排序方式: 共有46条查询结果,搜索用时 562 毫秒
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通过MK84125轧辊磨床在安钢1780mm热连轧生产线的成功投用,介绍了SINUMERIK840D数控系统在此磨床中的应用。分别从硬件的配置、软件的设计和NC的配置等几方面作了详细地阐述。经过近一年的使用,此磨床的控制精度和使用效率均达到了预期效果,完全满足生产需要。 相似文献
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针对电机叠频试验容易产生较大的有功功率低频波动,在弱电网条件下对电网造成污染导致电网上其他设备无法正常工作,提出了一种新型共直流母线的高压变频器。其整流侧采用移相变压器加二极管整流方案,通过电容串联建立高压直流母线,直流母线储存能量使其不回馈至电网,特别适用于弱电网下的电机叠频试验;逆变侧采用MMC逆变器(Modular Multilevel Converter),通过平衡控制策略达到模块电压平衡,环流抑制的效果。最后应用PSCAD/EMTDC搭建系统的仿真模型,证实了方案的可行性。 相似文献
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The homogenized response of metal matrix composites(MMC) is studied using strain gradient plasticity.The material model employed is a rate independent formulation of energetic strain gradient plasticity at the micro scale and conventional rate independent plasticity at the macro scale. Free energy inside the micro structure is included due to the elastic strains and plastic strain gradients. A unit cell containing a circular elastic fiber is analyzed under macroscopic simple shear in addition to transverse and longitudinal loading. The analyses are carried out under generalized plane strain condition. Micro-macro homogenization is performed observing the Hill-Mandel energy condition,and overall loading is considered such that the homogenized higher order terms vanish. The results highlight the intrinsic size-effects as well as the effect of fiber volume fraction on the overall response curves, plastic strain distributions and homogenized yield surfaces under different loading conditions. It is concluded that composites with smaller reinforcement size have larger initial yield surfaces and furthermore,they exhibit more kinematic hardening. 相似文献
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目的:通过比较准分子激光上皮下角膜磨镶术(LASEK)中预防性使用丝裂霉素C(MMC)与前弹力层下角膜磨镶术(SBK)治疗高度近视的临床疗效,评价两种手术的安全性和有效性.方法:回顾我院2010年1月至2011年6月行LASEK+ MMC及SBK的高度近视病例,观察两组术后裸眼视力(UCVA)、最佳矫正视力(BSCVA)、眼压、泪膜破裂时间(BUT)、角膜haze、角膜恢复情况及并发症等.结果:两组术后3月、6月、12月裸眼视力(UCVA)比较差异无统计学意义(P>0.05);两组患者术后最佳矫正视力(BSCVA)逐步稳定,特别是到术后3月、6月、12月两组BSCVA比较差异无明显统计学意义(P>0.05);术后一月开始两组间眼压及BUT比较差异均无明显统计学意义(P>0.05).LASEK+ MMC组术后可见1级及以下Haze,后渐减轻消退.SBK组6眼瓣下少量上皮植入.结论:LASEK+ MMC与SBK治疗高度近视相比,其安全性和有效性基本一致,并且没有高负压及角膜基质瓣的相关风险,仍然具有临床应用价值. 相似文献
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对MMC微裂纹分布的SEM照片连续地变换网格尺度,求得了MMC微裂纹分布的自相似分形维数,D=1.56.对大塑性变形后MMC分形重建后的σ(t)时间序列进行了非线性动力学过程分析,找到了相空间吸引子积分关联函数,确定了该MMC微裂纹演化存在吸引子,其分形关联维数值1.48与实验测得自相似分形维数值1.56接近。 相似文献
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《Journal of computational and graphical statistics》2013,22(4):937-955
Traditional tabular and graphical displays of results of simultaneous confidence intervals or hypothesis tests are deficient in several respects. Expanding on earlier work, we present new mean–mean multiple comparison graphs that succinctly and compactly display the results of traditional procedures for multiple comparisons of population means or linear contrasts involving means. The MMC plot can be used with unbalanced, multifactor designs with covariates. After reviewing the construction of these displays in the S language (S-Plus and R), we demonstrate their application to four multiple comparison scenarios. 相似文献