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71.
旋转不变振幅位相合成圆谐滤波器 总被引:1,自引:0,他引:1
提出了振幅位相合成圆谐滤器用于旋转不变模式识别,该滤波器的振幅是圆谐滤波器的振幅谱加偏移量后的逆函数,位相是圆谐滤波器的位相谱。计算机模拟实验证明,与传统的圆谐滤波器和纯位相圆谐滤波器相比,振幅位相合成圆谐滤波器具有更好的识别能力,能产生更尖锐的相关峰和更大的输出信噪比。 相似文献
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Acceleration waves propagating in isotropic solids at finite temperatures are studied by applying the method of singular surfaces to a new continuum model derived statistical-mechanically from a three-dimensional lattice model. The continuum model explicitly takes into account the microscopic thermal vibrations of the constituent atoms as one of the field variables. The propagation speeds and the ratios of mechanical and thermal amplitudes for both longitudinal and transverse waves are consistently determined. The differential equations that govern the time variation of the amplitudes of the waves are also derived. The analytical results, which are valid over a wide temperature range that includes the melting point, are evaluated numerically for several materials, and their physical implications are discussed. One of the findings to be emphasized is that of the singularities of the characteristic quantities at the melting point.Received: 13 March 2003, Accepted: 20 June 2003PACS:
62.30. + d, 65.40.-bM. Sugiyama: Correspondence to
Dedicated to Prof. Ingo Müller on the occasion of his 65th birthday. 相似文献
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This paper describes measurements of a vibrating object with rough surface by the time-averaged method of holography using a newly designed optically addressed liquid crystal spatial light modulator with a resolution of 102 lp/mm and a diffraction efficiency of 16%. An object vibrating faster than several tens of Hz could be visualized. The pattern obtained by the method provides the locus of vibrating nodes. The advantage of this method is that a high contrast pattern of a vibrating object can be imaged in near-real-time, although the sensitivity of vibration is decreased. 相似文献
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Summary. We derive a set of asymptotically exact coupled amplitude-streaming flow ({CASF}) equations governing the evolution of weakly nonlinear nearly inviscid multimode Faraday waves and the associated
streaming flow in finite geometries. The streaming flow is found to play a particularly important role near mode interactions.
Such interactions come about either through a suitable choice of parameters or through breaking of degeneracy among modes
related by symmetry. An example of the first case is provided by the interaction of two nonaxisymmetric modes in a circular
container with different azimuthal wavenumbers. The second case arises when the shape of the container is changed from square
to slightly rectangular, or from circular to slightly noncircular but with a plane of symmetry. The generation of streaming
flow in each of these cases is discussed in detail and the properties of the resulting CASF equations are described. A preliminary
analysis suggests that these equations can resolve discrepancies between existing theory and experimental results in the first
two of the above cases. 相似文献
79.
In the Shubnikov–de Haas oscillation spectrum of doped InAs/AlSb structures, high-amplitude peaks are established at combination
frequencies. It is demonstrated that they are caused by a significant contribution of intersubband scattering to the processes
of electron-electron interaction.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 32–38, December, 2008. 相似文献
80.
交流电桥的示波器测量方法 总被引:1,自引:0,他引:1
传统的交流电桥教学采用毫伏表,本文给出了一种采用示波器的电桥教学与测量方法,能更直观展示电桥的幅、相关系,有更好的教学效果。 相似文献