Simulation ISYE 6644
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This 0 page Class Notes was uploaded by Maryse Thiel on Monday November 2, 2015. The Class Notes belongs to ISYE 6644 at Georgia Institute of Technology - Main Campus taught by Seong-Hee Kim in Fall. Since its upload, it has received 43 views. For similar materials see /class/234202/isye-6644-georgia-institute-of-technology-main-campus in Industrial Engineering at Georgia Institute of Technology - Main Campus.
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Date Created: 11/02/15
Arena Basics ISyE 6644 SeongHee Kim Georgia Tech Barry Nelson Northwestern Overview We now move to the design and analysis of dynamic systems that evolve through time We will use Arena from Rockwell Software which is one of several popular discreteevent simulation software packages SeongHee Kim 2 Arena World View Arena takes the process interaction world view Entities flow through a network of modules that describe their logical behavior We describe the network by developing a process flowchart SeongHee Kim Flowchart Approach SeongHee Kim 4 About modules Arena contains a very large number of modules that are organized into panels The panels are structured from high level to low level concepts Basic Process Advanced Process amp Advanced Transfer Blocks amp Elements a programming language Our goal is not to learn lots of modules but rather to understand concepts that allow us to learn new modules as needed SeongHee Kim 5 En es Entities are dynamic elements that pass through the system Entities are distinguished by their attributes Ex people parts information papenNork etc SeongHee Kim More on Entities Entities must be Created to get them into the model and are Disposed when theyleave Unfortunately attributes must be numerical values SeongHee Kim Queueing Entities queue when they need processing ln Arena An entity tries to Seize a Resource The time the entity uses the resource is the Delay If the resource is not available the entity waits in a Queue The entity Releases the resource when processing is complete SeongHee Kim 8 Resources Resources have A Name up to you A Capacity number of identical units of this resource think of servers And can have a Schedule how many available when And Resources can be animated SeongHee Kim More on Resources Resources are automatically defined by some modules eg Process Resources can be defined manually and the properties of all resources are changed via the Resources spreadsheet on the Basic Process panel There is also a Schedule spreadsheet for specifying Resource schedules SeongHee Kim 10 More on Queues Queues are created automatically by some modules eg Process and can be defined manually Properties of a queue including the ranking rule are defined via the Queue spreadsheet Firstin or Lastin first out Lowest or Highest attribute value first SeongHee Kim Basic Process Modules Create 1 IL 0 Push possibly batches of entities into the model with a possibly random time between Process 1 Models QueueSeize Delay Release of Resource or any part of this like pure Delay Make decisions about where to go next based on conditions or chance 939 l IX Dispose 1 Take entities out of the model and perhaps record statistics SeongHee Kim 12 Basic Process Modules Assign 1 l I Assign values especially Attributes when an entity passes through gt Record1 Record information when entities pass through typically statistics on entities r Batch 1 lgt fl Combine multiple entities into a single entity 39 I o J eparate l Origira Split multiple entities that were combined or duplicate a single entity SeongHee Kim 13 Create item m p I e entities note that The decision is 2 Random time way by chance between means with 90 chance Exponential of being true A E t B roken Items g 1 Repair u The delay can be given Act39on 395 se39ze39Delay39 by an expression in this Release to represent case Expoo 125 a queue exponential with mean 0125 SeongHee Kim 14 Basic Animation Entity movement via module connections and queues are automatically animated The entity movement does not correspond to the passage of simulated time Later we will learn how to animate transportation delays SeongHee Kim Entity Animation The Entity spreadsheet allows you to change the entity picture for each entity type The Entity Type is a name usually given when the entity is created Create Entity Type Items An Assign module can be used to change the entity Type or Picture as it moves through the model SeongHee Kim 16 Queue Animation The default queue is the sideways T be dragged anywhere or reoriented Often need to make the queue picture longer which has no effect on queue capacity The queue symbol can SeongHee Kim To lengthen the queue symbol select it grab the end and pull Resource Animation Clickin the resource l39 button lets you add a resource picture You select pictures for the Bus Idle Inactive and Failyed states The Identifier must be the name of a resource already in the model eg defined by a Process SeongHee Kim 18 Delays Arena gives a default distribution for time between creations Random Expo and delay Triangular If we want to put in a different distribution we select Expression and enter the appropriate Arena function such as WEIB POIS etc We often get the expressions from the Input Analyzer SeongHee Kim 19 SeizeDelayRelease SeizeDelayRelease need not be done in a single Process One Process may be used to Queue and Seize the resource a number of other modules may represent the processing and yet another Process may finally Release the resource SeongHee Kim 20 Example Use a SeizeDelay with delay 0 here to get a Cart resource m Use a DelayRelease with delay 0 to free up the Cart resource Free Cart l l 75 5 0 Tr GetCart i ltSplitbyPartType V 0 Each part type has a unique Process Two different entity types are Created Use the entity type in 2way by Condition decision SeongHee Kim 21 Internal Variables Arena keeps a number of internal variables continually updated These variables are useful for making choices in a Decide module displaying in animated plots or for recording statistics The basic syntax is NameQuantity SeongHee Kim 22 Basic Process Variables Create NameNumberOut Process NameNumbern NameNumberOut Name WIP Name WaitTime Decide Name NumberOut True NameNumberOut False Assig n NameNumberOut Batch NameNumberOut Separate Name NumberOut Orig Name NumberOut Dup Record NameNumberOut Dispose NameNumberOut SeongHee Kim 23 We can use the internal variable RepairWP to create a dynamic plot of the number of parts at the Repair Process Example SeongHee Kim 24 Simulated Time The simulation keeps its own internal clock that jumps forward from event time to event time The time on the simulation clock is accessible through the Arena variable TNOW TNOW is useful for marking entities or making timebased decisions SeongHee Kim 25 Batch and Split Entities are processed in a batch of size two and then the system split entities that were combined SeongHee Kim 26
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