Using the single crack solution and the regular solution of plane harmonic function, the problem of Saint_Venant bending of a cracked cylinder by a transverse force was reduced to solving two sets of integral equation...Using the single crack solution and the regular solution of plane harmonic function, the problem of Saint_Venant bending of a cracked cylinder by a transverse force was reduced to solving two sets of integral equations and its general solution was then obtained. Based on the obtained solution, a method to calculate the bending center and the stress intensity factors of the cracked cylinger whose cross_section is not thin_walled, but of small torsion rigidity is proposed. Some numerical examples are given.展开更多
In this paper, we consider a method of centers for solving multi-objective programming problems, where the objective functions involved are concave functions and the set of feasible points is convex. The algorithm is ...In this paper, we consider a method of centers for solving multi-objective programming problems, where the objective functions involved are concave functions and the set of feasible points is convex. The algorithm is defined so that the sub-problems that must be solved during its execution may be solved by finite-step procedures. Conditions are given under which the algorithm generates sequences of feasible points and constraint multiplier vectors that have accumulation points satisfying the KKT conditions. Finally, we establish convergence of the proposed method of centers algorithm for solving multiobjective programming problems.展开更多
This paper proposes a hybrid vertex-centered fi- nite volume/finite element method for solution of the two di- mensional （2D） incompressible Navier-Stokes equations on unstructured grids. An incremental pressure fra...This paper proposes a hybrid vertex-centered fi- nite volume/finite element method for solution of the two di- mensional （2D） incompressible Navier-Stokes equations on unstructured grids. An incremental pressure fractional step method is adopted to handle the velocity-pressure coupling. The velocity and the pressure are collocated at the node of the vertex-centered control volume which is formed by join- ing the centroid of cells sharing the common vertex. For the temporal integration of the momentum equations, an im- plicit second-order scheme is utilized to enhance the com- putational stability and eliminate the time step limit due to the diffusion term. The momentum equations are discretized by the vertex-centered finite volume method （FVM） and the pressure Poisson equation is solved by the Galerkin finite el- ement method （FEM）. The momentum interpolation is used to damp out the spurious pressure wiggles. The test case with analytical solutions demonstrates second-order accuracy of the current hybrid scheme in time and space for both veloc- ity and pressure. The classic test cases, the lid-driven cavity flow, the skew cavity flow and the backward-facing step flow, show that numerical results are in good agreement with the published benchmark solutions.展开更多
A definition of combined phase center for horn feeds is given.Formulas of E-planeand H-plane combined phase center for conical horns and the corresponding Optimal model arepresented,and a fast optimization method for ...A definition of combined phase center for horn feeds is given.Formulas of E-planeand H-plane combined phase center for conical horns and the corresponding Optimal model arepresented,and a fast optimization method for solving this model is described.By using thismethod,the phase center of corrugated horn is discussed and calculated,and the variation of thephase center with distance and operating frequency is given.展开更多
It takes more time and is easier to fall into the local minimum value when using the traditional full-supervised learning algorithm to train RBFNN. Therefore, the paper proposes one algorithm to determine the RBFNN’s...It takes more time and is easier to fall into the local minimum value when using the traditional full-supervised learning algorithm to train RBFNN. Therefore, the paper proposes one algorithm to determine the RBFNN’s data center based on the improvement density method. First it uses the improved density method to select RBFNN’s data center, and calculates the expansion constant of each center, then only trains the network weight with the gradient descent method. To compare this method with full-supervised gradient descent method, the time not only has obvious reduction (including to choose data center’s time by density method), but also obtains better classification results when using the data set in UCI to carry on the test to the network.展开更多
Using the single crack solution and the regular solution elf plane harmonic function, the problem of Saint-Venant bending of a cracked cylinder by a transverse force was reduced to solving two sets of integral equatio...Using the single crack solution and the regular solution elf plane harmonic function, the problem of Saint-Venant bending of a cracked cylinder by a transverse force was reduced to solving two sets of integral equations and its general solution was then obtained. Based on the obtained solution, a method to calculate the bending center and the stress intensity factors of the cracked cylinger whose cross-section is not thin-walled, but of small torsion rigidity is proposed. Some numerical examples are given.展开更多
Introduction: Maternal mortality, which is estimated at 614 deaths per 100,000 births in Côte d’Ivoire, is associated with a low national contraceptive prevalence rate of 13.9%. In this study, we are interes...Introduction: Maternal mortality, which is estimated at 614 deaths per 100,000 births in Côte d’Ivoire, is associated with a low national contraceptive prevalence rate of 13.9%. In this study, we are interested in the contraceptive experiences of women who attend health centers to estimate their rate of contraceptive use and to assess the factors involved in the use of modern contraceptive methods among women of childbearing age who are exposed to the risk of pregnancy. Method: A descriptive cross-sectional study was conducted from December 2018 to September 2019 among 423 women, who attended two health centers in Abidjan. A bivariate analysis identified factors associated with contraceptive use by these women. A descriptive analysis determined the means for the quantitative variables and the frequencies and percentages of qualitative variables. Interpretation of results was based on significance (α = 5%, 95% CI). Results: Contraceptive prevalence was 37%. There was a significant relationship between contraceptive use and the socio-demographic and reproductive characteristics of women (p Conclusion: Women who were over 35 years age, uneducated, primary school graduates, housewives, unemployed, in the informal sector, Muslims, nulliparous, and lacking information and decision-making power were less likely to use modern contraceptive methods. They are the target population for strategic interventions to improve contraceptive prevalence.展开更多
3×3块鞍点问题作为一类特殊的线性方程组,其迭代方法的研究极具挑战性。基于经典的广义逐次超松弛(Generalized Successive Over Relaxation,GSOR)方法,针对3×3块大型稀疏鞍点问题,提出了三参数的中心预处理GSOR方法并讨论了...3×3块鞍点问题作为一类特殊的线性方程组,其迭代方法的研究极具挑战性。基于经典的广义逐次超松弛(Generalized Successive Over Relaxation,GSOR)方法,针对3×3块大型稀疏鞍点问题,提出了三参数的中心预处理GSOR方法并讨论了其收敛性。同时,通过数值实验验证了新方法在计算花费方面优于中心预处理的Uzawa-Low方法。进一步地,还将新方法拓展到i×i块鞍点问题,提出了相应的GSOR类迭代框架,通过数值实验和数据分析,给出了选择较优i的初步建议。展开更多
文摘Using the single crack solution and the regular solution of plane harmonic function, the problem of Saint_Venant bending of a cracked cylinder by a transverse force was reduced to solving two sets of integral equations and its general solution was then obtained. Based on the obtained solution, a method to calculate the bending center and the stress intensity factors of the cracked cylinger whose cross_section is not thin_walled, but of small torsion rigidity is proposed. Some numerical examples are given.
文摘In this paper, we consider a method of centers for solving multi-objective programming problems, where the objective functions involved are concave functions and the set of feasible points is convex. The algorithm is defined so that the sub-problems that must be solved during its execution may be solved by finite-step procedures. Conditions are given under which the algorithm generates sequences of feasible points and constraint multiplier vectors that have accumulation points satisfying the KKT conditions. Finally, we establish convergence of the proposed method of centers algorithm for solving multiobjective programming problems.
基金supported by the Natural Science Foundation of China (11061021)the Program of Higher-level talents of Inner Mongolia University (SPH-IMU,Z200901004)the Scientific Research Projection of Higher Schools of Inner Mongolia(NJ10016,NJ10006)
文摘This paper proposes a hybrid vertex-centered fi- nite volume/finite element method for solution of the two di- mensional （2D） incompressible Navier-Stokes equations on unstructured grids. An incremental pressure fractional step method is adopted to handle the velocity-pressure coupling. The velocity and the pressure are collocated at the node of the vertex-centered control volume which is formed by join- ing the centroid of cells sharing the common vertex. For the temporal integration of the momentum equations, an im- plicit second-order scheme is utilized to enhance the com- putational stability and eliminate the time step limit due to the diffusion term. The momentum equations are discretized by the vertex-centered finite volume method （FVM） and the pressure Poisson equation is solved by the Galerkin finite el- ement method （FEM）. The momentum interpolation is used to damp out the spurious pressure wiggles. The test case with analytical solutions demonstrates second-order accuracy of the current hybrid scheme in time and space for both veloc- ity and pressure. The classic test cases, the lid-driven cavity flow, the skew cavity flow and the backward-facing step flow, show that numerical results are in good agreement with the published benchmark solutions.
文摘A definition of combined phase center for horn feeds is given.Formulas of E-planeand H-plane combined phase center for conical horns and the corresponding Optimal model arepresented,and a fast optimization method for solving this model is described.By using thismethod,the phase center of corrugated horn is discussed and calculated,and the variation of thephase center with distance and operating frequency is given.
文摘It takes more time and is easier to fall into the local minimum value when using the traditional full-supervised learning algorithm to train RBFNN. Therefore, the paper proposes one algorithm to determine the RBFNN’s data center based on the improvement density method. First it uses the improved density method to select RBFNN’s data center, and calculates the expansion constant of each center, then only trains the network weight with the gradient descent method. To compare this method with full-supervised gradient descent method, the time not only has obvious reduction (including to choose data center’s time by density method), but also obtains better classification results when using the data set in UCI to carry on the test to the network.
文摘Using the single crack solution and the regular solution elf plane harmonic function, the problem of Saint-Venant bending of a cracked cylinder by a transverse force was reduced to solving two sets of integral equations and its general solution was then obtained. Based on the obtained solution, a method to calculate the bending center and the stress intensity factors of the cracked cylinger whose cross-section is not thin-walled, but of small torsion rigidity is proposed. Some numerical examples are given.
文摘Introduction: Maternal mortality, which is estimated at 614 deaths per 100,000 births in Côte d’Ivoire, is associated with a low national contraceptive prevalence rate of 13.9%. In this study, we are interested in the contraceptive experiences of women who attend health centers to estimate their rate of contraceptive use and to assess the factors involved in the use of modern contraceptive methods among women of childbearing age who are exposed to the risk of pregnancy. Method: A descriptive cross-sectional study was conducted from December 2018 to September 2019 among 423 women, who attended two health centers in Abidjan. A bivariate analysis identified factors associated with contraceptive use by these women. A descriptive analysis determined the means for the quantitative variables and the frequencies and percentages of qualitative variables. Interpretation of results was based on significance (α = 5%, 95% CI). Results: Contraceptive prevalence was 37%. There was a significant relationship between contraceptive use and the socio-demographic and reproductive characteristics of women (p Conclusion: Women who were over 35 years age, uneducated, primary school graduates, housewives, unemployed, in the informal sector, Muslims, nulliparous, and lacking information and decision-making power were less likely to use modern contraceptive methods. They are the target population for strategic interventions to improve contraceptive prevalence.
文摘3×3块鞍点问题作为一类特殊的线性方程组,其迭代方法的研究极具挑战性。基于经典的广义逐次超松弛(Generalized Successive Over Relaxation,GSOR)方法,针对3×3块大型稀疏鞍点问题,提出了三参数的中心预处理GSOR方法并讨论了其收敛性。同时,通过数值实验验证了新方法在计算花费方面优于中心预处理的Uzawa-Low方法。进一步地,还将新方法拓展到i×i块鞍点问题,提出了相应的GSOR类迭代框架,通过数值实验和数据分析,给出了选择较优i的初步建议。
