An investigation on electrochemical performances of as-cast and annealed La0.8Mg0.2Ni3.3Co0.2Six（x = 0-0.2） alloy electrodes for Ni/MH battery application

The La-Mg-Ni-based A2B7-type La0.5Mg0.2Ni3.3Co0.2Six （x=0-0.2） electrode alloys were prepared by casting and annealing. The influences of the additional silicon and the annealing treatment on the structure and electrochemical performances of the alloys were investigated systemically. Both of the analyses of XRD and SEM reveal that the as-cast and annealed alloys are of a multiphase structure, involving two main phases （La, Mg）2Ni7 and LaNi5 as well as one minor phase LaNi3. The addition of Si and annealing treatment bring on an evident change in the phase abundances and cell parameters of （La, Mg）2Ni7 and LaNi5 phase for the alloy without altering its phase structure. The phase abundances decrease from 74.3% （x=0） to 57.8% （x=0.2） for the （La, Mg）2Ni7 phase, and those of LaNi5 phase increase from 20.2% （x~0） to 37.3% （x=0.2）. As for the electrochemical measurements, adding Si and performing annealing treatment have engendered obvious impacts. The cycle stability of the alloys is improved dramatically, being enhanced from 80.3% to 93.7% for the as-annealed （950 ℃） alloys with Si content increasing from 0 to 0.2. However, the discharge capacity is reduced by adding Si, from 399.4 to 345.3 mA.h/g as the Si content increases from 0 to 0.2. Furthermore, such addition makes the electrochemical kinetic properties of the alloy electrodes first increase and then decrease. Also, it is found that the overall electrochemical properties of the alloys first augment and then fall with the annealing temperature rising.     

进气谐振对单缸发动机动力性能影响的试验研究

利用进气过程增加气缸内的进气量是提高发动机动力性能的有效途径,对发动机进气过程的动态特性进行了理论分析,并对进气管道和谐振器的结构参数进行了理论计算。在单缸摩托车汽油机上进行试验,结果显示,发动机输出的最大功率和最大扭矩提高了6%~8%,并且随着谐振器工作容积的变化,功率和扭矩的变化也呈现一定的规律性。因此,在一定的转速范围内,合理利用进气谐振可以有效提高发动机在该工况下的动力性能。     

反应等离子喷涂制备FeAl2O4-Al2O3-Fe涂层的性能研究

对反应等离子喷涂制备的FeAl2O4-Al2O3-Fe金属／陶瓷复合涂层的性能进行了研究。结果表明该复合涂层显微硬度存在压痕尺寸效应，并符合Meyer公式，其Meyer指数约为1．75；复合涂层以穿晶断裂为主，断口存在较大起伏，并具有金属拔出机制和韧窝明显的韧性断裂特征，复合涂层韧性较好；涂层结合性能好，结合强度约23．03MPa，要高于普通AT13陶瓷涂层；涂层较致密，孔隙率约为3．33％，低于普通AT13陶瓷涂层。     

PTC热敏电阻铝电极玻璃成分与电性能的关系

作者通过实验证明PTC热敏电阻器欧姆接触、通电老化、高温老化及潮热老化与铝导电浆料中玻璃组分的关系.在B、Si、Pb玻璃中添加Zr、Al、V和Na的氧化物,PTC热敏电阻器的电性能可以满足使用要求.     

外补偿法改善永磁体温度稳定性的研究进展

本文介绍了外补偿法改善永磁体磁性能温度稳定性的工作原理,综述了近年来外补偿法的应用现状,以及外补偿法对Nd-Fe-B永磁体进行磁性能温度补偿的应用情况和研究状况,阐述了补偿设计中所需的关键材料磁温度补偿合金的合金成分和制备工艺方面的研究进展,提出通过外补偿法使Nd-Fe-B永磁体取代Sm-Co磁体的可能性,指出存在的主要问题是磁温度补偿合金的热磁性能达不到要求,缺乏配套的高性能耐腐蚀的Nd-Fe-B永磁体,磁温度补偿合金与Nd-Fe-B永磁体之间的匹配问题,以及相应的磁路设计、组合磁体的表征方法等.     

A Prediction Region‐based Approach to Model Uncertainty for Multi‐response Optimization

Multi‐response optimization methods rely on empirical process models based on the estimates of model parameters that relate response variables to a set of design variables. However, in determining the optimal conditions for the design variables, model uncertainty is typically neglected, resulting in an unstable optimal solution. This paper proposes a new optimization strategy that takes model uncertainty into account via the prediction region for multiple responses. To avoid obtaining an overly conservative design, the location and dispersion performances are constructed based on the best‐case strategy and the worst‐case strategy of expected loss. We reveal that the traditional loss function and the minimax/maximin strategy are both special cases of the proposed approach. An example is illustrated to present the procedure and the effectiveness of the proposed loss function. The results show that the proposed approach can give reasonable results when both the location and dispersion performances are important issues. Copyright © 2015 John Wiley & Sons, Ltd.     

WC体积分数对WC_p/Fe复合材料组织及压缩性能的影响

为研究WC体积分数对WC_p/Fe复合材料组织、界面及压缩性能的影响,采用粉末烧结法制备了不同WC体积分数的WC_p/Fe复合材料。结果表明:在不同WC体积分数的WC_p/Fe复合材料中,WC颗粒发生了不同程度的溶解,其与基体间均呈冶金结合。随着WC体积分数的增加,WC_p/Fe复合材料的界面等效宽度呈现递减趋势,当WC体积分数为50%时,界面等效宽度最小,为39.8μm;复合材料的压缩强度呈先增大后减小趋势,当WC体积分数达到45%时,压缩强度达到最大值;复合材料的断裂方式由准解理断裂逐渐转向纯解理断裂,当WC体积分数达到50%时,WC_p/Fe复合材料的断裂方式为纯解理断裂。     

不同拓扑结构FC-AE-1553B网络性能研究

研究点对点、交换式与仲裁环3种不同拓扑结构的网络,建立FC-AE-1553B网络的Markov模型,并分析单点故障对不同拓扑结构总线的影响。仿真结果表明,基于点对点结构的FC-AE-1553B网络在传输NT节点到NC节点的数据流时,具有最小时延,基于交换机实现的FC-AE-1553B网络在传输NT节点到NT节点的数据时,传输性能较优。     

合成气燃气轮机燃烧室的试验研究

对某分管型燃气轮机燃烧室及其两个用于燃烧中热值合成气的改造方案在中压全尺寸试验台上进行了考核和实验研究。试验采用的等容积流率模化准则,即采用与真实燃烧室相同的尺寸、燃料、过量空气系数以及燃料和空气进口温度,而空气的总压和流量以及燃料的流量取为真实参数的1/6。试验结果表明2个改造方案的性能参数,包括燃烧效率、总压损失、出口温度分布、火焰筒壁面温度分布和火焰的稳定性(贫燃料熄火极限)都能够满足设计要求。此外,与原型燃烧室燃烧轻柴油的工况相比,2个改造方案在燃烧合成气时燃烧室主燃区的火焰筒壁面温度升高,而燃烧室的NOx排放大大降低,火焰的稳定性得到明显改善。因此保持火焰筒开孔规律不变,增大气体燃料喷射孔面积并增强旋流对燃烧室进行改造,使其能够高效洁净地燃烧中热值合成气,该方法是可行的。     

我国政府角色偏离的表现与原因探析

政府角色偏离现象是构建和谐社会的政府主体障碍之一,其外在表现为:政府规模相对庞大,职权行使越位,政府诚信表现不足,行政责任意识淡化,监督主体缺位等。而探析其成因主要可以从思想观念的转变、体制法规的健全、绩效指标的选取、公务员员素质的提升四个方面入手。