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本文以单相漏电保护器为例,阐明其几种错误接线的原因,并针对其不同的错误安装接线方法,提出了具体的改进措施。 相似文献
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Predicting the suitability and reliability of traits associated with juvenile growth as indirect selection criteria for choosing future broodstock requires accurate and repeatable estimates of genetic (co)variation for growth traits at different ages. We compared juvenile wet weight of black bream Acanthopagrus butcheri (Munro) at 6 months of age with wet weight, dressed weight, fillet yield and gonad weight in tagged individuals at 18 months of age, following 12 months of farm grow‐out. Fish survival and tag retention was high, and there was significant among‐family variation for all traits. The phenotypic correlations among wet weight, dressed weight and fillet yield at 18 months of age were very high (0.93–0.97) and similar to their genetic correlations (0.96). Importantly, the phenotypic correlations between wet weight at 6 months and wet weight, dressed weight and fillet yield at 18 months were high (0.63–0.65), and so too were their genetic correlations (0.66–0.73), indicating the potential for using wet weight in the hatchery as a selection criterion for improved weight and meat yield of fish at harvest. Gonad weight shared little or no phenotypic or genetic correlation with these other traits, suggesting that selection for faster growing fish will not affect fecundity or sexual maturation rate. It appears, however, that cultured black bream do become sexually mature more rapidly than wild fish, as 78% of all fish harvested in this study had developing or mature gonads, whereas less than 50% of fish in wild populations are reproductively mature by the same age. Precocious sexual development may lead to uncontrolled spawning in grow‐out ponds and a potential loss of selection gains. 相似文献
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本文通过分析、计算、现场实践.采用高强钢丝Φ_5~k,取代原Ⅰ、Ⅱ级钢筋制作大型屋面板,结果表明.提高了强度等级.工期、观感、降低了工程造价. 相似文献
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在5%NaCl溶液和5%NaCl+5%NaNO2溶液中,采用丝束电极技术测量了低砖、钢缝隙内、外的自腐蚀电位和电化学阻抗谱,研究了亚硝酸钠对低碳钢缝隙腐蚀的影响.结果表明,在5%NaCl溶液中,缝隙内的碳钢为阳极、缝隙外为阴极;随浸泡时间增加,腐蚀不均匀性增加.加入5%NaNO2后,缝隙内外的腐蚀电位都正移,电位差减小,碳钢的腐蚀速度显著降低.亚硝酸钠使碳钢表面形成致密氧化膜,有效抑制了碳钢的缝隙腐蚀. 相似文献
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张维 《西南大学学报(自然科学版)》2011,33(5)
随着半导体制造技术不断向微细化、高速、高密度方向发展,开发高精度、高效率、高可靠性的键合机是对封装设备制造业刻不容缓的要求.而深入认识、分析和改善键合机的机械结构与性能成为广大科研工作者面临的首要任务.利用虚拟机技术软件(ADAMS)建立了某键合机的动力学模型,并通过仿真验证了模型的正确性;利用有限元分析软件(PANTRAN)分析了该键合机中关键部件的物性特性对整机精度的影响,并得出初步的结论. 相似文献
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针对湖南电网研发的新型内嵌式地线地线新型直流融冰技术,提出地线直流融冰的所涉及的两个重要的参数(临界融冰电流和最大融冰电流)概念和计算方法。基于有限元法,以GJ-70电线为模型,建立3D热-电耦合仿真模型,仿真得出不同气候、温度条件下的临界融冰电流,以及地线正常运行所允许的最大电流,与试验人员得出的实验数据进行对比,进一步验证这种融冰技术的优越性,并为运行人员有效的融冰电流范围提供了参考依据。 相似文献
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Abstract A hatchery experiment was organised to find out if the high loss rate of coded wire tags, noticed in connection with an Arctic charr Salvelinus alpinus (L.) restocking programme, was size-dependent and also to test head moulds for future taggings. Six moulds made by Northwest Marine Technology Inc. and five moulds made at the Finnish Game and Fisheries Research Institute were used. A total of 100 charr were tagged with standard-length coded wire tags using each mould. One-summer old charr at tagging were held for 534 days and two-summer old charr for 320 days. The tag loss rate varied between 0% and 54% and was negatively related to the size of the charr at tagging. The high loss rate was connected with the poor alignment of some moulds, such that a large proportion of the tags were located in the nasal cavity instead of the nasal cartilage. Testing of the moulds and careful grading of the fish for tagging is emphasised, especially if Arctic charr smaller than 20 g in weight are to be tagged. 相似文献