Chapt 6 Resources & Gates

1. Chapt 6 Resources & Gates • Intro/ steps in the process • Distributions...What & Why • Resource Block • Await Node • Free node • Alter node • Group block • Open Node • Close node • Examples

2. Quiznon attributional Activity AWAIT COLCT CREATE Entity TERMINATE QUE ATRB NNQ GOON • Object flow thru network_________ • Node that is an entry point in to a system______ • Data attached to an entity________ • A symbol that can represent the passage of time____ • Node that generates a histogram______ • Node that represents people or item waiting in line___

3. Quiznon attributional • Hand draw tonight….Turn next week a printed version sing AweSim software, a single server operation of a 7-11 store using AweSim objects, customers arrive at the counter at a rate that is Exponentially distributed with a mean of 4.5 minutes, the duration of the service time is normally distributed with a mean of 3.2 minutes and a standard deviation of 0.6 minutes, end the simulation after 1000 customers. Collect data to be able to produce a histogram of how long customers are in the system.

4. Distributions • Use statistical distribution to represent your data or when an approximation is required. • Want to simulate arrival times of customers can either: • Collect data, use real data…must collect vast amounts • Collect representative sample of data, use distribution that best represents the data for the population • Have little or no data and make rough approximations of the expected population

5. Uniform Distribution • Used to generate random numbers between a range.

6. Exponential Distributions • Used to represent the arrival or service time time of random variables. Also used to represent time to failure.

7. Normal Distributions • Use statistical distribution to represent your data or when an approximation is known. Commonly used for service times.

8. Triangular Distributions • Used when only an approximation of the population is known. Used for service times.

9. Introduction • Entities move thru the network…waits at ques…encounters activities that take time… • Can also model networks where the entity requires a resource to perform an activity • Entity picks up resources at an AWAIT Node before going on to an activity • Resource block dictates the priorities of resources • Gate Nodes start & stop entity flow

10. RESOURCE Block • Block = entities do not flow thru, no in/ out • Identifies: resource name/ label = RLBL, initial # of resource units available = CAP, order which to AWAIT & PREEMPT allocate resources • Resource # 1, called ScrapeMetal, capacity of 1000, files 3 & 7 will be polled for entities waiting for ScrapeMetal

11. AWAIT Node • Used to store entities waiting for units of resources or a GATE to open • AWAIT Node called Needbooks, entity requires 2 units of the resource BOOKS, if available they are allocated to the entity & branches M=1, no limit for # of entity that can wait in file 1.

12. AWAIT Node • AWAIT Node called Needbooks1, # of books required by entity is prescribed by the value of attribute (4), if available they are allocated to the entity & branches M=2, no limit for # of entity that can wait in file 1.

13. FREE Node • FREE Node used to release units of resources when entity arrives at the node • Node called Freeupbooks, 4 BOOKS are made available when entity arrives

14. Inspector considered as a resource Ex • TVs in a production line get inspected, go to packing or need to be adjusted, inspector also does adjustment, can’t be used for insp when performing adjust

15. Flex Machining System Ex • Under const

16. ALTER Node • Used to change the capacity of a resource type by CC units, + = increased, - = Decrease • Decrease resource BOOKS by 3

17. Group Block • Provides a method of grouping resources so that any member of the group can be used to provide service to an entity • 3 examples of Group resources of BOOKS, Pencils, Packs L IDLE FM PREFERRED ORDER NEXT FREE

18. PREEMPT Node • Similar to AWAIT but an entity can preempt one unit of a resource that has been allocated to another entity • High priority to preempt 2 units of resource Books put remaining resource in attribute 2

19. Machine tool w/ breakdowns Ex • Parts are sent to Drill, Drill machine breaks down, which stops the processing of parts except by hand. Drill is modeled as a resources & parts require one unit of Drill. An entity representing Drill status is modeled in a disjoint network, delayed by time to failure, after which the Drill status arrives to a PREEMPT node. PREEMPT stops drilling by Drill, the part is drilled by hand & it takes twice as long

20. Parts are sent to Drill, Drill machine breaks down, which stops the processing of parts except by hand. Drill is modeled as a resources & parts require one unit of Drill. An entity representing Drill status is modeled in a disjoint network, delayed by time to failure, after which the Drill status arrives to a PREEMPT node. PREEMPT stops drilling by Drill, the part is drilled by hand & it takes twice as long Byhand PREEMPT

21. GATE Block • Provides a method of grouping resources so that any member of the group can be used to provide service to an entity • Ex LABELEDGATE is open, file # 1

22. OPEN Node • Used to open a gate with a gate label (GLBL) or gate code specified by an expression • Ex Open gate, called “Exampleopengate” is used to open gate “gatetomtl”

23. CLOSED Node • Used to close a gate with a gate label (GLBL) or gate code specified by an expression • Ex Close Gate, closegate, closes gate called, closetofuel

24. Gates to Model Shifts Ex • Model the activity of a process only in operation during the day shift. Entities arrive and routed to an AWAIT node that is associated with the gate called dayshift. In a disjoint network an entity is created that closed the gate after 8 hours and opens it 16 hours later

25. Model the activity of a process only in operation during the day shift. Entities arrive and routed to an AWAIT node that is associated with the gate called dayshift. In a disjoint network an entity is created that closed the gate after 8 hours and opens it 16 hours later Close gate Open gate

26. Exercises • 6-2 two types of customers 1) regular, uniform distributed btwn 15-20 min, 2) harder, expon distributed , mean = 20 min. 60% are regular customers, 40% harder. Customers arrive at a rate represented with a triangular distribution min = 10, max = 50, mode = 20. Find statistics that represent time in system, Use AWAIT/FREE Customer in Customer Serviced Customer out

27. Exercises 6-2 two types of customers 1) regular, uniform distributed btwn 15-20 min, 2) harder, expon distributed , mean = 20 min. 60% are regular customers, 40% harder. Customers arrive at a rate represented with a triangular distribution min = 10, max = 50, mode = 20. Find statistics that represent time in system, Use AWAIT/FREE

28. Exercises • Person arrives at bank cant find parking drives around block comes back parks.

29. ExercisesDue Monday 10/29 • 6-9 Machine tool processes 2 diff parts. T1 arrival time is tri dis 20-30-50. Interarrival time of T2 tri dis 35-50-60. Processing time for T1 is exp, m=20, T2 uniform min 15- max 20. Processing includes inspection, 1% fail, return to que the rework time =90% of original. Find time in system of part & utilization of machine. Use create/ await/ a conditional split of activities/ free/ collect/ terminate.

30. 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