33,035 research outputs found

    Middleware architectures for the smart grid: A survey on the state-of-the-art, taxonomy and main open issues

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    The integration of small-scale renewable energy sources in the smart grid depends on several challenges that must be overcome. One of them is the presence of devices with very different characteristics present in the grid or how they can interact among them in terms of interoperability and data sharing. While this issue is usually solved by implementing a middleware layer among the available pieces of equipment in order to hide any hardware heterogeneity and offer the application layer a collection of homogenous resources to access lower levels, the variety and differences among them make the definition of what is needed in each particular case challenging. This paper offers a description of the most prominent middleware architectures for the smart grid and assesses the functionalities they have, considering the performance and features expected from them in the context of this application domain

    Wormholes in de Sitter branes

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    In this work we present a class of geometries which describes wormholes in a Randall-Sundrum brane model, focusing on de Sitter backgrounds. Maximal extensions of the solutions are constructed and their causal structures are discussed. A perturbative analysis is developed, where matter and gravitational perturbations are studied. Analytical results for the quasinormal spectra are obtained and an extensive numerical survey is conducted. Our results indicate that the wormhole geometries presented are stable.Comment: 10 pages, 7 figure

    The Brutal Murder of George J. Bushman

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    In the fall of 1918 there occurred in Adams County a singularly brutal murder that brought the County and the town of Gettysburg to a shocked standstill. The tentacles of this event would reach into four Pennsylvania counties: Adams, Cumberland, Dauphin, and Philadelphia, and eventually the Pennsylvania Supreme Court. The investigation of the crime and the trial of the perpetrators involved so many public officials and families, as well as the extended judicial system and geographical locations within and without the County, that we have included a Cast of Characters and Locations to assist the reader in following this convoluted tale

    Biodiesel: Tomorrow\u27s Fuel, Today\u27s Solution

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    Study of physical and chemical properties of biodiesel fuels derived from poultry and plant fats

    Isothermal method for volume determination

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    Isothermal volume measurements for weight computation on monkey

    Conductance of nano-systems with interactions coupled via conduction electrons: Effect of indirect exchange interactions

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    A nano-system in which electrons interact and in contact with Fermi leads gives rise to an effective one-body scattering which depends on the presence of other scatterers in the attached leads. This non local effect is a pure many-body effect that one neglects when one takes non interacting models for describing quantum transport. This enhances the non-local character of the quantum conductance by exchange interactions of a type similar to the RKKY-interaction between local magnetic moments. A theoretical study of this effect is given assuming the Hartree-Fock approximation for spinless fermions in an infinite chain embedding two scatterers separated by a segment of length L\_c. The fermions interact only inside the two scatterers. The dependence of one scatterer onto the other exhibits oscillations which decay as 1/L\_c and which are suppressed when L\_c exceeds the thermal length L\_T. The Hartree-Fock results are compared with exact numerical results obtained with the embedding method and the DMRG algorithm
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