Final Presentation Mod Sim

8/6/2019 Final Presentation Mod Sim

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Final Presentation:Final Presentation:

Servicing a carServicing a car

Presentation By:



ObjectiveObjective

y Determine the average total service time

(simulation time) experienced by

customers in the reservation queue and

the no reservation queue

y Parameters are reservation or no

reservation and service time



System Model:System Model:

Entities and AttributesEntities and Attributes

Generator ² Poisson Distribution for Arrivals (random &memory less)

Sorter - Sorts arrivals into reservation queue or reservationqueue

Mechanic 1 (Reservation Queue) ² Deterministic Servicetime Distribution

Mechanic 2 (No Reservation Queue) ² Exponential Servicetime Distribution

Experience more total delay in no reservation queue than inthe reservation queue

Departure Sink ² Customers depart, exit simulation

Poisson Distribution: Probability of number of events occurring in a fixed period of time if these eventsoccur with a known average rate and independent of the time since the last event.




Block DiagramBlock Diagram




EventsEvents1) Vehicles arrive to sorter

2) Vehicles depart sorter sorted into

Reservations queue or No Reservations

queue4) Vehicles arrive to Mechanic 1 (Reservation

queue) get serviced immediately

5) Vehicles arrive to Mechanic 2 (No

Reservation queue) wait in queue for service

until mechanic is free

6) Vehicles Depart from Mechanic 1 and exit

simulation

7)Vehicles Depart from Mechanic 2 and exit

simulation



System ModelSystem Model

Flow Diagram Service forFlow Diagram Service for

CustomersCustomers




Stochastic ComponentsStochastic Componentsy Distinguish between customers with

reservations and no reservations

y

New vehicles joining the system and vehiclesleaving the system.

y Customers choose to have a reservation ornot

y Customers will require the service atunpredictable times

y Service time for each customer varies and isnot constant




DistributionsDistributionsy

Poisson Dist. (for arrivals) Models the number of random

memory less arrivals in a giventime interval.

Models the amount of people thatarrive with an average rate.

(1cust/5min) & (1cust/15min)randomly

y Deterministic Dist. (forreservation queue) Because cars are serviced only in

15 minute blocks Queue Type: M/D/1

y Exponential Dist. (for noreservation service) Because cars are serviced

randomly between 12-15 minutes

Queue Type: M/M/1



Simulation DemoSimulation Demo



Actual Results & Interpretation with workingActual Results & Interpretation with working

simulationsimulation48 customers/ open

20hours

Reservation

(min)

No Reservation (min)

Mean Delay 1.96 9.82

Max Delay 3 15

Delay Standard Deviation 0.82 4.33

Delay Variance 0.687 18.7

Mean Service Time 13.63 13.63

Max Service Time 15 15

Service Time Standard

Deviation

1.14 1.14

Service Time Variance 1.30 1.30

Total Service Time §15.59 §23.45



Results & interpretationResults & interpretation

y So customers who have a reservation

experience less total service time in the

system than customers who don·t have a

reservation

y Customers who don·t have a reservation

experience approximately 10 min of delay

making it better to make a reservation



VerificationVerification

y We switched the generator to only generatemessages with reservations and checkedboth sinks. Sink 1 had received messages

Sink 2 had noney We did the same for no reservations and

checked both sinks. Sink 1 had receivedmessages Sink 2 had none

y We ran the generator with randomlygenerated messages and both sinks hadresults.



ValidationValidation

y Compared to the data sets found in

research for maintenance of automobiles

the data is consistent

y Average time to change oil and do an

inspection is 12-15 minutes without wait.

y http://autorepair.about.com/



ReferencesReferences

y Course Notes

https://elearn.stevens.edu/webct

y Omnet ++ & Manual, User Guidehttp://www.omnetpp.org/documentation

y http://www.edmunds.com/how-to/how-to-change-your-oil-the-real-down-and-

dirty.html?articleid=43788y http://autorepair.about.com/

y Minitab & Excel

Documents

Final Presentation Mod Sim