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Predicting the Solar Potential of Rooftops using Image Segmentation and Structured Data
No full textInternational audienceEstimating the amount of electricity that can be produced by rooftop photovoltaic systems is a time-consuming process that requires on-site measurements, a difficult task to achieve on a large scale. In this paper, we present an approach to estimate the solar potential of rooftops based on their location and architectural characteristics, as well as the amount of solar radiation they receive annually. Our technique uses computer vision to achieve semantic segmentation of roof sections and roof objects on the one hand, and a machine learning model based on structured building features to predict roof pitch on the other hand. We then compute the azimuth and maximum number of solar panels that can be installed on a rooftop with geometric approaches. Finally, we compute precise shading masks and combine them with solar irradiation data that enables us to estimate the yearly solar potential of a rooftop
L’accessibilité numérique dans les systèmes numériques d’éducation : une étude portant sur la conception et l’évaluation d’un lecteur MOOC.
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An Ambient Assisted Living platform for supporting aging in place of prefrail and frail older adults: Rationale, HomeAssist plaform, quasiexperimental design, and baseline characteristics
No full textBackground: Ambient Assisted Living (AAL) technology is expected as a promising way for prolonging the aging in place. Very few evidence-based results are provided support to its real value, notably for frail older adults who have high risk of autonomy loss and of entering in nursing home. Objective: HomeAssist (HA) is a human-centered AAL platform offering a large set of applications for three main age-related need domains (Activities of Daily Living, Safety and Social participation), relying on a basic set of entities (sensors, actuators...). The HA intervention involves monitoring as well as assistive services to support independent living at home. The primary outcomes measures are related to aging in place in terms of effectiveness (institutionalization and hospitalization rates) and efficiency (everyday functioning indices). Secondary outcomes measures include indices of frailty, cognitive functioning, and psychosocial health of participants and their caregivers. Every 6 months, user experience and attitudes towards HA are also collected in equipped participants. Concomitantly, HA usages are collected. Methods: A study assessing the HA efficacy has been designed and is now conducted with 131 older adults aged 81.9 (±6.0) years (from autonomous to frail) who lived alone. The study design is quasi-experimental with a duration of 12 months optionally extensible to 24 months. It includes equipped participants, matched with non-equipped participants (n= 474). Followup assessments occurred at 0, 12 and 24 months. Results: The expected results are to inform the AAL value for independent living, but also to yield informed analysis on AAL usages and adoption in frail older individuals
Quantum-Optical Spectrometry in Relativistic Laser–Plasma Interactions Using the High-Harmonic Generation Process: A Proposal
No full textInternational audienceQuantum-optical spectrometry is a recently developed shot-to-shot photon correlation-based method, namely using a quantum spectrometer (QS), that has been used to reveal the quantum optical nature of intense laser–matter interactions and connect the research domains of quantum optics (QO) and strong laser-field physics (SLFP). The method provides the probability of absorbing photons from a driving laser field towards the generation of a strong laser–field interaction product, such as high-order harmonics. In this case, the harmonic spectrum is reflected in the photon number distribution of the infrared (IR) driving field after its interaction with the high harmonic generation medium. The method was implemented in non-relativistic interactions using high harmonics produced by the interaction of strong laser pulses with atoms and semiconductors. Very recently, it was used for the generation of non-classical light states in intense laser–atom interaction, building the basis for studies of quantum electrodynamics in strong laser-field physics and the development of a new class of non-classical light sources for applications in quantum technology. Here, after a brief introduction of the QS method, we will discuss how the QS can be applied in relativistic laser–plasma interactions and become the driving factor for initiating investigations on relativistic quantum electrodynamics
Intrinsic Rewards in Human Curiosity-Driven Exploration: An Empirical Study
No full textInternational audienceDespite their apparent importance for the acquisition of fullfledged human intelligence, mechanisms of intrinsically motivated autonomous learning are poorly understood. How do humans identify useful sources of knowledge and decide which learning situations to approach in the absence of external rewards? While the recognition of this important problem has grown in psychological sciences over the recent years, an intriguing proposition for the possible mechanism comes from artificial intelligence, where efficient autonomous learning is achieved by programming agents to follow the heuristic of maximizing learning progress (LP) during exploration. In this study, we set out to examine the empirical evidence for this idea. Using computational modeling, we demonstrate that humans show signs of following LP while they freely explore and practice a set of multiple learning activities of varying difficulty, including an activity that is impossible to learn. Different approaches to operationalizing the notion of LP and their plausibility in light of empirical data are also discussed. We also show that models combining several types of intrinsic rewards fit better human exploration data than single component models considered so far in theoretical accounts
IoT Data Replication and Consistency Management in Fog computing
No full textInternational audienceFog Computing has emerged as a virtual platform extending Cloud services down to the network edge especially (and not exclusively) to host IoT applications. Data replication strategies have been designed to investigate the best storage location of data copies in geo-distributed storage systems in order to reduce its access time for different consumer services spread over the infrastructure. Unfortunately, due to the geographical distance between Fog nodes, misplacing data in such an infrastructure may generate high latencies when accessing or synchronizing replicas, thus degrading the Quality of Service (QoS). In this paper, we present two strategies to manage IoT data replication and consistency in Fog infrastructures. Our strategies choose for each datum, the right replica number and their location in order to reduce data access latency and replicas synchronization cost. This is done while respecting the required consistency level. Also, we propose an evaluation platform based on the simulator iFogSim to enable users to implement and test their own strategies for IoT data replication and consistency management. Our experiments show that when using our strategies, the service latency can be reduced by 30% in case of small Fog infrastructures and by 13% in case of large scale Fog infrastructures compared to iFogStor, a state-of-the-art strategy that does not use replication
Spectral control of high order harmonics through non-linear propagation effects
No full textInternational audienceigh harmonic generation (HHG) in crystals has revealed a wealth of perspectives such as all-optical mapping of the electronic band structure, ultrafast quantum information, and the creation of all-solid-state attosecond sources. Significant efforts have been made to understandthe microscopic aspects of HHG in crystals, whereas the macroscopic effects, such as non-linear propagation of the driving pulse and itsimpact on the HHG process, are often overlooked. In this work, we study macroscopic effects by comparing two materials with distinct optical properties, silicon (Si) and zinc oxide (ZnO). By scanning the focal position of 85 fs duration and 2.123 lm wavelength pulses inside thecrystals, (Z-scan) we reveal spectral shifts in the generated harmonics. We interpret the overall blueshift of the emitted harmonic spectrumas an imprint of the spectral modulation of the driving field on the high harmonics. This process is supported with numerical simulations.This study demonstrates that through manipulation of the fundamental driving field through non-linear propagation effects, precise controlof the emitted HHG spectrum in solids can be realized. This method could offer a robust way to tailor HHG spectra for a range ofapplications
Conception d'un Système Tutoriel Intelligent (STI) basé sur les progrès d'apprentissage : des étapes formelles aux étapes d'expérimentations chez les enfants
No full textNational audienceBased on the Learning Progression (LP) model of Oudeyer and Gotlieb, 2016, an LP-based ITS approach was designed and implemented in a serious numeracy game (addition and subtraction of numbers in money exchange activities) called KidLearn. In this context, the ITS personalizes learning paths by optimizing LPs (multi-armed bandit-like algorithms), minimizing presuppositions about learners and knowledge domain. First, the adopted ITS approach is presented, followed by its validation through a large-scale study with 6-8 year old children. Then, the generalizability of this approach is illustrated through its transfer to a cognitively heterogeneous children (i.e., special education), and its transfer to another learning domain (i.e., health education).S'appuyant sur le modèle des Progrès d'Apprentissage (PA, Oudeyer & Gotlieb, 2016), une approche STI basée sur les PA a été conçue et implémentée dans un jeu sérieux de numératie (addition et soustraction de nombres dans des activités d'échanges monétaires) appelé KidLearn. Dans ce contexte, le STI personnalise les parcours d'apprentissage en optimisant les PA (algorithmes de type bandit multi-bras), en minimisant les présupposés sur les apprenants et le domaine de connaissance. Dans un premier temps, l'approche STI adoptée est présentée, suivie de sa validation par une étude à grande échelle auprès d'enfants de 6 à 8 ans. Puis, la capacité de généralisation de cette approche est illustrée à travers son transfert à un public cognitivement hétérogène (i.e. éducation spécialisée), et son transfert à un autre domaine d'apprentissage (i.e., éducation thérapeutique)
Model order reduction methods for geometrically nonlinear structures: a review of nonlinear techniques
No full textInternational audienceThis paper aims at reviewing nonlinear methods for model order reduction of structures with geometric nonlinearity, with a special emphasis on the techniques based on invariant manifold theory. Nonlinear methods differ from linear-based techniques by their use of a nonlinear mapping instead of adding new vectors to enlarge the projection basis. Invariant manifolds have been first introduced in vibration theory within the context of nonlinear normal modes (NNMs) and have been initially computed from the modal basis, using either a graph representation or a normal form approach to compute mappings and reduced dynamics. These developments are first recalled following a historical perspective, where the main applications were first oriented toward structural models that can be expressed thanks to partial differential equations (PDE). They are then replaced in the more general context of the parametrisation of invariant manifold that allows unifying the approaches. Then the specific case of structures discretized with the finite element method is addressed. Implicit condensation, giving rise to a projection onto a stress manifold, and modal derivatives, used in the framework of the quadratic manifold, are first reviewed. Finally, recent developments allowing direct computation of reduced-order models (ROMs) relying on invariant manifolds theory are detailed. Applicative examples are shown and the extension of the methods to deal with further complications are reviewed. Finally, open problems and future directions are highlighted