One More Try Another Example with Some Tweaks

Fall 2001IMSE 643 Industrial Simulation Two Job Types and a second Workstation Machine Inspection Arrivals Queue #1 Queue #2 Rework 10% Reject 10% Shipping 80% 1.Two Job Types (1 and 2) The inter-arrival time is exponentially distributed ~ expo(9) 30% of arrivals are Type 1 jobs – Priority =1 70% of arrivals are Type 2 jobs – Priority =2 2.Two Workstations: (Machine and Inspection) Machine: Type 1 jobs have first priority Processing Times: (Normal Distribution)

Fall 2001IMSE 643 Industrial Simulation Machine Center Mean Standard Deviation Type 15.0 min2.0 min Type 24.0 min1.0 min Processing Times follows Normal Distribution

Fall 2001IMSE 643 Industrial Simulation Inspection Center  Processing time follows Triangular Distribution  Serve based on Priority  Minimum possible inspecting time: 5 (min)  Most likely inspecting time: 8 (min)  Maximum possible inspecting time: 10 min  80% are good products  Shipping  10% are scraps  Rejection  10% need rework  machine with priority=3

Fall 2001IMSE 643 Industrial Simulation Rework Parts MeanStandard Dev. Type 13 min1 min Type 22 min1 min  Rework Parts have the lowest priority (3), same for both type 1 and type 2  Processing Times at Machine Center follow Normal dist.

Fall 2001IMSE 643 Industrial Simulation Simulation Requirements  Simulation time 480 min.  Count job finished for each type  Calculate average time a part spent in the system

Fall 2001IMSE 643 Industrial Simulation Describe the processes (1) 1. Create an Arrival ~ expo(9). 2. Assign JobType=1 or 2 (30% / 70%); Assign Status =1 ( ie. Regular part, not rework ); Assign Priority = JobType. 3. Waiting according to Priority for the machine to be idle. 4. Take possession of the machine. 5. Keep the machine for the time required to set-up and machining the job. 6. Release the machine for the next waiting job, if any

Fall 2001IMSE 643 Industrial Simulation Describe the processes (2) 7. Waiting according to Priority for the inspector to be idle. 8. Take possession of the inspector. 9. Keep the inspector for the time required to inspect the part. 10. Release the inspector for the next waiting job, if any. 11. Branch with the following outcomes: 80% good parts (go to step 12) 10% rejected parts (go to step 13) 10% rework parts (go to step 14)

Fall 2001IMSE 643 Industrial Simulation Describe the processes (3) 12. Count completed jobs by JobType and depart from the system. 13. Count the rejected parts and depart from the system. 14. Assign Status = 2 (i.e. Rework Part) Assign Priority = 3 and Go To Step 3.

Fall 2001IMSE 643 Industrial Simulation Attributes  Characteristic attributes, that are attached to and move with each entity  Special-purpose attributes: Pre-defined meaning with SIMAN e.g.M: Entity Current Station NS: Sequence # IS: Step #  General-purpose attributes: defined by users e.g. A(I)  Syntax: ATTRIBUTES: AttNo., AttName(Index), InitValue;  E.g. ATTRIBUTES: JobType, 1: Priority, 1: Status, 0;

Fall 2001IMSE 643 Industrial Simulation Variables  The set of changeable values characterizing the state or the components of the system.  Special-purpose variables: pre-defined by SIMAN (e.g. TNOW).  General-purpose variables: defined by users (e.g. V(I)).  Syntax : VARIABLES: VarNo, VarName(Index), InitValue;  E.g. VARIABLES: 1, Reorder Point: 2-11,StockLevel(10);  VARIABLES: Matrix(-3..6, 10);  VARIABLES: Mean(2, 2), 5,4,3,2;  VARIABLES: std(2, 2), 2, 1, 1, 1;

Fall 2001IMSE 643 Industrial Simulation Assign Values to Variables or Attributes  Block:  Syntax: ASSIGN: Variable = Value: repeats;  Ex. ASSIGN:JobType = Discrete(.3, 1, 1.0, 2): Status = 1: Priority = JobType; ASGIN VarNme = Value EXPO(30) Expo(30), 100

Fall 2001IMSE 643 Industrial Simulation Sample from a User-Defined Probability Distribution  Syntax: DISCRETE: (CumP1, Value1, CumP2, Value2, …);  Ex. DISCRETE(0.3, 1, 1.0, 2); f(X) X F(X) X

Fall 2001IMSE 643 Industrial Simulation Branch the flow of Entities in the System  In Step 11, 80% good parts (go to Shipping) 10% rejected parts (go to rejection) 10% rework parts (go to machine center)  Block:  Syntax: BRANCH, MaxTake: WITH prob., Lable: IF, Cond., Label: ELSE, Label ALWAYS label; Service time is a normal distribution Mean=10, std. Dev=4 During the operation the part stays in facility #2 Variable BRANCH, MaxTake WITH, Prob. IF, Cond. ELSE ALWAYS

Fall 2001IMSE 643 Industrial Simulation Sample Branches…  In Our Example Problem  To Duplicate the entities BRANCH, 1 WITH, 0.8 WITH, 0.1 Shipping Reject Machining BRANCH, 2 ALWAYS IF, TNOW < 10 Repeat WarmUp

Fall 2001IMSE 643 Industrial Simulation Count the Job Finished by JobType  COUNTERS: 1, Type1 JobDone: 2, Type2 JobDone: 3, Rejects;  (Step 12) ShippingCOUNT: JobType: DISPOSE;  (Step 13) RejectCOUNT: Rejects: DISPOSE;

Fall 2001IMSE 643 Industrial Simulation Collecting Statistics on Queues, Resources, and Time in the system  Data Types:  Observational Data:  Flow Time,  Cycle Time.  Time-Persistent Data  # of parts waiting in queue,  # of busy machine.

Fall 2001IMSE 643 Industrial Simulation Recording Time-Persistent Data: The DSTATS elements  Syntax: DSTATS: Number, Expression, Name, OutFile: Repeats;  Commonly used Time-Persistent Data:  NQ(QueueID) - # of entities in QueueID;  NR(ResourceID) - # of busy ResourceID;  MR(ResourceID) - # of Resource Available;  NSTO(StorageID) - # of entities in StorageID.

Fall 2001IMSE 643 Industrial Simulation Recording Observational Data: The TALLY Block  Example CREATE:Expo(8): MARK(TimeIn); DELAY:TRIA(5, 8, 10); TALLY:INTERVAL(TimeIn);  Examples TALLY: GroupSize, BatchSize; TALLY: TBDeparts, BETWEEN; TALLY: PartType, INT(TimeIn);

Fall 2001IMSE 643 Industrial Simulation Defining the Tally Records: The TALLIES Elements  TALLIES: TallyNo, TallyID, Outfiles: Repeats;  Example TALLIES: Time In System: TBDeparts, “c:\tbdepart.dat”  How do we do it in Arena – The “Statistics” element

Fall 2001IMSE 643 Industrial Simulation Recording Resource Untilization  For each Machine (Resource): DSTATS: NR(ResourceID)/MR(ResourceID)  In Example 2, assume that we would like to record the utilization of the inspector for each of the two job types.  We need to use different “storages” for different part type….

Fall 2001IMSE 643 Industrial Simulation Defining the storage records: The STORAGES Elements  Syntax: STORAGES: StorNo, StorName: Repeats;  Putting parts in different storages according to the JobType: DELAY: Duration, StorID;

Fall 2001IMSE 643 Industrial Simulation Example  For the Inspection section: QUEUE:InspectQ; SEIZE:Inspector; DELAY:TRIA(5, 8, 10), JobType; RELEASE:Inspector, 1; BRANCH, 1 with, 0.8, Shipping: with, 0.1, Rejection: with, 0.1, Rework;

Fall 2001IMSE 643 Industrial Simulation Also in the element definition  PROJECT, … ATTRIBUTES: …  STORAGES:1, InspType1: 2, InspType2;  DSTATS:  NSTO(InspType1), Inspect Type 1 Util: NSTO(InspType2), Inspect Type 2 Util: Collect Statistics Define Storages