Numerical study on onset of oscillatory thermocapillary flow in rectangular liquid pool

Thermocapillary flow in a rectangular liquid pool of large Prandtl fluid (Pr = 105.6) is numerically studied in microgravity. Oscillatory thermocapillary flow arises when the imposed temperature difference between the sidewalls exceeds a critical value. The fluctuations of the oscillatory flow, accompanied by the propagation of the hydrothermal wave from the cold sidewall to the hot one, are much smaller than the time-averaged velocity and temperature fields. The corresponding disturbance cells arise in the centre of the liquid pool initially, and extend to the whole region with the increasing imposed temperature difference. The present study reveals the different characteristics of the oscillatory themocapillary flow in the rectangular liquid pool as compared to the cases in other configurations.

CSR外靶实验终端大型探测器读出电子学研制

兰州重离子加速器-冷却储存环外靶实验终端大型探测器中子墙和TOF墙分别共有504个和360个通道用于测量中子和带电粒子的飞行时间,需要高精度时间测量的读出电子学系统。研制的8通道读出电子学模块采用了前沿定时的时间测量方法、基于TOT技术的电荷测量方法和PXI总线平台,电子学测试结果显示时间测量精度好于25ps。

中能重离子碰撞中晕核反应动力学

基于同位旋相关量子分子动力学研究了中子晕核和质子晕核的核反应动力学,着重研究了松散的晕结构对于重离子碰撞中的碎裂和动量耗散中的特殊作用.为了突出晕核松散结构在反应动力学中的特殊作用.同时计算了在完全相同入射道条件下相等质量稳定弹核引起核反应.通过对晕核和稳定核核反应动力学结果的对比分析,发现晕核的松散结构对核反应动力学的作用和影响是重要的.如这种松散结构明显的增加了碎裂多重性;相反,减小了原子核阻止(动量耗散).

30MeV/u~(40)Ar+~(112,124)Sn反应中的同位素产额比与核温度

系统研究了 3 0MeV u40 Ar+ 1 1 2 ,1 2 4 Sn反应中的轻粒子同位素产额比随角度和初始激发能的变化关系 .对于两个反应体系 ,均观察到3He 4He和6Li 7Li的产额比随角度的增加而增加 ,6He 4He和8Li 7Li随角度的增加而减小 .统计发射的运动学效应不能完全符合实验结果 .各种单同位素产额比与靶核的N Z比有关 ,表现出同位旋效应 ,而由双同位素比提取的核温度几乎没有靶核相关性

Nuclear reaction dynamics induced by halo-nuclei at intermediate energy heavy ion collisions

We studied systematically the reaction dynamics induced by neutron-halo nuclei and proton-halo nuclei within the isospin dependent quantum molecular dynamics, such as the effects of loose bound halo-nuclei on the fragmentation reaction and momentum dissipation for different colliding systems with different beam energies and different impact parameters. In order to emphasize the roles of neutron-halo nucleus B-19 and proton-halo nucleus Al-23 on the reaction dynamics we also calculated the the reaction dynamics induced by the stable nuclei F-19 and Na-23 with equal mass under identical incident channel conditions. Based on the comparison of results of reaction dynamics induced by halo-nucleus colliding systems and stable nucleus collidinmg systems we found that the roles of loose bound halo-nucleus structure on the fragmentation multiplicity and nuclear stopping (momentum dissipation) are important for all of colliding systems with different beam energies and minor impact parameters, such as, the loose bound halo-nuclei structure increases the fragmentation multiplicity, but reduces the nuclear stopping.

土壤水库和森林植被对水资源的调节作用

以湖南省土地、森林利用状况等有关资料为基础，从土壤和森林对降水形成径流的影响，调节水资源的数量和方式，防洪抗旱减灾方面的作用3个层次，详细地剖析了土壤水库和森林植被对水资源的调节作用。结果指出，土壤水库和森林植被能够调节水资源，其潜力非常大。合理利用土壤水库和森林植被可以蓄水保土减蚀，削减洪峰，减少自然灾害。 关键词：土壤水库；森林植被；水资源

蒙古高原北部典型草原区土壤风蚀的~(137)Cs示踪法研究

土壤风蚀是蒙古高原北部典型草原区土地退化的主导因素之一.运用137Cs核素示踪技术对蒙古国巴彦淖尔、哈拉和林的不同牧场和弃耕地土壤风蚀速率进行了研究.巴彦淖尔草原牧场、割草场采样点土壤风蚀速率在64.58~169.07t·km-2·a-1之间,均为微度侵蚀水平.哈拉和林弃耕地年均土壤风蚀厚度4.05mm·a-1,风蚀速率为6723.06t·km-2·a-1,达强度侵蚀水平,自20世纪60年代开垦以来,表层土壤累计风蚀损失17.4cm.牧场和弃耕地风蚀速率的差异表明,在蒙古高原北部典型草原区,人为翻动表土,发展种植业,会导致严重的土壤风蚀发生,而传统牧业生产方式对土壤表层扰动较少,未导致破坏性的土壤风蚀发生,对维持生态系统稳定性有重要作用.