图示危险点单元体的平面应力状态，按第三、第四强度理论的相当应力是（）。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/a3afa62ab3474f44b438ef2a5657f4c6.png

图示危险点单元体的平面应力状态，按第三、第四强度理论的相当应力是（ ）。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/a3afa62ab3474f44b438ef2a5657f4c6.png

已知系统和初始条件<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/15eb73651c0a4ae094e6de902b6c21ca.png" />求初始状态激励的响应 ( )。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/d016acd038b04b699e76c2354357c3d2.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/7a10be8f1ce74599a610fd0b9b9eb195.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/4621f442538946fdb897b89a1461e1e1.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/61b797beffc74a99b91e1934af1372fb.png" />

下面状态空间描述是能控规范形的是（）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/c0f8e3a2d77a4fd08b4ada9a5b324293.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/8d770c43b50544c08938c1b531fb582b.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/e7ba776f14894872b1c52d35b99ac85b.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/cc8e514019f84f9ea16e37a59b1a3bb1.png" />

已知<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/43114282e941476ba93775909fb3f237.png"/>，用拉氏变换法求解微分方程<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/0db291610cb64fa8ad46ae0bd15476b0.png"/> 的结果为（ ） A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/29ff68f02bdd438bb2e16c2a6e1ec18b.png"/> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/0010c1593c9145a4b928548ab38cf426.png"/> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/1f562f2536584121b53c30e4db08df88.png"/> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/f593399cb630435192baa8b3e871b533.png"/>