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International audience; Data-intensive cloud computing systems are growing year by year due to the increasing volume of data. In this context, data replication technique is frequently used to ensure a Quality of service, e.g., performance. However, most of the existing data replication strategies just reproduce the same number of replicas on some nodes, which is certainly not enough for more accurate results. To solve these problems, we propose a new data Replication and Placement strategy based on popularity of User Requests Group (RPURG). It aims to reduce the tenant response time and maximize benefit for the cloud provider while satisfying the Service Level Agreement (SLA). We demonstrate the validity of our strategy in a performance evaluation study. The result of experimentation shown robustness of RPURG.

The new concept of the Internet of Things (IoT) is bringing new forms of knowledge and applications that rely on smart objects able to sense and process the collected data on a remote workflow server in the perspective to generate automated decisions. In this context, one of the main problems is how to schedule the data flow circulating between objects, and between objects applications. The cooperation between these objects is a promising solution to meet this challenge. Business process management (BPM) is the most adapted way to carry out data management thanks to workflow processes. To this end, a new semantics operator which the authors call a gateway for intelligent process scheduling of IoT (GIPSIT) is proposed as a semantic gateway enabling the management of data flows circulating between the connected objects of IoT. The researchers validate their approach based on GIPSIT operator by implementing a realistic eHealth based-scenario in a Smart Home. The obtained findings showed clearly the importance of this new operator in the context of IoT.

International audience; Water plays a crucial role in the agricultural field for food production and raising livestock. Given the current trends in world population growth, the urgent food demand that must be answered by agriculture highly depends on our ability to efficiently exploit the available water resources. Among critical issues, there is water management. Recently, innovative technologies have improved water management and monitoring in agriculture. Internet of Things, Wireless Sensor Networks and Cloud Computing, have been used in diverse contexts in agriculture. By focusing on the water management challenge in general, existing approaches are aiming at optimizing water usage, and improving the quality and quantity of agricultural crops, while minimizing the need for direct human intervention. This is achieved by smoothing the water monitoring process, by applying the right automation level, and allowing farmers getting connected anywhere and anytime to their farms. There are plenty of challenges in agriculture involving water: water pollution monitoring, water reuse, monitoring water pipeline distribution network for irrigation, drinking water for livestock, etc. Several studies have been devoted to these questions in the recent decade. Therefore, this paper presents a survey on recent works dealing with water management and monitoring in agriculture, supported by advanced technologies. It also discusses some open challenges based on which relevant research directions can be drawn in the future, regarding the use of modern smart concepts and tools for water management and monitoring in the agriculture domain.

The dynamic thermal simulation of buildings is a real challenge, in terms of regulations and labelling but also of decisions (implementation, materials choice, architectural design, rehabilitation …). Today, we lack reference models of the dynamic thermal behaviour of the cooling floor under solar radiation effect. In fact, the simulation models developed in literature are represented in a very simplified method and cannot be used for a detailed analysis of thermal comfort. The present study aims to reduce the knowledge gap and resolve the limitations such as (i) studying the effect of sunspot for a real weather conditions, (ii) visualize the dynamic thermal behaviour of indoor air and surface cooling floor relative to the sunspot shifting and (iii) predict different sunspot shape as a function of geographic location. A 3D model is presented in this paper to evaluate the sunspot impact on cooling floor coupled to underground tank under climatic conditions in Algeria. The sunspot is calculated using a coupled TRNSYS-FLUENT dynamic simulation. Simulations are run for different periods and weather conditions. The results have shown that the developed model can provide a real simulation of thermal performance of the cooling floor taking into account the sunspot shifting. The incident solar heat flux on cooling floor reaches a maximum of 300 W/m2 for Bechar city and 120 W/m2 for Oran city. A wide surface temperature ranges of 13 °C between the umbrageous and illuminated areas. For Oran weather conditions, the indoor air temperature in the umbrageous area is around 24 °C, while that of the illuminated area is 28 °C which can cause a temperature heterogeneity in the room.

Pure and Mg-doped manganese oxide thin films were synthesized on heated glass substrates using the spray pyrolysis technique. The surface chemical composition was investigated by the use of X-ray photoelectron spectroscopy (XPS). Structural and morphological properties were studied by using X-ray diffraction (XRD), scanning electron microscope (SEM) and atomic force microscopy (AFM). Optical properties were characterized by UV-visible spectroscopy. XPS spectra showed typical Mn (2p3/2), (2p1/2) and O (1s) peaks of Mn3O4 with a slight shift attributed to the formation of different chemical states of manganese. XRD analysis revealed the tetragonal phase of Mn3O4 with a preferred (211) growth orientation that improved with Mg-doping, likewise, grain size is observed to increase with the Mg doping. SEM images of Mn3O4 films showed rough surfaces composed of uniformly distributed nanograins whose size decreases with the Mg-doping. The manganese oxide films surface observed in AFM show a textured, rough and porous surface. The combination of transmittance and absorption data in the UV-visible range allowed determining the energy values of the Eg band gap (1.5–2.5 eV). The decrease of the band gap with the Mg-doping increase is attributed to the influence of the greater size of the Mg2+ ion in the manganese oxide lattice.

Chemically-modified alginate (obtained by grafting urea on alginate, with different ratios; alginate-urea (1:1) and its new derivatives alginate-urea (1:2) with an exceed of the percent of amino group by 7%) was successfully tested for mercury sorption in aqueous solutions. The influence of pH on metal sorption was first investigated: optimum pH was close to 5.5. Sorption isotherms were modeled using the Langmuir and the Sips equations, and sorption capacity slightly increased with the increased of the % of–NH2 in the sorbent and the maximum sorption capacity exceeded 200 mg Hg l−1 (1.07 mmol Hg g−1; for alginate-urea (1:2)), this means two times the sorption capacity of reference material (i.e., non-modified alginate), and also has a capacity improved compared to alginate-urea (1:1). Under selected experimental conditions the equilibrium was reached with 6–8 h of contact and the kinetic profiles were modeled using the pseudo-first order equation (PFORE), the pseudo-second-order rate equation (PSORE) and the resistance to intraparticle diffusion (RIDE). Surface functional groups, notably; –NH2, –OH and –COOH, were involved in mercury sorption by alginate-urea, suggesting the ion exchange, complexation and/or electrostatic interaction of Hg(II) on the alginate-urea surface. The use of this material, environmentally friendly and simply obtained from a renewable resource, reveals promising for the treatment of low-metal concentration effluents: sorption capacities are comparable to alternative academic and commercials sorbents.

International audience; Nowadays, the massive proliferation of real-world multimedia devices has paved the way to the emergence of a new paradigm called the Internet of Multimedia Things wherein Low-power and Lossy Networks (LLNs) are the main components of this new technology. RPL is an IPv6 routing protocol for LLNs designed by IETF to meet the requirements of a wide range of LLN applications such as Wireless Multimedia Sensor Networks where video traffic is expected to reach 6 times more than non-video traffic in 2025. The mono-instance version of RPL is far from satisfying the network’s Quality of Service (QoS) and the user’s Quality of Experience (QoE), as video in its compressed form is typically composed of various frames with different priorities requiring different QoS and QoE levels. In this paper, we exploit the multi-instance version of RPL for developing a new routing approach that improves the transport of a compressed video, composed of two types of frames with different priorities, by delivering each of them on the corresponding instance. The fundamental question we are addressing, is to find the best way to construct these instances: instances with Nodes Disjoint (ND) or Links Disjoint (LD). To do so, we designed a Multi-Instance routing protocol, named MI-RPL, and we performed extensive simulation experiments using the Cooja simulator. The comparison of MI-RPL-ND, MI-RPL-LD and RPL which regards to QoS and QoE performance metrics, confirms that multi-instance routing for video transmission in WMSN (and in particular MI-RPL-ND) is the best choice.

In the field of organic photovoltaic cells (OPVs), ternary planar heterojunction allows widening absorption range. Optimization of the energy levels at the organic interfaces is the first task to achieve in order to obtain OPVs with high efficiency. In ternary OPVs, carrier mobility, charge transfer and presence of energy transfer are determinant. Here, we compare the performances of different, binary (electron donor/fullerene) and ternary (electron donor/ambipolar material/fullerene) combinations of small organic molecules in planar heterojunction (PHJ) cells. We chose the different ED molecules in order to investigate the different possible band scheme alignments. The study shows that if the open circuit voltage (Voc) is limited by the energy levels of the outer layers, i.e. the difference between the lowest unoccupied molecular orbital (LUMO) of the electron acceptor and the highest occupied molecular orbital (HOMO) of the outer electron donor layer, the energy loss can be smaller than 0.2 eV. If efficient ternary OPVs need global energy offset higher than the exciton energy to separate the charges of the exciton, the distribution of this offset between ΔLUMO and ΔHOMO is not critical. The mobility value of the carriers in the intercalated layer is determinant in obtaining performance of OPVs. Overlap between the photoluminescence of ED and the optical absorption of EDA is primordial for good energy transfer. The highest OPV efficiency improvement is obtained with organic materials such as ED and EDA that have the same HOMO and similar hole mobility which give homogeneous thin layers.

Light field technology represents a viable path for providing a high-quality VR content. However, such an imaging system generates a high amount of data leading to an urgent need for LF image compression solution. In this paper, we propose an efficient LF image coding scheme based on view synthesis. Instead of transmitting all the LF views, only some of them are coded and transmitted, while the remaining views are dropped. The transmitted views are coded using Versatile Video Coding (VVC) and used as reference views to synthesize the missing views at decoder side. The dropped views are generated using the efficient dual discriminator GAN model. The selection of reference/dropped views is performed using a rate distortion optimization based on the VVC temporal scalability. Experimental results show that the proposed method provides high coding performance and overcomes the state-of-the-art LF image compression solutions., Comment: IEEE International Conference on Multimedia and Expo (ICME), Jul 2020, Londre, United Kingdom

We compare the performances of organic photovoltaic cells (OPVCs) based on binary and ternary planar heterojunctions. The organic active layers are pentathiophene (5T), subphthalocyanine (SubPc) and fullerene (C60). SubPc being an ambipolar material we used it either as electron acceptor in binary OPVCs or as central layer in ternary cells in order to increase the efficiency of OPVCs using 5T as electron donor. So, the different OPVC configurations were 5T/C60, 5T/SubPc and 5T/SubPc/C60. The effect of the different organic layer thicknesses on the device performances was studied. In order to understand the behavior of the different OPVC configurations, we proceeded with a morphological study. The influence of the high roughness of the 5T layer on the OPVCs performances is discussed. The best OPVCs performances are obtained with the binary structure 5T/SubPc. Its maximum efficiency corresponds to an increase of 50% compared to the OPVC based on the couple 5T/C60. External Quantum Efficiency measurements show that both layers participate to the current generation. The efficiency increase is mainly due to the increase of the open circuit voltage ([Formula: see text]). In the case of ternary OPVCs, [Formula: see text] is limited by the band structure of 5T and C60, moreover, the efficiency is also limited by the poor charge collection efficiency of the ternary structure and the series resistance of the three stacked organic layers.

International audience; Deferred-preemption model has been proposed as a compromise between fully preemptive and non-preemptive systems: on one hand they reduce the cache related preemption delays; on the other hand they introduce a small blocking time to higher priority tasks. In this paper, we investigate the problem of allocating a set of real-time tasks with fixed-preemption points onto an identical multi-core platform. We first propose enumerative and branch-and-bound optimal algorithms, along with techniques to reduce their execution time. Further, we propose a set of heuristics to solve the same problem. We demonstrate the performances of the proposed approaches by the means of a large set of synthetic experiments. ACM Reference Format

We report on the photocatalytical properties of pure and barium-doped nickel oxide nanofilms synthesised on glass substrates using a simple spray pyrolysis method. The nanofilms were prepared from ...

International audience; Saliency prediction can be of great benefit for 360-degree image/video applications, including compression, streaming , rendering and viewpoint guidance. It is therefore quite natural to adapt the 2D saliency prediction methods for 360-degree images. To achieve this, it is necessary to project the 360-degree image to 2D plane. However, the existing projection techniques introduce different distortions, which provides poor results and makes inefficient the direct application of 2D saliency prediction models to 360-degree content. Consequently, in this paper, we propose a new framework for effectively applying any 2D saliency prediction method to 360-degree images. The proposed framework particularly includes a novel convolutional neural network based fusion approach that provides more accurate saliency prediction while avoiding the introduction of distortions. The proposed framework has been evaluated with five 2D saliency prediction methods, and the experimental results showed the superiority of our approach compared to the use of weighted sum or pixel-wise maximum fusion methods.

International audience; Al-SBA-15 is an interesting mesoporous material having highly ordered nanopores and a large surface area, which is widely employed as catalysts and adsorbents, but relatively few studies on the surfaces properties of this type of materials have been carried out. The purpose of the present work was to advance knowledge on the textural properties of Al-SBA-15 by applying the accurate NLDFT method as well as to gain insight into the surface characterisation and acidic trend of this material. Mesoporous Al-SBA-15 molecular sieves, in three SiO2/Al2O3 ratios: 50, 75 and 100 were accomplished by post-synthesis alumination in aqueous solution of a purely siliceous SBA-15 material. The obtained solids were characterized using powder X-ray diffraction (XRD), X-ray fluorescence (XRF), N-2 adsorption-desorption (BET/DFT), transmission electron microscopy (TEM), water adsorption and zeta potential measurements. The results indicate that Al atoms have been successfully incorporated into the framework of the hexagonal mesoporous SBA-15. The aluminum introduced amount has remarkably affected the surface properties of the SBA-15 solid, indeed microporosity decreased. Furthermore, the esterification test showed that the Al-SBA-15 material exhibit Bronsted acid properties with an interesting activity leading to yields of similar to 90% of biodiesel.

Among ITO alternative, dielectric/metal/dielectric multilayer structures are one of the most often studied possible substituent. However, if their optical and electrical properties are systematically investigated it is not the same with regard to their mechanical properties. In the present manuscript we have studied the properties of ZnS/Cu/Ag/ZnS, ZnS/Cu/Ag/MO 3 (with M = Mo or W) structures. With a maximum transmission of 90% and a sheet resistance of 5 Ω/sq the optimum structure exhibits a figure of merit of 82 10 −3 Ω −1 when λ = 600 nm. Beyond these standard measures we proceeded to the study of the mechanical properties of the multilayer structures. The inner and outer bending tests show that the ZnS/Cu/Ag/ZnS (or MO 3 ) structures are more flexible than ITO, while their responses to scotch tests show that they exhibit a large adhesion to the substrate, glass or plastic. The scratching adhesion test puts in evidence that the adhesion to the substrate of the Ag layer is smaller than that of ZnS/Cu/Ag/ZnS, which is smaller than that of ITO. On the other hand, this test shows that the ZnS/Cu/Ag/ZnS (no cracks for L = 25 N) is less brittle than ITO (cracks L = 15N). Finally, when used as anode in organic solar cells, the structure ZnS/Cu/Ag/WO 3 allows achieving the best efficiency, similar to that obtained with ITO.

Due to their light weight, flexibility and semi-transparency the organic photovoltaic cells play an important role for solar conversion photovoltaic (OPV). To achieve good performances, both donor and acceptor materials in OPVs need to have good extinction coefficients, high stabilities and good film morphologies. Since the donor plays a critical role as the absorber to solar photon flux, donor materials require wide optical absorption to match the solar spectrum. In this work the couple ED/EA in planar heterojunction was Tetracyano 4,4'-bis(9Hcarbazol-9-yl) biphenyl (TCC)/fullerene (C60). Optimum results are obtained when MoO3 alone is used as Hole Transporting Layer (HTL). The J/V characteristics do not exhibit S-shaped curves up to a TCC layer thickness of 15 nm, while they did when the HTL includes CuI. Theoretical study, complementary to the experimental study, shows that in the case of S-shaped curve the cell behaves as if it was made up of 2 diodes, one of which would be opposed to the flow of the photogenerated current. In the case of MoO3 HTL, i.e; without shaped curve, the optimum thickness is 13 nm, giving an efficiency η = 2.30% with V oc = 0.9 V, J sc = 5.17 mA/cm2 and FF = 49%.

International audience; Maximum Concurrent Flow techniques try to combine a maximum flow graph resolution and the satisfaction of queries on this graph. They are proven to give better performance over classical heuristic data-source placement methods combined with greedy query resolution. A new version of the MCF approach is proposed and examined. It is tailored to provide MCF properties for large IoT networks. The results found from evaluation and comparison with other algorithms show that it has high efficiency and outperforms many recent solutions.

The mixing improvement by passive control is of wide practical interest. The lobed diffuser, which mixes the primary and secondary streams with high efficiency, has been widely used for heat and mass transfer in the field of fluid engineering. In addition, the jets through lobed generate streamwise vortices, which mix the ambient air and the jet fluid more effectively. The main objective of the present work is to develop new air diffusers for heating, ventilation, air conditioning (HVAC) systems using different jet geometries, in order to improve the users’ thermal comfort. Three free jets of air diffusers emitted from a tubular lobed, with six and five lobes, and from a swirl nozzle have been both studied experimentally and numerically. All diffusers have the same throat diameter. It turns out that the results obtained with the LES/WALE and LES/K-ET turbulence models are respectively in good agreement with the experimental results of the lobed and swirling jets. These results indicate that the best mixture is obtained using the six-lobed nozzle with respect to the five-lobed nozzle and the swirling nozzle. In addition, the importance of the jet type on the mixing capacity is highlighted.

Public software repositories (SR) maintain a massive amount of valuable data offering opportunities to support software engineering (SE) tasks. Researchers have applied information retrieval techniques in mining software repositories. Topic models are one of these techniques. However, this technique does not give an interpretation nor labels to the extracted topics and it requires manual analysis to identify them. Some approaches were proposed to automatically label the topics using tags in SR, but they do not consider the existence of spam-tags and they have difficulties to scale to large tag space. This article introduces a novel approach called automatically labelled software topic model (AL-STM) that labels the topics based on observed tags in SR. It mitigates the shortcomings of manual and automatic labelling of topics in SE. AL-STM is implemented using 22K GitHub projects and evaluated in a SE task (tag recommending) against the currently used techniques. The empirical results suggest that AL-STM is more robust in terms of MAP and nDCG, and more scalable to large tag space.

International audience; The emergence of the Internet of Things (IoT) as the next generation megatrend has paved the way for pervasive, ubiquitous and proficient healthcare monitoring systems. In the diverse kinds of networks, Wireless Body Area Network (WBAN) has been perceived as one of the most promising wireless sensor technologies for improving healthcare services thanks to its potential for continuous and real-time monitoring of health conditions. However, the open nature of wireless communication introduces wide security and privacy concerns as personal health information could be exposed to unauthorized parties or even malicious adversaries. Furthermore, in such a dynamic and heterogeneous environment where the context conditions continuously and frequently change, adaptive and context-aware solutions become mandatory to satisfy burgeoning security and privacy requirements. Therefore, it is indispensable to adaptively secure the extra-body communication between the smart portable device held by the WBAN client and the healthcare providers while considering the dynamic context changes. In this paper, we propose a context-aware access control and anonymous authentication approach based on a secure and efficient Hybrid Certificateless Signcryption (H-CLSC) scheme. Particularly, it incorporates the merits of Ciphertext-Policy Attribute-Based Signcryption (CP-ABSC) and Identity-Based Broadcast Signcryption (IBBSC) in order to meet the security requirements and provide adaptive contextual privacy. From a security perspective, the proposed mechanism achieves confidentiality, integrity, anonymity, context-aware privacy, key escrow resistance, public verifiability, and ciphertext authenticity. Performance analysis proves the efficiency and the effectiveness of the H-CLSC scheme compared to benchmark schemes in terms of functional security, storage, communication, and computational cost.

International audience; The Software Defined Networking (SDN) paradigm proposes to decouple the control plane (decision-making process) and the data plane (packet forwarding) to overcome the limitations of traditional network infrastructures, which are known to be difficult to manage, especially at scale. Although there are previous works focusing on the problem of Quality of Service (QoS) routing in SDN networks, only few solutions have taken into consideration the network consistency, which reflects the adequacy between the decisions made and the decisions that should be taken. Therefore, we propose a network architecture that guarantees the consistency of the decisions to be taken in an SDN network. A consistent QoS routing strategy is, then, introduced in a way to avoid any quality degradation of prioritized traffic, while optimizing resources usage. Thus, we proposed a traffic dispersion heuristic in order to achieve this goal. We compared our approach to several existing framework in terms of best-effort flows average throughput, average video bitrate and video Quality of Experience (QoE). The emulations results, which are performed using the Mininet environment, clearly demonstrate the effectiveness of the proposed approach that outperforms existing frameworks.

This paper presents Real-Time Network-on-chip-based architecture Analysis and Simulation tool (ReTiNAS), with a special focus on real-time communications. It allows fast and precise exploration of real-time design choices onto NoC architectures. ReTiNAS is an event-based simulator written in Python. It implements different real-time communication protocols and tracks the communications within the NoC at cycle level. Its modularity allows activating and deactivating different NoC components and easily extending the implemented protocols for more customized simulations and analysis. Further, we use ReTiNAS to perform a comparative study of analysis and simulation for different communication protocols using a wide set of synthetic experiments.

International audience; This work concerns the preparation and modification of mesoporous silica SBA-15 with different amine-copper complexes in order to study their impact on the catalytic behavior via Aza Michael addition. Firstly, SBA-15 was prepared hydrothermally, then functionalized by mono-, di- and tri-amine, and in the second step, copper (II) was anchored. The catalytic activity of these solids was evaluated at room temperature under liquid-phase conditions. Effects of catalyst nature, catalyst mass, reaction time and the starting reagents nature were investigated. Cu@SBA-15 (non-aminated) was shown to be efficient in the Aza Michael addition, but after its second re-use, a progressive decrease in the product yield was obtained due to copper leaching. The catalytic behavior of all prepared catalysts showed a selective reaction via the mono-Aza-Michael addition. Amongst all the catalysts, the one containing the monoamine-copper complex led to the highest yield. This catalyst was used in four consecutive cycles without significant loss of activity, which confirms its stability.

Emulsifier-free polystyrene latexes with immobilized triazolic residues have been prepared by batch emulsion copolymerization of styrene with 1,2,3-triazole-based acrylic monomers containing diethylene or triethylene glycol monomethyl ether groups DEGTz and TEGTz, respectively. The effect of monomer structure and concentration on polymerization conversion, particle size, and morphology was investigated. Particle composition was also evidenced by 1H-NMR analysis. It was found that DEGTz monomer with the shorter pegylated chain allows the formation of the smaller particles with a better control of polytriazole water soluble oligomers formation. DEGTz and TEGTz were then used in batch and shot-growth polymerization of styrene-d8 in the aim to highlight the effect of deuterium isotope substitution. It was shown that the use of deuterated styrene significantly impacts the polymerization conversion as well as particle size and shape regardless of the monomer structure. Shot-growth process disadvantaged the copolymer particle formation in favor of obtaining water soluble polymers. This was confirmed from the NMR study and from the large values of surface charge density of latexes obtained from electrophoretic mobility.

International audience

International audience; The present paper addresses the dynamic scheduling problem of smart products in a Flexible Manufacturing System (FMS). Unrelated machines, multiple product families, operation setups and dynamic job arrivals are considered. The goal is to propose a dynamic selection of smart products scheduling rules enriched with a context perception capability that is optimized using a hyper heuristic. A proof of concept with preliminary results is given

IF=1.559; International audience; In this paper, we introduce an improved Greedy Randomized Adaptive Search Procedure (GRASP) based heuristic for the multi-product multi-vehicle inventory routing problem (MMIRP). The inventory routing problem, which combines the vehicle-routing problem and the inventory control decisions, is one of the most important problems in combinatorial optimization field. To deal with the MMIRP, we develop a GRASP-based heuristic (GBH). Each GBH iteration consists of two sequential phases; the first phase is a Greedy Randomized Procedure, in which, the best tradeoff between the inventory holding cost and routing cost is looked. Then, in the second phase, as local search for the GRASP, we use the Tabu search (TS) meta-heuristic to improve the solution found in the first phase. The GBH two phases are repeated until some stopped criterion is met. Our proposed method is evaluated on two benchmark data sets, and successfully compared with two state-of-the-art algorithms.

International audience; We propose a dynamic replication strategy that satisfies simultaneously availability and performance tenant requirements while taking into account the tenant budget and the provider profit. The proposed strategy is based on a cost model that aims to calculate the minimum number of replicas required to maintain a high data availability. A replica creation is triggered only when this number of replicas is not reached or when the response time objective is not satisfied. Then, the replication must be profitable for the provider when creating a new replica. Furthermore, data replication and query scheduling are coupled in order to place these replicas in a load balancing way while dealing with the tenant budget. The experiment results prove that the proposed strategy can significantly improve availability and performance while the tenant budget is taken into account.

International audience; N,N-Diisopropylferrocenecarboxamide can be enantioselectively deprotometalated by combining butyllithium with (‒)-sparteine in diethyl ether at low temperature. It is of interest to identify conditions that could allow substrates bearing more reactive functional groups (such as esters and ketones) to be similarly converted. We here report our efforts to use different chiral lithium-zinc bases, made from a simple chiral lithium amide, (R,R)- or (S,S)-lithium bis(1-phenylethyl)amide (PEALi), for the enantioselective deprotonation of N,N-diisopropylferrocenecarboxamide. First, different zinc-based in situ traps were employed to intercept the formed ferrocenyllithium; optimization using enantiopure lithium bis[1-(S)-phenylethyl]amide ((S)-PEALi) led to the 2-iodo derivative in 96% yield and 69% ee in favor of the RP enantiomer. The method was extended to N,N-dimethylferrocenecarboxamide, morpholinoferrocenecarboxamide and N,N-diethylferrocenecarboxamide; for the latter, similar yield and enantioselectivity were recorded. DFT calculations on a model reaction showed very small differences between the activation energies leading to (RP)- and (SP)-2-lithioferrocenecarboxamides.Next, the behavior of various mixed amino-alkyl lithium zincates of the types R2[(S)-PEA]ZnLi and R2[(S)-PEA]2ZnLi2 (R = alkyl) was studied, notably by varying the reaction temperature and time, and the amount of base. The best results were obtained with Me2[(S)-PEA]2ZnLi2, affording the 2-iodo derivative in 97% yield and 86% ee in favor of the SP enantiomer.

International audience; In this study, the photo-assisted SCR-NH3 activities of vanadium containing zeolite X (ZX-V) and Ag@ZX-V catalysts are investigated under visible-light and soft temperature conditions (RT and T = 150 °C). The highly dispersed silver was incorporated into the zeolite structure as Agn δ+ nano and sub-nano-clusters with small particle size using a new photochemical concept. The catalysts were characterized using different techniques such as XRD, N2 sorption, H-TEM, and DR–UV–Vis. An in situ FTIR study of adsorbed CO was also performed for the characterization of the metal sites and their accessibility. The catalytic reaction was investigated using the operando FTIR technique allowing the study of both Ag@ZX-V and ZX-V catalytic surfaces, and the gas phase of the reaction in real time. Both catalysts are not active in dark and only Ag@ZX-V exhibits a photocatalytic activity under visible light. At RT, the results show that silvers clusters promote the photocatalytic oxidation of NH3/NO, and no SCR is observed. This probably due to an energy transfer from the metallic site to the triplet oxygen and the formation of highly oxidant singlet oxygen. However, at T = 150 °C a significant photo-assisted SCR activity is observed under visible light irradiation with more than 18% of additional NOx removal. The different behavior of the material at 150 °C in respect to its activity at RT is mainly attributed to the additional formation of silver nanoparticles and to the possible formation and conversion of intermediates that are not formed and or converted at RT (thermodynamic limitation). Basing on this study, a possible mechanism of the photo-assisted SCR reaction over Ag@ZX-V catalyst is proposed. © 2019 International Solar Energy Society

International audience; Wireless sensor networks (WSNs) find extensive applications in various sensitive domains such as tracking, monitoring, environmental data collection and border surveillance. In these cases, the collected data are considered as a critical resource and used to detect any anomalies or abnormal behavior, providing information about an occurring event or a node failure. An outlier detection process must be set up to ensure the proper functioning of the monitoring system. The existing approaches are limited by assumptions on a specific distribution or a predefined data range of the collected data. Often these assumptions do not hold in practice, the data distribution is not known or determining reliable upper and lower bounds for the set of data is not possible. To overcome this, we propose a new copula-based probabilistic multivariate outlier detection method for faulty node detection in wireless sensor networks (WSNs). The joint probability density function of the copula is constructed considering dependency among the captured n−sensed measures without making any assumptions on the distribution of the collected data. The samples having probabilities violating a predetermined control limit are classified to be faulty. The performance of the proposed technique is observed to be better than the existing statistical methods.

International audience; Many resource-constrained applications make use of data aggregation in order to prolong the network lifetime. However, the resource-constrained devices are usually deployed in unattended environments in which providing security is of paramount importance. This leads to various attacks that can occur during data aggregation process. Internal attacks such as selective forwarding represent the most dangerous ones since they cannot be detected by existing cryptography- based protocols proposed to secure data aggregation. In this work, we propose a two-levels verification, in which data is verified using cryptography and intrusion detection techniques. Indeed, a lightweight homomorphic encryption is combined with a game-theory based technique to efficiently secure data aggregation. Our analysis and results show the applicability of the system for aggregation-based resource-constrained applications, especially those considering sensitive information (e.g. health monitoring, military) where the time-efficient detection is crucial.

International audience; This paper presents a cross-layer communication protocol for Wireless Sensor Network (WSN) enabled surveillance system for sensitive fenced areas, e.g., nuclear/oil site. Initially, the proposed protocol identifies the boundary nodes of the deployed WSN to be used as sentinel nodes, i.e., nodes that are always in active state. The remaining nodes are used as duty-cycled relay nodes during the data communication phase. The boundary nodes identification process and data routing are both performed using an enhanced version of the Greedy Perimeter Stateless Routing (GPSR) protocol, which relies on a Non Unit Disk Graph (N-UDG) and referred to as GPSR over Symmetrical Links (GPSR-SL). Both greedy and perimeter modes of GPSR-SL forward data through symmetrical links only. Moreover, we apply the Mutual Witness (MW) fix to the Gabriel Graph (GG) planarization, to enable a correct perimeter routing on a N-UDG. Simulation results show that the proposed protocol achieves higher packet delivery ratio by up to 3.63%, energy efficiency and satisfactory latency when compared to the same protocol based on the original GPSR.

Pristine and strontium doped ZnO nanometric films were successfully synthesized on heated glass substrates by the ultrasonic spray pyrolysis technique. The samples were characterized by means of X-ray diffraction (XRD), Atomic Force Microscope (AFM), UV–visible spectroscopy and photoluminescence (PL). X-ray diffraction patterns confirmed the hexagonal (wurtzite) structure, where the most pronounced (002) peak indicates the preferential orientation along the c-axis perpendicular to the sample surface. The intensity of this peak was increased rapidly from the first doping of 1% and its position was shifted toward higher angles under Sr-doping effect. For the used doping range of 1–5%, the Sr-doping at 3% attracted an especial attention. At this concentration, the particular transformation in the surface morphology of doped ZnO films was observed. The surface became granular and rough by expanding the crystallites' size. From optical measurements, transmittance and PL spectra were found to be sensitive to Sr-doping, where two different behaviors were observed before and after 3% of Sr-doping. Keywords: Ultrasonic spray pyrolysis, Sr-doped ZnO, Morphology study, Optical properties

Quartz has found a wide range of applications over the past years. In the present work, the temperature dependence of microcrystalline quartz is investigated with Raman spectroscopy and DFT-based molecular dynamics simulations. We aimed to determine the structure at short and medium range distances as a function of the increasing temperature. The dynamics and the structural changes are analysed in terms of time-dependent properties, and the vibrational analysis obtained from calculated dipole trajectory and vibrational density of states (VDOS). The computed data is compared to Raman and infrared spectroscopic measurements. The approach is of a particularly great interest when we focus on the structural behaviour, and the dynamical disorder observed and characterised through geometric and thermodynamic data. The calculations confirm that the infrared and Raman signature as a function of temperature provide a sensitive analysis of the structural behaviour of quartz.

International audience; In this works, we have explored a new method for a green synthesis of poly(ethylglyoxylate) (PEtG). This method consists on using a montmorillonite clay called Maghnite-H+ as an eco-catalyst to replace triethylamine which is toxic. Cationic polymerization experiments are performed in bulk conditions at three temperatures (-40 degrees C, 25 degrees C, 80 degrees C) and in THF solutions at room temperature (25 degrees C). At 25 degrees C, an optimum ratio of 5 wt% of catalyst leads to molar masses up to 22000 g/mol in THF solutions. Polymerizations in bulk conditions lead to slightly lower masses than experiments conducted in THF solutions. However, bulk polymerization of ethyleglyoxylate remains a preferable method in order to avoid the use of a solvent and therefore to stay in the context of green chemistry. The structure of obtained polymers are characterized and confirmed by H-1 and C-13 NMR. Thermogravimetric Analysis (TGA) shows an enhanced thermal stability for end-capped PEtG compared to non-terminated PEtG. The best conversion rate (92%) is observed in bulk conditions at 25 degrees C for a reaction time of 48h. An activation energy could be calculated from bulk experiments (Ea = 6.9kJ/mol). An interesting advantage of Maghnite-H+ is an easy recoverage by a simple filtration from the polymer solution.

International audience; Wireless Sensor Networks (WSNs) are arising from the pro- liferation of Micro-Electro-Mechanical Systems (MEMS) tech- nology as an important new area in wireless technology. They are composed of tiny devices which monitor physi- cal or environmental conditions such as temperature, pres- sure, motion or pollutants, etc. Moreover, the accuracy of individual sensor node readings is decisive in WSN ap- plications. Hence, detecting nodes with faulty sensors can strictly influence the network performance and extend the network lifetime. In this paper, we propose a new approach for faulty sensor node detection in WSNs based on Copula theory. The obtained experimental results on real datasets collected from real sensor networks show the effectiveness of our approach.

International audience; The grafting of urea and biuret on alginate backbone (confirmed by MR spectrometry analysis) increases by 53-84% the sorption efficiency of the biopolymer for Cd(II), Cu(II) and Pb(II) recovery from mild acidic solutions (i.e., pH in the range 4.5-5.5). Sorption isotherms are successfully described by the Langmuir and the Sips equations: maximum sorption capacities reach up to 3.7 mmol Cd g(-1), 4.7 mmol Cu g(-1) and 4.8 mmol Pb g(-1) for alginate-urea beads. The affinity of the sorbent for metal ions is correlated to the electronic properties (softness) and configuration of hydrated ions and to the HSAB properties (Hard and Soft Acid-Bases rules) of the ligands present on the sorbent. The diffusion properties are playing a significant role in the control of the uptake kinetic profiles; however, the pseudo-second order rate equation also allows a good fit of experimental sorption kinetics. In multi-component solutions the sorbents maintain a higher affinity for Pb(II) over the other two divalent cations.

Bioclimatic architecture strategies and solar active systems contribute strongly to the reduction of building energy demand and achieving thermal comfort for its occupants over the whole year. This paper deals with the study of the energy performance improvement of a pilot bioclimatic house located in Algiers (Algeria). First, a series of experimental measures are conducted during cold period to show the effect of passive and active solar gains on the improvement of the indoor air temperature of the house. Then, a dynamic model of a solar heating system coupled with a bioclimatic house has been developed using TRNSYS software and validated with experimental data. The validated model has been used to establish the energy balance of the pilot bioclimatic house without solar heating system and to compare them to those of a conventional house. Finally, the improvement of the energy balance of the pilot bioclimatic house has been done by passive and active ways. The passive one includes the increase of south facing windows size and the use of night cooling with the use of shading device in summer. The active one consists of the integration of a solar heating system. Furthermore, an environmental study has been performed. The experimental results show that the energy requirements of a pilot bioclimatic house are very low which is suitable for the use of solar heating system in building. The simulation results show that the application of bioclimatic strategies is a better way to provide thermal comfort in summer and decrease the space heating energy demand of the house with 48.70%. The active solar system will cover 67.74% of the energy demand for heating of the house. These energy savings generate a significant reduction in CO2 emissions. Practical application: This work will enable engineers and designers of modern buildings of buildings in a Mediterranean climate to improve building energy efficiency and reduce CO2 emissions by a conjunction of different passive heating and cooling techniques such as insulation, thermal mass, window shades, night ventilation, and the solar heating system. The paper provides designers an effective strategy in terms of energy savings and indoor thermal comfort while reducing CO2 emissions.

International audience; Nowadays, the diversity and large deployment of video recorders results in a large volume of video data, whose effective use requires a video indexing process. However, this process generates a major problem consisting in the semantic gap between the extracted low-level features and the ground-truth. The ontology paradigm provides a promising solution to overcome this problem. However, no naming syntax convention has been followed in the concept creation step, which constitutes another problem. In this paper, we have considered these two issues and have developed a full video surveillance ontology following a formal naming syntax convention and semantics that addresses queries of both academic research and industrial applications. In addition, we propose an Ontology Video-surveillance Indexing and retrieval System (OVIS) using a set of Semantic Web Rule Language (SWRL) rules that bridges the semantic gap problem. Currently, the existing indexing systems are essentially based on low-level features and the ontology paradigm is used only to support this process with representing surveillance domain. In this paper, we developed the OVIS system based on the SWRL rules and the experiments prove that our approach leads to promising results on the top video evaluation benchmarks and also shows new directions for future developments.

Software Defined Networking (SDN) is in the process of revolutionizing the way of managing networks by providing a new way to support current and future services. However, by relocating the control functionality in a remote entity, the measurements' accuracy of the resources' utilization becomes more difficult, which complicates the decision making. Although there are previous works focusing on the problem of network management and measurement in SDN networks, only few proposed solutions have taken into consideration the tradeoff existing between statistics' polling frequency (i.e. generated overhead), and the accuracy of monitoring results (i.e. optimized resources' allocation). In this paper, we propose a new approach calculating accurately the bandwidth utilization while adapting the polling frequency according to ports/switches activity. The emulations' results under Mininet clearly demonstrate the effectiveness of the proposed solution, which outperforms existing works.

International audience; Model checking is a very powerful formal verification technique. Formal verification of complex systems is a major challenge in many areas of human society. The verification of properties of these systems is recognized as a difficult problem and faces a number of practical and theoretical problems. The main limitation of the formal verification is known as the state explosion problem. In this paper, we discuss about two contributions to this problem for the improvement of performance in time and memory space.

In this study, we numerically examined the interactions among multiple swirling jets mounted in unbalanced positions. The formulation was based on the Reynolds average Navier–Stokes equations. In this study, turbulence was modeled using different turbulence models, i.e., k − ɛ standard, renormalization group, and Reynolds stress model (RSM) to make comparisons. This study was conducted under uniform thermal conditions for each configuration. The working fluid was the air, the Reynolds number was fixed at Re 0 = 3.1 0 4 , and the swirl number calculated from the measured velocity data was 1.33. We performed this study using the finite-volume FLUENT computational fluid dynamics solver. For most of the configurations analyzed, the results obtained using the RSM model agreed better with the experimental data compared with the standard turbulence model. The analysis of the flow features with moderate mesh refinement showed that the interactions between the swirling jets redistributed the temperature in the mixing zone as well as promoting the radial spread of the resultant jet. As expected, the development of the central jet improved thermal homogenization. More importantly, our results showed that changing the position between the central and peripheral jets greatly affected the quality of the thermal homogenization of the atmosphere.

International audience; Use of efficient anode cathode buffer layer (CBL) is crucial to improve the efficiency of organic photovoltaic cells. Here we show that using a double CBL, Ca/Alq3, allows improving significantly cell performances. The insertion of Ca layer facilitates electron harvesting and blocks hole collection, leading to improved charge selectivity and reduced leakage current, whereas Alq3 blocks excitons. After optimisation of this Ca/Alq3 CBL using CuPc as electron donor, it is shown that it is also efficient when SubPc is substituted to CuPc in the cells. In that case we show that the morphology of the SubPc layer, and therefore the efficiency of the cells, strongly depends on the deposition rate of the SubPc film. It is necessary to deposit slowly (0.02nm/s) the SubPc films because at higher deposition rate (0.06nm/s) the films are porous, which induces leakage currents and deterioration of the cell performances. The SubPc layers whose formations are kinetically driven at low deposition rates are more uniform, whereas those deposited faster exhibit high densities of pinholes.

The performance of organic photovoltaic cells depends on different properties of the organic materials, such as carrier mobility, band structure, morphology, and crystallinity. For AlPcCl, it is shown that these properties are dependent on the layer deposition rates. As the deposition rate increases, the surface roughness of AlPcCl layers decreases. In contrast, the crystallinity of the layers increases as the deposition rate decreases, thereby increasing the hole mobility value. These effects are opposed: the former effect allows higher open circuit voltages to be obtained as the deposition rate increases, whereas the latter increases the short circuit current as the deposition rate decreases. Therefore, there is a trade-off between open and short circuit current values, and it is necessary to find the best deposition rate for AlPcCl. Here, it is shown that the highest mobility carriers in layers deposited slowly allow the use of thicker AlPcCl layers, which permits acceptable open circuit voltage values and optimum photovoltaic cell efficiencies to be obtained. This results in an optimum efficiency value of 3.97% for a 26-nm-thick AlPcCl film that is deposited at 0.02–0.03 nm s−1.

In the present work, we are interested to the experimental and numerical study of the free turbulent lobed jet, used in residential heating and air conditioning. The objective of our study is the improvement of the diffusion performance of the ventilation driving air flow, in the occupancy zone. The experiments have been conducted in a room where the dimensions enables a better execution in the conditions of free and hot vertical jet at unfavorable pushing forces. The installation contains a hot air blowing diffuser oriented from top to bottom. The velocities of the flow were measured by a multi-functional thermo-anemometer. The probe is supported by a stem guided vertically and horizontally in order to sweep a maximum space. Experimentally, we measured the axial and radial velocity field. The dynamics field analysis, show that in the potential core region, the dynamic profiles are more spread at the principal plane and this is due to the widening of the lobes’ opening. While, in the transition zone and in the region where the flow is fully developed, these profiles are not influenced by the type of plane and then the jet will be similar to the circular one. Numerically, we used the commercial software Fluent. The obtained numerical results with turbulence method, (RNG k-ε), were in good accordance with the experimental one.

International audience; In this paper, we address the problem of analyzing the behavior of a set of real-time tasks on a Network-on-chip-based (NoC) architecture. Our approach is to transform the allocation of tasks and communications within a NoC into a classical real-time allocation problem. It provides an extension of classical bin-packing heuristics to allocate a set of real-time applications modeled using a directed acyclic graphs (DAGs) to a set of processors interconnected through a NoC. The paper describes the schedulability analysis, including allocation and communication. It provides also a comparative study of different allocation and communication algorithms and presents accordingly a set of promising research insights.