Toxoplasma gondii is a single-celled parasite that infects nearly all warm-blooded animals,including humans(Montoya and Liesenfeld,2004).It occurs worldwide and can persist for a lifetime in mammals.Humans get infecte...Toxoplasma gondii is a single-celled parasite that infects nearly all warm-blooded animals,including humans(Montoya and Liesenfeld,2004).It occurs worldwide and can persist for a lifetime in mammals.Humans get infected by eating undercooked meat of animals containing the tissue cysts of this parasite.In immune-competent individuals,T.展开更多
This article presents a novel electrical/mechanical hybrid 4-redundancy brushless DC torque motor （BLDCM）, which has found applications in direct drive actuators （DDA） of aerial vehicles. This motor is characteris...This article presents a novel electrical/mechanical hybrid 4-redundancy brushless DC torque motor （BLDCM）, which has found applications in direct drive actuators （DDA） of aerial vehicles. This motor is characteristic of electrical/mechanical hybrid 4-redundancy by securing two stators along with two rotors on the same shaft. Each stator contains two sets of windings embed- ded in separated slots. Furthermore, compared to the scheme of two electrical dual-redundancy BLDCMs linked by a mechanical transmission, the proposed motor has lower volume and lighter weight, eliminates the nonlinearity caused by the gap of the me- chanical transmission, moderates the requirement for the torque balance between redundancies and reduces the cogging torque by shifting the magnets. Both magnetic circuit calculation and the finite element analysis （FEA） of the electromagnetic field are conducted to optimize the design process. A prototype motor has been produced and tested. The results indicate that its perform- ances comply with the requirements presented by designers. Moreover, the position frequency response of the prototype in the DDA＇s unloaded situation has also demonstrated the fulfillment of desired dynamic characteristics.展开更多
The hard support vector regression attracts little attention owing to the overfitting phenomenon. Recently, a fast offiine method has been proposed to approximately train the hard support vector regression with the ge...The hard support vector regression attracts little attention owing to the overfitting phenomenon. Recently, a fast offiine method has been proposed to approximately train the hard support vector regression with the generation performance comparable to the soft support vector regression. Based on this achievement, this article advances a fast online approximation called the hard sup- port vector regression （FOAHSVR for short）. By adopting the greedy stagewise and iterative strategies, it is capable of online estimating parameters of complicated systems. In order to verify the effectiveness of the FOAHSVR, an FOAHSVR-based analytical redundancy for aeroengines is developed. Experiments on the sensor failure and drift evidence the viability and feasibility of the analytical redundancy for aeroengines together with its base--FOAHSVR. In addition, the FOAHSVR is anticipated to find applications in other scientific-technical fields.展开更多
The redundancy technology for the aircraft multi-channel DC electrical power supply system is studied. In this system, the key loads can obtain power from seven sources. The direct current bus power control unit （DC ...The redundancy technology for the aircraft multi-channel DC electrical power supply system is studied. In this system, the key loads can obtain power from seven sources. The direct current bus power control unit （DC BPCU） is put forward to manage the power supply system automatically. The redundancy innovation is also applied in both hardware and software of DC BPCU. Furthermore, redundancy fault diagnosis is discussed through the existing parts. Experiments and applications show that the proposed aircraft DC power supply system possesses many advantages of high reliability, high automation and so on.展开更多
This paper investigates the reliability of internal marine combustion engines using an integrated approach that combines Fault Tree Analysis(FTA)and Bayesian Networks(BN).FTA provides a structured,top-down method for ...This paper investigates the reliability of internal marine combustion engines using an integrated approach that combines Fault Tree Analysis(FTA)and Bayesian Networks(BN).FTA provides a structured,top-down method for identifying critical failure modes and their root causes,while BN introduces flexibility in probabilistic reasoning,enabling dynamic updates based on new evidence.This dual methodology overcomes the limitations of static FTA models,offering a comprehensive framework for system reliability analysis.Critical failures,including External Leakage(ELU),Failure to Start(FTS),and Overheating(OHE),were identified as key risks.By incorporating redundancy into high-risk components such as pumps and batteries,the likelihood of these failures was significantly reduced.For instance,redundant pumps reduced the probability of ELU by 31.88%,while additional batteries decreased the occurrence of FTS by 36.45%.The results underscore the practical benefits of combining FTA and BN for enhancing system reliability,particularly in maritime applications where operational safety and efficiency are critical.This research provides valuable insights for maintenance planning and highlights the importance of redundancy in critical systems,especially as the industry transitions toward more autonomous vessels.展开更多
This paper concentrates on the problem of data redundancy under the extended-possibility-based model. Based on the information gain in data classification, a measure - relation redundancy - is proposed to evaluate the...This paper concentrates on the problem of data redundancy under the extended-possibility-based model. Based on the information gain in data classification, a measure - relation redundancy - is proposed to evaluate the degree of a given relation being redundant in whole. The properties of relation redundancy are also investigated. This new measure is useful in dealing with data redundancy.展开更多
针对命名数据网络(named data networking,NDN)中缓存冗余高、资源利用率低的问题,提出基于数据冗余包的协同缓存放置策略(cooperative cache placement strategy based on da-ta redundancy packet,CCPS-DRP)。该策略先对网络进行社区...针对命名数据网络(named data networking,NDN)中缓存冗余高、资源利用率低的问题,提出基于数据冗余包的协同缓存放置策略(cooperative cache placement strategy based on da-ta redundancy packet,CCPS-DRP)。该策略先对网络进行社区划分,再利用复杂网络中节点介数确定关键路由节点,将数据冗余包中的相同数据副本存放于其中,并动态管理冗余数据副本,实现关键节点集中管理与动态冗余清理的协同机制,以减少相同数据内容的重复缓存,使路由节点中的缓存容量得到充分利用,降低网络负载。实验结果表明,无论在均匀分布或高度偏斜分布的场景下,还是在严格资源限制或有较高资源的场景下,CCPS-DRP在缓存命中率和平均请求时延方面的性能均明显优于常见的随处缓存策略、概率缓存策略等,其通过协同缓存与冗余控制显著提升了网络性能。展开更多
Actuation system is a vital system in an aircraft, providing the force necessary to move flight control surfaces. The system has a significant influence on the overall aircraft performance and its safety. In order to ...Actuation system is a vital system in an aircraft, providing the force necessary to move flight control surfaces. The system has a significant influence on the overall aircraft performance and its safety. In order to further increase already high reliability and safety, Airbus has imple- mented a dissimilar redundancy actuation system （DRAS） in its aircraft. The DRAS consists of a hydraulic actuation system （HAS） and an electro-hydrostatic actuation system （EHAS）, in which the HAS utilizes a hydraulic source （HS） to move the control surface and the EHAS utilizes an elec- trical supply （ES） to provide the motion force. This paper focuses on the performance degradation processes and fault monitoring strategies of the DRAS, establishes its reliability model based on the generalized stochastic Petri nets （GSPN）, and carries out a reliability assessment considering the fault monitoring coverage rate and the false alarm rate. The results indicate that the proposed reli- ability model of the DRAS, considering the fault and redundancy degradation process and identify monitoring, can express its fault logical relation potential safety hazards.展开更多
Analytic redundancy-based fault diagnosis technique （ARFDT） is applied to onboard maintenance system （OMS）. The principle of the proposed ARFDT scheme is to design a redundancy configuration using ARFDT to enhance...Analytic redundancy-based fault diagnosis technique （ARFDT） is applied to onboard maintenance system （OMS）. The principle of the proposed ARFDT scheme is to design a redundancy configuration using ARFDT to enhance the functions of redundancy management and built in test equipment （BITE） monitor. Redundancy configuration for dual-redundancy and analytic redundancy is proposed, in which, the fault diagnosis includes detection and isolation. In order to keep the balance between rapid diagnosis and binary hypothesis, a filter together with an elapsed time limit is designed for sequential probability ratio test （SPRT） in the process of isolation. Diagnosis results would be submitted to central maintenance computer （CMC） together with BITE information. Moreover, by adopting reconstruction, the designed method not only provides analytic redundancy to help redundancy management, but also compensates the output when both of the sensors of the same type are faulty. Our scheme is applied to an aircraft’s sensors in a simulation experiment, and the results show that the proposed filter SPRT （FSPRT） saves at least 50% of isolation time than Wald SPRT （WSPRT）. Also, effectiveness, practicability and rapidity of the proposed scheme can be successfully achieved in OMS.展开更多
This study provides new insights into the comparison of cable-stayed and extradosed bridges based on the safety assessment of their stay cables.These bridges are often regarded as identical structures owing to the use...This study provides new insights into the comparison of cable-stayed and extradosed bridges based on the safety assessment of their stay cables.These bridges are often regarded as identical structures owing to the use of inclined cables;however,the international standards for bridge design stipulate different safety factors for stay cables of both types of bridges.To address this misconception,a comparative study was carried out on the safety factors of stay cables under fatigue and ultimate limit states by considering the effects of various untoward and damaging factors,such as overloading,cable loss,and corrosion.The primary goal of this study is to describe the structural disparities between both types of bridges and evaluate their structural redundancies by employing deterministic and nondeterministic methods.To achieve this goal,three-dimensional finite-element models of both bridges were developed based on the current design guidelines for stay cables in Japan.After the balanced states of the bridge models were achieved,static analyses were performed for different safety factors of stay cables in a parametric manner.Finally,the first-order reliability method and Monte Carlo method were applied to determine the reliability index of stay cables.The analysis results show that cable-stayed and extradosed bridges exhibit different structural redundancies for different safety factors under the same loading conditions.Moreover,a significant increase in structural redundancy occurs with an incremental increase in the safety factors of stay cables.展开更多
基金supported by the National Natural Sci ence Foundation of China(No.31672543)the Zhejiang Province“Sannongliufang”Science and Technology Coopera tion Project(No.2020SNLF007),China.
文摘Toxoplasma gondii is a single-celled parasite that infects nearly all warm-blooded animals,including humans(Montoya and Liesenfeld,2004).It occurs worldwide and can persist for a lifetime in mammals.Humans get infected by eating undercooked meat of animals containing the tissue cysts of this parasite.In immune-competent individuals,T.
基金New Century Program For Excellent Talents of Ministry of Education of China (NCET-04-0163)
文摘This article presents a novel electrical/mechanical hybrid 4-redundancy brushless DC torque motor （BLDCM）, which has found applications in direct drive actuators （DDA） of aerial vehicles. This motor is characteristic of electrical/mechanical hybrid 4-redundancy by securing two stators along with two rotors on the same shaft. Each stator contains two sets of windings embed- ded in separated slots. Furthermore, compared to the scheme of two electrical dual-redundancy BLDCMs linked by a mechanical transmission, the proposed motor has lower volume and lighter weight, eliminates the nonlinearity caused by the gap of the me- chanical transmission, moderates the requirement for the torque balance between redundancies and reduces the cogging torque by shifting the magnets. Both magnetic circuit calculation and the finite element analysis （FEA） of the electromagnetic field are conducted to optimize the design process. A prototype motor has been produced and tested. The results indicate that its perform- ances comply with the requirements presented by designers. Moreover, the position frequency response of the prototype in the DDA＇s unloaded situation has also demonstrated the fulfillment of desired dynamic characteristics.
基金National Natural Science Foundation of China (50576033)Aeronautical Science Foundation of China (04C52019)
文摘The hard support vector regression attracts little attention owing to the overfitting phenomenon. Recently, a fast offiine method has been proposed to approximately train the hard support vector regression with the generation performance comparable to the soft support vector regression. Based on this achievement, this article advances a fast online approximation called the hard sup- port vector regression （FOAHSVR for short）. By adopting the greedy stagewise and iterative strategies, it is capable of online estimating parameters of complicated systems. In order to verify the effectiveness of the FOAHSVR, an FOAHSVR-based analytical redundancy for aeroengines is developed. Experiments on the sensor failure and drift evidence the viability and feasibility of the analytical redundancy for aeroengines together with its base--FOAHSVR. In addition, the FOAHSVR is anticipated to find applications in other scientific-technical fields.
文摘The redundancy technology for the aircraft multi-channel DC electrical power supply system is studied. In this system, the key loads can obtain power from seven sources. The direct current bus power control unit （DC BPCU） is put forward to manage the power supply system automatically. The redundancy innovation is also applied in both hardware and software of DC BPCU. Furthermore, redundancy fault diagnosis is discussed through the existing parts. Experiments and applications show that the proposed aircraft DC power supply system possesses many advantages of high reliability, high automation and so on.
基金supported by Istanbul Technical University(Project No.45698)supported through the“Young Researchers’Career Development Project-training of doctoral students”of the Croatian Science Foundation.
文摘This paper investigates the reliability of internal marine combustion engines using an integrated approach that combines Fault Tree Analysis(FTA)and Bayesian Networks(BN).FTA provides a structured,top-down method for identifying critical failure modes and their root causes,while BN introduces flexibility in probabilistic reasoning,enabling dynamic updates based on new evidence.This dual methodology overcomes the limitations of static FTA models,offering a comprehensive framework for system reliability analysis.Critical failures,including External Leakage(ELU),Failure to Start(FTS),and Overheating(OHE),were identified as key risks.By incorporating redundancy into high-risk components such as pumps and batteries,the likelihood of these failures was significantly reduced.For instance,redundant pumps reduced the probability of ELU by 31.88%,while additional batteries decreased the occurrence of FTS by 36.45%.The results underscore the practical benefits of combining FTA and BN for enhancing system reliability,particularly in maritime applications where operational safety and efficiency are critical.This research provides valuable insights for maintenance planning and highlights the importance of redundancy in critical systems,especially as the industry transitions toward more autonomous vessels.
基金Supported by the National Natural Science Foundation of China(No.70231010/70321001)the Bilateral Scientific and Technological Cooperation between China and Flanders (No.174B0201)
文摘This paper concentrates on the problem of data redundancy under the extended-possibility-based model. Based on the information gain in data classification, a measure - relation redundancy - is proposed to evaluate the degree of a given relation being redundant in whole. The properties of relation redundancy are also investigated. This new measure is useful in dealing with data redundancy.
文摘针对命名数据网络(named data networking,NDN)中缓存冗余高、资源利用率低的问题,提出基于数据冗余包的协同缓存放置策略(cooperative cache placement strategy based on da-ta redundancy packet,CCPS-DRP)。该策略先对网络进行社区划分,再利用复杂网络中节点介数确定关键路由节点,将数据冗余包中的相同数据副本存放于其中,并动态管理冗余数据副本,实现关键节点集中管理与动态冗余清理的协同机制,以减少相同数据内容的重复缓存,使路由节点中的缓存容量得到充分利用,降低网络负载。实验结果表明,无论在均匀分布或高度偏斜分布的场景下,还是在严格资源限制或有较高资源的场景下,CCPS-DRP在缓存命中率和平均请求时延方面的性能均明显优于常见的随处缓存策略、概率缓存策略等,其通过协同缓存与冗余控制显著提升了网络性能。
基金supported by the National Basic Research and Development Program of China(No.2014CB046402)the National Natural Science Foundation of China(No.51175014)‘‘111" Program of China
文摘Actuation system is a vital system in an aircraft, providing the force necessary to move flight control surfaces. The system has a significant influence on the overall aircraft performance and its safety. In order to further increase already high reliability and safety, Airbus has imple- mented a dissimilar redundancy actuation system （DRAS） in its aircraft. The DRAS consists of a hydraulic actuation system （HAS） and an electro-hydrostatic actuation system （EHAS）, in which the HAS utilizes a hydraulic source （HS） to move the control surface and the EHAS utilizes an elec- trical supply （ES） to provide the motion force. This paper focuses on the performance degradation processes and fault monitoring strategies of the DRAS, establishes its reliability model based on the generalized stochastic Petri nets （GSPN）, and carries out a reliability assessment considering the fault monitoring coverage rate and the false alarm rate. The results indicate that the proposed reli- ability model of the DRAS, considering the fault and redundancy degradation process and identify monitoring, can express its fault logical relation potential safety hazards.
基金Aeronautical Science Foundation of China (20100753009)
文摘Analytic redundancy-based fault diagnosis technique （ARFDT） is applied to onboard maintenance system （OMS）. The principle of the proposed ARFDT scheme is to design a redundancy configuration using ARFDT to enhance the functions of redundancy management and built in test equipment （BITE） monitor. Redundancy configuration for dual-redundancy and analytic redundancy is proposed, in which, the fault diagnosis includes detection and isolation. In order to keep the balance between rapid diagnosis and binary hypothesis, a filter together with an elapsed time limit is designed for sequential probability ratio test （SPRT） in the process of isolation. Diagnosis results would be submitted to central maintenance computer （CMC） together with BITE information. Moreover, by adopting reconstruction, the designed method not only provides analytic redundancy to help redundancy management, but also compensates the output when both of the sensors of the same type are faulty. Our scheme is applied to an aircraft’s sensors in a simulation experiment, and the results show that the proposed filter SPRT （FSPRT） saves at least 50% of isolation time than Wald SPRT （WSPRT）. Also, effectiveness, practicability and rapidity of the proposed scheme can be successfully achieved in OMS.
文摘This study provides new insights into the comparison of cable-stayed and extradosed bridges based on the safety assessment of their stay cables.These bridges are often regarded as identical structures owing to the use of inclined cables;however,the international standards for bridge design stipulate different safety factors for stay cables of both types of bridges.To address this misconception,a comparative study was carried out on the safety factors of stay cables under fatigue and ultimate limit states by considering the effects of various untoward and damaging factors,such as overloading,cable loss,and corrosion.The primary goal of this study is to describe the structural disparities between both types of bridges and evaluate their structural redundancies by employing deterministic and nondeterministic methods.To achieve this goal,three-dimensional finite-element models of both bridges were developed based on the current design guidelines for stay cables in Japan.After the balanced states of the bridge models were achieved,static analyses were performed for different safety factors of stay cables in a parametric manner.Finally,the first-order reliability method and Monte Carlo method were applied to determine the reliability index of stay cables.The analysis results show that cable-stayed and extradosed bridges exhibit different structural redundancies for different safety factors under the same loading conditions.Moreover,a significant increase in structural redundancy occurs with an incremental increase in the safety factors of stay cables.
