ABSTRACT Torque balancing for DI engines aims at eliminating the vibration mode and decreasing th... more ABSTRACT Torque balancing for DI engines aims at eliminating the vibration mode and decreasing the level of emissions induced by disturbances such as variability in injectors efficiency, inertia and geometry between cylinders. The contribution of this article is to present a real-time experimental setup along with simulations and experimental results of estimation of the indicated torque of a DI engine. We build a time-varying linear model of the system and design a linear observer to estimate the indicated torque produced by each cylinder. This is achieved with the instantaneous engine speed as only measurement. This work can be used in a next step when unbalance could be corrected in an adaptive manner by controlling the mass injected into each cylinder.
HIV replication follows a well-defined pattern during the acute phase of the infection in humans.... more HIV replication follows a well-defined pattern during the acute phase of the infection in humans. After reaching a peak during the first few weeks after infection, viral replication resolves to a set-point thereafter. There are still uncertainties regarding the contribution of CD8+ T cells in establishing this set-point. An alternative explanation, supported by in silico modeling, would imply that viral replication is limited by the number of available targets for infection, i.e. CD4+CCR5+ T cells. Here, we used NOD.SCID.gc-/- mice bearing human CD4+CCR5+ and CD8+ T cells derived from CD34+ progenitors to investigate the relative contribution of both in viral control after the peak. Using low dose of a CCR5-tropic HIV virus, we observed an increase in viral replication followed by "spontaneous" resolution of the peak, similar to humans. To rule out any possible role for CD8+ T cells in viral control, we infected mice in which CD8+ T cells had been removed by a depleting an...
ABSTRACT We propose in this paper a method to estimate the velocity of a rigid body, using a nove... more ABSTRACT We propose in this paper a method to estimate the velocity of a rigid body, using a novel stereo-vision principle. It is presented and applied in a laboratory test case which is representative of low-cost navigation for ground vehicles. The method exploits the dynamics of a scalar field obtained by weighting and averaging the brightness perceived by two embedded neighboring cameras. To be more specific, the cameras are complemented with a gyrometer to retrieve the curvilinear velocity of the moving rigid body. The proposed method is first tested on synthetic data, then on real data, and shows robustness to poor quality of image data. Significant levels of noise and blur are tested; in addition, this method does not require high resolution images, as opposed to any existing methods based on triangulation and tracking of keypoints.
We investigate the boundary stabilization of a particular subset of 3× 3 linear hyperbolic system... more We investigate the boundary stabilization of a particular subset of 3× 3 linear hyperbolic systems with varying coefficients on a bounded domain. The system is underactuated since only one of the three hyperbolic PDEs is actuated at the boundary. The setup considered ...
ABSTRACT Torque balancing for DI engines aims at eliminating the vibration mode and decreasing th... more ABSTRACT Torque balancing for DI engines aims at eliminating the vibration mode and decreasing the level of emissions induced by disturbances such as variability in injectors efficiency, inertia and geometry between cylinders. The contribution of this article is to present a real-time experimental setup along with simulations and experimental results of estimation of the indicated torque of a DI engine. We build a time-varying linear model of the system and design a linear observer to estimate the indicated torque produced by each cylinder. This is achieved with the instantaneous engine speed as only measurement. This work can be used in a next step when unbalance could be corrected in an adaptive manner by controlling the mass injected into each cylinder.
HIV replication follows a well-defined pattern during the acute phase of the infection in humans.... more HIV replication follows a well-defined pattern during the acute phase of the infection in humans. After reaching a peak during the first few weeks after infection, viral replication resolves to a set-point thereafter. There are still uncertainties regarding the contribution of CD8+ T cells in establishing this set-point. An alternative explanation, supported by in silico modeling, would imply that viral replication is limited by the number of available targets for infection, i.e. CD4+CCR5+ T cells. Here, we used NOD.SCID.gc-/- mice bearing human CD4+CCR5+ and CD8+ T cells derived from CD34+ progenitors to investigate the relative contribution of both in viral control after the peak. Using low dose of a CCR5-tropic HIV virus, we observed an increase in viral replication followed by "spontaneous" resolution of the peak, similar to humans. To rule out any possible role for CD8+ T cells in viral control, we infected mice in which CD8+ T cells had been removed by a depleting an...
ABSTRACT We propose in this paper a method to estimate the velocity of a rigid body, using a nove... more ABSTRACT We propose in this paper a method to estimate the velocity of a rigid body, using a novel stereo-vision principle. It is presented and applied in a laboratory test case which is representative of low-cost navigation for ground vehicles. The method exploits the dynamics of a scalar field obtained by weighting and averaging the brightness perceived by two embedded neighboring cameras. To be more specific, the cameras are complemented with a gyrometer to retrieve the curvilinear velocity of the moving rigid body. The proposed method is first tested on synthetic data, then on real data, and shows robustness to poor quality of image data. Significant levels of noise and blur are tested; in addition, this method does not require high resolution images, as opposed to any existing methods based on triangulation and tracking of keypoints.
We investigate the boundary stabilization of a particular subset of 3× 3 linear hyperbolic system... more We investigate the boundary stabilization of a particular subset of 3× 3 linear hyperbolic systems with varying coefficients on a bounded domain. The system is underactuated since only one of the three hyperbolic PDEs is actuated at the boundary. The setup considered ...
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Papers by Nicolas Petit