432 research outputs found

    Smart Grid Economics: Policy Guidance through Competitive Simulation

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    Sustainable energy systems of the future will need more than efficient, clean, low-cost, renewable energy sources; they will also need efficient price signals that motivate sustainable energy consumption as well as a better real-time alignment of energy demand and supply

    A Multi-Agent Energy Trading Competition

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    The energy sector will undergo fundamental changes over the next ten years. Prices for fossil energy resources are continuously increasing, there is an urgent need to reduce CO2 emissions, and the United States and European Union are strongly motivated to become more independent from foreign energy imports. These factors will lead to installation of large numbers of distributed renewable energy generators, which are often intermittent in nature. This trend conflicts with the current power grid control infrastructure and strategies, where a few centralized control centers manage a limited number of large power plants such that their output meets the energy demands in real time. As the proportion of distributed and intermittent generation capacity increases, this task becomes much harder, especially as the local and regional distribution grids where renewable energy generators are usually installed are currently virtually unmanaged, lack real time metering and are not built to cope with power flow inversions (yet). All this is about to change, and so the control strategies must be adapted accordingly. While the hierarchical command-and-control approach served well in a world with a few large scale generation facilities and many small consumers, a more flexible, decentralized, and self-organizing control infrastructure will have to be developed that can be actively managed to balance both the large grid as a whole, as well as the many lower voltage sub-grids. We propose a competitive simulation test bed to stimulate research and development of electronic agents that help manage these tasks. Participants in the competition will develop intelligent agents that are responsible to level energy supply from generators with energy demand from consumers. The competition is designed to closely model reality by bootstrapping the simulation environment with real historic load, generation, and weather data. The simulation environment will provide a low-risk platform that combines simulated markets and real-world data to develop solutions that can be applied to help building the self-organizing intelligent energy grid of the future

    Total photoproduction cross-section at very high energy

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    In this paper we apply to photoproduction total cross-section a model we have proposed for purely hadronic processes and which is based on QCD mini-jets and soft gluon re-summation. We compare the predictions of our model with the HERA data as well as with other models. For cosmic rays, our model predicts substantially higher cross-sections at TeV energies than models based on factorization but lower than models based on mini-jets alone, without soft gluons. We discuss the origin of this difference.Comment: 13 pages, 9 figures. Accepted for publication in EPJC. Changes concern added references, clarifications of the Soft Gluon Resummation method used in the paper, and other changes requested by the Journal referee which do not change the results of the original versio

    Multiple Interactions in Two-Photon Collisions

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    We compute cross sections for events where two pairs of partons scatter off each other in the same γγ\gamma\gamma reaction, giving rise to at least 3 high--{\mbox{pTp_T^{}}} jets. Unlike in {\mbox{ppˉp \bar p}}\ collisions we find the signal to lie well above the background from higher order QCD processes. If the usual ``eikonaliztion" assumption is correct, the signal should be readily observable at LEP2, and might already be detectable in data taken at TRISTAN.Comment: 8 pages, plain LaTeX, 2 figures (not included). A compressed PS file of the entire paper, including figures, can be obtained via anonymous ftp from ftp://phenom.physics.wisc.edu/pub/preprints/1995/madph-95-921.ps.

    The moral discourses of ‘post-crisis’ neoliberalism: a case study of Lithuania’s Labour Code reform

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    This article problematizes the neoliberal reconfiguration of labour rights in Lithuania, a newer European Union member state, in which the impacts of the global economic and financial crisis were particularly severe and where radical austerity measures were subsequently imposed. Now, after six years, in an attempt to resolve the exhaustion of previous austerity-based solutions for economic recovery, a new Labour Code is being introduced which will further weaken labour protections and labour rights. This article analyses conflicting positions in current debates over Labour Code reform. It attempts to map the mobilization of strategic discursive resources in an unfolding dialogical ‘moral’ politics of Labour Code reform in the current conjuncture of ‘post- crisis’. Theoretically, this article draws upon the seminal work of the early Soviet Marxist scholar V. N. Voloshinov in proposing a dialogical method which foregrounds the interconnections of language, class and ideology

    Next-to-Leading Order Cross Sections for Tagged Reactions

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    We extend the phase space slicing method of Giele, Glover and Kosower for performing next-to-leading order jet cross section calculations in two important ways: we show how to include fragmentation functions and how to include massive particles. These extensions allow the application of this method to not just jet cross sections but also to cross sections in which a particular final state particle, including a DD or BB-meson, is tagged.Comment: 36 pages, Latex Small corrections to text. To appear in Phys. Rev.

    Staff experiences of working in a Sexual Assault Referral Centre: the impacts and emotional tolls of working with traumatised people

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    This study considers the impacts on staff of supporting people who have reported sexual violence and attend a Sexual Assault Referral Centre (SARC). This paper focuses on the staff’s perspectives of the stresses and emotional tolls they experience including the coping mechanisms they utilise. Semi- structured interviews were conducted with 12 staff, and a focus group was held with a further four staff of a SARC. The data were examined using thematic analysis. Findings indicated that staff experienced positive emotions connected to the meaningfulness of the work and team spirit as well as a range of unpleasant emotions. Staff also reported emotional numbing, in connection to the specificity, volume and sometimes unpredictable nature of the work. Coping mechanisms used by staff focused on the supportive connection to family, nature, and other team members; the value of clinical supervision; and the avoidance of topics related to work

    Hard diffractive quarkonium hadroproduction at high energies

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    We present a study of heavy quarkonium production in hard diffractive process by the Pomeron exchange for Tevatron and LHC energies. The numerical results are computed using recent experimental determination of the diffractive parton density functions in Pomeron and are corrected by unitarity corrections through gap survival probability factor. We give predictions for single as well as central diffractive ratios. These processes are sensitive to the gluon content of the Pomeron at small Bjorken-x and may be particularly useful in studying the small-x physics. They may also be a good place to test the different available mechanisms for quarkonium production at hadron colliders.Comment: 7 pages, 3 figures, 1 table. Final version to be published in European Physical Journal

    The spin dependence of high energy proton scattering

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    Motivated by the need for an absolute polarimeter to determine the beam polarization for the forthcoming RHIC spin program, we study the spin dependence of the proton-proton elastic scattering amplitudes at high energy and small momentum transfer.We examine experimental evidence for the existence of an asymptotic part of the helicity-flip amplitude phi_5 which is not negligible relative to the largely imaginary average non-flip amplitude phi_+. We discuss theoretical estimates of r_5, essentially the ratio of phi_5 to phi_+, based upon extrapolation of low and medium energy Regge phenomenological results to high energies, models based on a hybrid of perturbative QCD and non-relativistic quark models, and models based on eikonalization techniques. We also apply the model-independent methods of analyticity and unitarity.The preponderence of evidence at available energy indicates that r_5 is small, probably less than 10%. The best available experimental limit comes from Fermilab E704:those data indicate that |r_5|<15%. These bounds are important because rigorous methods allow much larger values. In contradiction to a widely-held prejudice that r_5 decreases with energy, general principles allow it to grow as fast as ln(s) asymptotically, and some models show an even faster growth in the RHIC range. One needs a more precise measurement of r_5 or to bound it to be smaller than 5% in order to use the classical Coulomb-nuclear interference technique for RHIC polarimetry. As part of this study, we demonstrate the surprising result that proton-proton elastic scattering is self-analysing, in the sense that all the helicity amplitudes can, in principle, be determined experimentally at small momentum transfer without a knowledge of the magnitude of the beam and target polarization

    Prompt atmospheric neutrino fluxes: perturbative QCD models and nuclear effects

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    We evaluate the prompt atmospheric neutrino flux at high energies using three different frameworks for calculating the heavy quark production cross section in QCD: NLO perturbative QCD, kTk_T factorization including low-xx resummation, and the dipole model including parton saturation. We use QCD parameters, the value for the charm quark mass and the range for the factorization and renormalization scales that provide the best description of the total charm cross section measured at fixed target experiments, at RHIC and at LHC. Using these parameters we calculate differential cross sections for charm and bottom production and compare with the latest data on forward charm meson production from LHCb at 77 TeV and at 1313 TeV, finding good agreement with the data. In addition, we investigate the role of nuclear shadowing by including nuclear parton distribution functions (PDF) for the target air nucleus using two different nuclear PDF schemes. Depending on the scheme used, we find the reduction of the flux due to nuclear effects varies from 10%10\% to 50%50 \% at the highest energies. Finally, we compare our results with the IceCube limit on the prompt neutrino flux, which is already providing valuable information about some of the QCD models.Comment: 61 pages, 25 figures, 11 table
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