On the r−r-stability of spacelike hypersurfaces

In this paper we study the strong stability of spacelike hypersurfaces with constant $r$-th mean curvature in Generalized Robertson-Walker spacetimes of constant sectional curvature. In particular, we treat the case in which the ambient spacetime is the de Sitter space

Experimental analysis of lateral impact on planar brittle material: spatial properties of the cracks

The breakup of glass and alumina plates due to planar impacts on one of their lateral sides is studied. Particular attention is given to investigating the spatial location of the cracks within the plates. Analysis based on a phenomenological model suggests that bifurcations along the cracks' paths are more likely to take place closer to the impact region than far away from it, i. e., the bifurcation probability seems to lower as the perpendicular distance from the impacted lateral in- creases. It is also found that many observables are not sensitive to the plate material used in this work, as long as the fragment multiplicities corresponding to the fragmentation of the plates are similar. This gives support to the universal properties of the fragmentation process reported in for- mer experiments. However, even under the just mentioned circumstances, some spatial observables are capable of distinguishing the material of which the plates are made and, therefore, it suggests that this universality should be carefully investigated

Viscous Cosmology

We discuss the possibility to implement a viscous cosmological model, attributing to the dark matter component a behaviour described by bulk viscosity. Since bulk viscosity implies negative pressure, this rises the possibility to unify the dark sector. At the same time, the presence of dissipative effects may alleviate the so called small scale problems in the $\Lambda$CDM model. While the unified viscous description for the dark sector does not lead to consistent results, the non-linear behaviour indeed improves the situation with respect to the standard cosmological model.Comment: Latex file, 7 pages, 6 figures. To appear in the proceedings of the XIIth International Conference on Gravitation, Astrophysics and Cosmology, June 28-July 5, 2015, PFUR, Moscow, Russi

Deficiências minerais em pastagens do Estado do Rio de Janeiro.

bitstream/item/65349/1/CTAA-DOCUMENTOS-8-DEFICIENCIAS-MINERAIS-EM-PASTAGENS-DO-ESTADO-DO-RIO-DE-JANEIRO-FL-02171.pd

A framework for certification of large-scale component-based parallel computing systems in a cloud computing platform for HPC services

This paper addresses the verification of software components in the context of their orchestration to build cloud-based scientific applications with high performance computing requirements. In such a scenario, components are often supplied by different sources and their cooperation rely on assumptions of conformity with their published behavioral interfaces. Therefore, a faulty or ill-designed component, failing to obey to the envisaged behavioral requirements, may have dramatic consequences in practice. Certifier components, introduced in this paper, implement a verification as a service framework and are able to access the implementation of other components and verify their consistency with respect to a number of functional, safety and liveness requirements relevant to a specific application or a class of them. It is shown how certifier components can be smoothly integrated in HPC Shelf, a cloud-based platform for high performance computing in which different sorts of users can design, deploy and execute scientific applications.SmartEGOV: Harnessing EGOV for Smart Governance (Foundations, methods, Tools) / NORTE-01-0145-FEDER000037, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (EFD

Experimental analysis of lateral impact on planar brittle material

The fragmentation of alumina and glass plates due to lateral impact is studied. A few hundred plates have been fragmented at different impact velocities and the produced fragments are analyzed. The method employed in this work allows one to investigate some geometrical properties of the fragments, besides the traditional size distribution usually studied in former experiments. We found that, although both materials exhibit qualitative similar fragment size distribution function, their geometrical properties appear to be quite different. A schematic model for two-dimensional fragmentation is also presented and its predictions are compared to our experimental results. The comparison suggests that the analysis of the fragments' geometrical properties constitutes a more stringent test of the theoretical models' assumptions than the size distribution