University of Avignon

About: University of Avignon is a education organization based out in Avignon, Provence-Alpes-Côte-d'Azur, France. It is known for research contribution in the topics: Population & Speaker recognition. The organization has 1526 authors who have published 3766 publications receiving 88928 citations.

Cantor families of periodic solutions for completely resonant nonlinear wave equations

Abstract: We prove existence of small amplitude, $2\pi \slash \om$-periodic in time solutions of completely resonant nonlinear wave equations with Dirichlet boundary conditions, for any frequency $ \om $ belonging to a Cantor-like set of positive measure and for a new set of nonlinearities. The proof relies on a suitable Lyapunov-Schmidt decomposition and a variant of the Nash-Moser Implicit Function Theorem. In spite of the complete resonance of the equation we show that we can still reduce the problem to a {\it finite} dimensional bifurcation equation. Moreover, a new simple approach for the inversion of the linearized operators required by the Nash-Moser scheme is developed. It allows to deal also with nonlinearities which are not odd and with finite spatial regularity.

Leveraging Light Forest With Rateless Network Coding to Design Efficient All-Optical Multicast Schemes for Elastic Optical Networks

Abstract: In this paper, we study the multicast-capable routing, modulation, and spectrum assignment (MC-RMSA) schemes that consider the physical impairments from both the transmission and light splitting in elastic optical networks (EONs). Specifically, we propose to provision each multicast request with a light forest, which consists of one or more light trees to avoid the dilemma that because of the accumulated physical impairments, a relatively large light tree may have to use the lowest modulation level, and, hence, consume too many frequency slots (FS'). In order to further improve the spectral efficiency and compensate for the differential delays among the light trees, we incorporate the rateless network coding (R-NC) in the multicast system. We first formulate an integer linear programming (ILP) model to solve the problem for static network planning. Then, we propose three time-efficient heuristics that leverage the set-cover problem and utilize layered auxiliary graphs. The simulation results indicate that in both the ILP and heuristics, the MC-RMSA with R-NC can achieve better performance on the maximum index of used FS' than that without. After that we evaluate the heuristics in a dynamic network provisioning. The results show that the MC-RMSA with R-NC can effectively improve the performance of all-optical multicast in EONs to reduce the blocking probability.

Increased nitrogen availability in soil after repeated compost applications: Use of the PASTIS model to separate short and long-term effects

Abstract: Regular application of composts on cropped soils has been shown to restore soil organic matter contents. The effect of repeated applications of three urban composts on the nitrogen (N) dynamics in a cropped loamy soil was compared to farmyard manure application and a control receiving no amendment. Each amendment application brought on average 250-400 kg ha−1 of total N. After five applications, total organic N increased in amended soils from 9 to 27% compared to control and the increase of soil organic N corresponded to 32-79% of total N brought by the amendments. The PASTIS model was used to describe the N balance in the soil-plant system during the 2 years after a sixth amendment application and provided correct predictions of N dynamics in cropped plots. The N availability increased in all treatments receiving organic amendments. The N availability in the soils amended with urban composts or manure was predominantly driven by the biodegradability of the organic amendments, their mineral N content and by the cropping conditions. Composts with high biodegradability exhibited higher proportion of N recovery by plants (21% for the municipal solid waste compost) during the year following their application, while more stabilised composts (biowaste compost, co-compost of sludge and green wastes) increased the N availability mainly through the increase of soil organic N content and mineralisation after several compost applications (6-8% of the soil organic N increase). Mature composts behaved comparably to FYM, except that for FYM very little N from the last application was available. Regular compost applications equivalent to 200 kg N ha−1 every other year could increase N availability for crops of 50-70 kg N ha−1 over the 2 years of the crop rotation. However, the most stabilised composts led to a higher crop N recovery but also to potential higher amounts of leached N compared to less mature composts.

Decentralized Protection Strategies Against SIS Epidemics in Networks

Abstract: Defining an optimal protection strategy against viruses, spam propagation, or any other kind of contamination process is an important feature for designing new networks and architectures. In this paper, we consider decentralized optimal protection strategies when a virus is propagating over a network through an SIS epidemic process. We assume that each node in the network can fully protect itself from infection at a constant cost, or the node can use recovery software, once it is infected. We model our system using a game-theoretic framework and find pure, mixed equilibria, and the Price of Anarchy in several network topologies. Further, we propose a decentralized algorithm and an iterative procedure to compute a pure equilibrium in the general case of a multiple communities network. Finally, we evaluate the algorithms and give numerical illustrations of all our results.