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Véronique Poirel - 27/09/2018

Ludovick Gagnon, the Sphinx team's new recruit

There has been a new addition to the Sphinx team since 1st September, all the way from Quebec. Meeting with Ludovick Gagnon, 31, Inria researcher.

After finishing his secondary education, Ludovick (with a 'k' - his mother's whim, he tells me) continued his studies in Quebec (bachelor and master degree in mathematics). During his bachelor degree, he obtained a grant to carry out research. He was particularly interested in passing from physics to mathematics and from theory to applications, which is why he quite naturally moved towards control theory, which offers both possibilities. This research theme is particularly developed in France, and it was during a conference in Bilbao in 2011 that he had his first decisive encounter: Jean-Michel Coron, member of the French Académie des sciences and winner of the Maxwell prize. Coron suggested that Ludovick first study his master's in Paris, then his PhD alongside him. It's all good! Ludovick then did his post-doctorate degree in Nice, under the supervision of Gilles Lebeau, member of the French University Institute (IUF) and also member of the French Académie des Sciences. Once again, it's all good! And, at the beginning of 2017, a second decisive encounter with Thomas Chambrion, during a conference in Brazil, who encouraged him to contact Takéo Takahashi, head of the Sphinx team. Once again, it's all good!

What does your research work consist of?

The Sphinx team works on partial differential equations, control theory, inverse problems and numerical analysis. For my part, I work more specifically on control theory.Can you elaborate?It is the study of the evolution of a system's state (temperature of a room, shape of a wave in a canal) as a function of a force (our control - for example, air conditioning or a wave generator). On a mathematical level, we focus on seeing which states are accessible depending on the type of control selected. This theory has numerous applications. Two are of particular interest to me, due to the presence of a non-linear stable state, the soliton:

Cleaning a town's canals. Canals are often polluted and the current cleaning method consists in emptying the canal, cleaning it, and then filling it up again. The idea I am looking to develop is to create solitons in the canal so that the current they create displaces the pollutants towards a water treatment plant. The advantage of this method is that it appears to be energy-efficient. If that works, then collaborations will be possible with municipalities or companies responsible for carrying out pumping.

Solitons are also used for optical fibers in bit transmission, as the impulse sent is in the form of a soliton. The stability of the solitons enables information to be sent over several thousand kilometers. However, when disturbances on the line are too strong, the soliton can be altered and bits - and therefore information - are lost. Several techniques are used to amplify the signal along the optical fiber in order to prevent this bit loss. Rather than amplifying the signal along the line, I am trying to find a way of taking long range action by means of the source in order to maintain the soliton's shape.

Ludovick has other passions outside his professional activities. When he was young he played ice hockey - like any self-respecting Quebecker - but also enjoyed snowboarding and mountain hiking. However he is also interested in the theater and, more specifically, improvisation - an activity he discovered two years ago.

And in answer to the question: "if you were a famous character, who would you be...?" There is a mathematician who has always fascinated me, and many others: Paul Erdos. He is admired by many for his scientific contribution but I think that what inspires me the most is his nomadic lifestyle.

Welcome to Inria, Ludovick!