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强流电子束阻抗对相对论速调管放大器注入及群聚特性的影响分析 被引量:1
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作者 张泽海 舒挺 +1 位作者 张军 戚祖敏 《物理学报》 SCIE EI CAS CSCD 北大核心 2013年第4期62-68,共7页
通过数值计算及粒子模拟程序,分析了强流电子束阻抗、电压及电流特性对相对论速调管放大器(relativistic klystron amplifier,RKA)中束流调制、群聚特性的影响,其中粒子模拟程序中采用束发射方式以精确控制电子束的阻抗.结果表明,低阻... 通过数值计算及粒子模拟程序,分析了强流电子束阻抗、电压及电流特性对相对论速调管放大器(relativistic klystron amplifier,RKA)中束流调制、群聚特性的影响,其中粒子模拟程序中采用束发射方式以精确控制电子束的阻抗.结果表明,低阻抗电子束有利于减小群聚距离,缩短RKA器件的整体长度,不利于注入微波对电子束的调制,而高阻抗电子束情况正好相反.在电子束阻抗不变时,增加电子束加速电压类似于增大电子束阻抗的情况.另外,用粒子模拟方法确定了不同阻抗电子束对特定输入腔的电子负载电导,从而可以得到不同阻抗的强流电子束对种子源功率水平的需求以及对输入腔外观品质因数的要求. 展开更多
关键词 相对论速调管放大器 电子束阻抗 群聚距离 输入调制
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Self-organizing dual clustering considering spatial analysis and hybrid distance measures 被引量:10
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作者 JIAO LiMin LIU YaoLin ZOU Bin 《Science China Earth Sciences》 SCIE EI CAS 2011年第8期1268-1278,共11页
Dual clustering performs object clustering in both spatial and non-spatial domains that cannot be dealt with well by traditional clustering methods.However,recent dual clustering research has often omitted spatial out... Dual clustering performs object clustering in both spatial and non-spatial domains that cannot be dealt with well by traditional clustering methods.However,recent dual clustering research has often omitted spatial outliers,subjectively determined the weights of hybrid distance measures,and produced diverse clustering results.In this study,we first redefined the dual clustering problem and related concepts to highlight the clustering criteria.We then presented a self-organizing dual clustering algorithm (SDC) based on the self-organizing feature map and certain spatial analysis operations,including the Voronoi diagram and polygon aggregation and amalgamation.The algorithm employs a hybrid distance measure that combines geometric distance and non-spatial similarity,while the clustering spectrum analysis helps to determine the weight of non-spatial similarity in the measure.A case study was conducted on a spatial database of urban land price samples in Wuhan,China.SDC detected spatial outliers and clustered the points into spatially connective and attributively homogenous sub-groups.In particular,SDC revealed zonal areas that describe the actual distribution of land prices but were not demonstrated by other methods.SDC reduced the subjectivity in dual clustering. 展开更多
关键词 dual clustering DATAMINING self-organizing feature map Voronoi diagram
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