12,813 research outputs found

    Waldschmidt constants for Stanley-Reisner ideals of a class of graphs

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    In the present note we study Waldschmidt constants of Stanley-Reisner ideals of a hypergraph and a graph with vertices forming a bipyramid over a planar n-gon. The case of the hypergraph has been studied by Bocci and Franci. We reprove their main result. The case of the graph is new. Interestingly, both cases provide series of ideals with Waldschmidt constants descending to 1. It would be interesting to known if there are bounded ascending sequences of Waldschmidt constants.Comment: 7 pages, 2 figure

    Energy and economic analysis of a residential Solar Organic Rankine plant

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    To answer the actual energy, water, economic, social and environmental challenges, renewable, distributed power plants need to be developed. Among renewables, solar tri-generative power plants can be a solution where there is big low temperature heating/cooling demand and small electricity demand, like many residential and industrial utilities. In this case, solar thermal plants can produce thermal energy with low cost and high efficiency. The higher temperature heat not needed by the user can be exploited via Organic Rankine Cycle to produce electrical energy and desalinized water via reverse osmosis. The present paper analyses, via TRNSYS simulation, a system composed of 50 m2 of CPC solar thermal collectors, 3 m3 of thermal storage, a synthetic heat transfer fluid, 3 kWe ORC, 8 kWth absorber, 200 l/h direct reverse osmosis desalination device. The system is able to produce power, heating/cooling and fresh water needs for a residential house. Although system’s components are well known technologies, the integration to a efficient and economic working system is still a challenge. Global energy and economic analyses have been performed. Low temperature heating/cooling terminals allow to increase not only the use of thermal energy but also the ORCand absorber efficiency. ORC-Absorber configuration and relative fluids and temperatures are central. Government support and/or cost reduction of 30% are necessary to have positive NPV and acceptable PBT and IR

    Experimental tests to recover the photovoltaic power by battery system

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    The uncertainty and variability of the Renewable Energy Sources (RES) power plants within the power grid is an open issue. The present study focuses on the use of batteries to overcome the limitations associated with the photovoltaic inverter operation, trying to maximize the global energy produced. A set of switches, was placed between a few photovoltaic modules and a commercial inverter, capable to change configuration of the plant dynamically. Such system stores the power that the inverter is not able to let into the grid inside batteries. At the base of this optimization, there is the achievement of two main configurations in which the batteries and the photovoltaic modules are electrically connected in an appropriate manner as a function of inverter efficiency and thus solar radiation. A control board and the relative program, to change the configuration, was designed and implemented, based on the value of the measured radiation, current, batteries voltage, and calculated inverter efficiency. Finally from the cost and impact analysis we can say that, today the technology of lithium batteries, for this application, is still too expensive in comparison with lead-acid batteries

    TRT Alignment For SR1 Cosmics and Beyond

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    We present an algorithm for the alignment of the ATLAS Inner Detector, developed for the analysis of cosmics data taken with the ID barrel in SR1 in the summer of 2006. Our results include a comparison of the relative SCT-TRT alignment with survey measurements, a study of the alignment of SCT and TRT module positions and TRT module deformations, and a comparison of the `local' and `global' methods for alignment

    Intervista agli esperti di comunicazione intergenerazionale

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    Nell'intervista si illustrano le origini dell’interesse per il tema della comunicazione intergenerazionale e i successivi sviluppi delle ricerche/sperimentazioni di turismo intergenerazionale in Italia, specificandone le motivazioni, i contesti, le reti territoriali, i target e i risultati più salienti. Si evidenzia la stretta relazione tra ricerca, formazione e progettualità presentando l'innovativo profilo professionale del Manager in ambiente e turismo intergenerazionale

    Probabilistic Particle Flow Algorithm for High Occupancy Environment

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    Algorithms based on the particle flow approach are becoming increasingly utilized in collider experiments due to their superior jet energy and missing energy resolution compared to the traditional calorimeter-based measurements. Such methods have been shown to work well in environments with low occupancy of particles per unit of calorimeter granularity. However, at higher instantaneous luminosity or in detectors with coarse calorimeter segmentation, the overlaps of calorimeter energy deposits from charged and neutral particles significantly complicate particle energy reconstruction, reducing the overall energy resolution of the method. We present a technique designed to resolve overlapping energy depositions of spatially close particles using a statistically consistent probabilistic procedure. The technique is nearly free of ad-hoc corrections, improves energy resolution, and provides new important handles that can improve the sensitivity of physics analyses: the uncertainty of the jet energy on an event-by-event basis and the estimate of the probability of a given particle hypothesis for a given detector response. When applied to the reconstruction of hadronic jets produced in the decays of tau leptons using the CDF-II detector at Fermilab, the method has demonstrated reliable and robust performance.Comment: Accepted by Nuclear Instruments and Methods

    Cultivating diversity and food quality. Proceedings of Diversifood EU Forum, Brussels, 11 April 2018

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    To tackle this issue, Diversifood team organised a forum with policy makers and stakeholders on the 11th of April 2018, in Brussels. Diversifood’s aim is to share results and key lessons including new approaches for the management of cultivated biodiversity, for plant breeding for sustainable farming systems, and new relationships among actors of food systems. In the afternoon, there was time for discussion, knowledge sharing, collecting feedback and extending current policies to include cultivating diversity and food quality (for FP9, CAP 2020, The outputs of this workshop will feed Diversifood’s final recommendations. The forum was kindly hosted by the European Committee of the Regions (Rue Belliard/Belliardstraat 101, 1040 Brussels)

    Hydrogen vs. Battery in the long-term operation. A comparative between energy management strategies for hybrid renewable microgrids

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    The growth of the world’s energy demand over recent decades in relation to energy intensity and demography is clear. At the same time, the use of renewable energy sources is pursued to address decarbonization targets, but the stochasticity of renewable energy systems produces an increasing need for management systems to supply such energy volume while guaranteeing, at the same time, the security and reliability of the microgrids. Locally distributed energy storage systems (ESS) may provide the capacity to temporarily decouple production and demand. In this sense, the most implemented ESS in local energy districts are small–medium-scale electrochemical batteries. However, hydrogen systems are viable for storing larger energy quantities thanks to its intrinsic high mass-energy density. To match generation, demand and storage, energy management systems (EMSs) become crucial. This paper compares two strategies for an energy management system based on hydrogen-priority vs. battery-priority for the operation of a hybrid renewable microgrid. The overall performance of the two mentioned strategies is compared in the long-term operation via a set of evaluation parameters defined by the unmet load, storage efficiency, operating hours and cumulative energy. The results show that the hydrogen-priority strategy allows the microgrid to be led towards island operation because it saves a higher amount of energy, while the battery-priority strategy reduces the energy efficiency in the storage round trip. The main contribution of this work lies in the demonstration that conventional EMS for microgrids’ operation based on battery-priority strategy should turn into hydrogen-priority to keep the reliability and independence of the microgrid in the long-term operation
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