Chapter 4
Modeling Basic Operations & Inputs
 1 
Outline
 detailed
operations
 Model
04-01
 Model 04-02
 Model 04-03
 Model 04-04
 general
usage of ARENA
 2 
A Sequence of Related Models

Model 4-1: a sealed electronic assembly and test
system
 more features,
 Model
4-2: additional features in scheduling,
failure, and states of resources
 Model 4-3: more advanced animation
 Model 4-4: advanced features in moving –
stations, routes, and animation
 3 
An Electronic Assembly/Test System
Part A
EXPO(5)
Process A
Tria(1,4,8)
Scrapped
Part A
TRIA(1,3,4)
20%
Rework
Part B WEIB
(2.5, 5.3)
EXPO(45)
9%
Sealer
80%
Salvaged &
Shipped
Part B
Process B
91%
Batches of 4
EXPO(30), de- Tria(3,5,10)
batch on arrival
Shipped
 4 
An Electronic Assembly/Test System
Part A
EXPO(5)
Process A
Tria(1,4,8)
Scrapped
Part A
TRIA(1,3,4)
20%
Rework
Part B WEIB
(2.5, 5.3)
EXPO(45)
9%
Sealer
80%
Salvaged &
Shipped
Part B
Process B
91%
Batches of 4
EXPO(30), de- Tria(3,5,10)
batch on arrival
Shipped
processes
type-dependent
unreliable
system
create batches
service
times chance
create
entities
of 4 the
entities
&
to determine
number
of racks statistics
de-batch later
 5 
Model 04-01
 ignore
details
 the
2-minute traveling times
 the working hours of stations
 schedule of the re-workers
 failure of the sealer
 the number of racks used
 6 
Remarks for Model 04-01
 two
types of entities
 entity-dependent service time: an attributes of
an entity: a local variable of the entity
 time in system: marking the time entering the
system
 chance: conditional routes
 type dependent statistics: record mechanism
 7 
Model 04.02
 8 
New Features of Model 04-02:
Refinements of Model 04-01

run length 10 days, 16 hours per day

two 8 hr shifts / day


1 re-worker in the first shift

2 re-workers in the second shift
sealer may break down

life time expo(120)

repair time expo(4)

statistics of the status of sealer: on and off

statistics of the rework queue (distribution of # of racks)

each rack possible to hold 10 items
 9 
Schedule of the Rework Station
 run
length: Setup menu
 variable resource
 define
schedule of re-workers (Schedule module)
 modify
the # of hours per day to suit the schedule
 associate
the schedule with the (resource of the)
re-work station
 option
on resource when a service is interrupted: ignore,
wait, preempt
 10 
Failure of Resource
 failure
of the sealer
 define
a failure (Failure module in Advanced
Processes)
 associate the failure with a resource
 the treatment of incomplete work at a failure
 same
as schedule: ignore, wait, and preempt
 11 
Collect Statistics
 statistics
 time
in system: customer average
 sealer:
 rack:
state dependent, time average
number of rack needed, time average
 12 
Collect Statistics


to get time-in-system statistics of a type of entities
(customer-average statistics)

use Record module

record exit time - creation time

compile statistics
to get time-persistent statistics of a collection of values of
variables or a collection of states of resources

use Statistics module (in Advance Process Template)

may need to self-define categories
 13 
Statistics for Racks and for Sealers

time-persistent statistics – Statistic module

statistics on sealer status

 fraction
of idle, failed, and busy time of sealer
 statistic
type: frequency (not time-persistent)
statistics on number of racks needed
 fractions
 statistic
of time for different number of racks used
type: frequency (not time-persistent)
 14 
Instantaneous Utilization
and Scheduled Utilization
 for
a resource, let
 B(t)
= # of units of the resource busy at t
 M(t)
= # of units of the resource available at t
 instantaneous
utilization
T B( s)
0 M ( s ) ds
T
 scheduled
utilization
T
0 B( s) / Tds
T
0 M ( s) / Tds
 15 

T
0 B( s)ds
T
0 M ( s )ds
Model 04.03
 16 
New Features of Model 04-03:
Refinements of Model 04-02
 animation
 length
of queues
and points of queues
 changing
 creating
entity pictures
new one: copy, edit, and assign entity
picture
 adding
resource pictures
 creating
 adding
resource picture from animation tool bar
variable plots
 17 
Model 04.04
 18 
New Features of Model 04-04:
Refinements of Model 04-03

saving connection links by station and route modules

stations: module for program and icon for animation

route: module for program and link for animation

possible to have multiple station icons in animation for one
location


two station icons between one route link in animation
changing an entity picture: by an Assignment Module
 19 