Based on the Simplified Bishop Method, the minimum safety factor of ice slope both with and without tension cracks is calculated in combination with triaxial compression tests. It is found that there exists a critical...Based on the Simplified Bishop Method, the minimum safety factor of ice slope both with and without tension cracks is calculated in combination with triaxial compression tests. It is found that there exists a critical depth for each crack. Then, factors influencing ice slope stability such as slope ratio, slope height, ice cohesion, internal friction angle, unit weight and temperature were analyzed. Meanwhile, a regression equation between the aforementioned factors and safety factor is obtained, with which sensitivity analysis is carried out. The performance function is built in combination with random distribution of physical and mechanical parameters to analyze the reliability index. The Advanced First Order Second Moment Method is employed on the solution to the perfor- mance function. The one-way coupling system of ice slope stability is therefore formed based on safety factor and reliability index. Finally, an illustrated example of ice slope is provided, which shows that failure probability is relatively high, up to 6.18%, alt- hough safety factor is 2.77. Thus, it is objective and reasonable to apply the coupled system method to the slope stability rating.展开更多
目的研究1990—2019年由社会经济发展水平差异所致的全球口腔癌疾病负担不平等情况,为制定有效的预防和控制政策提供科学依据。方法本研究的疾病负担数据来源于2019年全球疾病负担研究,人类发展指数(human development index,HDI)来自于...目的研究1990—2019年由社会经济发展水平差异所致的全球口腔癌疾病负担不平等情况,为制定有效的预防和控制政策提供科学依据。方法本研究的疾病负担数据来源于2019年全球疾病负担研究,人类发展指数(human development index,HDI)来自于《2020年人类发展报告》,采用线性回归分析年龄标化的伤残调整寿命年(disability-adjusted life yeas,DALY)率与HDI的相关性,使用不平等斜率指数(slope index of inequality,SII)和集中指数(concentration index,CI)评价1990—2019年全球口腔癌疾病负担的不公平情况及发展趋势。结果本研究共纳入189个国家和地区,2019年口腔癌DALY率为46.61[IQR(30.70,64.97)],线性回归结果显示口腔癌DALY率与HDI水平呈显著负相关(ρ=-0.06,P<0.001)。口腔癌DALY负担在189个国家和地区间表现出显著的不平等性,2019年SII值为-107.16[95%CI(-127.60,-90.69)],1990—2019年SII值<0且绝对值呈上升趋势;2019年口腔癌CI值为-1.35[95%CI(-2.88,-1.01)],1990—2015年CI值>0且呈下降趋势,而2016—2019年CI值<0且绝对值呈上升趋势。结论1990—2019年全球口腔癌疾病负担存在明显的社会不公平现象,口腔癌疾病负担更集中在低社会经济发展水平国家,且随着时间变化呈现出加重趋势。因此,未来应注重发展中国家的医疗资源分配问题,采取更有针对性的措施,有效控制口腔癌疾病负担的不平等现状。展开更多
2020年超长梅雨期内的持续强降雨,导致安徽省发生全域性洪涝灾害,为了快速、准确地提取洪涝淹没范围,为防汛救灾提供科学支撑,选取安徽境内巢湖流域和淮河流域的灾前和灾中Sentinel-1A数据,首先,在快速预处理基础上,采用双极化水体指数(...2020年超长梅雨期内的持续强降雨,导致安徽省发生全域性洪涝灾害,为了快速、准确地提取洪涝淹没范围,为防汛救灾提供科学支撑,选取安徽境内巢湖流域和淮河流域的灾前和灾中Sentinel-1A数据,首先,在快速预处理基础上,采用双极化水体指数(Sentinel-1A dual-polarized water index,SDWI)法,并结合地形因子对平原和山区分别提取水体信息,建立一套洪水淹没区监测流程;然后通过该流程利用灾前、灾中两期合成孔径雷达数据提取2020年7月27日巢湖流域、淮河流域行蓄洪区洪水淹没范围。结果显示:SDWI比直接用后向散射系数提取水体具有优势;7月27日巢湖流域洪水淹没区面积为524.8 km^(2),其中受洪灾较重的是白石天河子流域,西河子流域次之;淮河流域安徽境内行蓄洪区,沿淮的4个地市淹没面积从大到小依次为淮南市、阜阳市、六安市、蚌埠市。研究表明,基于Sentinel-1A数据,采用SDWI和地形因子建立的洪水淹没区监测流程对平原和山区都具有较好的准确性、适用性,且具有较高的时效性,便于及时开展洪水灾害监测。展开更多
The combination of Morgenstern-Price Method (MPM) with Response Surface Method (RSM) improves the conventional RSM by replacing Finite-Element Method (FEM) with MPM, which is a type of reliability analysis method--RSM...The combination of Morgenstern-Price Method (MPM) with Response Surface Method (RSM) improves the conventional RSM by replacing Finite-Element Method (FEM) with MPM, which is a type of reliability analysis method--RSM based on MPM, and makes the computing process simpler. The stability of the slope was re-evaluated by use of Monte Carlo method (MCM) and the result contrasted with the fore is the conclusion. The reliability analysis of the artificial slope in Donggang Power Station was carried on, and obtained the reliable characteristics, which provided basis for the project.展开更多
An experimental study of regular wave and irregular wave breaking is performed on a gentle slope of 1:200, In the experiment, asymmetry of wave profile is analyzed to determine its effect on wave breaker indices and t...An experimental study of regular wave and irregular wave breaking is performed on a gentle slope of 1:200, In the experiment, asymmetry of wave profile is analyzed to determine its effect on wave breaker indices and to explain the difference between Goda and Nelson about the breaker indices of regular waves on very mild slopes. The study shows that the breaker index of irregular waves is under less influence of bottom slope l, relative water depth d/ L-0 and the asymmetry of wave profile than that of regular waves. The breaker index of regular waves from Goda may be used in the case of irregular waves, while the coefficient A should be 0.15. The ratio of irregular wavelength to the length calculated by linear wave theory is 0.74. Analysis is also made on the waveheight damping coefficient of regular waves after breaking and on the breaking probability of large irregular waves.展开更多
基金supported by the Western Project Program of the Chinese Academy of Sciences (KZCX2-XB3-19)the National key Basic Research Program of China (973 Program:No.2012CB026102)+4 种基金the Program for Innovative Research Group of Natural Science Foundation of China (No. 41121061)the Foundation of State Key Laboratory of Frozen Soil Engineering(SKLFSE-ZY-03)the foundation of State Key Laboratory of Frozen Soil Engineering (SKLFSE-ZY-03)the National Natural Science Foundation of China (40971045,41171060)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-EW-QN301)
文摘Based on the Simplified Bishop Method, the minimum safety factor of ice slope both with and without tension cracks is calculated in combination with triaxial compression tests. It is found that there exists a critical depth for each crack. Then, factors influencing ice slope stability such as slope ratio, slope height, ice cohesion, internal friction angle, unit weight and temperature were analyzed. Meanwhile, a regression equation between the aforementioned factors and safety factor is obtained, with which sensitivity analysis is carried out. The performance function is built in combination with random distribution of physical and mechanical parameters to analyze the reliability index. The Advanced First Order Second Moment Method is employed on the solution to the perfor- mance function. The one-way coupling system of ice slope stability is therefore formed based on safety factor and reliability index. Finally, an illustrated example of ice slope is provided, which shows that failure probability is relatively high, up to 6.18%, alt- hough safety factor is 2.77. Thus, it is objective and reasonable to apply the coupled system method to the slope stability rating.
文摘目的研究1990—2019年由社会经济发展水平差异所致的全球口腔癌疾病负担不平等情况,为制定有效的预防和控制政策提供科学依据。方法本研究的疾病负担数据来源于2019年全球疾病负担研究,人类发展指数(human development index,HDI)来自于《2020年人类发展报告》,采用线性回归分析年龄标化的伤残调整寿命年(disability-adjusted life yeas,DALY)率与HDI的相关性,使用不平等斜率指数(slope index of inequality,SII)和集中指数(concentration index,CI)评价1990—2019年全球口腔癌疾病负担的不公平情况及发展趋势。结果本研究共纳入189个国家和地区,2019年口腔癌DALY率为46.61[IQR(30.70,64.97)],线性回归结果显示口腔癌DALY率与HDI水平呈显著负相关(ρ=-0.06,P<0.001)。口腔癌DALY负担在189个国家和地区间表现出显著的不平等性,2019年SII值为-107.16[95%CI(-127.60,-90.69)],1990—2019年SII值<0且绝对值呈上升趋势;2019年口腔癌CI值为-1.35[95%CI(-2.88,-1.01)],1990—2015年CI值>0且呈下降趋势,而2016—2019年CI值<0且绝对值呈上升趋势。结论1990—2019年全球口腔癌疾病负担存在明显的社会不公平现象,口腔癌疾病负担更集中在低社会经济发展水平国家,且随着时间变化呈现出加重趋势。因此,未来应注重发展中国家的医疗资源分配问题,采取更有针对性的措施,有效控制口腔癌疾病负担的不平等现状。
文摘2020年超长梅雨期内的持续强降雨,导致安徽省发生全域性洪涝灾害,为了快速、准确地提取洪涝淹没范围,为防汛救灾提供科学支撑,选取安徽境内巢湖流域和淮河流域的灾前和灾中Sentinel-1A数据,首先,在快速预处理基础上,采用双极化水体指数(Sentinel-1A dual-polarized water index,SDWI)法,并结合地形因子对平原和山区分别提取水体信息,建立一套洪水淹没区监测流程;然后通过该流程利用灾前、灾中两期合成孔径雷达数据提取2020年7月27日巢湖流域、淮河流域行蓄洪区洪水淹没范围。结果显示:SDWI比直接用后向散射系数提取水体具有优势;7月27日巢湖流域洪水淹没区面积为524.8 km^(2),其中受洪灾较重的是白石天河子流域,西河子流域次之;淮河流域安徽境内行蓄洪区,沿淮的4个地市淹没面积从大到小依次为淮南市、阜阳市、六安市、蚌埠市。研究表明,基于Sentinel-1A数据,采用SDWI和地形因子建立的洪水淹没区监测流程对平原和山区都具有较好的准确性、适用性,且具有较高的时效性,便于及时开展洪水灾害监测。
文摘The combination of Morgenstern-Price Method (MPM) with Response Surface Method (RSM) improves the conventional RSM by replacing Finite-Element Method (FEM) with MPM, which is a type of reliability analysis method--RSM based on MPM, and makes the computing process simpler. The stability of the slope was re-evaluated by use of Monte Carlo method (MCM) and the result contrasted with the fore is the conclusion. The reliability analysis of the artificial slope in Donggang Power Station was carried on, and obtained the reliable characteristics, which provided basis for the project.
基金National Natural Science Foundation of China(Grant No.49876026) Research Foundation for Development of Engineering Technical Code of Ministry of Communication
文摘An experimental study of regular wave and irregular wave breaking is performed on a gentle slope of 1:200, In the experiment, asymmetry of wave profile is analyzed to determine its effect on wave breaker indices and to explain the difference between Goda and Nelson about the breaker indices of regular waves on very mild slopes. The study shows that the breaker index of irregular waves is under less influence of bottom slope l, relative water depth d/ L-0 and the asymmetry of wave profile than that of regular waves. The breaker index of regular waves from Goda may be used in the case of irregular waves, while the coefficient A should be 0.15. The ratio of irregular wavelength to the length calculated by linear wave theory is 0.74. Analysis is also made on the waveheight damping coefficient of regular waves after breaking and on the breaking probability of large irregular waves.
