A test case was defined to evaluate the capability of different global optimization algorithms to find the global minimum of a ship design problem. The goal is to minimize the vertical motion of the center of gravity (heave motion) of a S175 containership advancing at a speed of 16 knots in head seas for non-dimensional frequencies omega/sqrt(L.g) > 0.4 (omega = circular frequency of incident wave, L = ship length, g = 9.81 m/s2). Five different algorithms were tested: 1) Conjugate Gradient Method (a local search algorithm), 2) Simplex Method, 3) Parameter Space Investigation (PSI, provides the Pareto Optimal Set of a multi-criteria optimization problem sampling the feasible design region by means of an unformly distributed sequence of trial solutions), 4. Particle Swarm Optimization (PSO, an evolutionary technique where a population of trial solutions (represented by a swarm of particles) is used to sample the design space, each particle moving with an adaptable speed according to individual and collective rules), 5) Lipschitzian Optimization method (Diagonal Rectangular Analysis for Global Optimization (DRAGO)). The local gradient-based method remains trapped in the neighborhood of the original configuration, and the improvement obtained was less than 10%. However, all global optimization methods improved the objective function by more than 30% - even the simplex method, which is usually treated as a local method, but can overcome problems connected with high-frequency noise of the objective function if the investigation region is wide enough. Particle Swarm Optimization seems to give the best results among the investigated algorithms.
Global optimization algorithms in naval hydrodynamics
Globale Optimierungsalgorithmen für den Schiffsentwurf
Ship Technology Research / Schiffstechnik ; 51 , 3 ; 123-133
2004
11 Seiten, 7 Bilder, 1 Tabelle, 16 Quellen
Aufsatz (Zeitschrift)
Englisch
Global Optimization Algorithms in Naval Hydrodynamics
Taylor & Francis Verlag | 2004
|Global Optimization Algorithms in Naval Hydrodynamics
Online Contents | 2004
|British Library Conference Proceedings | 2004
British Library Conference Proceedings | 1997
|British Library Conference Proceedings | 1997
|