Search results for "Simulation."
showing 10 items of 4779 documents
Nonlinear Sculpturing of Optical Pulses in Fibre Systems
2019
The interplay among the effects of dispersion, nonlinearity and gain/loss in optical fibre systems can be efficiently used to shape the pulses and manipulate and control the light dynamics and, hence, lead to different pulse-shaping regimes [1,2]. However, achieving a precise waveform with various prescribed characteristics is a complex issue that requires careful choice of the initial pulse conditions and system parameters. The general problem of optimisation towards a target operational regime in a complex multi-parameter space can be intelligently addressed by implementing machine-learning strategies. In this paper, we discuss a novel approach to the characterisation and optimisation of …
Optical bullets and "rockets" in nonlinear dissipative systems and their transformations and interactions
2006
We demonstrate the existence of stable optical light bullets in nonlinear dissipative media for both cases of normal and anomalous chromatic dispersion. The prediction is based on direct numerical simulations of the (3+1)-dimensional complex cubic-quintic GinzburgLandau equation. We do not impose conditions of spherical or cylindrical symmetry. Regions of existence of stable bullets are determined in the parameter space. Beyond the domain of parameters where stable bullets are found, unstable bullets can be transformed into >rockets> i.e. bullets elongated in the temporal domain. A few examples of the interaction between two optical bullets are considered using spatial and temporal interact…
Design rules for nonlinear spectral compression in optical fibers
2016
International audience; We present comprehensive design rules to optimize the process of spectral compression arising from nonlinear pulse propagation in an optical fiber. Extensive numerical simulations are used to predict the performance characteristics of the process as well as to identify the optimal operational conditions within the space of system parameters. It is shown that the group-velocity dispersion of the fiber is not detrimental and, in fact, helps achieve optimum compression. We also demonstrate that near-transform-limited rectangular and parabolic pulses can be generated in the region of optimum compression.
Rational solutions to the mKdV equation associated to particular polynomials
2021
International audience; Rational solutions to the modified Korteweg-de Vries (mKdV) equation are given in terms of a quotient of determinants involving certain particular polynomials. This gives a very efficient method to construct solutions. We construct very easily explicit expressions of these rational solutions for the first orders n = 1 until 10.
Expanding genetic graphs' potential to analyse ecological connectivity: assessment of graphs construction methods
2019
International audience; Dispersal movements are often constrained in human-shaped landscapes, thereby threatening species survival. Landscape genetics approaches are commonly used to analyse ecological connectivity because genetic data well reflect dispersal capacities. When species occupy discrete habitat patches, graph-theoretic methods are a particularly relevant approach to study dispersal-driven gene flow. The links of a genetic graph can be weighted using different genetic distances between populations (nodes). Similarly, graph pruning (link set selection) can rely on different criteria. However, despite growing interest in genetic graphs, the influence of these parameters remains mos…
Quand et comment utiliser les graphes génétiques pour analyser la connectivité écologique dans des paysages hétérogènes ?
2019
National audience; Lorsque les espèces occupent des taches d’habitat au sein de paysages hétérogènes, la connectivité écologique est influencée par la topologie du réseau de populations qu’elles forment. Dans ce contexte, les méthodes basées sur les graphes génétiques permettent i) de révéler cette topologie en identifiant les chemins de dispersion directs et ii) de quantifier la résistance des éléments paysagers à la dispersion. Compte-tenu de l’intérêt croissant pour ces méthodes en génétique du paysage, il est nécessaire de mieux comprendre quand et comment il faut utiliser les graphes génétiques. Pour cela, nous avons simulé le flux génétique entre 50 populations dans différents paysage…
Calcul des contributions des incertitudes dans un modèle complexe de qualité de l'eau
2010
The quantification of uncertainty in integrated urban drainage water quality models is of paramount interest. Indeed, the assessment of the reliability of the model results for complex water quality models is useful for understanding the significance of the results. However, the state of knowledge regarding uncertainties in urban drainage models is poor. In the case of integrated urban drainage water quality models, due to the fact that integrated approaches are basically a cascade of sub-models (simulating sewer system, wastewater treatment plant and receiving water body), the uncertainty produced in one sub-model propagates to the following ones depending on the model structure, the estim…
Effets des émissions anthropiques de gaz à effet de serre sur le climat du bassin de l'océan Indien
2005
La simulation numérique du climat par le modèle couplé de circulation générale ARPEGE-OPA est utilisée ici pour prédire les effets d'un doublement du CO2 atmosphérique en l'an 2100 sur le climat du bassin de l'Océan Indien. Les températures de surface de la mer, les précipitations et les champs moyens de vents à 850 et 200 hPa sont étudiés au pas de temps trimestriel, sur les deux normales climatiques 1968-1997 et 2070-2099. Pour la fin du XX° siècle, le modèle a tendance à surestimer légèrement les TSM et plus fortement les précipitations, résultat d'un cycle hydrologique simulé trop développé. L'extraction d'indices pluviométriques calculés sur des régions homogènes montre que les télécon…
Towards human exploration of space: the THESEUS review series on cardiovascular, respiratory, and renal research priorities
2016
International audience; The THESEUS project (Towards Human Exploration of Space: aEUropean Strategy) was initiated within the seventh FrameworkProgramme by the European Commission. This project aimed toprovide a cross-cutting, life science-based roadmap for Europe’sstrategy towards human exploration of space, especially for deepspace missions and its relevance to applications on Earth. Toaddress these challenges, relevance of space research on thecardiovascular system, the lungs and kidneys, was discussed in anexpert group and its principal conclusions will be presented in thisarticle.
Straw mulch as a sustainable solution to decrease runoff and erosion in glyphosate-treated clementine plantations in Eastern Spain. An assessment usi…
2019
[EN] In many Mediterranean areas, citrus orchards exhibit high soil loss rates because of the expansion of drip irrigation that allows cultivation on sloping terrain and the widespread use of glyphosate. To mitigate these non-sustainable soil losses, straw mulch could be applied as an efficient solution but this has been poorly studied. Therefore, the main goal of this paper was to assess the use of straw mulch as a tool to reduce soil losses in clementine plantations, which can be considered representative of a typical Mediterranean citrus orchard. A total of 40 rainfall simulation experiments were carried out on 20 pairs of neighbouring bare and mulched plots. Each experiment involved app…