Graphical Modelling in Simile : Discrete event based

Event-based modelling in Simile

A pure discrete-event-based model includes only event symbols (time series and derived/delayed) and states. An event symbol only has a value at the point in time at which it occurs. The value of a derived event occurrence is calculated by its equation, which can include the value of the triggering event occurrence.  A state has a rule for each event symbol that influences it. When one occurs, the state's new value is given by the corresponding rule, otherwise it stays the same.

A model that mixes system dynamics (continuous) and discrete-event based operation also includes limit event symbols and squirts. A limit event occurrence is triggered when its equation reaches its minimum or maximum value, allowing continuous processes to set off events. A squirt is a derived event which causes an instantaneous transfer of material between compartments, allowing events to affect continuous processes. State changes can also affect continuous processes, but only squirts can cause discontinuities in the values of compartments.

event

An instantaneous occurrence which can have a magnitude

state

A quantity set by events according to rules

squirt An instantaneous transfer of a substance between compartments

 

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