Information Technology Reference
In-Depth Information
2 The Meta-heuristic Harmony Search Algorithm
Like other meta-heuristic optimization algorithms, the main philosophy of the HS al-
gorithm depends on a heuristic event. However, HS does not get its philosophy from
the natural processes, instead, it gets it from the musical improvisation which occurs
when a group of musicians searches for a better state of harmony. Geem et al. [9] first
adapted this musical improvisation process into the solution of engineering optimiza-
tion problems. In this adaptation, each musician corresponds to a decision variable
and possible notes in the musical instruments correspond to the possible values of the
decision variables. When the musicians find the fantastic harmony from their memo-
ries, it means, a global optimum solution is found through corresponding decision
variables. Figure 1 demonstrates the analogous relationship the musical improvisation
and optimization [12].
Fig. 1. Analogy between musical improvisation and optimization
As can be seen from Figure 1, each musician has several notes in their memories.
For example, if the first musician plays {Do} while second and third musicians play
{Sol} and {La} from their harmony memories, {Do, Sol, La} makes a new harmony.
If this harmony is better than the worst one in the harmony memory, it replaces the
worst one and this process is repeated until fantastic harmony is found. On the other
hand, in the optimization process, each musician is replaced with a decision variable
and notes are replaced with preferred values of decision variables. If the decision
variables take {1.0}, {1.5}, and {1.7} from the harmony memory, a new solution vec-
tor {1.0, 1.5, 1.7} is obtained. If this solution vector is better than the worst one stored
in the harmony memory, this new solution vector replaces the worst one. This itera-
tive process is repeated until the given termination criterion is satisfied.
Search WWH ::




Custom Search