Failure regime in (1+1) dimensions in fibrous materials

In this paper, we introduce a model for fracture in fibrous materials that takes into account the rupture height of the fibers, in contrast with previous models. Thus, we obtain the profile of the fracture and calculate its roughness, defined as the variance around the mean height. We investigate the relationship between the fracture roughness and the fracture toughness.Comment: 4 pages, 4 figures.eps, Revte

Criação de componente de fôrma industrializada de pilar através de uma plataforma BIM

In the Brazilian industry, few construction companies have very detailed and accurate formwork projects, resulting in waste, lack of planning, and delays. Thereupon, the objective of this paper was to incorporate the precepts of Building Information Modeling (BIM) in the industrialized column formwork product, that, because of its complexity, the graphic representation in 2D CAD lacks information and requires a lot of time in its development. It can be said that the most immediate benefits of BIM are the greater efficiency and productivity in the project documentation, which through the parameters, project information is generated automatically and more accurately. The modeling process prioritized the component's performance over its appearance, regarding some national and international manuals and standards. Before the actual modeling, family planning was carried out, then a parametric program was used, so that the nested families, parameters, rules, and links could be inserted into the family editor. The BIM project proved to be effective in terms of its automation and generation of quantitative in the project, however, as it is still a new product in the Brazilian industry, lacking in the attribution of information for 4D planning, maintenance, and logistics.No mercado brasileiro, são poucas as construtoras que possuem um projeto bem detalhado e preciso de fôrmas, resultando em desperdícios, falta de planejamento e atrasos. Desta forma, o objetivo deste trabalho foi incorporar os preceitos da Modelagem da Informação da Construção (BIM) no produto fôrma industrializada de pilar, que devido a sua complexidade, a sua representação gráfica no CAD 2D é carente de informações e requer muito tempo no seu desenvolvimento. Pode-se dizer que os benefícios mais imediatos do BIM é a maior eficiência e produtividade na documentação do projeto, que através dos parâmetros, informações do projeto são geradas de forma automática e mais precisa. O processo de modelagem priorizou o desempenho do componente em vez da sua aparência, tendo como referência alguns manuais e normas nacionais e internacionais. Antes da modelagem propriamente dita, foi realizado um planejamento da família, em seguida, utilizou-se um programa paramétrico, para que se pudesse inserir as famílias aninhadas, parâmetros, regras e vínculos no editor de famílias. O projeto em BIM se mostrou eficaz quanto a sua automatização e geração de quantitativos no projeto, porém, por ser ainda um produto novo no mercado brasileiro, carente quanto a atribuição de informações para planejamento 4D, para manutenção e para logística

Hubble expansion and structure formation in the "running FLRW model" of the cosmic evolution

A new class of FLRW cosmological models with time-evolving fundamental parameters should emerge naturally from a description of the expansion of the universe based on the first principles of quantum field theory and string theory. Within this general paradigm, one expects that both the gravitational Newton's coupling, G, and the cosmological term, Lambda, should not be strictly constant but appear rather as smooth functions of the Hubble rate. This scenario ("running FLRW model") predicts, in a natural way, the existence of dynamical dark energy without invoking the participation of extraneous scalar fields. In this paper, we perform a detailed study of these models in the light of the latest cosmological data, which serves to illustrate the phenomenological viability of the new dark energy paradigm as a serious alternative to the traditional scalar field approaches. By performing a joint likelihood analysis of the recent SNIa data, the CMB shift parameter, and the BAOs traced by the Sloan Digital Sky Survey, we put tight constraints on the main cosmological parameters. Furthermore, we derive the theoretically predicted dark-matter halo mass function and the corresponding redshift distribution of cluster-size halos for the "running" models studied. Despite the fact that these models closely reproduce the standard LCDM Hubble expansion, their normalization of the perturbation's power-spectrum varies, imposing, in many cases, a significantly different cluster-size halo redshift distribution. This fact indicates that it should be relatively easy to distinguish between the "running" models and the LCDM cosmology using realistic future X-ray and Sunyaev-Zeldovich cluster surveys.Comment: Version published in JCAP 08 (2011) 007: 1+41 pages, 6 Figures, 1 Table. Typos corrected. Extended discussion on the computation of the linearly extrapolated density threshold above which structures collapse in time-varying vacuum models. One appendix, a few references and one figure adde

First-order formalism for dark energy and dust

This work deals with first-order formalism for dark energy and dust in standard cosmology, for models described by real scalar field in the presence of dust in spatially flat space. The field dynamics may be standard or tachyonic, and we show how the equations of motion can be solved by first-order differential equations. We investigate a model to illustrate how the dustlike matter may affect the cosmic evolution using this framework.Comment: 5 pages, 1 figure; title changed, new author included, discussions extended, references added, version to appear in EPJ