The Long March 2 F(LM-2F) launch vehicle, the only launch vehicle designed for manned space flight in China, successfully launched the Tiangong 2 space laboratory and the Shenzhou 11 manned spaceship into orbits in 20...The Long March 2 F(LM-2F) launch vehicle, the only launch vehicle designed for manned space flight in China, successfully launched the Tiangong 2 space laboratory and the Shenzhou 11 manned spaceship into orbits in 2016 respectively. In this study, it introduces the technological improvements for enhancing the reliability of the LM-2F launch vehicle in the aspects of general technology, control system, manufacture and ground support system. The LM-2F launch vehicle will continue to provide more contributions to the Chinese Space Station Project with its high reliability and 100% success rate.展开更多
Stress-strength model is a basic and important tool for reliability analysis.There are few methods to assess the confidence limit of interference reliability when the distribution parameters of stress and strength are...Stress-strength model is a basic and important tool for reliability analysis.There are few methods to assess the confidence limit of interference reliability when the distribution parameters of stress and strength are all unknown.A new assessment method of interference reliability is proposed and the estimates of the distribution parameters are accordingly given.The lower confidence limit of interference reliability with given confidence can be obtained with the method even though the parameters are all unknown.Simulation studies and an engineering application are conducted to validate the method,which suggest that the method provides precise estimates even for sample size of approximately.展开更多
The rapid development of Internet of Things(IoT)technology has made previously unavailable data available,and applications can take advantage of device data for people to visualize,explore,and build complex analyses.A...The rapid development of Internet of Things(IoT)technology has made previously unavailable data available,and applications can take advantage of device data for people to visualize,explore,and build complex analyses.As the size of the network and the number of network users continue to increase,network requests tend to aggregate on a small number of network resources,which results in uneven load on network requests.Real-time,highly reliable network file distribution technology is of great importance in the Internet of Things.This paper studies real-time and highly reliable file distribution technology for large-scale networks.In response to this topic,this paper studies the current file distribution technology,proposes a file distribution model,and proposes a corresponding load balancing method based on the file distribution model.Experiments show that the system has achieved real-time and high reliability of network transmission.展开更多
The worldwide space industry has entered a new space economy era.The question is how to develop in this new era?This paper tries to answer this question from two aspects:highly reliable and low-cost technology for acc...The worldwide space industry has entered a new space economy era.The question is how to develop in this new era?This paper tries to answer this question from two aspects:highly reliable and low-cost technology for access to space,and the cislunar economic zone.Firstly,the development requirement of the future space transportation system is discussed and the development path to enable high-reliability and a low cost of space transportation system is analyzed.Moreover,the concept of a routine space transportation system is proposed,upon which this paper gives some thoughts to the development of the cislunar economic zone thus embracing the new space economy era.展开更多
As China’s only manned launch vehicle,the LM-2 F Launch vehicle successfully launched the Shenzhou 12 manned spacecraft into its predetermined orbit on June 12,2021,signifying the successful completion of the first m...As China’s only manned launch vehicle,the LM-2 F Launch vehicle successfully launched the Shenzhou 12 manned spacecraft into its predetermined orbit on June 12,2021,signifying the successful completion of the first manned launch mission in the construction and key technology test stage of China Space Station(CSS).From the launch of the Shenzhou 11 manned spacecraft on October 12,2016 to the launch of Shenzhou 12 in 2021,over the past five years,the LM-2 F launch vehicle has been continuously improved in terms of product reliability through technological innovation and design improvement,and its flight reliability index has increased from 0.97 to 0.98.Based on the new launch mission requirements for the construction stage of CSS,this paper introduces the technological innovation and reliability improvement methods of the LM-2 F from the aspects of design improvement,research methods and process optimization.The LM-2 F launch vehicle will make greater contributions in supporting the construction of CSS with higher reliability and perfect launch success rate.展开更多
Accelerated destructive degradation tests(ADDTs)are powerful to provide reliability information in the degradation processes with destructive measurements.In order to carry out an ADDT efficiently,both the estimation ...Accelerated destructive degradation tests(ADDTs)are powerful to provide reliability information in the degradation processes with destructive measurements.In order to carry out an ADDT efficiently,both the estimation precision of parameters and the test cost should be considered.On the basis of the given degradation model and failure criterion,a multiple-objective optimization model for the design of ADDTs is proposed.Under constrains of the maximum measurement time,the total sample size and the number of stress levels,a comprehensive target function is suggested to reflect both the precision of lifetime estimation and total cost,and the optimal test plan is obtained,which is composed by optimal choices for samples size,measurement frequency,and the number of measurements at each stress level.A real example is illustrated to demonstrate the implementation of the proposed approach.展开更多
In distributed storage systems,replication and erasure code(EC)are common methods for data redundancy.Compared with replication,EC has better storage efficiency,but suffers higher overhead in update.Moreover,consisten...In distributed storage systems,replication and erasure code(EC)are common methods for data redundancy.Compared with replication,EC has better storage efficiency,but suffers higher overhead in update.Moreover,consistency and reliability problems caused by concurrent updates bring new challenges to applications of EC.Many works focus on optimizing the EC solution,including algorithm optimization,novel data update method,and so on,but lack the solutions for consistency and reliability problems.In this paper,we introduce a storage system that decouples data updating and EC encoding,namely,decoupled data updating and coding(DDUC),and propose a data placement policy that combines replication and parity blocks.For the(N,M)EC system,the data are placed as N groups of M+1 replicas,and redundant data blocks of the same stripe are placed in the parity nodes,so that the parity nodes can autonomously perform local EC encoding.Based on the above policy,a two-phase data update method is implemented in which data are updated in replica mode in phase 1,and the EC encoding is done independently by parity nodes in phase 2.This solves the problem of data reliability degradation caused by concurrent updates while ensuring high concurrency performance.It also uses persistent memory(PMem)hardware features of the byte addressing and eight-byte atomic write to implement a lightweight logging mechanism that improves performance while ensuring data consistency.Experimental results show that the concurrent access performance of the proposed storage system is 1.70–3.73 times that of the state-of-the-art storage system Ceph,and the latency is only 3.4%–5.9%that of Ceph.展开更多
In this paper,a fault-tolerance wide voltage conversion gain DC/DC converter for More Electric Aircraft(MEA)is proposed.The proposed converter consists of a basic Cuk converter module and n expandable units.By adjusti...In this paper,a fault-tolerance wide voltage conversion gain DC/DC converter for More Electric Aircraft(MEA)is proposed.The proposed converter consists of a basic Cuk converter module and n expandable units.By adjusting the operation state of the expandable units,the voltage conversion gain of the proposed converter could be regulated,which makes it available for wide voltage conversion applications.Especially,since mutual redundancy can be realized between the basic Cuk converter module and the expandable units,the converter can continuously work when an unpredictable fault occurs to the fault-tolerant parts of the proposed converter,which reflects the fault tolerance of the converter and significantly improves the reliability of the system.Moreover,the advantages of small input current ripple,automatic current sharing and low voltage stress are also integrated in this converter.The working principle and features of the proposed converter are mainly introduced,and an experimental prototype with 800 W output power has been manufactured to verify the practicability and availability of the proposed converter.展开更多
文摘The Long March 2 F(LM-2F) launch vehicle, the only launch vehicle designed for manned space flight in China, successfully launched the Tiangong 2 space laboratory and the Shenzhou 11 manned spaceship into orbits in 2016 respectively. In this study, it introduces the technological improvements for enhancing the reliability of the LM-2F launch vehicle in the aspects of general technology, control system, manufacture and ground support system. The LM-2F launch vehicle will continue to provide more contributions to the Chinese Space Station Project with its high reliability and 100% success rate.
文摘Stress-strength model is a basic and important tool for reliability analysis.There are few methods to assess the confidence limit of interference reliability when the distribution parameters of stress and strength are all unknown.A new assessment method of interference reliability is proposed and the estimates of the distribution parameters are accordingly given.The lower confidence limit of interference reliability with given confidence can be obtained with the method even though the parameters are all unknown.Simulation studies and an engineering application are conducted to validate the method,which suggest that the method provides precise estimates even for sample size of approximately.
基金This work was supported by National Key Research&Development Plan of China under Grant 2016QY05X1000National Natural Science Foundation of China under Grant No.61771166CERNET Innovation Project(NGII20170412).
文摘The rapid development of Internet of Things(IoT)technology has made previously unavailable data available,and applications can take advantage of device data for people to visualize,explore,and build complex analyses.As the size of the network and the number of network users continue to increase,network requests tend to aggregate on a small number of network resources,which results in uneven load on network requests.Real-time,highly reliable network file distribution technology is of great importance in the Internet of Things.This paper studies real-time and highly reliable file distribution technology for large-scale networks.In response to this topic,this paper studies the current file distribution technology,proposes a file distribution model,and proposes a corresponding load balancing method based on the file distribution model.Experiments show that the system has achieved real-time and high reliability of network transmission.
文摘The worldwide space industry has entered a new space economy era.The question is how to develop in this new era?This paper tries to answer this question from two aspects:highly reliable and low-cost technology for access to space,and the cislunar economic zone.Firstly,the development requirement of the future space transportation system is discussed and the development path to enable high-reliability and a low cost of space transportation system is analyzed.Moreover,the concept of a routine space transportation system is proposed,upon which this paper gives some thoughts to the development of the cislunar economic zone thus embracing the new space economy era.
文摘As China’s only manned launch vehicle,the LM-2 F Launch vehicle successfully launched the Shenzhou 12 manned spacecraft into its predetermined orbit on June 12,2021,signifying the successful completion of the first manned launch mission in the construction and key technology test stage of China Space Station(CSS).From the launch of the Shenzhou 11 manned spacecraft on October 12,2016 to the launch of Shenzhou 12 in 2021,over the past five years,the LM-2 F launch vehicle has been continuously improved in terms of product reliability through technological innovation and design improvement,and its flight reliability index has increased from 0.97 to 0.98.Based on the new launch mission requirements for the construction stage of CSS,this paper introduces the technological innovation and reliability improvement methods of the LM-2 F from the aspects of design improvement,research methods and process optimization.The LM-2 F launch vehicle will make greater contributions in supporting the construction of CSS with higher reliability and perfect launch success rate.
文摘Accelerated destructive degradation tests(ADDTs)are powerful to provide reliability information in the degradation processes with destructive measurements.In order to carry out an ADDT efficiently,both the estimation precision of parameters and the test cost should be considered.On the basis of the given degradation model and failure criterion,a multiple-objective optimization model for the design of ADDTs is proposed.Under constrains of the maximum measurement time,the total sample size and the number of stress levels,a comprehensive target function is suggested to reflect both the precision of lifetime estimation and total cost,and the optimal test plan is obtained,which is composed by optimal choices for samples size,measurement frequency,and the number of measurements at each stress level.A real example is illustrated to demonstrate the implementation of the proposed approach.
基金Project supported by the National Key Research and Development Program of China(No.2021YFB3101100)。
文摘In distributed storage systems,replication and erasure code(EC)are common methods for data redundancy.Compared with replication,EC has better storage efficiency,but suffers higher overhead in update.Moreover,consistency and reliability problems caused by concurrent updates bring new challenges to applications of EC.Many works focus on optimizing the EC solution,including algorithm optimization,novel data update method,and so on,but lack the solutions for consistency and reliability problems.In this paper,we introduce a storage system that decouples data updating and EC encoding,namely,decoupled data updating and coding(DDUC),and propose a data placement policy that combines replication and parity blocks.For the(N,M)EC system,the data are placed as N groups of M+1 replicas,and redundant data blocks of the same stripe are placed in the parity nodes,so that the parity nodes can autonomously perform local EC encoding.Based on the above policy,a two-phase data update method is implemented in which data are updated in replica mode in phase 1,and the EC encoding is done independently by parity nodes in phase 2.This solves the problem of data reliability degradation caused by concurrent updates while ensuring high concurrency performance.It also uses persistent memory(PMem)hardware features of the byte addressing and eight-byte atomic write to implement a lightweight logging mechanism that improves performance while ensuring data consistency.Experimental results show that the concurrent access performance of the proposed storage system is 1.70–3.73 times that of the state-of-the-art storage system Ceph,and the latency is only 3.4%–5.9%that of Ceph.
基金supported by the National Natural Science Foundation of China(No.51707103)the Hubei Provincial Key Laboratory on Operation and Control of Cascaded Hydropower Station,China(No.2022KJX08).
文摘In this paper,a fault-tolerance wide voltage conversion gain DC/DC converter for More Electric Aircraft(MEA)is proposed.The proposed converter consists of a basic Cuk converter module and n expandable units.By adjusting the operation state of the expandable units,the voltage conversion gain of the proposed converter could be regulated,which makes it available for wide voltage conversion applications.Especially,since mutual redundancy can be realized between the basic Cuk converter module and the expandable units,the converter can continuously work when an unpredictable fault occurs to the fault-tolerant parts of the proposed converter,which reflects the fault tolerance of the converter and significantly improves the reliability of the system.Moreover,the advantages of small input current ripple,automatic current sharing and low voltage stress are also integrated in this converter.The working principle and features of the proposed converter are mainly introduced,and an experimental prototype with 800 W output power has been manufactured to verify the practicability and availability of the proposed converter.
