Shiming Ji

A survey of the image copy detection

This paper presents a review of recent as well as classic image copy detection method. The reviewed methods are classified as digital watermarking and contended based copy detection. The contended based copy detection usually extracts robust features from image directly that is the main difference from the digital watermarking which features are embedded before distribute. Some new and key techniques are discussed that applied in watermarking and CBCD. Main contributions, advantages, and drawbacks of the methods are mentioned in the paper. Problematic issues of image copy detection and outlook for the future research are discussed too. The major goal of the paper is to provide a comprehensive reference source for the researchers involved in image copy detection, regardless of particular application areas.

Principle of image encrypting algorithm based on magic cube transformation

A new method for digital image scrambling transformation, namely Magic Cube Transformation, was proposed and its principle was introduced. Combined with the Logistic mapping in non-linear dynamics system, an image encrypting and decrypting algorithm based on Magic Cube Transformation was designed. A natural chaotic sequence was created with the key. The image matrix was transformed with this chaotic sequence, using the Magic Cube Transformation. Then an encrypted image was resulted. The decrypting operation was the reverse process of encryption. The experimental results indicate that the proposed algorithm can get satisfying effect. Finally, the characteristics of the algorithm were summarized and the aspects of the subsequent work were prospected.

Optimal Design of Parallel Robots for the Prescribed Regular Dexterous Workspace

This paper presents a method for determining design parameters of parallel robots (PRs) in its optimal kinematic design. To produce a more compact and economical PR, the determination of an optimal workspace is important. This includes defining a workspace that encases the prescribed regular dexterous workspace (PRDW). Two requirements should be simultaneously satisfied: (i) the local or global performance index; (ii) a regular shape. In this paper, the optimal problem is firstly discussed and translated into two linear problems. Then, an optimal design procedure which adopts the generalized pattern search algorithm in the genetic algorithm and direct search toolbox of Matlab is proposed to solve these problems. Taken as an example, a linear Delta robot is designed for the four different PRDWs, and its optimal result provides some useful information in measuring the distance between a PRDW and the maximal sized normalized robot. On the basis of the value of distance, some wrong solutions of PR are clarified. It is concluded that the optimal design method is useful for the design and comparison of a general PR.

Optimal design of a linear Delta robot for the prescribed cuboid dexterous workspace

This paper presents a new idea to determine a set of optimal design parameters of a linear delta robot (LDR) whose workspace is as close as possible of being equal to a prescribed cuboid dexterous workspace (PCDW). The optimal design procedure on the basis of three algorithms is introduced in this paper. The kinematic problem is analyzed in brief to determine the design parameters and their relation. Two algorithms are designed to determine the reachable, rectangular dexterous workspace, and the maximal inscribed rectangle of dexterous workspace in the O-xy plane. Another algorithm is used to solve the optimal problem. As applying example, the results of four cases PCDW to LDR are presented. And the design result is compared with a new concept of the distance between the best state of the LDR and the requirement of the operation task. The method and result of this paper are very useful for the design and comparison of the parallel robot.

A Methodology for Determining the Reachable and Dexterous Workspace of Parallel Manipulators

A methodology is proposed for determining the reachable and dexterous workspace of parallel manipulators. The determination of two types of workspace is utmost important in optimal design and comparing performances of the manipulators because each configuration or point in this region has specified kinematic dexterity by designer. The method is based on a stratified workspace boundary search technique, which is referred to as stratified workspace boundary determining methodology (SWBDM), and considers the various physical and contrived constraints. After the two similar problems of the determination of two types of workspace boundaries were defined, we propose a unified method to solve these problems. The validity and efficiency of the proposed method are verified with two kinds of representative parallel manipulators, since their relational results were studied in literatures. Finally, we conclude some advantages of the proposed methodology by comparing with other methods.

A Methodology for Determining the Maximal Regular-shaped Dexterous Workspace of the PMs

A methodology for determining the maximal regular-shaped dexterous workspace (MRsDW) of parallel manipulators (PMs) is proposed. The MRsDW is the maximal subset of the dexterous workspace with prescribed dexterity, and has a regular shape such as a circle or rectangle for the planar and a cuboid or cylinder for the spatial situation. It is one of the objects of optimal design of the PMs while the workspace size and shape are considered. The concept of the utilizable ratio of dexterous workspace (URDW) is introduced, which is a new measure for the rationality of design parameters of a PM. The methodology based on the stratified workspace boundary search technique can determine both the dexterous workspace and their MRsDW. After the problem of determination of the MRsDW is defined formally, a numerical method is proposed to solve this problem by three algorithms. Finally, the validity and efficiency of the proposed method are verified through application of the 2-DOF planar PM and the linear delta robot.

Method of monitoring wearing and breakage states of cutting tools based on Mahalanobis distance features

Abstract The Mahalanobis distance features proposed by Mahalanobis, an Indian statistician, can be used in an automatic online cutting tool condition monitoring process based on digital image processing. In this paper, a new method of obtaining Mahalanobis distance features from a tool image is proposed. It can automatically divide the component groups for calculating the Mahalanobis distance based on the gray level of wearing or breakage regions in a tool image. The wearing region can be divided into a high gray level component group and the tool-blade into low one. The relation between the Mahalanobis distance features of component groups and tool conditions is investigated. The results indicate that the Mahalanobis distance features of the high gray level component group are related with the wearing state of the tool and the low gray level component group correlated with the breakage of tool. The results also indicate that the Mahalanobis distance features have a higher sensitivity in expressing wearing or breakage states of tools.

Video program clustering indexing based on face recognition hybrid model of hidden markov model and support vector machine

Human face is a very important semantic cue in video program. Therefore, this paper presents to implement video program content indexing based on Gaussian clustering after face recognition through Support Vector Machine (SVM) and Hidden Markov Model (HMM) hybrid model. The task consists of following steps: first, SVM and HMM hybrid model is used to recognize human face by Independent basis feature of face apparatus; then, the recognized faces are clustered for video content indexing by Mixture Gaussian. From the experiments, the precision of the mixed model for face recognition is 97.8 percent, and the recall is 95.2, which is higher than the complexion model. And the precision of the face clustering indexing is 94.6 percent of the mixed model for compere new program. The indexing result of clustering is famous.

Optimal design of a linear delta robot for the prescribed regular-shaped dexterous workspace

This paper follows a method to determine a set of optimal design parameters of a linear Delta robot (LDR) whose workspace is as close as possible of being equal to a prescribed regular-shaped dexterous workspace (PRsDW). The design process proposed in this paper considers the particularity of the LDR. The kinematic problem is analyzed in brief to determine the design parameters and their relation at first. Two kinds of PRsDWs are considered, one is cylindrical dexterous workspace and the other is cuboid dexterous workspace. The optimal design parameters corresponding to the two kinds of PRsDWs are obtained by means of generalized pattern search algorithm (GPSA) in the genetic algorithm and direct search toolbox of Matlab, and the results of each PRsDW are compared to see the reasonability to the different operation tasks. The method and result of this paper are very useful for the design and comparison of the parallel robots.

A Y-Star Robot: Optimal Design for the Specified Workspace

This paper adopts a methodology to determine a set of optimal design parameters of a Y-Star robot whose workspace is as close as possible of being equal to a prescribed cylindrical dexterous workspace (PCDW). Two requirements should be satisfied simultaneously: (i) the local or global performance index; (ii) a regular shape. The kinematic problem is analyzed in brief to determine the design parameters and their relation at first. The optimal design problem with nonlinear constraints is discussed and then translated into two optimal problems without constraints. Then, an optimal design procedure which adopts the generalized pattern search algorithm in the genetic algorithm and direct search toolbox of Matlab is adopted to solve these problems. As an applying example, the results of four cases of PCDW to the robot are presented. And the design results are compared with a concept of the distance between the best state of the robot and the requirement of the operation task. The methodology and result of this paper are very useful for the design and comparison of the Y-Star robot.