The deformation prediction models of Wuqiangxi concrete gravity dam are developed,including two statistical models and a deep learning model.In the statistical models,the reliable monitoring data are firstly determine...The deformation prediction models of Wuqiangxi concrete gravity dam are developed,including two statistical models and a deep learning model.In the statistical models,the reliable monitoring data are firstly determined with Lahitte criterion;then,the stepwise regression and partial least squares regression models for deformation prediction of concrete gravity dam are constructed in terms of the reliable monitoring data,and the factors of water pressure,temperature and time effect are considered in the models;finally,according to the monitoring data from 2006 to 2020 of five typical measuring points including J23(on dam section 24^(#)),J33(on dam section 4^(#)),J35(on dam section 8^(#)),J37(on dam section 12^(#)),and J39(on dam section 15^(#))located on the crest of Wuqiangxi concrete gravity dam,the settlement curves of the measuring points are obtained with the stepwise regression and partial least squares regression models.A deep learning model is developed based on long short-term memory(LSTM)recurrent neural network.In the LSTM model,two LSTMlayers are used,the rectified linear unit function is adopted as the activation function,the input sequence length is 20,and the random search is adopted.The monitoring data for the five typical measuring points from 2006 to 2017 are selected as the training set,and the monitoring data from 2018 to 2020 are taken as the test set.From the results of case study,we can find that(1)the good fitting results can be obtained with the two statistical models;(2)the partial least squares regression algorithm can solve the model with high correlation factors and reasonably explain the factors;(3)the prediction accuracy of the LSTM model increases with increasing the amount of training data.In the deformation prediction of concrete gravity dam,the LSTM model is suggested when there are sufficient training data,while the partial least squares regression method is suggested when the training data are insufficient.展开更多
Steady-state heat transfer problems in heterogeneous solid are simulated by developing an adaptive extended isogeometric analysis(XIGA)method based on locally refined non-uniforms rational B-splines(LR NURBS).In the X...Steady-state heat transfer problems in heterogeneous solid are simulated by developing an adaptive extended isogeometric analysis(XIGA)method based on locally refined non-uniforms rational B-splines(LR NURBS).In the XIGA,the LR NURBS,which have a simple local refinement algorithm and good description ability for complex geometries,are employed to represent the geometry and discretize the field variables;and some special enrichment functions are introduced into the approximation of temperature field,thus the computational mesh is independent of the material interfaces,which are described with the level setmethod.Similar to the approximation of temperature field,a temperature gradient recovery technique for heterogeneous media is proposed,and based on the Zienkiewicz–Zhu recovery technique a posteriori error estimator is defined to automatically identify the locally refined regions.The convergence and performance properties of the developed method are verified by using three numerical examples.The numerical results show that(1)The convergence speed of the adaptive local refinement is faster than that of the uniform global refinement;(2)The convergence rate of the high-order basis functions is faster than that of the low-order basis functions;and(3)The existing inclusions change the local distributions of the temperature,and the extreme values of the temperature gradients take place around the inclusion interfaces.展开更多
Numerical analysis of unsteady heat transfer problems with complex geometries by the isogeometric boundary element method(IGABEM)is presented.The IGABEM possesses many desirable merits and features,for instance,(a)exa...Numerical analysis of unsteady heat transfer problems with complex geometries by the isogeometric boundary element method(IGABEM)is presented.The IGABEM possesses many desirable merits and features,for instance,(a)exactly represented arbitrarily complex geometries,and higher-order continuity due to non-uniform rational B-splines(NURBS)shape functions;(b)using NURBS for both field approximation and geometric description;(c)directly utilizing geometry data from computer-aided design(CAD);and(d)only boundary discretization.The formulation of IGABEM for unsteady heat transfer is derived.The domain discretization in terms of IGABEM for unsteady heat transfer is required as that in traditional BEM.The internal values however are obtained with the analytical formula according to the values on the boundaries,and its computations are therefore mainly dependent on the discretization of the boundaries.The coordinates of internal control points are obtained with the coordinates of control points on the boundaries using Coons body interpolation method.The developed approach is tested with several numerical examples from simple to complicated geometries.Good agreement is gained with reference solutions derived from either analytical or finite element methods.展开更多
On 6 February 2023,two 7.8 magnitude earthquakes consecutively hit south-central Türkiye,causing great concern from all governments,the United Nations,academia,and all sectors of society.Analyses indicate that th...On 6 February 2023,two 7.8 magnitude earthquakes consecutively hit south-central Türkiye,causing great concern from all governments,the United Nations,academia,and all sectors of society.Analyses indicate that there is also a high possibility of strong earthquakes with a magnitude of 7.8 or above occurring in the western region of China in the coming years.China is a country that is highly susceptible to catastrophic disasters such as earthquakes,floods,and other natural calamities,which can cause significant damages to both human life and property,as well as widespread impacts on the society.Currently,China's capacity for disaster prevention and control is still limited.In order to effectively reduce the impact of catastrophic disasters,ensure the safety of people's lives and property to the greatest extent possible,maintain social stability in high-risk areas,and ensure high-quality and sustainable regional development,it is urgent to improve the seismic resistance level of houses and critical infrastructure in high earthquake risk zones and increase the earthquake-resistant design level of houses in high-risk fault areas with frequent seismic activities;significantly enhance the ability to defend against extreme weather and ocean disasters in economically developed areas along the southeastern coast,as well as the level of fortification in response to extreme meteorological and hydrological disasters of coastal towns/cities and key infrastructure;vigorously enhance the emergency response capacity and disaster risk prevention level in western and ethnic minority regions;comprehensively improve the defense level of residential areas and major infrastructure in high geological hazard risk zones with flash floods,landslides,and mudslides;systematically promote national disaster prevention and mitigation education;and greatly enhance the societal disaster risk reduction ability,including catastrophic insurance.展开更多
Evaluation of the economic costs and benefits of flood disaster risk management projects is crucial.However,current costbenefit analyses(CBA) often lack reliable estimates of the expected loss reduction from flood con...Evaluation of the economic costs and benefits of flood disaster risk management projects is crucial.However,current costbenefit analyses(CBA) often lack reliable estimates of the expected loss reduction from flood control measures and ignore quantitative assessments of resettlement.To address these limitations,this study incorporated a probabilistic risk analysis method and quantitative resettlement benefits assessment into the CBA framework,using the Wuxikou Integrated Flood Management Project(WIFMP) in Jiangxi Province,China,as a case study.The direct economic benefits of flood control were estimated by integrating hydrological statistics,numerical flood inundation simulation,and quantitative damage analysis with exposure and vulnerability data.Furthermore,the resettlement benefits were quantified by measuring the annual income growth of migrants based on assumptions about household employment.Our analysis shows that the total WIFMP investment is RMB 3546.1 million yuan(USD 1=RMB 6.976 yuan),including loan principal and interest of 244.4 million yuan,and operations and maintenance of 605.5 million yuan at 2020 prices.Annual project benefits are estimated at 351.3 million yuan in flood risk reduction,155.7-191.9 million yuan from increased resettlement income,and 42.7 million yuan in power and water revenues.Considering the costs and benefits across the entire project lifecycle,the internal rate of return ranges from 13.7 to 14.2%,and the net present value ranges from 31.8 to 352.6 billion yuan.Through improved benefit estimation methodology,this research enables a more reliable and holistic evaluation of costs and benefits for flood risk management projects.It provides insights for policymakers and practitioners involved in similar projects,contributing to more informed decision making and better allocation of resources in flood disaster risk management.展开更多
Tropical cyclones(TCs) cause catastrophic loss in many coastal areas of the world. TC wind hazard maps can play an important role in disaster management. A good representation of local factors reflecting the effects o...Tropical cyclones(TCs) cause catastrophic loss in many coastal areas of the world. TC wind hazard maps can play an important role in disaster management. A good representation of local factors reflecting the effects of spatially heterogeneous terrain and land cover is critical to evaluation of TC wind hazard. Very few studies, however,provide global wind hazard assessment results that consider detailed local effects. In this study, the wind fields of historical TCs were simulated with parametric models in which the planetary boundary layer models explicitly integrate local effects at 1 km resolution. The topographic effects for eight wind directions were quantified over four types of terrain(ground, escarpment, ridge, and valley),and the surface roughness lengths were estimated from a global land cover map. The missing TC parameters in the best track datasets were reconstructed with local regression models. Finally, an example of a wind hazard map in the form of wind speeds under a 100-year return period and corresponding uncertainties was created based on a statistical analysis of reconstructed historical wind fields over seven of the world's ocean basins.展开更多
To achieve sustainable development, understanding of the impact of global environmental change on natural resources and the frequency, intensity, and spatial-temporal patterns of all kinds of hazards should be advance...To achieve sustainable development, understanding of the impact of global environmental change on natural resources and the frequency, intensity, and spatial-temporal patterns of all kinds of hazards should be advanced. In recent years, severe losses of human lives and property have been caused by very large-scale natural hazards all over the world, such as the freezing rain and snowstorm disaster in China in 2008, Typhoon Sidr in Bangladesh in 2007, and Hurricane Katrina in the United States in 2005. Strengthening the study on integrated disaster risk governance has become a pressing issue of sustainable development. Supported by the Chinese National Committee for the International Human Dimensions Program on Global Environmental Change(CNC-IHDP), its Working Group for Risk Governance proposed to the IHDP in 2006 to launch a new international research project on integrated risk governance(IRG) in the context of global environmental change. The IRG-Project was accepted by the IHDP Scientific Committee as a pilot science project in 2008 and was approved in 2010 as a full IHDP core science project under the Strategic Plan 2007–2015. The research foci of this international science project will be on the issues of science, technology, and management of integrated disaster risk governance based on case comparisons around the world, in order to advance the theories and methodologies of integrated disaster risk governance and to improve the practices of integrated disaster reduction in the real world.展开更多
In this article,we recall the United Nations’30-year journey in disaster risk reduction strategy and framework,review the latest progress and key scientific and technological questions related to the United Nations d...In this article,we recall the United Nations’30-year journey in disaster risk reduction strategy and framework,review the latest progress and key scientific and technological questions related to the United Nations disaster risk reduction initiatives,and summarize the framework and contents of disaster risk science research.The object of disaster risk science research is the"disaster system"consisting of hazard,the geographical environment,and exposed units,with features of regionality,interconnectedness,coupling,and complexity.Environmental stability,hazard threat,and socioeconomic vulnerability together determine the way that disasters are formed,establish the spatial extent of disaster impact,and generate the scale of losses.In the formation of a disaster,a conducive environment is the prerequisite,a hazard is the necessary condition,and socioeconomic exposure is the sufficient condition.The geographical environment affects local hazard intensity and therefore can change the pattern of loss distribution.Regional multi-hazard,disaster chain,and disaster compound could induce complex impacts,amplifying or attenuating hazard intensity and changing the scope of affected areas.In the light of research progress,particularly in the context of China,we propose a threelayer disaster risk science disciplinary structure,which contains three pillars(disaster science,disaster technology,and disaster governance),nine core areas,and 27 research fields.Based on these elements,we discuss the frontiers in disaster risk science research.展开更多
Climatic conditions have important influences on human life and the sustainable development of economies and societies. Climate varies in space and time. People have always lived with climate diversity, and the two in...Climatic conditions have important influences on human life and the sustainable development of economies and societies. Climate varies in space and time. People have always lived with climate diversity, and the two influence each other. The degree of mutual influence differs at different spatial and temporal scales. Since the industrial revolution, the human effect on climate has gradually increased, and expanded from local to global scale. To allow people to live in harmony with nature and prevent disaster risks, the International Human Dimensions Program on Global Environmental Change(IHDP) announced the implementation of a scientific plan aimed at discussing risk governance, especially with respect to large-scale disaster risks, under global environmental change conditions(IHDP—Integrated Risk Governance Project, 2009–2019). As the initiator of this scientific plan, the authors propose a strategic development framework for living with global climate diversity considering a series of large-scale disasters in China and around the world in recent years and relevant experiences and lessons, and offer suggestions for the global mechanism of dealing with climate change risks.展开更多
A new computational approach that combines the extended finite element method associated with variable-node elements and cohesive zone model is developed.By using a new enriched technique based on sign function,the pr...A new computational approach that combines the extended finite element method associated with variable-node elements and cohesive zone model is developed.By using a new enriched technique based on sign function,the proposed model using 4-node quadrilateral elements can eliminate the blending element problem.It also allows modeling the equal stresses at both sides of the crack in the crack-tip as assumed in the cohesive model,and is able to simulate the arbitrary crack-tip location.The multiscale mesh technique associated with variable-node elements and the arc-length method further improve the efficiency of the developed approach.The performance and accuracy of the present approach are illustrated through numerical experiments considering both mode-I and mixed-mode fracture in concrete.展开更多
Tropical cyclones(TCs)may cause severe impacts on the activities of coastal fishing vessels.Due to the unavailability or unacceptability of detailed Automatic Identification System(AIS)data that are capable of differe...Tropical cyclones(TCs)may cause severe impacts on the activities of coastal fishing vessels.Due to the unavailability or unacceptability of detailed Automatic Identification System(AIS)data that are capable of differentiating fishing activity from navigation,as well as the lack of detailed models and observation data of TC winds,few studies have provided quantitative and reliable assessment of the impacts of TCs on fishing activities.In this study,we modeled snapshots for the TC winds of 52 TCs over the Northwest Pacific(NWP)basin from 2013 to 2018,as well as daily fishing hours and daily hours of presence(hereafter“vessel hours”)of fishing vessels.Based on these data,the spatiotemporal pattern of fishing vessel activity over off-shore China was first analyzed and mapped.Then,a TC wind hazard index and absolute and relative impact indices were proposed to assess the impact of the 52 TCs on fishing and vessel hours.Their relationship was then fitted with the cumulative distribution function(CDF)of the log-normal distribution.The results show that in the 2013-2018 period,the most active fishing areas were located in the South China Sea.In each instance,an increase was first observed in the initial several years;then a decrease followed in the yearly total fishing hours per vessel in the remaining years.The relative impact index was significantly correlated to the TC wind hazard index proposed in this study.Based on the quantitative relationship between the specified TC hazard index and the impact indices,it is possible to implement a pre-cyclone rapid loss assessment due to TC avoidance in the future.展开更多
文摘The deformation prediction models of Wuqiangxi concrete gravity dam are developed,including two statistical models and a deep learning model.In the statistical models,the reliable monitoring data are firstly determined with Lahitte criterion;then,the stepwise regression and partial least squares regression models for deformation prediction of concrete gravity dam are constructed in terms of the reliable monitoring data,and the factors of water pressure,temperature and time effect are considered in the models;finally,according to the monitoring data from 2006 to 2020 of five typical measuring points including J23(on dam section 24^(#)),J33(on dam section 4^(#)),J35(on dam section 8^(#)),J37(on dam section 12^(#)),and J39(on dam section 15^(#))located on the crest of Wuqiangxi concrete gravity dam,the settlement curves of the measuring points are obtained with the stepwise regression and partial least squares regression models.A deep learning model is developed based on long short-term memory(LSTM)recurrent neural network.In the LSTM model,two LSTMlayers are used,the rectified linear unit function is adopted as the activation function,the input sequence length is 20,and the random search is adopted.The monitoring data for the five typical measuring points from 2006 to 2017 are selected as the training set,and the monitoring data from 2018 to 2020 are taken as the test set.From the results of case study,we can find that(1)the good fitting results can be obtained with the two statistical models;(2)the partial least squares regression algorithm can solve the model with high correlation factors and reasonably explain the factors;(3)the prediction accuracy of the LSTM model increases with increasing the amount of training data.In the deformation prediction of concrete gravity dam,the LSTM model is suggested when there are sufficient training data,while the partial least squares regression method is suggested when the training data are insufficient.
文摘Steady-state heat transfer problems in heterogeneous solid are simulated by developing an adaptive extended isogeometric analysis(XIGA)method based on locally refined non-uniforms rational B-splines(LR NURBS).In the XIGA,the LR NURBS,which have a simple local refinement algorithm and good description ability for complex geometries,are employed to represent the geometry and discretize the field variables;and some special enrichment functions are introduced into the approximation of temperature field,thus the computational mesh is independent of the material interfaces,which are described with the level setmethod.Similar to the approximation of temperature field,a temperature gradient recovery technique for heterogeneous media is proposed,and based on the Zienkiewicz–Zhu recovery technique a posteriori error estimator is defined to automatically identify the locally refined regions.The convergence and performance properties of the developed method are verified by using three numerical examples.The numerical results show that(1)The convergence speed of the adaptive local refinement is faster than that of the uniform global refinement;(2)The convergence rate of the high-order basis functions is faster than that of the low-order basis functions;and(3)The existing inclusions change the local distributions of the temperature,and the extreme values of the temperature gradients take place around the inclusion interfaces.
基金This work was supported by Natural Science Foundation of Jiangsu Province of China(BK20151070)The financial supports are gratefully acknowledged。
文摘Numerical analysis of unsteady heat transfer problems with complex geometries by the isogeometric boundary element method(IGABEM)is presented.The IGABEM possesses many desirable merits and features,for instance,(a)exactly represented arbitrarily complex geometries,and higher-order continuity due to non-uniform rational B-splines(NURBS)shape functions;(b)using NURBS for both field approximation and geometric description;(c)directly utilizing geometry data from computer-aided design(CAD);and(d)only boundary discretization.The formulation of IGABEM for unsteady heat transfer is derived.The domain discretization in terms of IGABEM for unsteady heat transfer is required as that in traditional BEM.The internal values however are obtained with the analytical formula according to the values on the boundaries,and its computations are therefore mainly dependent on the discretization of the boundaries.The coordinates of internal control points are obtained with the coordinates of control points on the boundaries using Coons body interpolation method.The developed approach is tested with several numerical examples from simple to complicated geometries.Good agreement is gained with reference solutions derived from either analytical or finite element methods.
基金founded by the Sixth Task of the Second Tibetan Plateau Scientific Expedition and Research Program(STEP),“Integrated Disaster Risk Prevention”(Grant No.2019QZKK0906)。
文摘On 6 February 2023,two 7.8 magnitude earthquakes consecutively hit south-central Türkiye,causing great concern from all governments,the United Nations,academia,and all sectors of society.Analyses indicate that there is also a high possibility of strong earthquakes with a magnitude of 7.8 or above occurring in the western region of China in the coming years.China is a country that is highly susceptible to catastrophic disasters such as earthquakes,floods,and other natural calamities,which can cause significant damages to both human life and property,as well as widespread impacts on the society.Currently,China's capacity for disaster prevention and control is still limited.In order to effectively reduce the impact of catastrophic disasters,ensure the safety of people's lives and property to the greatest extent possible,maintain social stability in high-risk areas,and ensure high-quality and sustainable regional development,it is urgent to improve the seismic resistance level of houses and critical infrastructure in high earthquake risk zones and increase the earthquake-resistant design level of houses in high-risk fault areas with frequent seismic activities;significantly enhance the ability to defend against extreme weather and ocean disasters in economically developed areas along the southeastern coast,as well as the level of fortification in response to extreme meteorological and hydrological disasters of coastal towns/cities and key infrastructure;vigorously enhance the emergency response capacity and disaster risk prevention level in western and ethnic minority regions;comprehensively improve the defense level of residential areas and major infrastructure in high geological hazard risk zones with flash floods,landslides,and mudslides;systematically promote national disaster prevention and mitigation education;and greatly enhance the societal disaster risk reduction ability,including catastrophic insurance.
基金funded by the National Key Research and Development Program of China(Grant No.2022YFC3006404-02).
文摘Evaluation of the economic costs and benefits of flood disaster risk management projects is crucial.However,current costbenefit analyses(CBA) often lack reliable estimates of the expected loss reduction from flood control measures and ignore quantitative assessments of resettlement.To address these limitations,this study incorporated a probabilistic risk analysis method and quantitative resettlement benefits assessment into the CBA framework,using the Wuxikou Integrated Flood Management Project(WIFMP) in Jiangxi Province,China,as a case study.The direct economic benefits of flood control were estimated by integrating hydrological statistics,numerical flood inundation simulation,and quantitative damage analysis with exposure and vulnerability data.Furthermore,the resettlement benefits were quantified by measuring the annual income growth of migrants based on assumptions about household employment.Our analysis shows that the total WIFMP investment is RMB 3546.1 million yuan(USD 1=RMB 6.976 yuan),including loan principal and interest of 244.4 million yuan,and operations and maintenance of 605.5 million yuan at 2020 prices.Annual project benefits are estimated at 351.3 million yuan in flood risk reduction,155.7-191.9 million yuan from increased resettlement income,and 42.7 million yuan in power and water revenues.Considering the costs and benefits across the entire project lifecycle,the internal rate of return ranges from 13.7 to 14.2%,and the net present value ranges from 31.8 to 352.6 billion yuan.Through improved benefit estimation methodology,this research enables a more reliable and holistic evaluation of costs and benefits for flood risk management projects.It provides insights for policymakers and practitioners involved in similar projects,contributing to more informed decision making and better allocation of resources in flood disaster risk management.
基金supported by the National Key Research and Development Program of China(No.2017YFA0604903)
文摘Tropical cyclones(TCs) cause catastrophic loss in many coastal areas of the world. TC wind hazard maps can play an important role in disaster management. A good representation of local factors reflecting the effects of spatially heterogeneous terrain and land cover is critical to evaluation of TC wind hazard. Very few studies, however,provide global wind hazard assessment results that consider detailed local effects. In this study, the wind fields of historical TCs were simulated with parametric models in which the planetary boundary layer models explicitly integrate local effects at 1 km resolution. The topographic effects for eight wind directions were quantified over four types of terrain(ground, escarpment, ridge, and valley),and the surface roughness lengths were estimated from a global land cover map. The missing TC parameters in the best track datasets were reconstructed with local regression models. Finally, an example of a wind hazard map in the form of wind speeds under a 100-year return period and corresponding uncertainties was created based on a statistical analysis of reconstructed historical wind fields over seven of the world's ocean basins.
基金The research project this article is based on is sponsored by the Inter national Cooperation Project of the Ministry of Science and Technology,“Global Climate Change and Catastrophe Governance”(2008DFA20640)the International(Regional)Exchange Project of the National Natural Science Foundation,“Case Study on Core Science Projects of IHDP-IRG”(40821140354).
文摘To achieve sustainable development, understanding of the impact of global environmental change on natural resources and the frequency, intensity, and spatial-temporal patterns of all kinds of hazards should be advanced. In recent years, severe losses of human lives and property have been caused by very large-scale natural hazards all over the world, such as the freezing rain and snowstorm disaster in China in 2008, Typhoon Sidr in Bangladesh in 2007, and Hurricane Katrina in the United States in 2005. Strengthening the study on integrated disaster risk governance has become a pressing issue of sustainable development. Supported by the Chinese National Committee for the International Human Dimensions Program on Global Environmental Change(CNC-IHDP), its Working Group for Risk Governance proposed to the IHDP in 2006 to launch a new international research project on integrated risk governance(IRG) in the context of global environmental change. The IRG-Project was accepted by the IHDP Scientific Committee as a pilot science project in 2008 and was approved in 2010 as a full IHDP core science project under the Strategic Plan 2007–2015. The research foci of this international science project will be on the issues of science, technology, and management of integrated disaster risk governance based on case comparisons around the world, in order to advance the theories and methodologies of integrated disaster risk governance and to improve the practices of integrated disaster reduction in the real world.
基金financially supported by the National Key Research and Development Program of China,“Global Change Risks of Population and Economic Systems Mechanisms and Assessments,”Grant No.2016YFA0602404。
文摘In this article,we recall the United Nations’30-year journey in disaster risk reduction strategy and framework,review the latest progress and key scientific and technological questions related to the United Nations disaster risk reduction initiatives,and summarize the framework and contents of disaster risk science research.The object of disaster risk science research is the"disaster system"consisting of hazard,the geographical environment,and exposed units,with features of regionality,interconnectedness,coupling,and complexity.Environmental stability,hazard threat,and socioeconomic vulnerability together determine the way that disasters are formed,establish the spatial extent of disaster impact,and generate the scale of losses.In the formation of a disaster,a conducive environment is the prerequisite,a hazard is the necessary condition,and socioeconomic exposure is the sufficient condition.The geographical environment affects local hazard intensity and therefore can change the pattern of loss distribution.Regional multi-hazard,disaster chain,and disaster compound could induce complex impacts,amplifying or attenuating hazard intensity and changing the scope of affected areas.In the light of research progress,particularly in the context of China,we propose a threelayer disaster risk science disciplinary structure,which contains three pillars(disaster science,disaster technology,and disaster governance),nine core areas,and 27 research fields.Based on these elements,we discuss the frontiers in disaster risk science research.
基金This paper is based on research supported by grants from the National Key Basic Research and Development Program:Global and China Environmental Risk and Its Adaptation Paradigms(2012CB955404)the International Science and Technology Cooperation Project from the Ministry of Science and Technology:Comparative Research on Integrate d Risk Governance Technology and Paradigms in Typical Vulnerable Area(S2012GR0231).
文摘Climatic conditions have important influences on human life and the sustainable development of economies and societies. Climate varies in space and time. People have always lived with climate diversity, and the two influence each other. The degree of mutual influence differs at different spatial and temporal scales. Since the industrial revolution, the human effect on climate has gradually increased, and expanded from local to global scale. To allow people to live in harmony with nature and prevent disaster risks, the International Human Dimensions Program on Global Environmental Change(IHDP) announced the implementation of a scientific plan aimed at discussing risk governance, especially with respect to large-scale disaster risks, under global environmental change conditions(IHDP—Integrated Risk Governance Project, 2009–2019). As the initiator of this scientific plan, the authors propose a strategic development framework for living with global climate diversity considering a series of large-scale disasters in China and around the world in recent years and relevant experiences and lessons, and offer suggestions for the global mechanism of dealing with climate change risks.
文摘A new computational approach that combines the extended finite element method associated with variable-node elements and cohesive zone model is developed.By using a new enriched technique based on sign function,the proposed model using 4-node quadrilateral elements can eliminate the blending element problem.It also allows modeling the equal stresses at both sides of the crack in the crack-tip as assumed in the cohesive model,and is able to simulate the arbitrary crack-tip location.The multiscale mesh technique associated with variable-node elements and the arc-length method further improve the efficiency of the developed approach.The performance and accuracy of the present approach are illustrated through numerical experiments considering both mode-I and mixed-mode fracture in concrete.
基金supported by the National Key Research and Development Program of China (Grant Nos. 2018YFC1508803 and 2017YFA0604903)jointly supported by the Key Special Project for Introduced Talents Team of the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (Grant No. GML2019ZD0601)
文摘Tropical cyclones(TCs)may cause severe impacts on the activities of coastal fishing vessels.Due to the unavailability or unacceptability of detailed Automatic Identification System(AIS)data that are capable of differentiating fishing activity from navigation,as well as the lack of detailed models and observation data of TC winds,few studies have provided quantitative and reliable assessment of the impacts of TCs on fishing activities.In this study,we modeled snapshots for the TC winds of 52 TCs over the Northwest Pacific(NWP)basin from 2013 to 2018,as well as daily fishing hours and daily hours of presence(hereafter“vessel hours”)of fishing vessels.Based on these data,the spatiotemporal pattern of fishing vessel activity over off-shore China was first analyzed and mapped.Then,a TC wind hazard index and absolute and relative impact indices were proposed to assess the impact of the 52 TCs on fishing and vessel hours.Their relationship was then fitted with the cumulative distribution function(CDF)of the log-normal distribution.The results show that in the 2013-2018 period,the most active fishing areas were located in the South China Sea.In each instance,an increase was first observed in the initial several years;then a decrease followed in the yearly total fishing hours per vessel in the remaining years.The relative impact index was significantly correlated to the TC wind hazard index proposed in this study.Based on the quantitative relationship between the specified TC hazard index and the impact indices,it is possible to implement a pre-cyclone rapid loss assessment due to TC avoidance in the future.
