• 2014-2023close
• Part of book or chapter of book close
• US close
• GB close
• IL close
• Mémoires en Sciences de l'Information et de la Communication close
• Hyper Article en Ligne close

International audience; In this paper, we study the effect of smartphone camera exposure on the performance of optical camera communications (OCC) link. The exposure parameters of image sensor sensitivity (ISO), aperture and shutter speed are included. A static OCC link with a 8 × 8 red, green and blue (RGB) LED array employed as the transmitter and a smartphone camera as the receiver is demonstrated to verify the study. Signal-to-noise ratio (SNR) analysis at different ISO values, the effect of aperture and shutter speed on communication link quality is performed. While SNRs of 20.6 dB and 16.9 dB are measured at 1 m and 2 m transmission distance, respectively for a ISO value of 100, they are decreased to 17.4 dB and 13.32 dB for a ISO of 800. The bit error rate (BER) of a 1 m long OCC link with a camera's shutter speed of 1/6000 s is 1.3 × 10 −3 (i.e., below the forward error correction BER limit of 3.8 × 10 −3) and is dropped to 0.0125 at a shutter speed of 1/20 s. This study provides insight of the basic smartphone settings and the exposure adjustment for further complex OCC links.

WEST (Tungsten Environment in Steady-State Tokamak) will be operating by the end of 2016 as a test bed for the ITER divertor components in long pulse operation. In this context, radiative cooling of highly ionized impurities like tungsten (W) sputtered from Plasma Facing Components (PFC) into the plasma core is a critical issue since even small impurity concentrations below 10-4 degrade significantly plasma performances and can lead to radiative collapse. In the plasma core, tungsten emission is dominant in the Soft X-ray (SXR) range 0.1 keV -- 15 keV with complex contributions from line transition, radiative recombination and Bremsstrahlung emission.This paper presents the recent development of a synthetic SXR diagnostic using GEM (Gas Electron Multiplier) detectors. This diagnostic will be used on WEST for W transport studies and will be equipped with two new GEM based poloidal cameras allowing 2D tomographic reconstructions with spectral resolution in energy bands. Thus once GEM response to plasma emissivity is characterized thanks to synthetic diagnostic, it offers new possibilities to disentangle the different SXR contributions in harsh fusion environments like e.g. WEST or ITER with respect to conventional semiconductor diodes working in current mode. Emitted SXR spectrum from the plasma is modelled thanks to ADAS database from given WEST scenario. The synthetic diagnostic includes Lines of Sight (LoS) etendues of the two cameras as well as probability of photoabsorption through filters, photoionization in the detection gas mixture (Ar-CO2), and transport of electron avalanches in the gas through GEM foils as computed with Magboltz. Local SXR emissivity is then retrieved from tomographic inversion using a Minimum Fisher Information (MFI) algorithm. Comment: in 43rd European Physical Society Conference on Plasma Physics, Jul 2016, Leuven, Belgium

The interplay among the effects of dispersion, nonlinearity and gain/loss in optical fibre systems can be efficiently used to shape the pulses and manipulate and control the light dynamics and, hence, lead to different pulse-shaping regimes [1,2]. However, achieving a precise waveform with various prescribed characteristics is a complex issue that requires careful choice of the initial pulse conditions and system parameters. The general problem of optimisation towards a target operational regime in a complex multi-parameter space can be intelligently addressed by implementing machine-learning strategies. In this paper, we discuss a novel approach to the characterisation and optimisation of nonlinear shaping in fibre systems, which combines numerical simulations of the governing equations to identify the relevant parameters and the machine-learning method of neural networks (NNs) to make predictions across a larger range of the data domain. We illustrate this general method through application to two configurations.

Abstract The serotonergic system plays a key modulatory role in the brain. This system is critical in many drug developments for brain disorders via interactions with the 14 subtypes of 5-HT receptors or through reuptake blockade. Positron emission tomography (PET) is an efficient tool for in vivo studies of physiological and pathological processes. Because of its pertinent radiochemical properties, fluorine-18 is one of the most used radioisotopes in PET imaging. This chapter will propose an overview of the 18F-radioligands targeting serotonin receptors, which have been developed over the last few years. Both radiosyntheses and pharmacological properties of these radiotracers will be described, with a specific emphasis on their potential medical applications.

International audience; The relative efficiency of auctions and negotiations is still a puzzle in the literature. While auctions are the prescribed procedures and the most used ones for public procurement, in the private sector, where buyers are free to choose their purchasing method, competitive tendering is far from being their preferred option (Bajari et al. 2009). In addition, recent empirical studies (Estache et al. 2009, Bajari et al. 2009) highlight some failures of auction procedures and identify conditions under which negotiation is more efficient. In particular, they show that auctions perform poorly when projects are complex. In this paper, our aim is to contribute to this debate by providing an empirical analysis of how awarding mechanisms are chosen in public procurement in France. To this end, we examine a comprehensive database of 76,188 observations corresponding to the entire set of public procurement work contracts awarded between 2005 and 2007 in the construction sector. We find empirical regularities regarding the choice of awarding procedures by public buyers. However, most of these regularities do not coincide with what the theoretical literature considers as transaction-cost minimizing behaviours. In particular, the size of the construction projects as well as the length of contracts do not appear as key determinants of the choice of awarding procedures, which translates into costly renegotiations.

International audience; In this paper, we provide a necessary clarification of the good security properties that can be obtained from parallel implementations of masking schemes. For this purpose, we first argue that (i) the probing model is not straightforward to interpret, since it more naturally captures the intuitions of serial implementations, and (ii) the noisy leakage model is not always convenient, e.g. when combined with formal methods for the verification of cryptographic implementations. Therefore we introduce a new model, the bounded moment model, that formalizes a weaker notion of security order frequently used in the side-channel literature. Interestingly , we prove that probing security for a serial implementation implies bounded moment security for its parallel counterpart. This result therefore enables an accurate understanding of the links between formal security analyses of masking schemes and experimental security evaluations based on the estimation of statistical moments Besides its consolidating nature, our work also brings useful technical contributions. First, we describe and analyze refreshing and multiplication algorithms that are well suited for parallel implementations and improve security against multivariate side-channel attacks. Second, we show that simple refreshing algorithms (with linear complexity) that are not secure in the continuous probing model are secure in the continuous bounded moment model. Eventually, we discuss the independent leakage assumption required for masking to deliver its security promises, and its specificities related to the serial or parallel nature of an implementation.

Part 6: Network Modeling; International audience; Mobile Adhoc Networks (MANET) are susceptible to jamming attacks which can inhibit data transmissions. There has been considerable work done in the detection of external jamming attacks. However, detection of insider jamming attack in MANET has not received enough attention. The presence of an insider node that has constantly monitored the network and is privy to the network secrets can acquire sufficient information to cause irreparable damage. In this paper we propose a framework for a novel reputation-based coalition game between multiple players in a MANET to prevent internal attacks caused by an erstwhile legitimate node. A grand coalition is formed which will make a strategic security defense decision by depending on the stored transmission rate and reputation for each individual node in the coalition. Our results show that the simulation of the reputation-based coalition game would help improve the network’s defense strategy while also reducing false positives that results from the incorrect classification of unfortunate legitimate nodes as insider jammers.

The standardization effort in vibration’s field has unfolded the interests of industries. This research aimed at better understanding of the impact of vibration on human body. In the past years, healthcare centers and manufacturers started to equip the workplace with Anti-fatigue Mats (AFM) for the improvement of the working conditions and quality at work. This study analyzed the impact of AFM on the reduction of vibrations transmitted during the weekly activity of manufacturing workers. Seven AFM marketed by Notrax Premium Superior Manufacturing Group were tested. The laser vibrometry technique was used in order to measure vibratory displacements at various points. Under the effect of the vibrations, AFM behaved differently according to their structure and geometries. In comparison, the values obtained showed that AFM absorbed the vibration. It permitted to decrease the risks of ligamentous, or articular pathologies, which can affect employees at work. Taking into account, different results obtained showing that AFM could be used effectively in different areas of workplace, such as in medical or manufacturing settings, in order to improve working conditions.