Path computation in multi-layer networks: Complexity and algorithms

Carrier-grade networks comprise several layers where different protocols coexist. Nowadays, most of these networks have different control planes to manage routing on different layers, leading to a suboptimal use of the network resources and additional operational costs. However, some routers are able to encapsulate, decapsulate and convert protocols and act as a liaison between these layers. A unified control plane would be useful to optimize the use of the network resources and automate the routing configurations. Software-Defined Networking (SDN) based architectures, such as OpenFlow, offer a chance to design such a control plane. One of the most important problems to deal with in this design is the path computation process. Classical path computation algorithms cannot resolve the problem as they do not take into account encapsulations and conversions of protocols. In this paper, we propose algorithms to solve this problem and study several cases: Path computation without bandwidth constraint, under bandwidth constraint and under other Quality of Service constraints. We study the complexity and the scalability of our algorithms and evaluate their performances on real topologies. The results show that they outperform the previous ones proposed in the literature.Comment: IEEE INFOCOM 2016, Apr 2016, San Francisco, United States. To be published in IEEE INFOCOM 2016, \<http://infocom2016.ieee-infocom.org/\&g

Algorithme incrémental pour les graphes de voisins relatifs

National audienceNeighborhood graphs know increasing use in many fields as in Data Science, or Multi-dimensional data Indexing. This interest is the result of their ability to express similarity and closeness in both an intuitive and efficient manner, but also because of the emergence of graph databases and graph computation frameworks. In this short paper we propose a fast exact incremental procedure for the construction of Relative Neighborhood Graphs, and then inspired by previous work, we propose a faster heuristic methodLes graphes de proximité connaissent un usage conséquent ces dernières années comme alternatives aux méthodes traditionnelles de classification et d'indexation de données. Dans ce travail, nous proposons une méthode exacte pour la mise à jour de graphes de voisins relatifs, et nous proposons une heuristique plus efficace en combinant notre approche avec des travaux existants

Structural and Vibrational Properties of C60 and C70 Fullerenes Encapsulating Carbon Nanotubes

Carbon nanotubes (CNTs) can encapsulate small and large molecules, including C60 and C70 fullerenes (so-called carbon peapods). The challenge for nanotechnology is to achieve perfect control of nanoscale-related properties, which requires correlating the parameters of synthesis process with the resulting nanostructure. For that purpose, note every conventional characterization technique is suitable, but Raman spectroscopy has already proven to be. First, the different possible configurations of C60 and C70 molecules inside CNTs are reviewed. Therefore, the following changes of properties of the empty nanotubes, such as phonon modes, induced by the C60 and C70 filling inside nanotube are presented. We also briefly review the concept of Raman spectroscopy technique that provides information on phonon modes in carbon nanopeapods. The dependencies of the Raman spectrum as a function of nanotube diameter and chirality, fullerene molecules configuration and the filling level are identified and discussed. The experimental Raman spectra of fullerenes and fullerenes peapods are discussed in the light of theoretical calculation results. Finally, the variation of the average intensity ratio between C60 and C70 Raman-active modes and the nanotube ones, as a function of the concentration molecules, are analyzed, and a general good agreement is found between calculations and measurements

An LP V/H∞ integrated Vehicle Dynamic Controller

International audienceThis paper is concerned with the design and analysis of a new multivariable LP V /H∞ (Linear Parameter Varying) robust control design strategy for Global Chassis Control. The main objective of this study is to handle critical driving situations by activating several controller subsystems in a hierarchical way. The proposed solution consists indeed in a two-step control strategy that uses semi-active suspensions, active steering and electro-mechanical braking actuators. The main idea of the strategy is to schedule the 3 control actions (braking, steering and suspension) according to the driving situation evaluated by a specific monitor. Indeed, on one hand, rear braking and front steering are used to enhance the vehicle yaw stability and lateral dynamics, and on the other hand, the semi-active suspensions to improve comfort and car handling performances. Thanks to the LP V /H∞ framework, this new approach allows to reach a smooth coordination between the various actuators, to ensure robustness and stability of the proposed solution, and to significantly improve the vehicle dynamical behavior. Simulations have been performed on a complex full vehicle model which has been validated using data obtained from experimental tests on a real Renault Mégane Coupé. Moreover, the suspension system uses Magneto-Rheological dampers whose characteristics have been obtained through experimental identification tests. A comparison between the proposed LPV/H∞ control strategy and a classical LTI/H∞ controller is performed using the same simulation scenarios and confirms the effectiveness of this approach

A LPV/Hinf fault tolerant control of vehicle roll dynamics under semi-active damper malfunction

International audienceThis paper proposes a LPV/Hinf fault tolerant control strategy for roll dynamics handling under semi-active damper's malfunction. Indeed, in case of damper's malfunction, a lateral load transfer is generated, that amplifies the risks of vehicle roll over. In this study, the suspension systems efficiency is monitored through the lateral (or longitudinal) load transfer induced by a damper's malfunction. The information given by the monitoring system is used in a partly fixed LPV/Hinf controller structure that allows to manage the distribution of the four dampers forces in order to handle the over load caused by one damper's malfunction. The proposed LPV/Hinf controller then uses the 3 remaining healthy semi-active dampers in a real time reconfiguration. Moreover, the performances of the car vertical dynamics (roll, bounce, pitch) are adapted to the varying parameter given by the monitoring of the suspension system efficiency, which allows to modify online the damping properties (soft/hard) to limit the induced load transfer. Simulations are performed on a complex nonlinear full vehicle model, equipped by 4 magneto-rheological semi-active dampers. This vehicle undergoes critical driving situations, and only one damper is considered faulty at ones. The simulation results show the reliability and the robustness of the proposed solution

LPV methods for fault-tolerant vehicle dynamic control

International audienceThis paper aims at presenting the interest of the Linear Parameter Varying methods for vehicle dynamics control, in particular when some actuators may be in failure. The cases of the semi-active suspension control problem and the yaw control using braking, steering and suspension actuators will be presented. In the first part, we will consider the semi-active suspension control problem, where some sensors or actuator (damper leakage) faults are considered. From a quarter-car vehicle model including a non linear semi-active damper model, an LPV model will be described, accounting for some actuator fault represented as some varying parameters. A single LPV fault-tolerant control approach is then developed to manage the system performances and constraints. In the second part the synthesis of a robust gain-scheduled H1 MIMO vehicle dynamic stability controller (VDSC), involving front steering, rear braking, and four active suspension actuators, is proposed to improve the yaw stability and lateral performances. An original LPV method for actuator coordination is proposed, when the actuator limitations and eventually failures, are taken into account. Some simulations on a complex full vehicle model (which has been validated on a real car), subject to critical driving situations (in particular a loss of some actuator), show the efficiency and robustness of the proposed solution

Les limites de l’équivalence dans la traduction juridique

The limits of equivalence in legal translation   It is obvious that the main specificity of legal texts is to refer to legal systems and forms of thought rooted in a culture specific to a particular country. The texts of law are the result of reflections of an ethical, philosophical, psychological, cultural and religious order and for this each concept has its own legal system which is based on founding texts such as the constitution for French and American law and the Koran. and the Sunna for the law of Muslim countries. Consequently, the translator will have to translate into the target language concepts and notions that often only exist in the source language. The present paper aims at shedding light on the processes adopted by translators when dealing with the translation of legal texts with its different domains. The translator presents the synthesis of the linguistic expression, of the law, that is to say a "jurilinguistics" at the confluence of the law and the language, because it is difficult to translate a legal document without knowing the law of the two languages as it is difficult for a lawyer to translate their text well without a perfect mastery and general knowledge of both languages

Raman-active modes in defective peapod

International audienceThe vibrational properties of defective single-walled carbon nanotube filled with C60 fullerene is the subject of the current study. For this aim we use the spectral moments method in the framework of the bond-polarization theory to calculate the nonresonant Raman spectra of hexa-vacancy defective C60 peapods. Essentially, the vibrational properties are closely coupled with the atomic structure of the system. The evolution of the Raman spectrum as a function of the spatial arrangement of defects in carbon nanotubes is discussed. This work provides benchmark theoretical results to understand the experimental data of defective C60 peapod

Durability and Long-term Structural Performance of GFRP Bars in Concrete

ABSTRACT Although glass fibre reinforced polymer (GFRP) bars do not corrode in the same way as conventional steel reinforcement, their physical and mechanical properties are prone to degradation following exposure to a variety of aggressive environments. Despite the relatively large amount of research on durability of FRP reinforcement in concrete environments, the available design models are still not able to account for all of the most typical in-service conditions, especially the effect of sustained stress on long-term properties. Thus, there is a need to develop a reliable prediction model to estimate the rate of degradation of GFRP bars and long-term performance in real structural applications. A comprehensive test programme was carried out on 348 GFRP specimens subjected to different environments (concrete, alkali solution and tap water), different temperature levels (20, 40, 60°C) and two different levels of sustained stress. The mechanical performance of the GFRP specimens, as well as their physical and chemical characteristics, were evaluated through the implementation of a complementary set of techniques, including direct tension test, flexural tests, inter-laminar shear tests, moisture absorption, SEM-EDX, FTIR, and DMA. The material tests were complemented by accelerated tests on GFRP RC tension ties and small-scale beams to examine the effect of the studied environments on the long-term bond and flexural behaviour of GFRP RC members under service conditions. While no significant reduction was observed in the elastic modulus of the tested GFRP bars, tensile strength, flexural strength and transfer properties (ILSS) were found to be affected by the conditioning environment. The most significant cause of GFRP bar degradation in concrete was found to be driven by chemical reactions, which tend to be accelerated by a range of physical processes, with elevated temperatures playing a key role in triggering and accelerating the development of critical degradation mechanisms. The test results on the long-term performance of GFRP bars in concrete showed that stressed specimens conditioned in a wet environment underwent a reduction in tension stiffening response as a result of bond degradation and a reduced stress transfer from the bar to the surrounding concrete. The results also indicated that the accelerated aging conditions affected overall flexural behaviour and led to overall higher deflections and larger crack widths. A new framework, based on the implementation of the Arrhenius principle and a TSF concept, was developed to account for the effects of exposure temperature, moisture, sustained stress and service life on residual long-term properties of GFRP bars in concrete. A modified design equation was developed and proposed, along with a revised set of environmental reduction factor

Temperature Effects on Grinding Residual Stress

AbstractResidual stress is a key factor that influences the reliability, precision, and life of final products. Earlier studies have alluded to the fact that the grinding process is usually the source of a tensile residual stress on the part surface, while there exists a temperature level commonly referred to as the onset tensile temperature beyond which the tensile profile of residual stresses starts to be generated. In this paper, a physics-based model is proposed to predict the onset temperature as a function of residual stress on an analytical and quantitative basis. The predictive model is based on the temperature distribution function using a moving heat source approach. Then, the thermal stresses are calculated analytically using Timoshenko thermal stress theory [1] followed by an elastic-plastic relaxation condition imposed on these stresses, thus leading to the resulting residual stresses. The model-predicted results have been experimentally validated using data of the grinding of AISI52100 hardened steel with subsequent X-ray and Neutron diffraction measurements. The model was shown to predict the residual stress profile under given process conditions and material properties, therefore providing an analytical tool for grinding process planning and optimization based on the understanding of onset tensile temperature for control of tensile residual stresses