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异型坯表面纵向微细裂纹研究 总被引:1,自引:0,他引:1
通过对异型坯腹板表面纵向微细裂纹宏观和显微特征的研究、保护渣性能检验、连铸二冷段铸坯表面温度测定和连铸设备的检查等,确定了异型坯腹板表面纵向微细裂纹的产生原因主要有结晶器保护渣性能波动大、连铸冷却工艺不合理、设备状况差及连铸操作不规范等.根据分析结果,同时结合异型坯连铸温度场、应力场数值模拟结果,提出了改进措施,使异型坯表面纵向裂纹发生率由10%下降到1.5%以下. 相似文献
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在SS4 0 0钢中进行了异型坯结晶器喂稀土丝工业试验 ,结果表明 :稀土在异型坯中的分布较均匀 ,稀土回收率为 81 .9%~ 87.1 % ,硫化物球化良好 ,提高了H型钢的低温冲击功 相似文献
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异型坯的浇铸是连续铸锭技术发展中出现的一枝奇葩,今日早已应用于生产中。最初出现于文献中的异型坯是苏联的120°夹角的角钢异型坯。实际用于工业生产中的连铸异型坯是在加拿大阿尔戈马钢厂1968年投产的H形异型坯。 相似文献
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本文综述了近年来国外方坯和异型坯连铸技术的发展情况;简要介绍了影响连铸方坯和异型坯质量的龟裂、气泡、内部裂纹、大型非金属夹杂物、中心偏析等几种主要缺陷的产生原因和防止措施;提出了发展我国方坯和异型坯连铸技术的几点看法和建议。 相似文献
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针对推标工作的指导思想、基本原则、基本步骤、具体做法、实施措施、工作速度,制定了有效办法,保证了推标工作的有序进行,克服了推标工作的随机育目性,在岗位操作标准制定时,打破以往三大进修规程的理论体系强,岗位操作弱的特点,抓典型、树样板、以点带面、以面推动全局。 相似文献
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The genetic algorithm (GA) is a general optimization technique that has some unique features that are especially suitable for structural engineering problems. This work uses a simple GA with elitism to find the optimum design of welded steel plate girder bridges. The objectives are to minimize the weight and the cost of the girders. Two types of plate-girder bridges are studied: a single-span bridge and a two-equal-span continuous bridge. Bridges with various span lengths, in increments of 20?ft, are investigated; results are tabulated, parametric studies are made, and meaningful conclusions are drawn. 相似文献
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中国锰系铁合金现状与发展 总被引:1,自引:0,他引:1
介绍了世界、中国锰系铁合金生产、消费和进出口情况,分析了锰系铁合金的需求发展与变化,预测了2003年中国锰系铁合金消费、出口与生产情况,展望了2005年中国锰系铁合金的消费需求,提出了发展建议。 相似文献
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客运专线用100米60kg/m重轨在焊轨厂拼焊后,当四面矫直时发生断裂。采用光学显微镜及扫描电镜(TEM)等方法对钢轨矫直时断裂原因进行了分析和研究。结果表明:钢轨断裂是由于距钢轨端部约100mm轨底边缘处存在凸台缺陷,此凸台在钢轨拼焊后进行除瘤时除瘤刀将其铲平,致使钢轨产生冷裂纹,进而在矫直时断裂。通过控制万能精轧上下辊的辊径差以及调整轧制线高度等方面,使钢轨出轧机时尽量保持平直,避免上翘或扣头,从而消除凸台缺陷的产生。 相似文献
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文中分析了资源-环境-经济一体化核算的研究现状及存在的问题,界定了矿产资源核算的内涵及其对象,论述了矿产资源定价的理论基础,探讨了矿产资源的各种定价方法及其优缺点,适用范围,建立相应的估价模型,并进行了实证分析,这项研究对我国的资源--环境-经济一体化核算的理论研究与实践进展具有重要的理论意义和现实意义。 相似文献
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Maurizio Venutelli 《Canadian Metallurgical Quarterly》2002,128(3):281-288
The unsteady motion of streams, with a free surface, has been described by a system of equations that were proposed by Saint-Venant in 1871. These are universally known as “Saint-Venant’s equations.” Weighted four-point implicit finite difference schemes are largely used for their numerical solution in the case of one-dimensional flow. For these models, stability, dissipation, and dispersion are first investigated by looking at the truncation error and then by using Fourier’s classic linear analysis. Variations of the space and time weighting coefficients, the Courant number, the Froude number, and the frictional resistance term are examined in this paper. In particular, instabilities are analyzed that are due to the progressive accumulation of dispersion errors, which are the consequence of an increasing frictional resistance term. However, in this case the numerical scheme requires a dissipation mechanism. Computational suggestions are given for this mechanism. 相似文献
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The problem of defining satisfaction and the difficulties in distinguishing interests and satisfactions are indicated. "Aside from the final, consummatory activity, satisfaction cannot be identified in terms of activities, as can interests… . Because opinion items are not as stable as interest items, it is doubtful that they can be as useful as interest items in predicting future behavior." 5 characteristics of interests are that they: are acquired, are persistent, vary in intensity, function in acceptance-rejection behavior, are indicated in readiness to act. "Interest tests are diagnostic because no two persons have acquired the same lists of activities nor are the activities classified in the same manner as liked or disliked. Moreover, people engaged in an occupation have to a marked degree similar interests, and so people in one occupation can be differentiated from members of other occupations." Major topics are: job satisfaction and job success; opinion, attitude, interest, and satisfaction; measurement of motivation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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仲钨酸铵结晶母液处理技术研究进展 总被引:1,自引:0,他引:1
概述了处理仲钨酸铵结晶母液的方法,介绍了几种较为合理有效的处理技术.阐述了这些方法的基本原理、工艺流程及应用效果,并展望了其今后的发展方向. 相似文献