HCSB-DEMO�������������ȷ�����������

根据HCSB-DEMO堆的设计要求,对不同尺寸的聚变堆能产生的聚变功率、中子壁负载和等离子体燃烧时间等进行计算与分析,给出了符合设计要求的堆芯参数。在所选定的堆芯参数条件下进行了零维功率平衡计算分析,给出了3组HCSB-DEMO堆的等离子体初步设计参数。     

Unified semi‐analytical wall boundary conditions for inviscid,laminar or turbulent flows in the meshless SPH method

Wall boundary conditions in smoothed particle hydrodynamics (SPH) is a key issue to perform accurate simulations. We propose here a new approach based on a renormalising factor for writing all boundary terms. This factor depends on the local shape of a wall and on the position of a particle relative to the wall, which is described by segments (in two‐dimensions), instead of the cumbersome fictitious or ghost particles used in most existing SPH models. By solving a dynamic equation for the renormalising factor, we significantly improve traditional wall treatment in SPH, for pressure forces, wall friction and turbulent conditions. The new model is demonstrated for cases including hydrostatic conditions for still water in a tank of complex geometry and a dam break over triangular bed profile with sharp angle where significant improved behaviour is obtained in comparison with the conventional boundary techniques. The latter case is also compared with a finite volume and volume‐of‐fluid scheme. The performance of the model for a two‐dimensional laminar flow in a channel is demonstrated where the profiles of velocity are in agreement with the theoretical ones, demonstrating that the derived wall shear stress balances the pressure gradient. Finally, the performance of the model is demonstrated for flow in a schematic fish pass where both the velocity field and turbulent viscosity fields are satisfactorily reproduced compared with mesh‐based codes. Copyright © 2012 John Wiley & Sons, Ltd.     

Detection of copper(II) sulfate’s uniformity and its thermal behavior in flammability of cotton fabric

Blue vitriol (copper(II) sulfate pentahydrate), CuSO₄·5H₂O has been chosen and investigated for its effectiveness as a flame-retardant, when impregnated into cotton fabric (cotton with a plain structure; woven 180 g m⁻², with 22 numbers of yarns per 10 mm). Using the vertical flame test, the extent of resistance to burning of the specimens has been determined. The impregnation was accomplished via dipping and stirring of bone-dried, weighed fabrics into the individual and suitable concentrations of the salt at room temperature. Afterwards the samples were squeeze rolled and dried horizontally at 110°C for 30 min in an oven and cooled in a desiccator and reweighed with an analytical precision. They were then kept under ordinary conditions overnight prior the fulfillment of the vertical flame test. The efficient quantities of the aforesaid salt expressed in g per 100 g dry fabric have been determined in an average figure of 12.75%. Estimation of uniformity in a selected sample was carried out via a spectrophotometer and results are in favor of the heterogeneous distribution of the salt in the fabric’s middle sectors. However initial and final parts of specimen showed to be rather uniformed. Thermogravimetric analysis of the pure cotton and the treated ones with insufficient and effective amounts of the salt were fulfilled and their thermograms were compared and commented. The results obtained for the effect of copper(II) sulfate comply with ‘The Dust or Wall Effect Theory’. This action is also assigned to the condensed phase retardation.     

Participation of ions in promoting intermolecular associations of cell wall polysaccharides

The physiological functions of the two ions, Ca²⁺ and H⁺, in controlling mechanical properties of plant cell wall are reviewed. The interactions of these ions with major cell wall polysaccharides during cell growth and development are described. Experimental results for Ca²⁺/H⁺-induced molecular associations of some polysaccharides in solutions are also given. This article aims to bridge the understandings of molecular associations in solutions (in vitro) with those occurring in cell wall matrix of high order structure (in vivo).     

The delay of transition of a laminar boundary layer over compliant wall

In a previous paper^[1], a method has been developed to study the stability characteristics of laminar boundary layers over compliant walls. In this paper, the effect of double layered compliant wall and Kramer type compliant wall on delaying the transition is investigated, and it is shown that there does exist the possibility to delay the transition by applying such compliant walls. The project supported by the National Natural Science Foundation of China.     

Key side products due to reactivity of dimethylmaleoyl moiety as amine protective group

Dimethylmaleoyl (DMM) moiety has become an important amine protective group in sugar chemistry. We disclose herein that DMM-containing D-glucosamine analogues, because of their electrophilic nature, are prone to reactions with strong nucleophiles, such as hydrazine, resulting in a set of undesired side products that are difficult to detect, yet proved to be problematic for organic synthesis.     

大风区铁路沿线挡风墙积沙机理及优化措施的风洞实验研究

位于兰州至新疆的兰新二线是世界上首条穿越大风区的高速铁路,途径著名的烟墩风区、百里风区、三十里风区及达坂城风区,风区段铁路里程长达 462.4 km,占新疆段线路总长的 65.1${\%}$,大风对铁路的运营、养护和运输造成很大危害. 为了降低大风对通行列车的危害,兰新铁路沿线设置了大量挡风墙. 挡风墙发挥作用的同时,也带来了铁路沿线的积沙问题. 为了解决这一工程实践的现实问题,本文提出了在现有挡风墙背风侧的不同位置处,设立第二道挡墙以减弱铁路积沙的治理思路,并开展了对应条件下对现有单道挡风墙、以及在现有单道挡风墙背风侧坡顶处和坡脚处设置第二道挡墙,共计3种情景的风洞模拟实验,发现设置第二道挡墙后距轨道线路高0.1 m处的沙粒水平速度、数密度、输沙通量及沉积率较无第二道挡墙时明显减少,介于8%$\sim$12${\%}$,51%$\sim$69${\%}$,20%$\sim$73${\%}$以及26%$\sim $38${\%}$,而且在现有单道挡风墙背风侧坡顶部增设第二道挡风墙的效果更好. 因此,本文的研究成果有助于优化大风区已有铁路沿线、城镇等防沙治沙工程措施.      

Interaction of SWCNT and PPTA with sulfuric acid—Compatibilization of two materials in a common solvent

The results of a calorimetric study on the melting and crystallization behavior of concentrated sulfuric acid containing dispersed single wall carbon nanotubes (SWCNT), dissolved water, and dissolved poly‐p‐phenyleneterphthalate (PPTA) polymer are presented. The measured reduction of the heat of crystallization is caused by the build‐up of an associated layer of structured acid molecules around SWCNT and PPTA. The freezing point depression is related to the number of dissolved species such as ions. It is shown that this theory accurately describes the experimental data for dissolved water and sulfur trioxide, but not for large molecules such as SWCNT. A mechanism for the interaction between sulfuric acid and SWCNT is proposed, based on preferred adsorption of sulfur trioxide and dissociation of sulfuric acid, leading to an increased number of dissolved low‐molecular‐weight species. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1914–1922, 2008     

Geometry dependence of the viscosity of a thermotropic LC-polymer measured by slit dies

This paper reports on geometry dependent viscosity curves of the biaxial thermotropic LC-Polymer Vectra B 950 measured with rectangular slit dies. The geometry dependence of the flow behaviour originates from the flow of two layers. The layer near the wall is highly flow oriented and free from defects. The layer in the bulk has an ordered texture. The thickness of the wall layer decreases with wall shear stress. Based on the Frank theory and the assumption that the core of a moving disclination is the smallest radius of distortion, the wall layer thickness is predicted and compared with experimental data.     

槽道湍流近壁区多尺度输运特性研究

利用槽道湍流直接数值模拟的数据库和离散正交子波，对近壁湍流的多尺度输运特性进 行了研究. 通过在流向和展向分别进行子波多尺度分解，得到了近壁区湍动能在流向和展向 多尺度传输的不同性质，发现流向传输以能量的反传为主，而在展向能量存在明显的正传， 并且当过滤尺度较大时以正传为主. 近壁湍流能量传输的各向异性为进一步构造各向异 性大涡模拟亚格子模式提供了必要的参考.