Error evaluation on experimental stress–strain curve obtained from tube bulging test

To get precise material data for advanced numerical modelling of tube hydroforming process, the tube bulging test is recommended. Stresses and strains in the tube cannot be evaluated easily and several approaches have been proposed. A review is proposed and points out their advantages and drawbacks.     

工程项目价款变更确定的原则与方法

从合同管理的角度,通过相关文件、案例分析,以严格遵守合同约定为原则,对合同中的适用项目、类似项目及没有的项目如何确定变更单价进行阐述。     

Effect of austenite microstructure and cooling rate on transformation characteristics in a low carbon Nb-V microalloyed steel

Deformation dilatometry has been used to simulate controlled hot rolling followed by cooling of a Nb-V low carbon steel, looking for conditions corresponding to wide austenite grain size distributions prior to transformation. Recrystallization and non-recrystallization deformation schedules were applied, followed by controlled cooling at rates from 0.1 °C/s to about 200 °C/s, and the corresponding continuous cooling transformation (CCT) diagrams were constructed. The resultant microstructures ranged from polygonal ferrite (PF) and pearlite (P) at slow cooling rates to bainitic ferrite (BF) accompanied by martensite (M) for fast cooling rates. Plastic deformation of the parent austenite accelerated both ferrite and bainite transformations, displacing the CCT curve to higher temperatures and shorter times. However, it was found that the accelerating effect of strain on bainite transformation weakened as the cooling rate diminished and the polygonal ferrite formation was enhanced. Moreover, it was found that plastic deformation had different effects on the refinement of the microstructure, depending on the cooling rate. An analysis of the microstructural heterogeneities that can impair toughness behavior has been done.     

焙烧多功能机组电缆拖链装置结构改进

分析焙烧多功能机组电缆拖链损坏原因,对比新、旧拖链装置结构,介绍改进后电缆拖链装置的优点。     

Carrying capacity for the electromagnetic suspension low-speed maglev train on the horizontal curve

Aiming at the lateral dislocation between the electromagnets and the rails on a horizontal curve,we investigated a single magnetic bogie of the maglev train in this paper.The magnetic levitation and guidance forces supplied by the suspension modules were deduced by the flux tube method.According to the dynamic equilibrium equations of the maglev train on the curved track with cant,several major factors that influence the carrying capacity were analyzed,and the formula of the carrying capacity was presented....     

采用电力载波模块对控制与保护开关的远程控制方案

介绍了电力载波的工作原理和一种基于KQ-100E的电力载波模块的应用方案。该系统取代了对控制与保护开关的远程控制而建立的专用控制信号传输通道,通过电力线就可对远程的控制与保护开关进行控制,节省了建立信号传输途径的费用,且从电力线上传输,提高了运行的可靠性。     

行星齿轮调速器在660MWe超临界空冷机组电动给水泵上的应用

针对给水泵不同驱动方式进行了简单比较,并着重从行星齿轮调速器的安装、调试、运行等方面介绍了行星齿轮调速器在蒲城电厂的使用情况,以期对同行有所帮助。     

保护用电流互感器饱和特性及其误差曲线研究

当电力系统发生故障时,一次电流比正常运行时的电流大几倍甚至几十倍,此时,保护用电流互感器的铁芯发生饱和,引起二次电流的畸变,从而使继电保护及其二次设备误动作。笔者对保护用电流互感器的误差与饱和特性进行了分析,介绍了实际工作中电流互感器误差曲线的绘制以及二次负载的校核方法,并提出了减小电流互感器误差的具体措施。     

2种均布比载绳索在大跨越档内过渡的解法

在现有的校验绳索上扬公式的基础上,提出虚拟杆塔法,推导出导线展放过程中2种均布比载绳索在大跨越档内过渡的数值解法。计算结果表明:当张力车出口张力保持恒定时,随着走板由高挂点侧向低挂点侧前行,绳索距江面的净距逐渐减小,导线放通时,绳索距江面的净距最小,故在配置关键的受力工器具时,建议以导线放通的状态作为计算依据。