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transformerXL_PPO_JAX
No full textThis repository provides a JAX implementation of TranformerXL with PPO in a RL setup following : "Stabilizing Transformers for Reinforcement Learning" from Parisotto et al. (https://arxiv.org/abs/1910.06764).The code uses the PureJaxRL template for PPO and copied some of the code from Huggingface transformerXL transferring it to JAX. We also took inspiration from the pytorch code in https://github.com/MarcoMeter/episodic-transformer-memory-ppo, which has some simplification of gradient propagation and positional encoding compared to transformerXL as it is described in the original paper (https://arxiv.org/abs/1901.02860).The training handles Gymnax environment.We also tested it on Craftax, on which it beat the baseline presented in the paper (https://arxiv.org/abs/2402.16801) including PPO-RNN, training with unsupervised environment design and intrinsic motivation. Notably we reach the 3rd level (the sewer) and obtain several advanced advancements, which was not achieved by the methods presented in the paper. See Craftax Results for more informations.The training of a 5M transformer on craftax for 1e9 steps (with 1024 environments) takes about 6h30 on a single A100
AIoT Guidebook: Comprehensive tutorial for developingIoT and AI applications on STM32 microcontrollers
No full textAuthors of papers retain copyright and release the work under a GNU General Public License v3.0The goal of this tutorial is to design various Internet of Things (IoT) applications throughexperimentation, creation, and validation of functional projects. By combining technologicalinsights with practical, hands-on project-based learning, you will gain a comprehensive understandingof the components that make up a connected system, ranging from sensor selectionto data processing in cloud and Artificial Intelligence (AI)
Whispering Gallery Modes and Frequency Combs: Two excursions in the world of photonic resonators
No full textInternational audienceIn photonics, resonators are versatile elements designed with the aim of guiding light. They encompass various orders of magnitude for theirsizes and the power of their laser sources. Accordingly some effects can be considered as negligible, leading to simplified mathematical models. We will focus on two such models: one related to Whispering Gallery Mode resonators and the other to ring/Fabry-Perot resonators. In the first case the retained model leads to a two-dimensional linear Helmholtz equation in the whole space with material laws having a jump along a bounded interface. The set of complex resonances is analyzed close to the real axis, corresponding to modes concentrated close to the interface. In the second case a one-dimensional model with cubic nonlinearity based on the LugiatoLefever equation is considered. Branches of stationary solutions issued from flat solutions are highlighted, providing frequency comb solutions
A DEEP SEGMENTATION APPROACH FOR MULTIBEAM ECHO SOUNDER BACKSCATTER DATA BASED ON SEAFLOOR TYPE
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Co-Contraction Embodies Uncertainty: An Optimal Feedforward Strategy for Robust Motor Control
No full textInternational audienceDespite our environment is often uncertain, we generally manage to generate stable motor behaviors. While reactive control plays a major role in this achievement, proactive control is critical to cope with the substantial noise and delays that affect neuromusculoskeletal systems. In particular, muscle co-contraction is exploited to robustify feedforward motor commands against internal sensorimotor noise as was revealed by stochastic optimal open-loop control modeling. Here, we extend this framework to neuromusculoskeletal systems subjected to random disturbances originating from the environment. The analytical derivation and numerical simulations predict a singular relationship between the degree of uncertainty in the task at hand and the optimal level of anticipatory co-contraction. This prediction is confirmed through a single-joint pointing task experiment where an external torque is applied to the wrist near the end of the reaching movement with varying probabilities across blocks of trials. We conclude that uncertainty calls for impedance control via proactive muscle co-contraction to stabilize behaviors when reactive control is insufficient for task success
Total synthesis of photoactivatable latrunculin B for actin-targeting chemical biology
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Far-field sound field estimation using robotized measurements and the boundary elements method
No full textInternational audienceSound Field Estimation (SFE) is a numerical technique widely used to identify and reconstruct theacoustic fields radiated by unknown structures. In particular, SFE proves to be useful when datais only available close to the source, but information in the whole space is required. However, thepractical implementation of this method is still hindered by two major drawbacks: the lack ofefficient implementation of existing numerical methodologies, and the time-consuming and tediousroll-out of acoustic measurements. This paper aims to provide a solution to both issues. First, themeasurements step is fully automated by using a robotic arm, able to accurately gather geometricand acoustic data without any human assistance. In this matter, a particular attention has beenpaid to the impact of the robot on the acoustic pressure measurements. The sound field predictionis then tackled using the Boundary Element Method (BEM), and implemented using the FreeFEM++BEM library. Numerically simulated measurements have allowed us to assess the method accuracy,and the overall solution has been successfully tested using actual robotized measurements of anunknown loudspeake
Optimal computation of integrals in the Half-Space Matching method for modal simulation of SHM/NDE in 3D elastic plate
No full textInternational audienceSimulating structural health monitoring (SHM) or nondestructive evaluation (NDE) methods based on elastic guided waves (GW) is very helpful to handle their complexity (co-existence of several GW modes, frequency dependence of wavespeed) and to further design optimal methods of inspection offering high sensitivity to the sought flaws. The half-space matching (HSM) method has been established for the development of a model that hybridizes local finite element (FE) computations for GW scattering by a flaw, with a modal semi-analytical model for GW radiation and propagation in flawless plate-like structures. Highly oscillatory Integral formulae appear in the HSM method that radiate the scattered field away from theFE zone as the superimposition of modal contributions, which computation can be time-consuming. The present work is concerned with their optimal computation. Integral of this form can be efficiently computed under the far-field approximation but this classical technique fails at predicting accurately wavefields at relatively short distances (small number of wavelengths). The method developed herein relies on the complexification of the integrals to be computed and on specific deformation of integration paths in the complex plane, as detailed in the paper. It allows the evaluation of the integrals without approximation other than that of numerical quadratures, ensuring high accuracy while offering high computing performances. It indifferently applies in the far-field and in the near-field. The method of computation is validated by comparing its predictions with a reference solution of GW scattering. Its computational performances are also demonstrated, compared to those of the standard computation of the HSM integral formulae to be computed and on specific deformation of integration paths in the complex plane, as detailed in the paper. It allows the evaluation of the integrals without approximation other than that of numerical quadratures, ensuring high accuracy while offering high computingperformances. It indifferently applies in the far-field and in the near-field. The method of computation is validated by comparing its predictions with a reference solution of GW scattering. Its computational performances are also demonstrated, compared to those of the standard computation of the HSM integral formulae
Development of photoactivatable chemical tools to study actin dynamics
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Crystallization field around geometric singularity in filled natural rubber
No full textInternational audienceNatural Rubber (NR) is widely used in the automotive industry due to its antivibration properties and high fatigue lifetime. When subjected to loadings with sufficiently high cyclic load ratio, parts and samples lifetime increase, and crack propagation rate decreases. These improvements are at least partly related to mechanically induced crystallization (MiC). The link is nevertheless not clearly understood as it involves not only changes in phase content (due to MiC) but also in anisotropy, or dissipation. As a consequence, and despite recent proposals [1][2][3], MiC is rarely integrated in a comprehensive manner, in the design loop against fatigue, both from constitutive model and fatigue criteria points of view. The main goal of this study is to better understand the links between fatigue properties and crystallization as well as other microstructural changes, and to integrate these changes in prediction models in order to greatly increase lifetime prediction accuracy. To do so, a first major objective of our work is to characterize accurately MiC occurring in filled NR materials when submitted to mechanical loads usually met in industrial applications, throughout a large panel of experimental tools, from wide angle X-ray diffraction (WAXD) to thermomechanical observations using digital image correlation (DIC) and Infra-red (IR) thermography. Another major objective is to apply various mechanical protocols in order to dissociate the coupled influence of time on microstructural changes and mechanics, as visco-elasticity, crystallization kinetics and chains orientations are intricated. As a first step, relaxation tests in temperature were realized while the index of crystallinity was followed-up. These tests were realized a laboratory X-ray generator. As a second step, other tests were realized at European Synchrotron Radiation Facility (ESRF): relaxing and non-relaxing cyclic tests, anhysteretic test, creep and relaxation tests … These tests were carried out on three materials: filled and unfilled natural rubber and filled isoprene rubber. We mainly focus our attention in this communication to the presentation of extensive WAXD measurements and detail various microstructural indicators such the size of crystallites, their orientation, index of crystallinity, volumetric density of crystallites.[1] A. Gros, E. Verron, et B. Huneau, « A physically-based model for strain-induced crystallization in natural rubber. Part II: Derivation of the mechanical model », Journal of the Mechanics and Physics of Solids, vol. 125, p. 255 275, 2019.[2] J. Guilié, T.-N. Le, et P. Le Tallec, « Micro-sphere model for strain-induced crystallisation and three-dimensional applications », Journal of the Mechanics and Physics of Solids, vol. 81, p. 58 74, 2015.[3] M. Kroon, « A constitutive model for strain-crystallising Rubber-like materials », Mechanics of Materials, vol. 42, no 9, p. 873 885, 2010