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Failure Predictions In Repairable Multi-Component Systems., Woodrow Thomas Roberts Jr
Failure Predictions In Repairable Multi-Component Systems., Woodrow Thomas Roberts Jr
LSU Historical Dissertations and Theses
The subject of this research is the prediction of failures in repairable multi-component systems from statistical models that utilize the historical failure data for the systems. Failures occurring in repairable systems are examples of a series of discrete events which occur randomly in a continuum. Such stochastic point processes are analyzed using the statistics of event series. The Crow nonhomogenous Poisson process, NHPP, model is recognized by the reliability community as being one of the best models for repairable systems. The objective of this research is to show that the Crow NHPP model, with its overall failure predictions for a …
Three-Dimensional Nonlinear Analysis Of Components Of Reinforced Concrete Framed Structures., Srinivas Maddipudi
Three-Dimensional Nonlinear Analysis Of Components Of Reinforced Concrete Framed Structures., Srinivas Maddipudi
LSU Historical Dissertations and Theses
This study deals with the three dimensional analysis of reinforced concrete structural members under multiaxial loading conditions. An incremental formulation in conjunction with the finite element method is used to simulate the behavior of reinforced concrete material. A hypoelastic model capable of simulating response of plain concrete under nonproportional loading conditions is employed. A five parameter strength envelope is used to predict the failure of concrete in multiaxial stress states. A smeared crack model capable of handling multiple non-orthogonal cracks is used to represent the post cracking behavior of concrete. Objectivity in the results of analysis utilizing the smeared cracking …
Assimilation Of Organic Contaminants In Wetlands: Processes And A Conceptual Model., John Howard Pardue
Assimilation Of Organic Contaminants In Wetlands: Processes And A Conceptual Model., John Howard Pardue
LSU Historical Dissertations and Theses
Laboratory studies and field measurements were conducted to quantify assimilative capacity of toxic organic contaminants in freshwater wetlands. Studies were conducted for hexachlorobenzene and naphthalene in a mineral-dominated bottomland hardwood forest and an organic matter-dominated freshwater marsh. In laboratory studies, sorption of hexachlorobenzene (HCB) in wetland soil and floodwater was strongly influenced by high levels of naturally occurring dissolved organic carbon (DOC). Organic matter-dominated wetlands (e.g., marshes) demonstrated no advantage over mineral-dominated wetlands (e.g., bottomland hardwood forests) for sorption of HCB due to partitioning in this DOC phase. Over the short-term, sorption of HCB was adequately described using a three-phase …
The Effects Of Organoclay Adsorption On The Solidification Of Organic Wastes., Adam Faschan
The Effects Of Organoclay Adsorption On The Solidification Of Organic Wastes., Adam Faschan
LSU Historical Dissertations and Theses
The effects of organoclay adsorption on the leaching performance of solidified organic wastes was researched. Adsorption isotherms were developed for the adsorption of 1,2-dichlorobenzene (DCB), nitrobenzene (NB), and phenol by five different organoclays. Simulated liquid wastes containing DCB, NB, and phenol were solidified utilizing various combinations of Type I Portland cement and the five organoclays. The ratio of cement/clay utilized in each solidification matrix varied from 3/2 to 13/2. Linear and Langmuir adsorption isotherm models were utilized to predict the leaching performance of samples cured for 7, 28, and 90 days. The ratio of the actual leachate concentrations compared to …
Soot Suppressing Mechanisms Of Iron In Premixed Hydrocarbon Flames., David Worthington Hahn
Soot Suppressing Mechanisms Of Iron In Premixed Hydrocarbon Flames., David Worthington Hahn
LSU Historical Dissertations and Theses
In-situ light scattering measurements are combined with chemical analysis of sampled soot particles to elucidate the mechanisms through which iron addition affects soot formation and growth processes in fuel-rich, premixed propane and oxygen flames. Soot particle optical inhomogeneity resulting from the addition of iron is accounted for in the light scattering analysis using an effective refractive index model. The influence of iron addition on soot particle diameters, number densities, volume fractions, surface areas, and specific growth rates is investigated. In addition, X-ray photoelectron spectroscopy was used to determine the chemical state of iron species throughout the flame. The analysis revealed …
Incorporating Reservoir Characteristics For Automatic History Matching., Keith J. Halford
Incorporating Reservoir Characteristics For Automatic History Matching., Keith J. Halford
LSU Historical Dissertations and Theses
Automatic history matching is refined in this work by expanding the objective function and incorporating reservoir characteristics in the process of parameter selection. Iso-value contours are used to incorporate reservoir characteristics within history-matching parameters. These improvements are implemented in an automatic history-matching algorithm, OPTIM, that is coupled with BOAST II. Case histories of both hypothetical and real reservoirs demonstrated the effectiveness of incorporating reservoir characteristics in automatic history-matching parameters.
Fatigue Effects On Manual Lifting Acceleration., Youngjoun Kim
Fatigue Effects On Manual Lifting Acceleration., Youngjoun Kim
LSU Historical Dissertations and Theses
The objective of this research was to study the effects of fatigue on lifting acceleration and posture caused by repetitive manual lifting. Electromyogram, oxygen consumption and heart rate were used as indices of a subject's physiological fatigue. Data were collected for a period of two hours of continuous lifting, at a rate of 4 lifts per minute using the free-style posture. A box of fixed dimensions (30cm x 30cm x 20cm) and fixed weight (15.9 Kg) was used as load. It was found that the average load acceleration increased with work duration. Peak acceleration was found to be maximum in …
Nonlinear Inelastic Finite Element Analysis Of Reinforced Concrete Structures With Emphasis On Shear And Torsion. (Volumes I And Ii)., Ananth Ramaswamy
Nonlinear Inelastic Finite Element Analysis Of Reinforced Concrete Structures With Emphasis On Shear And Torsion. (Volumes I And Ii)., Ananth Ramaswamy
LSU Historical Dissertations and Theses
In this study a post-cracking formulation for the analysis of reinforced concrete structures has been proposed. The secant stiffness formulation considers the following nonlinearities: effects of tension-stiffening in concrete along the reinforcing direction(s), aggregate interlock model with variable shear based on crack confining stresses, and reduction of concrete compressive strength and stiffness after cracking as a function of stresses or strains. The cracking model is capable of simulating the effects of multiple non-orthogonal cracks at a point. This total stiffness formulation treats concrete unloading and reloading along a secant path and is capable of simulating the post-peak strain softening response. …
Development Of A Technique To Determine The Temperature Dependence Of The Refractive Index Of Carbonaceous Particulates., Barry James Stagg
Development Of A Technique To Determine The Temperature Dependence Of The Refractive Index Of Carbonaceous Particulates., Barry James Stagg
LSU Historical Dissertations and Theses
The complex refractive index of carbonaceous particulates is an important quantity in many areas of combustion research and practical applications. This property characterizes the radiative transport in luminous flames and plays a key role in the interpretation of conventional light scattering measurements. The purpose of the present study is to develop a technique which will allow the experimental determination of the temperature dependence of the refractive indices of carbonaceous materials and provide a predictive model for the variation of the indices. A high temperature ellipsometer system is developed that allows measurements of the intensity of polarized light reflected from the …
Dynamic Response Of An Electron Storage Ring Magnet., Shahriar Jahanian
Dynamic Response Of An Electron Storage Ring Magnet., Shahriar Jahanian
LSU Historical Dissertations and Theses
A combined experimental and numerical methodology was employed to investigate the dynamic response of the electron storage ring dipole magnets located in the Center for Advanced Microstructural Devices (CAMD) at Louisiana State University (L.S.U.). The magnet are highly anisotropic and can not be analysed for dynamic response without knowledge of the effective elastic properties. The theory of wave propagation in conjunction with finite element analysis was used to determine the variation of the effective modulus of elasticity magnets in question. The structure of the magnet was modeled with NASTRAN. A theoretical analysis was performede that supported the experimental variation of …
A Study Of Selected Phenomena Observed During Rotary Kiln Incineration., Christopher Brian Leger
A Study Of Selected Phenomena Observed During Rotary Kiln Incineration., Christopher Brian Leger
LSU Historical Dissertations and Theses
A comprehensive research program is underway at LSU with the ultimate goal of improved understanding and predictive capability for the performance of rotary kiln incinerators. In an extensive experimental study, packs containing toluene-contaminated clay sorbent are batch-fed into the field-scale rotary kiln incinerator of the Louisiana Division of Dow Chemical USA. Water cooled probes are used to obtain continuously gas temperatures and species concentrations within the kiln and afterburner, and existing facility instruments are also monitored. The kiln rotation rate is varied and turbulence air (air injected into the kiln to improve mixing) is added or turned off. Conditions at …
Nonlinear Stochastic Modeling Of Daily Temperature Series., Glenn Poloyapoy Fernandez
Nonlinear Stochastic Modeling Of Daily Temperature Series., Glenn Poloyapoy Fernandez
LSU Historical Dissertations and Theses
The major objective of this research is to develop daily time series models for maximum and minimum temperature series. A generalized modeling methodology is presented. Stochastic modeling was accomplished by analyzing the structural characteristics of the temperature series. Analyses included assessment for time reversibility, linearity, structural dependence and distributional properties of the weakly stationary series obtained by parametric standardization of the observed series. Based on the results of the structural characterization of the series and the results of the model class identification using a 'state-dependent model' formulation, a bilinear model class was identified as appropriate for the temperature series. Various …
Modification Of The Drainmod-Creams Model To Incorporate A Nutrient Submodel., Abdul Razak Bin Saleh
Modification Of The Drainmod-Creams Model To Incorporate A Nutrient Submodel., Abdul Razak Bin Saleh
LSU Historical Dissertations and Theses
DRAINMOD-CREAMS model was used to simulate surface runoff and sediment loss from subsurface drained plot and non-subsurface drained plot in southern Louisiana. Seven years (1981-1987) of recorded data were used in this study. In general, the performance of the model in simulating surface runoff and sediment loss from subsurface drained plot is satisfactory. However, the DRAINMOD-CREAMS model did not simulate surface runoff and sediment loss accurately from non-subsurface drained plot. The CREAMS nutrient submodel was also tested on both plots. The CREAMS model seriously overestimates the nitrogen loss from non-subsurface drained plot. The sensitivity of the DRAINMOD-CREAMS model on erodibility …
Demonstration Of A Control Strategy For Sustained Algal Growth At A Full-Scale Level Under Computer-Automated, Continuous Culture Conditions., Kelly Ann Rusch
Demonstration Of A Control Strategy For Sustained Algal Growth At A Full-Scale Level Under Computer-Automated, Continuous Culture Conditions., Kelly Ann Rusch
LSU Historical Dissertations and Theses
A computerized algal turbidostat was designed and constructed for use in aquaculture facilities requiring a continuous feed source. Continuous cultures, maintained in the exponential growth phase by the continual introduction of fresh media, exhibit a steadystate nature easily adaptable to computer automation and optimization processes. These characteristics, in contrast to batch culture methods, result in both reduced land and labor requirements; an important consideration for commercial applications wherein algal production occupies as much as 40 percent of a facility in both space and cost. The turbidostat system consisted of two 0.6 m$\sp3$ growth chambers supported by a central monitoring block …
Modeling Three-Dimensional Groundwater Flow And Solute Transport By The Finite Element Method With Parameter Estimation., Fang Xin Yu
LSU Historical Dissertations and Theses
A general, systematic and improved numerical formulation for the three-dimensional (3-D) groundwater flow and solute transport problems was derived, using the finite element method. In the numerical formulation, a hidden mistake, which has appeared in many textbooks and journal papers dealing with the advective term of the general 3-D solute transport equation, was found and corrected. Some simpler and practical expressions for the leaky boundary condition, surface flux condition, and sources and sinks were proposed. To improve the conventional formulation for the time derivatives, a combination of the Galerkin method and the collocation method was developed. A more accurate scheme …
The Structure Of Cementitious Materials Produced By Alkali Activation Of Calcium Aluminosilicate Glasses., Paul Joseph Schilling
The Structure Of Cementitious Materials Produced By Alkali Activation Of Calcium Aluminosilicate Glasses., Paul Joseph Schilling
LSU Historical Dissertations and Theses
A comprehensive investigation, using scanning electron microscopy, energy dispersive x-ray analysis, x-ray diffraction, and $\sp{29}$Si and $\sp{27}$Al magic angle spinning nuclear magnetic resonance spectroscopy, was conducted on the NaOH-activated blastfurnace slag system. Integration of the results from these techniques accommodated characterization of the unreacted glass, identification of the crystalline hydration products, and presentation of a proposed structure for the C-S-H phase. Crystalline hydration products identified by x-ray diffraction were CSH(I) and (C,M)$\sb4$AH$\sb{\rm x}$, and the proposed structure for the C-S-H phase consists mainly of imperfect layers of tobermorite. The structures of the hydrated phases were found to be closely related …
Interactive Graphics-Based Musculotendon Modeling For Reconstructive Surgery Of The Hand., Inmo Yoon
Interactive Graphics-Based Musculotendon Modeling For Reconstructive Surgery Of The Hand., Inmo Yoon
LSU Historical Dissertations and Theses
This research has been directed at studying and developing a prototype research and clinical Computer Aided Design (CAD) tool to be used for planning tendon paths in hand reconstructive surgery. Of equal importance is the goal of having an educational tool for teaching hand biomechanics to students of this specialty. The application of CAD to rehabilitative surgery of the hand is a new field of endeavor. There are currently no existing commercial products designed to assist the orthopedic surgeon in planning these complex procedures. Additionally, orthopedic surgeons are not trained in mechanics, kinematics, math modeling, or the use of computers. …
Plasticity-Damage Bounding Surface Model For Concrete Under Cyclic-Multiaxial Loading., Taher Mowafaq Abu-Lebdeh
Plasticity-Damage Bounding Surface Model For Concrete Under Cyclic-Multiaxial Loading., Taher Mowafaq Abu-Lebdeh
LSU Historical Dissertations and Theses
Concrete exhibits a significant strain-softening behavior beyond the peak stress, and moreover, the mechanism of inelastic deformation in concrete consists of both plastic slip and microcracking. Hence, a combined plasticity and damage mechanics model is proposed for modeling concrete behavior under both multiaxial monotonic and cyclic loadings. The model adopts a bounding surface concept for both plasticity and damage. The introduced plasticity bounding surface is a function of the maximum compressive strain experience by the material, while the damage bounding surface is a function of the accumulated damage parameter. By this definition, both surfaces shrink in size in the stress …
Phase Equilibria Of Supercritical Carbon Dioxide And Hydrocarbon Mixtures., Hyo-Guk Lee
Phase Equilibria Of Supercritical Carbon Dioxide And Hydrocarbon Mixtures., Hyo-Guk Lee
LSU Historical Dissertations and Theses
The phase equilibria of supercritical carbon dioxide and hydrocarbon mixtures were studied. Correlation techniques for vapor-liquid and solid-fluid equilibria were studied for binary CO$\sb2$ and hydrocarbon mixtures using existing experimental data. Experimental investigation and correlation of the experimental data were carried out for solid-liquid equilibria of light and heavy hydrocarbon mixtures, and CO$\sb2,$ light and heavy hydrocarbon mixtures. A new technique of vapor-liquid equilibrium calculation by the activity coefficient method was developed and applied to binary CO$\sb2$ and hydrocarbon mixtures. The extrapolated vapor pressure of CO$\sb2$ was used for calculation of the fugacity of pure hypothetical liquid CO$\sb2$ and for …