光伏电池板所处环境的非线性变化使得光伏电池的功率保持在最大功率点(maximum power point,MPP)非常困难。传统的最大功率点跟踪(maximum power point tracking,MPPT)方法普遍存在技术缺陷,无法满足当前需求。针对光伏发电MPPT问题,该...光伏电池板所处环境的非线性变化使得光伏电池的功率保持在最大功率点(maximum power point,MPP)非常困难。传统的最大功率点跟踪(maximum power point tracking,MPPT)方法普遍存在技术缺陷,无法满足当前需求。针对光伏发电MPPT问题,该文提出了一种基于麻雀搜索算法优化的极限学习机(sparrow search algorithm-extreme learning machine,SSA-ELM)神经网络控制器的MPPT方法。与传统技术相比,该MPPT方法在稳定性、速度、超调和MPP的振荡等方面的效果均较好。使用MATLAB/Simulink平台进行仿真实验,验证了所提控制策略及理论分析的正确性。展开更多
目的评估儿童先天性胫骨假关节(congenital pseudarthrosis of the tibia,CPT)行胫骨近端延长的愈合指数及并发症情况。方法回顾性分析2012年2月至2019年12月湖南省儿童医院骨科使用伊氏外固定装置行胫骨近端延长手术的57例CPT患儿临床...目的评估儿童先天性胫骨假关节(congenital pseudarthrosis of the tibia,CPT)行胫骨近端延长的愈合指数及并发症情况。方法回顾性分析2012年2月至2019年12月湖南省儿童医院骨科使用伊氏外固定装置行胫骨近端延长手术的57例CPT患儿临床资料,平均随访时间72.9个月。根据愈合指数的平均值分组,愈合指数小于57.1 d/cm为A组(n=32),大于57.1 d/cm为B组(n=25)。于胫骨近端延长治疗结束后1个月行X线检查,采用Li分类法评估骨痂质量,并随访患儿胫骨延长术后并发症情况。结果57例CPT患儿平均愈合指数为57.1 d/cm。A组手术时平均年龄为80个月,平均随访时间为75.5个月,平均延长长度为5.9 cm,延长结束后1个月骨痂形态质量良好者占81%(26/32),愈合指数为39.1 d/cm。B组手术时平均年龄为100.9个月,平均随访时间为69.6个月,平均延长长度为4.9 cm,延长结束后1个月骨痂形态良好者占56%(14/25),愈合指数为80.1 d/cm。57例中,3例于胫骨延长过程中腓骨提前愈合,5例出现针道感染,3例踝关节僵硬,1例出现踝关节跖屈20°畸形,4例出现延长段成角畸形,8例膝关节活动受限。结论CPT患儿胫骨延长过程中平均愈合指数为57.1 d/cm,存在腓骨提前愈合、延长段成角畸形等并发症,延长过程中需密切关注骨痂形态。展开更多
A more resilient livelihood is increasingly recognized as an efficient way to improve vulnerable households’food security and optimize their dietary decisions.This study quantifies rural household resilience in weste...A more resilient livelihood is increasingly recognized as an efficient way to improve vulnerable households’food security and optimize their dietary decisions.This study quantifies rural household resilience in western China,identifies the three pillars(absorptive capacity,adaptive capacity,and transformative capacity)contribution to resilience,and then establishes the estimated Resilience Capacity Index(RCI)linked with food security and dietary diversity supported by the multiple indicator multiple cause(MIMIC)model.Results show that,despite geographical heterogeneity,the RCI consistently increased from 2015 to 2021.Households with a higher RCI inheriting better capacity to deal with risk and shocks are significantly and positively correlated with increasing food expenditure and diversifying food choices.It can be because resilient households will allocate more money to food expenditure instead of saving for livelihood uncertainty.Thus,policymakers can provide more incentives for rural households to adopt more dynamic and effective risk management strategies.This,in turn,could yield positive spillover effects by preventing human capital loss associated with dietary-related chronic diseases and mortality.展开更多
文摘光伏电池板所处环境的非线性变化使得光伏电池的功率保持在最大功率点(maximum power point,MPP)非常困难。传统的最大功率点跟踪(maximum power point tracking,MPPT)方法普遍存在技术缺陷,无法满足当前需求。针对光伏发电MPPT问题,该文提出了一种基于麻雀搜索算法优化的极限学习机(sparrow search algorithm-extreme learning machine,SSA-ELM)神经网络控制器的MPPT方法。与传统技术相比,该MPPT方法在稳定性、速度、超调和MPP的振荡等方面的效果均较好。使用MATLAB/Simulink平台进行仿真实验,验证了所提控制策略及理论分析的正确性。
基金This paper was supported by the National Natural Science Foundation of China(NSFC)(71973138 and 72061137002)the Ministry of Science and Technology of China(2023YFE0105009).
文摘A more resilient livelihood is increasingly recognized as an efficient way to improve vulnerable households’food security and optimize their dietary decisions.This study quantifies rural household resilience in western China,identifies the three pillars(absorptive capacity,adaptive capacity,and transformative capacity)contribution to resilience,and then establishes the estimated Resilience Capacity Index(RCI)linked with food security and dietary diversity supported by the multiple indicator multiple cause(MIMIC)model.Results show that,despite geographical heterogeneity,the RCI consistently increased from 2015 to 2021.Households with a higher RCI inheriting better capacity to deal with risk and shocks are significantly and positively correlated with increasing food expenditure and diversifying food choices.It can be because resilient households will allocate more money to food expenditure instead of saving for livelihood uncertainty.Thus,policymakers can provide more incentives for rural households to adopt more dynamic and effective risk management strategies.This,in turn,could yield positive spillover effects by preventing human capital loss associated with dietary-related chronic diseases and mortality.
