声学隐身和海市蜃楼与飞毯
Acoustic cloaking and mirages with flying carpets
摘要：
这里考虑的地毯，在可压缩流体中传播的压力声波的上下文中，不接触地面：它们漂浮在半空中（或漂浮在水中），这导致隐藏在下面的物体的近似隐身，或接触地面上或上方的方柱体的任何一侧。附在方形圆柱体侧面的帐篷状地毯说明了墙上地毯的概念如何自然地推广到其他小型紧凑物体的侧面。然后我们将飞毯的概念扩展到圆柱体。然而，我们并没有像声学斗篷那样减少其散射截面，而是模仿另一种障碍物的散射截面，比如方形刚性圆柱体。例如，我们可以在这种圆形地毯下隐藏任何类型的缺陷，但它们仍然像一个较小的圆柱体一样散射波。有趣的是，所有这些地毯都由非奇异声学参数描述。为了解决这个重要的方面，我们提出了一个多层地毯组成的各向同性均匀的流体具有恒定的体积模量和不同的密度，其工作在有限的波长范围内。本文以声纳船和雷达为例，讨论了其应用。例如，我们想渲染一条位于海底或漂浮在水中的管道，使其无法被一艘在海面上静止的声纳船检测到。另一个可能的应用是保护抛物面天线。
英文摘要：
Carpets under consideration here, in the context of pressure acoustic waves propagating in a compressible fluid, do not touch the ground: they levitate in mid-air (or float in mid-water), which leads to approximate cloaking for an object hidden underneath, or touching either sides of a square cylinder on, or over, the ground. The tentlike carpets attached to the sides of a square cylinder illustrate how the notion of a carpet on a wall naturally generalizes to sides of other small compact objects. We then extend the concept of flying carpets to circular cylinders. However, instead of reducing its scattering cross-section like in acoustic cloaks, we rather mimic that of another obstacle, say a square rigid cylinder. For instance, show that one can hide any type of defects under such circular carpets, and yet they still scatter waves just like a smaller cylinder on its own. Interestingly, all these carpets are described by non-singular acoustic parameters. To exemplify this important aspect, we propose a multi-layered carpet consisting of isotropic homogeneous fluids with constant bulk modulus and varying density which works over a finite range of wavelengths. We have discussed some applications, with the sonar boats or radars cases as typical examples. For instance, we would like to render a pipeline lying on the bottom of the sea or floating in mid-water undetectable for a boat with a sonar at rest just above it on the surface of the sea. Another possible application would be protecting parabolic antennas.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
