变压器油中呋喃系列化合物检测方法研究

介绍了一种采用等度洗脱方式进行变压器油中呋喃系列化合物检测的液相色谱法。详细叙述了如何进行色谱分离条件的优化,实现各组分的良好分离和检测。采用该方法,即使色谱仪为一元泵配置,也可完成呋喃系列化合物的检测。     

基于Excel VBA实现普通高中毕业证书打印系统

介绍如何使用Excel VBA 开发毕业证书打印系统,并给出详细代码.     

Recrystallization Behavior of Deformed Austenite in High Strength Microalloyed Pipeline Steel

 Using methods of single hit hot compression and stress relaxation after deformation on a Gleeble 1500D thermomechanical simulator, the curves of flow stress and stress relaxation, the microstructure and the recrystallization behavior of Nb V Ti high strength microalloyed low carbon pipeline steel were studied, and the influence of the thermomechanical treatment parameters on dynamic and static recrystallization of the steel was investigated. It was found that microalloying elements improved the deformation activation energy and produced a retardation of the recrystallization due to the solid solution and precipitation pinning. The deformation conditions such as deformation temperature, strain, and strain rate influenced the recrystallization kinetics and the microstructure respectively. Equations obtained can be used to valuate and predict the dynamic and static recrystallizations.     

Mechanically strong conducting hydrogels with special double-network structure

Mechanically strong conducting hydrogels composed of poly(acrylamide) (PAAm) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) have been synthesized through the construction of a special double-network (sDN) structure. The novelty of the sDN hydrogels lies in the introduction of PEDOT-PSS semi-interpenetrating polymer network (semi-IPN) hydrogel as the second network. Based on the experimental results and the double-network theory, an additional strengthening effect resulting from the formation of the PEDOT clusters in a three-step fracture process is proposed. The applicability of as-prepared PAAm/PEDOT-PSS sDN hydrogels in electromechanical actuators is also briefly discussed.     

巯基乙酰壳聚糖制备条件的优化及其絮凝性能

通过正交试验研究了巯基乙酰壳聚糖(MAC)的最佳制备条件,探讨了MAC捕集重金属离子的机理,研究了pH、浊度对MAC除铜效果的影响,并对MAC去除重金属离子Cu2+、Cd2+、Ni2+的效果进行了对比。结果表明:制备MAC的最佳条件为:m(壳聚糖)∶m(巯基乙酸)为1∶2,pH为5.0,反应时间为3.5 h;水样浊度对铜离子的去除有促进作用;优化条件下,MAC对重金属离子的选择性顺序为Cd2+Cu2+Ni2+。     

中外建筑比较的意义

<正>中外建筑比较是一个视野宏大深远的研究领域,其价值可以归结为两点:第一是比较的意义,应是在关注对象与具可比性的其他对象之间,通过相互映照反衬,更加看清前者自身的特性所在;第二是比     

钢筋与混凝土粘结力及其施工措施

介绍了粘结力的定义和组成,并分析了各类型钢筋的粘结力及影响钢筋粘结强度的因素,在此基础上,阐述了保证可靠粘结力的施工措施,从而保证混凝土结构体系的安全性、适用性及耐久性。     

四角切圆煤粉炉内温度分布的数值预测

采用数值模拟的方法以吉林热电厂1台670t/h四角切圆煤粉炉为研究对象,对炉内的温度分布进行了详细的数值预测,通过计算结果与实验测试值的比较,证明所采用的计算方法的可行性和计算结果的合理性。     

蓄电池故障对110kV变电站安全运行影响分析探讨

以事故预想的形式,重点指出并列运行110 kV内桥接线变电站在蓄电池故障开路情况下,发生低压侧线路近区故障时可能引起线路保护越级跳闸。原因是由于全站直流系统输出电压达不到继电保护及自动装置的最低动作电压要求而引起站内保护拒动,只能靠电源侧变电站110 kV线路保护动作切除故障,这将导致110 kV变电站全停。通过对该安全隐患的分析,提出了三种相应的改进措施,能有效提高供电可靠性,避免全停事故的发生。     

PMSM无位置传感器矢量控制的滑模观测器设计

永磁同步电机无传感器控制技术不但能够降低系统成本,而且能够增加系统的可靠性。为实现永磁同步电机无位置传感器的运行,本文提出了一种基于自适应滑模观测器的非线性速度/角度估算方法,基于永磁同步电机的数学模型,根据实测电流与估算电流之间的误差构成滑模面,将反电动势估算值反馈引入电机电流观测中。为简化调速系统的硬件结构,我公司设计了一个截止频率可随转速变化的低通滤波器。