This paper proposed a novel weighted multidimensional scaling (MDS) estimator for estimating the position of a stationary emitter with sensor position uncertainties using time-difference-of-arrival measurements. The solution is closed form and unbiased. It is shown analytically to achieve the Cramer-Rao lower bound performance in small noise region. Simulation results show that the proposed estimator offers smaller bias and mean square error than the two-step weighted least square approach and traditional MDS estimator ignoring sensor position uncertainties at moderate noise level. Additionally, the computation complexities of them are comparable.

In this paper, we propose a novel discrete cuckoo search algorithm (DCS) for solving spherical Traveling Salesman Problem (TSP) where all points are on the surface of a sphere. The algorithm is based on the Lévy flight behaviour and brood parasitic behaviour. The proposed algorithm applies study operator, the "A" operator, and 3-opt operator to solutions in the bulletin board to speed up the convergence. Optimization results obtained for HA30 (an instance from TSPLIB) and different size problems are solved. Compared with GA, DCS is better and faster.

Abstract:In this paper, a novel discrete cuckoo search algorithm to solve the travelling salesman problem (TSP) is proposed. The algorithm is based on the continuous cuckoo search with brood parasitic behaviour and Lévy flight. The algorithm does not save the initial routes in the bulletin board, until the segment between each city and adjacent cities partially are reversed. In each generation, an each cuckoo searches a new nest and abandons the old one to decrease the TSP route. In order to accelerate the discrete cuckoo search algorithm convergence speed, the proposed algorithm applies learning operator, 'A' operator and 3-opt operator to the bulletin board. The numerical experiment results show that the proposed algorithm can find the global optimal solution with rapid convergences and stable generation.Keywords: discrete cuckoo search algorithm; metaheuristic; 3-opt; travelling salesman problem.Reference to this paper should be made as follows: Zhou, Y., Ouyang, X. and Xie, J. (2014) 'A discrete cuckoo search algorithm for travelling salesman problem', Int.

The classic two-step approach for time difference of arrival (TDOA) geolocation is suboptimal since the TDOA measurements have not followed the constraint that all measurements should be consistent for a geolocation of a single emitter. In this study, the direct TDOA geolocation approach is proposed for frequency-hopping (FH) emitters. It makes use of the sparsity of the FH signals in frequency domain, and constructs a cross correlation function (CCF) matrix in frequency domain, then the location estimate is obtained by searching the maximum eigenvalue of the CCF matrix in a two dimensional grid. The Cramer-Rao lower bound has been derived. The resolution for a single FH signal geolocation is also analysed. Further, an extension of the new method for multiple FH emitters direct TDOA geolocation has been presented. The performance comparison between the direct approach and the conventional two-step method has been made by simulations. The results demonstrated that the proposed method outperforms the conventional two-step method. The simulations also demonstrated the effectiveness of the new method in locating multiple FH emitters.