更多"在绘制事故树时,下层事件R1和R2其中只要有一个事件发生上层事件A就发"的相关试题:
[单项选择]在绘制事故树时,下层事件R1和R2其中只要有一个事件发生上层事件A就发生,这种情况下应使用( )表示三者的逻辑关系。
A. 或门
B. 与门
C. 与或门
D. 限制门
[单项选择]在绘制故障树时,下层事件R1和R2同时发生才会引起上层事件A的发生;反之,下层事件有一个不发生,A也不发生,则应使用______表示三者的逻辑关系。
A. 或门
B. 与门
C. 与或门
D. 非门
[判断题]电阻R1,R2并联,已知R1>>R2,并联后的等值电阻近似等于R1,即R≈R1。
[填空题]电阻R1和R2串联,已知R2=4R1,若R2两端电压U2=16V,则R1两端电压U1=()。
[单项选择]设关系R1有r1个元组,关系R2有r2个元组,则关系R1和R2连接后的结果关系的元组数目是 ______ 个。
A. r1+r2
B. ri*r2
C. ≤r1*r2
D. ≥r1*r2
[单项选择]设关系R1有r1个元组,关系R2有r2个元组,则关系R1和R2连接后的结果关系中的元组数目是______个。
A. rl+r2
B. rl×r2
C. ≤rl×r2
D. ≥r1×r2
[判断题]表达式"R1=R2+R3*SIN(R4)"的运算次序依次为SIN(R4),R3*SIN(R4),R2+R3*SIN(R4)(SIEMENS系统)。
[单项选择]在电路中R1和R2并联,R1=2Ω,R2=4Ω,则它们的电流比I1:I2=()。
A. 1:2
B. 1:4
C. 2:1
D. 4:1
[单项选择]两个电阻并联,其中R1为200Ω,通过R1的电流I1为0.2A,通过整个并联电路的电流I为1A,则R2=()Ω。
A. 50
B. 40
C. 30
D. 20
[单项选择]如下两个关系R1和R2,它们进行何种运算后得到R3R1
[判断题]已知R1=5Ω,R2=10Ω,把R1、R2串联起来,并在其两端加15V的电压,此时R1所消耗的功率是5W。
[单项选择]R1和R2并联,其功率之比P1:P2=1:2,并联的等效电阻为2Ω,则R1=()。
A. 6Ω
B. 7Ω
C. 8Ω
D. 9Ω
[单项选择]设关系R1有r1个元组,关系R2有r2个元组,则关系RI和R2连接后的结果关系的元组数目是______个。
A. r1+r2
B. r1*r2
C. ≤r1*r2
D. ≥r1*r2
[多项选择] Routers R1, R2, R3, and R4 connect to the same 10.10.10.0/24 LAN- based subnet. OSPF is fully working in the subnet. Later, R5, whose OSPF priority is higher than the other four routers, joins the subnet. Which of the following are true about the OSPF database exchange process over this subnet at this point?()
A. R5 will send its DD, LSR, and LSU packets to the 224.0.0.5 all - DR - routers multicast address.
B. R5 will send its DD, LSR, and LSU pack ets to the 224.0.0.6 all - DR - routers multicast address.
C. The DR will inform R5 about LSAs by sending its DD, LSR, and LSU packets to the 224.0.0.6 all- SPF - routers multicast address.
D. The DR will inform R5 about LSAs by sending its DD, LSR, and LSU pa ckets to the 224.0.0.5 all- SPF - routers multicast address.