为了提高光伏发电功率短期预测结果的准确性,提出了一种基于改进灰狼(improved grey wolf optimization,IGWO)算法优化长短时记忆(long short term memory,LSTM)神经网络的光伏发电功率短期预测方法。利用余弦相似度寻找相似日,确定光...为了提高光伏发电功率短期预测结果的准确性,提出了一种基于改进灰狼(improved grey wolf optimization,IGWO)算法优化长短时记忆(long short term memory,LSTM)神经网络的光伏发电功率短期预测方法。利用余弦相似度寻找相似日,确定光伏发电功率预测的特征量和训练集。采用非线性收敛因子和差分进化策略对GWO算法进行改进,得到收敛性能更好的IGWO算法,采用IGWO算法对LSTM的超参数进行优化,建立了基于IGWO-LSTM的光伏发电功率短期预测模型。使用某小型光伏电站的运行数据进行仿真分析,结果表明,IGWOLSTM模型对晴天、多云和阴雨天气光伏功率预测结果的均方根误差依次为2.11 kW、2.48 kW和2.74 kW,平均相对误差依次为3.43%、4.81%和6.33%,预测效果优于其他方法,验证了所提方法的实用性和有效性。展开更多
The electrical transport and magnetic properties of colossal magnetoresistance material FeCr_(2)S_(4) are studied.The temperature dependence of resistivityρand thermoelectric power S are investigated from 5 to 300 K ...The electrical transport and magnetic properties of colossal magnetoresistance material FeCr_(2)S_(4) are studied.The temperature dependence of resistivityρand thermoelectric power S are investigated from 5 to 300 K and from 77 to 300 K,respectively.The activation energy E ρ obtained from ρ-T is larger than the activation energy ES,obtained from S-T.This indicates that magnetic polarons dominate the conduction behaviour at temperatures above Tc.The M-T curve and electron spin resonance spectra show that the paramagnetic-ferromagnetic transition is incomplete,and that a paramagnetic phase coexists with a ferromagnetic phase in a certain temperature range below Tc.It is proposed that the insulator-metal transition near Tc could be attributed to the gradual delocalizing effect from magnetic polarons to naked carriers.The resistivity in the presented temperature range can be described by considering the coexistence of magnetic polarons and naked carriers.展开更多
目的:比较布地奈德雾化吸入与地塞米松静脉注射预防重症监护病房(intensive care unit,ICU)插管患者喉水肿的疗效.方法:选取2018年1月至2019年6月重庆市公共卫生医疗救治中心ICU收治的气管插管并顺利拔管的危重症患者318例,随机分为布...目的:比较布地奈德雾化吸入与地塞米松静脉注射预防重症监护病房(intensive care unit,ICU)插管患者喉水肿的疗效.方法:选取2018年1月至2019年6月重庆市公共卫生医疗救治中心ICU收治的气管插管并顺利拔管的危重症患者318例,随机分为布地奈德组、地塞米松组与对照组,每组106例.布地奈德组患者给予布地奈德混悬液雾化吸入治疗,地塞米松组患者给予地塞米松静脉注射治疗,对照组患者给予0.9%氯化钠注射液静脉注射治疗.于插管前,插管后6、12、24、36及48 h检测三组患者的最小潮气量(MTV)、相对漏气量(CLR),检测并比较三组患者心率(HR)、动脉血氧饱和度(SaO2)与平均动脉压(MAP).采用单变量分析人口统计学因素与CLR的相关性.结果:插管后12、24、36及48 h,布地奈德组、地塞米松组患者MTV、CLR水平明显优于对照组,差异均有统计学意义(P<0.05);插管后36、48 h,布地奈德组患者CLR水平明显高于地塞米松组,差异有统计学意义(P<0.05).插管后24、36及48 h,布地奈德组、地塞米松组患者HR、SaO2及MAP水平明显优于对照组,差异均有统计学意义(P<0.05);但插管后,布地奈德组、地塞米松组患者HR、SaO2及MAP水平的差异均无统计学意义(P>0.05).结论:布地奈德雾化吸入与地塞米松静脉注射均可有效预防ICU插管患者喉水肿并发症的发生;与地塞米松静脉注射相比,布地奈德雾化吸入预防的疗效更好.展开更多
文摘为了提高光伏发电功率短期预测结果的准确性,提出了一种基于改进灰狼(improved grey wolf optimization,IGWO)算法优化长短时记忆(long short term memory,LSTM)神经网络的光伏发电功率短期预测方法。利用余弦相似度寻找相似日,确定光伏发电功率预测的特征量和训练集。采用非线性收敛因子和差分进化策略对GWO算法进行改进,得到收敛性能更好的IGWO算法,采用IGWO算法对LSTM的超参数进行优化,建立了基于IGWO-LSTM的光伏发电功率短期预测模型。使用某小型光伏电站的运行数据进行仿真分析,结果表明,IGWOLSTM模型对晴天、多云和阴雨天气光伏功率预测结果的均方根误差依次为2.11 kW、2.48 kW和2.74 kW,平均相对误差依次为3.43%、4.81%和6.33%,预测效果优于其他方法,验证了所提方法的实用性和有效性。
基金Supported by the National Natural Science Foundation of China under Grant No.19934003the Foundation of Chinese Academy of Sciences,as well as the Research Fund for the Doctoral Program of Higher Education.
文摘The electrical transport and magnetic properties of colossal magnetoresistance material FeCr_(2)S_(4) are studied.The temperature dependence of resistivityρand thermoelectric power S are investigated from 5 to 300 K and from 77 to 300 K,respectively.The activation energy E ρ obtained from ρ-T is larger than the activation energy ES,obtained from S-T.This indicates that magnetic polarons dominate the conduction behaviour at temperatures above Tc.The M-T curve and electron spin resonance spectra show that the paramagnetic-ferromagnetic transition is incomplete,and that a paramagnetic phase coexists with a ferromagnetic phase in a certain temperature range below Tc.It is proposed that the insulator-metal transition near Tc could be attributed to the gradual delocalizing effect from magnetic polarons to naked carriers.The resistivity in the presented temperature range can be described by considering the coexistence of magnetic polarons and naked carriers.
