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- Film cooling (3)
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Articles 1 - 30 of 36
Full-Text Articles in Mechanical Engineering
Thermal Cycling And Thermal Radiation Performances Of Novel Thermal Barrier Coatings, Li Wang
Thermal Cycling And Thermal Radiation Performances Of Novel Thermal Barrier Coatings, Li Wang
LSU Doctoral Dissertations
Thermal barrier coatings (TBCs) play an important role in protecting the superalloy components from the hot gas stream in gas-turbine engines. Driven by the higher inlet temperature of modern gas turbine engines for higher efficiency and less harmful gas emission, exploration of TBC new materials and thermal radiation effects of TBCs have attracted more attentions recently. In this study, thermochemical compatibility of Gd2Zr2O7 (GZ) and yttria-stabilized-zirconia (YSZ) at 1300 ºC was investigated. Single, double and three ceramic-layered GZ based TBCs were prepared and their thermal cycling properties were performed under different thermal conditions. Thermochemical compatibility investigation showed that YSZ tended …
Modeling And Simulation Of Surface Profile Forming Process Of Microlenses And Their Application In Optical Interconnection Devices, Zhengyu Miao
LSU Doctoral Dissertations
Free space micro-optical systems require to integrate microlens array, micromirrors, optical waveguides, beam splitter, etc. on a single substrate. Out-of-plane microlens array fabricated by direct lithography provides pre-alignment during mask fabrication stage and has the advantage of mass manufacturing at low cost. However, this technology requires precise control of the surface profile of microlenses, which is a major technical challenge. The quality control of the surface profile of microlenses limits their applications. In this dissertation, the surface forming process of the out-of-plane microlenses in UV-lithography fabrication was modeled and simulated using a simplified cellular automata model. The microlens array was …
Measurement Of Continuum Breakdown Using A Disc Spin-Down Experiment In Low Pressure Air, Tathagata Acharya
Measurement Of Continuum Breakdown Using A Disc Spin-Down Experiment In Low Pressure Air, Tathagata Acharya
LSU Doctoral Dissertations
As flow becomes rarefied, a quantity called as the tangential momentum accommodation coefficient (TMAC) becomes important because it is a measure of the momentum transport from a gas molecule to a surface. Very few experimental measurements of continuum breakdown in boundary layer flows exist. All experimental measurements of the TMAC in macro-scale boundary layer flows have been done in the continuum slip and the transition flow regimes. Moreover the experimental apparatus used by previous researchers cannot accommodate for materials that are planar by nature such as those used in the field of aerospace and microfabrication. The objectives of this research …
Metal-Based Microchannel Heat Exchangers : Manufacturing And Heat Transfer Testing, Bin Lu
Metal-Based Microchannel Heat Exchangers : Manufacturing And Heat Transfer Testing, Bin Lu
LSU Doctoral Dissertations
This dissertation focuses on improving the functionality of metal-based microchannel heat exchangers (MHEs), as well as pushing this technology toward real-world applications. Design optimization was carried out on MHEs for performance maximization. Double-layered microchannel layout was experimentally studied, and a significant reduction on liquid flow pressure drop penalty was achieved. Other than water, another commonly-used coolant, ethylene glycol, was applied to MHEs, and flow and heat transfer characteristics were quantified. Transient Liquid Phase (TLP) bonding was used for joining Cu structures. For further understanding of the MHE heat transfer, a detailed examination was carried out on the TLP bonding interface …
A Fluorescent Oil Detection Device, Yuxuan Zhou
A Fluorescent Oil Detection Device, Yuxuan Zhou
LSU Doctoral Dissertations
On April 20th 2010, the largest offshore oil spill in U.S. history happened in the Gulf of Mexico. It is estimated total more than 4 million barrels oil spilled to Gulf of Mexico. More than two million gallons had been used. This had made the threat to coastal and sea ecosystem even greater and long term. Real-time monitoring is also a critical topic for oil spill response. In-situ monitoring devices are needed for rapid collection of real-time data. A new generation of instruments for spilled oil detection is reported in this paper. The main hypothesis in this research is that …
Fabrication And Characterization Of A Polymeric Nanofluidic Device For Dna Analysis, Jiahao Wu
Fabrication And Characterization Of A Polymeric Nanofluidic Device For Dna Analysis, Jiahao Wu
LSU Doctoral Dissertations
The growing needs for cheaper and faster sequencing of long biopolymers such as DNA and RNA have prompted the development of new technologies. Among the novel techniques for analyzing these biopolymers, an approach using nanochannel based fluidic devices is attractive because it is a label-free, amplification-free, single-molecule method that can be scaled for high-throughput analysis. Despite recent demonstrations of nanochannel based fluidic devices for analyzing physical properties of such biopolymers, most of the devices have been fabricated in inorganic materials such as silicon, silicon nitride and glass using expensive high end nanofabrication techniques such as focused ion beam and electron …
A Study On The Cleaning And Modification Of Metal Surfaces By Direct Current Cathodic Electrolytic Plasma Process, Jiandong Liang
A Study On The Cleaning And Modification Of Metal Surfaces By Direct Current Cathodic Electrolytic Plasma Process, Jiandong Liang
LSU Doctoral Dissertations
The processes of surface treatments or surface modifications, more formally known as surface engineering, tailor the surfaces of engineering materials. The treatments are usually intended to change physical properties such as thermal or electrical conductivity, modify the surface dimensions, i.e. roughness, etc. A novel surface treatment method, Electrolytic Plasma Process (EPP), was developed for coating purposes, in its early developmental stage. In this work, the major effort is to avoid using any environmental hazardous chemical (coatings) and to extend such its application to some new fields. The general response of the substrate material under electrolytic plasma process was summarized including …
Effect Of Surface Roughness On The Efficiency Of Self-Healing Polymers, Ifeanyi Janarus Okoro
Effect Of Surface Roughness On The Efficiency Of Self-Healing Polymers, Ifeanyi Janarus Okoro
LSU Master's Theses
A shape memory polymer (SMP) is a smart material capable of maintaining two distinct shapes depending on its temperature. A SMP is soft at temperatures above its glass transition temperature but hard below it. When copolyester thermoplastic additives are dispersed in a SMP, it becomes a SMP-based particulate composite capable of self-healing at both the molecular level and the structural level. This makes it very desirable for industrial applications. Upon damage to the composite, the surfaces at the damage interface have to come into contact for efficient healing; the shape memory effect, coupled with a confined recovery (healing) process, ensures …
Synthesis Of Poly(L-Lactic Acid) Scaffolds From Dioxane/Ethanol Using Control Rate Freezing And Study Of Its Microstructural Properties, George Idicula
Synthesis Of Poly(L-Lactic Acid) Scaffolds From Dioxane/Ethanol Using Control Rate Freezing And Study Of Its Microstructural Properties, George Idicula
LSU Master's Theses
Bio-degradable poly (l-lactic acid) (PLLA) scaffolds were prepared by using thermally induced phase separation (TIPS) method. A solution of PLLA-Dioxane was formed by dissolving PLLA in dehydrated 1,4-Dioxane at three wt/vol percentages, specifically 3, 7 and 10%. This PLLA-Dioxane solution was then frozen in borosilicate glass vials (5mL) at three cooling rates (1, 10 and 40 ˚C/min) in a commercially available controlled rate freezer (CRF). The frozen solution was freeze-dried to sublimate the Dioxane. The microstructural properties of the resulting PLLA scaffolds were determined utilizing Scanning Electron Microscopy (SEM) images and uni- axial compressive testing. The relationship between the wt/vol …
Numerical Evaluation And Analysis Of The Adhesion Phenomena In Thermal Barrier Coating Systems Through Bio-Mimicking Plasma Process, Naser Imran Hossain
Numerical Evaluation And Analysis Of The Adhesion Phenomena In Thermal Barrier Coating Systems Through Bio-Mimicking Plasma Process, Naser Imran Hossain
LSU Master's Theses
Thermal Barrier Coatings or TBCs when abbreviated are an imperative part of the thermal protection system of expensive equipment and machinery in the automobile and aeronautics industry. They provide protection to expensive alloy materials upto a temperature of 2700° C without expensive metallurgical additions. Unfortunately, the problem of coating adhesion has plagued the TBC field for years, leading to catastrophic failures in critical TBC systems. Efforts to chemically improve bond strength has not been entirely successful, so the only other efficient way to do this would be some kind of mechanical interlocking that occurs at micro/nano scales. This research work …
Parametric Optimization Of A Single-Tracked Vehicle, Darrick Jason Berner
Parametric Optimization Of A Single-Tracked Vehicle, Darrick Jason Berner
LSU Master's Theses
ABSTRACT The purpose of a suspension system for a vehicle is to contribute to the handling and assist in isolating the occupants from vibrations due to road irregularities. Generally, these primary functions are often at odds so the goal is to design a suspension system that finds the appropriate compromise. The focus of this thesis is to develop a two degree of freedom model and use parametric analysis to demonstrate an optimization technique by varying several geometric characteristics on a single-track vehicle. Furthermore, a dynamic vibration absorber will be added to the model to demonstrate its effect on the system. …
Comparison Of In Vivo Human Knee Joint Kinematics Using Axodes, Jacob Hipps
Comparison Of In Vivo Human Knee Joint Kinematics Using Axodes, Jacob Hipps
LSU Master's Theses
The human knee is of particular interest because of its importance in mobility. Pain and stability can be directly related to the motion, or kinematics, of the knee. Many studies have been conducted to quantify human knee kinematics, both in vitro and in vivo. One of the inherent issues with in vivo, skin mounted measurement systems is that they do not account for soft tissue artifact. Compensation for soft tissue artifact has been a difficult challenge for skin mounted tracking systems and has not yet been achieved. Therefore, bone mounted skeletal pins were chosen as the method of gathering kinematic …
Nanotube Film-Enhanced 3-D Photoanode For Application In Microsystems Technology, Fareed Dawan
Nanotube Film-Enhanced 3-D Photoanode For Application In Microsystems Technology, Fareed Dawan
LSU Doctoral Dissertations
Surface area plays an important factor in the energy conversion performance of solar cells. It has also emerged as a critical factor in the evolution of high-performance micro-electro-mechanical systems (MEMS) and multifunctional microstructures most of which will benefit from integrated on-chip solar power. Presented here is the hierarchical fabrication and characterization of TiO2 nanotubes on non-planar 3-dimensional microstructures for enhanced performance of the photoanode in dye-sensitized solar cells (DSSCs). The objective is to increase photoanode performance within a 1 cm2 lateral footprint area by increasing the vertical surface area through the formation of TiO2 nanotubes on 3-D microstructures. In the …
Developing Defect-Tolerant Demolding Process In Nanoimprint Lithography, Alborz Amirsadeghi
Developing Defect-Tolerant Demolding Process In Nanoimprint Lithography, Alborz Amirsadeghi
LSU Doctoral Dissertations
Demolding, the process to separate stamp from molded resist, is most critical to the success of ultraviolet nanoimprint lithography (UV-NIL). In the present study we first investigated adhesion and demolding force in UV-NIL for different compositions of a model UV-curable resist containing a base (either tripropyleneglycol diacrylate with shorter chain length or polypropyleneglycol diacrylate with longer chain length), a cross-linking agent (trimethylolpropane triacrylate) and a photoinitiator (Irgacure 651). The demolding force was measured using a tensile test machine after imprinting the UV resist on a silicon stamp. In general, the shorter monomer shows a larger demolding force. Decreasing the cross-linking …
Large Eddy Simulation And Analysis Of Shear Flows In Complex Geometries, Prasad Mohanrao Kalghatgi
Large Eddy Simulation And Analysis Of Shear Flows In Complex Geometries, Prasad Mohanrao Kalghatgi
LSU Doctoral Dissertations
In the present work, large eddy simulation is used to numerically investigate two types of shear flows in complex geometries, (i) a novel momentum driven countercurrent shear flow in dump geometry and (ii) a film cooling flow (inclined jet in crossflow). Verification of subgrid scale model is done through comparisons with measurements for a turbulent flow over back step, present cases of counter current shear and film cooling flow. In the first part, a three dimensional stability analysis is conducted for countercurrent shear flow using Dynamic mode decomposition and spectral analysis. Kelvin-Helmholtz is identified as primary instability mechanism and observed …
Investigations Of The Effects Of Flame Configuration On The Combustion Of Laminar Diffusion Flame, Li Lu
Investigations Of The Effects Of Flame Configuration On The Combustion Of Laminar Diffusion Flame, Li Lu
LSU Doctoral Dissertations
Motivation and objective to study double inverse diffusion flame is introduced, followed by the literature survey on soot formation in inverse diffusion flame (IDF), application of the unique structure of double inverse diffusion flame (DIDF), radiation effects on DIDF, factors that affect the formation of nitric oxide and effects of elevated pressure on diffusion flames. Numerical method is validated by the result of flame height for IDF, which is consistent with result from previous research. In present work, two DIDF burner configurations with different size are used to conduct the simulation. Ethylene is used as the fuel. For each of …
Micro & Nano Scale Mechanical Testing And Assembly With Applications To Metal Based Microsystems, Ke Chen
Micro & Nano Scale Mechanical Testing And Assembly With Applications To Metal Based Microsystems, Ke Chen
LSU Doctoral Dissertations
Metal-based high-aspect-ratio microscale structures (HARMS) are fundamental building blocks for functional metallic micro devices. This dissertation focuses on addressing several problems in fabrication and assembly of metal based microchannel devices. First, the materials’ responses to mechanical deformation at micro & nano scales, namely the mechanical “size effect”, have been explored by molding single crystal Al with long rectangular diamond punches and long wedge shaped indenters. It is noticed that the contact pressure of rectangular punches pressed into single crystal Al strongly depends on the punch width, while that of long wedge shaped indenters depends on the included wedge angle. We …
Topology And Shape Optimization Of Hydrodynamically–Lubricated Bearings For Enhanced Load-Carrying Capacity, Mohammad Fesanghary
Topology And Shape Optimization Of Hydrodynamically–Lubricated Bearings For Enhanced Load-Carrying Capacity, Mohammad Fesanghary
LSU Doctoral Dissertations
Bearings are basic and essential components of nearly all machinery. They must be designed to work under different loads, speeds, and environments. Of all the performance parameters, load-carrying capacity (LCC) is often the most crucial design constraint. The objective of this research is to investigate different design methodologies that significantly improve the LCC of liquid-lubricated bearings. This goal can be achieved by either altering the surface texture or the bearing geometrical configuration. The methodology used here is based on mathematical topological/shape optimization algorithms. These methods can effectively improve the design performance while avoiding time-consuming trial-and-error design techniques. The first category …
Graph Rigidity-Based Formation Control Of Planar Multi-Agent Systems, Xiaoyu Cai
Graph Rigidity-Based Formation Control Of Planar Multi-Agent Systems, Xiaoyu Cai
LSU Doctoral Dissertations
A multi-agent system is a network of interacting "agents" that collectively perform a complex task. This dissertation is concerned with the decentralized formation control of multi-agent systems moving in the plane. The formation problem is defined as designing control inputs for the agents so that they form and maintain a pre-defined, planar geometric shape. The focus is on three related problems with increasing level of complexity: formation acquisition, formation maneuvering, and target interception. Three different "dynamic" models, also with increasing level of complexity, are considered for the motion of the agents: the single-integrator model, the double-integrator model, and the full …
Polymer-Based Fluidic Devices Integrated With Perforated Micro- And Nanopore Membrane For Study Of Ionic And Dna Transport, Junseo Choi
LSU Doctoral Dissertations
This study aims to develop a process, allowing a low-cost and high-throughput fabrication technique to produce freestanding polymer membranes having perforated micro- and nanopores, and also to design 3D micro/nanofluidic devices with the membrane, enabling a study of ions and DNA transport through nanopores. Technically, we have designed and fabricated high quality silicon stamp. Then, they have been used as molds for modified nanoimprint lithography that takes advantages of a sacrificial layer to obtain freestanding polymer membrane. This technique allows easy fabrication of large area, fully released polymer membranes containing perforated micro- and sub-micropores. The membrane with perforated micropores has …
Analysis And Optimization Of Film Cooling Effectiveness, Hessam Babaee
Analysis And Optimization Of Film Cooling Effectiveness, Hessam Babaee
LSU Doctoral Dissertations
In the first part, an optimization strategy is described that combines high-fidelity simu- lations with response surface construction, and is applied to pulsed film cooling for turbine blades. The response surface is constructed for the film cooling effectiveness as a function of duty cycle, in the range of DC between 0.05 and 1, and pulsation frequency St in the range of 0.2-2, using a pseudo-spectral projection method. The jet is fully modulated and the blowing ratio, when the jet is on, is 1.5 in all cases. Overall 73 direct numerical sim- ulations (DNS) using spectral element method were performed to …
Molecular Dynamics Simulation Studies Of Interaction Of Amphiphilic Molecules With Lipid Bilayers, Jieqiong Lin
Molecular Dynamics Simulation Studies Of Interaction Of Amphiphilic Molecules With Lipid Bilayers, Jieqiong Lin
LSU Doctoral Dissertations
We use molecular dynamics simulations to investigate the behavior of various amphiphilic molecules in aqueous solutions in the presence of vitamin E or lipid bilayers. Our research studies focus on two molecular systems. First, we investigate the effect of DMSO on structural properties of DMPC bilayers and calculate bilayers permeability coefficients for both water and DMSO molecules at low DMSO concentration. The simulations show that the increase of DMSO concentration in solution leads to an increase of the permeability of water through the bilayers. The permeability increase might explain the unusual ability of DMSO, even at relatively low concentrations, to …
Steady And Unsteady Thermo-Strucural Simulation Of Thermally Actuated Micro- And Nano-Structures, Elham Maghsoudi
Steady And Unsteady Thermo-Strucural Simulation Of Thermally Actuated Micro- And Nano-Structures, Elham Maghsoudi
LSU Doctoral Dissertations
This dissertation provides a thermo-structural simulation for nano-scale and micro-scale structures with pinned and fixed boundary conditions which are either thermally positioned, buckled, or actuated. The study begins with simulating a pinned-pinned beam in micro-scale and nano-scale. The steady state thermo-structural equation is solved numerically using an implicit Finite Difference method implemented in Matlab to obtain the thermal positioning response, which is the thermally steady state center displacement, by adding a constant, time-independent heat flux to the structure. The results show the steady state thermal displacement of the system is a function of the geometry, pressure, material properties, and constant …
Instability Analysis And Suppression Of Instability In Low-Density Gas Jets, Sukanta Bhattacharjee
Instability Analysis And Suppression Of Instability In Low-Density Gas Jets, Sukanta Bhattacharjee
LSU Master's Theses
A numerical study is conducted to understand the global instability of very low-density jets (as encountered in thermal plasmas). The simulations have been carried out for different parameters of density ratios, S = ƒÏj /ƒÏ‡ ranging from 0.5 to 0.03, different Reynolds numbers ranging from 500 to 4000 and different momentum thickness obtained by different extension tube length ranging from 3 to 6 diameter long. The flow parameters and vortex structures has been visualized to understand the details of the evolution of the flow field. The axisymmetric shear layer rolls up in the near field of the jet forming vortex …
Modeling, Numerical Analysis, And Predictions For The Detonation Of Multi-Component Energetic Solids, Michael Wayne Crochet
Modeling, Numerical Analysis, And Predictions For The Detonation Of Multi-Component Energetic Solids, Michael Wayne Crochet
LSU Doctoral Dissertations
Metal powders are often used as an additive to conventional high explosives to enhance the post-detonation blast wave. Piston-impact simulations are commonly utilized to predict performance metrics such as detonation speed and strength, as well as assessing the impact and shock sensitivity of these materials. The system response is strongly influenced by the initial particle size distribution and material composition. Multiphase continuum models have been routinely applied at the macroscale to characterize the detonation of solid high explosives over engineering length scales. Current models lack a description of the physically permissible constitutive relations for mass transfer due to general chemical …
3d Integration Of Micro- And Nanostructures Into Bio-Analytical Devices, Bahador Farshchian
3d Integration Of Micro- And Nanostructures Into Bio-Analytical Devices, Bahador Farshchian
LSU Doctoral Dissertations
This study aims to develop a process which allows 3D integration of micro and nanostructures in microchannels. A fabrication process was established for the large area integration of hierarchical micro and nanostructures in microchannels. This novel process, which is called 3D molding, takes advantage of an intermediate thin flexible stamp such as PDMS from soft lithography and a hard mold such as brass from hot embossing process. However, the use of a thin intermediate polydimethylsiloxane (PDMS) stamp inevitably causes dimensional changes in the 3D molded channel, with respect to those in the brass mold protrusion and the intermediate PDMS stamp …
Multiscale Analysis Of Contact In Smooth And Rough Surfaces: Contact Characteristics And Tribo-Damage, Ali Beheshti
Multiscale Analysis Of Contact In Smooth And Rough Surfaces: Contact Characteristics And Tribo-Damage, Ali Beheshti
LSU Doctoral Dissertations
This dissertation is comprised of two major interrelated foci. The first focus is to investigate the effect of surface roughness on the behavior of dry contacting bodies through both deterministic and statistical approaches. In the current research, different statistical micro-contact models are employed together with the bulk deformation of the bounding solids to predict the characteristics of the dry rough line-contact and elliptical point-contact including the apparent pressure profile, contact dimensions and real area of contact. Further, based on the results of numerical simulations, useful relationships are provided for the contact characteristics. In addition, a robust approach for the deterministic …
Effect Of Rest Time On Heart Rate, Perceived Exertion, And Strength, Amir Bahador Bahmani Bahman Beiglou
Effect Of Rest Time On Heart Rate, Perceived Exertion, And Strength, Amir Bahador Bahmani Bahman Beiglou
LSU Master's Theses
Finding a proper work/rest schedule is considered an important factor for improved efficiency, safety, and a higher rate of productivity in the workplace. The purpose of this study was to determine the optimum rest period for lifting tasks using heart rate, perceived exertion, and physical strength. First, the maximum acceptable weight of the box to be lifted was determined for each one of 10 participants using a psychophysical approach. Then on separate days, participants were required to repetitively lift the box from knuckle height to shoulder height for 20 minutes. They were then allowed to rest 5, 10, 15, or …
Liposomal Uptake Of Silver And Gold Nanoparticles, Dipon Chanda
Liposomal Uptake Of Silver And Gold Nanoparticles, Dipon Chanda
LSU Master's Theses
The main objective of this work is to study the liposomal uptake of silver and old nanoparticles. Liposomes were prepared in Heating Method. The phospholipids used to prepare liposomes are 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (16:0 PC); 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (16:0 PG); 1,2-distearoyl-sn-glycero-3-phosphocholine (18:0 PC); 1,2-distearoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (sodium salt) (18:0 PG).Four different combinations of phospholipids were used to prepare liposomes. In all four combinations two types of phospholipids were used. The liposomes were incubated for 30 minute, 1 hour, 2 hour and 4 hour with silver and gold nanoparticles in streptavidin coated glass slide. All four liposomal formulations had a biotinylated lipid (1-oleoyl-2-[12-biotinyl(aminododecanoyl)]-sn-glycero-3-phosphocholine) which has a string …
Electric Field Influence On The Combustion Of Fuel Droplets, Solomon Benghan
Electric Field Influence On The Combustion Of Fuel Droplets, Solomon Benghan
LSU Master's Theses
Improving the combustion efficiency of fuels in combustion devices has become imperative in the face of the diminishing rate of the discovery of new energy sources and an ever increasing demand for energy. While there are other ways of improving combustion efficiency, this study investigated the effect of electric field on the combustion of fuel droplets. In order to model the physics of the problem, a mass transfer evaporation model, heat transfer evaporation model and a simple burning droplet model were considered and their result compared to existing result from literature. A burning rate constant of 1.380mm2/s, 14.910mm2/s and 0.612mm2/s …