The dispersed SiO2 microspheres supported Ru catalyst with enhanced activity for ammonia decomposition

Ru nanoparticles supported on SiO₂ microspheres (Ru/SiO₂-GUS) were prepared by the glucose-urea-metallic salt method and applied in the decomposition of ammonia. In the glucose-urea-metallic salt method, glucose as the carbon template plays a significant role in the formation of diffusion-beneficial structural properties of Ru/SiO₂-GUS, and also induceds the modification of the electronic state of Ru. Ru/SiO₂-GUS exhibited higher catalytic activity compared with the catalyst prepared with the impregnation method. The catalytic performance of Ru/SiO₂-GUS was further enhanced with the addition of either K or Cs——the addition order and amount strongly affecting the catalytic performance. When the ratio of K/Cs to Ru is 2, the alkali metal (KOH/CsOH) solution is added in the homogeneous solution of glucose, urea, RuCl₃ and the colloidal silica, the promotion effect of K/Cs is the strongest, particularly under lower reaction temperatures. However, the promotion effects of K and Cs are different as reveled by the combined results of H₂-TPR, XPS and NH₃-TPSR. More NH₃ can be absorbed on K–Ru/SiO₂-GUS and the electron density of Ru decreased. By contrast, more metallic Ru formed on Cs–Ru/SiO₂-GUS, facilitating N₂ recombination.     

基于致动线模型的风力机尾流场数值模拟

本文基于致动线模型求解三维Navier-Stokes方程的方法,对NTNU的"BlindTest1"风力机尾流场进行了数值模拟。该方法避免了求解实际叶片的表面边界层,无需使用动网格,从而大大降低了网格量和计算时间,非常适用于尾流场的模拟。该文所有计算均基于OpenFOAM自定义的求解器ALMpisoFoam。推力和功率的计算值与实验值吻合得很好,验证了求解器的正确性。3个典型叶尖速比下的轴向诱导因子、湍动能和尾涡结构等也在文中进行了简要分析。     

The role of relationship promoter in new product development collaboration

Since new product development (NPD) collaborations with external partners have become the next generation in NPD practices, relationship promoters have become especially relevant as key contributors to the success of this type of inter-organisational collaboration. To realise successful outcomes in NPD collaborations, partners face the challenge of effectively integrating the role of relationship promoter into their existing and essential relationships of trust. It is within this context that this paper examines the role of the relationship promoter, by analysing its moderating effect on the relationship between trust and the outcomes of NPD collaboration – including new product competitiveness and partner satisfaction. We test our hypotheses against survey data from 107 innovative firms involved in NPD collaboration with the help of relationship promoters. The results show that, while a non-significant influence can be reported about the presence of a relationship promoter in terms of partner satisfaction, the relationship promotor weakens the influence of trust on new product competitiveness, making trust less important when it comes to creating a competitive new product.     

The effects of run‐of‐river dam spill on Columbia River microplankton

Dams, increasingly common in riverine systems worldwide, are particularly prevalent on the Columbia River (CR) in the United States. Hydroelectric projects, including both storage and run‐of‐river (i.e., minimal storage) structures, on the mainstem CR highly manage water flow, often by releasing water over (rather than through) dams as “spill.” To test the effects of run‐of‐river dam spill on microplankton abundance and composition, we sampled above and below two dams in the lower CR before and during spill conditions in spring 2016 and during and after spill conditions in late summer 2007. We tested the effects of location (i.e., above vs. below dams), spill condition (i.e., before, during, and after spill), and their interaction on microplankton abundance. Generally, diatoms were most abundant during springtime, whereas cyanobacteria were most abundant in late summer. Most taxa were not significantly different in abundance above and below dams, regardless of spill status; although cyanobacteria abundance was marginally higher below dams in summer 2007 (p = .04). Abundances of all taxa were significantly different between pre‐spill and spill periods in spring 2016, whereas only diatom and flagellate abundances were significantly different between spill and post‐spill periods in summer 2007. We conclude that spill conditions may influence microplankton abundance, but are not likely to affect microplankton communities on either side of run‐of‐river dams on the CR. This is important information for dam managers concerned about ecosystem impacts of spill.     

The role of Al2O3, MgO and CeO2 addition on steam iron process stability to produce pure and renewable hydrogen

Steam iron process represents a technology for H₂ production based on iron redox cycles. Fe_xO_y are reduced by syngas/carbon to iron, which is subsequently oxidized by steam to produce pure H₂. However, the system shows low stability.In this work, the effect of promoters (Al₂O₃, MgO and CeO₂) on Fe_xO_y stability is investigated (10 consecutive redox cycles). Bioethanol is used as a reducing agent. The particles are synthesized by coprecipitation method, analysed by BET, XRD, SEM and tested in a fixed bed reactor (675 °C, 1 bar). Pure H₂ is obtained controlling the Fe_xO_y reduction degree feeding different amounts of ethanol (4.56–1.14 mmol) until no CO is detected in oxidation. The results show that the promoters not only improve the thermal stability of Fe_xO_y but also affect its redox activity and react with iron forming spinel structures. MgO led to the highest activity and cyclability (H₂ = 0.15 NL; E = 35%).     

Rochow-Müller反应制备甲基氯硅烷单体工艺的研究进展

Rochow-Müller反应是一种直接合成甲基氯硅烷的方法。由于其原料易得,产物收率高,工艺较易实现,成为有机硅工业单体生产的主流工艺。到目前为止,铜基催化剂仍为Rochow-Müller反应的核心催化剂,催化性能的改善对该工艺的提升具有重大意义。在探索高效催化剂和理解其机理方面已取得相关进展,但由于副产物多,复杂性高,对该反应真实反应路径的追踪仍然较为困难。对Rochow-Müller反应的热力学过程、铜基催化剂及助催化剂的应用、反应机制及动力学过程和工艺条件的影响进行综述讨论。希望这项工作能够准确地反应Rochow-Müller反应催化工艺的最新进展,并可以促进有机硅工业的可持续性发展。     

Structure of turbulent rich hydrogen‐air premixed flames

In the present article, series of experiments were conducted to study the structure characteristics of premixed flames in turbulent rich hydrogen‐air mixtures within a constant‐volume turbulent combustion system, 7 equivalence ratios (1.2, 1.4, 1.6, 1.8, 2.0, 2.2, and 2.5), and 5 turbulent intensity (0, 0.494, 0.742, 1.080, and 1.309 m/s) were studied. With the increase of turbulent intensity, the cellularity degree was obviously enhanced for turbulence promoted the formation and the development of initial cracks by wrinkling flame‐front; furthermore, the enhanced hydrodynamic instability was also one important reason. Turbulence would change the linear growth of critical radius to equivalence ratio into nonlinear, but the variation extents had limitation. The wrinkling index of flame‐front would rise as flame expanded, and the wrinkling index on flames with similar size would be increased with the increase of turbulence once the turbulent intensity was sufficiently high. From the variations of the root mean square of related oscillation on flame‐front, it could be found that the partial amount of oscillation induced by sole turbulence was declined as flame expanded for the breakup of large eddies.     

Numerical and physical requirements to simulation of gas release and dispersion in an enclosure with one vent

Numerical and physical requirements to simulations of sub-sonic release and dispersion of light gas in an enclosure with one vent are described and discussed. Six validation experiments performed at CEA in a fuel cell-like enclosure of sizes H × W × L = 126 × 93 × 93 cm with one vent, either W × H = 90 × 18 cm (vent A) or 18 × 18 cm (B) or 1 cm in diameter (C), with a vertical upward helium release from a pipe of internal diameter either 5 mm or 20 mm located 21 cm above the floor centre, were used in a parametric study comprising 17 numerical simulations. Three CFD models were applied, i.e. laminar, standard k-?, and dynamic LES Smagorinsky–Lilly, to clarify a range of their applicability and performance. The LES model consistently demonstrated the best performance in reproduction of measured concentrations throughout the whole range of experimental conditions, including laminar, transitional and turbulent releases even with large CFL numbers. The laminar and the standard k-? models were under performing in the reproduction of turbulent and laminar releases respectively, as expected, as well as in simulation of transitional flows. The laminar model demonstrated high sensitivity to the CFL (Courant–Friedrichs–Lewy) number even below the best practices limit of 40. Three different computational domains and grids were used in order to clarify the influence of mesh quality on the capability of simulations to reproduce the experimental data. It is concluded that physically substantiated choice of CFD model, the control of the CFL number (and released gas mass balance where appropriate), and the mesh quality can have a strong effect on the capability of simulations to reproduce experiments and, in general, on the reliability of CFD tools for application in hydrogen safety engineering.