Publications

2017

• Optimization and simulation for robust railway rolling-stock planning
  
  • Tréfond Sabine
  • Billionnet Alain
  • Elloumi Sourour
  • Djellab H.
  • Guyon Olivier
  Journal of Rail Transport Planning & Management, 2017. In this paper, we focus on the problem of robust rolling-stock planning for French passenger trains. First, we characterize robustness and define some indicators for the evaluation of rolling-stock rosters. We take a particular interest in homogenizing turning-times in a roster in order to absorb potential delays. Then, we propose a new approach to solve the problem of robust rolling-stock planning. The SNCF reference tool (PRESTO) calculates a solution to the rolling-stock planning problem. It consists of a multi-step approach to cover demand while minimizing operating costs, and to further add maintenance slots to the roster. We propose an integrated ILP model to add robustness to a roster while maintaining low operating costs compared to PRESTO. We have carried out tests on nine real French regional transport instances, and we use a simulation module to evaluate the results. We observe a significant improvement in robustness indicators while maintaining low operating costs and meeting maintenance requirements. (10.1016/j.jrtpm.2017.02.001)
  DOI : 10.1016/j.jrtpm.2017.02.001
• A two-way model for nonlinear acoustic waves in a non-uniform lattice of Helmholtz resonators
  
  • Mercier Jean-François
  • Lombard Bruno
  Wave Motion, Elsevier, 2017, 72, pp.260-275. Propagation of high amplitude acoustic pulses is studied in a 1D waveguide connected to a lattice of Helmholtz resonators. An homogenized model has been proposed by Sugimoto (J. Fluid. Mech., \textbf{244} (1992)), taking into account both the nonlinear wave propagation and various mechanisms of dissipation. This model is extended here to take into account two important features: resonators of different strengths and back-scattering effects. An energy balance is obtained, and a numerical method is developed. A closer agreement is reached between numerical and experimental results. Numerical experiments are also proposed to highlight the effect of defects and of disorder. (10.1016/j.wavemoti.2017.04.004)
  DOI : 10.1016/j.wavemoti.2017.04.004