补贴有什么作用?
参考答案:
形成向冒口的补缩通道,实现顺序凝固,增强补缩效果,可消除铸件下部热节处的缩孔,还可延长补缩距离,减少冒口数目。
He was so diligent that he _____ as a fresher in Qinghua university three years later. [ ]
A. brought up
B. ended up
C. picked up
D. looked up
以下所列举的MIMO系统增益中,哪些是利用空间信道衰落的相对独立性获得的()。
A.阵列增益
B.分集增益
C.空间复用增益
D.干扰抑制增益