强激光辐照下预载柱壳热屈曲失效的数值分析

 采用有限元方法（ANSYS7.0）和简易的热力耦合本构关系,较系统地数值研究了预载柱壳受激光辐照时的热力响应和热屈曲失效行为,分析了几种壳体在不同预载条件下（轴压或内压）的屈曲模态和屈曲特征值,给出了屈曲模态和热屈曲失效与激光强度、辐照时间、预载条件和壳体几何尺度及形状间的定量或定性关系。计算结果表明：（1）屈曲失效行为主要集中在激光辐照区内且以径向屈曲为主。（2）在一定范围内,屈曲特征值与光斑中心点温度近似有线性关系。（3）激光辐照区内高温引起的材料软化和预载径向变形的耦合作用是柱壳发生热屈曲失效的根本原因,有效提高结构刚度,可使屈曲特征值提高。（4）壳体形状的改变对内压柱壳有更为明显的影响,其中圆柱形壳体屈曲特征值最大,因此具有较高的安全性。     

两组份复合材料光学非线性性质的临界行为

对两组份非线性复合材料的光学非线性性质的临界行为进行了研究。考虑第一组份为非线性材料,其电流、电压间服从I=g1V x1V^β关系;而第二组份为线性材料,电流、电压间满足I—g2V,其中g1,x1是第一组份的线性电导和光学非线性极化率,g2是第二组份的线性电导,β是第一组份材料的光学非线性指数。分别采用了有效介质近似和相对电阻涨落的标度理论两种方法计算了系统有效响应的临界指数随光学非线性指数及维数的变化规律。用不同的方法得到系统的有效线性电导g和有效光学非线性极化率xe(β)的临界指数M(β)和N(β)的结论也不同。有效介质近似得到M(β)=1和N(β)=(β 1)/2,即M(β)与β和d都无关,而N(β)只与有β关而与d无关;而相对电阻涨落标度理论方法得到的M(β)和N(β)与β和d都有关。     

Asymptotical behavior of ground state solutions for critical quasilinear Schrödinger equation

This paper is concerned with the existence and asymptotical behavior of positive ground state solutions for a class of critical quasilinear Schrodinger equation.By using a change of variables and variational argument,we prove the existence of positive ground state solution and discuss their asymptotical behavior。     

灰色关联度法在工业企业去库存中的应用

工业企业为了赢得市场竞争地位,必须向市场提供质量好、人民满意的产品,这就需要处理企业库存中市场过剩的、不对路的产品,也就是开展“去库存”工作。论文通过设置与库存相关的指标,计算临界值来判断工业企业产品是否“过剩”,再通过灰色关联度法进行优化排序,确定整个工业行业“去库存”的主要抓手。研究结果表明,工业企业去库存的主要抓手有三个:一要加速库存商品资金周转;二要提高产品销售率;三要降低库存商品占流动资产的比例。论文将研究结论用于徐工集团工程机械股份有限公司,得到有效的验证。     

Nodal solutions for fourth order elliptic equations with critical exponent on compact manifolds

Using a variational method, we prove the existence of nodal solutions to prescribed scalar Q- curvature type equations on compact Riemannian manifolds with boundary. These equations are fourth-order elliptic equations with critical Sobolev growth.     

Homoclinic solutions for fourth order differential equations with superlinear nonlinearities

In this paper we investigate the existence of homoclinic solutions for a class of fourth order differential equations with superlinear nonlinearities. Under some superlinear conditions weaker than the well-known (AR) condition, by using the variant fountain theorem, we establish one new criterion to guarantee the existence of infinitely many homoclinic solutions.     

Magneto‐transport properties of polycrystalline YBa2(Cu1‐xMx)3O7‐δ (M = B and Mn)

The magnetic and transport properties of polycrystalline YBa₂ (Cu_1‐xM_x)₃ O_7‐δ (M = B and Mn) superconductor was investigated. Samples of YBa₂(Cu_1‐xB_x)₃O_7‐δ doped with several concentrations of boron B(x = 0.05 and 0.1) were investigated using magnetization measurements. A YBa₂(Cu_1‐xMn_x)₃O_7‐δ sample doped with Mn with concentration of x = 0.02 was investigated using current‐voltage (I‐V) measurements. Our results on the YBa₂(Cu_1‐xB_x)₃O_7‐δ samples reveal a considerable increase in the hysterisis width of the magnetization, M versus the applied magnetic field H with increasing boron concentration. The lower critical field was also found to be enhanced by boron doping. The critical current density, J_c was found to be significantly enhanced in the Mn‐doped sample. The enhancement of J_c was found to be more significant at the lower temperatures for all applied magnetic fields used (0 Oe, 300 Oe, and 500 Oe). Thus, chemical doping is suggested to enhance the vortex pinning forces in the YBCO samples. From the resistivity (R‐T) measurements, chemical doping of the samples was found to have no significant effect on the critical temperature, T_c. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Deformation of thin straight pipes under concentrated forces or prescribed edge displacements

The purpose of this paper is to present an efficient analytic method for obtaining the deformation of thin straight pipes, subjected to prescribed edge displacements or concentrated loads.The approach uses the mixed formulation where unknown functions are combined with trigonometric terms. A variational procedure is used to obtain the system of ordinary differential equations. For the applied load a Fourier approach is used to represent the load as an analytical function. For the prescribed displacement, three solutions for the ovalization are evaluated and a method based on energy contribution of each term is used to obtain their superposition.In contrast to finite element method the proposed method is efficient and can be applied to other boundary condition problems leading to continuous displacement and stress fields with a low number of unknowns. Comparisons with experimental and finite element procedures show good agreement that enhances the merits of the analytical solutions proposed.The value of this method is based on solving the differential equations rather than using commercial codes. So far, the solution of prescribed edge displacements has been limited to one term. This paper discusses how to add further terms using the mixed formulation, thus, presenting a novel procedure.     

Response of moving load due to irregularity in slightly compressible,finitely deformed elastic media

The present paper has been framed to study the stresses produced on the rough surface of a slightly compressible, finitely deformed half space due to a normal moving load. The surface of the medium is irregular with parabolic type of irregularity. The perturbation method is applied to find the displacement field. The normal and shear stresses have been obtained in closed form and discussed numerically by means of figures. It has been observed that the shear stress developed at different depths below the surface depends on the irregularity depth, frictional coefficient and irregularity factor of the rough surface of the medium. Also, surface plots have been drawn to analyze the combined variation of non-dimensional stresses and irregularity factor against depth.