Bearings are crucial components in rotating machines,which have direct effects on industrial productivity and safety.To fast and accurately identify the operating condition of bearings,a novel method based on multi⁃sc...Bearings are crucial components in rotating machines,which have direct effects on industrial productivity and safety.To fast and accurately identify the operating condition of bearings,a novel method based on multi⁃scale permutation entropy(MPE)and morphology similarity distance(MSD)is proposed in this paper.Firstly,the MPE values of the original signals were calculated to characterize the complexity in different scales and they constructed feature vectors after normalization.Then,the MSD was employed to measure the distance among test samples from different fault types and the reference samples,and achieved classification with the minimum MSD.Finally,the proposed method was verified with two experiments concerning artificially seeded damage bearings and run⁃to⁃failure bearings,respectively.Different categories were considered for the two experiments and high classification accuracies were obtained.The experimental results indicate that the proposed method is effective and feasible in bearing fault diagnosis.展开更多
Eighteen models based on two equations of state(EoS),three viscosity models,and four mixing rules were constructed to predict the viscosities of natural gases at high temperature and high pressure(HTHP)conditions.For ...Eighteen models based on two equations of state(EoS),three viscosity models,and four mixing rules were constructed to predict the viscosities of natural gases at high temperature and high pressure(HTHP)conditions.For pure substances,the parameters of free volume(FV)and entropy scaling(ES)models were found to scale with molecular weight,which indicates that the ordered behavior of parameters of Peng-Robinson(PR)and Perturbed-Chain Statistical Associating Fluid Theory(PC-SAFT)propagates to the behavior of parameters of viscosity model.Predicting the viscosities of natural gases showed that the FV and ES models respectively combined with MIX4 and MIX2 mixing rules produced the best accuracy.Moreover,the FV models were more accurate for predicting the viscosities of natural gases than ES models at HTHP conditions,while the ES models were superior to PRFT models.The average absolute relative deviations of the best accurate three models,i.e.,PC-SAFT-FV-MIX4,tPR-FVMIX4,and PC-SAFT-ES-MIX2,were 5.66%,6.27%,and 6.50%,respectively,which was available for industrial production.Compared with the existing industrial models(corresponding states theory and LBC),the proposed three models were more accurate for modeling the viscosity of natural gas,including gas condensate.展开更多
The application of the excess entropy scaling(EES)method to predict the viscosity,thermal conductivity and thermal diffusivity of HFC/HFO refrigerants is evaluated in this paper.The universal coefficients of the EES m...The application of the excess entropy scaling(EES)method to predict the viscosity,thermal conductivity and thermal diffusivity of HFC/HFO refrigerants is evaluated in this paper.The universal coefficients of the EES model were firstly obtained from the properties of HFC refrigerants,and the accuracy of the model was further investigated with HFO properties.It was suggested that the EES model correlated the viscosity very well with the average absolute deviations(AADs)of most HFC refrigerants lower than 6.55%except R32.The correlations also provided very good prediction on the viscosity for R1234yf and R1234ze(E),but not for R1336mzz(Z).The prediction of thermal conductivity for both HFC and HFO refrigerants was generally well with the maximum AAD of 11.44%.However,the paper also indicated that there were no universal thermal diffusivity coefficients for even HFC refrigerants,and the linear function could not fit the thermal diffusivity curve very well.Therefore,the exclusively two-order polynomial correlations based on the EES model were presented for each HFC/HFO refrigerant.展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.51505100)
文摘Bearings are crucial components in rotating machines,which have direct effects on industrial productivity and safety.To fast and accurately identify the operating condition of bearings,a novel method based on multi⁃scale permutation entropy(MPE)and morphology similarity distance(MSD)is proposed in this paper.Firstly,the MPE values of the original signals were calculated to characterize the complexity in different scales and they constructed feature vectors after normalization.Then,the MSD was employed to measure the distance among test samples from different fault types and the reference samples,and achieved classification with the minimum MSD.Finally,the proposed method was verified with two experiments concerning artificially seeded damage bearings and run⁃to⁃failure bearings,respectively.Different categories were considered for the two experiments and high classification accuracies were obtained.The experimental results indicate that the proposed method is effective and feasible in bearing fault diagnosis.
基金supported by the China Scholarship Council(No.202209225014)National Science Fund for Excellent Young Scholars(Grant No.52222402)+8 种基金National Natural Science Foundation of China(Grant No.52234003)National Natural Science Foundation of China(Grant No.52074235)National Science and Technology Major Project of China during the 13th Five-Year Plan Period(2016ZX05062)Sichuan Science and Technology Program(Grant No.2021YJ0345)National Natural Science Foundation of China(Grant No.51874251,51774243,52174036,and 51704247)Sichuan Science and Technology Program(NO.2022JDJQ0009)shale gas industry development Institute of Sichuan province,International S&T Cooperation Program of Sichuan Province(Grant No.2019YFH0169)the Deep Marine shale gas efficient development Overseas Expertise Introduction Center for Discipline Innovation(111 Center)Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(No.2020CX020202,2020CX030202).
文摘Eighteen models based on two equations of state(EoS),three viscosity models,and four mixing rules were constructed to predict the viscosities of natural gases at high temperature and high pressure(HTHP)conditions.For pure substances,the parameters of free volume(FV)and entropy scaling(ES)models were found to scale with molecular weight,which indicates that the ordered behavior of parameters of Peng-Robinson(PR)and Perturbed-Chain Statistical Associating Fluid Theory(PC-SAFT)propagates to the behavior of parameters of viscosity model.Predicting the viscosities of natural gases showed that the FV and ES models respectively combined with MIX4 and MIX2 mixing rules produced the best accuracy.Moreover,the FV models were more accurate for predicting the viscosities of natural gases than ES models at HTHP conditions,while the ES models were superior to PRFT models.The average absolute relative deviations of the best accurate three models,i.e.,PC-SAFT-FV-MIX4,tPR-FVMIX4,and PC-SAFT-ES-MIX2,were 5.66%,6.27%,and 6.50%,respectively,which was available for industrial production.Compared with the existing industrial models(corresponding states theory and LBC),the proposed three models were more accurate for modeling the viscosity of natural gas,including gas condensate.
基金sponsored by the following research grants:National Science Foundation of China(No 51906216)。
文摘The application of the excess entropy scaling(EES)method to predict the viscosity,thermal conductivity and thermal diffusivity of HFC/HFO refrigerants is evaluated in this paper.The universal coefficients of the EES model were firstly obtained from the properties of HFC refrigerants,and the accuracy of the model was further investigated with HFO properties.It was suggested that the EES model correlated the viscosity very well with the average absolute deviations(AADs)of most HFC refrigerants lower than 6.55%except R32.The correlations also provided very good prediction on the viscosity for R1234yf and R1234ze(E),but not for R1336mzz(Z).The prediction of thermal conductivity for both HFC and HFO refrigerants was generally well with the maximum AAD of 11.44%.However,the paper also indicated that there were no universal thermal diffusivity coefficients for even HFC refrigerants,and the linear function could not fit the thermal diffusivity curve very well.Therefore,the exclusively two-order polynomial correlations based on the EES model were presented for each HFC/HFO refrigerant.
