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But in practical operating, overvoltage caused by reignition of the vacuum switching device frequently appears, and it result in damage of the capacitor bank or the switchgear itself. Ensuring the switchgear against reignition and installing a protective device are two main approaches to avoid the phenomenon. In this paper, a study on overvoltage caused by reignition due to capacitor bank switching with the vacuum switching device and its preventive measures are carried out. The main work which has been done and researches are as follows: 1. The producing mechanism of overvoltage and its influence factor are analyzed. It is pointed out that single-phase reignition is the main reason for damage of the switchgear and two-phase reignition is the main reason for damage of the capacitor bank,so overvoltage of single-phase reignition and two-phase reignition are the emphases of prevention. 2. Analysis of the special working condition of the operating switch for capacitor bank is carried out. It indicates that the vacuum switching device is difficult to realize no-reignition under this operation condition, so it is more practical to adopt protection devices. 3. Analyses of protection effect of RC and MOA and their shortages are carried out. It shows that the two methods can only restrain effectively overvoltage caused by single-phase reignition, and they cannot protect the capacitor bank when reignition of two-phase occurs. 4. The operation principle of G-R damping device is analyzed and discussed emphatically.
本文针对真空开关投切电容器组时因重燃而产生的过电压及其防治措施进行了研究,所开展的主要工作和研究结果如下: 1、对过电压的产生机理及其影响因素进行了分析,指出单相重燃是导致开关设备损坏的主要原因,而两相重燃则是导致电容器组损坏的主要原因,因此单相重燃和两相重燃过电压是防护的重点; 2、对电容器组操作开关的特殊运行条件进行了分析,指出在这种运行条件真空开关难于实现不重燃,因此采用保护装置更具有现实意义; 3、对RC与MOA的保护效果和存在的不足进行了分析,指出这两种方法均只能有效抑制单相重燃过电压,而不能在发生两相重燃时保护电容器组; 4、重点对G-R阻尼装置的工作原理进行了分析和讨论,指出该装置接入后线路中将会出现两种频率的高频振荡,而电容器组上的过电压是由这两种振荡共同决定的; 5、根据对上述两种振荡的分析指出存在一个最佳电阻值使得过电压最低,并提出了电容器组电压和最佳电阻值的近似求解方法; 6、使用电气暂态分析软件MATLAB对G-R装置的保护效果进行了仿真计算,证实该装置确实可以有效抑制重燃时的电容器组过电压; 7、根据仿真与近似计算结果的偏差提出了近似计算的修正方法,经过修正后的过电压计算结果与仿真结果吻合较好; 8、对G-R装置中放电装置G与阻尼电阻R的要求进行了分析,指出采用编织电阻和真空间隙可能是最佳选择。
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It includes seven parts: PartⅠ, as a preface, includes the start-point, purpose, significance of this research and summarizes the relatable study in domestic and foreign; PartⅡ, the design elements, mainly including describes the research method, content, ideas, creativity, feasibility of this research, and the basic characteristics of the sample and related concepts defined and operation.
本研究主要分为六个部分:第一部分为绪论,主要阐述了本研究的出发点、目的、意义以及国内外相关研究的进展情况;第二部分主要是本研究设计内容,包括研究方法、研究内容和思路,研究的创新性和可行性,以及样本基本特征和相关概念的界定和操作化的阐述;第三部分至第五部分是论文主体。
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Resultantly, the individual warm/cold events in ENSO cycle appear to be partially locked to the annual cycle, and also exhibit obvious irregularity both in amplitude and in lasting time.
本文第四章研制设计了一包含海洋表面边界层和大气辐合反馈过程的热带太平洋海气耦合异常模式,进而利用该模式对ENSO循环进行了较为真实的模拟,通过对模式ENSO循环的演变特征及其形成机制的细致分析,建立了-ENSO循环的非线性分析模式,并提出了ENSO循环形成的一种更为客观的理论,指出:1)和观测事实类似,模式ENSO循环确实涉及了三种主要时间尺度过程即LF、QB和AC,其中LF为3-4年主周期振荡,QB占总方差10~20%;2)ENSO循环的正反馈机制是不稳定海气相互作用过程,且这一不稳定过程的发展在暖态中明显强于冷态;3)ENSO循环的负反馈机制在冷暖态中表现不同,在冷态消亡过程中,这种负反馈过程主要表现为西边界反射产生的时滞效应,但在暖态消亡过程中不存在类似的时滞效应,其负反馈过程主要表现为在海气耦合不稳定充分发展时伴随的赤道两侧冷水上翻过程的加强以及非线性过程的衰减作用抑制了不稳定的发展并最终使得系统回复至冷态;4)ENSO循环的3-4年主周期振荡是一非线性系统的自激振荡现象,其形成是线性系统的本征模即准两年振荡通过非线性机制产生的周期加倍所致,其中&单向性&大气辐合反馈加热过程对其形成至关重要;5)虽然年循环过程对ENSO循环形成没有本质影响,但它可明显影响ENSO循环的具体振幅和位相,使得ENSO对季节循环有明显的&锁相&特征,并且也使得ENSO循环在振幅大小和时间长短方面呈现出明显的不规则性。
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The main conclusions are: Mexican hat wavelet is anisotropic one, and it could detect pointlike singularities very efficiently. Morlet and Cauchy wavelet could be used to detect specific directions, and Cauchy wavelet has better direction selectivity than Morlet one. And it has been used to separate the wave field of Ricker. Its results are basically accurate and computation is more efficient.
主要结论有:Mexcian帽小波是各向同性的,主要用来检测点状信号分量,Morlet小波和Cauchy小波主要用来检测方向信号分量,并且Cauchy小波比Morlet小波的方向性要好,检测结果的分辨率要高;利用二维连续小波反变换,以合成的Ricker子波为模拟信号为例进行波场分离,提高了运算效率,实验结果基本上比较准确,还需要实际地震信号的进一步验证。
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Towers and " beautiful valley " sightseeing areas.The north of Gznzi Prefecture is perfect for exploring Kham culture in depth . Not-to-be-missed sights sights include; Dege Scripture Printing lamasery , a rare treasure of Tibetan culture; King Gesar's birthplace in Ahxu grassland; the Sun Tribe and many famous monasteries of the five main Tibetan Buddhist sects.In the South is Shangri-La, a fantastic ecological travel region. Highlights include: Daocheng Yading nature reserve; the West sun vally of china ,Shambala Xiangcheng;Cuopu Lake-the first lake of Eastern Tibet; and Genie Holy Mountain.
东部,康定风情生态观光渡假旅游区,四川省三大精品环线之一---西环线贯穿其间,主要是贡嘎山国家风景名胜区,&藏房艺术之乡&道孚,千碉之乡美人谷;北部,康巴文化旅游区,主要又&雪域文化宝库&德格印经院,格萨尔王诞生地阿须草原,太阳部落等荟萃了五大教派名寺;南部,香格里拉生态精品旅游区,主要有稻城亚丁,中国西部太阳谷,香巴拉乡城,&藏东第一圣湖&措普湖、格聂神山、郭岗顶。。。。。。
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The apoptosis of 80 mg/kg ﹒ d group was mainly located in spermatogenous cell and first spermatocyte; the apoptosis of 120 mg/kg ﹒ d group was mainly located in spermatogenous cell , first spermatocyte and spermatocyte of the second order; the apoptosis of 240 mg/kg ﹒ d group was mainly located in spermatogenous cell and first spermatocytes, and seemingly, the apoptosis located in first spermatocyte was dominant; whereas the apoptosis of 480 mg/kg ﹒ d group was located in all levels spermatogenic cells.
结果表明:各试验组小鼠生精细胞凋亡指数随着浓度的升高有增加的趋势,而且与对照组差异显著( P <0.05或 P <0.01)。80 mg/kg · d 组凋亡细胞主要定位于精原细胞和初级精母细胞;120 mg/kg · d 组凋亡细胞主要定位于精原细胞、初级精母细胞和次级精母细胞;240 mg/kg · d 组凋亡细胞主要定位于精原细胞、初级精母细胞,以初级精母细胞为最多;而480 mg/kg · d 组凋亡细胞定位于各级生精细胞。
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Results During Chinese reading, the activated areas included bilateral motor area, subfrontal gyri, superior temporal gyri, and superior parietal lobule; during English reading, the activated areas were left motor area, left subfrontal gyrus, left supra temporal gyrus, left insula and bilateral cerebellum; and the Nepali task demonstrated the activation of left anterior central gyms, superior frontal gyms, superior temporal gyms.
结果:除负责视觉活动的枕叶为双侧激活,汉语任务主要激活了双侧额上回、额中回、中央前回、顶上小叶、颞上回及颞中回;英语任务主要激活了左侧额上回、中央前回、顶上小叶、颞上回、颞下回及小脑;尼泊尔语任务主要激活了左侧中央前回、额上回及颞上回。
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The Es formation was divided into seven third order sequences based on the seismic, drilling and logging data, and plans deposition system plane distribution maps of different time were plotted by dominance phase principle. The lower Es4 is flood-overlake facies mainly; the upper Es4 is meandering stream and braided river delta deposition above the shore shallow lake background; in the Es3 period, the south mainly developed braided river, meandering stream delta, the northeast area main developed meandering stream delta, the middle area mainly developed semi-deep lakean d deep lake sediments. From lower Es3 to upper Es3, the delta scale gradually increased and the depositional area gradually moved to the east and the southeast; the Es2 period was dominated by shore-shallow lake sediments and widely developed braided river delta and delta deposits; the Es1 period was dominated by shore-shallow lake shoal deposits, and in the south developed meandering stream and braided river delta deposits.The lothological traps of the Shahejie group are mainly fluxoturbidite and stratum lateral pinch-out, and its formation and the distribution of the lothological trap were controlled mainly by the basin structure characteristic, palaeogeomorphology and tectonic activity and so on. It had a beneficial geological condition to develope sublacustrine slump turbidite fans in Jishan, Jiangjiadian and Wawu.
利用地震、钻井、测井等资料,将古近系沙河街组划分出7个三级层序,通过剖面沉积学分析,以优势相原则绘制不同时期各亚段沉积体系平面分布图:沙四下总体以洪水-漫湖沉积为特征,沙四上沉积时期是在滨浅湖背景之上发育了曲流河三角洲和辫状河三角洲沉积;沙三段沉积时期南部主要发育辫状河、曲流河三角洲,西北部地区发育曲流河三角洲,中部地区主要为深湖—半深湖沉积;由沙三下至沙三上,西北部三角洲规模逐渐增大,沉积范围逐渐向东、东南方向推进;沙二段沉积时期为滨浅湖沉积,在背景之上广泛发育了辫状河三角洲和三角洲沉积;沙一段以滨浅湖滩坝沉积为特征,南部发育了曲流河三角洲和辫状河三角洲沉积;沉积地层中的岩性圈闭以滑塌浊积岩岩性圈闭和地层侧向尖灭型岩性圈闭为主,其形成和分布主要受盆地结构、沉积古地貌和构造活动强度等因素控制,北部基山、南部江家店和瓦屋具有发育滑塌浊积扇的良好地质条件。
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Firstly, virtual water contents were calculated for primary farm products and for virtual water consumption of residents in Jiangxi Province in 2000. The virtual water contents of crops was 284.81×108 m^3, and the virtual water consumption of rural residents 670.17 m^3. Then, based on the predecessors' study results, the difference of virtual water con- sumption of residents between Jiangxi Province and Shanxi Province was analyzed.
首先计算2000年江西省主要农产品虚拟水含量和城乡居民生活消费虚拟水含量,得出粮食作物的虚拟水含量为284.81×108立方公尺;城镇居民人均消费主要产品的虚拟水量为768.27立方公尺;农村居民人均消费主要产品的虚拟水含量为670.17立方公尺。
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Theoria is mainly a mental activity to know universal principles of nature, praxis is mainly an action to seek ethic virtues and political justice, and poiesis is mainly labor to produce materials for human life.
其中,理论主要指求知自然的普遍原理的思想活动,实践主要指追求伦理德性和政治公正的行动,创制主要指生产生活资料的劳动。
- 推荐网络例句
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The split between the two groups can hardly be papered over.
这两个团体间的分歧难以掩饰。
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This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.
这种做法不仅鼓励了更多的反应,而且减少跟风的可能性。
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The new PS20 solar power tower collected sunlight through mirrors known as "heliostats" to produce steam that is converted into electricity by a turbine in Sanlucar la Mayor, Spain, Wednesday.
聚光:照片上是建在西班牙桑路卡拉马尤城的一座新型PS20塔式太阳能电站。被称为&日光反射装置&的镜子将太阳光反射到主塔,然后用聚集的热量产生蒸汽进而通过涡轮机转化为电力