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First principles fluid modelling of magnetic island stabilization by ECCD
No full textInternational audienceTearing modes are MHD instabilities that reduce the performances of fusion devices. They can however be controlled and suppressed using Electron Cyclotron Current Drive (ECCD) as demonstrated in various tokamaks. In this work, simulations of islands stabilization by ECCD-driven current have been carried out using the toroidal nonlinear 3D full MHD code XTOR-2F, in which a current-source term modeling the ECCD has been implemented. The efficiency parameter is computed and its variations with respect to source width and location are computed. The influence of parameters such as current intensity, source width and position with respect to the island is evaluated and compared to the Modified Rutherford Equation. We retrieve a good agreement between the simulations and the analytical predictions concerning the variations of control efficiency with source width and position. We also show that the 3D nature of the current source term can lead to the onset of an island if the source term is precisely applied on a rational surface. We report the observation of a flip phenomenon in which the O-and X-Points of the island rapidly switch their position in order for the island to take advantage of the current drive to grow
Hadron shower decomposition in the highly granular CALICE analogue hadron calorimeter
No full text38 pages, 19 figures, 5 tables, to be submitted to JINSTInternational audienceThe spatial development of hadronic showers in the CALICE scintillator-steel analogue hadron calorimeter is studied using test beam data collected at CERN and FNAL for single positive pions and protons with initial momenta in the range from 10 to 80 GeV/c. Both longitudinal and radial development of hadron showers are parametrised with two-component functions. The parametrisation is fit to test beam data and simulations using the QGSP_BERT and FTFP_BERT physics lists from Geant4 version 9.6. The parameters extracted from data and simulated samples are compared for the two types of hadrons. The response to pions and the ratio of the non-electromagnetic to the electromagnetic calorimeter response, h/e, are estimated using the extrapolation and decomposition of the longitudinal profiles
CSR related management practices and Firm Performance: An Empirical Analysis of the quantity-quality trade-off on French data
No full textFait aussi partie de la "Série Scientifique - Scientific Series" des CIRANO Working Papers, n°2014s-34. Le fichier joint correspond à cette version.International audienceThis paper analyzes how different combinations of Corporate Social Responsibility (CSR) dimensions affect corporate economic performance. We use various dimensions of CSR to examine whether firms rely on different combinations of CSR, in terms of quality versus quantity of CSR practices. Our empirical analysis based on an original database including 10,293 French firms shows that different CSR dimensions in isolation impact positively firms’ profits but their effect in term on intensity varies among CSR dimensions. Moreover, the findings on the qualitative CSR measure, based on interaction between its dimensions, show that the substitutability of these dimensions is highly significant for firm performance. However, in terms of the intensity, those interactions produce differential effects. Actually, asking whether a firm starting with a certain configuration cannot perform better by adding or removing some dimension(s) we found that only one configuration fulfills this requirement: green and HR. The interpretation is that when a firm starts with this configuration then it is better not to move to another configuration. In all other configurations, firms can always improve their profits either by adding or removing some dimensions. Finally, the profitability of CSR investments in French firms seems to rely on a specific qualitative mix of different CSR dimensions rather than a pure quantitative approach accumulating practices without designing a consistent set of interactions among them
Search for R-parity violating decays of a top squark in proton-proton collisions at sqrt(s) = 8 TeV
No full textSubmitted to Phys. Lett. B ; see paper for full list of authorsInternational audienceThe results of a search for a supersymmetric partner of the top quark (top squark), pair-produced in proton-proton collisions at sqrt(s) = 8 TeV, are presented. The search, which focuses on R-parity violating, chargino-mediated decays of the top squark, is performed in final states with low missing transverse momentum, two oppositely charged electrons or muons, and at least five jets. The analysis uses a data sample corresponding to an integrated luminosity of 19.7 inverse femtobarns collected with the CMS detector at the LHC in 2012. The data are found to be in agreement with the standard model expectation, and upper limits are placed on the top squark pair production cross section at 95% confidence level. Assuming a 100% branching fraction for the top squark decay chain, top squark to t + chargino, chargino to lepton + jj, top squark masses less than 890 (1000) GeV for the electron (muon) channel are excluded for the first time in models with a single nonzero R-parity violating coupling lambda'[ijk] (i,j,k <= 2), where i,j,k correspond to the three generations
Thioxanthene and dioxothioxanthene dihydroindeno[2,1-b]fluorenes: synthesis, properties and applications in green and sky blue phosphorescent OLEDs
No full textInternational audienceWe report herein the synthesis, and structural, electrochem. and photophys. properties of new dihydroindeno[2,1-b]fluorene-based semi-conductors, i.e. dispiro[thioxanthene-9,5'-indeno[2,1-b]fluorene-7',9''-thioxanthene] 2 and dispiro-[dioxothioxanthene-9,5'-indeno[2,1-b]fluorene-7',9''-thioxanthene] 3. These properties will be compared to those of the pure hydrocarbon deriv. dispiro[fluorene-9,5'-indeno[2,1-b]fluorene-7',9''-fluorene] 1 previously described. The incorporation of the sulfur atom within the bridged units allows tuning the HOMO and LUMO energy levels, nevertheless retaining the high ET of the dihydroindeno[2,1-b]fluorenyl core ([2,1-b]IF), the key feature of further device applications. This control of the properties has allowed incorporating 3 as the host material in blue and green phosphorescent OLEDs (PhOLEDs) with an EQE of 12.8% (at 1 mA cm-2 with the corresponding CE and PE of 48.6 cd A-1 and 29.5 lm W-1) for the green device and an EQE of 4.8% (at 1 mA cm-2 with the corresponding CE and PE of 14.8 cd A-1 and 8.2 lm W-1) for the sky-blue device. To the best of our knowledge, this work is the second example of incorporation of a dihydroindeno[2,1-b]fluorene based semi-conductor in a blue PhOLED and highlights the potential of this fragment in org. electronics
First results of the CALICE SDHCAL technological prototype
No full textsee paper for full list of authorsInternational audienceThe CALICE Semi-Digital Hadronic Calorimeter (SDHCAL) prototype, built in 2011, was exposed to beams of hadrons, electrons and muons in two short periods in 2012 on two different beam lines of the CERN SPS. The prototype with its 48 active layers, made of Glass Resistive Plate Chambers and their embedded readout electronics, was run in triggerless and power-pulsing mode. The performance of the SDHCAL during the test beam was found to be very satisfactory with an efficiency exceeding 90% for almost all of the 48 active layers. A linear response (within 5%) and a good energy resolution are obtained for a large range of hadronic energies (5-80GeV) by applying appropriate calibration coefficients to the collected data for both the Digital (Binary) and the Semi-Digital (Multi-threshold) modes of the SDHCAL prototype. The Semi-Digital mode shows better performance at energies exceeding 30Ge
A transmission electron microscopy study of radiation damages to β-dicalcium (Ca2SiO4) and M3-tricalcium (Ca3SiO5) orthosilicates
No full textInternational audienceIn this paper, we present results of a first study of electron radiation damages to β-dicalcium silicate (Ca2SiO4:C2S) and M3-tricalcium silicate (Ca3SiO5:C3S) in a Transmission Electron Microscope. Electron irradiation is used here as a means to bring to light a difference of reactivity under the electron beam between these two complex ceramic oxides, keeping in mind that C3S reacts faster with water than C2S and that this property remains unexplained, owing to the complex structural characteristics of these ceramics which have not yet been fully elucidated.The following results were obtained by coupling TEM imaging and EDS analysis: i) Rapid decomposition of both silicate particles into CaO nano-crystals separated by (presumably SiO2-rich) amorphous areas at low flux for both silicates; ii) once reached a threshold electron flux, formation of an amorphous crater in both silicates, fully calcium-depleted in C3S but never in C2S; iii) significant post-mortem structural evolution of the craters that at least partially recrystallize in C2S, to be compared to the quasi frozen damaged area in C3S; iv) hole drilling at high flux but only in C3S once reached a threshold flux, ϕth ∼ 7.9 × 1021 e− cm−2 s−1, of the same order of magnitude than previously estimated in a number of ceramic materials, whereas C2S still amorphizes under the electron beam for a flux as high as 2.2 × 1022 e− cm−2 s−1.The radiation damages and their post–mortem evolution differ largely between C2S and C3S. We attempted to relate the obtained results, and especially the evolution of the Ca content in the damaged areas under the electron beam to the available structural characteristics of these two orthosilicates
Exercice de style
No full textWe present the construction and implementation of an 8-bit S-box with a differential and linear branch number of 3. We show an application by designing FLY, a simple block cipher based on bitsliced evaluations of the S-box and bit rotations that targets the same platforms as PRIDE, and which can be seen as a variant of PRESENT with 8-bit S-boxes. It achieves the same performance as PRIDE on 8-bit microcontrollers (in terms of number of instructions per round) while having 1.5 times more equivalent active S-boxes. The S-box also has an efficient implementation with SIMD instructions, a low implementation cost in hardware and it can be masked efficiently thanks to its sparing use of non-linear gates.Cette note présente la construction et l'implémentation d'une boîte S sur 8 bits qui a un branchement linéaire et différentiel de 3.Nous montrons une application en construisant un chiffre par bloc sur 64 bits dont la structure est très simple et est basée sur l'évaluationen tranches (bitsliced) de la boîte S et des rotations sur mots de 8 bits et qui peut être vu comme une variante de PRESENT avec une boîte S de 8 bits. La fonction de tour de ce chiffre peut s'implémenter avec le même nombred'instructions que celle de PRIDE sur micro-controleurs 8-bits, tout en ayant 1,5 fois plus de boîtes S actives (relativement).Cette boîte S peut aussi s'implémenter efficacement avec des instructions SIMD, a un coût faible en matériel etpeut se masquer efficacement grâce au peu de portes non-linéaires nécessaires
Scaling of precipitation extremes with temperature in the French Mediterranean region: What explains the hook shape?
No full textInternational audienceExpected changes to future extreme precipitation remain a key uncertainty associated with anthropogenic climate change. Extreme precipitation has been proposed to scale with the precipitable water content in the atmosphere. Assuming constant relative humidity, this implies an increase of precipitation extremes at a rate of about 7% °C−1 globally as indicated by the Clausius-Clapeyron relationship. Increases faster and slower than Clausius-Clapeyron have also been reported. In this work, we examine the scaling between precipitation extremes and temperature in the present climate using simulations and measurements from surface weather stations collected in the frame of the HyMeX and MED-CORDEX programs in Southern France. Of particular interest are departures from the Clausius-Clapeyron thermodynamic expectation, their spatial and temporal distribution, and their origin. Looking at the scaling of precipitation extreme with temperature, two regimes emerge which form a hook shape: one at low temperatures (cooler than around 15°C) with rates of increase close to the Clausius-Clapeyron rate and one at high temperatures (warmer than about 15°C) with sub-Clausius-Clapeyron rates and most often negative rates. On average, the region of focus does not seem to exhibit super Clausius-Clapeyron behavior except at some stations, in contrast to earlier studies. Many factors can contribute to departure from Clausius-Clapeyron scaling: time and spatial averaging, choice of scaling temperature (surface versus condensation level), and precipitation efficiency and vertical velocity in updrafts that are not necessarily constant with temperature. But most importantly, the dynamical contribution of orography to precipitation in the fall over this area during the so-called “Cevenoles” events, explains the hook shape of the scaling of precipitation extremes
Dirichlet-to-Neumann operator for diffraction problems in stratified anisotropic acoustic waveguides
No full textInternational audienceThe purpose of this note is to construct a Dirichlet-to-Neumann operator for the diffraction problem in stratified anisotropic acoustic waveguides. The key idea consists in using an adapted change of coordinates that enables to recover the completeness and the orthogonality of the modes on " deformed " cross-sections of the waveguide. To cite this article