101 research outputs found

    Energy in a Finite World: Paths to a Sustainable Future (Volume 1)

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    This volume summarizes the results of a seven-year study conducted at the International Institute for Applied Systems Analysis (IIASA) in Laxenburg, Austria. The work, which involved over 140 scientists from 20 countries, aimed to provide new and critical insights into the international long-term dimensions of the energy problem. Given this objective, the 50-year period from 1980 to 2030 was analyzed in detail, though parts of the study looked even further into the future. Geographically, all countries of the world were included -- developed and developing, market and centrally planned economies. The picture that emerges is one of a world facing, during the 1980-2030 period, what is anticipated to be the steepest ever increase in its population. At the same time, the developing regions of the world, in which most of this population growth will occur, will be trying to close the economic gap separating them from the developed regions. Despite the resultant strains on the world's physical resources, on its institutions, and on human ingenuity, the conclusion is that the physical resources and the human potential exist to provide the energy for a 2030 world that is more prosperous than the world of today while supporting a population double that of 1975. Moreover, if resources are developed judiciously and strategically, the world of 2030 could be at the threshold of a critical and ultimately necessary transition from a global energy system based on depletable fossil fuels to one based on nondepletable, sustainable resources. The companion volume, "Energy in a Finite World, Vol. 2, A Global Systems Analysis", also published by Ballinger, presents the study findings in detail, with the references and qualifications typical of a comprehensive scientific work. ER-81-4, "Energy in a Finite World: Executive Summary", by Alan McDonald, provides a concise summary of the study and is available from IIASA

    The Impact of Waste Heat Release on Simulated Global Climate

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    The general circulation model of the United Kingdom Meteorological Office (UKMO) has been used to investigate the effects of thermal pollution from large-scale energy parks on climate. Two scenarios, with different locations for the energy parks, have been considered. Emphasis was placed on finding an estimate of model variability (on the basis of three control cases), so that the significance of the change caused by the heat release could be evaluated. As far as the model climatology is concerned, significant changes were produced by the energy parks. In addition, the location of the parks influenced the model response. The presently available models do not simulate climate in a completely realistic way so that the results of sensitivity experiments must be interpreted very carefully. At the present stage it can be said that the results call for further investigations

    Enhanced LoD concepts for virtual 3D city models

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    Virtual 3D city models contain digital three dimensional representations of city objects like buildings, streets or technical infrastructure. Because size and complexity of these models continuously grow, a Level of Detail (LoD) concept effectively supporting the partitioning of a complete model into alternative models of different complexity and providing metadata, addressing informational content, complexity and quality of each alternative model is indispensable. After a short overview on various LoD concepts, this paper discusses the existing LoD concept of the CityGML standard for 3D city models and identifies a number of deficits. Based on this analysis, an alternative concept is developed and illustrated with several examples. It differentiates between first, a Geometric Level of Detail (GLoD) and a Semantic Level of Detail (SLoD), and second between the interior building and ist exterior shell. Finally, a possible implementation of the new concept is demonstrated by means of an UML model

    A comparison study on jacket substructures for offshore wind turbines based on optimization

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    The structural optimization problem of jacket substructures for offshore wind turbines is commonly regarded as a pure tube dimensioning problem, minimizing the entire mass of the structure. However, this approach goes along with the assumption that the given topology is fixed in any case. The present work contributes to the improvement of the state of the art by utilizing more detailed models for geometry, costs, and structural design code checks. They are assembled in an optimization scheme, in order to consider the jacket optimization problem from a different point of view that is closer to practical applications. The conventional mass objective function is replaced by a sum of various terms related to the cost of the structure. To address the issue of high demand of numerical capacity, a machine learning approach based on Gaussian process regression is applied to reduce numerical expenses and enhance the number of considered design load cases. The proposed approach is meant to provide decision guidance in the first phase of wind farm planning. A numerical example for a National Renewable Energy Laboratory (NREL) 5&thinsp;MW turbine under FINO3 environmental conditions is computed by two effective optimization methods (sequential quadratic programming and an interior-point method), allowing for the estimation of characteristic design variables of a jacket substructure. In order to resolve the mixed-integer problem formulation, multiple subproblems with fixed-integer design variables are solved. The results show that three-legged jackets may be preferable to four-legged ones under the boundaries of this study. In addition, it is shown that mass-dependent cost functions can be easily improved by just considering the number of jacket legs to yield more reliable results.</p

    Stopping and Radial Flow in Central 58Ni + 58Ni Collisions between 1 and 2 AGeV

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    The production of charged pions, protons and deuterons has been studied in central collisions of 58Ni on 58Ni at incident beam energies of 1.06, 1.45 and 1.93 AGeV. The dependence of transverse-momentum and rapidity spectra on the beam energy and on the centrality of the collison is presented. It is shown that the scaling of the mean rapidity shift of protons established for AGS and SPS energies is valid down to 1 AGeV. The degree of nuclear stopping is discussed; the IQMD transport model reproduces the measured proton rapidity spectra for the most central events reasonably well, but does not show any sensitivity between the soft and the hard equation of state (EoS). A radial flow analysis, using the midrapidity transverse-momentum spectra, delivers freeze-out temperatures T and radial flow velocities beta_r which increase with beam energy up to 2 AGeV; in comparison to existing data of Au on Au over a large range of energies only beta_r shows a system size dependence

    K^+ production in the reaction 58Ni+58Ni^{58}Ni+^{58}Ni at incident energies from 1 to 2 AGeV

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    Semi-inclusive triple differential multiplicity distributions of positively charged kaons have been measured over a wide range in rapidity and transverse mass for central collisions of 58^{58}Ni with 58^{58}Ni nuclei. The transverse mass (mtm_t) spectra have been studied as a function of rapidity at a beam energy 1.93 AGeV. The mtm_t distributions of K^+ mesons are well described by a single Boltzmann-type function. The spectral slopes are similar to that of the protons indicating that rescattering plays a significant role in the propagation of the kaon. Multiplicity densities have been obtained as a function of rapidity by extrapolating the Boltzmann-type fits to the measured distributions over the remaining phase space. The total K^+ meson yield has been determined at beam energies of 1.06, 1.45, and 1.93 AGeV, and is presented in comparison to existing data. The low total yield indicates that the K^+ meson can not be explained within a hadro-chemical equilibrium scenario, therefore indicating that the yield does remain sensitive to effects related to its production processes such as the equation of state of nuclear matter and/or modifications to the K^+ dispersion relation.Comment: 24 pages Latex (elsart) 7 PS figures to be submitted to Nucl. Phys

    Nuclear energy in the public sphere: Anti-nuclear movements vs. industrial lobbies in Spain (1962-1979)

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    The final publication is available at Springer via http://dx.doi.org/10.1007/s11024-014-9263-0This article examines the role of the Spanish Atomic Forum as the representative of the nuclear sector in the public arena during the golden years of the nuclear power industry from the 1960s to 1970s. It focuses on the public image concerns of the Spanish nuclear lobby and the subsequent information campaigns launched during the late 1970s to counteract demonstrations by the growing and heterogeneous anti-nuclear movement. The role of advocacy of nuclear energy by the Atomic Forum was similar to that in other countries, but the situation in Spain had some distinguishing features. Anti-nuclear protest in Spain peaked in 1978 paralleling the debates of a new National Energy Plan in Congress, whose first draft had envisaged a massive nuclearization of the country. We show how the approval of the Plan in July 1979, with a significant reduction in the nuclear energy component, was influenced by the anti-nuclear protest movements in Spain. Despite the efforts of the Spanish Atomic Forum to counter its message, the anti-nuclear movement was strengthened by reactions to the Three Mile Island accident in March 1979

    Carbon Dioxide Emissions in a Methane Economy

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    Increasing reliance on natural gas (methane) to meet global energy demands holds implications for atmospheric CO2 concentrations. Analysis of these implications is presented, based on a logistic substitution model viewing energy technologies like biological species invading an econiche and substituting in case of superiority for existing species. This model suggests gas will become the dominant energy source and remain so for 50 years, peaking near 70 percent of world supply. Two scenarios of energy demand are explored, one holding per capita consumption at current levels, the second raising the global average in the year 2100 to the current U.S. level. In the first ("efficiency") scenario concentrations peak about 450 ppm, while in the second ("long wave") they near 600 ppm. Although projected CO2 concentrations in a "methane economy" are low in relation to other scenarios, the projections confirm that global climate warming is likely to be a major planetary concern throughout the twenty-first century. A second finding is that data on past growth of world per capita energy consumption group neatly into two pulses consistent with long-wave theories in economics

    Central Collisions of Au on Au at 150, 250 and 400 A MeV

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    Collisions of Au on Au at incident energies of 150, 250 and 400 A MeV were studied with the FOPI-facility at GSI Darmstadt. Nuclear charge (Z < 16) and velocity of the products were detected with full azimuthal acceptance at laboratory angles of 1-30 degrees. Isotope separated light charged particles were measured with movable multiple telescopes in an angular range of 6-90 degrees. Central collisions representing about 1 % of the reaction cross section were selected by requiring high total transverse energy, but vanishing sideflow. The velocity space distributions and yields of the emitted fragments are reported. The data are analysed in terms of a thermal model including radial flow. A comparison with predictions of the Quantum Molecular Model is presented.Comment: LateX text 62 pages, plus six Postscript files with a total of 34 figures, accepted by Nucl.Phys.
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