理解大自然对气候变化有怎样的反应需要监视世界各个角落的关键生命周期事件一一花开、叶子的出现、青蛙第一声呼唤春天的鸣叫。
Understanding how nature responds to climate change will require monitoring key life cycle events - flowering, the appearance of leaves, and the first frog calls of the spring - all around the world.
从自激振荡的稳定性入手，分别讨论了热声网络的周期时均和时变数学模型。
Based on the stability of self-oscillation of thermoacoustic engine. models of periodic average and time-varied are investigated respectively.
实验结果表明：正常肺音音源为白噪声，异常肺音音源为周期脉冲序列，肺胸系统相当于声低通滤波器。
The results of experiment show that dreath sound sources are random white noise, Abnormal breath sounds sources are sequence of periodic impulses.
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