交流电动机的软起动技术

交流电动机的软起动是一种综合技术，它克服了发鼠笼异步机传统降压起动方式的许多缺点，通过采用软起动器可以实现交流电动机的软起动。本文介绍了交流电动机主要的几种软起动方式以及交流电动机软起动的特点，并指出了软起动器的其他一些应用。     

通风管道的综合评述

通风管道是通风系统的重要组成部分。本文介绍几种具有代表性的通风管道,并逐一进行技术经济比较,综合评述通风管道。指出应该重视通风管道的防火功能并确保其可长期使用,强调判定产品标准。完善设计资料和施工验收标准的重要性。     

钢框架梁、柱节点在反复循环荷载作用下的试验研究

为了研究高层钢框架结构梁、柱节点受力、变形性能及破坏特点,作者对五个梁、柱节点进行了反复循环荷载作用下的试验,本文介绍了试验情况,分析了试验结果,并对节点设计提出了一些建议。     

EFFECTS OF HEAT TREATMENT ON TENSILE PROPERTIES AND SHAPE MEMORY EFFECTS OF Ni-Ti-Nb ALLOY

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稠油水淹测井解释方法研究——以欢喜岭油田齐40块为例

本文以齐40块稠油油藏为研究对象,通过对区块地质资料、测井资料、测试资料、采油动态资料分析研究,总结出稠油水淹在不同测井曲线上的响应特征,分析了利用激发极化电位、地层测试、碳氧比测井技术特征,有效进行水淹层识别及解释,为稠油油藏开发中、后期的解释评价提供有效方法和手段。     

Segregation of P at Grain Boundary and Reverse Embrittlement of Cr-Mn-Si Steel

1.IntroductionPhosphorus causes remarkable decreaseof impact toughness due to its segregationon grain boundary[1,2].In this paper,theinfluence of P content on the reverse changeof P segregation and impact toughness ofmedium carbon Cr-Mn-Si steel at the samestrength level is reported.     

EVAPORATION BEHAVIOR OF COMPONENTS IN Ti-15-3 MELT DURING ISM PROCESS

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电子直线加速器的温度瞬态问题

文章运用逐步逼近法求出了电子直线加速器在升温过程中温度变化的较精确的解析解,并对一种U型水冷系统的加速器作了详细分析,从瞬态变化的角度讨论了这种水冷系统的性能,研讨了电子束能量变化及时间常数。结果与实验吻合。     

NUMERICAL SIMULATION OF ROCK BREAKING MECHANISM WITH HIGH-PRESSURE WATER JET

Based on the analysis of experimental results.the rock damage model and the damage coupling model suitable for the whole rock breaking process with water jet were established with continuous damage mechanics and micro damage mechanics, and the numerical method was developed with continuum mechanics and the FEM theory. The rock breaking mechanism with water jet was studied systematically with numerical simulation for the first time in the field of water-jet rock breaking. The numerical results agree with the experimental ones which shows that the presented method is reasonable and can reflect the reality of water-jet rock breaking. The conclusion can be applied in practice.     

Tandem Strip Mill’s Multi-parameter Coupling Dynamic Modeling Based on the Thickness Control

The rolling process is determined by the interaction of a number of different movements,during which the relative movement occurs between the vibrating roll system and the rolled piece,and the roll system’s vibration interacts with the strip’s deformation and rigid movement.So many parameters being involved leads to a complex mechanism of this coupling effect.Through testing and analyzing the vibration signals of the mill in the rolling process,the rolling mill’s coupled model is established with comprehensive consideration of the coupling interaction between the mill’s vertical vibration,its torsional vibration and the working roll’s horizontal vibration,and vibration characteristics of different forms of rolling mill’s vibration are analyzed under the coupling effect.With comprehensive attention to the relationship between the roll system,the moving strip and the rolling parameters’dynamic properties,and also from the strip thickness control point of view,further research is done on the coupling mechanism between the roll system’s movement and the moving strip’s characteristics in the rolling process.As a result,the law of inertial coupling and the stiffness coupling effect caused by different forms of the roll system’s vibration is determined and the existence of nonlinear characteristics caused by the elastic deformation of moving strip is also found.Furthermore,a multi-parameter coupling-dynamic model is established which takes the tandem strip mill as its research object by making a detailed kinematics analysis of the roll system and using the principle of virtual work.The coupling-dynamic model proposes the instruction to describe the roll system’s movement,and analyzes its dynamic response and working stability,and provides a theoretical basis for the realization of the strip thickness’dynamic control.