Clustering of extreme events created by multiple correlated maxima

We consider stochastic processes arising from dynamical systems by evaluating an observable function along the orbits of the system. The novelty is that we will consider observables achieving a global maximum value (possible infinite) at multiple points with special emphasis for the case where these maximal points are correlated or bound by belonging to the same orbit of a certain chosen point. These multiple correlated maxima can be seen as a new mechanism creating clustering. We recall that clustering was intimately connected with periodicity when the maximum was achieved at a single point. We will study this mechanism for creating clustering and will address the existence of limiting Extreme Value Laws, the repercussions on the value of the Extremal Index, the impact on the limit of Rare Events Points Processes, the influence on clustering patterns and the competition of domains of attraction. We also consider briefly and for comparison purposes multiple uncorrelated maxima. The systems considered include expanding maps of the interval such as Rychlik maps but also maps with an indifferent fixed point such as Manneville-Pommeau maps

Extreme Value Laws for dynamical systems with countable extremal sets

We consider stationary stochastic processes arising from dynamical systems by evaluating a given observable along the orbits of the system. We focus on the extremal behaviour of the process, which is related to the entrance in certain regions of the phase space, which correspond to neighbourhoods of the maximal set $\mathcal M$, i.e. the set of points where the observable is maximised. The main novelty here is the fact that we consider that the set $\mathcal M$ may have a countable number of points, which are associated by belonging to the orbit of a certain point, and may have accumulation points. In order to prove the existence of distributional limits and study the intensity of clustering, given by the Extremal Index, we generalise the conditions previously introduced in \cite{FFT12,FFT15}.Comment: arXiv admin note: text overlap with arXiv:1505.0155

Solvatation du thorium par les fluorures en milieu sel fondu à haute température : application au procédé d'extraction réductrice pour le concept MSFR

The molten salt fast reactor (MSFR) is one of the six nuclear reactor concepts retained during the Forum GEN IV in 2001. The particularity of this concept is to use a liquid fuel consisting of a molten salt, LiF-ThF₄-UF₄ /UF ₃ (77-19-4 mol%) and to have an integrated spent fuel treatment process. This treatment consists of successive chemical separation steps based on redox and acid-base properties of the elements produced in the reactor by nuclear reactions: soluble and gaseous fission products, metals elements and soluble minor actinides. One of the major steps of the treatment method is a reducing extraction which consists to contact the molten salt and a liquid metal, bismuth, containing the reducing element, lithium. This step allows separating the minor actinides and lanthanides. Minor actinides are reintroduced in the nuclear reactor to be burned while the lanthanides are confined in deep storage.The work in this thesis had two objectives: (i) assess the feasibility of reducing extraction of actinides and lanthanides, a step that had previously only been validated on the basis of thermodynamic calculations and (ii) study the chemistry of molten fluoride salts (and especially the fuel salt) by developing a methodology for the determination of fundamental data such as the activity coefficients in fluorides media, coefficients activities which quantify the solvation properties.To experimentally realize a reducing extraction, the first step is to prepare a metal layer of liquid Bi-Li with predefined composition. An electrolysis technique in molten salt LiCl-LiF at 550°C was chosen to achieve these metal solutions. We have shown that only this molten medium could be used for the manufacture of such metal alloys. Extraction tests were then carried out by contact between LiF-ThF₄ (with UF₄ and NdF ₃ are introduced to simulate respectively the actinides and lanthanides) and Bi-Li at 650°C. The main results show that the extraction of neodymium and uranium was obtained with yields of around 3% and 15% respectively in the best conditions. These values are low compared to previous thermodynamic calculations. Low efficiency of the extraction is due to a simultaneous extraction of thorium in the liquid metal phase which forms intermetallic compounds at the metal/salt interphase and blocks the transfer.Methods have been developed to achieve fundamental data that are lacking in molten fluoride medium, in particularly the solvation properties. Speciation of some metallic cations by fluoride ions with high temperature was particularly studied and calculation of complexation constants by simulated experimental results was done. Carried out for two lanthanides, neodymium and lanthanum, two actinides, thorium and uranium, and also for a transition metal, nickel, this study achieves to calculate the activity coefficients of these elements in different fluoride molten salt. The study of the speciation of thorium was an important step to understand the chemistry of the fuel salt LiF-ThF₄. We were able to calculate the activity coefficient of the fluoride ion in this environment at 650°C.Finally, all of this work allows giving a first estimate of the reactivity of each element of the periodic table (present in the nuclear reactor after operation) at each stage of the treatment of the spent fuel salt.Le réacteur à sels fondus rapides (MSFR) est un des six concepts de réacteur nucléaire retenu lors du Forum Génération IV en 2001. La particularité de ce concept est d'utiliser un combustible liquide constitué d'un sel fondu, LiF-ThF₄-UF₄/UF3₃ (77-19-4 mol%) et d'intégrer un procédé de traitement du sel usé. Ce traitement est constitué d'étapes successives de séparation chimiques basées sur les propriétés redox et acido-basiques des éléments produits dans le réacteur par des réactions nucléaires : produits de fission solubles et gazeux, éléments métalliques et actinides mineurs solubles. L'une des étapes majeures du procédé de traitement est une extraction réductrice qui consiste à mettre en contact le sel fondu et un métal liquide, le bismuth, contenant un élément réducteur, le lithium. Cette étape permet notamment de séparer les actinides mineurs des lanthanides. Les actinides mineurs sont réintroduits dans le réacteur nucléaire afin d'y être brûler alors que les lanthanides seront confinés en stockage profond.Le travail réalisé au cours de cette thèse avait deux objectifs : (i) vérifier la faisabilité de l'extraction réductrice des actinides et des lanthanides, étape qui avait été validée au préalable uniquement sur la base de calculs thermodynamiques et (ii) étudier la chimie des sels fluorures fondus (et notamment le sel combustible LiF-ThF₄-UF₄) en développant une méthodologie pour la détermination de données fondamentales telles que les coefficients d'activité dans les milieux fluorures, coefficients qui quantifient les propriétés de solvatation.La première étape pour réaliser expérimentalement une extraction réductrice consiste à préparer une nappe métallique de Bi-Li liquide de composition pré-définie. Une technique d'électrolyse en milieu LiCl-LiF fondu à 550°C a été retenue pour réaliser ces solutions métalliques. Nous avons montré que seul ce milieu fondu pouvait être utilisé pour la fabrication de ces alliages métalliques. Des tests d'extraction ont ensuite été réalisés par contact entre LiF-ThF₄ (dans lequel sont introduits UF₄ et NdF ₃ pour simuler respectivement les actinides et les lanthanides) et Bi-Li à 650°C. Les principaux résultats montrent que l'extraction du néodyme et de l'uranium a été obtenue avec des rendements respectivement de l'ordre de 3% et 15% dans les meilleures conditions. Ces valeurs sont faibles comparées aux calculs thermodynamiques prévisionnels. On explique la faible efficacité de l'extraction par une extraction simultanée du thorium dans la nappe métallique liquide qui forme des composés intermétalliques à l'interface métal/sel et bloque le transfert interphasique. Des méthodes ont été développées pour atteindre des données fondamentales qui font défaut en milieu fluorures fondus, en particulier les propriétés de solvatation. La spéciation de plusieurs cations métalliques par les ions fluorures à haute température a notamment été étudiée et les constantes de complexation calculées par simulation des résultats expérimentaux. Réalisée pour deux lanthanides, le néodyme et le lanthane, deux actinides, le thorium et l'uranium et également pour un métal de transition, le nickel, cette étude permet d'atteindre les coefficients d'activité de ces éléments dans tous les sels fluorures fondus. En particulier, l'étude de la spéciation du thorium a été une étape importante dans la connaissance de la chimie du sel combustible LiF-ThF₄ puisque nous avons pu en déduire le coefficient d'activité de l'ion fluorure dans ce milieu à 650°C.Enfin, l'ensemble de ce travail a conduit à donner une première estimation de la réactivité de chaque élément de la classification périodique (présent dans le réacteur nucléaire après opération) à chaque étape du traitement du sel combustible usé

O início do resto de uma vida. O relato dos primeiros passos no mundo da docência

Este relatório de estágio surge no âmbito da unidade curricular Estágio Profissional integrada no segundo ano do Mestrado em Ensino de Educação Física nos Ensinos Básico e Secundário da Faculdade de Desporto da Universidade do Porto (FADEUP). O manuscrito trata a minha primeira experiência como professor, que teve como palco uma escola básica, na cidade de braga de onde sou natural. Através de uma perspetiva reflexiva é relatada a minha viagem ao longo do ano letivo 2022/2023. No que concerne à organização do mesmo, está divido em sete capítulos: introdução, enquadramento pessoal, enquadramento profissional, organização e gestão do ensino e da aprendizagem, participação na escola e relação com a comunidade, desenvolvimento profissional e, por fim, conclusões.This internship report is part of the Professional Internship course integrated into the second year of the Master's Degree in Physical Education Teaching in Elementary and Secondary Education at the Faculty of Sports of the University of Porto (FADEUP). The manuscript documents my first experience as a teacher, which took place in one basic school in the city of Braga, where I am originally from. Through a reflective perspective, I narrate my journey throughout the 2022/2023 academic year. In terms of its organization, the report is divided into seven chapters: introduction, personal background, professional context, organization and management of teaching and learning, school involvement and community relations, professional development, and, finally, conclusions

Preliminary studies on the lipidic compounds in the gonads of Catostylus tagi

2nd International Congress of CiiEM: “Translational Research and Innovation in Human in health Sciences”. Egas Moniz, Caparica, 11-13 June 2017The objective of this study was to initiate the characterization of the lipidic compounds present in the gonads of both sexes of the scyphozoan Catostylus tagi, native of the Tagus and Sado estuaries.Egas Moniz - Cooperativa de Ensino Superior CRL - EM-ZM 03: Preliminary studies on the capture and preservation conditions of a Portuguese medusa; EM-ZM-04: Studies on the utilization of Catostylus tagi in health sciences.N/

Quantum Machine Learning for bb-jet charge identification

Machine Learning algorithms have played an important role in hadronic jet classification problems. The large variety of models applied to Large Hadron Collider data has demonstrated that there is still room for improvement. In this context Quantum Machine Learning is a new and almost unexplored methodology, where the intrinsic properties of quantum computation could be used to exploit particles correlations for improving the jet classification performance. In this paper, we present a brand new approach to identify if a jet contains a hadron formed by a $b$ or $\bar{b}$ quark at the moment of production, based on a Variational Quantum Classifier applied to simulated data of the LHCb experiment. Quantum models are trained and evaluated using LHCb simulation. The jet identification performance is compared with a Deep Neural Network model to assess which method gives the better performance

MINHO@home

This paper briefly describes the development of a mobile robot to participate on RoboCup@Home. The focus of this project is to integrate robotic knowledge into home applications and human interaction. The robot has the ability to move in all directions due to its omnidirectional system with 3 Swedish wheels at 120º angle and can handle objects using an articulated arm with six degrees of freedom. It incorporates several vision systems allowing the robot to recognize faces and objects and to move autonomously on a domestic environment. Voice recognition and speech capabilities are also present

O mais importante registo histórico da vitivinicultura em Portugal

Relatório de estágio, na área de especialização em Gestão e Programação do Património Cultural, apresentado ao Departamento de História, Estudos Europeus, Arqueologia e Artes da Faculdade de Letras da Universidade de CoimbraO Museu do Vinho de Alcobaça representa o mais importante e completo testemunho da actividade vitivinícola nacional, ao longo de vários séculos, sobressaindo como um enorme património cultural tangível, móvel e imóvel, constituído pelos edifícios e respectivo conteúdo, e valorizando-se como um importante legado, de uma cultura que nos acompanha, com uma grande expressão, até à actualidade. O presente trabalho propõe-se ao conhecimento da história da vitivinicultura em Alcobaça, enquanto contexto de origem do Museu. Neste espaço, encontramos uma importante mostra desta zona vitivinícola e, apesar do seu enfoque ser nacional, este Museu possui uma forte inserção no território traduzida num contexto local muito identificado com a história do edifício que alberga o museu, assim como do diverso e vasto património preservado. Esta dissertação revela, ainda, uma análise comparativa com outros espaços museológicos e apresenta, por fim, uma proposta de gestão e programação para este espaço.The Wine Museum of Alcobaça shows us one of the most important and full testimonies of our national wine production, throughout centuries. It is a vast cultural patrimony, established by its constructions and its interior; a significant legacy of a culture that remained present until today, maintaining great vivacity in its practice. Thus, this study aims towards the knowledge of the history about viticulture in Alcobaça, home city of the Museum. At the Museum, it is possible to find a significant demonstration of Alcobaça’s wine production territory, showing that despite the National focus given to the Museum, there is a strong patent influence of the territory embodied in it as well – due to the connection with the past of its house, as well as to the diverse and vast local heritage. This dissertation also includes a comparative analysis of Alcobaça’s Wine Museum, to other Museums. In conclusion, we are shown a management and programing proposal with possible solutions for the Museum’s development

Keystrokes and clicks : measuring stress on e-learning students

In traditional learning, teachers can easily get an insight into how their students work and learn and how they interact in the classroom. However, in online learning, it is more difficult for teachers to see how individual students behave. With the enormous growing of e-learning platforms, as complementary or even primary tool to support learning in organizations, monitoring students’ success factors becomes a crucial issue. In this paper we focus on the importance of stress in the learning process. Stress detection in an E-learning environment is an important and crucial factor to success. Estimating, in a non-invasive way, the students’ levels of stress, and taking measures to deal with it, is then the goal of this paper. Moodle, by being one of the most used e-learning platforms is used to test the log tool referred in this work.(undefined

A Tool to Explore the Population of a CIDOC-CRM Ontology

This paper presents a visualising tool to explore the population of an Ontology, obtained through the processes of automatic migration and text information extraction. It was developed in the context of EPISA project, a R&D project that aims to represent the Portuguese National Archives records information in CIDOC-CRM, an ontology developed for museums. The tool allows the migration process developers to visualise the instances and their properties, and to debug the migration process and the migration representation model, or to explore the Archives by final users. It uses modeling and reasoners OWL-API with SPARQL-DL queries to obtain the exploration results