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LSU Doctoral Dissertations

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Articles 211 - 220 of 220

Full-Text Articles in Civil and Environmental Engineering

Solute Transport In A Porous Medium: A Mass-Conserving Solution For The Convection-Dispersion Equation In A Finite Domain, William Golz Jan 2003

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 …

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Rainfall-Runoff Control: Variably Saturated Transport For An Infiltration System Controlling Water Quality And Quantity, Zheng Teng Jan 2003

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 …

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Granulometry, Chemistry And Physical Interactions Of Non-Colloidal Particulate Matter Transported By Urban Storm Water, Hong Lin Jan 2003

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, …

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Investigation Of Bond Slip Between Concrete And Steel Reinforcement Under Dynamic Loading Conditions, John Henry Weathersby Jan 2003

Investigation Of Bond Slip Between Concrete And Steel Reinforcement Under Dynamic Loading Conditions, John Henry Weathersby

LSU Doctoral Dissertations

Structural failures during recent earthquakes and terrorist attacks have demonstrated shortcomings in the design procedures for reinforced concrete structures. Earlier research has demonstrated that a major limitation of the Finite Element (FE) modeling of the response of reinforced concrete is the accurate modeling of the interaction of the concrete with the steel reinforcement. Presently, there are insufficient data on the dynamic nonlinear interaction between the concrete material and the steel reinforcement to develop a numerical model of this interaction. The primary objective of this study was to experimentally investigate the dynamic interaction (bond slip) of reinforcement with concrete and gain …

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Optimization Of The Light Dynamics In The Hydraulically Integrated Serial Turbidostat Algal Reactor (Histar), Barbara Christine Benson Jan 2003

Optimization Of The Light Dynamics In The Hydraulically Integrated Serial Turbidostat Algal Reactor (Histar), Barbara Christine Benson

LSU Doctoral Dissertations

The research objective was the optimization of light dynamics in a Hydraulically Integrated Serial Turbidostat Algal Reactor (HISTAR). A deterministic model of HISTAR productivity that was responsive to manipulations of photosynthetic photon flux fluence rate (PPFFR) was developed, calibrated, and applied. A series of experiments was conducted to define the mathematical equations that best describe three relationships. The first relationship was between the elevation (E) of the light source and the culture surface PPFFR (Io). The second relationship was between the biomass concentration (X) in the experimental unit and the average PPFFR in the reactor (Ia). …

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Clay Landfill Liners Subject To Variable Interfacial Redox And Ph Conditions-Heavy Metal And Clay Interactions, Ping Zhou Jan 2003

Clay Landfill Liners Subject To Variable Interfacial Redox And Ph Conditions-Heavy Metal And Clay Interactions, Ping Zhou

LSU Doctoral Dissertations

Municipal landfill leachate contains high levels of metal species, including Cu, Zn, Cd and Pb generating competitive interactions between these metal species and the landfill clay liner materials. Characterization of the clay fraction, physical and chemical characteristics of landfill clay liner materials, the competitive interaction of metal species with clay liner materials, the kinetic modeling of metal species transport in clay liner, and the effect of cyclic interfacial redox potential on the structural changes to the clay liner and leachate metal transport were investigated in this study. The clay liner materials studied included Na-bentonite, kaolinite and Amite soil (sandy silty …

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Cementitious Stabilization Of Soils In The Presence Of Sulfate, Lan Wang Jan 2002

Cementitious Stabilization Of Soils In The Presence Of Sulfate, Lan Wang

LSU Doctoral Dissertations

Winn Rock (anhydrite, CaSO4) comes from a quarry in Winn Parish in north Louisiana. Gravel from the quarry has been used extensively as a surface course on local parish and logging roads. Stabilization of these roads with Type I Portland cement followed by an overlay by asphaltic concrete sometimes resulted in heaving. The causes for heaving and possible solutions were investigated. In the laboratory 2" x 4" molds of Winn Rock containing soil were prepared and cured in water bath at 40°C, sealed plastic bag at room temperature, and air. Molds were prepared with 5% to 20% cementitious material. The …

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A Variable Response Time Lag Module For Car Following Models Using Fuzzy Set Theory, Yilmaz Hatipkarasulu Jan 2002

A Variable Response Time Lag Module For Car Following Models Using Fuzzy Set Theory, Yilmaz Hatipkarasulu

LSU Doctoral Dissertations

Since the 1950s, car following phenomena have been studied and analyzed, resulting in various models and algorithms. In general, the car following process has been defined as a stimulus-response relationship in which the driver of the following vehicle reacts to the actions of the lead vehicle after a time lag. One of the fundamental assumptions that underlie car following theory is that the driver response time lag is always a constant value for the driver at all times, regardless of level of detail of the model. Assumption of a constant time lag value introduces a number of broad assumptions however, …

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Extraction Of Physically-Realistic Pore Network Properties From Three-Dimensional Synchrotron Microtomography Images Of Unconsolidated Porous Media, Riyadh Ibrahim Al-Raoush Jan 2002

Extraction Of Physically-Realistic Pore Network Properties From Three-Dimensional Synchrotron Microtomography Images Of Unconsolidated Porous Media, Riyadh Ibrahim Al-Raoush

LSU Doctoral Dissertations

Algorithms were implemented to obtain high resolution three-dimensional images using synchrotron microtomography. Morphological algorithms were developed to extract physically-realistic pore-network structure from unconsolidated porous media systems imaged using synchrotron microtomography. The structure can be used to correlate pore-scale phenomena with the pore structure and can also be incorporated into a pore-network model to verify existing models, understand, or predict transport and flow processes and phenomena in complex porous media systems. The algorithms are based on the three-dimensional skeletonization of the pore space in the form of nodes connected to paths. Dilation algorithms were developed to generate inscribed spheres on the …

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Heavy Metal Distribution For Aqueous And Solid Phases In Urban Runoff, Snowmelt And Soils, Donald W. Glenn Iii Jan 2001

Heavy Metal Distribution For Aqueous And Solid Phases In Urban Runoff, Snowmelt And Soils, Donald W. Glenn Iii

LSU Doctoral Dissertations

At the start of the third millennium, over 50% of the world’s population lives in urban areas. Anthropogenic activities associated with urban development such as traffic generate significant particulate and heavy metal mass loadings. Ten urban highway sites located throughout the metropolitan area of Cincinnati, Ohio were studied. Storm water, snow and transportation land use soil/residual complexes (RSCs) were collected at each site. For the storm water, results are presented for a series of eight rainfall runoff events over a two-year period and included analyses between dissolved and particulate-bound fractions of heavy metals (Pb, Cu, Cd and Zn), and water …

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