Search

Bi1.5ZnNb1.5O7 ceramics doped with Ca2+ in A-site and B-sites were prepared by the conventional solid state reaction method. The effect of Ca2+ doping on structure and dielectric properties has been investigated. The results showed that solid solubility of Ca2+ doping A-site, (Bi1.5−xCaxZn0.5)(Nb1.5Zn0.5)O7 (BCZN), was 0.25 mol, and B-site (Bi1.5Zn0.5)(Nb1.5−yCayZn0.5)O7 (BZNC) was 0.1 mol. With increasing Ca2+ content, the dielectric dispersion behavior of the BCZN and BZNC ceramics was qualitatively similar. The dielectric peak shifted to lower temperature in the case of A-sites doping (BCZN), while higher temperature in the case of B-sites doping (BZNC). In the same case of Ca2+ content, compared with A-site doping (BCZN), an decreasing dielectric relaxation for B-site doping (BZNC) occurs, which is attributed to the larger the bond valence sums (AVs) of O′ for B-site doped ceramics than A-site doped ceramics. The dielectric relaxation degree of BZN ceramics is closely related to the change from perfect octahedral to regular cube.

Bi1.5-δCaδZnNb1.5O6O′ (0≤δ≤0.3) ceramics samples were prepared by conventional solid-state reaction methods. The effect of Ca2+ doping on dielectric properties, crystal chemistry characteristics and relaxor behavior of α-BZN pyrochlore were investigated. The dielectric constant decreases with increasing Ca content. The bond valance calculations revealed the dielectric constant was proportional to bond valance sum of O′ anions. When δ = 0, the dielectric relaxation is attributed to hopping of A-site cations, however, when δ > 0, the declining relaxor behavior is closely related to the increasing A-O′ bond valance, the change from perfect octahedral to regular cube.

Herein, we propose a Spearman rank correlation based screening procedure for ultrahigh-dimensional data with censored response case. The proposed method is model-free without specifying any regression forms of predictors or response variable and is robust under the unknown monotone transformations of these response variable and predictors. The sure-screening and rank-consistency properties are established under some mild regularity conditions. Simulation studies demonstrate that the new screening method performs well in the presence of a heavy-tailed distribution, strongly dependent predictors or outliers and that offers superior performance over the existing nonparametric screening procedures. In particular, the new screening method still works well when a response variable is observed under a high censoring rate. An illustrative example is provided.

Twenty-first century is a rapid development century of science and technology, and will also be an era of big data. The enterprises should follow the big data era footsteps in the financial management in order to succeed in the fierce competition. Firstly, the article analyses the concept of the era of big data and then gives the applications of big data in the financial management optimization. Finally, the article puts forward several methods to improvethe level of usingbig data of

Fair value is the inevitable trend of the development of accounting measurement. China reintroduced fair value conceptand defined the scope of the application of it in 2006 to acceleratethe pr ogress of internationalization of China's accounting standards. This paper analyzes the problems in the application of fair value in accounting measures, and gives the corresponding measures in order to provide references for the related researchers.

This paper analyzed the trend of seed industry development in-depth and studied changes in quantity and quality of demands for seed industry talents. To adapt to “breeding, propagating and selling†integration and internationalized trend of seed industry, it stated that hierarchical training mode is an ideal mode for training outstanding seed industry talents. Finally, it elaborated specific objectives and requirements of the hierarchical training mode, i.e. undergraduate – master – doctor.