A stigmergic algorithm for solving inverse thermal systems

摘要

This thesis proposes a novel method for solving inverse thermal systems problems based on stigmergy. Inverse problems are those problems that have a desired output but the inputs required to achieve that output are unknown. The example problem examined is an established inverse radiation heat transfer problem in which two parallel plates are separated by a distance. The temperature profile along the top plate is adjusted to achieve a specified temperature profile on the insulated bottom plate. This type of inverse radiation problem arises in annealing, industrial process ovens, and combustion chambers. Stigmergic processes rely on local instructions and interactions and as a result can be readily scaled up to larger and more complex systems. The algorithm developed here uses the concept of distributed construction and finds the solution without direct communication and uses only local information. Specifically, a stigmergic algorithm was developed based on the egg dumping and redistribution behavior of lacebugs (Gargaphia solani) and the construction of ant cemeteries based on ant species Lasius niger and Pheidole pallidula. The algorithm is demonstrated with five separate lower surface starting and ending profiles. In contrast with traditional methods that rely on global information, the desired temperature profiles are attained using only local information. Based on this, in each case the temperature profile of the lower surface rapidly converges to the desired temperature profile. Therefore, sensors can be added as needed without restructuring the sensors network or control strategy.