zhishengji751.
My knowledge of utility patent law is very, very limited. However, it appears that all, or most, of the world's patent offices will not patent an invention after it is in the public domain and is perhaps already being used by others. To me, this makes good sense.
In the instance that you mention, only one of the four presenters of the earlier paper is one of the four inventors on the Patent Application. This earlier paper describes a unique idea (invention) for rotorcraft flight-control, only. All of the claims in the Patent Application are very general and they existed in the public domain well ahead of the paper's research.
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From a personal perspective, I have approximately
116 Web pages, which describe in various levels of detail, that which may constitute new ideas (inventions) to improve rotorcraft. They are all in the public domain so that others may utilize any valid ones and then patent any of their own ideas that may be founded on these public ideas.
It would 'piss me off' if someone were to usurp any of these ideas for their own personal gain, and to the detriment of others.
Dave