Trust regions in Kriging based optimization with expected improvement
The Kriging based Efficient Global Optimization (EGO) method works well on many expensive black box optimization problems. However, it does not seem to perform well on problems with steep and narrow global minimum basins and on high dimensional problems. This article develops a new Kriging based optimization method called TRIKE (Trust Region Implementation in Kriging based optimization with Expected improvement) that implements a trust region like approach where each iterate is obtained by maximizing an Expected Improvement (EI) function within some trust region. This trust region is adjusted depending on the ratio of the actual improvement to the EI. This article also develops the Kriging based CYCLONE (CYClic Local search in OptimizatioN using Expected improvement) method that uses a cyclic pattern to determine the search regions where the EI is maximized. TRIKE and CYCLONE are compared with EGO on 28 test problems with up to 32 dimensions and on a 36 dimensional groundwater bioremediation application in appendices supplied as an online supplement available at http:/dx.doi.org/10.1080/0305215X.2015.1082350. The results show that both algorithms yield substantial improvements over EGO and they are competitive with a radial basis function method.