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The Mars Organic Molecule Analyzer (MOMA) Instrument: Characterization of Organic Material in Martian Sediments
No full textInternational audienceThe Mars Organic Molecule Analyzer (MOMA) instrument onboard the ESA/Roscosmos ExoMars rover (to launch in July, 2020) will analyze volatile and refractory organic compounds in martian surface and subsurface sediments. In this study, we describe the design, current status of development, and analytical capabilities of the instrument. Data acquired on preliminary MOMA flight-like hardware and experimental setups are also presented, illustrating their contribution to the overall science return of the mission
Fault Tolerance of Self Organizing Maps
No full textInternational audienceAs the quest for performance confronts resource constraints, major breakthroughs in computing efficiency are expected to benefit from unconventional approaches and new models of computation such as brain-inspired computing. Beyond energy, the growing number of defects in physical substrates is becoming another major constraint that affects the design of computing devices and systems. Neural computing principles remain elusive, yet they are considered as the source of a promising paradigm to achieve fault-tolerant computation. Since the quest for fault tolerance can be translated into scalable and reliable computing systems, hardware design itself and the potential use of faulty circuits have motivated further the investigation on neural networks, which are potentially capable of absorbing some degrees of vulnerability based on their natural properties. In this paper, the fault tolerance properties of Self Organizing Maps (SOMs) are investigated. To asses the intrinsic fault tolerance and considering a general fully parallel digital implementations of SOM, we use the bit-flip fault model to inject faults in registers holding SOM weights. The distortion measure is used to evaluate performance on synthetic datasets and under different fault ratios. Additionally, we evaluate three passive techniques intended to enhance fault tolerance of SOM during training/learning under different scenarios
Network reduction based on multiple scenarios
No full textInternational audienceSimulation of large power systems require the reduction of the complexity of the network models. Different works propose methodologies to aggregate buses and to model the connections between those clusters, that are computationally expensive and developed to work around a specific operating point, presenting significant errors when that set-point changes. This paper proposes a methodology to define a reduced network model consisting in aggregating network buses, using clustering algorithms, and modelling the connections between them as an optimization problem as well as a performance assessment index to evaluate its accuracy. It differentiates from state of the art by the use of multiple operation scenarios, that help to improve its robustness to the system operation set-point, and through its application to a realistic case-study of the European transmission network
Trial-and-Error Learning of Repulsors for Humanoid QP-based Whole-Body Control
No full textInternational audienceWhole body controllers based on quadratic programming allow humanoid robots to achieve complex motions. However, they rely on the assumption that the model perfectly captures the dynamics of the robot and its environment, whereas even the most accurate models are never perfect. In this paper, we introduce a trial-and-error learning algorithm that allows whole-body controllers to operate in spite of inaccurate models, without needing to update these models. The main idea is to encourage the controller to perform the task differently after each trial by introducing repulsors in the quadratic program cost function. We demonstrate our algorithm on (1) a simple 2D case and (2) a simulated iCub robot for which the model used by the controller and the one used in simulation do not match
Conception d'une interface cerveau-ordinateur pour une meilleure surveillance des réveils peropératoires au cours d'une anesthésie générale
No full textInternational audienceEach year, several million of general anesthesia are realized in France. A recent study shows that, between 0.1-0.2 % of patients are victims of intraoperative awareness. This kind of awakening could cause post-traumatic syndromes for the patient. Unfortunately, today, no monitoring system is able to avoid the intraoperative awareness phenomenon. Interestingly, if there are no subject's movement due to curare, an electroencephalographical study of the motor cortex can help to detect an intention of movement. The dynamic study of motor cerebral activity during general anesthesia is essential if we want to create a brain-computer interface adapted to the detection of intraoperative awareness. The goal of this thesis is first, to realize a feasibility study. To this end, a clinical protocol is built to allow EEG data recording during general anesthesia with propofol. Then, the development of temporal analysis specific methods allows to quantify patterns of desynchronization and synchronization phases observed in delta, alpha and beta frequency bands. This will result in the creation of this interface.Chaque année en France, plusieurs millions d’anesthésies générales sont réalisées. Parmi celles-ci, on estime qu’entre 0.1 et 0.2% des patients subissent un réveil peropératoire. Actuellement, aucun dispositif de surveillance ne permet d’empêcher ce type de réveil alors même qu’il peut entraîner de graves séquelles psychologiques chez les patients(en anglais, Post-Traumatic Stress Disorder, PTSD). Or, l’étude par électroencéphalographie (EEG) de l'activité cérébrale au niveau des aires motrices peut révéler une intention de mouvement du patient reflétant une reprise de conscience, et ce même si aucun mouvement n'est perceptible visuellement par le personnel médical. Une BCI exploitant ces intentions de mouvements fournirait un outil innovant aux personnels médicaux et permettrait de limiter le nombre de PTSDs. Cependant, l'étude de la dynamique de l'activité cérébrale motrice au cours de l'anesthésie générale reste nécessaire pour concevoir une interface cerveau-ordinateur adaptée à la détection des réveils peropératoires. L’objectif de cette thèse est donc de réaliser une étude de faisabilité visant la création d’une interface permettant de détecter ce type de réveil. Pour cela, un protocole expérimental clinique est mis en place pour permettre l'acquisition de données EEG du cortex moteur pendant l'anesthésie générale sous propofol. Par la suite, le développement de méthodes d'analyse temporelle spécifiques permettra de quantifier les caractéristiques des phases de désynchronisation et de synchronisation observées dans les bandes de fréquences delta, alpha et bêta et conduira à la création de l’interface elle-même
Three-dimensional electromagnetic imaging of dielectric targets by means of the multiscaling inexact-Newton method
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Which Secure Transport Protocol for a Reliable HTTP/2-based Web Service : TLS or QUIC ?
No full textInternational audienceWeb browsing protocols are currently gaining the interest of the researchers. Indeed, HTTP/2, an improvement of HTTP/1.1 has been standardized in 2015 and meanwhile, Google proposed another transport protocol, QUIC (Quick UDP Internet Connection). The main objective of the two protocols is to improve end-users quality of experience and communications security. Current HTTP/2-based web servers rely on the standardized TLS (Transport Layer Security) protocol, on top of TCP. Google has developed its own security system, natively integrated within QUIC, and runs on top of UDP. If performance issues, comparing HTTP/2 over TLS/TCP and QUIC/UDP, have been investigated by few researchers, no one studied the security aspects of the two transport protocols. This paper aims at filling this gap and proposes a first security analysis of TLS/TCP and QUIC/UDP. Based on their characteristics, this paper identifies the vulnerabilities of the two protocols and evaluates their impacts on HTTP/2-based web services. This study can enable web servers developers or administrators to either select TLS/TCP or QUIC/UDP
Statistic Metrics for Evaluation of Binary Classifiers without Ground-Truth
No full textInternational audienceIn this paper, are presented a number of statistically grounded performance evaluation metrics capable of evaluating binary classifiers in absence of annotated Ground Truth. These metrics are generic and can be applied to any type of classifier but are experimentally validated on binarization algorithms. The statistically grounded metrics were applied and compared with metrics based on annotated data. This approach has statistically significant better than random results in classifiers selection, and our evaluation metrics requiring no Ground Truth have high correlation with traditional metrics. The experiments were conducted on the images from the DIBCO binarization contests between 2009 and 2013
Time Reversal Receive Antenna Shift Keying On MIMO LOS Channel
No full textInternational audienceReceive Antenna Shift Keying (RASK) is a Spatial Modulation (SM) transmission scheme that has recently been under study because of its low detection complexity and its ability to increase the spectral efficiency when combined with classical IQ modulation schemes. The idea is that the transmitter uses a focusing technique to target one of the receive antennas. The transmitted information is coded depending on the index of the receive antenna that have been targeted. Note that in this case, the sent signal does not contain any information, that's why RASK can be combined with any classical IQ modulation. Different focusing techniques could be used to target a receive antenna. In this study, the Time Reversal preprocessing technique is used at the transmitter side. In this paper, theoretical performance of the Bit Error Rate and of the focusing gain are established for the RASK scheme in a MIMO Line-of-Sight configuration with two receive antennas. Also, a testbed is evaluated and used to provide RASK performance in realistic conditions
Full-duplex communications to improve platooning control in multi-channel VANETs
No full textInternational audienceFull-duplex (FD) technologies promise to improve the performance of vehicular communications by enhancing the IEEE 802.11 medium access control (MAC) standard with collision detection capability and the simultaneous transmission and reception of data signals. In this paper, we propose a FD-based MAC extension for multi-channel vehicular networks based on IEEE 802.11. The solution is tailored to support platooning, considered as a crucial use case on the roadmap towards fully autonomous driving. A Control Channel (CCH) is used for the platooning service advertisement, and a Service Channel (SCH) carries data among platoon members. The on-board units in vehicles use FD capabilities to access both types of channels. Early achieved results show that the FD-enhanced solution is able to provide (i) higher reliability for the broadcast advertisement procedure carried out on the CCH, through a FD-enabled collision-detection mechanism, and (ii) increased capacity on the SCH, through FD-based simultaneous transmission and reception of messages among platoon vehicles intended to feed the driving control algorithm. These early encouraging results solicit further investigations to demonstrate the FD potentials in vehicular networks