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Articles 1 - 23 of 23
Full-Text Articles in Engineering
Numerical Implementation Of Prandtl’S Lifting-Line Theory And Modeling Of Aircraft Take-Off Phase For Wing Optimization, John William Dykes
Numerical Implementation Of Prandtl’S Lifting-Line Theory And Modeling Of Aircraft Take-Off Phase For Wing Optimization, John William Dykes
Honors Theses
No abstract provided.
State Feedback Control With Time Delay, Akshay Nareshraj Singh
State Feedback Control With Time Delay, Akshay Nareshraj Singh
LSU Doctoral Dissertations
In this thesis we start with an introduction to the theory of vibration control. We broadly classify the control methods into passive and active schemes. We introduce the problem of state feedback control and provide the classical solution in the form of Ackermann formula. We then identify the limitations of the classical approach and present the more elegant solution of partial pole assignment without spillover. We highlight the problem with model uncertainties and describe the method of pole assignment using data from measured receptances. This approach is extended for pole assignment for a linear vibrating system by using state feedback …
Large Eddy Simulation Of Turbulent Premixed Combustion In Gas Turbines, Ashoke De
Large Eddy Simulation Of Turbulent Premixed Combustion In Gas Turbines, Ashoke De
LSU Doctoral Dissertations
An artificially Thickened Flame (TF) approach based on LES framework is used to model the turbulent premixed combustion in gas turbine combustors. A number of variants of the Thickened Flame approach including a modified version of TF model have been studied in details. In the TF model, the flame front is artificially thickened to resolve on LES computational grid. With this approach, reaction rate modeling does not require any ad-hoc closure assumptions. However, suitable modifications have to be made to compensate for flame thickening. To verify the predictive capability of the models, a stoichiometric methane-air flame on Bunsen burner type …
Meso-Scale Heating Predictions For Weak Impact Of Granular Energetic Solids, Rohan Panchadhara
Meso-Scale Heating Predictions For Weak Impact Of Granular Energetic Solids, Rohan Panchadhara
LSU Doctoral Dissertations
An explicit, two-dimensional, Lagrangian finite and discrete element technique is formulated and used to computationally characterize meso-scale fluctuations in thermomechanical fields induced by low pressure deformation waves propagating through particulate energetic solids. Emphasis is placed on characterizing the relative importance of plastic and friction work as meso-scale heating mechanisms which may cause bulk ignition of these materials and their dependence on piston speed (vp ~ 50-500 m/s). The numerical technique combines conservation principles with a plane strain, thermoelastic-viscoplastic constitutive theory to describe deformation within the material meso-structure. An energy consistent, penalty based, distributed potential force method, coupled to a penalty …
Multiphase Flows In Polymer Microfluidic Systems, Namwon Kim
Multiphase Flows In Polymer Microfluidic Systems, Namwon Kim
LSU Doctoral Dissertations
Continuous delivery of segmented reagents using pressure-driven multiphase flow in microchannels is a promising technology for high throughput microfluidic bioassays. Separation and encapsulation of the target reagents with another inert fluid provide many advantages over single phase flow in microfluidic applications of biotechnology. In order to achieve these advantages and control these multiphase flows, it is necessary to understand their generation and transport characteristics as influenced by geometrical miniaturization, channel wall properties, the effects of surfactants and operating conditions. For gas-liquid two-phase flow, dry air and deionized water were driven into hot embossed PMMA microchannels with 200 μm square test …
A Modular Approach To High Throughput Microsystems, Pin-Chuan Chen
A Modular Approach To High Throughput Microsystems, Pin-Chuan Chen
LSU Doctoral Dissertations
A modular high throughput microsystem was developed using microfabrication technology and nucleic acid analysis. The purpose of developing this microsystem is to identify acute infectious disease and prevent contagious outbreak in a matter of time. This microsystem included three major components, a reagent distribution device, a 96 CFPCR array, and a multi-zone thermal system, to efficiently amplify specific DNA fragments to determine the disease status or precisely pinpoint a disease from multiple patients. Polymerase chain reaction (PCR) is the key component in the nucleic acid analysis for disease because it can be used to amplify interested DNA fragments by repeatedly …
A Multi-Function, Disposable, Microfluidic Module For Mutation Detection, Tae Yoon Lee
A Multi-Function, Disposable, Microfluidic Module For Mutation Detection, Tae Yoon Lee
LSU Doctoral Dissertations
Recognition of point mutations in a codon 12 of the K-ras gene, most frequently observed, is considered to be useful in the early diagnosis of several types of the human cancers. We have developed a multifunction, disposable, microfluidic module which detects low-abundant point mutations in human genomic DNA in modular architecture. Each functional component including a microfluidic PCR reactor, a passive diffusional micromixer reactor, and a microfluidic LDR reactor was separately designed and fabricated. Fluidic interconnects were also developed to make a fluidic passage between the functional components. Polycarbonate substrates were micro-molded, using hot embossing with micro-milled brass mold inserts …
Fabrication, Bonding, Assembly, And Testing Of Metal-Based Microchannel Devices, Fanghua Mei
Fabrication, Bonding, Assembly, And Testing Of Metal-Based Microchannel Devices, Fanghua Mei
LSU Doctoral Dissertations
Microsystem technologies are believed to be an important part of the contemporary technological foundation and are becoming a commercially significant specialty area in manufacturing. The design and fabrication of microscale engineering structures has the potential of generating revolutionary changes in many products over a wide range of industrial sectors. Metal-based microchannel heat exchangers (MHEs) promise high heat transfer coefficients together with mechanical robustness, and are of interest for a wide range of applications. Fabrication technologies capable of creating high-aspect-ratio microscale structures (HARMSs) in metals such as Cu at low cost and high throughput are of particular interest. Likewise, simple and …
Dynamics Of Vortical Structures In A Low-Blowing-Ratio Pulsed Transverse Jet, Clementine Vezier
Dynamics Of Vortical Structures In A Low-Blowing-Ratio Pulsed Transverse Jet, Clementine Vezier
LSU Master's Theses
Large Eddy Simulation is used to study the interaction of a 35° inclined jet into a crossflow. Steady state cases, with a BR ranging from 0.150 to 1.2, are firstly examined to understand the dynamics of the flow field. Iso-surface of Laplacian of the pressure, vorticity contour and velocity fields highlight the presence of four main vortical structures: shear layer vortices, horse-shoes vortices, wake vortices and CRVP. Qualitative comparisons are performed between simulations and experiments. The dynamics of the flow field is next characterized by pulsing the jet. The studied pulsed cases have same low BR and duty cycle respectively …
Numerical Investigation Of Film Cooling Fluid Flow And Heat Transfer Using Large Eddy Simulations, David Houston Leedom
Numerical Investigation Of Film Cooling Fluid Flow And Heat Transfer Using Large Eddy Simulations, David Houston Leedom
LSU Master's Theses
Large eddy simulations of film cooling from discrete holes inclined at 35° with a feeding plenum chamber are performed at a density ratio of 2 and blowing ratios from 0.5 to 2.0 in order to gauge the suitability and performance of different hole shapes. Cylindrical holes at length to diameter ratios of 1.75 and 3.5 as well as shaped holes (laterally diffused and console holes) at a length to diameter ratio of 3.5 are simulated issuing into a laminar crossflow at a Reynolds number of approximately 16,000 based on freestream velocity and hole diameter. The domain extends 15 hole diameters …
Self-Healing Of Fiber Reinforced Polymer Compoistes [Sic], Nebiyu Fikru
Self-Healing Of Fiber Reinforced Polymer Compoistes [Sic], Nebiyu Fikru
LSU Master's Theses
The study of self-healing materials is inspired by biological systems in which damage triggers an autonomous healing response. In recent years, this concept of autonomic healing material, where initiation of repair is integral to the material, is being considered for engineering applications. The concept offers the designer an ability to incorporate secondary functional ability of counteracting service degradation in addition to achieving the primary, usually structural integrity, requirement. Self-healing materials also have the benefit of offering lighter and optimized structures as well as reduced maintenance cost. Previous works on polymer matrix composites have shown that significant fractions of mechanical properties …
Aerodynamic And Heat Transfer Studies In A Combustor-Fired, Fixed-Vane Cascade With Film Cooling, James William Post
Aerodynamic And Heat Transfer Studies In A Combustor-Fired, Fixed-Vane Cascade With Film Cooling, James William Post
LSU Master's Theses
Pressure and heat transfer data has been generated in a high-pressure, high-temperature vane cascade. This cascade differs from many others seen in typical low-pressure facilities using room temperature air. Primarily, a natural gas-fired combustor generates realistic turbulence profiles in the high-temperature exhaust gases that pass through the vane cascade. The fixed-vane cascade test sections have film cooling holes machined into the surfaces in arrangements that closely model configurations seen in real-life first-row nozzle guide vanes (NGV). Theoretical coolant jet-to-crossflow blowing ratios (M) range from 0.5 to 3.0. Coolant jet-to-crossflow theoretical density ratios (DR) used for typical tests vary between 1.0 …
On The Effects Of Peripheral Sliding Velocity And Operating Differential Pressure In Rotary O-Ring Seals, Karan Lingerkar
On The Effects Of Peripheral Sliding Velocity And Operating Differential Pressure In Rotary O-Ring Seals, Karan Lingerkar
LSU Master's Theses
An O-ring seal is of paramount importance in hydraulic and pneumatic machinery used in oil and gas drilling processes. O-ring seals are generally employed to contain the environments of working fluids existing on either side of the seal from interacting with each other, to maintain a uniform pressure chamber and to eliminate the environmental contaminants that interact at the rubbing interface. Failure of dynamic O-rings in hydraulic and pneumatic machinery often results in considerable productivity loss to the chemical and petrochemical industries. Therefore, it is highly important to determine the life of an O-ring for these applications under various operating …
Thermal Characterization Of Plain And Carbon Nanotube Reinforced Syntactic Foams, Pratap Chandrashekhara Bhat
Thermal Characterization Of Plain And Carbon Nanotube Reinforced Syntactic Foams, Pratap Chandrashekhara Bhat
LSU Master's Theses
Syntactic foams are composite materials in which the matrix phase is reinforced with hollow particles called microballoons. They possess properties such as low moisture absorption, low thermal conductivity and high damage tolerance because of their compositions. Traditionally, syntactic foams are used for many high strength applications and as insulating materials. But for applications demanding better heat dissipation from syntactic foam, conductive filler materials need to be added while maintaining its property of low density. Carbon nanotubes although extremely conductive, have issues of agglomeration in the matrix. In this research, a new approach to the problem of dispersion of nanotubes was …
Effects Of Processing Parameters On The Embrittlement Of Self Reacting Friction Stir Welds, David Eric Taylor
Effects Of Processing Parameters On The Embrittlement Of Self Reacting Friction Stir Welds, David Eric Taylor
LSU Master's Theses
Friction Stir Welding (FSW) has been adopted as one of the major welding processes for joining Aluminum. Many aerospace and marine structures are welded through this novel FSW processes currently. The Lockheed Martin Space Systems (LMSS), Michoud Operations, in New Orleans is continuously pursuing Friction Stir Welding technologies in its efforts to advance fabrication of the external tanks of the space shuttle. Recently, a reduction in mechanical strength (embrittlement) has been observed especially in self-reacting (SR) friction stir welds. This strength reduction was attributed to Residual Oxide Defects (ROD) but the exact reasons for this type of behavior needed to …
Intracellular Ice Formation In Adult Stem Cells In The Presence Of Polyvinyl Pyrrolidone, Avishek Guha
Intracellular Ice Formation In Adult Stem Cells In The Presence Of Polyvinyl Pyrrolidone, Avishek Guha
LSU Master's Theses
The main objective of this work was to assess the effect of 10% (w/v) polyvinylpyrrolidone (PVP) on the pattern of intracellular ice formation (IIF) in human adipose tissue derived adult stem cells (ASCs) in the absence of serum and other cryoprotective agents (CPAs). Passage 1 (P1) ASCs were cultured, washed and suspended in either 1x PBS (Phosphate Buffered Saline) or 10% w/v solution of PVP in 1x PBS. The freezing experiments were carried out using a fluorescence microscope equipped with a Linkam™ cooling stage using two different temperature/time cooling protocols. Both the cooling protocols had a common cooling ramp: cells …
Functionally Gradient Syntactic Foams, Kanakaji Chittineni
Functionally Gradient Syntactic Foams, Kanakaji Chittineni
LSU Master's Theses
Syntactic foams are comprised of hollow microballoons in matrix systems. The superior mechanical and physical properties of syntactic foams such as light weight, high compressive strength, and low moisture absorption make them attractive materials for structural applications. As these materials are used in high mechanical performance applications, there is a need to achieve both high compressive strength and high energy absorption with minimal or no increase in density. In this study, the effect of gradient configuration of syntactic foams on the energy absorption and compressive strength is studied. Functionally Gradient Syntactic Foams (FGSFs) in five different layer sequencings are fabricated …
Atomistic Simulations Of Lipid Bilayers In The Presence Of Dimethylsulfoxide, Raghava Alapati
Atomistic Simulations Of Lipid Bilayers In The Presence Of Dimethylsulfoxide, Raghava Alapati
LSU Master's Theses
In a typical cryopreservation protocol, the system to be preserved is first equilibrated with chemicals known as cryoprotective agents (CPAs). CPAs have been shown to alleviate cell damage from either the solute effects or the formation of intracellular ice during the subsequent freezing process. Thus, an extensive body of literature reporting the effects of CPAs on cellular systems has been accumulated over the last 50 years; detailing largely experimental interactions between cell systems and chemicals. Recent advances in computational methodology now offer an additional dimension in our ability to understand the molecular interactions between cell membranes, idealized as lipid bilayers …
Experimental And Numerical Modeling Of Stresses In Non-Conventional Cross-Sectioned Composite Pipes, Prashanth Ramachandran
Experimental And Numerical Modeling Of Stresses In Non-Conventional Cross-Sectioned Composite Pipes, Prashanth Ramachandran
LSU Master's Theses
Composite materials have been widely used in the ship-building, aerospace and construction industries because of their distinct advantages of low weight, high stiffness, and high strength to weight ratios. These properties are due to the low weight of the epoxy core matrix and high strengths of the glass/carbon fibers. Composite pipes used in various applications are traditionally spherical in cross-section. In this study, non-conventional cross-sectioned composite pipes [i.e. rectangular and triangular cross-sections] have been proposed, fabricated, tested and analyzed because of their ability to be bundled without loss of space. The behaviors of these pipes under an internal pressure test …
Dynamical Investigation Of A Manned Capsule/Tether Re-Entry System, Jeffrey Alan Kornuta
Dynamical Investigation Of A Manned Capsule/Tether Re-Entry System, Jeffrey Alan Kornuta
LSU Master's Theses
The use of tethers in space has an exciting promise in future astronautical applications, with the possibility of providing more sophisticated functionality to satellites and spacecraft. Some of these applications include adjoining satellites, creating microgravity environments, generating power, and transferring momentum between spacecraft. The focus of this project is to investigate the possible reduction in convective heat flux and temperatures on a manned capsule as a result of re-entry with an attached momentum exchange tether, including how various tether parameters affect these results. Using a “bottom-up” approach by modeling the system as a series of lumped masses and rigid rods …
Fatigue Fracture And Microstructural Analysis Of Friction Stir Welded Butt Joints Of Aerospace Aluminum Alloys, Vinay Raghuram
Fatigue Fracture And Microstructural Analysis Of Friction Stir Welded Butt Joints Of Aerospace Aluminum Alloys, Vinay Raghuram
LSU Master's Theses
Friction-Stir-Welding (FSW) has been adopted as a major process for welding Aluminum aerospace structures. Al-2195, which is one of the new-generation Aluminum alloys that has been used on the external tank of the new super lightweight external tank of the space shuttle. The Lockheed Martin Space Systems (LMSS), Michoud Operations in New Orleans is continuously pursuing Friction-Stir-Welding technologies in its efforts to advance fabrication of the external tanks of the space shuttle. The future launch vehicles which will have to be reusable, m, an dates the structure to have good fatigue properties, which prompts an investigation into the fatigue behavior …
Thermomechanical Characterization Of A Shape Memory Polymer Based Syntactic Foam, Damon Nettles
Thermomechanical Characterization Of A Shape Memory Polymer Based Syntactic Foam, Damon Nettles
LSU Master's Theses
Shape memory polymers (SMPs) are a type of smart material capable of “remembering” multiple shapes and transitioning between them in response to an external stimulus. They offer the potential to self-seal macro-length scale damage in a nearly autonomous fashion. Syntactic foams are lightweight structural materials currently used in the marine and aerospace industries. This study seeks to bring syntactic foams and SMPs together, retaining characteristics of both components, to create a low-density smart composite. The SMP based syntactic foam is used as the core of a grid stiffened sandwich structure capable of healing impact damage multiple times. In order to …
A Self Healing Smart Syntactic Foam Based Grid Stiffened Sandwich Structure, Manu Kuruvila John
A Self Healing Smart Syntactic Foam Based Grid Stiffened Sandwich Structure, Manu Kuruvila John
LSU Doctoral Dissertations
Syntactic foams are composite materials synthesized by dispersing microballoons in a polymeric, ceramic or metallic matrix. In the past three decades, syntactic foams have gained immense importance as a lightweight and damage-tolerant material when used in foam-cored sandwich structures. Because of the structural-length scale damages by low velocity impact such as tool drops, runway debris etc., sandwich structures usually have a very low residual structural capacity. Unfortunately, macro-length scale damage, in particular internal damage such as impact damage, is very difficult to repair. Therefore, there is a genuine need to develop impact-tolerant and self-healing syntactic foams which can be used …