Diffusion regimes in Levy flights with trapping

The diffusion of a walk in the presence of traps is investigated. Different diffusion regimes are obtained considering the magnitude of the fluctuations in waiting times and jump distances. A constant velocity during the jump motion is assumed to avoid the divergence of the mean squared displacement. Using the limit theorems of the theory of Levy stable distributions we have provided a characterization of the different diffusion regimes.Comment: 1 figure, submitted to Physica

Optimisation Globale d'une Cellule de Commutation SiC : Dimensionnement CEM et Thermique

National audienceDans le domaine de l'aéronautique, la masse des équipements est un critère de sélection très important. Il est donc devenu essentiel de pouvoir modéliser ces dispositifs à des fins d'optimisation. Cet article présente une méthode de pré-dimensionnement par optimisation d'un hacheur série sur un modèle multi-physiques analytique. Le compromis pertes/CEM est alors étudié

Abundances on the Main Sequence of Omega Centauri

Abundance ratios of carbon, nitrogen and strontium relative to iron, calculated using spectrum synthesis techniques, are given for a sample of main sequence and turnoff stars that belong to the globular cluster omega Centauri. The variations of carbon, nitrogen and/or strontium show several different abundance patterns as a function of [Fe/H]. The source of the enhancements/depletions in carbon, nitrogen and/or strontium may be enrichment from asymptotic giant branch stars of low (1--3 solar masses) and intermediate (3--8 solar masses) mass. Massive rotating stars which produce excess nitrogen without carbon and oxygen overabundances may also play a role. These abundances enable different contributors to be considered and incorporated into the evolutionary picture of omega Cen.Comment: 43 Pages, 13 Figures. Accepted for publication in Ap

Charged vacancy in graphene: interplay between Landau levels and atomic collapse resonances

The interplay between a magnetic field and the Coulomb potential from a charged vacancy on the electron states in graphene is investigated within the tight-binding model. The Coulomb potential removes locally Landau level degeneracy, while the vacancy introduces a satellite level next to the normal Landau level. These satellite levels are found throughout the positive energy region, but in the negative energy region they turn into atomic collapse resonances. Crossings between Landau levels with different angular quantum number $m$ are found. Unlike the point impurity system in which an anticrossing occurs between Landau levels of the same $m$, in this work anticrossing is found between the normal Landau level and the vacancy induced level. The atomic collapse resonance hybridize with the Landau levels. The charge at which the lowest Landau level $m = -1, N = 1$ crosses increases $E = 0$ with enhancing magnetic field. Landau level scaling anomaly occurs when the charge is larger than the critical charge $\beta\approx0.6$ and this critical charge is independent of the magnetic field

Mathematics as a discipline and as a school course: a systemic comparative study conducted in Brazil and Greece about the in-service school principals’ constructions

Em todos os sistemas educacionais hierárquicos são importantes os pontos de vista dos diretores de escola, pois eles afetam crucialmente as práticas de sala de aula e as relações entre todos os protagonistas da unidade escolar. Neste trabalho, adotamos aspectos da abordagem para a teoria dos sistemas, com o objetivo de investigar os pontos de vista dos diretores em serviço sobre a matemática, tanto como uma disciplina curricular como as práticas gerenciais do sistema de ensino, buscando entender as interações entre seus pontos de vista em relação à matemática e à organização dessa disciplina no sistema. A matemática no contexto escolar foi investigada considerando três focos: as representações simbólicas/ regulamentares, as representações pragmáticas e as intencionalidades das ações adotadas. Um estudo comparativo qualitativo foi realizado em pequena escala (N = 59), incluindo diretores de escolas públicas em serviço em uma região de São Paulo, no Brasil (NB = 29) e diretores de escolas da Grécia (NG = 30). Os resultados das comparações intraculturais e interculturais sugerem convergências e divergências noemáticas entre os pontos de vista epistemológicos adotados sobre a matemática pelos diretores gregos e pelos seus colegas brasileiros, também evidenciam pontos de vista sobre a matemática como um curso no ano letivo, revelando então interações intra e intersistêmicas

Mathematics as a discipline and as a school course: a systemic comparative study conducted in Brazil and Greece about the in-service school principals’ constructions

Em todos os sistemas educacionais hierárquicos são importantes os pontos de vista dos diretores de escola, pois eles afetam crucialmente as práticas de sala de aula e as relações entre todos os protagonistas da unidade escolar. Neste trabalho, adotamos aspectos da abordagem para a teoria dos sistemas, com o objetivo de investigar os pontos de vista dos diretores em serviço sobre a matemática, tanto como uma disciplina curricular como as práticas gerenciais do sistema de ensino, buscando entender as interações entre seus pontos de vista em relação à matemática e à organização dessa disciplina no sistema. A matemática no contexto escolar foi investigada considerando três focos: as representações simbólicas/ regulamentares, as representações pragmáticas e as intencionalidades das ações adotadas. Um estudo comparativo qualitativo foi realizado em pequena escala (N = 59), incluindo diretores de escolas públicas em serviço em uma região de São Paulo, no Brasil (NB = 29) e diretores de escolas da Grécia (NG = 30). Os resultados das comparações intraculturais e interculturais sugerem convergências e divergências noemáticas entre os pontos de vista epistemológicos adotados sobre a matemática pelos diretores gregos e pelos seus colegas brasileiros, também evidenciam pontos de vista sobre a matemática como um curso no ano letivo, revelando então interações intra e intersistêmicas

Lean Construction: IGLC research evolution and agenda for the future

The way Lean Construction has evolved within the construction industry is still not entirely clear. Inspired by lean manufacturing, there are differences in the output of the construction industry, thus resulting in differences between both types of sectors. In 2012, Jacobs, Folkestad, Glick have conducted a study analyzing the works published in the IGLC between 1996 and 2009. The authors have noticed a gap between Lean Construction and the Toyota Production System framework. In view of the high volume of publications between 2010 and 2016, as well as of the dynamics of the sector, this work proposed to reanalyze the 686 works published in this interval, and to verify whether there have been changes in the content of Lean Construction. It also proposes to map, within the proposed topics, the main topics studied each year through content analysis. Initially, the results obtained with the publication of 2012 have been compared, and it was possible to verify that certain topics remained, as was the case of work-on-process improvement. On the other hand, new topics have emerged and became frequent, such as the case of the Last Planner tool. Thereafter, a roadmap was drawn up by grouping the main topics covered each year by topic, allowing the understanding of the development of Lean Construction in the studied time interval

Sesame Project - Deliverable D08-02 - WP02 H/V technique : experimental conditions - Final report on Measurement Guidelines

In the following we report the final results for WP02-Measurement Guidelines. This work was conducted under the framework of the SESAME Project (Site Effects Assessment Using Ambient Excitations, EC-RGD, Project No. EVG1-CT-2000-00026 SESAME), Task A (H/V technique), Work Package 02 (WP02 – Measurement Guidelines).European Commission – Research General Directorate Project No. EVG1-CT-2000-00026 SESAMEPublished4.1. Metodologie sismologiche per l'ingegneria sismicaope