常规Duffing振子检测方法只能确定待测弱信号的有无及幅值大小,却无法给出其在时域上的分布信息,且待测信号包络有起伏时会引起Duffing振子系统的误判。针对上述问题,本文提出可变幅值系数的短时Duffing振子阵列检测方法。应用互模糊函...常规Duffing振子检测方法只能确定待测弱信号的有无及幅值大小,却无法给出其在时域上的分布信息,且待测信号包络有起伏时会引起Duffing振子系统的误判。针对上述问题,本文提出可变幅值系数的短时Duffing振子阵列检测方法。应用互模糊函数推导出随机振幅包络起伏信号通过短时处理可以降低包络起伏因素对Duffing振子检测性能的影响,对信号加时间窗的短时处理可以保证窗内信号近似平稳,并可同时获得待测信号在时域上的分布信息。为克服相图判别法定性分析的不足,降低待测信号与内置策动力合成的总策动力幅值小于跃变阈值时出现的漏报误判概率,提出可变幅值系数的Poincare映射集判别方法,给出了量化统计判别结果。仿真及实测水声信号检测结果表明,在-33 d B的低信噪比背景下仍可实现信号的检测判别。展开更多
为了提高配电线路的安全可靠性并对线路防雷设计提供有价值的参考依据,基于非均匀传输线理论和Agrawal场线耦合模型,实现了一种用于求解非均匀多导体传输线场线耦合模型改进电报方程的单变量时域有限元(FETD)法,通过与双变量FETD法对比...为了提高配电线路的安全可靠性并对线路防雷设计提供有价值的参考依据,基于非均匀传输线理论和Agrawal场线耦合模型,实现了一种用于求解非均匀多导体传输线场线耦合模型改进电报方程的单变量时域有限元(FETD)法,通过与双变量FETD法对比,验证该方法的正确性。针对典型35 k V架空配电线路,计算了不同大地电导率和雷击距离条件下考虑导线弧垂的雷电感应电压,并分析了弧垂对雷电感应电压的影响机理。结果表明实现线路雷电感应电压的准确计算需要计及弧垂的影响。此外,比较了考虑弧垂、电晕和架设地线对雷电感应电压的影响,进一步说明了考虑导线弧垂的必要性。展开更多
A new efficient parallel finite-difference time-domain(FDTD) meshing algorithm, based on the ray tracing technique, is proposed in this paper. This algorithm can be applied to construct various FDTD meshes, such as re...A new efficient parallel finite-difference time-domain(FDTD) meshing algorithm, based on the ray tracing technique, is proposed in this paper. This algorithm can be applied to construct various FDTD meshes, such as regular and conformal ones. The Microsoft F# language is used for the algorithm coding, where all variables are unchangeable with its parallelization advantage being fully exploited. An improved conformal FDTD algorithm, also integrated with an improved surface current algorithm, is presented to simulate some complex 3D models, such as a sphere ball made of eight different materials, a tank, a J-10 aircraft, and an aircraft carrier with 20 aircrafts. Both efficiency and capability of the developed parallel FDTD algorithm are validated. The algorithm is applied to characterize the induced surface current distribution on an aircraft or a warship.展开更多
文摘常规Duffing振子检测方法只能确定待测弱信号的有无及幅值大小,却无法给出其在时域上的分布信息,且待测信号包络有起伏时会引起Duffing振子系统的误判。针对上述问题,本文提出可变幅值系数的短时Duffing振子阵列检测方法。应用互模糊函数推导出随机振幅包络起伏信号通过短时处理可以降低包络起伏因素对Duffing振子检测性能的影响,对信号加时间窗的短时处理可以保证窗内信号近似平稳,并可同时获得待测信号在时域上的分布信息。为克服相图判别法定性分析的不足,降低待测信号与内置策动力合成的总策动力幅值小于跃变阈值时出现的漏报误判概率,提出可变幅值系数的Poincare映射集判别方法,给出了量化统计判别结果。仿真及实测水声信号检测结果表明,在-33 d B的低信噪比背景下仍可实现信号的检测判别。
文摘为了提高配电线路的安全可靠性并对线路防雷设计提供有价值的参考依据,基于非均匀传输线理论和Agrawal场线耦合模型,实现了一种用于求解非均匀多导体传输线场线耦合模型改进电报方程的单变量时域有限元(FETD)法,通过与双变量FETD法对比,验证该方法的正确性。针对典型35 k V架空配电线路,计算了不同大地电导率和雷击距离条件下考虑导线弧垂的雷电感应电压,并分析了弧垂对雷电感应电压的影响机理。结果表明实现线路雷电感应电压的准确计算需要计及弧垂的影响。此外,比较了考虑弧垂、电晕和架设地线对雷电感应电压的影响,进一步说明了考虑导线弧垂的必要性。
基金Project supported in part by the National Natural Science Foundation of China(No.60831002)Zhejiang Provincial Natural Science Foundation of China(No.LZF010001)
文摘A new efficient parallel finite-difference time-domain(FDTD) meshing algorithm, based on the ray tracing technique, is proposed in this paper. This algorithm can be applied to construct various FDTD meshes, such as regular and conformal ones. The Microsoft F# language is used for the algorithm coding, where all variables are unchangeable with its parallelization advantage being fully exploited. An improved conformal FDTD algorithm, also integrated with an improved surface current algorithm, is presented to simulate some complex 3D models, such as a sphere ball made of eight different materials, a tank, a J-10 aircraft, and an aircraft carrier with 20 aircrafts. Both efficiency and capability of the developed parallel FDTD algorithm are validated. The algorithm is applied to characterize the induced surface current distribution on an aircraft or a warship.
