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
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
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
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
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
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
Neutrosophic theory can effectively and reasonably express indeterminate,inconsistent,and incomplete information.Since Smarandache proposed the neutrosophic theory in 1998,neutrosophic theory and related research have...Neutrosophic theory can effectively and reasonably express indeterminate,inconsistent,and incomplete information.Since Smarandache proposed the neutrosophic theory in 1998,neutrosophic theory and related research have been developed and applied to many important fields.Indeterminacy and fuzziness are one of the main research issues in the field of civil engineering.Therefore,the neutrosophic theory is very suitable for modeling and applications of civil engineering fields.This review paper mainly describes the recent developments and applications of neutrosophic theory in four important research areas of civil engineering:the neutrosophic decision-making theory and applied methods,the neutrosophic evaluation methods and applications of slope stability,the neutrosophic expressions and analyses of rock joint roughness coefficient,and the neutrosophic structural optimization methods and applications.In terms of these research achievements in the four areas of civil engineering,the neutrosophic theory demonstrates its advantages in dealing with the indeterminate and inconsistent issues in civil engineering and the effectiveness and practicability of existing applied methods.In the future work,the existing research results will be further improved and extended in civil engineering problems.In addition,the neutrosophic theory will also have better application prospects in other fields of civil engineering.展开更多
Fireworks products are energy-containing materials and are hazardous during production,storage,transportation,and use.By analyzing the range of civil aviation ground ambient temperature and civil aviation cabin ambien...Fireworks products are energy-containing materials and are hazardous during production,storage,transportation,and use.By analyzing the range of civil aviation ground ambient temperature and civil aviation cabin ambient temperature in storage and ground operation as well as establishing a spontaneous combustion mathematical model for cylindrical fireworks products based on the spontaneous combustion theory,we identified the critical temperature for spontaneous combustion of a single spray and analyzed the thermal safety of fireworks products under the civil aviation ambient temperature by example to provide theoretical support for the feasibility study of transporting fireworks products by civil aviation.展开更多
Green vocational education is a proactive response to the social objectives of sustainable development,building upon traditional vocational education.It serves as a crucial means to achieve sustainable development in ...Green vocational education is a proactive response to the social objectives of sustainable development,building upon traditional vocational education.It serves as a crucial means to achieve sustainable development in both urban and rural areas.Green vocational education plays a significant role in cultivating diverse talents for rural revitalization.Therefore,there are corresponding pathways for implementing civil engineering talent training.This paper examines the current state of green vocational education development in Guangxi within the context of rural revitalization and proposes an implementation pathway based on civil engineering majors.These findings provide valuable insights towards realizing the integration and transformation of green vocational education.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
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
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 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 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.
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Neutrosophic theory can effectively and reasonably express indeterminate,inconsistent,and incomplete information.Since Smarandache proposed the neutrosophic theory in 1998,neutrosophic theory and related research have been developed and applied to many important fields.Indeterminacy and fuzziness are one of the main research issues in the field of civil engineering.Therefore,the neutrosophic theory is very suitable for modeling and applications of civil engineering fields.This review paper mainly describes the recent developments and applications of neutrosophic theory in four important research areas of civil engineering:the neutrosophic decision-making theory and applied methods,the neutrosophic evaluation methods and applications of slope stability,the neutrosophic expressions and analyses of rock joint roughness coefficient,and the neutrosophic structural optimization methods and applications.In terms of these research achievements in the four areas of civil engineering,the neutrosophic theory demonstrates its advantages in dealing with the indeterminate and inconsistent issues in civil engineering and the effectiveness and practicability of existing applied methods.In the future work,the existing research results will be further improved and extended in civil engineering problems.In addition,the neutrosophic theory will also have better application prospects in other fields of civil engineering.
基金“Chenguang Program”supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(16CGB28).
文摘Fireworks products are energy-containing materials and are hazardous during production,storage,transportation,and use.By analyzing the range of civil aviation ground ambient temperature and civil aviation cabin ambient temperature in storage and ground operation as well as establishing a spontaneous combustion mathematical model for cylindrical fireworks products based on the spontaneous combustion theory,we identified the critical temperature for spontaneous combustion of a single spray and analyzed the thermal safety of fireworks products under the civil aviation ambient temperature by example to provide theoretical support for the feasibility study of transporting fireworks products by civil aviation.
基金This study was financially supported by Education and Teaching Research Projects of China Construction Education Association 2023-Exploration and Practice of Digital Talent Cultivation for Intelligent Buildings Oriented towards China-ASEAN(Grant No.2023265).
文摘Green vocational education is a proactive response to the social objectives of sustainable development,building upon traditional vocational education.It serves as a crucial means to achieve sustainable development in both urban and rural areas.Green vocational education plays a significant role in cultivating diverse talents for rural revitalization.Therefore,there are corresponding pathways for implementing civil engineering talent training.This paper examines the current state of green vocational education development in Guangxi within the context of rural revitalization and proposes an implementation pathway based on civil engineering majors.These findings provide valuable insights towards realizing the integration and transformation of green vocational education.
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.
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.