奈奎斯特准则提供了一种图形方法来确定闭环系统的稳定性。
信仰是生命的意义,这种感觉使人不毁灭自己,而是继续活下去。
The only way to avoid being miserable is not to have enough leisure to wonder whether you are happy or not.
The writer must be a smuggler of truths, a clandestine agent of freedom.