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2008

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Articles 991 - 997 of 997

Full-Text Articles in Civil and Environmental Engineering

Electromagnetic Modeling Of Distributed Coaxial Cable Crack Sensors In Reinforced Concrete Members, Mei Wang Jan 2008

Electromagnetic Modeling Of Distributed Coaxial Cable Crack Sensors In Reinforced Concrete Members, Mei Wang

Masters Theses

"Distributed crack sensors were recently developed with coaxial cables that are composed of inner and outer conductors as well as dielectric layer in between. These sensors were designed based on the change in topology of the cable outer conductor structure under strain effects. Various tests of reinforced concrete (RC) beams and columns indicated that the newly designed sensors are 10~50 times more sensitive than commercial cables to the longitudinal elongation applied on their cable structures. The spatial resolution of the sensors is approximately 50 mm. Limited numerical simulations with the transmission line theory and the finite difference time domain model …

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Investigating The Effect Of Stress, Wetting, And Compaction On Settlement Potential Of Mine Spoils, Lauren M. Little Jan 2008

Investigating The Effect Of Stress, Wetting, And Compaction On Settlement Potential Of Mine Spoils, Lauren M. Little

University of Kentucky Master's Theses

Strip mining in Kentucky has left large areas of land that could potentially be used for business and housing developments. However, the mine spoils underlying these areas are prone to severe differential settlement due to a variety of factors. Mine spoil from the Gateway Business Park in Jenkins, Kentucky was used for a series of laboratory tests to develop relationships between shear wave velocity, confining stress, compaction energy, and dry unit weight to develop a method to assess settlement potential. It was found that a stress-corrected shear wave velocity of greater than 275 ft/s/psi0.25 typically indicated dry mine spoil, …

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Production Of Low-Energy, 100% By-Product Cement Utilizing Coal Combustion Products, David E. Rust Jan 2008

Production Of Low-Energy, 100% By-Product Cement Utilizing Coal Combustion Products, David E. Rust

University of Kentucky Master's Theses

The ever-increasing quantity of by-products generated from burning coal in the production of electricity has brought about the need for new areas of utilization. This study examined the use of FGD gypsum and fluidized bed combustion ash along with Class F fly ash in the production of low-energy, 100% by-product cement blends. The cement blends used the advantageous properties of the by-product materials to create cementing properties rather than energy intensive clinker used in ordinary portland cement. The FGD gypsum was converted to hemihydrate which rapidly hydrated to provide the cement with early strength gains, whilst the fluidized bed combustion …

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Optimization Of Treatment Of Chlorinated Volatile Organic Compound Mixtures In Constructed Wetlands: Vegetation And Substrate Effects, Stephen Emmanuel Mbuligwe Jan 2008

Optimization Of Treatment Of Chlorinated Volatile Organic Compound Mixtures In Constructed Wetlands: Vegetation And Substrate Effects, Stephen Emmanuel Mbuligwe

LSU Doctoral Dissertations

Microcosm and mesocosm scale experiments were carried out to investigate the effects of vegetation and substrates on the performance of engineered wetland systems (EWSs) meant to treat mixtures of volatile organic compounds (cVOCs). The experiments were conducted with a view to optimizing contributions of these wetland components. Phragmites communis and Typha latifolia, the commonest wetland plant species, were compared in mesocosm scale EWSs. Eight common wetland plant species were compared using microcosm experiments based on the potential of their rootmatter to enhance treatment of cVOC mixtures. Twelve common wetland plants were similarly compared but on the basis of their aboveground …

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Redutive Dehalogenation Of Chlorinated Alkanes By Novel Bacteria At The Petroprocessor Of Louisiana Inc. Superfund Site, Jun Yan Jan 2008

Redutive Dehalogenation Of Chlorinated Alkanes By Novel Bacteria At The Petroprocessor Of Louisiana Inc. Superfund Site, Jun Yan

LSU Doctoral Dissertations

A reductively dehalogenating enrichment culture was established using chloroalkane-contaminated groundwater from the PetroProcessors of Louisiana, Inc. (PPI) Superfund site. Two novel, strictly anaerobic bacterial strains, designated as BL-DC-8 and BL-DC-9, were isolated from the enrichment culture. These strains represent the first bacteria known to anaerobically dehalogenate 1,2,3-trichloropropane, the degradation pathway of which was determined. Both strains could be cultured in completely defined basal medium and were also able to dehalogenate a variety of other vicinally chlorinated alkanes including 1,1,2,2-tetrachloroethane, 1,1,2-trichloroethane, 1,2-dichloroethane, and 1,2-dichloropropane via dichloroelimination reactions. Chlorinated alkanes containing only a single chlorine substituent (1-chloropropane, 2-chloropropane), chlorinated alkenes (tetrachloroethene, trichloroethene, …

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Bayesian Model Averaging On Hydraulic Conductivity Estimation And Groundwater Head Prediction, Xiaobao Li Jan 2008

Bayesian Model Averaging On Hydraulic Conductivity Estimation And Groundwater Head Prediction, Xiaobao Li

LSU Doctoral Dissertations

Characterization of aquifer heterogeneity is inherently difficult because of the insufficiency of data, the inflexibility of parameterization methods, and non-uniqueness of parameterization methods. Groundwater predictions are greatly affected by multiple interpretations of aquifer properties and the uncertainties of model parameters. This study introduces a Bayesian model averaging (BMA) method along with multiple generalized parameterization (GP) methods to identify hydraulic conductivity and along with multiple simulation models to predict groundwater head and quantify the prediction uncertainty. Two major issues about BMA are discussed. The first problem is with using Occam’s window in usual BMA applications. Occam’s window only accepts models in …

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Lattice Boltzmann Modeling For Mass Transport Equations In Porous Media, Borja Servan Camas Jan 2008

Lattice Boltzmann Modeling For Mass Transport Equations In Porous Media, Borja Servan Camas

LSU Doctoral Dissertations

The aim of this dissertation is to extend the lattice Boltzmann method (LBM) to cope with parameter heterogeneity and anisotropy in mass transport equations in porous media, as well as investigating the stability and accuracy. Although the LBM is a well known and effective numerical method to solve fluid flows, LBM has not been extensively applied to mass transport equations in porous medium flow yet, and only a few works can be found on improving LBM to cope with mass transport equations other than the diffusion and advection-diffusion equations. One of the reasons why LBM has not been extensively used …

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