Using mesoscale numerical model WRFV3.7,simulation tests of a low-vortex rainstorm were carried out in Langfang area,and simulation results of three boundary layer parameterization schemes(MYJ,YSU,ACM2)were contrasted...Using mesoscale numerical model WRFV3.7,simulation tests of a low-vortex rainstorm were carried out in Langfang area,and simulation results of three boundary layer parameterization schemes(MYJ,YSU,ACM2)were contrasted.The results showed that the rainstorm in Langfang area had better dynamic condition.By the influence of northeast cold vortex,cold vortex at high altitude cooperated with the surface wind speed convergence,which provided better dynamic condition for strong convective rainfall.Three boundary layer parameterization schemes all simulated surface wind speed convergence of rainstorm center.Simulation results of 24-h rainfall distribution showed that the simulation of YSU scheme was better than ACM2 and MYJ.The simulation results of flow field and temperature field also verified that YSU scheme was better than other schemes.展开更多
目的系统评价芪胶升白胶囊防治恶性肿瘤放射治疗和化学治疗(简称放化疗)后骨髓抑制的临床疗效,为临床用药提供参考。方法采用计算机检索中国知网(CNKI)、万方(WanFang)、维普(VIP)、中国生物医学文献服务系统(SinoMed)、PubMed、Web of ...目的系统评价芪胶升白胶囊防治恶性肿瘤放射治疗和化学治疗(简称放化疗)后骨髓抑制的临床疗效,为临床用药提供参考。方法采用计算机检索中国知网(CNKI)、万方(WanFang)、维普(VIP)、中国生物医学文献服务系统(SinoMed)、PubMed、Web of Science、The Cochrane Library等数据库中关于芪胶升白胶囊防治恶性肿瘤放化疗后骨髓抑制的随机对照试验(RCT),检索时限为自建库起至2023年4月22日。采用改良的Jadad量表对纳入文献进行质量评价,采用RevMan 5.4软件进行Meta分析。结果共纳入25项RCT,涉及患者2754例,其中试验组1466例,对照组1288例。Meta分析结果显示,予芪胶升白胶囊的试验组患者的总体骨髓抑制率[OR=0.27,95%CI(0.21,0.35),P<0.00001],Ⅲ-Ⅳ级骨髓抑制率[OR=0.23,95%CI(0.16,0.34),P<0.00001],白细胞[MD=1.18,95%CI(0.98,1.38),P<0.00001],血小板[MD=14.06,95%CI(12.95,15.16),P<0.00001],血红蛋白[MD=0.98,95%CI(0.87,1.09),P<0.00001],卡氏评分体系(KPS)评分改善率[OR=2.65,95%CI(1.90,3.70),P<0.00001],KPS评分[MD=6.13,95%CI(4.48,7.79),P<0.00001]的改善效果均显著优于对照组。结论芪胶升白胶囊可有效降低恶性肿瘤患者放化疗后的总体骨髓抑制率、Ⅲ-Ⅳ级骨髓抑制率,升高KPS评分、白细胞、血红蛋白、血小板,改善骨髓抑制情况。展开更多
电离层总电子含量(Total Electron Content,TEC)的监测与预报是空间环境研究的重要内容,对卫星通讯和导航定位等有重要意义.TEC值影响因素较多,很难确定精确物理模型来对其进行预测.本文设计了基于注意力机制的LSTM模型(Att-LSTM),采用...电离层总电子含量(Total Electron Content,TEC)的监测与预报是空间环境研究的重要内容,对卫星通讯和导航定位等有重要意义.TEC值影响因素较多,很难确定精确物理模型来对其进行预测.本文设计了基于注意力机制的LSTM模型(Att-LSTM),采用过去24小时TEC观测数据对未来TEC进行预测.选择北半球东经100°上,每2.5°纬度选择一个位置,共计36个位置来验证本文提出模型的性能,并与主流的深度学习模型如DNN、RNN、LSTM进行对比实验.取得了如下成果:(1)在选定的36个地区未来2小时单点预测上,基于本文的Att-LSTM模型的TEC预测性能明显优于其他对比模型;(2)讨论了纬度对Att-LSTM预测未来2小时TEC值时性能的影响,发现在北纬0°到60°之间,Att-LSTM预测性能随着纬度的升高而略有降低,在北纬62.5°~87.5°之间,模型预测性能出现扰动,预测效果略差;(3)讨论了磁暴期和磁静期模型的预测性能,发现无论是磁暴期还是磁静期,本文模型预测性能均较好;(4)还讨论了对未来多时点预测效果,实验结果表明,本文所提出的模型对未来2、4个小时的预测拟合度R-Square均超过0.95,预测结果比较可靠,对未来6、8、10个小时预测拟合度最高为0.7934,预测拟合度R-Square下降迅速,预测结果不可靠.展开更多
文摘Using mesoscale numerical model WRFV3.7,simulation tests of a low-vortex rainstorm were carried out in Langfang area,and simulation results of three boundary layer parameterization schemes(MYJ,YSU,ACM2)were contrasted.The results showed that the rainstorm in Langfang area had better dynamic condition.By the influence of northeast cold vortex,cold vortex at high altitude cooperated with the surface wind speed convergence,which provided better dynamic condition for strong convective rainfall.Three boundary layer parameterization schemes all simulated surface wind speed convergence of rainstorm center.Simulation results of 24-h rainfall distribution showed that the simulation of YSU scheme was better than ACM2 and MYJ.The simulation results of flow field and temperature field also verified that YSU scheme was better than other schemes.
文摘电离层总电子含量(Total Electron Content,TEC)的监测与预报是空间环境研究的重要内容,对卫星通讯和导航定位等有重要意义.TEC值影响因素较多,很难确定精确物理模型来对其进行预测.本文设计了基于注意力机制的LSTM模型(Att-LSTM),采用过去24小时TEC观测数据对未来TEC进行预测.选择北半球东经100°上,每2.5°纬度选择一个位置,共计36个位置来验证本文提出模型的性能,并与主流的深度学习模型如DNN、RNN、LSTM进行对比实验.取得了如下成果:(1)在选定的36个地区未来2小时单点预测上,基于本文的Att-LSTM模型的TEC预测性能明显优于其他对比模型;(2)讨论了纬度对Att-LSTM预测未来2小时TEC值时性能的影响,发现在北纬0°到60°之间,Att-LSTM预测性能随着纬度的升高而略有降低,在北纬62.5°~87.5°之间,模型预测性能出现扰动,预测效果略差;(3)讨论了磁暴期和磁静期模型的预测性能,发现无论是磁暴期还是磁静期,本文模型预测性能均较好;(4)还讨论了对未来多时点预测效果,实验结果表明,本文所提出的模型对未来2、4个小时的预测拟合度R-Square均超过0.95,预测结果比较可靠,对未来6、8、10个小时预测拟合度最高为0.7934,预测拟合度R-Square下降迅速,预测结果不可靠.
