Applied Mechanics and Materials Vols. 380-384

Abstract: [Purpose] In GPS/INS integrated navigation, which is widely used in high precision of the real-time navigation, the Extended Kalman Filter (EKF) has become one of the most widely used algorithms. Unfortunately, the EKF is based on a sub-optimal implementation of the recursive Bayesian estimation framework applied to Gaussian random variables. This can seriously affect the accuracy or even lead to divergence of the system. In order to improve the accuracy, we apply the Unscented Transformation to GPS/INS integrated navigation. [Method] This paper optimizes GPS/INS integrated navigation by applying the Unscented Kalman Filter (UKF) algorithm which is based on the Unscented Transformation. [Results] The experimental results show that the UKF has an error reduction of over 10% in every estimator relative to the EKF. [Conclusions] Consequently, the UKF is an effective algorithm to improve the accuracy of GPS/INS integrated navigation.

Abstract: This paper investigates a frequency coordination control strategy for islanded microgrid. The dynamic process is divided into three levels including the dynamic support, droop control and zero error regulation. The control strategy is classified into primary and secondary frequency regulation. Simulation is performed on DIgSILENT and the results verify the effectiveness of the proposed control strategy and improve the performance of system frequency regulation.

Abstract: Dissemination is a data dissemination protocol for wireless sensor network based on TinyOS. The purpose of it is that we can send data to every node reliably Dissemination can reconfigure,query and reprogram nodes easily This article briefs the mechanism of Dissemination,and analyzes its principle. At last, it is applied in practice. Practice shows that, when network traffic is small, Dissemination has good performance, and reliable, simple to deploy, with high practicability and value. But when network is large, its performance is poor. So, based on the specific practice, Dissemination is improved.

Abstract: The problem of resilient guaranteed cost control for a class of singular interval systems with time varying time-delay was investigated. A condition for the existence of resilient guaranteed cost controller is derived via linear matrix inequalities (LMI) technology. Furthermore, it is shown that this condition is equivalent to the feasibility problem of a set of LMIs, and its solutions provide a parameterized representation of resilient guaranteed cost controllers. Finally, a numerical example is given to show the effectiveness of it.

Abstract: A matching between two sets of points under affine transformations has attracted more and more attention. Many algorithms devote to extracting the descriptor for the point from the configuration, and the descriptor based point matching is achieved ignoring the pairwise geometric relations. In this paper, taking advantage of the inlier correspondences in matched configurations, we formalize a soft matching criterion which emerges from a matching probability matrix, followed by a relaxation labeling process to refine the match. The proposed approach has been implemented and gives encouraging results under rotation, scaling, shearing and noise.

Abstract: A passive long wave cochlea model is applied to extract audial feature of naval vessel radiation noise. Based on the model, a two dimensional time space distribution Spectrum of noise signal is calculated. Four one dimensional features with simple form are presented. The experiment results shows that the features based on cochlea model is consistent with auditory perception of noise signal. The approach is a new method to extract feature for passive sonar target recognition.

Abstract: According to the problem that there is a decline in accuracy of low-frequency signal parameter estimation by using the algorithm of all-phase FFT, an improved phase difference correcting spectrum method based on all-phase FFT is proposed. The contribution of negative frequency to FFT calculation was considered while using phase difference correcting spectrum method. The all-phase FFT spectrum analysis theory was presented as well as a traditional phase difference correcting method based on it. The equations of parameter estimation such as frequency, amplitude and phase for low-frequency signals were derived with the negative frequency contribution to spectrum analysis. The simulation results show that the method proposed in this paper can be used to estimate the parameters of low-frequency signals in a high accuracy, and also achieves an improvement in anti-noise ability.

Abstract: In this paper, a broadband septum dual circular polarized antenna with dielectric loaded is designed. In order to expand the bandwidth, the antenna uses the form of dielectric loaded in the waveguide and extends the dielectric to meet the miniaturization requirements, which can improve the Gain and the matching of waveguide. The simulation results show that in the 40% relative bandwidth, the VSWR is lower than 1.7. The isolation between the two input ports is lower than-10dB. Gain is larger than 7.5dB and the axial ratio is lower than 3.5dB.

Abstract: Firstly in this paper,an antipodal Vivaldi antenna is designed.The bandwidth is from 6GHz to 18GHz. The simulated results show good electric performance and the voltage standing wave ratio is less than 2 in the whole bandwidth.Secondly depending on this unit,this paper designs two kinds of arrays and estimates their radiation characteristics,respectively.The one array is a 1×8 array and the another array is a X-cross structure array with four elements.

Abstract: As next generation of the web, the semantic web aims at a more intelligent web severing machines as well as people, based on radical notions of information sharing and acquisition. For color image segmentation, semantic color is our focus. One method of color partition is fuzzy clustering which has been widely used in image segmentation. However, the fuzzy clustering algorithm is parameter sensitive, and lack of availability because of its initial focus on physical features. To improve the above problems, a novel fuzzy clustering method based on semantic color retrieval for image segmentation is proposed in this paper. The method is realized by modifying the membership function in the conventional clustering algorithm and by constructing the semantic color retrieval mechanism to achieve the semantic color extraction, which take human visual subjectivity into account in semantics. Experimental results show that the presented method performs more effectively than the previous algorithm.