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In this paper, the distributed second-order tracking control problem of a multi-vehicle system is investigated over a directed connection topology. It is supposed that each vehicle can only obtain the position measurements of itself and its neighbors in a noisy environment. The problem is solved by embedding a finite-time convergent estimator in each vehicle and then combining it with a linear or...
Remarkable progress has been made of terahertz technologies such as the source and detector. Great advancement has also been achieved of terahertz systems. Such progress reviewed here presents a big impetus to terahertz satellite communications. For satellite-to-satellite communications terahertz link shows great advantages over either millimeter-wave link or optical link. The architecture of terahertz...
In this paper, we propose an adaptive threshold estimation method for image denoising based on nonsubsampled contourlet transform (NSCT). The NSCT is developed because of the lack of translation invariance of the contourlet transform. It is good at isolating the smoothness along the contours and can overcome the Gibbs-like phenomena around singularities. The proposed algorithm can adapt different...
In this paper, we put forward an improved image denoising method based on multi-wavelet transform. According to the characteristic of the multi-wavelet coefficients in different directions of the different sub-band and combine with the image decomposition scaling function, this method can select different adaptive threshold of the best. Experiments show that this method can remove the white noise...
Tracking reentry vehicle with strong maneuvers on-line is a challenging task. The key is to develop suitable dynamic models and estimation methods. Two kinds of modeling methods are discussed for reentry tracking, and the unscented filter (UKF) is introduced to the nonlinear tracking system. To reduce the computational load, three simplifications of UKF are developed. Furthermore, the feasibility...
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