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Chapt 5 Basic Network Modeling

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Chapt 5 Basic. Network Modeling. Intro/ steps in the process. Single server queuing system ... Entities flow thru process ie items ... – PowerPoint PPT presentation

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Title: Chapt 5 Basic Network Modeling


1
Chapt 5 Basic Network Modeling
  • Intro/ steps in the process
  • Single server queuing system
  • CREATE Node
  • TERMINATE Node
  • ASSIGN Node
  • GOON Node
  • COLCT Node
  • SELECT Node
  • EXAMPLES

2
Introduction
  • Using process orientation
  • What detail to represent
  • How to represent detail
  • Will want to iteratively develop model
  • Use graphic symbolsie FBD

3
Introduction of a simple queue
  • Items arrive, wait, processed than depart
    system..ie a process
  • Entities flow thru process ie items
  • Entities are assigned attributes values that
    distinguish it ie time entered a system
  • Resources are what entities complete while
    flowing thru system ie servers, tools etc
    (busy/idle)
  • Use graphic symbols of SLAM to represent

4
Inspect Radios simple queue
  • Radio arrives _at_ inspection area
  • Queue of radios
  • Activity of the Inspection of radio
  • Inspected radio departs system

Queue of Radios
Arriving Radios
Inspection station
Inspected Radio
5
Modeling Queues servers
  • Passage of Time is represented by a branch
  • Waiting occurs at queue

IQ Initial Number in queue QC Max number in
queue IFLFile for storing waiting entities
Service Activity
IQ
IFL
QC
N
6
Modeling Arrival of Entities
  • Generates entities into the system
  • TF Time for First entity to be created
  • TBC Time Between Creations of entities
  • MV Variable to contain Mark time time entity
    was created
  • MC Max of entities created
  • M Max of branches

TBC
MV
M
MC
TF
When is 2nd entity created?
7
Modeling Departure of Entities
  • Entities leave the system
  • TC of entities arrivals to halt the analysis

8
Inspect Radios simple queue
  • Radio arrives _at_ inspection area
  • Queue of radios
  • Activity of the Inspection of radio
  • Inspected radio departs system

Queue of Radios
Arriving Radios
Inspection station
Inspected Radio
9
Combine Modeling Concepts
Take branch 1
TF7
of entities to terminate a run
Service time
9
200
3
1
Queue Node
parallel servers
Activity or server
10
Create Node
  • Create, TBC,TF,MV,MC,M

TBC, time bwtn EXPON(1) TF, start time 0 MV,
mark time goes in attribute 1 MC, entities
created infinite M, of branches is 1
11
Queue Node
  • Queue (IFL),IQ,QC

IFL, file 1 IQ, Initial in queue 10 QC,
queue capacity 20 Balk-entity routed to another
node in network Block-entity waits for free space
Queue called Awaitpaint
Hash mark for Queue
12
Terminate Node
  • Terminate, TC (IFL),IQ,QC

TC, termination count of entities to process
until stop, infinite
Called Finished
13
Assign Node
  • Used to prescribe values to the attributes of an
    entity passing thru an ASSIGN Nodeduration of
    activities based on assigned values
  • ASSIGN, VAR, VALUE, Repeats, M

of branches
P
2
5
10
The value of attribute 3 is assigned a value
based on a triangular distribution
Node Label/ name
14
Activities
  • Branches used to model activitiesspecific time
    delays prescribed of entities flowing thru
    network
  • ACTIVITY,A,DUR,CONDITION,NLBL,N,ID

A activity , DUR duration, NLBL end node
label if end node is not listed, N of
parallel servers, ID activity id
Condition
Duration
Activity
15
2 Parallel Servers Example
  • Create bank customers using exponential
    distribution start at 5 mins (10mean), initially
    2 entities in queue, max 10, 2 tellers in
    parallel, service time is uniform distribution
    btwen 6-12 mins, end sim when 100 entities have
    been processed.

2
16
Conditional Probabilistic Branching
  • Probability of a condition determines which path
    to take, ie from inspection 90 go to packing
    10 fail inspection, get reworked then back to
    inspection

Whats wrong?
17
GOON Node Go - on
  • A continue node to assign direction or new
    attribute in series or parallel, can assign
    conditions

18
COLCT Node Collect data/ statistics
  • Used to show mean, std dev, produce histograms
  • Example used to collect statistics on the
    completion time of a project, no histogram
    required, one branch from this node

Label
19
COLCT Node Collect data/ statistics
  • Example used to collect statistics on the
    completion time of a project, histogram required,
    20 cells, width of 5, 1st cell is -infinity to
    10, also 5 branches form this node

Label
20
Control Statements
  • Provide info about the simulation experiment, 3
    minimum statements, General, Limits Finsih
  • General GEN, NAME, PROJECT, DATE, NNRNS NAME
    OF MODELER, P TITLE, DATE, OF RUNS
  • Limits LIM, MXX, MLL, MSZ, MATRIB, MLTRIB,
    MSTRIB, MNTRY set max values for variables XX,
    LL, SZ, Attributes M, ML, MS largest of
    concurrent entities expected
  • Finish FIN end of visual slam statements

21
TV Production Ex
  • TVs in a production line get inspected, go to
    packing or need to be adjusted

Packing
Arriving TVs
INSP
Fixed TVs
22
TV Production Ex
  • TVs in a production line get inspected, go to
    packing or need to be adjusted

23
Select Node
  • Select are decisions on the routing of an entity,
    specify a Queue Selection Rule (QSR) or Server
    Selection Rule (SSR)

Longest idle time from server
Largest Average from Q
Select looks ahead to choose direction
24
Exercises
  • 5-1 pg 157 develop a portion of the network which
    the time to traverse an activity is normally
    distributed with a mean of 10, std dev is 2, a
    min value of 7 and max value of 15

25
Exercises
  • 5-1 pg 157 develop a portion of the network which
    the time to traverse an activity is normally
    distributed with a mean of 10, std dev is 2, a
    min value of 7 and max value of 15

26
Chapt 5 Basic Network Modeling
  • Intro/ steps in the process
  • Single server queuing system
  • CREATE Node
  • TERMINATE Node
  • ASSIGN Node
  • GOON Node
  • COLCT Node
  • SELECT Node
  • EXAMPLES
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