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Articles 1 - 30 of 38
Full-Text Articles in Engineering
Stability, Transport And Applications Of Polyaphrons In Porous Media, Le Yan
Stability, Transport And Applications Of Polyaphrons In Porous Media, Le Yan
LSU Doctoral Dissertations
Polyaphrons are a kind of macroemulsion. The most distinctive feature of polyaphrons is their high stability. On the other hand, certain polyaphrons can be effectively destabilized by multivalent ions. In this dissertation, we devise a novel procedure that utilizes the fact that polyaphrons can be destabilized by certain ions to deliver light chemicals to lower the density of dense non-aqueous phase liquid (DNAPL) contaminants in situ. We first investigate how the stability of diluted polyaphrons is affected by the properties of the continuous phase. We find that polyaphrons can be destabilized by a low concentration of Al3+ or Ca2+ in …
Multiphase Mechanisms And Fluid Dynamics In Gas Injection Enhanced Oil Recovery Processes, Madhav M. Kulkarni
Multiphase Mechanisms And Fluid Dynamics In Gas Injection Enhanced Oil Recovery Processes, Madhav M. Kulkarni
LSU Doctoral Dissertations
Currently, the Water-Alternating-Gas (WAG) process is the most widely practiced horizontal mode gas injection process in the industry. Although this process is conceptually sound, it has resulted in low (5 – 10%) oil field recoveries. Conversely, the gravity stable mode of gas injection has carved its niche as one of the most effective methods of gas injection EOR in the dipping reservoirs and pinnacle reefs. The Gas Assisted Gravity Drainage (GAGD) process is therefore being developed at LSU to extend these highly successful gravity stable applications to horizontal type reservoirs. The dissertation attempts to address six key questions: (i) do …
Transport And Kinetics Of Aromatic Hydrocarbons Into Micron-Sized Liquid Droplets: With Applications To Atmospheric Chemistry, Suresh Raja
LSU Doctoral Dissertations
In the natural process of wet deposition, gas-water interfaces play an important role in the transport of chemical contaminants in the atmosphere via fog, rain and cloud drops. Evidences from several other works point out deviations in gas-liquid partitioning as predicted by Henry’s law. Uptake and mass transfer of benzene, naphthalene, and phenanthrene was chosen to study in a falling droplet train apparatus. Higher droplet-to-vapor partition constant (KDV) was noted for diameters less than 200ìm and was attributed to surface adsorption and accumulation. Mass transfer of phenanthrene was dependent on gas-phase diffusion and mass accommodation at the interface, while the …
Cementitious Permeable Pavement As A Passive Unit Operation And Process For Stormwater Quality And Quantity Control, Xuheng Kuang
Cementitious Permeable Pavement As A Passive Unit Operation And Process For Stormwater Quality And Quantity Control, Xuheng Kuang
LSU Doctoral Dissertations
With respect to the problems caused by impervious pavements, cementitous permeable pavement (CPP) functions as a passive unit operation and process for stormwater quality and quantity control through infiltration, evaporation, filtration, absorption and reaction mechanisms. CPP pore characteristics were examined through pore connectivity analysis using X-Ray Tomography (XRT). Image resolution influence on image analysis results was evaluated. Relationships between parameters of pore characteristics were evaluated. Factors that significantly influence fluid flow in CPP media include effective porosity, pore connectivity and pore size distribution. A modified Kozeny-Carman model in which effective porosity, specific surface area based on effective pores (SSA)pe, and …
Computational Model For Elasto-Plastic And Damage Analysis Of Plates And Shells, Pawel Benedykt Woelke
Computational Model For Elasto-Plastic And Damage Analysis Of Plates And Shells, Pawel Benedykt Woelke
LSU Doctoral Dissertations
Shells and plates are very important for various engineering applications. Analysis and design of these structures is therefore continuously of interest to the scientific and engineering community. Accurate and conservative assessments of the maximum load carried by the structure, as well as the equilibrium path in both elastic and inelastic range are of paramount importance. Elastic behaviour of shells has been very closely investigated, mostly by means of the finite element method. Inelastic analysis on the other hand, especially accounting for damage effects, has received much less attention from the researchers. A computational model for finite element, elasto-plastic and damage …
Improvements In Groundwater Flow Modeling Through The Integration Of Resistivity Logs And Hydraulic Conductivity And The Use Of Variogram Uncertainty, Asheka Rahman
LSU Doctoral Dissertations
This study developed a coregionalized model to estimate hydraulic conductivity using spatial cross correlation between hydraulic conductivity and borehole geophysical data (a transform of the formation factor). An experimental pseudocross variogram is used instead of a cross variogram because data are not collocated. Experimental variogram uncertainty is investigated using confidence intervals for the experimental variogram calculated assuming variogram sills are lognormally distributed. These intervals are used for sensitivity modeling using kriging, cokriging, simulation and cosimulation. The hydraulic conductivity fields generated by kriging, cokriging, simulation, and cosimulation are then used in a high-resolution groundwater model created using telescopic mesh refinement (TMR) …
Thermo And Kinetic Studies On The Sorption And Desorption Of Hydrophobic Organic Contaminants In Sediments, Yunzhou Chai
Thermo And Kinetic Studies On The Sorption And Desorption Of Hydrophobic Organic Contaminants In Sediments, Yunzhou Chai
LSU Doctoral Dissertations
This study investigated the correlation of desorption resistance of hydrophobic organic contaminants (HOCs) in sediment and the heterogeneity of sediment organic matter (SOM). The amorphous and condensed phase organic carbon contents were defined by the method of Gustafsson et al. (1997) using thermal oxidation of sediment under 375°C. The desorption-resistant fraction of contaminants in sediments was operationally defined as the fraction that could not be removed by the adsorbent XAD-2. The correlation of the desorption-resistant fraction with sediment organic carbon characteristics was evaluated for both laboratory-inoculated and field-contaminated sediments. No strong correlation between the desorption resistant fraction in laboratory-inoculated sediments …
A Project Improvement System For Effective Management Of Construction Projects, Shahriyar Mojahed
A Project Improvement System For Effective Management Of Construction Projects, Shahriyar Mojahed
LSU Doctoral Dissertations
The concept of construction productivity began in the early 20th century with a series of time and motion studies to improve bricklaying operations. A substantial number of subsequent studies focused on repetitive tasks and automation of the manufacturing operations and subsequently benefited manufacturing more than the construction industry. There has been a lack of studies for productivity improvement in the construction industry. Building upon the available body of knowledge as it related to productivity of manufacturing and construction industries, this study focused on developing a project improvement system for effective management of construction projects. Development of the system included a …
Chemical Vapor Deposition Of Thin Films For Ulsi Interconnect Metallization, Lidong Wang
Chemical Vapor Deposition Of Thin Films For Ulsi Interconnect Metallization, Lidong Wang
LSU Doctoral Dissertations
We have studied the kinetics of copper chemical vapor deposition (CVD) for interconnect metallization using solution delivery of Cu(hfac)2 (Cu(II) hexafluoroacetyl-acetonate) dissolved in isopropanol. We observe a growth rate of 17.7 „b 1.5 nm/min at reference conditions of 300„aC substrate temperature, 0.025 Torr Cu(hfac)2 partial pressure, 1.6 Torr isopropanol (reducing agent), and 80 Torr H2 (carrier gas). The film resistivity approaches the bulk value of copper for film thickness greater than 100 nm. Reaction order experiments show first-order kinetics with respect to Cu(hfac)2 partial pressure and zero-order with respect to isopropanol. A series reaction mechanism including three kinetically significant steps …
Optimal Operating Strategy For Wells With Downhole Water Sink Completions To Control Water Production And Improve Performance, Ozan Arslan
LSU Doctoral Dissertations
Downhole water sink (DWS) technology is an alternative to conventional limited-entry completions to control water production in wells with bottom water drive. DWS wells comprise two completions: the bottom completion produces water and keeps the top completion open to oil inflow. The system performance depends on careful manipulation of the top and bottom rates to maximize oil productivity and produce oil-free water from the bottom completion. Conventional nodal analysis cannot provide a solution for DWS wells because the critical rates for water coning change with water drainage rate. A reservoir simulator is used to model two-phase flow to the dual …
Modeling The Flow Of Non-Newtonian Fluids In Packed Beds At The Pore Scale, Matthew Balhoff
Modeling The Flow Of Non-Newtonian Fluids In Packed Beds At The Pore Scale, Matthew Balhoff
LSU Doctoral Dissertations
Flow and transport in porous media are important in many science and engineering applications such as composite materials, subsurface water contamination, packed-bed reactors, and enhanced oil recovery. The general approach to modeling such processes is at the continuum scale. Semi-empirical expressions, such as Darcy's law, are substituted for velocity in the continuity equation, which is then coupled with a momentum, mass, and energy balance. While a continuum approach is acceptable in some cases, additional modeling is required for certain non-linear flows, such as multi-phase flows, inertial flows, non-Newtonian flows, and reactive flows. Pore-scale modeling is a first-principles approach to modeling …
Multivariate Hydrological Frequency Analysis And Risk Mapping, Lan Zhang
Multivariate Hydrological Frequency Analysis And Risk Mapping, Lan Zhang
LSU Doctoral Dissertations
In hydrological frequency analysis, it is difficult to apply standard statistical methods to derive multivariate probability distributions of the characteristics of hydrologic or hydraulic variables except under the following restrictive assumptions: (1) variables are assumed independent, (2) variables are assumed to have the same marginal distributions, and (3) variables are assumed to follow or are transformed to normal distribution. Relaxing these assumptions when deriving multivariate distributions of the characteristics of correlated hydrologic and hydraulic variables. The copula methodology is applied to perform multivariate frequency analysis of rainfall, flood, low-flow, water quality, and channel flow, using data from the Amite river …
Pah And Pcb Distribution In Sediment Fractions And Sorptive Phases, Trudy J. Estes
Pah And Pcb Distribution In Sediment Fractions And Sorptive Phases, Trudy J. Estes
LSU Doctoral Dissertations
Contaminant distribution is integral to environmental evaluations of contaminated sediment on every level. The technical and economic feasibility of treatment or beneficial use is a function of the accessibility or separability of the contaminants within the sediment. The magnitude of release to the environment during dredging and disposal is dependent upon the partitioning behavior of the contaminants. Yet, little attention has been paid to contaminant distribution in the fine sediment fractions. Further, conventional distribution coefficients provide little information regarding the relative contaminant loading of each of the sorptive phases. Bioavailability of contaminants in oil and grease, soot and organic carbon, …
Long Term Pressure Behavior In Turbidite Reservoirs, Feng Wang
Long Term Pressure Behavior In Turbidite Reservoirs, Feng Wang
LSU Doctoral Dissertations
In this study, we investigated several possible mechanisms that would give rise to the anomalous pressure behavior (early concave-up on Horner plot or upward drift on the derivative curve of the log-log plot and asymmetry between the pressure drawdown and buildup behavior) sometimes encountered in the turbidite reservoirs in GOM primarily using numerical simulation and 2-level experimental designs. We ascertained the most influential parameters to the pressure behavior and identified that multilayer commingled system and the leaky compartment model are the most probable mechanisms to cause the anomalous behavior due to layer or zone property contrast to a certain degree. …
Nonlinear Control And Its Application To Active Tilting-Pad Bearings, Zhijun Cai
Nonlinear Control And Its Application To Active Tilting-Pad Bearings, Zhijun Cai
LSU Doctoral Dissertations
The drawbacks of active magnetic bearings are arousing interest in the adaptation of mechanical bearings for active use. A promising mechanical bearing candidate for active operation is the tilting-pad bearing. In this research, we introduce an active tilting-pad bearing with linear actuators that translate each pad. The use of feedback in determining the actuator forces allows for the automatic, continuous adjustment of the pad position during the machine operation. In this work, we develop the dynamic model of the active bearing system such that the actuator forces are the control inputs. The hydrodynamic force is modeled as a spring/damper-like force …
Development Of High Performance Hybrid Syntactic Foams: Structure And Material Property Characterization, Rahul R. Maharsia
Development Of High Performance Hybrid Syntactic Foams: Structure And Material Property Characterization, Rahul R. Maharsia
LSU Doctoral Dissertations
Syntactic foams are light weight particulate composites that use hollow particles (microballoons) as reinforcement in a polymer resin matrix. High strength microballoons provide closed cell porosity which helps in reducing weight of the material. Due to their wide range of possible applications such as in aerospace and marine structures, it is desirable to modify the physical and mechanical properties of syntactic foams as per the requirements of an application. Various filler materials can be used to modify the foam microstructure to attain these desired properties. Compression tests have revealed that high density syntactic foams demonstrate poor damage tolerance and low …
Speciation, Equilibria And Kinetics For Rainfall-Runoff Metals In Adsorptive-Filtration Unit Operations And Processes, Tianpeng Guo
Speciation, Equilibria And Kinetics For Rainfall-Runoff Metals In Adsorptive-Filtration Unit Operations And Processes, Tianpeng Guo
LSU Doctoral Dissertations
Populations transferred by rainfall runoff can have many adverse effects livings and people. Treatment of rainfall-runoff continues to pose unique challenges due to the unsteady nature of processes including mobilization, partitioning and transport of heavy metals as well as other constituent loads. BMPs that incorporate heavy metal removal are generating more attention as the nature of stormwater is better understood. This dissertation focused on metal partitioning and speciation in rainfall-runoff through the in-situ Partial Exfiltration Reactor (PER) and exposed to various redox circumstances, and metal removal by sorptive engineered manganese oxides coated media. Adsorption capacity of three manganese oxides coated …
Biofiltration For Treatment Of Gas-Phase Voc Mixtures, Bing Qi
Biofiltration For Treatment Of Gas-Phase Voc Mixtures, Bing Qi
LSU Doctoral Dissertations
Biological processes are increasingly used for treatment of air streams contaminated by biodegradable volatile organic compounds (VOCs). The research described in this dissertation involves systematic investigation of various facets of applying biological processes dominated by fungi to remove mixtures of VOCs representative of emissions from paint application and manufacturing. Screening studies were first conducted to assess the ability of multiple fungal species to degrade various industrially important VOCs. In the following phases of the research, studies were conducted to evaluate performance of laboratory-scale bioreactors inoculated with fungi for treatment of mixtures of VOCs representative of emissions from paint spray booths …
Shaly Sand Interpretation Using Cec-Dependent Petrophysical Parameters, Fnu Kurniawan
Shaly Sand Interpretation Using Cec-Dependent Petrophysical Parameters, Fnu Kurniawan
LSU Doctoral Dissertations
This research explores the characterization of petrophysical parameters such as cementation exponent, saturation exponent and effective porosity as a function of cations exchange capacity (CEC), and its impact on shaly sand interpretation. Experimental and field data were used in the study. The latest LSU model for shaly sand interpretation uses of two cementation exponents, mf and mc, to represent the tortuosity of electric current path in free water and clay bound water, respectively. Experimental measurements on three types of rock, clean sand, shaly sand and pure shale using different brine salinity, were conducted to validate the use of these two …
Experimental Quantification And Dem Simulation Of Micro-Macro Behaviors Of Granular Materials Using X-Ray Tomography Imaging, Yanrong Fu
LSU Doctoral Dissertations
A non-invasive experimental method and a clustering DEM model were developed in this study to investigate micro-macro behaviors of real granular materials with irregular particle shape configurations. The investigated behaviors include global deformations, failure strengths and residual strengths, stress and strain distributions, local coordination number, local void ratio, particle kinematics, and fabric orientation distributions. The experimental method includes an approach to automatically identify and recognize multiple particles using x-ray computed tomography imaging (XCT) and an enhanced approach to digitally represent microstructures of granular materials. The digitally represented microstructure can be directly employed for numerical simulation setup. A compression test and …
On The Stability Of Rotor Bearing Systems Based On Hopf Bifurcation Theory, Jianke Wang
On The Stability Of Rotor Bearing Systems Based On Hopf Bifurcation Theory, Jianke Wang
LSU Doctoral Dissertations
This research is aimed to establish instability criteria for a rotor-bearing system which consists of a rotor supported by two fluid-film journal bearings. The static and dynamic characteristics of rotor-bearing systems with consideration of turbulent effects are evaluated by applying the Hopf bifurcation theory (HBT) to the equations of motion. A method is developed for predicting the stability envelope of rotor-bearing systems using HBT. Results are compared with published literature obtained using a trial-and-error method. A method based on HBT is presented for predicting the occurrence of a hysteresis phenomenon, which is observed in experimental results dealing with the instability …
Structural Integrity And Fatigue Crack Propagation Life Assessment Of Welded And Weld-Repaired Structures, Mohammad Shah Alam
Structural Integrity And Fatigue Crack Propagation Life Assessment Of Welded And Weld-Repaired Structures, Mohammad Shah Alam
LSU Doctoral Dissertations
Structural integrity is the science and technology of the margin between safety and disaster. Proper evaluation of the structural integrity and fatigue life of any structure (aircraft, ship, railways, bridges, gas and oil transmission pipelines, etc.) is important to ensure the public safety, environmental protection, and economical consideration. Catastrophic failure of any structure can be avoided if structural integrity is assessed and necessary precaution is taken appropriately. Structural integrity includes tasks in many areas, such as structural analysis, failure analysis, nondestructive testing, corrosion, fatigue and creep analysis, metallurgy and materials, fracture mechanics, fatigue life assessment, welding metallurgy, development of repairing …
Fabrication Of High Aspect Ratio Vibrating Cylinder Microgyroscope Structures By Use Of The Liga Process, Yohannes Mamo Desta
Fabrication Of High Aspect Ratio Vibrating Cylinder Microgyroscope Structures By Use Of The Liga Process, Yohannes Mamo Desta
LSU Doctoral Dissertations
Inertial grade microgyroscopes are of great importance to improve and augment inertial navigation systems based on GPS for industrial, automotive, and military applications. The efforts by various research groups worldwide to develop inertial grade microgyroscopes have not been successful to date. In 1994, the Department of Mechanical Engineering at Louisiana State University and SatCon Technology Corporation (Boston, Massachusetts) proposed a series of shock tolerant micromachined vibrating cylinder rate gyroscopes with aspect ratios of up to 250:1 to meet the needs of inertial navigation systems based on existing conventional vibrating cylinder gyroscopes. Each microgyroscope consisted of a tall thin shell metallic …
Interference Suppression And Parameter Estimation In Wireless Communication Systems Over Time-Varing Multipath Fading Channels, Jianqiang He
Interference Suppression And Parameter Estimation In Wireless Communication Systems Over Time-Varing Multipath Fading Channels, Jianqiang He
LSU Doctoral Dissertations
This dissertation focuses on providing solutions to two of the most important problems in wireless communication systems design, namely, 1) the interference suppression, and 2) the channel parameter estimation in wireless communication systems over time-varying multipath fading channels. We first study the interference suppression problem in various communication systems under a unified multirate transmultiplexer model. A state-space approach that achieves the optimal realizable equalization (suppression of inter-symbol interference) is proposed, where the Kalman filter is applied to obtain the minimum mean squared error estimate of the transmitted symbols. The properties of the optimal realizable equalizer are analyzed. Its relations with …
Speciation, Equilibrium Distribution And Kinetics Of Rainfall-Runoff Phosphorus In Adsorptive-Filtration Unit Operations And Processes, Jia Ma
LSU Doctoral Dissertations
This study examined the influence of hydrology on rainfall runoff phosphorus partitioning between aqueous and particulate-bound phase, and dissolved phosphorus speciation at the upper end of a Cementitious Porous Pavement (CPP) small urban watershed. This study also investigated particulate bound phosphorus temporal distribution during storm event and phosphorus equilibrium distribution on a wide gradation of solids captured by hydrodynamic separator after the storm completed. Results indicate that EMC of urban rainfall runoff phosphorus exceeds EPA water quality criteria, with majority of particulate-bound phosphorus while rainfall by itself contains non-comparable low concentration of phosphorus. Dissolved phosphorus was mainly H2PO4- and HPO4-2 …
Geostatistical Integration Of Geophysical, Well Bore And Outcrop Data For Flow Modeling Of A Deltaic Reservoir Analogue, Hong Tang
LSU Doctoral Dissertations
Significant world oil and gas reserves occur in deltaic reservoirs. Characterization of deltaic reservoirs requires understanding sedimentary and diagenetic heterogeneity at the submeter scale in three dimensions. However, deltaic facies architecture is complex and poorly understood. Moreover, precipitation of extensive calcite cement during diagenesis can modify the depositional permeability of sandstone reservoir and affect fluid flow. Heterogeneity contributes to trapping a significant portion of mobile oil in deltaic reservoirs analogous of Cretaceous Frontier Formation, Powder River Basin, Wyoming. This dissertation focuses on 3D characterization of an ancient deltaic lobe. The Turonian Wall Creek Member in central Wyoming has been selected …
Effects Of Strong Surface Energy Anisotropy On Stationary And Migrating Grain-Boundary Grooves, Donghong Min
Effects Of Strong Surface Energy Anisotropy On Stationary And Migrating Grain-Boundary Grooves, Donghong Min
LSU Doctoral Dissertations
Grain-boundary migration controls grain growth and is important in materials processing and synthesis. When a grain boundary ends at a free surface, a groove will develop at the tip to reduce the combined surface and grain-boundary energies. This groove may hinder the grain boundary movement and its effect needs to be understood. Previous studies have solved the groove profile for stationary or migrating grain boundaries by assuming small groove slopes with isotropic surface free energy. This work extends the analysis to finite slopes with isotropic or anisotropic surface free energy.
We first study migrating grain-boundary grooves with isotropic surface energy …
Power And Memory Optimization Techniques In Embedded Systems Design, Atef Khalil Allam
Power And Memory Optimization Techniques In Embedded Systems Design, Atef Khalil Allam
LSU Doctoral Dissertations
Embedded systems incur tight constraints on power consumption and memory (which impacts size) in addition to other constraints such as weight and cost. This dissertation addresses two key factors in embedded system design, namely minimization of power consumption and memory requirement. The first part of this dissertation considers the problem of optimizing power consumption (peak power as well as average power) in high-level synthesis (HLS). The second part deals with memory usage optimization mainly targeting a restricted class of computations expressed as loops accessing large data arrays that arises in scientific computing such as the coupled cluster and configuration interaction …
Photocatalysis In A Novel Semiconducting Optical Fiber Monolithic Reactor For Wastewater Treatment, Hongfei Lin
Photocatalysis In A Novel Semiconducting Optical Fiber Monolithic Reactor For Wastewater Treatment, Hongfei Lin
LSU Doctoral Dissertations
The development of photocatalytic reactors is essential for the successful exploitation of heterogeneous photocatalysis on semiconductor particles, which has been shown to be an effective means of removing organic pollutants from wastewater streams. In this dissertation, a novel photocatalytic optical fiber monolith reactor (OFMR), which employed a ceramic multi-channel monolith as a support for TiO2 and quartz fibers inserted inside the monolithic channels as both a light-transmitting conductor and a support for TiO2, was developed for wastewater treatment by investigating the photocatalytic degradation of o-dichlorobenzene (DCB) and phenanthrene (PHE). This configuration provides a high surface area for catalyst coating per …
Physically Based Multiscale-Viscoplastic Model For Metals And Steel Alloys: Theory And Computation, Farid H. Abed
Physically Based Multiscale-Viscoplastic Model For Metals And Steel Alloys: Theory And Computation, Farid H. Abed
LSU Doctoral Dissertations
The main requirement of large deformation problems such as high-speed machining, impact, and various primarily metal forming, is to develop constitutive relations which are widely applicable and capable of accounting for complex paths of deformation. Achieving such desirable goals for material like metals and steel alloys involves a comprehensive study of their microstructures and experimental observations under different loading conditions. In general, metal structures display a strong rate- and temperature-dependence when deformed non-uniformly into the inelastic range. This effect has important implications for an increasing number of applications in structural and engineering mechanics. The mechanical behavior of these applications cannot …