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Observations of Ion Cyclotron Waves Upstream from the Martian Bow Shock

Chinese Astronomy and Astrophysics 2025年第1期49卷 175-192页

作者： Jia-wei, Li Lei, Yang De-jin, Wu Cun-li, Dai Jian-ping, Li Liang, Xiang Qing-yu, Luo Zheng-wei, Cheng Key Laboratory of Planetary Sciences Purple Mountain Observatory CAS Nanjing 210023 School of Astronomy and Space Science University of Science Technology of China Hefei 230026 China State Key Laboratory of Space Weather National Space Science Center CAS Beijing 100190 College of Sciences Nanjing Agricultural University Nanjing 210095 Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory CAS Nanjing 210023 Institute of Space Physics Luoyang Normal University Luoyang 471934 Henan Key Laboratory of Electromagnetic Transformation and Detection Luoyang Normal University Luoyang 471934

Ion cyclotron waves are widely present upstream from the Martian bow shock, with frequencies near the local proton cyclotron frequency in the spacecraft frame. The waves propagate quasi-parallel to the background magnetic field, and are associated with the solar wind picking up newly-ionized hydrogen from the Martian exosphere. In this work, a typical ion cyclotron wave event was observed by MAVEN (Mars Atmosphere and Volatile Evolution) probe upstream from the Martian bow shock. The further MVA (minimum variance analysis) results for this event show that the magnetic field perturbations are left-handed polarized and propagate quasi-parallel (the propagation angle θ = 12.37^∘) to the background magnetic field. The relationship between the plasma perturbations and magnetic field perturbations is theoretically derived for slow magnetosonic, Alfv{\'e}n, and fast magnetosonic waves based on the magnetohydrodynamic theory. If we take the wave propagation angle θ = 12.37^∘ estimated from the MVA method, the theoretically expected density perturbation and velocity perturbation along the background magnetic field are in serious disagreement with the MAVEN data. Through fitting the plasma density perturbation, velocity perturbation, and magnetic field perturbation, it is found that the ion cyclotron wave event can be explained by the superposition of oblique fast magnetosonic waves with a propagation angle of 63^∘ relative to the background magnetic field and parallel propagating Alfv{\'e}n waves. The results are helpful to further understand the physical nature of the observed ion cyclotron wave-related perturbations upstream from the Martian bow shock, and have guiding implications for the re-modeling and numerical simulation of the plasma physical processes therein. © 2024

关键词： ion cyclotron wave—upstream from Mars—magnetohydrodynamics (MHD)—fast magnetosonic wave—Alfvén wave—slow magnetosonic wave

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Characteristics of boreal summer compound hot-drought events in the Yangtze River Valley and relationships with Indian Ocean Sea surface temperature

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Climate Dynamics 2025年第5期63卷 1-17页

作者： Zhang, Yifang An, Xuehua Sun, Shanlei Ma, Qianrong Yan, Pengcheng Zhou, Botao State Key Laboratory of Climate System Prediction and Risk Management/Key Laboratory of Meteorological Disaster Ministry of Education/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and Technology Nanjing 210044 China State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081 China College of Physical Science and Technology Yangzhou University Yangzhou 225012 China Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province/Key Laboratory of Arid Climatic Change and Reducing Disaster of China Meteorological Administration Institute of Arid Meteorology of China Meteorological Administration Lanzhou 730030 China

Compound hot-drought events (CHDEs) have drawn widespread attention for their severe impacts on ecosystems and human livelihoods. This study investigated the characteristics and driving mechanisms of boreal summer CHDEs in the Yangtze River Valley (YRV) during 1961–2022. Results showed that the most intense events were concentrated in Sichuan Province, with both the affected area and event severity exhibiting significant upward trends during the study period. A strong relationship was identified between CHDEs in the YRV and sea surface temperature (SST) anomalies in the Indian Ocean, independent of El Niño-Southern Oscillation (ENSO) influences. Cold SST anomalies cooled the tropical troposphere, triggering easterly winds over East Asia subtropical regions. Concurrently, increased precipitation over north-central India induced an upper-tropospheric anticyclone over the northwestern Tibetan Plateau. In turn, the propagated Rossby waves promoted anticyclonic conditions over East Asia and maintained a meridional dipole circulation pattern. Anomalous high-pressure systems over the North Atlantic and Europe-West Siberia amplified these patterns, which further altered surface radiation budgets, drying the land and enhancing sensible heat flux. The resulting land-atmosphere interaction sustained anticyclonic circulation, intensifying CHDEs in the YRV. Projections under the different warming scenarios suggested that the frequency of these atmospheric circulation patterns was likely to increase, exacerbating CHDEs in the YRV and posing heightened risks to the environment and society. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.

关键词： Atmospheric circulation Compound hot-drought events Flow analog Indian Ocean Yangtze River Valley

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Short-Term Synchronous and Asynchronous Ambient Noise Tomography in Urban Areas: Application to Karst Investigation

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Engineering 2025年第5期48卷 292-308页

作者： Liu, Ya Xia, Jianghai Guan, Bo Xi, Chaoqiang Ning, Ling Zhang, Hao Key Laboratory of Geoscience Big Data and Deep Resource of Zhejiang Province School of Earth Sciences Zhejiang University Hangzhou310027 China State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines School of Earth and Environment Anhui University of Science and Technology Huainan232001 China Key Laboratory of Poyang Lake Wetland and Watershed Research Ministry of Education Jiangxi Normal University Nanchang330022 China Greater Bay Area Branch of Aerospace Information Research Institute Chinese Academy of Sciences Guangzhou510700 China

Dense-array ambient noise tomography is a powerful tool for achieving high-resolution subsurface imaging, significantly impacting geohazard prevention and control. Conventional dense-array studies, however, require simultaneous observations of numerous stations for extensive coverage. To conduct a comprehensive karst feature investigation with limited stations, we designed a new synchronous–asynchronous observation system that facilitates dense array observations. We conducted two rounds of asynchronous observations, each lasting approximately 24 h, in combination with synchronous backbone stations. We achieved wide-ranging coverage of the study area utilizing 197 nodal receivers, with an average station spacing of 7 m. The beamforming results revealed distinct variations in the noise source distributions between day and night. We estimated the source strength in the stationary phase zone and used a weighting scheme for stacking the cross-correlation functions (C1 functions) to suppress the influence of nonuniform noise source distributions. The weights were derived from the similarity coefficients between multicomponent C1 functions related to Rayleigh waves. We employed the cross-correlation of C1 functions (C2 methods) to obtain the empirical Green's functions between asynchronous stations. To eliminate artifacts in C2 functions from higher-mode surface waves in C1 functions, we filtered the C1 functions on the basis of different particle motions linked to multimode Rayleigh waves. The dispersion measurements of Rayleigh waves obtained from both the C1 and C2 functions were utilized in surface wave tomography. The inverted three-dimensional (3D) shear-wave (S-wave) velocity model reveals two significant low-velocity zones at depths ranging from 40 to 60 m, which align well with the karst caves found in the drilling data. The method of short-term synchronous–asynchronous ambient noise tomography shows promise as a cost-effective and efficient approach for urban ge

关键词： Shear waves

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Multispectral imaging and enhanced YOLOv10n for efficient coal gangue detection in complex mining environments

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Journal of Real-Time Image Processing 2025年第3期22卷 1-14页

作者： Yan, Pengcheng Sun, Hao Zhao, Yuanjun Wang, Pinghong Wu, Zhiqi State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine Anhui University of Science and Technology Huainan 232001 China

To address the issues in existing coal gangue recognition methods, such as large detection models that are difficult to deploy on embedded devices, long detection times, and low accuracy, this paper proposes a method that collects multispectral images of coal gangue based on spectral technology and integrates an improved lightweight YOLOv10n model for target recognition and detection. This approach effectively reduces the model size, decreases detection time, and improves the accuracy and performance of coal gangue recognition. To reduce the model parameters, this study adopts the lightweight neural network architecture MobileNetV4 to replace the original backbone and further optimizes it for efficiency. Additionally, GhostConv layers are used in the head of the model to replace traditional Conv layers, reducing the computational burden. However, the model’s accuracy in multi-target recognition was still not ideal, so a Spatial Group-wise Enhancement (SGE) module was added after the C2fCIB (Contextual Feature Fusion and Inference Block) module in the head, significantly improving detection accuracy. The coal gangue dataset in this study was collected using a multispectral data acquisition system, resulting in 4500 sets of multispectral data. Through Principal Component Analysis (PCA), spectral images from the 4^th, 6^th, 22^th, and 25^th bands were selected from a total of 25 bands to generate pseudo-RGB images, forming the dataset for this study. A total of 974 initial sample images of coal gangue were collected. After applying Gaussian filtering to reduce noise and implementing data augmentation on certain images, a dataset of 4000 coal gangue images was generated. These images were then split into training and testing sets with a ratio of 4:1. The final improved model, M4-GHOST-SGE-YOLOv10n, further enhanced precision and recall. Compared to the original model, the M4-GHOST-SGE-YOLOv10n model reduced parameters and GFLOPs b

关键词： Coal gangue recognition Lightweight YOLOv10n Spatial group-wise enhancement module, SGE Spectral technology

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Petrogenesis of the Xifanping Porphyries in the Sanjiang Orogenic Belt,SW China:Eastward Propagation of the Indo-Asian Collision

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Acta Geologica Sinica(English Edition) 2025年第2期99卷 441-458页

作者： QIU Lei LI Lin ZHAO Guochun GUAN Chengyao LEI Hangshan SUN Kai TANG Yan ZHAO Zhidan Masroor ALAM LI Xiaowei Thomas BADER State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China Department of Earth Science Institute of Disaster Prevention Science and TechnologySanheHebei 065201China Tianjin Center China Geological SurveyTianjin 300170China Department of Earth Sciences Karakoram International University15100 GilgitGilgit BaltistanPakistan Institute of Geomechanics Chinese Academy of Geological SciencesMNR Key Laboratory of Paleomagnetism and Tectonic ReconstructionBeijing 100081China

Large-scale Cenozoic alkali-rich magmatic rocks are exposed at the eastern margin of Tibet due to the interaction between the Indian and Eurasian ***,their petrogenesis and associated geodynamic processes remain poorly *** analyzed the Xifanping porphyries in the Sanjiang orogenic belt to provide new *** study shows a successive assembly of porphyry intrusions during three magmatic *** magnitude and duration of the magmatic activities diminished sequentially,and mineralization occurred during the intermediate ***,the Xifangping porphyries display an adakitic *** to zircon Hf isotope data,we propose that these porphyries originated from the partial melting of the thickened mafic lower crust beneath the western Yangtze Craton in response to lithospheric extension and asthenospheric *** to the coeval alkali-rich porphyries in western Yunnan,the petrogenetic model of the Xifanping porphyries indicates regional north-south and east-west fractures caused by the clockwise rotation of the continental lithosphere and the Jinshajiang-Red River strike-slip during the post-collision phase of the India-Eurasia *** this context,we argue that the collision in eastern Tibet may have extended eastward to southwestern Sichuan during the post-collision period,persisting until approximately 30 Ma.

关键词： zircon U-Pb age Xifanping porphyries adakitic rocks southwestern Sichuan

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Geostatistics-block-based characterization of the relationship between rock mass quality and powder factor and its application on open-pit limit optimization

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International Journal of Mining science and technology 2025年第1期35卷 135-147页

作者： Jinduo Li Tianhong Yang Feiyue Liu Shigui Du Wenxue Deng Yong Zhao Honglei Liu Leilei Niu Zhiqiang Xu Center for Rock Instability and Seismicity Research School of Resources&Civil EngineeringNortheastern UniversityShenyang 110819China State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines Anhui University of Science and TechnologyHuainan 232001China Institute of Rock Mechanics Ningbo UniversityNingbo 315211China Shuguang Gold and Copper Open Pit Mine Zijin Mining Group Company LimitedHunchun 133300China

Accurately predicting the powder factor during blasting is essential for sustainable production planning in low-grade *** research presents a method for predicting powder factor based on the heterogeneity of rock mass rating(RMR).Considering a low-grade metal mine as an example,this study exploited geostatistical methods to obtain independent RMR for each block unit.A three-dimensional spatial distribution model for the powder factor was developed on the basis of the relationships between the RMR and the powder ***,models for blasting cost and mining value were built and employed to optimize the open-pit *** multi-variable model based on the RMR performed well in predicting the powder factor,achieving a correlation coefficient of 0.88(root mean square error of 4.3)and considerably outperforming the uniaxial compressive strength *** model optimization,the mean size and standard deviation of the fragments in the blast pile decreased by 8.5%and 35.1%,respectively,whereas the boulder yield and its standard deviation decreased by 33.3%and 58.8%,***,optimizing the open-pit limit using this method reduced the amount of rock,increased the amount of ore,and lowered blasting costs,thereby enhancing the economic efficiency of the *** study provides valuable insights for blasting design and mining decisions,demonstrating the advantages and potential applications of powder factor prediction based on the heterogeneity of rock mass quality.

关键词： Geostatistics method Powder factor Open-pit limit optimization Blasting cost Rock mass quality

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Seasonal Prediction of Pre-Summer Clustered Heavy Precipitation Days in South China

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Journal of Tropical Meteorology 2025年第1期31卷 107-119页

作者： ZHI Yao HAN Ting-ting JIANG Shun-li WANG Hui-jun HAO Xin LI Shang-feng State Key Laboratory of Climate System Prediction and Risk Management/Key Laboratory of Meteorological Disaster Ministry of Education/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University for Information Science and TechnologyNanjing 210044 China Nansen-Zhu International Research Centre Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) ZhuhaiGuangdong 519080 China Jilin Provincial Key Laboratory of Changbai Mountain Meteorology&Climate Change Laboratory of Research for Middle-High Latitude Circulation Systems and East Asian MonsoonInstitute of Meteorological Sciences of Jilin ProvinceChangchun 130062 China

Clustered heavy precipitation(CHP)events can severely impact human society,infrastructure,and natural ***,short-term climate prediction of CHP events is vital for the prevention and mitigation of associated *** year-to-year increment(DY)and multiple linear regression approaches,this study developed a seasonal prediction model for pre-summer(i.e.,May and June)CHP frequency in South China(SC)during 1981–*** robust predictor factors were identified:March sea surface temperature in Southwestern Atlantic,early-winter snow depth in East Europe,and winter soil moisture in Central *** predictors exert substantial impacts on presummer precipitation in SC via modulation of an anomalous anticyclone(cyclone)over the(subtropical)western North *** leave-one-out cross-validation test during 1981–2022,the prediction model exhibited reasonable performance in predicting the interannual and interdecadal variations and trends of CHP *** temporal correlation coefficient(TCC)was 0.66 between the observations and *** the independent hindcast for 2013–2022,the TCC was as high as ***,coherent covariations were observed between the frequency and the amounts of CHP,with a TCC of 0.99 for 1981–*** three predictors show good performance in forecasting CHP amounts over SC,with a TCC of 0.68 between the predictions and observations in the cross-validation test during 1981–2022 and of 0.86 in the independent hindcasts during 2013–***,the predictors also showed good predictive skill for years with high CHP occurrence(e.g.,1998 and 2019).The predicted high-incidence areas of heavy precipitation days were highly consistent with observations,with a pattern correlation coefficient of 0.44(0.55)for 1998(2019).This study provides valuable insights to improve seasonal prediction of pre-summer CHP frequency in SC.

关键词： seasonal prediction clustered heavy precipitation South China interannual increment

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Roles of the Tropical Intra-Seasonal Oscillations in the Sub-Seasonal Prediction of the Long-Lasting Compound Heatwave over Southern China in 2010

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Journal of Tropical Meteorology 2025年第1期31卷 30-42页

作者： WANG Kai-qi ZHANG Tuan-tuan YANG Song LIN Wen-shi WANG Wei-wei WANG Teng ZHANG Cheng-yang DONG Shao-rou Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) and School of Atmospheric SciencesSun Yat-sen UniversityZhuhaiGuangdong 519082 China Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies Sun Yat-sen UniversityZhuhaiGuangdong 519082 China Meteorological Bureau of Shenzhen Municipality ShenzhenGuangdong 518040 China Shenzhen Key Laboratory of Severe Weather in South China ShenzhenGuangdong 518040 China State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 518048 China Climate Center Guangxi Meteorological ServiceNanning 530022 China Guangdong Climate Center Guangzhou 519082 China

Sub-seasonal prediction of regional compound heatwaves and their predictability sources remain *** this study,the underlying mechanisms for the long-lasting compound heatwave over Southern China during July 1–18,2010,and the major sources of its sub-seasonal prediction skill are *** results show that both the development and decay of this compound heatwave are mainly dominated by atmospheric processes(i.e.,adiabatic heating associated with anticyclonic circulation),whereas land-atmosphere coupling processes play an important role in sustaining the heatwave.A further analysis indicates that by inducing anomalous anticyclonic circulations over Southern China,the tropical intraseasonal oscillations with periods of 30–60 days and 10–30 days facilitate the occurrence and maintenance of the heatwave during its entire and second half periods,*** NCEP Climate Forecast System Version 2 shows a low skill in predicting the 2010 compound heatwave over Southern China when the lead time is longer than 2 pentads,which is largely attributed to the model’s bias in representing the intensity and phase of intra-seasonal oscillations.

关键词： compound heatwave intra-seasonal oscillations sub-seasonal prediction Southern China

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The Enhancing Effect of the East Asian Subtropical Westerly Jet on Summer Extreme High-Temperature Events over Central-Eastern China Since the Late 1990s

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Advances in Atmospheric sciences 2025年第3期42卷 453-466页

作者： Chujie GAO Yuyu NIU Gen LI Shanlei SUN Bo LU Chaofan LI Bei XU Jinglong HUANG Xiubao SUN College of Oceanography&Key Laboratory of Marine Hazards Forecasting Ministry of Natural ResourcesHohai UniversityNanjing 210098China Key Laboratory of Meteorological Disaster Ministry of Education(KLME)&Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science and TechnologyNanjing 210044China State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Laboratory for Climate Studies and CMA-NJU Joint Laboratory for Climate Prediction Studies National Climate CenterChina Meteorological AdministrationBeijing 100081China Xiong’an Institute of Meteorological Artificial Intellegence Xiong'an 071708China Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of the Chinese Academy of SciencesBeijing 100049China College of Intelligent Science and Control Engineering Jinling Institute of TechnologyNanjing 211169China

The increase in frequency and intensity of Extreme High-temperature Events(EHEs)over Central-Eastern China(CEC)in recent decades has severely impacted social development and *** observation and reanalysis datasets,this study explores the effect of the East Asian subtropical westerly jet stream(EAJ)on the CEC EHEs for the summers spanning 1979–*** its general relative location to the right side of the upper-level jet stream exit region,CEC would theoretically suffer more EHEs with a stronger and northwardly-shifted EAJ in summer due to the likelihood of abnormal subsidence induced by the ***,such an EAJ–EHE connection has been unstable over the past four decades but has displayed an evident interdecadal *** the late 1990s,the interannual variation of the EAJ was manifested mainly by its meridional displacement in the northeastern part of East Asia;thus,the atmospheric responses were essentially located to the east of CEC,exerting less of an influence on the CEC ***,since the late 1990s,the EAJ variation has featured an intensity change in its center over the northwest portion of the CEC,which has resulted in a westward shift in atmospheric responses to cover the CEC ***,the EAJ could potentially affect the summer CEC EHEs during 2000–*** findings offer support for an in-depth understanding of the formation mechanisms of extreme weather/climate events of this nature and thus provide a scientific reference for seasonal climate predictions.

关键词： summer extreme high-temperature events East Asian subtropical jet atmospheric circulation central-eastern China interdecadal change

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Study on Gas Production Characteristics of Thermally Aged Composite Insulator Core Rods Under Vacuum Conditions 1st

Study on Gas Production Characteristics of Thermally Aged Co...

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1st Electrical Artificial Intelligence Conference, EAIC 2024

作者： Xiaogang, Li Dandan, Zhang Ji, Wang Kexin, Shi Zhao, Chen Xiang, Cai Gaoli, Song Zhiyu, Wan Henan Jiuyu EPRI Electric Power Technology Co. Ltd. Zhengzhou450052 China School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China Ministry of Education Wuhan430074 China State Key Laboratory of Advanced Electromagnetic Technology Huazhong University of Science and Technology Wuhan430074 China Disaster Prevention and Reduction Center State Grid Hunan Electric Power Company Limited Changsha410000 China

ISBN: (纸本)9789819640669

Given the extensive utilization of composite insulators in electricity systems, the unresolved decay-like fragmentation of the composite insulator is of paramount importance in the preservation of the system’s functionality in daily life. The core rod’s gas production during the thermal aging process has been verified, which may result in the silicone rubber sheath deforming and potentially rupturing. This study has created an innovative vacuum thermal aging experiment platform that enables the conduct of thermal aging tests under vacuum conditions, thereby further elucidating the process of gas generation and its consequential impact. In addition, this platform is capable of accurately monitoring and recording the gas pressure value in the heating chamber in real time, as well as gathering the gases generated by the thermal degradation of composite insulator core rods. The experimental results elucidate the characteristics of gas production, with a particular emphasis on the thermal press. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.

关键词： Gas fuel manufacture

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