Roberto da Silva

Bio: Roberto da Silva is an academic researcher from Universidade Federal do Rio Grande do Sul. The author has contributed to research in topics: Critical exponent & Monte Carlo method. The author has an hindex of 17, co-authored 100 publications receiving 921 citations. Previous affiliations of Roberto da Silva include University of São Paulo.

An agent-based simulation of pedestrian dynamics: from lane formation to auditorium evacuation

Abstract: In this paper we present an agent-based simulation of pedestrian dynamics based on cellular automata models. Differently from the cellular automata, our model represents different pedestrian characteristics: gender, speed, room geometry knowledge, and herding and obstacle avoidance behavior. We study how different room geometries, different pedestrian groups sizes and characteristics influence the pedestrian dynamics and the macroscopic behavior of the system. With this agent-based approach we expect to obtain more realistic results than the cases where the pedestrians are uniformly modeled. Our analysis indicates that pedestrian groups with different features contribute in different ways to the macroscopic behavior.

Modelling of Statistical Low-Frequency Noise of Deep-Submicron MOSFETs

Abstract: The low-frequency noise (LF-noise) of deep submicron MOSFETs is experimentally studied with special emphasis on yield relevant parameter scattering. A novel modeling approach is developed which includes detailed consideration of statistical effects. The model is based on device physics-based parameters which cause statistical fluctuations in LF-noise behavior of individual devices. It can easily be implemented in a compact model for use in circuit simulation tools.

Exame Nacional do Ensino Médio (ENEM): Uma análise crítica

Abstract: Ao enfrentar o desafio da criacao de poĺiticas de acesso ao ensino superior as nacoes se deparam com uma questao mais fundamental: como proceder a selecao daqueles que farao parte da sua elite intelectual? Entretanto este tema nao e novo. A China foi a primeira nacao a buscar uma solucao estruturada para ele. Em 605 d.C., durante a Dinastia Sui, foi criado o Exame Imperial que selecionava servidores publicos [1] para compor a elite intelectual do governo chines. Reconhecendo que a escolha de servidores publicos de alta patente deveria priorizar a excelencia, Thomas Taylor Meadows, que era consul de Guangzhou no sul da China, inspirando-se no modelo chines sugeriu a adocao de exames de selecao para o Imperio Britânico. Em 1806 iniciou o processo de selecao mediado por exames publicos para servidores de sua Majestade. No seculo XIX o sistema de educacao superior passou a enfrentar a questao da selecao. Napoleao buscando qualificar a formacao tecnica adotou o baccalaureat ou, como e hoje conhecido, o le bac, cuja aprovacao se tornou requisito para o ingresso nas grandes escolas francesas. No Reino Unido surgiu o General Certificate of Secondary Education (GCSE). Na China em 1952 foi criado o National Higher Education Entrance Examination, tendo 9,5 milhoes de candidatos em 2006. Nos Estados Unidos, entre os diversos instrumentos usados para selecionar estudantes, dois deles sao muito aceitos: o Scholastic Aptitude Test (SAT) e o American College Testing (ACT) criados respectivamente em 1926 e em 1959. O primeiro e mais voltado para habilidades cŕiticas e o segundo para deducao. O que difere, no entanto, o sistema americano daqueles usados no restante dos paises esta em que ingresso de um estudante se da em um processo multidimensional dependente de diversos fatores (media das notas no Ensino Medio, participacao em atividades sociais, desportivas, cientificas e culturais e cartas de recomendacao de professores) alem da nota em uma prova especifica. O peso de cada um destes itens e determinado pela universidade, propiciando uma diversidade entre os estudantes que ingressam no ensino superior nos Estados Unidos. A diversidade tem se mostrado um fator importante para o sucesso de sistemas educacionais e economicos. Ela rege o processo de selecao das grandes universidades americanas que primam por ter entre seus estudantes pessoas com perfis de formacao diversificados. A diversidade torna o sistema educacional daquele pais um sucesso, atestado nao somente pelo grande numero de ganhadores de premio Nobel, como tambem na gestao de empresas. Reconhecendo o poder da diversidade, grandes empresas hoje procuram atingi-la na sua producao comercial bem como no seu corpo tecnico e administrativo.

Maximum Entropy Principle and the Higgs boson mass

Abstract: A successful connection between Higgs boson decays and the Maximum Entropy Principle is presented. Based on the information theory inference approach we determine the Higgs boson mass as MH=125.04±0.25GeV, a value fully compatible to the LHC measurement. This is straightforwardly obtained by taking the Higgs boson branching ratios as the target probability distributions of the inference, without any extra assumptions beyond the Standard Model. Yet, the principle can be a powerful tool in the construction of any model affecting the Higgs sector. We give, as an example, the case where the Higgs boson has an extra invisible decay channel within a Higgs portal model.

Evolution and the Theory of Games

Abstract: In the Hamadryas baboon, males are substantially larger than females. A troop of baboons is subdivided into a number of ‘one-male groups’, consisting of one adult male and one or more females with their young. The male prevents any of ‘his’ females from moving too far from him. Kummer (1971) performed the following experiment. Two males, A and B, previously unknown to each other, were placed in a large enclosure. Male A was free to move about the enclosure, but male B was shut in a small cage, from which he could observe A but not interfere. A female, unknown to both males, was then placed in the enclosure. Within 20 minutes male A had persuaded the female to accept his ownership. Male B was then released into the open enclosure. Instead of challenging male A , B avoided any contact, accepting A’s ownership.

Universality classes in nonequilibrium lattice systems

Abstract: This article reviews our present knowledge of universality classes in nonequilibrium systems defined on regular lattices. The first section presents the most important critical exponents and relations, as well as the field-theoretical formalism used in the text. The second section briefly addresses the question of scaling behavior at first-order phase transitions. In Sec. III the author looks at dynamical extensions of basic static classes, showing the effects of mixing dynamics and of percolation. The main body of the review begins in Sec. IV, where genuine, dynamical universality classes specific to nonequilibrium systems are introduced. Section V considers such nonequilibrium classes in coupled, multicomponent systems. Most of the known nonequilibrium transition classes are explored in low dimensions between active and absorbing states of reaction-diffusion-type systems. However, by mapping they can be related to the universal behavior of interface growth models, which are treated in Sec. VI. The review ends with a summary of the classes of absorbing-state and mean-field systems and discusses some possible directions for future research.