Tunnels are a crucial component of urban infrastructure,continuously exposed to various hazards,threats,and stressors.Events such as earthquakes,fires,and floods,along with aging and construction-related disturbances,...Tunnels are a crucial component of urban infrastructure,continuously exposed to various hazards,threats,and stressors.Events such as earthquakes,fires,and floods,along with aging and construction-related disturbances,pose significant challenges to tunnel resilience.Reliable fragility,restoration,and traffic reinstatement models are essential for assessing and quantifying resilience,as they allow infrastructure operators to prioritize maintenance and adapt to evolving threats in complex transportation systems.Although the vulnerability and fragility of tunnels have been widely researched over the last decade,studies focusing on tunnel restoration to quantify resilience remain scarce.This gap prevents operators from implementing proactive and reactive adaptation measures to ensure seamless tunnel functionality.To address this issue,this study presents a novel,fit-for-purpose,damage-level-dependent probabilistic approach for quantifying tunnel recovery.It introduces the first realistic,practice-led restoration models that enable resilience quantification in tunnels.To develop these models,a global expert survey was conducted to establish reinstatement(traffic capacity)and restoration(structural capacity)models tailored to tunnel resilience assessments.A detailed questionnaire was designed to gather expert input on required restoration tasks,their duration,sequencing,and cost.The survey focused primarily on damage induced by seismic events,incorporating idle times and traffic capacity gains over time.The results were then used to generate deterministic and probabilistic reinstatement and restoration models.The deterministic models are intended for practical applications,while the probabilistic models account for epistemic uncertainties and are presented in a reproducible format for further development across different hazards and applications.A case study is included to demonstrate the resilience assessment of a typical tunnel using the newly developed restoration models.The findings will help infrastructure operators and city planners to accurately assess tunnel resilience,enabling informed investment decisions.展开更多
The key difficulty of restoring a fuzzy image is to estimate its point spread function( PSF). In the paper,PSF is modelled based on modulation transfer function( MTF). The first step is calculating the image MTF. In t...The key difficulty of restoring a fuzzy image is to estimate its point spread function( PSF). In the paper,PSF is modelled based on modulation transfer function( MTF). The first step is calculating the image MTF. In the traditional slanted-edge method,a sub-block is always manually extracted from original image and its MTF will be viewed as the result of the whole image. However,handcraft extraction is inefficient and will lead to inaccurate results. Given this,an automatic MTF computation algorithm is proposed,which extracts and screens out all the effective sub-blocks and calculates their average MTF as the final result. Then,a two-dimensional MTF restoration model is constructed by multiplying the horizontal and vertical MTF,and it is combined with conventional image restoration methods to restore fuzzy image. Experimental results indicate the proposed method implementes a fast and accurate MTF computation and the MTF model improves the performance of conventional restoration methods significantly.展开更多
Phosphorus is one of the most important nutrients required to support various kinds of biodegradation processes. As this particular nutrient is not included in the activated sludge model no. 1 （ASM1）, this study ext...Phosphorus is one of the most important nutrients required to support various kinds of biodegradation processes. As this particular nutrient is not included in the activated sludge model no. 1 （ASM1）, this study extended this model in order to determine the fate of phosphorus during the biodegradation processes. When some of the kinetics parameters are modified using observed data from the restoration project of the Xuxi River in Wuxi City, China, from August 25 to 31 in 2009, the extended model shows excellent results. In order to obtain optimum values of coefficients of nitrogen and phosphorus, the mass fraction method was used to ensure that the final results were reasonable and practically relevant. The temporal distribution of the data calculated with the extended ASM1 approximates that of the observed data.展开更多
Communities depend on critical infrastructure systems to support their regular operations and future develop-ment.Destructive events,such as natural disasters,threaten to disrupt service to these systems and the commu...Communities depend on critical infrastructure systems to support their regular operations and future develop-ment.Destructive events,such as natural disasters,threaten to disrupt service to these systems and the commu-nities they support.Strategies designed to reduce the impacts from disasters and other events are therefore an important consideration for community planning.At a regional level,coordination between communities sup-ports the efficient use of resources for implementing disaster risk reduction(DRR)measures and completing post-disaster repairs to meet the needs of all residents.Coordination is challenging,however,due to the complex-ity of regional systems and competing stakeholder interests.This work presents a case study model of regional water,wastewater,and power systems,and demonstrates the effect of seismic hardening and increased resource availability on post-earthquake repair requirements and critical infrastructure recovery.Model results indicate that implementing DRR strategies can reduce required repair costs by over 40 percent and outage severity by approximately 50 percent for the studied sectors.Not all strategies are effective for all sectors and locations,how-ever,so this work discusses the importance of comprehensive,coordinated,and accessible emergency planning activities to ensure that the needs of all residents are considered.展开更多
Grassland in northern Tibet plays an important role in the eco-security of the Qinghai-Tibet Plateau and the restoration of deserte@and degraded grassland is now a focus for governments. We used remote sensing, simula...Grassland in northern Tibet plays an important role in the eco-security of the Qinghai-Tibet Plateau and the restoration of deserte@and degraded grassland is now a focus for governments. We used remote sensing, simulations and field surveys to analyze the current status, trends and causes of grassland degradation across northern Tibet. We develop several recovery models for degraded grassland based on field experiments in the region. We found that slightly degraded grassland covers 62% and that moderate to severely degraded grassland occupied 15.1% in the Chang Tang Plateau. The amount of degraded alpine steppe increased from 1991, and the amount of area classified as severely degraded increased sharply from 2000. The cause of degraded steppe in northwestern Tibet may be the result of warming and an arid climate; the cause of severe degradation in mid and eastern regions was mainly from overgrazing. Three restoration models are proposed for different levels of degradation： ＂enclosures＂ for slightly degraded areas, ＂enclosures with fertilization＂ for moderately degraded areas, and ＂enclosure with oversowing and fertilization＂ for severely degraded areas.展开更多
Quasi-static testing is the primary seismic research method employed.The method proposed in this study utilizes the neural network(NN)algorithm for restoring force identification to extend the hysteretic performance o...Quasi-static testing is the primary seismic research method employed.The method proposed in this study utilizes the neural network(NN)algorithm for restoring force identification to extend the hysteretic performance of nonlinear complex components obtained from quasi-static tests shared or performed at a lower cost to the time history analysis of the seismic response of the entire structure.This approach enables accurate analysis of the seismic performance of the structure under real earthquake ground motions at a relatively low experimental costs.At the level of restoring force model recognition,the eight-path hysteresis model recognition theory and the corresponding complete set of input and output variables in the NN algorithm are proposed.The NN restoring force model was established using input and output parameters that characterize hysteresis state features,with a two-hidden-layer NN architecture.The case study results indicate that the prediction results of the NN restoring force model align well with the target values when trained on samples obtained under both seismic and quasi-static loading conditions.At the level of the nonlinear dynamic analysis of structures,the hybrid analysis method of structural seismic response based on NN restoring force model is proposed.In this method,the potentially severe nonlinear and elastic parts of the structure are divided into several NN substructures and principal numerical substructure,respectively.The pseudo-static test data of nonlinear regions were used to train the proposed NN restoring force model to identify the restoring force of NN substructures in the same region under time-history dynamic analysis.The platform was built to complete the data interaction between several NN substructures and principal numerical substructures,and a precise integration method was used to program the dynamic equation solving module,gradually completing dynamic response analysis of the entire structure.A multi-degree-offreedom nonlinear frame case study indicate that the proposed method has good accuracy and can effectively analyze the structural nonlinear seismic response.展开更多
基金support from the National Natural Science Foundation of China(52478410,W2411044,and 52408435)the National Key Research and Development Program of China(2022YFC3800905)+3 种基金Young Elite Scientists Sponsorship Program by CAST(2023QNRC001)the Fundamental Research Funds for the Central UniversitiesDr.Stergios-Aristoteles Mitoulis and Dr.Sotirios Argyroudis acknowledge funding from the UK Research and Innovation(UKRI)under the UK government’s Horizon Europe funding guarantee(EP/Y003586/1,EP/X037665/1)This is the funding guarantee for the European Union's HORIZON-MSCA-2021-SE-01(101086413)“ReCharged-Climate-Aware Resilience for Sustainable Critical and Interdependent Infrastructure Systems Enhanced by Emerging Digital Technologies.”。
文摘Tunnels are a crucial component of urban infrastructure,continuously exposed to various hazards,threats,and stressors.Events such as earthquakes,fires,and floods,along with aging and construction-related disturbances,pose significant challenges to tunnel resilience.Reliable fragility,restoration,and traffic reinstatement models are essential for assessing and quantifying resilience,as they allow infrastructure operators to prioritize maintenance and adapt to evolving threats in complex transportation systems.Although the vulnerability and fragility of tunnels have been widely researched over the last decade,studies focusing on tunnel restoration to quantify resilience remain scarce.This gap prevents operators from implementing proactive and reactive adaptation measures to ensure seamless tunnel functionality.To address this issue,this study presents a novel,fit-for-purpose,damage-level-dependent probabilistic approach for quantifying tunnel recovery.It introduces the first realistic,practice-led restoration models that enable resilience quantification in tunnels.To develop these models,a global expert survey was conducted to establish reinstatement(traffic capacity)and restoration(structural capacity)models tailored to tunnel resilience assessments.A detailed questionnaire was designed to gather expert input on required restoration tasks,their duration,sequencing,and cost.The survey focused primarily on damage induced by seismic events,incorporating idle times and traffic capacity gains over time.The results were then used to generate deterministic and probabilistic reinstatement and restoration models.The deterministic models are intended for practical applications,while the probabilistic models account for epistemic uncertainties and are presented in a reproducible format for further development across different hazards and applications.A case study is included to demonstrate the resilience assessment of a typical tunnel using the newly developed restoration models.The findings will help infrastructure operators and city planners to accurately assess tunnel resilience,enabling informed investment decisions.
基金Supported by the National High Technology Research and Development Programme of China(No.2012AA12A305)the National Key Technology R&D Program of the Ministry of Science and Technology(No.2013BAH03B01)+1 种基金Fundamental Research Funds for the Central Universities of China(No.2042015kf0059)China Postdoctoral Science Foundation(No.2015M582277)
文摘The key difficulty of restoring a fuzzy image is to estimate its point spread function( PSF). In the paper,PSF is modelled based on modulation transfer function( MTF). The first step is calculating the image MTF. In the traditional slanted-edge method,a sub-block is always manually extracted from original image and its MTF will be viewed as the result of the whole image. However,handcraft extraction is inefficient and will lead to inaccurate results. Given this,an automatic MTF computation algorithm is proposed,which extracts and screens out all the effective sub-blocks and calculates their average MTF as the final result. Then,a two-dimensional MTF restoration model is constructed by multiplying the horizontal and vertical MTF,and it is combined with conventional image restoration methods to restore fuzzy image. Experimental results indicate the proposed method implementes a fast and accurate MTF computation and the MTF model improves the performance of conventional restoration methods significantly.
文摘Phosphorus is one of the most important nutrients required to support various kinds of biodegradation processes. As this particular nutrient is not included in the activated sludge model no. 1 （ASM1）, this study extended this model in order to determine the fate of phosphorus during the biodegradation processes. When some of the kinetics parameters are modified using observed data from the restoration project of the Xuxi River in Wuxi City, China, from August 25 to 31 in 2009, the extended model shows excellent results. In order to obtain optimum values of coefficients of nitrogen and phosphorus, the mass fraction method was used to ensure that the final results were reasonable and practically relevant. The temporal distribution of the data calculated with the extended ASM1 approximates that of the observed data.
基金funding for this work was provided in part by the Canadian Safety and Security Program(CSSP)under project number CSSP-2018-CP-2351titled“Disaster Risk Reduction Pathways:Incentives for Mitigation&Adaptation Investments”.
文摘Communities depend on critical infrastructure systems to support their regular operations and future develop-ment.Destructive events,such as natural disasters,threaten to disrupt service to these systems and the commu-nities they support.Strategies designed to reduce the impacts from disasters and other events are therefore an important consideration for community planning.At a regional level,coordination between communities sup-ports the efficient use of resources for implementing disaster risk reduction(DRR)measures and completing post-disaster repairs to meet the needs of all residents.Coordination is challenging,however,due to the complex-ity of regional systems and competing stakeholder interests.This work presents a case study model of regional water,wastewater,and power systems,and demonstrates the effect of seismic hardening and increased resource availability on post-earthquake repair requirements and critical infrastructure recovery.Model results indicate that implementing DRR strategies can reduce required repair costs by over 40 percent and outage severity by approximately 50 percent for the studied sectors.Not all strategies are effective for all sectors and locations,how-ever,so this work discusses the importance of comprehensive,coordinated,and accessible emergency planning activities to ensure that the needs of all residents are considered.
基金The Key Technologies Research and Development Program of China (2011BAC09B03)Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA05060700)the‘Western Light’talents training program of Chiese Academy of Sciecnes
文摘Grassland in northern Tibet plays an important role in the eco-security of the Qinghai-Tibet Plateau and the restoration of deserte@and degraded grassland is now a focus for governments. We used remote sensing, simulations and field surveys to analyze the current status, trends and causes of grassland degradation across northern Tibet. We develop several recovery models for degraded grassland based on field experiments in the region. We found that slightly degraded grassland covers 62% and that moderate to severely degraded grassland occupied 15.1% in the Chang Tang Plateau. The amount of degraded alpine steppe increased from 1991, and the amount of area classified as severely degraded increased sharply from 2000. The cause of degraded steppe in northwestern Tibet may be the result of warming and an arid climate; the cause of severe degradation in mid and eastern regions was mainly from overgrazing. Three restoration models are proposed for different levels of degradation： ＂enclosures＂ for slightly degraded areas, ＂enclosures with fertilization＂ for moderately degraded areas, and ＂enclosure with oversowing and fertilization＂ for severely degraded areas.
基金supports from the National Natural Science Foundation of China(Grant Nos.52478305 and 52308483)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX22_0213).
文摘Quasi-static testing is the primary seismic research method employed.The method proposed in this study utilizes the neural network(NN)algorithm for restoring force identification to extend the hysteretic performance of nonlinear complex components obtained from quasi-static tests shared or performed at a lower cost to the time history analysis of the seismic response of the entire structure.This approach enables accurate analysis of the seismic performance of the structure under real earthquake ground motions at a relatively low experimental costs.At the level of restoring force model recognition,the eight-path hysteresis model recognition theory and the corresponding complete set of input and output variables in the NN algorithm are proposed.The NN restoring force model was established using input and output parameters that characterize hysteresis state features,with a two-hidden-layer NN architecture.The case study results indicate that the prediction results of the NN restoring force model align well with the target values when trained on samples obtained under both seismic and quasi-static loading conditions.At the level of the nonlinear dynamic analysis of structures,the hybrid analysis method of structural seismic response based on NN restoring force model is proposed.In this method,the potentially severe nonlinear and elastic parts of the structure are divided into several NN substructures and principal numerical substructure,respectively.The pseudo-static test data of nonlinear regions were used to train the proposed NN restoring force model to identify the restoring force of NN substructures in the same region under time-history dynamic analysis.The platform was built to complete the data interaction between several NN substructures and principal numerical substructures,and a precise integration method was used to program the dynamic equation solving module,gradually completing dynamic response analysis of the entire structure.A multi-degree-offreedom nonlinear frame case study indicate that the proposed method has good accuracy and can effectively analyze the structural nonlinear seismic response.
