某系统的闭环传递函数为：
，当k=（）时，闭环系统临界稳定。
A: 4
B: 8
C: 6
D: 2
，当k=（）时，闭环系统临界稳定。A: 4
B: 8
C: 6
D: 2
举一反三
- 某单位反馈系统的开环传递函数为：<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/eac70a0847b54d83b5a0ca46656a57cf.png" />，当k=（ ）时，闭环系统临界稳定。 A: 20 B: 30 C: 10 D: 40
- 为使锅垢中难溶于酸的CaSO4转化为易溶于酸的CaCO3，常用Na2CO3处理，反应式为CaSO4+CO32-<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/88320eab77594b6abf0039ab0efe3c57.png" />CaCO3+SO42-，此反应的标准平衡常数为（）。 A: K<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/e8c371ce6b96487e829331bb8dee134f.png" />(CaSO4)·K<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/e8c371ce6b96487e829331bb8dee134f.png" />(CaCO3) B: K<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/e8c371ce6b96487e829331bb8dee134f.png" />(CaCO3)/K<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/e8c371ce6b96487e829331bb8dee134f.png" />(CaSO4) C: [K<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/e8c371ce6b96487e829331bb8dee134f.png" />(CaSO4)·K<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/e8c371ce6b96487e829331bb8dee134f.png" />(CaCO3)]1/2 D: K<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/e8c371ce6b96487e829331bb8dee134f.png" />(CaSO4)/K<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/e8c371ce6b96487e829331bb8dee134f.png" />(CaCO3)
- 某最小相位系统的开环对数幅频特性曲线<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/bcd21e42b27341478945568b99d0e0e1.png" >如图所示，则其开环传递函数和相角裕度分别为（）。<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/84e4b98286924479ae7d38d3b0e5fd2f.png" > A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/b0eda84a8f794aaab38a2ca259435434.png" > B: 0° C: 16.3° D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/aa67284249764b51bb1c9fb836c2a9aa.png" >
- 设随机变量X~N(4,2)，则其特征函数为(). A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/357ad388efa144a1a2b824e2b1ded239.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/d52e72841a81484981168cbb693bad24.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/00e1e0c2bba04889b58eb483c88821fb.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/1851c30670244a5c821128d6c44a3ecc.png" >
- 10人中至少有2人同生日的概率是多少？（1年按365天计算）() A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/f3b577db2dd0429b9eab51dff5644b23.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/6f30552128e14bfb89b26b30ac2b72db.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/fa8f9ba9bd2d4a40b7d007fd9e9988fd.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/05a12b5d4da04e2c9ea779b313981c83.png" >