Learning to automatically detect features for mobile robots using second-order Hidden Markov Models

In this paper, we propose a new method based on Hidden Markov Models to interpret temporal sequences of sensor data from mobile robots to automatically detect features. Hidden Markov Models have been used for a long time in pattern recognition, especially in speech recognition. Their main advantages over other methods (such as neural networks) are their ability to model noisy temporal signals of variable length. We show in this paper that this approach is well suited for interpretation of temporal sequences of mobile-robot sensor data. We present two distinct experiments and results: the first one in an indoor environment where a mobile robot learns to detect features like open doors or T-intersections, the second one in an outdoor environment where a different mobile robot has to identify situations like climbing a hill or crossing a rock.Comment: 200

Formal and Informal Methods for Multi-Core Design Space Exploration

We propose a tool-supported methodology for design-space exploration for embedded systems. It provides means to define high-level models of applications and multi-processor architectures and evaluate the performance of different deployment (mapping, scheduling) strategies while taking uncertainty into account. We argue that this extension of the scope of formal verification is important for the viability of the domain.Comment: In Proceedings QAPL 2014, arXiv:1406.156

A limitation of the hydrostatic reconstruction technique for Shallow Water equations

Because of their capability to preserve steady-states, well-balanced schemes for Shallow Water equations are becoming popular. Among them, the hydrostatic reconstruction proposed in Audusse et al. (2004), coupled with a positive numerical flux, allows to verify important mathematical and physical properties like the positivity of the water height and, thus, to avoid unstabilities when dealing with dry zones. In this note, we prove that this method exhibits an abnormal behavior for some combinations of slope, mesh size and water height.Comment: 7 page

Job Creation, Job Destruction and the Life Cycle

This paper originally incorporates life-cycle features into the job creation - job destruction framework. Once a finite horizon is introduced, this workhorse labor market model naturally delivers the empirically uncontroversial prediction that the employment rate of workers decreases with age due to lower hirings and higher firings of older workers. This age profile of hirings and firings is in addition found to be optimal in a competitive search equilibrium context. If search externalities are not internalized and unemployment benefits distort equilibrium, there is a room for labor market policy differentiated by age. This lastly allows us to debate the incidence of labor demand policies which have been introduced in many countries to favor the older worker employment. We show that hiring subsidies and firing costs should be decreasing with age when unemployment benefits are sufficiently high, as in the Europe. On the contrary, if unemployment benefits are low, as in the US, optimal hiring subsidies and firing taxes should be increasing with age. In this latter case, the introduction of anti-discrimination laws is a good proxy of this first best policy.Job creations and destructions, Life cycle, Older workers

Recent progress in inverse methods in France

Given the current level of jet engine performance, improvement of the various turbomachinery components requires the use of advanced methods in aerodynamics, heat transfer, and aeromechanics. In particular, successful blade design can only be achieved via numerical design methods which make it possible to reach optimized solutions in a much shorter time than ever before. Two design methods which are currently being used throughout the French turbomachinery industry to obtain optimized blade geometries are presented. Examples are presented for compressor and turbine applications. The status of these methods as far as improvement and extension to new fields of applications is also reported