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Articles 2251 - 2280 of 2820
Full-Text Articles in Engineering
Flow And Distribution Of Water In Fractional Wettability Unsaturated Porous Media, Zaydoun Turkey Abusalem
Flow And Distribution Of Water In Fractional Wettability Unsaturated Porous Media, Zaydoun Turkey Abusalem
LSU Doctoral Dissertations
In recent years, interest in fluid flow and transport in the unsaturated zone has gained more attention, due to growing concerns that the quality of the subsurface environment is adversely affected by agricultural, industrial, and municipal activities. The wettability properties (e.g., water repellency) of soil in the unsaturated zone play an important role in determining fluid movement and ultimate distributions. A number of studies have shown that preferential flow and spatially variable moisture content is likely to occur in water repellant soils. Development of appropriate constitutive relations for numerical modeling becomes even more difficult in systems that contain water repellant …
Oil Bypassing By Water Invasion To Wells: Mechanisms And Remediation, Juan Carlos Hernandez
Oil Bypassing By Water Invasion To Wells: Mechanisms And Remediation, Juan Carlos Hernandez
LSU Doctoral Dissertations
This study addresses oil bypassing caused by water invasion to wells in edge and bottom water-drive oil reservoirs – a significant problem worldwide. It is shown that the amount of by-passed (not recovered) oil is significant and could be predicted analytically and reduced by modifying well’s completion. A large statistical sample from the population of possible reservoir-well systems with edge and bottom-water has been created theoretically using several databases of actual reservoirs properties worldwide. Dimensional analysis allowed converting reservoir properties distributions into dimensionless group distributions. Then, the amount of by-passed oil was correlated with the dimensionless groups using designed experiments …
Mechanistic Modeling Of An Underbalanced Drilling Operation Utilizing Supercritical Carbon Dioxide, Faisal Abdullah Aladwani
Mechanistic Modeling Of An Underbalanced Drilling Operation Utilizing Supercritical Carbon Dioxide, Faisal Abdullah Aladwani
LSU Doctoral Dissertations
Mechanistic modeling of an underbalanced drilling operation using carbon dioxide has been developed in this research. The use of carbon dioxide in an underbalanced drilling operation eliminates some of the operational difficulties that arises with gaseous drilling fluids, such as generating enough torque to run a downhole motor. The unique properties of CO2, both inside the drill pipe and in the annulus are shown in terms of optimizing the drilling operation by achieving a low bottomhole pressure window. Typically CO2 becomes supercritical inside the drill pipe at this high density; it will generate enough torque to run …
Production Data Analysis Of Shale Gas Reservoirs, Adam Michael Lewis
Production Data Analysis Of Shale Gas Reservoirs, Adam Michael Lewis
LSU Master's Theses
Hydrocarbon resources from unconventional shale gas reservoirs are becoming very important in the United States in recent years. Understanding the effects of adsorption on production data analysis will increase the effectiveness of reservoir management in these challenging environments. The use of an adjusted system compressibility proposed by Bumb and McKee (1988) is critical in this process. It allows for dimensional and dimensionless type curves to be corrected at a reasonably fundamental level, and it breaks the effects of adsorption into something that is relatively simple to understand. This coupled with a new form of material balance time that was originally …
Biodegradation And Characterization Of A Bio-Based Polyester, Benjamin Edward Stevens
Biodegradation And Characterization Of A Bio-Based Polyester, Benjamin Edward Stevens
LSU Master's Theses
Anaerobic biodegradation in sewage sludge and aerobic biodegradation in compost of polyhydroxybutyrate (PHB) were investigated to determine degradation kinetics and identify changes in polymer properties. To determine the impact of a natural plasticizer on biodegradation, tributyl citrate (TBC) was blended with some test specimens. For comparison to another bioplastic, polylactic acid (PLA) was biodegraded in the anaerobic study. Evolved gaseous carbon was measured to assess biodegradability according to ASTM standards D5210 and D5338. Mass loss experiments were performed to facilitate determination of degradation kinetics. Melt-pressed plates of the bioplastic with five different initial mass-to-surface-area ratios (plate thicknesses of 0.24, 0.5, …
An Investigation Of The Frictional And Thermal Behavior Of Oscillatory Sliding Line Contacts, Mongi Mansouri
An Investigation Of The Frictional And Thermal Behavior Of Oscillatory Sliding Line Contacts, Mongi Mansouri
LSU Doctoral Dissertations
This research deals with an experimental and numerical investigation of the frictional and thermal behavior of pin-bushing pairs, operating at reciprocating sliding motion or under heavy loads. Large interfacial temperatures developed due to frictional heating can cause failure. Therefore, numerical prediction and analysis of the surface temperature under various operating conditions are important. Laboratory tests using a pin-bushing tester provided measurements of the friction coefficient and temperature. Hard coated and plain (uncoated) bushings, both made of induction hardened stainless steel, were tested. Lower coefficient of friction and surface temperature were observed in the case of the coated bushing. In the …
Studies On The Heat/Mass Transfer Characteristics And Fluid Structure In A Square Internal Cooling Channel With Dimpled Surfaces, Fuguo Zhou
LSU Master's Theses
Experimental and numerical studies of heat/mass transfer on the dimpled surfaces in square channels are performed. The naphthalene sublimation method is employed in the experimental study. First, in a two-passage rotating channel, circle dimple matrices are cast on the leading and trailing walls in both the inlet and outlet of the serpentine channel. The experiments are carried out with Reynolds number of 7,000 and 21,000, and with Rotation number of 0 and 0.2. The dimpled walls lead to heat/mass transfer enhancements over smooth surfaces both in the stationary case and in the rotating case. In the stationary case, the dimple …
Optimization For Software Release And Crash, Tanvir Khan
Optimization For Software Release And Crash, Tanvir Khan
LSU Master's Theses
Software testing is a process to detect faults in the completeness and quality of developed computer software. Testing is a key process in assuring quality by identifying defects in software, and possibly fixing them, before it is delivered to end-users. A major decision to make during this software testing is, to determine whether to continue testing and eventually releasing the software, or when to stop the test and ‘crash’ it. Such a decision needs to be made to optimally balance the tradeoff between the cost of development and the reliability of the software. In this paper, a new optimal strategy …
Passive Alignment Of Micro-Fluidic Chips Using The Principle Of Elastic Averaging, Sitanshu Gurung
Passive Alignment Of Micro-Fluidic Chips Using The Principle Of Elastic Averaging, Sitanshu Gurung
LSU Master's Theses
This thesis presents a novel design for a passive alignment feature for vertically stacking chips in a micro fluidic device. Each chip is the size of a standard microscopic slide (75mm—25mm) and is a highly specialized functional unit designed and fabricated to process fluidic samples. The fluidic samples in the device flows from one chip to another using inter connecting holes 500μm-100μm in diameter. Hence an alignment of better than 100μm between chips is necessary to allow for the interconnecting holes to overlap so as to provide with a path for the fluid to flow. The feature to be used …
Data Compression With Application To Geo-Location, William Perkins
Data Compression With Application To Geo-Location, William Perkins
LSU Master's Theses
A common way to locate an emitter within a wireless sensor network requires the estimation of time-difference-of-arrival (TDOA) parameters using data collected by a set of spatially separated sensors. Compressing the data that is shared among the sensors can provide tremendous savings in terms of the energy and transmission latency. Traditional MSE and perceptual based data compression schemes fail to accurately capture the effects of compression on the TDOA estimation task; therefore, it is necessary to investigate compression algorithms suitable for TDOA parameter estimation. This thesis explores the effects of data compression on TDOA parameter estimation accuracy. The first part …
Measuring Skeletal Kinematics With Accelerometers On The Skin Surface, Kevin Curtis Ayer
Measuring Skeletal Kinematics With Accelerometers On The Skin Surface, Kevin Curtis Ayer
LSU Master's Theses
The most common motion analysis method uses cameras to track the position of markers on bodily surfaces over time. Although each species has a common skeletal frame to reference recorded motions, the soft tissue covering each is not rigid. Markers, therefore, experience motion relative to the bone and do not accurately portray underlying bone activity. This limits clinical use of motion studies and the understanding of joint motion. Use of MEMS accelerometers for removing soft tissue artifact, motion relative to the bone, from surface measurements and determining the position of the underlying bone was investigated. An animal limb was modeled …
Laboratory Characterization And Numerical Modeling Of Geogrid Reinforced Bases In Flexible Pavements, Munir Darwish Nazzal
Laboratory Characterization And Numerical Modeling Of Geogrid Reinforced Bases In Flexible Pavements, Munir Darwish Nazzal
LSU Doctoral Dissertations
This dissertation documents the results of an extensive research study that was conducted to characterize the behavior of geogrid reinforced base course materials. The research was conducted through an experimental testing and numerical modeling programs. The experimental testing program included performing different laboratory tests to evaluate the effect of various factors on the performance geogrid reinforced base course materials. Finite element models were also developed to investigate the benefits of placing geogrids within the base course layer in a flexible pavement structure. The results of the experimental testing demonstrated that the inclusion of the geogrid reinforcement layer(s) improved the compressive …
Experimental And Modeling Studies Of Contaminant Transport In Capped Sediments During Gas Bubble Ebullition, Qingzhong Yuan
Experimental And Modeling Studies Of Contaminant Transport In Capped Sediments During Gas Bubble Ebullition, Qingzhong Yuan
LSU Doctoral Dissertations
Fluxes of the three organics and eighteen metals from sediments were measured with diffusion chambers, and the effectiveness of a sand cap ascertained. The influence of sediment consolidation on contaminant flux and the mass transfer coefficient at the sediment-water interface was studied. A two-layer diffusion-advection model and consolidation model were coupled to elucidate the effect of sediment consolidation on chemical transport in the sediment-cap system. The model was tested and verified by the experimental data from microcosms, and then was used to predict phenanthrene flux under field conditions. The simulation results showed that consolidation could accelerate phenanthrene breakthrough and enhance …
Factors That Influence Visual Attention And Their Effects On Safety In Driving: An Eye Movement Tracking Approach, Larry Bargola Nabatilan
Factors That Influence Visual Attention And Their Effects On Safety In Driving: An Eye Movement Tracking Approach, Larry Bargola Nabatilan
LSU Doctoral Dissertations
Statistics show that a high percentage of road related accidents are due to factors that cause impaired driving. Since information extraction in driving is predominantly a visual task, visual distraction and its implications are therefore important safety issues. The main objective of this research is to study some of the implications of demands to human’s attention and perception and how it affects performance of tasks such as driving. Specifically, the study aims to determine the changes that occur in the visual behavior of drivers with different levels of driving experience by tracking the movement of the eye; examine the effects …
Three Dimensional Behavior Of Retaining Wall Systems, Kevin Abraham
Three Dimensional Behavior Of Retaining Wall Systems, Kevin Abraham
LSU Doctoral Dissertations
The objective of this study was to perform an engineering assessment of key three-dimensional (3-D) soil-structure interaction (SSI) features of selected earth retaining walls utilizing the nonlinear finite element method (FEM). These 3-D features are not explicitly incorporated in conventional two-dimensional (2-D) procedures that are commonly used to design these retaining walls. The research objective was accomplished utilizing the nonlinear FEM. The retaining walls selected for this research were described in detail. Design methodologies and computed responses for the walls based on conventional 2-D design procedures were summarized. Key engineering features of these structures such as construction sequence and system …
Wind Loads For Petrochemical Structures, Samuel Amoroso
Wind Loads For Petrochemical Structures, Samuel Amoroso
LSU Doctoral Dissertations
Techniques currently available to practicing engineers for estimating wind loads for petrochemical structures have little theoretical or experimental basis. This dissertation research is an effort to expand the understanding of wind effects on petrochemical and other, similar structures. Petrochemical structures introduce geometric scales into wind tunnel model simulations below what are common for enclosed structures. Wind tunnel experiments were performed to help determine whether this will introduce problems in achieving dynamic similarity between models and prototypes. The experiments did not reveal any clear indication that petrochemical structures cannot be modeled in wind tunnels at scales similar to those used for …
Monolithic Integration Of High-Aspect-Ratio Microstructures With Cmos Circuitry, Tinghui Xin
Monolithic Integration Of High-Aspect-Ratio Microstructures With Cmos Circuitry, Tinghui Xin
LSU Doctoral Dissertations
This work involves developing processing techniques for monolithically integrating a high-aspect-ratio microstructures with CMOS circuitry. A microsystem comprising of a microprobe array and signal processing circuitry is utilized as a test vehicle to demonstrate this fabrication process. One potential application of this microsystem is for recording neural signals from the central nervous system. The main results include thick photoresist processing, DC and pulse electroplating to form high-aspect-ratio microprobes, microprobe sharpening and developing a post-IC monolithic integration process. SU-8 is utilized for thick photoresist application. This work focuses on realization of a deep microrecess array in thick resists rather than traditional …
Loading And Recovery Behavior Of The Human Lumbar Spine Under Static Flexion, Guntulu Selen Hatipkarasulu
Loading And Recovery Behavior Of The Human Lumbar Spine Under Static Flexion, Guntulu Selen Hatipkarasulu
LSU Doctoral Dissertations
Musculoskeletal disorders account for 32 percent of work related injuries and illnesses. Extensive studies have been conducted to understand and explore the factors that affect the development of musculoskeletal disorders to provide effective control strategies. One of the most important factors that allow effective control strategies is the biomechanical factors. Among the biomechanical risk factors, exposures to repetitive static and vibratory activities are known to result in musculoskeletal disorders. A ligamento–muscular reflex activity exists in humans and animals to stabilize the knee, shoulder, elbow, ankle joints, and spine. This reflex activity decreases over time when static loading is applied, which …
Intercarrier Interference Suppression For The Ofdm Systems In Time-Varying Multipath Fading Channels, Xiaozhou Huang
Intercarrier Interference Suppression For The Ofdm Systems In Time-Varying Multipath Fading Channels, Xiaozhou Huang
LSU Doctoral Dissertations
Due to its spectral efficiency and robustness over the multipath channels, orthogonal frequency division multiplexing (OFDM) has served as one of the major modulation schemes for the modern communication systems. In the future, the wireless OFDM systems are expected to operate at high carrier-frequencies, high speed and high throughput mobile reception, where the fasting time-varying fading channels are encountered. The channel variation destroys the orthogonality among the subcarriers and leads to the intercarrier interference (ICI). ICI poses a significant limitation to the wireless OFDM systems. The aim of this dissertation is to find an efficient method of providing reliable communication …
Structural Performance Of Approach Slab And Its Effect On Vehicle Induced Bridge Dynamic Response, Xiaomin Shi
Structural Performance Of Approach Slab And Its Effect On Vehicle Induced Bridge Dynamic Response, Xiaomin Shi
LSU Doctoral Dissertations
Differential settlement often occurs between the bridge abutment and the embankment soil. It causes the approach slab to lose its contacts and supports from the soil and the slab will bend in a concave manner. Meanwhile, loads on the slab will also redistribute to the slab ends, which may result in faulting (or "bump") at the slab ends. Once a bump forms, repeating traffic vehicles can deteriorate the expansion joint in turn. In this case, the vehicle receives an initial disturbance before it reaches the bridge. This excitation introduces an extra impact load on the bridge and affects its dynamic …
An Adaptive Multi-Scale Computational Method For Modeling Nonlinear Deformation In Nanoscale Materials, Wenming Wang
An Adaptive Multi-Scale Computational Method For Modeling Nonlinear Deformation In Nanoscale Materials, Wenming Wang
LSU Doctoral Dissertations
In this dissertation a coupled multi-scale computational model for simulating nonlinear deformation processes in crystalline metals at finite temperatures is developed. The computational model uses the finite element method to model the coarse scale response of the material. The constitutive response in the finite element will be modeled through interatomic potentials acting on the underlying homogeneous crystal lattice that characterizes its nanostructure. An adaptive remeshing technique is proposed to automatically delineate regions of severe deformation where homogeneity of the microstructure/deformation is violated. In these regions the finite element will be replaced by a set of deformed atoms which interact with …
A Plasticity-Damage Model For Plain Concrete, Umit Cicekli
A Plasticity-Damage Model For Plain Concrete, Umit Cicekli
LSU Doctoral Dissertations
A plastic-damage model for plain concrete is developed in this work. The model uses two different yield criteria: one for plasticity and one for damage. In order to account both for compression and tension loadings, the damage criterion is divided into two parts: one for compression and a second for tension. The superscripts (+) and (-) in this work are used to represent tension and compression cases, respectively. The total stress is decomposed into tension and compressions components. The total strain is decomposed into elastic and plastic parts. The strain equivalence concept is used such that the strains in the …
Distribution Dynamics Of Complex Systems, Young-Pyo Jeon
Distribution Dynamics Of Complex Systems, Young-Pyo Jeon
LSU Doctoral Dissertations
A complex system is defined as a system with many interdependent parts having emergent self-organization; analyzing and designing such complex systems is a new challenge. A common observable structure of many complex systems is the network, which is connections among nodes, and thus inherently difficult to describe. The goal of this research is to introduce an effective methodology to describe complex systems, and thus we will construct a population balance (distribution kinetics) model based on the association-dissociation process to describe the evolution of complex systems. Networks are commonly observed structures in complex systems with interdependent parts that self-organize. How networks …
Optical Control Plane: Theory And Algorithms, Stefan Alexandru Pascu
Optical Control Plane: Theory And Algorithms, Stefan Alexandru Pascu
LSU Doctoral Dissertations
In this thesis we propose a novel way to achieve global network information dissemination in which some wavelengths are reserved exclusively for global control information exchange. We study the routing and wavelength assignment problem for the special communication pattern of non-blocking all-to-all broadcast in WDM optical networks. We provide efficient solutions to reduce the number of wavelengths needed for non-blocking all-to-all broadcast, in the absence of wavelength converters, for network information dissemination. We adopt an approach in which we consider all nodes to be tap-and-continue capable thus studying lighttrees rather than lightpaths. To the best of our knowledge, this thesis …
Development Of A Mix Design Methodology For Asphalt Mixtures With Analytically Formulated Aggregate Structures, Khalid Salim Alshamsi
Development Of A Mix Design Methodology For Asphalt Mixtures With Analytically Formulated Aggregate Structures, Khalid Salim Alshamsi
LSU Doctoral Dissertations
This research documents an extensive study on the design and characterization of asphalt mixtures for use as road pavement material. Several aspects of asphalt mixtures were addressed using the state of the art laboratory test equipment and technical literature from different information sources. The research was divided into two phases. Phase one included the design and detailed analysis of compaction and performance characteristics of asphalt concrete mixtures with aggregate structures that were designed using an analytical method of aggregate blending. Three aggregate types were considered in this study: limestone, sandstone, and granite. All the aggregates were crushed aggregates. Three different …
Electrodeposition Of Cocu Nanostructures, Yutong Li
Electrodeposition Of Cocu Nanostructures, Yutong Li
LSU Doctoral Dissertations
Electrodeposition is a key component in the microelectronic industry because it has the following advantages: low cost, easy operation and the capability to deposit into irregular geometries such as recessed and curved areas. In this dissertation, CoCu alloys were investigated to fabricate multilayers, microdevices and microposts. All of these multilayer structures were composed of nanometric copper and cobalt-rich layers in order to obtain magnetoresistance, a phenomenon where the resistance of multilayer structures decreases with increases of external magnetic field. An investigation was carried out in order to evaluate appropriate plating conditions during multilayered thin film deposition, with the aim to …
System Optimization For Realizing A Miniaturized Gas Chromatograph Sensor For Rapid Chemical Analysis, Abhinav Bhushan
System Optimization For Realizing A Miniaturized Gas Chromatograph Sensor For Rapid Chemical Analysis, Abhinav Bhushan
LSU Doctoral Dissertations
Rapid and comprehensive on-site analysis of chemicals in applications ranging from industrial process control to homeland security is of significant importance to improve the environment and save human life. The need for sensors that are fast, reliable, and portable has never been greater. For the challenging task of on-site instrumentation, where power sources can be limited, shrinking the size of the device is the most effective way to conserve power. Although gas chromatography is a mature technique well suited for these applications, current instrumentation has deficiencies that limit its usage. Speed of analysis and non portability are severe hindrances to …
Data-Driven Fault Detection Using Trending Analysis, Min Luo
Data-Driven Fault Detection Using Trending Analysis, Min Luo
LSU Doctoral Dissertations
The objective of this research is to develop data-driven fault detection methods which do not rely on mathematical models yet are capable of detecting process malfunctions. Instead of using mathematical models for comparing performances, the methods developed rely on extensive collection of data to establish classification schemes that detect faults in new data. The research develops two different trending approaches. One uses the normal data to define a one-class classifier. The second approach uses a data mining technique, e.g. support vector machine (SVM) to define multi class classifiers. Each classifier is trained on a set of example objects. The one-class …
Uv-Liga Micro-Fabrication Of Inertia Type Electrostatic Transducers And Their Application, Seok Jae Jeong
Uv-Liga Micro-Fabrication Of Inertia Type Electrostatic Transducers And Their Application, Seok Jae Jeong
LSU Doctoral Dissertations
This dissertation discusses the design, working principles, static & dynamic analysis and simulation, mechanics of material, applied MEMS technology, micro-fabrication, and experimental testing of two types of micro-transducers: micro-power relay and micro-accelerometer. Several possible design concepts were proposed, and the advantages and disadvantages of electrostatic working principles were also discussed. Transducers presented in this research used electrostatic force as a driving force in the micro-relay and capacitance as a sensing parameter in the micro-accelerometer. There was an analogy between the micro-relay and the micro-accelerometer in their theoretical approach and fabrication processes. The proposed micro-transducers (micro-relay and micro-accelerometer) were fabricated using …
Exploring The Hot-Carrier Effect On The Wireless Transceivers, Sameer R. Herlekar
Exploring The Hot-Carrier Effect On The Wireless Transceivers, Sameer R. Herlekar
LSU Doctoral Dissertations
Phase noise can be regarded as the most severe cause of performance degradation in the wireless communication systems. The hot-carriers (HCs), found in the CMOS synchronization circuits, are the high-energy charge carriers that degrade the MOSFET devices’ performance by increasing the threshold voltage required to operate the MOSFETs. The HC effect manifests itself as the phase noise whose level increases with the continued MOSFET operation and such increases result in the performance degradation of the voltage-controlled oscillator (VCO) built on the MOSFETs. The HC effect is particularly evident in the short-channel MOSFET devices. In this dissertation, we analyze the wireless …