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Engineering Science and Materials

2015

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Articles 211 - 223 of 223

Full-Text Articles in Engineering

Defeating Anisotropy In Material Extrusion 3d Printing Via Materials Development, Ángel Ramón Torrado Pérez Jan 2015

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 …

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Influence Of Spatial Variations Of Railroad Track Stiffness And Material Inclusions On Fatigue Life, Celestin Nkundineza Jan 2015

Influence Of Spatial Variations Of Railroad Track Stiffness And Material Inclusions On Fatigue Life, Celestin Nkundineza

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Railroad transportation is very important for economic growth and effective maintenance is one critical factor for its economic sustainability. The high repetitive forces from a moving railcar induce cyclic stresses that lead to rail bending and potential deterioration due to fatigue crack initiation and propagation. Previous research for prediction of fatigue life has been done under the assumptions of a uniform track bed and a homogeneous rail. However the spatial variation of the track stiffness is expected to increase the maximum stresses in the rail and, therefore, accelerate the fatigue process. The research described in this dissertation is focused on …

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Risk-Based Wind Loss And Mitigation For Residential Wood Framed Construction, Fatemeh Orooji Jan 2015

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 …

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Effects Of Gravity On The Acceleration And Pair Statistics Of Inertial Particles In Homogeneous Isotropic Turbulence, H. Parishani, O. Ayala, B. Rosa, L.-P. Wang, W. W. Grabowski Jan 2015

Effects Of Gravity On The Acceleration And Pair Statistics Of Inertial Particles In Homogeneous Isotropic Turbulence, H. Parishani, O. Ayala, B. Rosa, L.-P. Wang, W. W. Grabowski

Engineering Technology Faculty Publications

Within the context of heavy particles suspended in a turbulent airflow, we study the effects of gravity on acceleration statistics and radial relative velocity (RRV) of inertial particles. The turbulent flow is simulated by direct numerical simulation (DNS) on a 2563 grid and the dynamics of O(106) inertial particles by the point-particle approach. For particles/droplets with radius from 10 to 60 µm, we found that the gravity plays an important role in particle acceleration statistics: (a) a peak value of particle acceleration variance appears in both the horizontal and vertical directions at a particle Stokes number …

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Context Aware Textual Entailment, Soha Arab-Khazaeli Jan 2015

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 …

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Release, Stability And Functionality Of Nanodelivered Hydrophobic (Lutein And Beta-Carotene) And Hydrophilic (Folic Acid) Antioxidants Using Zein Nanoparticles, Thanida Chuacharoen Jan 2015

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 …

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Interorganizational Collaboration And Systemic Change Framework For Building Information Modeling (Bim) Adoption, Rehema Joseph Monko Jan 2015

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 …

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Integrated Sustainability And Resiliency Assessment Methodology For The Design Of Single-Family Residential Structures Subject To Wind And Flood Hazards, Elizabeth Chisolm Matthews Jan 2015

Integrated Sustainability And Resiliency Assessment Methodology For The Design Of Single-Family Residential Structures Subject To Wind And Flood Hazards, Elizabeth Chisolm Matthews

LSU Doctoral Dissertations

Sustainability and resiliency have become important in shaping the criteria in performance-based design objectives in the recent past and will continue to shape future design as climate change impacts and disasters become more prevalent. While much work has been carried out in developing tools to aid in sustainable and resilient performance-based design there is still much work to be done. It is evident that while sustainability and resiliency have mutual advantages there are also inherent conflicts between the two design approaches. Some of the conflict relates to the robustness required of resilient design, which may have higher environmental impacts than …

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Thermo-Catalytic Upgrading Of Pyrolysis Vapors Using Electromagnetic Heating, Pranjali Devidas Muley Jan 2015

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 …

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Time-Resolved Investigations Of Continuous Flow Synthesis Of Nanomaterials And Catalysis Using Millifluidic Reactors For Biomass Conversion Reactors, Chelliah V Navin Jan 2015

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 …

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Constitutive Modeling And Experiments For The Micro And Nano Behaviors In Metals, Cheng Zhang Jan 2015

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 …

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Image-Based Modeling Of Porous Media Using Fem And Lagrangian Particle Tracking, Paula Cysneiros Sanematsu Jan 2015

Image-Based Modeling Of Porous Media Using Fem And Lagrangian Particle Tracking, Paula Cysneiros Sanematsu

LSU Doctoral Dissertations

The study of fundamental flow and transport processes at the pore scale is essential to understanding how the mechanisms affect larger, field-scale, processes that occur in oil and gas recovery, groundwater flow, contaminant transport, and CO2 sequestration. Pore-scale imaging and modeling is one of the techniques used to investigate these fundamental mechanisms. Although extensive development of pore-scale imaging and modeling has occurred recently, some areas still need further advances. In this work, we address two areas: (1) imaging of bulk proppants and proppant-filled fractures under varying loading stress and flow simulation in these systems and (2) nanoparticle (NP) transport modeling …

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Zespół Energii Odnawialnej I Zrównoważonego Rozwoju (Eozr), Wojciech M. Budzianowski Dec 2014

Zespół Energii Odnawialnej I Zrównoważonego Rozwoju (Eozr), Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.

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