7,246 research outputs found

    Financial Risk, Innovation and Alternative Pathways to Decarbonising the Energy System in 2050

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    There is a lot of forward looking work attempting to envisage the decarbonised energy system of the future as reflected with current interest in 'smart grids'. A central tenet behind most visions of the 'smart grids' of the future are the price signals that financial and commodity markets will deliver to facilitate effective and efficient resource allocation. Most of these visions take stylised and static views of financial and commodity markets despite the fact that these markets are experiencing dramatic change due to innovation and regulation. Accordingly, the paper maps the risks associated in the fusion of financial innovation with innovation in the energy system through a theoretical framework that draws on evolutionary models of paradigm shift. Risks to both the financial and energy systems are characterised as either emanating from primary or secondary markets and these are explored in terms of alternative visions of the energy system in the long run

    On the Implementation of GNU Prolog

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    GNU Prolog is a general-purpose implementation of the Prolog language, which distinguishes itself from most other systems by being, above all else, a native-code compiler which produces standalone executables which don't rely on any byte-code emulator or meta-interpreter. Other aspects which stand out include the explicit organization of the Prolog system as a multipass compiler, where intermediate representations are materialized, in Unix compiler tradition. GNU Prolog also includes an extensible and high-performance finite domain constraint solver, integrated with the Prolog language but implemented using independent lower-level mechanisms. This article discusses the main issues involved in designing and implementing GNU Prolog: requirements, system organization, performance and portability issues as well as its position with respect to other Prolog system implementations and the ISO standardization initiative.Comment: 30 pages, 3 figures, To appear in Theory and Practice of Logic Programming (TPLP); Keywords: Prolog, logic programming system, GNU, ISO, WAM, native code compilation, Finite Domain constraint

    Percolation for the stable marriage of Poisson and Lebesgue with random appetites

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    Let Ξ\Xi be a set of centers chosen according to a Poisson point process in Rd\mathbb R^d. Consider the allocation of Rd\mathbb R^d to Ξ\Xi which is stable in the sense of the Gale-Shapley marriage problem, with the additional feature that every center ξ∈Ξ\xi\in\Xi has a random appetite αV\alpha V, where α\alpha is a nonnegative scale constant and VV is a nonnegative random variable. Generalizing previous results by Freire, Popov and Vachkovskaia (\cite{FPV}), we show the absence of percolation when α\alpha is small enough, depending on certain characteristics of the moment of VV.Comment: 12 pages. Final versio

    Parallel local search for solving Constraint Problems on the Cell Broadband Engine (Preliminary Results)

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    We explore the use of the Cell Broadband Engine (Cell/BE for short) for combinatorial optimization applications: we present a parallel version of a constraint-based local search algorithm that has been implemented on a multiprocessor BladeCenter machine with twin Cell/BE processors (total of 16 SPUs per blade). This algorithm was chosen because it fits very well the Cell/BE architecture and requires neither shared memory nor communication between processors, while retaining a compact memory footprint. We study the performance on several large optimization benchmarks and show that this achieves mostly linear time speedups, even sometimes super-linear. This is possible because the parallel implementation might explore simultaneously different parts of the search space and therefore converge faster towards the best sub-space and thus towards a solution. Besides getting speedups, the resulting times exhibit a much smaller variance, which benefits applications where a timely reply is critical

    Topological Magnons and Edge States in Antiferromagnetic Skyrmion Crystals

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    Antiferromagnetic skyrmion crystals are magnetic phases predicted to exist in antiferromagnets with Dzyaloshinskii-Moriya interactions. Their spatially periodic noncollinear magnetic texture gives rise to topological bulk magnon bands characterized by nonzero Chern numbers. We find topologically-protected chiral magnonic edge states over a wide range of magnetic fields and Dzyaloshinskii-Moriya interaction values. Moreover, and of particular importance for experimental realizations, edge states appear at the lowest possible energies, namely, within the first bulk magnon gap. Thus, antiferromagnetic skyrmion crystals show great promise as novel platforms for topological magnonics.Comment: 5 pages, 5 figure

    Towards End-to-End Acoustic Localization using Deep Learning: from Audio Signal to Source Position Coordinates

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    This paper presents a novel approach for indoor acoustic source localization using microphone arrays and based on a Convolutional Neural Network (CNN). The proposed solution is, to the best of our knowledge, the first published work in which the CNN is designed to directly estimate the three dimensional position of an acoustic source, using the raw audio signal as the input information avoiding the use of hand crafted audio features. Given the limited amount of available localization data, we propose in this paper a training strategy based on two steps. We first train our network using semi-synthetic data, generated from close talk speech recordings, and where we simulate the time delays and distortion suffered in the signal that propagates from the source to the array of microphones. We then fine tune this network using a small amount of real data. Our experimental results show that this strategy is able to produce networks that significantly improve existing localization methods based on \textit{SRP-PHAT} strategies. In addition, our experiments show that our CNN method exhibits better resistance against varying gender of the speaker and different window sizes compared with the other methods.Comment: 18 pages, 3 figures, 8 table

    Magnonic Quadrupole Topological Insulator in Antiskyrmion Crystals

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    When the crystalline symmetries that protect a higher-order topological phase are not preserved at the boundaries of the sample, gapless hinge modes or in-gap corner states cannot be stabilized. Therefore, careful engineering of the sample termination is required. Similarly, magnetic textures, whose quantum fluctuations determine the supported magnonic excitations, tend to relax to new configurations that may also break crystalline symmetries when boundaries are introduced. Here we uncover that antiskyrmion crystals provide an experimentally accessible platform to realize a magnonic topological quadrupole insulator, whose hallmark signature are robust magnonic corner states. Furthermore, we show that tuning an applied magnetic field can trigger the self-assembly of antiskyrmions carrying a fractional topological charge along the sample edges. Crucially, these fractional antiskyrmions restore the symmetries needed to enforce the emergence of the magnonic corner states. Using the machinery of nested Wilson loops, adapted to magnonic systems supported by noncollinear magnetic textures, we demonstrate the quantization of the bulk quadrupole moment, edge dipole moments, and corner charges

    Architecture for transition: Analysis of two projects in the peace-building process in Colombia

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    Architecture for transition is a proposal of theoretical and methodological approach that takes up approaches from the South epistemologies and critical design studies. Therefore, a conceptual debate on this perspective has the purpose of contextualizing and localizing the analysis of two communitarian small infrastructure projects generated within the framework of the peace-building process in Colombia. The evaluation of these projects implemented in the rural area of San José del Guaviare from the perspective of architecture for transition evidences a technical logic that is decontextualized, delocalized and dysfunctional in the conception and execution of the architectural design. This leads to the conclusion that the approach proposed should be considered to achieve architectural projects that adapt to the territorial conditions, respond to the inhabitants needs, strengthen community ties, and contribute to the construction of peace

    Engineering proteins with 3D convolutional neural networks

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