This paper gives the perturbation formulation of continuation method for nonlinear equations. Emphasis is laid on the discussion of searching for the singular points on the equilibrium path and of tracing the paths ov...This paper gives the perturbation formulation of continuation method for nonlinear equations. Emphasis is laid on the discussion of searching for the singular points on the equilibrium path and of tracing the paths over the limit or bifurcation points. The method is applied to buckling analysis of thin shells. The pre-and post-buckling equilibrium paths and deflections can be obtained, which are illustrated in examples of buckling analysis of cylindrical and toroidal shells.展开更多
Postbuckling behavior for Reissner's rectangular moderately thick plates and sandwich plates was investigated. The fundamental equations and boundary conditions were expressed in unified dimensionless form for rec...Postbuckling behavior for Reissner's rectangular moderately thick plates and sandwich plates was investigated. The fundamental equations and boundary conditions were expressed in unified dimensionless form for rectangular moderately thick plates and sandwich plates. Exact solutions of series form with a number of different boundary conditions, especially with unsymmetrical boundary conditions, were obtained by developing a new technique of mixed Fourier series in nonlinear analysis. The nonlinear partial differential equations were reduced to an infinite set of simultaneous nonlinear algebraic equations, which were truncated by iteration in numerical computations.展开更多
Nettings are complex flexible structures used in various fisheries.Understanding the hydrodynamic characteristics,de-formation,and the flow field around nettings is important to design successful fishing gear.This stu...Nettings are complex flexible structures used in various fisheries.Understanding the hydrodynamic characteristics,de-formation,and the flow field around nettings is important to design successful fishing gear.This study investigated the hydrodynamic characteristics and deformation of five nettings made of polyethylene and nylon materials in different attack angles through numeri-cal simulation and physical model experiment.The numerical model was based on the one-way coupling between computational fluid dynamics(CFD)and large deflection nonlinear structural models.Navier-Stokes equations were solved using the finite volume ap-proach,the flow was described using the k-ωshear stress turbulent model,and the large deflection structural dynamic equation was derived using a finite element approach to understand the netting deformation and nodal displacement.The porous media model was chosen to model the nettings in the CFD solver.Numerical data were compared with the experimental results of the physical model to validate the numerical models.Results showed that the numerical data were compatible with the experimental data with an average relative error of 2.34%,3.40%,6.50%,and 5.80%in the normal drag coefficients,parallel drag coefficients,inclined drag coefficients,and inclined lift coefficients,respectively.The hydrodynamic forces of the polyethylene and nylon nettings decreased by approxi-mately 52.56%and 66.66%,respectively,with decreasing net solidity.The drag and lift coefficients of the nylon netting were appro-ximately 17.15%and 6.72%lower than those of the polyethylene netting.A spatial development of turbulent flow occurred around the netting because of the netting wake.However,the flow velocity reduction downstream from the netting in the wake region in-creased with increasing attack angle and net solidity.In addition,the deformation,stress,and strain on each netting increased with in-creasing solidity ratio.展开更多
We present the moments formalism theory to study the deflection of the slow signal light in the cold atomic media, which is under the condition of the Gaussian control laser and electromagnetically induced transparenc...We present the moments formalism theory to study the deflection of the slow signal light in the cold atomic media, which is under the condition of the Gaussian control laser and electromagnetically induced transparency. Deflection, the interesting phenomenon on quantum coherence, is testified by analytic and numerical methods. Results show that, as the signal light propagating in the medium, there would be an observable deflection before the general diffraction. Influences of the coupling intensity on deflection phenomenon and the beam waist of the signal light in the medium are also investigated.展开更多
文摘This paper gives the perturbation formulation of continuation method for nonlinear equations. Emphasis is laid on the discussion of searching for the singular points on the equilibrium path and of tracing the paths over the limit or bifurcation points. The method is applied to buckling analysis of thin shells. The pre-and post-buckling equilibrium paths and deflections can be obtained, which are illustrated in examples of buckling analysis of cylindrical and toroidal shells.
文摘Postbuckling behavior for Reissner's rectangular moderately thick plates and sandwich plates was investigated. The fundamental equations and boundary conditions were expressed in unified dimensionless form for rectangular moderately thick plates and sandwich plates. Exact solutions of series form with a number of different boundary conditions, especially with unsymmetrical boundary conditions, were obtained by developing a new technique of mixed Fourier series in nonlinear analysis. The nonlinear partial differential equations were reduced to an infinite set of simultaneous nonlinear algebraic equations, which were truncated by iteration in numerical computations.
基金This study was financially sponsored by the National Natural Science Foundation of China(Nos.31902426,41806110)the Shanghai Sailing Program(No.19YF1419800)+1 种基金the National Key R&D Program of China(No.2019YFD 0901502)the Special Project for the Exploitation and Utilization of Antarctic Biological Resources of Ministry of Agriculture and Rural Affairs(No.D-8002-18-0097).
文摘Nettings are complex flexible structures used in various fisheries.Understanding the hydrodynamic characteristics,de-formation,and the flow field around nettings is important to design successful fishing gear.This study investigated the hydrodynamic characteristics and deformation of five nettings made of polyethylene and nylon materials in different attack angles through numeri-cal simulation and physical model experiment.The numerical model was based on the one-way coupling between computational fluid dynamics(CFD)and large deflection nonlinear structural models.Navier-Stokes equations were solved using the finite volume ap-proach,the flow was described using the k-ωshear stress turbulent model,and the large deflection structural dynamic equation was derived using a finite element approach to understand the netting deformation and nodal displacement.The porous media model was chosen to model the nettings in the CFD solver.Numerical data were compared with the experimental results of the physical model to validate the numerical models.Results showed that the numerical data were compatible with the experimental data with an average relative error of 2.34%,3.40%,6.50%,and 5.80%in the normal drag coefficients,parallel drag coefficients,inclined drag coefficients,and inclined lift coefficients,respectively.The hydrodynamic forces of the polyethylene and nylon nettings decreased by approxi-mately 52.56%and 66.66%,respectively,with decreasing net solidity.The drag and lift coefficients of the nylon netting were appro-ximately 17.15%and 6.72%lower than those of the polyethylene netting.A spatial development of turbulent flow occurred around the netting because of the netting wake.However,the flow velocity reduction downstream from the netting in the wake region in-creased with increasing attack angle and net solidity.In addition,the deformation,stress,and strain on each netting increased with in-creasing solidity ratio.
基金supported by the National Natural Science Foundation of China(Nos.10404031,60477007, and 10774047)the Shanghai Optical-Tech Special Project(No.034119815)
文摘We present the moments formalism theory to study the deflection of the slow signal light in the cold atomic media, which is under the condition of the Gaussian control laser and electromagnetically induced transparency. Deflection, the interesting phenomenon on quantum coherence, is testified by analytic and numerical methods. Results show that, as the signal light propagating in the medium, there would be an observable deflection before the general diffraction. Influences of the coupling intensity on deflection phenomenon and the beam waist of the signal light in the medium are also investigated.
