Pseudo-heteroclinic connections between bicircular restricted four-body problems

In this paper, we show a mechanism to explain transport from the outer to the inner Solar system. Such a mechanism is based on dynamical systems theory. More concretely, we consider a sequence of uncoupled bicircular restricted four-body problems –BR4BP –(involving the Sun, Jupiter, a planet and an infinitesimal mass), being the planet Neptune, Uranus and Saturn. For each BR4BP, we compute the dynamical substitutes of the collinear equilibrium points of the corresponding restricted three-body problem (Sun, planet and infinitesimal mass), which become periodic orbits. These periodic orbits are unstable, and the role that their invariant manifolds play in relation with transport from exterior planets to the inner ones is discussed.Peer ReviewedPostprint (published version

Sustainability and resilience of coastal tourist destinations: notes from the smart destinations approach

Con la crisis provocada por la COVID-19 el concepto de resiliencia ha ganado importancia en el sector turístico, uno de los más afectados. Esta pausa ha provocado que se plantee un cambio de modelo basado en la sostenibilidad donde el modelo de Destinos Turísticos Inteligentes (DTI) aparecen como los principales beneficiados de esta crisis, ya que consiguen superar el objetivo del crecimiento y tienen un enfoque de planificación y gestión directamente relacionado la sostenibilidad del sector turístico. En este trabajo se pretende, mediante el análisis de diversos indicadores, caracterizar la relación entre sostenibilidad y resiliencia, analizar la contribución del modelo DTI a la sostenibilidad, identificar su posibles limitaciones, e identificar nuevas posibilidades para hacer más resilientes los destinos. Evolucionar hacia destinos más inteligentes requiere más atención que no unos simples indicadores y la interrelación de diferentes dimensiones: ambiental, sociocultural,… que junto con la incorporación de los ODS 2030, nos lleve hacia un modelo más integrado y sostenible.With the crisis caused by COVID-19, the concept of resilience has gained importance in the tourism sector, one of the most affected. This pause has provoked a change of model based on sustainability where the model of Smart Tourism Destinations (ITD) appear as the main beneficiaries of this crisis since they manage to overcome the objective of growth and have a planning and management approach contributing to the sustainability of the tourism sector and acting as a good example. This paper aims through the analysis of indicators to characterize the relationship between sustainability and resilience, to analyze the contribution of the DTI model to sustainability and its implications for becoming more resilient, as well as to identify limitations and identify new possibilities to make destinations more resilient. Evolving towards smarter destinations requires more attention than simple indicators and the interrelation of different dimensions: environmental, socio-cultural,... that together with the incorporation of the SDG 2030, will lead us towards a more integrated and sustainable model

On central configurations of the kn-body problem

We consider planar central configurations of the Newtonian kn-body problem consisting in k groups of regular n-gons of equal masses, called (k, n)-crown. We derive the equations of central configurations for a general (k, n)-crown. When k = 2 we prove the existence of a twisted (2, n)-crown for any value of the mass ratio. Moreover, for n = 3,4 and any value of the mass ratio, we give the exact number of twisted (2, n)-crowns, and describe their location. Finally, we conjecture that for any value of the mass ratio there exist exactly three (2, n)-crowns for n = 5.Peer ReviewedPostprint (author's final draft

Convex central configurations of two twisted n-gons

Extended Conference abstract corresponding to talk given at the "Conference on Hamiltonian Systems and Celestial Mechanics 2014" (HAMSYS2014) held at the Centre de Recerca Matemàtica (CRM) in Barcelona from June 2nd to 6th, 2014. The talk is about Central Configurations, Periodic Orbits and Hamiltonian Systems with applications to Celestial Mechanics - a very modern and active field of researc

On strictly convex central configurations of the 2n-body problem

We consider planar central configurations of the Newtonian 2n-body problem consisting in two twisted regular n-gons of equal masses. We prove the conjecture that for n=5 all convex central configurations of two twisted regular n-gons are strictly convex.Peer ReviewedPostprint (author's final draft

The dynamics around the collinear point L3 of the RTBP

We consider the Restricted Three Body Problem (RTBP), and we restrict our attention to the equilibrium point L3. Our aim is centered in the description, as global as possible, of the dynamics around this equilibrium point. In this communication, we initially consider small values of µ, for which homoclinic connections to the equilibrium point L3 are horseshoe-shaped, and then, other values of µ are considered. We compute the objects in the center manifold of L3, including the invariant manifolds associated with them. They are computed by purely numerical procedures, in order to avoid the convergence restrictions of the semi-analytical ones (typically used around L1 or L2). We deal with homoclinic connections of periodic orbits and develop some numerical tools in order to compute them. These tools can be extended to compute also homoclinic connections to invariant tori

Estudio práctico de mecanismos de seguridad en dispositivos Android

Android climbed up to 80 percent of the smartphone and mobile devices market share. One of the key aspects for the acceptance of a mobile OS is the security degree the user perceives from the system. In this article, we explore some of the important security mechanisms implemented in Google Android through the study of several recent vulnerabilities. Particularly, we discuss a recent security issue in WhatsApp, the dangers of connecting devices to external machines and the security of current mechanisms for access control. We describe these vulnerabilities through in-lab proof-of-concepts. The experience learned from these cases is used to propose better practices for improving the security of the system.Este trabajo se ha financiado en parte por los proyectos TAMESIS (TEC2011-22746) y ARES (CSD2007-00004)

Simulation of millimeter-wave body images and its application to biometric recognition

Miriam Moreno-Moreno ; Julian Fierrez ; Ruben Vera-Rodriguez ; Josep Parron; "Simulation of millimeter-wave body images and its application to biometric recognition", Passive and Active Millimeter-Wave Imaging XV, Proc. SPIE 8362 (May 1, 2012); doi:10.1117/12.918549. Copyright 2012 Society of Photo‑Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.Proceedings of the Passive and Active Millimeter-Wave Imaging XV (Baltimore, Maryland, USA)One of the emerging applications of the millimeter-wave imaging technology is its use in biometric recognition. This is mainly due to some properties of the millimeter-waves such as their ability to penetrate through clothing and other occlusions, their low obtrusiveness when collecting the image and the fact that they are harmless to health. In this work we first describe the generation of a database comprising 1200 synthetic images at 94 GHz obtained from the body of 50 people. Then we extract a small set of distance-based features from each image and select the best feature subsets for person recognition using the SFFS feature selection algorithm. Finally these features are used in body geometry authentication obtaining promising results.This work has been partially supported by projects Bio-Challenge (TEC2009-11186), Contexts (S2009/TIC-1485), TeraSense (CSD2008-00068) and “Cátedra UAM-Telefónica”

Aplicació mòbil pel control del consum elèctric

El present projecte té com a objectiu dissenyar una aplicació mòbil capaç de monitoritzar el consum elèctric d’un habitatge i així ser una eina per millorar l’eficiència energètica amb un cost reduït. Per aconseguir-ho s’ha realitzat dos prototips diferents que mesuren la corrent que circula pel cable de fase i envia les dades obtingudes del sensor a una base de dades a través del wifi domèstic. L’aplicació mòbil rep la informació emmagatzemada des de la base de dades, en fa el tractament i càlculs necessaris i mostra informació de l’estat actual amb la potència instantània, consum, cost, potència màxima i mínima. Es permet a l’usuari seleccionar un dia en concret o un període i mostrar les dades a l’aplicació. L’aplicació és capaç de visualitza un gràfic de barres de consums diaris segons el període que selecciona l’usuari. Finalment l’aplicació permet optimitzar la potència a contractar a partir dels màxims diaris registrats durant un període llarg. Així l’usuari pot comprovar si té un bon contracte i si es reduís la potència quin estalvi anual obtindria