Background Motion Video Tracking of the Memory Watershed Disc Gradient Expansion Template

Yao Nan,Shen Haiping 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.4

In order to further improve motion video target tracking and detection accuracy, a motion video tracking algorithm based on memory watershed disc gradient expansion template is proposed in this article. Firstly, heterodromous diffusion is executed to preprocess the motion video image in order to reduce the noise interference in the motion target tracking and detection process, and meanwhile the differential operation and the morphological operation are executed to extract and operate the outer profile of the motion object. Secondly, in allusion to the excessive division in the watershed algorithm, target marking and division of the watershed algorithm are realized on the basis of characteristic memory, and the accurate detection of the motion target is realized on the basis of the disc gradient expansion template. Finally, according to the experimental comparison, the algorithm proposed in this article can be applied in the complex background detection of the motion target, and such algorithm can not only improve the motion target detection accuracy, but also significantly improve computation speed.

Ciphertext-Policy Attribute-Based Encryption with Hidden Access Policy and Testing

( Jiguo Li ),( Haiping Wang ),( Yichen Zhang ),( Jian Shen ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.7

In ciphertext-policy attribute-based encryption (CP-ABE) scheme, a user`s secret key is associated with a set of attributes, and the ciphertext is associated with an access policy. The user can decrypt the ciphertext if and only if the attribute set of his secret key satisfies the access policy specified in the ciphertext. In the present schemes, access policy is sent to the decryptor along with the ciphertext, which means that the privacy of the encryptor is revealed. In order to solve such problem, we propose a CP-ABE scheme with hidden access policy, which is able to preserve the privacy of the encryptor and decryptor. And what`s more in the present schemes, the users need to do excessive calculation for decryption to check whether their attributes match the access policy specified in the ciphertext or not, which makes the users do useless computation if the attributes don`t match the hidden access policy. In order to solve efficiency issue, our scheme adds a testing phase to avoid the unnecessary operation above before decryption. The computation cost for the testing phase is much less than the decryption computation so that the efficiency in our scheme is improved. Meanwhile, our new scheme is proved to be selectively secure against chosen-plaintext attack under DDH assumption.

Nonlinear bending of functionally graded porous nanobeam subjected to multiple physical load based on nonlocal strain gradient theory

Yang Gao,Wan-Shen Xiao,Haiping Zhu 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.5

We in this paper study nonlinear bending of a functionally graded porous nanobeam subjected to multiple physical load based on the nonlocal strain gradient theory. For more reasonable analysis of nanobeams made of porous functionally graded magneto-thermo-electro-elastic materials (PFGMTEEMs), both constituent materials and the porosity appear gradient distribution in the present expression of effective material properties, which is much more suitable to the actual compared with the conventional expression of effective material properties. Besides the displacement function regarding physical neutral surface is introduced to analyze mechanical behaviors of beams made of FGMs. Then we derive nonlinear governing equations of PFGMTEEMs beams using the principle of Hamilton. To obtain analytical solutions, a two-step perturbation method is developed in nonuniform electric field and magnetic field, and then we use it to solve nonlinear equations. Finally, the analytical solutions are utilized to perform a parametric analysis, where the effect of various physical parameters on static bending deformation of nanobeams are studied in detail, such as the nonlocal parameter, strain gradient parameter, the ratio of nonlocal parameter to strain gradient parameter, porosity volume fraction, material volume fraction index, temperature, initial magnetic potentials and external electric potentials.

Nonlinear vibration of functionally graded nano-tubes using nonlocal strain gradient theory and a two-steps perturbation method

Yang Gao,Wan-Shen Xiao,Haiping Zhu 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.2

This paper analyzes nonlinear free vibration of the circular nano-tubes made of functionally graded materials in the framework of nonlocal strain gradient theory in conjunction with a refined higher order shear deformation beam model. The effective material properties of the tube related to the change of temperature are assumed to vary along the radius of tube based on the power law. The refined beam model is introduced which not only contains transverse shear deformation but also satisfies the stress boundary conditions where shear stress cancels each other out on the inner and outer surfaces. Moreover, it can degenerate the Euler beam model, the Timoshenko beam model and the Reddy beam model. By incorporating this model with Hamilton’s principle, the nonlinear vibration equations are established. The equations, including a material length scale parameter as well as a nonlocal parameter, can describe the size-dependent in linear and nonlinear vibration of FGM nanotubes. Analytical solution is obtained by using a two-steps perturbation method. Several comparisons are performed to validate the present analysis. Eventually, the effects of various physical parameters on nonlinear and linear natural frequencies of FGM nanotubes are analyzed, such as inner radius, temperature, nonlocal parameter, strain gradient parameter, scale parameter ratio, slenderness ratio, volume indexes, different beam models.

Nonlinear thermal buckling of bi-directional functionally graded nanobeams

Yang Gao,Wan-Shen Xiao,Haiping Zhu 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.71 No.6

We in this article study nonlinear thermal buckling of bi-directional functionally graded beams in the theoretical frameworks of nonlocal strain graded theory. To begin with, it is assumed that the effective material properties of beams vary continuously in both the thickness and width directions. Then, we utilize a higher-order shear deformation theory that includes a physical neutral surface to derive the size-dependent governing equations combining with the Hamilton’s principle and the von Kármán geometric nonlinearity. It should be pointed out that the established model, containing a nonlocal parameter and a strain gradient length scale parameter, can availably account for both the influence of nonlocal elastic stress field and the influence of strain gradient stress field. Subsequently, via using a easier group of initial asymptotic solutions, the corresponding analytical solution of thermal buckling of beams is obtained with the help of perturbation method. Finally, a parametric study is carried out in detail after validating the present analysis, especially for the effects of a nonlocal parameter, a strain gradient length scale parameter and the ratio of the two on the critical thermal buckling temperature of beams.

On axial buckling and post-buckling of geometrically imperfect single-layer graphene sheets

Yang Gao,Wan-Shen Xiao,Haiping Zhu 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.2

The main objective of this paper is to study the axial buckling and post-buckling of geometrically imperfect single-layer graphene sheets (GSs) under in-plane loading in the theoretical framework of the nonlocal strain gradient theory. To begin with, a graphene sheet is modeled by a two-dimensional plate subjected to simply supported ends, and supposed to have a small initial curvature. Then according to the Hamilton*$39;s principle, the nonlinear governing equations are derived with the aid of the classical plate theory and the von-karman nonlinearity theory. Subsequently, for providing a more accurate physical assessment with respect to the influence of respective parameters on the mechanical performances, the approximate analytical solutions are acquired via using a two-step perturbation method. Finally, the authors perform a detailed parametric study based on the solutions, including geometric imperfection, nonlocal parameters, strain gradient parameters and wave mode numbers, and then reaching a significant conclusion that both the size-dependent effect and a geometrical imperfection can't be ignored in analyzing GSs.