PHD Defense - Samuel Hidalgo - 07/12/2022 - Studies of active systems for robotic exploration, wave manipulation, and control of liquids in the Leidenfrost state

Samuel Hidalgo’s PhD Defense will take place on:
December 7th at 2pm
IPGG amphitheater
6 Rue Jean Calvin, 75005 Paris

Studies of active systems for robotic exploration, wave manipulation, and control of liquids in the Leidenfrost state

Self-propelled physical systems, also called active systems, have a rich phenomenology with multiple application domains. They are natural or artificial systems consisting of one or more individuals that convert an internal or external energy source to move. In this work, we study some applications of three active systems that we can control at will. First, we study the dynamics of a robot that randomly explores a region of arbitrary shape. Thanks to the use of a new theorem, we demonstrate that it is able to measure the area and perimeter of any region. Then, we develop a strategy to recognize shapes previously saved in a dictionary. In the second part, we study another experimental system made of magnets levitating on a cushion of air and repelling each other. This magnetic network behaves like an elastic medium in which mechanical waves can propagate. We demonstrate that a propagating wave can be time-reversed by applying a violent change in the damping of the medium. The successive application of damping shocks allows us to selectively absorb
monochromatic components of a wave with a broadband spectrum. Finally, we are interested in the control of liquids in the Leidenfrost state. We introduce a new stabilization mechanism based on a partial draining of the vapor layer supporting the liquid to prevent the Rayleigh-Taylor instability. Finally, we show that a local control of the vapor evacuation direction is able to propel liquids and, thus, to build a new generation of hydrodynamic engines.