Defining the Sudden Withdrawal for Fire Suppression

Lesson 4, page 10 of 14

Now that we have defined the Fire event, we need to add another element that responds to it.Recall that whenever a fire occurs, a certain amount of water (100 m3) needs to be immediately removed (e.g., via helicopters) to fight the fire.

To represent this, we are going to use another specialized element called a Discrete Change.

Add a Discrete Change Element An element that generates discrete change signals that can subsequently modify stock elements. to Represent the Sudden Withdrawal of Water:

  1. In the graphics pane The primary portion of the GoldSim interface, where the graphical depiction of the model is shown., right-click, choose Insert Element, Events, and then select Discrete Change:


    Once you've inserted the element, its Properties dialog will immediately open:

  2. In the Element ID field, type "Sudden_Withdrawal".
  3. In the Description field, type "Sudden withdrawal for fire suppression".
  4. In the Display Units field, type "m3".
  5. In the Value field, type "100 m3".
  6. In the Instruction field, leave it at the default of "Add". (There is no "Subtract" instruction. As we will see, the fact that this is a withdrawal will be represented by the field it is linked to in the Reservoir A Stock element that integrates and conserves flows of materials. element.)
  7. Next we need to tell the element when to make the sudden withdrawal. To do so, press Trigger... button. The following dialog will be displayed:


    This dialog is used to specify "triggering events" instructing GoldSim when to make the sudden withdrawal.
  8. Press the Add button.
  9. From the Type drop-list, leave it at the default of "On Event".
  10. In the Trigger Definition, enter "Fire". The dialog will look like this:


    So this "trigger" tells GoldSim to make a sudden withdrawal whenever the Fire event occurs.
  11. Press Close to close the triggering dialog.The Discrete Change dialog should look like this:

  12. Press OK to close the dialog.
  13. Press the Save button in the toolbar (or press Ctrl+S):

The graphics pane should now look similar to this:

So we have defined the Fire event and we have defined the consequence of the event (i.e., the element that responds when the fire occurs, the Discrete Change element). What we have not yet done, however, is specified which element is impacted by the consequence.That is, we need to link the Sudden_Withdrawal to the Pond.

Note: You should notice that the influence An arrow connecting two elements that indicates that one element influences the other. drawn from Fire to Sudden_Withdrawal is red, while all of the other influences are black. This helps remind you that the information being passed is fundamentally different. The red influence indicates that a discrete signal A special category of output that emits information discretely, rather than continuously. is being passed between elements The basic building blocks with which a GoldSim model is constructed. Each element represents a feature, pararamer, process or event in the model..