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Search Results: 1 - 10 of 385782 matches for " 王宝华 "
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基于萤火虫算法的含DG配电网故障区段定位
Fault Location for Distribution Networks with DG Based on Firefly Algorithm
 [PDF]

岳凯旋,
Smart Grid (SG) , 2015, DOI: 10.12677/SG.2015.54024
Abstract:
萤火虫算法是一种新近提出的高级启发式算法,其具有概念简明、需要设置的参数少、收敛性好的优点。对配电网进行区域划分来降低解的维度并对萤火虫算法进行适当改进,提出了基于二进制萤火虫算法的含DG配电网故障定位方法。算例分析结果表明该方法在配电网发生单点以及多点故障,并伴有部分开关信息畸变情况下,均能够得到准确的结果,证明了其有效性。通过与粒子群算法进行对比,验证了萤火虫算法应用于配电网故障定位的快速性与可靠性。
Firefly algorithm is a new advanced heuristic algorithm, which has advantages of concise concept, few parameters need to be set and good astringency. By dividing the distribution network to reduce the solution’s dimension and improving the firefly algorithm, this paper puts forward a new method of fault location for distribution networks with DG based on binary firefly algorithm. Analysis of example shows that the proposed method is able to get accurate results when it is used to locate single fault or multiple faults in distribution networks accompanied by part of the switch under the distortion of information, which proves its effectiveness. Finally, the comparison results with particle swarm optimization algorithm testify its speed and reliability.
APF中完美谐波消除法的仿真与分析
Simulation and Analysis of the Perfect Harmonic Cancellation Method for APF
 [PDF]

孔昕,
Smart Grid (SG) , 2015, DOI: 10.12677/SG.2015.56034
Abstract:
谐波检测是有源电力滤波器(Active Power Filter, APF)的重要控制策略之一,当电网电压不平衡或畸变时,采用传统谐波检测方法会导致APF的谐波检测产生误差,最终的补偿效果变差。本文基于瞬时无功功率理论,推导了完美谐波消除法(Perfect Harmonic Cancellation, PHC)的补偿电流计算公式。PHC法检测谐波时提取了电网电压的正序基波分量,排除电网不平衡和畸变的影响,减小了谐波检测的误差。最后,本文对PHC法进行仿真验证,分别仿真了电网电压正常和电网电压畸变或畸变的情况,并与传统的p-q法和d-q法的补偿效果进行对比,证明了在电网电压不平衡或畸变的情况下,采用PHC法的APF具有更理想的补偿效果,验证了PHC法的正确性和优越性。
Harmonic detection is one of the most important control strategies in active power filter (APF). When the grid voltage is under distorted or unbalanced circumstance, the harmonic detection of APF causes error using the conventional harmonic detection methods, and the compensation effect is unsatisfactory. The compensating current equation of the perfect harmonic cancellation (PHC) is derived based on Instantaneous Reactive Power Theory in the paper. The PHC method uses positive sequence components of the grid voltage without the effect of distortion and unbalance while detecting harmonic. It makes for error reduction. Finally, the PHC method is simulated in the paper when the grid voltage is under normal circumstance or distorted and unbalanced circumstance. The simulation results verify that the APF using the PHC method has more satisfied compensation effect when the grid voltage is under distorted and unbalanced circumstance, and it proves that the PHC method is correct and superior.
沪港通对上海证券市场的影响分析
Analysis on the Influence of Shanghai-Hong Kong Stock Connect to Shanghai Stock Market
 [PDF]

, 钱伟民
Statistics and Applications (SA) , 2015, DOI: 10.12677/SA.2015.44026
Abstract: 沪港通对中国股市的影响一直倍受投资者关注,本文利用VAR模型的脉冲响应函数和方差分解、格兰杰因果检验、市场系统性风险结构的检验以及事件研究法研究沪港通对上海证券市场的影响,并对研究结果进行分析,得出结论沪港通对上海证券市场带来了一定的积极影响,但影响有限。
Investors have paid a lot of attention to the effect of Shanghai-Hong Kong Stock Connect to Chinese stock market. In this article, we will analyze the effect using Impulse Response Function and Va-riance Decompositions in a VAR model, Granger Causality Test, structure of market Systematic Risk and Event Study Method. We conclude that Shanghai-Hong Kong Stock Connect has some positive effect on Shanghai stock market, but the effect is limited.
铝钛双金属板KR曲线测定

材料工程 , 1997,
Abstract: 利用宽300mm、长/宽=1的横向CCT试样对国产铝钛(AI-Ti)双金属板做了常规力学性能测定,并按航标测定了KR曲线。经过柔度法和K值计算,分别测得了KRi和αi数据,确定了临界的Kc值。通过性能数据对比,研制的材料达到了进口料的性能要求。
含风电场的电网电能质量评估及监测装置整定方法
Grid Power Quality Assessment with Wind Farm and the Setting Method of Monitoring Device
 [PDF]

郑建华, 刘强, 杨鸯,
Smart Grid (SG) , 2012, DOI: 10.12677/SG.2012.23012
Abstract: 为保证风电场接入电网后系统的电能质量满足要求,需要对其进行电能质量评估和测试;同时在并网接入点装设电能质量监测装置。文中首先提出了对风电场电能质量监测装置进行整定所需的数据,进而针对某一实际风场,根据电能质量国标中的规定及计算方法对其接入点装设的监测装置各监测量进行整定,包括电压偏差和谐波等;并通过建模仿真额定运行及风速扰动下的电能质量情况,与整定值进行比较分析。结果表明,风速扰动下的风场电能质量若不能完全满足要求,则需进行相应的改善。
It is necessary to evaluate and test the power quality (PQ) of wind farm to safeguard it to meet the PQ re- quirements after its access to grid, so that PQ monitoring device is installed in the grid access point. The data required for the setting of PQ monitoring device is listed first, then an example of the setting method of monitoring parameters of PQ monitoring devices is provided based on the provision and calculation method in National Standards, including voltage deviation and harmonics, etc. Through simulation and analysis, results are compared with the setting values. Finally, if the PQ of wind farm can not satisfy the requirements when wind speed disturbance happens, then PQ im- provements should be taken.
河北省一九六五年甘薯增产技术总结
,
华北农学报 , 1966, DOI: 10.7668/hbnxb.1966.01.006
Abstract: 甘薯是我省主要高产粮食作物之一,面积大,分布广。种植面积占粮食耕地面积10%以上。广大平原及丘陵地区,皆普遍种植,近年来并有逐步向海拔和纬度更高地区发展的趋势。我省冬春雨少、夏秋雨多的自然特点,从整体上看,是基本符合甘薯生育前、后期耗水量少,中期耗水量多的要求的,因而常年产量比较稳定。但是,由于甘薯大部分在70%以上)种在早地,还存在着夏初干早不易保苗,夏末秋初出现洪涝或伏早,以及秋雨拮束早而形成“秋吊”等问题。特别是1965年夏秋正当甘薯伸蔓桔薯和薯块膨大时期,遇到多年少有的干早,严重影响甘薯增产。但是我省广大农民在党的正确镇导下,发展了敢于斗争、敢于胜利的革命精神,运用已有经验和科学技术,改进甘薯栽培措施,向自然灾害进行斗争,大部甘薯仍然获得了较好的收成,并且出现了不少大面积增产和高产典型。
中蒙干旱半干旱区降水异常的区域性差异及其年代际演变特征
The Spatial Variation in the Normal/Abnormal Precipitation over the Sina-Mongolia Arid/Semiarid Area and Its Decadal Transformation
 [PDF]

李万源, 吕世, 董治, 式功
Advances in Geosciences (AG) , 2012, DOI: 10.12677/ag.2012.21006
Abstract:

本文利用1951~2005年间中蒙干旱半干旱区322个气象测站的月降水量资料,借助聚类和小波等统计分析方法对该区各月降水异常的区域性差异及其年代际演变进行了较为详细的分析,主要揭露了以下事实:1) 同降水量的年变化特征相近,降水空间分布形势也表现出明显的年变化,由春季到夏季,多雨区不断扩展,少雨区不断退缩,直到各地降水量均达到最大,然后由秋季到冬季,少雨区不断扩展,多雨区则不断退缩,直到降水量恢复到全年的最小值,使得1年明显成为降水空间分布变化的一个周期。2) 通过聚类分析给出1951~2005年间各月降水异常的典型空间分布型及其出现的年份和频次,说明不同月份,即使属同一季节,其降水异常的典型空间分布型也有很大差异,不同月份典型空间分布型出现的年份也少有规律可循。3) 中蒙干旱半干旱区降水异常的区域性差异存在着明显的年代际演变。4) 通过小波分析给出一些主要区域逐月降水量年代际变化的主要周期性特征,结果表明同一区域,不同月份,即使属同一季节,其降水量变化的周期和位相也很不同。
Based on the monthly precipitaiton data during 1951 - 2005 for the selected 322 meteorological gauge stations over the Sina-Mongolia arid and semiarid area, the spatial variation in the normal/abnormal precipitation and its decadal transformation for each month have been analyzed in detail utilizing the statistical clustering and the wavelet analysis, disclosing the following facts: 1) Being similar to the monthly precipitation, the spatial distribution of the precipitation is also displaying its argular yearly variation apparently, with the wet area extending continuously and the arid area con-stracting from spring to summer, till the precipitation reaching the maximum at each station, and then, from autumn to winter, the arid area extending and the wet area constracting continuously, till the precipitaiton going back to the minimum at each place, so, one whole year is apparently a circulation of the spatial precipitaiton distribution. 2) The typical spatial distribution patterns of the abnormal monthly precipitation and their appearing years and frequencies during 1951 - 2005 have been found based on the statistical clustering analysis, showing that, the typical spatial distri-bution patterns and their appearing years and frequencies are all largely different from one month to another month even in the same season. 3) There is apparently a decadal transformation in the spatial variation of the normal/abnormal pre-cipitaiton over the Sina-Mongolia arid and semiarid area. 4) The major periods existing in the decadal variation of the precipitation for each calendar month and each major area have been found by the wavelet analysis, disclosing the pe-riodicity and the wave in the precipitaiton variation at some certain place will be different from one month to another even in the same season.

近半个世纪中国北方沙尘暴的空间分布和时间变化规律回顾
Spatial Distribution and Temporal Tendency of the Dust Storm Frequency in North and Northwest China for the Recent Nearly Half a Century
 [PDF]

李万元, 董治, 吕世, 式功, 奥银焕
Climate Change Research Letters (CCRL) , 2012, DOI: 10.12677/ccrl.2012.11001
Abstract: 特别是近10多年来,中外科学家对近半个世纪中国北方沙尘暴的地理分布和时间变化趋势作了大量工作,为了在借鉴前人成果的基础上更进一步把握现在和将来中国北方沙尘暴的发生、发展规律,本文就相关成果进行了详细的回顾、分析和总结:首先在气候意义上进一步阐明了我国沙尘暴发生频数、沙尘源区、爆发路径、传输路径、沉降区域等的地理分布状况及其形成的地表、气候和大气环流成因;然后总结了半个世纪以来我国沙尘暴的年际和年代际变化特征及其区域性差异,并就荒漠化、气候变化及环流演变三方面给出其可能的形成原因;最后提出几点沙尘暴预测和防治的建议。
A lot of efforts have been done on the geographic distribution and temporal variation trend of the dust storm frequency in North and Northwest China during the last half century, especially since 10 or so years before. In order to further understand the occurrence and development regulations for dust storms in China in the near and far future based on the previous successes, this paper has aimed to review, analyze and summarize in detail those relevant achievements obtained by inland and abroad scientists. Firstly, the climatic geographical distributions of the happening frequency, sand and dust sources, outbreak way, transport route and deposition areas of dust storms in China have been further elu-cidated with their causes such as surface conditions, climatic factors and atmospheric circulations. Secondly, the yearly and decadal variation characteristics of the dust storm frequency in China and their differences from area to area have been summarized for the last half century or so, focusing on the desertification land, climate change and atmospheric circulation modification in North and Northwest China to explain all the involved phenomena; Finally, some sugges-tions have been given on the prediction and restriction of dust storm in China.
浙江省淡水鱼类寄生单殖吸虫九新种
,淑霞
动物学研究 , 1983,
Abstract: 作者在整理1979—1981年于我省南部和东部各江河中收集的单殖吸虫过程中,发现九个新种现分述如下。文内量度以毫米为单位。 模式标本保存于杭州大学生物系动物教研室。 1.网状指环虫Dactylogyrus retiformis,新种(图1A.B.) 小型虫体,固着盘与体分界不明显,体长0.361—0.428,宽0.085—0.124;固着盘大小0.057—0.067×0.057—0.076;咽椭圆形,0.021—0.026×0.020—0.025。
Research on the Representation and Retrieval Algorithm of XML- based Facet Component
基于XML刻面构件描述与检索算法研究

鲁大营,,
计算机系统应用 , 2008,
Abstract: 随着构件库的规模的扩大以及构件的复杂性增加和语义性丰富,单一的软构件描述以及在此基础上的检索算法将很难再胜任整个构件库的检索任务.在基于刻面描述的软构件的基础上引入XML技术,来全面描述构件的静态属性、接口行为、组织分类和资源位置等信息,方便构件检索过程中信息的交换与处理,也便于与其他系统的互操作.并就此提出了一种新的构件检索方案,就算法的时间开销和空间开销进行分析,并利用试验数据说明算法的可行性和执行效率.
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