120,766 research outputs found

    Photoproduction of K+ΛK^{*+}\Lambda and K+Σ(1385)K^+\Sigma(1385) in the reaction \gamma \lowercase{p} \to K^+ \Lambda \pi^0 at Jefferson Lab

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    The search for missing nucleon resonances using coupled channel analysis has mostly been concentrated on NπN\pi and KYKY channels, while the contributions of KYK^*Y and KYKY^* channels have not been investigated thoroughly mostly due to the lack of data. With an integrated luminosity of about 75 pb1pb^{-1}, the photoproduction data using a proton target recently collected by the CLAS Collaboration at Jefferson Lab with a photon energy range of 1.5-3.8 GeV provided large statistics for the study of light hyperon photoproduction through exclusive reactions. The reaction γpK+Λπ0\gamma p \to K^+ \Lambda \pi^0 has been investigated. Preliminary results of the K+ΛK^{*+}\Lambda and K+Σ(1385)K^+\Sigma(1385) cross sections are not negligible compared with the KYKY channels. The Λπ0\Lambda \pi^0 invariant mass spectrum is dominated by the Σ(1385)\Sigma(1385) signal and no significant structure was found around the Σ(1480)\Sigma(1480) region.Comment: 4 pages, 3 figures, to be publised on the NSTAR05 proceeding

    Creating a Chemistry of Sciences with Big Data

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    The Data Science Institute at Imperial College London launched in April 2014, and will provide a hub for data-driven research and education. Its mission is to provide a focal point for the College's capabilities in multidisciplinary data-driven research by coordinating advanced data science research for college scientists and partners, and educating the next generation of data scientists. We surveyed the data-driven research needs at Imperial College London to gain an understanding across all disciplines offered by the College, and analysed the responses to gain insights into scientific and engineering needs for data science research. A clear message is that multidisciplinarity is essential for Big Data and data science research to enable a "chemistry of sciences": connecting all disciplines by integrating data. This paper presents our efforts to best understand datadriven research needs in a highly multidisciplinary researchintensive institution and describes our vision for the future of the Data Science Institute at Imperial College London. © Copyright 2014 ACM

    Spatio-temporal generalised frequency response functions over unbounded spatial domains

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    The concept of generalised frequency response functions (GFRFs), which were developed for nonlinear system identification and analysis, is extended to continuous spatio-temporal dynamical systems normally described by partial differential equations (PDEs). The paper provides the definitions and interpretation of spatio-temporal generalised frequency response functions for linear and nonlinear spatio-temporal systems, defined over unbounded spatial domains, based on an impulse response procedure. A new probing method is also developed to calculate the GFRFs. Both the Diffusion equation and Fisher’s equation are analysed to illustrate the new frequency domain methods

    Spatio-temporal generalised frequency response functions

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    The concept of generalised frequency response functions (GFRFs), which were developed for nonlinear system identification and analysis, is extended to continuous spatio-temporal dynamical systems normally described by partial differential equations (PDEs). The paper provides the definitions and interpretation of spatio-temporal generalised frequency response functions for linear and nonlinear spatio-temporal systems based on an impulse response procedure. A new probing method is also developed to calculate the GFRFs. Both the Diffusion equation and Fisher’s equation are analysed to illustrate the new frequency domain methods

    Study of Multilouvered Heat Exchangers at Low Reynolds numbers

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    Air Conditioning and Refrigeration Project 13

    Galaxy growth in the concordance Λ\LambdaCDM cosmology

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    We use galaxy and dark halo data from the public database for the Millennium Simulation to study the growth of galaxies in the De Lucia et al. (2006) model for galaxy formation. Previous work has shown this model to reproduce many aspects of the systematic properties and the clustering of real galaxies, both in the nearby universe and at high redshift. It assumes the stellar masses of galaxies to increase through three processes, major mergers, the accretion of smaller satellite systems, and star formation. We show the relative importance of these three modes to be a strong function of stellar mass and of redshift. Galaxy growth through major mergers depends strongly on stellar mass, but only weakly on redshift. Except for massive systems, minor mergers contribute more to galaxy growth than major mergers at all redshifts and at all stellar masses. For galaxies significantly less massive than the Milky Way, star formation dominates the growth at all epochs. For galaxies significantly more massive than the Milky Way, growth through mergers is the dominant process at all epochs. At a stellar mass of 6×1010M6\times 10^{10}M_\odot, star formation dominates at z>1z>1 and mergers at later times. At every stellar mass, the growth rates through star formation increase rapidly with increasing redshift. Specific star formation rates are a decreasing function of stellar mass not only at z=0z=0 but also at all higher redshifts. For comparison, we carry out a similar analysis of the growth of dark matter halos. In contrast to the galaxies, growth rates depend strongly on redshift, but only weakly on mass. They agree qualitatively with analytic predictions for halo growth.Comment: 11 pages, 6 figure

    Multiscale identification of spatio-temporal dynamical systems using a wavelet multiresolution analysis

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    In this paper, a new algorithm for the multiscale identification of spatio-temporal dynamical systems is derived. It is shown that the input and output observations can be represented in a multiscale manner based on a wavelet multiresolution analysis. The system dynamics at some specific scale of interest can then be identified using an orthogonal forward leastsquares algorithm. This model can then be converted between different scales to produce predictions of the system outputs at different scales. The method can be applied to both multiscale and conventional spatio-temporal dynamical systems. For multiscale systems, the method can generate a parsimonious and effective model at a coarser scale while considering the effects from finer scales. Additionally, the proposed method can be used to improve the performance of the identification when measurements are noisy. Numerical examples are provided to demonstrate the application of the proposed new approach
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