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Le Touquet – Paris-Plage, France

Goyat Y.,LCPC | Chateau T.,University Blaise Pascal | Bardet F.,University Blaise Pascal
Eurasip Journal on Advances in Signal Processing | Year: 2010

This paper presents an algorithm for modeling and tracking vehicles in video sequences within one integrated framework. Most of the solutions are based on sequential methods that make inference according to current information. In contrast, we propose a deferred logical inference method that makes a decision according to a sequence of observations, thus processing a spatio-temporal search on the whole trajectory. One of the drawbacks of deferred logical inference methods is that the solution space of hypotheses grows exponentially related to the depth of observation. Our approach takes into account both the kinematic model of the vehicle and a driver behavior model in order to reduce the space of the solutions. The resulting proposed state model explains the trajectory with only 11 parameters. The solution space is then sampled with a Markov Chain Monte Carlo (MCMC) that uses a model-driven proposal distribution in order to control random walk behavior. We demonstrate our method on real video sequences from which we have ground truth provided by a RTK GPS (Real-Time Kinematic GPS). Experimental results show that the proposed algorithm outperforms a sequential inference solution (particle filter). © 2010 Yann Goyat et al.

Habert G.,University Paris Est Creteil | Bouzidi Y.,French National Center for Scientific Research | Chen C.,University Paris Est Creteil | Jullien A.,LCPC
Resources, Conservation and Recycling | Year: 2010

The objective of this study is to propose a reliable and clear indicator that could assess the present state of depletion of local bulk resources in different regions. The article argues that indicators commonly used to assess resource consumption in the Life Cycle Impact Assessment (LCIA) are not fully adapted to the particular sector of concrete industry. Most impact assessment methods assume that at a global world wide scale, the stock for bulk resources, such as the sand and gravel used for concrete manufacture is so important that it could be considered as unlimited. This is true on global scale, but not on a regional scale. Here we assume that the regional scale is a pertinent scale upon which to base resource extraction policies, as concrete and its constituents are not transported over long distances. Therefore we propose a new method to calculate resource consumption impacts that uses a new assessment of the stock of resources. The potential accessible resource stock within one territory is calculated rather than the ultimate global resource availability. This potential stock is evaluated by the study of the temporal evolution of importation over consumption ratio for a given specific material. Some results for United States of America and for France are presented. It is shown that the impact on resource consumption for concretes made with aggregates coming from different places is significantly different using the new indicator. It was not possible to highlight this with previous LCIA indicators. Finally the limit of this indicator application is discussed. © 2009 Elsevier B.V. All rights reserved.

Drissi-Habti M.,LCPC
Advances in FRP Composites in Civil Engineering - Proceedings of the 5th International Conference on FRP Composites in Civil Engineering, CICE 2010 | Year: 2011

The goal of this contribution is to share some ideas that can bring heavier discussion among the population of bridge researchers and engineers about SHM. For existing infrastructures, an emphasis will be made on how critical the detection of the onset of corrosion as well as its rate of proliferation within steels. In the case of new bridges, design and conception should include smart materials and structures. Smart composites, that are integrating embedded sensors, can bring significant advances in civil engineering applications. So is the case of nano-sensors, that will surely offer additional valuable solutions in the mid-term future. The issues related to standards in using composites in civil engineering are also addressed. © Tsinghua University Press, Beijing and Springer-Verlag Berlin Heidelberg 2011.

Noel M.-H.,French National Center for Scientific Research | Van Damme H.,LCPC | Hebraud P.,French National Center for Scientific Research
Cement and Concrete Research | Year: 2011

A thermoresponsive copolymer solution is used to control the mechanical properties of a cement paste suspension. We use a comb copolymer consisting of a polymethacrylic acid (PMAA) backbone grafted with a polypropylene oxide (PPO) and polyethylene oxide (PEO) copolymer that possesses a low critical solution temperature (LCST). When the temperature crosses the LCST value, microphase separation occurs and the adsorption of the copolymer onto the cement particles is modified. We show that a control of the grafting ratio and of the graft chain composition allows monitoring of the transition temperature as well as the viscosity of the paste in the low and high temperature phases. © 2011 Elsevier Ltd.

Goyat Y.,LCPC | Chateau T.,LASMEA | Trassoudaine L.,LASMEA
Machine Vision and Applications | Year: 2010

This article presents a probabilistic method for vehicle tracking using a sensor composed of both a camera and a laser rangefinder. Two main contributions will be set forth in this paper. The first involves the definition of an original likelihood function based on the projection of simplified 3D vehicle models. We will also propose an efficient approach to compute this function using a line-based integral image. The second contribution focuses on a sampling algorithm designed to handle several sources. The resulting modified particle filter is capable of naturally merging several observation functions in a straightforwardmanner.Many trajectories of a vehicle equipped with a kinematic GPS 1 have been measured on actual field sites, with a video system specially developed for the project. This field input has made it possible to experimentally validate the result obtained from the algorithm. The ultimate goal of this research is to derive a better understanding of driver behavior in order to assist road managers in their effort to ensure network safety. © Springer-Verlag 2008.

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