El precio de la gasolina en España: distribución con restricciones verticales

[ES] Hemos realizado un análisis estructural del mercado de la gasolina en España para conocer la manera en la que se establecen los precios de la gasolina en comparación con los de la Unión Europea. Para ello analizamos la cadena de valor de las empresas más destacadas del mercado, así como las distintas barreras de entrada que limitan la competencia. Por último, destacamos las restricciones verticales que estas imponen a sus distribuidores minorista y su incidencia en el precio final del producto.

Vertical Differentiation and Entry Deterrence: A Reconsideration

In this work we emphasize why market coverage should be considered endogenous for a correct analysis of entry deterrence in vertical differentiation models and discuss the implications of this endogeneity for that analysis. We consider contexts without quality costs and also contexts with convex fixed quality costs.

A rational fraction polynomials model to study vertical dynamic wheel-rail interaction

This paper presents a model designed to study vertical interactions between wheel and rail when the wheel moves over a rail welding. The model focuses on the spatial domain, and is drawn up in a simple fashion from track receptances. The paper obtains the receptances from a full track model in the frequency domain already developed by the authors, which includes deformation of the rail section and propagation of bending, elongation and torsional waves along an infinite track. Transformation between domains was secured by applying a modified rational fraction polynomials method. This obtains a track model with very few degrees of freedom, and thus with minimum time consumption for integration, with a good match to the original model over a sufficiently broad range of frequencies. Wheel-rail interaction is modelled on a non-linear Hertzian spring, and consideration is given to parametric excitation caused by the wheel moving over a sleeper, since this is a moving wheel model and not a moving irregularity model. The model is used to study the dynamic loads and displacements emerging at the wheel-rail contact passing over a welding defect at different speeds.