The integration of Communicative Language Testing(CLT)principles with AI-driven automated assessment poses a significant challenge in professional language testing.Addressing this issue within the specific context of ...The integration of Communicative Language Testing(CLT)principles with AI-driven automated assessment poses a significant challenge in professional language testing.Addressing this issue within the specific context of Civil Aviation Ground Service English,this study explores pathways for their logical reconciliation.Through conceptual analysis and theoretical deduction,with a focus on human-AI interaction scenarios,we demonstrate that the synergy between CLT and AI stems from a shared focus on competency measurement.Key findings reveal that:(1)standardized competency dimensions in CLT can be operationalized into data-processable formats for AI;(2)within professional contexts,AI algorithms can be tailored using authentic service corpora to meet CLT’s demand for situational authenticity;and(3)a division of labor based on competency level-where AI handles standardized scoring of lower-order competencies and human-AI collaboration assesses higher-order competencies-effectively resolves the tension between CLT’s dynamic communication and AI’s static algorithms.Ultimately,the study constructs a three-dimensional integration framework encompassing“professional register,”“competency level,”and“human-AI division of labor,”offering a theoretical model for CLT-AI integration and a practical blueprint for innovating Civil Aviation Ground Service English assessment.展开更多
This study provides the first systematic evaluation of image resolution’s effect (50-300 PPI, pixels per inch) on UAV (unmanned aerial vehicle)-based digital close-range photogrammetry accuracy in civil engineering a...This study provides the first systematic evaluation of image resolution’s effect (50-300 PPI, pixels per inch) on UAV (unmanned aerial vehicle)-based digital close-range photogrammetry accuracy in civil engineering applications, such as infrastructure monitoring and heritage preservation. Using a high-resolution UAV with a 20 MP (MegaPixels) sensor, four images of a brick wall test field were captured and processed in Agisoft Metashape, with resolutions compared against Leica T2002 theodolite measurements (1.0 mm accuracy). Advanced statistical methods (ANOVA (analysis of variance), Tukey tests, Monte Carlo simulations) and ground control points validated the results. Accuracy improved from 25 mm at 50 PPI to 5 mm at 150 PPI (p < 0.01), plateauing at 4 mm beyond 200 PPI, while 150 PPI reduced processing time by 62% compared to 300 PPI. Unlike prior studies, this research uniquely isolates resolution effects in a controlled civil engineering context, offering a novel 150 PPI threshold that balances precision and efficiency. This threshold supports Saudi Vision 2030’s smart infrastructure goals for megaprojects like NEOM, providing a scalable framework for global applications. Future research should leverage deep learning to optimize resolutions in dynamic environments.展开更多
Civil infrastructure is continuously subject to aging and deterioration due to multiple factors,which lead to a decline in performance and impact structural health.Accumulated damage on structures increases operationa...Civil infrastructure is continuously subject to aging and deterioration due to multiple factors,which lead to a decline in performance and impact structural health.Accumulated damage on structures increases operational costs and poses significant risks to public safety.Effective maintenance,repair,and rehabilitation strategies are needed to ensure civil infrastructure’s overall safety and reliability.Non-Destructive Evaluation(NDE)methods are utilized to assess latent damage and provide decision-makers with real-time information for mitigating hazards.Within the last decade,there has been a significant increase in the research and development of innovative NDE techniques to improve data processing and promote efficient and accurate infrastructure assessment.This paper aims to review one of those methods,namely,Infrared Thermography(IRT),and its applications in civil infrastructure.A comprehensive review is presented by investigating numerous journal articles,research papers,and technical reports describing numerous IRT applications for bridges,buildings,and general civil structures made from different materials.The capability of IRT to identify and pinpoint anomalies,typically in the early stages of degradation,has excellent potential to improve the safety and shore up the dependability of civil infrastructures while reducing expenses tied to maintenance and rehabilitation.Furthermore,the non-invasive nature of IRT is beneficial in mitigating disturbances and downtime that may occur during various inspection procedures.It is highlighted that IRT is a highly versatile and effective tool for infrastructure condition assessment.With further advancement and fine-tuning of the available techniques,it is likely that IRT will continue to gain significant popularity in maintaining and monitoring civil infrastructure.展开更多
The optimization of civil engineering structures is critical for enhancing structural performance and material efficiency in engineering applications.Structural optimization approaches seek to determine the optimal de...The optimization of civil engineering structures is critical for enhancing structural performance and material efficiency in engineering applications.Structural optimization approaches seek to determine the optimal design,by considering material performance,cost,and structural safety.The design approaches aim to reduce the built environment’s energy use and carbon emissions.This comprehensive review examines optimization techniques,including size,shape,topology,and multi-objective approaches,by integrating these methodologies.The trends and advancements that contribute to developing more efficient,cost-effective,and reliable structural designs were identified.The review also discusses emerging technologies,such as machine learning applications with different optimization techniques.Optimization of truss,frame,tensegrity,reinforced concrete,origami,pantographic,and adaptive structures are covered and discussed.Optimization techniques are explained,including metaheuristics,genetic algorithm,particle swarm,ant-colony,harmony search algorithm,and their applications with mentioned structure types.Linear and non-linear structures,including geometric and material nonlinearity,are distinguished.The role of optimization in active structures,structural design,seismic design,form-finding,and structural control is taken into account,and the most recent techniques and advancements are mentioned.展开更多
In the face of data scarcity in the optimization of maintenance strategies for civil aircraft,traditional failure data-driven methods are encountering challenges owing to the increasing reliability of aircraft design....In the face of data scarcity in the optimization of maintenance strategies for civil aircraft,traditional failure data-driven methods are encountering challenges owing to the increasing reliability of aircraft design.This study addresses this issue by presenting a novel combined data fusion algorithm,which serves to enhance the accuracy and reliability of failure rate analysis for a specific aircraft model by integrating historical failure data from similar models as supplementary information.Through a comprehensive analysis of two different maintenance projects,this study illustrates the application process of the algorithm.Building upon the analysis results,this paper introduces the innovative equal integral value method as a replacement for the conventional equal interval method in the context of maintenance schedule optimization.The Monte Carlo simulation example validates that the equivalent essential value method surpasses the traditional method by over 20%in terms of inspection efficiency ratio.This discovery indicates that the equal critical value method not only upholds maintenance efficiency but also substantially decreases workload and maintenance costs.The findings of this study open up novel perspectives for airlines grappling with data scarcity,offer fresh strategies for the optimization of aviation maintenance practices,and chart a new course toward achieving more efficient and cost-effective maintenance schedule optimization through refined data analysis.展开更多
With the increasing demand for buildings and infrastructures and the mounting challenges associated with the current construction technologies such as high emission,high pollution,and high energy consumption,the civil...With the increasing demand for buildings and infrastructures and the mounting challenges associated with the current construction technologies such as high emission,high pollution,and high energy consumption,the civil engineering profession is at the crossroad for a transformation or upgrading before it can be put into tasks for these challenges.Inspired by the concept of harmonious coexistence between humans and nature,a new concept,biogenic construction,for civil engineering is proposed in this paper.The definition of biogenic construction is given.The framework and four components of biogenic construction are established.These include microbial construction,plant construction,animal construction,and bioinspired construction.Examples of each compo-nent are given.A new construction system for creating a more eco-friendly,healthier,and more sustainable environment for future civil engineering developments is also proposed.展开更多
The development of the theoretical system of civil law scholarship and the codification of civil law are closely related and of promotional function to each other.The codification of civil law can promote the systemat...The development of the theoretical system of civil law scholarship and the codification of civil law are closely related and of promotional function to each other.The codification of civil law can promote the systematization of civil law scholarship,perfection of the value system,development and modernization of civil law studies,and the systematization of legal hermeneutics.The subjectivity of China’s civil law scholarship,i.e.,the notions of problem-orientation,nativeness,practice,the times and innovations,can be improved during China’s civil law codification.The codification of civil law can promote the development of a theoretical system of civil law scholarship with Chinese characteristics,including the development of diversified elements such as values,content,system,hermeneutics and methods of civil law.展开更多
Putting the people first in human rights protection is the most distinctive feature of the outlook on human rights in contemporary China. The codification of the Civil Code of the People’s Republic of China reflects ...Putting the people first in human rights protection is the most distinctive feature of the outlook on human rights in contemporary China. The codification of the Civil Code of the People’s Republic of China reflects the people’s legislation for themselves, which is guided by the principle of putting the people first in its external system and internal values. Functionally, the Civil Code of the People’s Republic of China reflects the obligation of the country to protect human rights, constructs the framework relationship between the country and individual people, and perfects the mechanism for human rights protection. The continuous expansion of the types, contents, and functions of civil rights in the Civil Code of the People’s Republic of China is required by the broad scope of human rights, with an aim to realize a happy life for the people, the most important human rights, and protect people’s personal rights, property rights, and right to dignity through specific rules. The universal sharing of human rights requires the universality of the subjects of civil rights. The equal sharing of human rights requires the equality of forms of civil rights protection. Meanwhile, it further requires the substantive equality of civil rights protection. Attention is paid to protecting the rights and interests of specific groups in external and embedded ways.展开更多
Magnetorheological (MR) fluid is a kind of smart material whose rheological properties can be rapidly varied in magnetic field. To make full use of the advantages of MR fluid to devices, a model of double ended, shear...Magnetorheological (MR) fluid is a kind of smart material whose rheological properties can be rapidly varied in magnetic field. To make full use of the advantages of MR fluid to devices, a model of double ended, shear combined and valve typed MR damper is designed and manufactured, and the dynamic properties under sinusoidal excitations are experimentally studied. The experiment results show that the maximum damping force of the MR damper at the full magnetic intensity reaches about 20 kN while the maximum power required is less than 50 W, which predicts that the MR damper will be a powerful measurement for semi active vibration control of civil infrastructures.展开更多
Safety is one of the important topics in the field of civil aviation. Auxiliary Power Unit(APU) is one of important components in aircraft, which provides electrical power and compressed air for aircraft. The hazards ...Safety is one of the important topics in the field of civil aviation. Auxiliary Power Unit(APU) is one of important components in aircraft, which provides electrical power and compressed air for aircraft. The hazards in APU are prone to cause economic losses and even casualties. So,actively identifying the hazards in APU before an accident occurs is necessary. In this paper, a Hybrid Deep Neural Network(HDNN) based on multi-time window convolutional neural network-Bidirectional Long Short-Term Memory(CNN-Bi LSTM) neural network is proposed for active hazard identification of APU in civil aircraft. In order to identify the risks caused by different types of failures, the proposed HDNN simultaneously integrates three CNN-Bi LSTM basic models with different time window sizes in parallel by using a fully connected neural network. The CNN-Bi LSTM basic model can automatically extract features representing the system state from the input data and learn the time information of irregular trends in the time series data. Nine benchmark models are compared with the proposed HDNN. The comparison results show that the proposed HDNN has the highest identification accuracy. The HDNN has the most stable identification performance for data with imbalanced samples.展开更多
Structural health monitoring and performance prediction are crucial for smart disaster mitigation and intelligent management of structures throughout their lifespan.Recent advancements in predictive maintenance strate...Structural health monitoring and performance prediction are crucial for smart disaster mitigation and intelligent management of structures throughout their lifespan.Recent advancements in predictive maintenance strategies within the industrial manufacturing industry have inspired similar innovations in civil engineering,aiming to improve structural performance evaluation,damage diagnosis,and capacity prediction.This review delves into the framework of predictive maintenance and examines various existing solutions,focusing on critical areas such as data acquisition,condition monitoring,damage prognosis,and maintenance planning.Results from real-world applications of predictive maintenance in civil engineering,covering high-rise structures,deep foundation pits,and other infrastructure,are presented.The challenges of implementing predictive maintenance in civil engineering structures under current technology,such as model interpretability of data-driven methods and standards for predictive maintenance,are explored.Future research prospects within this area are also discussed.展开更多
The airlines need to select the optional equipment according to their individual development demands and the manufacture′s standard specification manual when purchasing a new airplane.For this customization process,t...The airlines need to select the optional equipment according to their individual development demands and the manufacture′s standard specification manual when purchasing a new airplane.For this customization process,the selection theory is mainly based on qualitative analysis and quantitative analysis.The grey incidence analysis(GIA)is used for modeling,which evaluates the correlations between optional equipment and airlines′individual demands.Meanwhile,the customization demands are quantitatively processed as different weights in evaluation index system with analytical hierarchy process.Then,the value of grey incidence degree is obtained which shows whether the optional equipment is on the purchasing list or not.Finally,two airlines′customization demands are applied in the example of aircraft cabin′s seats,so two different purchasing priorities and equipment installation lists can be obtained.The results and comparisons verify the reasonable of modeling,which provides an objective scheme of aircraft equipment selection.展开更多
To reduce engine maintenance cost and support safe operation, a prediction method of engine life on wing was proposed. This method is a kind of regression model which is a function of the condition monitoring and fail...To reduce engine maintenance cost and support safe operation, a prediction method of engine life on wing was proposed. This method is a kind of regression model which is a function of the condition monitoring and failure data. Key causes of engine removals were analyzed, and the life limit due to performance deterioration was predicted by proportional hazards model. Then the scheduled removal causes were considered as constraints of engine life to predicte the finai life on wing. Application of the proposed prediction method to the case of CF6-80C2A5 engine fleet in an airline proved its effectiveness.展开更多
The BeiDou-Ⅱcivil navigation message(BDⅡ-CNAV)is transmitted in an open environment and no information integrity protection measures are provided.Hence,the BDⅡ-CNAV faces the threat of spoofing attacks,which can le...The BeiDou-Ⅱcivil navigation message(BDⅡ-CNAV)is transmitted in an open environment and no information integrity protection measures are provided.Hence,the BDⅡ-CNAV faces the threat of spoofing attacks,which can lead to wrong location reports and time indication.In order to deal with this threat,we proposed a scheme of anti-spoofing for BDⅡ-CNAV based on integrated information authentication.This scheme generates two type authentication information,one is authentication code information(ACI),which is applied to confirm the authenticity and reliability of satellite time information,and the other is signature information,which is used to authenticate the integrity of satellite location information and other information.Both authentication information is designed to embed into the reserved bits in BDⅡ-CNAV without changing the frame structure.In order to avoid authentication failure caused by public key error or key error,the key or public key prompt information(KPKPI)are designed to remind the receiver to update both keys in time.Experimental results indicate that the scheme can successfully detect spoofing attacks,and the authentication delay is less than 1%of the transmission delay,which meets the requirements of BDⅡ-CNAV information authentication.展开更多
The relationship between environmental quality and economic growth has been a hot topic for decades.After years of rapid industrialization and urbanization,China’s environmental challenges are approaching a turning p...The relationship between environmental quality and economic growth has been a hot topic for decades.After years of rapid industrialization and urbanization,China’s environmental challenges are approaching a turning point.Following the principles of ecological civilization construction,China is on its way to maintaining high-quality and green economic development.On 10 June 2020,the Chinese Government reported the key findings of the Second National General Survey of Pollution Sources(fiscal year 2017),which provides strong quantitative evidence of progress toward ecological civilization.In terms of our comparison between the two National General Surveys in 2007 and 2017,it was found that environmental pollution,measured in terms of many wastewater and air emission pollutant discharges,is decreasing despite the steady growth in economic activities—and at a noticeably fast pace.Other national and local governments can adopt some of China’s ecological civilization practices,within their own individual contexts.展开更多
In the last twenty years, near-field problems became an important topic for both seismologists and civil engineers. The one aspect is to illuminate mechanisms of earthquakes and explain new phenomena. The another aspe...In the last twenty years, near-field problems became an important topic for both seismologists and civil engineers. The one aspect is to illuminate mechanisms of earthquakes and explain new phenomena. The another aspect is the ground motions, which are usually assigned by engineers as a type of input load for seismic design of structures, sometimes can control the final design results. The experiments, performance evaluations and other related aspects are all based on the specified type of load. As a result, many aspects related to civil engineering will be influenced by changes of the type of load, Hence, the characteristics of the load and the corresponding response of structures are desired for studying. In this paper, the state-of-the-art of near-field problems in civil engineering is comprehensively reviewed, which include inherent characteristics of near-field ground motions and influences of these ground motions on civil structures. The existing problems are pointed out and work needed to be further investigated in the future is suggested. It is believed that the information in this paper can be useful to advance the state of investigation on near-field problems.展开更多
基金supported by the Vocational Education Research Project from China Commercial Technicians Association:“Research on the Construction and Application of AI-Enabled English Testing System for Civil Aviation Ground Services”(20ZSJYB20250420)the Education Science Planning Projects(Higher Education Special Program)from Guangdong Provincial Department of Education:“Research on the Evaluation System of Digital Competence in Curriculum Ideology and Politics for Higher Vocational Teachers in Guangdong under the Background of Educational Digitalization”(2024GXJK877)“Digital Empowerment for High-Quality Development in Guangdong:An Innovative Study on Cultivating Interdisciplinary Foreign Language Talents”(2023GXJK691).
文摘The integration of Communicative Language Testing(CLT)principles with AI-driven automated assessment poses a significant challenge in professional language testing.Addressing this issue within the specific context of Civil Aviation Ground Service English,this study explores pathways for their logical reconciliation.Through conceptual analysis and theoretical deduction,with a focus on human-AI interaction scenarios,we demonstrate that the synergy between CLT and AI stems from a shared focus on competency measurement.Key findings reveal that:(1)standardized competency dimensions in CLT can be operationalized into data-processable formats for AI;(2)within professional contexts,AI algorithms can be tailored using authentic service corpora to meet CLT’s demand for situational authenticity;and(3)a division of labor based on competency level-where AI handles standardized scoring of lower-order competencies and human-AI collaboration assesses higher-order competencies-effectively resolves the tension between CLT’s dynamic communication and AI’s static algorithms.Ultimately,the study constructs a three-dimensional integration framework encompassing“professional register,”“competency level,”and“human-AI division of labor,”offering a theoretical model for CLT-AI integration and a practical blueprint for innovating Civil Aviation Ground Service English assessment.
文摘This study provides the first systematic evaluation of image resolution’s effect (50-300 PPI, pixels per inch) on UAV (unmanned aerial vehicle)-based digital close-range photogrammetry accuracy in civil engineering applications, such as infrastructure monitoring and heritage preservation. Using a high-resolution UAV with a 20 MP (MegaPixels) sensor, four images of a brick wall test field were captured and processed in Agisoft Metashape, with resolutions compared against Leica T2002 theodolite measurements (1.0 mm accuracy). Advanced statistical methods (ANOVA (analysis of variance), Tukey tests, Monte Carlo simulations) and ground control points validated the results. Accuracy improved from 25 mm at 50 PPI to 5 mm at 150 PPI (p < 0.01), plateauing at 4 mm beyond 200 PPI, while 150 PPI reduced processing time by 62% compared to 300 PPI. Unlike prior studies, this research uniquely isolates resolution effects in a controlled civil engineering context, offering a novel 150 PPI threshold that balances precision and efficiency. This threshold supports Saudi Vision 2030’s smart infrastructure goals for megaprojects like NEOM, providing a scalable framework for global applications. Future research should leverage deep learning to optimize resolutions in dynamic environments.
文摘Civil infrastructure is continuously subject to aging and deterioration due to multiple factors,which lead to a decline in performance and impact structural health.Accumulated damage on structures increases operational costs and poses significant risks to public safety.Effective maintenance,repair,and rehabilitation strategies are needed to ensure civil infrastructure’s overall safety and reliability.Non-Destructive Evaluation(NDE)methods are utilized to assess latent damage and provide decision-makers with real-time information for mitigating hazards.Within the last decade,there has been a significant increase in the research and development of innovative NDE techniques to improve data processing and promote efficient and accurate infrastructure assessment.This paper aims to review one of those methods,namely,Infrared Thermography(IRT),and its applications in civil infrastructure.A comprehensive review is presented by investigating numerous journal articles,research papers,and technical reports describing numerous IRT applications for bridges,buildings,and general civil structures made from different materials.The capability of IRT to identify and pinpoint anomalies,typically in the early stages of degradation,has excellent potential to improve the safety and shore up the dependability of civil infrastructures while reducing expenses tied to maintenance and rehabilitation.Furthermore,the non-invasive nature of IRT is beneficial in mitigating disturbances and downtime that may occur during various inspection procedures.It is highlighted that IRT is a highly versatile and effective tool for infrastructure condition assessment.With further advancement and fine-tuning of the available techniques,it is likely that IRT will continue to gain significant popularity in maintaining and monitoring civil infrastructure.
文摘The optimization of civil engineering structures is critical for enhancing structural performance and material efficiency in engineering applications.Structural optimization approaches seek to determine the optimal design,by considering material performance,cost,and structural safety.The design approaches aim to reduce the built environment’s energy use and carbon emissions.This comprehensive review examines optimization techniques,including size,shape,topology,and multi-objective approaches,by integrating these methodologies.The trends and advancements that contribute to developing more efficient,cost-effective,and reliable structural designs were identified.The review also discusses emerging technologies,such as machine learning applications with different optimization techniques.Optimization of truss,frame,tensegrity,reinforced concrete,origami,pantographic,and adaptive structures are covered and discussed.Optimization techniques are explained,including metaheuristics,genetic algorithm,particle swarm,ant-colony,harmony search algorithm,and their applications with mentioned structure types.Linear and non-linear structures,including geometric and material nonlinearity,are distinguished.The role of optimization in active structures,structural design,seismic design,form-finding,and structural control is taken into account,and the most recent techniques and advancements are mentioned.
文摘In the face of data scarcity in the optimization of maintenance strategies for civil aircraft,traditional failure data-driven methods are encountering challenges owing to the increasing reliability of aircraft design.This study addresses this issue by presenting a novel combined data fusion algorithm,which serves to enhance the accuracy and reliability of failure rate analysis for a specific aircraft model by integrating historical failure data from similar models as supplementary information.Through a comprehensive analysis of two different maintenance projects,this study illustrates the application process of the algorithm.Building upon the analysis results,this paper introduces the innovative equal integral value method as a replacement for the conventional equal interval method in the context of maintenance schedule optimization.The Monte Carlo simulation example validates that the equivalent essential value method surpasses the traditional method by over 20%in terms of inspection efficiency ratio.This discovery indicates that the equal critical value method not only upholds maintenance efficiency but also substantially decreases workload and maintenance costs.The findings of this study open up novel perspectives for airlines grappling with data scarcity,offer fresh strategies for the optimization of aviation maintenance practices,and chart a new course toward achieving more efficient and cost-effective maintenance schedule optimization through refined data analysis.
文摘With the increasing demand for buildings and infrastructures and the mounting challenges associated with the current construction technologies such as high emission,high pollution,and high energy consumption,the civil engineering profession is at the crossroad for a transformation or upgrading before it can be put into tasks for these challenges.Inspired by the concept of harmonious coexistence between humans and nature,a new concept,biogenic construction,for civil engineering is proposed in this paper.The definition of biogenic construction is given.The framework and four components of biogenic construction are established.These include microbial construction,plant construction,animal construction,and bioinspired construction.Examples of each compo-nent are given.A new construction system for creating a more eco-friendly,healthier,and more sustainable environment for future civil engineering developments is also proposed.
基金This article is the phased achievement of the National Social Science Fund Project:“Research on the Legislation on Personality Rights”(18ZDA143).
文摘The development of the theoretical system of civil law scholarship and the codification of civil law are closely related and of promotional function to each other.The codification of civil law can promote the systematization of civil law scholarship,perfection of the value system,development and modernization of civil law studies,and the systematization of legal hermeneutics.The subjectivity of China’s civil law scholarship,i.e.,the notions of problem-orientation,nativeness,practice,the times and innovations,can be improved during China’s civil law codification.The codification of civil law can promote the development of a theoretical system of civil law scholarship with Chinese characteristics,including the development of diversified elements such as values,content,system,hermeneutics and methods of civil law.
基金accomplishment under the Scientific Research Fund Program of Renmin University of China (Project Approval No. 22XNQT12)。
文摘Putting the people first in human rights protection is the most distinctive feature of the outlook on human rights in contemporary China. The codification of the Civil Code of the People’s Republic of China reflects the people’s legislation for themselves, which is guided by the principle of putting the people first in its external system and internal values. Functionally, the Civil Code of the People’s Republic of China reflects the obligation of the country to protect human rights, constructs the framework relationship between the country and individual people, and perfects the mechanism for human rights protection. The continuous expansion of the types, contents, and functions of civil rights in the Civil Code of the People’s Republic of China is required by the broad scope of human rights, with an aim to realize a happy life for the people, the most important human rights, and protect people’s personal rights, property rights, and right to dignity through specific rules. The universal sharing of human rights requires the universality of the subjects of civil rights. The equal sharing of human rights requires the equality of forms of civil rights protection. Meanwhile, it further requires the substantive equality of civil rights protection. Attention is paid to protecting the rights and interests of specific groups in external and embedded ways.
文摘Magnetorheological (MR) fluid is a kind of smart material whose rheological properties can be rapidly varied in magnetic field. To make full use of the advantages of MR fluid to devices, a model of double ended, shear combined and valve typed MR damper is designed and manufactured, and the dynamic properties under sinusoidal excitations are experimentally studied. The experiment results show that the maximum damping force of the MR damper at the full magnetic intensity reaches about 20 kN while the maximum power required is less than 50 W, which predicts that the MR damper will be a powerful measurement for semi active vibration control of civil infrastructures.
基金co-supported by National Natural Science Foundation of China(No.U1933202)Natural Science Foundation of Civil Aviation University of China(No.U1733201)+1 种基金China Scholarship Council(CSC)(No.201906830043)Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Nos.KYCX18_0310 and KYCX18_0265)。
文摘Safety is one of the important topics in the field of civil aviation. Auxiliary Power Unit(APU) is one of important components in aircraft, which provides electrical power and compressed air for aircraft. The hazards in APU are prone to cause economic losses and even casualties. So,actively identifying the hazards in APU before an accident occurs is necessary. In this paper, a Hybrid Deep Neural Network(HDNN) based on multi-time window convolutional neural network-Bidirectional Long Short-Term Memory(CNN-Bi LSTM) neural network is proposed for active hazard identification of APU in civil aircraft. In order to identify the risks caused by different types of failures, the proposed HDNN simultaneously integrates three CNN-Bi LSTM basic models with different time window sizes in parallel by using a fully connected neural network. The CNN-Bi LSTM basic model can automatically extract features representing the system state from the input data and learn the time information of irregular trends in the time series data. Nine benchmark models are compared with the proposed HDNN. The comparison results show that the proposed HDNN has the highest identification accuracy. The HDNN has the most stable identification performance for data with imbalanced samples.
基金The National Natural Science Foundation of China(No.52278312)the National Key Research and Development Program of China(No.2022YFC3801202)the Fundamental Research Funds for the Central Universities.
文摘Structural health monitoring and performance prediction are crucial for smart disaster mitigation and intelligent management of structures throughout their lifespan.Recent advancements in predictive maintenance strategies within the industrial manufacturing industry have inspired similar innovations in civil engineering,aiming to improve structural performance evaluation,damage diagnosis,and capacity prediction.This review delves into the framework of predictive maintenance and examines various existing solutions,focusing on critical areas such as data acquisition,condition monitoring,damage prognosis,and maintenance planning.Results from real-world applications of predictive maintenance in civil engineering,covering high-rise structures,deep foundation pits,and other infrastructure,are presented.The challenges of implementing predictive maintenance in civil engineering structures under current technology,such as model interpretability of data-driven methods and standards for predictive maintenance,are explored.Future research prospects within this area are also discussed.
文摘The airlines need to select the optional equipment according to their individual development demands and the manufacture′s standard specification manual when purchasing a new airplane.For this customization process,the selection theory is mainly based on qualitative analysis and quantitative analysis.The grey incidence analysis(GIA)is used for modeling,which evaluates the correlations between optional equipment and airlines′individual demands.Meanwhile,the customization demands are quantitatively processed as different weights in evaluation index system with analytical hierarchy process.Then,the value of grey incidence degree is obtained which shows whether the optional equipment is on the purchasing list or not.Finally,two airlines′customization demands are applied in the example of aircraft cabin′s seats,so two different purchasing priorities and equipment installation lists can be obtained.The results and comparisons verify the reasonable of modeling,which provides an objective scheme of aircraft equipment selection.
基金The joint fundations of National Natural Science Foundation of China and Civil Aviation Administration of China (60672164)National High-tech Research and Development Program of China (863 Program)(2006AA04Z427)
文摘To reduce engine maintenance cost and support safe operation, a prediction method of engine life on wing was proposed. This method is a kind of regression model which is a function of the condition monitoring and failure data. Key causes of engine removals were analyzed, and the life limit due to performance deterioration was predicted by proportional hazards model. Then the scheduled removal causes were considered as constraints of engine life to predicte the finai life on wing. Application of the proposed prediction method to the case of CF6-80C2A5 engine fleet in an airline proved its effectiveness.
基金supported in part by the National Key R&D Program of China(No.2022YFB3904503)National Natural Science Foundation of China(No.62172418)。
文摘The BeiDou-Ⅱcivil navigation message(BDⅡ-CNAV)is transmitted in an open environment and no information integrity protection measures are provided.Hence,the BDⅡ-CNAV faces the threat of spoofing attacks,which can lead to wrong location reports and time indication.In order to deal with this threat,we proposed a scheme of anti-spoofing for BDⅡ-CNAV based on integrated information authentication.This scheme generates two type authentication information,one is authentication code information(ACI),which is applied to confirm the authenticity and reliability of satellite time information,and the other is signature information,which is used to authenticate the integrity of satellite location information and other information.Both authentication information is designed to embed into the reserved bits in BDⅡ-CNAV without changing the frame structure.In order to avoid authentication failure caused by public key error or key error,the key or public key prompt information(KPKPI)are designed to remind the receiver to update both keys in time.Experimental results indicate that the scheme can successfully detect spoofing attacks,and the authentication delay is less than 1%of the transmission delay,which meets the requirements of BDⅡ-CNAV information authentication.
基金Huabo Duan acknowledges financial support from the China National Key Research and Development(R&D)Plan(2018YFB1502804)the Scientific Research Fund of Introduced High Talent of Shenzhen University(827-000044),China.
文摘The relationship between environmental quality and economic growth has been a hot topic for decades.After years of rapid industrialization and urbanization,China’s environmental challenges are approaching a turning point.Following the principles of ecological civilization construction,China is on its way to maintaining high-quality and green economic development.On 10 June 2020,the Chinese Government reported the key findings of the Second National General Survey of Pollution Sources(fiscal year 2017),which provides strong quantitative evidence of progress toward ecological civilization.In terms of our comparison between the two National General Surveys in 2007 and 2017,it was found that environmental pollution,measured in terms of many wastewater and air emission pollutant discharges,is decreasing despite the steady growth in economic activities—and at a noticeably fast pace.Other national and local governments can adopt some of China’s ecological civilization practices,within their own individual contexts.
基金National Natural Science Foundation of China (50538050, 50608024)
文摘In the last twenty years, near-field problems became an important topic for both seismologists and civil engineers. The one aspect is to illuminate mechanisms of earthquakes and explain new phenomena. The another aspect is the ground motions, which are usually assigned by engineers as a type of input load for seismic design of structures, sometimes can control the final design results. The experiments, performance evaluations and other related aspects are all based on the specified type of load. As a result, many aspects related to civil engineering will be influenced by changes of the type of load, Hence, the characteristics of the load and the corresponding response of structures are desired for studying. In this paper, the state-of-the-art of near-field problems in civil engineering is comprehensively reviewed, which include inherent characteristics of near-field ground motions and influences of these ground motions on civil structures. The existing problems are pointed out and work needed to be further investigated in the future is suggested. It is believed that the information in this paper can be useful to advance the state of investigation on near-field problems.
