IE 429IE 429Discrete Systems Discrete Systems

SimulationSimulation

Group 8: Extra CreditExample 5: Expression

Geoffrey CheungChris Guzman

Chris Mui

ExpressionsExpressionsAn expression element is an

element whose value is determined by referencing the expression name while the general term expression refers to a data type that defines the acceptable entries for a particular field.

Purpose of ExpressionWe use the expression module for

travel time when travel time is consistent throughout the process to help aid when doing a sensitivity analysis.

The analyst would only have to change one expression element as oppose to many within the system.

When there are many processes with travel times that are the same (e.g. travel time of expo(3) or expo(4)) then analyst will only need to refer to the expression element within the process.

Practice ExamplePractice ExamplePart A arrives to the facility one by one with

time between arrivals that are distributed exponentially with an average of 5 hours.

Part A goes through 4 different processes: welding (EXPO 5 hours), machining (EXPO 2 hours), paint (EXPO 3 hours), and inspection (EXPO 2 hours).

There is a travel time that is triangularly distributed with a minimum of .5 hours, maximum of 1.5 hours, and a mode of 1 hour before each process.

After the processes are completed, part A is sent to the warehouse. Run this model for 2000 hours.

Logical ModelLogical Model

Implement ExpressionsImplement Expressions

Steps to Implement Steps to Implement ExpressionsExpressions

Steps to Implement Steps to Implement ExpressionsExpressions

Results – Tally VariablesResults – Tally Variables Identifier Average Half Width Minimum Maximum Obs. _____________________________________________________________________________________

______________

PartA.VATime 15.948 .76470 5.4401 38.227 405 PartA.NVATime .00000 .00000 .00000 .00000 405 PartA.WaitTime 103.60 (Corr) .00000 243.07 405 PartA.TranTime .00000 .00000 .00000 .00000 405 PartA.OtherTime .00000 .00000 .00000 .00000 405 PartA.TotalTime 119.55 (Corr) 10.968 266.16 405 Inspection.Queue.WaitTime 1.6834 .73676 .00000 16.145 405 Machining.Queue.WaitTime 1.4772 .58827 .00000 17.815 408 Paint.Queue.WaitTime 6.2826 3.6648 .00000 59.525 407 Welding.Queue.WaitTime 95.265 (Corr) .00000 228.14 412

Results – Discrete Change Results – Discrete Change Variables Variables

Identifier Average Half Width Minimum Maximum FinalValue _______________________________________________________________________________________

__________ PartA.WIP 26.444 (Corr) .00000 56.000 46.000 Inspector Gadget.NumberBusy .42360 .06710 .00000 1.0000 .00000 Inspector Gadget.NumberScheduled 1.0000 (Insuf) 1.0000 1.0000 1.0000 Inspector Gadget.Utilization .42360 .06710 .00000 1.0000 .00000 Painter.NumberBusy .64789 (Insuf) .00000 1.0000 1.0000 Painter.NumberScheduled 1.0000 (Insuf) 1.0000 1.0000 1.0000 Painter.Utilization .64789 (Insuf) .00000 1.0000 1.0000 Welder.NumberBusy .98944 (Insuf) .00000 1.0000 1.0000 Welder.NumberScheduled 1.0000 (Insuf) 1.0000 1.0000 1.0000 Welder.Utilization .98944 (Insuf) .00000 1.0000 1.0000

Results – Discrete Change Variables

Identifier Average Half Width Minimum Maximum FinalValue

_________________________________________________________________________________________________

Worker.NumberBusy .39053 .06137 .00000 1.0000 1.0000

Worker.NumberScheduled 1.0000 (Insuf) 1.0000 1.0000 1.0000

Worker.Utilization .39053 .06137 .00000 1.0000 1.0000

Inspection.Queue.NumberInQueue .34090 .16101 .00000 6.0000 .00000

Machining.Queue.NumberInQueue .31169 (Insuf) .00000 8.0000 2.0000

Paint.Queue.NumberInQueue 1.2785 .74172 .00000 14.000 .00000

Welding.Queue.NumberInQueue 21.231 (Corr) .00000 53.000 39.000

Identifier Value ______________________________________________________

_______ PartA.NumberIn 451.00 PartA.NumberOut 405.00 Inspector Gadget.NumberSeized 405.00 Inspector Gadget.ScheduledUtilization .42360 Painter.NumberSeized 407.00 Painter.ScheduledUtilization .64789 Welder.NumberSeized 412.00 Welder.ScheduledUtilization .98944 Worker.NumberSeized 408.00 Worker.ScheduledUtilization .39053 System.NumberOut 405.00

Results - OutputsResults - Outputs