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2010

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Articles 121 - 134 of 134

Full-Text Articles in Engineering Science and Materials

Hybrid Manufacturing: Integrating Stereolithography And Direct Print Technologies, Amit Lopes Jan 2010

Hybrid Manufacturing: Integrating Stereolithography And Direct Print Technologies, Amit Lopes

Open Access Theses & Dissertations

The focus of this research was the development of a hybrid manufacturing system that integrates stereolithography (SL) and direct print (DP) technologies to fabricate three dimensional (3D) structural electronic devices within a single set-up. The capabilities of this new additive manufacturing (AM) technology was explored in the context of fabricating and prototyping complex electronic devices in which conformal shape, rugged and light-weight integration, and a natural resistance to reverse engineering are all of paramount importance. Consequently, electronic components can be tightly integrated together in a rugged, light-weight 3D structure of arbitrary form. This research is a continuing advancement of the …

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Surface Modification Of Carbon Structures For Biological Applications, Elizabeth Irene Maurer Jan 2010

Surface Modification Of Carbon Structures For Biological Applications, Elizabeth Irene Maurer

Browse all Theses and Dissertations

Carbon substrates have a wide variety of applications, many of which are enabled by appropriate surface modifications. In particular, the use of carbon-based substrates for biological devices can be quite advantageous due to their relative inertness and biocompatibility. Moreover, graphitic carbon can take many forms ranging from flat sheets to foams, fibers, and nanotubes. In this project, larger carbon substrates such as microcellular foam and flat graphite have been modified with carbon nanotubes, and their potential use in two types of biological applications was tested. The first study involved an investigation of the growth and proliferation of osteoblast cells on …

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A Critical Assessment Of The High Cycle Bending Fatigue Behavior Of Boron-Modified Ti-6al-4v, Casey M. Holycross Jan 2010

A Critical Assessment Of The High Cycle Bending Fatigue Behavior Of Boron-Modified Ti-6al-4v, Casey M. Holycross

Browse all Theses and Dissertations

Boron-modified Ti-6Al-4V alloys have shown increased performance in mechanical properties over unmodified alloys and are currently of interest for use in turbine engine applications. These alloys offer up to 40% increase in ultimate tensile strength, up to 30% increase in stiffness, and favorable damage characteristics while maintaining a ductility greater than 10%. These attractive properties are attributed to small additions of boron that refine the microstructure and form strong and stiff TiB whiskers. Previous research has found that these modified alloys compare favorably in fatigue. Samples machined from a powder-metallurgy forging with nominal composition Ti-6Al-4V-1B, were tested in fully-reversed bending …

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Fabrication And Analysis Of Compositionally Graded Functional Layers For Solid Oxide Fuel Cells, Jared Ray Mccoppin Jan 2010

Fabrication And Analysis Of Compositionally Graded Functional Layers For Solid Oxide Fuel Cells, Jared Ray Mccoppin

Browse all Theses and Dissertations

Solid Oxide Fuel Cell (SOFC) structures must be optimized for high performance, increased life, and low cost. Fabrication methods are an area of research interest in bringing down the total cost of SOFCs, and can also impact cell life and performance. Graded functional layers have been shown to enhance cell performance, but current fabrication methods require multiple fabrication steps. This thesis describes a novel fabrication method capable of compositional gradation of functional layers for SOFCs. Using colloidal spray deposition technology, a controlled co-deposition strategy was utilized to fabricate SOFC's with compositionally graded cathode and anode functional layers (CGCFL/CGAFL). In this …

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Studies Of Dynamic Crack Propagation And Crack Branching With Peridynamics, Youn Doh Ha, Florin Bobaru Jan 2010

Studies Of Dynamic Crack Propagation And Crack Branching With Peridynamics, Youn Doh Ha, Florin Bobaru

Department of Engineering Mechanics: Faculty Publications

In this paper we discuss the peridynamic analysis of dynamic crack branching in brittle materials and show results of convergence studies under uniform grid refinement (m-convergence) and under decreasing the peridynamic horizon (δ-convergence). Comparisons with experimentally obtained values are made for the crack-tip propagation speed with three different peridynamic horizons.We also analyze the influence of the particular shape of themicro-modulus function and of different materials (Duran 50 glass and soda-lime glass) on the crack propagation behavior. We show that the peridynamic solution for this problem captures all the main features, observed experimentally, of dynamic crack propagation and branching, as well …

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A Study Of Demoulding Force Prediction Applied To Periodic Mould Surface Profiles, Kevin Delaney, Giuliano Bissacco, David Kennedy Jan 2010

A Study Of Demoulding Force Prediction Applied To Periodic Mould Surface Profiles, Kevin Delaney, Giuliano Bissacco, David Kennedy

Conference Papers

Demoulding components without damage to either the components or tool is critical to successful replication processes. Accurate demoulding force prediction prior to tool fabrication helps designers optimize replication tools to minimize the demoulding force and resultant stress on replicated parts. Various models have been proposed to predict demoulding forces. One such model, the stair-step model, was developed by Colton et al for stereolithographic moulding tools. This paper investigates applying the model to other periodic surfaces with validation using published experimental data. In addition validity of the model for application to micro mould surfaces produced by micro milling is discussed.

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Temporal Scales For Transport Patterns In The Gulf Of Finland, Bert Viikmae, Tarmo Soomere, Mikk Viidebaum, Mihhail Berezovski Jan 2010

Temporal Scales For Transport Patterns In The Gulf Of Finland, Bert Viikmae, Tarmo Soomere, Mikk Viidebaum, Mihhail Berezovski

Publications

The basic time scales for current-induced net transport of surface water and associated time scales of reaching the nearshore in the Gulf of Finland, the Baltic Sea, are analysed based on Lagrangian trajectories of water particles reconstructed from three-dimensional velocity fields by the Rossby Centre circulation model for 1987–1991. The number of particles reaching the nearshore exhibits substantial temporal variability whereas the rate of leaving the gulf is almost steady. It is recommended to use an about 3 grid cells wide nearshore area as a substitute to the coastal zone and about 10–15 day long trajectories for calculations of the …

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Waves In Materials With Microstructure: Numerical Simulation, Mihhail Berezovski, Arkadi Berezovski, Juri Engelbrecht Jan 2010

Waves In Materials With Microstructure: Numerical Simulation, Mihhail Berezovski, Arkadi Berezovski, Juri Engelbrecht

Publications

Results of numerical experiments are presented in order to compare direct numerical calculations of wave propagation in a laminate with prescribed properties and corresponding results obtained for an effective medium with the microstructure modelling. These numerical experiments allowed us to analyse the advantages and weaknesses of the microstructure model.

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Effects Of Bondline Thickness On Nonlinear Interfacial Fracture Of Bonded Adhesive Joint, Gefu Ji Jan 2010

Effects Of Bondline Thickness On Nonlinear Interfacial Fracture Of Bonded Adhesive Joint, Gefu Ji

LSU Doctoral Dissertations

A number of existing and emerging industrial applications are dependent on layered substrates through adhesive bonding. The interfacial fracture of adhesively bonded structures is a critical issue for its extensive applications to a variety of modern industries. In the recent two decades, cohesive zone models (CZMs) have been receiving intensive attentions for fracture problems of adhesively bonded joints due to its fairly simple and accurate predictive ability. In CZMs the nonlinear interfacial fracture behaviors are described by the traction-separation laws (also referred to as cohesive laws). The cohesive laws represent the local constitutive behavior, instead of the global parameter, such …

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Dynamic Model Of Ecological Factors Impacting The Gulf Of Mexico Dead Zone, Jimmie Arnold Brumfield Ii Jan 2010

Dynamic Model Of Ecological Factors Impacting The Gulf Of Mexico Dead Zone, Jimmie Arnold Brumfield Ii

LSU Doctoral Dissertations

The industrial agriculture complex of the Mississippi River Drainage Basin has the positive effect of feeding more individuals with less land via the use of chemical nutrients, pesticides and drainage. The negative effects of the agricultural nutrient load are carried by the Mississippi River to the Gulf of Mexico. After the flood of 1927 the Flood Control Act of 1928 began changing the Mississippi River into a navigation and flood control project. While successful, the river was turned into a channel where nutrient input was discharged into the Gulf of Mexico. Nitrogen compounds discharged from the Mississippi are claimed to …

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Value-Added Processing Of Rice And Rice By-Products, Rebecca C. Schramm Jan 2010

Value-Added Processing Of Rice And Rice By-Products, Rebecca C. Schramm

LSU Doctoral Dissertations

World competition has encouraged United States rice farmers and rice mills to be efficient in farming and production practices. Efforts to augment economic competitiveness include development of new varieties, improvements in milling practices, and identification of uses for rice products and by-products. The research detailed in this dissertation adds to the body of knowledge in milling practices and identification of uses for rice bran. To improve the prediction of milled rice quality at industrial scale, correlations for milling quality among laboratory, pilot, and industrial scale mills were identified for Clearfield 161. Final industrial product whiteness was ten points higher than …

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Antioxidant Nanoparticles As Delivery Systems, Carlos Ernesto Astete R. Jan 2010

Antioxidant Nanoparticles As Delivery Systems, Carlos Ernesto Astete R.

LSU Doctoral Dissertations

The goal of the study was to develop antioxidant polymeric nanoparticles as a new delivery system for food and pharmaceutical applications. Natural antioxidants like alpha-tocopherol, vitamin C, and carnosine, are responsible to protect biological systems against free radicals attack. The conjugation of vitamin C-vitamin E (EC) and alpha-tocopherol-carnosine (VECAR) were performed to obtain antioxidant surfactants which were used for polymeric nanoparticle synthesis. The surfactant made of á-tocopherol (vitamin E) and ascorbic acid (vitamin C) of antioxidant properties dubbed as EC was used to make poly(lactic-co-glycolic) acid (PLGA) nanoparticles. Self-assembled EC nanostructures and PLGA-EC nanoparticles were made by nanoprecipitation, and the …

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Lattice Boltzmann Modeling For Shallow Water Equations Using High Performance Computing, Kevin Tubbs Jan 2010

Lattice Boltzmann Modeling For Shallow Water Equations Using High Performance Computing, Kevin Tubbs

LSU Doctoral Dissertations

The aim of this dissertation project is to extend the standard Lattice Boltzmann method (LBM) for shallow water flows in order to deal with three dimensional flow fields. The shallow water and mass transport equations have wide applications in ocean, coastal, and hydraulic engineering, which can benefit from the advantages of the LBM. The LBM has recently become an attractive numerical method to solve various fluid dynamics phenomena; however, it has not been extensively applied to modeling shallow water flow and mass transport. Only a few works can be found on improving the LBM for mass transport in shallow water …

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Experimental And Numerical Analysis Of Fuel Cells, Abul Bashar Mahmud Hasan Jan 2010

Experimental And Numerical Analysis Of Fuel Cells, Abul Bashar Mahmud Hasan

LSU Doctoral Dissertations

Fuel Cells are attractive power source for use in electronic applications. Physical phenomena (water generation, saturation effect in fuel cell, poisoning, and thermal stress) are studied that governs the operation of a Proton Exchange Membrane Fuel Cell (PEMFC) and Solid Oxide Fuel cell (SOFC). Additionally, experimental studies and numerical simulations on PEMFC gas flow channel, the determination of the impact of the single channel fuel cell are presented. Furthermore, preliminary study is done for the application of APS (Air Plasma Spray) to SOFC and adhesion of anode and cathode with electrolytes for the determination of parameters involved in manufacturing the …

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