Facile construction of composition-tuned ruthenium-nickel nanoparticles on g-C3N4 for enhanced hydrolysis of ammonia borane without base additives

Developing high-efficiency and low-cost catalysts for hydrogen evolution from hydrolysis of ammonia borane (AB) is significant and critical for the exploitation and utilization of hydrogen energy. Herein, the in-situ fabrication of well-dispersed and small bimetallic RuNi alloy nanoparticles (NPs) with tuned compositions and concomitant hydrolysis of AB are successfully achieved by using graphitic carbon nitride (g-C₃N₄) as a NP support without additional stabilizing ligands. The optimized Ru₁Ni_7.5/g-C₃N₄ catalyst exhibits an excellent catalytic activity with a high turnover frequency of 901 min^?1 and an activation energy of 28.46 kJ mol^?1 without any base additives, overtaking the activities of many previously reported catalysts for AB hydrolysis. The kinetic studies indicate that the AB hydrolysis over Ru₁Ni_7.5/g-C₃N₄ is first-order and zero-order reactions with respect to the catalyst and AB concentrations, respectively. Ru₁Ni_7.5/g-C₃N₄ has a good recyclability with 46% of the initial catalytic activity retained even after five runs. The high performance of Ru₁Ni_7.5/g-C₃N₄ should be assigned to the small-sized alloy NPs with abundant accessible active sites and the synergistic effect between the composition-tuned Ru–Ni bimetals. This work highlights a potentially powerful and simple strategy for preparing highly active bimetallic alloy catalysts for AB hydrolysis to generate hydrogen.     

Enhancing urban infrastructure investment planning practices for a changing climate.

Climate change raises many concerns for urban water management because of the effects on all aspects of the hydrological cycle. Urban water infrastructure has traditionally been designed using historical observations and assuming stationary climatic conditions. The capability of this infrastructure, whether for storm-water drainage, or water supply, may be over- or under-designed for future climatic conditions. In particular, changes in the frequency and intensity of extreme rainfall events will have the most acute effect on storm-water drainage systems. Therefore, it is necessary to take future climatic conditions into consideration in engineering designs in order to enhance water infrastructure investment planning practices in a long time horizon. This paper provides the initial results of a study that is examining ways to enhance urban infrastructure investment planning practices against changes in hydrologic regimes for a changing climate. Design storms and intensity-duration-frequency curves that are used in the engineering design of storm-water drainage systems are developed under future climatic conditions by empirically adjusting the general circulation model output, and using the Gumbel distribution and the Chicago method. Simulations are then performed on an existing storm-water drainage system from NE Calgary to investigate the resiliency of the system under climate change.     

探针馈电圆柱共形微带天线阻抗特性的FDTD法分析

将圆柱坐标系下非分裂式理想匹配层吸收边界条件(UPML)引入到圆柱共形微带天线的全波分析中，并给出了其中的场量迭代方程，明显地减小了计算空间，简化了编程；提出了圆柱坐标系下考虑有限尺寸探针半径的新算法，使得计算结果更加精确；应用GPOF方法预估了时域晚时响应，使计算时间减少了70％～90％。本文给出的模型能够对任意多层圆柱共形结构的微带天线进行计算，因此对此类天线的CAD设计具有实际意义。     

宽带PON系统测试、设备进展和应用展望

宽带正成为国内外运营商战略和业务转型的基础.在国内,宽带已成为拉动固网运营商业务收入增长的主要动力.作为推动宽带业务发展的宽带接入技术正在不断发展和演进,特别是近两年新推出的宽带PON(无源光网络)技术由于带宽高、扩展性好、运维成本低等优点,正成为电信领域的热点.本文就主流宽带PON技术、系统测试、芯片和设备进展进行简要介绍,最后对其应用予以展望.     

氧化钙固体碱催化剂用于大豆油和甲醇酯交换制备生物柴油的研究

对氧化钙固体碱催化剂用于甲醇和大豆油的酯交换反应制备生物柴油（脂肪酸甲酯）进行了研究，考察了醇油摩尔比、反应温度、催化剂用量等因素对生物柴油产率的影响，以及采用四氢呋喃等溶剂溶解产物中的甘油和脂肪酸甲酯以分离回收催化剂的方法。结果表明，在醇油摩尔比为12、反应温度为65℃、催化剂用量为8％、反应1．5h的条件下，生物柴油产率达到了95％以上。重复使用实验结果表明，CaO的催化活性比K2CO3／γ-Al2O3和KF／γ-Al2O3固体碱催化剂高，寿命更长，重复使用20次后催化效果无明显下降。     

油田数字技术的应用

如何获取数据并对数据进行处理,如何提高决策的质量和效率,数字技术的迅速变化正推动着它们的变革与发展.利用新老数字技术,BP(英国石油公司)致力于最大限度地发挥其资产效率、提高采收率并降低成本.该公司实施了一项名为未来油田(FOTF)的项目,该项目涉及技术开发和推广应用,并涉及新老油田、海上和陆上油田从油藏到原油外输各个方面的油气田生产方面问题的解决方法.     

随机减量技术中周期激励的影响及消除方法

本文针对机械系统中通常存在确定性周期激励的事实 ,论证了周期干扰成分的存在对提取的随机减量特征信号的影响 ,基于数字滤波技术提出了一种从周期干扰环境中提取随机减量特征信号的简便方法。在回转机械稳定性监测中的应用实例表明本文提出的方法是有效的。     

连续油管技术与装备发展综述

自世界上第一台连续油管作业机问世至今,连续油管作业技术与装备已经过了40多年的发展历程,以其占地面积小、作业成本低、搬迁安装方便、保护油层、增加油井产量和使用范围广等诸多不可比拟的优势,得到迅速发展,并广泛应用于钻井、完井、试油、采油、修井和集输等各个作业领域。实践表明,连续油管作业技术与装备是一项具有巨大潜力和生命力的实用性技术。目前,该项技术的应用日趋活跃,备受关注。在总结连续油管作业技术与装备的发展现状和展示其发展趋势的基础上,客观地分析了国内连续油管技术与装备的应用与研究现状,提出相应的发展对策。