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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。
; M. b. F& x# M% }3 \这是一个人力资源调度的小模型。. h' _+ z% }7 l! C: }
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?4 f, M- i+ N4 e. d
题目:
" Q0 b/ U ]% E, W5 {! ^. {At the DMV photo license center, the current “rule of thumb” is to get the drivers in and
, i0 [) B) |6 k0 J( Mout as fast as possible. Therefore, when drivers come to get their photo ID, the following + {7 Q% K! I% t
activities occur: Drivers go to a large counter, pick up a blank form, and fill it out. (We’ll ( [3 `, ~& ]1 R7 J, N# t! I7 h
assume the counter is large enough that any number of drivers can obtain and complete / B7 k, G! K# e, R( A% X" c
the form at one time.) The drivers then wait in line for an available photo clerk.
# q3 [& J, T( ^& o$ h' _The drivers are serviced by: 1 part-time clerk (Rich) who works daily from 10 a.m. to 8 @( `/ V5 j) S3 F- ~( ^3 E
2 p.m., 1 full-time clerk (Ann) who works daily from 8 a.m. to 5 p.m. with an hour break 5 {& v @! H6 z! Z/ l0 {9 z" R o
between 10:30 a.m. and 11:30 a.m., and the site manager (Dina) who only helps when 0 h" A! H7 B" m: O
everyone else is busy and there are more drivers to be served. The manager works daily
" w' F. v& j3 L% g: P/ Qlike Ann, but gets her break from 1:15 p.m. to 2:15 p.m. Due to budgetary constraints,
* {: K7 `3 q, L0 e) t& m# a3 Y' fthere are only 2 computers available at the facility. (Don’t worry about using sets for this $ u. C# S' W; b
resource.) The computers are used to capture the driver’s signature and to print the
: ?, t6 i5 S9 N4 ^& elicense.
( v/ f) l8 n3 L6 a- j6 c& t3 {The process goes as follows: The clerk reviews the form with each driver, takes the + Z5 d+ W8 K1 ]- m* E1 _
driver’s photo, captures the driver’s signature, and prints the completed license. (Note: A ( o! b, X% P; g4 Q. [6 u- U
computer is needed for both the signature capture and for printing the license.) The DMV # [ f/ W7 F5 o, ^5 Q
manager knows that it normally takes 3 minutes (some as short as 2 minutes, others as 5 a- T* W* O# O: [! r
long as 4 minutes) to review the form and take a driver’s photo, and anywhere between \% h# D, Q! A% |
30 and 60 seconds to capture the driver’s signature electronically. It then takes exactly + x' q" r* {3 Y( M( B
45 seconds to print and seal the new photo driver’s license. |
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