7,196 research outputs found

    Market Power in Mixed Hydro-Thermal Electric Systems

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    This paper shows that, unlike what has been found in other papers, a hydro reservoir is an effective tool to exercise market power. Its appealing as a tool is enhanced by the fact that there is no need to constrain total hydro production - a practice too easy to detect -; it suffices to distort the intertemporal allocation of hydro production over time. A hydro-producer may increase his profits by exploiting differences in price elasticity of demand across periods, allocating too little supply to less elastic periods and too much to more elastic periods. Differences in price elasticity across periods may result from the combination of a fluctuating market demand and capacity or transmission constraints that bind intermitently. This hydro scheduling decision is only available to hydro producers as thermal generators are not able to "store electric power" and decide when to sell it. It is also shown that total hydro production is not a sufficient indicator of market power being exercised as hydro producers may exercise market power even when all the water available in the\reservoir is used. The real indicator of market power being exercised is the hydro scheduling strategy usedUtilities; Market Power; Scheduling of Hydro-Reservoirs.

    Reaction cross sections for proton scattering from stable and unstable nuclei based on a microscopic approach

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    Microscopic optical model potential results for reaction cross sections of proton elastic scattering are presented. The applications cover the 10-1000 MeV energy range and consider both stable and unstable nuclei. The study is based on in-medium g-matrix full-folding optical model approach with the appropriate relativistic kinematic corrections needed for the higher energy applications. The effective interactions are based on realistic NN potentials supplemented with a separable non-Hermitian term to allow optimum agreement with current NN phase-shift analyzes, particularly the inelasticities above pion production threshold. The target ground-state densities are obtained from Hartree-Fock-Bogoliubov calculations based on the finite range, density dependent Gogny force. The evaluated reaction cross sections for proton scattering are compared with measurements and their systematics is analyzed. A simple function of the total cross sections in terms of the atomic mass number is observed at high energies. At low energies, however, discrepancies with the available data are observed, being more pronounced in the lighter systems.Comment: 11 pages, 4 figures, submitted to Phys. Rev.

    Sensitivity of nucleon-nucleus scattering to the off-shell behavior of on-shell equivalent NN potentials

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    The sensitivity of nucleon-nucleus elastic scattering to the off-shell behavior of realistic nucleon-nucleon interactions is investigated when on-shell equivalent nucleon-nucleon potentials are used. The study is based on applications of the full-folding optical model potential for an explicit treatment of the off-shell behavior of the nucleon-nucleon effective interaction. Applications were made at beam energies between 40 and 500 MeV for proton scattering from 40Ca and 208Pb. We use the momentum-dependent Paris potential and its local on-shell equivalent as obtained with the Gelfand-Levitan and Marchenko inversion formalism for the two nucleon Schroedinger equation. Full-folding calculations for nucleon-nucleus scattering show small fluctuations in the corresponding observables. This implies that off-shell features of the NN interaction cannot be unambiguously identified with these processes. Inversion potentials were also constructed directly from NN phase-shift data (SM94) in the 0-1.3 GeV energy range. Their use in proton-nucleus scattering above 200 MeV provide a superior description of the observables relative to those obtained from current realistic NN potentials. Limitations and scope of our findings are presented and discussed.Comment: 17 pages tightened REVTeX, 8 .ps figures, submitted to Phys. Rev.

    Modelo de cuantificaci贸n del consumo energ茅tico en edificaci贸n

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    The research conducted in this paper focuses on the generation of a model for the quantification of energy consumption in building. This is to be done through one of the most relevant environmental impact indicators associated with weight per m2 of construction, as well as the energy consumption resulting from the manufacturing process of materials used in building construction. The practical application of the proposed model on different buildings typologies in Seville, will provide information regarding the building materials, the subsystems and the most relevant construction elements. Hence, we will be able to observe the impact the built surface has on the environment. The results obtained aim to reference the scientific community, providing quantitative data comparable to other types of buildings and geographical areas. Furthermore, it may also allow the analysis and the characterization of feasible solutions to reduce the environmental impact generated by the different materials, subsystems and construction elements commonly used in the different building types defined in this study.La investigaci贸n realizada en el presente trabajo plantea la generaci贸n de un modelo de cuantificaci贸n del consumo energ茅tico en edificaci贸n, a trav茅s de uno de los indicadores de impacto ambiental m谩s relevantes asociados al peso por m2 de construcci贸n, el consumo energ茅tico derivado del proceso de fabricaci贸n de los materiales de construcci贸n empleados en edificaci贸n. La aplicaci贸n pr谩ctica del modelo propuesto sobre diferentes tipolog铆as edificatorias en Sevilla aportar谩 informaci贸n respecto a los materiales de construcci贸n, subsistemas y elementos constructivos m谩s impactantes, permitiendo visualizar la influencia que presenta la superficie construida en cuanto al impacto ambiental generado. Los resultados obtenidos pretenden servir de referencia a la comunidad cient铆fica, aportando datos num茅ricos que podr谩n ser comparados en otras tipolog铆as y 谩mbitos geogr谩ficos, a la vez que permitir谩n analizar y precisar mejoras en cuanto al impacto ambiental generado por los diferentes materiales, subsistemas y elementos constructivos habitualmente utilizados en las tipolog铆as edificatorias definidas

    Non-Gaussian Geostatistical Modeling using (skew) t Processes

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    We propose a new model for regression and dependence analysis when addressing spatial data with possibly heavy tails and an asymmetric marginal distribution. We first propose a stationary process with tt marginals obtained through scale mixing of a Gaussian process with an inverse square root process with Gamma marginals. We then generalize this construction by considering a skew-Gaussian process, thus obtaining a process with skew-t marginal distributions. For the proposed (skew) tt process we study the second-order and geometrical properties and in the tt case, we provide analytic expressions for the bivariate distribution. In an extensive simulation study, we investigate the use of the weighted pairwise likelihood as a method of estimation for the tt process. Moreover we compare the performance of the optimal linear predictor of the tt process versus the optimal Gaussian predictor. Finally, the effectiveness of our methodology is illustrated by analyzing a georeferenced dataset on maximum temperatures in Australi