To solve the medium and long term power load forecasting problem,the combination forecasting method is further expanded and a weighted combination forecasting model for power load is put forward.This model is divided ...To solve the medium and long term power load forecasting problem,the combination forecasting method is further expanded and a weighted combination forecasting model for power load is put forward.This model is divided into two stages which are forecasting model selection and weighted combination forecasting.Based on Markov chain conversion and cloud model,the forecasting model selection is implanted and several outstanding models are selected for the combination forecasting.For the weighted combination forecasting,a fuzzy scale joint evaluation method is proposed to determine the weight of selected forecasting model.The percentage error and mean absolute percentage error of weighted combination forecasting result of the power consumption in a certain area of China are 0.7439%and 0.3198%,respectively,while the maximum values of these two indexes of single forecasting models are 5.2278%and 1.9497%.It shows that the forecasting indexes of proposed model are improved significantly compared with the single forecasting models.展开更多
地面强冷池在飑线灾害大风的生成过程中具有重要作用,其模拟强度与模式内云微物理过程及边界层过程的参数设置密切相关。然而,由于参数的不确定性,目前仍无法对飑线系统实施合理的参数扰动。为提升对流尺度数值模式在飑线系统预报中的表...地面强冷池在飑线灾害大风的生成过程中具有重要作用,其模拟强度与模式内云微物理过程及边界层过程的参数设置密切相关。然而,由于参数的不确定性,目前仍无法对飑线系统实施合理的参数扰动。为提升对流尺度数值模式在飑线系统预报中的表现,基于WRF(The Weather Research and Forecasting Model)模式,针对飑线冷池模拟偏弱的问题,从云微物理过程和边界层过程等方案中选取5个关键参数进行敏感性试验。并在此基础上,对其中的敏感参数实施联合扰动,探讨该方法对江苏地区一次飑线过程模拟的影响。结果表明,调整影响蒸发作用的参数,能够显著改变对地面冷池的估计,其中反映雨滴大小对其下落速度影响的参数CONSTB和考虑雨滴下落时周围空气的流动对雨滴影响的参数VF1R对地面冷池的敏感性最强;在单参数和多参数联合扰动试验中,飑线冷区模拟的2 m气温相比对照试验低1—2℃,有效改善了冷池模拟偏弱的问题。此外,CONSTB和VF1R的联合扰动对预报的影响更显著,且其模拟的10 m最大风速最接近实况。上述结果表明,针对飑线冷池的多参数联合扰动方法不仅能够有效表征物理参数化方案中参数的不确定性,还能改进对冷池的模拟,进而提高对飑线大风的预报准确度。展开更多
文摘To solve the medium and long term power load forecasting problem,the combination forecasting method is further expanded and a weighted combination forecasting model for power load is put forward.This model is divided into two stages which are forecasting model selection and weighted combination forecasting.Based on Markov chain conversion and cloud model,the forecasting model selection is implanted and several outstanding models are selected for the combination forecasting.For the weighted combination forecasting,a fuzzy scale joint evaluation method is proposed to determine the weight of selected forecasting model.The percentage error and mean absolute percentage error of weighted combination forecasting result of the power consumption in a certain area of China are 0.7439%and 0.3198%,respectively,while the maximum values of these two indexes of single forecasting models are 5.2278%and 1.9497%.It shows that the forecasting indexes of proposed model are improved significantly compared with the single forecasting models.
文摘地面强冷池在飑线灾害大风的生成过程中具有重要作用,其模拟强度与模式内云微物理过程及边界层过程的参数设置密切相关。然而,由于参数的不确定性,目前仍无法对飑线系统实施合理的参数扰动。为提升对流尺度数值模式在飑线系统预报中的表现,基于WRF(The Weather Research and Forecasting Model)模式,针对飑线冷池模拟偏弱的问题,从云微物理过程和边界层过程等方案中选取5个关键参数进行敏感性试验。并在此基础上,对其中的敏感参数实施联合扰动,探讨该方法对江苏地区一次飑线过程模拟的影响。结果表明,调整影响蒸发作用的参数,能够显著改变对地面冷池的估计,其中反映雨滴大小对其下落速度影响的参数CONSTB和考虑雨滴下落时周围空气的流动对雨滴影响的参数VF1R对地面冷池的敏感性最强;在单参数和多参数联合扰动试验中,飑线冷区模拟的2 m气温相比对照试验低1—2℃,有效改善了冷池模拟偏弱的问题。此外,CONSTB和VF1R的联合扰动对预报的影响更显著,且其模拟的10 m最大风速最接近实况。上述结果表明,针对飑线冷池的多参数联合扰动方法不仅能够有效表征物理参数化方案中参数的不确定性,还能改进对冷池的模拟,进而提高对飑线大风的预报准确度。
文摘目的:研究血清缺氧诱导因子(hypoxia-inducible factor,HIF)-1α联合前梯度蛋白2(anterior gradient 2,AGR2)对经鼻蝶手术治疗垂体瘤患者复发的预测价值。方法:回顾性分析2020年1月—2023年1月徐州市肿瘤医院收治的120例经鼻蝶手术治疗的垂体瘤患者的临床资料,根据1年内是否发生垂体瘤复发事件分为复发组和未复发组,入院时检测血清HIF-1α、AGR2水平,分析两组基本资料、生化指标,采用多因素logistic回归和受试者工作特征(receiver operating characteristic,ROC)曲线分析垂体瘤经鼻蝶手术治疗患者复发的影响因素和预测价值。结果:120例患者中,25例患者在1年内复发,复发率为20.83%。复发组血清HIF-1α、AGR2水平高于未复发组,差异有统计学意义(P<0.05)。多因素logistic回归分析结果显示HIF-1α、AGR2为垂体瘤患者经鼻蝶手术后复发的危险因素(P<0.05)。ROC曲线分析显示,血清HIF-1α、AGR2及联合预测垂体瘤患者经鼻蝶手术手复发的曲线下面积(area under the curve,AUC)分别为0.811、0.950、0.965(P<0.05)。结论:血清HIF-1α、AGR2水平是垂体瘤经鼻蝶手术治疗患者复发的危险因素,HIF-1α联合AGR2对患者复发的预测价值高于单一指标。
