This peper introduces the concept of direct-projective covers, and prove that a ring R is left perfect if and only if every left R-module(flat left R-module) has a direct-projective cover;
The cooling problem of solid state active phased array radar is discussed in this paper. And the type of a high efficient cold plate with plate fin that is suitable for T /Rmodule is introduced .
对固态有源相控阵雷达的冷却问题进行了探讨,并且介绍了一种适合于T/R组件用的高效率板翅式冷板。
3
The principle of digital T/Rmodule based on direct digital synthesis (DDS) technology is proposed, and the experiment results on the digital T/Rmodule are given in this paper.