4,674 research outputs found

    The energy tax: who pays?

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    An examination of the problems that arise when the government attempts to formulate economic policies having multiple objectives--in this case, reducing the nation's energy consumption and its associated social costs while ensuring that no particular region or income group bears a disproportionate share of the burden.Power resources ; Taxation

    The Cost of Renewable Power Integration and the Transition to Low Carbon Emissions for Japan’s Energy Industry

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    An earthquake on March 11, 2011 caused catastrophic damage to Eastern Japan’s people, infrastructure and energy markets. This event signified the need for dramatic change towards sustainable energy. The recent Paris Accords on climate change has provided a framework for sustainability development towards CO2 emission reductions. Therefore, the experiment in this paper models the proposed increase to ~23 percent renewable generation as well as modest decreases in fossil fuel generation relative to generation demand and emissions reductions. The results of this paper will demonstrate that there is a ~56 percent chance under randomized input scenarios that cost increases remain within consumer tolerance levels. Further compounding this analysis, this probability falls to ~34 percent when considering targeted emissions levels. The incidence of these probabilities can be dramatically impacted by an overall decrease in the commodity inputs for fuel prices and an increase in costs levied against carbon emissions

    Dark matter scenarios in a constrained model with Dirac gauginos

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    We perform the first analysis of Dark Matter scenarios in a constrained model with Dirac Gauginos. The model under investigation is the Constrained Minimal Dirac Gaugino Supersymmetric Standard model (CMDGSSM) where the Majorana mass terms of gauginos vanish. However, RR-symmetry is broken in the Higgs sector by an explicit and/or effective BÎĽB_\mu-term. This causes a mass splitting between Dirac states in the fermion sector and the neutralinos, which provide the dark matter candidate, become pseudo-Dirac states. We discuss two scenarios: the universal case with all scalar masses unified at the GUT scale, and the case with non-universal Higgs soft-terms. We identify different regions in the parameter space which fullfil all constraints from the dark matter abundance, the limits from SUSY and direct dark matter searches and the Higgs mass. Most of these points can be tested with the next generation of direct dark matter detection experiments.Comment: 28 pages, 11 figures; v2: minor changes, title modified; matches published versio

    Establishing Consensus Turbulence Statistics for Hot Subsonic Jets

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    Many tasks in fluids engineering require knowledge of the turbulence in jets. There is a strong, although fragmented, literature base for low order statistics, such as jet spread and other meanvelocity field characteristics. Some sources, particularly for low speed cold jets, also provide turbulence intensities that are required for validating Reynolds-averaged Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) codes. There are far fewer sources for jet spectra and for space-time correlations of turbulent velocity required for aeroacoustics applications, although there have been many singular publications with various unique statistics, such as Proper Orthogonal Decomposition, designed to uncover an underlying low-order dynamical description of turbulent jet flow. As the complexity of the statistic increases, the number of flows for which the data has been categorized and assembled decreases, making it difficult to systematically validate prediction codes that require high-level statistics over a broad range of jet flow conditions. For several years, researchers at NASA have worked on developing and validating jet noise prediction codes. One such class of codes, loosely called CFD-based or statistical methods, uses RANS CFD to predict jet mean and turbulent intensities in velocity and temperature. These flow quantities serve as the input to the acoustic source models and flow-sound interaction calculations that yield predictions of far-field jet noise. To develop this capability, a catalog of turbulent jet flows has been created with statistics ranging from mean velocity to space-time correlations of Reynolds stresses. The present document aims to document this catalog and to assess the accuracies of the data, e.g. establish uncertainties for the data. This paper covers the following five tasks: Document acquisition and processing procedures used to create the particle image velocimetry (PIV) datasets. Compare PIV data with hotwire and laser Doppler velocimetry (LDV) data published in the open literature. Compare different datasets acquired at roughly the same flow conditions to establish uncertainties. Create a consensus dataset for a range of hot jet flows, including uncertainty bands. Analyze this consensus dataset for self-consistency and compare jet characteristics to those of the open literature. One final objective fulfilled by this work was the demonstration of a universal scaling for the jet flow fields, at least within the region of interest to aeroacoustics. The potential core length and the spread rate of the half-velocity radius were used to collapse of the mean and turbulent velocity fields over the first 20 jet diameters in a highly satisfying manner
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