In this model, the noise field in sound shadow region is deduced by applying Huygens-Fresnel principle. It provides a new ideal for deducing the diffraction sound of complicated…

模型中对声影区的声场分布采用惠更斯-菲涅耳原理进行推导计算，给出的理论计算公式可为推导计算其它复杂声源的衍射声提供借鉴。

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For decades, the conflict between Israelis and Arabs has cast a shadow over the region.

WHITEHOUSE: Moment of Opportunity: American Diplomacy in the Middle East & North Africa | The White House

But BP's disastrous oil spill in the Gulf of Mexico has cast another dark shadow over the region.

ECONOMIST: New Orleans five years after Katrina

Mr Lloyd, who was elected as PCC in November, said child sexual exploitation was a "hugely complex issue which casts a dark shadow" across the region.

BBC: Summit held to tackle child grooming in Greater Manchester