浅谈GIS设备波纹管应用

GIS设备因其占地面积小、配置灵活、受外部环境影响小等优点,倍受电力用户青睐,目前已成为电网的关键设备。本文通过对GIS设备用波纹管的介绍,分析了波纹管在GIS应用中的种类、作用、配置原则等,可为GIS电站设计提供设计参考和建议。     

H,Cl和F原子钝化Cu_2ZnSnS_4(112)表面态的第一性原理计算

采用基于密度泛函理论的第一性原理计算方法系统研究了Cu_2ZnSnS_4体相的晶格结构、能带、态密度及表面重构与H,Cl和F原子在Cu_2ZnSnS_4(112)表面上的吸附和钝化机理.计算结果表明:表面重构出现在以金属原子Cu-Zn-Sn终止的Cu_2ZnSnS_4(112)表面上,并且表面重构使表面发生自钝化;当单个H,Cl或F原子吸附在S原子终止的Cu_2ZnSnS_4(112)表面上时,相比于桥位(bridge)、六方密排(hcp)位和面心立方(fcc)位点,三种原子均在特定的顶位(top)吸附位点表现出最佳稳定性.当覆盖度为0.5 ML时,无论H,Cl还是F原子占据Cu_2ZnSnS_4(112)表面的2个顶位均具有最低的吸附能.以S原子终止的Cu_2ZnSnS_4(112)表面在费米能级附近的电子态主要由价带顶部Cu-3d轨道和S-3p轨道电子贡献,此即表面态.当H,Cl或F原子在表面的覆盖度达0.5 ML时,费米能级附近的表面态降低,其中H原子钝化表面态的效果最佳,Cl原子的效果次之,F原子的效果最差.表面态降低的主要原因在于吸附原子从S原子获得电子致使表面Cu原子和S原子在费米能级处的态密度峰几乎完全消失.     

永磁无刷直流电机漏电故障分析及诊断

针对用永磁无刷直流电机电流信号对其漏电故障进行诊断易受汽车电池系统干扰的问题,提出一种对其转速信号进行故障特征提取的方法——阶次自分离方法.该方法以转速信号为分析对象,借鉴传统阶次分析法对变速信号的处理方式,从输出转速信号中分离出转速波动成分,对转速波动成分进行角域重采样,基于转速波动成分的阶次分析,提取由故障状态而引起转速非正常波动的阶次特征.基于永磁无刷直流电机相间漏电故障分析得知漏电故障会使电机产生转速故障信号,通过电机Matlab/Simulink仿真和漏电故障试验,分析不同漏电程度下电机输出转速信号的阶次特征,可以有效地识别电机漏电故障状态.     

浅谈GIS平面布置图设计

气体绝缘金属封闭开关设备(GIS),因其占地面积小,与环境的协调性好、配置灵活、受外部条件影响小等优点受到电力用户的青睐,目前GIS设备成为了电网的关键设备.本文通过对GIS平面布置图设计要点的阐述,能够为GIS设备变电站工程设计人员提供设计参考和建议.     

Lattice structures and electronic properties of WZ-CuInS_2/WZ-CdS interface from first-principles calculations

Using the first-principles plane-wave calculations within density functional theory, the perfect bi-layer and monolayer terminated WZ-CIS(100)/WZ-Cd S(100) interfaces are investigated. After relaxation the atomic positions and the bond lengths change slightly on the two interfaces. The WZ-CIS/WZ-Cd S interfaces can exist stably, when the interface bonding energies are-0.481 J/m~2(bi-layer terminated interface) and-0.677 J/m~2(monolayer terminated interface). Via analysis of the density of states, difference charge density and Bader charges, no interface state is found near the Fermi level.The stronger adhesion of the monolayer terminated interface is attributed to more electron transformations and orbital hybridizations, promoting stable interfacial bonds between atoms than those on a bi-layer terminated interface.     

基于阶次自分离的轮毂电机故障诊断方法

轮毂电机作为电动汽车四轮独立驱动系统的动力源,其运行状态直接关系着整车安全。为了逐步实现对轮毂电机运行状态的监测,提出一种新的方法——阶次自分离方法,以适应其复杂多变的行驶工况。本方法克服了传统阶次跟踪方法需同时采集转速信号和振动信号的局限性,仅针对转速信号进行研究,并提取其中蕴藏的非正常波动成分,同时借鉴传统阶次跟踪方法对时域非平稳信号的处理方式,对波动成分进行角域重采样和傅里叶变换,凸显出蕴藏于转速信号中的故障特征,进而实现对轮毂电机的故障诊断。结合Matlab仿真分析和轮毂电机漏电故障试验,结果表明阶次自分离方法可有效识别出轮毂电机漏电故障特征。     

氟化度及单轴应力对氟化石墨烯结构稳定性和能带的影响

采用基于密度泛函数理论的第一性原理,通过计算研究了四种(Chair、Zigzag、Boat、Armchair)双面全氟化石墨烯(N_C∶N_F=1∶1)构型,发现Chair型氟化后的石墨烯构型最稳定。在此基础上,系统研究了以Chair形式氟化时不同氟化度和单轴应力对氟化石墨烯结构稳定性与能带的影响.计算结果表明:氟化度越高氟化石墨烯结构越稳定,且双面氟化石墨烯较单面氟化更稳定。对构造的全氟化石墨烯体系沿X方向施加压(拉)应变时,石墨烯体系的起伏高度随单轴应变的增加而减小,导带底和价带顶均发生微小移动、带隙逐渐减小,带隙在轴向压应力作用下减小得更快.     

Lattice structures and electronic properties of CIGS/CdS interface:First-principles calculations

Using first-principles calculations within density functional theory, we study the atomic structures and electronic properties of the perfect and defective （2VCu＋ Incu） CulnGaSe2/CdS interfaces theoretically, especially the interface states. We find that the local lattice structure of （2VCu＋ InCu） interface is somewhat disorganized. By analyzing the local density of states projected on several atomic layers of the two interfaces models, we find that for the （2VCu＋InCu） interface the interface states near the Fermi level in CulnGaSe2 and CdS band gap regions are mainly composed of interracial Se-4p, Cu-3d and S-3p orbitals, while for the perfect interface there are no clear interface states in the CulnGaSe2 region but only some interface states which are mainly composed of S-3p orbitals in the valance band of CdS region.     

Phase equilibrium of Cd_(1-x)Zn_xS alloys studied by first-principles calculations and Monte Carlo simulations

The first-principles calculations based on density functional theory combined with cluster expansion techniques and Monte Carlo(MC) simulations were used to study the phase diagrams of both wurtzite(WZ) and zinc-blende(ZB)Cd_(1-x)Zn_xS alloys.All formation energies are positive for WZ and ZB Cd_(1-x)Zn_xS alloys,which means that the Cd_(1-x)Zn_xS alloys are unstable and have a tendency to phase separation.For WZ and ZB Cd_(1-x)Zn_xS alloys,the consolute temperatures are 655 K and 604 K,respectively,and they both have an asymmetric miscibility gap.We obtained the spatial distributions of Cd and Zn atoms in WZ and ZB Cd_(0.5)Zn_(0.5)S alloys at different temperatures by MC simulations.We found that both WZ and ZB phases of Cd_(0.5)Zn_(0.5)S alloy exhibit phase segregation of Cd and Zn atoms at low temperature,which is consistent with the phase diagrams.     

基于WMM-HMM的轮毂电机机械故障诊断方法

为有效监控电动汽车用轮毂电机的运行状态,保障整车的运行安全,提出了一种基于混合Weibull分布模型(WMM)与隐马尔科夫模型(HMM)的轮毂电机机械故障诊断方法(WMM-HMM诊断法).首先,利用轮毂电机振动信号提取敏感特征参数,用以表征其运行状态,建立观测序列.其次,利用WMM对轮毂电机各种运行状态下有限的观测序列...