Abstract. With the widespread use of encryption techniques in network applications, encrypted network traffic has recently become a great challenge for network management. Studies on encrypted traffic classification not only help to improve the network service quality, but also assist in enhancing network security. In this paper, we first introduce the basic information of encrypted traffic classification, emphasizing the influences of encryption on current classification methodology. Then, we summarize the challenges and recent advances in encrypted traffic classification research. Finally, the paper is ended with some conclusions.
In double planar mirror omnidirectional imaging systems, camera calibration is a crucial part of the 3D reconstruction process. Based on analysis of the imaging geometric features of double planar mirrors, three types of algorithms for the camera intrinsic parameters are presented by computing the imaged circular points and orthogonal vanishing points. The camera intrinsic parameters can be obtained by the constraints on the imaged circular points and the orthogonal vanishing points to the image of the absolute conic. Simulation, real data, and 3D reconstruction experiments are presented to show the feasibility and validity of the proposed methods.
This paper introduces an omnidirectional vision system calibration method that uses the central catadioptric projection properties of a single sphere. A central catadioptric camera with a single effective viewpoint images a single sphere as a closed conic. The intrinsic parameters of the camera can be obtained based on the imaged circular points and orthogonal vanishing points. The feasibility and validity of three algorithms were demonstrated through simulations and experiments with real data.
A new paclitaxel derivative and two new 2(3-->20)-abeo-taxoids were isolated from a methanol extract of the seeds of Taxus mairei, and their structures were established as 1-deoxypaclitaxel (1), 7beta,10beta-diacetoxy-2alpha,5alpha,13alpha-trihydroxy-2(3-->20)-abeo-taxa-4(20),11-dien-9-one (2), and 2alpha,13alpha-diacetoxy-10beta-hydroxy-2(3-->20)-abeo-taxa-4(20),6,11-triene-5,9-dione (3) on the basis of spectroscopic data analysis. Taxane 1 is the first example of a paclitaxel analogue with a C-1beta hydrogen substituent. Taxane 3 is an 2(3-->20)-abeo-taxane with a rare C-5 ketone and C-6 double bond.
As one of the classical theories of projective geometry, Pascal’s theorem is closely related to the conic, which is the image of a circle. A circle is the geometric element typically used as a template for camera calibration methods. In this work, we propose a calibration method based on Pascal’s theorem and its inference, in which a circle is used as the calibration template. The proposed calibration method can be applied to solve the image of the circular points via the Newton iteration method. The intrinsic parameters of the camera can then be determined based on the constraints of the images of the circular points and the image of the absolute conic. The results of simulations and experiments conducted verify the validity and feasibility of the proposed calibration method.
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