一个LTI系统是因果的充分必要条件是其系统函数的收敛域包含 ( )
A. 单位圆
B. 无穷
C. 实轴
D. 虚轴
它们的线性卷积长度N为 ( )
A. 17
B. 16
C. 18
D. 19
What are the measures to prevent local instability of the beam ( )
A. limit the width-thickness ratio of the plate
B. Increase the section moment of inertia
C. Set the stiffener
D. Increase section area
In the following members, which one can be treated as axially loaded member? （）
A. frame beam
B. shear wall
C. member in steel truss
D. frame column
微信支付 
支付宝支付