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Articles 1 - 30 of 98
Full-Text Articles in Engineering
The Determination Of Appropriate Phosphogypsum: Class C Fly Ash : Portland Type Ii Cement Compositions For Use In Marine Applications, Pradyot Sudhakar Deshpande
The Determination Of Appropriate Phosphogypsum: Class C Fly Ash : Portland Type Ii Cement Compositions For Use In Marine Applications, Pradyot Sudhakar Deshpande
LSU Master's Theses
Phosphogypsum (PG, CaSO4·2H2O) is a waste by-product produced during the wet manufacturing phosphoric acid process. Phosphoric acid is manufactured by processing phosphate rock that contains relatively high concentrations of naturally occurring radioactive impurities which makes PG a radioactive material. PG also contains certain trace metals including As, Ba, Cd, Cr and Pb and radioactive contaminants such as Radium226 and Uranium238 that pose potential hazard to human health and the environment. According to USEPA, the current allowable disposal method for PG is stack piling. This research was focused on stabilizing PG with Portland Type II …
Circuitry For A Remotely Powered Bio-Implantable Gastric Electrical Stimulation System, Satish Kona
Circuitry For A Remotely Powered Bio-Implantable Gastric Electrical Stimulation System, Satish Kona
LSU Master's Theses
Power to bio-implantable devices is usually supplied through a battery implanted with the system or through wires extending to an outside power source. The latter case with wires protruding out of the body can be unaesthetic in appearance and can cause infection. In this research, we consider an alternative way to power a bio-implantable microsystem. It involves using rechargeable lithium batteries. Here, power is delivered remotely to charge implanted battery or batteries. This approach avoids periodic surgery necessary for battery replacement. It also does not tie a person to an external power source at all times. This improves patient’s quality …
Forced Bubble Columns, Jia Ma
Forced Bubble Columns, Jia Ma
LSU Master's Theses
In many chemical, biochemical and pharmaceutical industrial processes, bubble breakage is very important for gas component to dissolve and react with surrounding liquid. The overall mass transfer performance can be improved greatly when the interfacial gas-liquid area is increased due to bubble breakup. In forced bubble columns operating at low forcing frequency (<30Hz) and small forcing amplitude (<3mm), bubbles undergo phenomenal breakage. Mass transfer coefficient, kLa, is increased to 250%~625% of the no forcing value depending on flow regime and configuration of membrane and piston. Two different mechanisms, induced shear slug breakage in the gas feeder tube for bubbly flow and resonant frequency bubble breakage in the column fluid phase for jet flow, seem to at work.
The Rapid Template Fabrication Process For Producing A Liga Heat Exchanger Bonded To A Mechanical Seal, Jason Patrick Tuma
The Rapid Template Fabrication Process For Producing A Liga Heat Exchanger Bonded To A Mechanical Seal, Jason Patrick Tuma
LSU Master's Theses
Mechanical seals are widely used in the chemical processing, aerospace, and automotive, industries. When a mechanical seal fails, considerable cost is typically involved in replacing the seal. Most seal failures are a result of high temperatures generated by frictional heating. Effectively removing the heat generated would significantly increase the mechanical seal’s work life and lead to significant monetary savings. One method of removing the heat generated is bonding an effective LIGA micro heat exchanger to the mechanical seal and forcing coolant through the heat exchanger. Previous work on this subject revealed promising results, especially for micro heat exchangers with microstructures …
Structure And Mechanical Properties Of Ti-Si-N Coatings, Xiaodong Zhang
Structure And Mechanical Properties Of Ti-Si-N Coatings, Xiaodong Zhang
LSU Master's Theses
In order to better define conditions under which ~{!0~}super-strengthening~{!1~} occurs in the Ti-Si-N system, we performed detailed experimental studies on how the structure and mechanical properties of Ti-Si-N coatings are influenced by the deposition temperature. Different series of Ti-Si-N specimens were prepared in an inductively coupled plasma (ICP)-assisted reactive sputtering system at both low and high temperatures. Coating compositions were measured by Rutherford backscattering spectrometry (RBS) technique, surface roughness was examined on an atomic force microscope (AFM), coating thicknesses were obtained by performing cross-sectional scanning electron microscopy (SEM), and their structure examined with transmission electron microscopy (TEM). Vibrational frequency results …
Large Eddy Simulations Of Complex Turbulent Flows, Mayank Tyagi
Large Eddy Simulations Of Complex Turbulent Flows, Mayank Tyagi
LSU Doctoral Dissertations
In this dissertation a solution methodology for complex turbulent flows of industrial interests is developed using a combination of Large Eddy Simulation (LES) and Immersed Boundary Method (IBM) concepts. LES is an intermediate approach to turbulence simulation in which the onus of modeling of “universal” small scales is appropriately transferred to the resolution of “problem-dependent” large scales or eddies. IBM combines the efficiency inherent in using a fixed Cartesian grid to compute the fluid motion, along with the ease of tracking the immersed boundary at a set of moving Lagrangian points. Numerical code developed for this dissertation solves unsteady, filtered …
Optimal Batch Quantity Models For A Lean Production System With Rework And Scrap, Pablo Biswas
Optimal Batch Quantity Models For A Lean Production System With Rework And Scrap, Pablo Biswas
LSU Master's Theses
In an imperfect manufacturing process, the defective items are produced with finished goods. Rework process is necessary to convert those defectives into finished goods. As the system is not perfect, some scrap is produced during this process of rework. In this research, inventory models for a single-stage production process are developed where defective items are produced and reworked, where scrap is produced, detected and discarded during the rework. Two policies of rework processes are considered (a) First policy: rework is done within the cycle, and (b) Second policy: rework is done after N cycles of normal production. Also, three types …
Development Of A Performance-Based Design Approach And Related Loads For Facilities Designated As Essential During A Hurricane Event, Joffrey Elliott Easley
Development Of A Performance-Based Design Approach And Related Loads For Facilities Designated As Essential During A Hurricane Event, Joffrey Elliott Easley
LSU Master's Theses
Historically, shelters and other facilities designated as "essential" during hurricanes have experienced unacceptable damage during recent hurricanes, exposing the occupants to uncomfortable and dangerous conditions. One of the reasons for this is the lack of standards or design guidelines addressing the special considerations required for such facilities. A new approach to the design of essential facilities in hurricane regions is proposed. The goal of this work is to create a tool for improving the safety and serviceability of evacuation shelters and other critical facilities utilized during hurricane events. This is achieved by developing a new philosophy based on selection of …
Heat Transfer In Outdoor Aquaculture Ponds, Jonathan Lamoureux
Heat Transfer In Outdoor Aquaculture Ponds, Jonathan Lamoureux
LSU Master's Theses
An energy balance was developed for heated and unheated earthen aquaculture ponds to 1) determine the relative importance of energy transfer mechanism affecting pond temperature; 2) predict pond temperatures; 3) estimate the energy required to control pond temperatures, and 4) recommend efficient heating and cooling methods. PHATR (Pond Heating and Temperature Regulation), a computer program using 4th order Runge-Kutta numerical method was developed to solve the energy balance using weather, flow rate and pond temperature data. By comparing measured and modeled pond temperatures, the average difference (the average bias) was 0.5°C for unheated ponds and 2.4°C for heated ponds. The …
Analytical Study On Flood Induced Seepage Under River Levees, Senda Ozkan
Analytical Study On Flood Induced Seepage Under River Levees, Senda Ozkan
LSU Doctoral Dissertations
A common and potentially dangerous phenomenon associated with flooding is seepage under levees and the formation of sand boils. Seepage flow due to hydrostatic head gradients of floods may cause deformation of pervious layers leading to heave, piping and sand boils. Underseepage may also cause irreversible changes in the characteristics of the porous medium. A series of independent flood events may have cumulative effects on pervious layers causing sand boils to grow. Current underseepage analyses for levees are based on steady-state flow. Transient seepage flow due to rapid changes in river head may contribute to cumulative effects and cause critical …
Hydrodynamic And Sediment Transport Modeling Of Deltaic Sediment Processes, Hassan Shahid Mashriqui
Hydrodynamic And Sediment Transport Modeling Of Deltaic Sediment Processes, Hassan Shahid Mashriqui
LSU Doctoral Dissertations
This dissertation tests the hypothesis that the early phases of deltaic bar and distributary channel formation and sediment transport on an adverse slope could be simulated with a 2D finite element sediment transport model. The models used were RMA2 and SED2D modules of the TABS-MD model suite. A finite element mesh of the lower Atchafalaya River and the delta was developed, using the Surface Water Modeling System (SMS) software package. Calibration and validation of the model were performed, using data collected during field surveys and from available Atchafalaya River archived flow, suspended sediment, and dredging records. In a test simulation …
Staying Afloat: A Risk Analysis Study Of Flooding In South Louisiana, Marlene Tomaszkiewicz
Staying Afloat: A Risk Analysis Study Of Flooding In South Louisiana, Marlene Tomaszkiewicz
LSU Master's Theses
For decades, South Louisiana has been battling with flood risk. The area has been inundated with flood waters several times, whether it is due to tropical weather, strong rainfall events, or rising waters. This has resulted in millions of dollars in damages, and in some instances, the same home has been affected multiple times. Many agree that South Louisiana is just not a livable area to begin with; the risk is just too great. However, abandoning the area is simply not an option. As a result, the flood risk battle ensues. How much risk are we talking about? The Federal …
Characterization Of Syntactic Foams And Their Sandwich Composites: Modeling And Experimental Approaches, Nikhil Gupta
Characterization Of Syntactic Foams And Their Sandwich Composites: Modeling And Experimental Approaches, Nikhil Gupta
LSU Doctoral Dissertations
Hollow particle filled polymers known as syntactic foams are lightweight and highly damage tolerant. Syntactic foams are used as core materials in sandwich composites. The use of such materials in aeronautical and space structures make it necessary to understand their characteristics for various environmental and loading conditions. The first part of the present work takes modeling and finite element analysis approach to understand and predict the deformation behavior of syntactic foams. Contact analysis is performed on single particle models by the finite element analysis approach. In the second part extensive experiments are carried out to characterize syntactic foams for hygrothermal …
Optimization And Automation Of A Thermal Oyster Shucking Process, Daniel Edgar Martin
Optimization And Automation Of A Thermal Oyster Shucking Process, Daniel Edgar Martin
LSU Doctoral Dissertations
Louisiana Gulf Coast oysters (Crassostrea virginica) were subjected to thermal shucking treatments to effect adductor muscle release from both left and right valves. The oysters were instrumented with thermocouples to monitor and record process temperatures in the oysters and on the shell. Following treatment, the oysters were evaluated for relaxation and release of the adductor muscle, meat quality and texture, and for the effect of the treatments on the storage life of the oysters as measured by total microbial plate counts. The treatments of many oysters resulted in a complete release of the adductor muscle from the shell while maintaining …
Treatment Of Chlorinated Volatile Organic Compounds Using Wetland Systems, Gabriel Roderick Kassenga
Treatment Of Chlorinated Volatile Organic Compounds Using Wetland Systems, Gabriel Roderick Kassenga
LSU Doctoral Dissertations
Bench-scale continuous vertical flow column and microcosm studies were conducted to investigate the attenuation potential of chlorinated volatile organic compounds (CVOCs) in constructed wetland soil mixtures prepared from peat, compost and sand and in a pristine natural freshwater wetland soil. The study also determined geotechnical properties of potential synthetic peat mixtures for construction of treatment wetlands for CVOCs. Trichloroethene (TCE), cis-1,2-dichloroethene (cis-1,2-DCE) and 1,2-dichloroethane (1,2-DCA) were the main test chemicals used during the studies. Based on geotechnical and sorption characteristics, two mixtures (one comprised of sand and peat and the other comprised of sand, peat and compost product) were selected …
Solute Transport In A Porous Medium: A Mass-Conserving Solution For The Convection-Dispersion Equation In A Finite Domain, William Golz
Solute Transport In A Porous Medium: A Mass-Conserving Solution For The Convection-Dispersion Equation In A Finite Domain, William Golz
LSU Doctoral Dissertations
This dissertation considers the proper mathematical description for the physical problem of a miscible solute undergoing longitudinal convective-dispersive transport with constant production, first-order decay, and equilibrium sorption in a porous medium. Initial and input concentrations may be any continuously differentiable functions and the mathematical system is articulated for a finite domain. This domain yields a mass balance which requires Robin (i.e., third-type) boundaries, which describe a continuous flux but a discontinuous resident-concentration. The discontinuity in the resident concentration at the outflow boundary yields an underdetermined system when the exit concentration is not experimentally measured. This is resolved by defining the …
Adsorption Of Aromatic Hydrocarbons At Gas-Water Interface, Suresh Raja
Adsorption Of Aromatic Hydrocarbons At Gas-Water Interface, Suresh Raja
LSU Master's Theses
Adsorption of organic vapors at a gas-water interface has several physical applications with respect to natural processes in the environment. Understanding the adsorption processes is critical in development of risk assessment and modeling of transport and fate of various chemical species that are abundantly present in the environment. Evidences from the works of several researchers point out deviations in gas-liquid partitioning as predicted by Henry’s law. In view of several theories that describe these deviations, adsorption process is hypothesized to be significant in gas-liquid partitioning, in addition to temperature and presence of organic matter, particularly on liquid surfaces with high …
A Screening Assessment Of Solidification/Stabilization For Storm Water Residuals, Erin Ezell Krielow
A Screening Assessment Of Solidification/Stabilization For Storm Water Residuals, Erin Ezell Krielow
LSU Master's Theses
Metal species infused particulate matter associated with urban rainfall-runoff is a unique and profuse source of pollution. Generated from urban activities, such as traffic activity and vehicular/infrastructure abrasion, contaminated residual material is deposited to roadways during dry weather and transported to surrounding environments and/or best management practice (BMP) treatment facilities during wet-weather events. These particulates range in size from 1 ƒÝm to 10000 ƒÝm and are contaminated with metal species that originate from such sources as vehicular body wear (Cu), tire wear (Zn), and brake dust (Pb). Depending on the efficiencies of the BMP treatment facilities, these containment systems have …
Biomechanical Effects Of Cyclic Loading On The Lower Back, Lakiesha Claude
Biomechanical Effects Of Cyclic Loading On The Lower Back, Lakiesha Claude
LSU Master's Theses
More than 30 million people in the United States may have low back pain at any time, and 10 million of them have chronic symptoms. Epidemiological studies indicate that along with axial compressive loads, other factors including repetitive twisting or lateral bending and lifting are significant risk factors for low-back disorders. Literature repeatedly confirms that cyclic occupational functions expose workers to a 10-fold increase in episodes of low back injury and pain. This study examined the biomechanical effects of cyclical loading on the lower back. Twenty in vivo feline preparations were subjected to passive cyclic loading at 20 N (n=6), …
Rainfall-Runoff Control: Variably Saturated Transport For An Infiltration System Controlling Water Quality And Quantity, Zheng Teng
LSU Doctoral Dissertations
Rainfall-runoff impacted by anthropogenic activities transports significant quantities of particulate, aqueous and complexed constituents. These diffuse, unsteady and stochastic event-based loadings are unique challenges for water quality and quantity control. The design, water quality and quantity functions of a partial exfiltration reactor (PER) utilizing Fe-coated-sand and porous pavement (CPP) is examined specifically across three representative rainfall-runoff events. Total concentrations and mass for metals (Zn, Pb, Cu and Cd), suspended solids, and Chemical oxygen demand were reduced significantly. Rainfall-runoff volume and peak flow were reduced and time to peak was extended. Influent dm/dp ratios based on particle analyses suggest that the …
Thermohydrodynamic Analysis Of Compressible Gas Flow In Compliant Foil Bearings, Zhengchun Peng
Thermohydrodynamic Analysis Of Compressible Gas Flow In Compliant Foil Bearings, Zhengchun Peng
LSU Master's Theses
This thesis deals with the development of mathematical models and numerical schemes for simulating the hydrodynamic pressure and temperature rise of compliant foil bearings lubricated by a thin gas film in between its compliant bearing surface and the rotating shaft. The model accounts for the compressibility of gas, the compliance of the bearing surface, and the interaction between the pressure field and temperature field of the gas film in the bearing system. Numerical solutions obtained over a fairly large range of operating speeds show excellent agreement with existing experimental data from both load performance test and bearing temperature measurement. A …
Modeling And Evaluating Evacuation Contraflow Termination Point Designs, Yu Yik Lim
Modeling And Evaluating Evacuation Contraflow Termination Point Designs, Yu Yik Lim
LSU Master's Theses
Prior studies showed that most evacuation contraflow designs have never been implemented. As a result, the effectiveness of these contraflow termination point designs remains unknown. To address this problem, a microscopic traffic simulation tool, CORSIM 5.0, was used. Ten simulation models were conducted and determined the factors that affect traffic operations in the vicinity of the various planned contraflow termination point with median crossover designs. The performance of various models was ranked by statistical test in terms of the total number of vehicles processed, traffic flow, speed, density and delay. The results that were based on theoretical simulations and assumptions …
Precipitate Growth Features In The Duplex Size Gamma Prime Distribution In The Superalloy In738lc, Indranil Roy
Precipitate Growth Features In The Duplex Size Gamma Prime Distribution In The Superalloy In738lc, Indranil Roy
LSU Master's Theses
IN738LC is a modern, nickel base superalloy utilized at high temperatures in aggressive environments. Durability of this superalloy is dependent on the retention of strengthening by Gamma Prime precipitates. The precipitate growth features in the duplex size (fine and coarse) precipitate distribution was studied by heating the alloy for various times in vacuum at selected temperatures in the range 800 °C to 1100 °C. Increasing the holding times from 1 hour to 100 hours shows joining of the fine particles to form bigger particles, leading to distinct raft patterns. Two different Gamma Prime precipitate growth processes had been observed: merging …
Minimization Of Power Losses In Active Magnetic Bearing Control, Nader Motee
Minimization Of Power Losses In Active Magnetic Bearing Control, Nader Motee
LSU Master's Theses
A solution to the problem of AMB control with reduced electrical power losses will be presented in this thesis. The proposed control solution will be founded on the integrator backstepping technique, which decouples the rotor stabilization problem from the bias flux design problem. It further allows for the easy redesign of the control law to compensate for uncertainties in the AMB system. A class of nonlinear controllers will be developed that reduces the AMB power losses in comparison to standard fixed-bias controllers, while containing no control singularity. Control laws will be presented for the standard AMB operating mode where both …
Design Of Optimal Equalizers And Precoders For Mimo Channels, Lijuan Li
Design Of Optimal Equalizers And Precoders For Mimo Channels, Lijuan Li
LSU Doctoral Dissertations
Channel equalization has been extensively studied as a method of combating ISI and ICI for high speed MIMO data communication systems. This dissertation focuses on optimal channel equalization in the presence of non-white observation noises with unknown PSD but bounded power-norm. A worst-case approach to optimal design of channel equalizers leads to an equivalent optimal H-infinity filtering problem for the MIMO communication systems. An explicit design algorithm is derived which not only achieves the zero-forcing (ZF) condition, but also minimizes the RMS error between the transmitted symbols and the received symbols. The second part of this dissertation investigates the design …
Electrodeposition Of Nickel-Copper Alloys And Nickel-Copper-Alumina Nanocomposites Into Deep Recesses For Mems, Amrit Panda
Electrodeposition Of Nickel-Copper Alloys And Nickel-Copper-Alumina Nanocomposites Into Deep Recesses For Mems, Amrit Panda
LSU Doctoral Dissertations
Electrodeposition is an important component in the fabrication of micro electro mechanical systems (MEMS). Nickel is the most commonly used material to produce three dimensional microstructures and few material alternatives have been demonstrated. In this dissertation, electrodeposited Ni-Cu alloys and nanocomposites are investigated as possible replacements for nickel in microsystems. Ni-Cu alloys are attractive for their corrosion resistance, magnetic and thermophysical properties. Alumina nanoparticulates included into metal matrices improve hardness and tribology of deposits. The Ni-Cu alloys and Ni-Cu-g-Al2O3 nanocomposites were electrodeposited from a citrate electrolyte, both at low and high pH. Electrodeposition experiments were performed in recessed microelectrodes 500 …
Granulometry, Chemistry And Physical Interactions Of Non-Colloidal Particulate Matter Transported By Urban Storm Water, Hong Lin
LSU Doctoral Dissertations
Urban rainfall-runoff is a major source of anthropogenic pollutions to the natural water bodies. Particulate matter generated from anthropogenic environments and activities is a constituent of environmental concern as well as a carrier substrate for reactive contaminants such as metals. Partitioning, transport and transformation of particulate-bound contaminants are determined by the granulometry, physical and geochemical properties of the particulate carriers. Previous research emphasized in the transport of colloidal and suspended particles in rainfall-runoff. The settleable and sediment material were ignored though they are a major granulometric fraction which may contain most of the sorbed or transported constituents such as metals, …
Assessing Sample Bias And Establishing Standardized Procedures For Weighting And Expansion Of Travel Survey Data, Fahmida Nilufar
Assessing Sample Bias And Establishing Standardized Procedures For Weighting And Expansion Of Travel Survey Data, Fahmida Nilufar
LSU Master's Theses
Recent household travel surveys are encountering problems with non-response, non-coverage, non-reporting, and even incorrect or incomplete reporting of trips. In addition, data from survey samples are affected by the social, and economic conditions of the respondents, as well as the survey instrument used to collect the data. As a result, household travel survey data are invariably associated with some level of bias. These threats to the integrity of the data are often ignored while analyzing the sample survey data. However, considering the importance of information derived from such surveys, it is necessary that the survey must provide an accurate reflection …
Manufacturing And Analysis Of A Liga Heat Exchanger For The Surface Of A Tube: A Cooling Simulation Of The Leading Edge Region Of A Turbine Blade, Christophe Marques
Manufacturing And Analysis Of A Liga Heat Exchanger For The Surface Of A Tube: A Cooling Simulation Of The Leading Edge Region Of A Turbine Blade, Christophe Marques
LSU Doctoral Dissertations
Fabricating nickel micro heat exchangers directly on planar or non-planar metal surfaces has been demonstrated using the LIGA micromachining process. These heat exchangers can effectively control the temperature of surfaces in high heat flux applications. Of particular interest is the temperature control of gas turbine engine components. The locations in the gas turbine engine where improved, efficient cooling is required includes gas turbine blades, stator vanes, the turbine disk, and the combustor liner. In this dissertation, the primary application of interest is the use of such heat exchangers to cool airfoils such as turbine blades. In the first part of …
Design Of Power Efficient Multicast Algorithms For Sparse Split Wdm Networks, Kavitha Devi Buddharaju
Design Of Power Efficient Multicast Algorithms For Sparse Split Wdm Networks, Kavitha Devi Buddharaju
LSU Master's Theses
Recent years witnessed tremendous increase in data traffic as new Internet applications were launched. Optical networks employing recent technologies such as DWDM and EDFA`s emerged as the most prominent and most promising solutions in terms of their ability to keep with the demand on bandwidth. However for a class of applications bandwidth is not the only important requirement, These applications require efficient multicast operations. They include data bases, audio/video conferencing, distributed computing etc. Multicasting in the optical domain however has its own unique set of problems. First, an optical signal can be split among the outputs of a node but …