边值问题中与分离变量法等价的级数解法

用带奇性分离的Ｆｏｕｒｉｅｒ级数解平面边值问题，改进了不能满足全部边界条件的一般级数解法，得到收敛较好的解析算法。文中证明了级数解法与分离变量法的等价性，由此将分离变量解所得的非线性特征方程转化为多项式方程，为近似算法与渐近分析提供了依据。     

The distribution of zeroes of solutions of neutral equations

1.IntroductionThestudyofoscillator}'behaviorofneutraldifferentialequationsisarelativealnewfieldandisveryinterestinginapplications.Inrecentyears.theoscillatorytheoryfortheseequationshasbeenextensivelydeveloped.WerefertotherecentbookbyGyoriandLadaSI'I,Baino…     

A SPECIAL METHOD OF FOURIER SERIES WHICH IS EQUAL TO THE METHOD OF SEPARATION OF VARIABLES ON BOUNDARY VALUE PROBLEM

By the separation of singularity, a special Fourier series solution of the boundary valueproblem for plane is obtained, which can satisfy all boundary conditions and converges rapidly. It isproved that the solution is equal to the result of separation of variables. As a result, the non-linearcharacteristic equations resulting from the method of separation of variables are transformed into poly-nomial equations that can provide a foundation for approximate computation and asymptotic analysis.     

Separation of variables in one problem of motion of the generalized Kowalevski top

In the problem of motion of the Kowalevski top in a double force field the new case of reduction to a Hamiltonian system with two degrees of freedom was pointed out by Kharlamov [Kharlamov, M.P., 2004. Mekh. Tverd. Tela 34, 47–58]. We show that the equations of motion in this case can be separated by the appropriate change of variables, the new variables U,V being hyperelliptic functions of time. The natural phase variables (components of the angular velocity and the direction vectors of the forces with respect to the movable basis) are expressed via U,V explicitly in elementary algebraic functions.     

A SYMBOLIC COMPUTATION METHOD TO DECIDE THE COMPLETENESS OF THE SOLUTIONS TO THE SYSTEM OF LINEAR PARTIAL DIFFERENTIAL EQUATIONS

ＩｎｔｒｏｄｕｃｔｉｏｎＣｏｎｓｉｄｅｒｔｈｅｓｙｓｔｅｍｏｆｐａｒｔｉａｌｄｉｆｆｅｒｅｎｔｉａｌａｌｇｅｂｒａｉｃｅｑｕａｔｉｏｎｓ (ＰＤＡＥｓ) :Σ :　Ｐｉ(ｙ1,ｙ2 ,… ,ｙｎ) =0　　 (ｉ =1,2 ,… ,ｒ) ,ｗｈｅｒｅｔｈｅｃｏｅｆｆｉｃｉｅｎｔｓａｒｅｉｎｔｈｅｄｉｆｆｅｒｅｎｔｉａｌｆｉｅｌｄＫｗｉｔｈｃｈａｒａｃｔｅｒｉｓｔｉｃｚｅｒｏ .ＴｈｅｉｍｐｏｒｔａｎｔｑｕｅｓｔｉｏｎｉｓｈｏｗｔｏｓｏｌｖｅｔｈｉｓＰＤＡＥｓｉｎｔｈｅｔｈｅｏｒｙｏｆｐａｒｔｉａｌｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａ…     

Partially invariant solutions for a submodel of radial motions of a gas

All partially invariant solutions in terms of the group of extensions for a model of radial motions of an ideal gas are found. The solutions are obtained by the method of separation of variables in an equation containing functions of one variable but different functions of different independent variables. The solutions predict different continuous unsteady convergence or expansion of the gas under the action of a piston with a point sink or source. If the sink or source affects all particles simultaneously, a collapse or an explosion occurs. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 5, pp. 26–34, September–October, 2007.     

平面粘弹性问题的辛求解方法

将弹性力学辛对偶求解方法与Laplace变换相结合,提出了一个求解粘弹性平面问题的新方法。首先利用Laplace变换,将粘弹性平面问题转化为一个准弹性问题,在辛弹性力学的框架下,利用分离变量和辛本征展开法对其进行求解,然后由逆变换得到原问题的解。为证明方法的有效性,求解分析了矩形域平面粘弹性圣维南问题,得到了令人满意的结果。     

Transient ultrasonic wave propagation in porous material of non-integer space dimension

Acoustic propagation in a self-similar porous medium having a rigid frame is studied. A fractional propagation equation in a porous material of non-integer dimension is established using the variational method (Stillinger–Palmer–Stavrinou formalism). The wave equation is solved analytically in the time domain using the Laplace transform method. The analytical solution of the propagation equation shows the existence of a supersonic wave whose front wave velocity depends on the non-integer dimension and the tortuosity of the self-similar porous material. Numerical simulations of the amplitude of the ultrasonic wave inside the material show the sensitivity of the main important parameters describing the propagation (non-integer dimension, tortuosity, viscous and thermal characteristic lengths). The non-integer dimension seems to be the only parameter which acts on both the amplitude and the velocity of the acoustic wave.     

Boundary integral equations of unique solutions in elasticity

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｂｏｕｎｄａｒｙｅｌｅｍｅｎｔｍｅｔｈｏｄ（ＢＥＭ）ｐｒｏｖｉｄｅｓａｎａｔｔｒａｃｔｉｖｅａｌｔｅｒｎａｔｉｖｅｆｏｒｔｈｅａｎａｌｙｓｉｓｏｆｅｎｇｉｎｅｅｒｉｎｇｐｒｏｂｌｅｍｓ．Ｉｔｓｍａｉｎａｄｖａｎｔａｇｅｓａｒｅｅｃｏｎｏｍｉｃａｌａｎｄｐａｒｔｉｃｕｌａｒｌｙｃｏｎｖｅｎｉｅｎｔｆｏｒｕｎｂｏｕｎｄｅｄｄｏｍａｉｎａｎｄｓｔｒｅｓｓｃｏｎｃｅｎｔｒａｔｉｏｎｐｒｏｂｌｅｍｓ．Ｔｈｅｂｏｕｎｄａｒｙｉｎｔｅｇｒａｌｅｑｕａｔｉｏｎ（ＢＩＥ）ｉｓｔｈｅ…     

New scalar-type equilibrium equations of the general space force system

ＩｎｔｒｏｄｕｃｔｉｏｎＬｉｋｅｔｈｅｃｏｐｌａｎａｒｆｏｒｃｅｓｙｓｔｅｍ ,ａｎｙｇｅｎｅｒａｌｓｐａｃｅｆｏｒｃｅｓｙｓｔｅｍＦｉ(ｉ =1 ,2 ,… ,ｎ)ｃａｎｂｅｒｅｄｕｃｅｄｔｏａｐｏｉｎｔＯａｎｄｒｅｐｌａｃｅｄｂｙａｐｒｉｎｃｉｐａｌｖｅｃｔｏｒＲａｎｄａｐｒｉｎｃｉｐａｌｍｏｍｅｎｔＬ0 .Ｓｏｔｈａｔｔｈｅｖｅｃｔｏｒ＿ｔｙｐｅｎｅｃｅｓｓａｒｙａｎｄｓｕｆｆｉｃｉｅｎｔｃｏｎｄｉｔｉｏｎｓｆｏｒｅｑｕｉｌｉｂｒｉｕｍｏｆｔｈｅｇｉｖｅｎｆｏｒｃｅｓｙｓｔｅｍａｒｅＲ =0 ,　Ｌ0 =0 . (1 )…     

Numerical solutions of singular integral equations for planar rectangular interfacial crack in three dimensional bimaterials

Stress intensity factors for a three dimensional rectangular interfacial crack were considered using the body force method. In the numerical calculations, unknown body force densities were approximated by the products of the fundamental densities and power series; here the fundamental densities are chosen to express singular stress fields due to an interface crack exactly. The calculation shows that the numerical results are satisfied. The stress intensity factors for a rectangular interface crack were indicated accurately with the varying aspect ratio, and bimaterial parameter.     

Explicit integration of one problem of motion of the generalized Kowalevski top

In the problem of motion of the Kowalevski top in a double force field the four-dimensional invariant submanifold of the phase space was pointed out by [Kharlamov, M.P., 2002. Mekh. Tverd. Tela 32, 33–38]. We show that the equations of motion on this manifold can be separated by the appropriate change of variables, the new variables s₁, s₂ being elliptic functions of time. The natural phase variables (components of the angular velocity and the direction vectors of the forces with respect to the movable basis) are expressed via s₁, s₂ explicitly in elementary algebraic functions.     

Existence of solutions for nonlinear impulsive Hammerstein integral equations in Banach spaces

ＩｎｔｒｏｄｕｃｔｉｏｎＩｔｉｓｗｅｌｌ＿ｋｎｏｗｎｔｈａｔｔｈｅｂａｓｉｃｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｎｏｎｌｉｎｅａｒｉｎｔｅｇｒａｌｅｑｕａｔｉｏｎｏｆＶｏｌｔｅｒｒａｔｙｐｅａｒｅｆｕｎｄａｍｅｎｔａｌｌｙｄｉｆｆｅｒｅｎｔｆｒｏｍｔｈａｔｏｆＨａｍｍｅｒｓｔｅｉｎｔｙｐｅ:Ｈａｍｍｅｒｓｔｅｉｎｉｎｔｅｇｒａｌｅｑｕａｔｉｏｎｈａｓａｆｉｘｅｄｕｐｐｅｒｌｉｍｉｔｏｆｉｎｔｅｇｒａｔｉｏｎ.Ｔｈｉｓｍｅａｎｓｔｈａｔａｓｏｌｕｔｉｏｎｍｕｓｔａｌｗａｙｓｂｅｄｅｆｉｎｅｄｏｖｅｒｅ…     

Characteristic equation solution strategy for deriving fundamental analytical solutions of 3D isotropic elasticity

A simple characteristic equation solution strategy for deriving the fundamental analytical solutions of 3D isotropic elasticity is proposed. By calculating the determinant of the differential operator matrix obtained from the governing equations of 3D elasticity, the characteristic equation which the characteristic general solution vectors must satisfy is established. Then, by substitution of the characteristic general solution vectors, which satisfy various reduced characteristic equations, into various reduced adjoint matrices of the differential operator matrix, the corresponding fundamental analytical solutions for isotropic 3D elasticity, including Boussinesq-Galerkin (B-G) solutions, modified Papkovich-Neuber solutions proposed by Min-zhong WANG (P-N-W), and quasi HU Hai-chang solutions, can be obtained. Furthermore, the independence characters of various fundamental solutions in polynomial form are also discussed in detail. These works provide a basis for constructing complete and independent analytical trial functions used in numerical methods.     

On certain global solutions of the cauchy problem for the (classical) coupled Klein-Gordon-Dirac equations in one and three space dimensions

If the data of the Dirac spinor field is suitably chosen, global solutions of the Klein-Gordon-Dirac Equations with Yukawa coupling are shown to exist for which the meson field remains free. In one space dimension, conditions are found under which the spinor field does not decay uniformly to zero, thus precluding a scattering theory in the H¹ (IR¹) norm. In three space dimensions, the existence of free Hⁿ(10³) (n≧0) asymptotic spinors is established and a scattering theory is developed.     

Exact solutions of the system of the equations of thermal motion of gas in the rarefied space

We study the model describing thermal motion of gas in the rarefied space. This model can be used, in particular, in the study of the state of the medium behind the front of shock wave after very strong blast, in the study of the processes taking place inside of tornado, in the study of the motion of the gas in outer space. For any given initial distribution of the pressure a specific selection of mass Lagrange variables leads to reduction of the system of differential equations describing this motion to the system, for which the number of independent variables is less on the unit. For the obtained system we found all nontrivial conservation laws of the first order. In addition to the classical conservation laws the system has other conservation laws, which generalizes the energy conservation law. We obtained the exact solutions of this system. These solutions describe a variety of different physical processes taking place in the rarefied medium. Using the symmetry properties of the system we got the generating formulas for the receipt of the new solutions using already found earlier solutions of the system.     

Refined differential equations of deflections in axial symmetrical bending problems of spherical shell and their singular perturbation solutions

This paper deals with the research of accuracy of differential equations of deflections.The basic idea is as follows.Firstly,considering the boundary effect the meridianmidsurface displacement u=0,thus we derive the deflection differential equations;secondly we accurately prove that by use of the deflection differential equations or theoriginal differential equations the same inner forces solutions are obtained;finally,weaccurately prove that considering the boundary effect the meridian surface displacementu=0 is an exact solution.In this paper we give the singular perturbation solution of thedeflection differential equations.Finally we check the equilibrium condition and prove theinner forces solved by perturbation method and the outer load are fully equilibrated.Itshows that perturbation solution is accurate.On the other hand,it shows again that thedeflection differential equation is an exact equation.The features of the new differential equations are as follows:1.The accuracies of the new differentia     

THE EXISTENCE OF PERIODIC SOLUTIONS FOR A CLASS OF FUNCTIONAL DIFFERENTIAL EQUATIONS AND THEIR APPLICATION

ＴＨＥＥＸＩＳＴＥＮＣＥＯＦＰＥＲＩＯＤＩＣＳＯＬＵＴＩＯＮＳＦＯＲＡＣＬＡＳＳＯＦＦＵＮＣＴＩＯＮＡＬＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮＳＡＮＤＴＨＥＩＲＡＰＰＬＩＣＡＴＩＯＮＺｈａｏＪｉｅ－ｍｉｎ（赵杰民）;ＨｕａｎｇＫｅ－ｌｅｉ（黄克累）...     

EXISTENCE OF POSITIVE RADIAL SOLUTIONS FOR SOME SEMILINEAR ELLIPTIC EQUATIONS IN ANNULUS

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｓｔｕｄｉｅｓｏｆｐｏｓｉｔｉｖｅｒａｄｉａｌｓｏｌｕｔｉｏｎｓｆｏｒｆｏｌｌｏｗｉｎｇｓｅｍｉｌｉｎｅａｒｅｌｌｉｐｔｉｃｂｏｕｎｄａｒｙｖａｌｕｅｐｒｏｂｌｅｍ(Ｐ)　Δｕ(Ｘ) +ｇ( ｜Ｘ｜)ｆ(ｕ(Ｘ) ) =0 ,　　Ｒ1<｜Ｘ｜<Ｒ2 ,ｕ(Ｘ) ｜｜Ｘ｜ =Ｒ1 =ｕ(Ｘ) ｜｜Ｘ｜ =Ｒ2 =0(ｗｈｅｒｅＲ1>0 ,Ｘ ∈Ｒｎ,ｎ ≥ 2 )ａｒｅｂｅｉｎｇｃｏｎｔｉｎｕｅｄｆｏｒｒｅｃｅｎｔ 2 0ｙｅａｒｓｗｉｔｈｏｕｔｉｎｔｅｒｒｕｐｔｉｏｎ[1- 11],ｂｅｃａｕｓｅｔｈｅｐｒｏｂｌｅｍ (Ｐ)ｈａｓｗｉ…     

基于通用炸药状态方程分析飞板运动规律的特征线法

从小扰动波(马赫波)的物理概念出发,导出了不依赖流体状态方程表达形式的平面二维超声速定常流的特征线方程;重新定义了以流体密度为单自变量的Prantl-Meyer函数,形成了求解平面二维超声速定常流的封闭方程组。还利用这种通用物态方程的特征线差分解法,针对滑移爆轰驱动飞板运动问题构建了爆轰产物流场内部和飞板边界特征线差分法格式。对TNT炸药和乳化炸药采用JWL状态方程和多方方程进行了对比计算。结果表明,炸药爆轰对飞板的驱动能力与状态方程表示的炸药的做功能力是一致的。