Instituto Superior Técnico

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.

The Intermittent Bus Lane signals setting within an area

Abstract: Intermittent Bus Lane (IBL) used for bus priority is a lane in which the status of a given section changes according to the presence or not of a bus in its spatial domain: when a bus is approaching such a section, the status of that lane is changed to BUS lane, and after the bus moves out of the section, it becomes a normal lane again, open to general traffic. Therefore when bus services are not so frequent, general traffic will not suffer much, and bus priority can still be obtained. This measure can be operating at a single city block, but if all related control parameters along bus lines are considered together, more time gains can be obtained. In this paper, the basic structure and operation of IBL around a single intersection are briefly introduced, then the construction of an objective function and its relationships with the related priority control parameters along one bus line and their simplifications are described. Finally the calculations of the priority control parameters when there are several connected bus lines within an area and some simulation results are discussed.

Nonperturbative Ambiguities and the Reality of Resurgent Transseries

Abstract: In a wide range of quantum theoretical settings—from quantum mechanics to quantum field theory, from gauge theory to string theory—singularities in the complex Borel plane, usually associated to instantons or renormalons, render perturbation theory ill-defined as they give rise to nonperturbative ambiguities. These ambiguities are associated to choices of an integration contour in the resummation of perturbation theory, along (singular) Stokes directions in the complex Borel plane (rendering perturbative expansions non-Borel summable along any Stokes line). More recently, it has been shown that the proper framework to address these issues is that of resurgent analysis and transseries. In this context, the cancelation of all nonperturbative ambiguities is shown to be a consequence of choosing the transseries median resummation as the appropriate family of unambiguous real solutions along the coupling-constant real axis. While the median resummation is easily implemented for one-parameter transseries, once one considers more general multi-parameter transseries the procedure becomes highly dependent upon properly understanding Stokes transitions in the complex Borel plane. In particular, all Stokes coefficients must now be known in order to explicitly implement multi-parameter median resummations. In the cases where quantum-theoretical physical observables are described by resurgent functions and transseries, the methods described herein show how one may cancel nonperturbative ambiguities, and define these observables nonperturbatively starting out from perturbation theory. Along the way, structural results concerning resurgent transseries are also obtained.

Effects of mixing with quark singlets

Abstract: The mixing of the known quarks with new heavy singlets can modify significantly some observables with respect to the standard model predictions. We analyze the range of deviations permitted by the constraints from precision electroweak data and flavor-changing neutral processes at low energies. We study top charged current and neutral current couplings, which will be directly tested at top factories, such as the CERN LHC and the DESY TESLA. We discuss some examples of observables from K and B physics, such as the branching ratio of ${K}_{L}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{ u}\overline{\ensuremath{ u}},$ the ${B}_{s}^{0}$ mass difference, or the time-dependent $\mathrm{CP}$ asymmetry in ${B}_{s}^{0}\ensuremath{\rightarrow}{D}_{s}^{+}{D}_{s}^{\ensuremath{-}},$ which can also show large new effects.