Syntheses and ultra-deep desulfurization performance of sandwich-type polyoxometalate-based TiO<Subscript>2</Subscript> nanofibres

The sandwich-type polyoxometalate-based TiO₂ nanofibres were prepared successfully by electrospinning combining with chemical reaction and employed in ultra-deep desulfurization. OTA–CoVW–TiO₂ nanofibres (OTA?=?CH₃(CH₂)₁₇(CH₃)₃N, CoVW?=?[Co₄(H₂O)₂(VW₉O₃₄)₂]^10?) confirmed the excellent desulfurization performance in extraction catalytic oxidative desulfurization system (ECODS). At 323 K, the 500 ppm DBT (dibenzothiophene) model oil was entirely removed within 20 min using 0.010 g 45 wt% OTA–CoVW–TiO₂ nanofibres as catalyst when O/S molar ratio was 4:1 and the dosage of model oil was 5 mL. The catalysts could be recycled and reused at least five times without remarkable decrease in catalytic activity. The desulfurization efficiencies for different substrates were shown as following order: DBT?>?4,6-DMDBT (4,6-dimethyl-dibenzothiophene)?>?BT (benzothiophene). Moreover, the possible mechanism was also elucidated.     

浅析后现代建筑中的传统元素表达

在“国际化”思潮的影响下,我国的传统建筑正在受着猛烈的冲击．而香山饭店却以超前的设计思维和以人为本崇尚自然的设计理念,成为中国传统元素与现代设计理念完美结合的典范．我们不得不承认贝先生的香山饭店设计．的确探索了一条中国建筑发展的新的道路,他在一个现代化的建筑物上,体现了中国民族建筑艺术的精华。     

Kinetics study for sodium transformation in supercritical water gasification of Zhundong coal

Zhundong coal (ZDC) has attracted much attention due to its high alkali metal content which can lead to a series of problems such as furnace slagging and ash fouling. Supercritical water gasification (SCWG) become a better choice for ZDC coal utilization because of its unique chemical and physical properties. The transformation mechanism of alkali metals during SCWG process was different from conventional ways of coal utilization. Systematic research about it could hardly be found. In this study, ZDC was used to explore sodium transformation mechanism and kinetics during supercritical water gasification under typical conditions. We got four kinds of sodium including the water-soluble fraction (L1), the carboxylic matrix-associated fraction (L2), the macromolecular organic group-associated fraction (L3), and the inorganic silicate mineral fraction (L4) through sequential extraction method after SCWG. A reaction pathway of sodium transformation in supercritical water gasification was proposed. A quantitative kinetic model for describing sodium transformation mechanism was developed. Finally, it was found that, L1 played an important role in catalytic process and mineral in coal weaken the catalytic process by combining with L1. L2 and L3 served as the two important intermediate products in the coal gasification, which explained the catalytic mechanism of sodium. L3 showed better reactivity. Sodium finally tended to deposit in the form of NaSiAlO₄ (L4) which was stable and environmentally friendly. All of these could provide basis for high-efficiency utilization of ZDC and the design of a reactor.     

Monte Carlo simulation of the diffusion-limited aggregating process of particle suspension systems

The aggregating process of particle suspension systems is a very universal phenomena and crucial for various processes both in nature and in industry. In this paper, the aggregating process was simulated with off-lattice diffusion-limited cluster-cluster aggregation (DLCA) Monte Carlo programs. The self-similar fractal structures of aggregates have been clearly demonstrated by the statistical analysis of gyration radius distribution and the existence of a scaling distribution of the reduced cluster size. The fractal dimension determined from the relationship between mass and gyration radius of aggregates was 1.80 or so. The fractal dimension of the aggregates drawn from the radial distribution function and structure factor of a single aggregate is about 1.90–2.10. It was also showed that, along with the increasing of particle volume fraction, the fractal dimension will increase in a nearly square root manner, and the spatial range of the fractal structure appearing becomes narrower. Also, the gelation transition can only occur in a particle suspension system where the particle volume fraction is greater than a critical value.     

不同湿度混凝土动力抗压性能数值模拟分析

本文基于随机骨料建立了二维混凝土的细观数值模型,利用无厚度cohesive单元模拟界面层及基体的损伤,用弹性单元模拟孔隙水,并结合黏性效应、惯性效应,模拟分析了应变率和孔隙含水率对混凝土抗压强度、峰值应变和弹性模量的影响。结果表明:动力分析时混凝土组成材料采用静力参数,考虑了惯性效应与黏性作用后,数值模型可以很好地反映动力荷载作用下混凝土名义动力强度增长因子(DIF)、单轴压缩弹性模量和峰值应变随应变率增加而增加的宏观现象,以及随着孔隙含水率增加混凝土静动态抗压强度线性减小、DIF线性增加、率效应增强的变化规律。以应变率和孔隙含水率为参数,提出了以干燥混凝土静态抗压强度为基准的含水混凝土动态抗压强度的预测公式。     

给水管道工程加气冲洗方案探讨

常规给水管道冲洗耗水量大,限制因素较多。在某工程中采用了加气冲洗方法,介绍了该方法的原理和操作步骤。对该方法与常规冲洗方法的耗水量、冲洗效果进行对比,结果表明该法冲洗效果好,大大节约了冲洗耗水量。