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【简答题】在 Fanuc Oi Mate-MC 数控系统中,手轮是一个与数控系统以数据线相连的独立个体。它由控制轴旋钮、移动量旋钮和手摇脉冲发生器组成。在手轮进给方式中,刀具可以通过旋转机床操作面板上的手摇脉冲发生器微量移动。手轮旋转一个刻度时,刀具移动的距离根据手轮上的设置有 3 种不同的移动距离,分别为: ( )mm 、 ( )mm 、 ( )mm
【单选题】Suppose relation R(A,B,C) has the following tuples: A B C 1 2 3 4 2 3 4 5 6 2 5 3 1 2 6 Select the tuples with the condition of either A>B or B>C. Which of the following tuples is in the result?
A.
(4,5,3)
B.
(2,5,3)
C.
(4,5,6)
D.
(1,2,3)
【单选题】Suppose relation R(A,B) has the following tuples: A B 1 2 3 4 5 6 and relation S(B,C,D) has the following tuples: B C D 2 4 6 4 6 8 4 7 9 Compute the theta-join of R and S with the condition R.A < S.D...
A.
(3,4,4,6,8)
B.
(1,2,2,6,8)
C.
(5,6,4,6,8)
D.
(1,2,4,6,8)
【单选题】Suppose relation R(A,B,C) has the following tuples: A B C 1 2 3 4 2 3 4 5 6 2 5 3 1 2 6 Compute the projection π C,B (R). Which of the following tuples is in the result?
A.
(2,3)
B.
(4,3)
C.
(3,2)
D.
(5,6)
【简答题】比较M03S800和G01X20F200两组指令的不同,数控机床的主轴控制与进给控制不同,进给控制是一个以 和 为控制目标的系统。而主轴控制是一个以 控制目标的自动控制系统,位移(角位移)不是主轴控制的目标。
【单选题】Suppose relation R(A,B,C) has the following tuples: A B C 1 2 3 4 2 3 4 5 6 2 5 3 2 1 6 Select the tuples with the condition of either A>B or B>C. Which of the following tuples is NOT in the result?
A.
(4,2,3)
B.
(2,5,3)
C.
(4,5,6)
D.
(2,1,6)
【单选题】Suppose relation R(A,B) has the following tuples: A B 1 a 7 t 2 g 4 c 9 t and relation S(B,C,D) has the following tuples: B C D c 5 6 a 7 8 t 8 9 Compute the theta-join of R and S with the condition R...
A.
(1, a, a, 7, 8)
B.
(2, g, c, 5, 6)
C.
(4, c, c, 7, 8)
D.
(4, c, c, 7, 8)
【单选题】Suppose relation R(A,B,C) has the following tuples: A B C 1 2 3 4 2 3 4 5 6 2 5 3 1 2 6 Compute the projection π C,A (R). Which of the following tuples is in the result?
A.
(1,3)
B.
(4,3)
C.
(3,4)
D.
(5,3)
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