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把同一个系统用不同的软件建模,可以发现很多有趣的地方。5 b& G2 @3 B! J% v9 M
这是一个人力资源调度的小模型。7 q- j8 R% v' a8 L' C4 E5 J
按题目要求分别用ExtendSim和Arena建模,结果发现离开系统的实体数量有差异3个,参数和时间我已经检查过了,没有差异。已知Arena模型没有错,谁知道ExtendSim输出结果为何会有差别?难道是Shift里面的时间点设置有问题吗?
/ p) ?- J! C: ^题目:
& x2 ^+ h0 I# Z) U! K3 _( a3 VAt the DMV photo license center, the current “rule of thumb” is to get the drivers in and 0 ~+ u9 Q: s- G7 B
out as fast as possible. Therefore, when drivers come to get their photo ID, the following , M5 ]5 h/ m6 c3 v6 S
activities occur: Drivers go to a large counter, pick up a blank form, and fill it out. (We’ll
& |" z* o3 P4 M* r( o; K. yassume the counter is large enough that any number of drivers can obtain and complete
: `$ s2 {, c6 I2 m) C# dthe form at one time.) The drivers then wait in line for an available photo clerk. * d& d" }0 j- D
The drivers are serviced by: 1 part-time clerk (Rich) who works daily from 10 a.m. to m& [2 e" b1 D: j
2 p.m., 1 full-time clerk (Ann) who works daily from 8 a.m. to 5 p.m. with an hour break ! F% _" ], ?4 x. J$ g5 l# y
between 10:30 a.m. and 11:30 a.m., and the site manager (Dina) who only helps when + O4 s z4 S! w# [
everyone else is busy and there are more drivers to be served. The manager works daily 2 A: T: i/ N/ X. k4 t& k, G. A7 y, U
like Ann, but gets her break from 1:15 p.m. to 2:15 p.m. Due to budgetary constraints,
) }* \1 b/ G' Q' |- u5 v' q( N) n8 }there are only 2 computers available at the facility. (Don’t worry about using sets for this " y7 ~. Z2 w( n3 Q$ _
resource.) The computers are used to capture the driver’s signature and to print the
! J4 h& Q+ B* k0 K: L4 {) elicense. . o6 T2 K' X2 T/ X l
The process goes as follows: The clerk reviews the form with each driver, takes the
% S# G/ Q& |; h/ Xdriver’s photo, captures the driver’s signature, and prints the completed license. (Note: A
2 B4 H5 j9 I- d& U) t: Ncomputer is needed for both the signature capture and for printing the license.) The DMV 4 Y. n' b9 o6 d; {' z! Q
manager knows that it normally takes 3 minutes (some as short as 2 minutes, others as 3 p2 q5 F! o- }9 S0 ^% b9 Q X
long as 4 minutes) to review the form and take a driver’s photo, and anywhere between
9 k* ?0 n. a0 g30 and 60 seconds to capture the driver’s signature electronically. It then takes exactly * o. ?# g4 Z" Q* X( P
45 seconds to print and seal the new photo driver’s license. |
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