Recently, the phenomenon of "software aging", one in which the state of a software system gradually de-grades with time and eventually leads to performance degradation or crash/hang failure, has been reporte...Recently, the phenomenon of "software aging", one in which the state of a software system gradually de-grades with time and eventually leads to performance degradation or crash/hang failure, has been reported. The agingphenomenon is ubiquitous in all kinds of software systems and hard to eliminate thoroughly. A proactive techniquecalled "software rejuvenation" has been proposed[13] to counter the aging problem and increase the software availabili-ty. In this paper, we systematically investigate the basic motivation, concept and development of software rejuvena-tion, and then, detailedly analyze the main research work on it. At last, a prospect about the future research direc-tions is outlined.展开更多
The currently prevalent machine performance degradation assessment techniques involve estimating a machine＇s current condition based upon the recognition of indications of failure features,which entail complete data ...The currently prevalent machine performance degradation assessment techniques involve estimating a machine＇s current condition based upon the recognition of indications of failure features,which entail complete data collected in different conditions.However,failure data are always hard to acquire,thus making those techniques hard to be applied.In this paper,a novel method which does not need failure history data is introduced.Wavelet packet decomposition（WPD） is used to extract features from raw signals,principal component analysis（PCA） is utilized to reduce feature dimensions,and Gaussian mixture model（GMM） is then applied to approximate the feature space distributions.Single-channel confidence value（SCV） is calculated by the overlap between GMM of the monitoring condition and that of the normal condition,which can indicate the performance of single-channel.Furthermore,multi-channel confidence value（MCV）,which can be deemed as the overall performance index of multi-channel,is calculated via logistic regression（LR） and that the task of decision-level sensor fusion is also completed.Both SCV and MCV can serve as the basis on which proactive maintenance measures can be taken,thus preventing machine breakdown.The method has been adopted to assess the performance of the turbine of a centrifugal compressor in a factory of Petro-China,and the result shows that it can effectively complete this task.The proposed method has engineering significance for machine performance degradation assessment.展开更多
For some repeatedly occurring failure with root cause,the reliability centered maintenance (RCM) can’t deal with them effectively. So,the logic diagram of RCM was improved by combining it with proactive maintenance t...For some repeatedly occurring failure with root cause,the reliability centered maintenance (RCM) can’t deal with them effectively. So,the logic diagram of RCM was improved by combining it with proactive maintenance technology. First,root cause analysis is used to build a key result-cause chain of the repeatedly occur failure. Then,a reasonable link in the chain,which work station is suitable to be monitored and repaired,should be selected. Finally,the corresponding proactive maintenance measure should be adopted to prevent the matter occur on the chain and broken the key result-cause chain,and the repeatedly occur failure is to be prevent at a deeper level or from the root cause. By doing this,a system engineering method comes into being,not only it can determine the needs of preventive maintenance for equipment,but also determine the proactive maintenance needs for equipment. The analysis result of reliability centered maintenance and the analysis result considering proactive maintenance are combined to form a maintenance guideline containing proactive maintenance strategy.展开更多
文摘Recently, the phenomenon of "software aging", one in which the state of a software system gradually de-grades with time and eventually leads to performance degradation or crash/hang failure, has been reported. The agingphenomenon is ubiquitous in all kinds of software systems and hard to eliminate thoroughly. A proactive techniquecalled "software rejuvenation" has been proposed[13] to counter the aging problem and increase the software availabili-ty. In this paper, we systematically investigate the basic motivation, concept and development of software rejuvena-tion, and then, detailedly analyze the main research work on it. At last, a prospect about the future research direc-tions is outlined.
基金supported by National Key Natural Science Foundation of China (Grant No. 50635010)
文摘The currently prevalent machine performance degradation assessment techniques involve estimating a machine＇s current condition based upon the recognition of indications of failure features,which entail complete data collected in different conditions.However,failure data are always hard to acquire,thus making those techniques hard to be applied.In this paper,a novel method which does not need failure history data is introduced.Wavelet packet decomposition（WPD） is used to extract features from raw signals,principal component analysis（PCA） is utilized to reduce feature dimensions,and Gaussian mixture model（GMM） is then applied to approximate the feature space distributions.Single-channel confidence value（SCV） is calculated by the overlap between GMM of the monitoring condition and that of the normal condition,which can indicate the performance of single-channel.Furthermore,multi-channel confidence value（MCV）,which can be deemed as the overall performance index of multi-channel,is calculated via logistic regression（LR） and that the task of decision-level sensor fusion is also completed.Both SCV and MCV can serve as the basis on which proactive maintenance measures can be taken,thus preventing machine breakdown.The method has been adopted to assess the performance of the turbine of a centrifugal compressor in a factory of Petro-China,and the result shows that it can effectively complete this task.The proposed method has engineering significance for machine performance degradation assessment.
文摘For some repeatedly occurring failure with root cause,the reliability centered maintenance (RCM) can’t deal with them effectively. So,the logic diagram of RCM was improved by combining it with proactive maintenance technology. First,root cause analysis is used to build a key result-cause chain of the repeatedly occur failure. Then,a reasonable link in the chain,which work station is suitable to be monitored and repaired,should be selected. Finally,the corresponding proactive maintenance measure should be adopted to prevent the matter occur on the chain and broken the key result-cause chain,and the repeatedly occur failure is to be prevent at a deeper level or from the root cause. By doing this,a system engineering method comes into being,not only it can determine the needs of preventive maintenance for equipment,but also determine the proactive maintenance needs for equipment. The analysis result of reliability centered maintenance and the analysis result considering proactive maintenance are combined to form a maintenance guideline containing proactive maintenance strategy.
