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
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
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 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
With the advent of the big data era and the rise of Industrial Revolution 4.0,digital twins(DTs)have gained sig-nificant attention in various industries.DTs offer the opportunity to combine the physical and digital wor...With the advent of the big data era and the rise of Industrial Revolution 4.0,digital twins(DTs)have gained sig-nificant attention in various industries.DTs offer the opportunity to combine the physical and digital worlds and aid the digital transformation of the civil engineering industry.In this paper,605 documents obtained from the search werefirst analysed using CiteSpace for literature visualisation,and an author co-occurrence network,a keyword co-occurrence network,and a keyword clustering set were obtained.Next,through a literature review of 86 papers,this paper summarises the current status of DT application in civil engineering based on a review of the origins,concepts,and implementation techniques of DTs,and it introduces the application of DTs in the full project lifecycle.This study shows that DTs have great potential to address many of the challenges faced by civil engineering.In this regard,the paper also presents some thoughts on the future directions of DT research.展开更多
Due to the lack of authentication mechanism in BeiDou navigation satellite system(BDS),BD-Ⅱ civil navigation message(BDⅡ-CNAV) are vulnerable to spoofing attack and replay attack.To solve this problem,we present a s...Due to the lack of authentication mechanism in BeiDou navigation satellite system(BDS),BD-Ⅱ civil navigation message(BDⅡ-CNAV) are vulnerable to spoofing attack and replay attack.To solve this problem,we present a security authentication protocol,called as BDSec,which is designed by using China’s cryptography Shangyong Mima(SM) series algorithms,such as SM2/4/9 and Zu Chongzhi(ZUC)algorithm.In BDSec protocol,both of BDⅡ-CNAV and signature information are encrypted using the SM4 algorithm(Symmetric encryption mechanism).The encrypted result is used as the subject authentication information.BDSec protocol applies SM9 algorithm(Identity-based cryptography mechanism) to protect the integrity of the BDⅡ-CNAV,adopts the SM2 algorithm(Public key cryptosystem) to guarantee the confidentiality of the important session information,and uses the ZUC algorithm(Encryption and integrity algorithm) to verify the integrity of the message authentication serial number and initial information and the information in authentication initialization sub-protocol respectively.The results of the SVO logic reasoning and performance analysis show that BDSec protocol meets security requirements for the dual user identity authentication in BDS and can realize the security authentication of BDⅡ-CNAV.展开更多
This article examines the pathway to digital transformation and upgrading in undergraduate institutions,using the civil engineering program at Chongqing Three Gorges University as a case study,focusing on six key area...This article examines the pathway to digital transformation and upgrading in undergraduate institutions,using the civil engineering program at Chongqing Three Gorges University as a case study,focusing on six key areas:developing a high-quality digital talent training program for civil engineering;assembling diverse resources to create a digital,multi-scenario open learning environment that encompasses teaching,research,and practical training for civil engineering undergraduates;piloting innovative digital teaching models for civil engineering undergraduates;crafting a new model for digital resource provision,utilizing self-developed and specialized resources;devising assessment methods and ongoing improvement strategies based on the achievement of students’digital competencies;and devising a new,three-dimensional,multi-modal teaching evaluation system through intelligent data capture and analysis.展开更多
Adverse weather during aircraft operation generates more complex scenarios for tactical trajectory planning,which requires superior real-time performance and conflict-free reliability of solving methods.Multi-aircraft...Adverse weather during aircraft operation generates more complex scenarios for tactical trajectory planning,which requires superior real-time performance and conflict-free reliability of solving methods.Multi-aircraft real-time 4D trajectory planning under adverse weather is an essential problem in Air Traffic Control(ATC)and it is challenging for the existing methods to be applied effectively.A framework of Double Deep Q-value Network under the Critic guidance with heuristic Pairing(DDQNC-P)is proposed to solve this problem.An Agent for two aircraft synergetic trajectory planning is trained by the Deep Reinforcement Learning(DRL)model of DDQNC,which completes two aircraft 4D trajectory planning tasks preliminarily under dynamic weather conditions.Then a heuristic pairing algorithm is designed to convert the multi-aircraft synergetic trajectory planning into multi-time pairwise synergetic trajectory planning,making the multiaircraft trajectory planning problem processable for the trained Agent.This framework compresses the input dimensions of the DRL model while improving its generalization ability significantly.Substantial simulations with various aircraft numbers,weather conditions,and airspace structures were conducted for performance verification and comparison.The success rate of conflict-free trajectory resolution reached 96.56% with an average calculation time of 0.41 s for 3504D trajectory points per aircraft,finally confirming its applicability to make real-time decision-making support for controllers in real-world ATC systems.展开更多
Objective:To investigate and analyze the annual physical examination results of retired employees from a unit in the civil aviation system,focusing on blood lipids,blood glucose,blood uric acid,and blood routine resul...Objective:To investigate and analyze the annual physical examination results of retired employees from a unit in the civil aviation system,focusing on blood lipids,blood glucose,blood uric acid,and blood routine results.The study aims to provide relevant references for formulating reasonable disease management measures for preventing and controlling hyperlipidemia,hyperuricemia,and other conditions in retired employees.Methods:The examination results of 231 participants were collected and analyzed.The participants were divided into four groups based on age:middle-aged group,young-old group,middle-old group,and old-old group.The blood test results were compared across these groups,and an assessment of atherosclerotic cardiovascular disease(ASCVD)risk levels was completed in conjunction with medical history.Blood test results were also compared by gender.Results:There were no significant statistical differences in blood test results when grouped by age.However,the prevalence of hyperuricemia was higher in males than in females,while the prevalence of hypercholesterolemia was higher in females than in males.The LDL-C target achievement rate was lower in the moderate-and-high-risk group as well as the very high-risk group as defined by ASCVD risk levels.Conclusion:Management of hyperuricemia and hyperlipidemia in retired employees(elderly patients)should be strengthened to reduce the risk of ASCVD events and alleviate the potential medical burden associated with disease progression.展开更多
In the last decade,the detection and attribution science that links climate change to extreme weather and climate events has emerged as a growing field of research with an increasing body of literature.This paper over...In the last decade,the detection and attribution science that links climate change to extreme weather and climate events has emerged as a growing field of research with an increasing body of literature.This paper overviews the methods for extreme event attribution(EEA)and discusses the new insights that EEA provides for infrastructure adaptation.We found that EEA can inform stakeholders about current climate risk,support vulnerability-based and hazard-based adaptations,assist in the development of cost-effective adaptation strategies,and enhance justice and equity in the allocation of adaptation resources.As engineering practice shifts from a retrospective approach to a proactive,forward-looking risk management strategy,EEA can be used together with climate projections to enhance the comprehensiveness of decision making,including planning and preparing for un-precedented extreme events.Additionally,attribution assessment can be more useful for adaptation planning when the exposure and vulnerability of communities to past events are analyzed,and future changes in the probability of extreme events are evaluated.Given large uncertainties inherent in event attribution and climate projections,future research should examine the sensitivity of engineering design to climate model uncertainties,and adapt engineering practice,including building codes,to uncertain future conditions.While this study focuses on adaptation planning,EEA can also be a useful tool for informing and enhancing decisions related to climate mitigation.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
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
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.
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supported by the Key Research and Development Program of Zhejiang(Grant No.2023C03183)the Natural Science Foundation of Zhejiang Province(Grant No.LY23E080005)Science and Technology Project of Zhejiang Provincial Department of Transport(Grant No.202225).
文摘With the advent of the big data era and the rise of Industrial Revolution 4.0,digital twins(DTs)have gained sig-nificant attention in various industries.DTs offer the opportunity to combine the physical and digital worlds and aid the digital transformation of the civil engineering industry.In this paper,605 documents obtained from the search werefirst analysed using CiteSpace for literature visualisation,and an author co-occurrence network,a keyword co-occurrence network,and a keyword clustering set were obtained.Next,through a literature review of 86 papers,this paper summarises the current status of DT application in civil engineering based on a review of the origins,concepts,and implementation techniques of DTs,and it introduces the application of DTs in the full project lifecycle.This study shows that DTs have great potential to address many of the challenges faced by civil engineering.In this regard,the paper also presents some thoughts on the future directions of DT research.
基金supported in part by the National Key R&D Program of China(No.2022YFB3904503)National Natural Science Foundation of China(No.62172418)the joint funds of National Natural Science Foundation of China and Civil Aviation Administration of China(No.U2133203).
文摘Due to the lack of authentication mechanism in BeiDou navigation satellite system(BDS),BD-Ⅱ civil navigation message(BDⅡ-CNAV) are vulnerable to spoofing attack and replay attack.To solve this problem,we present a security authentication protocol,called as BDSec,which is designed by using China’s cryptography Shangyong Mima(SM) series algorithms,such as SM2/4/9 and Zu Chongzhi(ZUC)algorithm.In BDSec protocol,both of BDⅡ-CNAV and signature information are encrypted using the SM4 algorithm(Symmetric encryption mechanism).The encrypted result is used as the subject authentication information.BDSec protocol applies SM9 algorithm(Identity-based cryptography mechanism) to protect the integrity of the BDⅡ-CNAV,adopts the SM2 algorithm(Public key cryptosystem) to guarantee the confidentiality of the important session information,and uses the ZUC algorithm(Encryption and integrity algorithm) to verify the integrity of the message authentication serial number and initial information and the information in authentication initialization sub-protocol respectively.The results of the SVO logic reasoning and performance analysis show that BDSec protocol meets security requirements for the dual user identity authentication in BDS and can realize the security authentication of BDⅡ-CNAV.
基金Chongqing Higher Education Teaching Reform Research Key Project(Project number:222128)Chongqing Three Gorges University Higher Education Research Project(Project number:JGSZH2203)+3 种基金Chongqing Education Science Planning Project(Project number:K23ZG2120245,K22ZS212737,K23YD2120100)Chongqing Three Gorges University First-Class Undergraduate Course“Principles of Steel Structures”Chongqing Three Gorges University Course Ideological and Political Demonstration Course“Principles of Steel Structures”Chongqing First-Class Undergraduate Course“Principles of Steel Structures”。
文摘This article examines the pathway to digital transformation and upgrading in undergraduate institutions,using the civil engineering program at Chongqing Three Gorges University as a case study,focusing on six key areas:developing a high-quality digital talent training program for civil engineering;assembling diverse resources to create a digital,multi-scenario open learning environment that encompasses teaching,research,and practical training for civil engineering undergraduates;piloting innovative digital teaching models for civil engineering undergraduates;crafting a new model for digital resource provision,utilizing self-developed and specialized resources;devising assessment methods and ongoing improvement strategies based on the achievement of students’digital competencies;and devising a new,three-dimensional,multi-modal teaching evaluation system through intelligent data capture and analysis.
基金the support of the Chinese Special Research Project for Civil Aircraft(No.MJZ1-7N22)the National Natural Science Foundation of China(No.U2133207).
文摘Adverse weather during aircraft operation generates more complex scenarios for tactical trajectory planning,which requires superior real-time performance and conflict-free reliability of solving methods.Multi-aircraft real-time 4D trajectory planning under adverse weather is an essential problem in Air Traffic Control(ATC)and it is challenging for the existing methods to be applied effectively.A framework of Double Deep Q-value Network under the Critic guidance with heuristic Pairing(DDQNC-P)is proposed to solve this problem.An Agent for two aircraft synergetic trajectory planning is trained by the Deep Reinforcement Learning(DRL)model of DDQNC,which completes two aircraft 4D trajectory planning tasks preliminarily under dynamic weather conditions.Then a heuristic pairing algorithm is designed to convert the multi-aircraft synergetic trajectory planning into multi-time pairwise synergetic trajectory planning,making the multiaircraft trajectory planning problem processable for the trained Agent.This framework compresses the input dimensions of the DRL model while improving its generalization ability significantly.Substantial simulations with various aircraft numbers,weather conditions,and airspace structures were conducted for performance verification and comparison.The success rate of conflict-free trajectory resolution reached 96.56% with an average calculation time of 0.41 s for 3504D trajectory points per aircraft,finally confirming its applicability to make real-time decision-making support for controllers in real-world ATC systems.
文摘Objective:To investigate and analyze the annual physical examination results of retired employees from a unit in the civil aviation system,focusing on blood lipids,blood glucose,blood uric acid,and blood routine results.The study aims to provide relevant references for formulating reasonable disease management measures for preventing and controlling hyperlipidemia,hyperuricemia,and other conditions in retired employees.Methods:The examination results of 231 participants were collected and analyzed.The participants were divided into four groups based on age:middle-aged group,young-old group,middle-old group,and old-old group.The blood test results were compared across these groups,and an assessment of atherosclerotic cardiovascular disease(ASCVD)risk levels was completed in conjunction with medical history.Blood test results were also compared by gender.Results:There were no significant statistical differences in blood test results when grouped by age.However,the prevalence of hyperuricemia was higher in males than in females,while the prevalence of hypercholesterolemia was higher in females than in males.The LDL-C target achievement rate was lower in the moderate-and-high-risk group as well as the very high-risk group as defined by ASCVD risk levels.Conclusion:Management of hyperuricemia and hyperlipidemia in retired employees(elderly patients)should be strengthened to reduce the risk of ASCVD events and alleviate the potential medical burden associated with disease progression.
文摘In the last decade,the detection and attribution science that links climate change to extreme weather and climate events has emerged as a growing field of research with an increasing body of literature.This paper overviews the methods for extreme event attribution(EEA)and discusses the new insights that EEA provides for infrastructure adaptation.We found that EEA can inform stakeholders about current climate risk,support vulnerability-based and hazard-based adaptations,assist in the development of cost-effective adaptation strategies,and enhance justice and equity in the allocation of adaptation resources.As engineering practice shifts from a retrospective approach to a proactive,forward-looking risk management strategy,EEA can be used together with climate projections to enhance the comprehensiveness of decision making,including planning and preparing for un-precedented extreme events.Additionally,attribution assessment can be more useful for adaptation planning when the exposure and vulnerability of communities to past events are analyzed,and future changes in the probability of extreme events are evaluated.Given large uncertainties inherent in event attribution and climate projections,future research should examine the sensitivity of engineering design to climate model uncertainties,and adapt engineering practice,including building codes,to uncertain future conditions.While this study focuses on adaptation planning,EEA can also be a useful tool for informing and enhancing decisions related to climate mitigation.
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.
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.
