Process Activity Connections

A process model consists of one or more process activities. Each process activity represents a step in the process which is represented by one of the basic EPA Chapter 16 models (Charge, Heat, Purge, and others). Most of the process activities in the process are implemented in a specific sequence or order as governed by the process recipe.

Emission Master provides connectivity tools for helping to configure process activities to best represent the process recipe while at the same time providing support for subsequent changes that might need to be made in the modeling. For example, if the start time or duration of one of the steps in the process needs to be made later on then the connectivity tools help to ensure that the changes that are made to early in the process are reflected later in the process as well. In this way, if the charge time used in the 3rd step in the process is made then this change will be correctly reflected in the 50th step of the process.

The following descriptions are provided to help explain the differences that exist between the ways that process activities can be connected within a process model. The square with the red center represents the process activity being described.


	Leading or Disconnected - A leading or disconnected process activity is one that exist in the process but does not structurally follow any other process activity. The start time for this type of process activity may be assigned by the user as needed based on the process recipe. This process activity can exist in the process without any trailing process activities or it can have trailing process activities. If the user changes the start time or duration time of this type of process activity then the start time of all trailing process activities (if they exist) will be automatically adjusted.

	Sequence i - A simple sequence process activity (type I) is one that is preceded by one or more other process activities in the same sequence. The start time for this type of process activity is controlled by the preceding process activity. For example, if a change is made to the start time of the leading process activity of the sequence or the duration of any of any of the preceding process activities in the same sequence then the start time for this process activity will be recalculated. The duration of this process activity is set by the user.

	Sequence ii - A sequence process activity (type ii) is exactly the same as the sequence process activity (type i) in that it is preceded by one or more other process activities in the same sequence. The start time for this type of process activity is controlled by the preceding process activity. If a change is made to the start time of the leading process activity of the sequence or the duration of any of any of the preceding process activities in the same sequence then the start time for this process activity will be recalculated. The duration of this process activity is set by the user. However, a type ii shares the same preceding process activity of a type i.

	Concurrent - A concurrent process activity is one that is set to have the same start time as another process activity. The start time for this type of process activity is set by the process activity that it is connected to. If a start time change is made to the controlling adjacent process activity then a similar start time charge will be made to concurrent process activity. A concurrent process activity is very similar to a simple sequence (type i or type ii) process activity. However, one difference is that a simple sequence process activity must follow a preceding process activity while a concurrent process activity must have the same start time as the process activity that it is connected to.