A computer code based on the double-body potential flow model and the classic source panel method has been developed to study various problems of hydrodynamic interaction between ships and other objects with solid bou...A computer code based on the double-body potential flow model and the classic source panel method has been developed to study various problems of hydrodynamic interaction between ships and other objects with solid boundaries including the seabed. A peculiarity of the proposed implementation is the application of the so-called ＂moving-patch＂ method for simulating steady boundaries of large extensions. The method is based on an assumption that at any moment just the part of the boundary （＂moving patch＂） which lies close to the interacting ship is significant for the near-field interaction. For a specific case of the fiat bottom, comparative computations were performed to determine optimal dimensions of the patch and of the constituting panels based on the trade-off between acceptable accuracy and reasonable efficiency. The method was applied to estimate the sway force on a ship hull moving obliquely across a dredged channel. The method was validated for a case of ship-to-ship interaction when tank data were available. This study also contains a description of a newly developed spline approximation algorithm necessary for creating consistent discretizations of ship hulls with various degrees of refinement.展开更多
In this paper, we review some results on the spectral methods. We first consider the Jacobi spectral method and the generalized Jacobi spectral method for various problems, including degenerated and singular different...In this paper, we review some results on the spectral methods. We first consider the Jacobi spectral method and the generalized Jacobi spectral method for various problems, including degenerated and singular differential equations. Then we present the generalized Jacobi quasi-orthogonal approximation and its applica- tions to the spectral element methods for high order problems with mixed inhomogeneous boundary conditions. We also discuss the related spectral methods for non-rectangular domains and the irrational spectral methods for unbounded domains. Next, we consider the Hermite spectral method and the generalized Hermite spec- tral method with their applications. Finally, we consider the Laguerre spectral method and the generalized Laguerre spectral method for many problems defined on unbounded domains. We also present the generalized Laguerre quasi-orthogonal approximation and its applications to certain problems of non-standard type and exterior problems.展开更多
The prestress developing of tensile cable-net structures is a state transforming process from the initial unstressed state to the final prestressed state, and it is rather complicated because the elastic deformation i...The prestress developing of tensile cable-net structures is a state transforming process from the initial unstressed state to the final prestressed state, and it is rather complicated because the elastic deformation is normally coupled with the kinematic mechanism movement. Firstly, the basic equations of prestress developing by moving boundary joint are derived from the total potential energy equation. Secondly, the presumed initial tension is proposed to impose into the elements and avoid the singularity of global stiffness matrix. And the self-stress mode which is calculated from the equilibrium matrix with singular vMue decomposition is employed as basically presumed initial tension. By applying boundary movement increment, an iterative computation is developed to calculate the updating geometric configuration and tension evolution. Finally, the MATLAB program is coded from the presented method, and numerical examples indicate that this computational method is effective and has theoretical significance and valuable guide to design and construction of tensile cable-net structure.展开更多
基金Supported by the Portuguese Foundation for Science and Technology under Grant No.PTDC/ECM/100686/2008
文摘A computer code based on the double-body potential flow model and the classic source panel method has been developed to study various problems of hydrodynamic interaction between ships and other objects with solid boundaries including the seabed. A peculiarity of the proposed implementation is the application of the so-called ＂moving-patch＂ method for simulating steady boundaries of large extensions. The method is based on an assumption that at any moment just the part of the boundary （＂moving patch＂） which lies close to the interacting ship is significant for the near-field interaction. For a specific case of the fiat bottom, comparative computations were performed to determine optimal dimensions of the patch and of the constituting panels based on the trade-off between acceptable accuracy and reasonable efficiency. The method was applied to estimate the sway force on a ship hull moving obliquely across a dredged channel. The method was validated for a case of ship-to-ship interaction when tank data were available. This study also contains a description of a newly developed spline approximation algorithm necessary for creating consistent discretizations of ship hulls with various degrees of refinement.
基金supported by National Natural Science Foundation of China(Grant No.11171227)Fund for Doctoral Authority of China(Grant No.20123127110001)+1 种基金Fund for E-institute of Shanghai Universities(Grant No.E03004)Leading Academic Discipline Project of Shanghai Municipal Education Commission(Grant No.J50101)
文摘In this paper, we review some results on the spectral methods. We first consider the Jacobi spectral method and the generalized Jacobi spectral method for various problems, including degenerated and singular differential equations. Then we present the generalized Jacobi quasi-orthogonal approximation and its applica- tions to the spectral element methods for high order problems with mixed inhomogeneous boundary conditions. We also discuss the related spectral methods for non-rectangular domains and the irrational spectral methods for unbounded domains. Next, we consider the Hermite spectral method and the generalized Hermite spec- tral method with their applications. Finally, we consider the Laguerre spectral method and the generalized Laguerre spectral method for many problems defined on unbounded domains. We also present the generalized Laguerre quasi-orthogonal approximation and its applications to certain problems of non-standard type and exterior problems.
基金the National Natural Science Foundation of China (Nos. 50878128 and 51278299)
文摘The prestress developing of tensile cable-net structures is a state transforming process from the initial unstressed state to the final prestressed state, and it is rather complicated because the elastic deformation is normally coupled with the kinematic mechanism movement. Firstly, the basic equations of prestress developing by moving boundary joint are derived from the total potential energy equation. Secondly, the presumed initial tension is proposed to impose into the elements and avoid the singularity of global stiffness matrix. And the self-stress mode which is calculated from the equilibrium matrix with singular vMue decomposition is employed as basically presumed initial tension. By applying boundary movement increment, an iterative computation is developed to calculate the updating geometric configuration and tension evolution. Finally, the MATLAB program is coded from the presented method, and numerical examples indicate that this computational method is effective and has theoretical significance and valuable guide to design and construction of tensile cable-net structure.
