Progress in study on new piezoelectric ceramics with high Kt

The first paper¹ which was presented on ISAF'90 reported the high K_t performance of the PZT ceramics with the compositions situated near the ferroelectric(F) and antiferroelectric(AF) phase boundary. In this paper, other two systems PSZT and PLZT ceramics also on F-AF phase boundary were studied and the same character which shows the high K_t for the composition situated near the phase boundary has been examined. The highest K_t is up to 0.56. In case of favorable poling condition and additives, even higher value of K_t can be expected. The possible reasons for this character are discussed.     

Characteristics and mechanism of abrasive wear for thermoplastic polymers

Abrasive wear characteristics of polyethylene, polystyrene, polymethylmethacrylate, nylon 1010 and polyvinyl chloride were investigated. The volume relative wear resistance coefficients of these thermoplastic polymers are 18%-35% (hardened and low temperature tempered steel 45 was used as a comparing material), and have a linear correlation with square roots of their cohesive energy densities. The coefficients of linear correlation is 0.949. Wear morphologies were observed by scanning electron microscope (SRM). Main wear mechanism of the thermoplastic polymers includes brittle breaking for the hard and brittle polymers & plowing and fatiguing for the soft and tough ones.     

千床医院项目，科特赖克，比利时

在设计协议最终被签订之前，所有竞标者都需要对一系列具体的问题做出答复。     

公伯峡水电站发电厂房施工质量管理

公伯峡水电站发电厂房工程的施工质量管理采用：强化质量意识，健全制度，落实质量责任，技术措施先行，资源投入到位，严格工艺作风，强化现场控制等措施；通过全体职工的努力，工程施工质量一直保持在较高的水平。     

城市集中供热发展成就和发展展望

文章对我国城市集中供暖发展成就进行了总结并指出存在的问题。同时,对城市集中供暖的发展前景做了全面展望。     

Damping Performances of Carbon Nanotube Reinforced Cement Composite

Multi-walled carbon nanotubes (MWCNTs) were dispersed in an aqueous cement matrix using surfactant decoration, ultrasonic treatment, and, subsequently, intensive mixing to fabricate MWCNT/cement composites with six different MWCNT concentrations. Damping performances of these cured nanocomposites were studied with forced vibration testing, half-power bandwidth, and Morlet wavelet transform identification methods. The micro-crack bridging and interfacial “stick-slip” capacity of nanotubes among cement matrix contributes to balanced enhancement on structural damping capacity and flexural strength of the nanocomposite. With the addition of 2.0% nanotubes, the fundamental frequency, damping ratio, and flexural strength of the nanocomposite increases around 13 Hz, 60, and 32%, as compared to the reference, respectively.     

循环流化床锅炉床温控制神经网络动态建模

针对循环流化床锅炉燃烧过程非常复杂,难以建立精确的数学模型,提出基于神经网络的方法对床温控制系统进行建模,并对标准的BP网络进行了改进,引入系统动态性,较好地解决了床温调节的滞后性.根据所提的建模方法对某电厂已投产的一台循环流化床锅炉实际建模.计算结果表明,该模型对床温具有较好的预测能力,能够反映一次风、给煤量等操作量变化时循环流化床锅炉床温的动态特性,说明了该建模方法的可行性,对床温控制系统的研究有一定的实际意义和应用价值.     

广东海上丝绸之路博物馆

作为中外文化的探索者,海上丝绸之路不仅是贸易之路,更是对话之路,是古代东西方文明碰撞、交流之路。而有"海上敦煌"之称的宋代沉船"南海1号",则如远古绝唱,媲美西域丝路上的敦煌飞天壁画,记载着千年传奇。海上丝绸之路博物馆的概念正源于这种文化碰撞。它既需要满足沉船在馆     

高分子卷材屋面采用喷涂聚脲整体翻新的施工质量控制

上海通用汽车某车间与仓库屋面原为"彩钢板+岩棉保温层+高分子卷材"结构,经过近20年使用,屋面防水层开始失效,其维修采用了在原结构上喷涂聚脲防水层和辊涂脂肪族聚氨酯面漆的整体翻新方案。介绍了该施工项目实施过程中的质量控制要点,探讨了本项目"岩棉保温层+高分子卷材"组成的软基层不同于聚脲常规应用的刚性混凝土基层给施工质量控制和应用效果带来的新课题。