S1. Calculate the distance to neighbor nodes. |
The distance between the current node and allowed visit neighbor node is given by: |
, |
where, is the coordinate of the neighbor node ; is the coordinate of the current node ; is the length of link |
. |
S2. Calculate the congestion degrees of neighbor nodes. |
The allowed visit neighbor node ’s congestion degree at the time step is given by: |
, |
where, is the number of evacuees in neighbor node at the time step. is the capacity of node . |
S3. Calculate transition probability from node to |
The transition probability from node to at the time step is given by: |
|
where, is the subzone which the ant is in currently. is the pheromone amount on connection at generation |
under pheromone vector; is the heuristic information related with link at time step, under pheromone |
vector, at generation; is the set of candidate nodes; and are the parameters to control the relative importance between |
the pheromone and the heuristic information. |
The heuristic information on link at time step is given by: |
, |
where, is the length of link ; is the number of evacuees in node at the time step; is the capacity of node . |
S4. Select one of candidate nodes according to cumulative transition probability |
According to roulette wheel selection, the node would be selected only and if only when |
, rand is a random real number between 0 and 1. is the cumulative transition |
probability, which is given by: |
|
Besides, we rule that . |