折板及多面板非线性弯曲分析的样条核质点法

提出了一种研究折板及多面板类结构非线性弯曲行为的样条核质点法.方法包括以下步骤:(1)将折板及多面板结构模拟成不同平面上平板的集合体;(2)基于冯.卡门的大挠度理论,使用一阶剪切变形理论和样条核质点法先分析各平板的几何非线性行为;(3)将经过修正的各板的非线性刚度矩阵叠加得到整个折板结构的非线性刚度矩阵;(4)研究整个结构的几何非线性行为.由于摆脱了网格的束缚,本文方法可以避免网格扭曲引起的网格重构问题.文末通过几个算例将本文方法解与使用壳单元的ANSYS有限元解或已有文献解进行对比,验证了本文方法的收敛性和准确性.     

On two‐dimensional unsteady incompressible fluid flow in an infinite strip

In this paper, we study two‐dimensional incompressible fluid flow in an infinite strip. The stream function form of Navier–Stokes equation is considered, which keeps the physical boundary condition and avoids some difficulties in numerical simulations. The existence and uniqueness of global solution are proved. Some results on the regularity of solution are obtained. Copyright © 2000 John Wiley & Sons, Ltd.     

(NdDy)(FeAl)B速凝带的热处理对磁体的性能和微结构的影响

采用旋淬非晶带作为液相,而将主相母合金速凝带进行热处理后,不仅使烧结NdFeB磁体的微观形貌和磁性能显著改善,还调整了速凝带主相和富钕相的计量成分比。结果表明:双合金法烧结工艺要求比普通工艺更高的烧结温度和较短的烧结时间。速凝带经热处理后,磁体的内禀矫顽力jHc和磁能积(BH)max分别由718和285kJ·m-3提高到87和360kJ·m-3。将改进工艺后得到的速凝带进行热处理后,磁能积(BH)max达到392kJ·m-3。     

MODEL SHIFT AND STRANGE ATTRACTOR ON MOBIUS STRIP

A new model shift mapping was given in bilateral symbol space. It istopologically conjugate with the traditional shift mapping. Similar to Smale Horseshoe, amodel was constructed correspondent to the model shift mapping, i. e., a class of mappingon Mobius strip was given. Its attractors' structure and dynamical behaviour weredescribed.     

Linear and sub-linear growth and the CLT for hitting times of a random walk in random environment on a strip

The main goal of this work is to study the asymptotic behaviour of hitting times of a random walk (RW) in a quenched random environment (RE) on a strip. We introduce enlarged random environments in which the traditional hitting time can be presented as a sum of independent random variables whose distribution functions form a stationary random sequence. This allows us to obtain conditions (stated in terms of properties of random environments) for a linear growth of hitting times of relevant random walks. In some important cases (e.g. independent random environments) these conditions are also necessary for this type of behaviour. We also prove the quenched Central Limit Theorem (CLT) for hitting times in the general ergodic setting. A particular feature of these (ballistic) laws in random environment is that, whenever they hold under standard normalization, the convergence is a convergence with a speed. The latter is due to certain properties of moments of hitting times which are also studied in this paper. The asymptotic properties of the position of the walk are stated but are not proved in this work since this has been done in Goldhseid (Probab. Theory Relat. Fields 139(1):41–64, 2007).      

非关联流动的安定性理论及在土力学中的应用

将Melan静力型安定定理加以推广，使其适用于非关联流动法则下的土工结构的安定性分析．应用Palmer的方法构造塑性势面，根据其性质，证明了静力型安定定理在非关联流动法则下同样成立．在非关联的Mok—Coulomb准则下，求解浅黏土层地基极限载荷，得到了比较合理的解答．最后，计算了非关联流动法则下的条形基础地基的安定裁荷．     

Existence of positive solutions of some nonlinear elliptic problems in unbounded domains

In this paper, we study the existence of positive solutions of some nonlinear elliptic problems in unbounded domains. The existence is affected by the properties of the geometry and the topology of the domain.     

双调和泊松方程的新解法

本文用Fourier变换法求解了区域为带形区域和上半平面的双调和Po isson方程的边值问题。     

Trace continuation in infinite-order Sobolev space on a multidimensional strip region

In the Sobolev infinite-order space on a multidimensional strip region we obtain conditions for the existence of a function that, together with all its derivatives, assumes prescribed values on the boundary. An example shows that the sufficient conditions for the trace continuation obtained in the present paper have a significant advantage over those obtained earlier. Furthermore, for spaces of some special type our conditions for trace continuation are both sufficient and necessary. Translated fromMatematicheskie Zametki, Vol. 62, No 6, pp. 820–830, December, 1997 Translated by M. A. Shishkova     

薄壁铸造和退火工艺对LPCNi3.55Co0.75Mn0.4Al0.3贮氢合金电化学性能的影响

研究了不同铸锭厚度(1～10mm)对薄壁铸造的铸态和退火态LPCNi3．55Co0.75Mn0.4Al0.3贮氢合金电化学性能的影响。结果发现：铸态LPCNi3．55Co0.75Mn0.4Al0.3合金的0．2C放电容量随着合金锭厚度的增加有增大的趋势。10mm厚铸态合金的活化性能优于其它厚度的合金，且在1C的放电容量和循环稳定性比在其它厚度的高。主要原因应归结为该厚度合金具有更大的晶胞体积和更小的晶格应力。退火态3mm LPCNi3．55Co0.75Mn0.4Al0.3合金的综合电化学性能比铸态更优异，6mm合金的循环稳定性和3～6mm合金的活化性能得到改善。主要原因应归结为晶格应力的极大释放以及Mn等元素偏析的改善。