2,859 research outputs found

    Field-induced negative differential spin lifetime in silicon

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    We show that the electric field-induced thermal asymmetry between the electron and lattice systems in pure silicon substantially impacts the identity of the dominant spin relaxation mechanism. Comparison of empirical results from long-distance spin transport devices with detailed Monte-Carlo simulations confirms a strong spin depolarization beyond what is expected from the standard Elliott-Yafet theory already at low temperatures. The enhanced spin-flip mechanism is attributed to phonon emission processes during which electrons are scattered between conduction band valleys that reside on different crystal axes. This leads to anomalous behavior, where (beyond a critical field) reduction of the transit time between spin-injector and spin-detector is accompanied by a counterintuitive reduction in spin polarization and an apparent negative spin lifetime

    Partitioning Clustering Based on Support Vector Ranking

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    Experimental analysis for the effect of dynamic capillarity on stress transformation in porous silicon

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    The evolution of real-time stress in porous silicon(PS) during drying is investigated using micro-Raman spectroscopy. The results show that the PS sample underwent non-negligible stress when immersed in liquid and suffered a stress impulsion during drying. Such nonlinear transformation and nonhomogeneneous distribution of stress are regarded as the coupling effects of several physical phenomena attributable to the intricate topological structure of PS. The effect of dynamic capillarity can induce microcracks and even collapse in PSstructures during manufacture and storage.This work is funded by the National Natural Science Foundation of China Contract Nos. 10732080 and 10502014

    RESEARCH ON VISUALIZATION TECHNOLOGY OF CYBERCITY 3D SCENE

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    3D visualization is a Key Technology in CyberCity. It has been applied in many fields. In this paper, we discussed and studied several key techniques of 3D visualization in CyberCity. These key techniques contain Oriented Object 3D Data Model, Advanced Modeling Techniques which contain Particle System and Billboard, 3D Scene Accelerate Rendering Techniques, Information Inquire techniques in 3D scene and so on. The 3D Scene Accelerate Rendering Techniques contain Object Culling, Back Face Culling and LOD (level of detail) technique. Based on these techniques, we designed and implemented an advanced 3D Rendering Engine. At the end of paper, we give some results created by the 3D Rendering Engine. The results show that the 3D engine can render highly reality 3D scene and user can obtain highly immersion by rambling in 3D scene and inquiring information based on database.

    The C∞-convergence of SG circle patterns to the Riemann mapping

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    AbstractThurston conjectured that the Riemann mapping function from a simply connected region onto the unit disk can be approximated by regular hexagonal packings. Schramm introduced circle patterns with combinatorics of the square grid (SG) and showed that SG circle patterns converge to meromorphic functions. He and Schramm proved that hexagonal disk packings converge in C∞ to the Riemann mapping. In this paper we show a similar C∞-convergence for SG circle patterns
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