NiCoFe/C cathode electrocatalysts for direct ethanol fuel cells

A direct ethanol fuel cell (DEFC), which is less prone to ethanol crossover, is reported. The cell consists of PtRu/C catalyst as the anode, Nafion^® 117 membrane, and Ni–Co–Fe (NCF) composite catalyst as the cathode. The NCF catalyst was synthesized by mixing Ni, Co, and Fe complexes into a polymer matrix (melamine-formaldehyde resins), followed by heating the mixture at 800 °C under inert atmosphere. TEM and EDX experiments suggest that the NCF catalyst has alloy structures of Ni, Co and Fe. The catalytic activity of the NCF catalyst for the oxygen reduction reaction (ORR) was compared with that of commercially available Pt/C (CAP) catalyst at different ethanol concentrations. The decrease in open circuit voltage (V_oc) of the DEFC equipped with the NCF catalysts was less than that of CAP catalyst at higher ethanol concentrations. The NCF catalyst was less prone to ethanol oxidation at cathode even when ethanol crossover occurred through the Nafion^®117 film, which prevents voltage drop at the cathode. However, the CAP catalyst did oxidize ethanol at the cathode and caused a decrease in voltage at higher ethanol concentrations.     

个旧有色冶化公司一期低浓度铜烟气制酸工程简介

介绍90 kt/a铜冶炼烟气制酸装置的设计和运行情况。采用三段式净化工艺与污水处理系统相结合, 有效地解决了用高砷、氟铜精砂生产硫酸的问题。采用多孔板支撑缩放管气体换热器与高蓄热能力的转化器相结合,在转化器进口平均φ(SO2)约4％,而生产负荷仅为设计能力(270t/d)的74％的条件下,转化系统仍能维持自热平衡。     

一种支持企业集成的基于Agent的企业信息模型

文章从企业集成的角度,对企业信息模型进行探讨和研究,提出基于Agent的企业信息模型以支持企业集成和电子商务活动.     

抛物问题Mortar有限元的瀑布型多重网格法

对抛物问题的全离散格式采用Mortar型有限元逼近,构造了相应的瀑布型多重网格法,证明了该方法的最优性.     

非线性等式与不等式问题的信赖域算法

５１．引言 本文讨论如下非线性等式与不等式问题的求解问题：其中,吐。）是＊”＋Ｂ的连续可微函数． 非线性问题（１．１）广泛出现于优化问题、互补问题及变分不等式等应用数学领域中,因而对其算法的研究也是计算数学的一个重要部分．许多作者考察了该问题的求解,如Ｄｅｎｎｉｓ和Ｓｃｈｎａｂｅ［６］, Ｐｓｈｅｎｉｃｈｌｌｙｉ［９］, Ｒｏｂｉｎｓｏｎ［１０１等人讨论了该问题的牛顿法求解,梯度法求解,Ｂｕｒｋｅ和 Ｈａｎ［‘］讨论了高斯一牛顿法求解． Ｄｅｎｎｉｓ在［５］中首次采用了信赖域算法的求解,［５］中通过引…     

壳间连接形式对双层壳声辐射性能的影响

研究流场中受径向点激励的有限长双层圆柱壳壳间用实肋板连接或用托板连接对其振动和声辐射性能的影响。壳体的振动用Flügge壳体方程描述,将加强构件等价为对内外壳体的支持力,实肋板作用可以等价为周向、轴向和径向三个方向的力和轴向弯矩作用到壳体上。托板近似简化为拉压杆件进行计算,并推导了托板的动反力公式,然后将其引入壳体振动方程,最后求解双壳体声-流体-结构耦合方程,计算结果用辐射声功率、表面振动均方速度级和辐射效率的形式表示。在数值分析部分,讨论了壳间连接型式变化对双层圆柱壳的声辐射性能的影响,分析了托板和实肋板的差别。得出结论:壳间连接越紧密,对应的双层加筋圆柱壳的辐射声功率越高。     

用自回归最小二乘消噪法提纯轴承故障信号

为了消除噪声信息、提取反映机械部件故障的有用信息，对自适应消噪方法进行研究。利用自回归最小二乘消噪方法提纯反映轴承故障的机械信号，该方法应用于6215轴承故障的检测，提取出反映轴承故障的冲击信号，检测出其轴承外圈和滚珠故障，并与理论计算的轴承故障特征频率相吻合，效果很好。     

Cutting Force Model for a Small-diameter Helical Milling Cutter

In the milling process, the major flank wear land area (two-dimensional measurement for the wear) of a small-diameter milling cutter, as wear standard, can reflect actual changes of the wear land of the cutter. By analyzing the wearing characteristics of the cutter, a cutting force model based on the major flank wear land area is established. Characteristic parameters such as pressure parameter and friction parameter are calculated by substituting tested data into their corresponding equations. The cutting force model for the helical milling cutter is validated by experiments. The computational and experimental results show that the cutting force model is almost consistent with the actual cutting conditions. Thus, the cutting force model established in the research can provide a theoretical foundation for monitoring the condition of a milling process that uses a small-diameter helical milling cutter.     

实现机床颤振早期诊断的一个新的特征量

本文通过大量试验信号的互谱分析,找出了颤振建立过程中切削力和振动加速度信号互谱的特征变化:主频带的移动及其相位差的变化.然后,基于互谱与互相关函数的关系.分析了一步互相关系数的变化与互谱上述两种特征变化的内在联系.从而可将一步互相关系数作为机床颤振早期诊断的一个特征量.试验结果表明,该特征量是有效的.