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991.
Bart De Geeter Olivier Nys Jean-Paul Bardyn 《Analog Integrated Circuits and Signal Processing》1997,14(3):179-191
A pressure sensor interface circuit featuring micropower consumptionis presented. The sensitivity to leakage currents has been reduced, allowingoperation at high temperature. Special attention has been paid to minimisealiasing in the sampled interface. An optimal combination of contradictoryrequirements on power consumption, temperature range and sampling speed wasobtained by a very careful system design and optimisation. The circuitconverts a sensor capacitance variation of ±5pF into an 11 bit outputword at a 2Hz rate. This resolution is guaranteed in the –40°C to100°C temperature range. It may slowly decay above 100°C but ensuresat least 5 bit at 130°C. The power consumption at room temperature issmaller than 2µA from a 2.4V to 4V battery. 相似文献
992.
Tathamay Basu Clarisse Bloyet Flicien Beaubras Vincent Caignaert Olivier Perez Jean‐Michel Rueff Alain Pautrat Bernard Raveau Jean‐Franois Lohier Paul‐Alain Jaffrs Hlne Couthon Guillaume Rogez Grgory Taupier Honorat Dorkenoo 《Advanced functional materials》2019,29(33)
Very few hybrid organic–inorganic framework (HOIF) exhibit direct coupling between spins and dipoles and are also restricted to a particular COOH‐based system. It is shown how one can design a hybrid system to obtain such coupling based on the rational design of the organic ligands. The layered phosphonate, MnO3PC6H5?H2O, consisting of perovskite layers stacked with organic phenyl layers, is used as a starting potential candidate. To introduce dipole moment, a closely related metal phosphonate, MnO3PC6H4‐m‐Br?H2O is designed. For this purpose, this phosphonate is prepared from 3‐bromophenylphosphonic acid that features one electronegative bromine atom directly attached on the aromatic ring in the meta position, lowering the symmetry of precursor itself. Thus, bromobenzene moieties in MnO3PC6H4‐m‐Br?H2O induce a finite dipole moment. This new designed compound exhibits complex magnetism, as observed in layered alkyl chains MnO3PCnH2n+1?H2O materials, namely, 2D magnetic ordering ≈20 K followed by weak ferromagnetic ordering below 12 K (T1) with a magnetic field (H)‐induced transition ≈25 kOe below T1. All these magnetic features are exactly captured in the T and H‐dependent dielectric constant, ε′(T) and ε′(H). This demonstrates direct magnetodielectric coupling in this designed hybrid and yields a new path to tune multiferroic ordering and magnetodielectric coupling. 相似文献
993.
Kybic J Clerc M Abboud T Faugeras O Keriven R Papadopoulo T 《IEEE transactions on medical imaging》2005,24(1):12-28
The forward electroencephalography (EEG) problem involves finding a potential V from the Poisson equation inverted Delta x (sigma inverted Delta V) f, in which f represents electrical sources in the brain, and sigma the conductivity of the head tissues. In the piecewise constant conductivity head model, this can be accomplished by the boundary element method (BEM) using a suitable integral formulation. Most previous work uses the same integral formulation, corresponding to a double-layer potential. In this paper we present a conceptual framework based on a well-known theorem (Theorem 1) that characterizes harmonic functions defined on the complement of a bounded smooth surface. This theorem says that such harmonic functions are completely defined by their values and those of their normal derivatives on this surface. It allows us to cast the previous BEM approaches in a unified setting and to develop two new approaches corresponding to different ways of exploiting the same theorem. Specifically, we first present a dual approach which involves a single-layer potential. Then, we propose a symmetric formulation, which combines single- and double-layer potentials, and which is new to the field of EEG, although it has been applied to other problems in electromagnetism. The three methods have been evaluated numerically using a spherical geometry with known analytical solution, and the symmetric formulation achieves a significantly higher accuracy than the alternative methods. Additionally, we present results with realistically shaped meshes. Beside providing a better understanding of the foundations of BEM methods, our approach appears to lead also to more efficient algorithms. 相似文献
994.
Laurent Rubaldo Alexandre Brunner Jocelyn Berthoz N. Péré-Laperne A. Kerlain P. Abraham D. Bauza G. Reimbold Olivier Gravrand 《Journal of Electronic Materials》2014,43(8):3065-3069
At high temperature, infra-red focal plane arrays are limited by their performance in operability, detectivity D * or noise equivalent temperature difference. Trap characterization and defect studies are necessary to better understand these limitations at high temperature. In this paper, we use deep level transient spectroscopy to study electrically active defects in mercury cadmium telluride n +/p diodes. The material investigated has a cut-off frequency (λ c) of 2.5 μm at 180 K and p doping performed with mercury vacancy. Trap energy signatures as well as capture cross-section measurements are detailed. A low temperature hole trap close to midgap is observed in the range 150–200 K with an activation energy around 0.18 ± 0.025 eV. A high temperature hole trap is also observed in the range 240–300 K with an activation energy of 0.68 ± 0.06 eV. A hole capture cross-section of 10?19 cm2 is obtained for both traps. The nature of the defects and their correlation with dark current are discussed. 相似文献
995.
Several sensitive applications deployed within wireless networks require group communications. A high level of security is often required in such applications, like military or public security applications. The most suitable solution to ensure security in these services is the deployment of a group key management protocol, adapted to the characteristics ofManets, especially to mobility of nodes. In this paper, we present theOmct (Optimized Multicast Cluster Tree) algorithm for dynamic clustering of multicast group, that takes into account both nodes localization and mobility, and optimizes the energy and bandwidth consumptions. Then, we show how we integrateOmct within our group key management protocolBalade, in a sequential multi-source model. The integration ofBalade andOmct allows an efficient and fast key distribution process, validated through simulations, by applying various models of mobility (individual mobility and group mobility). The impact of the mobility model on the performance and the behaviour of the group key management protocolBalade coupled withOmct, is also evaluated. 相似文献
996.
Accurate event-driven motion compensation in high-resolution PET incorporating scattered and random events 总被引:2,自引:0,他引:2
Rahmim A Dinelle K Cheng JC Shilov MA Segars WP Lidstone SC Blinder S Rousset OG Vajihollahi H Tsui BM Wong DF Sossi V 《IEEE transactions on medical imaging》2008,27(8):1018-1033
997.
Auzias G Colliot O Glaunès JA Perrot M Mangin JF Trouvé A Baillet S 《IEEE transactions on medical imaging》2011,30(6):1214-1227
The alignment and normalization of individual brain structures is a prerequisite for group-level analyses of structural and functional neuroimaging data. The techniques currently available are either based on volume and/or surface attributes, with limited insight regarding the consistent alignment of anatomical landmarks across individuals. This article details a global, geometric approach that performs the alignment of the exhaustive sulcal imprints (cortical folding patterns) across individuals. This DIffeomorphic Sulcal-based COrtical (DISCO) technique proceeds to the automatic extraction, identification and simplification of sulcal features from T1-weighted Magnetic Resonance Image (MRI) series. These features are then used as control measures for fully-3-D diffeomorphic deformations. Quantitative and qualitative evaluations show that DISCO correctly aligns the sulcal folds and gray and white matter volumes across individuals. The comparison with a recent, iconic diffeomorphic approach (DARTEL) highlights how the absence of explicit cortical landmarks may lead to the misalignment of cortical sulci. We also feature DISCO in the automatic design of an empirical sulcal template from group data. We also demonstrate how DISCO can efficiently be combined with an image-based deformation (DARTEL) to further improve the consistency and accuracy of alignment performances. Finally, we illustrate how the optimized alignment of cortical folds across subjects improves sensitivity in the detection of functional activations in a group-level analysis of neuroimaging data. 相似文献
998.
A quasi-one-dimensional CFD model for multistage turbomachines 总被引:1,自引:0,他引:1
The objective of this paper is to present a fast and reliable CFD model that is able to simulate stationary and transient operations of multistage compressors and turbines. This analysis tool is based on an adapted version of the Euler equations solved by a time-marching, finite-volume method. The Euler equations have been extended by including source terms expressing the blade-flow interactions. These source terms are determined using the ve- locity triangles and a row-by-row representation of the blading at mid-span. The losses and deviations undergone by the fluid across each blade row are supplied by correlations. The resulting flow solver is a performance pre- diction tool based only on the machine geometry, offering the possibility of exploring the entire characteristic map of a multistage compressor or turbine. Its efficiency in terms of CPU time makes it possible to couple it to an optimization algorithm or to a gas turbine performance tool. Different test-cases are presented for which the calculated characteristic maps are compared to experimental ones. 相似文献
999.
The ubiquity of IP associated with the acknowledgment of ATM as a key switching technology has motivated an increasing interest towards the design of a more efficient way of operating IP over ATM networks. This approach is known under the name Label Swapping. A few studies have addressed the primary issue of providing simultaneously quality of service and multicast. We propose a solution where we mix an RSVP architecture with one Label Swapping technique called IP Switching. We discuss problems that arise when using cut-through associated with an RSVP multicast model and propose an application for an IPv6 environment over an ATM switching hardware. 相似文献
1000.
Olivier Bardagot Pawe Kubik Tomasz Marszalek Pawel Veyre Asma Aicha Medjahed Martina Sandroni Benjamin Grvin Stphanie Pouget Tamara Nunes Domschke Alexandre Carella Serge Gambarelli Wojciech Pisula Renaud Demadrille 《Advanced functional materials》2020,30(21)
The impact of the chemical structure and molecular order on the charge transport properties of two donor–acceptor copolymers in their neutral and doped states is investigated. Both polymers comprise 3,7‐bis((E)‐7‐fluoro‐1‐(2‐octyl‐dodecyl)‐2‐oxoindolin‐3‐ylidene)‐3,7‐dihydrobenzo[1,2‐b:4,5‐b′]difuran‐2,6‐dione (FBDOPV) as electron‐accepting unit, copolymerized with 9,9‐dioctyl‐fluorene (P(FBDOPV‐F)) or with 3‐dodecyl‐2,2′‐bithiophene (P(FBDOPV‐2T‐C12)). These copolymers possess an amorphous and semi‐crystalline nature, respectively, and exhibit remarkable electron mobilities of 0.065 and 0.25 cm2 V–1 s–1 in field effect transistors. However, after chemical n‐doping with 4‐(1,3‐dimethyl‐2,3‐dihydro‐1H‐benzoimidazol‐2‐yl)phenyl)dimethylamine (N‐DMBI), electrical conductivities four orders of magnitude higher can be achieved for P(FBDOPV‐2T‐C12) (σ = 0.042 S cm?1). More charge‐transfer complexes are formed between P(FBDOPV‐F) and N‐DMBI, but the highly localized polaronic states poorly contribute to the charge transport. Doped P(FBDOPV‐2T‐C12) exhibits a negative Seebeck coefficient of –265 µV K?1 and a thermoelectric power factor (PF) of 0.30 µW m?1 K?2 at 303 K which increases to 0.72 µW m?1 K?2 at 388 K. The in‐plane thermal conductivity (κ|| = 0.53 W m?1 K?1) on the same micrometer‐thick solution‐processed film is measured, resulting in a figure of merit (ZT) of 5.0 × 10?4 at 388 K. The results provide important design guidelines to improve the doping efficiency and thermoelectric properties of n‐type organic semiconductors. 相似文献