Observing the Evolution of QUIC Implementations

The QUIC protocol combines features that were initially found inside the TCP, TLS and HTTP/2 protocols. The IETF is currently finalising a complete specification of this protocol. More than a dozen of independent implementations have been developed in parallel with these standardisation activities. We propose and implement a QUIC test suite that interacts with public QUIC servers to verify their conformance with key features of the IETF specification. Our measurements, gathered over a semester, provide a unique viewpoint on the evolution of a protocol and of its implementations. They highlight the arrival of new features and some regressions among the different implementations.Comment: 6 pages, 8 figure

Comparaison de descripteurs pour la classification de décompositions parcimonieuses invariantes par translation

National audienceNous étudions les descripteurs adaptés à la classification de décompositions parcimonieuses invariantes par translation. Nous comparons les différents descripteurs de l'état de l'art sur les mêmes données et avec le même classifieur, ce qui permet d'évaluer leurs efficacités et nous testons aussi leur robustesse à la translation. Grâce à un nouveau fenêtrage, une famille de nouveaux descripteurs est proposée, dépassant l'état de l'art tout en étant robuste à la translation

4DVarNet-SSH: end-to-end learning of variational interpolation schemes for nadir and wide-swath satellite altimetry

The reconstruction of sea surface currents from satellite altimeter data is a key challenge in spatial oceanography, especially with the upcoming wide-swath SWOT (Surface Ocean and Water Topography) altimeter mission. Operational systems however generally fail to retrieve mesoscale dynamics for horizontal scales below 100 km and time-scale below 10 days. Here, we address this challenge through the 4DVarnet framework, an end-to-end neural scheme backed on a variational data assimilation formulation. We introduce a parametrization of the 4DVarNet scheme dedicated to the space-time interpolation of satellite altimeter data. Within an observing system simulation experiment (NATL60), we demonstrate the relevance of the proposed approach both for nadir and nadir+swot altimeter configurations for two contrasted case-study regions in terms of upper ocean dynamics. We report relative improvement with respect to the operational optimal interpolation between 30 % and 60 % in terms of reconstruction error. Interestingly, for the nadir+swot altimeter configuration, we reach resolved space-time scales below 70 km and 7 days. The code is open-source to enable reproductibility and future collaborative developments. Beyond its applicability to large-scale domains, we also address uncertainty quantification issues and generalization properties of the proposed learning setting. We discuss further future research avenues and extensions to other ocean data assimilation and space oceanography challenges.</p

Spectroscopic measurement of the excitation spectrum on effectively curved spacetimes in a polaritonic fluid of light

Quantum fields in regions of extreme spacetime curvature give rise to a wealth of effects, like Hawking radiation at the horizon of black holes. While quantum field theory can only be studied theoretically in black holes, it can be tested in controlled laboratory experiments. Typically, a fluid accelerating from sub- to supersonic speed will create an effectively curved spacetime for the acoustic field, with an apparent horizon where the speed of the fluid equals the speed of sound. Here we create effective curved spacetimes with a quantum fluid of light, with smooth and steep acoustic horizons and various supersonic fluid speeds. We use a recently developed spectroscopy method to measure the spectrum of acoustic excitations on these spacetimes, thus observing negative energy modes in the supersonic regions. This demonstrates the potential of quantum fluids of light for the study of field theories on curved spacetimes.Comment: 5 pages, 3 figure

An adaptive multi-agent system for task reallocation in a MapReduce job

International audienceWe study the problem of task reallocation for load-balancing of MapReduce jobs in applications that process large datasets. In this context, we propose a novel strategy based on cooperative agents used to optimise the task scheduling in a single MapReduce job. The novelty of our strategy lies in the ability of agents to identify opportunities within a current unbalanced allocation, which in turn trigger concurrent and one-to-many negotiations amongst agents to locally reallocate some of the tasks within a job. Our contribution is that tasks are reallocated according to the proximity of the resources and they are performed in accordance to the capabilities of the nodes in which agents are situated. To evaluate the adaptivity and responsiveness of our approach, we implement a prototype test-bed and conduct a vast panel of experiments in a heterogeneous environment and by exploring varying hardware configurations. This extensive experimentation reveals that our strategy significantly improves the overall runtime over the classical Hadoop data processing

Prise en compte de l’occupant dans une démarche interdisciplinaire de réhabilitation durable

Une approche interdisciplinaire avec une entrée relevant des sciences humaines et sociales peut conduire à une meilleure prise en compte de l’occupant dans les opérations de réhabilitation. Celle décrite ici s’appuie sur l’analyse du processus informationnel et communicationnel qui s’instaure entre l’usager et son cadre de vie. La satisfaction des usagers est au cœur de la démarche, qui intègre la perception du confort par l’usager sans pour autant chercher à changer son comportement. L’objectif est de proposer des scénarios de réhabilitation qui intègrent à la fois la dimension mesurable du confort et la dimension perçue par l’occupant. Pour illustrer nos propos, nous avons choisi d’expliciter un exemple : celui du confort thermique.An interdisciplinary approach based human and social sciences can lead to a better understanding of the householder concerning the process of rehabilitation. The one described here insists on the informative and communicative analysis established between the user and his environment. Users' satisfaction is at the core of the procedure. It includes the user’s perception of comfort without trying to change his behaviour. The aim is to offer different scenarios of rehabilitation that include at the same time the measurement of comfort and the measurement perceived by the householder. To illustrate this point, we have chosen to work on the thermal comfort example