DMTAM光度法同时测定钯和钴

以硫脲作为掩蔽剂,在pH3.75～5.0的HAc—NaAc缓冲介质中,Pd、Co(Ⅱ)和DMTAM均能形成稳定的1∶2型配合物,其表观摩尔吸光系数分别为ε_(Pd)=6.14×10~4,ε_(Co)=6.20×10~4,遵守比尔定律的线性范围分别为Pd0～35μg/25ml,Co0～15μg/25ml。研究了30余种共存离子的影响。可应用于分子筛和矿样中Pd、Co的同时测定。     

Simulations of the dielectric constant of bonding materials and field emission properties of CNT cathodes

The effect of the dielectric constant (k) of bonding materials in a screen-printed carbon nanotube (CNT) cathode on the field enhancement factor was investigated for high-efficiency CNT cathodes using the ANSYS software. The values obtained by a simulation study were compared to the experimental results obtained for screen-printed CNT cathodes. The field enhancement factor increased as the dielectric constant decreased, reaching a maximum value at a dielectric constant of 1, the value for a vacuum. The findings indicate that the larger sheet resistance of the bonding materials, after the firing process, can be attributed to the larger emission current of the CNT cathode. From these results, it was concluded that the best bonding materials for screen-printed CNT cathodes should have a low dielectric constant and a high sheet resistance. This finding can be used as criteria for selecting bonding materials for use in CNT pastes for highly efficient CNT cathodes.     

全球铝轧制工业概览系列综述之十二 法国雷纳铝业公司新布里萨克轧制厂

对法国雷纳铝业公司新布里萨克轧制厂作了全面系统的介绍,并对普基公司的情况简介了一下。雷纳铝业公司是世界第五大铝业公司,是全球生产航空航天硬合金材料的第三大公司。雷纳铝业公司在法国本土有两个板带材轧制厂:新布里萨克轧制厂,专门轧制1×××、3×××、5×××系等民用材料;伊苏瓦尔轧制厂,以生产硬合金板材为主。新布里萨克轧制厂1961年开始建设,1967年投产,1992年对原来的3机架热精连轧生产线改为4机架的,仅用了17天时间,未影响生产。该厂有熔铸、热轧、冷轧、精整、维护等车间。热轧线生产能力450kt/a。     

Effect of Powder Injection Location on Ceramic Coatings Properties When Using Plasma Spray

The effect of powder injecting location of the plasma spraying on spraying properties was studied. Three different powder-injecting methods were applied in the experiment. In the first method, the particles were axially injected into the plasma flow from the cathode tip. In the second method, the particles were radially injected into the plasma flow just downstream of the anode arc root inside the anode nozzle. In the third method, the particles were radially injected into the plasma jet at the nozzle exit. The alumina particles with a mean diameter of 20 μm were used to deposit coatings. Spraying properties, such as the deposition efficiency, the melting rate of the powder particles, and the coating quality were investigated. The results show that the spraying with axial particle injecting can heat and melt the powder particles more effectively, produce coatings with better quality, and have higher deposition efficiency. This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2007.     

基于FNN的轮式机器人路径跟踪研究

针对目前轮式机器人在路径跟踪时容易出现的偏离期望路径甚至打滑、侧翻失去控制等问题,对轮式机器人结构及其路径跟踪特点进行了分析,构建了轮式机器人运动学模型,设计了一种基于模糊神经网络(FNN)的行进路线和行驶速度分级控制的路径跟踪方法.第一级中模糊神经网络利用机器人位姿信息确定行进路线即转弯半径,第二级根据前方路径情况和转弯半径调节机器人行驶的角速度和线速度.仿真实验表明,所设计的模糊神经网络能够对所期望的路径进行快速准确地拟合,且鲁棒性强;轮式机器人路径跟踪过程稳定,不会出现失控现象.     

岸站式河湖水质远程监控柜设计与开发

随着我国工业化进程的加速,河湖水体污染现象日益加剧,已经严重威胁到我国的经济和社会发展。鉴于目前河湖水质监测手段落后和水质评价困难的现状,本文设计了岸站式河湖水质远程监控柜。该监控柜主要安放于河湖岸边,利用水质传感器实时采集河湖的水质信息参数,连同监控柜的状态信息等通过无线网络上传至上位机监控平台,对采集到的水质信息进行分析处理,实现了对河湖水质状况的有效监测,且兼具门禁指纹认证、枯水检测等功能。同时,为了对河湖水质状况做出及时、客观的评价和分级,结合改进层次分析法与熵权法的特点,提出一种水质参数权重确定算法。该算法既兼顾了决策者的偏好,同时又尽量减小了赋权的主观随意性,促使主观与客观评价相统一,且计算较简便、可操作性好。将上述算法嵌入到监控柜上位监控系统中,在唐山青龙河水域进行了系统测试,测试结果表明该监控柜系统运行正常,可以实时获取青龙河的水质信息参数,对河湖水质状况做出及时、客观的评价和分级,实现对河湖水质的综合分析与管理,进而为河湖水环境保护提供一种有效地辅助决策平台。     

A simulation framework for measuring robustness of incentive mechanisms and its implementation in reputation systems

In game theoretical analysis of incentive mechanisms, all players are assumed to be rational. Since it is likely that mechanism participants in the real world may not be fully rational, such mechanisms may not work as effectively as in the idealized settings for which they were designed. Therefore, it is important to evaluate the robustness of incentive mechanisms against various types of agents with bounded rational behaviors. Such evaluations would provide us with the information needed to choose mechanisms with desired properties in real environments. In this article, we first propose a general robustness measure, inspired by research in evolutionary game theory, as the maximal percentage of invaders taking non-equilibrium strategies such that the agents sustain the desired equilibrium strategy. We then propose a simulation framework based on evolutionary dynamics to empirically evaluate the equilibrium robustness. The proposed simulation framework is validated by comparing the simulated results with the analytical predictions based on a modified simplex analysis approach. Finally, we implement the proposed simulation framework for evaluating the robustness of incentive mechanisms in reputation systems for electronic marketplaces. The results from the implementation show that the evaluated mechanisms have high robustness against a certain non-equilibrium strategy, but is vulnerable to another strategy, indicating the need for designing more robust incentive mechanisms for reputation management in e-marketplaces.     

一种基于项目属性评分的协同过滤推荐算法

协同过滤是电子商务推荐系统中应用最成功的推荐技术之一,但面临着严峻的用户评分数据稀疏性和推荐精度低等问题。针对数据稀疏性高和单一评分导致的推荐精度低等问题,提出一种基于项目属性评分的协同过滤推荐算法。首先通过均值法或缩放法构造用户-项目属性评分矩阵将单一评分转化为多评分;其次基于每个属性评分矩阵,计算用户间的偏好相似度,得到目标用户的偏好最近邻居集;然后针对每个最近邻居集,在用户-项目评分矩阵上完成对目标用户的初步评分预测;最后,将多个初步预测评分加权求和作为综合评分,完成推荐。在Movie Lens扩展数据集上的实验结果表明,该算法能有效提高推荐精度。