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楼主 |
发表于 2011-4-19 23:05
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回复 hupo99
这就是所谓 "迷宫箱的原理"吗? 是不是作者自己都被"多次反射"搞晕了, 绕不出来了?
推荐一 ...
dd2008 发表于 2011-4-18 16:26 
不错 ,一个很好的悖论。如果声道是弯曲光滑的,多次反射并不严重。声道的长度不能乱定。
你提到的pdf里面有很多论述,46页的E文啊。谁个翻译一下再放上来就好了,建议开新帖
Displacement, Velocity, and Acceleration :
Three expressions need to be defined to allow the discussion to proceed and
hopefully have some physical meaning for most readers. In the following paragraphs
sinusoidal displacement, velocity, and acceleration will be referred to over and over
again. For example, the equations describing one possible sinusoidal displacement
function and its relationship to velocity and acceleration are shown below.
displacement = x(t) = sin(ω t )
velocity = u(t) = dx/dt = ω cos(ω t) = ω sin(ω t + 90 degrees)
acceleration = a(t) = d2x/dt2 = -ω2 sin(ω t) = ω2 sin(ω t + 180 degrees) |
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