共查询到20条相似文献,搜索用时 125 毫秒
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快速多极子边界元算法可以加速矩阵和向量乘法运算, 将传统边界元算法的计算量和内存占用量分别降为O(N log2N)和O(N), 适用于大型声学模型模拟计算. 本文发展了一种基于Burton-Miller方程的三维多层声学快速多极子边界元算法. 将新的自适应树状算法应用到对角形式的快速多极子边界元算法, 并使用最新提出的解析式源点矩计算公式, 进一步提高了快速多极子边界元的计算效率. 绝对软球体在内部共振频率处的散射声场计算, 验证了所发展算法在共振频率处求解的正确性. 与Bapat所提供的程序在多脉动球体辐射声场计算精度的比较, 验证了算法及程序在大型模型声学计算中的准确性, 同时显示了其求解的高效性. 最后, 将该算法用于车内声场及水下声学探测的分析计算. 相似文献
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与模型自由度的平方成正比的存储量和计算量,使传统边界元无法应用到大型模型的计算。为此,发展了一种二维声学多层快速多极子边界元算法。通过二维Helmholtz核函数展开理论的简要介绍,推导了源点矩计算、源点矩转移、源点矩至本地展开转移、本地展开转移公式,并详细描述了二维声学快速多极子边界元算法的具体实现步骤。使用快速傅里叶插值进行源点矩和本地展开系数的多层传递。采用对角左预处理方法,改善边界方程的条件数,减少迭代求解次数。最后通过数值算例,验证了所发展的二维声学快速多极子算法的正确性和高效性。 相似文献
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针对基于空间功率合成的空馈平面反射阵(FLAPS)型高功率微波辐射器的高效率电磁仿真需求,应用积分方程方法结合多尺度混合电磁建模技术MLFMA-MLACE进行问题的电磁建模及求解,主要过程包括:针对设计模型进行多尺度几何建模;在宏观层面采用多层快速多极子加速矩矢相乘;在微观层面采用多层笛卡尔展开加速求解。结合W波段的FLAPS初步模型,利用传统多层快速多极子技术(MLFMA)进行了精度验证,对于混合方法在仿真中的适用性、模型等效处理程度的影响以及计算成本等进行了分析。结果表明,该方法在内存及计算时间方面显著地提高了效率,论文还对后续改进方向进行了讨论。 相似文献
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鉴于快速多极子边界元法的应用主要局限于单区域声学问题计算,发展基于子结构技术的快速多极子边界元法以计算多区域声场问题,介绍基本原理、具体实施过程以及优缺点.以带有插进口管的膨胀腔消声器为例,应用子结构快速多极子边界元法和传统边界元法计算其传递损失,通过与实验测量结果的比较,验证方法的有效性和计算精度.研究表明,快速多极子边界元法与传统边界元法相比,节点数越多,其在节省计算时间,减少计算量等方面的优势越明显. 相似文献
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在电磁场积分方程方法框架下,应用等效原理求解了半空间背景下目标的电磁散射问题,可针对目标仅处于半空间界面单侧及目标跨越半空间界面处于半空间两侧的几何相对位置。与传统的半空间格林函数计算方法不同的是,这一方法使用的是各自介质的自由空间格林函数,因此可以回避索墨菲积分并且可以很方便与快速算法(如多层快速多级子)相结合,并对求解临近半空间界面的目标获得较好的收敛性。在等效原理方法中需要用有限的界面等效无限大半空间界面,因此采用了锥形入射波以降低开放边界引起的边缘效应。不同于一般目标的远场雷达散射截面表达,在该模型下,半空间电磁散射的远场描述需要用差场雷达散射截面。给出的算例能与现有文献以及仿真软件很好的吻合,并可作为实用工具分析半空间背景对目标远场响应的影响。 相似文献
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James K. Boon 《Waves in Random and Complex Media》2004,14(3):199-216
Traditionally, in moment-method analyses of electromagnetic scattering, the elements of the impedance matrix are calculated as convolutions of the basis elements with the appropriate dyadic Green's function. However, for scattering in the half-space, the vertical and azimuthal copolar terms of the Green's function require evaluation of Sommerfeld integrals which are computationally burdensome. In this paper, it is shown that, in populating the impedance matrix for the half-space problem, evaluation of Sommerfeld integrals is, in fact, not necessary. For monochromatic excitation, the plane-wave expansion of the scattered field constitutes a Fourier transform, in the horizontal plane, of a vector spectral function. This vector function results from the convolution, in the vertical dimension, of the respective angular spectra of the Green's function and the equivalent current. On application of the moment method, through the Weyl identity, the impedance-matrix elements corresponding to the singular terms of the Green's function are convolutions in the horizontal plane of spherical potentials, and Fourier transforms of scalar spectral functions. These scalar functions are derived from the basis elements and, with a judicious choice of basis, they are well behaved and of compact support, and consequently their Fourier transforms can be computed as FFTs. 相似文献
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Ochmann M 《The Journal of the Acoustical Society of America》2004,116(6):3304-3311
The sound field caused by a monopole source above an impedance plane can be calculated by using a superposition of equivalent point sources located along a line in the mirror space below the plane. Originally, such an approach for representing the half-space Green's function was described by Sommerfeld at the beginning of the last century, in order to treat half-space problems of heat conduction. However, the representation converges only for masslike impedances and cannot be used for the more important case of reflecting planes with springlike surface impedances. The singular part of the line integral can be transformed into a Hankel function, which shows that surface waves are contained in the whole solution. Unfortunately, this representation suffers from the lack of validity at certain receiver points and from restrictions on wave number and impedance range to ensure the necessary convergence. The main idea of the present method is to use also a superposition of equivalent point sources, but to allow that these sources can be located at complex source points. The corresponding form of the half-space Green's function is suitable for both masslike and springlike surface impedances, and can be used as a cornerstone for a boundary element method. 相似文献
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研究了半空间内(海面,地面)电大尺寸涂敷目标散射的高频求解方法.将半空间并矢格林函数引入物理光学方法中,对半空间复杂环境影响进行考虑,并利用阻抗边界条件考虑涂敷目标表面的复杂电磁散射,推导出半空间物理光学分析方法,同时结合图形电磁学,对半空间电大涂敷目标进行消隐判断,提取像素面元法矢量和深度缓存等有效信息,快速有效地计算了半空间电大涂敷目标的雷达散射截面.数值结果证明了方法的有效性和准确性.
关键词:
半空间物理光学方法
半空间并矢格林函数
图形电磁学
雷达散射截面 相似文献
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Zabolotskaya EA Ilinskii YA Hay TA Hamilton MF 《The Journal of the Acoustical Society of America》2012,131(3):1831-1842
Green's functions are derived for elastic waves generated by a volume source in a homogeneous isotropic half-space. The context is sources at shallow burial depths, for which surface (Rayleigh) and bulk waves, both longitudinal and transverse, can be generated with comparable magnitudes. Two approaches are followed. First, the Green's function is expanded with respect to eigenmodes that correspond to Rayleigh waves. While bulk waves are thus ignored, this approximation is valid on the surface far from the source, where the Rayleigh wave modes dominate. The second approach employs an angular spectrum that accounts for the bulk waves and yields a solution that may be separated into two terms. One is associated with bulk waves, the other with Rayleigh waves. The latter is proved to be identical to the Green's function obtained following the first approach. The Green's function obtained via angular spectrum decomposition is analyzed numerically in the time domain for different burial depths and distances to the receiver, and for parameters relevant to seismo-acoustic detection of land mines and other buried objects. 相似文献
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A half-space, x3 0, of a transversely isotropic solid whose axis of symmetry makes an angle with the x3-axis, is subjected to a spatially uniform time-harmonic distribution of normal surface tractions over a circular area of the plane x3 = 0. The wave motion radiated into the half-space is investigated. Using an integral representation for the displacement components the problem is first reduced to a system of singular integral equations for the displacements on the surface x3 = 0. This system is solved by the boundary element method over a truncated area, where use is made of recently derived simplified forms of the Green's functions. The results show the skewing of the beam as the angle between the axis of symmetry of the transversely isotropic solid and the normal to the surface of the solid is increased. 相似文献
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Coyette JP Van den Nieuwenhof B 《The Journal of the Acoustical Society of America》2000,108(4):1464-1473
Many acoustic problems (especially in environmental acoustics) involve half-space domains bounded by a plane subjected to normal admittance boundary conditions. In the "low" frequency domain, the numerical treatment of such problems usually relies on boundary element methods based on a particular Green's function suited for the half-(admittance) plane. In the present paper, an alternative hybrid finite/infinite element scheme is proposed. The method relies on a direct treatment of nonhomogeneous boundary conditions along infinite element edges (or faces). The procedure is validated through comparisons with an available reference solution. 相似文献
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V.V. Kocharovsky VI.V. Kocharovsky 《Physica C: Superconductivity and its Applications》1992,200(3-4):385-402
The Green's function method and diagram technique for umklapp electron-electron scattering mediated by the screened Coulomb interaction in layered anisotropic conductors are examined. Gor'kov-type equations and their general solution for anomalous and normal temperature Green's functions are derived taking into account umklapp scattering of all orders. Explicit equations for dielectric and superconducting order parameters, including coexistent Bragg and BCS pairing, are found. The possibility of the first-order phase transition to the superconducting state is discussed. The theory elucidates the origin of Bragg-Coulomb high-Tc superconductivity, proposed by the authors. 相似文献