Oxidation and reforming reactions of CH4 on a stepped Pt(5 5 7) single crystal

The oxidation and reforming kinetics of methane by O₂, CO₂ and H₂O were studied on a stepped Pt(5 5 7) single crystal from 623 to 1050 K under methane rich conditions. The rate of carbon deposition was followed by ex-situ Auger electron spectroscopy under non-oxidative conditions. The apparent activation energy for methane decomposition was significantly lower than the apparent barriers measured for both total oxidation, CO₂ and H₂O reforming. Total oxidation of methane to CO₂ and H₂O followed by combined dry and steam reforming (combined combustion-reforming) led to CO production rates which were higher than direct CO₂ or H₂O reforming rates. The enhanced rates are most likely due to the ability of adsorbed oxygen to prevent carbon nucleation and/or scavenge carbon enabling the reforming reaction to turnover on a larger fraction of sites. Comparable amounts of carbon were found by Auger electron spectroscopy measurements after both direct dry or steam reforming, while combined oxidation-reforming had considerable less carbon. During direct dry or steam reforming, CO₂ and H₂O serve only to scavenge adsorbed atomic carbon, while in the presence of oxygen, carbon is removed by both combustion and reforming routes.     

高收率合成DADE的新方法

在比较DADE的3条文献合成路线基础上，研究了以2-甲基-4，6-嘧啶二酮为母体用硝硫混酸硝化生成中间体2-(二硝基亚甲基)-5，5-二硝基-2H-嘧啶-4，6-二酮、中间体水解合成DADE的方法。DADE总收率达到83％以上，用IR、MS、NMR及元素分析鉴定了其结构。     

Effects of apitong (Dipterocarpus spp.) extractives on bond strength development and curing rate of adhesives

Emulsion polymer isocyanate ( ), polyvinyl acetate ( ) and resorcinol-formaldehyde ( ) adhesives were used to produce single lap shear specimens using resinous and non-resinous apitong (Dipterocarpus spp.) timbers. Tests showed that joints made with highly resinous apitong were about 40% weaker than similar joints made with non-resinous apitong. The resinous apitong was treated with different solvents to yield five different extractives which were characterized by infra-red analysis. Apitong extractives were then added to and adhesives and joints made with buna (Fagus crenata), a timber known to be low in extractives and easy to bond. Joints prepared using extractive-containing adhesives were generally weaker than those made with the unmodified adhesives. RF adhesives containing extractives cured more slowly than unmodified . It is thought that the acidic nature of the extractives changes the pH of the system sufficiently to affect the curing mechanism     

基于统计的中文机构名实体识别的研究

针对中文机构名实体的识别提出了利用隐马尔科夫统计模型的方法.同时,在此方法的基础上通过构建一元模型来补充识别那些缩写的和没有核心词的机构名,弥补了单一统计模型在机构名实体识别中的不足.实验证明二者相结合的方法能获得较高的准确率和召回率,具有可行性.     

660MW超临界机组循环水系统运行优化分析

结合沧东公司循环水系统的运行条件,以及优化循环水系统的运行方式,提出了低负荷单机单泵运行方式.同时根据相关计算和试验,对该类型机组采用单泵运行的可行性、安全性、经济性进行了分析,结果表明,660 MW同类型机组低负荷时采用单台循环水泵运行完全能满足机组正常运行的需要.     

Effective prediction of DEA model by neural network

In this paper,a fast neural network model for the forecasting of effective points by DEA model is proposed,which is based on the SPDS training algorithm.The SPDS training algorithm overcomes the drawbacks of slow convergent speed and partially minimum result for BP algorithm.Its training speed is much faster and its forecasting precision is much better than those of BP algorithm.By numeric examples,it is showed that adopting the neural network model in the forecasting of effective points by DEA model is valid.     

螺纹桩在软弱地层中的应用

分析了螺纹桩的受力机理,探讨了螺纹桩单桩承载力的确定方法,指出螺纹桩单桩承载力高、节约材料显著、能充分利用地基土的特性,在软弱地层中的应用优势显著,并通过实际工程实例给予具体说明.     

基于DS18B20的多点测温扩展模块

针对目前广泛应用的DALLAS公司的数字温度传感器DS18B20,分析了多点测温电路的缺陷,介绍了一个实现多点测温模块的实现方法。使用DS18B20,配合总线驱动双向三态门74LS245的电路成功实现了多点测温,并给出了编写模块驱动程序的流程,最后说明了多点测温模块适用的场合。     

涤棉织物单面防水泡沫涂层工艺

通过泡沫整理法对涤棉织物进行单面防水整理,使其单面防水的同时反面具有良好的吸湿透气性能。复配了稳定型泡沫防水涂层剂,并探讨了该涂层工艺的最佳焙烘温度和时间。实验结果表明,最佳整理剂配方为防水剂与10%SDS溶液以2∶1混合,并添加CMC 10g/L,HEC 0.5g/L,PTF 5g/L,焙烘温度160℃,时间3min,效果最佳;织物带液率由传统整理的45%降至为26%,节约原料55%。     

双向全桥DC-DC变换器单移相闭环控制研究

针对基于传统单移相控制的双向全桥DC-DC变换器存在效率低的问题,提出了一种基于单移相闭环控制的双向全桥DC-DC变换器设计方案;分析了双向全桥DC-DC变换器稳态特性,详细介绍了基于单移相闭环控制的双向全桥DC-DC变换器的建模实现。仿真与实验结果表明,基于单移相闭环控制的双向全桥DC-DC变换器效率高、损耗小。