Aspen Touch Solutions ATM-123R Series Specifikace stáhnout pdf (Strana 138)

3-54 Extension Unit Operations

3-54

3.10.2 ExtnUnitOperation

Interface

The ExtnUnitOperation interface must be implemented by all

Extension Unit Operations. Only two methods (the Initialize

method and the Execute method) are mandatory.

3.10.3 Passes

Execute Passes

The Solver performs steady state calculations in two passes: the

Forget Pass and the Calculate Pass. Normally, extension Unit

Operations need not know which pass is underway, but an

IsForgetting parameter is passed to the extension's Execute

method so the extension can optimize calculations if necessary.

The Solver propagates information through the flowsheet via the

Solver Notification links that are set up when connections are

made between objects. Whenever a Unit Operation changes the

value of a variable within a linked object, that object's Execute

method is called. If that object then changes the value of a

variable in another object, the Solver then moves on to that

object.

The propagation of information is completed when no object can

calculate any new information, or if calculated values are within

a tolerance of the value previously calculated. When new values

are within the tolerance, the linked object does not have its

Execute method called.

If two objects calculate the same value in to an object, and

these values are not within the tolerance, an Inconsistency

Derived from Properties Methods

IDispatch none • BasisChanged

•Execute

•Initialize

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Aspen Touch Solutions ATM-123R Series Specifikace Strana 138