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Search Results: 1 - 10 of 6127 matches for " Stéphane Dufau "
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Deep Learning of Orthographic Representations in Baboons
Thomas Hannagan, Johannes C. Ziegler, Stéphane Dufau, Jo?l Fagot, Jonathan Grainger
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0084843
Abstract: What is the origin of our ability to learn orthographic knowledge? We use deep convolutional networks to emulate the primate's ventral visual stream and explore the recent finding that baboons can be trained to discriminate English words from nonwords [1]. The networks were exposed to the exact same sequence of stimuli and reinforcement signals as the baboons in the experiment, and learned to map real visual inputs (pixels) of letter strings onto binary word/nonword responses. We show that the networks' highest levels of representations were indeed sensitive to letter combinations as postulated in our previous research. The model also captured the key empirical findings, such as generalization to novel words, along with some intriguing inter-individual differences. The present work shows the merits of deep learning networks that can simulate the whole processing chain all the way from the visual input to the response while allowing researchers to analyze the complex representations that emerge during the learning process.
Pricing and Hedging in Stochastic Volatility Regime Switching Models  [PDF]
Stéphane Goutte
Journal of Mathematical Finance (JMF) , 2013, DOI: 10.4236/jmf.2013.31006

We consider general regime switching stochastic volatility models where both the asset and the volatility dynamics depend on the values of a Markov jump process. Due to the stochastic volatility and the Markov regime switching, this financial market is thus incomplete and perfect pricing and hedging of options are not possible. Thus, we are interested in finding formulae to solve the problem of pricing and hedging options in this framework. For this, we use the local risk minimization approach to obtain pricing and hedging formulae based on solving a system of partial differential equations. Then we get also formulae to price volatility and variance swap options on these general regime switching stochastic volatility models.


Analysis of Relationships between Port Activity and Other Sectors of the Economy: Evidence from Cote d’Ivoire  [PDF]
Nomel Paul Stéphane Essoh
American Journal of Industrial and Business Management (AJIBM) , 2013, DOI: 10.4236/ajibm.2013.33042

This research paper aims to study the correlation between the port activity and the activity of the different services sectors. By comparing trends between them and analyzing the causality relationships between the port traffic and the other economic sectors, our study tends to present how the activity of the port of Abidjan could have a decisive effect on the local economy. To meet our objectives, correlation analysis and statistical test tools Eviews and other techniques have been run with data provided by local agencies and port authority. By doing so, our research study finds that there is existing correlation between port activity and activity generated by the other services sectors and its contribution can accelerate the economic growth.

Cote d’Ivoire’s Commodities Export and Shipping: Challenges for Port Traffic and Regional Market Size  [PDF]
Nomel P. Stéphane Essoh
American Journal of Industrial and Business Management (AJIBM) , 2014, DOI: 10.4236/ajibm.2014.45031

The global integration with the growth of the world population generated a constant need of goods where trade took place with both inputs and ready-made products. Although this global need has led to a diversification of exports of goods, it still requires special commodities from tropical Africa and trade partners in West Africa that may supply more their specialized products which can be moved in cargo between destinations. This paper identifies especially Cote d’Ivoire’s commodities export and shipping market structure with its main agricultural products which makes him the world’s dominant producer and exporter of cocoa beans. It develops the importance of export crops structure for local economy driven by the international demand for cocoa beans. And it finally could indicate in our future study whether the possibility of pricing power and export taxes affecting the shipping market has a decisive impact on the port traffic and accelerates growth.

An Aspect-Oriented Approach for Use Case Based Modeling of Software Product Lines  [PDF]
Stéphane S. SOMé, Pauline ANTHONYSAMY
Journal of Software Engineering and Applications (JSEA) , 2009, DOI: 10.4236/jsea.2009.24032
Abstract: Software Product Line Development advocates software reuse by modeling common and variable artefacts separately across members of a family of products. Aspect-Oriented Software Development aims at separation of concerns with “aspects” to increase modularity, reusability, maintainability and ease of evolution. In this paper, we apply an as-pect-oriented use case modeling approach to product line system modeling. A use case specification captures stake-holders concerns as interactions between a system and its actors. We adapt our previous work with the introduction of a “variability” relationship for the expression of variabilities. This relationship is used to model variable and common behaviours across a family of products as use cases. A variability composition mechanism enables building of executa-ble behaviour models for each member of a product line family by integrating common elements with the applicable variable elements.
Three Patterns of Motion Which Change the Perception of Emotional Faces  [PDF]
Alhadi Chafi, Loris Schiaratura, Stéphane Rusinek
Psychology (PSYCH) , 2012, DOI: 10.4236/psych.2012.31014
Abstract: The aim of the study was to focus on the relationship between motion and emotion. Relying on studies in Behavioral Neurology and Social Psychology, it is believed motion is one of the core components of Emotion. The study uses basic emotional faces (i.e., Happy, Surprised, Fearful, Sad, Disgusted and Angry) which are presented displaying patterns of motion (i.e., a Parabolic motion, a Translational motion and a Wave-like motion). Hypotheses are that the wave-like motion will increase perceived intensities and arou- sal related to positive emotional faces (i.e., Happy and Surprised), and simplify their recognition. Otherwise, the parabolic motion is hypothesized to increase perceived intensities and arousal related to negative emotional faces (i.e., Angry, Disgusted, Fearful and Sad), while enhancing their recognition. Results sho- wed that “Happy” is the most recognized face and “Fearful” is the least recognized one. Concerning Perceived Intensity, an Emotional Face main effect and an Interaction Motion Pattern × Emotional Face were obtained. Finally, the Arousal dimension yielded two main effects, one for the Emotional Face and one for the Motion Pattern. On one hand, results we found are very promising in understanding the part played by motion in Arousal. On the other hand, further research still has to be done so as to question the exact effects of the Translational, Parabolic and Wave-like motion patterns, especially in more dynamic contexts.
A Process Study of the Tidal Circulation in the Persian Gulf  [PDF]
Stéphane Pous, Xavier Carton, Pascal Lazure
Open Journal of Marine Science (OJMS) , 2012, DOI: 10.4236/ojms.2012.24016
Abstract: A homogeneous shallow-water model with free surface is used to model the tidal circulation in the Persian Gulf. The numerical finite-difference model includes harmonic diffusion of horizontal momentum and quadratic bottom friction, it has a 9 km mesh size and it is forced by 7 tidal components at its southern boundary. High precision bathymetric data are used to obtain the bottom topography. The numerical model is run for more than a year. The results are the following: 1) The model accurately reproduces the tidal phase and amplitude observed at 42 tidal gauges in the region. This accuracy is attributed to the presence of the 7 components which are able to interact nonlinearly; 2) The amphidromic points are also well positioned by the model due to a proper choice of bathymetry. This was checked also with a simpler geometry of the domain; 3) The tidal currents can be strong in the Straits of Hormuz and in shallow areas; thus they will have an effect of the hydrology of the region. The residual currents are weak so that they will be negligible for the large-scale circulation on long periods; 4) Finally, the sea-surface elevation forecast by the model is in close agreement with in-situ measurements of pressure in the Straits, performed during the GOGP99 experiment.
A Process Study of the Wind-Induced Circulation in the Persian Gulf  [PDF]
Stéphane Pous, Xavier Carton, Pascal Lazure
Open Journal of Marine Science (OJMS) , 2013, DOI: 10.4236/ojms.2013.31001

A shallow-water model, coupled with a three dimensional, hydrostatic ocean model, is used to study the wind induced circulation, and the Shatt-al-Arab river plume expansion, in the Persian Gulf. The models are used in an idealized configuration. The following results are obtained: 1) with northwesterly winds, a double gyre is formed: this gyre is cyclonic in the south and anticyclonic in the north. Southeastward currents flow along the Iranian and Arabian coast where the wind stress at the surface dominates the pressure gradient related to the free surface slope, and conversely in the deeper region of the Gulf; 2) In the eastern part of the Gulf, the cyclonic gyre intensifies, as observed and reported in the literature; 3) For northwesterly winds, the plume from Shatt-al-Arab first heads towards the Iranian coast and then spreads southeastward along the Arabian coast; for northerly and northeasterly winds, the plume directly follows the Kuwaiti coast and then the Arabian coast. This sensitivity of the orientation can be related to the double gyre flow structure; 4) A southeasterly wind confines the plume in the northern end of the Gulf as does a pure tidal flow.

Control of the Atomic Ionization with Short and Intense Chirped Laser Pulses  [PDF]
Samira Barmaki, Salima Hennani, Stéphane Laulan
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.410A1003

We investigate a two-photon ionization process in a real hydrogen atom by short and intense chirped laser pulses. Our simulation of the laser-atom interaction consists on numerically solving the three-dimensional time-dependent Schrodinger equation with a spectral method. The unperturbed wave functions and electronic energies of the atomic system were found by using an accurate L2 discretisation technique based on the expansion of the wave functions on B-spline functions. We show the efficiency of chirped laser pulses to control the ionization yield and the transfer of the population to the 2p bound state involved in the ionization path.

Unsteady Cavitation Analysis Using Phase Averaging and Conditional Approaches in a 2D Venturi Flow  [PDF]
Vincent Aeschlimann, Stéphane Barre, Henda Djeridi
Open Journal of Fluid Dynamics (OJFD) , 2013, DOI: 10.4236/ojfd.2013.33022

The present study refers to a cavitating Venturi type section geometry characterized by a convergent angle of 18° and a divergent angle of about 8° where the sheet cavity presents typical self-oscillation behavior with quasi-periodic vapor clouds shedding. This work is an extension of previous works concerning void ratio measurements and velocity fields using double optical probe and constitutes a complete analysis of the two-phase structure of unsteady cavitating flow. This paper provides a new method based on conditional and phase averaging technique with wall pressure signal to treat experimental data in order to evaluate more precisely time-averaged and rms values of the void ratio and instantaneous velocity fields. Conditional analysis shows a different behavior of the two-phase flow dynamics leading to highlight high void ratio events linked to the break-off cycle. Unsteady phase averaging of the optical probe signal gives the evolution of the void ratio at each studied location in the venturi and shows that the fluctuations close to the wall (where the re-entrant jet is predominant) are in phase with the upper part of the cavity instead of the thickness of the cavity which is unchanged.

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