Investigation of Topology Optimization of Magnetic Circuit by Using Density Method
The topology optimization using the density method, which determines the optimal topology by distributing the magnetic material in the design domain, is attractive for designers of magnetic devices, because an initial conceptual design can be obtained. As the number of design variables in design domain is so huge, a sufficient solution cannot be obtained by using the direct search method. Then, the steepest descent method is adopted to obtain the fast convergence. In this paper, some problems in applying the density method to the practical topology optimization are investigated. The accuracy of calculating the sensitivity using the adjoint variables method and the effect of initial material density on the obtained results are examined. The effectiveness of the proposed optimization method is illustrated by applying it to the determination of the optimal topology of permanent magnet which generates a uniform magnetic field.
Unlike traditional omni-directional sensors that always have an omni-angle of sensing range, directional sensors may be able to switch to several directions and each direction has a limited angle of sensing range. Area coverage is still an essential issue in a directional sensor network which consists of a number of directional sensors. In this paper, we study a novel "area coverage by directional sensors" problem. We propose the maximum directional area coverage (MDAC) problem to maximize covered area by scheduling the working directions of the sensors in the network. We prove the MDAC to be NP-complete and propose one distributed scheduling algorithm for the MDAC. Simulation results are also presented to demonstrate the performance of the proposed algorithm.