四大观测器中，仍有三个在服役。

Image above: Three of NASA's four Great Observatories are still in service. Credit: NASA.

观测器如何探测穿过地球的引力波涟漪呢？

How will the detectors know if a ripple of gravity passes through the Earth? Per Caltech's official LIGO website?

本文还分析了负载惯量变化时，观测器和系统的工作情况。

Also, the paper analyses how the observer and system work when the load inertia varies.

对于离散时间线性系统的输出反馈设计，我们考虑使用预测型降维观测器的积分控制器。

For the output feedback design of discrete-time linear system, we consider the integral controller using prediction type reduced-order observer.