1,930 research outputs found

    An Application Case Study on Multi-sensor Data fusion System for Intelligent Process Monitoring

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    AbstractMulti-sensor data fusion is a technology to enable combining information from several sources in order to form a unified picture. Focusing on the indirect method, an attempt was made to build up a multi-sensor data fusion system to monitor the condition of grinding wheels with force signals and the acoustic emission (AE) signals. An artificial immune algorithm based multi-signals processing method was presented in this paper. The intelligent monitoring system is capable of incremental supervised learning of grinding conditions and quickly pattern recognition, and can continually improve the monitoring precision. The application case indicates that the accuracy of condition identification is about 87%, and able to meet the industrial need on the whole

    Neutron Scattering Measurements of Spatially Anisotropic Magnetic Exchange Interactions in Semiconducting K0.85Fe1.54Se2 (TN=280 K)

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    We use neutron scattering to study the spin excitations associated with the stripe antiferromagnetic (AFM) order in semiconducting K0.85_{0.85}Fe1.54_{1.54}Se2_2 (TNT_N=280280 K). We show that the spin wave spectra can be accurately described by an effective Heisenberg Hamiltonian with highly anisotropic in-plane couplings at TT= 55 K. At high temperature (TT= 300300 K) above TNT_N, short range magnetic correlation with anisotropic correlation lengths are observed. Our results suggest that, despite the dramatic difference in the Fermi surface topology, the in-plane anisotropic magnetic couplings are a fundamental property of the iron based compounds; this implies that their antiferromagnetism may originate from local strong correlation effects rather than weak coupling Fermi surface nesting.Comment: 5 pages, 4 figure

    Classical-driving-assisted quantum synchronization in non-Markovian environments

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    We study the quantum phase synchronization of a driven two-level system (TLS) coupled to a structured environment and demonstrate that quantum synchronization can be enhanced by the classical driving field. We use the Husimi QQ-function to characterize the phase preference and find the in-phase and anti-phase locking phenomenon in the phase diagram. Remarkably, we show that the classical driving enables a TLS to reach stable anti-phase locking in the Markovian regime. However, we find that the synergistic action of classical driving and non-Markovian effects significantly enhances the in-phase locking. By introducing the SS-function and its maximal value to quantify the strength of synchronization and sketch the synchronization regions, we observe the typical signatures of the hollowed Arnold tongue in the parameter regions of synchronization. In the hollowed Arnold tongue, the synchronization regions exist both inside and outside the tongue while unsynchronized regions only lie on the boundary line. We also provide an intuitive interpretation of the above results by using the quasimode theory.Comment: 10 pages, 5 figures, revised versio

    Non-Thermal X-ray Properties of Rotation Powered Pulsars and Their Wind Nebulae

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    We present a statistical study of the non-thermal X-ray emission of 27 young rotation powered pulsars (RPPs) and 24 pulsar wind nebulae (PWNe) by using the Chandra and the XMM-Newton observations, which with the high spatial resolutions enable us to spatially resolve pulsars from their surrounding PWNe. We obtain the X-ray luminosities and spectra separately for RPPs and PWNe, and then investigate their distribution and relation to each other as well as the relation with the pulsar rotational parameters. In the pair-correlation analysis we find that: (1) the X-ray (2-10 keV) luminosities of both pulsar and PWN (L_{psr} and L_{pwn}) display a strong correlation with pulsar spin down power Edot and characteristic age, and the scalings resulting from a simple linear fit to the data are L_{psr} \propto Edot^{0.92 \pm 0.04} and L_{pwn} \propto Edot^{1.45 \pm 0.08} (68% confidence level), respectively, however, both the fits are not statistically acceptable; (2) L_{psr} also shows a possible weak correlation with pulsar period P and period derivative Pdot, whereas L_{pwn} manifests a similar weak correlation with Pdot only; (3) The PWN photon index Gamma_{pwn} is positively correlated with L_{pwn} and L_{pwn}/Edot. We also found that the PWN X-ray luminosity is typically 1 to 10 times larger than that from the underlying pulsar, and the PWN photon indices span a range of ~1.5 to ~2. The statistic study of PWN spectral properties supports the particle wind model in which the X-ray emitting electrons are accelerated by the termination shock of the wind.Comment: 15 pages, 9 figures, 3 Tables, ApJ accepted version. Substantial revision, especially luminosity uncertainty taken into accounted and one fig added. Main conclusions unchange

    Steroidal and pregnane glycosides from Ypsilandra thibetica

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    The whole plants of Ypsilandra thibetica have been analyzed as part of a systematic study on saponin constituents of medicinal plants. This has resulted in the isolation of two new bisdesmosidic furostanol saponins, named ypsilandroside P (1) and ypsilandroside Q (2), and one new pregnane glycoside, named ypsilandroside R (3), together with nine known steroidal glycosides. Their structures were elucidated on the basis of extensive spectroscopic analysis, including that of 2D NMR data, and the results of acidic hydrolysis. Ypsilandroside P (1) was cytotoxicity against two human tumor cell lines. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available for this article at 10.1007/s13659-011-0039-z and is accessible for authorized users
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