共查询到20条相似文献，搜索用时 62 毫秒
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介绍了导、地线覆冰的形成、分类及其影响因素。导、地线覆冰会导致杆塔荷载过大,导线弧垂变大,脱冰时导地线因为跳跃发生鞭击等,为输电线路设计及安全提供参考。 相似文献
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为了准确检测出输电线路覆冰厚度以保证系统安全稳定运行,提出一种基于输电线路覆冰图像轮廓拟合的覆冰厚度测量方法。该方法对覆冰图片中感兴趣区域进行高斯滤波、阈值分割等图像预处理;利用提取到的覆冰轮廓进行最小二乘法曲线拟合,应用奇异值分解（SVD）得出最小二乘法的解;通过求取拟合曲线轮廓内的最大长度,得出覆冰的最大像素厚度。根据导线的实际外径和测量出的覆冰前导线像素厚度,得出覆冰的实际厚度。通过模拟试验进行验证,结果表明测量值与实际值误差在2mm以内,测量精度较高。 相似文献
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本文对导线积雪、覆冰、脱落造成故障及跳闸线路的基本情况进行了分析,并给出了应对措施. 相似文献
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输电线路覆冰形成机理分析 总被引：3，自引：0，他引：3
输电线路覆冰是受微气象、微地形及温度、湿度、冷暖空气对流、环流以及风速风向等因素影响的综合物理现象。按冰的形成机理,覆冰可分为降水覆冰、云中覆冰、凝华覆冰,其中以降水覆冰产生的雨凇冰最危险。 相似文献
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针对高压输电线路的覆冰情况,提出了一种线路除冰机器人,该机器人由行走机构、越障机构、除冰工具、传动系统和摄像系统组成。机器人利用固定在前端的除冰砂轮对覆冰切割,而后除冰锤实现180°半圆形往复运动对剩余覆冰进行反复敲打清除;驱动轮采用半圆型结构,适应一定范围的线径,为机器人提供了稳定性。该机器人体积小,除冰效率高,可清除厚度为10~25 mm的覆冰。 相似文献
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为防止线路发生覆冰事故,首先在设计输电线路阶段应采用合适的抗冰设计措施;在设计阶段无法做到有效抗冰时,则应考虑采用合适的防冰和除冰技术措施。 相似文献
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为解决线路覆冰问题,通过对"弧垂"和"大气质量"监测的研究,提出通过对导线倾斜角进行实时监测来测量线路弧垂和覆冰的思路,和对线路走廊微气象参数进行实时监测的思路;提出了采用弧垂实时监测、线路图像实时监视和小型气象站相结合的综合方法来实时监测架空线路覆冰的解决方案。 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献