2,501 research outputs found

    A Generalized Nash-Cournot Model for the North-Western European Natural Gas Markets with a Fuel SubstitutionDemand Function: The GaMMES Model

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    This article presents a dynamic Generalized Nash-Cournot model to describe the evolution of the natural gas markets. The aim of this work is to provide a theoretical framework that would allow us to analyze future infrastructure and policy developments, while trying to answer some of the main criticisms addressed to Cournot-based models of natural gas markets. The major gas chain players are depicted including: producers, consumers, storage and pipeline operators, as well as intermediate local traders. Our economic structure description takes into account market power and the demand representation tries to capture the possible fuel substitution that can be made between the consumption of oil, coal and natural gas in the overall fossil energy consumption. We also take into account the long-term aspects inherent to some markets, in an endogenous way. This particularity of our description makes the model a Generalized Nash Equilibrium problem that needs to be solved using specialized mathematical techniques. Our model has been applied to represent the European natural gas market and forecast, until 2030, after a calibration process, consumption, prices, production and natural gas dependence. A comparison between our model, a more standard one that does not take into account energy substitution, and the European Commission natural gas forecasts is carried out to analyze our results. Finally, in order to illustrate the possible use of fuel substitution, we studied the evolution of the natural gas price as compared to the coal and oil prices. This paper mostly focuses on the model description.Energy markets modeling, Game theory, Generalized Nash-Cournot equilibria, Quasi-Variational Inequality

    Double-slot antennas on extended hemispherical dielectric lenses

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    An investigation of the coupling efficiencies to a gaussian-beam of a double-slot antenna on a hyperhemispherical lens is presented. It is shown that both lenses couple equally well to an appropriate gaussian beam (about 80 percent). The radiation patterns of both lenses with a double-slot antenna are computed using the ray-tracing method. The experimental radiation patterns are presented and show close agreement to the theoretically computed patterns

    Fundamentals of Lung Auscultation

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    Chest auscultation has long been considered a useful part of the physical examination, going back to the time of Hippocrates. However, it did not become a widespread practice until the invention of the stethoscope by René Laënnec in 1816, which made the practice convenient and hygienic.1 During the second half of the 20th century, technological advances in ultrasonography, radiographic computed tomography (CT), and magnetic resonance imaging shifted interest from lung auscultation to imaging studies, which can detect lung disease with an accuracy never previously imagined. However, modern computer-assisted techniques have also allowed precise recording and analysis of lung sounds, prompting the correlation of acoustic indexes with measures of lung mechanics. This innovative, though still little used, approach has improved our knowledge of acoustic mechanisms and increased the clinical usefulness of auscultation. In this review, we present an overview of lung auscultation in the light of modern concepts of lung acoustics

    Classical dissipative cost of quantum control

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    Protocols for non-adiabatic quantum control often require the use of classical time varying fields. Assessing the thermodynamic cost of such protocols, however, is far from trivial. In this letter we study the irreversible entropy produced by the classical apparatus generating the control fields, thus providing a direct link between the cost of a control protocol and dissipation. We focus, in particular, on the case of time-dependent magnetic fields and shortcuts to adiabaticity. Our results are showcased with two experimentally realisable case studies: the Landau-Zener model of a spin-1/2 particle in a magnetic field and an ion confined in a Penning trap

    Simultaneity

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    Catalog for the exhibition Simultaneity held at the Seton Hall University Walsh Gallery, January 20 - March 14, 2014. Curated by Gabriel Phipps. Includes essays by Joe Fyfe and Gabriel Phipps. Includes color illustration

    First Passage Times for Continuous Quantum Measurement Currents

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    The First Passage Time (FPT) is the time taken for a stochastic process to reach a desired threshold. It finds wide application in various fields and has recently become particularly important in stochastic thermodynamics, due to its relation to kinetic uncertainty relations (KURs). In this letter we address the FPT of the stochastic measurement current in the case of continuously measured quantum systems. Our approach is based on a charge-resolved master equation, which is related to the Full-Counting statistics of charge detection. In the quantum jump unravelling we show that this takes the form of a coupled system of master equations, while for quantum diffusion it becomes a type of quantum Fokker-Planck equation. In both cases, we show that the FPT can be obtained by introducing absorbing boundary conditions, making their computation extremely efficient. The versatility of our framework is demonstrated with two relevant examples. First, we show how our method can be used to study the tightness of recently proposed KURs for quantum jumps. Second, we study the homodyne detection of a single two-level atom, and show how our approach can unveil various non-trivial features in the FPT distribution.Comment: 8 pages, 2 figure

    Term-weighting for summarization of multi-party spoken dialogues

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    This paper explores the issue of term-weighting in the genre of spontaneous, multi-party spoken dialogues, with the intent of using such term-weights in the creation of extractive meeting summaries. The field of text information retrieval has yielded many term-weighting techniques to import for our purposes; this paper implements and compares several of these, namely tf.idf, Residual IDF and Gain. We propose that term-weighting for multi-party dialogues can exploit patterns in word us- age among participant speakers, and introduce the su.idf metric as one attempt to do so. Results for all metrics are reported on both manual and automatic speech recognition (ASR) transcripts, and on both the ICSI and AMI meeting corpora

    Optimizing Coherence Traffic in Manycore Processors Using Closed-Form Caching/Home Agent Mappings

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    [Abstract] Manycore processors feature a high number of general-purpose cores designed to work in a multithreaded fashion. Recent manycore processors are kept coherent using scalable distributed directories. A paramount example is the Intel Mesh interconnect, which consists of a network-on-chip interconnecting “tiles”, each of which contains computation cores, local caches, and coherence masters. The distributed coherence subsystem must be queried for every out-of-tile access, imposing an overhead on memory latency. This paper studies the physical layout of an Intel Knights Landing processor, with a particular focus on the coherence subsystem, and uncovers the pseudo-random mapping function of physical memory blocks across the pieces of the distributed directory. Leveraging this knowledge, candidate optimizations to improve memory latency through the minimization of coherence traffic are studied. Although these optimizations do improve memory throughput, ultimately this does not translate into performance gains due to inherent overheads stemming from the computational complexity of the mapping functions.Ministerio de Educación; FPU16/00816U.S. National Science Foundation; CCF-1750399Xunta de Galicia and FEDER; ED431G 2019/01Ministerio de Ciencia e Innovación; PID2019-104184RB-I0
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