufacturing facility purchases raw material from outside supplier at a fixed size and supplies a fixed quantity of finished products to a buyer periodically after using its production processes. Moreover, buyers demand frequent deliveries of small lots of finished products since the price is continuously decreasing, and this emphasizes the significance of just-in-time (JIT) inventory management for successful companies in technology-related …

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Simulation Study Evaluating Alternative Initial Responses To Formation Fluid Influx During Managed Pressure Drilling, Asis Kumar Das Jan 2007

Simulation Study Evaluating Alternative Initial Responses To Formation Fluid Influx During Managed Pressure Drilling, Asis Kumar Das

LSU Master's Theses

Managed pressure drilling is an innovative technique to precisely manage wellbore pressure. It is particularly applicable for reducing the risk of a kick or lost returns when drilling with a narrow window between pore pressure and fracture pressure. The constant bottomhole pressure method of managed pressure drilling uses annular frictional pressure and choke pressure in addition to mud hydrostatic pressure to achieve precise wellbore pressure control. This project investigated alternative initial responses to kicks to determine which would be most effective and reliable under different well scenarios when applying the constant bottomhole pressure method of managed pressure drilling. Three different …

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Direct White Sugar Production: Optimization And Chemical Regeneration Of Fixed-Bed Activated Carbon Adsorbers, Raul Alejandro Cortes Jan 2007

Direct White Sugar Production: Optimization And Chemical Regeneration Of Fixed-Bed Activated Carbon Adsorbers, Raul Alejandro Cortes

LSU Master's Theses

A system for the direct production of white sugar from clarified sugar cane juice in a raw sugar factory has been developed at the Audubon Sugar Institute. This Direct White Sugar Production (DWiSP) system employs a series of columns packed with adsorbent media. Activated carbon is used in the first column(s) as a filter and bulk decolorizer. Ion exchange resins are then used to remove ash and remaining color. Batch testing was performed in order to determine equilibrium parameters. An analytical model was utilized in conjunction with column loading tests to determine dynamic characteristics of the carbon adsorber for use …

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Fabrication Of Single Walled Carbon Nanotube (Sw-Cnt) Cantilevers For Chemical Sensing, Jui-Ching Hsu Jan 2007

Fabrication Of Single Walled Carbon Nanotube (Sw-Cnt) Cantilevers For Chemical Sensing, Jui-Ching Hsu

LSU Master's Theses

With the discovery of carbon nanotubes (CNTs), many applications have been implemented based on their unique electronic, mechanical, chemical and optoelectronic properties. One area of applications is in gas sensors for detecting, oxygen, flammable and toxic gases. In our work, the focus is on the fabrication of carbon nanotube (CNT) cantilever sensors for integration with CMOS readout chip which offer increased sensitivity. The higher surface-to-bulk ratio enhances the property and performance of the gas sensor by nanocantilevers. In this work, we present the detection method based on the change in capacitance of the single walled carbon nanotube (SWCNT) cantilever. Carbon …

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A Novel Template Stage With Superior Alignment Capability For Nanoimprint And Step And Flash Lithography, Yunmi Jeon Jan 2007

A Novel Template Stage With Superior Alignment Capability For Nanoimprint And Step And Flash Lithography, Yunmi Jeon

LSU Master's Theses

The high-resolution capabilities of imprinting and step and flash lithography make these techniques strong contenders for the next generation lithography. Unfortunately, alignment remains an area of concern for nanoimprint because it must be completed before the template is moved into contact with the wafer. The large forces on the template during the process, even for step and flash, place additional demands on the stiffness as well as the reproducibility of the template stage. In this thesis, a prototype flexure stage has been developed to meet these demands. A compressive load, slightly below the Euler's limit, is used to produce relatively …

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Reactive Multilayer Foils And Their Applications In Joining, Xiaotun Qiu Jan 2007

Reactive Multilayer Foils And Their Applications In Joining, Xiaotun Qiu

LSU Master's Theses

In this study, Ni/Al multilayer foils were fabricated by a cold rolling method. A two-stage reaction process was observed in the reaction-ignition experiment. The phase formation process in the cold rolled foils was studied. The first reaction stage with a slow reaction velocity was the lateral growth of Al3Ni phase at isolated nucleation sites and the subsequent coalescence into a continuous layer. The second reaction stage with a fast reaction velocity was the growth of the Al3Ni layers in the direction normal to the Ni/Al interface until all Al was consumed. Afterwards, Al3Ni reacted with the remaining Ni to form …

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The Catalytic Partial Oxidation Of N-Tetradecane On Rh And Sr Substituted Pyrochlores, Daniel Haynes Jan 2007

The Catalytic Partial Oxidation Of N-Tetradecane On Rh And Sr Substituted Pyrochlores, Daniel Haynes

LSU Master's Theses

Catalyst deactivation by high levels of sulfur and aromatics limits the catalytic partial oxidation (CPOX) of diesel fuel into a H2-rich stream for fuel cells. These species poison traditional supported metal catalysts because they adsorb strongly to electron dense metal clusters and promote the formation of carbon on the surface. Therefore, it is logical to spatially distribute an active metal into the lattice of a chemically and thermally stable material to create an active catalyst surface that is less likely to accumulate carbon or be deactivated by sulfur. In this work, Rh metal only and Rh + Sr …

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Optimum Energy Allocation For Detection In Wireless Sensor Networks, Krishna Kishore Gunturu Jan 2007

Optimum Energy Allocation For Detection In Wireless Sensor Networks, Krishna Kishore Gunturu

LSU Master's Theses

The problem of binary hypothesis testing in a wireless sensor network is studied in the presence of noisy channels and for non-identical sensors. We have designed a mathematically tractable fusion rule for which optimal energy allocation for individual sensors can be achieved. In this thesis we considered two methods for transmitting the sensor observations; binary modulation and M-ary modulation. In binary modulation we are able to allocate the energy among the sensors and protect the individual quantized bits where as the M-ary modulation provides optimum energy allocation only among the sensors. The goal is to design a fusion rule and …

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Urban Stream Stabilization Using Regional Hydraulic Geometry Curves For Bankfull Floodplain Design, Jonathan Edward Fourrier Jan 2007

Urban Stream Stabilization Using Regional Hydraulic Geometry Curves For Bankfull Floodplain Design, Jonathan Edward Fourrier

LSU Master's Theses

The objective of this thesis was to determine the effectiveness of hydraulic geometry curves for designing bankfull floodplains to stabilize urban streams. In stable streams bankfull discharge is contained within the stream's banks. Higher flows spread out onto the floodplain where the water's velocity drops due to the increase in area and vegetation. This dissipation of energy promotes sediment deposition, decreases flow velocity, and reduces channel erosion. In cases like Galbraith Drain where historical gage data are not available and bankfull indicators are not present, a degraded stream's bankfull depth may be estimated with hydraulic geometry curves. Over forty cross …

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Development Of A Biomass Transducer For Automated Microalgal Bioreactors, Amar Shivaram Hegde Jan 2007

Development Of A Biomass Transducer For Automated Microalgal Bioreactors, Amar Shivaram Hegde

LSU Master's Theses

A highly sensitive miniaturized biomass transducer is necessary for continuous and reliable monitoring of the microalgal biomass in a computer controlled, automated microalgal bioreactor. Previous known methods to determine microalgal biomass applicable in these bioreactors are based on single wavelength turbidimetric or fluorescence. The objectives of this research were to (1) determine the light absorption characteristics of some commercially applicable microalgae in the electromagnetic wavelength range of 200-800 nm (2) design and construct a new miniaturized biomass transducer (3) process the transducer output to correlate with the biomass. Wavelength sensitivity analysis was conducted on the commercially important microalgal species - …

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Study Of Demolding Process In Thermal Imprint Lithography Via Numerical Simulation And Experimental Approaches, Zhichao Song Jan 2007

Study Of Demolding Process In Thermal Imprint Lithography Via Numerical Simulation And Experimental Approaches, Zhichao Song

LSU Master's Theses

The objective of present study was to analyze the mechanical behavior of polymer resist during the demolding process, such as stress distribution and evolution; distortion and tilt of microstructures in thermal imprint lithography, a new emerging technique in mass production of micro/nanoscale patterns. One of the most challenging technical issues for thermal imprint lithography is the structural damages during demolding process. Thermal stress, adhesion force and friction force all play important roles in determination of the success of demolding and it is crucial to understand the underlying physics in order to optimize the structure and process design. In present study, …

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Magnetically Induced Release Of Fluorescein Isothiocyanate (Fitc) From Polymer Nanoparticle Composites (Pncs), Michelle Urbina Jan 2007

Magnetically Induced Release Of Fluorescein Isothiocyanate (Fitc) From Polymer Nanoparticle Composites (Pncs), Michelle Urbina

LSU Master's Theses

Magnetically induced drug release can be used as a site-specific, minimally invasive pharmaceutical treatment. Its purpose is to increase the efficacy of drug therapies to diseased or damaged tissue and to decrease the amount of unnecessary damage to healthy, surrounding tissue. To prove the concept of drug release by a magnetic field, this study focused on the release of a fluorescent molecule from magnetic polymeric nanoparticle composites (PNCs) via induction of an alternating current (AC) magnetic field. Fluorescent magnetic PNCs used were 250 ?m or less in size, and were made of poly(methyl methacrylate) (PMMA) containing either the magnetic material …

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Production Well Operations Optimization In Water Distribution System Using Genetic Algorithm, Vineet Katiyar Jan 2007

Production Well Operations Optimization In Water Distribution System Using Genetic Algorithm, Vineet Katiyar

LSU Master's Theses

The City of Chandler, Arizona lies in semi-arid area and the water resources management has been a major concern by the State citizen. There is always a need of optimizing the available water resources when the rate of demand constantly beats the rate of replenishment. In this study we have developed a management model to link the Chandler water distribution model (EPANET) with the Chandler groundwater flow model (MODFLOW) under an optimization framework (Genetic algorithm). The EPANET model supplied by the Chandler city municipal authority has several improper setting (pumping schedules, valves settings, pressure zones etc.). The original model has …

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Pile Capacity Utilization For Bridge Bents Designed Using Simplified Procedures, Md Rubiat Ferdous Jan 2007

Pile Capacity Utilization For Bridge Bents Designed Using Simplified Procedures, Md Rubiat Ferdous

LSU Master's Theses

Bent substructure systems are being used increasingly in bridge construction. Among the various bent systems, pile bents are considered a popular choice due to their effectiveness in reducing time and cost. They are constructed by first driving piles to a specified elevation above the ground surface. Then, a cast-in-place reinforced concrete bent cap ties the piles together at their top end. The current Louisiana Department of Transportation and Development Bridge Design Manual provides guidelines for the structural analysis and construction details for general use in the preparation of plans for pile bents. The manual allows the use of a simplified …

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The Electrodeposition Of Cerium/Copper Prox Catalysts On Metal Foam, James Matthew Faubion Jan 2007

The Electrodeposition Of Cerium/Copper Prox Catalysts On Metal Foam, James Matthew Faubion

LSU Master's Theses

A cerium/copper (Ce/Cu) preferred carbon monoxide (CO) oxidation (PROX) catalyst has been synthesized via electrodeposition onto a metal foam monolith. The catalyst was characterized using ICP, TPRS, TPR and SEM/EDS. Preliminary PROX TPRS evidence in a reaction mixture of 1% CO, 0.5% O2, 40% H2 (bal. Ar.) indicated that the highest activity was seen in a sequential deposition, in which Cu was deposited first. The highest CO oxidation activity was obtained when the Ce concentration in the second step was 0.1 M (resulting in a bulk wt% loading of 0.24 Ce:Cu). SEM/EDS analysis indicated that an increase in ceria loading …

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A Liquid Lens Based On Electrowetting, Jihwan Park Jan 2007

A Liquid Lens Based On Electrowetting, Jihwan Park

LSU Master's Theses

A primary goal of this work is to develop and characterize a novel liquid lens based on electrowetting. A droplet of silicone oil confined in an aqueous solution works as a lens. Electrowetting then controls the shape of the confined silicone oil, and the focal length may be varied upon an applied electric potential. The planar lens design is employed for easy integration of a lens system into a microfluidic device. The achievements of this work are to develop an electrowetting-based planar liquid lens without an off-the-plane electrode structure and to demonstrate the planar liquid lens with variable focal length …

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Study Of Half-Order Bod Reactions, Nicole Plauche Lirette Jan 2007

Study Of Half-Order Bod Reactions, Nicole Plauche Lirette

LSU Master's Theses

Appropriate modeling of Biochemical Oxygen Demand, BOD, is an important part of understanding the character of a wastewater. Much necessary information is gleaned and extracted from the kinetic equation chosen for modeling, especially when a BOD model is included in a dissolved oxygen model. Some information includes the ultimate level of BOD exerted, the rate the BOD demand for dissolved oxygen is exerted, and the critical time at which the minimum level of dissolved oxygen occurs. Although widely used, the first-order kinetic BOD model is not suited for all situations. In some instances, as is the case with constituents found …

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Transcendental Eigenvalue Problems Associated With Vibration, Buckling And Control, Jayaram Subramanian Jan 2007

Transcendental Eigenvalue Problems Associated With Vibration, Buckling And Control, Jayaram Subramanian

LSU Master's Theses

The static and dynamic analysis of structures requires us to obtain solutions of their espective governing differential equations subject to appropriate boundary conditions. The dynamic analysis of non-uniform continuous structures is of primary interest, as most traditional methods take the help of discrete models to analyze them. Well established discrete model methods lead to an algebraic eigenvalue problem, the characteristic equation associated with which is a polynomial. The spectral characteristics of a continuous system nevertheless are represented by transcendental functions and cannot be approximated by polynomials efficiently. Hence finite dimensional discrete models are not capable of predicting the response of …

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On The Stress Analysis Of Bimetallic Packing Rings, Eric Richard Lewis Jan 2007

On The Stress Analysis Of Bimetallic Packing Rings, Eric Richard Lewis

LSU Master's Theses

The purpose of this research is to try and understand hypercompressor packing ring failures better with a view of ultimately reducing or even eliminating their occurrences. In order to gain further understanding of packing ring failures, we seek to obtain an appreciation of the stresses they experience during operation. First we consider a conventional simulation of an axisymmetric packing ring and cup subjected to the typical pressure loading conditions experienced by these components when installed in a hypercompressor cylinder. The key locations of interest are along the bimaterial interface, and in particular at the ends of the interface. These ends …

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Predictive Data Compression Using Adaptive Arithmetic Coding, Claudio Jose Iombo Jan 2007

Predictive Data Compression Using Adaptive Arithmetic Coding, Claudio Jose Iombo

LSU Master's Theses

The commonly used data compression techniques do not necessarily provide maximal compression and neither do they define the most efficient framework for transmission of data. In this thesis we investigate variants of the standard compression algorithms that use the strategy of partitioning of the data to be compressed. Doing so not only increases the compression ratio in many instances, it also reduces the maximum data block size for transmission. The partitioning of the data is made using a Markov model to predict if doing so would result in increased compression ratio. Experiments have been performed on text files comparing the …

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Sigma-Delta Modulation Based Distributed Detection In Wireless Sensor Networks, Dimeng Wang Jan 2007

Sigma-Delta Modulation Based Distributed Detection In Wireless Sensor Networks, Dimeng Wang

LSU Master's Theses

We present a new scheme of distributed detection in sensor networks using Sigma-Delta modulation. In the existing works local sensor nodes either quantize the observation or directly scale the analog observation and then transmit the processed information independently over wireless channels to a fusion center. In this thesis we exploit the advantages of integrating modulation as a local processor into sensor design and propose a novel mixing topology of parallel and serial configurations for distributed detection system, enabling each sensor to transmit binary information to the fusion center, while preserving the analog information through collaborative processing. We develop suboptimal fusion …

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Pre-Treatment Of Dynamically Varying Waste Gas Concentrations Using Activated Carbon Prior To Biofiltration: Effect Of Cycle Length On Degree Of Load Equalization, Kodi L. Collins Jan 2007

Pre-Treatment Of Dynamically Varying Waste Gas Concentrations Using Activated Carbon Prior To Biofiltration: Effect Of Cycle Length On Degree Of Load Equalization, Kodi L. Collins

LSU Master's Theses

Dynamically varying waste gas concentrations pose challenges to the operation and design of air pollution control techniques such as biofilters. Although design approaches are becoming well established for biofilters treating gases containing VOC concentrations that are constant as a function of time, many industrial processes emit gas streams contaminated with volatile organic compounds at concentrations that fluctuate with time. Application of an effective load equalization technique could eliminate some challenges associated with fluctuating pollutant concentrations. Recent research has demonstrated that granular activated carbon (GAC) can serve as a passively controlled system to provide load-equalization as a pre-treatment prior to biofiltration. …

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Oblivious Transfer For Secure Communication, Abhishek Parakh Jan 2007

Oblivious Transfer For Secure Communication, Abhishek Parakh

LSU Master's Theses

Over the past four decades, computational power and algorithmic strategies have advanced tremendously resulting in an enormous increase in the key sizes required for secure cryptosystems such as RSA. At the same time, the electronic devices have grown smaller and portable requiring algorithms running on them to be optimized in size and efficiency while providing security, at least, equivalent to that provided on a typical desktop computer. As a result, the industry is moving towards newer cryptosystems such as ECC and NTRU that are well suited for resource constrained environments. While, ECC claims to provide security equivalent to that of …

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Characterization Of Polyethylene Glycol Hydrogels For Biomedical Applications, Anushree Datta Jan 2007

Characterization Of Polyethylene Glycol Hydrogels For Biomedical Applications, Anushree Datta

LSU Master's Theses

Polyethylene glycol is one of the most widely used synthetic materials for biomedical applications. Its biocompatibility, flexibility, and 'stealth' properties make it ideal for use in drug delivery applications. The main objective of this paper is to characterize the structural and mass transfer properties of polyethylene glycol hydrogels for applications in drug delivery and biological immobilization. Swelling behavior of the gels was studied to determine the mesh size, and other significant structural parameters of the gel. For accurate design of drug delivery device, along with network design, mathematical modeling of release profiles was performed. The study of PEG hydrogels was …

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Quasi Group Based Crypto-System, Maruti Venkat Kartik Satti Jan 2007

Quasi Group Based Crypto-System, Maruti Venkat Kartik Satti

LSU Master's Theses

For electronic commerce and other applications it is required to encrypt data that is transmitted over an unsecured channel. The data is encrypted/randomized using a key. Algorithms such as DES and ECC randomize the data such that un-authorized user cannot decrypt it .This thesis presents a practical implementation of a quasi group based multilevel, indexed scrambling transformation for use in signal encryption. Results of experiments with text and speech scrambling are presented. It is shown that the quasi group transformation maximizes the entropy at the output, which is desirable for a good system. This system provides extremely large group of …

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Characterization And Analysis Of Hybrid Electronic Materials For Molecular Based Devices, Sathish Thiruvengadam Jan 2007

Characterization And Analysis Of Hybrid Electronic Materials For Molecular Based Devices, Sathish Thiruvengadam

LSU Master's Theses

The goal of this work is to characterize and to analyze hybrid electronic materials (HEMs) using fluorescence (FL) spectroscopy and conductive probe-atomic force microscopy (CP-AFM) in order to investigate the electrical and optical properties of these materials. Currently, research efforts to characterize novel organic materials for the determination of molecular level transport properties are of great interest.[6] One of the most interesting organic materials is the porphyrin molecule, which exhibits behavior useful for memory applications.[4] Colloidal CdS quantum dots (Q-CdS) capped with dioctyl sulfosuccinate (AOT) and thiol functionalized porphyrin molecules are explored for their potential application to next-generation hybrid electronic …

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Saltwater Intrusion Simulation In Heterogeneous Aquifer Using Lattice Boltzmann Method, Borja Servan Camas Jan 2007

Saltwater Intrusion Simulation In Heterogeneous Aquifer Using Lattice Boltzmann Method, Borja Servan Camas

LSU Master's Theses

This study develops a saltwater intrusion simulation model using a lattice Boltzmann method (LBM) in a two-dimensional coastal confined aquifer. The saltwater intrusion is described by density-dependent groundwater flow and mass transport equations, where a freshwater-saltwater mixing zone is considered. The problem is formulated in terms of hydraulic head instead of pressure, which is recommended in those cases where static pressures dominate to reduce computational cost. The aquifer heterogeneity is explicitly a function of the speed of sound, relaxation parameter and time steps in the LBM. This study explores the equivalent squared sound speed to deal with the spatial-temporal heterogeneity …

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Manufacturing, Testing And Modeling Of Advanced Filament Wound Grid Stiffened Composite Cylinders, Ravi Chaitanya Velamarthy Jan 2007

Manufacturing, Testing And Modeling Of Advanced Filament Wound Grid Stiffened Composite Cylinders, Ravi Chaitanya Velamarthy

LSU Master's Theses

Advanced Grid Stiffened (AGS) structures are a kind of FRP composites that are being extensively used in many engineering fields because of their inherent advantages. Hence it is of utmost importance to understand the basic mechanism of these structures in order to develop better models and to find ways to improve their efficiency. This thesis discusses the manufacturing technology used viz. the filament winding technique to fabricate grid stiffened composite cylinders. A step by step procedure of the fabrication process of grid cylinders is explained. The confinement effectiveness of the AGS cylinders is evaluated by filling them with concrete and …

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Assessment Of Dynamic Contrast Enhanced Mri For The Early Detection Of Treatment Response In Human Advanced Hepato-Cellular Carcinoma, Yun Jiang Jan 2007

Assessment Of Dynamic Contrast Enhanced Mri For The Early Detection Of Treatment Response In Human Advanced Hepato-Cellular Carcinoma, Yun Jiang

All ETDs from UAB

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has been shown to be a potentially useful tool for early prediction of tumor response to antiangiogenesis agents. In this study, the technique was used to evaluate the chemotherapeutic drug doxorubicin with or without the tyrosine kinase inhibitor sorafenib in patients with advanced hepatocellular carcinoma (HCC). Five male patients (ages 50 to 78 years, average age 67  8 years) were studied with serial T1-weighted DCE-MRI to measure the alteration of perfusion parameters of tumors in response to the treatment. All patients received doxorubicin at dose of 60 mg/m2 intravenously every 21 days. Among …

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