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Articles 2581 - 2610 of 2820
Full-Text Articles in Engineering
Electrodeposition Of Feconicu Quaternary System, Qiang Huang
Electrodeposition Of Feconicu Quaternary System, Qiang Huang
LSU Doctoral Dissertations
Electrodeposition is a cost-effective method to produce thin film materials, which have been used widely in the microelectronic industry, and is advantageous to fabricate metal deposits into recessed and curved areas. In this dissertation, FeCoNiCu quaternary alloy system was investigated, both experimentally and theoretically, for fabrication of multilayers, grating structures, and nanowires. Multilayer structures are composed of alternating ferromagnetic and nonmagnetic nanometric layers, and are of interest due to the giant magnetoresistance (GMR) property it possesses, a change in electric resistance in the presence of an external magnetic field. In addition, the compositional modulation, or the composition contrast, in multilayer …
Modeling The Effects Of Rainfall Intensity And Deep Chiseling On Infiltration And Runoff Within Drainmod For Alluvial Soils, Daniel Nyabiba Moriasi
Modeling The Effects Of Rainfall Intensity And Deep Chiseling On Infiltration And Runoff Within Drainmod For Alluvial Soils, Daniel Nyabiba Moriasi
LSU Doctoral Dissertations
Accurate hydrologic models are needed to aid engineers and researchers design, install and evaluate efficient and cost-effective agricultural water management systems to reduce risks associated with food production, and to reduce soil erosion and water pollution. One model used for the alluvial soils of Louisiana is DRAINMOD. This model does not accurately predict infiltration and runoff for the crusting-prone alluvial soils of Louisiana. The main goal of this study was to modify the current DRAINMOD model to incorporate the effects of rainfall intensity and deep chiseling to improve its estimation of infiltration and surface runoff. The second goal was to …
Innovative Cooling Configurations For Low Emission Gas Turbine Combustors, Ryan Thomas Hebert
Innovative Cooling Configurations For Low Emission Gas Turbine Combustors, Ryan Thomas Hebert
LSU Master's Theses
Presently, effective cooling of modern low NOx combustor liners is achieved through combinations of innovative impingement configurations and other heat transfer enhancement methods. An inherent characteristic of conventional impingement configurations is the occurrence of downstream heat transfer degradation due to increased crossflow effects. In the present study, two different impingement configurations are studied. Both impingement configurations examined in this study aim to increase heat transfer effectiveness by reducing the detrimental effects of spent air crossflow. In Part I, a combination technique wherein impingement is combined with ribs placed in between impingement rows is studied. Three configurations with increased rib placements …
Material Length Scales In Gradient-Dependent Plasticity/Damage And Size Effects: Theory And Computation, Rashid Kamel Abu Al-Rub
Material Length Scales In Gradient-Dependent Plasticity/Damage And Size Effects: Theory And Computation, Rashid Kamel Abu Al-Rub
LSU Doctoral Dissertations
Structural materials display a strong size-dependence when deformed non-uniformly into the inelastic range: smaller is stronger. This effect has important implications for an increasing number of applications in structural failure, electronics, functional coatings, composites, micro-electro-mechanical systems (MEMS), nanostructured materials, micro/nanometer fabrication technologies, etc. The mechanical behavior of these applications cannot be characterized by classical (local) continuum theories because they incorporate no ‘material length scales’ and consequently predict no size effects. On the other hand, it is still not possible to perform quantum and atomistic simulations on realistic time and structures. It is therefore necessary to develop a scale-dependent continuum theory …
Optimization Of A Skewed Logistic Distribution With Respect To The Kolmogorov-Smirnov Test, James Charles Finney
Optimization Of A Skewed Logistic Distribution With Respect To The Kolmogorov-Smirnov Test, James Charles Finney
LSU Doctoral Dissertations
The four-parameter kappa distribution (Hosking 1994) was analyzed with respect to the various possible shapes of the probability density function. The general form for the cumulative distribution function when both h and k are non-zero is: F(x) = { 1 - h [ 1 - k ( x - ξ ) / α ]1/k }1/h. The parameters h and k work together to define the function's shape, ξ affects location, and α is the scale parameter. A method of selecting parameters to minimize the Kolmogorov-Smirnov test statistic, D, was developed. The technique was first described for the …
Synthesis, Structure, And Tribological Behavior Of Nanocomposite Dlc Based Thin Films, Varshni Singh
Synthesis, Structure, And Tribological Behavior Of Nanocomposite Dlc Based Thin Films, Varshni Singh
LSU Doctoral Dissertations
Diamond-like carbon (DLC) films possess a combination of attractive properties and have been largely employed to modify the tribological behavior of materials. Nanocomposite, metal-containing DLC films are the new generation of these coatings providing tremendous potential to modify and tailor their properties expanding their applications in the field of nanotechnology. The present study investigates nanoscale effects on the tribological behavior of composite nanostructured DLC-based films and functional coatings. Three aspects were studied: (i) effect of Cr interlayer on a functionally gradient substrate; (ii) nanoparticulate Cr-containing DLC (Cr-DLC) films; and (iii) nanocomposite multilayered Cr/DLC coatings. Intensified plasma assisted nitriding produced a …
Design And Operating Strategies For Bioreactors Treating Dynamically Varying Concentrations Of Gas-Phase Volatile Organic Compounds (Vocs), Congna Li
LSU Doctoral Dissertations
The dynamically varying concentrations of volatile organic compounds (VOCs) in most waste gas streams present a challenge in design and operation of biofilters treating such off-gases. Studies described in this dissertation were directed toward development and experimental testing of two design modifications/operating strategies that have the potential to improve biofilter performance during unsteady-state loadings. In the first design modification studied, activated carbon was incorporated into biofilter packing media and a novel periodic operating strategy, Sequencing Batch Biofilter (SBB) operation, was tested under “normal” and various “shock” loading conditions treating methyl ethyl ketone contaminated air. Results demonstrate how the operational flexibility …
Numerical Modeling Of Strain Localization In Granular Materials Using Cosserat Theory Enhanced With Microfabric Properties, Mustafa Alsaleh
Numerical Modeling Of Strain Localization In Granular Materials Using Cosserat Theory Enhanced With Microfabric Properties, Mustafa Alsaleh
LSU Doctoral Dissertations
Finite element solution in the updated Lagrangian frame is used to investigate the strain localization phenomenon "shear bands" in granular materials. The micro-polar theory was used as the mathematical foundation for the continuum formulations. A laboratory testing results are used for verification and comparison with the numerical simulation. Silica sand and glass beads with different shape indices, size and surface roughness were tested under biaxial and triaxial loading conditions to investigate the physics of the problem. The shape non-uniformity and the irregular surface roughness of the grains were studied carefully to evaluate their effect on shear band characteristics. To this …
Numerical Methods For The Unsteady Incompressible Navier-Stokes Equations And Their Application To The Direct Numerical Simulation Of Turbulent Flows, Frank Herbert Muldoon
Numerical Methods For The Unsteady Incompressible Navier-Stokes Equations And Their Application To The Direct Numerical Simulation Of Turbulent Flows, Frank Herbert Muldoon
LSU Doctoral Dissertations
Two new methods for the efficient parallel computation of the unsteady incompressible Navier-Stokes equations are presented. Such efficient methods are desired for large scale parallel computations of unsteady turbulent flows such as Direct Numerical Simulations (DNS). The performance of the new methods has a distinct advantage over the artificial compressibility method, in that the methods exhibit robust convergence for a variety of flow problems without extensive need for tuning computational parameters. These methods and others have been implemented in a computer program designed for massively parallel computer architectures, written by the author and used to obtain all results in this …
Improved Opportunity Cost Algorithm For Carrier Selection In Combinatorial Auctions, Viswanath Uma Gnanasekaran
Improved Opportunity Cost Algorithm For Carrier Selection In Combinatorial Auctions, Viswanath Uma Gnanasekaran
LSU Master's Theses
Transportation costs constitute up to thirty percent of the total costs involved in a supply chain. Outsourcing the transportation service requirements to third party logistics providers have been widely adopted, as they are economically more rational than owning and operating a service. Transportation service procurement has been traditionally done through an auctioning process where the auctioneer (shipper) auctions lanes (distinct delivery routes) to bidders (carriers). Individual lanes were being auctioned separately disallowing the carriers to express complements and substitutes. Using combinatorial auctions mechanism to auction all available lanes together would allow the carriers to take advantage of the lane bundles, …
Numerical Simulation And Field Verification Of Inclined Piezocone Penetration Test In Cohesive Soils, Lei Wei
Numerical Simulation And Field Verification Of Inclined Piezocone Penetration Test In Cohesive Soils, Lei Wei
LSU Doctoral Dissertations
A large strain finite element analysis is performed to analyze the effect of soil anisotropy on the inclined piezocone penetration test in normally consolidated cohesive soils. The piezocone penetration is numerically simulated using the commercial finite element code ABAQUS. The saturated clay is modeled as a two-phase material and the effective stress principle is used to describe its behavior. A frictional contact interface utilizing Mohr-Coulomb's theory was chosen to represent interactions between the surface of the cone and the soil. The Anisotropic Modified Cam Clay Model (AMCCM) by Dafalias (1987) was chosen and implemented into ABAQUS through user subroutine UMAT. …
Tissue Interactions With Lasers And Liquid Nitrogen: A Novel Cryopreservation Method, Deepak Kandra
Tissue Interactions With Lasers And Liquid Nitrogen: A Novel Cryopreservation Method, Deepak Kandra
LSU Master's Theses
The importance of the imposed cooling rate in cryopreserving native cells and tissues has been long recognized in the field of cryobiology. When biological tissues are subjected to cooling rates in excess of thousands of degree C per minute, the characteristic structural and physical manifestations of the ice formed are such that the traditional damage due to ice formation at lower cooling rates are suppressed. Hence, achieving high cooling rates in tissues and cells of biologically relevant sizes (mm’s and cm’s) has been a long standing research problem. In the present study, we present a novel technique to achieve high …
Color, Texture And Rehydration Characteristics Of Ohmically Treated Sweet Potatoes, Sireesha Bhattiprolu
Color, Texture And Rehydration Characteristics Of Ohmically Treated Sweet Potatoes, Sireesha Bhattiprolu
LSU Master's Theses
Ohmic heating has been shown to affect the drying rate and texture of foods. This research was designed to determine the effect of ohmic heating on rehydration, color and texture properties of sweet potatoes. Three combinations: 60Hz, 40V, 60Hz, 60V and 1Hz, 40V were applied to ohmically heat sweet potato cubes. The ohmic treated cubes and untreated cubes or controls were stored for six days in four different %relative humidities of 11.15%, 32.73%, 57.70% and 75.32%. Results showed that there was no significant difference in the rehydration properties of ohmic treated samples and control samples. The % moisture gain varied …
Heat/Mass Transfer In Smooth And Ribbed Rectangular Serpentine Passages Of Different Aspect Ratio's And Orientation, Peeyush Agarwal
Heat/Mass Transfer In Smooth And Ribbed Rectangular Serpentine Passages Of Different Aspect Ratio's And Orientation, Peeyush Agarwal
LSU Master's Theses
An experimental study of heat/mass transfer in rectangular smooth and ribbed serpentine passages with and without rotation in two different aspect ratios (1:4 and 4:1) channel is performed for two different orientations of the test section (90-degree and 45-degree). The Reynolds number is varied in the range of 5,000 to 40,000 and rotation numbers in the range of 0-0.12. Such passages are encountered close to the mid-chord sections or towards the trailing edge of the turbine blade. Two different configurations of the Normal ribs (e/Dh=0.3125, P/e=8 and e/Dh=0.156, P/e=11.2) are placed on the leading and the …
Mems Accelerometer: Proof Of Concept For Geotechnical Engineering Testing, Keith Nicholas Hoffman
Mems Accelerometer: Proof Of Concept For Geotechnical Engineering Testing, Keith Nicholas Hoffman
LSU Master's Theses
Geotechnical engineering materials are inherently variable, which leads to many simplifications when trying to model their behavior. The materials must always be characterized prior to any design work so that the engineer knows which direction he must progress to have a reliable design. Although subsurface characterization techniques and geotechnical design steadily improve, they are by no means infallible. The combination of geotechnical subsurface characterization along with geophysical techniques for improved design and construction monitoring has begun to surface as a viable alternative to the standard techniques in geotechnical engineering. This is important because there is a lack of Quality Control/Quality …
Photo-Control Of Dna Oligonucleotides With Cage Compounds, Bilal Ghosn
Photo-Control Of Dna Oligonucleotides With Cage Compounds, Bilal Ghosn
LSU Master's Theses
Many biochemical processes in which DNA and other nucleic acids participate are central to functions in both living cells and in molecular biology assays. While many compounds have been used to regulate the activity of DNA, these strategies are limited to the aqueous-based diffusion of the activator to the target DNA molecule. An improvement to the induction of DNA bioactivity is to move to a light-based modulation. This research demonstrates a light-based technique using a photo-cleavable cage compound to transiently inactivate DNA hybridization. Function can be restored with exposure to near-UV light, allowing for temporal control of DNA oligonucleotide (ODN) …
Synthesis, Characterization And Tribological Behavior Of Nitrogen-Doped Chromium-Diamond-Like Carbon Nanocomposite Thin Films, Sunil Kumar Pal
Synthesis, Characterization And Tribological Behavior Of Nitrogen-Doped Chromium-Diamond-Like Carbon Nanocomposite Thin Films, Sunil Kumar Pal
LSU Master's Theses
Diamond-like carbon (DLC) films have been extensively studied for more than two decades due to their highly attractive properties. These films exhibit unique mechanical, chemical and electronic properties and thus, possess great potential for applications in tribology. However, two drawbacks in the DLC films are high level of internal stress developed during growth preventing deposition of thick films and low thermal stability. Synthesis of Me-DLC (Cr-DLC and N-doped Cr-DLC) presents a way to overcome these drawbacks. In the present study, DLC, Cr-DLC and N-doped Cr-DLC films were deposited on Si substrate using a hybrid Plasma assisted CVD/PVD process. Film characterization …
An Evaluation Of Methods Used To Obtain The Railroad Preemption Queue Clearance Time, Deeangela Renee Kenon
An Evaluation Of Methods Used To Obtain The Railroad Preemption Queue Clearance Time, Deeangela Renee Kenon
LSU Master's Theses
Because of the potential for serious train-vehicle accidents at or near railroad-highway grade crossings, preemption of traffic signals is a very important supplement to an active warning system. Preemption is the transfer of normal signal phasing to a special control mode with the purpose of clearing any vehicles that are queued within the dynamic envelope as the train approaches, and prohibiting signal phases that would allow additional vehicles in the track area while the train is present. The focus of this research was the determination of the Clear Track Green Interval (or the Queue Clearance Time). The clear track green …
Modeling Event-Based Coupled Hydrologic And Mass Transport In Small Urban Watersheds, Yuhong Sheng
Modeling Event-Based Coupled Hydrologic And Mass Transport In Small Urban Watersheds, Yuhong Sheng
LSU Doctoral Dissertations
To investigate the event-based coupled hydrologic and mass transport processes of particulate matter and their eventual fate in unit operations/processes, several methodologies were developed. Discrete rainfall-runoff events data were collected at two similar urban watersheds for model calibration and verification. A mathematically and physically-based criterion was proposed to differentiate rainfall-runoff events between either mass-limited or flow-limited. Statistical techniques of Logistic Regression and Discriminant Analysis were utilized to derive classification rules for event categories based on hydrologic data only. With watersheds assumed as either lumped systems or distributed systems, physically-based semi-empirical models were developed to simulate particulate mass delivery process during …
Design And Performance Of Electric Shock Absorber, Oly D. Paz
Design And Performance Of Electric Shock Absorber, Oly D. Paz
LSU Master's Theses
The electric shock absorber is a device that converts the kinetic energy of an oscillating object into electric energy. This kinetic energy is normally dumped in a form of thermal energy in a conventional, mechanical shock absorber. The electric shock absorber consists of a permanent magnet linear synchronous generator (PMLSG), a spring, and an electric energy accumulator. The major goal of the project is to design and analyze the operation of an electric shock absorber. In order to define the initial requirements that the electric shock absorber has to satisfy, the construction and performance of currently used shock absorbers were …
Fabrication And Assembly Of An Array Of Micro Fuel Injector Nozzles For A Trapped-Vortex Combustor, Tracy Ettel Morris
Fabrication And Assembly Of An Array Of Micro Fuel Injector Nozzles For A Trapped-Vortex Combustor, Tracy Ettel Morris
LSU Master's Theses
An array of four fuel injector nozzles, each with micrometer-scale swirlers and a microhole, is created on a single coupon. The nozzles are intended to atomize fuel to blend with swirling air before ejecting into a trapped-vortex combustion chamber. A first-generation metal prototype is fabricated in order to form the micro features, supply the fuel and gas to the nozzles, and guide the mixture to the combustion chamber. Microfabrication methods and precision machining are used to create a multiple plate laminate assembly. The central plate contains the four microholes, which atomize the fuel, and facilitate the swirler structures needed to …
Analysis And Evaluation Of A Bioengineered Submerged Breakwater, Matthew Dwain Campbell
Analysis And Evaluation Of A Bioengineered Submerged Breakwater, Matthew Dwain Campbell
LSU Master's Theses
Louisiana's coastline has received national attention due to rapid erosion rates estimated from approximately 60 to 100 square kilometers per year. The disappearance of coastal areas jeopardizes public and private infrastructure, property values, aquatic ecosystems, and standards of living. In order to resolve the erosion problem, innovative solutions have been explored that may improve effectiveness and cost efficiency. This research involves a technology, termed an "oysterbreak," which is a bioengineered submerged breakwater. This structure promotes oysters to form a dense structure that dissipates wave energy. Since the structure is biologically dominated, initial material use is modest. The oysterbreak was evaluated …
Towards Automated Capture Of 3d Foot Geometry For Custom Orthoses, Rajeev Madazhy
Towards Automated Capture Of 3d Foot Geometry For Custom Orthoses, Rajeev Madazhy
LSU Master's Theses
This thesis presents a novel method of capturing 3D foot geometry from images for custom shoe insole manufacture. Orthopedic footwear plays an important role as a treatment and prevention of foot conditions associated with diabetes. Through the use of customized shoe insoles, a podiatrist can provide a means to better distribute the pressure around the foot, and can also correct the biomechanics of the foot. Different foot scanners are used to obtain the geometric plantar surface of foot, but are expensive and more generic in nature. The focus of this thesis is to build 3D foot structure from a pair …
Biological Treatment Of Industrial Wastewater Containing High Concentrations Of Linear Alkylbenzene Sulfonate (Las), Luis Alberto Espinoza
Biological Treatment Of Industrial Wastewater Containing High Concentrations Of Linear Alkylbenzene Sulfonate (Las), Luis Alberto Espinoza
LSU Master's Theses
Lauryl Alkylbenzene Sulfonate (LAS) is the major anionic surfactant used worldwide in detergent and household cleaning product formulations. Its biodegradation and removal has been extensively studied in wastewater treatment facilities and laboratory-scale tests at low concentrations (<10 mg/L) typical of those encountered in municipal wastewater treatment plants. Less effort, however, has been expended investigating degradation of higher concentrations of LAS representative of those expected in wastewater generated at LAS manufacturing operations. The research described in this thesis was conducted to study biological processes for treating wastewaters containing high concentrations (e.g., 400 mg/L) of LAS. Initial experiments were carried out using a respirometry technique, and subsequently, three different laboratory-scale bioreactor systems. The three systems studied were a Sequencing Batch Reactor (SBR), a Sequencing Batch Biofilm Reactor (SBBR), and an Intermittent Cycle Extension Aeration System (ICEAS). The SBR and ICEAS were operated on a five-day cycle basis with a hydraulic retention time of four days. The SBBR was operated mainly in a two-day cycle having a hydraulic retention time of ten days as well, and polyurethane foam cubes were used as a support medium for attached biomass growth. The three systems were compared on their ability to remove LAS measured in terms of total organic carbon (TOC) and methylene blue active substances (MBAS). The reactors were also compared on the basis of foam production. The ICEAS showed the best performance in terms of controllable foam production while exhibiting a capacity for effectively dealing with transient periods of elevated loading. When a short Fill period was used, the SBR and SBBR had the disadvantage of producing excessive foaming, and an intermittent aeration strategy was required avoid overflow.
Chemical Production Complex Optimization, Pollution Reduction And Sustainable Development, Aimin Xu
Chemical Production Complex Optimization, Pollution Reduction And Sustainable Development, Aimin Xu
LSU Doctoral Dissertations
The objective of this research is to propose, develop and demonstrate chemical production complex optimization to determine the optimal configuration of chemical plants in a superstructure of possible plants. The Chemical Complex Analysis System is a new methodology that has been developed to determine the best configuration of plants in a chemical production complex based on the AIChE Total Cost Assessment (TCA) for economic, energy, environmental and sustainable costs. All new, energy-efficient, and environmentally acceptable plants using greenhouse gases that can produce potentially commercial products designed with HYSYS were integrated into the chemical complex using the System. The optimum configuration …
Numerical And Experimental Investigation Of Transport Processes In Biological Systems, Yimeng He
Numerical And Experimental Investigation Of Transport Processes In Biological Systems, Yimeng He
LSU Master's Theses
This thesis focuses on optimization techniques for transport process during the cryopreservation of biological systems. In the first part of this thesis, a well established shape independent Differential Scanning Calorimeter (DSC) technique was used to measure the dehydration response during freezing of Pacific oyster sperm cells. Volumetric shrinkage during freezing of diploid and tetraploid pacific oyster sperm cell suspensions was obtained at cooling rates of 5 and 20 ˚C/min in the presence of extracellular ice and CPAs. By fitting a model of water transport to the experimentally obtained volumetric shrinkage data the best fit membrane permeability parameters (Lpg and …
Ceria-Zirconia Oxide High Temperature Desulfurization Sorbent, Kwang Bok Yi
Ceria-Zirconia Oxide High Temperature Desulfurization Sorbent, Kwang Bok Yi
LSU Doctoral Dissertations
High temperature desulfurization of highly reducing coal-derived gases using ceria and ceria-zirconia sorbents is the primary object of this dissertation research. If H2S concentration is reduced to less than 1 ppmv the product gas may be used with fuel cells and downstream catalytic process. CeO2 is reduced to a non-stoichiometric oxide, which is superior to CeO2 in removing H2S. Moreover, ZrO2 addition to CeO2 to form a solid solution, Ce1-xZrxO2, increases the reducibility of CeO2. This should also result in improved desulfurization performance. Pure CeO2 and sorbents, both commercially available and prepared at LSU, were tested. XRD analysis indicated that …
Travel Time Tomographic Imaging Of The Distribution Of The Effective Stress In Clean Sand Under A Model Footing, William M. Tanner
Travel Time Tomographic Imaging Of The Distribution Of The Effective Stress In Clean Sand Under A Model Footing, William M. Tanner
LSU Master's Theses
The use of high-speed data acquisition systems, inexpensive and reliable transducers, and better models of interpretation have combined to make elastic wave tomographic imaging of geotechnical engineering systems easier to accomplish both in the laboratory and in the field. An important application of these developments is that the evaluation of states of effective stress in soils using images of elastic wave velocity distribution. As a consequence, it is possible to experimentally estimate the state of induced and in-situ effective stresses and to compare these results with established models of stress distribution based on the theory of elasticity (e.g., Boussinesq’s solution). …
Watermarking Using Decimal Sequences, Navneet Kumar Mandhani
Watermarking Using Decimal Sequences, Navneet Kumar Mandhani
LSU Master's Theses
This thesis introduces the use of decimal sequences in watermarking to hide information for authentication. The underlying system is based on code division multiple access (CDMA), which is a form of spread spectrum communication. Different algorithms for the use of decimal sequences have been formulated for use in black and white images. The watermark is spread across the carrier image by using the d- sequences of optimal period and retrieval is made by the use of correlation. Matlab version 6.5 was used to implement the algorithms discussed in this thesis. The advantage of using d-sequences over PN sequences is that …
Design And Fabrication Of Electromagnetic Micro-Relays Using The Uv-Liga Technique, John Dalton Williams
Design And Fabrication Of Electromagnetic Micro-Relays Using The Uv-Liga Technique, John Dalton Williams
LSU Doctoral Dissertations
This dissertation reports a research effort to microfabricate an electromagnetic relay for power applications using a multilayer UV-LIGA process. A mechanically wrapped coil was used and very simple design for the magnetic circuit was adopted to increase the design flexibility and performances. The broad material selection and the capability of making high aspect ratio microstructures of the UV-LIGA make the technology best suited for fabricating microelectromechanical power relays. Fabrication of the device required significant advances in the optical lithography of SU-8 negative photoresist. Research proved that aspect-ratios up to 40:1 in isolated open field structures of thickness between 1 and …