Describe the Simulation Environment Through Scenarios

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A scenario defines the simulation environment for a process. A simulation uses a single scenario with one or more process diagrams. You can have several scenarios in one file for running what-if simulations or variations of a process.

To view scenarios, click the View Scenario button on the Modeling toolbar.
or
On the File menu, choose Components and double-click the scenario or right-click and choose View.

The most frequently used sections in the Scenario are Run Setup, Generators, Resources, and the Schedules subsection under Calendars.

Run Setup Section: Set simulation timing and how the results of simulation are placed in a report

Expand the Run Setup section in the Scenario and double-click the text shown to display the Run Setup dialog box. The most important options are the Simulation Time tab and Initialization/Reports tab.

On the Simulation Time tab:

Control	Behavior
Mode (Calendar or Compressed) and Default Schedule	Use Calendar mode to have real-life calendar time, including evenings and weekends; Schedules with inactive time may be used. Use Compressed mode to only have active time. Default Schedule applies to Calendar mode. Set the default schedule used by Resources, Generators, etc. The default schedule can be overridden on each object that specifies a schedule.
Simulation Start	Specifies when the simulation starts (default Weekday rather than a specific date).
Simulation End	Specifies when simulation stops (default Transactions Complete). Most often you’ll want to set a specific duration for simulation (Custom). To set a custom end for simulation: Choose Custom from the drop-down list. Choose a duration time unit (for example, Hours). Enter a duration (simulation end) value.

Control

Behavior

Mode (Calendar or Compressed) and Default Schedule

Use Calendar mode to have real-life calendar time, including evenings and weekends; Schedules with inactive time may be used. Use Compressed mode to only have active time.

Default Schedule applies to Calendar mode. Set the default schedule used by Resources, Generators, etc. The default schedule can be overridden on each object that specifies a schedule.

Simulation Start

Specifies when the simulation starts (default Weekday rather than a specific date).

Simulation End

Specifies when simulation stops (default Transactions Complete). Most often you’ll want to set a specific duration for simulation (Custom). To set a custom end for simulation:

Choose Custom from the drop-down list.
Choose a duration time unit (for example, Hours).
Enter a duration (simulation end) value.

On the Initialization/Reports tab, specify how the simulation results are saved to the report (the default is Create New Report, so results are replaced each time a simulation runs).

Generators Section: Set up introduction of transactions into the process

Expand the Generators section and a Process (diagram) name in the Scenario, and then double-click the text shown, to display the Generators dialog box. During simulation, generators introduce transactions into the process. The most important option is Generator Type, which determines other data to specify. Common types are:

Generator Type	Behavior
Completion	Introduces one or more transactions into the process when the previous transaction or transactions have completed processing. If you specify a maximum, places one transaction or a group of transactions at a time in the process until transactions reach the maximum count (default Max Transactions: 1).
Demand	Introduces a transaction whenever the named resource (for example, Worker) is available or not acquired in the swimlane that has the Start activity for this generator.
Interarrival	Specifies the duration of time between transactions arriving in the process. You may start with a simple Constant or Distributed interarrival time. Constant: The same (constant) time between transactions entering the process. Distributed: The time between transactions entering the process is a range between two values. Expression: The expression can use math functions such as ExponDist() for exponential arrivals.
Event	Introduces transactions upon the occurrence of specific time event(s). Choose an Event from the list, or click the Bell (Event) icon to define your own event.
Timetable	Introduces transactions at specified intervals over a span of time. The table may be repeated. Click the Modify Timetable button to modify the timetable generator. On the bar chart, the X-axis shows the time intervals and the overall time span, and the Y-axis shows the number of transactions introduced during each interval. Values of interest are: Total Span: The total span of time covered by the timetable pattern given. For example, 1d (1 day) indicates that every day the given pattern should repeat. Time Resolution: The smallest interval of time unit of time in the bar chart.

Resources: Create, modify, and manage resources used by the process

Choose a task below and follow the corresponding procedure.

Task	Procedure
Add a resource type	From the Model menu, select Resource Types to access the Define Resource Types dialog box. Click to select a location for the new resource type in the expandable list on the left. Click the Add button. A new resource type appears under the one you selected. Type a name of the new resource type. (Do not use special characters or spaces. The “_” character is allowed.) Optionally, specify Summary and Purpose descriptions for the new resource type on the Properties tab. Click OK to save your new resource type definition.
Modify a resource	Double-click the Resources section in the Scenario to access the Define Resources dialog box. In the resource list on the left, select the resource. Click the Properties tab. If the resource Use value is Pool, specify the Count (number of that resource available to the process). On this tab, set the Schedule (when resources are available and inactive), cost (the Hourly Rate and Hourly Rate for overtime for the resource), Overtime, and Availability for the resource. Click OK to save your changes.

Task

Procedure

Add a resource type

From the Model menu, select Resource Types to access the Define Resource Types dialog box.
Click to select a location for the new resource type in the expandable list on the left.
Click the Add button. A new resource type appears under the one you selected.
Type a name of the new resource type. (Do not use special characters or spaces. The “_” character is allowed.)
Optionally, specify Summary and Purpose descriptions for the new resource type on the Properties tab.
Click OK to save your new resource type definition.

Modify a resource

Double-click the Resources section in the Scenario to access the Define Resources dialog box.
In the resource list on the left, select the resource.
Click the Properties tab. If the resource Use value is Pool, specify the Count (number of that resource available to the process). On this tab, set the Schedule (when resources are available and inactive), cost (the Hourly Rate and Hourly Rate for overtime for the resource), Overtime, and Availability for the resource.
Click OK to save your changes.

Schedules: Specify spans of active or inactive time

iGrafx provides several built-in schedules. See Calendars.