Seminários do CEAUL

Sala 6.2.50, FCUL, Lisboa

Extreme Value Laws and Point Processes of Rare Events for Chaotic Dynamical Systems

Ana Cristina Moreira Freitas
FEP and CMUP, Universidade do Porto

We consider discrete time dynamical systems and show the linking between Extreme Value Laws and Hitting Time Statistics. The stochastic processes arise from dynamical systems by evaluating an observable function (which achieves a global maximum at a single point of the phase space) along the orbits of the system. We exploit the connection between these two approaches both in the absence and presence of clustering. We associate the existence of an Extremal Index less than 1 to the occurrence of periodic phenomena. We show that, under certain conditions, in the absence of clustering, the point processes of exceedances converge to a standard Poisson process. In the presence of clustering, the point processes converge to a compound Poisson process, so instead of single exceedances, we have entire clusters of exceedances occurring at Poisson times with a geometric distribution ruling its multiplicity. We will also consider observables achieving a global maximum at multiple points which are correlated by belonging to the same orbit of a certain chosen point. We will see that this is a mechanism capable of creating clustering without an underlying periodic phenomenon and with different types of patterns.

Complete Convergence of Rare Events Point Processes and Records with Clustering

Jorge Milhazes de Freitas
FCUP and CMUP, Universidade do Porto

We consider time series corresponding to the evaluation of given potential along the orbits of systems with `nice' first return induced maps. Nice, here, means good memory loss properties. We are particularly interested in events corresponding to exceedances of high thresholds, i.e. instants at which the potential reaches abnormally high values, and, more specifically, when these exceedances have a tendency to appear in clusters. This clustering effect is known to be related to some form of underlying periodicity and we study its effects in the convergence of conveniently normalised point processes that count the number of exceedances in a certain time frame. We consider bidimensional point processes marking the exceedance instants in the x-axis and their severity in the y-axis. The convergence of these bidimensional processes is then used to obtain information about records.

14h00-16h30
CEAUL - Centro de Estatística e Aplicações da Universidade de Lisboa
Logótipo do Programa Portugal 2020

Apresentação de candidaturas a financiamento no âmbito do programa COMPETE 2020 direcionado a:

 

O CNADS - Conselho Nacional do Ambiente e Desenvolvimento Sustentável é presidido por Filipe Duarte Santos (FCUL / cE3c).

ScienceIN2Business - Call for Projects 2018

Call destinada a alunos e investigadores de Ciências que estejam envolvidos em projetos de base científica e/ou tecnológica com potencial de mercado.

Por Mario Alberto Salazar (Instituto Politécnico Nacional, México).

Astrobiologia, a origem e a procura de vida no sistema solar

Por Zita Martins (Instituto Superior Técnico da Universidade de Lisboa).

Curso reagendado para os dias 28 e 29 de abril de 2018, com vagas extra - inscrições até ao final do dia 21 de abril para ShortCourses1718@gmail.com.

Henrique Califórnia Mendes defende a dissertação "Security Auditing of a DLMS/COSEM Smart Grid Communication Protocol Implementation".

Por Vicente Muñoz Velázquez (Univ. Complutense, Madrid).

Quarries Alive 2018 International Conference

The conference aims to create a bridge between quarry restoration projects around the world.

Por Carlos Antunes (DEGGE/IDL - FCUL).

Por Luís Tiago Ferreira e Eduardo Francisco (EDP Distribuição - Direção de Tecnologia e Inovação, Eficiência Energética e Mobilidade Elétrica).

Percurso

Sessão de divulgação dos Mestrados disponíveis no ano letivo de 2018/2019, com os seguintes participantes:

The course will cover methods for fitting geostatistical and spatial point process models to data obtained from surveys on which the whole region or population of interest is observed, as well as surveys on which observations are available only in a spatial sample from the regi

Por Simão Palmeirim (CIEBA | FBAUL).

Ciência e Império

Este seminário destina-se à apresentação de trabalhos em curso sobre as inter-relações entre conhecimento científico, tecnologia e formações imperiais.

Logótipo do Dia Aberto em Ciências 2018

O Dia Aberto de Ciências realiza-se no dia 09 de maio de 2018.

Anny Caroline de Almeida Muniz defende a dissertação "Caracterização do perfil de iniciação do consumo tabágico dos alunos de 3.º ciclo dos agrupamentos de escolas adstritos ao ACES Arco Ribeirinho".

Cursos Avançados cE3c 2017/2018

Nature-based approach to Design solutions for a more resilient future aims to support societies address a variety of environmental, social and economic challenges in sustainable ways. This approach relies on actions that are inspired by, supported by or copied from Nature.

Por Augusto Gerolin (University of Jyväskylä, Finland).

Programa Almeida Garrett 2018/2019

Candidaturas até 18 de maio de 2018 (mobilidade no 1.º semestre) e até 19 de outubro de 2018 (mobilidade no 2.º semestre).

Logótipo do Programa MAR2020

Encontra aberto o período para a apresentação de candidaturas a financiamento no âmbito da Medida 3 da Prioridade 1 do Programa MAR2020:

A ferramenta do astrólogo: a figura celeste ou mapa astrológico

Este novo seminário, organizado pelo CIUHCT e pelo Departamento de História e Filosofia das Ciências (FCUL), é dedicado à história da astronomia antiga, estendendo o conceito aos aspetos históricos da disciplina, ou de outras que com ela se relacionaram, até ao século XIX.

Cursos Avançados cE3c 2017/2018

Currently, climate changes or alterations are known to be reflected on the stable isotope ratios of Hydrogen, Nitrogen, Carbon, Oxygen and Sulphur present in atmospheric gas forms, fresh or ocean water, as well as in plants and animals and organic matter in the soil.

Cursos Avançados cE3c 2017/2018

Phylogeography is one of the recent scientific areas emergent from the dissemination of highthrouput technologies of sequencing starting in the 90’s of the XXth century, with the consequent development of intra-specific genetic variance analysis and its geographic distribution.

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