Diffraction assisted rough ground effect: models and data.
Diffraction assisted rough ground effect: models and data.
复制标题
衍射辅助粗糙地面效应：模型和数据。
DOI：
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发表时间：
2013
影响因子：
2.4
通讯作者：
K. Attenborough
中科院分区：
文献类型：
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作者：
I. Bashir;S. Taherzadeh;K. Attenborough
本文研究了具有不同截面形状的周期性和随机分布的粗糙元(半圆柱形、矩形和楔形条)在过量衰减(EA)谱中观察到的破坏性干扰。如果粗糙度是周期性间隔的，则在与随机分布的粗糙度观察到的一个或两个相同的频率范围内观察到两个或三个相消干涉极大值。对粗糙度引起的表面波也进行了研究。它们的幅度和出现的频率取决于粗糙度高度、平均中心到中心间距和粗糙度的周期性程度。用半解析多重散射理论和数值方法(边界单元法)对EA谱进行了预测，并与实测值进行了比较。此外，研究还发现，由粗糙表面复EA测量得到的有效表面阻抗谱与硬背多孔层的有效表面阻抗谱具有相似的共振性。在此基础上，建立了粗糙硬表面的启发式有效阻抗模型，并将相应的EA谱预测值与数据进行了比较。
The destructive interferences observed in Excess Attenuation (EA) spectra over periodically and randomly spaced roughness elements with different cross-sectional profiles (semicylindrical, rectangular and wedge-shaped strips) have been investigated. If the roughness is spaced periodically, then two or three destructive interference maxima are observed in the same frequency range as the one or two observed with randomly distributed roughness. Roughness-induced surface waves are investigated also. Their amplitudes and the frequencies at which they occur are found to depend on the roughness height, mean center-to-center spacing and the extent to which the roughness is periodic. A semianalytical Multiple Scattering Theory and a numerical method (the Boundary Element Method) have been used to make predictions of the EA spectra which are compared with measurements. In addition it is found that the effective surface impedance spectra deduced from complex EA measurements over rough surfaces exhibit resonances similar to those observed for a hard-backed porous layer. On this basis a heuristic effective impedance model for rough hard surfaces is developed and the corresponding predictions of EA spectra are compared with data.