Follow ing the fram ew ork of the finite elem ent m ethods based on Riesz-representing operators developed by Duan Huoyuan in 1997,through discreteRieszrepresenting-operators on som e virtual(non-) conform ing finit...Follow ing the fram ew ork of the finite elem ent m ethods based on Riesz-representing operators developed by Duan Huoyuan in 1997,through discreteRieszrepresenting-operators on som e virtual(non-) conform ing finite-dim ensionalsubspaces,a stabilization form ulation is pre- sented for the Stokes problem by em ploying nonconform ing elem ents.This form ulation is uni- form ly coercive and notsubject to the Babus ka-Brezzicondition,and the resulted linear algebraic system is positive definitew ith the spectralcondition num berO(h- 2 ). Quasi-optim alerrorbounds are obtained,which is consistentwith the interpola- tion properties ofthe finite elem entsused.展开更多
In this paper,the necessary and sufficient conditions for generalone-step m ethods to be exponentially fitted atq0∈C aregiven.A classofm ultiderivative hybrid one-step m ethods of order at leasts+ 1 is constructed ...In this paper,the necessary and sufficient conditions for generalone-step m ethods to be exponentially fitted atq0∈C aregiven.A classofm ultiderivative hybrid one-step m ethods of order at leasts+ 1 is constructed w ith s+ 1 param eters,w here sis the order of derivative.The necessary and sufficient conditions for these m ethods to be A-stable and exponentially fitted is proved.Furtherm ore,a class ofA-stable 2 param eters hybrid one-step m ethods oforderatleast 8 are constructed,w hich use 4th order derivative.These m ethods are exponentially fitted atq0 if and only if its fitted function f(q) satisfies f(q0)= 0.Finally,an A-stable exponentially fitted m ethod oforder 8 is obtained.展开更多
Totally, 3 701 prim iparousw om en in Shanghaiw ere follow ed up for 15 m onths after delivery to assess their initialand subsequent changes in choice of contraceptive m ethods. Results show ed that 15 m onths after...Totally, 3 701 prim iparousw om en in Shanghaiw ere follow ed up for 15 m onths after delivery to assess their initialand subsequent changes in choice of contraceptive m ethods. Results show ed that 15 m onths after delivery, 95.46of w om en had al- ready used a contraceptive m ethod. The leading firstchoice of contraceptive m ethods am ong urban w om en w asthe condom (50.72) or IUD(29.09), w hile the leading firstchoice am ong ruralw om en w asIUD(56.65) or the condom (30.60). Within 15 m onths after delivery, w om en w hose first choice had been the condom tended to sw itch usually to an IUD. Butfew er w om en w hosefirstm ethod w asan IUD sw itched to other m ethods. Atthe 15th m onth follow -up, 94.54of w om en w ere all using a m ethod, w ith 60.76of urban w om en and 71.07of rural w om en using IUDs. Multinom inal logistic regression analysis suggests that w om en's characteristics influ- ence the choice of m ethods. Urban, w ell-educated w om en w ere m ore likely to choose condom and rhythm , and lesslikely to chooseOC. Older w om en tended to use condom and rhythm m ore often than younger w om en. Breastfeeding w om en w ere lesslikely to use OC. Wom en w ho received recom m endations regarding postpartum contraception from fam ily planning w orkers w ere m ore likely to use IUD. It w as concluded that fam ily planning w orkers should increase w om en's aw areness of the advantages and disadvantagesof differentm ethods, dispelmythsand rum orsaboutsom em ethodsand improve w om en'sknow ledge of inform ed choice.展开更多
This paper presents a new trust region dogleg method for unconstrained optimization. The method can deal with the case when the Hessian B of quadratic models is indefinite. It is proved that the method is globally...This paper presents a new trust region dogleg method for unconstrained optimization. The method can deal with the case when the Hessian B of quadratic models is indefinite. It is proved that the method is globally convergent and has a quadratic convergence rate if B\+\{(k)\} = Δ\+2 f(x\+\{(k)\}). Under certain conditions, the solution obtained by the method is even a second order stationary point. Numerical results also declare effectiveness of the method.展开更多
The characteristics of broken surfaces were r esearched by a scanning electron microscope (SEM) and a reflection microscope, a nd the fractal dimensions of broken surfaces were measured by the Slit Island me thod. Th...The characteristics of broken surfaces were r esearched by a scanning electron microscope (SEM) and a reflection microscope, a nd the fractal dimensions of broken surfaces were measured by the Slit Island me thod. The experimental results indicate that the broken surface of aluminum elec tric porcelain is a fractal body in statistics, and the fractal dimensions of br oken surfaces are different with the different amplification multiple value.In a ll of measured fractal dimensions,both of values measured in 100× under reflect ion microscope and in 500× under SEM are maximum, whereas the values measur ed in 63× under reflection microscope and in 2000× under SEM are obviously min imum. The fractal dimensions of broken surfaces are also affected by the degrees of gray comparison and the kinds of measuring methods. The relationships betwee n the fractal dimensions of broken surfaces and porcelain bend strengths are tha t they are in positive correlation on the low multiples and in negative correlat ion on the high multiples.展开更多
A class of constrained semi\|infinite minimax problem is transformed into a simple constrained problem, by means of discretization decomposition and maximum entropy method, making use of surrogate constraint. The pa...A class of constrained semi\|infinite minimax problem is transformed into a simple constrained problem, by means of discretization decomposition and maximum entropy method, making use of surrogate constraint. The paper deals with the convergence of this asymptotic approach method.展开更多
Using the method of undetermined function, a set of 12 parameter rectangular plate element with double set parameter and geometry symmetry is constructed. Their consistency error are O(h\+2) , one order higher than...Using the method of undetermined function, a set of 12 parameter rectangular plate element with double set parameter and geometry symmetry is constructed. Their consistency error are O(h\+2) , one order higher than the usual 12 parameter rectangular plate elements.展开更多
This paper studies the finite element method for some nonlinear hyperbolic partial differential equations with memory and dampling terms.A Crank\|Nicolson approximation for this kind of equations is presented.By using...This paper studies the finite element method for some nonlinear hyperbolic partial differential equations with memory and dampling terms.A Crank\|Nicolson approximation for this kind of equations is presented.By using the elliptic Ritz\|Volterra projection,the analysis of the error estimates for the finite element numerical solutions and the optimal H \+1\|norm error estimate are demonstrated.展开更多
Based on the modified Jocobi elliptic function expansion method and the modified extended tanh function method,a new algebraic method is presented to obtain mu ltiple travelling wave solutions for nonlinear wave equ...Based on the modified Jocobi elliptic function expansion method and the modified extended tanh function method,a new algebraic method is presented to obtain mu ltiple travelling wave solutions for nonlinear wave equations.By using the metho d,Ito's 5th order and 7th order mKdV equations are studied in detail and more new exact Jocobi elliptic function periodic solutions are found.With modulus m→1 or m→0,these solutions degenerate into corresponding solitary wave s olutions,shock wave solutions and trigonometric function solutions.展开更多
In this paper,a new numerical method,the coupling method of spherical harmonic function spectral and finite elements,for a unsteady transport equation is discussed,and the error analysis of this scheme is proved.
文摘Follow ing the fram ew ork of the finite elem ent m ethods based on Riesz-representing operators developed by Duan Huoyuan in 1997,through discreteRieszrepresenting-operators on som e virtual(non-) conform ing finite-dim ensionalsubspaces,a stabilization form ulation is pre- sented for the Stokes problem by em ploying nonconform ing elem ents.This form ulation is uni- form ly coercive and notsubject to the Babus ka-Brezzicondition,and the resulted linear algebraic system is positive definitew ith the spectralcondition num berO(h- 2 ). Quasi-optim alerrorbounds are obtained,which is consistentwith the interpola- tion properties ofthe finite elem entsused.
文摘In this paper,the necessary and sufficient conditions for generalone-step m ethods to be exponentially fitted atq0∈C aregiven.A classofm ultiderivative hybrid one-step m ethods of order at leasts+ 1 is constructed w ith s+ 1 param eters,w here sis the order of derivative.The necessary and sufficient conditions for these m ethods to be A-stable and exponentially fitted is proved.Furtherm ore,a class ofA-stable 2 param eters hybrid one-step m ethods oforderatleast 8 are constructed,w hich use 4th order derivative.These m ethods are exponentially fitted atq0 if and only if its fitted function f(q) satisfies f(q0)= 0.Finally,an A-stable exponentially fitted m ethod oforder 8 is obtained.
文摘Totally, 3 701 prim iparousw om en in Shanghaiw ere follow ed up for 15 m onths after delivery to assess their initialand subsequent changes in choice of contraceptive m ethods. Results show ed that 15 m onths after delivery, 95.46of w om en had al- ready used a contraceptive m ethod. The leading firstchoice of contraceptive m ethods am ong urban w om en w asthe condom (50.72) or IUD(29.09), w hile the leading firstchoice am ong ruralw om en w asIUD(56.65) or the condom (30.60). Within 15 m onths after delivery, w om en w hose first choice had been the condom tended to sw itch usually to an IUD. Butfew er w om en w hosefirstm ethod w asan IUD sw itched to other m ethods. Atthe 15th m onth follow -up, 94.54of w om en w ere all using a m ethod, w ith 60.76of urban w om en and 71.07of rural w om en using IUDs. Multinom inal logistic regression analysis suggests that w om en's characteristics influ- ence the choice of m ethods. Urban, w ell-educated w om en w ere m ore likely to choose condom and rhythm , and lesslikely to chooseOC. Older w om en tended to use condom and rhythm m ore often than younger w om en. Breastfeeding w om en w ere lesslikely to use OC. Wom en w ho received recom m endations regarding postpartum contraception from fam ily planning w orkers w ere m ore likely to use IUD. It w as concluded that fam ily planning w orkers should increase w om en's aw areness of the advantages and disadvantagesof differentm ethods, dispelmythsand rum orsaboutsom em ethodsand improve w om en'sknow ledge of inform ed choice.
文摘This paper presents a new trust region dogleg method for unconstrained optimization. The method can deal with the case when the Hessian B of quadratic models is indefinite. It is proved that the method is globally convergent and has a quadratic convergence rate if B\+\{(k)\} = Δ\+2 f(x\+\{(k)\}). Under certain conditions, the solution obtained by the method is even a second order stationary point. Numerical results also declare effectiveness of the method.
基金Funded by the Natural Science Foundation of Shaanxi Province(No.2003E225)
文摘The characteristics of broken surfaces were r esearched by a scanning electron microscope (SEM) and a reflection microscope, a nd the fractal dimensions of broken surfaces were measured by the Slit Island me thod. The experimental results indicate that the broken surface of aluminum elec tric porcelain is a fractal body in statistics, and the fractal dimensions of br oken surfaces are different with the different amplification multiple value.In a ll of measured fractal dimensions,both of values measured in 100× under reflect ion microscope and in 500× under SEM are maximum, whereas the values measur ed in 63× under reflection microscope and in 2000× under SEM are obviously min imum. The fractal dimensions of broken surfaces are also affected by the degrees of gray comparison and the kinds of measuring methods. The relationships betwee n the fractal dimensions of broken surfaces and porcelain bend strengths are tha t they are in positive correlation on the low multiples and in negative correlat ion on the high multiples.
文摘A class of constrained semi\|infinite minimax problem is transformed into a simple constrained problem, by means of discretization decomposition and maximum entropy method, making use of surrogate constraint. The paper deals with the convergence of this asymptotic approach method.
文摘Using the method of undetermined function, a set of 12 parameter rectangular plate element with double set parameter and geometry symmetry is constructed. Their consistency error are O(h\+2) , one order higher than the usual 12 parameter rectangular plate elements.
文摘This paper studies the finite element method for some nonlinear hyperbolic partial differential equations with memory and dampling terms.A Crank\|Nicolson approximation for this kind of equations is presented.By using the elliptic Ritz\|Volterra projection,the analysis of the error estimates for the finite element numerical solutions and the optimal H \+1\|norm error estimate are demonstrated.
基金Supported by the Natural Science Foundation of Zhejiang Province (1 0 2 0 37)
文摘Based on the modified Jocobi elliptic function expansion method and the modified extended tanh function method,a new algebraic method is presented to obtain mu ltiple travelling wave solutions for nonlinear wave equations.By using the metho d,Ito's 5th order and 7th order mKdV equations are studied in detail and more new exact Jocobi elliptic function periodic solutions are found.With modulus m→1 or m→0,these solutions degenerate into corresponding solitary wave s olutions,shock wave solutions and trigonometric function solutions.
文摘In this paper,a new numerical method,the coupling method of spherical harmonic function spectral and finite elements,for a unsteady transport equation is discussed,and the error analysis of this scheme is proved.
