不同电荷态的129Xeq+激发Au的X射线发射研究

报道了在兰州重离子加速器国家实验室测量动能为2.4 MeV的Xe^q+(q=10, 15, 20, 26)轰击Au表面辐射的X射线的实验数据. 实验结果表明, Au的M-X射线有不同程度的能移, 这是由于入射过程引起了靶原子内壳层的多电离, 多电离的程度主要取决于离子的外壳层电子分布. 计算了X射线产额, 并与BEA理论计算值进行了比较, 讨论了电荷态对X射线产额的影响.     

Structural Interpretation of Eyring Activation Parameters for Tensile Yielding Behavior of Isotactic Polypropylene Solids

The temperature and strain rate dependence of the stress-strain curves of isotactic polypropylene were analyzed on the basis of Eyring kinetic theory. The molecular and structural basis underlying the parameters, such as activation volume and activation energy, used by the Eyring analysis were studied using the lamellar cluster theory, where a stacked lamella acts as a basic structural unit under yielding and necking deformation. It was suggested that, at lower temperatures, the activation volume corresponds to chain slippage within crystalline lamellae in the lamellar clusters whereas at higher temperature the increase in activation volume results in intralamellar slip corresponding to the α₂ relaxation.     

Contribution of point defects to the temperature anomaly of the yield stress in single crystals of the Ni<Subscript>3</Subscript>Ge alloy

The temperature dependence of the yield stress τ_* Ni ₃ Ge single crystals is studied. The temperature dependence τ_*(T) in the high-temperature region (above 420 K) is found to be conditioned by thermally activated accumulation of the density of non-screw components of superdislocations. Interaction of point defects with edge dislocations and its effect on the temperature anomaly of the yield stress in Ni ₃ Ge single crystals are analyzed. The calculated results are found to agree with experimental data. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 4, pp. 154–161, July–August, 2007.     

镁合金屈服与强度的实验研究

报导镁合金ＭＢ８薄壁圆管试件在比例加载时Ｐ－ｐ复杂应力状态下的实验结果，主要研究了：（１）初始屈服曲面；（２）强度极限曲面；（３）初始屈服曲面与强度极限曲面的关系。     

Shock-induced chemical processes and ‘molecular rocket reaction’ in metallocenes and their cyclodextrin inclusion compounds

Shock-induced yield enhancement has been observed in implantation of recoil atoms into metallocene and its-cyclodextrin (CD) inclusion compounds, as in the case of metal-diketonate compounds previously studied. The enhancement, however, occurs at much lower energy compared with that in metal-diketonates. In acetylruthenocene and benzoylruthenocene--CD inclusion compounds, various aspects of molecular rocket reaction have been discussed.This article was processed by the author using Springer-Verlag T_EX PJour2g macro package version 1.     

Two-dimensional planar flow of a viscoelastic plastic medium

The present study is concerned with finite element simulation of the planar entry flow of a viscoelastic plastic medium exhibiting yield stress. The numerical scheme is based on the Galerkin formulation. Flow experiments are carried out on a carbon black filled rubber compound. Steady-state pressure drops are measured on two sets of contraction or expansion dies having different lengths and a constant contraction or expansion ratio of 4:1 with entrance angles of 90, 45 and 15 degrees. The predicted and measured pressure drops are compared. The predicted results indicate that expansion flow has always a higher pressure drop than contraction flow. This prediction is in agreement with experimental data only at low flow rates, but not at high flow rates. The latter disagreement is possibly an indication that the assumption of fully-developed flow in the upstream and downstream regions is not realistic at high flow rates, even for the large length-to-thickness ratio channels employed. The evolution of the velocity, shear stress, and normal stress fields in the contraction or expansion flow and the location of pseudo-yield surfaces are also calculated.     

巷道围岩塑性状态判定分析方法

本文依照莫尔-库仑屈服条件和非关联流动准则, 从地应力场及地下巷道开挖工程特点出发, 提出对围岩塑性屈服状态进行判定的方法。对无支护巷道和水泥锚杆支护巷道围岩进行有限元分析表明, 巷道开挖以后及时支设锚杆, 对出现塑性屈服的围岩起到了等效提高其刚度和强度的作用, 从而增加了围岩稳定性。与现场实测结果对比说明, 非关联流动准则比关联流动准则更符合实际。     

简支圆板在复杂荷载作用下的塑性极限荷载统一解析解

本文采用双剪统一屈服准则对受线性荷载和边缘弯矩联合作用下的简支圆板进行了塑性极限分析，考虑了联合作用的两种形式，分别给出了统一的解析解。得到了极限荷载随不同屈服准则的变化曲线。对于不同的材料，本文均能给出相应的极限荷载。已有的Tresca准则、Von Mises准则、双剪应力准则的解答是文中解答的特例或逼近。本文得到的一系列有规则变化的解析解，可以适用于各种拉压强度相同材料的简支圆板的塑性极限荷载求解。文中统一解大于Tresca单剪理论解，它可以更好地发挥材料的强度潜力，工程应用可以取得明显的经济效益。     

Rheological studies of coal-oil mixtures

Summary Samples of stable coal-oil mixtures were prepared with coal concentrations ranging from 30–50% by weight. Extensive rheological data were obtained using capillary and cone-plate viscometers for samples of coal-oil mixtures and fuel-oil which served as a reference fluid. Viscosity measurements show coal-oil mixtures to be shear-thinning suspensions, i.e., the viscosity decreases moderately with increasing shear rates. In the concentration range of 30–40% coal, the coal-oil mixture shows a predominantly Newtonian behavior. For mixtures with coal concentrations higher than 40%, a yield point was observed. The study of these samples with the rotating-rod viscometer indicated a migration of coal particles away from the rotating rod with no noticeable rod climbing, thus no evidence of normal stress effects. The rheological data can be represented by any of the three two-parameter models: Power Law, Bingham Plastic, or Casson, with the last two models being more realistic and consistent with the observations.With 9 figures     

半无限空间重力隧洞洞室临塑状态分析

利用Mindlin给出的、半无限空间重力隧洞初始应力场下的完整应力解分析了洞室周边的应力分布规律,用数值方法计算出了最大压应力的位置;结合Mohr-Coulomb屈服条件,研究了洞室周边出现塑性点时洞室直径、围岩粘聚力、内摩擦角与相对埋深的关系,以便工程设计应用。