Research on effects of hydrostatic pressure on the dielectric property of Pb(Zn<Subscript>1/3</Subscript>Nb<Subscript>2/3</Subscript>)O<Subscript>3−</Subscript>BaTiO<Subscript>3−</Subscript> PbTiO<Subscript>3</Subscript> relaxor ferroelectric ceramics

The dielectric properties of Pb(Zn1_1/3Nb_2/3)O₃₋ BaTiO₃₋PbTiO₃ relaxor ferroelectric ceramics near the rhombohedral and tetragonal phase boundary were investigated under hydrostatic pressure. It was found that hydrostatic pressure made their phase transition temperature T _c and the peak temperature T _m decreased, and the frequency dispersion and relaxor behavior enhanced. In these disorder systems of composite pervoskite structures, there appeared polar clusters or nanodomains. The unique physical characteristics, which made the relaxor behavior enhanced, is that the correlation length among these nanodomains decreases greatly with the pressure increasing.     

虚拟企业协作博弈中的双优策略

讨论了目前供应链中的虚拟企业的基本概念及出现的背景 ,介绍了动态联盟为基础的敏捷制造模式 ,从对偶线性规划和双层规划的思想出发 ,在虚拟企业中共赢策略的基础上提出双优的实施策略 ,论述了达到双优所需要的条件及可行性 ,最后讨论了供应链的敏捷性 .     

A sphingosine-1-phosphate receptor regulates cell migration during vertebrate heart development

Coordinated cell migration is essential in many fundamental biological processes including embryonic development, organogenesis, wound healing and the immune response. During organogenesis, groups of cells are directed to specific locations within the embryo. Here we show that the zebrafish miles apart (mil) mutation specifically affects the migration of the heart precursors to the midline. We found that mutant cells transplanted into a wild-type embryo migrate normally and that wild-type cells in a mutant embryo fail to migrate, suggesting that mil may be involved in generating an environment permissive for migration. We isolated mil by positional cloning and show that it encodes a member of the lysosphingolipid G-protein-coupled receptor family. We also show that sphingosine-1-phosphate is a ligand for Mil, and that it activates several downstream signalling events that are not activated by the mutant alleles. These data reveal a new role for lysosphingolipids in regulating cell migration during vertebrate development and provide the first molecular clues into the fusion of the bilateral heart primordia during organogenesis of the heart.     

MAS NMR studies of modified HY zeolites

The variations in structure and acidity on the internal and external surfaces of HY zeolites modified by MgO and SiO₂ have been studied by MAS NMR, together with the selective adsorption of perfluorotributyl-amine.²⁷Al and²⁹Si MAS NMR spectra revealed that the modifications led to significant changes of the framework owing to the migration of some non-framework Si and Al into the framework in the course of the modifications.¹H MAS NMR spectra showed that the modifications decreased the acidity of the zeolite surfaces. With an increasing of the loading of the oxides, the acidity of the surface decreased further. Both of the two kinds of Brönsted acidity of the MgO-modified HY zeolites decreased, particularly those in the supercages, while those of the SiO₂-modified HY zeolites decreased less, and this result is consistent with that of NH₃-TPD. From the adsorption of perfluorotributyl-amine, it was found that the acidic sites on the external surface of the HY zeolite can be completely covered by SiO₂ after being modified by the chemical liquid deposition (CLD) method.     

浅谈晋城市综合馆拱支承屋盖钢结构设计

论述了晋城市综合馆的工程概况及结构形式,分析了该工程结构设计、节点设计的亮点,并谈了自己的一些体会。     

浅谈晋城市综合馆拱支承屋盖钢结构设计

论述了晋城市综合馆的工程概况及结构形式，分析了该工程结构设计、节点设计的亮点，并谈了自己的一些体会。     

多编队对地攻防对抗多层决策分析仿真与研究

针对编队协同对地攻击的攻防对抗系统的强对抗性、多目标性和多层次性,建立了三层决策模型,由最高决策层根据战场情况调配编队方案,将中间决策层和最低决策层建立成为两级主从递阶互动决策模式,建立Nash-Stackelberg-Nash决策方法求解对抗条件下双方中间决策层和最低决策层的联合最优策略。仿真结果表明该三层决策模型应用于编队协同对地攻防对抗决策系统,其中间决策层和最低决策层构成的两层对策系统能够较好的解决两层对抗决策问题;同时,最高决策层有效的控制了编队支援方案,达到了较好的作战效果。三层决策系统为作战对抗提供了有力的战场分析依据。     

飞机空面精确打击武器火控系统精度仿真分析

空对面精确打击武器火控系统是现代作战飞机对付地面(或海面)目标的一种重要武器系统,在现代战争中有着无可替代的作用,其武器系统精度是关键技术指标。在分析精度分析评价指标体系的基础上,分析了影响飞机空面精确导弹武器火控系统的误差因素,确定了从飞机火控系统和导弹制导系统两个方面来分析武器火控系统精度误差链的分析方法。针对防区外空地电视遥控制导导弹火控系统进行精度分析与评估,利用蒙特卡罗法对防区外空地导弹火控系统进行了全武器精度分析仿真。其结果对评价空对面精确打击武器火控系统精度具有很好的工程应用价值。     

基于贝叶斯网络的编队对地攻击损伤评估研究

随着武器的高科技化、战场环境的复杂化、战斗节奏的加快,战斗损伤评估系统在现代战争中占有越来越重要的地位。针对战场战斗损伤评估信息的多样性、不确定性和模糊性,基于贝叶斯网络易于进行不确定性推理的优点,提出应用贝叶斯网络对对地攻击效果进行分析评价,建立了编队对地攻击损伤评估的贝叶斯网络模型,给出了基于贝叶斯网络的损伤评估的推理决策方法,并且对该方法进行了仿真分析。仿真实例表明,基于贝叶斯网络的损伤评估模型能够提高损伤评估的准确度,而且推理简单,易于实现。     

定轴旋转参照系中物体的运动规律

利用旋转非惯性系中的基本动力学方程,导出在定轴旋转参照系中物体运动的基本规律,以及物体动量守恒和动量矩守恒的条件.