Chapter 6 Simulating a Business Process Model


SIMUL8 basics

The main objects in SIMUL8 are the following:

SIMUL8 objects Description
Work Center Place where work takes place on work items. Work items can be transformed by work centers (they can be updated, split or merged)
Work Item Representation of a work being performed in the organization. For a factory process it is the product, for a hospital process it is a patient, and for a purchase order process it is the order. This object does not appear in the diagram except on simulation execution where potentially several work items transit through the flows
Work Entry Point A work entry point is a place where work to be done is displayed in your simulation for the first time. You can have as many work entry points as you like. Each can feed in work using different statistical distributions (if required). Each can feed in Work item of different types (if required)
Work Exit Point A work exit point is a place where work that is complete leaves your simulation. At the point in time when each work item leaves, data is recorded about how long it has spent in the simulation (from the time when it entered through a work entry point)
Label Labels can be attached to any work item going through the simulation. For example you might attach a label "Illness" to work item type "Patients" and set this label to a code number as they enter your simulation of a hospital. Each code number would represent a type of illness and could be used to route the patients through the different work centers in the simulation.

Labels can:

  • Contain either text or numbers
  • Be used to tell work centers, which distributions to use for defining work times
  • Be used to prioritize work items as they enter a queue
  • Be used to route a work item depending on label value (route out Discipline property = Label)
  • Be used to control the image that is used to display the work item on the screen
  • Be used to batch work together as it enters a work center
Route In / Route Out Flows between work centers are not objects. The work center contains route in or route out properties for each input or output flow.

Route in properties: (example: selection method: circulate, priority, collect, passive...) to control where a work center gets the work items that it performs tasks on

Route out properties: (example: discipline: circulate, percent, ...) to control where work items should go next after being at a work center
Queue A queue is a place where work to be done can wait until appropriate resources or work centers are available
Resource Items that are required by work centers to work on work items. Work centers cannot start work until both a work item is available and the specified resources are also available.

Resources are shared between all the work centers that use them.

Each type of resource has a number of available resources.

A pooled resource is one resource that does not really exist but instead is a combination of other resources.

If task A can be performed by people A and task B can be performed by people B and task C can be performed by either A or B people then create a pooled resource called C and use the Pooled check box in the resource dialog and button to set that either A or B can be used whenever a work center is seeking resource type C
Clock Time Units: Seconds, Minutes (by default), Hours, Days, or Simple unit count from zero (= no unit).

For units smaller than seconds use decimals of units: 0.001 = 1 millisecond.

Other properties: Start time each day, Time in each day, Days per week, Warm up period, Results collection period, Running time (this is the simulation duration: default value = 2400)
Sub-Window With a complex simulation you may want to summarize your simulation at different levels. You do this, using sub-windows and sub-windows within sub windows to any level of depth you require.

You drag a rectangle around the objects symbol you would like to include in the sub-window, then right-click the rectangle and select the Create Sub-Window command. The group of symbols is replaced with a sub-window containing the symbols, plus an icon (hidden by the sub-window).

A sub-window can contain other sub-windows.

You can close the sub-window, and then re-open it by double-clicking the icon
Component You must select a group of objects, then right-click the Create Component Type command. The selected objects become sub-objects, and a new component is created.

If you save the component as a reusable component (via Component Properties→Toolbar→Save As Reusable component), a new tool is added in the toolbar2. When you use the New Component tool, the component and its sub-objects are duplicated, not reused.

A Component can contain other components.

To display the sub-components: (for example, to see the results of each sub-object after a simulation) in the property sheet of the component, you must click the Graphics button and deselect the Hide Sub-Objects checkbox. The component icon itself can be hidden. The command Objects→Advanced→Components→All allows you to redisplay the component properties

 


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