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In order to slow down the continuing environmental deterioration, regulations for pollutant emissions limitations are increasingly rigorous. The development of new alternative fuels for internal combustion engines is a very interesting solution not only to overcome the pollution problem but also because of the petroleum shortage. In this context, the present work investigates the improvement of a DI diesel engine operating at constant speed (1500 rpm) and under dual fuel mode with eucalyptus biodiesel and natural gas (NG) enriched by various H2 quantities (15, 25 and 30 by v%). The eucalyptus biodiesel quantity injected into the engine cylinder is kept constant, to supply around 10% of the engine nominal power, for all examined engine loads. The engine load is further increased using only the gaseous fuel (NG+H2), which is introduced with the intake air. The effect of H2/NG blending ratio on the combustion parameters, performance and pollutant emissions of the engine is investigated and compared with those of pure NG case. An important benefit in terms of brake specific fuel consumption, reaching a decrease of 4–10% with the 25% H2 blend compared to the pure NG case, is achieved. Concerning the pollutant emissions, NG enrichment with H2 is an efficient solution to enhance the combustion process and hence reduce carbon monoxide, unburned hydrocarbon and soot emissions at high loads where they are important for pure NG. However for the nitrogen oxide emissions, NG blending with H2 is attractive only at low and medium loads where their levels are lower than pure NG.

The objective is to develop a control algorithm for quadrotors that guarantees a good compromise robustness/performance in presence of external disturbances. Thus, we investigate and apply a nominal model-based control strategy doted by a robustness boosting mechanism. This latter, uses an Extended State-based Observer (ESO) to estimate the uncertainties and the various disturbances. The obtained controller is augmented by an additional input, which is derived via a sliding modes framework to handle the estimation errors and ensure asymptotic stability. The primary results are shown through numerical simulations.

With the evolution of the communication technology, fast and efficient tools for secure exchanged data are highly required. Through this research work, we introduce a simplified and fast chaos-based scheme for multimedia data encryption and in particular for color image encryption application. The new algorithm is based on an extracted four-dimension (4-D) discrete time map. The proposed 4-D chaos system includes seven (07) nonlinear terms and four (04) controllers to generate a robust chaos that can satisfy the encryption requirements. The performance of this image encryption algorithm are analyzed with the help of four important factors which are key space, correlation, complexity and running time. Results of the security analysis compared to some of similar proposals, show that our encryption scheme is more effective in terms of key stream cipher space, correlation, complexity and running time.

The heterogeneity and complexity of lignin necessitate a deep understanding to select the most appropriate lignin valorization and convert it into value-added products. The objective of this research is to investigate the features of organosolv and Kraft lignins, in order to understand the effects of the sources and the isolation treatment, through the comparison of physicochemical and thermal properties. Various techniques have been employed such us Fourier transform infrared spectroscopy (FTIR), carbon solid state nuclear magnetic resonance 13CNMR, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. It was found that lignin produced from the hardwood using the Kraft process provided the greatest yield compared to other combinations. Softwood pretreatments achieve almost higher sugar yield than hardwood treatments. The infrared spectroscopy analysis confirms the existence of different monolignols. Organosolv lignins showed a predominance of guaiacyl and syringyl units. To provide additional information, the principle components analysis, as a powerful chemometric method, has also been applied to evaluate the FTIR data. NMR spectroscopy of lignins demonstrated the presence of essential functional chemical groups. It is also revealed that the nature of the treatment and the source of lignin samples affect the thermal properties. Overall, lignin isolated from Aleppo pine using Kraft process presented better thermal stability than that of organosolv lignin.

International audience

Over the past few years, nanocellulose (NC), cellulose in the form of nanostructures, has been proved to be one of the most prominent green materials of modern times. NC materials have gained growing interests owing to their attractive and excellent characteristics such as abundance, high aspect ratio, better mechanical properties, renewability, and biocompatibility. The abundant hydroxyl functional groups allow a wide range of functionalizations via chemical reactions, leading to developing various materials with tunable features. In this review, recent advances in the preparation, modification, and emerging application of nanocellulose, especially cellulose nanocrystals (CNCs), are described and discussed based on the analysis of the latest investigations (particularly for the reports of the past 3 years). We start with a concise background of cellulose, its structural organization as well as the nomenclature of cellulose nanomaterials for beginners in this field. Then, different experimental procedures for the production of nanocelluloses, their properties, and functionalization approaches were elaborated. Furthermore, a number of recent and emerging uses of nanocellulose in nanocomposites, Pickering emulsifiers, wood adhesives, wastewater treatment, as well as in new evolving biomedical applications are presented. Finally, the challenges and opportunities of NC-based emerging materials are discussed.

Axial flow fans are used in many fields in order to ensure the mass and heat transfer from air, chiefly in the heating, ventilation and air conditioning industry (HVAC). A more proper understanding of the airflow behavior through the systems is necessary to manage and optimize the fan operation. Computational fluid dynamics (CFD) represents a real tool providing the ability to access flow structures in areas that measuring equipment cannot reach. Reducing the leakage flow rate, inherent in operation, by synthetic-jet techniques improves performance. This paper presents the CFD results performed on a hollow blade fan developed by our team. The leakage flow is controlled by blowing air from 16 designated circular holes and arranged on the fan shroud. We discuss the results for two rotational speeds (1000 and 2000 rpm) and two injection rates (400 and 800 L/min). The numerical results consistent with the experimental show, for the low rotation speed and high injection ratio, significant gains in power (53%), torque (80%) and leakage flow rate (80%).

Environmental benefits are one of the main motivations encouraging the use of natural gas as fuel for internal combustion engines. In addition to the better impact on pollution, natural gas is available in many areas. In this context, the present work investigates the effect of hydrogen addition to natural gas in dual fuel mode, on combustion characteristics improvement, in relation with engine performance. Various hydrogen fractions (10, 20 and 30 by v%) are examined. Results showed that natural gas enrichment with hydrogen leads in general to an improved gaseous fuel combustion, which corresponds to an enhanced heat release rate during gaseous fuel premixed phase, resulting in an increase in the in-cylinder peak pressure, especially at high engine load (4.1 bar at 70% load). The highest cumulative and rate of heat release correspond to 10% Hydrogen addition. The combustion duration of gaseous fuel combustion phase is reduced for all hydrogen blends. Moreover, this technique resulted in better combustion stability. For all hydrogen test blends, COVIMEP does not exceed 10%. However, no major effect on combustion noise was noticed and the ignition delay was not affected significantly. Regarding performance, an important improvement in energy conversion was obtained with almost all hydrogen blends as a result of improved gaseous fuel combustion. A maximum thermal efficiency of 32.5%, almost similar to the one under diesel operation, and a minimum fuel consumption of 236 g/kWh, are achieved with 10% hydrogen enrichment at 70% engine load.

International audience

In the present paper, a new joint eigenvalue decomposition (JEVD) method is developed by considering generalized Givens rotations. This method deals with a set of square matrices sharing a same eigenstructure. Several Jacobi-like methods exist already for solving the aforementioned problem. The differences reside in the way of estimating the Shear rotation. Herein, we clarify these differences, highlight the weaknesses of the existing solutions and develop a new robust method named Efficient and Stable Joint eigenvalue Decomposition (ESJD). Simulation results are provided to highlight the effectiveness of the proposed technique especially in difficult scenario.

This paper deals with a hybrid joint diagonalization (JD) problem considering both Hermitian and transpose congruences. Such problem can be encountered in certain non-circular signal analysis applications including blind source separation. We introduce new Jacobi-like algorithms using Givens or a combination of Givens and hyperbolic rotations. These algorithms are compared with state-of-the-art methods and their performance gain, especially in the high dimensional case, is assessed through simulation experiments including examples related to blind separation of non-circular sources., Supplementary material (ref. [18]) is included in this file

We study algorithms to compute the Shapley value for a cooperative game on a lattice L Σ = (F Σ , ⊆) where F Σ is the family of closed sets given by an implicational system Σ on a set N of players. The first algorithm is based on the generation of the maximal chains of the lattice L Σ and computes the Shapley value in O(|N | 3 .|Σ|.|Ch|) time complexity using polynomial space, where Ch is the set of maximal chains of L Σ. The second algorithm proceeds by building the lattice L Σ and computes the Shapley value in O(|N | 3 .|Σ|.|F Σ |) time and space complexity. Our main contribution is to show that the Shapley value of weighted graph games on a product of chains with the same fixed length is computable in polynomial time. We do this by partitioning the set of feasible coalitions relevant to the computation of the Shapley value into equivalence classes in such a way that we need to consider only one element of each class in the computation.

International audience; This paper deals with the estimation of power consumption for an unmanned road vehicle, according to the degree of steerability, the degree of redundancy and the path curvature changes. Thus, the main dynamic behaviors inducing directly or indirectly the power consumption for an autonomous road vehicle are considered for uniform and uniformly variable motions less than 15km/h. A comparison between different scenarios of piloting has been validated experimentally and through co-simulation using professional real-time dynamic vehicle simulator namely SCANeR Studio(c).

A novel spectral-based feature set is proposed for ground moving target classification using a battlefield surveillance radar. Precise frequencies and coefficients are extracted from the backscattered radar signal which is used as an information in Automatic Target Recognition (ATR) system to solve the problem of ground moving target classification. The proposed ATR system is realized by combining Gaussian Mixture Model (GMM) with Maximum Likelihood (ML) rule. Experimental signals, realized with ground surveillance radar operating in centimetre range wavelengths, are used to test our ATR system. Numerical evaluation results are presented to assess the performance gain provided by the proposed method.

International audience; In recent years, a plethora of different studies for design of traditional ensemble classifiers has been proposed in order to improve final recognition accuracy. However, among the ensemble classifiers, combination methods are focused on building independent classifiers of the same or different algorithms using majority voting methods. In this paper, we present a new fusion scheme for ensemble classifiers based on a new concept called Generalized Fuzzy Soft Set (GFSS), which we apply in activity classification. Essentially, we apply a weighted aggregate operator to the output of each classifier in order to fuse the GFSS into a more reliable classifier. The proposed fusion method is based on a new ranking algorithm to classify activities. We show that the proposed method produces more accurate results than the best single classifier and its effectiveness is demonstrated by comparing it with single classifier in terms of activity recognition accuracy.

International audience; In the present paper, a method based on a new concept called power fuzzy soft set is proposed for multi-observer decision making problems under uncertain information. The new method applies a weighted conjunctive operator to aggregate these sets into a reliable resultant power fuzzy soft set from the input data set. To decide among the alternatives, a new ranking algorithm is introduced. The effectiveness and feasibility of this method are demonstrated by comparing it to algorithms based on the maximum score in decision making.

Artificial potential field and fuzzy logic are efficient approaches for mobile robots autonomous navigation. However, both have advantages and drawbacks. Their integration into a common control scheme can significantly improve the performances of the resulting hybrid controller. In this article, we propose a novel hybrid approach in order to better exploit their advantages. The present work contributes in three aspects: first, the proposed control scheme integrates interval type-2 fuzzy logic concepts with artificial potential field concepts into a common framework in order to better exploit their advantages. Second, the proposed control scheme is a simple and realizable design for real-time implementation because only 15 fuzzy rules are sufficient to control the mobile robot. Third, the proposed control scheme is a synthesized design which utilizes both heuristic knowledge and the sampled input–output data pairs. An implementation in real-time on an omnidirectional mobile robot validates the effectiveness of the proposed control scheme.

Navigation technology has an important role in designing intelligent vehicles and advanced robots. To have a continuous navigation solution that does not suffer from interruption, GPS (Global Positioning System) data is merged with relative positioning techniques such as inertial navigation system (INS) or odometry (Odm). To accomplish the reliability and integrity desired, it is therefore necessary to take into account physical capabilities and limitations of each sensor during navigation. A fuzzy switcher controller (FSC) is well suited for this task. FSC is an Expert rule-based method for choosing the best fusion from multiple redundant integration methodologies (GPS/INS, GPS/Odometry, Odometry/INS or GPS/INS/Odometry) based on navigation conditions and accuracy of the navigation systems.

International audience; This study presents the conception, simulation, realisation and characterisation of a patch antenna made of a composite based on polyaniline (PANI) and multiwall carbon nanotubes (MWCNTs). The antenna is designed to operate at the frequency of 4.5 GHz; the dielectric substrate used is Rogers RT/Duroid® 5870 which has a dielectric permittivity of 2.33 and a loss tangent of 0.0012. The conductive polymer (PANI/MWCNTs) fabricated has a conductivity of 4500 S/m. The performance of the proposed antenna is investigated as a function of the thickness of the conductive polymer. The experimental results show an antenna gain of 5.18 dB for a PANI/MWCNTs thickness of 110 μm. The results obtained suggest that this kind of conductive polymers are good candidates for future applications based on organic electronics.

International audience; In this paper, a fully organic dual-band antenna is presented. It consists of a coplanar waveguide coupled to an elliptical monopole antenna designed on a kapton substrate. This antenna is fabricated from a process, based on the use of a conductive polymer (Polyaniline) doped with multiwall carbon nanotubes, that has been optimized for this application. The flexibility of both, kapton substrate and doped conductive polymer, gives the antenna the ability to be freely crumpled paving the way to body-worn high data rate communications at microwave frequencies. Applications in wireless networks can also be addressed by using this kind of antennas. In this study, a comparison between the performance of an antenna under bending conditions (using a 3D support) and its uncrumpled version is presented. We evaluate the crumpling effect on the resonant frequency, the bandwidth and the radiation patterns. A good agreement is observed between measurements and simulations data, even when the antenna is crumpled.

In this paper, we treat the problem of trajectory planning of an unmanned ground vehicle evolving on an uneven terrain. In such environment, the role of the suspension system cannot be neglected and a vehicle vertical model has to be taken into account. In the present work, we present three reduced models with different level of complexity. These models make possible to handle the constraints inherent to stability, embedded equipment safety and suspension mechanical integrity. An optimization problem is also formulated in order to define the optimal speed profile for a safety behaviour of the mobile robot.

International audience; These last years, a lot of combination rules emerged in order to model the situations of belief fusion. These rules can be classified in two different classes. However, these rules do not differentiate between focal elements in the combination step which produce counterintuitive results in some situations. Motivated by this observation, we propose a new combination rule which hybrids the strategies of these two classes. Our rule is two-step operator where the averaging step comes first, and then the conflict redistribution step. Experimental studies are conducted on a real smart home dataset to show the accuracy of our rule in ubiquitous-assisted living situation.

International audience; The elastic modulus of thin films can be directly determined by instrumented indentation when the indenter penetration does not exceed a fraction of the film thickness, depending on the mechanical properties of both film and substrate. When it is not possible, application of models for separating the contribution of the substrate is necessary. In this work, the robustness of several models is analyzed in the case of the elastic modulus determination of a porous aluminium oxide film produced by anodization of an aluminium alloy. Instrumented indentation tests employing a Berkovich indenter were performed at a nanometric scale, which allowed a direct determination of the film elastic modulus, whose value was found to be approximately 11 GPa. However, at a micrometric scale the elastic modulus tends toward the value corresponding to the substrate, of approximately 73 GPa. The objective of the present work is to apply different models for testing their consistency over the complete set of indentation data obtained from both classical tests in microindentation and the continuous stiffness measurement mode in nanoindentation. This approach shows the continuity between the two scales of measurement thus allowing a better representation of the elastic modulus variation between two limits corresponding to the substrate and film elastic moduli. Gao's function proved to be the best to represent the elastic modulus variation.

This paper describes geometric and kinematic modelling steps of a class of an hybrid hyper-redundant robot (HHRR). The main problem of such complex manipulator robot structures is the synthesis of an appropriate control of n number of degrees of freedom (DOF). Thus, it is important at the design step, to develop geometric and kinematic models allowing to reconstruct the kinematical behavior of n concatenated modules. The studied structure is considered as modular with multiple DOF and is built by connecting in serial many parallel modules. The coordinate frame distribution is based on space curve differential geometry. The inverse Geometric and kinematic models are calculated analytically for a n-DOF of HHRR manipulator while the final application is applied to the case of a 3-modules robot (18-DOF).

In this article we address the problem of mobile robot formation control. Indeed, the most work, in this domain, have studied extensively classical control for keeping a formation of mobile robots. In this work, we design an FLC (Fuzzy logic Controller) controller for separation and bearing control (SBC). Indeed, the leader mobile robot is controlled to follow an arbitrary reference path, and the follower mobile robot use the FSBC (Fuzzy Separation and Bearing Control) to keep constant relative distance and constant angle to the leader robot. The efficiency and simplicity of this control law has been proven by simulation on different situation., {"references": ["", "Kar-Han Tan , M.A.Lewis, \u00d4\u00c7\u00ff-Virtual structures for high precision cooperative control--, technical report, Computer Science Department, University of California, Los Angles, 1997.", "W. Ren, R. W. Beard, \"A Decentralized scheme for spacecraft formation flying via the virtual structure approach\", AIAA Journal of Guidance, Control, & Dynamics, Revised Submission, June 2003.", "M. Egerstedt, K. Hu \u00d4\u00c7\u00ff-Formation constrained multi-agent control--, proceedings of 2001 IEEE International Conference on Robotics and Automation, pp .3961-3966, Seoul, Korea, May 21-26, 2001.", "J.M. Esposito, V. Kumar, \u00d4\u00c7\u00ff-A formalism for parallel composition of reactive and deliberative control objectives for mobile robots--, technical report, Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, 2000.", "H.Yamgachi, \u00d4\u00c7\u00ff-A Cooperative Hunting Behavior by Mobile Robot Troops--, ICRA-98 pp.3204-3209, Leuven Belgium, May 1998", "K. Sugihara and I. Suzuki, \"Distributed algorithms for formation of geometric patterns with many mobile robots\", J. Robot. Syst., Vol. 9, pp.777-790, 2001.", "Jose Sanchez and Rafael Fierro, \u00d4\u00c7\u00ff-Sliding mode control for robot formations--, Proc. IEEE Int. Symposium on Intelligent Control, Oct. 2003, pp.438-443.", "Xiaohai Li, Jizong Xiao, Zijun Cai, \u00d4\u00c7\u00ff-Backstepping based multiple mobile robots formation control--, 2005 IEEE/RSJ International Conference on Intelligent Robots and Systems, pp.1313-1318.", "A. Luca, G. Oriolo and M. Vendittelli, ÔÇÿ-Control of wheeled mobile robots: An experimental overview--, in RAMSETE - Articulated and Mobile Robotics for Services and Technologies, S. Nicosia, B. Siciliano, A. Bicchi and P. Valigi, Eds. Springer-Verlag, 2001. [10] G. Oriolo, A. Luca and M. Vandittelli, ÔÇÿ-WMR control via dynamic feedback linearization: design, implementation, and experimental v validation--, IEEE Transactions on Control Systems Technology, vol. 10, no. 6, pp. 835-852, 2002. [11] G. Klan\u2500ìar, D Matko, S. Bla\u017ei\u2500ì, ÔÇÿ-Mobile robot control on a reference path--, Proceedings of the 13th Mediterranean Conference on Control and Automation Limassol, Cyprus, June 27-29, 2005, pp 1343-1348 [12] Y. Kanayama, Y. Kimura, F. Miyazaki, and T. Noguchi, “A stable tracking control scheme for an autonomous mobile robot," in Proceedings IEEE International Conference on Robotics and Automation, 1990, pp. 384-389. [13] S. G. Tzafestas and G. G. Rigatos, “A simple robust sliding-mode fuzzy logic controller of the diagonal type," J. Intelligent Robotic Systems, vol. 26, pp. 353-388, 1999. [14] Okyay Kaynak, Kemalettin Erbatur, and Meliksah Ertugrul, ÔÇÿ-The fusion of computationally intelligent methodologies and sliding-mode controlsurvey-- IEEE Transactions on Industrial Electronics, Vol. 48, No. 1, February 2001 pp. 4-17. [15] T.-H. S. Li and M.-Y. Shieh, “Switching-type fuzzy sliding mode control of a cart-pole system," Mechatronics, vol. 10, pp. 91-109, 2000."]}