High-Speed Rail Versus Air Transportation: Case Study of Madrid–Barcelona, Spain.

Travel time savings, better quality of the supplied services, greater comfort for the users, and improved accessibility are the main factors of success of High Speed Rail(HSR)links. This paper presents the results from a revealed and stated preference survey conducted to both HSR and air transport users in the Madrid Barcelona corridor. The data gathered from the stated preference survey was used to calibrate a modal choice model aiming at explaining competition between HSR and air transportation in the corridor. From the model, the authors obtain that prices and service frequency are the most important variables to compete with the other mode. In addition, they found that check-in and security controls at the airport are a crucial variable for the users in their modal choice. Other policies, such as the improvement of parking facilities at the train stations, play a secondary role

Integration constraint in diffuse element method

International audienceThe “patch test” verifies whether a linear solution is reproduced exactly in an elasticity problem. This approach to test the numerical formulation and the code itself is standard in the finite element method.The MLS shape functions do not have a polynomial form. Therefore, the integration is not well performed by the classical Gauss–Legendre scheme and the patch test is only satisfied asymptotically at convergence. In this paper, we propose a custom quadrature scheme for MLS shape functions in order to ensure the properties needed for an exact verification of the patch test

Protonic defects and water incorporation in Si and Ge-based apatite ionic conductors

Apatite-type oxide-ion conductors have attracted considerable interest as potential fuel cell electrolytes. Atomistic modelling techniques have been used to investigate oxygen interstitial sites, protonic defects and water incorporation in three silicate and three germanate-based apatite-systems, namely La8Ba2(SiO4)(6)O-2, La-9.33(SiO4)(6)O-2, La-9.67(SiO4)(6)O-2.5, La8Ba2(GeO4)(6)O-2, La-9.33(GeO4)(6)O-2, and La-9.67(GeO4)(6)O-2.5. The simulation models reproduce the complex experimental structures for all of these systems. The interstitial defect simulations have examined the lowest energy configuration and confirm this site to be near the Si/GeO4 tetrahedra. The water incorporation calculations identify the O-H protonic site to be along the O-4 oxygen channel as seen in naturally occurring hydroxy-apatites. The results also show more favourable and exothermic water incorporation energies for the germanate based apatites. This is consistent with recent experimental work, which shows that Ge-apatites take up water more readily than the silicate analogues