为了提高文本聚类的性能,采用k-modes算法进行文本聚类,并采用知识图谱进行样本预分析,以提高k-modes的文本聚类适用度。采用知识图谱进行样本预处理,对待聚类的文本进行知识图谱三元分析,并生成对应概念、实体和关系的样本集合;接着建...为了提高文本聚类的性能,采用k-modes算法进行文本聚类,并采用知识图谱进行样本预分析,以提高k-modes的文本聚类适用度。采用知识图谱进行样本预处理,对待聚类的文本进行知识图谱三元分析,并生成对应概念、实体和关系的样本集合;接着建立k-modes文本聚类模型,设定簇内节点至簇中心的距离值之和为目标函数,通过轮流固定隶属矩阵和聚类簇矩阵,不断求解目标函数的最小值直至目标函数值稳定,获得簇中心,最后根据簇中心及各节点到簇中心距离来确定聚类结果。实验表明,经过知识图谱分析之后,k-modes算法能够获得更优的纯度、标准互信息和F值性能,且聚类纯度的均方根误差(Root mean squared error,RMSE)值更低;和常用文本聚类算法相比,对于UCI集和新闻集,该文算法均表现出了更高的聚类准确率。展开更多
To further research the response of the tearing mode（TM） to dynamic resonant magnetic perturbation（DRMP） on the J-TEXT tokamak, a modified series resonant inverter power supply（MSRIPS） with a function of discret...To further research the response of the tearing mode（TM） to dynamic resonant magnetic perturbation（DRMP） on the J-TEXT tokamak, a modified series resonant inverter power supply（MSRIPS） with a function of discrete variable frequency is designed for DRMP coils in this study. The MSRIPS is an AC–DC–AC converter, including a phase-controlled rectifier, an LC filter, an insulated gate bipolar transistor（IGBT） full bridge, a matching transformer, three resonant capacitors with different capacitance values, and three corresponding silicon controlled rectifier（SCR） switches. The function of discrete variable frequency is realized by switching over different resonant capacitors with corresponding SCR switches while matching the corresponding driving frequency of the IGBT full bridge. A detailed switching strategy of the SCR switch is put forward to obtain sinusoidal current waveform and realize current waveform smooth transition during frequency conversion. In addition, a resistor and thyristor bleeder is designed to protect the SCR switch from overvoltage. Manufacturing of the MSRIPS is completed, and the MSRIPS equipment can output current with an amplitude of 1.5 kA when its working frequency jumps among different frequencies. Moreover, the current waveform is sinusoidal and can smoothly transition during frequency conversion. Furthermore, the transition time when the current amplitude rises from zero to a steady state is less than 2 ms during frequency conversion. By using the MSRIPS, the expected discrete variable frequency DRMP is generated, and the phenomenon of the TM being locked to the discrete variable frequency DRMP is observed on the J-TEXT tokamak.展开更多
文摘为了提高文本聚类的性能,采用k-modes算法进行文本聚类,并采用知识图谱进行样本预分析,以提高k-modes的文本聚类适用度。采用知识图谱进行样本预处理,对待聚类的文本进行知识图谱三元分析,并生成对应概念、实体和关系的样本集合;接着建立k-modes文本聚类模型,设定簇内节点至簇中心的距离值之和为目标函数,通过轮流固定隶属矩阵和聚类簇矩阵,不断求解目标函数的最小值直至目标函数值稳定,获得簇中心,最后根据簇中心及各节点到簇中心距离来确定聚类结果。实验表明,经过知识图谱分析之后,k-modes算法能够获得更优的纯度、标准互信息和F值性能,且聚类纯度的均方根误差(Root mean squared error,RMSE)值更低;和常用文本聚类算法相比,对于UCI集和新闻集,该文算法均表现出了更高的聚类准确率。
基金supported by the National ITER Project Foundation of China(No.2014GB118000)National Natural Science Foundation of China(No.11405068)
文摘To further research the response of the tearing mode（TM） to dynamic resonant magnetic perturbation（DRMP） on the J-TEXT tokamak, a modified series resonant inverter power supply（MSRIPS） with a function of discrete variable frequency is designed for DRMP coils in this study. The MSRIPS is an AC–DC–AC converter, including a phase-controlled rectifier, an LC filter, an insulated gate bipolar transistor（IGBT） full bridge, a matching transformer, three resonant capacitors with different capacitance values, and three corresponding silicon controlled rectifier（SCR） switches. The function of discrete variable frequency is realized by switching over different resonant capacitors with corresponding SCR switches while matching the corresponding driving frequency of the IGBT full bridge. A detailed switching strategy of the SCR switch is put forward to obtain sinusoidal current waveform and realize current waveform smooth transition during frequency conversion. In addition, a resistor and thyristor bleeder is designed to protect the SCR switch from overvoltage. Manufacturing of the MSRIPS is completed, and the MSRIPS equipment can output current with an amplitude of 1.5 kA when its working frequency jumps among different frequencies. Moreover, the current waveform is sinusoidal and can smoothly transition during frequency conversion. Furthermore, the transition time when the current amplitude rises from zero to a steady state is less than 2 ms during frequency conversion. By using the MSRIPS, the expected discrete variable frequency DRMP is generated, and the phenomenon of the TM being locked to the discrete variable frequency DRMP is observed on the J-TEXT tokamak.
