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An enthalpy-based lattice Boltzmann formulation for unsteady convection-diffusion heat transfer problems in heterogeneous media
No full textInternational audienceIn this paper, we propose a direct extension of a previous work presented by Hamila et al. [1 R. Hamila, M. Nouri, S. Ben Nasrallah, and P. Perré, Int. J. Heat Mass Transfer, vol. 100, pp. 728–736, 2016.[CrossRef], [Web of Science ®], [Google Scholar]] dealing with the simulation of conjugate heat transfer by conduction in heterogeneous media. In [1 R. Hamila, M. Nouri, S. Ben Nasrallah, and P. Perré, Int. J. Heat Mass Transfer, vol. 100, pp. 728–736, 2016.[CrossRef], [Web of Science ®], [Google Scholar]] a novel enthalpy-based lattice Boltzmann (LB) formulation was successfully simulated in several conjugate heat transfer problems by conduction. We propose testing this enthalpic LB formulation in solving convection-diffusion heat transfer problems in heterogeneous media. The main idea of this formulation is to introduce an extra source term, avoiding any additional treatment of the distribution functions at the interface. Continuity of temperature and normal heat flux at the interface is satisfied automatically. The performance of the present method is successfully validated by comparison to the control volume methods (CVMs) solutions of several heat convection-diffusion problems in heterogeneous media
Actes des Rencontres Doctorales de la 28ième conférence francophone sur l’Interaction Homme-Machine
No full textInternational audiencePour sa 28ème édition, la conférence francophone sur l'Interaction Homme-Machine (IHM) vient en Suisse pour la première fois, à Fribourg. Cette édition marque aussi un événement important de l’AFIHM : ses vingt ans ! La conférence, se tenant du 25 au 28 octobre 2016, est présidée par Denis Lalanne (Human-IST, Université de Fribourg) et Laurence Nigay (Université Grenoble Alpes). IHM 2016 est un lieu d'échanges entre les différents acteurs de la recherche en Interaction Homme-Machine. Nos ambitions avec cette édition d'IHM étaient :•D’encourager la participation de jeunes chercheurs•D’augmenter les liens entre laboratoires et entreprises, notamment locales, autour des problématiques d’IHM•De favoriser la pluridisciplinarité (informatique, psychologie, sociologie)•De promouvoir le domaine de l’Interaction Homme-Machine en Suisse et de tisser un lien fort avec le reste de la communauté en Interaction Homme-Machine•De fêter les vingt ans de l’AFIH
Robust stabilization of delayed neural fields with partial measurement and actuation
No full textExtended preprint of the eponym paper to appear in AutomaticaNeural fields are integro-differential equations describing spatiotemporal activity of neuronal populations. When considering finite propagation speed of action potentials, neural fields are affected by space-dependent delays. In this paper, we provide conditions under which such dynamics can be robustly stabilized by a proportional feedback acting only on a portion of the neuronal population and by relying on measurements of this subpopulation only. To that aim, in line with recent works, we extend the concept of input-to-state stability (ISS) to generic nonlinear delayed spatiotemporal dynamics and provide a small-gain result relying on Lyapunov-Krasovskii functionals. Exploiting the robustness properties induced by ISS, we provide conditions under which a uniform control signal can be used for the whole controlled subpopulation and we analyze the robustness of the proposed strategy to measurement and actuation delays. These theoretical findings are compared to simulation results in a model of pathological oscillations generation in Parkinson's disease
Lens Antenna for Wide Angle Beam Scanning at 79 GHz for Automotive Short Range Radar Applications
No full textInternational audienceThis communication presents the design and experimental verification of a substrate integrated waveguide fed lens antenna for 79 GHz automotive radar applications. The proposed integrated lens antenna consists of a six layer cylindrical Luneburg lens illuminated by 17 source elements of substrate integrated waveguide fed by a planar log periodic dipole antenna array. The Luneburg lens is developed by using a unique foam material AirexR82 (r = 1.12), which is drilled and pressed to achieve the different dielectric constant needed to follow the index law inside the lens. The return loss and the radiation characteristics of the proposed integrated lens antenna are investigated and validated by measurements. A good agreement between the measured and simulated results is observed. The measured results confirm the beam scanning capability of the proposed integrated lens antenna for a wide scan angle of ±85° in azimuth plane having a maximum antenna gain of 15 dBi at 82.5 GHz and gain drop of less than 2.75 dB for the edge feeds. The estimated radiation efficiency of the antenna is found to be 67% at 82.5 GHz. © 1963-2012 IEEE
Computing generator in cyclotomic integer rings: A subfield algorithm for the Principal Ideal Problem in Ll∆Kl(1/2) and application to cryptanalysis of a FHE scheme
No full textInternational audienceThe Principal Ideal Problem (resp. Short Principal Ideal Problem), shorten as PIP (resp. SPIP), consists in finding a generator (resp. short generator) of a principal ideal in the ring of integers of a number field. Several lattice-based cryptosystems rely on the presumed hardness of these two problems. In practice, most of them do not use an arbitrary number field but a power-of-two cyclotomic field. The Smart and Vercauteren fully homomorphic encryption scheme and the multilinear map of Garg, Gentry, and Halevi epitomize this common restriction. Recently, Cramer, Ducas, Peikert, and Regev showed that solving the SPIP in such cyclotomic rings boiled down to solving the PIP. In this paper, we present a heuristic algorithm that solves the PIP in prime-power cyclotomic fields in subexponential time L(1/2), where ∆ K denotes the discriminant of the number field. This is achieved by descending to its totally real subfield. The implementation of our algorithm allows to recover in practice the secret key of the Smart and Vercauteren scheme, for the smallest proposed parameters (in dimension 256)
Process development for novel low temperature plasma synthesized nanocarbon–based biosensors
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Scientific workflows for computational reproducibility in the life sciences: Status, challenges and opportunities
No full textInternational audienceWith the development of new experimental technologies, biologists are faced with an avalanche of data to be computationally analyzed for scientific advancements and discoveries to emerge. Faced with the complexity of analysis pipelines, the large number of computational tools, and the enormous amount of data to manage, there is compelling evidence that many if not most scientific discoveries will not stand the test of time: increasing the reproducibility of computed results is of paramount importance. The objective we set out in this paper is to place scientific workflows in the context of reproducibility. To do so, we define several kinds of repro-ducibility that can be reached when scientific workflows are used to perform experiments. We characterize and define the criteria that need to be catered for by reproducibility-friendly scientific workflow systems, and use such criteria to place several representative and widely used workflow systems and companion tools within such a framework. We also discuss the remaining challenges posed by reproducible scientific workflows in the life sciences. Our study was guided by three use cases from the life science domain involving in silico experiments
Gaussian framework for interference reduction in live recordings
No full textInternational audienceIn live multitrack recordings, each voice is usually captured by dedicated close microphones. Unfortunately, it is also captured in practice by other microphones intended for other sources, leading to so-called " interferences ". Reducing this interference is desirable because it opens new perspectives for the engineering of live recordings. Hence, it has been the topic of recent research in audio processing. In this paper, we show how a Gaussian probabilistic framework may be set up for obtaining good isolation of the target sources. Doing so, we extend several state-of-the art methods by fixing some heuristic parts of their algorithms. As we show in a perceptual evaluation on real-world multitrack live recordings, the resulting principled techniques yield improved quality
Sub-sampling of channels with time and frequency sparsity access
No full textInternational audienceThis paper shows that sub-sampling of signals canhelp in reducing the amount of data to be processed and storedwhen time and frequency sparsity is considered. The contextis the one of the Internet of Things (IoT) for which a hugequantity of users (i.e. objects) communicate with very few timeand frequency accesses. Taking advantage of the occupancytheory of probabilities, we propose a theoretical model for suchcommunications and we show that the sampling frequency o
Blind Modulation Classification for Cognitive Satellite in the Spectral Coexistence Context
No full textInternational audienceThe scarcity of the usable satellite spectrum has led to a need for advanced communication techniques. Among them, multi-satellite networks have been promoted for their ability to reuse the frequency bands in a more aggressive manner. This is made possible by sharing both the spectral and spatial degrees of freedom. Meanwhile, the concept of Cognitive Satellite (CS) was deeply investigated to make the best of these novel architectures. In this context, very few blind signal processing methods were proposed to tackle the co-channel interference issues entailed by such systems. Herein, we develop a novel low-complexity algorithm for blind Automatic Modulation Classification (AMC) and parameters estimation in the strongly interfering scenario. The proposed method rely on an Analytical study of the Mth-Power non-linear Transformation (AMPT) of the co-channel mixture. Theoretical analysis and extensive simulations show the effectiveness of the proposed method in various scenarios