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Radical Instability in Aid of Efficiency: A Powerful Route to Highly Functional MIDA Boronates
No full textInternational audienceThe inability of the sp(3) boron in MIDA boronates to stabilize an adjacent radical makes possible the efficient addition of a wide array Of xanthates to vinyl MIDA boronate, leading to highly functionalized and diverse aliphatic organoboron structures. The lack of radical Stabilization also allows the exchange Of the Xanthate in the adducts with a bromine. In one case, the bromine was substituted to generate a cyclopropyl MIDA derivative
Front-end electronics and data acquisition system for imaging atmospheric Cherenkov telescopes
No full textInternational audienceIn this paper, a front-end electronics based on an application-specific integrated circuit (ASIC) is presented for the future imaging atmospheric Cherenkov telescopes (IACTs). To achieve this purpose, a 16-channel ASIC chip, PARISROC 2 (Photomultiplier ARray Integrated in SiGe ReadOut Chip) is used in the analog signal processing and digitization. The digitized results are sent to the server by a user-defined User Datagram Protocol/Internet Protocol (UDP/IP) hardcore engine through Ethernet that is managed by a FPGA. A prototype electronics fulfilling the requirements of the Wide Field of View Cherenkov Telescope Array (WFCTA) of the Large High Altitude Air Shower Observatory (LHAASO) project has been designed, fabricated and tested to prove the concept of the design. A detailed description of the development with the results of the test measurements are presented. By using a new input structure and a new configuration of the ASIC, the dynamic range of the circuit is extended. A highly precise-time calibrating algorithm is also proposed, verified and optimized for the mass production. The test results suggest that the proposed electronics design fulfills the general specification of the future IACTs
Ambition numérique: Pour une politique française et européenne de la transition numérique
No full textRapport remis au premier ministr
Abstract Economies with Endogenous Sharing Rules
No full textURL des Documents de travail : http://centredeconomiesorbonne.univ-paris1.fr/documents-de-travail/Documents de travail du Centre d'Economie de la Sorbonne 2015.58 - ISSN : 1955-611XEndogenous sharing rules was introduced by Simon and Zame to model payoff indeterminacy in discontinuous games. Their main result concerns the existence of a solution, i.e., a mixed Nash equilibrium and an associated sharing rule. This note extends their result to abstract economies where, by definition, players are restricted to pure strategies, and provide an interpretation of Simon and Zame's model in terms of preference incompleteness.La notion de règle de partage endogène (« Endogenous sharing rules ») a été introduite par Simon et Zame (Econometrica 1990) afin de modéliser la possible indétermination des paiements dans les jeux stratégiques discontinus. Leur résultat principal est l'existence d'une solution, c'est à dire qu'un équilibre de Nash mixte et d'une règle de partage associée. Dans cette note, l'on étend leur résultat au cas d'une économie abstraite, où, par définition, les joueurs doivent choisir des stratégies pures, et l'on fournit une interprétation du modèle Simon et Zame en terme de préférences incomplètes
Response analysis of a laminar premixed M-flame to flow perturbations using a linearized compressible Navier-Stokes solver
No full textInternational audienceThe response of a laminar premixed methane-air flame subjected to flow perturbations around a steady state is examined experimentally and using a linearized compressible Navier-Stokes solver with a one-step chemistry mechanism to describe combustion. The unperturbed flame takes an M-shape stabilized both by a central bluff body and by the external rim of a cylindrical nozzle. This base flow is computed by a nonlinear direct simulation of the steady reacting flow, and the flame topology is shown to qualitatively correspond to experiments conducted under comparable conditions. The flame is then subjected to acoustic disturbances produced at different locations in the numerical domain, and its response is examined using the linearized solver. This linear numerical model then allows the componentwise investigation of the effects of flow disturbances on unsteady combustion and the feedback from the flame on the unsteady flow field. It is shown that a wrinkled reaction layer produces hydrodynamic disturbances in the fresh reactant flow field that superimpose on the acoustic field. This phenomenon, observed in several experiments, is fully interpreted here. The additional perturbations convected by the mean flow stem from the feedback of the perturbed flame sheet dynamics onto the flow field by a mechanism similar to that of a perturbed vortex sheet. The different regimes where this mechanism prevails are investigated by examining the phase and group velocities of flow disturbances along an axis oriented along the main direction of the flow in the fresh reactant flow field. It is shown that this mechanism dominates the low-frequency response of the wrinkled shape taken by the flame and, in particular, that it fully determines the dynamics of the flame tip from where the bulk of noise is radiated
A decomposition approach for the discrete-time approximation of FBSDEs with a jump
No full text31 pagesInternational audienceWe are concerned with the discretization of a solution of a Forward-Backward stochastic differential equation (FBSDE) with a jump process depending on the Brownian motion. In this paper, we study the cases of Lipschitz generators and the generators with a quadratic growth w.r.t. the variable z. We propose a recursive scheme based on a general existence result given in the companion paper [15] and we study the error induced by the time discretization. We prove the convergence of the scheme when the number of time steps n goes to infinity. Our approach allows to get a convergence rate similar to that of schemes of Brownian FBSDEs. Keywords: discrete-time approximation, forward-backward SDE, Lipschitz generator, generator of quadratic growth, progressive enlargement of filtrations, decomposition in the reference filtration. MSC classification (2010): 65C99, 60J75, 60G57
A numerical strategy to discretize and solve the Poisson equation on dynamically adapted multiresolution grids for time-dependent streamer discharge simulations
No full textInternational audienceWe develop a numerical strategy to solve multi-dimensional Poisson equations on dynamically adapted grids for evolutionary problems disclosing propagating fronts. The method is an extension of the multiresolution finite volume scheme used to solve hyperbolic and parabolic time-dependent PDEs. Such an approach guarantees a numerical solution of the Poisson equation within a user-defined accuracy tolerance. Most adaptive meshing approaches in the literature solve elliptic PDEs level-wise and hence at uniform resolution throughout the set of adapted grids. Here we introduce a numerical procedure to represent the elliptic operators on the adapted grid, strongly coupling inter grid relations that guarantee the conservation and accuracy properties of multiresolution finite volume schemes. The discrete Poisson equation is solved at once over the entire computational domain as a completely separate process. The accuracy and numerical performance of the method is assessed in the context of streamer discharge simulations
A New Method to Evaluate Simulation Models: The Calibration Profile (CP) Algorithm A New Method to Evaluate Simulation Models: The Calibration Profile (CP) Algorithm
No full textInternational audienceModels of social systems generally contain free parameters that can-not be evaluated directly from data. A calibration phase is therefore necessary to assess the capacity of the model to produce the expected dynamics. However, despite the high computational cost of this calibra-tion it doesn't produce a global picture of the relationship between the parameter space and the behaviour space of the model. The Calibration Profile (CP) algorithm is an innovative method extending the concept of automated calibration processes. It computes a profile that depicts the effect of each single parameter on the model behaviour, independently from the others. A 2-dimensional graph is thus produced exposing the impact of the parameter under study on the capacity of the model to pro-duce expected dynamics. The first part of this paper is devoted to the formal description of the CP algorithm. In the second part,we apply it to an agent based geographical model (SimpopLocal). The analysis of the results brings to light novel insights on the model
ortho-, meta-, and para-Dihydroindenofluorene Derivatives as Host Materials for Phosphorescent OLEDs.
No full textInternational audienceThis work reports the first structure-properties relationship study of ortho [2,1-c]-, meta [1,2-a]-, and para [1,2-b]dihydroindenofluorenes, highlighting the influence of bridge rigidification on the electronic properties. This study has made it possible to devise an extended π-conjugated molecule with both a high triplet state energy level and excellent thermal and morphological stability. As a proof of concept, dihydroindenofluorenes were used as the host in sky-blue phosphorescent organic light-emitting diodes (PhOLEDs) with high performance
ANTITRUST VERSUS INDUSTRIAL POLICIES, ENTRY AND WELFARE
No full textIn industries with large sunk costs, the investment strategy of competing firms depends on the regulatory context. We consider ex-ante industrial policies in which the sunk cost may be either taxed or subsidized, and antitrust policies which could be either pro-competitive (leading to divestiture in case of high ex-post protability) or lenient (allowing mergers in case of low ex-post protability). Through a simple entry game we completely characterize the impact of these policies and examine their associated dynamic trade-offs between the timing of the investment, the ex-post benefits for the consumers, and the possible duplication of fixed costs. We find that merger policies are dominated by ex-ante industrial policies, whereas the latter are dominated by divestiture policies only under very special circumstances