Modeling and Simulating
Business Processes
Chapter 8
Business Process Modeling, Simulation and
Design
1
Simulating Business Processes
NOTE:
We recommend presenting this chapter by running Extend
6.0 directly, and interactively show how the program works.
However, for your convenience, we have attached a
selection of the figures/screenshots from Chapter 8 of the
book as the basis for an in class presentation without access
to a computer with Extend installed.
2
Generating Items
Import block dialog showing and exponential interarrival times with mean of 6 minutes
3
Generating Items
1 2 A PV
t
y
Input Data block used to change the first parameter of the
inter-arrival time distribution in the Import block
4
Generating Items
Input Data block dialog for dry cleaner example
5
Generating Items
Program block (and dialog window) connected to a Stack block
6
Prioritizing Items
Selection of a priority queue in the Queue tab of a Stack block
7
Balking
Model of a single server with a queue, where customers
balk if the line reaches a specified number of customers
8
Balking
Dialog window of the Decision(2) block
9
Reneging
Incoming
calls
Helping
customers
u
#
Calls on hold
L
w
p
0
1 2 A PV
R
1
p
Answered
calls
#
23
CD
Lost calls
#
Rand
Generating
call time
7
1 2 3
Model of a single server with a queue, where customers hang up after
being on hold for specified amount of time
10
Reneging
Stack block to simulate a reneging queue with reneging time of 5 minutes
11
Priority Queues
Admissions process with a priority queue that allows
patients to go in front of the line after filling out additional forms
12
Priority Queues
Dialog window of the Stack block
13
Routing - Multiple Paths
0.20
Incoming job
0.30
0.50
Path 1
Path 2
Path 3
Example of probabilistic routing of an incoming job
14
Multiple Paths
#
0.20
21
Path 1
Probabilistic
decision
Generate jobs
#
0.30
29
?
1 2 A PV
Path 2
Decision(5)
Import
Rand
#
0.50
50
1 2 3
Random Number
Path 3
Illustration of probabilistic routing with Extend
15
Multiple Paths
L1
L
w
#
S u A1-3
p
245
R
p
DS A1-3
Rand
1 2
L2
L
?
w
3
#
S u A1-3
p
211
R
p
DS A1-3
1 2 A PV
Rand
L1
L2
L3
Max
Con
Min
Con
1 2
3
L3
L
w
S u A1-3
p
#
169
R
p
DS A1-3
Rand
1 2
3
Illustration of tactical routing with customers choosing the shortest line
16
Routing – Parallel Paths
Prepare invoice
Receive order
Ship order
Assemble order
Parallel activities in an order fulfillment process
17
Parallel Paths
Operation, Reverse block and dialog window
18
Parallel Paths
Operation block that batches two items
19
Parallel Paths
S u A1-3
DS A1-3
S u A1-3
Prepare Inv oice
S u A1-3
#
R
1 2 A PV
DS A1-3
Receiv ing Order
Q1-Q3
DS A1-3
S u A1-3
Ship Order
DS A1-3
Assemble Order
Extend model of the order fulfillment process
20
Processing Time
S u A1-3
20
17
DS A1-3
10
Slider control
21
Processing Time
Input Data block to model variable processing time
22
Processing Time
Processing time based on the value of the “ProcTime” attribute
23
Batching
Batch block and dialog window
24
Batching
Preserving uniqueness when batching a purchase order and an agent
25
Batching
Unbatching items with an Unbatch block
26
Batching – Resources
Model that batches patients and nurses
27
Activity-based Costing
Cost tab of the Import block
28
Activity-based Costing
Model to accumulate cost per unpacked crate
29
Activity-based Costing
Dialog of the Cost by Item block
30
Cycle Time Analysis
Two operations in series with a Timer block to measure cycle time
31
Cycle Time Analysis
Minutes
6
Avg. Cycle Time vs. Simulation Time
4.5
3
1.5
0
0
150
Av g. Cy cle Time Red
300
Simulation Time
Green
Count
450
600
Black
Histogram
175
131.25
87.5
43.75
0
0
Delay Time
Data
4.3
8.6
Cy cle times
Data
12.9
17.2
Data
Histogram of cycle times and average cycle time vs. simulation time
32
Model Enhancements
Rand
5
3.6
1 2
3
1
Slider control to set the mean value of an Exponential distribution
33
Model Enhancements
Meter connected to the utilization output of Labor Pool block
34
Model Enhancements
Clone layer tool
35
Case: Software Support
Incoming
Real-time
calls
Software
response
Engineer
Incoming
e-mails
Problems
Software
resolved
Engineer
Documented software support process
36
Case: Software Support
Simulation model of actual process
37
Case: Software Support
Simulation model of documented process
38
Case: Hospital Admissions
Floors
Type 1 Time
U(3,8)
Admissions
Registration
Desk
Time
U(2,5)
Types 2 and 3
Lab
Waiting
Room
Schematic representation of the hospital admissions process
39
Case: Hospital Admissions
Arriv ing patients and
ty pe 2 patients
returning f rom the lab
are merged
Patients arriv e
ev ery 15 minutes
D
Admitting of f icers
help patients
Orderlies accompany
patients to their rooms
#
Ty pes 1 and 2
M
33
Arriv als
sensor
Timer
Admissions
Patients ty pe 2 and 3
go to registration and
lab tests
Total number of
patients serv ed
Ty pe 3 patients
#
Activ ity
Stats
Update
Rooms
u
Ty pe 2 patiens
walk back to
admissions
Reg and Lab Ty pe 2 patients
Set P
P
Change priority f rom
ty pe 2 to 1.5
CD
Walk back
Extend model of the current admissions process
40
Case: Hospital Admissions
Set A
Get P

Rand
?
P
1 2 A PV
Y
Con1Out
N
A
#
2
Sy s
Var
1 2 3
Bef ore 10 AM
Rand
T
Current time
Patients arriv ing af ter
4 PM are sent to the
outpatient desk
1 2 3
Af ter 10 AM
Sy s
Var
Current time
Arrivals block from the admissions model
41
Case: Hospital Admissions
u
#
Patients wait f or an
admissions of f icer
CD
Ty pe 1
If patient is ty pe 2 or
3, go to the lab,
otherwise go to the
rooms
Rand
p
w
L
Con1In
R
p
Queue
a b c
a
b
c
demand
Get P
1 2
3

#
u
Get P
a
P
b
u
#
c
CD
Ty pe 2

Con2Out
demand
Rand
Pool of admitting
of f icers
Con3Out
P
1 2 3
#
u
CD
Ty pe 3
Rand
1 2 3
Admissions block from the admissions model
42
Case: Hospital Admissions
Patients f orm a line at
the registration desk
L
w
p
Patients wait f or a lab
technician
#
u
L
w
Ty pe 3 patients
leav e the process
#
p
u
Con3Out
Get P
Con1In
R
p
CD
Registration
R
P
p
CD
Waiting room
Rand
Rand
1 2 3
1 2

?
Y
N
Lab tests
Con2Out
Ty pe 2 patients
return to the
admissions desk
3
Registration and Lab block from the admissions model
43
Case: Hospital Admissions
Con3In
Pool of
orderlies
u
#
Orderlies and
patients walk to
the rooms
Orderlies and
patients are
batched
a b c
a
b
c
#
demand
CD
u
Orderiles and
patients are
unbatched
0.2
?
0.8
Walk to room
Rand
a
#
u
a
b
select
Con1Out
b
c
CD
demand
Wait f or papers
#
1 2 3
Orderlies walk back
to admissions
u
CD
Walk back
Rooms block from the admissions model
44
Case: Hospital Admissions
100
100.00%
90
80
80.00%
Frequency
70
60
60.00%
50
40
40.00%
30
20
20.00%
10
0
.00%
20
30
40
50
60
70
80
More
Cycl e time
Histogram of cycle times for type 1 patients
45
Case: Hospital Admissions
Patients arriv e
ev ery 15 minutes
Ty pe 1 and 2 patients
are merged
Admitting of f icers
help patients
D
Orderlies accompany
patients to their rooms
M
Ty pes 1 and 2
#
36
Arriv als
sensor
Timer
Admissions
Rooms
#
u
Patients ty pe 2 and 3
go to lab tests
CD
Ty pe 2 patiens
walk to wait f or
an orderly
Total number of
patients serv ed
Walk back
Ty pe 3 patients
leav e
Ty pe 2 patients
Lab tests
Extend model of the redesigned admissions process
46
Exercise 1
Type I
B
C
A
F
Types
II & III
D
G
E
Measuring cycle times of different types of jobs
47
Exercise 2
Type 1
A1
B1
C1
A2
B2
C2
A3
B3
C3
Type 2
Type 3
Investigating the effect of pooling resources
48
Exercise 4
Review &
Distribution
Underwriting
Rating
Policy
Writing
Assessing process performance
49
Exercise 7
D
0.8
A
C
E
0.2
B
F
Priority queues
50
Exercise 8
0.2
0.5
B
C
I
J
0.8
A
0.5
D
E
F
0.2
G
H
Flowchart for Exercise 8
51
Project: X-ray Process
10
1
2
3
4
5
6
7
8
9
12
11
25%
Flowchart for the X-ray process
52
Project: An Assembly Factory
Storage of
inbound
material
Parallel operations
(Workstations 1-3)
Assembly
(Workstation 4)
Painting
(Workstation 5)
Inspection
1
2
4
5
3
Rework
Flowchart of the production process
for the Assembly Factory
53