On Thursday, the U. S. Navy said Somali pirates opened fire on a Navy helicopter, as it was conducting a surveillance of a captured vessel in central Somalia.

星期四，美国海军说，索马里海盗对一架海军直升机开火，这架直升机当时在索马里中部对一艘被海盗劫持的船只进行监视。

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For infrared surveillance system, it is most difficult that the measurements are only angles not distance, which makes target location of fire control system be difficult to realize.

对于红外预警系统，目标定位的最大难点是观测量只有角度，没有距离，这就使得火控系统的目标导引遇到困难。

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This proves that the one-dimensional trajectory amendments mode of ground radar surveillance and progroud fire-control center control is entirely feasible and can achieve low-cost and miniaturization.

由此可见，采用地面雷达导航、由地面火控中心发射指令的一维弹道修正方式完全可行，并可以做到低成本，小型化。

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Backers hope they will prove a cheaper alternative to helicopters and fixed-wing aircraft for tasks as varied as power and pipeline inspection, mapping, security, border surveillance, research, filming, fire fighting, search and rescue and delivering supplies.

ECONOMIST: A small Welsh airport has become an unlikely tech cluster

"The cease-fire enabled us to conduct disease surveillance with the freedom of movement, not fearing land mines and getting shot, " said Dr. Nabil Azziz, who coordinated Sudan's national Guinea worm eradication program until 2007.

CNN: Guinea worm a greater challenge than smallpox

Former President Jimmy Carter negotiated a cease-fire in 1995 to allow health workers to conduct national Guinea worm disease surveillance, treating patients and tracking cases.

CNN: Guinea worm a greater challenge than smallpox