 1  Outline  world view of simulation  overview of ARENA  simple ARENA model: Model  basic operations: Model 04-01

 2  World Views of Simulation  discrete-event approach  application: systems with well-defined event times  modeling: definition of variables and events, including their interaction  characteristics  more suitable for discrete-event systems  requiring knowledge for users  activity scanning approach  application: systems where activities duration are defined by interaction of variables and events, e.g., system dynamics  modeling: definition of variables and their interaction  characteristics  more suitable for continuous-event systems  requiring knowledge for users

 3  World Views of Simulation  process orientation approach  modeling: definition of the processes as experienced by entities  characteristics  minimum knowledge from users  applicable to both discrete- or continuous-event systems  only discrete-event approach being considered here

 4  Process Oriented Simulation Languages  fixed number of “work stations”  fixed types of “entities”  possibly to have infinite supply for a type of entities  “process” as experienced by each type of entities

 5  Process Oriented Simulation Languages “work stations”: “entities”: “processes of entities”:  for each station, specify  its characteristics  rules of operations  for each process of a type of entities, specify  the routing  the “treatment” at each station

 6  Process Oriented Simulation Languages  process oriented approach: experienced of entities  for entities  routing, including rules to select stations  time and resources for service at stations  time and resources for moving around stations

 7  Process Oriented Simulation Languages  for stations  the arrival process: inter-arrival time, number of arrivals batch, any dependency of inter-arrival times, etc.  the service process: number of service servers, service time distributions, any dependency of service times, resources for service  the queueing discipline: number of queues, priorities adopted in queues, rules to assign waiting customers to available servers  miscellaneous issues: waiting space, walking distance from queue to servers, type changes of customers, etc

 8  Process Oriented Simulation Languages  from processes typed in  an underlying discrete-event (or activity scanning in applications not in this course) program being generated  good support in statistical analysis, reporting, and animation  ARENA: process oriented simulation package  pretty flexible, possible to  model in other approaches  interact with Spreadsheet, programming langagues

 9  Process-Oriented Portion of ARENA  components of the process  arrival  service  characteristics of stations  service time  resources required  priority of customers in queues (to take resources)  rules for customers to direct to queues

 10  Process-Oriented Portion of ARENA  components of the process (con ’ t)  transportation  moving as a time delay  moving that requires equipment  moving according to routes  others  schedule of resources  capacity changes of resources  up and down times of resources

 11  ARENA  to learn how to learn  c:\Program Files\Rockwell Software\Arena7.0  useful folders: Online Books, Book Examples, Examples, SmartsOnline BooksBook Examples ExamplesSmarts  Help in ARENA  Templates of ARENA Templates of ARENA

 12  Trade off of Flexibility in Modeling and Convenience in Applications flexibility in modeling convenience in application

 13  Model Model GI/G/1 Queue Model  a drill press processing one type of product  interarrival times ~ i.i.d. exp(5)  service times ~ i.i.d. triangular (1,3,6)  all random quantities are independent  simulation: 20 time units a drill press one type of parts; parts come in and are processed one by one

 14  Model  to introduce  arrivals: Create Module  service: Process Module (resource)  departure: Dispose Module  Expression Builder – right click mouse  menu option: Setup  graphic library

 15  Desirable Features  to introduce  automatic plotting number in queue, etc.  animation icon for resources: Resource Picture Placement Dialog  (click Resource Animation icon)  open new icon library.plb  association of icon to resource  animation icon for entities: Entity Pictures (Edit menu)

 16  Desirable Features  report  WIP = Drill Press.Queue + Driller Instantaneous Utilization  difference between Instantaneous Utilization and Scheduled Utilization  difference between waiting time in Drill Press.queue and Wait time of entity

 17  To Understand the Report  GI/G/1 queue with service times = 1 unit  interarrival time = 1.5 units  interarrival times = 0.8 units

 18  Inconvenience of the Process-Oriented Approach  the protocol: not suitable for all cases  how to define entities for  a Newsboy problem  critical path method in project management  integration  possible to have entities for conceptual, logical, not physical flow

 19  Chapter 4 Modeling Basic Operations & Inputs

 20  Electronic Assembly/Test System Sealer Part A EXPO(5) Part B Batches of 4 EXPO(30) Process A Tria(1,4,8) Process B Tria(3,5,10) Part A TRIA(1,3,4) Part B WEIB (2.5, 5.3) EXPO(45) Rework 9% 91% Shipped 20% Scrapped 80% Salvaged & Shipped

 21  type-dependent service times Electronic Assembly/Test System Sealer Part A EXPO(5) Part B Batches of 4 EXPO(30) Process A Tria(1,4,8) Process B Tria(3,5,10) Part A TRIA(1,3,4) Part B WEIB (2.5, 5.3) EXPO(45) Rework 9% 91% Shipped 20% Scrapped 80% Salvaged & Shipped create entities create batches of 4 entities processes chance statistics time varying capacity unreliable system to determine the number of racks

 22  Models  Model 4.1: basic  Model 4.2: resource schedule, resource failure, frequency – time persistence statistics  Model 4.3: changing animation queue, changing entity picture, adding resource picture, adding variables and plots

 23  Model Model  ignore details  the 2-minute traveling times  the working hours of stations  schedule of the re-workers  failure of the sealer  the number of racks used