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Articles 1 - 19 of 19
Full-Text Articles in Mechanical Engineering
Study Of Characteristics Of Plasma Nitriding And Oxidation Of Superalloy In738lc, Mary Shanti Pampana
Study Of Characteristics Of Plasma Nitriding And Oxidation Of Superalloy In738lc, Mary Shanti Pampana
LSU Master's Theses
IN738LC is a nickel base superalloy, widely used in various applications in turbine engines at high temperatures. Its oxidation and nitriding characteristics were focused in this study. Oxidation kinetics of IN738LC in dry air was studied at selected temperatures, specially chosen depending on the chemical dynamics of the alloy at such high temperatures during annealing. Isothermal oxidation in dry air was carried out at 1000°C, 1090°C, 1140°C and 1190°C. XRD results indicated an interesting onset of preferred orientation in the ã’ depleted layer in all the samples. The XPS and XRD analyses revealed the main oxide phases present in the …
Mesoscopic Simulation Of Abnormal Grain Growth, Rakesh Kumar Behera
Mesoscopic Simulation Of Abnormal Grain Growth, Rakesh Kumar Behera
LSU Master's Theses
Grain growth is the process that takes place during annealing of polycrystalline materials; its major feature is a systematic increase in grain size. Two different types of grain growth can be distinguished: the normal and abnormal grain growth. During normal grain growth, the microstructure exhibits a uniform increase in grain size with time and the grain size distribution follows the log-normal distribution with the grain sizes ranging from 0 - 2.2 times the average grain size (R). On the contrary, when the abnormal grain growth is the dominant mechanism, there are certain grains (abnormal grains) in the microstructure that grow …
Fabrication And Assembly Of An Array Of Micro Fuel Injector Nozzles For A Trapped-Vortex Combustor, Tracy Ettel Morris
Fabrication And Assembly Of An Array Of Micro Fuel Injector Nozzles For A Trapped-Vortex Combustor, Tracy Ettel Morris
LSU Master's Theses
An array of four fuel injector nozzles, each with micrometer-scale swirlers and a microhole, is created on a single coupon. The nozzles are intended to atomize fuel to blend with swirling air before ejecting into a trapped-vortex combustion chamber. A first-generation metal prototype is fabricated in order to form the micro features, supply the fuel and gas to the nozzles, and guide the mixture to the combustion chamber. Microfabrication methods and precision machining are used to create a multiple plate laminate assembly. The central plate contains the four microholes, which atomize the fuel, and facilitate the swirler structures needed to …
Towards Automated Capture Of 3d Foot Geometry For Custom Orthoses, Rajeev Madazhy
Towards Automated Capture Of 3d Foot Geometry For Custom Orthoses, Rajeev Madazhy
LSU Master's Theses
This thesis presents a novel method of capturing 3D foot geometry from images for custom shoe insole manufacture. Orthopedic footwear plays an important role as a treatment and prevention of foot conditions associated with diabetes. Through the use of customized shoe insoles, a podiatrist can provide a means to better distribute the pressure around the foot, and can also correct the biomechanics of the foot. Different foot scanners are used to obtain the geometric plantar surface of foot, but are expensive and more generic in nature. The focus of this thesis is to build 3D foot structure from a pair …
Heat/Mass Transfer In Smooth And Ribbed Rectangular Serpentine Passages Of Different Aspect Ratio's And Orientation, Peeyush Agarwal
Heat/Mass Transfer In Smooth And Ribbed Rectangular Serpentine Passages Of Different Aspect Ratio's And Orientation, Peeyush Agarwal
LSU Master's Theses
An experimental study of heat/mass transfer in rectangular smooth and ribbed serpentine passages with and without rotation in two different aspect ratios (1:4 and 4:1) channel is performed for two different orientations of the test section (90-degree and 45-degree). The Reynolds number is varied in the range of 5,000 to 40,000 and rotation numbers in the range of 0-0.12. Such passages are encountered close to the mid-chord sections or towards the trailing edge of the turbine blade. Two different configurations of the Normal ribs (e/Dh=0.3125, P/e=8 and e/Dh=0.156, P/e=11.2) are placed on the leading and the …
Synthesis, Characterization And Tribological Behavior Of Nitrogen-Doped Chromium-Diamond-Like Carbon Nanocomposite Thin Films, Sunil Kumar Pal
Synthesis, Characterization And Tribological Behavior Of Nitrogen-Doped Chromium-Diamond-Like Carbon Nanocomposite Thin Films, Sunil Kumar Pal
LSU Master's Theses
Diamond-like carbon (DLC) films have been extensively studied for more than two decades due to their highly attractive properties. These films exhibit unique mechanical, chemical and electronic properties and thus, possess great potential for applications in tribology. However, two drawbacks in the DLC films are high level of internal stress developed during growth preventing deposition of thick films and low thermal stability. Synthesis of Me-DLC (Cr-DLC and N-doped Cr-DLC) presents a way to overcome these drawbacks. In the present study, DLC, Cr-DLC and N-doped Cr-DLC films were deposited on Si substrate using a hybrid Plasma assisted CVD/PVD process. Film characterization …
Ultra Deep Su-8 Manufacturing And Characterization For Mems Applications, Charles Joseph Becnel
Ultra Deep Su-8 Manufacturing And Characterization For Mems Applications, Charles Joseph Becnel
LSU Master's Theses
The Micro Systems Engineering Team (mSET) at Louisiana State University (LSU) utilizes microfabrication for a number of heat and mass transfer devices. These include cross flow heat exchangers, mechanical seals with integrated micro heat exchangers, catalytic converters, and micro reactors. In all of these applications, micro honeycomb arrays provide increased surface area per unit volume which significantly enhances heat and mass transfer. In the past, it was only possible to fabricate SU-8 structures approximately 1.5 mm tall. Furthermore, qualitatively, it is much more difficult to fabricate close packed feature arrays than sparse arrays. For many of the previously mentioned applications, …
Effects Of Corrosion Prevention Compounds And Overload Induced Residual Stress Field On Fatigue Life In Aluminum Alloy, Jin Hee Park
Effects Of Corrosion Prevention Compounds And Overload Induced Residual Stress Field On Fatigue Life In Aluminum Alloy, Jin Hee Park
LSU Master's Theses
Corrosion-Prevention Compounds (CPC) are commonly used to prevent corrosion in the aircraft industry. The presence of corrosive environment (salt-fog, water-fog, even dry air) on aircraft structures has detrimental effects on the integrity of aircraft components which reduces the fatigue life and may accelerate the crack growth rate in the structures. This thesis work is aimed at identifying the effect of CPC and corrosion fatigue on the fatigue life of test specimen. This study describes the results of an experimental study on aluminum alloy 2024-T3 with center-crack specimen to investigate the effect of CPC on fatigue life. Generally, these compounds contain …
Numerical And Experimental Investigation Of Transport Processes In Biological Systems, Yimeng He
Numerical And Experimental Investigation Of Transport Processes In Biological Systems, Yimeng He
LSU Master's Theses
This thesis focuses on optimization techniques for transport process during the cryopreservation of biological systems. In the first part of this thesis, a well established shape independent Differential Scanning Calorimeter (DSC) technique was used to measure the dehydration response during freezing of Pacific oyster sperm cells. Volumetric shrinkage during freezing of diploid and tetraploid pacific oyster sperm cell suspensions was obtained at cooling rates of 5 and 20 ˚C/min in the presence of extracellular ice and CPAs. By fitting a model of water transport to the experimentally obtained volumetric shrinkage data the best fit membrane permeability parameters (Lpg and …
A Novel Mechanical Seal Design With Superior Thermal Characteristics, Anoop Kumar Somanchi
A Novel Mechanical Seal Design With Superior Thermal Characteristics, Anoop Kumar Somanchi
LSU Master's Theses
A mechanical face seal is an important component of variety of pumps used in chemical, petrochemical and process industry. The primary function of a mechanical seal is to prevent leakage of the process fluid from the pump housing and shaft to the environment. The factors that affect the performance of a mechanical seal to leak are friction, wear and its thermal characteristics. Improving upon the thermal characteristics of a mating ring in a mechanical seal would enhance its performance. Implanting a heat exchanger in the mating ring hold great promise for improving the performance of mechanical seals from the viewpoint …
A Simplified Thermohydrodynamic Stability Analysis Of The Plain Cylindrical Hydrodynamic Journal Bearings, Sumit Singhal
A Simplified Thermohydrodynamic Stability Analysis Of The Plain Cylindrical Hydrodynamic Journal Bearings, Sumit Singhal
LSU Master's Theses
A journal bearing is used to support radial loads under high speed operating conditions. In a journal bearing, pressure or hydrodynamic lift is generated in the thin lubricant oil film that separates the shaft and the bushing, thus preventing metal-to-metal contact. Some journal-bearing configurations are susceptible to large-amplitude, lateral vibrations due to a “self-excited instability” known as oil whirl. In order to investigate the effects of lubricant viscosity on oil whirl, a simplified Thermohydrodynamic analysis (THD) analysis of a plain cylindrical journal bearing system has been developed. The “classical” form of the Reynolds equation coupled with simplified, first-order energy equations …
Design, Fabrication And Thermomechanical Testing Of A Vertical Bimorph Sensor In The Wafer Plane, Madhulika Sathe
Design, Fabrication And Thermomechanical Testing Of A Vertical Bimorph Sensor In The Wafer Plane, Madhulika Sathe
LSU Master's Theses
A bimetallic recurve device was designed, fabricated and tested as a temperature sensor. The device is to be used for sensing temperatures up to 300 C inside oil wells for downhole condition monitoring. Continuous downhole measurements at high temperatures and pressures are required to monitor conditions downhole instruments are exposed to during use. Currently mercury thermometers and resistive temperature detectors (RTD) are used for downhole temperature measurements. Microsensors have potential application downhole, due to their small size and inherent robustness. The principle of a bimetallic beam was used to measure temperature. A bimetallic beam deflects with changes in temperature due …
Tissue Interactions With Lasers And Liquid Nitrogen: A Novel Cryopreservation Method, Deepak Kandra
Tissue Interactions With Lasers And Liquid Nitrogen: A Novel Cryopreservation Method, Deepak Kandra
LSU Master's Theses
The importance of the imposed cooling rate in cryopreserving native cells and tissues has been long recognized in the field of cryobiology. When biological tissues are subjected to cooling rates in excess of thousands of degree C per minute, the characteristic structural and physical manifestations of the ice formed are such that the traditional damage due to ice formation at lower cooling rates are suppressed. Hence, achieving high cooling rates in tissues and cells of biologically relevant sizes (mm’s and cm’s) has been a long standing research problem. In the present study, we present a novel technique to achieve high …
Towards Automation Of Forensic Facial Reconstruction, Hemant Narendra Khatod
Towards Automation Of Forensic Facial Reconstruction, Hemant Narendra Khatod
LSU Master's Theses
Forensic facial reconstruction is a blend of art and science thus computerizing the process leads to numerous solutions. However, complete automation remains a challenge. This research concentrates on automating the first phase of forensic facial reconstruction which is automatic landmark detection by model fitting and extraction of feature points. Detection of landmarks is a challenging task since the skull orientation in a 3D scanned data cloud is generally arbitrary and unknown. To address the issue, well defined skull and mandible models with known geometric structure, features and orientation are (1) aligned and (2) fit to the scanned data. After model …
Optimal Rate Of Freezing Biological Systems, Sreedhar Thirumala
Optimal Rate Of Freezing Biological Systems, Sreedhar Thirumala
LSU Master's Theses
This thesis addresses optimization techniques for cryopreservation of biological systems. A part of the thesis (Chapter 2) reports a simplified procedure to predict the optimal rate of freezing biological systems once the cell level parameters are known a priori. The key cell level parameters investigated were, reference permeability of the membrane to water (Lpg), apparent activation energy (ELp), inactive cell volume (Vb), diameter (D), and the ratio of the available surface area for water transport to the initial volume of intracellular water (SA/WV). The simplified procedure was developed by performing a thorough analysis of the water transport model over a …
A Bio-Mems Device For Separation Of Breast Cancer Cells From Peripheral Whole Blood, Juan Feng
A Bio-Mems Device For Separation Of Breast Cancer Cells From Peripheral Whole Blood, Juan Feng
LSU Master's Theses
This work demonstrates the application of Bio-Micro Electro Mechanical System (Bio-MEMS) technology for early breast cancer detection and diagnosis. Early breast cancer detection and diagnosis typically uses conventional mammogram screening followed by biopsy, which can be problematic since mammography can only detect highly calcified tumors greater than 1 cm in size. A micro-device was developed to identify and specifically collect tumor cells of low abundance (1 tumor cell among 107 normal blood cells) from circulating whole blood. By immobilizing anti-EpCAM (Epithelial Cell Adhesion Molecule) antibodies on polymer micro-channel walls by the chemical surface modification of PMMA, breast cancer cells …
Design Of A Microfabricated Device For Ligase Detection Reaction (Ldr), Dwhyte Omar Barrett
Design Of A Microfabricated Device For Ligase Detection Reaction (Ldr), Dwhyte Omar Barrett
LSU Master's Theses
The Ligase Detection Reaction (LDR) is a mutation detection technique used to identify point mutations in deoxyribonucleic acid (DNA). Developed by Francis Barany and associates at Cornell University it is used to find specific low abundant point mutations that may lead to colorectal cancer in the early stages of disease development. The research objective was to design and manufacture a microscale Ligase Detection Reaction (LDR) device in polycarbonate. The LDR module will be incorporated with other microdevices such as: Continuous Flow Polymerase Chain Reaction (CFRCR) and Capillary Electrophoresis (CE) in modular lab-on-a-chip technology. In making the microdevice, the duration of …
Innovative Cooling Configurations For Low Emission Gas Turbine Combustors, Ryan Thomas Hebert
Innovative Cooling Configurations For Low Emission Gas Turbine Combustors, Ryan Thomas Hebert
LSU Master's Theses
Presently, effective cooling of modern low NOx combustor liners is achieved through combinations of innovative impingement configurations and other heat transfer enhancement methods. An inherent characteristic of conventional impingement configurations is the occurrence of downstream heat transfer degradation due to increased crossflow effects. In the present study, two different impingement configurations are studied. Both impingement configurations examined in this study aim to increase heat transfer effectiveness by reducing the detrimental effects of spent air crossflow. In Part I, a combination technique wherein impingement is combined with ribs placed in between impingement rows is studied. Three configurations with increased rib placements …
Experimental Validation Of A Smart-Bias Active Magnetic Bearing Controller, Shailesh Pradhananga
Experimental Validation Of A Smart-Bias Active Magnetic Bearing Controller, Shailesh Pradhananga
LSU Master's Theses
Active magnetic bearings (AMBs) are being increasingly employed in the aerospace industry in a variety of devices including compressors, turbines, pumps, and flywheels. One application of great interest to future space missions is the Integrated Power and Attitude Control System (IPACS). The IPACS consists of an arrangement of flywheels that integrates the energy storage and attitude control functions into a single system; thereby, reducing the spacecraft mass, volume, launching cost, and maintenance. Like any energy storage system, flywheels need to be operated with low power losses. AMBs are ideally suited for flywheels because they eliminate mechanical losses (friction). Nevertheless, AMBs …