Vibration signals have the characteristics of multi-source strong shock coupling and strong noise interference owing to the complex structure of reciprocating machinery.Therefore,it is difficult to extract,analyze,and...Vibration signals have the characteristics of multi-source strong shock coupling and strong noise interference owing to the complex structure of reciprocating machinery.Therefore,it is difficult to extract,analyze,and diagnose mechanical fault features.To accurately extract sensitive features from the strong noise interference and unsteady monitoring signals of reciprocating machinery,a study on the time-frequency feature extraction method of multi-source shock signals is conducted.Combining the characteristics of reciprocating mechanical vibration signals,a targeted optimization method considering the variational modal decomposition(VMD)mode number and second penalty factor is proposed,which completed the adaptive decomposition of coupled signals.Aiming at the bilateral asymmetric attenuation characteristics of reciprocating mechanical shock signals,a new bilateral adaptive Laplace wavelet(BALW)is established.A search strategy for wavelet local parameters of multi-shock signals is proposed using the harmony search(HS)method.A multi-source shock simulation signal is established,and actual data on the valve fault are obtained through diesel engine fault experiments.The fault recognition rate of the intake and exhaust valve clearance is above 90%and the extraction accuracy of the shock start position is improved by 10°.展开更多
The role of inositol 1,4,5-trisphosphate （IP3） in transducing heat-shock （HS） signals was examined in Arabidopsis. The whole-plant IP3 level increased within 1 min of HS at 37℃. After 3 min of HS, the IP3 level r...The role of inositol 1,4,5-trisphosphate （IP3） in transducing heat-shock （HS） signals was examined in Arabidopsis. The whole-plant IP3 level increased within 1 min of HS at 37℃. After 3 min of HS, the IP3 level reached a maximum 2.5 fold increase. Using the transgenic Arabidopsis plants that have AtHsp 18.2 promoter-β-glucuronidase （GUS） fusion gene, it was found that the level of GUS activity was up-regulated by the addition of caged IP3 at both non-HS and HS temperatures and was down-regulated by the phospholipase C （PLC） inhibitors {1-[6-（（ 1713-3-Methoxyestra-1,3,5（10）-trien- 7-yl）amino）hexyl]-2,5-pyrrolidinedione } （U-73122）. The intracellular-free calcium ion concentration （[Ca^2＋]i） increased during HS at 37℃ in suspension-cultured Arabidopsis cells expressing apoaequorin. Treatment with U-73122 prevented the increase of [Ca^2＋]i to some extent. Above results provided primary evidence for the possible involvement of IP3 in HS signal transduction in higher plants.展开更多
It＇ s a problem to be solved how to de-noise the signal of blast shock wave overpressure. In the conventional methods, the high frequency of the signal is cut directly by some mathematics algorithms, such as Fourier ...It＇ s a problem to be solved how to de-noise the signal of blast shock wave overpressure. In the conventional methods, the high frequency of the signal is cut directly by some mathematics algorithms, such as Fourier Transform, but some of the useful signal will be cut together. We adopt a new method for the signal de-noising of shock wave overpressure by wavelet analysis, There are four steps in this method. Firstly, the original signal is de-compoed. Then the time-frequency features of the signal and noise are analyzed. Thirdly, the noise is separated from the signal by only cutting its frequency while the useful signal frequency is reserved as much as possible. Lastly, the useful signal with least loss of information is recovered by reconstruction process. To verify this method, a blast shock wave signal is de-noised with FFF to make a comparison. The results show that the signal de-noised by wavelet analysis approximates the ideal signal well.展开更多
During the test on transient pressure signal in explosion field,false trigger caused by field interference can lead to test failure.To improve the stability of test system,a signal detection and recognition technology...During the test on transient pressure signal in explosion field,false trigger caused by field interference can lead to test failure.To improve the stability of test system,a signal detection and recognition technology is proposed for transient pressure test system.In the process of signal acquisition,firstly,electrical levels are monitored in real time to find effective abrupt changes and mark them;then the effective data segments are detecdted totected;thus the effective signals can be acquired in turn finally.The experimental results show that the shock wave signal can be collected effectively and the reliability of the test system can be improved after removal of interferences.展开更多
In order to overcome the existing disadvantages of offline laser shock peening detection methods, an online detection method based on acoustic wave signals energy is provided. During the laser shock peening, an acoust...In order to overcome the existing disadvantages of offline laser shock peening detection methods, an online detection method based on acoustic wave signals energy is provided. During the laser shock peening, an acoustic emission sen- sor at a defined position is used to collect the acoustic wave signals that propagate in the air. The acoustic wave signal is sampled, stored, digitally filtered and analyzed by the online laser shock peening detection system. Then the system gets the acoustic wave signal energy to measure the quality of the laser shock peening by establishing the correspondence between the acoustic wave signal energy and the laser pulse energy. The surface residual stresses of the samples are measured by X-ray stress analysis instrument to verify the reliability. The results show that both the surface residual stress and acoustic wave signal energy are increased with the laser pulse energy, and their growth trends are consistent. Finally, the empirical formula between the surface residual stress and the acoustic wave signal energy is established by the cubic equation fitting, which will provide a theoretical basis for the real-time online detection of laser shock peening.展开更多
基金Supported by National Natural Science Foundation of China (Grant Nos.52101343,52201351)。
文摘Vibration signals have the characteristics of multi-source strong shock coupling and strong noise interference owing to the complex structure of reciprocating machinery.Therefore,it is difficult to extract,analyze,and diagnose mechanical fault features.To accurately extract sensitive features from the strong noise interference and unsteady monitoring signals of reciprocating machinery,a study on the time-frequency feature extraction method of multi-source shock signals is conducted.Combining the characteristics of reciprocating mechanical vibration signals,a targeted optimization method considering the variational modal decomposition(VMD)mode number and second penalty factor is proposed,which completed the adaptive decomposition of coupled signals.Aiming at the bilateral asymmetric attenuation characteristics of reciprocating mechanical shock signals,a new bilateral adaptive Laplace wavelet(BALW)is established.A search strategy for wavelet local parameters of multi-shock signals is proposed using the harmony search(HS)method.A multi-source shock simulation signal is established,and actual data on the valve fault are obtained through diesel engine fault experiments.The fault recognition rate of the intake and exhaust valve clearance is above 90%and the extraction accuracy of the shock start position is improved by 10°.
基金This work was supported by the National Natural Science Foundation of China （No. 30270796） Natural Science Foundation of Hebei Province, China （No. C2005000171）.
文摘The role of inositol 1,4,5-trisphosphate （IP3） in transducing heat-shock （HS） signals was examined in Arabidopsis. The whole-plant IP3 level increased within 1 min of HS at 37℃. After 3 min of HS, the IP3 level reached a maximum 2.5 fold increase. Using the transgenic Arabidopsis plants that have AtHsp 18.2 promoter-β-glucuronidase （GUS） fusion gene, it was found that the level of GUS activity was up-regulated by the addition of caged IP3 at both non-HS and HS temperatures and was down-regulated by the phospholipase C （PLC） inhibitors {1-[6-（（ 1713-3-Methoxyestra-1,3,5（10）-trien- 7-yl）amino）hexyl]-2,5-pyrrolidinedione } （U-73122）. The intracellular-free calcium ion concentration （[Ca^2＋]i） increased during HS at 37℃ in suspension-cultured Arabidopsis cells expressing apoaequorin. Treatment with U-73122 prevented the increase of [Ca^2＋]i to some extent. Above results provided primary evidence for the possible involvement of IP3 in HS signal transduction in higher plants.
文摘It＇ s a problem to be solved how to de-noise the signal of blast shock wave overpressure. In the conventional methods, the high frequency of the signal is cut directly by some mathematics algorithms, such as Fourier Transform, but some of the useful signal will be cut together. We adopt a new method for the signal de-noising of shock wave overpressure by wavelet analysis, There are four steps in this method. Firstly, the original signal is de-compoed. Then the time-frequency features of the signal and noise are analyzed. Thirdly, the noise is separated from the signal by only cutting its frequency while the useful signal frequency is reserved as much as possible. Lastly, the useful signal with least loss of information is recovered by reconstruction process. To verify this method, a blast shock wave signal is de-noised with FFF to make a comparison. The results show that the signal de-noised by wavelet analysis approximates the ideal signal well.
基金The 11th Postgraduate Technology Innovation Project of North University of China(No.20141142)
文摘During the test on transient pressure signal in explosion field,false trigger caused by field interference can lead to test failure.To improve the stability of test system,a signal detection and recognition technology is proposed for transient pressure test system.In the process of signal acquisition,firstly,electrical levels are monitored in real time to find effective abrupt changes and mark them;then the effective data segments are detecdted totected;thus the effective signals can be acquired in turn finally.The experimental results show that the shock wave signal can be collected effectively and the reliability of the test system can be improved after removal of interferences.
基金This study was co-supported by National Natural Science Foundation of China （51501219）, National Key Development Program of China （2016YFB 1192704）, NSFC -Liaoning Province United Foundation （U 1608259） and National Key Technology Research and Development Program of the Ministry of Science and Technology of China （2015BAFOBBO 1-01）.
文摘In order to overcome the existing disadvantages of offline laser shock peening detection methods, an online detection method based on acoustic wave signals energy is provided. During the laser shock peening, an acoustic emission sen- sor at a defined position is used to collect the acoustic wave signals that propagate in the air. The acoustic wave signal is sampled, stored, digitally filtered and analyzed by the online laser shock peening detection system. Then the system gets the acoustic wave signal energy to measure the quality of the laser shock peening by establishing the correspondence between the acoustic wave signal energy and the laser pulse energy. The surface residual stresses of the samples are measured by X-ray stress analysis instrument to verify the reliability. The results show that both the surface residual stress and acoustic wave signal energy are increased with the laser pulse energy, and their growth trends are consistent. Finally, the empirical formula between the surface residual stress and the acoustic wave signal energy is established by the cubic equation fitting, which will provide a theoretical basis for the real-time online detection of laser shock peening.
