Engineering Science and Materials Commons^™

An Improved Sin-Hyperbolic Constitutive Model For Creep Deformation And Damage, Mohammad Shafinul Haque

Open Access Theses & Dissertations

Inspection and maintenance of industrial gas turbines (IGTs) cost millions of dollars. Growing demand of obtaining higher IGT efficiency leads to higher temperature and pressure operating conditions. Long exposure of turbine components at elevated temperature and pressure

makes creep damage critically important to consider during planning, designing and operating conditions. Effective and economic maintenance requires accurate creep deformation, damage

evolution and rupture life prediction information. Creep prediction models are used to determine the state of the turbine components and to schedule the inspection, maintenance and replacement time periods. The more accurate the prediction model, the less is the overall cost …

Transition Metal Carbide (Tmc) Novel Materials For Novel Catalytic Applications, Svetlana Lagoykina

Open Access Theses & Dissertations

Transition metal carbides (TMC) constitute a diverse class of materials and traditionally have many technological applications. TMC became a subject of extensive research since 1973, when their platinum -like properties were discovered. They demonstrated high catalytical activity and selectivity in a variety of chemical reaction and have potential for some novel catalytic application.

This research is an effort to design new high effective, selective and stable bimetal or alkali promoted TMC catalyst. After extensive theoretical research a wide range of TMC, including bimetal and alkali promoted carbides, were synthesized by different methods. All solids were characterized by XRD and microscopy. …

Reaction Of Liquid Aluminium- Samarium Alloys With B4c At Ultra High Temperatures, Sanjay Shantha-Kumar

Open Access Theses & Dissertations

Reactive studies between a packed bed of B4C and Al-Sm-Me (Me = Ti, Zr, Hf) alloy melts were carried out under a pseudo-isopiestic thermodynamic system. A graphite enclosure isolated the system under a temperature gradient with one end reaching temperatures greater than 1800 K and the opposite end of the graphite enclosure contains liquid Al with temperatures approximating 950 K. The liquid Al establishes an oxygen potential to control oxidation of very reactive elements (i.e., Al, Sm and Ti). The Al-Sm-Me alloy infuses into a packed bed of B4C reacting exothermically to form borides and carbides depending on the thermodynamic …

Hybrid Nano-Structure For Enhanced Energy Storage Devices, Mohammad Arif Ishtiaque Shuvo

Open Access Theses & Dissertations

The goal of this research is to develop electrode materials using various nano-structure hybrids for improved energy storage devices. Enhancing the performance of energy storage device has been gaining tremendous attention since it holds the key solution to advance renewable energy usage thus reduce the consumption of fossil fuels. The application of energy storage devices such as super-capacitor and Li-ion-battery has seen significant growth; however, it is still limited mainly by charge/discharge rate and energy density. One of the solutions is to use nano-structure materials, which offer higher power at high energy density and improved stability during the charge discharge …

High Temperature Oxidation Of Nb-Cr-Mo-Si-B Alloys, Kathryn S. Thomas

Open Access Theses & Dissertations

It has been the trend to use nickel based superalloys in high temperature applications, however higher temperatures are required in the effort to enhance the efficiency of such components as jet turbine engines. The melting temperature of the nickel based superalloy limits the extent to which temperature can be raised as these materials are typically used at temperatures within 200 degrees of their melting point. Refractory metal based systems are attractive due to their high melting points, low densities, and good high temperature strength. However, in such cases as niobium, poor oxidation resistance limits the widespread use of such alloys. …

Defeating Anisotropy In Material Extrusion 3d Printing Via Materials Development, Ángel Ramón Torrado Pérez

Open Access Theses & Dissertations

Additive Manufacturing technologies has been in continuous development for more than 35 years. Specifically, the later denominated Material Extrusion Additive Manufacturing (MEAM), was first developed by S. Scott Crump around 1988 and trademarked later as Fused Deposition Modeling (FDM). Although all of these technologies have been around for a while, it was not until recently that they have been more accessible to everyone. Today, the market of 3D printers covers all ranges of price, from very specialized, heavy and expensive machines, to desktop printers of only a few cubic inches in volume. Until recently, FDM technology had remained somewhat stagnant …

A Study To Evaluate Non-Uniform Phase Maps In Shape Memory Alloys Using Finite Element Method, Naren Motte

Theses and Dissertations

The unique thermo-mechanical behavior of Shape Memory Alloys (SMAs), such as their ability to recover the original shape upon heating or being able to tolerate large deformations without undergoing plastic transformations, makes them a good choice for actuators.

This work studies their application in the aerospace and defense industries where SMA components can serve as release mechanisms for gates of enclosures that have to be deployed remotely. This work provides a novel approach in evaluating the stress and heat induced change of phase in a SMA, in terms of the transformation strain tensor. In particular, the FEA tool

ANSYS has …

Interorganizational Collaboration And Systemic Change Framework For Building Information Modeling (Bim) Adoption, Rehema Joseph Monko

LSU Doctoral Dissertations

It was found that an integrated framework needs to be developed for the construction industry that allows optimized interorganizational collaboration and systemic change while using Building Information Modeling (BIM) technologies. The framework needs to be effective so the industry can adopt BIM through a set of interdependent activities beyond their organizational boundaries. The adoption has been proven difficult because of industry competitiveness and a fragmented work environment. Meanwhile, existing frameworks vary between studies. This research developed an integrated framework, identified critical factors, and provided an evaluation guide for interorganizational collaboration and set of coordinated changes necessary to adopt BIM. This …

Product Parameters Optimization For Double Purge Of C-Magma Integrated With Conventional Three-Boiling Crystallization Scheme To Improve Raw Sugar Whole Color, Luz Stella Polanco

LSU Doctoral Dissertations

Efficient crystallization in raw sugar production is the result of a combination of factors and responses that meet specific criteria. Matching a sugar quality standard, maximizing sugar yield, maximizing crystallization equipment capacity and minimizing heat requirement are all necessary optimization criteria. A double centrifugation or purge of C-magma is intended to improve raw sugar whole color by the reduction of color recirculation with the sugar crystal. Combining a three boiling crystallization scheme with a second centrifugation after the last crystallization stage required optimizing the input/output product parameters (purities) and the location of the liquid recycle component (double purge molasses) for …

Risk-Based Wind Loss And Mitigation For Residential Wood Framed Construction, Fatemeh Orooji

LSU Doctoral Dissertations

As a result of increasing windstorm losses in the United States over the past 50 years, a variety of residential wind hazard mitigation methods have been suggested. Mitigation undoubtedly reduces windstorm losses; however, the expected economic risk reduction of mitigation practices over the life of the building depends on the building characteristics (i.e., capacity) and the intensity and occurrence of wind speeds (i.e., demand). Effective decision making requires estimation of potential future losses based on many variables. Many models, primarily mechanics-based simulation models, have been developed to predict building damage from wind events; however; fewer models of economic loss have …

Constitutive Modeling And Experiments For The Micro And Nano Behaviors In Metals, Cheng Zhang

LSU Doctoral Dissertations

This work addresses the micro- and nano-behaviors in metals through constitutive modeling and experiments. The size effect encountered during nanoindentation experiments, which is known as indentation size effect (ISE), is investigated for metal materials. The ISE is believed to be related with the strain gradient at small indentation depths. Geometrically necessary dislocations (GNDs) are formed in order to accommodate the strain gradient, which results in the increase in the material hardness. The grain boundaries in polycrystalline materials play an important role on the material hardness during nanoindentation experiments as there is a soften-hardening segment in the curve of hardness as …

Time-Resolved Investigations Of Continuous Flow Synthesis Of Nanomaterials And Catalysis Using Millifluidic Reactors For Biomass Conversion Reactors, Chelliah V Navin

LSU Doctoral Dissertations

Millifluidics can be used as a simple tool and convenient platform to perform in-situ investigations on nanoparticles synthesis to generate real-time information in a continuous flow fashion. These investigations can be used to observe the relationship between the structure and performance of nanoparticles for catalytic applications as a function of space and time. These improvements in nanoparticles research offer unique advantages to develop catalysts with molecular strategies. In order to showcase these advantages of the millifluidic reactors, here we: A. Extensively covered a complete literature review on Lab-on-a-chip devices for gold nanoparticle synthesis and as a catalyst support for continuous …

Context Aware Textual Entailment, Soha Arab-Khazaeli

LSU Doctoral Dissertations

In conversations, stories, news reporting, and other forms of natural language, understanding requires participants to make assumptions (hypothesis) based on background knowledge, a process called entailment. These assumptions may then be supported, contradicted, or refined as a conversation or story progresses and additional facts become known and context changes. It is often the case that we do not know an aspect of the story with certainty but rather believe it to be the case; i.e., what we know is associated with uncertainty or ambiguity. In this research a method has been developed to identify different contexts of the input raw …

Developing Co-Current And Counter-Current Spray Drying Computational Fluid Dynamics (Cfd) Simulation Studies To Predict The Quality Of Microencapsulated Fish Oil With Egg White Hydrolysates Powders, Kevin Estuardo Mis Solval

LSU Doctoral Dissertations

Eggs are an excellent source of high quality protein containing all essential amino acids (EAA) including leucine. Food-grade protein hydrolysates can enhance the growth of lactic acid bacteria (LAB). Thermal degradation of bioactives normally occurs during microencapsulation by spray drying. Spray drying modeling using computational tools is essential to engineer new food powders and to minimize and thermal degradation of bioactives. The first chapter of this work discusses the optimization of an enzymatic process in terms of reaction temperature, pH, enzyme:substrate ratio, and reaction time using a response surface methodology (RSM) to produce food-grade protein hydrolysates from egg whites (EWH). …

Release, Stability And Functionality Of Nanodelivered Hydrophobic (Lutein And Beta-Carotene) And Hydrophilic (Folic Acid) Antioxidants Using Zein Nanoparticles, Thanida Chuacharoen

LSU Doctoral Dissertations

Nanodelivery systems enable innovations that can benefit foods and human health on a large scale in the coming years. The instabilities of antioxidants during food processing and during digestion are drawbacks that can be successfully addressed by nanoentrapment. This research provided technical strategies to synthesize zein nanoparticles loaded with hydrophobic/hydrophilic antioxidants, and to study the release profiles and physical stability of nanocarriers and chemical stability of entrapped bioactives under on-shelf and GI conditions. The results supported the potential of zein nanoparticles stabilized by surfactants to improve chemical stability of entrapped lutein, and to slowly release lutein under PBS conditions. Same …

Optimal Location Of Biomethane Gas Manufacturing Plants And Allocation Of Feedstock And Liquified Carbon Product, Bingqing Wu

LSU Doctoral Dissertations

Biomethane gas (BMG), known for its sustainability, low environmental impact, and high profitability, has received wide attention in recent years. To facilitate the process of making strategic plans for building a BMG production system, this dissertation leverages the mathematical modeling and optimization techniques to minimize the supply chain cost for such a system. Typical elements in a BMG production system consist of the local farms that produce the feedstock, the hubs that collect and store the feedstock produced by farms, the reactors that generate BMG from the feedstock transported from the hubs, the condensers that liquefy the BMG from the …

Thermo-Catalytic Upgrading Of Pyrolysis Vapors Using Electromagnetic Heating, Pranjali Devidas Muley

LSU Doctoral Dissertations

Electromagnetic heating offers several advantages such as rapid heating rates, accurate temperature control and energy efficiency over conventional reactors. The goal of this study was to design an effective and energy efficient catalytic reactor for pyrolysis vapor upgrading. An induction based catalytic reactor was designed for upgrading of pyrolysis vapors. The effect of catalyst bed temperatures (290°, 330° and 370°C) and biomass to catalyst ratios of 1, 1.5 and 2 was studied. The results were compared to conventional heating reactor. Induction heating reactor performance exceeded that of conventional heater. The biomass to catalyst ratio of 2 in combination with the …

Thiol-Ene Scaffolds As Synthetic Augments And Silicate Ceramics As Osteogenic Components For Bone Tissue Engineering Applications, Cong Chen

LSU Doctoral Dissertations

Bone tissue engineering approaches using polymer/ceramic composites show promise as effective biocompatible, absorbable, and osteoinductive materials. A novel class of in situ polymerizing thiol-acrylate based copolymers synthesized via an amine-catalyzed Michael addition was studied for its potential to be used in bone defect repair. Both pentaerythritol triacrylate-co-trimethylolpropane tris(3-mercaptopropionate) (PETA-co-TMPTMP) and PETA-co-TMPTMP with hydroxyapatite composites were fabricated in solid cast and foamed forms. These materials were characterized chemically and mechanically followed by an in vitro evaluation of the biocompatibility and chemical stability in conjunction with human adipose-derived mesenchymal pluripotent stem cells (hASC). The solid PETA-co-TMPTMP with and without hydroxyapatite (HA) exhibited …

Development And Preliminary Evaluation Of A Spray Deposition Sensing System For Improving Pesticide Application, Melissa A. Kesterson, Joe D. Luck, Michael P. Sama

Department of Mechanical and Materials Engineering: Faculty Publications

An electronic, resistance-based sensor array and data acquisition system was developed to measure spray deposition from hydraulic nozzles. The sensor surface consisted of several parallel tin plated copper traces of varying widths with varying gap widths. The system contained an embedded microprocessor to monitor output voltage corresponding to spray deposition every second. In addition, a wireless module was used to transmit the voltage values to a remote laptop. Tests were conducted in two stages to evaluate the performance of the sensor array in an attempt to quantify the spray deposition. Initial tests utilized manual droplet placement on the sensor surface …

Inducing Persistent Flow Disturbances Accelerates Atherogenesis And Promotes Thin Cap Fibroatheroma Development In D374y-Pcsk9 Hypercholesterolemic Minipigs, Ryan M. Pedrigi, Christian Bo Poulsen, Vikram V. Mehta, Niels Ramsing Holm, Nilesh Pareek, Anouk L. Post, Ismail Dogu Kilic, Winston A.S. Banya, Gianni Dall'ara, Alessio Mattesini, Martin M. Bjorklund, Niels P. Andersen, Anna K. Grondal, Enrico Petretto, Nicolas Foin, Justin E. Davies, Carlo Di Mario, Jacob Fog Bentzon, Hans Erik Botker, Erling Falk, Rob Krams, Ranil De Silva

Department of Mechanical and Materials Engineering: Faculty Publications

Background—Although disturbed flow is thought to play a central role in the development of advanced coronary atherosclerotic plaques, no causal relationship has been established. We evaluated whether inducing disturbed flow would cause the development of advanced coronary plaques, including thin cap fibroatheroma (TCFA).

Methods and Results—D374Y-PCSK9 hypercholesterolemic minipigs (N=5) were instrumented with an intracoronary shear-modifying stent (SMS). Frequency-domain optical coherence tomography was obtained at baseline, immediately post-stent, 19, and 34 weeks and used to compute shear stress metrics of disturbed flow. At 34 weeks, plaque type was assessed within serially-collected histological sections and co-registered to …