显影机理的正电子化学研究

采用正电子湮没技术(PAT)研究了照相明胶中的自由体积空穴在显影过程中的作用机理,为显影过程中银丝的生成机理探讨了一个新的模式,并为感光科学的研究拓展了一种新的研究技术和手段.结果表明:明胶的自由体积空穴的平均尺寸在显影过程中基本保持不变.照相明胶的自由体积空穴在电子密度空间限制了银离子还原为银原子的过程,并使得银原子的沉积生长以丝状的形式进行.照相明胶大分子结构和组份的复杂性导致了其自由体积空穴在空间分布无序混乱性,可能正是这种无序混乱性导致了银丝缠绕成团的松散空间结构.     

基于均匀照明的LED反射器的设计

为了创造良好的视觉环境,并提高光能利用率,设计了一种基于均匀照明的LED反射器。之所以选用球面环形阵列LED光源,第一是为扩大照明范围,其次是为了避免面光源垂直照射产生光强过强而导致的眩晕。设计的反射器是运用划分网格的方法获得自由曲面面型,运用机械建模软件拟合曲面的实体模型,进行了照明仿真模拟及分析。结果表明,与传统的反光器相比,自由曲面的反射器能较大程度地利用光源发出的能量,而且均匀性也有很大的提高。     

NF/rGO/Co_3O_4/NiO电极的制备及在超级电容器中的应用

以泡沫镍(NF)为集流体,在优化好的电位、时间和浓度下,将还原氧化石墨烯(rGO)、金属氧化物(Co_3O_4和NiO)直接生长在泡沫镍上,制备了NF/rGO/Co_3O_4和NF/rGO/Co_3O_4/NiO电极.运用三电极体系对电极材料进行了恒流充放电(GCD)和交流阻抗(EIS)等测试.结果表明,复合材料NF/rGO/Co_3O_4/NiO具有较高的比容量(电流密度为2 A/g时,比容量达到1188.6 F/g)和较好的循环稳定性(2000周充放电后,稳定性达到80.5%).该材料还具有较高的倍率性能,当电流密度由2 A/g增至12 A/g时,倍率性能仍能达到75.7%.     

锑(Ⅲ)-邻苯三酚红-硫脲体系的极谱络合吸附波

在0.08 mol/L磷酸溶液中,锑(Ⅲ)-邻苯三酚红络合物产生一灵敏的吸附波,加入硫脲对峰高有增敏作用.峰电位在-0.30 V(vs.SCE)左右,峰高与锑浓度在4.1×10-10～2.1×10-6 mol/L间呈线性关系;检出限为2×10-10 mol/L.并进行了机理研究.方法应用于铜合金中锑的直接测定,结果满意.     

Analysis of a permeable interface crack in elastic dielectric/piezoelectric bimaterials

A permeable interface crack between elastic dielectric material and piezoelectric material is studied based on the extended Stroh’s formalism. Motivated by strong engineering demands to design new composite materials, the authors perform numerical analysis of interface crack tip singularities and the crack tip energy release rates for 35 types of dissimilar bimaterials, respectively, which are constructed by five kinds of elastic dielectric materials: Epoxy, Polymer, Al₂O₃, SiC, and Si₃N₄ and seven kinds of practical piezoelectric ceramics: PZT-4, BaTiO₃, PZT-5H, PZT-6B, PZT-7A, P-7, and PZT-PIC 151, respectively. The elastic dielectric material with much smaller permittivity than commercial piezoelectric ceramics is treated as a special transversely isotropic piezoelectric material with extremely small piezoelectricity. The present investigation shows that the structure of the singular field near the permeable interface crack tip consists of three singularities: and , which is quite different from that in the impermeable interface crack. It can be concluded that different far field loading cases have significant influence on the near-tip fracture behaviors of the permeable interface crack. Based on the present theoretical treatment and numerical analysis, the electric field induced crack growth is well explained, which provides a better understanding of the failure mechanism induced from interface crack growth in elastic dielectric/piezoelectric bimaterials. The project supported by the National Natural Science Foundation of China (10572110), Doctor Foundation of the Chinese Education Ministry and Doctorate Foundation of Xi’an Jiaotong University. The English text was polished by Yunming Chen.     

Fitting of the initialization function of fractional order systems

Nonlinear Dynamics - The initial value problem of fractional order systems is studied further in this paper. Firstly, a new concept is put forward and named as aberration phenomenon, which reflects...