In this paper, we obtain the optimum plan by discussing a constant-stress accelerated life test (ALT) satisfying the condition (3.3) at k stresses under an exponential distribution.
To estimate the life of vacuum fluorescent display （VFD） more accurately and reduce test time and cost, four constant stress accelerated life tests （CSALTs） were conducted on an accelerated life test model. In the...To estimate the life of vacuum fluorescent display （VFD） more accurately and reduce test time and cost, four constant stress accelerated life tests （CSALTs） were conducted on an accelerated life test model. In the model, statistical analysis of test data is achieved by applying lognormal function to describe the life distribution, and least square method （LSM） to calculate the mean value and the standard deviation of logarithm. As a result, the accelerated life equation was obtained, and then a self-developed software was developed to predict the VFD life. The data analysis results demonstrate that the VFD life submits to lognormal distribution, that the accelerated model meets the linear Arrhenius equation, and that the precise accelerated parameter makes it possible to acquire the life information of VFD within one month.展开更多
An issue to distinguish sensitive parameters of storage life prior to the failure of a bridgewire electro-(explosive) device (EED) is studied. The degradations of bridgewire resistance, 50% firing current, ignition de...An issue to distinguish sensitive parameters of storage life prior to the failure of a bridgewire electro-(explosive) device (EED) is studied. The degradations of bridgewire resistance, 50% firing current, ignition delay time, bridgewire molten time and powder color with the storage time were measured under a simulating accelerated life test of high-temperature and high-humidity. The most sensitive parameter suitable to evaluate the EED storage life is discussed. It is concluded that the standard deviation of resistance change is the most sensitive degradation variable, and the next is bridgewire molten time, 50% firing current and ignition delay time. The mean of resistance is an insensitive degradation parameter.展开更多
Engineering practice has shown that early faults of gearboxes are a leading maintenance cost driver that can easily lower the profit from a wind turbine operation.A novel oil-lubricated electrostatic monitoring of wea...Engineering practice has shown that early faults of gearboxes are a leading maintenance cost driver that can easily lower the profit from a wind turbine operation.A novel oil-lubricated electrostatic monitoring of wear debris for a wind turbine gearbox is presented.The continuous wavelet transform(CWT)is used to eliminate the noises of the original electrostatic signal.The kurtosis and root mean square(RMS)values of the time domain signal are extracted as the characteristic parameters to reflect the deterioration of the gearbox.The overall tendency of electrostatic signals in accelerated life test is analyzed.In the eighth cycle,the abnormal wear in the wind turbine gearbox is detected by electrostatic monitoring.A comparison with the popular MetalScan monitoring is given to illustrate the effectiveness of the electrostatic monitoring method.The results demonstrate that the electrostatic monitoring method can detect the fault accurately.展开更多
文摘In this paper, we obtain the optimum plan by discussing a constant-stress accelerated life test (ALT) satisfying the condition (3.3) at k stresses under an exponential distribution.
基金Shanghai Municipal Natural Science Foun-dation (NO.09ZR1413000)Undergraduate Education High-land Construction Project of ShanghaiKey Technology R&D Program of Shanghai Municipality (No.08160510600)
文摘To estimate the life of vacuum fluorescent display （VFD） more accurately and reduce test time and cost, four constant stress accelerated life tests （CSALTs） were conducted on an accelerated life test model. In the model, statistical analysis of test data is achieved by applying lognormal function to describe the life distribution, and least square method （LSM） to calculate the mean value and the standard deviation of logarithm. As a result, the accelerated life equation was obtained, and then a self-developed software was developed to predict the VFD life. The data analysis results demonstrate that the VFD life submits to lognormal distribution, that the accelerated model meets the linear Arrhenius equation, and that the precise accelerated parameter makes it possible to acquire the life information of VFD within one month.
文摘An issue to distinguish sensitive parameters of storage life prior to the failure of a bridgewire electro-(explosive) device (EED) is studied. The degradations of bridgewire resistance, 50% firing current, ignition delay time, bridgewire molten time and powder color with the storage time were measured under a simulating accelerated life test of high-temperature and high-humidity. The most sensitive parameter suitable to evaluate the EED storage life is discussed. It is concluded that the standard deviation of resistance change is the most sensitive degradation variable, and the next is bridgewire molten time, 50% firing current and ignition delay time. The mean of resistance is an insensitive degradation parameter.
基金co-supported by the National Natural Science Foundation of China(Nos.61403198,BK20140827 and U1233114)the Funding of Jiangsu Innovation Program for Graduate Education(No.KYLX15_0313)+1 种基金the Fundamental Research Funds for the Central Universities(No.NS2015072)the support provided by China Scholarship Council(No.201606830028)
文摘Engineering practice has shown that early faults of gearboxes are a leading maintenance cost driver that can easily lower the profit from a wind turbine operation.A novel oil-lubricated electrostatic monitoring of wear debris for a wind turbine gearbox is presented.The continuous wavelet transform(CWT)is used to eliminate the noises of the original electrostatic signal.The kurtosis and root mean square(RMS)values of the time domain signal are extracted as the characteristic parameters to reflect the deterioration of the gearbox.The overall tendency of electrostatic signals in accelerated life test is analyzed.In the eighth cycle,the abnormal wear in the wind turbine gearbox is detected by electrostatic monitoring.A comparison with the popular MetalScan monitoring is given to illustrate the effectiveness of the electrostatic monitoring method.The results demonstrate that the electrostatic monitoring method can detect the fault accurately.
