STEM help / Data dialogs

Transformation / Time Lag

A Time Lag transformation may be selected from the Type menu in the Input and Transformation dialog. A Time Lag Transformation allows you to model demand which depends on something which has happened in an earlier year, based on a single Input and an integer Time Lag input, which represents the number of years delay.

These inputs are accessed via the Input and Transformation dialog.

Output Unit

Select the output unit that you want to use from the drop-down list box, or define your own. The selection has no effect on the model but is used in results graphs.

Default: none.

Features See Multiplier Transformation, Transformations.

Multiplier (2)

Multiplies the Input of a Transformation to calculate its Output.

Default: Constant {1.0}.

Features See Multiplier Transformation, Transformations.

Time Lag

Time Lag

The number of years delay between the Input to a Time Lag Transformation and the corresponding Output.

The output in year n, zn, is calculated as:

zn = 0 for n < c

zn = xn–c for n ≥ c

where

x = Transformation input

c = Lag input

Default: 1.

Features See Transformations.

Costs

If defined, this input of a Previous or Time Lag transformation is used as an alternative target for cost-allocation in order to avoid the circularity which would otherwise arise if the transformation were used to calculate a difference equation indirectly involving ‘itself’ (i.e., an earlier value of the same transformation).

Default: Resource (<none>, Installed Capacity).

Features See Transformations.

Input

Identifies an element as a source of demand for a Transformation; together with a Basis, which specifies the particular result, associated with that element, which defines the size of that Input in any year. Expression Transformations have several inputs, called Input 1, Input 2, and so on.

Default: Resource (<none>, Installed Capacity). For an Erlang B Formula transformation, Service (<none>, Busy Hour Traffic). For a Time Factor transformation, Transformation (<none>).

Features See Transformations.

 

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