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Articles 1 - 30 of 34
Full-Text Articles in Engineering
Eigenvalue Optimization And Its Applications In Buckling And Vibration, Srinivas Gopal Krishna
Eigenvalue Optimization And Its Applications In Buckling And Vibration, Srinivas Gopal Krishna
LSU Doctoral Dissertations
Eigenvalue problems are of immense interest and play a pivotal role not only in many fields of engineering but also in pure and applied mathematics. An in-depth understanding of this class of problems is a pre-requisite for vibration and buckling analyses of structures. Design optimization of structures to prevent failure due to instability (bucking) and vibration introduces the problem of determining optimal physical parameters such that load carrying capacity or the fundamental natural frequency is maximized. A classical example of such problems is the Lagrange problem of determining the shape of the strongest column against buckling. The primary objective of …
An Experimental Study On Characteristics And Behavior Of Reinforced Soil Foundation, Qiming Chen
An Experimental Study On Characteristics And Behavior Of Reinforced Soil Foundation, Qiming Chen
LSU Doctoral Dissertations
This research study aims at investigating the potential benefits of using the reinforcement to improve the bearing capacity and reduce the settlement of shallow foundations. To implement this objective, a total of one hundred seventeen tests were performed to study the behavior of reinforced soil foundation. The test results showed that the inclusion of reinforcement can significantly improve the soil's bearing capacity and reduce the footing settlement. The geogrids with higher tensile modulus performed better than geogrids with lower tensile modulus. The strain developed along the reinforcement is directly related to the settlement. The test results also showed that the …
Particle And Dredge-Scale Kinetic Studies Of Hydrophobic Organic Chemical Desorption From Sediment, Justin Edward Birdwell
Particle And Dredge-Scale Kinetic Studies Of Hydrophobic Organic Chemical Desorption From Sediment, Justin Edward Birdwell
LSU Doctoral Dissertations
The discharge of hydrophobic organic chemicals (HOCs) and other hazardous substances from anthropogenic sources to surface waters and the atmosphere has led to the widespread contamination of bottom sediments throughout the world. HOCs collect in sediments due to their affinity for organic matter and other sorbents present on and within their solid matrices. There is interest in the movement of HOCs from historically contaminated, resuspended sediments to surface waters due to the connection between chemical desorption and bioavailability. Quantitatively accurate predictions of contaminant concentrations in environmental media are needed for reliable risk assessment and to develop strategies for protection of …
Semantic Image Retrieval Using Relevance Feedback And Transaction Logs, Amin Shah-Hosseini
Semantic Image Retrieval Using Relevance Feedback And Transaction Logs, Amin Shah-Hosseini
LSU Doctoral Dissertations
Due to the recent improvements in digital photography and storage capacity, storing large amounts of images has been made possible, and efficient means to retrieve images matching a user’s query are needed. Content-based Image Retrieval (CBIR) systems automatically extract image contents based on image features, i.e. color, texture, and shape. Relevance feedback methods are applied to CBIR to integrate users’ perceptions and reduce the gap between high-level image semantics and low-level image features. The precision of a CBIR system in retrieving semantically rich (complex) images is improved in this dissertation work by making advancements in three areas of a CBIR …
Locally Derived Nonpoint Loading Estimates For The Boeuf River/Bayou Lafourche Watershed, Emerald Purser Roider
Locally Derived Nonpoint Loading Estimates For The Boeuf River/Bayou Lafourche Watershed, Emerald Purser Roider
LSU Doctoral Dissertations
There is currently a great demand for data and models that can be used to quantify nonpoint source pollutant loads from different land-use types. The Louisiana Department of Environmental Quality (LDEQ) is in the process of implementing management programs for impacted water bodies based on the Total Maximum Daily Load (TMDL) of a pollutant. Pollutants of concern include total suspended solids (TSS), nitrogen, and phosphorus. One of the key parameters in determining the TMDL of a water body is the nonpoint source pollutant load from different land-use types. To date, such load estimates in Louisiana are lacking. The primary objective …
Monolithic Integration Of High-Aspect-Ratio Microstructures With Cmos Circuitry, Tinghui Xin
Monolithic Integration Of High-Aspect-Ratio Microstructures With Cmos Circuitry, Tinghui Xin
LSU Doctoral Dissertations
This work involves developing processing techniques for monolithically integrating a high-aspect-ratio microstructures with CMOS circuitry. A microsystem comprising of a microprobe array and signal processing circuitry is utilized as a test vehicle to demonstrate this fabrication process. One potential application of this microsystem is for recording neural signals from the central nervous system. The main results include thick photoresist processing, DC and pulse electroplating to form high-aspect-ratio microprobes, microprobe sharpening and developing a post-IC monolithic integration process. SU-8 is utilized for thick photoresist application. This work focuses on realization of a deep microrecess array in thick resists rather than traditional …
Mechanistic Modeling Of An Underbalanced Drilling Operation Utilizing Supercritical Carbon Dioxide, Faisal Abdullah Aladwani
Mechanistic Modeling Of An Underbalanced Drilling Operation Utilizing Supercritical Carbon Dioxide, Faisal Abdullah Aladwani
LSU Doctoral Dissertations
Mechanistic modeling of an underbalanced drilling operation using carbon dioxide has been developed in this research. The use of carbon dioxide in an underbalanced drilling operation eliminates some of the operational difficulties that arises with gaseous drilling fluids, such as generating enough torque to run a downhole motor. The unique properties of CO2, both inside the drill pipe and in the annulus are shown in terms of optimizing the drilling operation by achieving a low bottomhole pressure window. Typically CO2 becomes supercritical inside the drill pipe at this high density; it will generate enough torque to run …
Factors That Influence Visual Attention And Their Effects On Safety In Driving: An Eye Movement Tracking Approach, Larry Bargola Nabatilan
Factors That Influence Visual Attention And Their Effects On Safety In Driving: An Eye Movement Tracking Approach, Larry Bargola Nabatilan
LSU Doctoral Dissertations
Statistics show that a high percentage of road related accidents are due to factors that cause impaired driving. Since information extraction in driving is predominantly a visual task, visual distraction and its implications are therefore important safety issues. The main objective of this research is to study some of the implications of demands to human’s attention and perception and how it affects performance of tasks such as driving. Specifically, the study aims to determine the changes that occur in the visual behavior of drivers with different levels of driving experience by tracking the movement of the eye; examine the effects …
Computer Model Of Hybrid Compensator Of Fast Varying Loads, Veronica Bohorquez
Computer Model Of Hybrid Compensator Of Fast Varying Loads, Veronica Bohorquez
LSU Doctoral Dissertations
A computer model of the hybrid compensator of fast varying loads was developed in this dissertation. The computer model was implemented in MFC Visual C++ compiler version 6.0. The classification of fast varying loads and effects of their operation in distribution systems were described in this dissertation. The power properties of fast varying loads were expressed in terms of the Currents' Physical Components Theory. Therefore, the Currents' Physical Components Theory was applied to systems with non-periodic voltages and currents. The supply current of the fast varying loads was decomposed into the useful and the useless components using an algorithm based …
Laboratory Characterization And Numerical Modeling Of Geogrid Reinforced Bases In Flexible Pavements, Munir Darwish Nazzal
Laboratory Characterization And Numerical Modeling Of Geogrid Reinforced Bases In Flexible Pavements, Munir Darwish Nazzal
LSU Doctoral Dissertations
This dissertation documents the results of an extensive research study that was conducted to characterize the behavior of geogrid reinforced base course materials. The research was conducted through an experimental testing and numerical modeling programs. The experimental testing program included performing different laboratory tests to evaluate the effect of various factors on the performance geogrid reinforced base course materials. Finite element models were also developed to investigate the benefits of placing geogrids within the base course layer in a flexible pavement structure. The results of the experimental testing demonstrated that the inclusion of the geogrid reinforcement layer(s) improved the compressive …
Turbulence Modeling For Film Cooling Flows, Asif Hoda
Turbulence Modeling For Film Cooling Flows, Asif Hoda
LSU Doctoral Dissertations
An improved two equation turbulence model has been developed in this dissertation to better predict the complex film cooling flow field that is formed from the interaction of a coolant jet and a crossflow over a modeled turbine blade surface. Film cooling of turbine blades is commonly employed to effectively protect turbine blades from thermal failure and thereby to allow higher inlet temperatures in order to increase the efficiency of gas turbine engines. Film cooling involves the injection of rows of coolant jets from slots on the surface of a turbine blade which is then bent over by the crossflow …
Engineering A Photo-Control Mechanism For Rna Interference, Richard Andrew Blidner
Engineering A Photo-Control Mechanism For Rna Interference, Richard Andrew Blidner
LSU Doctoral Dissertations
RNA interference (RNAi) is a phenomenon in which RNA molecules elicit potent and sequence-specific post-transcriptional gene silencing. Nucleic acid chemical modifications have been incorporated to improve their pharmacological properties. Despite numerous developments in chemical modifications for increased stability, safety, and efficiency of these therapeutic agents, they still face challenges of spatial and temporal targeting. One potential targeting strategy uses photocaging techniques, which involves the covalent attachment of photolabile compounds to the effector NA species that blocks bioactivity until exposed to near UV-light. This work demonstrates that fully-2’-fluorinated nucleic acids (FNAs) can elicit RNAi and that these effectors are resistant to …
Aconitic Acid From Sugarcane: Production And Industrial Application, Nicolas Javier Gil Zapata
Aconitic Acid From Sugarcane: Production And Industrial Application, Nicolas Javier Gil Zapata
LSU Doctoral Dissertations
Trans aconitic acid (TAA) is the predominant organic acid in cane leaf matter (CLM) juice. Its concentration is three to six times higher than the level found in sugarcane stalks. The variation of composition in terms of total fermentable sugars (TFS), anions, and cations of the LCP85-384 sugarcane variety during 2003-2006 seasons, as well as the ripener (Polado-L®) effect were analyzed. TAA content ranged between 2.1-3.1 kg / t CLM. The TFS in CLM juice yielded a fermentation efficiency of 92%, four points lower than with sugar molasses. Liquid-liquid extraction (LLE), solid-liquid extraction and ion exchange were evaluated for the …
Oil Bypassing By Water Invasion To Wells: Mechanisms And Remediation, Juan Carlos Hernandez
Oil Bypassing By Water Invasion To Wells: Mechanisms And Remediation, Juan Carlos Hernandez
LSU Doctoral Dissertations
This study addresses oil bypassing caused by water invasion to wells in edge and bottom water-drive oil reservoirs – a significant problem worldwide. It is shown that the amount of by-passed (not recovered) oil is significant and could be predicted analytically and reduced by modifying well’s completion. A large statistical sample from the population of possible reservoir-well systems with edge and bottom-water has been created theoretically using several databases of actual reservoirs properties worldwide. Dimensional analysis allowed converting reservoir properties distributions into dimensionless group distributions. Then, the amount of by-passed oil was correlated with the dimensionless groups using designed experiments …
Readjustment Of A Regional Geodetic Leveling Network To Account For Temporally And Spatially Variable Vertical Displacement Of Benchmarks, Kurt Shinkle
LSU Doctoral Dissertations
This dissertation describes and analyzes the temporally and spatially non-linear nature of the vertical displacement of 1st order geodetic benchmarks in the lower Mississippi Valley and northern Gulf of Mexico coastal region. The least-squares method of adjusting redundant surveying observations is implemented to compute the most likely value of the most recent rates of displacement at node benchmarks within the network, along with estimates of the uncertainty of those values. Using that result, a modification of the standard method of adjusting geodetic leveling networks is developed and demonstrated to compute new elevations for the node benchmarks which accounts for both …
Development Of Micropump For Microfluidic Applications, Dong Eun Lee
Development Of Micropump For Microfluidic Applications, Dong Eun Lee
LSU Doctoral Dissertations
This dissertation covers the research work on two types of micropumps, one is based on magnetohydrodynamic (MHD) principle that utilizes Lorentz force for actuation, and the other is based on electrochemical actuation. The AC-type MHD micropump was designed and analyzed as a solution to the bubble formation problem encountered in DC-type MHD micropump. A UV-LIGA process using thick layer of SU-8 negative photoresist was successfully developed to microfabricate the AC MHD micropump. Preliminary studies and tests of the AC MHD micropumps demonstrate that bubble formation was significantly reduced to permit the proper function of the micropump. A continuous flow was …
Measurement Of Metal Migration In Sediment Caps With X-Ray Fluorescene, Ming Yin
Measurement Of Metal Migration In Sediment Caps With X-Ray Fluorescene, Ming Yin
LSU Doctoral Dissertations
ABSTRACT Sand is often used as a passive barrier to slow release of metals from the sediment and to separate benthic organisms from the sediment. Materials that effectively adsorb metals have the potential to provide significantly greater effectiveness by further retarding metal release. In this thesis, the effectiveness of apatite and Phosphil®, which contain phosphate in a form that can absorb many metals, is evaluated with a series of sorption and migration column experiments using Cr, Cu, Zn and Pb. Langmuir shape isotherms were observed suggesting that the effectiveness of these materials decreases at high concentration. The sorption isotherm experiments …
Characterization Of Unsaturated Soils Using Elastic And Electromagnetic Waves, Bashar Alramahi
Characterization Of Unsaturated Soils Using Elastic And Electromagnetic Waves, Bashar Alramahi
LSU Doctoral Dissertations
Recent advances in laboratory instruments and techniques enabled researchers to explore new aspects of the behavior of geomaterials and perform measurements that would be otherwise impossible to acquire using traditional geotechnical laboratory techniques. This dissertation is focused on utilizing elastic and electromagnetic wave measurements and SMCT imaging to non-destructively characterize different aspects of the behavior of unsaturated soils. A model that relates P-wave velocity in soils to the volumetric water content was used to develop a new methodology to determine the in situ density and moisture content of soils. It was numerically and experimentally verified to assess it validity and …
Micro Injection Fuel/Air Premixer/Combustion, Jian Zhang
Micro Injection Fuel/Air Premixer/Combustion, Jian Zhang
LSU Doctoral Dissertations
Lean premixed (LP) combustion has become the dominant industrial approach to reduce NOx emissions. Homogeneous mixing of lean fuel and air mixtures prevents the presence of undesirable localized regions of near-stoichiometric fuel/air mixtures, thereby allowing a reduction in thermal NOx. A new concept, a multi-point micro injection premixer, is presented in this dissertation. The multi-point micro injection premixer is a porous plate that provides a simple but extremely effective method to mix air and fuel. An array of fuel jets is injected in a direction perpendicular to the plane of the premixer plate into an oncoming counterflow stream of air. …
Effect Of Hole Configurations On Film Cooling From Cylindrical Inclined Holes For The Application To Gas Turbine Blades, Yiping Lu
LSU Doctoral Dissertations
Film cooling is one of the cooling systems investigated for the application to gas turbine blades. Gas turbines use film cooling in addition to turbulated internal cooling to protect the blades outer surface from hot gases. The present study concentrates on the experimental and numerical investigation of film cooling performance for a row of cylindrical holes in a modern turbine blade. The adiabatic film effectiveness and the heat transfer coefficient are determined experimentally on a flat plate downstream of a row of inclined different geometries hole exit by using a single test transient IR thermography technique. The focus of this …
Wind Loads For Petrochemical Structures, Samuel Amoroso
Wind Loads For Petrochemical Structures, Samuel Amoroso
LSU Doctoral Dissertations
Techniques currently available to practicing engineers for estimating wind loads for petrochemical structures have little theoretical or experimental basis. This dissertation research is an effort to expand the understanding of wind effects on petrochemical and other, similar structures. Petrochemical structures introduce geometric scales into wind tunnel model simulations below what are common for enclosed structures. Wind tunnel experiments were performed to help determine whether this will introduce problems in achieving dynamic similarity between models and prototypes. The experiments did not reveal any clear indication that petrochemical structures cannot be modeled in wind tunnels at scales similar to those used for …
Effects Of Capping On Biodegradation Of Organic Contaminants In Sediments, Eun Ju Lee
Effects Of Capping On Biodegradation Of Organic Contaminants In Sediments, Eun Ju Lee
LSU Doctoral Dissertations
Sediment capping remains an effective remediation technique for contaminated sediments due to its capability to contain contaminants and provide a sound habitat for indigenous biota. This research investigated the effect of capping on biodegradation of organic contaminants in Anacostia River sediments using both experimental and modeling techniques. 14C–Phenanthrene mineralization was monitored under various redox conditions in Anacostia River sediments. Mineralization of 14C–phenanthrene was strongly linked to sulfate reduction, which was the more energetic process than any other anaerobic condition in Anacostia sediments. Sulfate is a more promising terminal electron acceptor for intrinsic degradation in Anacostia River and other PAH contaminated …
Flow And Distribution Of Water In Fractional Wettability Unsaturated Porous Media, Zaydoun Turkey Abusalem
Flow And Distribution Of Water In Fractional Wettability Unsaturated Porous Media, Zaydoun Turkey Abusalem
LSU Doctoral Dissertations
In recent years, interest in fluid flow and transport in the unsaturated zone has gained more attention, due to growing concerns that the quality of the subsurface environment is adversely affected by agricultural, industrial, and municipal activities. The wettability properties (e.g., water repellency) of soil in the unsaturated zone play an important role in determining fluid movement and ultimate distributions. A number of studies have shown that preferential flow and spatially variable moisture content is likely to occur in water repellant soils. Development of appropriate constitutive relations for numerical modeling becomes even more difficult in systems that contain water repellant …
Electrodeposition Of Rare Earth-Transition Metal Alloy Thin Films And Nanostructures, Rohit Mishra
Electrodeposition Of Rare Earth-Transition Metal Alloy Thin Films And Nanostructures, Rohit Mishra
LSU Doctoral Dissertations
Rare earth-transition metal alloys are of interest in MEMS and magnetic storage industries because of their unique magnetic properties. However, the applications of these alloys have been limited to bulk and thin film architectures because of the limitations of the contemporary vapor deposition technique to fabricate high aspect ratio nanostructures. The objective of this study is to develop an electrochemical process to deposit rare earth-transition metal alloys thus making it possible to deposit high aspect ratio nanostructures such as nanowires and nanotubes, which helps to tune their properties for specific applications. Electrodeposition of rare earth-transition metal alloys was achieved from …
Granular Contact Lubrication: Theory And Experiment, Karim El Kholy
Granular Contact Lubrication: Theory And Experiment, Karim El Kholy
LSU Doctoral Dissertations
This dissertation is devoted to a theoretical and experimental study of the granular contact lubrication, both. The theory is based on the kinetic of the granular material where the granules interact with each other and with the boundary surfaces through instantaneous, binary collisions, characterized by a constant coefficient of restitution. Specifically this study focuses on granular lubrication in Couette flows. A series of simulations is reported and the results show good agreement with several published papers. Also, a theory that ties the true temperature to the grain mobility is developed. The true temperature of a granular material depends on the …
Three Dimensional Behavior Of Retaining Wall Systems, Kevin Abraham
Three Dimensional Behavior Of Retaining Wall Systems, Kevin Abraham
LSU Doctoral Dissertations
The objective of this study was to perform an engineering assessment of key three-dimensional (3-D) soil-structure interaction (SSI) features of selected earth retaining walls utilizing the nonlinear finite element method (FEM). These 3-D features are not explicitly incorporated in conventional two-dimensional (2-D) procedures that are commonly used to design these retaining walls. The research objective was accomplished utilizing the nonlinear FEM. The retaining walls selected for this research were described in detail. Design methodologies and computed responses for the walls based on conventional 2-D design procedures were summarized. Key engineering features of these structures such as construction sequence and system …
An Investigation Of The Frictional And Thermal Behavior Of Oscillatory Sliding Line Contacts, Mongi Mansouri
An Investigation Of The Frictional And Thermal Behavior Of Oscillatory Sliding Line Contacts, Mongi Mansouri
LSU Doctoral Dissertations
This research deals with an experimental and numerical investigation of the frictional and thermal behavior of pin-bushing pairs, operating at reciprocating sliding motion or under heavy loads. Large interfacial temperatures developed due to frictional heating can cause failure. Therefore, numerical prediction and analysis of the surface temperature under various operating conditions are important. Laboratory tests using a pin-bushing tester provided measurements of the friction coefficient and temperature. Hard coated and plain (uncoated) bushings, both made of induction hardened stainless steel, were tested. Lower coefficient of friction and surface temperature were observed in the case of the coated bushing. In the …
Measurements And Computations Of The Flow In Full-Scale Sugar Evaporative-Crystallizers And In Lab-Scale Models, Luis Fernando Echeverri
Measurements And Computations Of The Flow In Full-Scale Sugar Evaporative-Crystallizers And In Lab-Scale Models, Luis Fernando Echeverri
LSU Doctoral Dissertations
The circulation of massecuite is a key factor in achieving efficient heat transfer and crystallization in sugar evaporative crystallizers, and should be as high as practically possible for recovery, quality, and capacity reasons. This research report presents results on the circulation obtained applying modern experimental and numerical techniques. The main goals are contributing to expand the understanding of the process in sugar crystallizers; developing realistic models for the simulation of the circulation; and studying the effect of different design parameters. The circulation of massecuite is driven by buoyancy force due to density difference between the vapor generated and the surrounding …
Characterization Of Advanced Composites- A Nondestructive Approach, Phani Surya Kiran Mylavarapu
Characterization Of Advanced Composites- A Nondestructive Approach, Phani Surya Kiran Mylavarapu
LSU Doctoral Dissertations
Adhesively bonded sandwich structures comprising of particulate composites as core and graphite epoxy skins as stiffeners are widely used for various applications in the marine and aerospace industry. The core material and the stiffener are held together by an adhesive bond. Particulate composites are made from a mixture of a polymer resin and hollow or solid particles. Hollow particulate composites are known as syntactic foams. Particulate composites possess attractive mechanical and physical properties such as high compressive strength etc, making them attractive materials for use in structural applications. Characterization of the adhesive bondline and core material in sandwich structures is …
Experimental And Modeling Studies Of Contaminant Transport In Capped Sediments During Gas Bubble Ebullition, Qingzhong Yuan
Experimental And Modeling Studies Of Contaminant Transport In Capped Sediments During Gas Bubble Ebullition, Qingzhong Yuan
LSU Doctoral Dissertations
Fluxes of the three organics and eighteen metals from sediments were measured with diffusion chambers, and the effectiveness of a sand cap ascertained. The influence of sediment consolidation on contaminant flux and the mass transfer coefficient at the sediment-water interface was studied. A two-layer diffusion-advection model and consolidation model were coupled to elucidate the effect of sediment consolidation on chemical transport in the sediment-cap system. The model was tested and verified by the experimental data from microcosms, and then was used to predict phenanthrene flux under field conditions. The simulation results showed that consolidation could accelerate phenanthrene breakthrough and enhance …