1,880 research outputs found

    Formaliser la multiplicité des constructions sociales de la réalité par les systèmes multi-agents institutionnels

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    Les institutions et les normes ont été traités de différentes façons : dans nos travaux en modéli- sation des dynamiques sociales du point de vue de l'anthropologie du droit où une multiplicité d'interprétations légales des acteurs, des choses et des actes était nécessaire, en philosophie qui insiste sur le rôle des définitions dans les institutions à travers les normes constitutives, et dans le domaine des systèmes multi-agents pour spécifier les interactions entre agents à tra- vers une multiplicité de rôles. Nous proposons dans ce papier une synthèse permettant de trai- ter conjointement la multiplicité des interpréta- tions, des normes constitutives et des structures de rôles. Nous proposons également une spé- cification de systèmes multi-agents institution- nels spatialisés, montrant sa capacité à rendre compte syntaxiquement et sémantiquement de cette synthèse. En particulier, nous montrons comment cette multiplicité interprétative struc- ture l'espace en autant de territoire

    Assessment of the potential of MERIS near-infrared water vapour products to correct ASAR interferometric measurements

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    Atmospheric water vapour is a major limitation for high precision Interferometric Synthetic Aperture Radar (InSAR) applications due to its significant impact on microwave signals. We propose a statistical criterion to test whether an independent water vapour product can reduce water vapour effects on InSAR interferograms, and assess the potential of the Medium Resolution Imaging Spectrometer (MERIS) near-infrared water vapour products for correcting Advanced SAR (ASAR) data. Spatio-temporal comparisons show c. 1.1mm agreement between MERIS and GPS/radiosonde water vapour products in terms of standard deviations. One major limitation with the use of MERIS water vapour products is the frequency of cloud free conditions. Our analysis indicates that in spite of the low global cloud free conditions (~25%), the frequency can be much higher for certain areas such as Eastern Tibet (~38%) and Southern California (~48%). This suggests that MERIS water vapour products show potential for correcting ASAR interferometric measurements in certain regions

    A simple and quick sensitivity analysis method for methane isotopologues detection with GOSAT-TANSO-FTS

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    Measurements of methane isotopologues can differentiate between different source types, be they biogenic (e.g. marsh lands) or abiogenic (e.g. industry). Global measurements of these isotopologues would greatly benefit the current disconnect between ‘top-down’ (knowledge from chemistry transport models and satellite measurements) and ‘bottom-up’ (in situ measurement inventories) methane measurements. However, current measurements of these isotopologues are limited to a small number of in situ studies and airborne studies. In this paper we investigate the potential for detecting the second most common isotopologue of methane (13CH4) from space using the Japanese Greenhouse Gases Observing Satellite applying a quick and simple residual radiance analysis technique. The method allows for a rapid analysis of spectral regions, and can be used to teach university students or advanced school students about radiative transfer analysis. Using this method we find limited sensitivity to 13CH4, with detections limited to total column methane enhancements of >6%, assuming a desert surface albedo of >0.3

    Negative specific heat in a thermodynamic model of multifragmentation

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    We consider a soluble model of multifragmentation which is similar in spirit to many models which have been used to fit intermediate energy heavy ion collision data. In this model cvc_v is always positive but for finite nuclei cpc_p can be negative for some temperatures and pressures. Furthermore, negative values of cpc_p can be obtained in canonical treatment. One does not need to use the microcanonical ensemble. Negative values for cpc_p can persist for systems as large as 200 paticles but this depends upon parameters used in the model calculation. As expected, negative specific heats are absent in the thermodynamic limit.Comment: Revtex, 13 pages including 6 figure

    Photonic band structure of highly deformable, self-assembling systems

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    We calculate the photonic band structure at normal incidence of highly deformable, self-assembling systems - cholesteric elastomers subjected to external stress. Cholesterics display brilliant reflection and lasing owing to gaps in their photonic band structure. The band structure of cholesteric elastomers varies sensitively with strain, showing new gaps opening up and shifting in frequency. A novel prediction of a total band gap is made, and is expected to occur in the vicinity of the previously observed de Vries bandgap, which is only for one polarisation

    Model of multifragmentation, Equation of State and phase transition

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    We consider a soluble model of multifragmentation which is similar in spirit to many models which have been used to fit intermediate energy heavy ion collision data. We draw a p-V diagram for the model and compare with a p-V diagram obtained from a mean-field theory. We investigate the question of chemical instability in the multifragmentation model. Phase transitions in the model are discussed.Comment: Revtex, 9 pages including 6 figures: some change in the text and Fig.
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