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Anne-Laure Afchain 《Comptes Rendus Mathematique》2004,339(2):137-140
In this Note, we model an industrial system by a semi-Markov process where failure and repair phenomena are in mutual competition. A non-parametric estimation method for system component lifetime and repair time distributions and for associated hazard rate functions is proposed. The lifetime and repair time empirical distributions are reduced to two Kaplan–Meier estimators. A numerical example from an industrial system with three components and one repair man modeled by a birth and death process is provided to illustrate the previous results. To cite this article: A.-L. Afchain, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献
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Efficient preparation of 3-aryl-1H-pyrazoles by reaction of 1-protected-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazoles with (het)aryl halides is described. The choice of THP protecting group is discussed. 相似文献
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Resonant grating filters are promising components for free-space narrowband filtering. Unfortunately, due to their weak angular tolerance, their performances are strongly deteriorated when they are illuminated with a standard collimated beam. Yet this problem can be overcome by resorting to a complex periodic pattern known as the doubly periodic grating [Lemarchand et al., Opt. Lett.23, 1149 (1998)]. We report what we believe to be the first experimental fabrication and characterization of a bidimensional doubly periodic grating filter. We obtained a 0.5 nm bandpass polarization independent reflection filter for telecom wavelengths (1520-1570 nm) that presents a transmittivity minimum of 18% with a standard incident collimated beam. 相似文献
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Catherine Bessada Aydar Rakhmatullin Anne-Laure Rollet Didier Zanghi 《Journal of fluorine chemistry》2009,130(1):45-52
In situ high temperature nuclear magnetic resonance in molten fluoride mixtures gives some structural picture of the complexes existing in the melt, i.e. of their nature and relative proportion. Thanks to the development of a laser heating system associated with a close crucible in boron nitride, we can describe experimentally the evolution of these complexes from the anions and the cations point of view. By 19F NMR, we have shown the existence of three kinds of fluorine atoms depending on the composition: free fluorine like in pure LiF (non-bonded), bridging fluorine in melts rich in LnF3 in addition with terminal fluorine singly bonded to one rare earth. Data obtained by NMR spectroscopy are also combined with EXAFS measurements, again thanks to a specific development of the sample holder adapted with molten fluorides and high temperature. This study is a part of our systematic investigation of the different Alk-LnF3 systems by NMR and EXAFS spectroscopy. 相似文献
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We consider the model of the one-dimensional cookie random walk when the initial cookie distribution is spatially uniform
and the number of cookies per site is finite. We give a criterion to decide whether the limiting speed of the walk is non-zero.
In particular, we show that a positive speed may be obtained for just three cookies per site. We also prove a result on the
continuity of the speed with respect to the initial cookie distribution.
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This work is focused on studying the grafting of gold nanoparticles (Np) on a cystamine self-assembled monolayer on gold, in order to build sensitive immunosensors. The synthesis and deposition of gold nanoparticles, 13 and 55 nm sizes, were characterised by combining Polarisation Modulation Infrared Reflection-Absorption Spectroscopy (PM-IRRAS), X-ray Photoelectron Spectroscopy (XPS) Surface Enhanced Raman Scattering (SERS), and Atomic Force Microscopy (AFM) which all indicated the formation of a dispersed layer of nanoparticles. This observation is explained by the compromise between the high reactivity of amine-terminated layers towards gold, and interparticle repulsions. Nps were then functionalised with antibody probes, and the recognition by an anti-rIgG was assayed both on planar and Np gold surfaces.The important result is that nanoparticles of 55 nm are preferable for the following reasons: they enable to build a denser and well dispersed layer and they increase both the number of receptors (IgGs) and their accessibility. Beside these geometric improvements, a net enhancement of the Raman signal was observed on the 55 nm nanoparticle layer, making this new platform promising for optical detection based biosensors. 相似文献
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Deschamps M Fayon F Cadars S Rollet AL Massiot D 《Physical chemistry chemical physics : PCCP》2011,13(17):8024-8030
Measuring internuclear distances through dipolar interaction is a major challenge for solid-state nuclear magnetic resonance (NMR) spectroscopy. Obtaining reliable interatomic distances provides an access to the local structure in ordered or disordered solids. We show that at magic angle spinning (MAS) frequencies larger than ca. 50 kHz, some of the three-spin terms of the homogeneous homonuclear dipolar Hamiltonian can be used to promote the creation of double-quantum coherences between neighbouring (1)H or (19)F spins without using dipolar recoupling pulse sequences in the Dipolar Homonuclear Homogeneous Hamiltonian (DH(3)) double-quantum/single-quantum correlation experiment. This makes it possible to probe inter-nuclear spatial proximity with limited risk of probe or sample damage from radio-frequency (RF) irradiation, and is fully appropriate for fast repetition rate offering sensitivity gains in favourable cases. Experimental demonstrations are supported by multi-spin numerical simulations, which points to new possibilities for the characterization of spin-system geometries. 相似文献