数据采集系统的设计研究

考虑到移动设备运行中状态信号采集和传榆的难度提出了一种新的故障诊断监控系统。该系统通过基于W77E58高速单片机的数据采集终端对移动设备的状态信号进行采集,采用无线传输方式快速传递数据。并可对数据信号进行故障诊断和精密分析。它具备快速获取大量数据、高精度数据转换、程控放大、程控五阶低通滤波等功能。该系统在固内某大型钢铁企业炼铁厂运料小车的振动状态监测项目实际应用中得以验证。     

Fuzzy risk analysis based on similarity measures between interval-valued fuzzy numbers and interval-valued fuzzy number arithmetic operators

In this paper, we present a new method for fuzzy risk analysis based on a new similarity measure between interval-valued fuzzy numbers and new interval-valued fuzzy number arithmetic operators. First, we present a new similarity measure between interval-valued fuzzy numbers. The proposed similarity measure considers the similarity of the gravities on the X-axis between upper fuzzy numbers, the difference of the spreads between upper fuzzy numbers, the heights of the upper fuzzy numbers, the degree of similarity on the X-axis between interval-valued fuzzy numbers, and the gravities on the Y-axis between interval-valued fuzzy numbers. We also present three properties of the proposed similarity measure between interval-valued fuzzy numbers. Then, we present new interval-valued fuzzy number arithmetic operators. Finally, we apply the proposed similarity measure between interval-valued fuzzy numbers and the proposed interval-valued fuzzy number arithmetic operators to propose a fuzzy risk analysis algorithm to deal with fuzzy risk analysis problems. The proposed method provides a useful way for handling fuzzy risk analysis problems based on interval-valued fuzzy numbers.     

滚子轴承受载变形计算的修正

通过对线接触Palmgren公式和推导出的有限长线接触变形理论公式的分析对比,提出了一种滚子轴承受载变形计算的修正方法。在采用现行分析方法对轴承进行求解的基础上,利用有限长线接触变形理论公式对部分计算结果进行适当的修正。该方法计算精度高且简捷,便于在工程实际中推广应用。     

Characteristics of classical Kirchhoff's superposition law in carbon atomic wires connected in parallel

The classical Kirchhoff's superposition law is hard to realize in the molecular scale devices because the coupling between the juxtaposed molecules can lead to constructive or destructive quantum interferences [Vazquez et al. nature nanotechnology 2012, 7, 663; Zhu et al. Phys. Rev. B 2014, 89, 085427]. In view of this, we try to eliminate the quantum interference between the juxtaposed molecules by increasing the distance between them. Simple junctions of carbon atomic wire(s) coupled to zigzag graphene nanoribbon electrodes are chosen as our model. Interestingly, fine Kirchhoff's superposition law phenomenon is found when the distance between the two carbon atomic wires reaches 15.5 Å. At the distance 15.5 Å, the conductance for the double carbon atomic wire (DCAW) configuration is 1.96 times of that for single carbon atomic wire (SCAW) configuration and the current across the DCAW configuration keeps nearly two times of that across the SCAW configuration at the applied biases. In addition, the conductance superposition effect becomes better when the distance between the two wires increases further and the spin filtering effect is enhanced in the DCAW configuration.     

Preparation of the Pb(Mg1/3Nb2/3)O3 films by aqueous tape casting

Lead magnesium niobate (PMN) is a relaxor ferroelectric material. Because of its high dielectric constant and superior electrostrictive properties it is commonly used in the manufacture of multilayer electronic devices which is typically produced by tape casting. However, preparation of PMN slurry formulations to use in aqueous tape casting process is not investigated in detail yet. Therefore, in this study aqueous PMN formulations were developed for tape casting and its relation with the final properties of PMN films were investigated. The slurries were prepared using poly(acrylic acid)-based comb polymer as the dispersant, nonionic acrylic latex as the binder and the hydroxypropyl methyl cellulose as the wetting agent. The results showed that it is possible to prepare flexible, crack-free PMN films using highly concentrated suspensions without using any plasticizer. The study gives guidelines for the aqueous tape casting of PMN and can be adapted to processing of other multi-component metal oxides.     

基于FPGA的任意被形发生器设计写研究

在此基于DDS技术进行任意波形发生器的研制。以单片机为控制核心,采用FPGA芯片EP1C3T144C8,通过使用相位累加器和波形ROM等模块实现DDS功能,可产生正弦,方波,三角波与锯齿波等常规波形,而且能够产生任意波形,并通过键盘一一对应波形,从而满足研究的需要。最后给出系统产生的测试数据,并对影响频谱纯度的杂数与噪声产生的原因进行分析。     

支承轴承对高速主轴系统特性的影响

结合轴系变形方程,对支承部位轴承与主轴的位移耦合以及对系统轴向力平衡条件进行了分析,提出用迭代法求解高速主轴系统刚度和临界转速的概念。计算结果表明,支承轴承的非线性对系统性能影响明显,当轴承预加轴向载荷增加时,轴承支承刚度增大,导致主轴系统刚度和临界转速随之增大。     

滚动轴承钢上复合化学镀镍技术的研究

研究了滚动轴承钢表面复合化学镀镍工艺,利用SEM分析了纯镍镀层、复合镀层的表面显微组织和相结构;采用HXZ-100显微硬度计和LY71-XM-200型表面形貌测量仪测试了镀层的硬度、耐磨性能,分析了其磨损机理.结果表明:热处理前镀层的结构是胞状突起,硬度为430.6HV;经热处理后,镀层为单一的纳米金刚石镍复合膜,均匀致密,硬度达到1 807.0HV,耐磨性大大提高;镀层的耐磨性随镀液中金刚石粉含量的不同而发生变化;镀层在19.6N压力下研磨也不会发生脱落,表明其附着力极好,达到滚动轴承的表面性能要求.     

Spin filtering and rectifying effects in the zinc methyl phenalenyl molecule between graphene nanoribbon leads

The molecule zinc methyl phenalenyl (ZMP), which is a neutral planar phenalenyl-based molecule, has been successfully synthesized experimentally, and large magnetic anisotropy was demonstrated when it is grown on the ferromagnetic metal surface [K. V. Raman et al. Nature, 2013, 493, 509]. Here, by using nonequilibrium Green's functions combined with the density functional theory, we investigate the electronic transport properties in the ZMP molecule coupled to graphene nanoribbon (GNR) leads. When the ZMP molecule is linked to zigzag GNR (ZGNR) electrodes, perfect spin-filtering effect and large spin-rectifying effect are found. And when the ZMP molecule is coupled to armchair GNR (AGNR) electrodes, rectifying effect is obtained and the rectifying directions can be manipulated by substituting the hydrogen atoms at the edge of ZMP molecule with atoms oxygen or nitrogen. The above interesting properties can be used for the next generation nanoscale device. Analyses are proposed for these phenomena.     

双联角接触球轴承轴向预载荷试验

以角接触球轴承轴向载荷和轴向位移的非线性函数关系为基础,进行了双联轴承加载试验。通过对加载曲线的分析对比,得到了施加在双联轴承上的轴向预载荷。串联型双联轴承虽然不存在预载荷问题,但通过加载试验曲线的测试与分析,可以使两套轴承承受相同的轴向载荷。