Who am I talking with? A face memory for social robots

In order to provide personalized services and to develop human-like interaction capabilities robots need to rec- ognize their human partner. Face recognition has been studied in the past decade exhaustively in the context of security systems and with significant progress on huge datasets. However, these capabilities are not in focus when it comes to social interaction situations. Humans are able to remember people seen for a short moment in time and apply this knowledge directly in their engagement in conversation. In order to equip a robot with capabilities to recall human interlocutors and to provide user- aware services, we adopt human-human interaction schemes to propose a face memory on the basis of active appearance models integrated with the active memory architecture. This paper presents the concept of the interactive face memory, the applied recognition algorithms, and their embedding into the robot’s system architecture. Performance measures are discussed for general face databases as well as scenario-specific datasets

Dependent Lindeberg central limit theorem and some applications

In this paper, a very useful lemma (in two versions) is proved: it simplifies notably the essential step to establish a Lindeberg central limit theorem for dependent processes. Then, applying this lemma to weakly dependent processes introduced in Doukhan and Louhichi (1999), a new central limit theorem is obtained for sample mean or kernel density estimator. Moreover, by using the subsampling, extensions under weaker assumptions of these central limit theorems are provided. All the usual causal or non causal time series: Gaussian, associated, linear, ARCH($\infty$), bilinear, Volterra processes,$...$, enter this frame

Local existence of dynamical and trapping horizons

Given a spacelike foliation of a spacetime and a marginally outer trapped surface S on some initial leaf, we prove that under a suitable stability condition S is contained in a ``horizon'', i.e. a smooth 3-surface foliated by marginally outer trapped slices which lie in the leaves of the given foliation. We also show that under rather weak energy conditions this horizon must be either achronal or spacelike everywhere. Furthermore, we discuss the relation between ``bounding'' and ``stability'' properties of marginally outer trapped surfaces.Comment: 4 pages, 1 figure, minor change

Classification des types de prairies et estimation de la diversité taxonomique à partir de séries temporelles d'images satellites

La télédétection offre de nombreuses possibilités pour caractériser la végétation aussi bien par sa composition que par sa structure. Si la capacité de cet outil à caractériser les milieux mono-spécifiques comme les grandes cultures a été montrée à de nombreuses reprises, plus de difficultés sont rencontrées lors de l’étude de milieux pluri-spécifiques comme les prairies. En effet, le mélange des espèces dans un milieu renvoie des valeurs radiométriques difficiles à interpréter. Dans ce contexte, l’objectif de ce stage est de caractériser le mode de gestion et la composition botanique des prairies à partir d’une série temporelle d’images satellites Formosat-2. Des relevés botaniques et des enquêtes sur le mode de conduite d’une cinquantaine de prairies ont été réalisés lors d’une campagne de terrain. Des typologies botaniques ont été construites avec une approche fonctionnelle de la composition en espèces, qui permet de rendre compte de la valeur d’usage agricole. Les prairies ont ainsi été distinguées selon leur précocité, leur potentiel de productivité, et la richesse en formes de vie (graminées, légumineuses, et diverses). Elles ont aussi été distinguées selon les différents modes de conduite qui ont été identifiés sur le terrain (prairies fauchées une fois, prairies fauchées deux fois, prairies pâturées et prairies mixtes). Des classifications supervisées ont été réalisées sur chacune de ces typologies et différents modèles linéaires ont été construits pour relié directement les taux de recouvrement des formes de vies avec les valeurs radiométriques enregistrées par les images. Les résultats indiquent qu’il est possible de distinguer les prairies fauchées des prairies mises en pâture avec une précision globale de plus de 80%. En revanche, la distinction des classes botaniques est difficile, notamment en raison du manque d’informations sur des paramètres non contrôlés, et d’un échantillonnage parfois irrégulier. De même, les modèles linéaires construits n’expliquent que très peu la composition botanique à partir des variables spectrales utilisées

mlr3spatiotempcv: Spatiotemporal resampling methods for machine learning in R

Spatial and spatiotemporal machine-learning models require a suitable framework for their model assessment, model selection, and hyperparameter tuning, in order to avoid error estimation bias and over-fitting. This contribution reviews the state-of-the-art in spatial and spatiotemporal cross-validation, and introduces the {R} package {mlr3spatiotempcv} as an extension package of the machine-learning framework {mlr3}. Currently various {R} packages implementing different spatiotemporal partitioning strategies exist: {blockCV}, {CAST}, {skmeans} and {sperrorest}. The goal of {mlr3spatiotempcv} is to gather the available spatiotemporal resampling methods in {R} and make them available to users through a simple and common interface. This is made possible by integrating the package directly into the {mlr3} machine-learning framework, which already has support for generic non-spatiotemporal resampling methods such as random partitioning. One advantage is the use of a consistent nomenclature in an overarching machine-learning toolkit instead of a varying package-specific syntax, making it easier for users to choose from a variety of spatiotemporal resampling methods. This package avoids giving recommendations which method to use in practice as this decision depends on the predictive task at hand, the autocorrelation within the data, and the spatial structure of the sampling design or geographic objects being studied.Comment: 35 pages, 15 Figures, 1 Tabl

Monoclonal gammopathy missed by capillary zone electrophoresis

Background: Serum protein electrophoresis is used as a screening test for monoclonal gammopathies. Here, we present a case of a high-concentration monoclonal immunoglobulin (M-protein) that was missed by serum protein electrophoresis on a Capillarys 2 capillary zone electrophoresis system. The aim of our study was to identify the reason for the failure of the system to detect the M-protein. Methods: M-protein solubility was examined in response to temperature, pH, ionic strength, the chaotropic agent urea and the reducing agent 2-mercaptoethanol. Results: Precipitation of the M-protein was not cold-induced, but solubility decreased at pH 8.5 or higher, when the pH approached the apparent isoelectric point. The M-protein also precipitated in alkaline Capillarys 2 electrophoresis buffer (pH 10), which was the reason for the false-negative electrophoresis result. Precipitation of the M-protein was not related to the ionic strength of the buffer. Solubility improved in presence of urea. Pre-treatment of serum with 2-mercaptoethanol revealed the missing M-protein peak of 36g/L on the electropherogram. Conclusions: This case shows that insolubility of M-proteins in alkaline buffer is one possible cause of false-negative results on capillary zone electrophoresis systems. False-negative results should be considered, especially when accompanying laboratory results are inconsistent with the electropherogra

Modeling and frequency domain analysis of nonlinear compliant joints for a passive dynamic swimmer

In this paper we present the study of the mathematical model of a real life joint used in an underwater robotic fish. Fluid-structure interaction is utterly simplified and the motion of the joint is approximated by D\"uffing's equation. We compare the quality of analytical harmonic solutions previously reported, with the input-output relation obtained via truncated Volterra series expansion. Comparisons show a trade-off between accuracy and flexibility of the methods. The methods are discussed in detail in order to facilitate reproduction of our results. The approach presented herein can be used to verify results in nonlinear resonance applications and in the design of bio-inspired compliant robots that exploit passive properties of their dynamics. We focus on the potential use of this type of joint for energy extraction from environmental sources, in this case a K\'arm\'an vortex street shed by an obstacle in a flow. Open challenges and questions are mentioned throughout the document.Comment: 12 p, 5 fig, work in progress, collaborative wor