A Robust Localization System for Inspection Robots in Sewer Networks †

Sewers represent a very important infrastructure of cities whose state should be monitored periodically. However, the length of such infrastructure prevents sensor networks from being applicable. In this paper, we present a mobile platform (SIAR) designed to inspect the sewer network. It is capable of sensing gas concentrations and detecting failures in the network such as cracks and holes in the floor and walls or zones were the water is not flowing. These alarms should be precisely geo-localized to allow the operators performing the required correcting measures. To this end, this paper presents a robust localization system for global pose estimation on sewers. It makes use of prior information of the sewer network, including its topology, the different cross sections traversed and the position of some elements such as manholes. The system is based on a Monte Carlo Localization system that fuses wheel and RGB-D odometry for the prediction stage. The update step takes into account the sewer network topology for discarding wrong hypotheses. Additionally, the localization is further refined with novel updating steps proposed in this paper which are activated whenever a discrete element in the sewer network is detected or the relative orientation of the robot over the sewer gallery could be estimated. Each part of the system has been validated with real data obtained from the sewers of Barcelona. The whole system is able to obtain median localization errors in the order of one meter in all cases. Finally, the paper also includes comparisons with state-of-the-art Simultaneous Localization and Mapping (SLAM) systems that demonstrate the convenience of the approach.Unión Europea ECHORD ++ 601116Ministerio de Ciencia, Innovación y Universidades de España RTI2018-100847-B-C2

Critical dynamics of active phase separation: A scalar field theory approach

This thesis studies the critical properties of several systems under the overarching theme of active matter. These are systems that constantly consume energy at particle level and transform it into motion. Several field theories have been proposed as continuum descriptions of isotropic systems of self-propelled particles, that are able to reproduce some of the phenomena observed in these systems at particle level, mainly motility-induced phase separation (MIPS). This is a form of phase separation in the absence of attractive interactions that is not present in these systems' passive counterparts. These theories are built as extensions of models of equilibrium phase separation (Model B) that minimally break detailed balance. This thesis addresses the question of how these field theories behave at criticality, in the transition between uniform and phase separated states, and whether this transition lies in the Ising-like universality class of the background equilibrium model, or instead belongs to a new universality class. The first model analysed, named here conserved KPZ+, is a simplification of the main MIPS model studied, and proves to be a general model for surface growth with conserved mass, not present in the literature. This system has an Renormalization Group flow that, to one loop, shows a strong coupling regime in and above its critical dimension d_c = 2 that was not present in the previous systems considered to model this physical process. This strong coupling regime is also explored numerically, showing that the equation of motion indeed has a more complex phase diagram than it was thought for these surfaces. The full field theory for MIPS is then analysed using Renormalization Group. The results are that, between 2 and 4 dimensions, a new fixed point appears as an extension of the Wilson-Fisher fixed point. This new fixed point rules a new transition to a strong coupling regime not present in the equilibrium Model B. The perturbative nature of the RG approach leaves the quantitative characterization of this phase as an open question, but the phase diagram obtained matches roughly the one explored numerically in the literature, and strongly suggests that the strong coupling regime represents a new universality class of nonequilibrium phase separation. Finally, the entropy production rate (EPR) is studied for these active field theories close to the equilibrium critical points. The results indicate that the EPR per correlation volume can be constant or even diverge close to the equilibrium critical points, meaning that even though the dynamics of these systems are effectively in equilibrium, there is a nontrivial critical scaling for the EPR that is part of Ising-like universality classes.EPSR

Sobre el proceso de cristianización de los pueblos eslavos

En este artículo se trata de reflexionar sobre los aspectos generales del proceso de cristianización de los eslavos. La finalidad no es la exposición del proceso de modo narrativo, sino tratar de ofrecer una síntesis de los aspectos y elementos que constituyeron y caracterizaron el mismo. De este modo, se comenzará por identificar los orígenes espacio-temporales y sociales del proceso de la conversión al cristianismo. A continuación se tratará de identificar los agentes históricos del mismo y los contextos que permitan hacer una interpretación ulterior de los acontecimientos referidos a la cristianización. Por último, se ofrecerá una breve reflexión en torno a la fusión entre la fe cristiana y la cultura eslava, así como la permanencia de elementos paganos en la misma.In this article we are going to reflect on the general aspects which are involved in the Slavic Christianization process. The aim is not to explain the process in a narrative way, but rather to try to offer a synthesis of the different aspects and elements that made up and characterized the process itself. We will start by identifying the time, space and social dimensions at the origin of the Christianization process. We will then try to identify its historical agents and the context. This will allow us to better understand the events that lead to Christianization itself. Finally, we will offer some thoughts about the integration between Christian faith and Slav culture, as well as the permanence of pagan elements in the latter.peerReviewe

Decision-Theoretic Planning with Person Trajectory Prediction for Social Navigation

Robots navigating in a social way should reason about people intentions when acting. For instance, in applications like robot guidance or meeting with a person, the robot has to consider the goals of the people. Intentions are inherently nonobservable, and thus we propose Partially Observable Markov Decision Processes (POMDPs) as a decision-making tool for these applications. One of the issues with POMDPs is that the prediction models are usually handcrafted. In this paper, we use machine learning techniques to build prediction models from observations. A novel technique is employed to discover points of interest (goals) in the environment, and a variant of Growing Hidden Markov Models (GHMMs) is used to learn the transition probabilities of the POMDP. The approach is applied to an autonomous telepresence robot

DLL: Direct LIDAR Localization. A map-based localization approach for aerial robots

This paper presents DLL, a fast direct map-based localization technique using 3D LIDAR for its application to aerial robots. DLL implements a point cloud to map registration based on non-linear optimization of the distance of the points and the map, thus not requiring features, neither point correspondences. Given an initial pose, the method is able to track the pose of the robot by refining the predicted pose from odometry. Through benchmarks using real datasets and simulations, we show how the method performs much better than Monte-Carlo localization methods and achieves comparable precision to other optimization-based approaches but running one order of magnitude faster. The method is also robust under odometric errors. The approach has been implemented under the Robot Operating System (ROS), and it is publicly available.Comment: Accepted for IROS2021. Associated code can be downloaded from https://github.com/robotics-upo/dl

The role of structural pleiotropy in the retention of protein complexes after gene duplication

La duplication de gènes est l’un des plus importants mécanismes évolutifs pour la génération de diversité fonctionelle. Lorsqu’un gène est dupliqué, la nouvelle copie partage toutes ses fonctions avec la copie ancestrale car elles encodent pour des protéines identiques. Donc, les deux protéines, appelées paralogues, auront le même réseau d’interactions physiques protéine-protéine. Cependant, dans le cas de la duplication des gènes qui codent des protéines qui interagissent avec elles-mêmes (homomères), la nouvelle protéine interagira aussi avec la copie ancestrale, ce qui introduit une nouvelle interaction (heteromère) (Kaltenegger and Ober, 2015; Pereira-Leal et al., 2007). Puisque ces interactions peuvent avoir des différents motifs de rétention et de fonction (Ashenberg et al., 2011; Baker et al., 2013; Boncoeur et al., 2012; Bridgham et al., 2008), il est important de mieux comprendre comment ces états sont atteints et quelles forces évolutives les favorisent. Dans ce memoire, je cible ces questions avec des simulations in silico de l’évolution des protéines suite à la duplication de gènes en travaillant avec des structures crystallographiques de haute qualité, provenant de la Protein Data Bank (Berman et al., 2000; Dey et al., 2018). Les simulations montrent que les sous-unités et interfaces partagées entraînent une forte corrélation entre les trajectoires évolutives de ces complexes. Ainsi, les simulations prédisent que la préservation de seulement les deux homomères ou seulement l’hétéromère ne devrait pas être fréquente. Toutefois, la simulation qui applique la sélection seulement sur un homomère montre que l’homomère neutre est destabilisé plus rapidement que l’hétéromère neutre. Nous avons comparé ces prédictions avec des résultats expérimentaux du réseau d’interactions protéine-protéine de la levure. Comme suggéré par les simulations, les patrons d’interactions les plus fréquents ont été la formation des trois complexes (deux homomères et un hétéromère) ou la formation de seulement un homomère. Les patrons correspondants à deux homomères sans hétéromères ou un hétéromère sans homomères sont rares. Nos résultats démontrent l’extension de l’hétéromérisation entre paralogues dans le réseau d’interactions physiques protéine-protéine de la levure, les mécanismes sous-jacents et ses implications.Gene duplication is one of the most important evolutionary mechanisms for the generation of functional diversity. When a gene is duplicated, the new copy shares all of the ancestral copy’s functions because they encode identical proteins. Therefore, the two proteins, called paralogs, will have the same protein-protein interaction network. However, in the case of the duplication of genes encoding proteins that self-interact (homomers), the new protein will also interact with the ancestral copy, introducing a novel interaction (heteromer) (Kaltenegger and Ober, 2015; Pereira-Leal et al., 2007). As these interactions can have different retention and functional patterns (Ashenberg et al., 2011; Baker et al., 2013; Boncoeur et al., 2012; Bridgham et al., 2008), it is important to understand better how these states are reached and what evolutionary forces favor each of them. In this thesis, I approach these questions by means of in silico simulations of protein evolution after gene duplication by working with high-quality crystal structures from the Protein Data Bank (Berman et al., 2000; Dey et al., 2018). The simulations show that the shared subunits and interfaces lead to these complexes having highly correlated evolutionary trajectories. Thus, the simulations predict that the preservation of only the two homomers or only the heteromer is not likely to happen often. Nevertheless, simulating evolution with selection on only one homomer shows that the neutral homomer is destabilized faster than the neutral heteromer. We compared these predictions against experimental results from the yeast protein-protein interaction network. As suggested by the simulations, the most abundant interaction patterns were either the formation of all three complexes (two homomers and one heteromer) or the formation of only one homomer, with motifs corresponding to two homomers without a heteromer or a heteromer without homomers being rare. Our results highlight the extent of heteromerization between paralogs in the yeast protein-protein interaction network, the underlying mechanisms, and its implication

Estudio y aplicación del algoritmo de Davidon a la optimización del gobierno en tiempo mínimo de sistemas lineales

Un método algorítmico de minimización será eficaz cuando esté concebido de manera que converja en todo momento y que, al llegar a la vecindad del mínimo, se adapte a la geografía de segundo grado para converger ya con rapidez cuadrática. El método de Davidon pertenece a esta clase

Activity suppressed phase separation

We use a continuum model to examine the effect of activity on a phase separating mixture of an extensile active nematic and a passive fluid. We highlight the distinct role of previously considered interfacial active stresses and bulk active stresses that couple to liquid crystalline degrees of freedom. Interfacial active stresses can arrest phase separation, as previously demonstrated. Bulk extensile active stresses can additionally strongly suppress phase separation by sustained self-stirring of the fluid, substantially reducing the size of the coexistence region in the temperature/concentration plane relative to that of the passive system. The phase separated state is a dynamical emulsion-like steady state of continuously splitting and merging droplets, as suggested by recent experiments. Using scaling analysis and simulations, we identify various regimes for the dependence of droplet size on activity. These results can provide a criterion for identifying the mechanisms responsible for arresting phase separation in experiments