101 research outputs found
Energy in a Finite World: Paths to a Sustainable Future (Volume 1)
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
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
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
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 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
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 at incident energies from 1 to 2 AGeV
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 Ni with Ni nuclei. The transverse
mass () spectra have been studied as a function of rapidity at a beam
energy 1.93 AGeV. The 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)
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
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
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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