Rationale for a new class of double-hybrid approximations in density-functional theory

We provide a rationale for a new class of double-hybrid approximations introduced by Br\'emond and Adamo [J. Chem. Phys. 135, 024106 (2011)] which combine an exchange-correlation density functional with Hartree-Fock exchange weighted by \l and second-order M{\o}ller-Plesset (MP2) correlation weighted by \l^3. We show that this double-hybrid model can be understood in the context of the density-scaled double-hybrid model proposed by Sharkas et al. [J. Chem. Phys. 134, 064113 (2011)], as approximating the density-scaled correlation functional E_c[n_{1/\l}] by a linear function of \l, interpolating between MP2 at \l=0 and a density-functional approximation at \l=1. Numerical results obtained with the Perdew-Burke-Ernzerhof density functional confirms the relevance of this double-hybrid model.Comment: 4 pages, 2 figures, to appear in Journal of Chemical Physic

Cognitive visual tracking and camera control

Cognitive visual tracking is the process of observing and understanding the behaviour of a moving person. This paper presents an efficient solution to extract, in real-time, high-level information from an observed scene, and generate the most appropriate commands for a set of pan-tilt-zoom (PTZ) cameras in a surveillance scenario. Such a high-level feedback control loop, which is the main novelty of our work, will serve to reduce uncertainties in the observed scene and to maximize the amount of information extracted from it. It is implemented with a distributed camera system using SQL tables as virtual communication channels, and Situation Graph Trees for knowledge representation, inference and high-level camera control. A set of experiments in a surveillance scenario show the effectiveness of our approach and its potential for real applications of cognitive vision

Quasi-static Free-Boundary Equilibrium of Toroidal Plasma with CEDRES++: Computational Methods and Applications

International audienceWe present a comprehensive survey of the various computational methods in CEDRES++ for finding equilibria of toroidal plasma. Our focus is on free-boundary plasma equilib-ria, where either poloidal field coil currents or the temporal evolution of voltages in poloidal field circuit systems are given data. Centered around a piecewise linear finite element representation of the poloidal flux map, our approach allows in large parts the use of established numerical schemes. The coupling of a finite element method and a boundary element method gives consistent numerical solutions for equilibrium problems in unbounded domains. We formulate a new Newton method for the discretized non-linear problem to tackle the various non-linearities, including the free plasma boundary. The Newton method guarantees fast convergence and is the main building block for the inverse equilibrium problems that we can handle in CEDRES++ as well. The inverse problems aim at finding either poloidal field coil currents that ensure a desired shape and position of the plasma or at finding the evolution of the voltages in the poloidal field circuit systems that ensure a prescribed evolution of the plasma shape and position. We provide equilibrium simulations for the tokamaks ITER and WEST to illustrate the performance of CEDRES++ and its application areas

Expérimentation d'une plate-forme de portage logiciel à l'INRIA

National audienceAu sein de l'INRIA, les équipes projets qui développent des logiciels scientifiques sont confrontées, dès lors qu'elles veulent les distribuer, au portage sur une multiplicité d'environnements matériels et logiciels en constante évolution. Les tâches de portage logiciel sont réalisées par l'intermédiaire de leurs propres parcs de machines hétérogènes qui posent des problèmes d'hébergement, d'administration système et de maintenance. Les configurations spécifiques sur de nombreuses combinaisons possibles d'architectures et de systèmes ne permettent pas d'envisager une solution de mutualisation à partir de serveurs de connexion classiques. PIPOL (Plate-forme Inria de POrtage Logiciel) est une expérimentation d'un service de portage pour les logiciels scientifiques à l'échelle de l'INRIA. Les ressources matérielles sont partagées et disponibles après réservation et déploiement du système d'exploitation souhaité. Un service permet la configuration automatique des systèmes, la planification et le traitement de travaux utilisateurs

A Computer system to monitor older adults at home: Preliminary results

International audienceDetermining the individual transition from the 3rd to the 4th of frailty phase of life is important for both the safety of the older person and to support the care provider. We developed an automatic monitoring system consisting of cameras and different sensors that analyze human behaviors and looks for changes in their activities by detecting the presence of people, their movements, and automatically recognizing events and Activities of Daily Living (ADLs). Assessment took place in a laboratory environment (GERHOME) comprised of four rooms (kitchen, living-room, bedroom, and bathroom). Data from 2 volunteers (64 and 85 years old) were analyzed. Precision in recognizing postures and events ranged from 62-94%, while sensitivity fell in the range of 62-87%. The system could differentiate ADL levels for the 64 and 85 year old subjects. These results are promising and merit replication and extension. Considerable work remains before the complete transition from 3rd to 4th life phase can be reliably detected. The GERHOME system is promising in this respect

Assistive technologies to address capabilities of people with dementia: from research to practice

Assistive technologies (AT) became pervasive and virtually present in all our life domains. They can be either an enabler or an obstacle leading to social exclusion. The Fondation Médéric Alzheimer gathered international experts of dementia care, with backgrounds in biomedical, human and social sciences, to analyse how AT can address the capabilities of people with dementia, on the basis of their needs. Discussion covered the unmet needs of people with dementia, the domains of daily life activities where AT can provide help to people with dementia, the enabling and empowering impact of technology to improve their safety and wellbeing, barriers and limits of use, technology assessment, ethical and legal issues. The capability approach (possible freedom) appears particularly relevant in person-centered dementia care and technology development. The focus is not on the solution, rather on what the person can do with it: seeing dementia as disability, with technology as an enabler to promote capabilities of the person, provides a useful framework for both research and practice. This article summarizes how these concepts took momentum in professional practice and public policies in the past fifteen years (2000-2015), discusses current issues in the design, development and economic model of AT for people with dementia, and covers how these technologies are being used and assessed

Simulation ab initio de spectres UV-visibles

UV-visible response factors are commonly used in analytical chemistry in order to evaluate the different compound proportions of a mix. Particularly popular in the industrial field, most of the time these factors are difficult to obtain, mainly when implicated compounds are difficult to isolate or to synthesize. In this context, theoretical chemistry - and more precisely Time Dependent Density Functional Theory (TD-DFT) --- could be a useful asset able to give rapid answers. In order to obtain this type of information, a study focused on UV-visible spectroscopy is needed. This study underlines the TD-DFT capacity to simulate at the same time the position of the absorption bands and to provide information related to quantification. Along these lines, some new density functionals were developed in order to try to increase the accuracy of the method from a structural point of view or property simulation like excitation energies. All in all, many models were tested --- some of them were developed --- in order to reproduce with the best accuracy the band shape of UV-visible absorption spectra. Not only focused on absorption, this study also tries to model fluorescence, showing the useful role of theoretical chemistry in science and in industry.Les facteurs de réponse UV-visible sont des éléments clés utilisés en chimie analytique afin d'évaluer les proportions des différents constituants d'un mélange. Particulièrement prisés par le monde de l'industrie, ces facteurs sont le plus souvent difficiles à obtenir, surtout lorsque les composés mis en jeu sont des impuretés difficiles à isoler ou à synthétiser. Dans ce contexte, la chimie théorique, et plus particulièrement la Théorie de la Fonctionnelle de la Densité Dépendant du Temps peut devenir un atout non négligeable, capable d'apporter des réponses en un minimum de temps. Afin de parvenir à ce type d'informations, une étude approfondie de la spectroscopie UV-visible est nécessaire. Cette étude met en lumière les capacités de la TD-DFT à simuler, non seulement la position des bandes d'absorption d'un spectre, mais également à être utilisée pour faire de la quantification de composés. À ce titre, plusieurs nouvelles fonctionnelles de la densité ont ici été développées afin de tenter d'améliorer la précision de la méthode, à la fois d'un point de vue structural, et d'un point de vue de la simulation de propriétés comme les énergies d'excitations. En somme, plusieurs modèles ont été éprouvés, dont certains développés, tous visant principalement à reproduire au mieux la structure parfois complexe des bandes d'absorption d'un spectre UV-visible. Non seulement centrée sur le processus d'absorption, cette étude s'étend également au processus de fluorescence, montrant et démontrant l'utilité de la chimie théorique en science et dans l'industrie

Assessment of the ground spin state of iron(I) complexes : insights from DFT predictive models

International audienceAn efficient DFT benchmarking method is described for the assessment of the ground spin state of various iron(I) organometallic complexes. Factors determining the spin multiplicity are discussed. A focus is put on the analysis of the electronic structure of bis-ligated X$-$[Fe$^I$]$-$X species

The nature of vertical excited states of dyes containing metals for DSSC applications: insights from TD-DFT and density based indexes

International audienceTransition metal complexes, typically Ru-based complexes, are the most efficient dyes used in dye-sensitized solar cells. The absorption spectra of these molecules generally involve numerous electronic transitions, which are not equivalent for the conversion of the light into electricity. In the present manuscript, an analysis of each electronic transition of selected inorganic complexes is performed based on the variation of the electronic density upon light absorption. To this end, a series of indices recently proposed in the literature is applied. The main conclusions of this work are twofold: from a methodological point of view, global hybrid functionals confirm their robustness for studying the electronic transitions of these compounds and from an application oriented point of view it is clear that the most intense transitions are not necessarily the most efficient ones for the light conversion