Crystallographic structure- and texture-dependent fracture behavior of polycrystalline lead zirconate titanate ceramics

Journal of Electroceramics - The effect of crystallographic structure and texture on the fracture behavior of lead zirconate titanate (PZT) ceramics was investigated. PZT ceramics with Zr/Ti ratio...     

方面化构件软件动态演化支撑框架研究

随着用户需求和开放的网络计算环境的不断变化,软件复杂性与演化要求也随之不断增强。为适应基于关注点分离的方面化构件软件的动态演化需求,提出一种动态方面编织框架DWAC(Dynamic Weaving Framework for Aspectual Component-based Software)。该框架以方面化构件为基本单位,基于软件体系结构规约和系统实现,给出方面化构件增加、删除和修改的具体执行过程,并举例验证了其对面向方面的构件化软件动态演化的支持能力。     

特殊钢方坯连铸的发展

为满足成品棒材组织结构的要求，生产齿轮钢、高碳铬轴承钢等合金钢的连铸坯断面直径在350mm以上为宜，减少中间包钢水过热度，采用铸模电磁搅拌和低速浇铸等可防止柱状晶裂纹和减少中心疏松和偏析。     

Experimental validation of the gas-solid flow in the CFB riser

In this paper, an experimental study is performed to investigate the flow structure in a circulating fluidized bed (CFB). The typical core-annulus structure and small amount of back-mixing of particles near the wall of the riser were observed. The axial solid concentration distributions contain a dilute region towards the up-middle zone and a dense region near the bottom and the top exit zones. Furthermore, the solid concentration decreases with the increase of the superficial gas velocity, and increases with the increment of the circulation rate at the same height position. The total pressure drop of the main bed represents a linear relationship with the solid flux rate. In the dense phase zone, the solid concentration increases linearly with the augmentation of the solid flux, however, the change of the solid concentration is slight, even unchangeable at the up zones. In addition, based on the Energy-Minimization Multi-Scale (EMMS) method, a revised drag force model is proposed, which is coupled in the Eulerian two-fluid model for simulating the flow structure in the riser. Numerical results are consistent with the experimental data, which indicate the revised drag force model is very successful in simulating flow structure of the dense gas-solid two-phase flow.     

建筑形式与文化及非文化因素的关系

自现代主义建筑发展以来,影响建筑形式的因素众说纷纭,在现行建筑设计的过程中出现了各种试图将建筑形式的产生归于物质性和技术性的需求和制约的理论而忽略了文化背景的作用,而本文从文化因素以及非文化因素的角度,分别针对不同因素对建筑形式所产生的影响进行较深入的研究,从而确定文化因素对建筑的形式起首要的影响作用,而非文化因素起一定的限制和修正的作用。     

从国际经验看中国REIT发展模式的选择

当前我国房地产业迫切需要金融创新来为其发展输送血液,而房地产投资信托基金（Real Estate Investment Trust,REIT）作为一种新兴的房地产融资投资方式引起了业内人士的广泛关注。从亚洲各国的经验来看。发展REIT需要进行前瞻性制度设计。REIT制度主要包括了投资范围、主动交易能力、所有权结构以及借贷的限制四个方面的内容。从这四个方面借鉴国外／海外经验,结合中国实际形成适合中国国情的REIT制度是中国REIT发展成败的关键。本文借鉴世界各国的REITS的发展经验,从上述四个方面对中国REIT发展模式进行了探讨。     

一种新型附件自动夹紧机构的设计

文章介绍了一种结构紧凑，巧妙的机床附件夹紧机构，利用斜面机械的力放大原理，通过一块楔块的上下移动，推动拉钉，卡爪运动，实现附件的自动夹紧功能。     

直流（DC）电弧炉技术的发展动态

大电流可控硅整流电源的发展和炉底电极这一难题的解决促使直流（ＤＣ）电弧炉的迅速发展，近几年大部分新建电弧炉为ＤＣ炉并将一些已有的交流（ＡＣ）电弧炉改成ＤＣ电弧冶炼。