A DTN routing scheme for quasi-deterministic networks with application to LEO satellites topology

We propose a novel DTN routing algorithm, called DQN, specifically designed for quasi-deterministic networks with an application to satellite constellations. We demonstrate that our proposal efficiently forwards the information over a satellite network derived from the Orbcomm topology while keeping a low replication overhead. We compare our algorithm against other well-known DTN routing schemes and show that we obtain the lowest replication ratio without the knowledge of the topology and with a delivery ratio of the same order of magnitude than a reference theoretical optimal routing

L'évaluabilité du Crédit d'Impôt pour la Transition Énergétique

Le Crédit d’Impôt pour la Transition Energétique (CITE), anciennement Crédit d’Impôt Développement Durable (CIDD), est un dispositif fiscal dont l’objectif depuis 2005 est d’inciter les ménages à réaliser des travaux de performance énergétique dans leur logement. La rénovation énergétique du parc de logements français constitue un défi majeur pour les pouvoirs publics et s’inscrit dans l’ambition française d’économies d’énergie et de réduction des émissions de gaz à effet de serre (GES). Au cours des dix dernières années, le dispositif a subi de nombreux ajustements, avant de devenir en 2014 le CITE, avec un taux unique à 30%. Dans un contexte de rationalisation des dépenses publiques il apparaît nécessaire d’interroger et d’expliciter les ressorts d’un tel outil de politique publique. Des évaluations, souvent ponctuelles et centralisées, ont été menées au cours de son exercice pour tester son efficacité énergétique et son efficience conomique avec des résultats contrastés fondés sur des modèles théoriques ou des enquêtes déclaratives. Cette étude porte sur les pistes d’évaluabilité du CITE, dans l’objectif de contribuer à son amélioratio

Cross metathesis of bio-sourced fatty nitriles with acrylonitrile.

International audienceWe report the cross metathesis of two olefinic partners contg. different types of nitrile functionality. Thus, cross metathesis of fatty nitriles with acrylonitrile have been achieved with olefin metathesis ruthenium catalysts. 10-Undecenenitrile provides 2-dodecenedinitrile with a high turnover no. of 13,280 in the green solvent, di-Et carbonate. Cross metathesis with the internal carbon-carbon double bond of oleonitrile gave the expected products, and the cleavage of the internal double bond proved to be more difficult probably owing to faster catalyst decomposition

DTN routing for quasi-deterministic networks with application to LEO constellations

We propose a novel DTN routing algorithm, called DQN, specifically designed for quasi-deterministic networks with an application to satellite constellations. We demonstrate that our proposal efficiently forwards the information over a satellite network derived from the Orbcomm topology while keeping a low replication overhead. We compare our algorithm against other well-known DTN routing schemes and show that we obtain the lowest replication ratio with a delivery ratio of the same order of magnitude than a reference theoretical optimal routing. We also analyze the impact of terrestrial gateways density and analyze DQN performances in heterogeneous cases

FLOWER - Fuzzy lower than-best effort transport protocol

We present a new delay-based transport protocol named FLOWER, that aims at providing a Lower-than-Best-Effort (LBE) service. The objective is to propose an alternative to the Low Extra Delay Background Transport (LEDBAT) widely deployed within the official BitTorrent client. Indeed, besides its intra-fairness problem, known as latecomer unfairness, LEDBAT can be too aggressive against TCP, making it ill suited for providing LBE services over certain networks such as constrained wireless networks. By using a fuzzy controller to modulate the sending rate, FLOWER aims to solve LEDBAT issues while fulfilling the role of a LBE protocol. Our simulation results show that FLOWER can carry LBE traffic in network scenarios where LEDBAT cannot while solving the latecomer unfairness problem. Finally, the presented algorithm is simple to implement and does not require complex computation that would prevent its deployment

Polyester layered silicate nanohybrids by controlled grafting polymerization

peer reviewedPoly( epsilon-caprolactone) (PCL) layered silicate nanohybrids were synthesized by ring opening polymerization of epsilon-caprolactone according to a well-controlled coordination-insertion mechanism. Montmorillonites were surface-modified by non functional (trimethylhexadecylammonium) and hydroxy functional alkylammonium cations, i.e., (2-hydroxyethyl) dimethylhexadecylammonium. The hydroxy functions available at the clay surface were activated into tin( II or IV) or Al(III) alkoxide initiators for lactone polymerization, thus yielding surface-grafted PCL chains. The surface-grafted PCL chains were recovered by an ionic exchange reaction with lithium chloride and they were analyzed by size exclusion chromatography. The PCL molar mass was measured as a function of the hydroxy content of the clay that was modulated by exchanging the Na cations with mixtures of non-functional and hydroxy functional ammonium cations of different compositions. Nanohybrids were also characterized by small-angle X-ray diffraction, transmission electron microscopy and thermogravimetry. The PCL molar mass and the nanocomposite morphology (i.e., exfoliation and/or intercalation) were readily tuned by the content of the hydroxy groups available at the clay surface. Surface-grafted aluminium trialkoxide species proved highly efficient in initiating polymerization that leads to PCL chains of controlled molar mass and narrow molecular weight distribution with polydispersity indices as low as 1.2

Towards an engineering approach for advanced interaction techniques in 3D environments

National audienceIn recent years, Virtual Environments have appeared in new areas such as mass-market, web or mobile situations. In parallel, advanced forms ofinteractions are emerging such as tactile, mixed, tangible or spatial user interfaces, promoting ease of learning and use. To contribute to the democratization of 3D Virtual Environments(3DVE) and their use by persons who are not experts in 3D and occasional users, simultaneously considering Computer Graphics and Human Computer Interaction design considerations is required. In this position paper, we first provide an overview of a new analytical framework for the design of advanced interaction techniques for 3D Virtual Environment. It consists in identifying links that support the interaction and connect user’s tasks to be performed in a 3DVE with the targeted scene graph. We relate our work to existing modeling approaches and discuss about our expectations with regards to the engineering of advanced interaction techniqu

On The Existence Of Optimal LEDBAT Parameters

The Low Extra Delay Background Transport (LEDBAT) protocol is a recently standardized protocol that aims to offer a scavenger service (i.e. the goal is to exploit the remaining and unused capacity of a link). LEDBAT is a delay-based protocol mainly defined by two parameters: a target queuing delay and a gain. The RFC 6817 provides guidelines to configure both parameters that strongly impact on the LEDBAT behavior in terms of fairness with other protocols. However, these guidelines are questioned by several studies as they might lead to the generation of a non-LBE (Less-than-Best-Effort) traffic. This paper explores the set of optimal parameters allowing LEDBAT protocol to effectively perform as an LBE traffic. We conclude that the optimal couple of target and decrease gain is (5ms; 10). However, we observe that the aggregated use of optimized LEDBAT sources still disturb the overall traffic performance and that the exponential backoff is not an answer to this issue. As a result, we believe that additional strategies to limit the number of LEDBAT flows are required for integrating this protocol at a large scale

Digital Holographic Interferometry in the Long-Wave Infrared for the Testing of Large Aspheric Space Reflectors

Digital holographic (DH) interferometry has been developed in the long-wave infrared spectral range with CO2 lasers and microbolometer arrays. This application has been driven by the European Space Agency’s constant need of techniques for monitoring large displacements of large structures. Here the study focuses on the case of aspheric mirrors, like parabola and ellipses. Usually they are tested through interferometric wavefront error measurements which require expensive null-lenses matching each of the reflectors considered. In the case of monitoring deformation a holographic technique can be considered where the wavefront is compared with itself at different instant. Therefore the optical can be quite simple and easily reconfigurable from one reflector to another. The advantage of using long wavelength is that large deformations can be measured at once, in addition to being more immune against environmental perturbations. Another advantage of DH at such wavelengths is that the ratio between the wavelength and the pixel size allows reconstructing objects 5 to 10 times larger than with DH in the visible. In this project we considered first the case of a 1.1 meter diameter parabola for submillimeter range observations. Such specimen shows strong specular reflectivity. We have developed several set-ups with different ways to illuminate the object and to collect rays to form the object beam: either through point source or through and extended diffuser working by reflection of the laser beam. Both possibilities have been compared in terms of fringe quality as well as measurement range. We selected the diffuser illumination for applying the set-up into a large vacuum facility for measuring the deformation of the parabola between 224 and 107 K. Results of this measurement campaign are presented. A further application has been shown by observation of off-axis ellipse. In this case interferometric testing is difficult to achieve and LWIR DHI with diffuser illumination is found quite simple to implement and gives straightforward results.GSTP HOLODI

Smartphone Based 3D Navigation Techniques in an Astronomical Observatory Context: Implementation and Evaluation in a Software Platform

International audience3D Virtual Environments (3DVE) come up as a good solution to transmit knowledge in a museum exhibit. In such contexts, providing easy to learn and to use interaction techniques which facilitate the handling inside a 3DVE is crucial to maximize the knowledge transfer. We took the opportunity to design and implement a software platform for explaining the behavior of the Telescope Bernard-Lyot to museum visitors on top of the Pic du Midi. Beyond the popularization of a complex scientific equipment, this platform constitutes an open software environment to easily plug different 3D interaction techniques. Recently, popular use of a smartphones as personal handled computer lets us envision the use of a mobile device as an interaction support with these 3DVE. Accordingly, we design and propose how to use the smartphone as a tangible object to navigate inside a 3DVE. In order to prove the interest in the use of smartphones, we compare our solution with available solutions: keyboard-mouse and 3D mouse. User experiments confirmed our hypothesis and particularly emphasizes that visitors find our solution more attractive and stimulating. Finally, we illustrate the benefits of our software framework by plugging alternative interaction techniques for supporting selection and manipulation task in 3D