2,901 research outputs found

    Quantum density anomaly in optically trapped ultracold gases

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    We show that the Bose-Hubbard Model exhibits an increase in density with temperature at fixed pressure in the regular fluid regime and in the superfluid phase. The anomaly at the Bose-Einstein condensate is the first density anomaly observed in a quantum state. We propose that the mechanism underlying both the normal phase and the superfluid phase anomalies is related to zero point entropies and ground state phase transitions. A connection with the typical experimental scales and setups is also addressed. This key finding opens a new pathway for theoretical and experimental studies of water-like anomalies in the area of ultracold quantum gases

    Molecular correlations and solvation in simple fluids

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    We study the molecular correlations in a lattice model of a solution of a low-solubility solute, with emphasis on how the thermodynamics is reflected in the correlation functions. The model is treated in Bethe-Guggenheim approximation, which is exact on a Bethe lattice (Cayley tree). The solution properties are obtained in the limit of infinite dilution of the solute. With h11(r)h_{11}(r), h12(r)h_{12}(r), and h22(r)h_{22}(r) the three pair correlation functions as functions of the separation rr (subscripts 1 and 2 referring to solvent and solute, respectively), we find for r2r \geq 2 lattice steps that h22(r)/h12(r)h12(r)/h11(r)h_{22}(r)/h_{12}(r) \equiv h_{12}(r)/h_{11}(r). This illustrates a general theorem that holds in the asymptotic limit of infinite rr. The three correlation functions share a common exponential decay length (correlation length), but when the solubility of the solute is low the amplitude of the decay of h22(r)h_{22}(r) is much greater than that of h12(r)h_{12}(r), which in turn is much greater than that of h11(r)h_{11}(r). As a consequence the amplitude of the decay of h22(r)h_{22}(r) is enormously greater than that of h11(r)h_{11}(r). The effective solute-solute attraction then remains discernible at distances at which the solvent molecules are essentially no longer correlated, as found in similar circumstances in an earlier model. The second osmotic virial coefficient is large and negative, as expected. We find that the solvent-mediated part W(r)W(r) of the potential of mean force between solutes, evaluated at contact, r=1r=1, is related in this model to the Gibbs free energy of solvation at fixed pressure, ΔGp\Delta G_p^*, by (Z/2)W(1)+ΔGppv0(Z/2) W(1) + \Delta G_p^* \equiv p v_0, where ZZ is the coordination number of the lattice, pp the pressure, and v0v_0 the volume of the cell associated with each lattice site. A large, positive ΔGp\Delta G_p^* associated with the low solubility is thus reflected in a strong attraction (large negative WW at contact), which is the major contributor to the second osmotic virial coefficient. In this model, the low solubility (large positive ΔGp\Delta G_p^*) is due partly to an unfavorable enthalpy of solvation and partly to an unfavorable solvation entropy, unlike in the hydrophobic effect, where the enthalpy of solvation itself favors high solubility, but is overweighed by the unfavorable solvation entropy.Comment: 9 pages, 2 figure

    Towards a relational model for component interconnection

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    The basic motivation of component based development is to replace conventional programming by the composition of reusable off-the-shelf units, externally coordinated through a network of connecting devices, to achieve a common goal. This paper introduces a new relational model for software connectors and discusses some preliminary work on its implementation in HASKELL. The proposed model adopts a coordination point of view in order to deal with components’ temporal and spatial decoupling and, therefore, to provide support for looser levels of inter-component dependency and effective external control

    An orchestrator for dynamic interconnection of software components

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    Composing and orchestrating software components is a fundamental concern in modern software engineering. This paper addresses the possibility of such orchestration being dynamic, in the sense that the structure of component's interconnection patterns can change at run-time. The envisaged approach extends previous work by the authors on the use of coalgebraic models for the specification of software connectors.POSI/ICHS/44304/200

    Looking Beyond Appearances: Synthetic Training Data for Deep CNNs in Re-identification

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    Re-identification is generally carried out by encoding the appearance of a subject in terms of outfit, suggesting scenarios where people do not change their attire. In this paper we overcome this restriction, by proposing a framework based on a deep convolutional neural network, SOMAnet, that additionally models other discriminative aspects, namely, structural attributes of the human figure (e.g. height, obesity, gender). Our method is unique in many respects. First, SOMAnet is based on the Inception architecture, departing from the usual siamese framework. This spares expensive data preparation (pairing images across cameras) and allows the understanding of what the network learned. Second, and most notably, the training data consists of a synthetic 100K instance dataset, SOMAset, created by photorealistic human body generation software. Synthetic data represents a good compromise between realistic imagery, usually not required in re-identification since surveillance cameras capture low-resolution silhouettes, and complete control of the samples, which is useful in order to customize the data w.r.t. the surveillance scenario at-hand, e.g. ethnicity. SOMAnet, trained on SOMAset and fine-tuned on recent re-identification benchmarks, outperforms all competitors, matching subjects even with different apparel. The combination of synthetic data with Inception architectures opens up new research avenues in re-identification.Comment: 14 page

    A hybrid genetic approach to solve real make-to-order job shop scheduling problems

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    Tese (doutorado) - Universidade Federal de Santa Catarina, Centro TecnologicoProcedimentos de busca local (ex. busca tabu) e algoritmos genéticos têm apresentado excelentes resultados em problemas clássicos de programação da produção em ambientes job shop. No entanto, estas abordagens apresentam pobres habilidades de modelamento e poucas aplicações com restrições de ambientes reais de produção têm sido publicadas. Além disto, os espaços de busca considerados nestas aplicações são nomlalmente incompletos e as restrições reais são poucas e dependentes do problema em questão. Este trabalho apresenta uma abordagem genética híbrida para resolver problemas de programação em ambientes job shop com grande número de restrições reais, tais como produtos com vários níveis de submontagem, planos de processamento altemativos para componentes e recursos alternativos para operações, exigência de vários recursos para executar uma operação (ex., máquina, ferramentas, operadores), calendários para todos os recursos, sobreposição de operações, restrições de disponibilidade de matéria-prima e componentes comprados de terceiros, e tempo de setup dependente da sequência de operações. A abordagem também considera funções de avaliação multiobjetivas. O sistema usa algoritmos modificados de geração de programação, que incorporam várias heurísticas de apoio à decisão, para obter um conjunto de soluções iniciais. Cada solução inicial é melhorada por um algoritmo de subida de encosta. Então, um algoritmo genético híbrido com procedimentos de busca local é aplicado ao conjunto inicial de soluções localmente ótimas. Ao utilizar técnicas de programação de alta perfomlance (heurísticas construtivas, procedimentos de busca local e algoritmos genéticos) em problemas reais de programação da produção, este trabalho reduziu o abismo existente entre a teoria e a prática da programação da produção

    Burberry, tisci and streetwear

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    The main purpose of the following report is to try to reach the expected quantitative value Riccardo Tisci with his streetwear collections may bring to Burberry in the next five financial years. Due to a lack of resources, many assumptions were made in order to reach a quantitative final result. Notwithstanding these assumptions were based on consulting reliable sources. I do believe that with more data and more complete empirical and behavioral research could bring more concrete results.The report starts with a brief introduction to the streetwear trend and why Riccardo Tisci to be chosen based on new Burberry’s strategy
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