Structural, magnetic and dielectric properties of La2−xCaxNiO4+δ (x = 0, 0.1, 0.2, 0.3)

The synthesis, structural, magnetic and dielectric properties of a new type of high permittivity materials La_2−xCa_xNiO_4+δ (x = 0, 0.1, 0.2, 0.3) (abbreviated as LCNs) were reported. The samples were prepared through conventional solid state reaction route. Detailed structural information was retrieved by Rietveld refinement; normalized bond length and bond valence was calculated to investigate the compression/dilation effect of bonds and atoms in unit cell. It can be found all samples belong to K₂NiF₄ structure with space group I4/mmm. Doping of Ca in La₂NiO_4+δ shrinks the unit cell and makes the structure tend to become instable. Three types of (La, Ca)-O bonds, and two kinds of Ni-O bonds exist in LCNs. Along c axis there are alternately compressed (La,Ca)O₉ dodecahedra and lengthened NiO₆ octahedra. Room temperature magnetic measurements show that the materials are paramagnetic and Ca doping can improve the spontaneous magnetization. Furthermore, all samples have colossal values of the dielectric constant (?) at frequencies lower than 1 kHz. Interestingly, La_1.8Ca_0.2NiO_4+δ maintains its high permittivity at frequencies up to 1 MHz while La_1.7Ca_0.3NiO_4+δ has the lowest dielectric loss (tan δ). Calcium doping can effectively enhance ? and inhibit tan δ. The distortion of (La,Ca)O₉ dodecahedra can well explain their dielectric properties.     

Evaluating expectations about negative emotional states of aggressive boys using Bayesian model selection.

Researchers often have expectations about the research outcomes in regard to inequality constraints between, e.g., group means. Consider the example of researchers who investigated the effects of inducing a negative emotional state in aggressive boys. It was expected that highly aggressive boys would, on average, score higher on aggressive responses toward other peers than moderately aggressive boys, who would in turn score higher than nonaggressive boys. In most cases, null hypothesis testing is used to evaluate such hypotheses. We show, however, that hypotheses formulated using inequality constraints between the group means are generally not evaluated properly. The wrong hypotheses are tested, i.e.. the null hypothesis that group means are equal. In this article, we propose an innovative solution to these above-mentioned issues using Bayesian model selection, which we illustrate using a case study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

New optical material europium EDTA complex in polyvinyl pyrrolidone films with fluorescence enhanced by silver plasmons

In our search for efficient Luminescent Solar Concentrators (LSC) we have prepared polyvinyl pyrrolidone (PVP) films incorporated by ethylenediamine tetraacetic acid (EDTA) complex of europium and co-doped with silver nanoparticles (NPs). Steady state fluorescence was studied under weak and strong excitation. Dynamical study was performed by second harmonic of Nd laser. Under weak excitation the fluorescence of europium co-doped with silver plasmons increased by a factor of three and excited by continuous laser by a factor of 50. The lifetimes of films doped by the complex were 755 μs and co-doped with silver nanoparticles 946 μs. This is the first finding that the photon density accumulates the number of plasmons interacting with electronic states of europium increasing its transition probability resulting in the strong intensification of fluorescence. In dynamical measurements of lifetimes a single pulse does not provide enough energy to create such number of plasmons.     

隧道及地下工程岩体模型材料研究现状分析

归纳了当今国内外地质力学模型相似材料的研究现状,指出了常用相似材料的优缺点,并对测试相似材料力学特性的方法作了介绍,最终选取相似程度最好的模型材料,以更好的模拟实际条件。     

时滞LPV离散系统的稳定新准则及控制器设计

针对一类具有状态时滞的线性参数变化离散时间系统，提出了一种新的依赖于参数的Lyapunov稳定条件。该准则通过引入一个附加矩阵解除了系统矩阵与依赖于参数的Lyapunov函数之间的耦合而更易于控制系统的分析与综合。在此基础上设计了此类系统的状态反馈控制器，并将控制器存在的充分条件转化为参数线性矩阵不等式的解存在条件。数值仿真验证了所提出算法的可行性。     

大型空冷汽轮发电机冷却技术的现状与分析

本文分析了空冷技术当前受到重视的原因.通过对国内外空冷汽轮发电机发展状况的分析,指出了国内进一步研究空冷技术的必要性.通过对空冷汽轮发电机冷却原理的介绍,对空冷技术改进的可行性进行了分析.     

前苏联核电站用1000 MW四极汽轮发电机

介绍"电力"工厂20世纪80年代研制的TBB-1000-4型四极汽轮发电机的主要技术数据、结构以及厂内试验结果.图1表3     

Asynchronous distributed state estimation based on a continuous‐time stochastic model

In this paper, the problem of state estimation in an asynchronous distributed multi‐sensor estimation (ADE) system is considered. In such an ADE system, the state of a plant of interest is estimated by a group of local estimators. Each local estimator based, for example, on a Kalman filter, performs fusion of data from its local sensor and other (remote) processors to compute possibly best state estimates. In performing data fusion, however, two important issues need to be addressed, namely, the problem of asynchronism of local processors and the one of unknown correlation between asynchronous data in local processors. Consequently, there are two main contributions proposed in this paper. The first is a method to deal with asynchronous discrete‐time data based on a continuous‐time stochastic plant model. The second contribution is an asynchronous distributed data‐fusion algorithm. Simulated experiments illustrate the effectiveness of the proposed ADE approach. Copyright © 2011 John Wiley & Sons, Ltd.     

纯方位目标跟踪极坐标模型的状态空间变换方法

在纯方位目标跟踪定位研究领域里,采用极坐标模型,可以实现可观测状态和不可观测状态的分离,但非线性的系统方程使算法的具体实现非常困难。利用状态空间的变换,可避免直接计算非线性函数雅可比矩阵的值,减小了计算量,提高了滤波稳定性。     

Anion Acceptors Dioxaborinane Contained in Solid State Polymer Electrolyte: Preparation,Characterization, and DFT Calculations

A novel dioxaborinane‐contained solid state polymer electrolyte poly((2‐phenyl‐1, 3, 2‐dioxaborolane‐4‐yl) methyl methacrylate) (P(GMMA‐PBA)) for symmetrical capacitors (SCs) is prepared through solution casting technique. Due to the effect of electron withdrawing of dioxaborinane groups and irregular distributed porous microstructures, the solid polymer electrolyte (SPE) exhibits an optimal ionic conductivity of 0.5 mS cm^?1 at ambient conditions. The electronic properties of dioxaborinane groups and their interaction with anions of electrolyte salts are further studied with density functional theory calculations. SCs fabricated with this polymer film as electrolyte and reduced graphene oxide as electrodes provide a broad potential window of 2.5 V. The energy density of this capacitor ups to 22.49 Wh kg^?1 with a power density of 6.34 kW kg^?1 at 5 A g^?1. After 3000 charge–discharge cycles, the capacitance of the symmetrical SPE capacitor maintains 90% of its initial values.