~(146)Tb的能级结构研究

利用能量为161—175MeV的~(32)S束流,通过反应~(118)Sn(~(32)S,1p3n)~(146)Tb研究了双奇核~(146)Tb的高自旋态能级结构。实验进行了γ射线的激发函数、γ射线的各向异性度、X-γ和γ-γ-t符合测量。基于这些测量结果,建立了激发能达8390kev的~(146)Tb核的能级纲图,其中包括新发现的41条γ射线和新建立的27个能级,并指定了~(146)Tb新发现能级的自旋值。用一个h_(11/2)价质子和一个h_(11/2)~(-1)价中子空穴耦合、πh_(11/2)υh_(11/2)~(-1)与~(146)Gd核实激发态的耦合对~(146)Tb的能级结构进行了定性地讨论。

Properties of the beta-delayed proton decay of Ho-146

The proton-rich isotope Ho-148 was produced via the fusion-evaporation reaction Mo-92 (Ni-58, 3p1n). The beta-delayed proton decay of Ho-146 was studied by proton-gamma coincidence measurements using a He-jet tape transport system. The gamma-transitions in Tb-145 following the proton emissions were observed, and the beta-delayed proton branching ratios to the final states in the grand-daughter nucleus Tb-145 were determined. According to the relative branching ratios, the ground-state spin of Ho-146 has been proposed and the possible configuration discussed.

Analysis of Wave-Induced Effective Stresses of Seabed

波浪作用下海床的稳定性分析是海洋工程地质评价的重要内容。海床的稳定性可通过计算分析其随时间变化的有效应力场来评估。建议了一个周期载荷作用下土体的本构模型,并用于计算波浪作用下海床的应力与变形。采用Biot固结理论和有限单元法,分析了海床的动态应力场与孔隙水压力场。波浪作用下两种渗透系数时有效应力的动态变化过程结果对比,反映了渗透消散作用对海床有效应力变化的影响。

Simulations of oil spread on a water surface

Numerical simulation of an oil slick spreading on still and wavy surfaces is described in this paper. The so-called sigma transformation is used to transform the time-varying physical domain into a fixed calculation domain for the water wave motions and, at the same time, the continuity equation is changed into an advection equation of wave elevation. This evolution equation is discretized by the forward time and central space scheme, and the momentum equations by the projection method. A damping zone is set up in front of the outlet boundary coupled with a Sommerfeld-Orlanski condition at that boundary to minimize the wave reflection. The equations for the oil slick are depth-averaged and coupled with the water motions when solving numerically. As examples, sinusoidal and solitary water waves, the oil spread on a smooth plane and on still and wavy water surfaces are calculated to examine the accuracy of simulating water waves by Navier-Stokes equations, the effect of damping zone on wave reflection and the precise structures of oil spread on waves.

固体破坏的损伤演化诱致突变现象

介绍了基于细观非线性动力学模型的研究所取得的进展。发现系统显示一种共性特征，称为演化诱致突变，即演化模式从整体稳定向灾变性模式转变，宏观破坏的样本个性行为，以及宏观性质对细观无序性的敏感性。

天然淡水冰单轴压缩强度及其温度和应变率效应

本文报道了在不同温度和不同应变率下天然淡水冰单轴压缩强度的实验结果。指出S—l型柱状晶粒冰的压缩强度随着温度的降低而增加,极限压缩强度在应变率为10~(-4)S(-1)时有一个最大值。本实验的应变率范围是10~(-5)—10~0s~(-1)。10~(-1)—10~0s~(-1)的应变率范围是在冲击速度lm/s左右的实验条件下获得的,这个速度接近于浮冰与海上结构物相撞的情况。以本实验为基础,有希望发展对海冰的实验技术。

扩散型连续波HF化学激光器小信号增益的计算

应用层流边界层二维简化模型计算了扩散型连续波HF化学激光器的小信号增益。研究了气流速度、温度、组份对增益的影响,得到一些有用的结果。计算结果与二维Navier-Stokes方程组的计算结果相符,但计算方法较简单。