共查询到20条相似文献,搜索用时 15 毫秒
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P. V. Artel’nyi A. L. Virovlyansky A. Yu. Kazarova P. I. Korotin L. Ya. Lyubavin A. V. Stulenkov 《Acoustical Physics》2018,64(2):175-185
The paper presents the results of processing measurement data on the spatiotemporal structures of sound fields in Lake Ladoga. Measurements were taken with an extended vertical receiver array. The aim of processing was to isolate the field components that were stable with respect to small variations in the waveguide parameters. Since a model of the medium is inevitably inaccurate, such components can be predicted with greater accuracy than the total field. In terms of the ray approach, a stable component is generated by a beam of rays propagating over close trajectories. The discussed experiment analyzed sound fields excited by a point source that emitted wideband pulses, as well as the fields of wave beams excited by the emitting vertical array at fixed frequencies. In both cases, the processing results showed that the isolated stable components, as expected, coincide substantially better with the prediction of theoretical calculation (by the wide angle parabolic equation method) than with the total wave field. 相似文献
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Acoustical Physics - The paper discusses representation of the wave field on a vertical array in an underwater sound channel as the superposition of components stable with respect to large-scale... 相似文献
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激光声遥感探测水下声信号技术,是比以往任何一种水声探测技术都先进的技术,但探测系统的灵敏度一直未曾分析。得出了在直接光强检测方式下表面微波的最小可探测幅度值,并且分析了最小可探测幅度值分别和探测高度、接收孔径的关系。在直接光强检测方式下,针对水下声场形成的表面微扰现象,通过建立探测系统的一维物理模型进行理论推算。直接光强检测方式下表面微波的最小可探测幅度值为0.424 4 mm,当表面微波幅度超过该值时,探测系统灵敏度完全满足对水下声场的实时监测要求。 相似文献
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空间衍射声波波前与压力场的计算机层析三维重建 总被引:2,自引:0,他引:2
应用脉冲载波电子散斑干涉(pulsedcarried-ESPI)与计算机层析技术(CT),实现了由高压电极放电激励所产生的瞬态传输声场在经过不同孔径模板衍射后波前与压力场的三维重建,给出了数值结果,并对噪声条件下的计算机层析重建进行了讨论。 相似文献
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Acoustical Physics - The characteristic features of acoustic wave propagation in orthotropic elastic topographic waveguides are investigated for waveguides in the form of extended cylindrical... 相似文献
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由于在水下爆炸冲击波的数值仿真研究中,水的状态方程、人工黏性系数和网格尺寸对数值计算结果影响很大,采用常规TNT炸药的水下爆炸为例,以冲击波的峰值压力和比冲量为衡量指标,研究了这3个主要影响因素对数值仿真结果的影响。首先,通过采用常用的5种水的状态方程进行系列仿真,给出了各种状态方程的适用范围;其次,讨论了人工黏性系数对计算结果的影响,并给出了一次与二次人工黏性系数的建议取值范围;最后,通过对不同炸药当量及不同网格尺寸开展系列运算,从而得到不同炸药当量在满足工程计算精度要求下所对应的建议网格尺寸,并得到了不同炸药当量所对应的建议网格尺寸的表达式。 相似文献
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在声波的教学中,由于学生知识结构的关系,对于声波性质的了解有一定的欠缺,为了让学生充分认识声波的特性,在实际教学过程中,通过对如下几个关系的认识,学生对知识的了解将会更加清晰、明了.1 声波的传播与波速的关系 在教材中,列出了声波在各种不同介质中的传播速度,以及它们随温度变化的情况, 相似文献
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平均余弦是海水重要的表观光学参数之一。本文分析比较不同水质参数下平均余弦随散射次数以及传输距离的变化规律,得出准直光束在不同水质海水中散射次数的分布及极限。 相似文献
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克尔型介质平板波导中的弱非线性横向电场波 总被引:1,自引:0,他引:1
对芯子为克尔型非线性介质、覆盖层和衬底为线性介质的平板波导,在弱非线性近似下,导出了这类波导横向电场波满足的色散方程和场分布,其物理意义清晰,且大大降低了数值计算的强度。 相似文献
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Numerical simulation of traveling wave excitation, propagation, and diffraction in structures with local inhomogeneities (obstacles) is computationally expensive due to the need for mesh-based approximation of extended domains with the rigorous account for the radiation conditions at infinity. Therefore, hybrid numerical-analytic approaches are being developed based on the conjugation of a numerical solution in a local vicinity of the obstacle and/or source with an explicit analytic representation in the remaining semi-infinite external domain. However, in standard finite-element software, such a coupling with the external field, moreover, in the case of multimode expansion, is generally not provided. This work proposes a hybrid computational scheme that allows realization of such a conjugation using a standard software. The latter is used to construct a set of numerical solutions used as the basis for the sought solution in the local internal domain. The unknown expansion coefficients on this basis and on normal modes in the semi-infinite external domain are then determined from the conditions of displacement and stress continuity at the boundary between the two domains. We describe the implementation of this approach in the scalar and vector cases. To evaluate the reliability of the results and the efficiency of the algorithm, we compare it with a semianalytic solution to the problem of traveling wave diffraction by a horizontal obstacle, as well as with a finite-element solution obtained for a limited domain artificially restricted using absorbing boundaries. As an example, we consider the incidence of a fundamental antisymmetric Lamb wave onto surface and partially submerged elastic obstacles. It is noted that the proposed hybrid scheme can also be used to determine the eigenfrequencies and eigenforms of resonance scattering, as well as the characteristics of traveling waves in embedded waveguides. 相似文献
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The temperature field distribution directly reflects the combustion condition in a furnace.In this paper, acoustic thermometry to reconstruct temperature distribution is investigated. A method based on radial basis function approximation with polynomial reproduction (RBF-PR) is proposed in order to improve the accuracy and stability of the method based on RBF approximation. In addition, the refraction effect of sound wave paths is considered in the process of reconstruction. The curved lines with refraction effect are numerically calculated by solving differential equations, which show that sonic waves curve towards the zones of higher temperature. The reconstructed performance is validated via numerical simulation using four temperature distribution models. Results and analysis show that the proposed method has much greater accuracy than the method based on RBF approximation, and when considering the effect of refraction, our method can reconstruct more excellent reconstruction performance than others, which do not take into account the refraction effect of sound wave paths. 相似文献
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《中国物理快报》2017,(9)
We study the phonon mode excitation of spin-orbit(SO) coupled Bose-Einstein condensates trapped in a one-dimensional optical lattice. The sound speed of the system is obtained analytically. Softening of the phonon mode,i.e., the vanishing of sound speed, in the optical lattice is revealed. When the lattice is absent, the softening of phonon mode occurs only at the phase transition point, which is not influenced by the atomic interaction and Raman coupling when the SO coupling is strong. However, when the lattice is present, the softening of phonon modes can take place in a regime near the phase transition point. Particularly, the regime is widened as lattice strength and SO coupling increase or atomic interaction decreases. The suppression of sound speed by the lattice strongly depends on atomic interaction, Raman coupling, and SO coupling. Furthermore, we find that the sound speed in plane wave phase regime and zero-momentum phase regime behaves with very different characteristics as Raman coupling and SO coupling change. In zero-momentum phase regime, sound speed monotonically increases/decreases with Raman coupling/SO coupling, while in plane wave phase regime, sound speed can either increase or decrease with Raman coupling and SO coupling, which depends on atomic interaction. 相似文献
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根据鱼雷对舰船毁伤的特点,建立了多介质水下爆炸数值模型,提出了交界面处理及广义光滑长度计算方法,编制了多介质水下爆炸计算程序,并对水下爆炸空气隔层衰减冲击波的性能进行了定量分析。结果表明:无论是接触爆炸还是非接触爆炸,空气隔层均可有效衰减冲击波,并且接触爆炸中空气隔层衰减冲击波的效果更好,最大可使冲击压力峰值降低约55%;空气隔层厚度与爆炸厚度之比为1时便可达到较好的衰减冲击波效果,继续增加空气隔层厚度对衰减冲击波效果影响不大。研究结果可为舰船结构防护及防雷舱的结构设计提供参考。 相似文献
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Alexander Ye. Svezhentsev 《International Journal of Infrared and Millimeter Waves》2008,29(8):724-740
Eigenwave analysis is given to an infinite array of stub-loaded rectangular waveguides using the method of moments (Galerkin’s
scheme), with the basis functions explicitly satisfying the rectangular-edge condition. The numerical data on propagation
constants and field structure for different modes are presented as a function of geometrical parameters and frequency. The
emphasis is on the groove dominant wave. In particular, its radiation loss is shown to be effectively controlled by adding
some asymmetry to the groove geometry. Wave mode coupling effects have been revealed between the groove dominant wave and
the planar waveguide section waves. The so-called Morse critical points of the dispersion equation are identified within the
coupling domains. 相似文献
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A simple and effective method is proposed to analyze the field distribution of a curved dielectric waveguide with rectangular cross-section. Numerical results are compared with the measured values. It is shown that the present approach is effective and reliable. 相似文献