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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. Quiz non attributional. Activity AWAIT COLCT CREATE Entity TERMINATE QUE

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Chapt 6 Resources & Gates

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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


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___


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.


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


Uniform Distribution

  • Used to generate random numbers between a range.


Exponential Distributions

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


Normal Distributions

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


Triangular Distributions

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


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


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


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.


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.


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


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


Flex Machining System Ex

  • Under const


ALTER Node

  • Used to change the capacity of a resource type by CC units, + = increased, - = Decrease

  • Decrease resource BOOKS by 3


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


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


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


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


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


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”


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


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


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


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


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


Exercises

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


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.


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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