The Experts below are selected from a list of 60045 Experts worldwide ranked by ideXlab platform

Cui Zhang - One of the best experts on this subject based on the ideXlab platform.

Yusen Wu - One of the best experts on this subject based on the ideXlab platform.

  • Bifurcation of limit cycles at degenerate Singular Point and infinity in a septic system
    Advances in Difference Equations, 2013
    Co-Authors: Yusen Wu, Feng Li
    Abstract:

    In this paper, the problem of bifurcation of limit cycles from degenerate Singular Point and infinity in a class of septic polynomial differential systems is investigated. Using the computer algebra system Mathematica, the limit cycle configurations of { ( 8 ) , 3 } Open image in new window and { ( 3 ) , 6 } Open image in new window are obtained under synchronous perturbation at degenerate Singular Point and infinity. To our knowledge, up to now, this is the first time that the problem of limit cycles bifurcated from degenerate Singular Point and infinity under synchronous perturbed conditions in a septic system has been investigated.

  • Bifurcation of limit cycles and pseudo-isochronous center at degenerate Singular Point in a septic system☆
    Applied Mathematics and Computation, 2012
    Co-Authors: Yusen Wu, Cui Zhang
    Abstract:

    Abstract In this literature we are concerned with the bifurcation of limit cycles and pseudo-isochronous center conditions at degenerate Singular Point in a polynomial differential system of degree seven. The key contribution of this paper is to give an example of septic system with 8 limit cycles bifurcated from the degenerate Singular Point and list its pseudo-isochronous center conditions.

  • Bifurcation of Limit Cycles and Pseudo-Isochronicity at Degenerate Singular Point in a Septic System
    Results in Mathematics, 2010
    Co-Authors: Yusen Wu, Cui Zhang
    Abstract:

    This paper deals with the problems of bifurcation of limit cycles and pseudo-isochronous center conditions at degenerate Singular Point in a class of septic polynomial differential system. We solve the problems by an indirect method, i.e., we transform the degenerate Singular Point into an elementary Singular Point. Then we construct a septic system which allows the appearance of eight limit cycles in the neighborhood of degenerate Singular Point. Finally, we investigate the pseudo-isochronous center conditions at degenerate Singular Point for the system. As far as we know, this is the first time that an example of septic system with eight limit cycles bifurcating from degenerate Singular Point is given, and it is also the first time the pseudo-isochronous center conditions at degenerate Singular Point in a septic system are discussed.

Hideo Koguchi - One of the best experts on this subject based on the ideXlab platform.

  • Stress Singularity analysis around the Singular Point on the stress Singularity line in three-dimensional joints
    International Journal of Solids and Structures, 2004
    Co-Authors: Monchai Prukvilailert, Hideo Koguchi
    Abstract:

    Abstract The characteristics of the stress fields around a Singular Point on the stress Singularity line of dissimilar materials in three-dimensional joints are investigated using BEM. Contour for the order of stress Singularity around the Point is mapped on Dundurs’ parameters plane using eigen value analysis by FEM. The results in 3D joints are compared with those in 2D joints having the same cross section and material combination. The order of stress Singularity around the Singular Point on the stress Singularity line in 3D joints is almost identical with that in 2D joints in the Singularity region. However, the zero boundary of Singularity in 3D joints is slightly different from that in 2D joints. Furthermore, the multiple root of p  = 1 exists in the eigen value analysis by FEM. Therefore, logarithmic Singularity possibly occurs around the Singular Point on the stress Singularity line. Then, the stress distributions around this Point are expressed by the combination of the r λ term and logarithmic Singularity terms. Finally, the characteristics of the stress intensity factors of the r λ term and logarithmic Singularity terms around the Singular Points are investigated.

Jiangzhou Wang - One of the best experts on this subject based on the ideXlab platform.

  • an adaptive element subdivision technique for evaluation of various 2d Singular boundary integrals
    Engineering Analysis With Boundary Elements, 2008
    Co-Authors: Xiaowei Gao, Kai Yang, Jiangzhou Wang
    Abstract:

    In this paper, a unified algorithm is presented for the numerical evaluation of weakly, strongly and hyper Singular boundary integrals with or without a logarithmic term, which often appear in two-dimensional boundary element analysis equations. In this algorithm, the Singular boundary element is broken up into a few sub-elements. The sub-elements involving the Singular Point are evaluated analytically to remove the Singularities by expressing the non-Singular parts of the integration kernels as polynomials of the distance r, while other sub-elements are evaluated numerically by the standard Gaussian quadrature. The number of sub-elements and their sizes are determined according to the Singularity order and the position of the Singular Point. Numerical examples are provided to demonstrate the correctness and efficiency of the proposed algorithm.

Christophe Tournier - One of the best experts on this subject based on the ideXlab platform.

  • A tool path patching strategy around Singular Point in 5-axis ball-end milling
    International Journal of Production Research, 2016
    Co-Authors: Laureen Grandguillaume, Sylvain Lavernhe, Christophe Tournier
    Abstract:

    In 5-axis high speed milling, large incoherent movements of rotary axes around the Singular Point are known to be a problem. Correction methods found in the literature deal mostly with the collision that may happen between the tool and the part but not with the feedrate slowdowns which affect surface quality and machining productivity. The method proposed in this paper addresses both geometrical and productivity issues by modifying the tool axes orientation while respecting maximum velocity, acceleration and jerk of the machine-tool axes. The aim is to detect these behaviors and replace the considered portion of the tool path by a patch curve respecting kinematical contraints of the machine tool. Compare to previous works, the inserted patch curve is not constrained to pass through the Singularity but respect tangential contrains to ensure the monotony of the tool path and is also connected with the rest of the tool path to ensure a continuity up to the third derivative in order to fulfill jerk limitations. For that purpose, the initial articular positions of the rotary axes around the Singular Point are fitted with B-spline curves, modified and finally discretized for linear interpolation. Experimental investigations on a test part are carried out to show the efficiency of the method in terms of feedrate and surface quality.