An instrument for measuring ultrasonic attenuation by means of comparing the ultrasonic pulse echo with a calibrated exponential decay wave-form is described.
本装置用超声脉冲回波与定标指数波形比较的方法测量超声衰减。
By using the perturbed-energy method, the exponential decay of the solution is obtained for the nonlinear wave equations with time-dependent coefficients and dissipative boundary condition.
利用能量法证明了具耗散边界条件和时间依赖系数的非线性波方程的能量指数衰减性。
By using one-dimension FDTD method we simulates the decay of double exponential pulse through the soil media, and its refractive time-domain wave shape is discussed in detail.
用一维FDTD方法模拟了双指数脉冲在单层岩土介质中的衰减，并对电磁波在岩土层中的穿透进行了详细的讨论。
In theory, the influence of the exponential DC component on the fundamental wave component with random decay time constant can be completely eliminated with the algorithm.
理论上新算法可以消除任意衰减时间常数的直流分量对所求各次谐波分量的影响。
Downward wave amplitude decay in negative exponential function, but the upward wave amplitude is not the case.
下行波的衰减规律符合指数衰减，但上升波的衰减并不符合这一规律。
Downward wave amplitude decay in negative exponential function, but the upward wave amplitude is not the case.
下行波的衰减规律符合指数衰减，但上升波的衰减并不符合这一规律。
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