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
随着我国西部地区风电场规模的不断增大且电源接入点稀少,导致牵引所和风电场的耦合度较高,电铁面临的负序问题更加严重。因此,计及双馈风电场的主动补偿能力,提出了一种电气化铁路接入风电汇集地区电网的负序优化补偿策略。首先,建立...随着我国西部地区风电场规模的不断增大且电源接入点稀少,导致牵引所和风电场的耦合度较高,电铁面临的负序问题更加严重。因此,计及双馈风电场的主动补偿能力,提出了一种电气化铁路接入风电汇集地区电网的负序优化补偿策略。首先,建立了电气化铁路牵引变电所和双馈风电场的负序阻抗模型,牵引变电所包括V/v接线牵引供电系统和静止无功发生器(static var generator,SVG)。其次,分析了V/v接线牵引供电系统的负序特性,推导了计及风电场主动补偿能力的负序传播模型。然后,给出了双馈风机(doubly-fed induction generator,DFIG)的剩余容量计算方法,提出了协同控制SVG与双馈风电场的负序优化补偿策略。最后,基于Matlab/Simulink仿真平台,验证了补偿策略的正确性和有效性。对比传统的电气化铁路负序补偿策略,该补偿策略能有效降低SVG实际补偿容量,提高装置运行年限。展开更多
建筑火灾通常发展迅速且具有很大的随机性,为最大程度减少人员伤亡,准确、快速且有效的火灾救援疏散路径引导显得尤为重要。为确保火灾发生后建筑内人员能在最短时间疏散到安全地带,以新兴的BIM(Building Information Modeling)技术为基...建筑火灾通常发展迅速且具有很大的随机性,为最大程度减少人员伤亡,准确、快速且有效的火灾救援疏散路径引导显得尤为重要。为确保火灾发生后建筑内人员能在最短时间疏散到安全地带,以新兴的BIM(Building Information Modeling)技术为基础,从火灾应急救援角度,对BIM技术在建筑火灾中的应用及目前存在的问题进行综述。从BIM技术在防火监督方面、火灾现场模拟和应急疏散应用3个方面进行综述,分析并归纳国内外BIM技术在建筑火灾中的优缺点,并对其未来的研究工作进行预测与展望,可为构建完善的智能疏散系统提供理论基础,以期为相关学者的研究工作提供启示与帮助。展开更多
储能电池作为一种较优的储能方式,在解决弃风、弃光问题方面逐渐得到重视。然而电池储能电站(battery energy storage station,BESS)的经济性现状还不明朗,难以进行大规模应用。提出了一种BESS与常规机组竞价上网的辅助服务提供模式;建...储能电池作为一种较优的储能方式,在解决弃风、弃光问题方面逐渐得到重视。然而电池储能电站(battery energy storage station,BESS)的经济性现状还不明朗,难以进行大规模应用。提出了一种BESS与常规机组竞价上网的辅助服务提供模式;建立了BESS的市场效益分析模型;根据模型计算,利用Microsoft Office Excel 2007进行BESS投资收益的敏感性分析,为电池储能电站方案规划提供工程经济参考。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.
文摘随着我国西部地区风电场规模的不断增大且电源接入点稀少,导致牵引所和风电场的耦合度较高,电铁面临的负序问题更加严重。因此,计及双馈风电场的主动补偿能力,提出了一种电气化铁路接入风电汇集地区电网的负序优化补偿策略。首先,建立了电气化铁路牵引变电所和双馈风电场的负序阻抗模型,牵引变电所包括V/v接线牵引供电系统和静止无功发生器(static var generator,SVG)。其次,分析了V/v接线牵引供电系统的负序特性,推导了计及风电场主动补偿能力的负序传播模型。然后,给出了双馈风机(doubly-fed induction generator,DFIG)的剩余容量计算方法,提出了协同控制SVG与双馈风电场的负序优化补偿策略。最后,基于Matlab/Simulink仿真平台,验证了补偿策略的正确性和有效性。对比传统的电气化铁路负序补偿策略,该补偿策略能有效降低SVG实际补偿容量,提高装置运行年限。
文摘建筑火灾通常发展迅速且具有很大的随机性,为最大程度减少人员伤亡,准确、快速且有效的火灾救援疏散路径引导显得尤为重要。为确保火灾发生后建筑内人员能在最短时间疏散到安全地带,以新兴的BIM(Building Information Modeling)技术为基础,从火灾应急救援角度,对BIM技术在建筑火灾中的应用及目前存在的问题进行综述。从BIM技术在防火监督方面、火灾现场模拟和应急疏散应用3个方面进行综述,分析并归纳国内外BIM技术在建筑火灾中的优缺点,并对其未来的研究工作进行预测与展望,可为构建完善的智能疏散系统提供理论基础,以期为相关学者的研究工作提供启示与帮助。
