Aiming at the characteristics of multi-stage and(extremely)small samples of the identification problem of key effectiveness indexes of weapon equipment system-of-systems(WESoS),a Bayesian intelligent identification an...Aiming at the characteristics of multi-stage and(extremely)small samples of the identification problem of key effectiveness indexes of weapon equipment system-of-systems(WESoS),a Bayesian intelligent identification and inference model for system effectiveness assessment indexes based on dynamic grey incidence is proposed.The method uses multi-layer Bayesian techniques,makes full use of historical statistics and empirical information,and determines the Bayesian estima-tion of the incidence degree of indexes,which effectively solves the difficulties of small sample size of effectiveness indexes and difficulty in obtaining incidence rules between indexes.Sec-ondly,The method quantifies the incidence relationship between evaluation indexes and combat effectiveness based on Bayesian posterior grey incidence,and then identifies key system effec-tiveness evaluation indexes.Finally,the proposed method is applied to a case of screening key effectiveness indexes of a missile defensive system,and the analysis results show that the proposed method can fuse multi-moment information and extract multi-stage key indexes,and has good data extraction capability in the case of small samples.展开更多
I firmly believe that of systems engineering is the requirement-driven force for the progress ofsoftware engineering, artificial intelligence and electronic technologies. The development ofsoftware engineering, artifi...I firmly believe that of systems engineering is the requirement-driven force for the progress ofsoftware engineering, artificial intelligence and electronic technologies. The development ofsoftware engineering, artificial intelligence and electronic technologies is the technical supportfor the progress of systems engineering. INTEGRATION can be considered as "bridging" the ex-isting technologies and the People together into a coordinated SYSTEM.展开更多
Recent studies have successfully demonstrated high-Tc superconductivity in bilayer nickelate La3Ni2O7.However,research on modulating the structural and transport characteristics of La3Ni2O7 films by applying“chemical...Recent studies have successfully demonstrated high-Tc superconductivity in bilayer nickelate La3Ni2O7.However,research on modulating the structural and transport characteristics of La3Ni2O7 films by applying“chemical”compressive pressure through cation substitution is still limited.Here,we address this issue in the La_(3−x)Nd_(x)Ni_(2)O_(7)(x=0,1.0,1.5,2.0,and 2.5)thin film samples.It was found that using Nd3+with a smaller radius instead of La3+can reduce the c-axis lattice constant and shift the metal-insulator transition(MIT)temperature TMIT.To probe the origin of the MIT at cryogenic temperatures,experimental measurements of magnetoresistance were conducted,and theoretical analysis was carried out using the Kondo model,Hikami-Larkin-Nagaoka equation,and other methods.The results indicate that as Nd doping rises,the contributions of the Kondo effect and two-dimensional weak localization(WL)first decrease and then increase.The total contribution of WL and the Kondo effect in the mid-doped La_(1.5)Nd_(1.5)Ni_(2)O_(7)sample was the smallest,which to some extent explains the changes in TMIT.The Kondo effect dominates in other La_(3−x)Nd_(x)Ni_(2)O_(7)(x=0,1.0,2.0,and 2.5)samples.This work demonstrates that cation doping has a significant impact on bilayer nickelates,providing experimental evidence for understanding the physical mechanism of the MIT in bilayer nickelates.展开更多
For constrained linear parameter varying(LPV)systems,this survey comprehensively reviews the literatures on output feedback robust model predictive control(OFRMPC)over the past two decades from the aspects on motivati...For constrained linear parameter varying(LPV)systems,this survey comprehensively reviews the literatures on output feedback robust model predictive control(OFRMPC)over the past two decades from the aspects on motivations,main contributions,and the related techniques.According to the types of state observer systems and scheduling parameters of LPV systems,different kinds of OFRMPC approaches are summarized and compared.The extensions of OFRMPC for LPV systems to other related uncertain systems are also investigated.The methods of dealing with system uncertainties and constraints in different kinds of OFRMPC optimizations are given.Key issues on OFRMPC optimizations for LPV systems are discussed.Furthermore,the future research directions on OFRMPC for LPV systems are suggested.展开更多
This paper aims at a type of image homing guided missile. The guided trajectory characteristics and the initial condition of the homing guidance are analyzed by calculating the miss distance of the image guided missil...This paper aims at a type of image homing guided missile. The guided trajectory characteristics and the initial condition of the homing guidance are analyzed by calculating the miss distance of the image guided missile. Several modified proportional navigation laws which are easy for engineering implementation are introduced.展开更多
Optical microscope,X-ray diffractometer,scanning electron microscope,tensile tester and dynamic mechanical analyzer(DMA) were applied to investigate the effects of Y and Zn additions on microstructure,mechanical prope...Optical microscope,X-ray diffractometer,scanning electron microscope,tensile tester and dynamic mechanical analyzer(DMA) were applied to investigate the effects of Y and Zn additions on microstructure,mechanical properties and damping capacity of Mg-3Cu-1Mn(CM31) alloy.The results show that with the increase of Y and Zn contents,the secondary dendrite arm spacing of alloys is reduced;meanwhile,the yield strength is increased.In low strain amplitude,the damping capacity of alloys with Y and Zn addition is lower than that of CM31 alloy.However,in strain amplitude over 5×10-3,the damping capacity of alloy with a trace of Y and Zn addition(1%Y and 2%Zn,mass fraction) increases abnormally with the increase of strain amplitude and is near to that of pure Mg,probably due to the increase of dislocation density caused by the precipitation of secondary phase.The temperature dependence of damping capacity of above alloy was also tested and discussed.展开更多
Microstructure and mechanical properties of electron beam post-weld aging treatment （PWAT） conditions. The results welded alloy J75 were studied under as-welded and showed that high-quality welds were produced by el...Microstructure and mechanical properties of electron beam post-weld aging treatment （PWAT） conditions. The results welded alloy J75 were studied under as-welded and showed that high-quality welds were produced by electron beam welding. Under as-welded condition, a fine dendritic structure consisting of gamma dendrite matrix and Laves phase was observed in the welds. Better mechanical properties were obtained in the weld zone than that of base metal because of the fine size of the dendritic structure. After PWAT, a discontinuous distribution of γ＇ particles existed in the dendritic structure. The presence of a γ＇ depletion zone in the dendrite core resulted in a significant degradation of mechanical properties of the weld.展开更多
The microstructure,mechanical properties and damping capacity of ZK60-xY(x=0,1.5%,2.5%,4.0%,mass fraction) magnesium alloys were investigated by using the optical microscope(OM),X-ray diffractometer(XRD),universal ten...The microstructure,mechanical properties and damping capacity of ZK60-xY(x=0,1.5%,2.5%,4.0%,mass fraction) magnesium alloys were investigated by using the optical microscope(OM),X-ray diffractometer(XRD),universal tensile testing machine and dynamic mechanical analyzer(DMA).The mechanisms for damping capacity of referred alloys were discussed by Granato-Lücke theory.The results show that Y additions remarkably reduce grain size(the average grain size is 21.6,13.0,8.6 and 4.0μm,respectively),and the tensile properties are enhanced with grain refining(the yield tensile strength increases to 292 MPa from 210 MPa and ultimate tensile strength increases to 330 MPa from 315 MPa).For the ZK60-xY(x=0,1.5%,4.0%)alloys,the damping capacity decreases with the increase of Y content.However,for the ZK60-xY(x=2.5%)alloy,the damping capacity improves abnormally,which is possibly related to the formation of Mg3Y2Zn3(W)FCC phase in this alloy.展开更多
For the system with the fuzzy failure state, the effects of the input random variables and the fuzzy failure state on the fuzzy probability of failure for the structural system are studied, and the moment-independence...For the system with the fuzzy failure state, the effects of the input random variables and the fuzzy failure state on the fuzzy probability of failure for the structural system are studied, and the moment-independence global sensitivity analysis（GSA） model is proposed to quantitatively measure these effects. According to the fuzzy random theory, the fuzzy failure state is transformed into an equivalent new random variable for the system, and the complementary function of the membership function of the fuzzy failure state is defined as the cumulative distribution function（CDF） of the new random variable. After introducing the new random variable, the equivalent performance function of the original problem is built. The difference between the unconditional fuzzy probability of failure and conditional fuzzy probability of failure is defined as the moment-independent GSA index. In order to solve the proposed GSA index efficiently, the Kriging-based algorithm is developed to estimate the defined moment-independence GSA index. Two engineering examples are employed to verify the feasibility and rationality of the presented GSA model, and the advantages of the developed Kriging method are also illustrated.展开更多
Hydrogen-induced modification in the deformation and fracture of a precipitation-hardened Fe-Ni based austenitic alloy has been investigated in the present study by means of thermal hydrogen charging experiment, tensi...Hydrogen-induced modification in the deformation and fracture of a precipitation-hardened Fe-Ni based austenitic alloy has been investigated in the present study by means of thermal hydrogen charging experiment, tensile tests, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. It is found that the γ＇ particles are subjected to the multiple shearing by dislocations during plastic deformation, which promotes the occurrence of the dislocation planar slip. Moreover, the alloy will be enhanced by hydrogen resulting in the formation of strain localization at macroscale. So, the mechanisms of deformation and fracture in the alloy have been proposed in terms of serious hydrogen-induced planar slip at microscale which can lead to macroscopic strain localization.展开更多
Current Web services architectures are confronted with a few stubborn problems, and the security problem becomes one of the bottlenecks that restrict the extensive application of Web service. After compared transport ...Current Web services architectures are confronted with a few stubborn problems, and the security problem becomes one of the bottlenecks that restrict the extensive application of Web service. After compared transport level with message level security, the limitation of transport level security became clearly. And then on the basis of the analysis message level security, especially WS-Security, XML security protocol was adopted to guarantee message level security. Because WS-Security is a new protocol jointly developed by Microsoft and IBM among these XML security protocols, and a security-token mechanism of WS-Security mechanism was improved, added a table with security-token types. And a new model consisting of multiple security-token is put forward to guarantee the security of message transmission.展开更多
Based on Bayesian network, a new method to diagnose satellite faults is presented. The Bayesian network model of physical processing of satellite is developed; the main ideas of Bayesian network model of satellite fau...Based on Bayesian network, a new method to diagnose satellite faults is presented. The Bayesian network model of physical processing of satellite is developed; the main ideas of Bayesian network model of satellite fault diagnosis are introduced; the method to make the symptom variables values into discrete forms is proposed; one example is given to illustrate the application of Bayesian network model for satellite fault diagnosis.展开更多
A problem of the air pollution control in China is getting to know a regional contribution rate of internal and external source of PM2.5. In this paper,Set Pair Analysis（ SPA） method is proposed to calculate the con...A problem of the air pollution control in China is getting to know a regional contribution rate of internal and external source of PM2.5. In this paper,Set Pair Analysis（ SPA） method is proposed to calculate the contribution rate of PM2.5in Dongguan City. Due to geographic,meteorological factors and the low concentration of air pollutants in Qingxi area,the PM2.5in this place is mainly contributed by the regional transport of air pollutants from other inside areas of Dongguan,and less affected by the outside of Dongguan. So the concentration of PM2.5in Qingxi area can reflect the Dongguan＇s basic background concentration of PM2.5. On the basis of the basic background concentration,firstly the concentration of each pollutant components is divided into the internal part and the mixed part. Secondly using the source apportionment samples of five monitoring sites in Dongguan we can respectively construct a sample set A and an evaluation set B. Thirdly the SPA is operated onto the mixed part in terms of set B.At last the connection degree between the concentration of each pollutant components and external source and internal source will be calculated,that is the contribution rate. The research reveals that the contribution rate of internal source and external source of PM2.5in Dongguan City is 83%and 17% respectively,which roughly met expectations. This method is simple and effective and it can provide a reference for the government taking reduction measures to control PM2.5pollutants emission.展开更多
Failure of a stored system can only be detected after inspection and its reliability can be resumed by replacement of failed components. A maintenance policy of combining periodic inspection and preventive replacement...Failure of a stored system can only be detected after inspection and its reliability can be resumed by replacement of failed components. A maintenance policy of combining periodic inspection and preventive replacement is proposed to improve its availability. To coordinate component replacement and spare provision,an ordering policy of (0,1) is considered jointly. Thus,the joint maintenance policy contains inspection,replacement and spare provision. A programming model based on the joint maintenance policy is established,whose objective function is average expected cost,containing maintenance cost and inventory cost,and the constraint is system availability. Applying renewal theorem,the performance indexes are deduced under the condition that the stored system obeys the common life distribution. Numerical examples are given for a stored system with two different units,where unit 1 probability degrades with time and unit 2 probability degrades at each test. The effect of reliability parameters on the policies is discussed. The results indicate that the joint policy is very close to the independent policy.展开更多
Software testing is a very important phase of the software development process. It is a very difficult job for a software manager to allocate optimally the financial budget to a software project during testing. In thi...Software testing is a very important phase of the software development process. It is a very difficult job for a software manager to allocate optimally the financial budget to a software project during testing. In this paper the problem of optimal allocation of the software testing cost is studied. There exist several models focused on the development of software costs measuring the number of software errors remaining in the software during testing. The purpose of this paper is to use these models to formulate the optimization problems of resource allocation: Minimization of the total number of software errors remaining in the system. On the assumption that a software project consists of some independent modules, the presented approach extends previous work by defining new goal functions and extending the primary assumption and precondition.展开更多
We investigate the factors that affect synchronizability of coupled oscillators on scale-free networks. Using the memory Tabu search （MTS） algorithm, we improve the eigen-ratio Q of a coupling matrix by edge intercr...We investigate the factors that affect synchronizability of coupled oscillators on scale-free networks. Using the memory Tabu search （MTS） algorithm, we improve the eigen-ratio Q of a coupling matrix by edge intercrossing. The numerical results show that the synchronizatlon-improved scale-free networks should have distinctive both small average distance and larger clustering coefficient, which are consistent with some real-world networks. Moreover, the synchronizability-improved networks demonstrate the disassortative coefficient.展开更多
The deformation and failure mechanism of cylindrical shells and square plate with pre-formed holes under blast loading were investigated numerically by employing the Ansys 17.0 and Ls-Dyna 971.To calibrate the numeric...The deformation and failure mechanism of cylindrical shells and square plate with pre-formed holes under blast loading were investigated numerically by employing the Ansys 17.0 and Ls-Dyna 971.To calibrate the numerical model,the experiments of square plates with pre-formed circle holes were modeled and the numerical results have a good agreement with the experiment data.The calibrated numerical model was used to study the deformation and failure mechanism of cylindrical shells with pre-formed circle holes subjected to blast loading.The structure response and stress field changing process has been divided into four specific stages and the deformation mechanism has been discussed systematically.The local and global deformation curves,degree of damage,change of stress status and failure modes of cylindrical shell and square plate with pre-formed circular holes are obtained,compared and analyzed,it can be concluded as:(1)The transition of tensile stress fields is due to the geometrical characteristic of pre-formed holes and cylindrical shell with arch configuration;(2)The existence of preformed holes not only lead to the increasing of stress concentration around the holes,but also release the stress concentration during whole response process;(3)There are three and two kinds of failure modes for square plate and cylindrical shell with pre-formed holes,respectively.and the standoff distance has a key influence on the forming location of the crack initiating point and the locus of crack propagation;(4)The square plate with pre-formed holes has a better performance than cylindrical shell on blast-resistant capability at a smaller standoff distance,while the influence of pre-formed holes on the reduction of blast-resistant capability of square plate is bigger than that of cylindrical shell.展开更多
The uncertainty widely exists in the engineering practice.Therefore,it is necessary to research the effect of uncertainty on the structural system. In this paper,the reliability and sensitivity of the flexure hinge, w...The uncertainty widely exists in the engineering practice.Therefore,it is necessary to research the effect of uncertainty on the structural system. In this paper,the reliability and sensitivity of the flexure hinge, which is the key component of the compliant mechanisms,are investigated. The results of the reliability analysis can effectively guide the engineer to design and optimize the flexure hinge. In order to improve the calculating efficiency,the kriging method is introduced to estimate the failure probability and reliability sensitivity.展开更多
Due to bad working conditions and complicated structure,kinds of complicated cycle loads work on turbine disc, and it's difficult to determine the stress distribution of their equivalent load.Based on the traditio...Due to bad working conditions and complicated structure,kinds of complicated cycle loads work on turbine disc, and it's difficult to determine the stress distribution of their equivalent load.Based on the traditional stress-strength interference model and conditional reliability,the reliability models of turbine disc without the stress distribution are established in this paper. In the range of fatigue limit, by improving fatigue life curve, the relationship between turbine disc's life probability distribution and material GH4133B's is got,and so is the relationship between life and stress.Then,on the basis of test data of smooth material test-piece from references,the fatigue life probability distribution of material testpiece is found out,and then the fatigue life probability distribution of turbine disc is confirmed. The fatigue life probability distribution of turbine disc is taken into reliability model and the reliability of turbine is analyzed disc under random loads. And this analysis result confirms the variation trend of engine's reliability.展开更多
基金supported by the National Natural Science Foundation of China(72271124,72071111).
文摘Aiming at the characteristics of multi-stage and(extremely)small samples of the identification problem of key effectiveness indexes of weapon equipment system-of-systems(WESoS),a Bayesian intelligent identification and inference model for system effectiveness assessment indexes based on dynamic grey incidence is proposed.The method uses multi-layer Bayesian techniques,makes full use of historical statistics and empirical information,and determines the Bayesian estima-tion of the incidence degree of indexes,which effectively solves the difficulties of small sample size of effectiveness indexes and difficulty in obtaining incidence rules between indexes.Sec-ondly,The method quantifies the incidence relationship between evaluation indexes and combat effectiveness based on Bayesian posterior grey incidence,and then identifies key system effec-tiveness evaluation indexes.Finally,the proposed method is applied to a case of screening key effectiveness indexes of a missile defensive system,and the analysis results show that the proposed method can fuse multi-moment information and extract multi-stage key indexes,and has good data extraction capability in the case of small samples.
文摘I firmly believe that of systems engineering is the requirement-driven force for the progress ofsoftware engineering, artificial intelligence and electronic technologies. The development ofsoftware engineering, artificial intelligence and electronic technologies is the technical supportfor the progress of systems engineering. INTEGRATION can be considered as "bridging" the ex-isting technologies and the People together into a coordinated SYSTEM.
基金supported by the Natural Science Foundation of Guangdong Province of China(Grant No.2025A1515011071)the National Natural Science Foundation of China(Grant Nos.92065110,11974048,and 12074334)the Beijing Municipal Natural Science Foundation Key Research Topics(Grant No.Z230006)。
文摘Recent studies have successfully demonstrated high-Tc superconductivity in bilayer nickelate La3Ni2O7.However,research on modulating the structural and transport characteristics of La3Ni2O7 films by applying“chemical”compressive pressure through cation substitution is still limited.Here,we address this issue in the La_(3−x)Nd_(x)Ni_(2)O_(7)(x=0,1.0,1.5,2.0,and 2.5)thin film samples.It was found that using Nd3+with a smaller radius instead of La3+can reduce the c-axis lattice constant and shift the metal-insulator transition(MIT)temperature TMIT.To probe the origin of the MIT at cryogenic temperatures,experimental measurements of magnetoresistance were conducted,and theoretical analysis was carried out using the Kondo model,Hikami-Larkin-Nagaoka equation,and other methods.The results indicate that as Nd doping rises,the contributions of the Kondo effect and two-dimensional weak localization(WL)first decrease and then increase.The total contribution of WL and the Kondo effect in the mid-doped La_(1.5)Nd_(1.5)Ni_(2)O_(7)sample was the smallest,which to some extent explains the changes in TMIT.The Kondo effect dominates in other La_(3−x)Nd_(x)Ni_(2)O_(7)(x=0,1.0,2.0,and 2.5)samples.This work demonstrates that cation doping has a significant impact on bilayer nickelates,providing experimental evidence for understanding the physical mechanism of the MIT in bilayer nickelates.
基金Supported by the Natural Science Foundation of Hunan Province （07JJ6112）, the Construct Program of the Key Discipline in Hunan Province （control theory and control engineering）, and Scientific Research Fund of Hunan Provincial Education Department （04A012, 07A015）
基金supported in part by the National Natural Science Foundation of China(62103319,62073053,61773396)。
文摘For constrained linear parameter varying(LPV)systems,this survey comprehensively reviews the literatures on output feedback robust model predictive control(OFRMPC)over the past two decades from the aspects on motivations,main contributions,and the related techniques.According to the types of state observer systems and scheduling parameters of LPV systems,different kinds of OFRMPC approaches are summarized and compared.The extensions of OFRMPC for LPV systems to other related uncertain systems are also investigated.The methods of dealing with system uncertainties and constraints in different kinds of OFRMPC optimizations are given.Key issues on OFRMPC optimizations for LPV systems are discussed.Furthermore,the future research directions on OFRMPC for LPV systems are suggested.
文摘This paper aims at a type of image homing guided missile. The guided trajectory characteristics and the initial condition of the homing guidance are analyzed by calculating the miss distance of the image guided missile. Several modified proportional navigation laws which are easy for engineering implementation are introduced.
基金Project(10876045) supported by the National Natural Science Foundation of China and China Academy of Engineering PhysicsProject(2007CB613704) supported by the National Basic Research Program of ChinaProject(CSTS2008AB4114) supported by Chongqing Science and Technology Commission,China
文摘Optical microscope,X-ray diffractometer,scanning electron microscope,tensile tester and dynamic mechanical analyzer(DMA) were applied to investigate the effects of Y and Zn additions on microstructure,mechanical properties and damping capacity of Mg-3Cu-1Mn(CM31) alloy.The results show that with the increase of Y and Zn contents,the secondary dendrite arm spacing of alloys is reduced;meanwhile,the yield strength is increased.In low strain amplitude,the damping capacity of alloys with Y and Zn addition is lower than that of CM31 alloy.However,in strain amplitude over 5×10-3,the damping capacity of alloy with a trace of Y and Zn addition(1%Y and 2%Zn,mass fraction) increases abnormally with the increase of strain amplitude and is near to that of pure Mg,probably due to the increase of dislocation density caused by the precipitation of secondary phase.The temperature dependence of damping capacity of above alloy was also tested and discussed.
基金supported by the National Natural Science Foundation of China and China Academy of Engineering Physics(Project No.U1230118)
文摘Microstructure and mechanical properties of electron beam post-weld aging treatment （PWAT） conditions. The results welded alloy J75 were studied under as-welded and showed that high-quality welds were produced by electron beam welding. Under as-welded condition, a fine dendritic structure consisting of gamma dendrite matrix and Laves phase was observed in the welds. Better mechanical properties were obtained in the weld zone than that of base metal because of the fine size of the dendritic structure. After PWAT, a discontinuous distribution of γ＇ particles existed in the dendritic structure. The presence of a γ＇ depletion zone in the dendrite core resulted in a significant degradation of mechanical properties of the weld.
基金Project(10876045)supported by the National Natural Science Foundation Commission of China and China Academy of Engineering PhysicsProject(50725413)supported by the National Natural Science Foundation of China+1 种基金Project(2007CB613704)supported by the National Basic Research Program of ChinaProject(CSTS2008AB4114)supported by Chongqing Science and Technology Commission(CQ CSTC)
文摘The microstructure,mechanical properties and damping capacity of ZK60-xY(x=0,1.5%,2.5%,4.0%,mass fraction) magnesium alloys were investigated by using the optical microscope(OM),X-ray diffractometer(XRD),universal tensile testing machine and dynamic mechanical analyzer(DMA).The mechanisms for damping capacity of referred alloys were discussed by Granato-Lücke theory.The results show that Y additions remarkably reduce grain size(the average grain size is 21.6,13.0,8.6 and 4.0μm,respectively),and the tensile properties are enhanced with grain refining(the yield tensile strength increases to 292 MPa from 210 MPa and ultimate tensile strength increases to 330 MPa from 315 MPa).For the ZK60-xY(x=0,1.5%,4.0%)alloys,the damping capacity decreases with the increase of Y content.However,for the ZK60-xY(x=2.5%)alloy,the damping capacity improves abnormally,which is possibly related to the formation of Mg3Y2Zn3(W)FCC phase in this alloy.
基金supported by the National Natural Science Foundation of China(11702281)the Science Challenge Project(TZ2018007)the Technology Foundation Project of State Administration of Science,Technology and Industry for National Defence,PRC(JSZL2017212A001)
文摘For the system with the fuzzy failure state, the effects of the input random variables and the fuzzy failure state on the fuzzy probability of failure for the structural system are studied, and the moment-independence global sensitivity analysis（GSA） model is proposed to quantitatively measure these effects. According to the fuzzy random theory, the fuzzy failure state is transformed into an equivalent new random variable for the system, and the complementary function of the membership function of the fuzzy failure state is defined as the cumulative distribution function（CDF） of the new random variable. After introducing the new random variable, the equivalent performance function of the original problem is built. The difference between the unconditional fuzzy probability of failure and conditional fuzzy probability of failure is defined as the moment-independent GSA index. In order to solve the proposed GSA index efficiently, the Kriging-based algorithm is developed to estimate the defined moment-independence GSA index. Two engineering examples are employed to verify the feasibility and rationality of the presented GSA model, and the advantages of the developed Kriging method are also illustrated.
基金the National Natural Science Foundation of China and China Academy of Engineering Physics (NSAF) under grant No.U1230118the National Natural Science Foundation of China (NSFC) under grant No.51171178
文摘Hydrogen-induced modification in the deformation and fracture of a precipitation-hardened Fe-Ni based austenitic alloy has been investigated in the present study by means of thermal hydrogen charging experiment, tensile tests, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. It is found that the γ＇ particles are subjected to the multiple shearing by dislocations during plastic deformation, which promotes the occurrence of the dislocation planar slip. Moreover, the alloy will be enhanced by hydrogen resulting in the formation of strain localization at macroscale. So, the mechanisms of deformation and fracture in the alloy have been proposed in terms of serious hydrogen-induced planar slip at microscale which can lead to macroscopic strain localization.
基金Supported by the National Natural Science Foundation of China (70571056) and the High Technology Research and Development Pro-gram of Hebei Province (04213534, 04213529)
文摘Current Web services architectures are confronted with a few stubborn problems, and the security problem becomes one of the bottlenecks that restrict the extensive application of Web service. After compared transport level with message level security, the limitation of transport level security became clearly. And then on the basis of the analysis message level security, especially WS-Security, XML security protocol was adopted to guarantee message level security. Because WS-Security is a new protocol jointly developed by Microsoft and IBM among these XML security protocols, and a security-token mechanism of WS-Security mechanism was improved, added a table with security-token types. And a new model consisting of multiple security-token is put forward to guarantee the security of message transmission.
文摘Based on Bayesian network, a new method to diagnose satellite faults is presented. The Bayesian network model of physical processing of satellite is developed; the main ideas of Bayesian network model of satellite fault diagnosis are introduced; the method to make the symptom variables values into discrete forms is proposed; one example is given to illustrate the application of Bayesian network model for satellite fault diagnosis.
基金Supported by National Natural Science Foundation of China(71171089)Research for PM_(2.5) Contamination Characteristics and Prevention and Control Countermeasures in Dongguan City(Dongcaidan[2013]222)
文摘A problem of the air pollution control in China is getting to know a regional contribution rate of internal and external source of PM2.5. In this paper,Set Pair Analysis（ SPA） method is proposed to calculate the contribution rate of PM2.5in Dongguan City. Due to geographic,meteorological factors and the low concentration of air pollutants in Qingxi area,the PM2.5in this place is mainly contributed by the regional transport of air pollutants from other inside areas of Dongguan,and less affected by the outside of Dongguan. So the concentration of PM2.5in Qingxi area can reflect the Dongguan＇s basic background concentration of PM2.5. On the basis of the basic background concentration,firstly the concentration of each pollutant components is divided into the internal part and the mixed part. Secondly using the source apportionment samples of five monitoring sites in Dongguan we can respectively construct a sample set A and an evaluation set B. Thirdly the SPA is operated onto the mixed part in terms of set B.At last the connection degree between the concentration of each pollutant components and external source and internal source will be calculated,that is the contribution rate. The research reveals that the contribution rate of internal source and external source of PM2.5in Dongguan City is 83%and 17% respectively,which roughly met expectations. This method is simple and effective and it can provide a reference for the government taking reduction measures to control PM2.5pollutants emission.
基金Sponsored by the National Nature Science Foundation of China (60674085)
文摘Failure of a stored system can only be detected after inspection and its reliability can be resumed by replacement of failed components. A maintenance policy of combining periodic inspection and preventive replacement is proposed to improve its availability. To coordinate component replacement and spare provision,an ordering policy of (0,1) is considered jointly. Thus,the joint maintenance policy contains inspection,replacement and spare provision. A programming model based on the joint maintenance policy is established,whose objective function is average expected cost,containing maintenance cost and inventory cost,and the constraint is system availability. Applying renewal theorem,the performance indexes are deduced under the condition that the stored system obeys the common life distribution. Numerical examples are given for a stored system with two different units,where unit 1 probability degrades with time and unit 2 probability degrades at each test. The effect of reliability parameters on the policies is discussed. The results indicate that the joint policy is very close to the independent policy.
文摘Software testing is a very important phase of the software development process. It is a very difficult job for a software manager to allocate optimally the financial budget to a software project during testing. In this paper the problem of optimal allocation of the software testing cost is studied. There exist several models focused on the development of software costs measuring the number of software errors remaining in the software during testing. The purpose of this paper is to use these models to formulate the optimization problems of resource allocation: Minimization of the total number of software errors remaining in the system. On the assumption that a software project consists of some independent modules, the presented approach extends previous work by defining new goal functions and extending the primary assumption and precondition.
基金Supported by the Natural Science Foundation of China under Grant Nos 70431001 and 70271046, the ASIA：NZ Foundation Higher Education Exchange Program （2005）, Massey University Research Fund （2005）, and Massey University International Visitor Research Fund （2007）.
文摘We investigate the factors that affect synchronizability of coupled oscillators on scale-free networks. Using the memory Tabu search （MTS） algorithm, we improve the eigen-ratio Q of a coupling matrix by edge intercrossing. The numerical results show that the synchronizatlon-improved scale-free networks should have distinctive both small average distance and larger clustering coefficient, which are consistent with some real-world networks. Moreover, the synchronizability-improved networks demonstrate the disassortative coefficient.
基金The reported research is financially supported by The National Natural Science Foundation of China under Grant No.11902310 and No.11802292.
文摘The deformation and failure mechanism of cylindrical shells and square plate with pre-formed holes under blast loading were investigated numerically by employing the Ansys 17.0 and Ls-Dyna 971.To calibrate the numerical model,the experiments of square plates with pre-formed circle holes were modeled and the numerical results have a good agreement with the experiment data.The calibrated numerical model was used to study the deformation and failure mechanism of cylindrical shells with pre-formed circle holes subjected to blast loading.The structure response and stress field changing process has been divided into four specific stages and the deformation mechanism has been discussed systematically.The local and global deformation curves,degree of damage,change of stress status and failure modes of cylindrical shell and square plate with pre-formed circular holes are obtained,compared and analyzed,it can be concluded as:(1)The transition of tensile stress fields is due to the geometrical characteristic of pre-formed holes and cylindrical shell with arch configuration;(2)The existence of preformed holes not only lead to the increasing of stress concentration around the holes,but also release the stress concentration during whole response process;(3)There are three and two kinds of failure modes for square plate and cylindrical shell with pre-formed holes,respectively.and the standoff distance has a key influence on the forming location of the crack initiating point and the locus of crack propagation;(4)The square plate with pre-formed holes has a better performance than cylindrical shell on blast-resistant capability at a smaller standoff distance,while the influence of pre-formed holes on the reduction of blast-resistant capability of square plate is bigger than that of cylindrical shell.
基金Foundations of China Academic Engineering Physics(CAEP)(Nos.2013B0203028,2014B0203023)Technology Foundation Project,China(No.2015ZK1.1)
文摘The uncertainty widely exists in the engineering practice.Therefore,it is necessary to research the effect of uncertainty on the structural system. In this paper,the reliability and sensitivity of the flexure hinge, which is the key component of the compliant mechanisms,are investigated. The results of the reliability analysis can effectively guide the engineer to design and optimize the flexure hinge. In order to improve the calculating efficiency,the kriging method is introduced to estimate the failure probability and reliability sensitivity.
基金Foundation of China Academic Engineering Physics(No.2013B0203028)
文摘Due to bad working conditions and complicated structure,kinds of complicated cycle loads work on turbine disc, and it's difficult to determine the stress distribution of their equivalent load.Based on the traditional stress-strength interference model and conditional reliability,the reliability models of turbine disc without the stress distribution are established in this paper. In the range of fatigue limit, by improving fatigue life curve, the relationship between turbine disc's life probability distribution and material GH4133B's is got,and so is the relationship between life and stress.Then,on the basis of test data of smooth material test-piece from references,the fatigue life probability distribution of material testpiece is found out,and then the fatigue life probability distribution of turbine disc is confirmed. The fatigue life probability distribution of turbine disc is taken into reliability model and the reliability of turbine is analyzed disc under random loads. And this analysis result confirms the variation trend of engine's reliability.
