[Objective] The aim was to assess the ecosystem vulnerability of Dashanbao wetland.[Method] The evaluation index system of ecosystem vulnerability of Dashanbao wetland was constructed by using analytic hierarchy proce...[Objective] The aim was to assess the ecosystem vulnerability of Dashanbao wetland.[Method] The evaluation index system of ecosystem vulnerability of Dashanbao wetland was constructed by using analytic hierarchy process(AHP),and the ecosystem vulnerability of Dashanbao wetland from 2002 to 2008 was assessed based on vulnerable degree of ecosystem.[Result] The vulnerable degree of ecosystem of Dashanbao wetland from 2002 to 2008 was 0.560 0,0.513 7,0.516 4,0.465 4,0.476 0,0.449 2 and 0.400 6 respectively,that is,showing decreasing trend on the whole,and the vulnerability of wetland ecosystem transformed from moderate vulnerability to mild vulnerability,and it showed that the ecological environment quality of Dashanbao wetland was better.[Conclusion] The study could provide references for wetland restoration,protection,ecological environment planning and management.展开更多
The ecosystem is important because it is the life sustaining system for human survival.Three ecosystem characteristics are:regional particularities,ecosystem complexity and conventional cultural particularities.This p...The ecosystem is important because it is the life sustaining system for human survival.Three ecosystem characteristics are:regional particularities,ecosystem complexity and conventional cultural particularities.This paper develops a remote sensing based dynamic model to assess grassland ecosystem service values involving multidisciplinary knowledge.The ecological value of grassland ecosystems is focused on using a remote sensing technique in the model,and setting up the framework for a dynamic assessing model.The grassland ecological services condition and value in 1985 is used as the benchmark.The dynamic model has two adjusting indicators:biomass and price index.The biomass is simulated using the CASA(Carnegie-Ames-Stanford Approach) model.The price index was obtained from statistics data published by the statistical bureau.Results show that the grassland ecosystem value in Gansu Province was 28.36 billion Chinese Yuan in 1985,140.37 billion in 1999 and 130.86 billion in 2002.展开更多
To investigate the impact of dynamic assessment(DA)on the development of speaking skills,a case study was conducted,recruiting a non-English major undergraduate.DA was constructed following the design combining sandwi...To investigate the impact of dynamic assessment(DA)on the development of speaking skills,a case study was conducted,recruiting a non-English major undergraduate.DA was constructed following the design combining sandwich and cake format with an interactionist approach.To collect data,a profile was designed in accordance with the China’s Standards of English Language Ability(CSE)to record the learner’s changes.A semi-structured interview was conducted to reveal his perspectives on DA.The generated profile with specific mediator-learner’s moves revealed the learner’s microgenetic development in both organizational knowledge and oral expression strategy ability.The thematic analysis of the interview demonstrated the learner’s positive experience with DA,while also unveiling the weak points of DA.Finally,the operational framework for applying interactionist DA in the oral classroom was discussed,and the complementary relationship between DA and traditional teaching and testing practices was highlighted.展开更多
In recent years,the escalation in accidental explosions has emerged as a formidable threat to tunnel infrastructures.Therefore,it is of great significance to conduct a dynamic performance analysis of the tunnels,to im...In recent years,the escalation in accidental explosions has emerged as a formidable threat to tunnel infrastructures.Therefore,it is of great significance to conduct a dynamic performance analysis of the tunnels,to improve the safety and maintain the functionality of underground transport hubs.To this end,this study proposes a dynamic performance assessment framework to assess the extent of damage of shallow buried circular tunnels under explosion hazards.First,the nonlinear dynamic finite element numerical model of soil-tunnel interaction system under explosion hazard was established and validated.Then,based on the validated numerical model,an explosion intensity(EI)considering both explosion equivalent and relative distance was used to further analyze the dynamic response characteristics under typical explosion conditions.Finally,this study further explored the influence of the integrity and strength of the surrounding soil,concrete strength,lining thickness,rebar strength,and rebar rate on the tunnel dynamic performance.Our results show that the dynamic performance assessment framework proposed for shallow circular tunnels fully integrates the coupling effects of explosion equivalent and distance,and is able to accurately measure the degree of damage sustained by these structures under different EI.This work contributes to designing and managing tunnels and underground transport networks based on dynamic performance,thereby facilitating decision-making and efficient allocation of resources by consultants,operators,and stakeholders.展开更多
It is well established that at the university,one forms the critical spirit,the spirit of analysis and the spirit of synthesis.What we advocate is a spirit of evaluation.The process we followed is part of a problemati...It is well established that at the university,one forms the critical spirit,the spirit of analysis and the spirit of synthesis.What we advocate is a spirit of evaluation.The process we followed is part of a problematic of teaching French and especially in didactics of writing.We have implemented an experimental device in our teaching practice.This is the dynamic evaluation.This evaluation allows the measurement of the initial level of achievement of a written production.And also the introduction of elements likely to help the subject to modify his usual strategies involved in the realization of a failed written production.But above all the appreciation of the way new strategies are involved.It is a four-phase experience that lasted a whole year.We first put our sample audience to a pre-test;with them,we determined the teaching objectives;then we set up the training workshops for the dynamic assessment,and finally we closed the process with a final test of measurement and evaluation.Two questionnaires were used and an observation grid.展开更多
The rapid development of international tourism has led to an increasing demand for English professionals. In order to meet this demand, universities have placed greater emphasis on the quality and level of teaching in...The rapid development of international tourism has led to an increasing demand for English professionals. In order to meet this demand, universities have placed greater emphasis on the quality and level of teaching in the courses of tourism English. This paper proposes a dynamic evaluation model for tourism English courses, based on the principles of dynamic assessment theory, such as process-orientation, evaluation-teaching integration, and multiple interactions. Taking the course of Beijing World Cultural Heritage as an example, the model is instantiated to demonstrate the feasibility of applying dynamic assessment theory to tourism English courses and this model helps to provide a reference for the evaluation methods of English courses.展开更多
A number of contingencies simulated during dynamic security assessment do not generate unacceptable values of power system state variables, due to their small influence on system operation. Their exclusion from the se...A number of contingencies simulated during dynamic security assessment do not generate unacceptable values of power system state variables, due to their small influence on system operation. Their exclusion from the set of contingencies to be simulated in the security assessment would achieve a significant reduction in computation time. This paper defines a critical contingencies selection method for on-line dynamic security assessment. The selection method results from an off-line dynamical analysis, which covers typical scenarios and also covers various related aspects like frequency, voltage, and angle analyses among others. Indexes measured over these typical scenarios are used to train neural networks, capable of performing on-line estimation of a critical contingencies list according to the system state.展开更多
In 1974,Andreas Grüntzig developed the technique“percutaneous transluminal dilatation”using the first balloon angioplasty,and for this he was awarded the Nobel Prize in Physiology or Medicine.Balloon angioplast...In 1974,Andreas Grüntzig developed the technique“percutaneous transluminal dilatation”using the first balloon angioplasty,and for this he was awarded the Nobel Prize in Physiology or Medicine.Balloon angioplasty heralded a new era of interventional medicine and has shaped the modern approach to coronary artery disease intervention.Research within the field has led to an improved understanding of the pathophysiology of coronary artery disease and the development of technologies for its treatment.The efficacy of balloon angioplasty was evident from its inception,but initial theories explaining the mechanism of action of this procedure did not encompass the entire process within the coronary artery.展开更多
In a high-risk sector,such as power system,trans parency and interpretability are key principles for effectively deploying artificial intelligence(AI)in control rooms.There fore,this paper proposes a novel methodology...In a high-risk sector,such as power system,trans parency and interpretability are key principles for effectively deploying artificial intelligence(AI)in control rooms.There fore,this paper proposes a novel methodology,the evolving sym bolic model(ESM),which is dedicated to generating highly in terpretable data-driven models for dynamic security assessment(DSA),namely in system security classification(SC)and the def inition of preventive control actions.The ESM uses simulated annealing for a data-driven evolution of a symbolic model tem plate,enabling different cooperative learning schemes between humans and AI.The Madeira Island power system is used to validate the application of the ESM for DSA.The results show that the ESM has a classification accuracy comparable to pruned decision trees(DTs)while boasting higher global inter pretability.Moreover,the ESM outperforms an operator-de fined expert system and an artificial neural network in defining preventive control actions.展开更多
Deep learning(DL)-based methods in pre-fault dynamic security assessment(DSA)have provided significant results,contributing to the safe operation of power systems.However,power systems often suffer from insuf-ficient,...Deep learning(DL)-based methods in pre-fault dynamic security assessment(DSA)have provided significant results,contributing to the safe operation of power systems.However,power systems often suffer from insuf-ficient,small,and imbalanced datasets,which significantly impact the performance of DL-based DSA models.Existing DSA frameworks typically operate as two-class black-box models,assessing only overall system security without providing insights into the causes of insecurity or identifying critical generators(CGs),and they fail to quantify prediction uncertainty.These challenges hinder the implementation of current methods in real-world power systems and reduce operators’confidence in them.To address these issues,this paper proposes an uncertainty-aware bi-level multitask learning framework based on transfer learning and SqueezeNet architec-ture.The framework assesses system security,identifies CGs during instability,and leverages fine-tuning of a pretrained SqueezeNet model to facilitate training with limited data.Additionally,evidential deep learning is incorporated to quantify classification uncertainty.Without relying on the complex and challenging data augmentation method,this framework uses a simple technique called optimal classification threshold determi-nation to mitigate the negative impact of imbalanced data on model performance.The optimal threshold is determined by maximizing the area under the receiver operating characteristic(ROC)curve.The application of the proposed method to the IEEE 118-bus system shows its strong performance.These results offer crucial technical insights for the implementation of DL-based DSA in real-world power systems.展开更多
This letter proposes a reliable transfer learning(RTL)method for pre-fault dynamic security assessment(DSA)in power systems to improve DSA performance in the presence of potentially related unknown faults.It takes ind...This letter proposes a reliable transfer learning(RTL)method for pre-fault dynamic security assessment(DSA)in power systems to improve DSA performance in the presence of potentially related unknown faults.It takes individual discrepancies into consideration and can handle unknown faults with incomplete data.Extensive experiment results demonstrate high DSA accuracy and computational efficiency of the proposed RTL method.Theoretical analysis shows RTL can guarantee system performance.展开更多
Water scarcity and environment deterioration have become main constraints to sustainable economic and social development.Scientifically assessing Water Resources Carrying Capacity(WRCC)is essential for the optimal all...Water scarcity and environment deterioration have become main constraints to sustainable economic and social development.Scientifically assessing Water Resources Carrying Capacity(WRCC)is essential for the optimal allocation of regional water resources.The hilly area at the northern foot of Yanshan Mountains is a key water conservation zone and an important water source for Beijing,Tianjin and Hebei.Grasping the current status and temporal trends of water quality and WRCC in representative small watersheds within this region is crucial for supporting rational water resources allocation and environment protection efforts.This study focuses on Pingquan City,a typical watershed in northern Hebei Province.Firstly,evaluation index systems for surface water quality,groundwater quality and WRCC were estab-lished based on the Pressure-State-Response(PSR)framework.Then,comprehensive evaluations of water quality and WRCC at the sub-watershed scale were conducted using the Varying Fuzzy Pattern Recogni-tion(VFPR)model.Finally,the rationality of the evaluation results was verified,and future scenarios were projected.Results showed that:(1)The average comprehensive evaluation scores for surface water and groundwater quality in the sub-watersheds were 1.44 and 1.46,respectively,indicating that both met the national Class II water quality standard and reflected a high-quality water environment.(2)From 2010 to 2020,the region's WRCC steadily improved,with scores rising from 2.99 to 2.83 and an average of 2.90,suggesting effective water resources management in Pingquan City.(3)According to scenario-based predic-tion,WRCC may slightly decline between 2025 and 2030,reaching 2.92 and 2.94,respectively,relative to 2020 levels.Therefore,future efforts should focus on strengthening scientific management and promoting the efficient use of water resources.Proactive measures are necessary to mitigate emerging contradiction and ensure the long-term stability and sustainability of the water resources system in the region.The evalua-tion system and spatiotemporal evolution patterns proposed in this study can provide a scientific basis for refined water resource management and ecological conservation in similar hilly areas.展开更多
The development of innovative, complex marine systems, such as autonomous ship concepts, has led to risk-based approaches indesign and operation that provide safety level quantification and continuous risk assessment....The development of innovative, complex marine systems, such as autonomous ship concepts, has led to risk-based approaches indesign and operation that provide safety level quantification and continuous risk assessment. The existing approaches to dynamicrisk assessmentmainly aim at updating accident probabilities for specific risk scenarios, based on knowledge of system operation andfailure, aswell as on past accident and failure information. However, for innovative marine systems that include complex interactions,our ability to identify anything that might go wrong is very limited, which may lead to unidentified risks, and failure data may not beavailable. This paper presents the foundations of a framework for dynamic risk assessment, which is equally applicable to mannedand autonomous ships and mainly relies on information about the safe operational envelope and real-time information regardingdeviations from safety. Inspiration is drawn from how the biological immune system identifies the risk of infection in a dynamicenvironment. The objective is to show the feasibility and benefits of our approach for quantifying the operational risk of marinesystems. This paper provides the conceptual basis for developing ship specific applications and describes a process for dynamic riskassessment that is methodologically based on artificial immune systems. To demonstrate the implementation of our framework, wedescribed, an illustrative example that involves a ship in a grounding scenario. The results show that the bio-inspired assessmentprocess and risk description can reflect the changes of the risk level of a marine system.展开更多
The present case study explores the effects of mediation of dynamic assessment （DA） on EFL writing development of English majors. Two junior English majors and their English writing teacher in a Chinese university w...The present case study explores the effects of mediation of dynamic assessment （DA） on EFL writing development of English majors. Two junior English majors and their English writing teacher in a Chinese university were involved in a DA writing task. Student B was asked to write an application letter in English of around 500 words during her spare time. Student A and the teacher, as the mediators, tried to help her improve the essay based on her Zone of Proximal Development （ZPD）. The dialogues in the two mediation processes were recorded and transcribed. Analysis of the data from Student B＇s compositions and the recorded talks during the mediation process showed that there are some similarities between the two mediations including making more use of implicit prompts to guide the learner and playing a positive role to facilitate EFL language growth, especially grammar. The.analysis, however, also showed great differences. The teacher tutor attempted more prompts and more implicit strategies than the peer to show that the teacher could do a better job in exploring the learner＇s ZPD. Even so, the peer might be of important help in improving the language and content before a teacher mediation in the DA process.展开更多
Landslide susceptibility assessment is crucial in predicting landslide occurrence and potential risks.However,traditional methods usually emphasize on larger regions of landsliding and rely on relatively static enviro...Landslide susceptibility assessment is crucial in predicting landslide occurrence and potential risks.However,traditional methods usually emphasize on larger regions of landsliding and rely on relatively static environmental conditions,which exposes the hysteresis of landslide susceptibility assessment in refined-scale and temporal dynamic changes.This study presents an improved landslide susceptibility assessment approach by integrating machine learning models based on random forest(RF),logical regression(LR),and gradient boosting decision tree(GBDT)with interferometric synthetic aperture radar(InSAR)technology and comparing them to their respective original models.The results demonstrated that the combined approach improves prediction accuracy and reduces the false negative and false positive errors.The LR-InSAR model showed the best performance in dynamic landslide susceptibility assessment at both regional and smaller scale,particularly when identifying areas of high and very high susceptibility.Modeling results were verified using data from field investigations including unmanned aerial vehicle(UAV)flights.This study is of great significance to accurately assess dynamic landslide susceptibility and to help reduce and prevent landslide risk.展开更多
Based on the citrus temperature, precipitation, sunlight and climate risk degree, the article divides subtropics of China into three types： the low risk region, the moderate risk region and the high risk region. The ...Based on the citrus temperature, precipitation, sunlight and climate risk degree, the article divides subtropics of China into three types： the low risk region, the moderate risk region and the high risk region. The citrus temperature risk increases with increasing latitude （except for the western mountainous area of subtropics of China）. The citrus precipitation risk in the central part of subtropics of China is higher than that in the northern and western parts. The distributions of citrus sunlight risk are not consistent to those of the citrus precipitation risk. The citrus climate risk is mainly influenced by temperature. There is latitudinal zonal law for the distribution of the climate risk, that is, the climate risk increases with increasing latitude At the same time the climate risk in mountainous area is high and that in eastern plain area is low. There are differences in the temporal and spatial changes of the citrus climate. In recent 46 years, the citrus climate risk presents a gradual increasing trend in subtropics of China, especially it has been increasing fast since the 1980s. Because of the global warming, the low risk region in the eastern and southern parts has a gradual decreasing trend, however, the high risk region in the northern and western parts has an increasing trend and the high risk region has been extending eastward and southward. The article analyses the distribution of the citrus climate risk degree of reduction rates of 〉10%, 〉20% and 〉30% in subtropics of China, and studies their changes in different time periods. Results show that the risk is increasing from southeast to northwest.展开更多
Dynamic comprehensive assessment of regional power industry development levels is of paramount importance for understanding the development characteristics and potential of the local power industry.A tri-level evaluat...Dynamic comprehensive assessment of regional power industry development levels is of paramount importance for understanding the development characteristics and potential of the local power industry.A tri-level evaluation index system is established,describing five aspects of the local power industry development level,specifically,the coordination degree between the power industry and economy/energy,power generation,power consumption,power supply and development potential.A combination of information entropy and the analytic hierarchy process(AHP)is used to establish a static evaluation model,and a blend of subjective opinions and objective data information is then realized.By aggregating the static evaluation model for each time period based on a time-ordered weighting vector calculated using time-ordered information entropy,a dynamic comprehensive evaluation model of power industry development level is established.By considering provincial data from China recorded during 2007 to 2016 as the sample set,through synchronic and diachronic comparisons of the evaluation results,the differences,characteristics and potential of local power industry development in China are explored.展开更多
The present paper reviews 25 studies conducted in the domain of L2 （second/foreign language） dynamic assessment （DA） in recent years. It begins with a survey of relevant research, then discusses some of the major ...The present paper reviews 25 studies conducted in the domain of L2 （second/foreign language） dynamic assessment （DA） in recent years. It begins with a survey of relevant research, then discusses some of the major findings and problems, and finishes with some suggestions for further research. The main findings of the review are as follows： （a） DA has the potential to promote L2 competence development; （b） both the interactionist approach and interventionist approach have attracted the interest of L2 researchers; （c） most studies have focused on small samples; （d） reading and grammatical knowledge have drawn the most attention; （e） group DA may be a potential method to advance L2 competence development in both the focused individual and the other members of the group; （f） computers might play a complementary role to humans acting as mediators; and （g） case study methodology has been the overwhelming choice for experimental design. Based on the available research, we suggest that additional studies are called for on the following issues： （a） L2 DA as an approach to measurement, （b） potential mediators, （c） validity issues of L2 DA, （d） the interface between DA and second language acquisition, and （e） the development of L2 classroom teachers.展开更多
文摘[Objective] The aim was to assess the ecosystem vulnerability of Dashanbao wetland.[Method] The evaluation index system of ecosystem vulnerability of Dashanbao wetland was constructed by using analytic hierarchy process(AHP),and the ecosystem vulnerability of Dashanbao wetland from 2002 to 2008 was assessed based on vulnerable degree of ecosystem.[Result] The vulnerable degree of ecosystem of Dashanbao wetland from 2002 to 2008 was 0.560 0,0.513 7,0.516 4,0.465 4,0.476 0,0.449 2 and 0.400 6 respectively,that is,showing decreasing trend on the whole,and the vulnerability of wetland ecosystem transformed from moderate vulnerability to mild vulnerability,and it showed that the ecological environment quality of Dashanbao wetland was better.[Conclusion] The study could provide references for wetland restoration,protection,ecological environment planning and management.
基金supported by the CAS (Chinese Academy of Sciences) Action Plan for West Development Project "Watershed Allied Telemetry Experimental Research (WATER)"(grant number:KZCX2-XB2-09)the Global Change Research Program of China (2010CB951403)+2 种基金WP6 of FP7 topic ENV.2007.4.1.4.2 "Improving observing systems for water resource management"the National Natural Science Foundation of China (grant number:41071227)the Major Research Plan "Integrated Research on the Eco-Hydrological Process of Heihe Basin" of National Natural Science Foundation of China,topic (grant number:91025001)
文摘The ecosystem is important because it is the life sustaining system for human survival.Three ecosystem characteristics are:regional particularities,ecosystem complexity and conventional cultural particularities.This paper develops a remote sensing based dynamic model to assess grassland ecosystem service values involving multidisciplinary knowledge.The ecological value of grassland ecosystems is focused on using a remote sensing technique in the model,and setting up the framework for a dynamic assessing model.The grassland ecological services condition and value in 1985 is used as the benchmark.The dynamic model has two adjusting indicators:biomass and price index.The biomass is simulated using the CASA(Carnegie-Ames-Stanford Approach) model.The price index was obtained from statistics data published by the statistical bureau.Results show that the grassland ecosystem value in Gansu Province was 28.36 billion Chinese Yuan in 1985,140.37 billion in 1999 and 130.86 billion in 2002.
基金supported by the Project of Research on the Evaluation of the Cultivation of Language Talents for International Cultural Communication in Beijing(No.19JDYYB003),which is funded by Beijing Planning Office of Philosophy and Social Science。
文摘To investigate the impact of dynamic assessment(DA)on the development of speaking skills,a case study was conducted,recruiting a non-English major undergraduate.DA was constructed following the design combining sandwich and cake format with an interactionist approach.To collect data,a profile was designed in accordance with the China’s Standards of English Language Ability(CSE)to record the learner’s changes.A semi-structured interview was conducted to reveal his perspectives on DA.The generated profile with specific mediator-learner’s moves revealed the learner’s microgenetic development in both organizational knowledge and oral expression strategy ability.The thematic analysis of the interview demonstrated the learner’s positive experience with DA,while also unveiling the weak points of DA.Finally,the operational framework for applying interactionist DA in the oral classroom was discussed,and the complementary relationship between DA and traditional teaching and testing practices was highlighted.
基金Project(22dz1201202)supported by the Shanghai Science and Technology Committee Program,ChinaProjects(52108381,52090082)supported by the National Natural Science Foundation of China+1 种基金Project(2023QNRC001)supported by the Young Elite Scientists Sponsorship Program by CAST,ChinaProject(TSY2022QT161)supported by the Damage Database for Urban Rail Transit Underground Structures and Resilience Evaluation Algorithm Research。
文摘In recent years,the escalation in accidental explosions has emerged as a formidable threat to tunnel infrastructures.Therefore,it is of great significance to conduct a dynamic performance analysis of the tunnels,to improve the safety and maintain the functionality of underground transport hubs.To this end,this study proposes a dynamic performance assessment framework to assess the extent of damage of shallow buried circular tunnels under explosion hazards.First,the nonlinear dynamic finite element numerical model of soil-tunnel interaction system under explosion hazard was established and validated.Then,based on the validated numerical model,an explosion intensity(EI)considering both explosion equivalent and relative distance was used to further analyze the dynamic response characteristics under typical explosion conditions.Finally,this study further explored the influence of the integrity and strength of the surrounding soil,concrete strength,lining thickness,rebar strength,and rebar rate on the tunnel dynamic performance.Our results show that the dynamic performance assessment framework proposed for shallow circular tunnels fully integrates the coupling effects of explosion equivalent and distance,and is able to accurately measure the degree of damage sustained by these structures under different EI.This work contributes to designing and managing tunnels and underground transport networks based on dynamic performance,thereby facilitating decision-making and efficient allocation of resources by consultants,operators,and stakeholders.
文摘It is well established that at the university,one forms the critical spirit,the spirit of analysis and the spirit of synthesis.What we advocate is a spirit of evaluation.The process we followed is part of a problematic of teaching French and especially in didactics of writing.We have implemented an experimental device in our teaching practice.This is the dynamic evaluation.This evaluation allows the measurement of the initial level of achievement of a written production.And also the introduction of elements likely to help the subject to modify his usual strategies involved in the realization of a failed written production.But above all the appreciation of the way new strategies are involved.It is a four-phase experience that lasted a whole year.We first put our sample audience to a pre-test;with them,we determined the teaching objectives;then we set up the training workshops for the dynamic assessment,and finally we closed the process with a final test of measurement and evaluation.Two questionnaires were used and an observation grid.
文摘The rapid development of international tourism has led to an increasing demand for English professionals. In order to meet this demand, universities have placed greater emphasis on the quality and level of teaching in the courses of tourism English. This paper proposes a dynamic evaluation model for tourism English courses, based on the principles of dynamic assessment theory, such as process-orientation, evaluation-teaching integration, and multiple interactions. Taking the course of Beijing World Cultural Heritage as an example, the model is instantiated to demonstrate the feasibility of applying dynamic assessment theory to tourism English courses and this model helps to provide a reference for the evaluation methods of English courses.
文摘A number of contingencies simulated during dynamic security assessment do not generate unacceptable values of power system state variables, due to their small influence on system operation. Their exclusion from the set of contingencies to be simulated in the security assessment would achieve a significant reduction in computation time. This paper defines a critical contingencies selection method for on-line dynamic security assessment. The selection method results from an off-line dynamical analysis, which covers typical scenarios and also covers various related aspects like frequency, voltage, and angle analyses among others. Indexes measured over these typical scenarios are used to train neural networks, capable of performing on-line estimation of a critical contingencies list according to the system state.
文摘In 1974,Andreas Grüntzig developed the technique“percutaneous transluminal dilatation”using the first balloon angioplasty,and for this he was awarded the Nobel Prize in Physiology or Medicine.Balloon angioplasty heralded a new era of interventional medicine and has shaped the modern approach to coronary artery disease intervention.Research within the field has led to an improved understanding of the pathophysiology of coronary artery disease and the development of technologies for its treatment.The efficacy of balloon angioplasty was evident from its inception,but initial theories explaining the mechanism of action of this procedure did not encompass the entire process within the coronary artery.
基金supported by the ENFIELD(European Lighthouse to Manifest Trustworthy and Green AI)project,European Union’s Horizon Research and Innovation Programme(No.101120657).
文摘In a high-risk sector,such as power system,trans parency and interpretability are key principles for effectively deploying artificial intelligence(AI)in control rooms.There fore,this paper proposes a novel methodology,the evolving sym bolic model(ESM),which is dedicated to generating highly in terpretable data-driven models for dynamic security assessment(DSA),namely in system security classification(SC)and the def inition of preventive control actions.The ESM uses simulated annealing for a data-driven evolution of a symbolic model tem plate,enabling different cooperative learning schemes between humans and AI.The Madeira Island power system is used to validate the application of the ESM for DSA.The results show that the ESM has a classification accuracy comparable to pruned decision trees(DTs)while boasting higher global inter pretability.Moreover,the ESM outperforms an operator-de fined expert system and an artificial neural network in defining preventive control actions.
基金The Imperial College London team was supported through the Reli-ability,Resilience and Defense technology for the grid(R2D2)Project co-funded by the Europe(EU)through the LCE Policy Support Program under Grant HORIZON-CL5-2021through the Competitiveness and Innovation Framework Program under Grant 101075714the EPSRC-funded programs“NetworkPlus-A green,connected and pros-perous Britain”under grant number EP/W034204/1.
文摘Deep learning(DL)-based methods in pre-fault dynamic security assessment(DSA)have provided significant results,contributing to the safe operation of power systems.However,power systems often suffer from insuf-ficient,small,and imbalanced datasets,which significantly impact the performance of DL-based DSA models.Existing DSA frameworks typically operate as two-class black-box models,assessing only overall system security without providing insights into the causes of insecurity or identifying critical generators(CGs),and they fail to quantify prediction uncertainty.These challenges hinder the implementation of current methods in real-world power systems and reduce operators’confidence in them.To address these issues,this paper proposes an uncertainty-aware bi-level multitask learning framework based on transfer learning and SqueezeNet architec-ture.The framework assesses system security,identifies CGs during instability,and leverages fine-tuning of a pretrained SqueezeNet model to facilitate training with limited data.Additionally,evidential deep learning is incorporated to quantify classification uncertainty.Without relying on the complex and challenging data augmentation method,this framework uses a simple technique called optimal classification threshold determi-nation to mitigate the negative impact of imbalanced data on model performance.The optimal threshold is determined by maximizing the area under the receiver operating characteristic(ROC)curve.The application of the proposed method to the IEEE 118-bus system shows its strong performance.These results offer crucial technical insights for the implementation of DL-based DSA in real-world power systems.
基金supported by the Internal Talent Award(TRACS)with Wallenberg-NTU Presidential Postdoctoral Fellowship 2022the National Research Foundation,Singapore and DSO National Laboratories under the AI Singapore Program(AISG Award No:AISG2-RP-2020-019)+1 种基金the RIE 2020 Advanced Manufacturing and Engineering(AME)Programmatic Fund(No.A20G8b0102),SingaporeFuture Communications Research&Development Program(FCP-NTU-RG-2021-014).
文摘This letter proposes a reliable transfer learning(RTL)method for pre-fault dynamic security assessment(DSA)in power systems to improve DSA performance in the presence of potentially related unknown faults.It takes individual discrepancies into consideration and can handle unknown faults with incomplete data.Extensive experiment results demonstrate high DSA accuracy and computational efficiency of the proposed RTL method.Theoretical analysis shows RTL can guarantee system performance.
基金financially supported by China Geological Survey Project(No.DD20220954)Open Funding Project of the Key Laboratory of Groundwater Sciences and Engineering,Ministry of Natural Resources(No.SK202301-4)+2 种基金Science and Technology Innovation Foundation of Comprehensive Survey&Command Center for Natural Resources(No.KC20240003)Yanzhao Shanshui Science and Innovation Fund of Langfang Integrated Natural Resources Survey Center,China Geological Survey(No.YZSSJJ202401-001)Open Foundation of the Key Laboratory of Coupling Process and Effect of Natural Resources Elements(No.2022KFKTC009).
文摘Water scarcity and environment deterioration have become main constraints to sustainable economic and social development.Scientifically assessing Water Resources Carrying Capacity(WRCC)is essential for the optimal allocation of regional water resources.The hilly area at the northern foot of Yanshan Mountains is a key water conservation zone and an important water source for Beijing,Tianjin and Hebei.Grasping the current status and temporal trends of water quality and WRCC in representative small watersheds within this region is crucial for supporting rational water resources allocation and environment protection efforts.This study focuses on Pingquan City,a typical watershed in northern Hebei Province.Firstly,evaluation index systems for surface water quality,groundwater quality and WRCC were estab-lished based on the Pressure-State-Response(PSR)framework.Then,comprehensive evaluations of water quality and WRCC at the sub-watershed scale were conducted using the Varying Fuzzy Pattern Recogni-tion(VFPR)model.Finally,the rationality of the evaluation results was verified,and future scenarios were projected.Results showed that:(1)The average comprehensive evaluation scores for surface water and groundwater quality in the sub-watersheds were 1.44 and 1.46,respectively,indicating that both met the national Class II water quality standard and reflected a high-quality water environment.(2)From 2010 to 2020,the region's WRCC steadily improved,with scores rising from 2.99 to 2.83 and an average of 2.90,suggesting effective water resources management in Pingquan City.(3)According to scenario-based predic-tion,WRCC may slightly decline between 2025 and 2030,reaching 2.92 and 2.94,respectively,relative to 2020 levels.Therefore,future efforts should focus on strengthening scientific management and promoting the efficient use of water resources.Proactive measures are necessary to mitigate emerging contradiction and ensure the long-term stability and sustainability of the water resources system in the region.The evalua-tion system and spatiotemporal evolution patterns proposed in this study can provide a scientific basis for refined water resource management and ecological conservation in similar hilly areas.
文摘The development of innovative, complex marine systems, such as autonomous ship concepts, has led to risk-based approaches indesign and operation that provide safety level quantification and continuous risk assessment. The existing approaches to dynamicrisk assessmentmainly aim at updating accident probabilities for specific risk scenarios, based on knowledge of system operation andfailure, aswell as on past accident and failure information. However, for innovative marine systems that include complex interactions,our ability to identify anything that might go wrong is very limited, which may lead to unidentified risks, and failure data may not beavailable. This paper presents the foundations of a framework for dynamic risk assessment, which is equally applicable to mannedand autonomous ships and mainly relies on information about the safe operational envelope and real-time information regardingdeviations from safety. Inspiration is drawn from how the biological immune system identifies the risk of infection in a dynamicenvironment. The objective is to show the feasibility and benefits of our approach for quantifying the operational risk of marinesystems. This paper provides the conceptual basis for developing ship specific applications and describes a process for dynamic riskassessment that is methodologically based on artificial immune systems. To demonstrate the implementation of our framework, wedescribed, an illustrative example that involves a ship in a grounding scenario. The results show that the bio-inspired assessmentprocess and risk description can reflect the changes of the risk level of a marine system.
文摘The present case study explores the effects of mediation of dynamic assessment （DA） on EFL writing development of English majors. Two junior English majors and their English writing teacher in a Chinese university were involved in a DA writing task. Student B was asked to write an application letter in English of around 500 words during her spare time. Student A and the teacher, as the mediators, tried to help her improve the essay based on her Zone of Proximal Development （ZPD）. The dialogues in the two mediation processes were recorded and transcribed. Analysis of the data from Student B＇s compositions and the recorded talks during the mediation process showed that there are some similarities between the two mediations including making more use of implicit prompts to guide the learner and playing a positive role to facilitate EFL language growth, especially grammar. The.analysis, however, also showed great differences. The teacher tutor attempted more prompts and more implicit strategies than the peer to show that the teacher could do a better job in exploring the learner＇s ZPD. Even so, the peer might be of important help in improving the language and content before a teacher mediation in the DA process.
基金the National Natural Science Foundation of China(Grant No.42271078)Key Research and Development Program of Shaanxi(2024SF-YBXM-669)。
文摘Landslide susceptibility assessment is crucial in predicting landslide occurrence and potential risks.However,traditional methods usually emphasize on larger regions of landsliding and rely on relatively static environmental conditions,which exposes the hysteresis of landslide susceptibility assessment in refined-scale and temporal dynamic changes.This study presents an improved landslide susceptibility assessment approach by integrating machine learning models based on random forest(RF),logical regression(LR),and gradient boosting decision tree(GBDT)with interferometric synthetic aperture radar(InSAR)technology and comparing them to their respective original models.The results demonstrated that the combined approach improves prediction accuracy and reduces the false negative and false positive errors.The LR-InSAR model showed the best performance in dynamic landslide susceptibility assessment at both regional and smaller scale,particularly when identifying areas of high and very high susceptibility.Modeling results were verified using data from field investigations including unmanned aerial vehicle(UAV)flights.This study is of great significance to accurately assess dynamic landslide susceptibility and to help reduce and prevent landslide risk.
基金National Natural Sciences Foundation of China,No.40771033Special Item Funds of Climate Change Supported by China Meteorological Administration,No.CCSF-09-11
文摘Based on the citrus temperature, precipitation, sunlight and climate risk degree, the article divides subtropics of China into three types： the low risk region, the moderate risk region and the high risk region. The citrus temperature risk increases with increasing latitude （except for the western mountainous area of subtropics of China）. The citrus precipitation risk in the central part of subtropics of China is higher than that in the northern and western parts. The distributions of citrus sunlight risk are not consistent to those of the citrus precipitation risk. The citrus climate risk is mainly influenced by temperature. There is latitudinal zonal law for the distribution of the climate risk, that is, the climate risk increases with increasing latitude At the same time the climate risk in mountainous area is high and that in eastern plain area is low. There are differences in the temporal and spatial changes of the citrus climate. In recent 46 years, the citrus climate risk presents a gradual increasing trend in subtropics of China, especially it has been increasing fast since the 1980s. Because of the global warming, the low risk region in the eastern and southern parts has a gradual decreasing trend, however, the high risk region in the northern and western parts has an increasing trend and the high risk region has been extending eastward and southward. The article analyses the distribution of the citrus climate risk degree of reduction rates of 〉10%, 〉20% and 〉30% in subtropics of China, and studies their changes in different time periods. Results show that the risk is increasing from southeast to northwest.
基金This work was supported by the National Natural Science Foundation of China under Grant No.51777104the Science and Technology Project of State Grid Corporation of China.
文摘Dynamic comprehensive assessment of regional power industry development levels is of paramount importance for understanding the development characteristics and potential of the local power industry.A tri-level evaluation index system is established,describing five aspects of the local power industry development level,specifically,the coordination degree between the power industry and economy/energy,power generation,power consumption,power supply and development potential.A combination of information entropy and the analytic hierarchy process(AHP)is used to establish a static evaluation model,and a blend of subjective opinions and objective data information is then realized.By aggregating the static evaluation model for each time period based on a time-ordered weighting vector calculated using time-ordered information entropy,a dynamic comprehensive evaluation model of power industry development level is established.By considering provincial data from China recorded during 2007 to 2016 as the sample set,through synchronic and diachronic comparisons of the evaluation results,the differences,characteristics and potential of local power industry development in China are explored.
基金part of the achievements of the project "Reform of Reading-to-Writing Courses of English Major,"supported by Guangdong Province Higher Educational Reform Essential Project(2013)the education reform project of Southern Medical University
文摘The present paper reviews 25 studies conducted in the domain of L2 （second/foreign language） dynamic assessment （DA） in recent years. It begins with a survey of relevant research, then discusses some of the major findings and problems, and finishes with some suggestions for further research. The main findings of the review are as follows： （a） DA has the potential to promote L2 competence development; （b） both the interactionist approach and interventionist approach have attracted the interest of L2 researchers; （c） most studies have focused on small samples; （d） reading and grammatical knowledge have drawn the most attention; （e） group DA may be a potential method to advance L2 competence development in both the focused individual and the other members of the group; （f） computers might play a complementary role to humans acting as mediators; and （g） case study methodology has been the overwhelming choice for experimental design. Based on the available research, we suggest that additional studies are called for on the following issues： （a） L2 DA as an approach to measurement, （b） potential mediators, （c） validity issues of L2 DA, （d） the interface between DA and second language acquisition, and （e） the development of L2 classroom teachers.
