4,655 research outputs found

    Dependence of the drag over super hydrophobic and liquid infused surfaces on the textured surface and Weber number

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    Direct Numerical Simulations of a turbulent channel flow have been performed. The lower wall of the channel is made of staggered cubes with a second fluid locked in the cavities. Two viscosity ratios have been considered, m=μ1/μ2=0.02 and 0.4 (the subscript 1 indicates the fluid in the cavities and 2 the overlying fluid) mimicking the viscosity ratio in super–hydrophobic surfaces (SHS) and liquid infused surfaces (LIS) respectively. A first set of simulations with a slippery interface has been performed and results agree well with those in literature for perfect slip conditions and Stokes approximations. To assess how the dynamics of the interface affects the drag, a second set of DNS has been carried out at We=40 and 400 corresponding to We+≃10−3 and 10−2. The deformation of the interface is fully coupled to the Navier-Stokes equation and tracked in time using a Level Set Method. Two gas fractions, GF=0.5 and 0.875, have been considered to assess how the spacing between the cubes affects the deformation of the interface and therefore the drag. For the dimensions of the substrate here considered, under the ideal assumption of flat interface, staggered cubes with GF=0.875 provide about 20% drag reduction for We=0. However, a rapid degradation of the performances is observed when the dynamics of the interface is considered, and the same geometry increases the drag of about 40% with respect to a smooth wall. On the other hand, the detrimental effect of the dynamics of the interface is much weaker for GF=0.5 because of the reduced pitch between the cubes

    On the universality of the scaling of fluctuations in traffic on complex networks

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    We study the scaling of fluctuations with the mean of traffic in complex networks using a model where the arrival and departure of "packets" follow exponential distributions, and the processing capability of nodes is either unlimited or finite. The model presents a wide variety of exponents between 1/2 and 1 for this scaling, revealing their dependence on the few parameters considered, and questioning the existence of universality classes. We also report the experimental scaling of the fluctuations in the Internet for the Abilene backbone network. We found scaling exponents between 0.71 and 0.86 that do not fit with the exponent 1/2 reported in the literature.Comment: 4 pages, 4 figure

    EVALUATION OF RURAL DEVELOPMENT PROGRAMMES FAILURES WITHIN THE 2007-13 REGIONAL POLICY FRAME

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    New 2007-13 planning framework of the EU keeps using economic criteria (GDP) to identify those regions requiring priority attention (convergence objective). Although these criteria are useful for the overall Regional Policy, nevertheless it might result some planning failures of the strategies of rural development. This work focuses in evaluating possible failures of the Rural Development Programmes. For this purpose, a wide range of member Estates and Regions has been selected and two analysis have been applied: first, the coherence analysis (in relation to the economic, social and environmental situation of territories); and second, the conflict (among the rural territories development objectives) analysis. As result of this evaluation, a typology of the analysed Rural Development Programmes will be shown, which identifies different cases of failures. This work concludes that the use of methodological criteria in Regional Policy complementing to the Efficiency criteria might improve the territorial cohesion process and reduce some of the analysed failures in rural areas.Rural Development Programmes, Regional Policy, European Union, Community/Rural/Urban Development,

    Thermodynamics of noncommutative quantum Kerr black holes

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    Thermodynamic formalism for rotating black holes, characterized by noncommutative and quantum corrections, is constructed. From a fundamental thermodynamic relation, equations of state and thermodynamic response functions are explicitly given and the effect of noncommutativity and quantum correction is discussed. It is shown that the well known divergence exhibited in specific heat is not removed by any of these corrections. However, regions of thermodynamic stability are affected by noncommutativity, increasing the available states for which some thermodynamic stability conditions are satisfied.Comment: 16 pages, 9 figure

    Modelling security properties in a grid-based operating system with anti-goals

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    The Pleistocene Glyptodontidae Gray, 1869 (Xenarthra: Cingulata) of Colombia and some considerations about the South American Glyptodontinae

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    Until recently, one well-characterized Pleistocene genus of the subfamily Glyptodontinae (Glyptodon ca. 1.08-0.0011 My) was recognized in South America. In recent times, some authors have demonstrated, through the re-analysis of material originally classified as Glyptodon Owen and Hoplophorus Lund, the presence of a second species belonging to the North American glyptodontine Glyptotherium Osborn (ca. 58-12 ky BP), currently known from in Venezuela and Brazil. This situation implies the need for a new study, with modern taxonomical criteria, of those materials belonging to the Glyptodontinae, particularly in those territories where the knowledge of these taxa is scarce. Presented here is a new analysis of the Pleistocene Glyptodontidae from Colombia, including some taxonomic and paleobiogeographic remarks. The results show that the only reported Glyptodontidae specimens in Colombia belong to Glyptodon sp. In turn, the evidence suggests that only one single species of Glyptotherium is present in South America, currently assigned to Glyptotherium cf. Gl. cylindricum. However, a more accurate analysis is necessary to confirm or refute this taxonomic identification. To date, Glyptotherium present has been found only in an area parallel to the Caribbean Sea and the Atlantic Ocean (northern Venezuela and eastern Brazil), up to 20°S, and is always linked to lowlands. This geographic distribution agrees with the proposition of an eastern corridor during the Great American Biotic Interchange. Below this latitude, the only recorded glyptodontine corresponds to Glyptodon, which is also recorded in a strip parallel to the Cordillera de Los Andes reaching Colombia and Venezuela. Taking into account this distribution, the presence of this genus in Central America cannot be discardedAté pouco tempo, um único gênero endêmico do Pleistoceno pertencente à subfamília Glyptodontinae (Glyptodon ca. 1.08- 0.0011 Ma) era reconhecido para a América do Sul. Recentemente, alguns autores têm demonstrado, através de novas análises do material originalmente classificado como Glyptodon Owen e Hoplophorus Lund, a presença de uma segunda espécie de Glyptodontinae pertencente ao gênero norte-americano Glyptotherium (ca. 58-12 ka AP), atualmente presente na Venezuela e Brasil. Essa situação implica na necessidade de uma nova análise do material referente à Glyptodontinae, com um critério taxonômico mais moderno, especialmente em localidades onde o conhecimento desse grupo é escasso. Na presente contribuição, é apresentada uma nova análise taxonômica dos Glyptodontidae encontrados na Colômbia, incluindo algumas observações taxonômicas e paleobiogeográficas. Os resultados demonstram que o único relato de Glyptodontidae para a Colômbia pertence à Glyptodon sp. Porém, a evidência sugere que somente uma única espécie de Glyptotherium Osborn está presente na América do Sul, atualmente atribuída a Glyptotherium cf. Gl. cylindricum. Uma análise mais precisa é necessária para confirmar sua identificação taxonômica. Até agora, Glyptotherium está presente em uma faixa paralela ao Mar Caribenho e Oceano Atlântico (Norte da Venezuela e região oriental do Brasil), até 20°S, e sempre vinculado à terras baixas. Essa distribuição geográfica concorda com a proposição de um corredor oriental durante o Grande Intercâmbio Biótico Americano. Abaixo dessa latitude, o único registro de Glyptodontinae corresponde a Glyptodon, o qual também é registrado em uma faixa paralela a Cordilheira dos Andes, alcançando Colômbia e Venezuela. Levando em consideração essa distribuição, a presença desse gênero na América Central não deveria ser descartada.Fil: Zurita, Alfredo Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Miño Boilini, Ángel Ramón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Francia, Analia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Arenas Mosqueras, José E.. Museo Geológico Nacional José Royo y Gómez; Colombi

    Beyond mean-field bistability in driven-dissipative lattices: bunching-antibunching transition and quantum simulation

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    In the present work we investigate the existence of multiple nonequilibrium steady states in a coherently driven XY lattice of dissipative two-level systems. A commonly used mean-field ansatz, in which spatial correlations are neglected, predicts a bistable behavior with a sharp shift between low- and high-density states. In contrast one-dimensional matrix product methods reveal these effects to be artifacts of the mean-field approach, with both disappearing once correlations are taken fully into account. Instead, a bunching-antibunching transition emerges. This indicates that alternative approaches should be considered for higher spatial dimensions, where classical simulations are currently infeasible. Thus we propose a circuit QED quantum simulator implementable with current technology to enable an experimental investigation of the model considered

    Magnetodielectric coupling of infrared phonons in single crystal Cu2_{2}OSeO3_{3}

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    Reflection and transmission as a function of temperature have been measured on a single crystal of the magnetoelectric ferrimagnetic compound Cu2_{2}OSeO3_{3} utilizing light spanning the far infrared to the visible portions of the electromagnetic spectrum. The complex dielectric function and optical properties were obtained via Kramers-Kronig analysis and by fits to a Drude-Lortentz model. The fits of the infrared phonons show a magnetodielectric effect near the transition temperature (Tc60T_{c}\sim 60~K). Assignments to strong far infrared phonon modes have been made, especially those exhibiting anomalous behavior around the transition temperature

    Resilience, Acculturative Stress, and Family Norms Against Disclosure of Mental Health Problems Among Foreign-Born Filipino American Women

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    The present study explores the relationships between resilience, acculturative stress, and family norms against disclosure of mental health problems among foreign-born Filipino American women. The sample consisted of 159 foreign-born Filipino American women aged 18 years and above and residing in Las Vegas, Nevada, United States. Participants completed paper-and-pencil questionnaires. Results indicated high levels of resilience and moderate levels of acculturative stress. Findings also showed a significant negative correlation between resilience and acculturative stress, and a significant predictive effect of resilience on acculturative stress. We also found a significant negative relationship between resilience and family norms against disclosure of mental health problems but no significant mediating effect of resilience on the relationship between acculturative stress and family norms. This lack of significant findings related to the mediating effect of resilience on the relationship between acculturative stress and family norms against disclosure of mental illness may be due to the absence of theoretical models and research regarding the role of resilience in the context of acculturation among Filipino American women. Our findings imply the need to further explore underlying mechanisms that explain the relationships between resilience, acculturative stress, and family norms. The findings of the study also confirm the need to develop interventions and resources that ameliorate acculturative stress and promote an increase of the disclosure and reporting of mental health problems among Filipino American women
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