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.

Lyapunov Exponents and Smooth Ergodic Theory

Abstract: Introduction Lyapunov stability theory of differential equations Elements of nonuniform hyperbolic theory Examples of nonuniformly hyperbolic systems Local manifold theory Ergodic properties of smooth hyperbolc measures Bibliography Index

Vision-based navigation and environmental representations with an omnidirectional camera

Abstract: Proposes a method for the visual-based navigation of a mobile robot in indoor environments, using a single omnidirectional (catadioptric) camera. The geometry of the catadioptric sensor and the method used to obtain a bird's eye (orthographic) view of the ground plane are presented. This representation significantly simplifies the solution to navigation problems, by eliminating any perspective effects. The nature of each navigation task is taken into account when designing the required navigation skills and environmental representations. We propose two main navigation modalities: topological navigation and visual path following. Topological navigation is used for traveling long distances and does not require knowledge of the exact position of the robot but rather, a qualitative position on the topological map. The navigation process combines appearance based methods and visual servoing upon some environmental features. Visual path following is required for local, very precise navigation, e.g., door traversal, docking. The robot is controlled to follow a prespecified path accurately, by tracking visual landmarks in bird's eye views of the ground plane. By clearly separating the nature of these navigation tasks, a simple and yet powerful navigation system is obtained.

Optimal Location of Charging Stations for Electric Vehicles in a Neighborhood in Lisbon, Portugal:

Abstract: Growing concerns about environmental issues have led to the consideration of alternatives to current mobility. Electric mobility is one such alternative that is receiving a great deal of attention in Europe. In particular, a new legal framework for the introduction of an electric mobility system in Portugal has recently been set up by the government. A key issue in this system is recharging the batteries and, consequently, the location of charging stations. This paper presents a study on the location of electric-vehicle charging stations for an area of Lisbon, the capital city of Portugal, characterized with a strong concentration of population and employment. This type of area is appropriate for slow charging because vehicles stay parked for several hours within a 24-h period. The methodology used here is based on a maximal covering model to optimize the demand covered within an acceptable level of service and to define the number and capacity of the stations to be installed. The results clearly indicate...

Shadows and strong gravitational lensing: a brief review

Abstract: For ultra compact objects, light rings and fundamental photon orbits (FPOs) play a pivotal role in the theoretical analysis of strong gravitational lensing effects, and of BH shadows in particular. In this short review, specific models are considered to illustrate how FPOs can be useful in order to understand some non-trivial gravitational lensing effects. This paper aims at briefly overviewing the theoretical foundations of these effects, touching also some of the related phenomenology, both in general relativity and alternative theories of gravity, hopefully providing some intuition and new insights for the underlying physics, which might be critical when testing the Kerr black hole hypothesis.

A High Spatial Resolution Analysis of the MAXIMA-1 Cosmic Microwave Background Anisotropy Data

Abstract: We extend the analysis of the MAXIMA-1 cosmic microwave background data to smaller angular scales. MAXIMA, a bolometric balloon-borne experiment, mapped a 124 deg2 region of the sky with 10' resolution at frequencies of 150, 240, and 410 GHz during its first flight. The original analysis, which covered the multipole range 36 ≤ l ≤ 785 using a 100 deg2 map, is extended to l = 1235 using a subset of the data from three 150 GHz photometers in the fully cross-linked central 60 deg2 of the map. The main improvement over the original analysis is the use of 3' square pixels in the calculation of the map. The new analysis is consistent with the original for l 785, where inflationary models predict a third acoustic peak, the new analysis shows power with an amplitude of 56 ± 7 μK at l 850 in excess to the average power of 42 ± 3 μK in the range 441 < l < 785.