Worker flows, job flows and establishment wage differentials : analyzing the case of France

We address the relation between establishment wage differentials and worker flows, i.e. the churning rate and the quit rate. Our analysis is based on a linked employer-employee dataset covering the French private non-farm sector from 2002 to 2005. Our estimations support the hypothesis that wage premium is an efficient human resource management tool to stabilize workers : churning rates are lower in high-paying firms due to lower quit rates. We further show that the relation is not linear, and it differs among skill groups and according to establishment size : it is strongest for low-wage levels, for low-skilled workers and in large establishments.Establishment wage effects, worker flows, churning rate, quite rate, linked employer-employee panel data, France.

I - Matter, antimatter and geometry II - The twin universe model : a solution to the problem of negative energy particles III - The twin universe model plus electric charges and matter-antimatter symmetry

We introduce a new dynamical group whose coadjoint action on its momentum space takes account of matter-antimatter symmetry on pure geometrical grounds. According to this description the energy and the spin are unchanged under matter-antimatter symmetry. We recall that the antichron components of the Poincar\'{e} group, ruling relativistic motions of a mass-point particle, generate negative energy particles. The model with two twin universes, inspired by Sakharov's one, solves the stability issue. Positive and negative energy particles motions hold in two distinct folds. The model is extended to charged particles. As a result, the matter-antimatter duality holds in both universes.Comment: 19 Fevrier 200

Modeling and control of a Diesel HCCI engine

International audienceThis article focuses on the control of a Diesel engine airpath. We propose a detailed description of the airpath of a Diesel HCCI engine supported by experimental results. Moreover, we propose a simple, yet innovative, motion planning control strategy. At the light of this study, we can finally conclude, with supportive results, that motion planning is indeed an appropriate solution for controlling the airpath dynamics

Motion planning control of the airpath of a S.I. engine with Valve Timing Actuators

International audienceWe address the control of the airpath of a turbocharged S.I. engine equipped with Variable Valve Timing actuators (VVT). Compared to standard configurations, the engine does not possess any external EGR (Exhaust Gas Recirculation) loop. Rather, VVT are used to produce internal EGR, providing similar beneficial effects in terms of emissions reduction. The airpath dynamics takes the form of a single mono-dimensional air balance in the intake manifold. In this equation, the VVT act as a disturbance by impacting on the air mass flow through the inlet valves. This impact can be estimated from real-time measurements. We use this information in a motion planning based control strategy by, successively, turning the driver's torque demand into a trajectory generation problem for the air mass contained in the intake manifold, and then deriving an intake manifold pressure trajectory. Supportive simulation results show the relevance of this approach and suggest ways of further improvements