为便于太阳风暴行星际传播数值模型结果可视化分析,提出一种针对时变模拟数据体绘制的传输函数设计算法(Transfer Function for Time-varying Volume data,TFTV)。该算法首先基于KNN(K-Nearest Neighbors,KNN)背景差分法提取运动区域;然...为便于太阳风暴行星际传播数值模型结果可视化分析,提出一种针对时变模拟数据体绘制的传输函数设计算法(Transfer Function for Time-varying Volume data,TFTV)。该算法首先基于KNN(K-Nearest Neighbors,KNN)背景差分法提取运动区域;然后,利用频率调谐(Frequency Tuned,FT)显著性算法检测日冕物质抛射(Coronal Mass Ejection,CME),并设计颜色反映射算法查找CME与背景的分界阈值;最后,基于阈值自适应调整传输函数实现各时间步上运动区域中CME的快速三维可视化。实验结果表明,该算法能够适应静态及动态背景下CME的数值模型结果,相对于线性传输函数有效避免了视线方向的遮挡,直观自动地展示了相对动量的变化,示踪行星际空间中CME的演化过程,局部区域的提取降低了数据冗余,借助算法自动分析数据自适应调整传输函数避免了人工调整的低效性。展开更多
We analyse the WIND data of an interplanetary magnetic cloud （MC） on 2 November 2001, and find new evidences for magnetic reconnection in the tail of this MC. In the MC tail, the largely dip and the large change of ...We analyse the WIND data of an interplanetary magnetic cloud （MC） on 2 November 2001, and find new evidences for magnetic reconnection in the tail of this MC. In the MC tail, the largely dip and the large change of the orientation of the magnetic field occurred simultaneously, △θ≈45° and △φ changed from 90° to 320°. Correspondingly, the number density of ions increased, and the superthermal electrons were heated and accelerated, however its number density decreased. Meanwhile, inverse jets and Hall term were observed. The pitch-angle distributions of the electrons with lower energy and higher energy showed strong turbulence and bi-direction flow, respectively. The plasma wave activity enhanced near the electron plasma frequency, fpe and 2fpe. These important physical characteristics are new evidences for magnetic reconnection existing in interplanetary space.展开更多
文摘为便于太阳风暴行星际传播数值模型结果可视化分析,提出一种针对时变模拟数据体绘制的传输函数设计算法(Transfer Function for Time-varying Volume data,TFTV)。该算法首先基于KNN(K-Nearest Neighbors,KNN)背景差分法提取运动区域;然后,利用频率调谐(Frequency Tuned,FT)显著性算法检测日冕物质抛射(Coronal Mass Ejection,CME),并设计颜色反映射算法查找CME与背景的分界阈值;最后,基于阈值自适应调整传输函数实现各时间步上运动区域中CME的快速三维可视化。实验结果表明,该算法能够适应静态及动态背景下CME的数值模型结果,相对于线性传输函数有效避免了视线方向的遮挡,直观自动地展示了相对动量的变化,示踪行星际空间中CME的演化过程,局部区域的提取降低了数据冗余,借助算法自动分析数据自适应调整传输函数避免了人工调整的低效性。
基金Supported by the National Natural Science Foundation of China under Grant Nos G200078405, 40336053 and 40274052, and the International Collaboration Research Team Program of the Chinese Academy of Sciences.
文摘We analyse the WIND data of an interplanetary magnetic cloud （MC） on 2 November 2001, and find new evidences for magnetic reconnection in the tail of this MC. In the MC tail, the largely dip and the large change of the orientation of the magnetic field occurred simultaneously, △θ≈45° and △φ changed from 90° to 320°. Correspondingly, the number density of ions increased, and the superthermal electrons were heated and accelerated, however its number density decreased. Meanwhile, inverse jets and Hall term were observed. The pitch-angle distributions of the electrons with lower energy and higher energy showed strong turbulence and bi-direction flow, respectively. The plasma wave activity enhanced near the electron plasma frequency, fpe and 2fpe. These important physical characteristics are new evidences for magnetic reconnection existing in interplanetary space.
