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Most of the current trajectory privacy protection methods does not consider the shape similarity of trajectory sufficiently, and it is easy to ignore the timing correlation of each point on the trajectory, which results in the low availability of the generated interference tracks. To solve these problems, a differential privacy trajectory protection mechanism based on density clustering algorithm was proposed. Firstly, density based spatial clustering of application with noise (DBSCAN) algorithm was used for clustering analysis of data to reduce the influence of noise points in data set on clustering effect. Secondly, the position transition probability matrix was generated according to the time sequence relationship of user's activity locus points, and the differential privacy method was used to ensure that the generated interference locus points have similar position transfer probability to the real locus points. Finally, considering the influence of differential privacy budget and Fréchet distance on trajectory similarity to select the location interference point. The simulation results show that the proposed scheme has advantages in efficiency obviously, and the generated interference trajectory has higher shape similarity compared with the real position trajectory. [ABSTRACT FROM AUTHOR]

Aiming at the problem of elevator braking failure caused by the uneven wear of the elevator brake, the reasons for the uneven wear and the influence of the elevator brake were summarized. The internal energy change of the elevator brake system was analyzed and studied.The change of the heat flux on the surface of the elevator brake was obtained, and a kind of elevator brake based on the thermal image analysis was put forward. The uneven wear test method was used to collect the infrared thermal image of the brake skin on the elevator brake, the mixed noise in the collection process was filtered out, the isotherm feature vector and the gate edge feature vector was extracted, and the uneven wear degree of the elevator brake skin was characterized by calculating the frying distance between the characteristic vector of the isothermal line and the edge eigenvector of the elevator brake. The results indicate that this method can detect the uneven wear of the elevator brake, and figure out the problem that the elevator can not detect the uneven wear of the brake under the condition of undisintegration. [ABSTRACT FROM AUTHOR]

To solve the problem that underwater submarine target signal are corruped by the strong magnetic background noise and interrupter in the aeromagnetic anomaly detection, a joint estimation detection method is proposed. A signal model of target measured by optical pump magnetometer is established for submarine target based on magnetic dipole. The target signal model is determined by 7 unknown parameters： position vector a:,y ,2 , magnetic moment vector Mx,My,M： 9 and course angle 〇. According to the observation sample, the unknown parameters are searched by genetic algorithm and the prior information of submarine target, and the fitness function is constructed by Frechet distance. Then the test statistic of mean correlation is proposed based on the target estimated signal, and the correlation detector using target estimated signal is designed. The performance analysis using measurement data shows that the detector is still with good detection performance in the low signal-to-noise ratio condition. Compared with the traditional detection based on decomposition of orthonormal basis and the aeromagnetic anomaly detection for moving target, the performance of the joint estimator and detector using target estimated signal is better, and it can improve the signal-to-noise ratio and reduce the false alarm probability. [ABSTRACT FROM AUTHOR]

In different spatial data set, corresponding enties have different space pattern of manifestation, while identification of multi-source heterogeneous data sets of the same entity is the fundamental problem in spatial data integration and various kinds of its applications. Integrating geospatial data from different sources is the most important way to improve the quality of GIS data, while identification of the same object is the prerequisite for integration and analysis of spatial data. In this paper, on the basis of the shape characters, we classify the complex linear features into the simple and the complex linear features, In terms of matching of curve features, there are still some shortcomings in existing methods, this is the reason that the paper puts forward complex curve features of the Fréchet distance matching method. Based on geometry and topology characteristics of curve features, the method first obtains the matching candidates, and then realizes the simplification of features on the basis of Fréchet distance and simplified method. Finally, by introducing triads of simplified features to store the attribute information of the complex linear element, the paper proposed an improved method based on the Fréchet distance and the triads information of the complex linear feature to accomplish the detection of different types of corresponding pairs and to realize complex curve features matching. The test results show that the proposed method not only can efficiently solve the matching problems of curve features, but also can effectively identify 1:0,1:N and M:N matching pairs. [ABSTRACT FROM AUTHOR]

Geometric similarity measurement of linear features is the key to matching map data, fusion, and clustering. This paper presents a new method for geometric similarity measurement of digital map linear features based on the traditional discrete Frechet distance. We derived a formula for computing discrete curves Frechet distance based on recurrence and presents curves similarity measurement model based on average Frechet distance. The average Frechet distance is obtained by recognizing and computing minimal path between points in two curves, which can avoid biggish error of traditional Frechet distance. Meanwhile, this paper demonstrates that the average Frechet distance delivers higher accuracy, theoretically. In order to measure the partial and overall similarity between two curves, we also present a partial-overall discrete Frechet distance based on the average Frechet distance. Finally, this Frechet distance was applied to matching map data, fusion and contour interpolation. Experiments were performed to show the feasibility and superiority of the method. [ABSTRACT FROM AUTHOR]