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Articles 2011 - 2040 of 2820
Full-Text Articles in Engineering
Nanoidentation Behavior Of Clay Minerals And Clay-Based Nonstructured Multilayers, Zhongxin Wei
Nanoidentation Behavior Of Clay Minerals And Clay-Based Nonstructured Multilayers, Zhongxin Wei
LSU Doctoral Dissertations
Clay minerals, ubiquitous in the geosphere, are hydrous layered silicates or phyllosilicates that are made of nanometer-thick 2:1 or 1:1 layers. Understanding their mechanical properties of clay minerals is of vital importance to a variety of disciplines, such as geomechanics, geophysics, mineral physics, and nanocomposites. Owing to their complex crystal structure and size, however, accurate determination of their mechanical properties is a significant challenge. This dissertation presents the first research effort to study systematically the fundamental mechanical properties along the c-axis (e.g., elastic modulus, hardness) of a wide range of phyllosilicates with varying crystal structure and chemical compositions. To explore …
Supercritical Pyrolysis Of 1-Methylnaphthalene, Michelle Somers Walker
Supercritical Pyrolysis Of 1-Methylnaphthalene, Michelle Somers Walker
LSU Doctoral Dissertations
Fuels used in future high-speed jet aircraft will act as coolants to absorb excess heat produced by the engine, exposing the fuel to elevated temperatures and pressures beyond the fuel’s critical point before entering the combustion environment. Fuels used in this capacity are subject to pyrolysis reactions in the supercritical environment, forming polycyclic aromatic hydrocarbons (PAH) and eventually carbonaceous solids, a disastrous effect for aircraft operation. Thus, it is important to understand how different components of jet fuel will react in the supercritical pyrolysis environment, particularly if their reactions will lead to PAH and/or carbonaceous solids. To better understand these …
Dynamics Of Vortical Structures In A Low-Blowing-Ratio Pulsed Transverse Jet, Clementine Vezier
Dynamics Of Vortical Structures In A Low-Blowing-Ratio Pulsed Transverse Jet, Clementine Vezier
LSU Master's Theses
Large Eddy Simulation is used to study the interaction of a 35° inclined jet into a crossflow. Steady state cases, with a BR ranging from 0.150 to 1.2, are firstly examined to understand the dynamics of the flow field. Iso-surface of Laplacian of the pressure, vorticity contour and velocity fields highlight the presence of four main vortical structures: shear layer vortices, horse-shoes vortices, wake vortices and CRVP. Qualitative comparisons are performed between simulations and experiments. The dynamics of the flow field is next characterized by pulsing the jet. The studied pulsed cases have same low BR and duty cycle respectively …
Dynamical Investigation Of A Manned Capsule/Tether Re-Entry System, Jeffrey Alan Kornuta
Dynamical Investigation Of A Manned Capsule/Tether Re-Entry System, Jeffrey Alan Kornuta
LSU Master's Theses
The use of tethers in space has an exciting promise in future astronautical applications, with the possibility of providing more sophisticated functionality to satellites and spacecraft. Some of these applications include adjoining satellites, creating microgravity environments, generating power, and transferring momentum between spacecraft. The focus of this project is to investigate the possible reduction in convective heat flux and temperatures on a manned capsule as a result of re-entry with an attached momentum exchange tether, including how various tether parameters affect these results. Using a “bottom-up” approach by modeling the system as a series of lumped masses and rigid rods …
Enhancing Reductive Dechlorination Of Chlorinated Ethenes And Ethanes In A Natural Treatment System, Caroline Burda
Enhancing Reductive Dechlorination Of Chlorinated Ethenes And Ethanes In A Natural Treatment System, Caroline Burda
LSU Master's Theses
Chlorinated solvent contamination continues to plague sites around the world. In many cases, lower chlorinated daughter products build up and remain in ground waters and soils. A Bio-Filter/Phytobed (BFP) system has been developed to replace a traditional pump and treat technology currently operating at the ReSolve Superfund site in North Dartmouth, MA. Pilot scale testing at the facility displayed a significant acclimation period prior to microbial dechlorination, as well as delayed degradation of chlorinated ethanes. Microcosm studies suggest that acidic conditions, possibly created by the peat mixture used to construct the bio-filter, inhibited bacterial growth. The neutralization of trench pH …
Advanced Microwave Technology For Biodiesel Feedstock Processing, Beatrice G. Terigar
Advanced Microwave Technology For Biodiesel Feedstock Processing, Beatrice G. Terigar
LSU Master's Theses
The goal of this work was to assist in overcoming the most important bottlenecks in the biodiesel production chain: to improve the biodiesel production process (oil extraction and esterification) using advanced microwave technologies from traditional and alternative feedstock; and identify the important characteristics of an alternative, high oil yield crop (TT). Dielectric properties of two feedstocks, soybean and rice bran were measured in presence of several solvents at different ratios, temperature and frequency. Results indicated that dielectric properties are ratio, temperature, frequency and solvent type dependent. Quasi-linear relationship using second order logarithmic transformation of the data provided a reliable estimator …
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 …
Third Order Cmos Decimator Design For Sigma Delta Modulators, Hemalatha Mekala
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 …
Thermomechanical Modeling And Optimization Of Friction Stir Welding, Manthan Malde
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 …
Gas Transfer In Air-Lifts Used To Recirculate Aquaculture Systems, Ryan Anthony Hearn
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 …
Neck Muscles Activity And Upper Body Extremity Angles In Dynamic Overhead Lifting, Mohamed Wassim Mokrani
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 …
Prioritization Of Safety Countermeasures For The State Of Louisiana Using Fuzzy Inference Systems, Meisam Akbarzadeh
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 …
A Simulation-Based Evaluation Of Alternative Initial Responses To Gas Kicks During Managed Pressure Drilling Operations, Majid Davoudi
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 …
Assessment Of Target Purity Difference For A Louisiana Sugar Mill, Luz Stella Polanco
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 …
Poly (D, L-Lactide-Co-Glycolide) And Chitosan Particles For Oral Delivery Of Model Lipophilic Vitamin, Abitha Murugeshu
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 …
Laser Assisted Friction Stir Welding: Finite Volume Method And Metaheuristic Optimization, Shivani Daftardar
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 …
Bilateral Filter In Image Processing, Ming Zhang
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 …
Hearing Assessment Of Forest Loggers, Antonio A. Fonseca
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 …
Assessing The Accuracy Of Task Time Prediction Of An Emerging Human Performance Modeling Software - Cogtool, Oluwakemi Damilola Adio
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 …
Realtime Reservoir Characterization And Beyond: Cyber-Infrastructure Tools And Technologies, Yaakoub Youssef El-Khamra
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 …
Phosphorus Dynamics In The Marshland Upwelling System, Dhaval Shirish Shah
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) …
Hydro Mechanical Behavior Of Unsaturated Soil Subjected To Drying, Dev Raj Pokhrel
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 …
Two-Dimensional Microscanners With T-Shaped Hinges And Piezoelectric Actuators, Wenyu Song
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 …
Downhole Water Loop (Dwl) Well Completion For Water Coning Control --- Theoretical Analysis, Lu Jin
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 …
Secure Distributed Detection In Wireless Sensor Networks Via Encryption Of Sensor Decisions, Venkata Sriram Siddhardh Nadendla
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 …
Development And Thermal Characterization Of Cellulose/Clay Nanocomposites, Christopher D. Delhom
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 …
Geometric Capacity Studies For Dtv Transmitter Identification By Using Kasami Sequences, Xiaoyu Feng
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 …
Effects Of Physical And Mental Tasks On Heart Rate Variability, Satya Anasuya Paritala
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 …
Passenger Car Equivalents Of Trucks Under Lane Restriction And Differential Speed Limit Policies On Four Lane Freeways, John Stanley
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 …
Ternary To Binary Converter Design In Cmos Using Multiple Input Floating Gate Mosfets, Josephine Ratna Sathiaraj
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 …