953 research outputs found

    (Poor) Roger Maris, 1964 Topps

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    A comparative study of circular and rectangular bended plunging jets

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    In the present work we study the topology, mixing properties, turbulence quantities, dependence on the outlet geometry of a sharp-edged orifice plunging jet which first issues horizontally in air and then plunges in a water pool. The investigated orifices shapes are circular and rectangular. Data are acquired at different Reynolds numbers in the range 11000-25000, based on the orifice diameter (equal to 2 cm) and on the average exit velocity, as derived from flow rate measurements. Velocity fields in vertical and horizontal planes are measured using planar time-resolved Particle Image Velocimetry. Results show a clear asymmetry of the cross-velocity profiles both in circular and rectangular cases, with the latter that revealed a shape which is Reynolds num-ber dependent. Axial velocity decays, potential core lengths and spreading rates highlight an opposite trend between the two jet geometries, thus suggesting a higher mixing for the lowest Reynolds number circular jet and the highest rectangular one. Plunging angle shows a dependency on Reynolds number. Moreover, it seems to play a role in the evolution of the upper and lower side of the jet due to the onset of a co-flow. Ambient mass entrainment points out the different interactions of the two plunging jets with the ambient flow: in circular case, it entrains fluid from the surroundings, from horizontal to vertical planes in streamwise direction, while in rectangular one it ejects flow from vertical to horizontal planes. Finally, Strouhal numbers are derived for main vortices frequencies along jet centerline, other than upper and lower sides

    HeteroGenius: A Framework for Hybrid Analysis of Heterogeneous Software Specifications

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    Nowadays, software artifacts are ubiquitous in our lives being an essential part of home appliances, cars, cell phones, and even in more critical activities like aeronautics and health sciences. In this context software failures may produce enormous losses, either economical or, in the worst case, in human lives. Software analysis is an area in software engineering concerned with the application of diverse techniques in order to prove the absence of errors in software pieces. In many cases different analysis techniques are applied by following specific methodological combinations that ensure better results. These interactions between tools are usually carried out at the user level and it is not supported by the tools. In this work we present HeteroGenius, a framework conceived to develop tools that allow users to perform hybrid analysis of heterogeneous software specifications. HeteroGenius was designed prioritising the possibility of adding new specification languages and analysis tools and enabling a synergic relation of the techniques under a graphical interface satisfying several well-known usability enhancement criteria. As a case-study we implemented the functionality of Dynamite on top of HeteroGenius.Comment: In Proceedings LAFM 2013, arXiv:1401.056

    Improving performances of biomimetic wings with leading-edge tubercles

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    The present study aims investigating experimentally wing/blade geometries in which the leading edge is modified by the presence of artificial bumps, following examples in nature (“biomimetics”). Specifically, the tubercles observed in humpback whales are considered with a special focus on easy manufacturing and performance improvements, trying to overcome the observed lift coefficient reduction before stall in comparison with a standard wing. To this end, different tubercle geometries are tested, by measuring overall forces acting on the wings and by deriving detailed velocity fields using particle image velocimetry. Measurements indicate performance improvements for all trailing edge tubercle geometries here tested. In addition, the detailed analysis of mechanisms underlying the improvement of performances suggests that a triangular shape of the leading edge combines the advantages of easy manufacturing and improvements of pre-stall behaviour. So far, a simple mathematical model, describing tubercles as delta wings, is presented and verified by experimental data. The objective of the present work is focusing on the basic fluid-mechanics phenomena involved, to show that beneficial effects of tubercles are present even when tubercle details are simplified, in order to couple performance improvement and ease of assembly

    Separating sets of strings by finding matching patterns is almost always hard

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    © 2017 Elsevier B.V. We study the complexity of the problem of searching for a set of patterns that separate two given sets of strings. This problem has applications in a wide variety of areas, most notably in data mining, computational biology, and in understanding the complexity of genetic algorithms. We show that the basic problem of finding a small set of patterns that match one set of strings but do not match any string in a second set is difficult (NP-complete, W[2]-hard when parameterized by the size of the pattern set, and APX-hard). We then perform a detailed parameterized analysis of the problem, separating tractable and intractable variants. In particular we show that parameterizing by the size of pattern set and the number of strings, and the size of the alphabet and the number of strings give FPT results, amongst others

    Intergroup alliance orientation among intermediate-status group members: The role of stability of social stratification

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    Three studies have tested the hypothesis that intermediate-status groups are more oriented to ally with outgroups when their social position is under threat. In study 1, participants believed that their ingroup was intermediate in status and social stratification was manipulated as either stable or status-detrimental unstable. Results indicated that participants were more likely to seek alliances a) with a high-status group and b) when social stratification was status-detrimental unstable. Study 2 showed that participants were more likely to seek alliances with a lower status group when social stratification was status-detrimental unstable rather than stable, while they were supportive of policies helping disadvantaged groups regardless of the stability of social stratification. Study 3 showed that when social stratification was status-detrimental unstable, intermediate-status group members were more oriented to ally with a low-status group, equally supportive of policies helping disadvantaged groups, but less oriented to supplying direct help to a low-status group

    World Trade Center disaster: short- and medium-term health outcome

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    Several studies related to September 11 World Trade Center (WTC) terrorist attack have been conducted in order to monitor physical and mental health in the population at risk in the short and medium term. In this paper the main health consequences in the exposed subjects 6 years after the disaster, including ocular, gastrointestinal, respiratory and psychological effects are described and discussed

    Screening of at-risk blood donors for Chagas disease in non-endemic countries: Lessons from a 2-year experience in Tuscany, Italy

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    Background: Chagas disease (CD) is caused by the protozoan parasite Trypanosoma cruzi and is transmitted by blood-sucking triatomine insects in endemic areas of Latin America. Transmission can also occur via blood transfusion and is a major cause of CD in non-endemic areas. Objectives: The aim of the study was to assess the prevalence of anti-T. cruzi antibodies in blood donors at risk of infection in Tuscany, Italy, following the introduction of blood safety Italian legislation. Material and methods: Donors (N = 1985) were tested in 2016 to 2018 for anti-T. cruzi IgG using an immunochromatographic test (ICT). Chemiluminescent immunoassay (CLIA) was performed on ICT-positive donors to exclude CD, whereas enzyme-linked immunosorbent assay and Western blot were performed in case of discordant results. All assays were performed on CD patients (N = 10) for validation. Results: Ten blood donors had a positive ICT result, with a resulting T. cruzi seroprevalence of 0.5% but demonstrates negative results to CLIA, as well as to the other serological assays. The comparison of serological assays suggested a lower relative sensitivity of ICT. Conclusion: The results of this study confirm the significance of serological testing in the screening strategy for TT CD. However, they provide evidence for discontinuing the use of ICT as a screening test and suggest that a sensitive, specific and multi-sample format assay should be used at the national level for uniformity of results

    Editorial: Exploring system justification phenomenon among disadvantaged individuals

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    The question of why (or even when) the disadvantaged might be more or less supportive of existing social arrangements is a matter of debate amongst social and political psychologists (e.g., Passini, 2019; Jost, 2020, see also Rubin et al., 2022). Accordingly, for this Research Topic, we chose a title that was deliberately broad in scope, accommodating several aspects that included: (a) the drivers of system justification; (b) the socio-structural conditions that enhance or dampen system justification, (c) the ideological correlates of system support, and (d) the impact of system justification on wellbeing. Taken together, the contributions comprised in this Research Topic provide a comprehensive analysis of these four issues

    The influence of chromium nitrides precipitation on the fatigue behavior of duplex stainless steels

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    This paper studies the fatigue behavior at room temperature of UNS S32205 and UNS S32750 duplex stainless steels (DSSs) under two thermal treatments. In both types of DSSs, thermal treatments at high temperature followed by water quenching (TTW) produces the precipitation of Cr2N within the ferrite phase. The amount of Cr2N increases mainly with the ferritic grain size independently of the nitrogen content. This nitride precipitation hardens the ferritic phase and produces a detrimental effect on the fatigue life of both steels.Fil: Hereñu, Silvina Andrea Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Armas, A. F.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Alvarez, Iris. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); ArgentinaFil: Moscato, M. G.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentin
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