Several software reliability growth models （SRGM） have been developed to monitor the reliability growth during the testing phase of software development. In most of the existing research available in the literatures...Several software reliability growth models （SRGM） have been developed to monitor the reliability growth during the testing phase of software development. In most of the existing research available in the literatures, it is considered that a similar testing effort is required on each debugging effort. However, in practice, different types of faults may require different amounts of testing efforts for their detection and removal. Consequently, faults are classified into three categories on the basis of severity： simple, hard and complex. This categorization may be extended to r type of faults on the basis of severity. Although some existing research in the literatures has incorporated this concept that fault removal rate （FRR） is different for different types of faults, they assume that the FRR remains constant during the overall testing period. On the contrary, it has been observed that as testing progresses, FRR changes due to changing testing strategy, skill, environment and personnel resources. In this paper, a general discrete SRGM is proposed for errors of different severity in software systems using the change-point concept. Then, the models are formulated for two particular environments. The models were validated on two real-life data sets. The results show better fit and wider applicability of the proposed models as to different types of failure datasets.展开更多
A new rotor broken bar fault diagnosis method for induction motors based on the double PQ transformation is pre-sented. By distinguishing the different patterns of the PQ components in the PQ plane,the rotor broken ba...A new rotor broken bar fault diagnosis method for induction motors based on the double PQ transformation is pre-sented. By distinguishing the different patterns of the PQ components in the PQ plane,the rotor broken bar fault can be detected. The magnitude of power component directly resulted from rotor fault is used as the fault indicator and the distance between the point of no-load condition and the center of the ellipse as its normalization value. Based on these,the fault severity factor which is completely independent of the inertia and load level is defined. Moreover,a method to reliably discriminate between rotor faults and periodic load fluctuation is presented. Experimental results from a 4 kW induction motor demonstrated the validity of the proposed method.展开更多
S Zorb装置程控阀的可靠性运行是成品汽油硫含量达标的关键。程控阀的阀体、附件等在阀门的频繁动作以及恶劣现场环境下会产生一系列问题,影响装置的稳定性。使用故障模式影响与危害度分析(FMECA)方法分析程控阀各子系统故障严重性,利...S Zorb装置程控阀的可靠性运行是成品汽油硫含量达标的关键。程控阀的阀体、附件等在阀门的频繁动作以及恶劣现场环境下会产生一系列问题,影响装置的稳定性。使用故障模式影响与危害度分析(FMECA)方法分析程控阀各子系统故障严重性,利用模糊评价与层次分析法(AHP)建立程控阀维护策略,将二者组合形成FMECA-AHP方法,并应用于某石化公司S Zorb装置。结果表明:采用FMECA-AHP方法对程控阀各子系统故障进行等级划分并设计维护策略,可有效提高S Zorb装置程控阀维护效率,该方法高效、可靠,降低了成本,为企业创造了效益。展开更多
Fault current limiting is a critical technology to en sure the safe operation of modular multilevel converter based multi-terminal direct current(MMC-MTDC)grids.This paper proposes a fault severity classification base...Fault current limiting is a critical technology to en sure the safe operation of modular multilevel converter based multi-terminal direct current(MMC-MTDC)grids.This paper proposes a fault severity classification based coordination con trol strategy of fault current limiter(FCL)and MMC for adap tive fault current limiting.The proposed strategy reduces the in vestment in FCL,and keeps the bus voltages of non-faulty lines at reasonable values.Firstly,a rapid fault circuit parameter esti mation(FCPE)method using initial fault current information is proposed.With this method,the fault distance and fault transi tion resistance can be quickly estimated,which are used for a quantitative indication of the fault severity.Subsequently,the coordination control strategy of FCL and MMC is proposed,in which the FCL action is prioritized,while the control of MMC is complementary for current limiting.Based on the proposed strategy,fault severity phase planes(FSPPs)are constructed to assess fault severity and calculate the activation time of FCL and voltage regulation factor of MMC.Therefore,the FCL acti vation and MMC control are matched to the fault severity.The effectiveness and advantages of the proposed strategy are vali dated by the simulations in PSCAD/EMTDC.展开更多
文摘Several software reliability growth models （SRGM） have been developed to monitor the reliability growth during the testing phase of software development. In most of the existing research available in the literatures, it is considered that a similar testing effort is required on each debugging effort. However, in practice, different types of faults may require different amounts of testing efforts for their detection and removal. Consequently, faults are classified into three categories on the basis of severity： simple, hard and complex. This categorization may be extended to r type of faults on the basis of severity. Although some existing research in the literatures has incorporated this concept that fault removal rate （FRR） is different for different types of faults, they assume that the FRR remains constant during the overall testing period. On the contrary, it has been observed that as testing progresses, FRR changes due to changing testing strategy, skill, environment and personnel resources. In this paper, a general discrete SRGM is proposed for errors of different severity in software systems using the change-point concept. Then, the models are formulated for two particular environments. The models were validated on two real-life data sets. The results show better fit and wider applicability of the proposed models as to different types of failure datasets.
基金Project (No. 50677060) supported by the National Natural ScienceFoundation of China
文摘A new rotor broken bar fault diagnosis method for induction motors based on the double PQ transformation is pre-sented. By distinguishing the different patterns of the PQ components in the PQ plane,the rotor broken bar fault can be detected. The magnitude of power component directly resulted from rotor fault is used as the fault indicator and the distance between the point of no-load condition and the center of the ellipse as its normalization value. Based on these,the fault severity factor which is completely independent of the inertia and load level is defined. Moreover,a method to reliably discriminate between rotor faults and periodic load fluctuation is presented. Experimental results from a 4 kW induction motor demonstrated the validity of the proposed method.
基金supported in part by the National Natural Science Foundation of China(No.52207126)the Natural Science Foundation of Sichuan Province(No.2024NSFSC0869)the Joint Funds of the National Natural Science Foundation of China(No.U22B6006).
文摘Fault current limiting is a critical technology to en sure the safe operation of modular multilevel converter based multi-terminal direct current(MMC-MTDC)grids.This paper proposes a fault severity classification based coordination con trol strategy of fault current limiter(FCL)and MMC for adap tive fault current limiting.The proposed strategy reduces the in vestment in FCL,and keeps the bus voltages of non-faulty lines at reasonable values.Firstly,a rapid fault circuit parameter esti mation(FCPE)method using initial fault current information is proposed.With this method,the fault distance and fault transi tion resistance can be quickly estimated,which are used for a quantitative indication of the fault severity.Subsequently,the coordination control strategy of FCL and MMC is proposed,in which the FCL action is prioritized,while the control of MMC is complementary for current limiting.Based on the proposed strategy,fault severity phase planes(FSPPs)are constructed to assess fault severity and calculate the activation time of FCL and voltage regulation factor of MMC.Therefore,the FCL acti vation and MMC control are matched to the fault severity.The effectiveness and advantages of the proposed strategy are vali dated by the simulations in PSCAD/EMTDC.
