Guangzheng Ni

A modified ant colony optimization algorithm modeled on tabu-search methods

An earlier model underlying the foraging strategy of a pachycodyla apicalis ant is modified. The proposed algorithm incorporates key features of the tabu-search method in the development of a relatively simple but robust global ant colony optimization algorithm. Numerical results are reported to validate and demonstrate the feasibility and effectiveness of the proposed algorithm in solving electromagnetic (EM) design problems

Wavelet-Galerkin method for computations of electromagnetic fields-computation of connection coefficients

One of the key issues which makes the wavelet-Galerkin method unsuitable for solving general electromagnetic problems is a lack of exact representations of the connection coefficients. This paper presents the mathematical formulae and computer procedures for computing some common connection coefficients. The characteristic of the present formulae and procedures is that the arbitrary point values of the connection coefficients, rather than the dyadic point values, can be determined. A numerical example is also given to demonstrate the feasibility of using the wavelet-Galerkin method to solve engineering field problems.

A tabu method to find the Pareto solutions of multiobjective optimal design problems in electromagnetics

A tabu search algorithm is proposed for finding the Pareto solutions of multiobjective optimal design problems. In this paper, the contact theorem is used to evaluate the Pareto solutions. The ranking selecting approach and the fitness sharing function are also introduced to identify new current points to begin every iteration cycle. Detailed numerical results are reported in this paper to demonstrate the power of the proposed algorithm in ensuring uniform sampling and obtaining the Pareto optimal front of the multiobjective design problems. The most efficient method of implementing the proposed algorithm is also discussed.

A meshless collocation method based on radial basis functions and wavelets

A meshless method based on collocation with radial basis functions (RBFs) and wavelets is proposed. It is shown that the proposed method takes full advantage of both RBFs and wavelets. The bridging scales are employed to preserve the mathematical properties of the entire bases in terms of consistency and linear independence. A numerical example that is used to validate the proposed method is reported.

An improved Tabu search for the global optimizations of electromagnetic devices

An extended Tabu algorithm with an aspiration factor is proposed. The algorithm is based on the success of techniques such as the memorization of the previously visited subspaces, the systematic diversification as well as the intensification process for neighborhood creations. The numerical results obtained by solving a mathematical test function and the benchmark problem 22 of the TEAM Workshop reported in this paper demonstrate the usefulness of the proposed method.

A self-learning simulated annealing algorithm for global optimizations of electromagnetic devices

A self-learning simulated annealing algorithm is developed by combining the characteristics of simulated annealing and domain elimination methods. The algorithm is validated by using a standard mathematical function and by optimizing the end region of a practical power transformer. The numerical results show that the CPU time required by the proposed method is about one third of that using conventional simulated annealing algorithm.

A simulated annealing algorithm for multiobjective optimizations of electromagnetic devices

This paper proposes a simulated annealing algorithm for multiobjective optimizations of electromagnetic devices to find the Pareto solutions in a relatively simple manner. The algorithm is based on the successful introductions of the Pareto set as well as the parameter and objective space strings. The new rank formula and fitness-sharing functions together with the stop criterion and other improvements are investigated in the proposed method. Two numerical examples for validating the robustness of the proposed method are also reported.

3-D eddy current analysis in the end region of a turbogenerator by using reduced magnetic vector potential

This paper presents a novel strategy to model the full three-dimensional structures of end region of huge turbine-generators with power level up to 1000MW. The 3-D nonlinear anisotropic magnetic field including the eddy current losses is calculated by utilizing the reduced magnetic vector potential formulation. With the help of Biot-Savarts law, the magnetic field caused by currents in the stator and rotor windings, which are very complex in geometric shapes, can be calculated in a far easy way. The flux density distribution in the end region and the eddy current distribution in the structural parts under different operating conditions are presented

A Quantum-Based Particle Swarm Optimization Algorithm Applied to Inverse Problems

To balance exploration and exploitation searches in order to prevent premature convergences in Particle Swarm Optimization (PSO) algorithms, an improved Quantum-based PSO (QPSO) algorithm is proposed with an ultimate goal of preserving the simplicities of available QPSOs. The improvements include the design of diversification and intensification phases, searching mechanisms and a strategy to shift away from the worst solutions. The proposed QPSO are compared to available optimizers on two case studies to showcase its merits.

A combined wavelet-element free Galerkin method for numerical calculations of electromagnetic fields

A combined wavelet-element free Galerkin (W-EFG) method is proposed for solving electromagnetic (EM) field problems. The bridging scales are used to preserve the consistency and linear independence properties of the entire bases. A detailed description of the development of the discrete model and its numerical implementations is given to facilitate the reader to understand the proposed algorithm. A numerical example to validate the proposed method is also reported.