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2010

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Articles 4441 - 4470 of 5375

Full-Text Articles in Engineering

Electrodeposited Cu-Based Catalysts For Alcohols From Co Hydrogenation And Electrodeposition Of Cuniw/Cuni Multilayered Alloys, Mayank Gupta Jan 2010

Electrodeposited Cu-Based Catalysts For Alcohols From Co Hydrogenation And Electrodeposition Of Cuniw/Cuni Multilayered Alloys, Mayank Gupta

LSU Doctoral Dissertations

Ethanol and higher alcohols can be used as a fuel or fuel additive in gasoline engines as well as a hydrogen carrier. One of the promising methods to synthesize these alcohols is based on thermochemical conversion of CO and H2 (CO hydrogenation). Conventional catalysts used for the conversion CO and H2 (syngas) to ethanol typically give yields less than 20% with the balance resulting mostly in the formation of the thermodynamically favored products CH4 and CO2. New catalysts with compositions designed to kinetically favor the formation of ethanol and higher alcohols are needed. Electrodeposition of nanowires offers a means to …

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Dynamic Trip Distribution Models For Hurricane Evacuation, Guangxiang Cheng Jan 2010

Dynamic Trip Distribution Models For Hurricane Evacuation, Guangxiang Cheng

LSU Doctoral Dissertations

The dissertation presents several methods to estimate time-dependent origin-destination (O-D) trip tables for hurricane evacuation using survey data from hurricane Floyd in South Carolina in 1999. A static disaggregate destination choice model in multinomial logit form was developed considering household characteristics, hurricane threats, and destination socioeconomic and demographic characteristics. Models were developed for persons evacuating to friends or relatives, and hotels or motels separately. None of the household characteristics of evacuees were found to be significant in distinguishing destination choice but destination characteristics were. The model was tested by comparing the observed destination choices with predicted values via trip length …

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X-Ray Absorption Spectroscopy Applied To Mixed-Metal Iron-Based Fischer-Tropsch Catalysts, Andrew Allen Campos Jan 2010

X-Ray Absorption Spectroscopy Applied To Mixed-Metal Iron-Based Fischer-Tropsch Catalysts, Andrew Allen Campos

LSU Doctoral Dissertations

Synthetic fuels derived from methane, coal or biomass are essential in addressing future transportation fuel demands which are expected to exceed petroleum-derived capacities. The Fischer-Tropsch synthesis (FTS) is the most studied technique for the conversion of coal or biomass-derived syngas into transportation fuels. Fe-based catalysts are typically used for the FTS of biomass and/or coal-derived syngas due to: the relatively low cost of iron, water-gas shift activity, and low methane selectivity at industrial FTS conditions. Fe/Cu/SiO2 Fischer-Tropsch catalysts promoted with Cr, Mn, Mo, W, or Zr were studied in-situ, using Fe K-edge TPR XANES (temperature programmed reduction X-ray absorption near-edge …

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Modeling And Multiresolution Characterization Of Micro/Nano Surface For Novel Tailored Nanostructures, Rajib Mukherjee Jan 2010

Modeling And Multiresolution Characterization Of Micro/Nano Surface For Novel Tailored Nanostructures, Rajib Mukherjee

LSU Doctoral Dissertations

Nanofabrication is state of the art technology. Various chemical, mechanical, biochemical and semiconductor products have characteristics controlled by the nanostructures of the surface and interphase. Surface microscopic imaging is generally used to capture different surface features. By properly analyzing the surface image, valuable information regarding manufacturing process and product performance can be extracted. While microscopy measurements can offer very accurate qualitative information about surface features, for many applications, it is critical to obtain a quantitative description of the surface morphology. Various statistical features can be used to characterize the surface in quantitative way. Such an analysis can be done by …

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Friction And Wear At Elevated Velocities, Adam Lodygowski Jan 2010

Friction And Wear At Elevated Velocities, Adam Lodygowski

LSU Doctoral Dissertations

Severe contact stress problems generate high temperature and create thermomechanical gouging and wear due to high velocity sliding between contacting materials. The major consideration is to develop an experimental and theoretical model for the material constitutive behavior in order to better characterize and predict the internal failure surroundings the gouging and wear events and understand the physical behavior of high speed contact environment. An enhancement of an existing tribometer device developed by Philippon et al. [2004] is made up of a dynamometer ring and a load sensor that allows to apply an apparent normal force on specimens and measure frictional …

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Effects Of Bondline Thickness On Nonlinear Interfacial Fracture Of Bonded Adhesive Joint, Gefu Ji Jan 2010

Effects Of Bondline Thickness On Nonlinear Interfacial Fracture Of Bonded Adhesive Joint, Gefu Ji

LSU Doctoral Dissertations

A number of existing and emerging industrial applications are dependent on layered substrates through adhesive bonding. The interfacial fracture of adhesively bonded structures is a critical issue for its extensive applications to a variety of modern industries. In the recent two decades, cohesive zone models (CZMs) have been receiving intensive attentions for fracture problems of adhesively bonded joints due to its fairly simple and accurate predictive ability. In CZMs the nonlinear interfacial fracture behaviors are described by the traction-separation laws (also referred to as cohesive laws). The cohesive laws represent the local constitutive behavior, instead of the global parameter, such …

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Supercritical Pyrolysis Of N-Decane, Sean Bagley Jan 2010

Supercritical Pyrolysis Of N-Decane, Sean Bagley

LSU Doctoral Dissertations

Fuels used in future generations of high-speed jet aircraft will be required to take on increasing heat loads in their role as the primary coolant for the absorption of waste heat from the engine. As a consequence, the hydrocarbon fuels will be exposed to elevated temperatures and pressures prior to their use as fuels, conditions which are beyond the critical point of the fuel and which lead to the formation of carbonaceous solid deposits in the pre-combustion environment.

Deposition of solids causes reduced engine performance and eventual failure, so understanding the mechanisms by which thermally stressed hydrocarbons become solids is …

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Evaluation Of Project Delivery Methods For Trenchless Construction, Sahar W. Hasan Jan 2010

Evaluation Of Project Delivery Methods For Trenchless Construction, Sahar W. Hasan

Civil Engineering Theses - Archive

The need of today's construction whether it be residential, commercial or infrastructure is to cut costs while maintaining schedule, scope, and delivering the expected quality. This realization has brought to light the importance of project delivery methods. Project delivery methods are no longer seen only as procedures to follow for a construction project; they have become instruments that are being used to save money, deliver projects ahead of schedule and come up with innovative design solutions by utilizing the contractor's expertise. This thesis evaluates the pros and cons of project delivery methods with respect to trenchless construction. Trenchless technology methods …

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Time Depedent Queuing Models Of The National Airspace, Chatabush Roongrat Jan 2010

Time Depedent Queuing Models Of The National Airspace, Chatabush Roongrat

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

Air transportation in the US system has dramatically changed in the past few decades. The National Airspace System (NAS) has increasingly become congested. A high volume of air traffic demand is one of the major challenges of the NAS. However, air traffic is very difficult to study due to many uncertainties involved. It is important that we be able to understand the relationship under uncertainties due to aviation operations, precision of navigation and control, and traffic flow efficiency. Many queuing models have been studied to better understand and quantify these relationships. In the past decade, most queuing network models assume …

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Synthesis And Characterization Of Ferromagnetic Nanowires, Poching Tsai Jan 2010

Synthesis And Characterization Of Ferromagnetic Nanowires, Poching Tsai

Material Science and Engineering Theses - Archive

Ferromagnetic nanocrystals with shape anisotropy have drawn great attention in the past decades because of their unique magnetic properties and for their potential applications in ultra-high-density magnetic recording media, exchange-coupled nanocomposite magnets and related nanodevices. In this thesis, synthesis and characterixation of ferromagnetic CoNi and CoFe nanowires are reported. CoNi nanocrystals with different size, shape and composition were successfully synthesized via a catalyst chemical solution method. It was found out that the structure and morphology can be controlled by altering the NaOH concentration, and the elongation of the nanowires can be adjusted by changing surfactants ratio and catalyst amount. Unlike …

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Solid-State Tunneling Spectroscopy Of Individual Quantum Dots, Ramkumar Subramanian Jan 2010

Solid-State Tunneling Spectroscopy Of Individual Quantum Dots, Ramkumar Subramanian

Material Science and Engineering Dissertations - Archive

Quantum dots are gaining importance for their potential applications in the fields of energy harvesting, bio-labeling and treatment, in opto-electronic devices and in photonic devices. For all these applications, it is imperative to know their electronic structure. Although currently several spectroscopic techniques exist to study the electronic structure of these quantum dots, they are accompanied by other effects and do not give purely the electronic structure of the individual quantum dot. The main goals of this research are to:o To study the energy level structure of `single' quantum dots.o Develop a new spectroscopic technique that allows the measurement of the …

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Transmission Electron Microscopy Studies Of Lamno₃ And La₁₋Xsrxmno₃Thin Films Grown On Various Substrates, Yinsheng Fang Jan 2010

Transmission Electron Microscopy Studies Of Lamno₃ And La₁₋Xsrxmno₃Thin Films Grown On Various Substrates, Yinsheng Fang

Material Science and Engineering Theses - Archive

LaMnO₃ (LMO) and La₁₋xSrxMnO₃ (LSMO) thin films with colossal magnetoresistance have attracted considerable interest for potential applications in many technological devices, such as magnetic sensors and read-head of computer memory. In this work, polycrystalline and epitaxial LMO and LSMO thin films were deposited on various substrates including (001) Si, (001) MgO, and (001) LaAlO₃ (LAO) using RF magnetron sputtering. The microstructures of the thin films were initially studied using X-ray diffraction. Detailed microstructure information such as crystallite of the films, grain size, epitaxial quality, crystallographic structure and film/substrate interface were studied using high-resolution transmission electron microscope (HRTEM). More specifically, Effects …

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Investigating The Effects Of Various Crowd Characteristics On The Dynamic Properties Of An Occupied Structure, Robert Joseph Firman Iii Jan 2010

Investigating The Effects Of Various Crowd Characteristics On The Dynamic Properties Of An Occupied Structure, Robert Joseph Firman Iii

Honors Theses

One of the challenges for structural engineers during design is considering how the structure will respond to crowd-induced dynamic loading. It has been shown that human occupants of a structure do not simply add mass to the system when considering the overall dynamic response of the system, but interact with it and may induce changes of the dynamic properties from those of the empty structure. This study presents an investigation into the human-structure interaction based on several crowd characteristics and their effect on the dynamic properties of an empty structure. The dynamic properties including frequency, damping, and mode shapes were …

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Active Noise Barrier Minimizing Pressure Gradient, Carl Hart, Siu-Kit Lau Jan 2010

Active Noise Barrier Minimizing Pressure Gradient, Carl Hart, Siu-Kit Lau

Durham School of Architectural Engineering and Construction: Faculty Publications

Minimization of the sound pressure field within the shadow zone of a noise barrier is achieved by reducing the pressure gradient along a line, at the top of a barrier, via active noise control. The noise control effectiveness of a barrier is increased by this strategy, especially for specific system configurations. The proposed method was evaluated by numerical simulation. Results indicate that system orientation has little effect on minimizing the pressure gradient at the top of the barrier when the error sensors are invisible to the primary noise disturbance. Highly effective control within the shadow zone and close to the …

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Audio Watermarking Using Transformation Techniques, Rajkiran Ravula Jan 2010

Audio Watermarking Using Transformation Techniques, Rajkiran Ravula

LSU Master's Theses

Watermarking is a technique, which is used in protecting digital information like images, videos and audio as it provides copyrights and ownership. Audio watermarking is more challenging than image watermarking due to the dynamic supremacy of hearing capacity over the visual field. This thesis attempts to solve the quantization based audio watermarking technique based on both the Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT). The underlying system involves the statistical characteristics of the signal. This study considers different wavelet filters and quantization techniques. A comparison is performed on diverge algorithms and audio signals to help examine the performance …

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Effect Of Management Awareness Of Safety Climate Concept On Organizational Safety Climate, Christopher Michael Holzner Jan 2010

Effect Of Management Awareness Of Safety Climate Concept On Organizational Safety Climate, Christopher Michael Holzner

LSU Master's Theses

Safety research and practice have shifted focus away from accident rates and accident causal information to a more proactive approach that may predict organizational safety trends. This proactive approach involves the concept of an organizational safety culture and the use of surveys to measure organizational safety climate or „snapshot‟ of the organizational safety culture. Surveys were administered to line workers, supervisors, and managers at a modular home manufacturing company before and after safety climate information was presented to supervisors and managers in an attempt to measure the effect of the supervisors‟ and managers‟ increased awareness of the factors that define …

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Investigating The Use Of Bioengineered Oyster Reefs As A Method Of Shoreline Protection And Carbon Storage, Daniel D. Dehon Jan 2010

Investigating The Use Of Bioengineered Oyster Reefs As A Method Of Shoreline Protection And Carbon Storage, Daniel D. Dehon

LSU Master's Theses

The Louisiana Gulf Coast is losing land at an alarming rate for a combination of reasons. At the same time carbon dioxide is accumulating in the atmosphere and the oceans by the increased burning of fossil fuels. Therefore, bioengineered oyster dominated artificial reefs have been developed in an effort to mitigate erosion while storing carbon in the oyster shells. These reefs support the growth of a native oyster species, Crassostrea virginica, which are considered ecological engineers and serve to improve water quality, protect coastal wetlands, capture and store carbon, and enhance the economy. Evaluation of test pieces showed the addition …

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Hydrodynamic Modeling Of San Elijo Lagoon, California, Mary Elizabeth Nee Friedmann Bourgoyne Jan 2010

Hydrodynamic Modeling Of San Elijo Lagoon, California, Mary Elizabeth Nee Friedmann Bourgoyne

LSU Master's Theses

Decisions on where to concentrate management efforts need to be guided by an ability to accurately simulate and predict physical and ecological changes. Many restoration projects experience difficulties due to a lack of understanding of the ecological response and evolution of wetland systems (Goodwin et al., 2001). There are several approaches that can be taken in analyzing a system. The appropriate selection should be based on the available data, the spatial scale of the wetland, and the physical processes governing the system (Goodwin and Kamman, 2001). Predictive tools are essential for good long-term management (Goodwin et al., 2001). The objective …

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Implementation Of Risk Management In The Medical Device Industry, Rachelo Dumbrique Jan 2010

Implementation Of Risk Management In The Medical Device Industry, Rachelo Dumbrique

Master's Theses

This study looks at the implementation and effectiveness of risk management (RM) activities in the medical device industry. An online survey was distributed to medical device professionals who were asked to identify RM-related activities performed during the device life cycle. RM activities and techniques included Establishing Risk Acceptance Criteria, Hazard Identification, Human Factors/Usability, Fault Tree Analysis (FTA), Design Failure Mode and Effects Analysis (DFMEA), Process Failure Mode and Effects Analysis (PFMEA), Hazard and Operability Study (HAZOP), Hazard Analysis and Critical Control Point (HACCP), Risk Benefit Analysis, and Risk Assessment of Customer Complaint. Devices were identified by type (therapeutic, surgical/clinical tools, …

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Phase Investigation Of Zirconia Fibers And Their Applications On Solid Oxide Fuel Cells (Sofcs), Luping Li Jan 2010

Phase Investigation Of Zirconia Fibers And Their Applications On Solid Oxide Fuel Cells (Sofcs), Luping Li

LSU Master's Theses

Pure zirconia nanofibers were fabricated by electrospinning zirconia-polymer precursor and subsequent annealing. Fiber properties such as polymer decomposition, crystallization formation, phase transformation, surface morphologies, etc., were investigated by various techniques, including thermogravimetric analysis (TGA) and differential thermal analysis (DTA), high temperature differential scanning calorimeter (HTDSC), powder X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), etc. It was found the crystallization of as-spun fibers started at 450 °C and the initial crystallized zirconia phase was tetragonal (t), which began transforming to monoclinic (m) phase at 650 °C as evidenced by XRD; HTDSC showed at different thermal circles, the m-to-t transformation …

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Degradation Behavior Of Shape Memory Polymer Due To Water And Diesel Fuel, Mohammad Nazmul Hasan Nahid Jan 2010

Degradation Behavior Of Shape Memory Polymer Due To Water And Diesel Fuel, Mohammad Nazmul Hasan Nahid

LSU Master's Theses

Shape memory polymers (SMP) are smart materials, which have the ability to memorize the original or permanent shape. Owing to this characteristic SMP can be used as a sensor, a transplant, as well as structural materials in wide range of applications. Despite its importance, its degradation behavior is still not completely known; and only a limited amount of work has been reported in the literature. In this thesis, the experiments have been carried out to evaluate the degradation behavior of Veriflex- SMP (industry supplied SMP samples) upon exposure to two different types of liquids; water and diesel fuel separately. It …

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Optimization Of New Chinese Remainder Theorems Using Special Moduli Sets, Narendran Narayanaswamy Jan 2010

Optimization Of New Chinese Remainder Theorems Using Special Moduli Sets, Narendran Narayanaswamy

LSU Master's Theses

The residue number system (RNS) is an integer number representation system, which is capable of supporting parallel, high-speed arithmetic. This system also offers some useful properties for error detection, error correction and fault tolerance. It has numerous applications in computation-intensive digital signal processing (DSP) operations, like digital filtering, convolution, correlation, Discrete Fourier Transform, Fast Fourier Transform, direct digital frequency synthesis, etc. The residue to binary conversion is based on Chinese Remainder Theorem (CRT) and Mixed Radix Conversion (MRC). However, the CRT requires a slow large modulo operation while the MRC requires finding the mixed radix digits which is a slow …

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Itraconazole Loaded Poly (Lactic-Co-Glycolic) Acid Nanoparticles For Improved Antifungal Activity, Nipur Rajan Patel Jan 2010

Itraconazole Loaded Poly (Lactic-Co-Glycolic) Acid Nanoparticles For Improved Antifungal Activity, Nipur Rajan Patel

LSU Master's Theses

PLGA (polylactic-co-glycolic acid) nanoparticles containing the hydrophobic antifungal Itraconazole (ITZ) were developed to address the need for more efficient means of treating fungal infections. PLGA-ITZ nanoparticles were synthesized using an oil-in-water emulsion evaporation method. The nanoparticles morphology (TEM), size and size distribution, zeta potential (DLS), encapsulation efficiency (UV-VIS), release profile, and antifungal activity were characterized. The blank NPs and loaded PLGA-ITZ NPs were spherical with diameters of 201±5 nm, 232±1 nm and 223±36 nm at 0%, 12.5% and 25% loadings, respectively. All synthesized particles measured a negative zeta potential ranging from -28 to -33 mV. The maximum encapsulation efficiency of …

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Modeling And Analysis Of Radial Flux Toroidally Wound Twin Rotor Permanent Magnet Motor, Ravi Kishore Pratapa Jan 2010

Modeling And Analysis Of Radial Flux Toroidally Wound Twin Rotor Permanent Magnet Motor, Ravi Kishore Pratapa

LSU Master's Theses

The main objective of current thesis is the study of Radial Flux Twin Rotor Permanent Magnet (RFTWTRPM) motor. The tasks were to review the literature about RFTWTPM motors and model the motor using Finite Element Method Magnetics (FEMM 4.0). Later the performance of RFTWTRPM motor as a brushless dc motor was analyzed by using MATLAB/SIMULINK package. To find the electrical and mechanical parameters of the RFTWTRPM motor, the rotor and stator dimensions of the motor were firstly optimized using linear FEMM model of the motor. The optimized dimensions were used to construct the cylindrical FEMM model. This model was later …

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Operational And Safety Assessment Of Joint And Conventional Lane Merge Configurations For Freeway Work Zones, Pradeep Rayaprolu Jan 2010

Operational And Safety Assessment Of Joint And Conventional Lane Merge Configurations For Freeway Work Zones, Pradeep Rayaprolu

LSU Master's Theses

Inefficient operation of traffic at work zone areas typically leads to increase in travel time delays, queue length, fuel consumption, number of forced merges, and roadway accidents. In order to improve the operational efficiency of work zones, research on freeway work zones constantly seeks to develop different lane merge control strategies, in addition to the conventional lane merge configuration, recommended by the Manual on Uniform Traffic Control Devices. This study evaluates the operational efficiency and safety benefits of a newly proposed configuration, joint lane merge (JLM), and compare its performance with the conventional lane merge (CLM) configuration. A simulation model …

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Experimental Study On Single Cement Fracture Exposed To Co2 Saturated Brine Under Dynamic Conditions, Tevfik Yalcinkaya Jan 2010

Experimental Study On Single Cement Fracture Exposed To Co2 Saturated Brine Under Dynamic Conditions, Tevfik Yalcinkaya

LSU Master's Theses

Carbon capture and storage is one of the technologies that could help reduce CO2 concentration in the atmosphere while contributing to cutback of Greenhouse Gas emissions. Depleted oil and gas fields are favorable targets for CO2 storage because existing wells can be readily used as injection wells. However, a number of abandoned wells also serve as gateway to the reservoir which should be considered in the context of effective Carbon capture and storage. Wellbore cement is a very essential element in wellbore systems that serve as a barrier between different zones in the subsurface. The fractures inside wellbore cement sheath, …

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Cost Effective Prevention Of Reflective Cracking In Composite Pavements, Rakesh Bandaru Jan 2010

Cost Effective Prevention Of Reflective Cracking In Composite Pavements, Rakesh Bandaru

LSU Master's Theses

Louisiana had experimented with various techniques and treatments to control reflection cracking since the 1970s; however, the cost-effectiveness and performance of these methods had not been reliably evaluated. In addition, scientific evaluation and testing of these treatment methods was not performed on many projects. To ensure successful control of this distress and effective allocation of maintenance funds, there is a critical need to assess the performance of pavement sections across the state built with various treatment methods and to determine the most cost-effective techniques to delay or to prevent reflection cracking in composite pavements. The objective of this study is …

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The Effects Of Lean On Employees' Affective Attitude In A Modular Homebuilding Manufacturer, Digvesh Khot Jan 2010

The Effects Of Lean On Employees' Affective Attitude In A Modular Homebuilding Manufacturer, Digvesh Khot

LSU Master's Theses

Many organizational problems are related to job dissatisfaction, job-related stress, and lack of commitment in workers. Employees’ Affective Attitude (EAA) involves these three factors: job satisfaction, job stress, and commitment. This research is aimed at measuring the impact of Lean concepts on EAA factors. While providing an overview of Lean production and construction, this study focuses on one fundamental Lean concept, Kaizen. This thesis describes a case study showcasing the application of Lean concepts through Kaizen events and its impact on EAA for a modular homebuilder company. Based on previous literature a conceptual model was developed describing the potential links …

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Characterization Of Composite Piezoelectric Materials For Smart Joint Applications, Hari Prasad Konka Jan 2010

Characterization Of Composite Piezoelectric Materials For Smart Joint Applications, Hari Prasad Konka

LSU Master's Theses

Piezoelectric materials have the ability to provide desired transformation from mechanical to electrical energy and vice versa. When a mechanical force is applied to the piezoelectric material an electrical voltage is generated and when an electrical voltage is applied to the piezoelectric material it gets strained or deformed. Owing to these characteristics piezoelectric materials can be used as a sensor, an actuator, as well as a power generation unit. The high brittleness property of the original piezoelectric material is one of the major constraints in using them in the engineering applications. In order to overcome this disadvantage the composite piezoelectric …

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Desulfurization And Tar Removal From Gasifier Effluents Using Mixed Rare Earth Oxides, Sumana Adusumilli Jan 2010

Desulfurization And Tar Removal From Gasifier Effluents Using Mixed Rare Earth Oxides, Sumana Adusumilli

LSU Master's Theses

Biomass gasification is a promising source of fuels. However, hydrogen sulphide, tars and other by-products must be removed from the raw gas because they deactivate downstream reforming and water gas shift catalysts. The goal of this project is to find the best REO combination for simultaneous tar cracking and desulfurization of gasifier effluents and to find the sorbents that are stable at high operating temperatures of gasifiers. Simultaneous tar cracking and H2S removal from a simulated gasifier effluent was tested using different rare earth mixed oxide (REO) catalysts/sorbents based on Ce/LaOx, Ce/La/MOx and Ce/La/M2Ox/Al2O3 where M is a transition metal …

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