隐式极限状态方程可靠性研究

针对非线性隐式极限状态方程失效概率的计算,提出了精度更高的改进的均值二次法,并提出了与响应面法相结合的改进均值法,给出了所提方法的实现策略．具体算例表明,改进的均值二次法的精度较改进的均值一次法有明显提高,而改进均值法与响应面法结合后的精度改善更为明显,并且这种结合方法对响应面法的插值点位置不敏感,插值点在较大范围内变化均能得到稳健的高精度结果,从而说明所提方法的有效性．     

机械可靠性分析的高精度响应面法

通过对已有可靠性分析中的响应面法的研究,提出了一种高精度的响应面法,该方法通过迭代线性插值的策略,来保证确定响应面的抽样点比经典的响应面法更接近真实的极限状态方程,并且该方法通过序列线性插值的方法来控制抽样点与插值中心点的距离,保证随着插值中心点收敛于真实设计点,抽样点提供更多的关于设计点附近真实极限状态方程的信息,进而保证了收敛的响应面能够在设计点附近更好地拟合真实的极限状态方程,并得到高精度的失效概率计算结果．算例充分说明了所提方法的合理性与适用性．     

二氧化铅电极上氧发生反应的交流阻抗研究

测定了二氧化铅电极上氧发生反应的交流阻抗。用曲线拟合法解析组抗谱,求得了反应电阻R_t、吸附电阻R_a、双层电容C_d、吸附电容C_a的值。认为(OH)吸+H₂O→(O)吸+H₃O⁺+e^-是氧发生反应的控制步骤。讨论了C_d、C_a与OH^-离子浓度变化的关系。     

STRESS ANALYSIS IN CUBIC BORON NITRIDE FILMS BY X-RAY DIFFRACTION USING sin2 ψ METHOD

The boron nitride (BN) films containing cubic boron nitride (c-BN) and hexagonal boron nitride (h-BN) were prepared by radio frequency a ssisted thermal filament chemical vapor deposition. The stress and strain in BN films were investigated by X-ray diffraction analysis using the sin² ψ method. The results showed that both c-BN and h-BN in the same film have similar values of elastic strain, however, the compressive stress in c-BN is much greater than that in h-BN for the same film. Both stress and strain gradually decre ased with the increase of substrate temperature (T_s). The effective stress in the films calculated by the effective stress model increased with the increase of T_s. Furthermore, the dependence of effective stress in the films on T_s was also investigated.     

Strong spin frustration and magnetism in kagomé antiferromagnets LnCu3(OH)6Br3(Ln = Nd,Sm, and Eu)

To study the effects of lanthanide ions on the geometrically frustrated antiferromagnets and their magnetic properties,we grew high-quality single crystals of LnCu₃(OH)₆Br₃(Ln=Nd,Sm,and Eu) by hydrothermal method and studied their crystal structures and magnetic properties.The refinements of the crystal structure referred to the powder x-ray diffraction data show that LnCu₃(OH)₆Br₃ adopt a Kapellasite-type layer structure,which is...     

三维SPH程序及其在斜高速碰撞问题的应用

叙述了平滑粒子流体动力学(简称SPH)的基本概念,重新推导了所用的基本方程。介绍了具体计算格式、算法以及策略等。对所编制的程序作了一定的检验。对SPH方法中的人为粘性和人为热流的作用作了数值考查。还提供了一个三维高速碰撞现象的算例。最后指出尚存在的若干问题。     

NdCl3-FeCl3-石墨层间化合物的合成及结构模型

通过扫描电子显微镜(SEM)和能谱分析(EDS)研究了NdCl3-FeCl3-石墨层间化合物的微观形貌和元素分布. 结果表明, Nd元素插入石墨层间并形成了NdCl3-FeCl3-石墨层间化合物, 同时发现在石墨中Nd, Fe元素分布均匀. 在此实验基础上, 建立了稀土氯化物(RECl3)插入石墨的结构模型; 依据模型, 计算了RECl3-石墨层间化合物的特征层间距dPP值和间隔能指数, 计算值与实验值吻合较好, 其相对误差约为±2%; 并且发现TbCl3～LuCl3以(001)晶面插入石墨层间时, 其所需间隔能最小, 而LaCl3～GdCl3以(111)晶面为最优取向.     

8-羟基喹啉铝高分子薄膜的荧光特性

In this paper, the solid state. polymer thin films of 8-hydroxylquinoline aluminum (Alq3) were made by spinning coat method. The fluorescence efficiencies and the luminescence spectra of them were measured via the laser systems. Various experimental factors were considered and tested. It was found that the peak wavelength of the luminescence spectra of the Alq3 polymer films shifted and that the purity of the samples affected its fluorescence efficiencies: the fluorescence efficiencies of impure samples were about three-fourth of that of the purified ones; fluorescence efficiencies of Alq3 doped in PMMA polymer was higher than that doped in PC and PEO. Under certain conditions, transparent thin film 10 layers can be achieved. This kind of polymer thin film of Alq3 exhibits well fluorescence response, but also has good stability. Spin coat method can greatly reduce the technical requirements comparing with the vacuum plating method.     

新合成"哥腊"衍生试剂在甲醛的电分析化学中的研究

利用合成新的Ｇｉｒａｒｄ’ｓ试剂Ｔ,使之与甲醛反应生成电活性的产物,在银基汞膜电极上不原来检测甲醛。对影响这一测定方法的各种因素进行了研究,指出了最佳的实验条件,探讨了衍生反应和电极过程。应用这一方法测定浓度为５．０×１０＾－６ｍｏｌ／Ｌ的甲醛,重现性良好,其ＲＳＤ为３．０５％;对浓度为２．０１０＾－７ｍｏｌ／Ｌ的甲醛测定７次,其检测限为７．６×１０＾－８ｍｏｌ／Ｌ。     

Study on the second-order non-linear optical properties of 10-hydrocarbylacridones

Twenty 10-hydrocarbylacridones and 2-methylacridone, 1-hydroxyacridone were synthesized from acridone and characterized by mp, IR, UV, 1H NMR and MS. Using Nd:YAG as a laser source, the second-order harmonic generation (SHG) values of the acridone derivatives were measured in powder state as compared with urea powder. The results showed that the SHG values of some of 10-hydrocarbylacridones were higher than that of urea, while others were lower. Although the hydrocarbyl substituents (R) attached to nitrogen atom of acridone were different in size and electronegativity, they had a little effect on the SHG values of 10-hydrocarbylacridones. Substituents, such as methyl or hydroxy group connected to the phenyl ring, caused a little effect on the SHG values, too, compared with acridone. The ability of R to push electron toward the nitrogen atom or to pull electron from the nitrogen atom play an important role on the maximum wavelengthes of UV-visible absorption of acridone derivatives.