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Full-Text Articles in Mechanical Engineering

An Investigation Into Fuel Cells And Flow Cytometers Optimal Design, Etim Sunday Udoetok Jan 2008

An Investigation Into Fuel Cells And Flow Cytometers Optimal Design, Etim Sunday Udoetok

LSU Doctoral Dissertations

The aim of the fuel cells part of this project was to investigate the performance of Proton Exchange Membrane Fuel Cells and closely related fuel cell types like the Alkaline Fuel Cells and Phosphoric Acid Fuel Cells. The investigation involved understanding the performance of fuel cells, addressing the shortcomings of currently used designs, and finding new methods for improving the performance of fuel cells. CFD was used to study flow channels and information learned from the study was used to design a new and improved flow channel. A prototype of the new design was fabricated, tested and found to perform ...


Numerical Simulations Of Flow And Mass Transport In Micro-Fluidic Components For Modular Bio-Analytic Chip Applications, Sudheer D. Rani Jan 2008

Numerical Simulations Of Flow And Mass Transport In Micro-Fluidic Components For Modular Bio-Analytic Chip Applications, Sudheer D. Rani

LSU Doctoral Dissertations

Microfluidics has received a great deal of attention in the past decade. The ability of modular microfluidic chips to miniaturize integrate chemical and biological systems (┬ÁTAS) can be greatly productive in terms of cost and efficiency. During the design of these modular devices, misalignment of materials, geometrical or both is one of the most common problems. These misalignments can have adverse effect in both pressure driven and electrokinetically driven flows. In the present work, Numerical Simulations have been performed to study the effect of material and geometrical mismatch on the flow behavior and species progression in microfluidic interconnects. In the ...


Microassembly Technology For Modular, Polymer Microfluidic Devices, Byoung Hee You Jan 2008

Microassembly Technology For Modular, Polymer Microfluidic Devices, Byoung Hee You

LSU Doctoral Dissertations

Assembly of modular, polymer microfluidic devices with different functions to obtain more capable instruments may significantly expand the options available for detection and diagnosis of disease through DNA analysis and proteomics. For connecting modular devices, precise, passive alignment structures can be used to prevent infinitesimal motions between the devices and minimize misalignment. The motion and constraint of passive alignment structures were analyzed using screw theory. A combination of three v-groove and hemisphere-tipped post joints constrained all degrees of freedom of the two mating modules without overconstraint. Simulations and experiments were performed to assess the predictability of dimensional and location variations ...


Thermomechanical Interaction Analysis Of Bodies Subjected To Oscillatory Heat Source, Jun Wen Jan 2008

Thermomechanical Interaction Analysis Of Bodies Subjected To Oscillatory Heat Source, Jun Wen

LSU Doctoral Dissertations

Surface heating by application of a moving heat source is a common problem in most manufacturing processes as well as in many tribological applications. The existing literature on studies of moving heat source problems primarily concentrates on unidirectional moving heat sources. Yet, a more complete analysis requires understanding of thermal behavior of bodies in relative sliding contacts subjected to oscillatory heat sources and thermomechanical interaction. In this dissertation, two analytical models are developed for rapid evaluation of the transient temperature in solids undergoing oscillatory heat source. In the first model, an analytical technique is presented to treat oscillatory heat source ...


Replication Of Metal-Based Microscale Structures By Compression Molding: A Combined Experimental And Finite Element Analysis Study, Jing Jiang Jan 2008

Replication Of Metal-Based Microscale Structures By Compression Molding: A Combined Experimental And Finite Element Analysis Study, Jing Jiang

LSU Doctoral Dissertations

Fabrication of microscale Ta mold inserts by micro-electrical-discharge-machining (├ČEDM) is reported. Morphology, chemistry, and structure of the near-surface region of as-machined Ta blanks have been characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. A TaC surface layer forms on as-machined Ta surfaces. This altered surface layer was removed by electro-chemical-polishing. Further modification of Ta insert surfaces was accomplished by deposition of a conformal Ti-containing hydrogenated carbon coating. We demonstrate successful replication of high-aspect-ratio microscale structures (HARMS) in Al and Cu by compression molding with such surface-engineered Ta mold inserts. In addition, a hybrid microfabrication technique, combining ...


Cryopreservation Of Adipose Derived Adult Stem Cells And Multidimensional Cell Sheets, Sreedhar Thirumala Jan 2008

Cryopreservation Of Adipose Derived Adult Stem Cells And Multidimensional Cell Sheets, Sreedhar Thirumala

LSU Doctoral Dissertations

Human adipose tissue provides a uniquely abundant and accessible source of adult stem cells. In response to chemical, hormonal or structural stimuli, these human adipose-derived adult stem (ASCs) cells can differentiate along multiple lineage pathways, including adipocytes, chondrocytes, myocytes, neurons and osteoblasts. Successful cryopreservation of scientifically and commercially important ASCs would revolutionize the tissue engineering and regenerative medicine industry. In this research, we have investigated the water transport phenomenon during freezing of several passages of adipose derived adult stem cells and generated the membrane permeability parameters in the presence and absence of cryoprotective agents. These measured permeability parameters were then ...