ERP Characterization of Sustained Attention Effects in Visual Lexical Categorization

As our understanding of the basic processes underlying reading is growing, the key role played by attention in this process becomes evident. Two research topics are of particular interest in this domain: (1) it is still undetermined whether sustained attention affects lexical decision tasks; (2) the influence of attention on early visual processing (i.e., before orthographic or lexico-semantic processing stages) remains largely under-specified. Here we investigated early perceptual modulations by sustained attention using an ERP paradigm adapted from Thierry et al. [1]. Participants had to decide whether visual stimuli presented in pairs pertained to a pre-specified category (lexical categorization focus on word or pseudoword pairs). Depending on the lexical category of the first item of a pair, participants either needed to fully process the second item (hold condition) or could release their attention and make a decision without full processing of the second item (release condition). The P1 peak was unaffected by sustained attention. The N1 was delayed and reduced after the second item of a pair when participants released their attention. Release of sustained attention also reduced a P3 wave elicited by the first item of a pair and abolished the P3 wave elicited by the second. Our results are consistent with differential effects of sustained attention on early processing stages and working memory. Sustained attention modulated early processing stages during a lexical decision task without inhibiting the process of stimulus integration. On the contrary, working memory involvement/updating was highly dependent upon the allocation of sustained attention. Moreover, the influence of sustained attention on both early and late cognitive processes was independent of lexical categorization focus

Sémiotique et visualisation de l'identité numérique: une étude comparée de Facebook et Myspace

Digital identity is divided into 3 sign sets: (1) declarative identity, (2) acting identity and (3) calculated identity. This typology allows leading a quantitative analysis of cultural influence of identity representation in social web, through the comparative study of two social networks: Facebook and MySpace. Unlike early web, social web makes possible identification of a user without having to declare describing elements. The comparative analysis presented here continues this analysis by specifying the procedures of this new paradigm of identity and highlighting two different ideologies of identity, on the one hand, a normative one to stimulate socialization, on the other hand, an egocentric one for the sake of self-expression. “Calculated identity” encourages users to make comparisons between them and feed their representation, but increasing disproportionately the number of friends is not sufficient to play the social game as it is structured by Facebook: visualization shows that the social network is maintained by sharing. Sharing photos, participating in shared groups is a part of regular social interaction announcing the emergence of a new intersubjective language.Un modèle sémiotique de l'identité numérique construit précédemment distingue 3 ensembles de signes : l'identité déclarative, agissante et calculée. Ce modèle est utilisé pour développer une analyse quantitative appliquée de l'emprise culturelle du web 2.0 sur la représentation de l'identité à travers l'étude comparative de deux logiciels de réseaux sociaux, Facebook et Myspace. Contrairement au premier web, le web social rend possible l'identification personnelle d'un utilisateur sans qu'il ait à déclarer des éléments qui le décrivent ; l'analyse comparée ici présentée poursuit cette analyse en précisant les procédés de ce nouveau paradigme identitaire et mettant en évidence des idéologies identitaires différentes, l'une normative par souci de socialisation, l'autre égocentrée par souci d'expression de soi. L'identité calculée incite les utilisateurs à établir des comparaisons entre eux et à nourrir leur représentation, mais il ne s'agit pas pour autant de jouer à accroître démesurément un critère comme le nombre d'amis pour jouer le jeu social : les graphes nœud-lien montrent que le réseau s'entretient par le partage. Partager des photographies, participer à des groupes communs fait partie des échanges sociaux réguliers qui annoncent l'émergence d'un nouveau langage intersubjectif

Nonlinear Model Predictive Control of the Air Path of a Turbocharged Gasoline Engine Using Laguerre Functions

International audienceObjectives in terms of pollutant emissions and fuel consumption reduction have led car manufacturers to enhance the technical definitions of combustion engines. The latter should now be considered as multiple-input multiple-output nonlinear systems with saturated actuators. This considerably increases the challenge regarding the development of optimal control laws under the constraints of constant cost reductions in the automotive industry. In the present paper, the use of a nonlinear model predictive control (NMPC) scheme is studied for the air path control of a turbocharged gasoline engine. Specifically, a zero dimension physics-based model is combined with parameterization of the future control trajectory. The use of Laguerre polynomials is shown to increase flexibility for the future control trajectory at no cost in computational requirements. This increase in flexibility leads to an improvement of the transient response of the closed-loop with respect to traditional approaches. This practical application shows that this approach makes it easier to fine-tune the NMPC scheme when dealing with engine air path control

Explicit-Ready Nonlinear Model Predictive Control for Turbocharged Spark-Ignited Engine

International audienceThe trend to reduce the engine size in automotive industry is motivated by more restrictive pollutant emissions standards. That is why engine technical definitions have become more and more complicated. The control challenge has also grown since engines are now considered as highly nonlinear multi-input multi-output systems with saturated actuators. In this context, the need for model-based control laws is bigger than ever. In this study we propose a nonlinear model predictive control strategy based on a physical engine model. Moreover, we also underline the benefit of using a thermodynamic engine term in the objective function. Finally, the design and calibration choices consciously fulfill the criterions of the use of an explicit approach for the real time implementation

Nouvelle méthode de détermination de la distribution de la tailles des pores d’un milieu poreux par l’injection d’un fluide à seuil

La caractérisation des milieux poreux (M.P.) en termes de porosité, de surface spécifique, de distribution de tailles des pores etc. est un enjeu important pour de nombreuses filières industrielles : récupération assistée de pétrole, thermique du bâtiment, séquestration de CO2, stockage d'énergie ... Ainsi, les phénomènes de transports liés aux écouelments au sein des M.P. ont occupé et continuent à stimuler une forte activité de recherche aussi bien fondamentale qu'appliquée. Dans cette communication, nous présentons une méthode innovante qui s'appuie sur l'écoulement d'un fluide viscoplastique à seuil au travers d'un poreux permettant de scanner la distribution de taille de pores

Explicit Nonlinear Model Predictive Control of the Air Path of a Turbocharged Spark-Ignited Engine

International audiencePollutant emissions and fuel economy objectives have led car manufacturers to develop innovative and more sophisticated engine layouts. In order to reduce time-to-market and development costs, recent research has investigated the idea of a quasi-systematic engine control development approach. Model based approaches might not be the only possibility but they are clearly predetermined to considerably reduce test bench tuning work requirements. In this paper, we present the synthesis of a physics-based nonlinear model predictive control law especially designed for powertrain control. A binary search tree is used to ensure real-time implementation of the explicit form of the control law, computed by solving the associated multi-parametric nonlinear problem

On the Recent Use of Local Binary Patterns for Face Authentication

This paper presents a survey on the recent use of Local Binary Patterns (LBPs) for face recognition. LBP is becoming a popular technique for face representation. It is a non-parametric kernel which summarizes the local spacial structure of an image and it is invariant to monotonic gray-scale transformations. This is a very interesting property in face recognition. This probably explains the recent success of Local Binary Patterns in face recognition. In this paper, we describe the LBP technique and different approaches proposed in the literature to represent and to recognize faces. The most representatives are considered for experimental comparison on a common face authentication task. For that purpose, the XM2VTS and BANCA databases are used according to their respective experimental protocols

A methodology to study oil-coking problem in small turbochargers

[EN] In compliance with oncoming emission directives, turbocharging and increasing complexity in the turbocharger system demands a great effort from researchers on the development of effective procedures and tools to cope with the new technological exigencies. This article describes a methodology for studying oil-coking influence in turbocharger performance. A preliminary evaluation and calibration is done. The aim of this work focuses on the development of methodologies and tools that help to evaluate and understand the consequences that degraded oils can generate in the bearing system during enhanced oil-coking procedure. Several experimental tests have been carried out in an engine test bench and using an independent lubrication system that only feeds the turbocharger. The test campaign is done under a specific engine cycle and using oil artificially contaminated at two different levels. The work is divided into two parts. The first part provides a description and definition of test conditions for measuring of the maximum temperature in the bearing system and the second part tackles the measurement and post-processing of the main instantaneous parameters defining the engine and turbocharger behavior.The authors would like to acknowledge the Apoyo para la investigación y Desarrollo (PAID) grant for doctoral studies (FPI-2016-S2-1354). This work was partially supported by FEDER and the Spanish Ministry of Economy and Competitiveness through Grant Number TRA2016-79185-R.Serrano, J.; Tiseira, A.; García-Cuevas González, LM.; Rodriguez-Usaquen, YT.; Guillaume, M. (2020). A methodology to study oil-coking problem in small turbochargers. International Journal of Engine Research. 21(7):1193-1204. https://doi.org/10.1177/1468087418803197S11931204217Giakoumis, E. G. (2016). Review of Some Methods for Improving Transient Response in Automotive Diesel Engines through Various Turbocharging Configurations. Frontiers in Mechanical Engineering, 2. doi:10.3389/fmech.2016.00004Nguyen-Schäfer, H. (2012). Rotordynamics of Automotive Turbochargers. doi:10.1007/978-3-642-27518-0Brouwer, M. D., Sadeghi, F., Lancaster, C., Archer, J., & Donaldson, J. (2013). Whirl and Friction Characteristics of High Speed Floating Ring and Ball Bearing Turbochargers. Journal of Tribology, 135(4). doi:10.1115/1.4024780Addison J, Needelman W. Diesel engine lubricant contamination and wear. New York: Pall Corporation, 1986, p.12.Serrano, J. R., Olmeda, P., Tiseira, A., García-Cuevas, L. M., & Lefebvre, A. (2013). Theoretical and experimental study of mechanical losses in automotive turbochargers. Energy, 55, 888-898. doi:10.1016/j.energy.2013.04.042Galindo, J., Lujan, J. M., Guardiola, C., & Lapuente, G. S. (2006). A method for data consistency checking in compressor and variable-geometry turbine maps. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 220(10), 1465-1473. doi:10.1243/09544070jauto82Serrano, J. R., Arnau, F. J., Dolz, V., & Piqueras, P. (2009). Methodology for characterisation and simulation of turbocharged diesel engines combustion during transient operation. Part 1: Data acquisition and post-processing. Applied Thermal Engineering, 29(1), 142-149. doi:10.1016/j.applthermaleng.2008.02.011Ghazikhani, M., Davarpanah, M., & Shaegh, S. A. M. (2008). An experimental study on the effects of different opening ranges of waste-gate on the exhaust soot emission of a turbo-charged DI diesel engine. Energy Conversion and Management, 49(10), 2563-2569. doi:10.1016/j.enconman.2008.05.012Jun, H.-B., Kiritsis, D., Gambera, M., & Xirouchakis, P. (2006). Predictive algorithm to determine the suitable time to change automotive engine oil. Computers & Industrial Engineering, 51(4), 671-683. doi:10.1016/j.cie.2006.06.017Owrang, F., Mattsson, H., Olsson, J., & Pedersen, J. (2004). Investigation of oxidation of a mineral and a synthetic engine oil. Thermochimica Acta, 413(1-2), 241-248. doi:10.1016/j.tca.2003.09.016Serrano, J. R., Olmeda, P., Arnau, F. J., Reyes-Belmonte, M. A., & Tartoussi, H. (2015). A study on the internal convection in small turbochargers. Proposal of heat transfer convective coefficients. Applied Thermal Engineering, 89, 587-599. doi:10.1016/j.applthermaleng.2015.06.053Serrano, J. R., Olmeda, P., Arnau, F. J., Dombrovsky, A., & Smith, L. (2014). Analysis and Methodology to Characterize Heat Transfer Phenomena in Automotive Turbochargers. Journal of Engineering for Gas Turbines and Power, 137(2). doi:10.1115/1.402826

Elaboration and Optimization of Tellurite-based Materials for Raman Gain Application

L expansion de nouvelles technologies et la demande incessante d une transmission d informations plus rapide font que les systèmes de télécommunications nécessitent plus de débit sur de plus longues distances. L amplification optique et notamment l amplification optique par effet Raman représente une intéressante possibilité à repousser les limites de distance et de debit.Les verres à base d oxyde de tellure sont des matériaux prometteurs pour les applications d amplification optique par effet Raman; en particulier grâce à leurs fortes propriétés optiques linéaires et non linéaires, leurs fenêtres de transparence allant dans le proche et milieu infra-rouge du spectre de transmission. De plus, leurs propriétés thermiques et en particulier leurs faibles temperatures de transition vitreuse permettent une facilité de fibrage. L estimation de l intensité du gain Raman et sa zone spectrale mise en jeu sont généralement approchées à partir du spectre de diffusion Raman spontanée du matériaux. La compréhension des relations existantes entre la structure vitreuse, la réponse vibrationnelle et les propriétés d optique non linéaire, représente un point clé au développement et à l optimisation des verres de tellure pour l amplification Raman. Cette dissertation apporte une réponse détaillée à la question fondamentale de l étude doctorale: Quel est l impact de la structure vitreuse sur les propriétés d amplification Raman dans les verres d oxyde de tellure?Tellurite-based oxide glasses have been investigated as promising materials for Raman gain applications, due to their good linear and nonlinear optical properties and their wide transparency windows in the near- and midwave infrared spectral region. Furthermore, their interesting thermal properties, i.e. low glass transition temperature and ability to be drawn into optical fibers, make tellurite-based glasses excellent candidates for optical fiber amplifiers. The estimation of the strength and spectral distribution of Raman gain in materials is commonly approximated from the spontaneous Raman scattering cross-section measurement. For development of tellurite-based glasses as Raman amplifiers, understanding the relationship between glass structure, vibrational response, and nonlinear optical properties (NLO) represents a key point. This dissertation provides an answer to the fundamental question of the PhD study: What is the impact of the glass structure on Raman gain properties of tellurite glasses?BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF