17 research outputs found

    A Visualization Tool for Foam Research

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    Aluminium foams and their applications in engineering practice

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    Bakalárska práca zahrňuje poznatky o hliníkových penách a ich praktickom využití. V prvej časti je práca zameraná na základnú charakteristiku hliníka a jeho zliatin a následne sú charakterizované kovové peny a uvedené ich základné rozdelenie. Ďalej je venovaná značná pozornosť vybraným spôsobom ich výroby. Taktiež sú uvedené vlastnosti takýchto pien, a to predovšetkým tie najpodstatnejšie – mechanické. Práca pojednáva aj o technologickom spracovaní pien a posledná časť obsahuje popis vybraných aplikácií kovových pien v technickej praxi.Bachelor thesis includes knowledge of aluminum foams and their practical use. The first part of the thesis is focused on the basic characteristics of aluminum and its alloys, consequently, there are characterized metal foams and stated their basic division. Further, there is also devoted considerable attention to selected methods of its manufacturing. Also, properties of these foams are mentioned, mainly the most important ones – mechanical. Thesis deals even about technological processing of foams and the last part contains description of selected applications of metal foams in technical practice.

    Manufacturing and Properties of Cast Metallic Foams with Regular Structure

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    Diplomová práce je zaměřena na kovové pěny, které se díky svým vlastnostem stále více využívají v různých průmyslových oborech. Kovové pěny jsou materiály, které mají ve své struktuře úmyslně vytvořené póry, které jim dodávají zcela výjimečné vlastnosti. Teoretická část práce popisuje charakteristické vlastnosti, jednotlivé slévárenské možnosti výroby, oblasti a užití těchto kovových pěn v průmyslu. V experimentální části práce se provádí ověření a realizace zvolené metody Lost Foam k výrobě kovových pěn s pravidelnou buněčnou strukturou v provozních laboratořích školy.The diploma thesis is focused on metal foams that are due to their properties are increasingly used in various industrial fields. Metallic foams are materials that have intentionally created pores in their structure, that give them extraordinary characteristics. The theoretical part describes characteristic features, individual foundry production possibilities, areas and use of these metal foams in industry. In the experimental part of the work is performed verification and implementation of the chosen method is carried out lost foam to produce metal foams with regular cellular structure in the operating laboratories of the school.618 - Katedra metalurgie a slévárenstvívelmi dobř

    Visualization of time-dependent foam simulation data.

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    Research in the field of complex fluids such as polymer solutions, particulate suspensions and foams studies how the flow of fluids with different material parameters changes as a result of various constraints. Surface Evolver, the standard solver software used to generate foam simulations, provides large, complex, time-dependent data sets with hundreds or thousands of individual bubbles and thousands of time steps. However this software has limited visualization capabilities, and no foam specific visualization software exists. We describe the foam research application area where, we believe, visualization has an important role to play. We present a novel application, called Foam Vis, that provides various techniques for visualization, exploration and analysis of foam simulation data. Foam Vis can visualize individual time steps or produce time-dependent visualizations. It can process a simulation or it can facilitate comparison of several related simulations. We show new features in foam simulation data and new insights into foam behavior discovered using our application. Based on the many research questions that domain experts are able to address, we believe we provide a valuable tool for visualization and analysis of data in the foam research community

    Probability of breaking waves in random seas

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    SIGLEAvailable from British Library Document Supply Centre- DSC:D94941 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

    Investigating enteroaggregative Escherichia coli virulence factors in human intestinal infection

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    Enteroaggregative Escherichia coli (EAEC) are a major cause of diarrhoeal illness in children, travellers, and the immunocompromised, and associated with foodborne outbreaks worldwide. However, EAEC is a heterogeneous pathotype with frequent asymptomatic carriage and a diversity of virulence factors. Previous studies have been unsuccessful in identifying genetic virulence markers. In this study, two complimentary approaches were applied using intestinal infection models to investigate bacterial factors contributing to EAEC pathogenesis in the human gut. Firstly, the influence of intestinal environmental signals on the expression of putative EAEC virulence genes was evaluated using a vertical diffusion chamber (VDC). Aerobic oxygen levels increased expression of the adhesins aggregative adherence fimbriae II (AAF/II) and E. coli common pilus, the colonisation factor dispersin, and the global transcriptional activator AggR in prototype strain 042. Furthermore, adherence to polarised T84 intestinal epithelial cells significantly enhanced the expression of adherence factors (AAFs and dispersin), toxins (HlyE, EAST-1, Pet) and the Pic mucinase. This induction required host cell binding and was independent of AggR regulation. Based on these findings, it is proposed that EAEC adherence factors are induced by proximity to the oxygen diffusion gradient across the gut epithelium, while epithelial cell contact activates expression of further virulence factors. As an alternative approach to identify EAEC pathogenicity markers, virulence-associated phenotypes and genotypic profiles were determined for EAEC sequence types associated with disease (ST40) or carriage (ST31). ST40 isolates exhibited significantly higher biofilm formation and adherence to T84 cells and human colonic biopsies. The genotype comparison identified differences in virulence genes associated with epithelial colonisation and induction of host inflammatory responses between both sequence types. Overall, this project has revealed that EAEC virulence gene expression is modulated by intestinal environmental signals and identified phenotypic and genotypic traits specific for EAEC sequence types associated with disease or carriage

    The Influence of Stent Geometry on Haemodynamics and Endothelialisation

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    Every year, millions of people worldwide undergo stent implantation to widen narrowed arteries or to redirect blood away from aneurysms. The rapid post-operative regrowth of a healthy endothelial layer, a key factor in stented artery repair, would reduce complications and improve quality of life for many patients. While this has long been a clinical or pharmaceutical issue, this project considers the role of local haemodynamics, specifically the effects of stent-modified wall shear stress on the endothelium. Endothelial cells have a strong mechanobiological response to wall shear stress magnitude, direction and time variance. To understand the impact of stent geometry on this response through altered fluid dynamics, a novel model vessel was developed for the deployment of a wide range of coronary and flow diverter stents in vitro. The model allowed the observation of both endothelial cell migration and, via particle tracking, disturbed flow within the stents. High-resolution micro-computed tomography scanning techniques replicated stent geometry in silico, enabling computational fluid dynamics simulations for the assessment of wall shear stress distribution. Coronary stents greatly influenced fluid flow. The orientation and distribution of tracked particle streamlines were transformed proximal to stents struts, which were also areas of reduced wall shear stress. These areas correlated with zones of reduced cell migration. Flow diverter stents had a lesser impact on observable particle flow; yet endothelial cell migration within them was completely arrested. This is likely due to their structure directing flow away from the wall and reducing shear stress to an even greater extent that coronary stents, over a more substantial area. Dissimilar cell migration between coronary and flow diverter stents is a point of possible significance as the two are treated alike with respect to post-operative care and medication. Continued analysis of various geometries may enable the efficacy of individual stent designs to be quantified or predicted. By applying this knowledge in the future, careful stent design could reduce their impact, or exert an intentional, active influence on endothelial cells, to optimise the healing proces

    Energy. A continuing bibliography with indexes, issue 36, January 1983

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    This bibliography lists 1297 reports, articles, and other documents introduced into the NASA scientific and technical information system from October 1, 1982 through December 31, 1982

    Energy: A continuing bibliography with indexes, issue 20

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    A bibliography is presented which lists 1250 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System from October 1, 1978 through December 31, 1978
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