The reasonable quantification of the concrete freezing environment on the Qinghai–Tibet Plateau(QTP) is the primary issue in frost resistant concrete design, which is one of the challenges that the QTP engineering ma...The reasonable quantification of the concrete freezing environment on the Qinghai–Tibet Plateau(QTP) is the primary issue in frost resistant concrete design, which is one of the challenges that the QTP engineering managers should take into account. In this paper, we propose a more realistic method to calculate the number of concrete freeze–thaw cycles(NFTCs) on the QTP. The calculated results show that the NFTCs increase as the altitude of the meteorological station increases with the average NFTCs being 208.7. Four machine learning methods, i.e., the random forest(RF) model, generalized boosting method(GBM), generalized linear model(GLM), and generalized additive model(GAM), are used to fit the NFTCs. The root mean square error(RMSE) values of the RF, GBM, GLM, and GAM are 32.3, 4.3, 247.9, and 161.3, respectively. The R^(2) values of the RF, GBM, GLM, and GAM are 0.93, 0.99, 0.48, and 0.66, respectively. The GBM method performs the best compared to the other three methods, which was shown by the results of RMSE and R^(2) values. The quantitative results from the GBM method indicate that the lowest, medium, and highest NFTC values are distributed in the northern, central, and southern parts of the QTP, respectively. The annual NFTCs in the QTP region are mainly concentrated at 160 and above, and the average NFTCs is 200 across the QTP. Our results can provide scientific guidance and a theoretical basis for the freezing resistance design of concrete in various projects on the QTP.展开更多
目的评估SOFIA远端通路导管直接抽吸治疗早期急性缺血性脑卒中(acute ischemic stroke,AIS)的安全性及有效性。方法选取2018年1月至2019年10月间进行血管内治疗的早期AIS患者65例,其中20例首选SOFIA远端通路导管抽吸取栓治疗(抽吸组),4...目的评估SOFIA远端通路导管直接抽吸治疗早期急性缺血性脑卒中(acute ischemic stroke,AIS)的安全性及有效性。方法选取2018年1月至2019年10月间进行血管内治疗的早期AIS患者65例,其中20例首选SOFIA远端通路导管抽吸取栓治疗(抽吸组),45例首选支架取栓治疗(支架组)。采用改良脑梗死溶栓治疗分级(modified treatment in cerebral ischemia,mTICI)、美国国立卫生研究院卒中量表(National Institute of Health stroke scale,NIHSS)、改良Rankin量表评分(modified rankin scale,mRS)分别评估成功再通及临床预后。对比抽吸组与支架组的手术相关指标(手术时间、血管成功再通)、并发症及临床预后。结果抽吸组较支架组穿刺至血管成功再通时间短,差异具有统计学意义[27(14,36)min vs.34(29,50)min,P<0.05],而血管成功再通率(mTICI 2b/3级)差异无统计学意义(18/20 vs.38/45,P>0.05)。抽吸组与支架组发生血栓逃逸(1/20 vs.3/45)、颅内出血(3/20 vs.7/45)和其他不良事件(1/20 vs.5/45),差异无统计学意义(P>0.05)。抽吸组与支架组术后24 h和7 d NIHSS评分[10(5,13)vs.12(7,17),5(3,11)vs.10(3,15)],90 d mRS评分≤2分及死亡率,差异均无统计学意义(P>0.05)。结论与首选支架取栓相比,SOFIA远端通路导管直接抽吸治疗早期AIS患者具有相似安全性及疗效,且具有操作简单用时短的特点。展开更多
基金supported by Shandong Provincial Natural Science Foundation (grant number: ZR2023MD036)Key Research and Development Project in Shandong Province (grant number: 2019GGX101064)project for excellent youth foundation of the innovation teacher team, Shandong (grant number: 2022KJ310)。
文摘The reasonable quantification of the concrete freezing environment on the Qinghai–Tibet Plateau(QTP) is the primary issue in frost resistant concrete design, which is one of the challenges that the QTP engineering managers should take into account. In this paper, we propose a more realistic method to calculate the number of concrete freeze–thaw cycles(NFTCs) on the QTP. The calculated results show that the NFTCs increase as the altitude of the meteorological station increases with the average NFTCs being 208.7. Four machine learning methods, i.e., the random forest(RF) model, generalized boosting method(GBM), generalized linear model(GLM), and generalized additive model(GAM), are used to fit the NFTCs. The root mean square error(RMSE) values of the RF, GBM, GLM, and GAM are 32.3, 4.3, 247.9, and 161.3, respectively. The R^(2) values of the RF, GBM, GLM, and GAM are 0.93, 0.99, 0.48, and 0.66, respectively. The GBM method performs the best compared to the other three methods, which was shown by the results of RMSE and R^(2) values. The quantitative results from the GBM method indicate that the lowest, medium, and highest NFTC values are distributed in the northern, central, and southern parts of the QTP, respectively. The annual NFTCs in the QTP region are mainly concentrated at 160 and above, and the average NFTCs is 200 across the QTP. Our results can provide scientific guidance and a theoretical basis for the freezing resistance design of concrete in various projects on the QTP.
文摘目的评估SOFIA远端通路导管直接抽吸治疗早期急性缺血性脑卒中(acute ischemic stroke,AIS)的安全性及有效性。方法选取2018年1月至2019年10月间进行血管内治疗的早期AIS患者65例,其中20例首选SOFIA远端通路导管抽吸取栓治疗(抽吸组),45例首选支架取栓治疗(支架组)。采用改良脑梗死溶栓治疗分级(modified treatment in cerebral ischemia,mTICI)、美国国立卫生研究院卒中量表(National Institute of Health stroke scale,NIHSS)、改良Rankin量表评分(modified rankin scale,mRS)分别评估成功再通及临床预后。对比抽吸组与支架组的手术相关指标(手术时间、血管成功再通)、并发症及临床预后。结果抽吸组较支架组穿刺至血管成功再通时间短,差异具有统计学意义[27(14,36)min vs.34(29,50)min,P<0.05],而血管成功再通率(mTICI 2b/3级)差异无统计学意义(18/20 vs.38/45,P>0.05)。抽吸组与支架组发生血栓逃逸(1/20 vs.3/45)、颅内出血(3/20 vs.7/45)和其他不良事件(1/20 vs.5/45),差异无统计学意义(P>0.05)。抽吸组与支架组术后24 h和7 d NIHSS评分[10(5,13)vs.12(7,17),5(3,11)vs.10(3,15)],90 d mRS评分≤2分及死亡率,差异均无统计学意义(P>0.05)。结论与首选支架取栓相比,SOFIA远端通路导管直接抽吸治疗早期AIS患者具有相似安全性及疗效,且具有操作简单用时短的特点。
