An approach of dynamic mesh adaptation for simulating 3‐dimensional unsteady moving‐immersed‐boundary flows

In this paper, we present an approach of dynamic mesh adaptation for simulating complex 3‐dimensional incompressible moving‐boundary flows by immersed boundary methods. Tetrahedral meshes are adapted by a hierarchical refining/coarsening algorithm. Regular refinement is accomplished by dividing 1 tetrahedron into 8 subcells, and irregular refinement is only for eliminating the hanging points. Merging the 8 subcells obtained by regular refinement, the mesh is coarsened. With hierarchical refining/coarsening, mesh adaptivity can be achieved by adjusting the mesh only 1 time for each adaptation period. The level difference between 2 neighboring cells never exceeds 1, and the geometrical quality of mesh does not degrade as the level of adaptive mesh increases. A predictor‐corrector scheme is introduced to eliminate the phase lag between adapted mesh and unsteady solution. The error caused by each solution transferring from the old mesh to the new adapted one is small because most of the nodes on the 2 meshes are coincident. An immersed boundary method named local domain‐free discretization is employed to solve the flow equations. Several numerical experiments have been conducted for 3‐dimensional incompressible moving‐boundary flows. By using the present approach, the number of mesh nodes is reduced greatly while the accuracy of solution can be preserved.     

A procedure for measuring the flexibility of single wood-pulp fibres

A way of determining the flexibility of wood-pulp fibres is developed, which involves i) a precise measurement of the topology of single-fibres by using a confocal laser scanning microscope and ii) the measurement of the elastic modulus of the fibres by using a single-fibre fatigue cell. Reported in this paper are the initial results of tests carried out on black spruce fibres, which have been subjected to three different levels of mechanical refining energy, namely ∼1100, 2300, and 3500 kWh/t. It is found that the fibre flexibility rises significantly between the first and second energy levels, but it does not change to the same degree between the second and third ones. The described procedure of measuring the flexibility of fibres may be used to establish the appropriate refiner energy necessary for the production of a specific grade of paper. Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 1, pp. 115–128, January–February, 2006.     

Lu2O3对球形Ni(OH)2高温充放电性能的影响

为了改善镍电极的高温充电效率，采用机械混合的方式将球形Ni(OH)2与不同比例的Lu2O3混合后制成粘结式镍正极。充放电测试、循环伏安和XRD等实验结果表明，掺杂Lu2O3后镍电极的析氧过电位明显提高，高温充电效率得到了很大改善，在充电后的电极中β-NiOOH生成；而且Lu2O3的掺杂比例对镍电极的高温性能在不同的充放电倍率下有不同程度的影响，3．5％是最好的掺杂比例，掺杂对高温小电流充电效率的改善作用要大于高温大电流充电。     

铌酸锂晶体性能的组成依赖性(英文)

总结了铌酸锂晶体的各项性能指标,显示了其对晶体实际组成的强烈依赖性.利用化学键模型定量地解释了这种依赖性产生的根源,从而说明了制约该晶体性能提高的关键因素是晶体结构中的缺陷控制.     

Al3Ti1B1RE细化剂对罐用铝材的细化效果及稀土的作用

采用XRD，OM，SEM，EDAX等探讨了一种新型Al3Ti1B1RE中间合金细化剂对罐用铝材的细化效果及RE的作用。结果表明，该细化剂对罐用铝材的细化效果优于进口和国产Al3Ti1B，且具有长效性，达6h后仍未见明显衰退，明显提高了该材料的强度和塑性；其细化效果及稳定性好的主要原因是：RE可降低铝液的表面能，增加铝液对细化核心(如TiAl3，TiB2)的润湿性，既充分发挥了异质形核作用，又防止了TiB2聚集沉淀倾向；RE也极易在结晶前沿富集造成成分过冷，阻碍了α-Al晶粒生长，并促进其在细化核心上形核；此外RE还兼有一定的净化、细化和变质作用，尤其是净化作用提高了该细化剂的冶金质量。     

活性炭对丙烯酰胺单体水溶液的精制作用

活性炭对丙烯酰胺单体水溶液的精制作用李瑛＊孙文霞季鸿渐郭淑玲＊＊申花英＊＊（中国科学院长春应用化学研究所长春１３００２２）关键词丙烯酰胺，精制，活性炭１９９６－１２－１３收稿，１９９７－０６－１６修回国家“八五”攻关项目专题＊＊现在大庆油田管理局化...     

Influence of the peak height distribution on separation performances: Discrimination factor and effective peak capacity

Summary A new index of performance of the chromatographic separation between two adjacent peaks, the discrimination factor, d₀, is defined. It is normalized between 0 and 1 and is directly and easily determined from the chromatogram. It does not depend on any assumption regarding peak shape, except that the peak profiles of individual sample components have a single mode. Its value depends on the relative heights of the two peaks as well as on their separation. The separation power of a chromatographic system is classically measured by its peak capacity, defined on the basis of constant resolution between adjacent peaks. A previously developed statistical theory of the composition of mixtures makes it possible to extend the concept of peak capacity by taking into account the peak height distribution in typical average chromatograms. A new parameter, the effective peak capacity, is defined for this purpose on the basis of a constant discrimination factor between adjacent peaks. It allows to take into account the distribution of peak heights in statistical theories of the evaluation of complex chromatograms and in the measurement of the limit of determination in quantitative analysis. The characteristics of the two new parameters, the discrimination factor and effective peak capacity, are discussed and compared with those of their classical homologs, resolution and peak capacity, in the case of gaussian component peaks of equal widths.     

表面活性剂在离子选择电极分析中的增敏作用

本文以涂丝Ag-Ag2S电极为指示电极,饱和甘汞电极和自制锑电极为参比电极,分别试验了加入阳离子、阴离子和非离子表面活性剂对电极灵敏度的影响。结果表明,加入非离子表面活性剂对电极响应无明显影响,但阴离子和阳离子表面活性剂可使电极灵敏度有较大提高;其中,十六烷基三甲基溴化铵(CTMAB)和十二烷基苯磺酸钠(SDBS)、十二烷基硫酸钠(SDS)对电极的增敏效果显著,可使电极响应线性范围下限扩大一个数量级左右,且电极响应时间缩短,稳定性提高。     

Tribological behaviors of a novel trilayer nanofilm: the influence of outer chain length and interlayer thickness

Polydopamine (coded as PDA) is reported to be very adhesive and reactive due to the attached functional groups, such as amine and hydroxyl groups. In this work, taking advantage of the condensation between Si–OH of the hydroxylated alkyltrichlorosilane (ATS) and C–OH on PDA surface, ATS molecules with different chain carbon number of 10, 14 and 18 were grafted onto the 3‐aminopropyl triethoxysilane (APTES)‐PDA dual‐layer film, which was composed of PDA outerlayer and APTES underlayer, on Si substrate. Thus, hydrophobic trilayer films coded as APTES‐PDA‐ATS were prepared successfully. In order to reveal the dependence of the tribological behaviors upon the microstructures of the film, tribological experiments were conducted on an atomic force microscope and a ball‐on‐plate tribometer. Experimental results showed that the (micro‐) friction reducing (characterized by a parameter of relative friction coefficient or friction coefficient, RFC or FC) and macro‐wear resisting (characterized by anti‐wear life) behaviors were related with the chain length of outerlayer and the PDA thickness. Specifically, on one hand, as the chain length increases, RFC/FC decreased and macro anti‐wear life lengthened; on the other hand, as PDA gets thicker, RFC increased and the anti‐wear life enhanced. Copyright © 2013 John Wiley & Sons, Ltd.     

稀土镧在腈纶纤维化学镀银中的应用及其电化学性能

采用化学镀法(镀液中加入适量的稀土镧)在硅烷偶联剂改性后的腈纶纤维表面沉积金属银,由粒径分析、X射线衍射、扫描电子显微镜、阴极极化曲线以及循环伏安曲线等方法对其进行表征,研究了硝酸镧对化学镀银沉积速度、镀层质量和电化学性能的影响。结果表明,镀银液中加入适宜的硝酸镧,银的沉积速率和腈纶纤维表面银镀层的表面质量均有不同程度的提高。电化学测试表明,镀银液中增大硝酸镧的浓度(0～0.01 g/L),阴极极化曲线极化度增大,氧化还原峰的电流上升,电沉积的速度加快。