Numerical investigation on the heat transfer characteristics of a liquid-metal pool subjected to a partial solidification process

The main purpose of this paper is to investigate numerically the effects of solidification on the heat transfer characteristics of the liquid metal layer, for use in accident analyses. The situation is very similar to an overlying liquid melt pool that could be fooned in the reactor lower head during the late phase of a severe nuclear accident. Based on a computational model, MPCOOL, the numerical predictions were then assessed through a comparison with the experimental data that was obtained with various boundary temperature conditions and geometrical aspect ratios, especially for the Ra-Nu relationship. For the cases with solidification, the results of the comparison show that(a) the computational model does show a good agreement with heat transter rates inferred from the experimental data, with a few exceptions at the Ra numbers which suggest a turbulent transport; and also (b) the computational model underpredicts the heat transfer rates by about 6% than that inferred from the experimental data when it is integrally evaluated with the Ra-Nu correlation. The foregoing results are mainly due to the currently limited applicability of the computational model up to the laminar-to-turbulence transition flows and its application to the turbulence flows because it is always subjected to a model uncertainty between the laminar and turbulence. Next, an additional comparison for the cases with and without solidification was made to examine the effects of the solidification on the energy partition within the liquid metal layer and its effects on the directional heat transfer rates. The results of the comparison show that the computational model for the case without solidification predicts higher heat transfer rates by about 15% than when solidification is included, but there isn't any experimental data that directly supports this trend.     

Parallelization of a multi-blocked CFD code via three strategies for fluid flow and heat transfer analysis

This paper reports on a parallel implementation of a general 3D multi-block CFD code. The parallelization is achieved by using three strategies. Firstly, it is done on dual-processor PC-clusters where Windows NT systems are running. A multi-thread programming model is adopted for the multi-block code, where one thread corresponds to a block. Shared-memory is used for the exchange of inner-boundaries between neighboring blocks (threads) on the same node, while WinSockets are employed for those on different nodes. Secondly, the parallelization is extended to UNIX operating system. MPI is applied for all the message passing between different processors, including those on the same node. Thirdly, Pthreads (POSIX threads), a standardized application interface for threads, are adopted to take the advantage of the shared-memory feature of the SMP nodes, while MPI is only applied for the message passing between processors on different nodes. In all the strategies, a static load-balancing method is employed for equitable distribution of computational work to specified nodes. The parameters of the present code is studied in detail to facilitate the explanation of the speedup results. Two examples are provided to show the speedup and load balancing of the parallel calculation. Detailed comparison is made to evaluate the efficiency of different strategies.     

竞技体操运动员平衡木项目平衡能力影响因素研究

本研究运用文献资料法、专家访谈法、问卷调查法、测试法、数理统计等方法,以24名女运动员为研究对象,对不同水平竞技体操运动员平衡木项目平衡能力影响因素进行研究,得出结论：竞技体操运动员平衡木项目向前比向侧平衡容易保持;平衡木的高度、前庭机能和视觉对平衡能力均有影响。     

池式核沸腾中滑移汽泡的薄层蒸发传热模型

通过对池式核沸腾下加热壁面上滑移汽泡引起的薄层蒸发传热的分析,在若干假定基础上,建立了滑移汽泡薄层蒸发传热模型,并在该传热模型的基础上,结合管束沸腾传热机理的实验研究结果,给出了管束沸腾传热的薄层蒸发传热增强贡献的分析表达式,验证结果表明,采用建立模型计算所得单管池沸腾传热系数与实验结果的平均相对误差为±６．１％。     

When viewing variations in paintings by Mondrian, aesthetic preferences correlate with pupil size.

Observers consciously prefer Mondrian's paintings in their original orientation compared with a rotated position—the “oblique effect” (Latto, Brain, & Kelly, 2000). However, this finding's premise, that all vertical–horizontal orientations of the thick black lines in Mondrian's oeuvre are preferred, overlooks the fact that the overall balance of these images is also altered when they are reoriented. Thus, balance may regulate the oblique effect, which might influence conscious aesthetic preferences. To address this issue, we explore Hess's (1965, 1972) claim that observers will unconsciously increase their pupil diameter to pleasing images and constrict it to unpleasant images. We overcame Hess's methodological limitation of not keeping his images' luminances and contrast constant across conditions by presenting eight Mondrian paintings (1921–1944) to 30 observers on a CRT for 20 s each in either their original or seven rotated positions. Simultaneously, we measured their pupil size while asking them to report how (dis)pleasing they found each image. We found both evidence for the oblique effect (where image rotation hampers preference) and a correlation between this consciously reported aesthetic preference and unconsciously derived pupil size. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

润滑油加氢精制的用能分析

为了降低润滑油加氢装置的能耗,本文以工艺过程用能分析为理论依据,通过对燕化炼油厂加氢精制的能量测试,考察分析了装置能耗结构及用能特点,对进一步降低润滑油加氢精制的综合能耗提出了节能改进的建议。     

浙江省硫酸工业进展

介绍近6年来浙江省的硫酸产能和产量及下游耗酸产业结构.浙江省2005年硫酸产量占全国总产量的3%,预计2006年产量将达到1 600 kt.建议缓建硫酸装置,积极发展耗酸行业,控制进口酸量,加强企业间的协调,以使浙江省的硫酸市场在新的供需形势下建立起新的平衡.     

Effect of postmolding heat treatment on in vitro properties of a polyanhydride implant containing gentamicin sulfate

A polyanhydride implant containing gentamicin sulfate was fabricated using a laboratory-scale injection-molding machine. After injection molding, the implants were subject to heat treatment at 60°C for various time periods with or without nitrogen protection. The impact of this heat treatment on the in vitro properties of the implants including copolymer molecular weights, mechanical properties, and in vitro drug-release profiles was investigated. This heat treatment caused a drastic drop in the molecular weight of the copolymer. Heating without nitrogen protection resulted in the hardening of the implant, but heating in the presence of nitrogen rendered the implant less rigid. It was also found that a faster in vitro drug release profile was shown by implants heated without nitrogen protection and a pronounced slowing down in drug release was exhibited by implants heated with nitrogen protection.     

Synthesis of single-walled carbon nanotubes by arc-vaporization under high gravity condition

Arc-vaporization is one of the common methods to synthesize single-walled carbon nanotubes (SWNTs). However the detailed synthesis mechanism is still not clear, and the synthesis of longer and chirality-selected SWNTs has not been obtained. Here influence of the gravity G = 1 g₀, 2 g₀, and 3 g₀ is studied in order to develop the synthesis method of SWNTs. Simultaneously, calculations of heat convection are also carried out by using a fluid simulation program and the results are compared with the experimental results.     

显像管玻壳退火炉热平衡测试及评估

通过对4台玻壳退火炉的热平衡测试、计算及分析,得到了玻壳退火炉热平衡收支数据,计算出玻璃成品的单位质量产品耗热量、单位质量产品燃气耗量等主要技术经济指标。提出了进一步提高热效率的技术措施。