多端柔性直流输电系统在继电保护方面面临的主要问题在于如何快速识别直流线路故障。阿西亚.布朗.勃法瑞有限公司(Asea Brown Boveri Ltd.,ABB)提出的极波保护原理灵敏度较低,直接应用于多端柔性直流输电系统的效果需要特别关注。因此,...多端柔性直流输电系统在继电保护方面面临的主要问题在于如何快速识别直流线路故障。阿西亚.布朗.勃法瑞有限公司(Asea Brown Boveri Ltd.,ABB)提出的极波保护原理灵敏度较低,直接应用于多端柔性直流输电系统的效果需要特别关注。因此,该文针对限流式混合直流断路器构成的边界特性,对ABB极波保护中的极波变化率进行矢量或矩阵拓展,构建极波广义变化率,并利用得到的极波变化率作为保护动作的判据。通过PSCAD/EMTDC搭建三端柔性直流输电系统,验证了改进的高敏度算法对于多端柔性直流输电系统接地故障识别的可靠性。算例表明,该极波广义变化率算法对于保护区域内的接地故障识别有较高的灵敏性和速动性,能够在0.1 ms时间尺度识别区内故障。展开更多
针对传统的协同过滤算法中广泛存在的冷启动问题,提出一种基于项目属性的推荐算法CFAFN(Collaborative Filtering based on Attributes-Filling and the Number of rating for items).通过对新用户的询问,个性化推荐系统将获取新用户对...针对传统的协同过滤算法中广泛存在的冷启动问题,提出一种基于项目属性的推荐算法CFAFN(Collaborative Filtering based on Attributes-Filling and the Number of rating for items).通过对新用户的询问,个性化推荐系统将获取新用户对项目属性的偏好信息.此外,对项目属性评分矩阵进行填充,以降低项目属性评分矩阵的稀疏性.在生成最终推荐信息之前,引入项目被评分数量的影响,进一步调整项目的预测评分,提高个性化推荐的推荐精度.通过Movie Lens数据集测试表明,该算法的推荐精度得到提升,优于一些新近提出的冷启动推荐算法.展开更多
By the aid of nullor-mirror models of the second-generation current-controlled conveyor(CCCII) and applying the nodal admittance matrix(NAM) expansion method, the family of current-mode Colpitts oscillators employing ...By the aid of nullor-mirror models of the second-generation current-controlled conveyor(CCCII) and applying the nodal admittance matrix(NAM) expansion method, the family of current-mode Colpitts oscillators employing four CCCIIs and three grounded capacitors is synthesized. Thirty-two Colpitts oscillators using CCCIIs are obtained in all. By using canonical number of components, the circuits can be easily integrated and the oscillation criterion and the oscillation frequency can be independently and electronically tuned by tuning bias currents of the CCCIIs. The paper-and-pencil analysis and Pspice simulation results have been included to support the synthesis method.展开更多
In order to obtain the multiple-feedback filter with simpler structure and electronic control,this paper first derives nodal admittance matrix(NAM)equation of the multiple-feedback filter.Furthermore,in accordance wit...In order to obtain the multiple-feedback filter with simpler structure and electronic control,this paper first derives nodal admittance matrix(NAM)equation of the multiple-feedback filter.Furthermore,in accordance with the pathological models of the operational transconductance amplifier(OTA)and second generation current-controlled conveyor(CCCII),the multiplefeedback filter based on OTAs and CCCIIs are respectively synthesized by the NAM expansion method.The filter employing three OTAs has eight equivalent realizations and the filter employing three CCCIIs has 16 equivalent realizations.24 different forms of the current-mode filters are synthesized in all.fo and Q of the synthesized filters can be tuned by tuning bias currents of the active elements.The hand analysis and computer analysis are included to support the method to be utilized.展开更多
为了得到单个VDTA浮地回转器,首先给出了VDTA的16个奇异模型,再根据节点导纳矩阵扩展法,系统综合了基于电压差分跨导放大器(VDTA)的浮地回转器,该回转器使用1个VDTA和一个接地电容,而且容易集成。通过调节的VDTA偏置电流,电路的参数能...为了得到单个VDTA浮地回转器,首先给出了VDTA的16个奇异模型,再根据节点导纳矩阵扩展法,系统综合了基于电压差分跨导放大器(VDTA)的浮地回转器,该回转器使用1个VDTA和一个接地电容,而且容易集成。通过调节的VDTA偏置电流,电路的参数能电控调节。最后,为了证实导出电路的可实现性,利用回转器构造了一个二阶通用滤波器,其极点频率fo=159 k Hz,品质因数Q=1。MULTISIM仿真结果与理论一致。展开更多
文摘多端柔性直流输电系统在继电保护方面面临的主要问题在于如何快速识别直流线路故障。阿西亚.布朗.勃法瑞有限公司(Asea Brown Boveri Ltd.,ABB)提出的极波保护原理灵敏度较低,直接应用于多端柔性直流输电系统的效果需要特别关注。因此,该文针对限流式混合直流断路器构成的边界特性,对ABB极波保护中的极波变化率进行矢量或矩阵拓展,构建极波广义变化率,并利用得到的极波变化率作为保护动作的判据。通过PSCAD/EMTDC搭建三端柔性直流输电系统,验证了改进的高敏度算法对于多端柔性直流输电系统接地故障识别的可靠性。算例表明,该极波广义变化率算法对于保护区域内的接地故障识别有较高的灵敏性和速动性,能够在0.1 ms时间尺度识别区内故障。
文摘针对传统的协同过滤算法中广泛存在的冷启动问题,提出一种基于项目属性的推荐算法CFAFN(Collaborative Filtering based on Attributes-Filling and the Number of rating for items).通过对新用户的询问,个性化推荐系统将获取新用户对项目属性的偏好信息.此外,对项目属性评分矩阵进行填充,以降低项目属性评分矩阵的稀疏性.在生成最终推荐信息之前,引入项目被评分数量的影响,进一步调整项目的预测评分,提高个性化推荐的推荐精度.通过Movie Lens数据集测试表明,该算法的推荐精度得到提升,优于一些新近提出的冷启动推荐算法.
基金Supported by the Shaanxi Provincial Key Research and Development Program,China(2018NY-158)
文摘By the aid of nullor-mirror models of the second-generation current-controlled conveyor(CCCII) and applying the nodal admittance matrix(NAM) expansion method, the family of current-mode Colpitts oscillators employing four CCCIIs and three grounded capacitors is synthesized. Thirty-two Colpitts oscillators using CCCIIs are obtained in all. By using canonical number of components, the circuits can be easily integrated and the oscillation criterion and the oscillation frequency can be independently and electronically tuned by tuning bias currents of the CCCIIs. The paper-and-pencil analysis and Pspice simulation results have been included to support the synthesis method.
基金Supported by the Shaanxi Provincial Key Research and Development Program,China(2018NY-158).
文摘In order to obtain the multiple-feedback filter with simpler structure and electronic control,this paper first derives nodal admittance matrix(NAM)equation of the multiple-feedback filter.Furthermore,in accordance with the pathological models of the operational transconductance amplifier(OTA)and second generation current-controlled conveyor(CCCII),the multiplefeedback filter based on OTAs and CCCIIs are respectively synthesized by the NAM expansion method.The filter employing three OTAs has eight equivalent realizations and the filter employing three CCCIIs has 16 equivalent realizations.24 different forms of the current-mode filters are synthesized in all.fo and Q of the synthesized filters can be tuned by tuning bias currents of the active elements.The hand analysis and computer analysis are included to support the method to be utilized.
文摘为了得到单个VDTA浮地回转器,首先给出了VDTA的16个奇异模型,再根据节点导纳矩阵扩展法,系统综合了基于电压差分跨导放大器(VDTA)的浮地回转器,该回转器使用1个VDTA和一个接地电容,而且容易集成。通过调节的VDTA偏置电流,电路的参数能电控调节。最后,为了证实导出电路的可实现性,利用回转器构造了一个二阶通用滤波器,其极点频率fo=159 k Hz,品质因数Q=1。MULTISIM仿真结果与理论一致。
