In this paper,a rainfall-runoff modeling system is developed based on a nonlinear Volterra functional series and a hydrological conceptual modeling approach.Two models,i.e.the time-variant gain model(TVGM)and the dist...In this paper,a rainfall-runoff modeling system is developed based on a nonlinear Volterra functional series and a hydrological conceptual modeling approach.Two models,i.e.the time-variant gain model(TVGM)and the distributed time-variant gain model(DTVGM)that are built on the platform of Digital Elevation Model(DEM),Remote Sensing(RS)and Unit Hydro-logical Process were proposed.The developed DTVGM model was applied to two cases in the Heihe River Basin that is located in the arid and semiarid region of northwestern China and the Chaobai River basin located in the semihumid region of northern China.The results indicate that,in addition to the classic dynamic differential approach to describe nonlinear processes in hy-drological systems,it is possible to study such complex processes through the proposed sys-tematic approach to identify prominent hydrological relations.The DTVGM,coupling the advan-tages of both nonlinear and distributed hydrological models,can simulate variant hydrological processes under different environment conditions.Satisfactory results were obtained in fore-casting the time-space variations of hydrological processes and the relationships between land use/cover change and surface runoff variation.展开更多
基于时变参数向量自回归(time-varying parameter-vector auto regression,TVPVAR)模型,考察了经济政策不确定性、投资者情绪与股价同步性之间的时变关联性.模型估计结果表明,经济政策不确定性对股价同步性主要表现为中短期的正向影响,...基于时变参数向量自回归(time-varying parameter-vector auto regression,TVPVAR)模型,考察了经济政策不确定性、投资者情绪与股价同步性之间的时变关联性.模型估计结果表明,经济政策不确定性对股价同步性主要表现为中短期的正向影响,且波动比较明显,长期影响则相对较弱;投资者情绪对股价同步性表现为负向影响,且短期影响最为明显,长期影响则较弱.时点脉冲函数结果显示,在不同时间点上,股价同步性对经济政策不确定性的冲击具有正向响应,对投资者情绪的冲击具有负向响应,且不同时间点的响应程度和响应时间均存在差异.这些结论为进一步完善政策调控体系,规范和引导投资者行为,促进市场理性化提供了思路.展开更多
针对混合型有源滤波器在实际应用时,无功补偿不能出现过补偿及谐振的问题,提出采用电容无功补偿功率与串并联谐振频率的关系作为约束条件对并联混合型有源滤波器SHAPF(shunt hybrid active powerfilter)参数进行优化配置。寻优算法采用...针对混合型有源滤波器在实际应用时,无功补偿不能出现过补偿及谐振的问题,提出采用电容无功补偿功率与串并联谐振频率的关系作为约束条件对并联混合型有源滤波器SHAPF(shunt hybrid active powerfilter)参数进行优化配置。寻优算法采用改进的粒子群优化算法IPSO(improved particle swarm optimiza-tion),根据粒子群算法参数速度v和惯性因子w的关系,提出时变的非线性三角函数方法来控制参数,加速了算法的收敛速度,防止陷入局部最优。通过Matlab进行仿真验证,SHAPF的参数设计得到了优化配置,具有良好的滤波效果。在实例应用中,有效地避免了谐振,具有一定的工程应用价值。展开更多
基金the Hundred Talents Program and Knowledge Innovation Key Project and the Outstanding Overseas Chinese Scholars Program of the Chinese Academy of Sciences(Grant No.KZCX2-SW-317/KZCX1-09-02)the National Natural Science Foundation of China(Grant No.50279049).
文摘In this paper,a rainfall-runoff modeling system is developed based on a nonlinear Volterra functional series and a hydrological conceptual modeling approach.Two models,i.e.the time-variant gain model(TVGM)and the distributed time-variant gain model(DTVGM)that are built on the platform of Digital Elevation Model(DEM),Remote Sensing(RS)and Unit Hydro-logical Process were proposed.The developed DTVGM model was applied to two cases in the Heihe River Basin that is located in the arid and semiarid region of northwestern China and the Chaobai River basin located in the semihumid region of northern China.The results indicate that,in addition to the classic dynamic differential approach to describe nonlinear processes in hy-drological systems,it is possible to study such complex processes through the proposed sys-tematic approach to identify prominent hydrological relations.The DTVGM,coupling the advan-tages of both nonlinear and distributed hydrological models,can simulate variant hydrological processes under different environment conditions.Satisfactory results were obtained in fore-casting the time-space variations of hydrological processes and the relationships between land use/cover change and surface runoff variation.
文摘基于时变参数向量自回归(time-varying parameter-vector auto regression,TVPVAR)模型,考察了经济政策不确定性、投资者情绪与股价同步性之间的时变关联性.模型估计结果表明,经济政策不确定性对股价同步性主要表现为中短期的正向影响,且波动比较明显,长期影响则相对较弱;投资者情绪对股价同步性表现为负向影响,且短期影响最为明显,长期影响则较弱.时点脉冲函数结果显示,在不同时间点上,股价同步性对经济政策不确定性的冲击具有正向响应,对投资者情绪的冲击具有负向响应,且不同时间点的响应程度和响应时间均存在差异.这些结论为进一步完善政策调控体系,规范和引导投资者行为,促进市场理性化提供了思路.
