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合金化和球化工艺对超高碳钢组织和性能的影响 总被引:1,自引:0,他引:1
研究了合金化和球化工艺对超高碳钢组织和性能的影响。用扫描电子显微镜、透射电子显微镜和能谱仪观察了钢的组织形貌和元素分布。结果表明:在碳和铬含量相同的超高碳钢中加入同量的合金元素铝和硅时,铝可明显抑制锻造组织中网状或粗大的颗粒状碳化物的析出、细化珠光体组织和控制石墨形成。UHCS 213Si和UHCS 261Al钢经850 ℃×3 h球化退火处理后,都能得到较好的球化组织,其力学性能分别为:UHCS 213Si钢,Rm=1 033 MPa,Re=734 MPa,A=149%;UHCS 261Al钢,Rm=973 MPa,Re=677 MPa,A=182%。 相似文献
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本文将用数学和实验两种方法证实MC~2电缆不仅能保证特性阻抗变化不超出电缆技术规范。而且能保证在设计频率范围内电缆结构反射损耗最小。 相似文献
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多关系数据挖掘是近年来快速发展的重要的数据挖掘领域之一。传统的数据挖掘方法只能完成单一关系中的模式发现,多关系数据挖掘能够从复杂结构化数据中发现涉及多个关系的复杂模式。该文综述了多关系数据挖掘的研究状况。首先分析了多关系数据挖掘领域发生的原因和背景,其次总结了多关系数据挖掘研究的一般方法,然后介绍、分析了最具代表性的多关系数据挖掘算法。最后,总结了多关系数据挖掘将来发展需重点解决的问题和面临的挑战。 相似文献
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Adel M. AginaAuthor Vitae 《Computers in human behavior》2011,27(3):1129-1142
Because of several analytical and methodological critiques on the findings and contexts of children’s private speech (PS), self-regulation learning (SRL), and thinking aloud (TA), the present study was conducted to shed new light on the effect of the nonhuman’s/computer’s versus human’s/teacher’s intervention (C-Condition versus T-Condition) on young children’s speech use, SRL, and satisfaction during learning tasks. Four developmental measurements with novel criteria were used to measure: (1) speech analysis, (3) SRL as a function of task level selection, (3) SRL as a function of task precision, and (4) a friendly-chat questionnaire to measure children’s satisfaction. Two types of intervention (enacted versus verbal encouragement) were applied through computer-based learning environment and investigated by forty preschool children divided by their teachers between the two conditions equivalently. It was hypothesized that children who acted alone (C-Condition) were more PS productive, manifested higher SRL, task performance, and satisfaction. The results confirmed the hypothesis with no significant differential effect of the gender on performance, showed that the injudicious use of encouragement hindered the children’s regulation behavior, and proved that PS and TA elicitation were fully different. However, the results were not confirmed Vygotsky’s view and simultaneously not fully inline with Piaget’s view of self-regulation development. 相似文献
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Vocational degree earners represent a major portion of the work force in Taiwan. However, vocational education in Taiwan is highly competitive in that it must attract sufficient student enrollment in an environment with a rapidly increasing number of schools. In this context, many vocational students tend to have lower levels of academic achievement. Under such constraints but moving toward more practical orientation, the authors conducted a quasi-experiment to examine the effects of applying web-based self-regulated learning (SRL), web-based problem-based learning (PBL) with initiation, and their combination to help these low-achieving students be involved positively in their learning. Four classes in successive years, with a total of 177 third-year students, were divided into 2 (SRL vs. non-SRL) × 2 (PBL with initiation vs. PBL without initiation) experimental groups. Results were generally positive. The authors further discuss the implications for schools, particularly vocational schools, and for scholars and teachers concerned about e-learning. 相似文献
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金晓冬 《宁波工程学院学报》2013,25(1):10-15
学生自我评价是学生对自身知识,行为和理解的评价监控活动,是自主学习过程中不可或缺的一环。本文在学习能力自我评价相关理论研究的基础上,剖析学习者自我评价的元认知结构和认知过程,提出自我评价动态过程模型,讨论其在培养学生自我评价能力中的可行性以及对教学的启示。 相似文献
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