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Articles 121 - 150 of 452

Full-Text Articles in Mechanical Engineering

Heat And Mass Transfer In A Cylindrical Heat Pipe With Idealized Porous Lining, Pramesh Regmi Jan 2017

Heat And Mass Transfer In A Cylindrical Heat Pipe With Idealized Porous Lining, Pramesh Regmi

LSU Master's Theses

Many devices use heat pipes for cooling. They can be of different cross-sectional shapes and can range from 15 m long to 10 mm. In this work, the heat and mass transfer in a cylindrical heat pipe is modelled. The heat pipe is lined with a wick next to the wall. The wick consists of straight capillaries that run the whole length of the pipe and radially aligned capillaries that span the width of the wick. The capillaries are filled with a partially wetting liquid, and the center of the pipe is filled with its vapor. The radial capillaries are …


Osteogenic Potential Of Poly (L-Lactic Acid) Scaffolds Prepared By Thermally Controlled Methods On Human Adipose Derived Stem Cells, Harish Chinnasami Shanmugam Jan 2017

Osteogenic Potential Of Poly (L-Lactic Acid) Scaffolds Prepared By Thermally Controlled Methods On Human Adipose Derived Stem Cells, Harish Chinnasami Shanmugam

LSU Doctoral Dissertations

Thermally Induced Phase Separation (TIPS) method was used to make porous three-dimensional PLLA scaffolds. The effect of imposed thermal profile during freezing of the PLLA in dioxane solution on the scaffold was characterized by their micro-structure, porosity (%), pore-sizes distribution and mechanical strength. The porosity (%) decreased considerably with increasing concentrations of PLLA in the solution, while a decreasing trend was observed with increasing cooling rates. The mechanical strength increases with increase in PLLA concentration and also with increase in the cooling rate for both types of solvents. Therefore, mechanical strength was increased by higher cooling rates while the porosity …


Development Of Laboratory Scale Conical Spouted Bed Reactors, James Blake Gegenheimer Jan 2017

Development Of Laboratory Scale Conical Spouted Bed Reactors, James Blake Gegenheimer

LSU Master's Theses

Conical spouted beds (CSBs) are a form of a fluidized bed that is characteristic of its spouting behaviors. The conical spouted bed has a small inlet that diverges through a conical section towards a larger fixed-diameter column which is filled with static spouting media. By injecting a fluid at a sufficient velocity, a small spout will form in which the spouting media will become entrained by the fluid particles and carried to the top of the system where it will circulate back into the system. It has been shown that CSB reactors have the potential for increasing the heat circulation …


Analytical Solutions And Multiscale Creep Analysis Of Functionally Graded Cylindrical Pressure Vessels, Jasem Amjad Ahmed Jan 2017

Analytical Solutions And Multiscale Creep Analysis Of Functionally Graded Cylindrical Pressure Vessels, Jasem Amjad Ahmed

LSU Doctoral Dissertations

This study deals with the time-dependent creep analysis of functionally graded thick-cylinders under various thermal and mechanical boundary conditions. Firstly, exact thermoelastic stress, and iterative creep solutions for a heat generating and rotating cylindrical vessel made of functionally graded thermal and mechanical properties are proposed. Equations of equilibrium, compatibility, stress-strain, and strain-displacement relations are solved to obtain closed-form initial stress and strain solutions. It is found that material gradient indices have significant influences on thermoelastic stress profiles. For creep analysis, Norton’s model is incorporated into rate forms of the above-mentioned equations to obtain time-dependent stress and strain results using an …


Material Evaluation Of A Lightweight, Automated Canned Pet Food Dispenser, Kathryn Marie Carr May 2016

Material Evaluation Of A Lightweight, Automated Canned Pet Food Dispenser, Kathryn Marie Carr

Honors Capstones

No abstract provided.


Impact Of Additive Manufacturing Technologies And The Development Ofa Mixed Metal Powderbed Additive Manufacturing System, Gerald L. Knapp Apr 2016

Impact Of Additive Manufacturing Technologies And The Development Ofa Mixed Metal Powderbed Additive Manufacturing System, Gerald L. Knapp

Honors Capstones

No abstract provided.


Weld Quality Classification From Sensory Signatures In Friction-Stir-Welding (Fsw) Using Discrete Wavelet Transform And Advanced Metaheuristic Techniques, James Devecmon Roberts Jan 2016

Weld Quality Classification From Sensory Signatures In Friction-Stir-Welding (Fsw) Using Discrete Wavelet Transform And Advanced Metaheuristic Techniques, James Devecmon Roberts

LSU Master's Theses

Controlling the quality of welds is an essential part of high quality fabrications and ensuring structural integrity of welded joints and welded structures. Industry is in an endless pursuit to find more cost effective methods of testing welds for defects and eliminating them entirely. This Study contributes to this goal by investigating a new system with the ability to monitor welding conditions during the forging process. Monitoring the condition of the weld, while the metals are joined together is faster and more cost- effective than conventional methods of post-weld defect detection. In this study, the feedback signals are first collected …


A Comparison Between Functional And Traditional Interface Displays In Support Of Console Operator Performance And Workload, Sophie Lynn Schwartz Jan 2016

A Comparison Between Functional And Traditional Interface Displays In Support Of Console Operator Performance And Workload, Sophie Lynn Schwartz

LSU Master's Theses

In the petrochemical industry, schematic interfaces have been traditionally used as the main interface for console operators to monitor activities. There is limited research in this industry investigating alternative interface types to better support console operator’s decisions during alarm management. Furthermore, even less of that research includes eye-tracking as a measure for console operator situation awareness (SA). This research aimed to investigate an alternative interface, called a functional interface, in its level of support of console operator situation awareness, accuracy, subjective workload, and average response time. Additionally, eye-tracking was incorporated to explore its value as measure for situation awareness on …


Hybrid Ant Colony Optimization For Fuzzy Unrelated Parallel Machine Scheduling Problems, Po An Su Jan 2016

Hybrid Ant Colony Optimization For Fuzzy Unrelated Parallel Machine Scheduling Problems, Po An Su

LSU Master's Theses

This study extends the best hybrid ant colony optimization variant developed by Liao et al. (2014) for crisp unrelated parallel machine scheduling problems to solve fuzzy unrelated parallel machine scheduling problems in consideration of trapezoidal fuzzy processing times, trapezoidal fuzzy sequencing dependent setup times and trapezoidal fuzzy release times. The objective is to find the best schedule taking minimum fuzzy makespan in completing all jobs. In this study, fuzzy arithmetic is used to determine fuzzy completion times of jobs and defuzzification function is used to convert fuzzy numbers back to crisp numbers for ranking. Eight fuzzy ranking methods are tested …


The Design, Fabrication, And Validation Of A Film Cooled Rotating Turbine Cascade With An Actively Cooled Shroud In A Closed Loop Wind Tunnel, Christopher Michael Drewes Jan 2016

The Design, Fabrication, And Validation Of A Film Cooled Rotating Turbine Cascade With An Actively Cooled Shroud In A Closed Loop Wind Tunnel, Christopher Michael Drewes

LSU Master's Theses

To test shroud and blade cooling effectiveness, a closed loop, heated wind tunnel housing a film cooled rotating turbine cascade with prescribed blade and vane geometry surrounded by a fully cooled shroud with a leading edge gap were designed and assembled on Louisiana State University’s campus. Heat transfer coefficients and film cooling effectiveness results were computed using a 1-D semi-infinite solid conduction analysis of material temperatures obtained with liquid crystal thermography. Proper analysis required a step change in air temperature; so a bypass loop provided mainstream air heating while maintaining the shroud and blades at ambient temperature. Also, analysis required …


Thermophysical And Thermochemical Property Measurement And Prediction Of Liquid Metal Titanium Alloys With Applications In Additive Manufacturing, Jonathan Richard Raush Jan 2016

Thermophysical And Thermochemical Property Measurement And Prediction Of Liquid Metal Titanium Alloys With Applications In Additive Manufacturing, Jonathan Richard Raush

LSU Doctoral Dissertations

Accurate high-temperature thermophysical property data for liquid metals and alloys are important for simulation of laser-based 3D printing processes. To understand and better control such additive manufacturing processes, knowledge of density, viscosity, and surface tension of liquid metals and alloys versus composition and temperature is needed. Likewise, thermochemical property data information regarding alloys, including chemical activities and free energies relative to composition and temperature, aid in the understanding and development of phase data important in the material design process. Vacuum electrostatic levitation (ESL) is an important technique through which both thermophysical and thermochemical property measurements can be accomplished without physical …


Design Of Surface Texture For The Enhancement Of Tribological Performance, Cong Shen Jan 2016

Design Of Surface Texture For The Enhancement Of Tribological Performance, Cong Shen

LSU Doctoral Dissertations

Surface texturing is a method of surface modification that fabricates micro patterns on the contacting surfaces to improve the tribological performance in sliding, lubricated system. It is found that the geometric design of textures has a significant influence on the performance of textured surfaces. Some important geometric parameters, such as the area ratio and the depth-over-diameter ratio, have been identified for textures in the form of circular dimples. The current study aims to improve the friction reduction effect of surface texturing by using textures with novel designs. Some new factors considered in the design of textures are: internal structure and …


On The Degradation Of Lubricating Grease, Asghar Rezasoltani Jan 2016

On The Degradation Of Lubricating Grease, Asghar Rezasoltani

LSU Doctoral Dissertations

A comprehensive literature review on physical and chemical degradation monitoring and life estimation models for lubricating greases is presented in chapter one. Degradation mechanisms for lubricating grease are categorized and described, and an extensive survey of the available empirical and analytical grease life estimation models including degradation monitoring standards and methods are presented. In chapter two, irreversible thermodynamic theory is employed to study the mechanical degradation of lubricating grease. A correlation between the mechanical degradation and entropy generation is established and the results are verified experimentally using a rheometer, a journal bearing test rig, and a modified grease worker machine. …


Fabrication And Characterization Of Thiol-Acrylate Based Polymer For Bone Tissue Engineering Application, Anoosha Forghani Jan 2016

Fabrication And Characterization Of Thiol-Acrylate Based Polymer For Bone Tissue Engineering Application, Anoosha Forghani

LSU Master's Theses

Thiol-acrylate materials have been demonstrated to have therapeutic potential as biocompatible scaffolds for bone tissue regeneration due to their osteoconductivity, biodegradability, and well-suited mechanical properties. This study connects the mechanical properties and stability of thiol-acrylate polymer with cell adhesion and proliferation of human adipose derived stromal cells. The polymer presented in this study, trimethylolpropane ethoxylate triacrylate-co-trimethylolpropane tris (3-mercaptopropionate) (TMPeTA-co-TMPTMP), was synthesized by an amine-catalyzed Michael addition reaction. Physical, mechanical, and chemical characterizations were performed on the polymeric scaffold, followed by preliminary in vitro cytocompatibility tests. Live/dead staining assays showed significant differences in cell adhesion for TMPeTA (692 and 912 MW). …


Characterization Of Thermoplastic Fusion Bonding Of Microchannels Using Pressure Assisted Boiling Point Control System, Kavya Dathathreya Jan 2016

Characterization Of Thermoplastic Fusion Bonding Of Microchannels Using Pressure Assisted Boiling Point Control System, Kavya Dathathreya

LSU Master's Theses

An innovative method of thermoplastic fusion bonding using a pressure assisted boiling point control (PABP) system was characterized to determine the optimum parameters for bonding polymethyl methacrylate (PMMA) components containing microchannels and thin, 250 µm cover sheets. The PABP system enables precise control of the temperature boundary condition and the applied pressure by immersing the components being bonded in boiling water and varying the vapor pressure. Test structure geometries containing microchannels of two depths and four different aspect ratios were designed: 1:10 (Depth: 10µm, Width: 100 µm and Depth: 5µm, Width: 50 µm), 1:50 (Depth: 10µm, Width: 500µm and Depth: …


Optimal Configuration Of Inspection And Rework Stations In A Multistage Flexible Flowline, Md. Shahriar Jahan Hossain Jan 2016

Optimal Configuration Of Inspection And Rework Stations In A Multistage Flexible Flowline, Md. Shahriar Jahan Hossain

LSU Master's Theses

Inspection and rework are two important issues of quality control. In this research, an N-stage flowline is considered to make decisions on these two issues. When defective items are detected at the inspection station the items are either scrapped or reworked. A reworkable item may be repaired at the regular defect-creating workstation or at a dedicated off-line rework station. Two problems (end-of-line and multistage inspections) are considered here to deal with this situation. The end-of-line inspection (ELI) problem considers an inspection station located at the end of the line while the multistage inspection (MSI) problem deals with multiple in-line inspection …


Molecular Dynamics Simulation Study Of Single Dna Nucleotides Transport Through Nanoslits, Kai Xia Jan 2015

Molecular Dynamics Simulation Study Of Single Dna Nucleotides Transport Through Nanoslits, Kai Xia

LSU Doctoral Dissertations

There is potential for flight time based DNA sequencing involving disassembly into individual nucleotides which would pass through a nanochannel with 2 or more detectors. Molecular dynamics simulation of electrophoretic motion of single DNA nucleotides through 3 nm wide hydrophobic slits was performed. Electric field strength (E) varied from 0.0 to 0.6 V/nm. Slit walls were smooth or had a roughness similar to nucleotide size. Multiple nucleotide-wall adsorptions occurred. The electric field did not influence the nucleotide adsorption and desorption mechanism for E ¡Ü 0.1 V/nm, but influenced nucleotide orientation relative to the field direction. The nucleotide-wall interactions differed due …


Heat Transfer Study Of Porous Media With A Temperature Jump Condition, Pravin Kumar Jan 2015

Heat Transfer Study Of Porous Media With A Temperature Jump Condition, Pravin Kumar

LSU Master's Theses

Conjugate heat transfer in a porous media is investigated with a temperature jump condition obtained from kinetic gas theory. The temperature jump appears alongside flow boundary condition when the pressure is low, and considered to be in non-continuum regime. This investigation focuses on both one-dimensional and two-dimensional porous media models. The length scale of the pores is 100 microns. The temperature is ambient, and the pressure is low enough to reach the slip-flow regime. The thermal behavior of porous media is investigated using a slot model with a gas trapped between two solid blocks. Aluminum oxide and air are considered …


Degradation And Fatigue Involving Dissipated Processes, Md Liakat Ali Jan 2015

Degradation And Fatigue Involving Dissipated Processes, Md Liakat Ali

LSU Doctoral Dissertations

Irreversible material degradation due to cyclic mechanical loading is investigated utilizing the concept of thermodynamic entropy, plastic strain energy, and temperature slope measurement. Uniaxial tension-compression and fully-reversed bending fatigue tests are performed over a wide range of loading conditions with metallic and composite materials subject to both constant- and variable-amplitude loading. A methodology is developed for the estimation of the fatigue fracture entropy (FFE) and fatigue toughness of metallic specimens in a rapid fashion. It is found that the FFE and the fatigue toughness of each material tested are within a small band. The value of FFE is found to …


Numerical Studies Of Liquid-Liquid Segmented Flows In Square Microchannels Using A Front-Tracking Algorithm, Eamonn Daire Walker Jan 2015

Numerical Studies Of Liquid-Liquid Segmented Flows In Square Microchannels Using A Front-Tracking Algorithm, Eamonn Daire Walker

LSU Doctoral Dissertations

Liquid-liquid segmented flows in a square microchannel are investigated numerically using a hybrid front-tracking/front-capturing method. The code is found to be well-adapted to a large range of flow parameters, but droplet flows are limited by poor accuracy at Laplace number above 100 – 1000 and plug flows are limited by the code’s current inability to adequately model the flow in thin films at low capillary numbers. A Schwarz-Aitken acceleration technique is investigated as a means to reduce computation time, but is found not to be advantageous compared to the parallel multigrid formulation of the code. Numerical simulations are divided into …


Chemical Structure And Dynamics In Laminar Flame Propagation, Mohsen Ayoobi Jan 2015

Chemical Structure And Dynamics In Laminar Flame Propagation, Mohsen Ayoobi

LSU Doctoral Dissertations

The objective of this dissertation is to investigate fundamental aspects of premixed flame structures as well as flame dynamics that arise due to conjugate heat transfer in narrow channels. Laminar premixed combustion simulations in narrow 2D channels show that conjugate heat transfer allows for combustion of mixtures at small scales that are not flammable at normal conditions. To investigate the impact of conjugate heat transfer, preheated 1D cases with premixed H2/Air fuel are simulated for a wide range of operating conditions based on inlet temperature and equivalence ratio. For post-processing, Chemical Explosive Mode Analysis (CEMA, an eigen-analysis technique) is used …


Effect Of Appointment Schedules On The Operational Performance Of A University Medical Clinic, Arunn Pisharody Vijayan Jan 2015

Effect Of Appointment Schedules On The Operational Performance Of A University Medical Clinic, Arunn Pisharody Vijayan

LSU Master's Theses

Healthcare costs in the United States are one of the highest in the world. The healthcare expenditure alone accounted for 17.9% of the Gross Domestic Product of US in 2011. The National Healthcare Expenditure (NHE) is expected to increase at an annual rate of 6.6% from $ 2.6 Trillion in 2010 to $ 4.5 Trillion in 2019. The per capita expenditure for hospital outpatients and physicians has been the highest among other hospital expenses. This escalation in expenses created a need for productivity improvements in the healthcare industry to control costs. Some of the common problems encountered in outpatient clinics …


Exploration Of Segmented Flow In Microchannels Using The Volume Of Fluid Method In Ansys Fluent, Jace Michael Boudreaux Jan 2015

Exploration Of Segmented Flow In Microchannels Using The Volume Of Fluid Method In Ansys Fluent, Jace Michael Boudreaux

LSU Master's Theses

Segmented flow can be utilized in lab-on-a-chip technologies to speed up chemical and biological analysis. Segmented flow (also known as Taylor flow or the Bretherton problem) has often been explored in circular channels, but rectangular channels are more common for microfluidics applications. To this end, pressure-driven droplet flow in a square microchannel is studied using the volume of fluid method in ANSYS Fluent, a computational fluid dynamics program. It was found that for low Reynolds number (Ret = 0.01) and droplet sizes larger than the channel diameter, the flow is mostly influenced by capillary number and viscosity ratio. The …


Experimental Study Of A Cascade Of Low Pressure Turbine Blades With Upstream Periodic Stator Wakes, Carlos Rene Gonzalez Rodriguez Jan 2015

Experimental Study Of A Cascade Of Low Pressure Turbine Blades With Upstream Periodic Stator Wakes, Carlos Rene Gonzalez Rodriguez

LSU Master's Theses

The objective of this study is to experimentally study film cooling flows. A closed-loop wind tunnel with a four passage linear cascade of US Air Force Research Laboratory (AFRL) ultra-high-lift L1A low pressure turbine (LPT) blades and upstream wake generator is used in conjunction with Particle Image Velocimetry (PIV) flow visualization technique to study turbulent film cooling flows due to the interaction between vanes and blades. Further post-processing in the form of Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) modal analyses is performed to determine the relevant modes that characterize the coherent structures in the flow. An image …


Radiation Heat Transfer In A Particulate Medium Using A Ray Tracing Method, Manish B. Patil Jan 2015

Radiation Heat Transfer In A Particulate Medium Using A Ray Tracing Method, Manish B. Patil

LSU Master's Theses

In the present work, a complete 3D simulation of ray tracing model is developed for studying the radiation heat transfer, associated with laser based additive manufacturing, in both thick and thin particulate beds by using the Monte Carlo method. Additional program is developed for creating different types of packing structures such as simple cubic, rhombohydral and random packing. The scattering mechanisms in the particulate beds for large opaque spheres are evaluated using the specular and diffuse reflection methods. Further, a novel approach has been added to the model to include isotropic, forward and backward scattering mechanisms for a medium which …


Development Of A Three-Dimensional Bioprinter With Inline Light Activation For Bone Tissue Engineering, Colton Alexander Mcelheny Jan 2015

Development Of A Three-Dimensional Bioprinter With Inline Light Activation For Bone Tissue Engineering, Colton Alexander Mcelheny

LSU Master's Theses

Bioprinting offers exciting possibilities for tissue engineering related to tissue and organ failure due to trauma, disease, or aging. This is of substantial societal value as the world populace mean age rises. Current needs for tissue and organ repair far exceed availability. A strategy being explored to counter this imbalance is the single step fabrication of cellular constructs. This paper explores various bioprinting techniques and suggests a custom design for a cost-effective, low-maintenance bioprinting platform for academic research. The platform functionality was validated via two-dimensional image transfer and simple three-dimensional geometries.


A Comparative Assessment Of Ergonomic Risk Factors In University Personnel Using Rula And Reba Aiming To Study The Cause And Effect Relationship, Nabila Chowdhury Jan 2015

A Comparative Assessment Of Ergonomic Risk Factors In University Personnel Using Rula And Reba Aiming To Study The Cause And Effect Relationship, Nabila Chowdhury

LSU Master's Theses

The aim of this research was to conduct an ergonomic assessment of working postures and the design of computer workstations of the employees in Louisiana State University. The purpose of the study was threefold- (1) to determine the major ergonomic issues in university employees while working on computer workstations, (2) to compare the two ergonomic assessment tools (RULA and REBA) to see how similarly or differently they assess the risks present in the same working condition and (3) to develop a model that correlates between working condition, work posture and computer workstation design with their effects on musculoskeletal system. This …


On The Role Of Surface Roughness In Elastohydrodynamic Lubrication Of Tribological Components, Mohammad Masjedi Jan 2015

On The Role Of Surface Roughness In Elastohydrodynamic Lubrication Of Tribological Components, Mohammad Masjedi

LSU Doctoral Dissertations

The present dissertation investigates the effect of surface roughness in the elastohydrodynamic lubrication (EHL). Since many essential components of the machinery such as gears, rolling element bearings, cam-followers, and heavily loaded journal bearings operate under the mixed EHL condition, and given the fact that nearly all engineering surfaces are rough to some extent, there is a need for an extensive research which can realistically quantify the effect of the surface roughness in such applications. We thus seek to develop an applied engineering approach for the treatment of the mixed EHL for prediction of the performance of machinery. Both line-contact and …


Deposition And Characterization Of Ceramic Thin Films And A New Experimental Approach To Evaluate The Mechanical Integrity Of Film/Substrate Interfacial Layers, Yang Mu Jan 2015

Deposition And Characterization Of Ceramic Thin Films And A New Experimental Approach To Evaluate The Mechanical Integrity Of Film/Substrate Interfacial Layers, Yang Mu

LSU Doctoral Dissertations

Due to their corrosion resistance, high temperature stability, high strength, and high hardness, refractory ceramic thin films and coatings have been utilized for surface engineering of mechanical components and mechanical fabrication tools. Adhesion between ceramic thin films and coatings and the substrate is of critical concern for performance and life time of coated systems. In this dissertation, a custom designed and constructed ultra-high-vacuum (UHV) vapor phase deposition system was used for the preparation of ceramic thin films through low-pressure high-density plasma assisted physical vapor deposition (PVD) methods. Deposited thin films were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), …


On The Thermally Induced Failure Of Rolling Element Bearings, Jafar Takabi Jan 2015

On The Thermally Induced Failure Of Rolling Element Bearings, Jafar Takabi

LSU Doctoral Dissertations

This dissertation is devoted to the investigation of thermally induced seizure of rolling element bearings. A comprehensive thermal model of the rolling element bearings is developed which can predict the operating temperature of the bearing components in a wide range of operating conditions. The validity of this thermal model is verified by comparing the simulation results with a set of experiments. The results of simulations reveal that the rotational speed, oil viscosity and cooling rate of the housing have a significant influence on the operating temperature of the rolling bearings. To provide detailed information about all of the contact forces …