The Permanent Magnet Torque Motor(PMTM)is the key electro-mechanical conversion device in an Electro-Hydraulic Servo Valve(EHSV).In this work,a refined model of a PMTM is developed,considering the non-working air-gaps...The Permanent Magnet Torque Motor(PMTM)is the key electro-mechanical conversion device in an Electro-Hydraulic Servo Valve(EHSV).In this work,a refined model of a PMTM is developed,considering the non-working air-gaps between the upper or lower yoke and the armature,the fringing effect at the limiting holes,and the nonlinear permeability of soft magnetic material.Based on the refined model,the influences of various factors on the calculation accuracy of the magnetic flux at the pole surfaces of the armature and the output torque are investigated.For verifying the validity of the refined model,a Finite Element Analysis(FEA)of the PMTM is conducted,and a test platform is constructed.Compared with existing models,the refined model can better reveal the intrinsic mechanism of the PMTM,and its calculations are more consistent with the FEA results.The experimental results of the armature deflection displacement show that the refined model can accurately describe the output characteristics of the PMTM.展开更多
Objective:To evaluate the application value of a refined quality control management model for a sterilization supply center.Methods:A retrospective analysis was conducted on the work situation of the sterilization sup...Objective:To evaluate the application value of a refined quality control management model for a sterilization supply center.Methods:A retrospective analysis was conducted on the work situation of the sterilization supply center from January 2021 to January 2023.The work situation before January 31,2022,was classified as the control group;a routine quality control management model was implemented,and the work situation after January 31,2022,was classified as the observation group.The quality of medical device management and department satisfaction between the two groups were compared.Results:The timely recovery and supply rate,classification and cleaning pass rate,disinfection pass rate,packaging pass rate,sterilization pass rate,and department satisfaction score in the observation group were all higher than those of the control group(P<0.05).Conclusion:Implementing a refined quality control management model in the sterilization supply center can improve the quality management level of medical devices and department satisfaction and is worthy of promotion.展开更多
Overtopping is one of the main reasons for the breaching of concrete-face sand-gravel dams(CFSGDs).In this study,a refined mathematical model was established based on the characteristics of the overtopping breaching o...Overtopping is one of the main reasons for the breaching of concrete-face sand-gravel dams(CFSGDs).In this study,a refined mathematical model was established based on the characteristics of the overtopping breaching of CFSGDs.The model characteristics were as follows:(1)Based on the Renormailzation Group(RNG)k-εturbulence theory and volume of fluid(VOF)method,the turbulent characteristics of the dam-break flow were simulated,and the erosion surface of the water and soil was tracked;(2)In consideration of the influence of the change in the sediment content on the dam-break flow,the dam material transport equation,which could reflect the characteristics of particle settlement and entrainment motion,was used to simulate the erosion process of the sand gravels;(3)Based on the bending moment balance method,a failure equation of the concrete face slab under dead weight and water load was established.The proposed model was verified through a case study on the failure of the Gouhou CFSGD.The results showed that the proposed model could well simulate the erosion mode of the special vortex flow of the CFSGD scouring the support body of the concrete face slab inward and reflect the mutual coupling relationship between the dam-break flow,sand gravels,and concrete face slabs.Compared with the measured values,the relative errors of the peak discharge,final breach average width,dam breaching duration,and maximum failure length of the face slab calculated using the proposed model were all less than 12%,thus verifying the rationality of the model.The proposed model was demonstrated to perform better and provide more detailed results than three selected parametric models and three simplified mathematical models.The study results can aid in establishing the risk level and devising early warning strategies for CFSGDs.展开更多
The present paper presents an innovative approach for the numerical modeling of piezo-electric transducers for the health-monitoring of layered structures.The numerical approach has been developed in the frameworks of...The present paper presents an innovative approach for the numerical modeling of piezo-electric transducers for the health-monitoring of layered structures.The numerical approach has been developed in the frameworks of the Carrera Unified Formulation.This computa-tional tool allows refined numerical models to be derived in a unified and efficient fashion.The use of higher-order models and the cap-ability to connect different kinematic models using the node-depen-dent kinematic approach has led to an efficient modeling technique for global-local analysis.This approach can refine the model only in those regions where it is required,e.g.,the areas where piezo-electric transducers are placed.The model has been used to study embedded and surface-mounted sensors.The accuracy of the pre-sent model has been verified by comparing the current results with numerical and experimental data from the literature.Different mod-eling solutions have been developed,mixing one-,two-and threedimensional finite elements.The results show that the use of the present modeling technique allows the computational cost to be reduced with respect to the classical approaches preserving the ccuracy of the results in the critical areas.展开更多
This study investigated the degradation mechanism of the surrounding rock of a heavy-haul railway under a water-rich condition,based on the construction of the Taihangshan tunnel for the Wari Railway,a heavy-haul rail...This study investigated the degradation mechanism of the surrounding rock of a heavy-haul railway under a water-rich condition,based on the construction of the Taihangshan tunnel for the Wari Railway,a heavy-haul railway that used standard construction practices for axle loads of 30 t.Remote monitoring demonstrated that the coupling effect between the dynamic load of a heavy-haul train and the groundwater leads to the deterioration and hollowing of the surrounding rock.This study clarified the void evolution process and deterioration mechanism of the basement rock under the comprehensive influence of the groundwater–train dynamic load using a refined discrete element numerical simulation.The results revealed that the groundwater was the primary influencing factor in the deterioration of the lower part of the heavy-haul railway tunnel.Rock particles were gradually lost under the effects of long-term erosion due to groundwater and heavy-haul trains,which inevitably damaged the basement rock after the construction was completed.Based on this observation,the critical conditions for the deterioration and attenuation law of the physical parameters of the basement rock were obtained.The results of this study can provide ideas and serve as a reference for the forecasting and disaster treatment of basement rock damage in heavy-haul railway tunnels.展开更多
The tropospheric delay is a significant error source in Global Navigation Satellite System(GNSS)positioning and navigation.It is usually projected into zenith direction by using a mapping function.It is particularly i...The tropospheric delay is a significant error source in Global Navigation Satellite System(GNSS)positioning and navigation.It is usually projected into zenith direction by using a mapping function.It is particularly important to establish a model that can provide stable and accurate Zenith Tropospheric Delay(ZTD).Because of the regional accuracy difference and poor stability of the traditional ZTD models,this paper proposed two methods to refine the Hopfield and Saastamoinen ZTD models.One is by adding annual and semi-annual periodic terms and the other is based on Back-Propagation Artificial Neutral Network(BP-ANN).Using 5-year data from 2011 to 2015 collected at 67 GNSS reference stations in China and its surrounding regions,the four refined models were constructed.The tropospheric products at these GNSS stations were derived from the site-wise Vienna Mapping Function 1(VMP1).The spatial analysis,temporal analysis,and residual distribution analysis for all the six models were conducted using the data from 2016 to 2017.The results show that the refined models can effectively improve the accuracy compared with the traditional models.For the Hopfield model,the improvement for the Root Mean Square Error(RMSE)and bias reached 24.5/49.7 and 34.0/52.8 mm,respectively.These values became 8.8/26.7 and 14.7/28.8 mm when the Saastamoinen model was refined using the two methods.This exploration is conducive to GNSS navigation and positioning and GNSS meteorology by providing more accurate tropospheric prior information.展开更多
The loading capacity in the axial direction of a bolted thin steel plate was investigated.A refined numerical model of bolt was first constructed and then validated using existing experiment results.Parametrical analy...The loading capacity in the axial direction of a bolted thin steel plate was investigated.A refined numerical model of bolt was first constructed and then validated using existing experiment results.Parametrical analysis was performed to reveal the influences of geometric parameters,including the effective depth of the cap nut,the yield strength of the steel plate,the preload of the bolt,and shear force,on the ultimate loading capacity.Then,an analytical method was proposed to predict the ultimate load of the bolted thin steel plate.Results derived using the numerical and analytical methods were compared and the results indicated that the analytical method can accurately predict the pull-through capacity of bolted thin steel plates.The work reported in this paper can provide a simplified calculation method for the loading capacity in the axial direction of a bolt.展开更多
Background Recent advances in serial femtosecond crystallography(SFX)using X-ray free electron lasers(XFELs)have facilitated accurate structure determination for biological macromolecules.However,given the many fluctu...Background Recent advances in serial femtosecond crystallography(SFX)using X-ray free electron lasers(XFELs)have facilitated accurate structure determination for biological macromolecules.However,given the many fluctuations inherent in SFX,the acquisition of SFX data of sufficiently high quality still remains challenging.Method Aimed at enhancing the accuracy of SFX data,this study proposes an iterative refinement method to optimally match pairs of the observed and predicted reflections on the detector plane.This method features a combination of detector geometry optimization and diffraction model refinement in an alternate manner,concomitant with a cycle-by-cycle peak selection procedure.Result To demonstrate whether this iterative method is convergent and feasible,both numerical simulations and experimental tests have been performed.The results reveal that this method can gradually improve overall quality of the integrated SFX data and therefore accelerate the convergence of Monte Carlo integration,while simultaneously suppressing correlations inherent in certain parameters and precluding outliers to some extent during the refinement.Conclusion We have demonstrated that our iterative refinement method is applicable to both simulated and experimental SFX data.It is expected that this method could provide meaningful insights into the refinement of SFX data and take the step forward toward more accurate Monte Carlo integration.展开更多
基金co-supported by the National Natural Science Foundation of China(No.51975275)Primary Research&Development Plan of Jiangsu Province,China(No.BE2021034)Postgraduate Research&Practice Innovation Program of NUAA,China(No.xcxjh20210502).
文摘The Permanent Magnet Torque Motor(PMTM)is the key electro-mechanical conversion device in an Electro-Hydraulic Servo Valve(EHSV).In this work,a refined model of a PMTM is developed,considering the non-working air-gaps between the upper or lower yoke and the armature,the fringing effect at the limiting holes,and the nonlinear permeability of soft magnetic material.Based on the refined model,the influences of various factors on the calculation accuracy of the magnetic flux at the pole surfaces of the armature and the output torque are investigated.For verifying the validity of the refined model,a Finite Element Analysis(FEA)of the PMTM is conducted,and a test platform is constructed.Compared with existing models,the refined model can better reveal the intrinsic mechanism of the PMTM,and its calculations are more consistent with the FEA results.The experimental results of the armature deflection displacement show that the refined model can accurately describe the output characteristics of the PMTM.
文摘Objective:To evaluate the application value of a refined quality control management model for a sterilization supply center.Methods:A retrospective analysis was conducted on the work situation of the sterilization supply center from January 2021 to January 2023.The work situation before January 31,2022,was classified as the control group;a routine quality control management model was implemented,and the work situation after January 31,2022,was classified as the observation group.The quality of medical device management and department satisfaction between the two groups were compared.Results:The timely recovery and supply rate,classification and cleaning pass rate,disinfection pass rate,packaging pass rate,sterilization pass rate,and department satisfaction score in the observation group were all higher than those of the control group(P<0.05).Conclusion:Implementing a refined quality control management model in the sterilization supply center can improve the quality management level of medical devices and department satisfaction and is worthy of promotion.
基金supported by the National Science Fund for Distinguished Young Scholars(Grant No.52125904)the National Natural Science Foundation of China(Grant No.51979224)the Program 2022TD-01 for Shaanxi Provincial Innovative Research Team(Grant No.2022TD-01)。
文摘Overtopping is one of the main reasons for the breaching of concrete-face sand-gravel dams(CFSGDs).In this study,a refined mathematical model was established based on the characteristics of the overtopping breaching of CFSGDs.The model characteristics were as follows:(1)Based on the Renormailzation Group(RNG)k-εturbulence theory and volume of fluid(VOF)method,the turbulent characteristics of the dam-break flow were simulated,and the erosion surface of the water and soil was tracked;(2)In consideration of the influence of the change in the sediment content on the dam-break flow,the dam material transport equation,which could reflect the characteristics of particle settlement and entrainment motion,was used to simulate the erosion process of the sand gravels;(3)Based on the bending moment balance method,a failure equation of the concrete face slab under dead weight and water load was established.The proposed model was verified through a case study on the failure of the Gouhou CFSGD.The results showed that the proposed model could well simulate the erosion mode of the special vortex flow of the CFSGD scouring the support body of the concrete face slab inward and reflect the mutual coupling relationship between the dam-break flow,sand gravels,and concrete face slabs.Compared with the measured values,the relative errors of the peak discharge,final breach average width,dam breaching duration,and maximum failure length of the face slab calculated using the proposed model were all less than 12%,thus verifying the rationality of the model.The proposed model was demonstrated to perform better and provide more detailed results than three selected parametric models and three simplified mathematical models.The study results can aid in establishing the risk level and devising early warning strategies for CFSGDs.
文摘The present paper presents an innovative approach for the numerical modeling of piezo-electric transducers for the health-monitoring of layered structures.The numerical approach has been developed in the frameworks of the Carrera Unified Formulation.This computa-tional tool allows refined numerical models to be derived in a unified and efficient fashion.The use of higher-order models and the cap-ability to connect different kinematic models using the node-depen-dent kinematic approach has led to an efficient modeling technique for global-local analysis.This approach can refine the model only in those regions where it is required,e.g.,the areas where piezo-electric transducers are placed.The model has been used to study embedded and surface-mounted sensors.The accuracy of the pre-sent model has been verified by comparing the current results with numerical and experimental data from the literature.Different mod-eling solutions have been developed,mixing one-,two-and threedimensional finite elements.The results show that the use of the present modeling technique allows the computational cost to be reduced with respect to the classical approaches preserving the ccuracy of the results in the critical areas.
基金the National Natural Science Foundation of China(5108098,51508475)The Chongqing Education Commission science and technology research project(KJQN201901509)Sichuan University Key Laboratory Fundation of Bridge Nondestructive Testing and Engineering Calculation(2018QYJ06).
文摘This study investigated the degradation mechanism of the surrounding rock of a heavy-haul railway under a water-rich condition,based on the construction of the Taihangshan tunnel for the Wari Railway,a heavy-haul railway that used standard construction practices for axle loads of 30 t.Remote monitoring demonstrated that the coupling effect between the dynamic load of a heavy-haul train and the groundwater leads to the deterioration and hollowing of the surrounding rock.This study clarified the void evolution process and deterioration mechanism of the basement rock under the comprehensive influence of the groundwater–train dynamic load using a refined discrete element numerical simulation.The results revealed that the groundwater was the primary influencing factor in the deterioration of the lower part of the heavy-haul railway tunnel.Rock particles were gradually lost under the effects of long-term erosion due to groundwater and heavy-haul trains,which inevitably damaged the basement rock after the construction was completed.Based on this observation,the critical conditions for the deterioration and attenuation law of the physical parameters of the basement rock were obtained.The results of this study can provide ideas and serve as a reference for the forecasting and disaster treatment of basement rock damage in heavy-haul railway tunnels.
基金the Fundamental Research Funds for the Central Universities(No.2021XJDC01)the State Key Laboratory of Resources and Environmental Information System,the Key Laboratory of Geospace Environment and Geodesy,Ministry of Education,Wuhan University(No.19-02-08)+1 种基金the Guangxi Key Laboratory of Spatial Information and Geomatics(No.19-050-11-01)the National Natural Science Foundation of China(Nos.41804038,42001368).
文摘The tropospheric delay is a significant error source in Global Navigation Satellite System(GNSS)positioning and navigation.It is usually projected into zenith direction by using a mapping function.It is particularly important to establish a model that can provide stable and accurate Zenith Tropospheric Delay(ZTD).Because of the regional accuracy difference and poor stability of the traditional ZTD models,this paper proposed two methods to refine the Hopfield and Saastamoinen ZTD models.One is by adding annual and semi-annual periodic terms and the other is based on Back-Propagation Artificial Neutral Network(BP-ANN).Using 5-year data from 2011 to 2015 collected at 67 GNSS reference stations in China and its surrounding regions,the four refined models were constructed.The tropospheric products at these GNSS stations were derived from the site-wise Vienna Mapping Function 1(VMP1).The spatial analysis,temporal analysis,and residual distribution analysis for all the six models were conducted using the data from 2016 to 2017.The results show that the refined models can effectively improve the accuracy compared with the traditional models.For the Hopfield model,the improvement for the Root Mean Square Error(RMSE)and bias reached 24.5/49.7 and 34.0/52.8 mm,respectively.These values became 8.8/26.7 and 14.7/28.8 mm when the Saastamoinen model was refined using the two methods.This exploration is conducive to GNSS navigation and positioning and GNSS meteorology by providing more accurate tropospheric prior information.
基金The work described in this paper was financially supported by the Project funded by China Postdoctoral Science Foundation(No.2017M621156)the State Key Research Development Program of China(Nos.2016YFC0801404 and 2016YFC0600704).
文摘The loading capacity in the axial direction of a bolted thin steel plate was investigated.A refined numerical model of bolt was first constructed and then validated using existing experiment results.Parametrical analysis was performed to reveal the influences of geometric parameters,including the effective depth of the cap nut,the yield strength of the steel plate,the preload of the bolt,and shear force,on the ultimate loading capacity.Then,an analytical method was proposed to predict the ultimate load of the bolted thin steel plate.Results derived using the numerical and analytical methods were compared and the results indicated that the analytical method can accurately predict the pull-through capacity of bolted thin steel plates.The work reported in this paper can provide a simplified calculation method for the loading capacity in the axial direction of a bolt.
基金This work was financially supported by the grants from the Strategic Priority Research Program of CAS(XDB08030103)the National Natural Science Foundation of China(31570744,31670059).
文摘Background Recent advances in serial femtosecond crystallography(SFX)using X-ray free electron lasers(XFELs)have facilitated accurate structure determination for biological macromolecules.However,given the many fluctuations inherent in SFX,the acquisition of SFX data of sufficiently high quality still remains challenging.Method Aimed at enhancing the accuracy of SFX data,this study proposes an iterative refinement method to optimally match pairs of the observed and predicted reflections on the detector plane.This method features a combination of detector geometry optimization and diffraction model refinement in an alternate manner,concomitant with a cycle-by-cycle peak selection procedure.Result To demonstrate whether this iterative method is convergent and feasible,both numerical simulations and experimental tests have been performed.The results reveal that this method can gradually improve overall quality of the integrated SFX data and therefore accelerate the convergence of Monte Carlo integration,while simultaneously suppressing correlations inherent in certain parameters and precluding outliers to some extent during the refinement.Conclusion We have demonstrated that our iterative refinement method is applicable to both simulated and experimental SFX data.It is expected that this method could provide meaningful insights into the refinement of SFX data and take the step forward toward more accurate Monte Carlo integration.
