Advanced Materials Research Vols. 255-260

Abstract: In this paper, the traditional passive loop filter is improved, and a new type of Cascade Third-order filter structure and Graphical Phase Design method is proposed, which greatly simplifies high-order PLL filter’s design, analysis and calculation. According to graphical phase design principle, parameters for cascade third-order filter could be figured out from the given formula, the derived result is simulated in the form of Bode plots and Unit-step response with Pspice software and the loop target under different parameters is compared. Experiments show that this third-order filter could significantly improve the stability of PLL, deeply attenuate the phase detector’s high-frequency noise and is well adapted to the loop gain change. Users can also change the design parameters flexibly according to the system requirements with this filter.

Abstract: Dynamic time warping(DTW) distance is the most effective similarity measurement methods in time-series data mining area. Because of the high computational complexity of DTW, it is not suitable for huge amounts of data. Thus, some DTW distance lower bound methods are proposed, which can improve the efficiency of DTW distance calculation. In this paper, we summarized the existing lower bound of DTW method and then proposed a closely related field with the application and exacted Lower Bounding distance measure with Segmentation(eLBS). Experiment results show that this method meet the need of non-omission.

Abstract: Affine reconstruction is to restore the affine shape of the object. Generally, there are two ways of achieving, one is to determine the plane at infinity, another is to determine the plane homography. Using the homography which had determined the plane at infinity achieve affine reconstruction. In this paper, firstly give out the homography of infinity plane and the algorithm of affine reconstruction, then proved: if the scene contains a set of parallel planes and a infinity point, the homography of infinity plane can be obtained and affine reconstruction can be linearly got in the scene. Computer simulation and real experiments show that the linear affine reconstruction algorithm is correct, and the approach has a good precision.

Abstract: For effectively solving human behavior recognition in video surveillance, a novel behavior recognition model is presented. New behaviors may be produced in the process of human motion, hierarchical Dirichlet process is used to cluster monitored feature data of human body to decide whether unknown behaviors occur or not. The infinite hidden Markov model is used to learn unknown behavior patterns with supervised method, and then update the knowledge base. When knowledge base reaches a certain scale, the system can analyze human behaviors with unsupervised method. The Viterbi decoding algorithm of HMM is adopted to analyze current behavior of the human motion. The simulation experiments show that this method has unique advantage over others.

Abstract: The occlusion problem in crowded people environment makes human segmentation and tracking more difficult in video surveillance. Thus, a human segmentation method combing human model with body edge curve is presented. Because segmentation may result in serious defect and distortion, robust BP neural network model is adopted as tracking mode. For improving autonomous learning ability of BP network, Hierarchical Dirichlet Process (HDP) is used to decide whether new types of human body characteristic data is generated, which provides decision basis for BP network learning. The simulation experiments confirm that the method presented in this paper can effectively solve the problem of partial human body occlusion. Meanwhile, this method has unique advantage of simplicity and real-time over others.

Abstract: Species identification plays an important role in botanical research, but traditional identification tool, which mainly depends on reference books or identification keys, is often recognized as a difficult and frustrating task, especially for novices. In recent decades, many efforts have been made by taxonomists and programmers to ease the difficulty of species identification by developing a range of tools that increasingly involved the use of computers. In this paper, new advances of plant identification based on three main artificial intelligent technologies: expert system, artificial neural network, and machine vision are briefly introduced. Several trends of plant identification tools for non-expert users are also proposed in the last part.

Abstract: In this paper, we introduce a robust image watermarking method based on Hilbert-Huang Transform (HHT) against geometric distortion. This watermarking is detected by a linear frequency change. The HHT transformation is used to detect the watermark. The chirp signals are used as watermarks and this type of signals is resistant to all stationary filtering methods and exhibits geometrical symmetry. In the two-dimensional Radon-Wigner transformation domain, the chirp signals used as watermarks change only its position in space/spatial-frequency distribution, after applying linear geometrical attack, such as scale rotation and cropping. But the two-dimensional Radon-Wigner transformation needs too much difficult computing. So the image is put into a series of 1D signal by choosing scalable local time windows. The watermark embedded in the HHT transformation domain. The watermark thus generated is invisible and performs well in StirMark test and is robust to geometrical attacks. Compared with other watermarking algorithms, this algorithm is more robust, especially against geometric distortion, while having excellent frequency properties.

Abstract: The security strategy description is important contents of security access control research about grid. The strategy of traditional access control models has ignored the subject security, and can not be solved with the dynamic grid, and the characteristics of the coexistence of multiple security strategy etc problems. Regarding the concept of subject/ object decomposition and the organization classifications are defined, and the concepts of subject safe service, object safe service, and granularity control etc are expanded, Using the RBAC model and BLP the model basic principle, a group new access control security strategy based on the grid environment have be given in the paper. After discussion shows that the new rules emphasis on the subject security, and adapt to the dynamic nature of grid environment and characteristics of the coexistence of multiple security strategy. The new rules are compatibility with existing network access control model, they are secure and are also an expansion under the common network environment access control strategy, and this has certain positive significance to the grid security research.

Abstract: Aiming at pounding damage at expansion joint in a bridge under earthquake, the paper builds space dynamic models of a curved bridge and a linear bridge with expansion joint. Using nonlinear time history analysis, the paper contrasts the difference of pounding response at expansion joint in the linear bridge and the curved bridge and gives their simulation result under eight types of seismic input. The result indicates that the pounding response at expansion joint of curved bridge is larger and more obvious than that of linear bridge, especially at abutment expansion joint.

Abstract: This paper deals with an experimental study on the seismic performance of haunched transfer beam structures with varied ratio of section height to thickness of short-leg shearwall (RHT). Based on the seismic tests of three 1:3-scaled specimens under low-frequency cyclic lateral load with constant vertical actions, the failure pattern, the hysteresis curves, the skeleton curves, the energy dissipation capacity, and the stiffness degradation laws of haunched transfer beam structures are investigated. The effects of different RHT (i.e., 5, 6 and 7) on the seismic performance of haunched transfer beam structures are emphasized and analyzed in detail. It is concluded that the rigidity of the structure is noticeable enhanced, the endogen force becomes more evenly distributed and the bearing is more rational with an increase of the RHT; the rationally designed haunched transfer beam structure has a good seismic behavior.