The extreme temperature differences in fiat steel box girder of a cable-stayed bridge were studied.Firstly,by using the long-term measurement data collected by the structural health monitoring system installed on the ...The extreme temperature differences in fiat steel box girder of a cable-stayed bridge were studied.Firstly,by using the long-term measurement data collected by the structural health monitoring system installed on the Runyang Cable-stayed Bridge,the daily variations as well as seasonal ones of measured temperature differences in the box girder cross-section area were summarized.The probability distribution models of temperature differences were further established and the extreme temperature differences were estimated with a return period of 100 years.Finally,the temperature difference models in cross-section area were proposed for bridge thermal design.The results show that horizontal temperature differences in top plate and vertical temperature differences between top plate and bottom plate are considerable.All the positive and negative temperature differences can be described by the weighted sum of two Weibull distributions.The maximum positive and negative horizontal temperature differences in top plate are 10.30 ℃ and -13.80 ℃,respectively.And the maximum positive and negative vertical temperature differences between top plate and bottom plate are 17.30 ℃ and-3.70 ℃,respectively.For bridge thermal design,there are two vertical temperature difference models between top plate and bottom plate,and six horizontal temperature difference models in top plate.展开更多
Extrerae case formulation(ECF) was first put forward by Pomerantz in 1986 and is thought to be a general linguistic phenomenon in daily conversation.Since previous studies have manifested that linguistic gender differ...Extrerae case formulation(ECF) was first put forward by Pomerantz in 1986 and is thought to be a general linguistic phenomenon in daily conversation.Since previous studies have manifested that linguistic gender difference do exist in the conversation,whether there is any difference in the use of extreme case formulations caused by different gender becomes a considerable subject.In this paper,this subject is studied based on the corpus of lines of Friends.The quantitative analysis is mainly applied with the help of the software Antconc to get the number and proportion of extreme case respectively used by male and female.The statistics shows that gender difference do exist in the use of extreme case.The number of extreme case used by female is basically more than men under the condition that the extreme cases are used in 3 ways and 4 kinds of activities that were summarized by Pomerantz.Besides,there are some limitations in this paper,the data is not widely covered and the reason of the gender difference is not thoroughly investigated.Therefore,the study of the linguistic gender difference in the respect of extreme cases still has a long way to go.展开更多
In this paper,a new type of finite difference mapped weighted essentially non-oscillatory(MWENO)schemes with unequal-sized stencils,such as the seventh-order and ninthorder versions,is constructed for solving hyperbol...In this paper,a new type of finite difference mapped weighted essentially non-oscillatory(MWENO)schemes with unequal-sized stencils,such as the seventh-order and ninthorder versions,is constructed for solving hyperbolic conservation laws.For the purpose of designing increasingly high-order finite difference WENO schemes,the equal-sized stencils are becoming more and more wider.The more we use wider candidate stencils,the bigger the probability of discontinuities lies in all stencils.Therefore,one innovation of these new WENO schemes is to introduce a new splitting stencil methodology to divide some fourpoint or five-point stencils into several smaller three-point stencils.By the usage of this new methodology in high-order spatial reconstruction procedure,we get different degree polynomials defined on these unequal-sized stencils,and calculate the linear weights,smoothness indicators,and nonlinear weights as specified in Jiang and Shu(J.Comput.Phys.126:202228,1996).Since the difference between the nonlinear weights and the linear weights is too big to keep the optimal order of accuracy in smooth regions,another crucial innovation is to present the new mapping functions which are used to obtain the mapped nonlinear weights and decrease the difference quantity between the mapped nonlinear weights and the linear weights,so as to keep the optimal order of accuracy in smooth regions.These new MWENO schemes can also be applied to compute some extreme examples,such as the double rarefaction wave problem,the Sedov blast wave problem,and the Leblanc problem with a normal CFL number.Extensive numerical results are provided to illustrate the good performance of the new finite difference MWENO schemes.展开更多
In the context of global climate change and rapid urbanization,climate governance has become one of the unavoidable challenges of human society.Therefore,climate engineering is increasingly mentioned in the internatio...In the context of global climate change and rapid urbanization,climate governance has become one of the unavoidable challenges of human society.Therefore,climate engineering is increasingly mentioned in the international climate negotiations.For solar radiation management with the most controversy in climate engineering method,based on two scenarios of climate engineering (G4) and non climate engineering (RCP4.5) of BNU-ESM model,95% and 99% percentiles of daily rainfall data during 2010-2099 were taken as thresholds of heavy rainfall and extreme rainfall events.The data of over threshold sampling (POT) were fitted by Weibull distribution to diagnose the heavy rainfall and extreme rainfall in 10,20,50 and 100 years of return period.The results showed that:in two scenarios,strength of heavy rainfall and extreme rainfall enhanced with return period increased,and they showed a southeast high-northwest low spatial characteristics.Climate engineering,in general,contributes to the increase in heavy rainfall and extreme rainfall in China,as well as spatial heterogeneity,which represents the suppression of heavy rainfall and extreme rainfall in parts of the country.This research is of great significance for the future global climate control and regional climate adaptation.展开更多
高速公路分流区作为典型的交织区域,容易发生急刹车、急变道等危险驾驶行为,这些行为往往会引发严重的交通冲突。为有效评估高速公路分流区的安全水平,深入探讨了冲突数据的优化问题,提出了一种融合冲突可能性和严重性的高速公路分流区...高速公路分流区作为典型的交织区域,容易发生急刹车、急变道等危险驾驶行为,这些行为往往会引发严重的交通冲突。为有效评估高速公路分流区的安全水平,深入探讨了冲突数据的优化问题,提出了一种融合冲突可能性和严重性的高速公路分流区冲突数据集筛选方法及极值建模应用。在冲突可能性方面,以碰撞时间差(Time Difference to Collision,TDTC)为指标,探究了高速公路分流区车辆碰撞的3种典型场景,并计算出冲突事件的时间阈值;在冲突严重性方面,引入Delta-V来筛选出具有潜在人员伤亡后果的冲突事件。将该融合数据集与传统仅考虑冲突可能性的单一数据集进行对比,并通过构建区组极值模型进行安全评估。结果表明:基于融合数据集构建的极值模型,冲突极值的重现水平结果平均绝对误差为0.046,均方根误差为0.058,其估计精度和实际冲突的拟合效果均优于传统数据集;使用极值模型对各分流区的碰撞频次进行了预测分析,发现其评估可靠性和事故预测结果更加符合实际冲突情况,提升了事故预测的可靠性。融合冲突可能性和严重性的高速公路分流区冲突数据集筛选方法可以为高速公路分流区安全评估模型的精度提升提供新的思路。展开更多
运行数据显示全光纤电流互感器(fiber optic current transformer,FOCT)在极端环境下(温度为–45~85℃、振动加速度>15 m/s^(2))故障概率明显偏高,因此研究极端环境对FOCT性能的影响十分必要。在分析FOCT工作原理基础上,重点讨论了F...运行数据显示全光纤电流互感器(fiber optic current transformer,FOCT)在极端环境下(温度为–45~85℃、振动加速度>15 m/s^(2))故障概率明显偏高,因此研究极端环境对FOCT性能的影响十分必要。在分析FOCT工作原理基础上,重点讨论了FOCT核心模块的结构特征及极端环境的影响,并建立FOCT传变模型。根据FOCT真实工作环境,分析了极端环境对其测量准确性的影响。结果表明:温度的升高、光纤长度的增加、振动加速度的变大,都会使FOCT比差增大,测量精度下降。特别是在极端环境下,测量误差较大,无法满足0.2S级测量准确度的要求。为验证模型的可靠性,开展了温度和振动影响试验。针对现有试验缺乏对极端环境的考核,提出增加测点的温度试验方法和增加振动响应试验及振动耐久试验的振动试验方法。试验结果与仿真结果对比表明:两者结果具有一致性,偏差电流波形变化趋势比较一致。该研究为FOCT可靠性问题提供有益参考。展开更多
基金Project(51178100)supported by the National Natural Science Foundation of ChinaProject(1105007001)supported by the Foundation of the Priority Academic Development Program of Higher Education Institute of Jiangsu Province,ChinaProject(3205001205)supported by the Teaching and Research Foundation for Excellent Young Teachers of Southeast University,China
文摘The extreme temperature differences in fiat steel box girder of a cable-stayed bridge were studied.Firstly,by using the long-term measurement data collected by the structural health monitoring system installed on the Runyang Cable-stayed Bridge,the daily variations as well as seasonal ones of measured temperature differences in the box girder cross-section area were summarized.The probability distribution models of temperature differences were further established and the extreme temperature differences were estimated with a return period of 100 years.Finally,the temperature difference models in cross-section area were proposed for bridge thermal design.The results show that horizontal temperature differences in top plate and vertical temperature differences between top plate and bottom plate are considerable.All the positive and negative temperature differences can be described by the weighted sum of two Weibull distributions.The maximum positive and negative horizontal temperature differences in top plate are 10.30 ℃ and -13.80 ℃,respectively.And the maximum positive and negative vertical temperature differences between top plate and bottom plate are 17.30 ℃ and-3.70 ℃,respectively.For bridge thermal design,there are two vertical temperature difference models between top plate and bottom plate,and six horizontal temperature difference models in top plate.
文摘Extrerae case formulation(ECF) was first put forward by Pomerantz in 1986 and is thought to be a general linguistic phenomenon in daily conversation.Since previous studies have manifested that linguistic gender difference do exist in the conversation,whether there is any difference in the use of extreme case formulations caused by different gender becomes a considerable subject.In this paper,this subject is studied based on the corpus of lines of Friends.The quantitative analysis is mainly applied with the help of the software Antconc to get the number and proportion of extreme case respectively used by male and female.The statistics shows that gender difference do exist in the use of extreme case.The number of extreme case used by female is basically more than men under the condition that the extreme cases are used in 3 ways and 4 kinds of activities that were summarized by Pomerantz.Besides,there are some limitations in this paper,the data is not widely covered and the reason of the gender difference is not thoroughly investigated.Therefore,the study of the linguistic gender difference in the respect of extreme cases still has a long way to go.
基金the NSFC grant 11872210 and the Science Challenge Project,No.TZ2016002the NSFC Grant 11926103 when he visited Tianyuan Mathematical Center in Southeast China,Xiamen 361005,Fujian,Chinathe NSFC Grant 12071392 and the Science Challenge Project,No.TZ2016002.
文摘In this paper,a new type of finite difference mapped weighted essentially non-oscillatory(MWENO)schemes with unequal-sized stencils,such as the seventh-order and ninthorder versions,is constructed for solving hyperbolic conservation laws.For the purpose of designing increasingly high-order finite difference WENO schemes,the equal-sized stencils are becoming more and more wider.The more we use wider candidate stencils,the bigger the probability of discontinuities lies in all stencils.Therefore,one innovation of these new WENO schemes is to introduce a new splitting stencil methodology to divide some fourpoint or five-point stencils into several smaller three-point stencils.By the usage of this new methodology in high-order spatial reconstruction procedure,we get different degree polynomials defined on these unequal-sized stencils,and calculate the linear weights,smoothness indicators,and nonlinear weights as specified in Jiang and Shu(J.Comput.Phys.126:202228,1996).Since the difference between the nonlinear weights and the linear weights is too big to keep the optimal order of accuracy in smooth regions,another crucial innovation is to present the new mapping functions which are used to obtain the mapped nonlinear weights and decrease the difference quantity between the mapped nonlinear weights and the linear weights,so as to keep the optimal order of accuracy in smooth regions.These new MWENO schemes can also be applied to compute some extreme examples,such as the double rarefaction wave problem,the Sedov blast wave problem,and the Leblanc problem with a normal CFL number.Extensive numerical results are provided to illustrate the good performance of the new finite difference MWENO schemes.
基金Supported by the National Basic Research Program of China(2018YFC0806900)the National Natural Science Foundation of China(41801064,71790611)the Central Asia Atmospheric Science Research Fund(CAAS201804)
文摘In the context of global climate change and rapid urbanization,climate governance has become one of the unavoidable challenges of human society.Therefore,climate engineering is increasingly mentioned in the international climate negotiations.For solar radiation management with the most controversy in climate engineering method,based on two scenarios of climate engineering (G4) and non climate engineering (RCP4.5) of BNU-ESM model,95% and 99% percentiles of daily rainfall data during 2010-2099 were taken as thresholds of heavy rainfall and extreme rainfall events.The data of over threshold sampling (POT) were fitted by Weibull distribution to diagnose the heavy rainfall and extreme rainfall in 10,20,50 and 100 years of return period.The results showed that:in two scenarios,strength of heavy rainfall and extreme rainfall enhanced with return period increased,and they showed a southeast high-northwest low spatial characteristics.Climate engineering,in general,contributes to the increase in heavy rainfall and extreme rainfall in China,as well as spatial heterogeneity,which represents the suppression of heavy rainfall and extreme rainfall in parts of the country.This research is of great significance for the future global climate control and regional climate adaptation.
文摘高速公路分流区作为典型的交织区域,容易发生急刹车、急变道等危险驾驶行为,这些行为往往会引发严重的交通冲突。为有效评估高速公路分流区的安全水平,深入探讨了冲突数据的优化问题,提出了一种融合冲突可能性和严重性的高速公路分流区冲突数据集筛选方法及极值建模应用。在冲突可能性方面,以碰撞时间差(Time Difference to Collision,TDTC)为指标,探究了高速公路分流区车辆碰撞的3种典型场景,并计算出冲突事件的时间阈值;在冲突严重性方面,引入Delta-V来筛选出具有潜在人员伤亡后果的冲突事件。将该融合数据集与传统仅考虑冲突可能性的单一数据集进行对比,并通过构建区组极值模型进行安全评估。结果表明:基于融合数据集构建的极值模型,冲突极值的重现水平结果平均绝对误差为0.046,均方根误差为0.058,其估计精度和实际冲突的拟合效果均优于传统数据集;使用极值模型对各分流区的碰撞频次进行了预测分析,发现其评估可靠性和事故预测结果更加符合实际冲突情况,提升了事故预测的可靠性。融合冲突可能性和严重性的高速公路分流区冲突数据集筛选方法可以为高速公路分流区安全评估模型的精度提升提供新的思路。
文摘运行数据显示全光纤电流互感器(fiber optic current transformer,FOCT)在极端环境下(温度为–45~85℃、振动加速度>15 m/s^(2))故障概率明显偏高,因此研究极端环境对FOCT性能的影响十分必要。在分析FOCT工作原理基础上,重点讨论了FOCT核心模块的结构特征及极端环境的影响,并建立FOCT传变模型。根据FOCT真实工作环境,分析了极端环境对其测量准确性的影响。结果表明:温度的升高、光纤长度的增加、振动加速度的变大,都会使FOCT比差增大,测量精度下降。特别是在极端环境下,测量误差较大,无法满足0.2S级测量准确度的要求。为验证模型的可靠性,开展了温度和振动影响试验。针对现有试验缺乏对极端环境的考核,提出增加测点的温度试验方法和增加振动响应试验及振动耐久试验的振动试验方法。试验结果与仿真结果对比表明:两者结果具有一致性,偏差电流波形变化趋势比较一致。该研究为FOCT可靠性问题提供有益参考。
