Benefits of Waveform Relaxation Method and Output Space Mapping for the Optimization of Multirate Systems

We present an optimization problem that requires to model a multirate system, composed of subsystems with different time constants. We use waveform relaxation method in order to simulate such a system. But computation time can be penalizing in an optimization context. Thus we apply output space mapping which uses several models of the system to accelerate optimization. Waveform relaxation method is one of the models used in output space mapping

La poésie pense : une modalité assomptive de la connaissance

La poésie pense : une modalité assomptive de la connaissance — Dans un monde utilitariste dominé par la technologie, la poésie ne correspond pas forcément aux idées qu'on a sur elle. Exploration du monde et de la vie, elle est comme la science au coeur de la connaissance, repoussant elle aussi les limites de l'inconnu et de l’impensé. Elle est encore la conscience critique du rapport nécessairement subjectif à la connaissance. C'est par son caractère « épiphanique » que la poésie se distingue du discours scientifique. Au savoir-vrai argumenté du discours de la science, elle oppose la modalité assomptive, immédiate, de la saisie du monde.Thinking Poetry : an Assumptive Approach to Knowledge — In our technology-dominated utilitarian world, poetry does not necessarily correspond to our definitions and ideas of it. An exploration of the world and of life, it is like the science at the heart of knowledge, pushing back the boundaries of the unknown and the unthought. The critical conscience in our inescapably subjective relationship to knowledge, its "epiphanic" character is that which sets it apart from scientific discourse. Poetry opposes science's fact-based discourse on knowledge with the world's necessarily assumptive and judgmental approach to it

The Suborbital Particle Aggregation and Collision Experiment (SPACE): Studying the Collision Behavior of Submillimeter-Sized Dust Aggregates on the Suborbital Rocket Flight REXUS 12

The Suborbital Particle Aggregation and Collision Experiment (SPACE) is a novel approach to study the collision properties of submillimeter-sized, highly porous dust aggregates. The experiment was designed, built and carried out to increase our knowledge about the processes dominating the first phase of planet formation. During this phase, the growth of planetary precursors occurs by agglomeration of micrometer-sized dust grains into aggregates of at least millimeters to centimeters in size. However, the formation of larger bodies from the so-formed building blocks is not yet fully understood. Recent numerical models on dust growth lack a particular support by experimental studies in the size range of submillimeters, because these particles are predicted to collide at very gentle relative velocities of below 1 cm/s that can only be achieved in a reduced-gravity environment. The SPACE experiment investigates the collision behavior of an ensemble of silicate-dust aggregates inside several evacuated glass containers which are being agitated by a shaker to induce the desired collisions at chosen velocities. The dust aggregates are being observed by a high-speed camera, allowing for the determination of the collision properties of the protoplanetary dust analog material. The data obtained from the suborbital flight with the REXUS (Rocket Experiments for University Students) 12 rocket will be directly implemented into a state-of-the-art dust growth and collision model