Superconducting radio-frequency(SRF)cavities are the core components of SRF linear accelerators,making their stable operation considerably important.However,the operational experience from different accelerator labora...Superconducting radio-frequency(SRF)cavities are the core components of SRF linear accelerators,making their stable operation considerably important.However,the operational experience from different accelerator laboratories has revealed that SRF faults are the leading cause of short machine downtime trips.When a cavity fault occurs,system experts analyze the time-series data recorded by low-level RF systems and identify the fault type.However,this requires expertise and intuition,posing a major challenge for control-room operators.Here,we propose an expert feature-based machine learning model for automating SRF cavity fault recognition.The main challenge in converting the"expert reasoning"process for SRF faults into a"model inference"process lies in feature extraction,which is attributed to the associated multidimensional and complex time-series waveforms.Existing autoregression-based feature-extraction methods require the signal to be stable and autocorrelated,resulting in difficulty in capturing the abrupt features that exist in several SRF failure patterns.To address these issues,we introduce expertise into the classification model through reasonable feature engineering.We demonstrate the feasibility of this method using the SRF cavity of the China accelerator facility for superheavy elements(CAFE2).Although specific faults in SRF cavities may vary across different accelerators,similarities exist in the RF signals.Therefore,this study provides valuable guidance for fault analysis of the entire SRF community.展开更多
Acquiring pristine deep lunar regolith cores with appropriate drilling tools is crucial for deciphering the lunar geological history.Conventional thick-walled drill bits are inherently limited in obtaining deep lunar ...Acquiring pristine deep lunar regolith cores with appropriate drilling tools is crucial for deciphering the lunar geological history.Conventional thick-walled drill bits are inherently limited in obtaining deep lunar regolith samples,whereas thin-walled coring bits offer a promising solution for lunar deep drilling.To support future lunar deep exploration missions,this study systematically investigates the failure mechanisms of lunar regolith induced by thin-walled drilling tools.Firstly,five thin-walled bit configurations were designed and evaluated based on drilling load,coring efficiency,and disturbance minimization,with Bit D demonstrating optimal overall performance.And the interaction mechanisms between differently configured coring bits and large-particle lunar regolith were elucidated.Coring experiments under critical drilling parameters revealed an operational window for the feed-to-rotation ratio(FRR of 2.0–2.5),effectively balancing drilling load and core recovery rate.Furthermore,a novel theoretical framework was developed to characterize dynamic drilling load parameters,supported by experimental validation.Based on these findings,practical strategies are proposed to mitigate drilling-induced disturbances,including parameter optimization and bit structural improvements.This research could provide valuable insights for designing advanced lunar deep drilling tools and developing drilling procedures.展开更多
In recent years,the abuse of chemical fertilizers has caused numerous environmental problems,such as soil acidification and compaction.Replacing chemical fertilizers with organic fertilizers can effectively alleviate ...In recent years,the abuse of chemical fertilizers has caused numerous environmental problems,such as soil acidification and compaction.Replacing chemical fertilizers with organic fertilizers can effectively alleviate these problems.However,the effects of alternative organic fertilizers remain unclear.To explore the effects of organic fertilizer substitution on rice yield and paddy soil physicochemical properties and bacterial community structure,we conducted a 5-year experiment using different proportions of organic fertilizer substitution in a double-cropping rice field in Jiangxi,China.Our results showed that replacing chemical fertilizers with organic fertilizers can reduce soil acidification,increase soil organic matter content,nutrient contents,and enzyme activities,improve soil physicochemical properties and microbial community,and enhance soil metabolism.Appropriate organic substitution also had positive effects on rice production.These findings enhance our understanding of the effects of different alternative organic fertilization methods and have important theoretical significance for the promotion of the use of organic fertilizers in the future.展开更多
With the increasing scarcity of Earth’s resources and the development of space science and technology,the exploration, development, and utilization of deep space-specific material resources(minerals, water ice, volat...With the increasing scarcity of Earth’s resources and the development of space science and technology,the exploration, development, and utilization of deep space-specific material resources(minerals, water ice, volatile compounds, etc.) are not only important to supplement the resources and reserves on Earth but also provide a material foundation for establishing extraterrestrial research bases. To achieve large depth in-situ condition-preserved coring(ICP-Coring) in the extreme lunar environment, first, lunar rock simulant was selected(SZU-1), which has a material composition, element distribution, and physical and mechanical properties that are approximately equivalent to those of lunar mare basalt. Second, the influence of the lunar-based in-situ environment on the phase, microstructure, and thermal physical properties(specific heat capacity, thermal conductivity, thermal diffusivity, and thermal expansion coefficient)of SZU-1 was explored and compared with the measured lunar rock data. It was found that in an air atmosphere, low temperature has a more pronounced effect on the relative content of olivine than other temperatures, while in a vacuum atmosphere, the relative contents of olivine and anorthite are significantly affected only at temperatures of approximately-20 and 200 ℃. When the vacuum level is less than100 Pa, the contribution of air conduction can be almost neglected, whereas it becomes dominant above this threshold. Additionally, as the testing temperature increases, the surface of SZU-1 exhibits increased microcracking, fracture opening, and unevenness, while the specific heat capacity, thermal conductivity,and thermal expansion coefficient show nonlinear increases. Conversely, the thermal diffusivity exhibits a nonlinear decreasing trend. The relationship between thermal conductivity, thermal diffusivity, and temperature can be effectively described by an exponential function(R^(2)>0.98). The research results are consistent with previous studies on real lunar rocks. These research findings are expected to be applied in the development of the test and analysis systems of ICP-Coring in a lunar environment and the exploration of the mechanism of machine-rock interaction in the in-situ drilling and coring process.展开更多
基金supported by the studies of intelligent LLRF control algorithms for superconducting RF cavities(No.E129851YR0)the National Natural Science Foundation of China(No.U22A20261)Applications of Artificial Intelligence in the Stability Study of Superconducting Linear Accelerators(No.E429851YR0)。
文摘Superconducting radio-frequency(SRF)cavities are the core components of SRF linear accelerators,making their stable operation considerably important.However,the operational experience from different accelerator laboratories has revealed that SRF faults are the leading cause of short machine downtime trips.When a cavity fault occurs,system experts analyze the time-series data recorded by low-level RF systems and identify the fault type.However,this requires expertise and intuition,posing a major challenge for control-room operators.Here,we propose an expert feature-based machine learning model for automating SRF cavity fault recognition.The main challenge in converting the"expert reasoning"process for SRF faults into a"model inference"process lies in feature extraction,which is attributed to the associated multidimensional and complex time-series waveforms.Existing autoregression-based feature-extraction methods require the signal to be stable and autocorrelated,resulting in difficulty in capturing the abrupt features that exist in several SRF failure patterns.To address these issues,we introduce expertise into the classification model through reasonable feature engineering.We demonstrate the feasibility of this method using the SRF cavity of the China accelerator facility for superheavy elements(CAFE2).Although specific faults in SRF cavities may vary across different accelerators,similarities exist in the RF signals.Therefore,this study provides valuable guidance for fault analysis of the entire SRF community.
基金supported by the National Natural Science Foundation of China(Nos.52225403,52434004,and 52404365)the National Key Research and Development Program of China(No.2023YFF0615404)the Scientific Instrument Developing Project of Shenzhen University.
文摘Acquiring pristine deep lunar regolith cores with appropriate drilling tools is crucial for deciphering the lunar geological history.Conventional thick-walled drill bits are inherently limited in obtaining deep lunar regolith samples,whereas thin-walled coring bits offer a promising solution for lunar deep drilling.To support future lunar deep exploration missions,this study systematically investigates the failure mechanisms of lunar regolith induced by thin-walled drilling tools.Firstly,five thin-walled bit configurations were designed and evaluated based on drilling load,coring efficiency,and disturbance minimization,with Bit D demonstrating optimal overall performance.And the interaction mechanisms between differently configured coring bits and large-particle lunar regolith were elucidated.Coring experiments under critical drilling parameters revealed an operational window for the feed-to-rotation ratio(FRR of 2.0–2.5),effectively balancing drilling load and core recovery rate.Furthermore,a novel theoretical framework was developed to characterize dynamic drilling load parameters,supported by experimental validation.Based on these findings,practical strategies are proposed to mitigate drilling-induced disturbances,including parameter optimization and bit structural improvements.This research could provide valuable insights for designing advanced lunar deep drilling tools and developing drilling procedures.
基金supported by the National Key R&D Program of China(Nos.2017YFD0301601 and 2016YFD-0200402)National Natural Science Foundation of China(No.31560582)+1 种基金Beijing Key Laboratory of Biodiversity and Organic Farming,China(No.BOF201902)the funds of the Shandong"Double Tops"Program,China.
文摘In recent years,the abuse of chemical fertilizers has caused numerous environmental problems,such as soil acidification and compaction.Replacing chemical fertilizers with organic fertilizers can effectively alleviate these problems.However,the effects of alternative organic fertilizers remain unclear.To explore the effects of organic fertilizer substitution on rice yield and paddy soil physicochemical properties and bacterial community structure,we conducted a 5-year experiment using different proportions of organic fertilizer substitution in a double-cropping rice field in Jiangxi,China.Our results showed that replacing chemical fertilizers with organic fertilizers can reduce soil acidification,increase soil organic matter content,nutrient contents,and enzyme activities,improve soil physicochemical properties and microbial community,and enhance soil metabolism.Appropriate organic substitution also had positive effects on rice production.These findings enhance our understanding of the effects of different alternative organic fertilization methods and have important theoretical significance for the promotion of the use of organic fertilizers in the future.
基金supported by the National Natural Science Foundation of China(Nos.U2013603 and 52225403)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2019ZT08G315)the Shenzhen National Science Fund for Distinguished Young Scholars(No.RCJC20210706091948015).
文摘With the increasing scarcity of Earth’s resources and the development of space science and technology,the exploration, development, and utilization of deep space-specific material resources(minerals, water ice, volatile compounds, etc.) are not only important to supplement the resources and reserves on Earth but also provide a material foundation for establishing extraterrestrial research bases. To achieve large depth in-situ condition-preserved coring(ICP-Coring) in the extreme lunar environment, first, lunar rock simulant was selected(SZU-1), which has a material composition, element distribution, and physical and mechanical properties that are approximately equivalent to those of lunar mare basalt. Second, the influence of the lunar-based in-situ environment on the phase, microstructure, and thermal physical properties(specific heat capacity, thermal conductivity, thermal diffusivity, and thermal expansion coefficient)of SZU-1 was explored and compared with the measured lunar rock data. It was found that in an air atmosphere, low temperature has a more pronounced effect on the relative content of olivine than other temperatures, while in a vacuum atmosphere, the relative contents of olivine and anorthite are significantly affected only at temperatures of approximately-20 and 200 ℃. When the vacuum level is less than100 Pa, the contribution of air conduction can be almost neglected, whereas it becomes dominant above this threshold. Additionally, as the testing temperature increases, the surface of SZU-1 exhibits increased microcracking, fracture opening, and unevenness, while the specific heat capacity, thermal conductivity,and thermal expansion coefficient show nonlinear increases. Conversely, the thermal diffusivity exhibits a nonlinear decreasing trend. The relationship between thermal conductivity, thermal diffusivity, and temperature can be effectively described by an exponential function(R^(2)>0.98). The research results are consistent with previous studies on real lunar rocks. These research findings are expected to be applied in the development of the test and analysis systems of ICP-Coring in a lunar environment and the exploration of the mechanism of machine-rock interaction in the in-situ drilling and coring process.
