Piston-driven laminar flow and heat transfer in a plane channel with a sudden expansion

 This paper presents a numerical study of piston-driven heat transfer and fluid flow in a plane channel containing a sudden expansion. The numerical method employed is based on a control-volume-based finite element method for incompressible flow with a staggered and moving grid and SIMPLER algorithm for pressure-velocity coupling. The numerical results show a good agreement with the experimental data reported in the literature. Results concerning time and space evolution of the thermal and flow fields are presented for different values of the expansion ratio, the initial clearance volume, and the piston velocity. Received: 20 April 2002 / Accepted: 23 January 2003     

Fuel cycle strategies and plutonium management in Europe

An overview of current nuclear power generation and fuel cycle strategies in Europe is presented, with an emphasis on options for the management of separated plutonium in the medium to long term. Countries which have opted for reprocessing of spent fuel have had to contend with increasing inventories of separated plutonium. Of the various potential options for utilisation or disposition of these stockpiles, only light water reactor (LWR) mixed-oxide (MOX) fuel programmes are sufficiently technologically mature to be fully operational in several European countries at present. Such reprocessing-recycling programmes allow for a stabilisation of the overall separated plutonium stocks, but not for a significant reduction in the stockpile. Moreover, the quality of recycled plutonium decreases at each potential step of re-irradiation. Therefore, optimised or new ways of managing the plutonium stocks in the medium to long term are required. In the present overview we consider the most promising options for reactor utilisation of plutonium in both near-term future reactor and Generation IV systems.     

应用于离子注入的RFQ加速器

射频四极场(Radio frequency quodrupole,RFQ)加速器是一种非常适于用作MeV级能量离子注入的加速器.它具有束流强、体积小、使用方便、离子源处在地电位,还可同时加速正、负两种离子等优点.本文介绍了RFQ加速器在国际上的发展状况及其基本原理、北京大学研制的1 MeV RFQ加速器的具体结构、性能以及一种新型RFQ-SFRFQ组合加速器的特点.     

利用模糊综合评判法评价水井分层注水效果

对水井分层注水进行评价,可直观体现出注水井分层注水前后的效果,为此针对各因素对水井井组影响的不确定性,建立了一套适用于井组评价的定量化方法。在对井组进行注水效果评价之前,对现有各井做出评价,并利用模糊综合评判的方法计算出井组综合评价系数来评判各个井组的性质。结合普17断块的实际地质和开发状况,根据计算得出的综合评价系数E2,找出E2值与注水效果的递增关系,通过综合系数E2值评价出各井组注水效果的优劣,既可以评价井组分层注水是否合理。     

Numerical analysis of pulsating heat pipe based on separated flow model

The examination on the operating mechanism of a pulsating heat pipe (PHP) using visualization revealed that the working fluid in the PHP oscillated to the axial direction by the contraction and expansion of vapor plugs. This contraction and expansion is due to the formation and extinction of bubbles in the evaporating and condensing section, respectively. In this paper, a theoretical model of PHP was presented. The theoretical model was based on the separated flow model with two liquid slugs and three vapor plugs. The results show that the diameter, surface tension and charge ratio of working fluid have significant effects on the performance of the PHP. The following conclusions were obtained. The periodic oscillations of liquid slugs and vapor plugs were obtained under specified parameters. When the hydraulic diameter of the PHP was increased to d=3mm, the frequency of oscillation decreased. By increasing the charging ratio from 40 to 60 by volume ratio, the pressure difference between the evaporating section and condensing section increased, the amplitude of oscillation reduced, and the oscillation frequency decreased. The working fluid with higher surface tension resulted in an increase in the amplitude and frequency of oscillation. Also the average temperature of vapor plugs decreased.     

东风水电站励磁系统设计

介绍了东风水电站励磁系统的可靠性、技术先进性和辅助功能的完整性设汁，以及该励磁系统的主要技术特点。     

动态重复与线性展开——对大舍幼儿园设计中传统空间关系的解读

当代中国．如何在建筑与城市设计中．尤其是”空间”这一更为本质的层面．体现“本土意识”是一个值得探讨的话题。通过对大舍两个幼儿园设计实例（青浦夏雨幼儿园和嘉定新城实验幼儿园）的分析，研究其空间关系和组织模式对于中国传统空间的传承．进一步探索东方文化支配下的建筑与城市空间的特质。     

温度场对iPP/CAB体系形态结构的影响

利用扫描电子显微镜研究了温度场对iPP/CAB共混物样品形态结构的影响,研究发现共混物样品在150℃的硅油或者140℃的真空烘箱中放置时,随着热处理时间的增加,分散相尺寸会不断增大;并且样品在硅油中放置时,分散相尺寸增大的速度更快.     

DPMS湿式永磁磁选机在福建省连城锰矿的应用

阐述了DPMS湿式永磁磁选机在连城锰矿的应用实践,从而寻找一条回收利用庙前选厂强磁尾矿的新路子。