A engineering system is usually repairable, and failure process of a repairable by a failure point process. The power law model is a commonly used approach to model syst the em is often described failure point process...A engineering system is usually repairable, and failure process of a repairable by a failure point process. The power law model is a commonly used approach to model syst the em is often described failure point process. This paper introduces the concept and model for the failure process of repairable system. The method of parameter estimation is developed, and failure observations are fitted into a power-law model by using the least square method. Two applications of the pressent model are discussed according to the practical failure data of the central cooling system of a nuclear power plant. One application is determining the optimal overhaul time, and the other is evaluating the quality of maintenance. This paper provides references for the overhaul decision making and maintenance quality evaluation in reality.展开更多
As a critical Internet infrastructure,domain name system(DNS)protects the authenticity and integrity of domain resource records with the introduction of security extensions(DNSSEC).DNSSEC builds a single-center and hi...As a critical Internet infrastructure,domain name system(DNS)protects the authenticity and integrity of domain resource records with the introduction of security extensions(DNSSEC).DNSSEC builds a single-center and hierarchical resource authentication architecture,which brings management convenience but places the DNS at risk from a single point of failure.When the root key suffers a leak or misconfiguration,top level domain(TLD)authority cannot independently protect the authenticity of TLD data in the root zone.In this paper,we propose self-certificating root,a lightweight security enhancement mechanism of root zone compatible with DNS/DNSSEC protocol.By adding the TLD public key and signature of the glue records to the root zone,this mechanism enables the TLD authority to certify the self-submitted data in the root zone and protects the TLD authority from the risk of root key failure.This mechanism is implemented on an open-source software,namely,Berkeley Internet Name Domain(BIND),and evaluated in terms of performance,compatibility,and effectiveness.Evaluation results show that the proposed mechanism enables the resolver that only supports DNS/DNSSEC to authenticate the root zone TLD data effectively with minimal performance difference.展开更多
Using a differential form of the potential energy function and taking the effect of work applied by external force in far field into account, the mechanism of strike-slip fault earthquake is analyzed. The research ind...Using a differential form of the potential energy function and taking the effect of work applied by external force in far field into account, the mechanism of strike-slip fault earthquake is analyzed. The research indicates that each characteristic displayed with a fold catastrophe model in the catastrophe theory corresPonds to a specific primary characteristic of the strike-slip fault earthquake. The fold catastrophe can describe the positions of starting and end points of a fault failure and the distance of fault dislocation. These include the description of stability of the surrounding rock-fault system before and after the earthquake. Two different illustrations about elastic energy releasing amount of the surrounding rock with the fault failure are shown with the primary characteristics mutually demonstrated. The intensity of strike-slip fault earthquake is related to the surrounding rock press and the stiffness ratio of surrounding rock and fault. The larger the surrounding rock press, the smaller the stiffness ratio. The larger the included angle between the tangential stress axis and the causative fault surface, the stronger the earthquake.展开更多
The simulation of slope failures,including both failure initiation and development,has been modelled using the material point method（MPM）.Numerical case studies involving various slope angles,heterogeneity and rainf...The simulation of slope failures,including both failure initiation and development,has been modelled using the material point method（MPM）.Numerical case studies involving various slope angles,heterogeneity and rainfall infiltration are presented.It is demonstrated that,by utilising a constitutive model which encompasses,in a simplified manner,both pre-and post-failure behaviour,the material point method is able to simulate commonly observed failure modes.This is a step towards being able to better quantify slope failure consequence and risk.展开更多
Identity-based threshold signature(IDTS)is a forceful primitive to protect identity and data privacy,in which parties can collaboratively sign a given message as a signer without reconstructing a signing key.Neverthel...Identity-based threshold signature(IDTS)is a forceful primitive to protect identity and data privacy,in which parties can collaboratively sign a given message as a signer without reconstructing a signing key.Nevertheless,most IDTS schemes rely on a trusted key generation center(KGC).Recently,some IDTS schemes can achieve escrow-free security against corrupted KGC,but all of them are vulnerable to denial-of-service attacks in the dishonest majority setting,where cheaters may force the protocol to abort without providing any feedback.In this work,we present a fully decentralized IDTS scheme to resist corrupted KGC and denialof-service attacks.To this end,we design threshold protocols to achieve distributed key generation,private key extraction,and signing generation which can withstand the collusion between KGCs and signers,and then we propose an identification mechanism that can detect the identity of cheaters during key generation,private key extraction and signing generation.Finally,we formally prove that the proposed scheme is threshold unforgeability against chosen message attacks.The experimental results show that the computation time of both key generation and signing generation is<1 s,and private key extraction is about 3 s,which is practical in the distributed environment.展开更多
The aim of this paper is to propose a theoretical approach for performing the nonprobabilistic reliability analysis of structure.Due to a great deal of uncertainties and limited measured data in engineering practice,t...The aim of this paper is to propose a theoretical approach for performing the nonprobabilistic reliability analysis of structure.Due to a great deal of uncertainties and limited measured data in engineering practice,the structural uncertain parameters were described as interval variables.The theoretical analysis model was developed by starting from the 2-D plane and 3-D space.In order to avoid the loss of probable failure points,the 2-D plane and 3-D space were respectively divided into two parts and three parts for further analysis.The study pointed out that the probable failure points only existed among extreme points and root points of the limit state function.Furthermore,the low-dimensional analytical scheme was extended to the high-dimensional case.Using the proposed approach,it is easy to find the most probable failure point and to acquire the reliability index through simple comparison directly.A number of equations used for calculating the extreme points and root points were also evaluated.This result was useful to avoid the loss of probable failure points and meaningful for optimizing searches in the research field.Finally,two kinds of examples were presented and compared with the existing computation.The good agreements show that the proposed theoretical analysis approach in the paper is correct.The efforts were conducted to improve the optimization method,to indicate the search direction and path,and to avoid only searching the local optimal solution which would result in missed probable failure points.展开更多
基金supported by the National Natural Science Foundation of China(71771029)
文摘A engineering system is usually repairable, and failure process of a repairable by a failure point process. The power law model is a commonly used approach to model syst the em is often described failure point process. This paper introduces the concept and model for the failure process of repairable system. The method of parameter estimation is developed, and failure observations are fitted into a power-law model by using the least square method. Two applications of the pressent model are discussed according to the practical failure data of the central cooling system of a nuclear power plant. One application is determining the optimal overhaul time, and the other is evaluating the quality of maintenance. This paper provides references for the overhaul decision making and maintenance quality evaluation in reality.
基金This work is partially supported by the National Key Research and Development Program(2018YFB1800702).
文摘As a critical Internet infrastructure,domain name system(DNS)protects the authenticity and integrity of domain resource records with the introduction of security extensions(DNSSEC).DNSSEC builds a single-center and hierarchical resource authentication architecture,which brings management convenience but places the DNS at risk from a single point of failure.When the root key suffers a leak or misconfiguration,top level domain(TLD)authority cannot independently protect the authenticity of TLD data in the root zone.In this paper,we propose self-certificating root,a lightweight security enhancement mechanism of root zone compatible with DNS/DNSSEC protocol.By adding the TLD public key and signature of the glue records to the root zone,this mechanism enables the TLD authority to certify the self-submitted data in the root zone and protects the TLD authority from the risk of root key failure.This mechanism is implemented on an open-source software,namely,Berkeley Internet Name Domain(BIND),and evaluated in terms of performance,compatibility,and effectiveness.Evaluation results show that the proposed mechanism enables the resolver that only supports DNS/DNSSEC to authenticate the root zone TLD data effectively with minimal performance difference.
基金Project supported by the National Natural Science Foundation of China (No. 5067059)
文摘Using a differential form of the potential energy function and taking the effect of work applied by external force in far field into account, the mechanism of strike-slip fault earthquake is analyzed. The research indicates that each characteristic displayed with a fold catastrophe model in the catastrophe theory corresPonds to a specific primary characteristic of the strike-slip fault earthquake. The fold catastrophe can describe the positions of starting and end points of a fault failure and the distance of fault dislocation. These include the description of stability of the surrounding rock-fault system before and after the earthquake. Two different illustrations about elastic energy releasing amount of the surrounding rock with the fault failure are shown with the primary characteristics mutually demonstrated. The intensity of strike-slip fault earthquake is related to the surrounding rock press and the stiffness ratio of surrounding rock and fault. The larger the surrounding rock press, the smaller the stiffness ratio. The larger the included angle between the tangential stress axis and the causative fault surface, the stronger the earthquake.
基金supported by the Marie Curie Career Integration Grant(No.333177)the "100 Talents" programme of the Chinese Academy of Science+1 种基金the China Scholarship Councilthe Geo-Engineering Section of Delft University of Technology
文摘The simulation of slope failures,including both failure initiation and development,has been modelled using the material point method（MPM）.Numerical case studies involving various slope angles,heterogeneity and rainfall infiltration are presented.It is demonstrated that,by utilising a constitutive model which encompasses,in a simplified manner,both pre-and post-failure behaviour,the material point method is able to simulate commonly observed failure modes.This is a step towards being able to better quantify slope failure consequence and risk.
基金support by the National Key R&D Program of China(No.2021YFB3100400)the National Natural Science Foundation of China(Grant Nos.62172216,U20A201092)+6 种基金the Jiangsu Provincial Key Research and Development Program(Nos.BE2022068,BE2022068-2)the Key R&D Program of Guangdong Province(No.2020B0101090002)the Natural Science Foundation of Jiangsu Province(No.BK20211180)the Research Fund of Guangxi Key Laboratory of Trusted Software(No.KX202034)the Research Fund of State Key Laboratory of Integrated Services Networks(Xidian University)(No.ISN23-20)the Fund of Prospective Layout of Scientific Research for NUAA(Nanjing University of Aeronautics and Astronautics)JSPS Postdoctoral Fellowships(No.P21073).
文摘Identity-based threshold signature(IDTS)is a forceful primitive to protect identity and data privacy,in which parties can collaboratively sign a given message as a signer without reconstructing a signing key.Nevertheless,most IDTS schemes rely on a trusted key generation center(KGC).Recently,some IDTS schemes can achieve escrow-free security against corrupted KGC,but all of them are vulnerable to denial-of-service attacks in the dishonest majority setting,where cheaters may force the protocol to abort without providing any feedback.In this work,we present a fully decentralized IDTS scheme to resist corrupted KGC and denialof-service attacks.To this end,we design threshold protocols to achieve distributed key generation,private key extraction,and signing generation which can withstand the collusion between KGCs and signers,and then we propose an identification mechanism that can detect the identity of cheaters during key generation,private key extraction and signing generation.Finally,we formally prove that the proposed scheme is threshold unforgeability against chosen message attacks.The experimental results show that the computation time of both key generation and signing generation is<1 s,and private key extraction is about 3 s,which is practical in the distributed environment.
基金the National Natural Science Foundation of China (51408444, 51708428)
文摘The aim of this paper is to propose a theoretical approach for performing the nonprobabilistic reliability analysis of structure.Due to a great deal of uncertainties and limited measured data in engineering practice,the structural uncertain parameters were described as interval variables.The theoretical analysis model was developed by starting from the 2-D plane and 3-D space.In order to avoid the loss of probable failure points,the 2-D plane and 3-D space were respectively divided into two parts and three parts for further analysis.The study pointed out that the probable failure points only existed among extreme points and root points of the limit state function.Furthermore,the low-dimensional analytical scheme was extended to the high-dimensional case.Using the proposed approach,it is easy to find the most probable failure point and to acquire the reliability index through simple comparison directly.A number of equations used for calculating the extreme points and root points were also evaluated.This result was useful to avoid the loss of probable failure points and meaningful for optimizing searches in the research field.Finally,two kinds of examples were presented and compared with the existing computation.The good agreements show that the proposed theoretical analysis approach in the paper is correct.The efforts were conducted to improve the optimization method,to indicate the search direction and path,and to avoid only searching the local optimal solution which would result in missed probable failure points.
