共查询到20条相似文献,搜索用时 437 毫秒
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弹簧摆内共振现象的实验研究 总被引:1,自引:1,他引:0
用视频摄像和计算机技术从实验上研究了弹簧摆的内共振现象。从系统的势能出发,讨论了弹簧摆的运动规律。通过实时记录摆球的位置,得了不同初始条件下,弹簧摆振动的位移曲线、能量曲线和摆球运动的轨迹。实验结果展示了理论与实验的一致性。 相似文献
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弹簧摆的内共振特性分析 总被引:2,自引:0,他引:2
首先提出了一种弹簧摆模型,通过谐波平衡法对弹簧摆的内共振现象进行了解析处理,得到了弹簧摆内共振条件以及X、Z两模态能量之间的转换关系.再利用数值模拟得到弹簧摆内共振时的时序图、相图、轨迹图、能量图以及内共振耦合区域图等,分析表明,解析和数值模拟的结果与实验结果吻合一致. 相似文献
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求解弹簧耦合摆的简正频率是理论力学中一道非常经典的题目,用分析力学的角度研究该题是一种重要的方法.目前对弹簧摆的研究多针对两单摆间的距离恰好等于弹簧原长;而当距离略大于或小于弹簧原长时,平衡状态下单摆摆线不再处于竖直状态,由于涉及不同的小角度近似,系统动能和势能的表示都变得更为复杂.本文探究了弹簧耦合摆系统的简正频率与系统静止时摆线偏移竖直方向角度的关系,利用MATLAB计算对比了是否使用小角度近似的运动过程,得到了近似解的适用情况.最后,在不考虑小角度的情况下,计算了拍频与弹簧固有频率、单摆固有频率和单摆平衡状态下偏移角度的关系. 相似文献
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Ugeda MM Fernández-Torre D Brihuega I Pou P Martínez-Galera AJ Pérez R Gómez-Rodríguez JM 《Physical review letters》2011,107(11):116803
Understanding the coupling of graphene with its local environment is critical to be able to integrate it in tomorrow's electronic devices. Here we show how the presence of a metallic substrate affects the properties of an atomically tailored graphene layer. We have deliberately introduced single carbon vacancies on a graphene monolayer grown on a Pt(111) surface and investigated its impact in the electronic, structural, and magnetic properties of the graphene layer. Our low temperature scanning tunneling microscopy studies, complemented by density functional theory, show the existence of a broad electronic resonance above the Fermi energy associated with the vacancies. Vacancy sites become reactive leading to an increase of the coupling between the graphene layer and the metal substrate at these points; this gives rise to a rapid decay of the localized state and the quenching of the magnetic moment associated with carbon vacancies in freestanding graphene layers. 相似文献
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A. H. Taub 《General Relativity and Gravitation》1979,10(12):1009-1009
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In this note we use some of the results of [3] to derive a general duality theorem for the cohomologies of foliated structures on a manifold. The result is applied to the special case of a symplectic manifold M on which the foliation is given by a complex polarization F in the sense of geometric quantization. We obtain, for example, a rigorous proof of the fact that for a smooth function ƒ on M whose Hamiltonian vector field leaves F invariant, the spectrum of the corresponding prequantization operator v(ƒ) coincides with the spectrum of its transpose, under the above duality. This latter result was obtained by Simms in [12] under certain hypotheses. Proofs of the validity of those hypotheses are now available in the literature; cf. [3] and [7]. 相似文献
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Valfells A. Verboncoeur J.P. Lau Y.Y. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2000,28(3):529-536
Analyzes the effects of space charge shielding on the steady state of a multipactor discharge on a dielectric. Analytic methods are used to obtain an exact function for the potential in the discharge, assuming a Maxwellian distribution of emitted electrons. An equation for the amount of power deposited on the dielectric by the multipactoring electrons, for a given saturation level, is given. A simple method for obtaining the saturation level, for a given material, is obtained 相似文献
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We study the relation between the centro-affine geometry of star-shaped planar curves and the projective geometry of parametrized maps into RP1. We show that projectivization induces a map between differential invariants and a bi-Poisson map between Hamiltonian structures. We also show that a Hamiltonian evolution equation for closed star-shaped planar curves, discovered by Pinkall, has the Schwarzian KdV equation as its projectivization. (For both flows, the curvature evolves by the KdV equation.) Using algebro-geometric methods and the relation of group-based moving frames to AKNS-type representations, we construct examples of closed solutions of Pinkall’s flow associated with periodic finite-gap KdV potentials. 相似文献
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《Surface science》1986,171(1):103-110
Cl2 layers adsorbed on Grafoil have been investigated by X-ray diffraction between 78 and 285 K. Mono- and submonolayers crystallize in a parallelogram lauttce, incommensurate with the (001) graphite surfaces, the molecules oriented almost perpendicular to the surface. The structure is closely related to that of the (001) planes of three-dimensional solid chlorine. For coverages above the monolayer completion bulk crystalization sets in. 相似文献
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Kopeikin SM 《Physical review letters》2007,98(22):229001; discussion 229002