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Institution

Instituto Superior Técnico

Education
About: Instituto Superior Técnico is a based out in . It is known for research contribution in the topics: Catalysis & Finite element method. The organization has 10085 authors who have published 30226 publications receiving 667524 citations. The organization is also known as: IST & Instituto Superior Tecnico.


Papers
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Book ChapterDOI
01 Jan 2003
TL;DR: In this work continuous force and unilateral contact models are presented and the equivalence between the different contact models is discussed, taking into account the use of the different representations of the system flexibility.
Abstract: The use of multibody tools in a virtual environment, aiming to real-time, leads to models where a compromise between accuracy and computational efficiency has to be reached. Complex multibody models that undergo complex interactions often experience some level of deformations while contact between the system components or with external surfaces occurs. Depending on the objectives of the virtual environment different modeling assumptions, leading to various types of models, can be used. In this work several representations of the system flexibility able to represent the deformation of the components are presented. The plastic hinge and the finite segment approaches provide computationally efficient forms of representing large and small deformations but they lack the ability of describing the stresses and strains on the deformed components. The finite element approaches can describe with high level of accuracy the system deformation, including the stress and strain fields, but they have higher computational costs. In systems that experience contact or impact situations it is necessary to include proper contact models. In this work continuous force and unilateral contact models are presented. The choice between these contact models is discussed here taking into account the use of the different representations of the system flexibility. In the process, the equivalence between the different contact models is discussed. Applications to railway, automobile and biomechanical contact are used to demonstrate the use of the formulations proposed.

148 citations

Journal ArticleDOI
TL;DR: In this article, a detailed analysis of perturbed Kerr-AdS black holes in four-and five-dimensional spacetimes is presented, including the computation of its quasinormal modes, hydrodynamic modes and superradiantly unstable modes.
Abstract: Black holes in anti-de Sitter (AdS) backgrounds play a pivotal role in the gauge/gravity duality where they determine, among other things, the approach to equilibrium of the dual field theory. We undertake a detailed analysis of perturbed Kerr-AdS black holes in four- and five-dimensional spacetimes, including the computation of its quasinormal modes, hydrodynamic modes and superradiantly unstable modes. Our results shed light on the possibility of new black hole phases with a single Killing field, possible new holographic phenomena and phases in the presence of a rotating chemical potential, and close a crucial gap in our understanding of linearized perturbations of black holes in anti-de Sitter scenarios.

148 citations

Journal ArticleDOI
TL;DR: In this article, a comparison of the life cycle of concrete with coarse natural and recycled concrete aggregates is presented, showing that the use of coarse aggregates recycled from concrete can significantly reduce the Environmental Impacts and costs.

148 citations

Journal ArticleDOI
TL;DR: In this paper, a partial mixed layerwise finite element model for adaptive plate structures is presented by considering a Reissner mixed variational principle, and the mixed functional is formulated using transverse stresses, displacement components and electric and magnetic potentials as primary variables.

148 citations

Journal ArticleDOI
TL;DR: In this paper, the authors presented black hole type solutions in the scalar-tensor theory with non-minimal derivative coupling to the Einstein tensor for the particular coupling constant tuned to the inverse of the cosmological constant, and for the other coupling constant, more general solutions can be obtained, while the thermodynamic properties of a black hole are very similar to those of the Schwarzschild-AdS black hole in the Einstein gravity.
Abstract: We present black hole type solutions in the scalar-tensor theory with nonminimal derivative coupling to the Einstein tensor. The effects of the nonminimal derivative coupling appear in the large scales, while the solutions approach those in the Einstein gravity in the small scales. For the particular coupling constant tuned to the inverse of the cosmological constant, the scalar field becomes trivial and the solutions in the Einstein gravity are recovered. For the other coupling constant, more general solutions can be obtained. If the two-dimensional maximally symmetric space is a two-sphere, the spacetime structure approaches anti--de Sitter (AdS) spacetime in the large scales. On the other hand, if the two-dimensional space is a two-hyperboloid, the spacetime approaches de Sitter spacetime. If it is a flat space, the cosmological constant affects only the amplitude of the scalar field. The extension to the higher-dimensional case is also straightforward. For a certain range of the negative cosmological constant, thermodynamic properties of a black hole are very similar to those of the Schwarzschild-AdS black hole in the Einstein gravity.

148 citations


Authors

Showing all 10288 results

NameH-indexPapersCitations
Joao Seixas1531538115070
A. Gomes1501862113951
Amartya Sen149689141907
António Amorim136147796519
Joao Varela133141192438
Pietro Faccioli132137889795
João Carvalho126127877017
Pedro Jorge12477668658
Pedro Silva12496174015
A. De Angelis11853454469
Hermine Katharina Wöhri11662955540
Helena Santos114105854286
P. Conde Muiño10955856133
Joao Saraiva10751953340
J. N. Reddy10692666940
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202341
2022354
20212,263
20202,433
20192,327
20182,190