Llibres / Capítols de llibre (Matemàtica)

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    Open Access
    METMA X. Proceedings of the 10th International Workshop on Spatio-Temporal Modelling. Lleida (Spain) 1-3 June 2022
    (Edicions i Publicacions de la Universitat de Lleida, 2022) Comas Rodríguez, Carles; Mateu, Jorge
    METMA workshop comes to its 10th edition meaning 20 years of history since its first version held in Castellon (Spain) back in 2001. Since then, its location has been moving along through Spain, Portugal, France and Italy, and has become an international reference for space-time statistics. This edition was aimed to be held in 2020 but was postponed to 2022 due to covid pandemic, and thus it somehow will be remembered as the covid-time edition. The purpose of this conference is to promote the development and application of spatial, temporal, and mainly spatio-temporal statistical methods to different fields related to the environment. The general aim is to bring together practitioners and researchers of different areas and countries all over the world. Cross-disciplinary actions to solve environmental problems are very welcome. The scientific program (http://www.metma-x.udl.cat/) features sessions covering topics on the latest advancements in theory, methods and applications, and presentations from keynotes, invited and a number of oral contributed and posters completes the program.
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    Open Access
    Notes sobre combinatòria: matemàtica discreta
    (Paperkite Editorial, 2002) Gimbert i Quintilla, Joan; Moreno Chiral, Ramiro; Valls Marsal, Magda
    Aquestes notes pretenen ser una introducció a la Combinatòria Enumerativa, la qual s'ocupa dels problemes de recompte. Els continguts d'aquestes notes estan estructurats en dos capítols, un dedicat als principis, objectes i nombres combinatoris bàsics i l'altre centrat en les relacions de recurrència. Per tal de facilitar l'assimilació dels conceptes i l'adquisició de certes tècniques combinatòries, hem inclòs un bon nombre d'exemples i una variada col·lecció de problemes amb les seves corresponents solucions numèriques.
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    Open Access
    Improving a smart metering system using elliptic curves and removing the trusted dealer
    (2018) Garra Oronich, Ricard; Martínez Rodríguez, Santi; Miret, Josep M. (Josep Maria); Sebé Feixas, Francesc
    Fine-grained electricity consumption information has been proven to allow to infer people’s habits from their consumption patterns. Hence, smart metering systems need a secure way to regularly transmit the electricity consumption to the supplier in such a way that the privacy of customers is preserved. Several proposals can be found in the literature. Some of them, classified as aggregative solutions, organize the meters into groups and employ homomorphic cryptography in such a way that the supplier only obtains the aggregated consumption values of the meters in each group. In this paper we propose a technique which allows to remove the presence of a trusted dealer in one of the most efficient current proposals. Furthermore, we increase the overall performance of the resulting system by employing elliptic curve cryptography. The resulting system only requires a single message sent from each smart meter to its substation, without needing the meters to communicate among them. With the use of elliptic curve cryptography, the only relevant computation that the smart meters need to perform is a single elliptic curve point multiplication by a scalar. The system has been proven to be feasible and practical even for large neigborhoods including several thousands of meters.