Nonlinear dynamic analysis of a rotor system with fixed-tilting-pad self-acting gas-lubricated bearings support

Based on the nonlinear theory, the unbalanced responses of a fixed-tilting-pad gas-lubricated journal bearing-rigid rotor system are investigated. A?time-dependent mathematical model is established to describe the pressure distribution of gas-lubricated journal bearing with nonlinearity. The rigid rotor supported by a fixed-tilting-pad self-acting gas-lubricated journal bearing is modeled. The differential transformation method has been employed to solve the time-dependent gas-lubricated Reynolds equation, and the dynamic motion equation has been solved by the direct integral method. The unbalanced responses of the rotor system supported by fixed-tilting-pad gas-lubricated journal bearings are analyzed by the orbit diagram, Poincaré map, time series, and spectrum diagram. The numerical results reveal periodic, period-3, and quasiperiodic motions of nonlinear behaviors of the system. Finally, the effects of pivot ratio and preload coefficient on the nonlinear dynamic characteristics of the fixed-tilting-pad self-acting gas-lubricated journal bearing-rotor system are investigated.     

半导体纳晶能级结构与电子性质的电化学研究

了解半导体纳晶能级结构特征和电子特性是其在光电子器件中应用的基础,电化学循环伏安技术提供了一种获取上述关键信息的有效途径。本文系统介绍了利用循环伏安技术探测纳晶能级结构与电子性质的原理、方法以及局限;在此基础上,着重从纳晶能级结构与电子性质的影响因素及规律、纳晶电荷输运性质、纳晶电化学反应机理等方面,综述了该方向近年来取得的研究进展;最后指出了目前研究中存在的问题,并预测了今后的发展方向。     

有限长滑动轴承非线性油膜力的近似解法

本文中提出了一种求解有限长径向滑动轴承非线性油膜力的近似解析方法.在滑动轴承-转子系统非线性动力行为分析中,油膜力计算模型通常采用"π"油膜假设,但是,实际工况中油膜的存在区域并非是"π"区域,运行时油膜中出现气穴,破裂成条纹状(即具有Reynolds边界条件).本文中的近似解析方法采用Reynolds边界条件,基于变分原理,运用分离变量法求解油膜的压力分布,其中油膜压力的周向分离函数通过无限长轴承的油膜压力分布获得,油膜的破裂终止位置角通过连续条件确定,轴向分离函数运用变分原理并结合周向函数求得.计算结果表明:本文中提出的方法和有限元方法的结果吻合得很好.在此基础上,分析了一些轴承参数对油膜压力分布的影响.     

突破传统教学模式 深化工程力学课程改革

 针对目前大部分学生认为工程力学课程抽象和所学知识与实践应用脱节的现象,介绍了 通过转变教师角色,突破传统教学模式,采用现代化教学手段,根据需要对教学内容进行整 合,注重实践教学和改革考核机制等措施去培养学生的学习自主性和创新能力,使学生养成 良好的学习习惯,为本课程和其他课程的学习起到良好的促进作用.     

聚噻吩在离子液体中的电化学合成研究

Polythiophene（PTh）films were prepared by the direct electropolymerization of thiophene in the ionic liquid,1-butyl-3-methylimidazolium hexafluorophosphate（BMIM）PF6 . The structure and morphology of PTh films were characterized by means of the FT-IR spectrum and the scanning electron microscopy（ SEM）. The electrical and electrochemical properties of PTh films were examined with the UV-Vis spectrum,cyclic voltammetry（CV） and four-probe method. The results showed that when the potential for electropolymerization was controlled between +1.7 and +1.9 V（vs. Ag/AgCl）,very homogeneous PTh films could be prepared in the ionic liquid （BMIM）PF6 used as solvent and electrolyte. The de-doping（reduction）and re-doping（re-oxidation）of the PTh film prepared in ionic liquid are reversible and stable,and the conductivity of PTh films is 0.01-0.1 S/cm.     

含磷杂环化合物研究(Ⅵ)——2-硫逐(或无取代)-2-酯基取代氧乙烯基(或肟、胺、烷硫基)1,3,2-苯并二氧磷杂戊环化合物

合成了4个1,3,2-苯并二氧磷杂戊环的三价磷化合物Ⅰ_1-4,7个2-硫逐1,3,2-苯并二氧磷杂戊环的五价磷化合物Ⅱ_1-7,研究了其波谱特性,认为当p(Ⅲ)存在时可影响乙烯基类反应的的E、Z体比例。观察到Ⅱ_1-3化合物可能产生红移现象。     

两种捕食螨的生殖行为

作者在室内对东方钝绥螨和尼氏钝绥螨的生殖行为进行了研究。结果表明,交配之前,两种捕食螨的雄螨积极主动寻找雌螨并能辅帮雌后若螨蜕皮。正式交配的方位为雄性在下,雌性在上,雌雄腹面紧贴。交配的持续时间,东方钝绥螨长于尼氏钝绥螨。交配结束至产卵,雌螨需大量取食。产卵方     

在二维原子自洽场计算中的Gaussian函数展开方法

报告了在二维原子结构的自洽场计算中,单电子波函数向笛卡尔Gaussian函数展开的基本方法.推导了由s,p和d电子组成的闭壳层和开壳层电子组态的能量表达式,和二维的Hartree-Fock-Roothaan HFR方程,最后给出了二维原子自洽场计算的主要结果精度的讨论.     

多孔硅吸附染料分子的荧光增强效应

报道了利用多孔硅独特的表面特性,吸附染料分子后,使得染料的荧光得到很大的增强,并观察到了这种吸附过程中彼此间的能量转移过程。对染料的荧光增强机理及实验结果进行了讨论。     

Iodonium Initiators: Paving the Air-free Oxidation of Spiro-OMeTAD for Efficient and Stable Perovskite Solar Cells

To date, perovskite solar cells (pero-SCs) with doped 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (Spiro-OMeTAD) hole transporting layers (HTLs) have shown the highest recorded power conversion efficiencies (PCEs). However, their commercialization is still impeded by poor device stability owing to the hygroscopic lithium bis(trifluoromethanesulfonyl)imide and volatile 4-tert-butylpyridine dopants as well as time-consuming oxidation in air. In this study, we explored a series of single-component iodonium initiators with strong oxidability and different electron delocalization properties to precisely manipulate the oxidation states of Spiro-OMeTAD without air assistance, and the oxidation mechanism was clearly understood. Iodine (III) in the diphenyliodonium cation (IP⁺) can accept a single electron from Spiro-OMeTAD and forms Spiro-OMeTAD⋅⁺ owing to its strong oxidability. Moreover, because of the coordination of the strongly delocalized TFSI⁻ with Spiro-OMeTAD⋅⁺ in a stable radical complex, the resulting hole mobility was 30 times higher than that of pristine Spiro-OMeTAD. In addition, the IP-TFSI initiator facilitated the growth of a homogeneous and pinhole-free Spiro-OMeTAD film. The pero-SCs based on this oxidizing HTL showed excellent efficiencies of 25.16 % (certified: 24.85 % for 0.062-cm²) and 20.71 % for a 15.03-cm² module as well as remarkable overall stability.