RepositóriUM Collection:http://hdl.handle.net/1822/122422019-11-21T20:23:32Z2019-11-21T20:23:32ZOn the determination coefficient and global adjustment test of goodness of fitAzevedo, CecíliaSilva, Rita Catarina Assunção RibeiroHorta, Ana Maria Lacerda Morgado Fernandes Carvalho AboimCorreia-Neves, Mhttp://hdl.handle.net/1822/497012018-01-25T13:35:12Z2018-01-25T13:35:12Z<b>Title</b>: On the determination coefficient and global adjustment test of goodness of fit
<b>Author(s)</b>: Azevedo, Cecília; Silva, Rita Catarina Assunção Ribeiro; Horta, Ana Maria Lacerda Morgado Fernandes Carvalho Aboim; Correia-Neves, M
<b>Type</b>: oralPresentation2018-01-25T13:35:12ZThe role of execution errors in populations of ultimatum bargaining agentsSantos, Fernando P.Pacheco, Jorge Manuel SantosPaiva, AnaSantos, Francisco C.http://hdl.handle.net/1822/478952018-04-04T16:48:22Z<b>Title</b>: The role of execution errors in populations of ultimatum bargaining agents
<b>Author(s)</b>: Santos, Fernando P.; Pacheco, Jorge Manuel Santos; Paiva, Ana; Santos, Francisco C.
<b>Abstract(s)</b>: The design of artificial intelligent agents is frequently accomplished by equipping individuals with mechanisms to choose actions that maximise a subjective utility function. This way, the implementation of behavioural errors, that systematically prevent agents from using optimal strategies, often seems baseless. In this paper, we employ an analytical framework to study a population of Proposers and Responders, with conflicting interests, that co-evolve by playing the prototypical Ultimatum Game. This framework allows to consider an arbitrary discretisation of the strategy space, and allows us to describe the dynamical impact of individual mistakes by Responders, on the collective success of this population. Conveniently, this method can be used to analyse other continuous strategy interactions. In the case of Ultimatum Game, we show analytically how seemingly disadvantageous errors empower Responders and become the source of individual and collective long-term success, leading to a fairer distribution of gains. This conclusion remains valid for a wide range of selection pressures, population sizes and mutation rates.
<b>Type</b>: conferencePaperRelativistic Elasticity: recent developments.Ramos, M. P. Machadohttp://hdl.handle.net/1822/457972018-02-02T16:14:32Z2017-06-01T09:06:52Z<b>Title</b>: Relativistic Elasticity: recent developments.
<b>Author(s)</b>: Ramos, M. P. Machado
<b>Abstract(s)</b>: The theory of elasticity in the context of general relativity was developed in the mid twentieth century. The need for such a theory came in the late 1950s with Weber´s bar antenna for gravitational waves in order to explain how these waves interact with elastic solids. In 1973, a fully developed nonlinear theory of elasticity adapted to general relativity was given in a paper by Carter and Quintana, which, to a certain extent, remains as the standard reference of this theory. In this paper the concept of elasticity is formulated within the framework of general relativity. In this talk, the theory of elastic matter within the context of general relativity is presented, following the formulation of Carter and Quintana. The latest developments within this theory will be discussed; in particular, recent work on conformally flat spacetimes associated to an elastic stress energy tensor will be analysed.
<b>Type</b>: conferenceAbstract2017-06-01T09:06:52ZNumerical simulation of electrical problems in a vacuum disjuntorClain, StéphaneRodrigues, José Albertohttp://hdl.handle.net/1822/370552018-07-05T16:55:20Z2015-09-10T15:33:28Z<b>Title</b>: Numerical simulation of electrical problems in a vacuum disjuntor
<b>Author(s)</b>: Clain, Stéphane; Rodrigues, José Alberto
<b>Abstract(s)</b>: A vacuum circuit breaker is a device that allows the cutting of electrical
power. This device consists essentially of two electrodes, one of them being mobile and is
subject to a mechanical force produced by a spring, giving rise to the contact between the
two electrodes. The current passing between two electrodes is determined by the extension
of the contact zone. Moreover, the passage of current generated Laplace forces in areas
bordering the contact, but not yet in contact. Due to the curved geometry of the electrodes,
these Laplace forces are opposite and therefore cause the repulsion of the electrodes. This
means that for a given power we have to evaluate the electric potential, the magnetic field
corresponding to the contact zone.
<b>Type</b>: conferencePaper2015-09-10T15:33:28ZKilling vector analysis in GHP formalism of conformally flat pure radiation metrics with negative cosmological constantBradley, MichaelRamos, M. P. Machadohttp://hdl.handle.net/1822/370322018-06-28T11:22:28Z2015-09-10T14:04:11Z<b>Title</b>: Killing vector analysis in GHP formalism of conformally flat pure radiation metrics with negative cosmological constant
<b>Author(s)</b>: Bradley, Michael; Ramos, M. P. Machado
<b>Abstract(s)</b>: In a paper by Edgar and Ludwig it was shown how the symmetry analysis of a spacetime may be considerably simpli ed when using intrinsic GHP tetrads. A generalised Lie derivative operator, that reduces to the usual Lie derivative when acting on zero-weighted quantities, was introduced. The Killing equations are then obtained by acting with the commutators of this derivative and the GHP operators on zero-weighted scalars (the intrinsic coordinates). In this work we extend the method to a class of
spacetimes with null rotation isotropy, where an intrinsic GHP tetrad cannot be completly found. The Killing vectors of the conformally at pure radiation metrics with negative cosmological constant arethen determined and the result is compared with other methods.
<b>Description</b>: Poster apresentado na conferência 20th International Conference on General Relativity and Gravitation
<b>Type</b>: conferenceAbstract2015-09-10T14:04:11Z