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2009

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Articles 3421 - 3450 of 4158

Full-Text Articles in Engineering

Laboratory Characterization Of Geogrid-Reinforced Unbound Granular Material For Use In Flexible Pavement Structures, Gael Souci Jan 2009

Laboratory Characterization Of Geogrid-Reinforced Unbound Granular Material For Use In Flexible Pavement Structures, Gael Souci

LSU Master's Theses

This thesis documents and summarizes research and background information carried on geogrid reinforced base course in pavement design. Research was experimental carried through Repeated Load Triaxial (RLT) tests at the Louisiana Transportation Research Center. The experimental tests were performed to observe the benefit of the geogrid as well as to differentiate between geogrid location, geometry and tensile modulus of the various geogrid. Experiments were also carried to further describe the Shakedown Theory and its use for characterization of base course materials. The experimental results showed that there was a benefit in placing the geogrid within the aggregate specimen. There were …

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Third Order Cmos Decimator Design For Sigma Delta Modulators, Hemalatha Mekala Jan 2009

Third Order Cmos Decimator Design For Sigma Delta Modulators, Hemalatha Mekala

LSU Master's Theses

A third order Cascaded Integrated Comb (CIC) filter has been designed in 0.5μm n-well CMOS process to interface with a second order oversampling sigma-delta ADC modulator. The modulator was designed earlier in 0.5μm technology. The CIC filter is designed to operate with 0 to 5V supply voltages. The modulator is operated with ±2.5V supply voltage and a fixed oversampling ratio of 64. The CIC filter designed includes integrator, differentiator blocks and a dedicated clock divider circuit, which divides the input clock by 64. The CIC filter is designed to work with an ADC that operates at a maximum oversampling clock …

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Thermomechanical Modeling And Optimization Of Friction Stir Welding, Manthan Malde Jan 2009

Thermomechanical Modeling And Optimization Of Friction Stir Welding, Manthan Malde

LSU Master's Theses

This thesis research implemented an existing thermomechanical model of friction stir welding process, and studied the surrogate model-based optimization approach to obtain optimal process parameters for the modeled friction stir welding process. As an initial step, the thermomechanical model developed by Zhu and Chao for friction stir welding of 304L stainless steel was replicated using ANSYS. The developed model was then used to conduct parametric studies to understand the effect of various input parameters like total rate of heat input, welding speed and clamping location on temperature distribution and residual stress in the workpiece. With the data from the simulated …

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Gas Transfer In Air-Lifts Used To Recirculate Aquaculture Systems, Ryan Anthony Hearn Jan 2009

Gas Transfer In Air-Lifts Used To Recirculate Aquaculture Systems, Ryan Anthony Hearn

LSU Master's Theses

The following studies were conducted to determine hydraulic, aeration, and degasification characteristics associated with various air-lift pumps. The first study presented data on a 20.3 cm air-lift used to support adult Yellowtail broodstock (Seriola lalandi) in an oligotrophic warmwater marine RAS (recirculating aquaculture system). Empirical relationships were used to estimate actual oxygen and carbon dioxide mass transfer rates (AOTR & ACTR) as the inlet oxygen or carbon dioxide concentrations were perturbed under lift heights of 30.5, 38.1, and 45.7 cm. Transfer rates, kg of constituent per day, were found to be dependent on air injection depth and volume, aqueous gas …

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Neck Muscles Activity And Upper Body Extremity Angles In Dynamic Overhead Lifting, Mohamed Wassim Mokrani Jan 2009

Neck Muscles Activity And Upper Body Extremity Angles In Dynamic Overhead Lifting, Mohamed Wassim Mokrani

LSU Master's Theses

Injuries of the neck and shoulders are common among workers who perform overhead tasks. In order to develop an injury-free working environment with regards to occupational musculoskeletal stress, it is pivotal to understand the pathophysiology of mechanical stress on the musculoskeletal system. The objective of this research was to study the effect of overhead lifting on the sternocleidomastoid and upper Trapezius muscles. Upper body joint angles were also analyzed using APAS during the overhead lifting. This study was conducted using two devices. The set of equipment incorporates an electromyography device, and the APAS. Two electrodes were placed at the muscle …

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Prioritization Of Safety Countermeasures For The State Of Louisiana Using Fuzzy Inference Systems, Meisam Akbarzadeh Jan 2009

Prioritization Of Safety Countermeasures For The State Of Louisiana Using Fuzzy Inference Systems, Meisam Akbarzadeh

LSU Master's Theses

In this study a fuzzy inference system is proposed for prioritization of countermeasures aimed at improving safety in the state of Louisiana. Countermeasures are prioritized based on their collective performance on cost, expected crash reduction and the severity of the problem they address. These three decision parameters can have six permutations in terms of their relative importance in decision making. In order to make the prioritization procedure handier for decision makers, the inference system is capable of being run under all six possible cases. Current safety standards influence the importance attached to crash reduction performance and severity of the problem …

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A Simulation-Based Evaluation Of Alternative Initial Responses To Gas Kicks During Managed Pressure Drilling Operations, Majid Davoudi Jan 2009

A Simulation-Based Evaluation Of Alternative Initial Responses To Gas Kicks During Managed Pressure Drilling Operations, Majid Davoudi

LSU Master's Theses

Managed pressure drilling (MPD) is an adaptation of conventional drilling that has been developed to manage and control subsurface pressures in the well in order to minimize specific drilling problems. The constant bottom hole pressure approach (CBHP) is a versatile method of MPD, where a closed annulus allows initial responses to kicks other than simply shutting in the well. The objective of this research was to identify and evaluate the best initial response to gas kicks taken during drilling as a basis for developing reliable well control procedures for CBHP operations. Nine non-circulating and circulating responses (NCRs and CRs) were …

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Assessment Of Target Purity Difference For A Louisiana Sugar Mill, Luz Stella Polanco Jan 2009

Assessment Of Target Purity Difference For A Louisiana Sugar Mill, Luz Stella Polanco

LSU Master's Theses

The main goals of a “raw” sugarcane factory are to have an efficient profitable operation with the required sugar quality and maximum sugar recovery. The loss of sugar to final molasses accounts for 45 to 47% of the total sugar losses. An estimation of the average cost of the manufacturing losses for the 2007 harvest season was approximately $9 million – the sugar lost to the final molasses accounts for approximately 50% of this cost (Salassi, 2008). For final molasses, the “Target Purity” (or equilibrium purity) refers to the minimum level of sucrose that theoretically remains in solution for a …

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Poly (D, L-Lactide-Co-Glycolide) And Chitosan Particles For Oral Delivery Of Model Lipophilic Vitamin, Abitha Murugeshu Jan 2009

Poly (D, L-Lactide-Co-Glycolide) And Chitosan Particles For Oral Delivery Of Model Lipophilic Vitamin, Abitha Murugeshu

LSU Master's Theses

Improved oral delivery of vitamins and antioxidants via food, beverages or supplements can be achieved by encapsulation of the bioactive component in biodegradable and biocompatible colloidal and nanoparticle systems. Mucoadhesive chitosan/Poly (D, L-lactide-co-glycolide) particles were investigated as a means to control the release of bioactive compounds such as vitamin E in the gastrointestinal (GI) tract. Chitosan/PLGA particles with entrapped alpha-tocopherol at different initial loadings were synthesized by emulsion evaporation method, compared against PLGA particles in terms of their physical properties, stability, and gastrointestinal release profiles. Chi/PLGA particles of 250 ± 8.9 nm with a zeta potential of 61 ± 3.1 …

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Laser Assisted Friction Stir Welding: Finite Volume Method And Metaheuristic Optimization, Shivani Daftardar Jan 2009

Laser Assisted Friction Stir Welding: Finite Volume Method And Metaheuristic Optimization, Shivani Daftardar

LSU Master's Theses

Friction Stir Welding (FSW) is a solid state joining process that uses a non-consumable rotating welding tool to generate frictional heat at the welding location. Large forces are required to produce friction between the welding tool and the work piece which increases the wear rate of the welding tool in welding materials with high melting temperature. Several different approaches have been developed to address this problem. This thesis focuses on a new modification of friction stir welding, called Laser Assisted Friction Stir Welding, a process developed in the last decade. This process uses laser energy to preheat the work piece …

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Bilateral Filter In Image Processing, Ming Zhang Jan 2009

Bilateral Filter In Image Processing, Ming Zhang

LSU Master's Theses

The bilateral filter is a nonlinear filter that does spatial averaging without smoothing edges. It has shown to be an effective image denoising technique. It also can be applied to the blocking artifacts reduction. An important issue with the application of the bilateral filter is the selection of the filter parameters, which affect the results significantly. Another research interest of bilateral filter is acceleration of the computation speed. There are three main contributions of this thesis. The first contribution is an empirical study of the optimal bilateral filter parameter selection in image denoising. I propose an extension of the bilateral …

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Hearing Assessment Of Forest Loggers, Antonio A. Fonseca Jan 2009

Hearing Assessment Of Forest Loggers, Antonio A. Fonseca

LSU Master's Theses

Forest logging is the process in which trees are cut down for forest management and/or timber harvest. According to OSHA, logging is the most dangerous occupation in the United States. It consistently represents one of the most hazardous industries, with a fatality rate more than 21 times higher than the rate for all workers in the United States. Yet, little research has been performed to determine the long term effect of noise on forest loggers. OSHA regulations state that the maximum permissible hearing in an 8 hour shift should not exceed 90 dB. Occupational noise exposure is recognized as a …

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Assessing The Accuracy Of Task Time Prediction Of An Emerging Human Performance Modeling Software - Cogtool, Oluwakemi Damilola Adio Jan 2009

Assessing The Accuracy Of Task Time Prediction Of An Emerging Human Performance Modeling Software - Cogtool, Oluwakemi Damilola Adio

LSU Master's Theses

There is a need for a human performance modeling tool which not only has the ability to accurately estimate skilled user task time for any interface design, but can be used by modelers with little or no programming knowledge and at a minimal cost. To fulfill this need, this research investigated the accuracy of task time prediction of a modeling tool – CogTool - on two versions of an interface design used extensively in the petrochemical industry – DeltaV. CogTool uses the KeyStroke Level Model (KLM) to calculate and generate time predictions based on specified operators. The data collected from …

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Realtime Reservoir Characterization And Beyond: Cyber-Infrastructure Tools And Technologies, Yaakoub Youssef El-Khamra Jan 2009

Realtime Reservoir Characterization And Beyond: Cyber-Infrastructure Tools And Technologies, Yaakoub Youssef El-Khamra

LSU Master's Theses

The advent of the digital oil _x000C_eld and rapidly decreasing cost of computing creates opportunities as well as challenges in simulation based reservoir studies, in particular, real-time reservoir characterization and optimization. One challenge our e_x000B_orts are directed toward is the use of real-time production data to perform live reservoir characterization using high throughput, high performance computing environments. To that end we developed the required tools of parallel reservoir simulator, parallel ensemble Kalman _x000C_lter and a scalable work ow manager. When using this collection of tools, a reservoir modeler is able to perform large scale reservoir management studies in short periods …

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Phosphorus Dynamics In The Marshland Upwelling System, Dhaval Shirish Shah Jan 2009

Phosphorus Dynamics In The Marshland Upwelling System, Dhaval Shirish Shah

LSU Master's Theses

The Marshland Upwelling System (MUS) is an alternative onsite wastewater treatment technology designed to utilize the natural ecology of saltwater marshes to remove human-borne contaminants. Previous research has assessed the ability of MUS to remove both total and orthophosphate. Studies have also indicated a clear zone of phosphorus (P) saturation occurring in MUS soils. Laboratory column study was performed to accomplish the objectives of this study which were to: 1) determine the fate and fractionation of phosphorus in the soil matrix, 2) understand sorption kinetics and determine phosphorus sorption potential of wetland soils in retaining phosphorus in the MUS, 3) …

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Hydro Mechanical Behavior Of Unsaturated Soil Subjected To Drying, Dev Raj Pokhrel Jan 2009

Hydro Mechanical Behavior Of Unsaturated Soil Subjected To Drying, Dev Raj Pokhrel

LSU Master's Theses

The literature of unsaturated soils in terms of hydraulic and mechanical behavior is reviewed. The hydro- mechanical behavior of unsaturated soil was studied using experimental investigation and numerical simulation of 1D and 2D modeling in HYDRUS software. Low plasticity silty clay (CL) and sand bentonite mixed soil SB (5% and 2% bentonite) specimens were investigated. Soil water characteristics curve (SWCC) tests were carried out in CL sample along with shear wave velocity measurement test using bender element (BE). The influence of moisture variation on specimens was investigated to see its impact on suction and on stiffness of soil. Similarly, the …

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Two-Dimensional Microscanners With T-Shaped Hinges And Piezoelectric Actuators, Wenyu Song Jan 2009

Two-Dimensional Microscanners With T-Shaped Hinges And Piezoelectric Actuators, Wenyu Song

LSU Master's Theses

For a wide range of application areas such as medical instruments, defense, communication networks, industrial equipment, and consumer electronics, microscanners have been a vibrant research topic. Among various fabrication methodologies, MEMS (microelectromechanical system) stands out for its small size and fast response characteristics. In this thesis, piezoelectric actuation mechanism is selected because of its low voltage and low current properties compared with other mechanisms, which are especially important for the target application of biomedical imaging. Although 1- and 2-dimensional microscanners with piezoelectric actuators have been studied by several other groups, this thesis introduces innovative improvements in design of the piezoelectric …

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Downhole Water Loop (Dwl) Well Completion For Water Coning Control --- Theoretical Analysis, Lu Jin Jan 2009

Downhole Water Loop (Dwl) Well Completion For Water Coning Control --- Theoretical Analysis, Lu Jin

LSU Master's Theses

The Thesis is an analytical and numerical analysis of a new method for completing and producing oil wells affected by water coning. The method enables producing oil with no or minimal water cut while keeping the water subsurface with downhole water loop (DWL) installation. Typically, a DWL well is triple-completed in the oil and water zones with the three completions separated by parkers. The top completion produces oil to the surface while the middle and bottom completions drain from and inject into the bottom water zone, respectively. Segregated-inflow operation of DWL well requires keeping the production and drainage-injection rates below …

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Secure Distributed Detection In Wireless Sensor Networks Via Encryption Of Sensor Decisions, Venkata Sriram Siddhardh Nadendla Jan 2009

Secure Distributed Detection In Wireless Sensor Networks Via Encryption Of Sensor Decisions, Venkata Sriram Siddhardh Nadendla

LSU Master's Theses

We consider the problem of binary hypothesis testing using a distributed wireless sensor network. Identical binary quantizers are used on the sensor's observations and the outputs are encrypted using a probabilistic cipher. The third party (enemy) fusion centers are unaware of the presence of the probabilistic encipher. We find the optimal (minimum-probability-of-error) fusion rule for the ally (friendly) fusion center subject to a lower bound on the the probability of error for the third-party fusion centers. To obtain the minimum probability of error, we first prove the quasi-convexity of error probability with respect to the sensor's threshold for a given …

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Development And Thermal Characterization Of Cellulose/Clay Nanocomposites, Christopher D. Delhom Jan 2009

Development And Thermal Characterization Of Cellulose/Clay Nanocomposites, Christopher D. Delhom

LSU Master's Theses

Cotton is the most important textile fiber for apparel use and is preferred to synthetic fibers for reasons such as comfort and feel. Cotton may also be used to produce the regenerated cellulose fibers, such as lyocell and viscose, which have numerous textile applications. A major drawback of cotton, and other cellulosic fibers, is its inherent ability to burn. Many finishes have been developed to impart flame resistance to cotton. These finishes have limited use in textiles for apparel due to problems with the finish not being durable during laundering and increasing the susceptibility of the fabric to wear. Most …

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Geometric Capacity Studies For Dtv Transmitter Identification By Using Kasami Sequences, Xiaoyu Feng Jan 2009

Geometric Capacity Studies For Dtv Transmitter Identification By Using Kasami Sequences, Xiaoyu Feng

LSU Master's Theses

The transmitter identification of the DTV systems becomes crucial nowadays. Transmitter identification (TxID, or transmitter fingerprinting) technique is used to detect, diagnose and classify the operating status of any radio transmitter of interest. A pseudo random sequence was proposed to be embedded into the DTV signal before transmission. Thus, the transmitter identification can be realized by invoking the cross-correlation functions between the received signal and the possible candidates of the pseudo random sequences. Gold sequences and Kasami sequences are two excellent candidates for the transmitter ID sequences as they provide a large family of nearly-orthogonal codes. In order to investigate …

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Effects Of Physical And Mental Tasks On Heart Rate Variability, Satya Anasuya Paritala Jan 2009

Effects Of Physical And Mental Tasks On Heart Rate Variability, Satya Anasuya Paritala

LSU Master's Theses

Demands at work are associated with an increased risk of cardio vascular diseases, but little is known about its underlying connection. The purpose of this study was to evaluate the effects of physical and mental tasks that induced stress, on Heart Rate Variability (HRV). Another aim was to observe the trends in subjective workload ratings in conjunction with the physiological response of the heart and also to assess the comfort level of the participants while wearing the heart rate monitor and performing tasks. Heart rate was recorded while at rest and while performing the tasks. Subjective workload ratings were obtained …

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Passenger Car Equivalents Of Trucks Under Lane Restriction And Differential Speed Limit Policies On Four Lane Freeways, John Stanley Jan 2009

Passenger Car Equivalents Of Trucks Under Lane Restriction And Differential Speed Limit Policies On Four Lane Freeways, John Stanley

LSU Master's Theses

Lane restriction for trucks and differential speed limits for trucks and cars are becoming more common and feasible policies to improve the efficiency and safety of a freeway. It is believed that passenger car equivalents for trucks are impacted by these non typical freeway operating conditions, which are not explicitly addressed by the latest edition of the Highway Capacity Manual. Using simulated and real world data an elevated 18- mile four lane freeway was modeled under the restriction policies. The section which was used as a test bed was simulated under various control variables. Some of the control variables used …

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Ternary To Binary Converter Design In Cmos Using Multiple Input Floating Gate Mosfets, Josephine Ratna Sathiaraj Jan 2009

Ternary To Binary Converter Design In Cmos Using Multiple Input Floating Gate Mosfets, Josephine Ratna Sathiaraj

LSU Master's Theses

In this work, a ternary to binary converter circuit is designed in 0.5μm n-well CMOS technology. The circuit takes two inputs corresponding to the ternary bits and gives four outputs, which are the binary equivalent bits of the ternary inputs. The ternary inputs range from (-1,-1)3 to (1,1) 3 which are decimal -4 to 4 and the four binary output bits are the sign bit (SB), most significant bit (MSB), second significant bit (SSB) and the least significant bit (LSB). The ternary inputs (-1, 0 and 1) are represented in terms of voltages of -3V, 0V and 3V. Multiple …

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Numerical Modeling For Long Term Performance Of Soil-Bentonite Cut-Off Walls In Unsaturated Soil Zone, Sukanta Chakraborty Jan 2009

Numerical Modeling For Long Term Performance Of Soil-Bentonite Cut-Off Walls In Unsaturated Soil Zone, Sukanta Chakraborty

LSU Master's Theses

ABSTRACT The construction practices of containment walls are extremely important in this competitive economic market, but development is limited. Unsaturated zone is an integral part of the geotechnical problems, as it affects on any kind of soils structures. The unsaturated zone plays significant role in many aspects of water flow and contaminant transport, including containment system such as: cut-off walls, infiltration, soil moisture storage, evaporation, plant water uptake, ground water recharge, erosion, and runoff. This research focuses on the hydraulic sustainability and performance of soil-bentonite cutoff walls (Britton et al, 2004) models showing hydraulic behavior of barrier walls. The cutoff …

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Dynamic Behavior Of Unsaturated Soils, Prathima Alla Jan 2009

Dynamic Behavior Of Unsaturated Soils, Prathima Alla

LSU Master's Theses

The behavior of unsaturated soils is different from the behavior of saturated soil deposits. Unsaturated soils have more than two phases; the pore water pressure in unsaturated soils is negative. The behavior of unsaturated soil when a dynamic loading such as an earthquake loading is imposed on them, the susceptibility of lab tested soils to liquefaction is investigated in this study. As the phenomenon of liquefaction occurs only in the case of saturated soil deposits, the behavior of unsaturated soil under these conditions is investigated. Sand and silty sand are used in this study, wetting and drying soil water characteristic …

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Mechanistic Foam Modeling And Simulations: Gas Injection During Surfactant-Alternating-Gas Processes Using Foam-Catastrophe Theory, Ali Afsharpoor Jan 2009

Mechanistic Foam Modeling And Simulations: Gas Injection During Surfactant-Alternating-Gas Processes Using Foam-Catastrophe Theory, Ali Afsharpoor

LSU Master's Theses

The use of foam for mobility control is a promising means to improve sweep efficiency in subsurface applications such as improved/enhanced oil recovery and aquifer remediation. Foam can be introduced into geological formations by injecting gas and surfactant solutions simultaneously or alternatively. Alternating gas and surfactant solutions, which is often referred to as surfactant-alternating-gas (SAG) process, is known to effectively create fine-textured strong foams due to fluctuation in capillary pressure. Recent studies show that foam rheology in porous media can be characterized by foam-catastrophe theory which exhibits three foam states (weak-foam, strong-foam, and intermediate states) and two strong-foam regimes (high-quality …

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Atomistic Simulations Of Lipid Bilayers In The Presence Of Dimethylsulfoxide, Raghava Alapati Jan 2009

Atomistic Simulations Of Lipid Bilayers In The Presence Of Dimethylsulfoxide, Raghava Alapati

LSU Master's Theses

In a typical cryopreservation protocol, the system to be preserved is first equilibrated with chemicals known as cryoprotective agents (CPAs). CPAs have been shown to alleviate cell damage from either the solute effects or the formation of intracellular ice during the subsequent freezing process. Thus, an extensive body of literature reporting the effects of CPAs on cellular systems has been accumulated over the last 50 years; detailing largely experimental interactions between cell systems and chemicals. Recent advances in computational methodology now offer an additional dimension in our ability to understand the molecular interactions between cell membranes, idealized as lipid bilayers …

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Fundamental Characterization Of Unbound Base Course Materials Under Cyclic Loading, Aaron Matthew Austin Jan 2009

Fundamental Characterization Of Unbound Base Course Materials Under Cyclic Loading, Aaron Matthew Austin

LSU Master's Theses

ABSTRACT Pavements are a layered system each layer distinguished by different materials as required by traffic and subgrade conditions. A base course is an intermediate layer constructed of high quality stone aggregates: quality based on physical properties such as gradation, hardness, and texture. Although indicative of performance, physical properties do not directly measure performance. This thesis presents the results of a comprehensive experimental testing program that was conducted to examine the behavior of unbound granular base materials under cyclic loading and to evaluate the effect of the stress level and moisture content on strain behavior. Three base materials, namely granite, …

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Biocompatible/ Bioresorbable Polymer Based Silver Nanaomaterial Coatng For Chronic Indwelling Medical Devices And Bioscaffolds For Tissue Regrowth, Ammar T. Qureshi Jan 2009

Biocompatible/ Bioresorbable Polymer Based Silver Nanaomaterial Coatng For Chronic Indwelling Medical Devices And Bioscaffolds For Tissue Regrowth, Ammar T. Qureshi

LSU Master's Theses

The objective of this study is to synthesize and characterize antimicrobial, bio-polymer based silver nanomaterials composite coatings, for use in chronic indwelling medical devices, and bioscaffolds. The coatings and bioscaffolds are comprised of novel biomass mediated silver nano particles (SNP) that are biocompatible, highly concentrated, highly pure, cost-effective, polydispersed and compatible with a range of polymer systems applicable for use with existing chronic indwelling medical devices. This thesis is divided into three main chapters. In Chapter 1, detailed review on the need for antimicrobial nanocomposite coatings for chronic indwelling medical devices along with different SNP synthesis and characterization methods is …

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