Ecolego Wiki

A common request is to find the maximum value of an output. For this one can use the Min/Max block. However, in this experiment we will determine the maximum for each month of the simulation.

This means that we need to reset the Min/Max block every month. We will need the following:

• A Time point block which allows us to specify the first day of each month
• A Time event which will fire events based on the time point block
• A Min/Max block which records the soil concentration.

Create time point

1. Create a time point block
2. Edit the block.
3. In the Properties screen
   1. change the name to “Month_time_point”.
4. In the Values screen
   1. click the Settings button.
   2. Change the Mode to Day of month.
   3. Enter the value 1 as the Timepoint in the table, which indicates the 1st of each month.
5. Close the window

Create event

1. Create a time event block
2. Edit the block.
3. In the Properties screen
   1. change the name to “Month_event”.
4. In the Values screen
   1. select Month_time_point and click the > button.
5. Close the window

Create min/max

1. Create a min/max block
2. Edit the block
3. In the Properties screen, change the name to Monthly_max
4. In the Values screen
   1. Enter the name _Soil_ in the Target expression column
   2. Select _Month_event_ in the Reset column
5. Close the window

Run a simulation

1. Run a simulation, then plot _Soil_ together with _Monthly max. - The plot should look like this: You can download the model here ==== Base model ==== All examples are based on the following base model, which calculates a dummy value we can use for our event experiments. You can download the model from here 1. Edit simulation settings. Set * Time unit: Days * Time mode: Time * Start time: 0.0 * End time: 100.0 * Start date:2000-01-01 * Output options: Produce additional output * Time points: from start to end with a 1.0 increment 2. Create a material named Poison with the unit mg. 3. Create two compartments Sky and Soil. Set the initial condition for Sky to be 500 (mg) of Poison**.

4. Add a transfer from Sky to Soil and set its equation to “30+sin(time/5)*20+cos(time/3+2)*10”

5. Add a transfer from Soil to Sky and set its equation to “30+sin(time/3+2)*10+cos(time/7+3)*20”

6. When run, the model will output a Sky and Soil concentration like this:

Continue with Next

• First page
• Tutorials