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Development of a high-resolution near-surface meteorological forcing dataset for the Third Pole region

Science China Earth Sciences 2025年第4期68卷 1274-1290页

作者： Yaozhi JIANG Wenjun TANG Kun YANG Jie HE Changkun SHAO Xu ZHOU Hui LU Yingying CHEN Xin LI Jiancheng SHI School of Resources and Environment University of Electronic Science and Technology of ChinaChengdu611731China Department of Earth System Science Ministry of Education Key Laboratory for Earth System ModelingInstitute for Global Change StudiesTsinghua UniversityBeijing100084China National Tibetan Plateau Data Center State Key Laboratory of Tibetan Plateau Earth SystemEnvironment and ResourcesInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing100101China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing100084China Tsinghua University(Department of Earth System Science)-Xi’an Institute of Surveying and Mapping Joint Research Center for Next-Generation Smart Mapping Beijing100084China National Space Science Center Chinese Academy of SciencesBeijing100190China

Recently,the Third Pole(TP)region has experienced rapid environmental *** data are essential for hydrometeorological and ecological applications but still have large uncertainties on the TP owing to the heterogeneous land surface,complex terrain,and sparse weather *** this study,a long-term(1979–2020)high-resolution(1/30°)meteorological forcing dataset for the TP(TPMFD)was developed,as a sister to the widely used China Meteorological Forcing Dataset(CMFD).The TPMFD comprises seven components necessary for driving land surface *** have previously contributed precipitation and downward shortwave radiation data for the TPMFD,and this study presents the development of five other components and focuses on validations for all ***,2-meter air temperature,2-meter specific humidity,10-meter wind speed,and surface air pressure were generated by combining the fifth-generation atmospheric reanalysis for European Center for Medium-Range Weather Forecasts(ERA5),a short-term high-resolution atmospheric simulation,and in situ observations,and the downward longwave radiation was calculated using semi-physical *** cross-validation and independent-validation demonstrated that most variables in the developed dataset outperformed those in widely used reanalysis datasets,including ERA5,ERA5-Land,and the Global Land Data Assimilation system(GLDAS).This dataset is expected to be beneficial for climate analyses and modeling applications of land-surface processes on the TP.

关键词： Meteorological data Third Pole High-resolution Data downscaling and merging

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Effects of Corona Discharge from the Grounding Tip on Charge Evolution of Wall Bushing

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IEEE Transactions on Power Delivery 2025年第3期40卷 1682-1693页

作者： Bai, Zheng Zhou, Yuanxiang Zhang, Yunxiao Huang, Xin Xie, Xiongjie Liu, Taiwei Tsinghua University State Key Laboratory of Power System Operation and Control Department of Electrical Engineering Beijing100084 China Electric Power Research Institute State Key Laboratory of Power Grid Environmental Protection Wuhan430204 China

Manufacturers consider that the grounding tip near the wall bushing flange is a potentially important factor in several sheath perforation accidents. Taking a ±100 kV true type SF6 gas-insulated bushing as a typical wall bushing, this paper tests the impact of the nearby grounding tip on the charge accumulation. Based on the experiment results, we propose the three-dimensional nonlinear conduction model to unravel the charge accumulation process and the three-dimensional corona ion migration model to clarify the corona process. It is concluded that the consumption of gas ions leads to the nonlinear charge relaxation process. When the corona of grounding tip incepts, numerous ions are generated, forming an "overcharge" phenomenon. The electric field at the insulator-sheds interface and the SF6-insulator interface increases compared to the normal condition, with non-uniform distribution along the circumferential direction. Material inhomogeneity amplifies electric field distortion and creates insulation weaknesses, making insulation aging more likely and potentially leading to a slowly developing electrical tree breakdown process. The length of the needle tip affects the duration of the corona effect;an excessively long needle tip can cause a sustained corona discharge. This research provides a foundation for bushing accidents analysis and operation reliability improvement. © 1986-2012 IEEE.

关键词： Bushings

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A Grey Wolf Optimizer Variant with Weighted-leader Strategy 24

A Grey Wolf Optimizer Variant with Weighted-leader Strategy

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3rd International Conference on Signal Processing, Computer Networks and Communications, SPCNC 2024

作者： Liang, Yajun Yan, Su Ma, Qian Huang, Shunlun Liu, Xin China Aerodynamics Research & Development Center Sichuan Mianyang China Science and Technology on Complex Aviation Systems Simulation Laboratory Beijing China State Key Laboratory of Air Traffic Management System Beijing China Beijing Aviation Meteorological Institute Beijing China

ISBN: (纸本)9798400710834

To enhance the convergence capability of grey wolf optimizer (GWO), this research investigates an evolved GWO using weighted-leader strategy (WLS), namely WLSGWO. The key issue of WLS is realizing the adaptive adjustment of position weighting according to the control parameters, thus well overcoming the drawback of premature convergence in the basic GWO. The newly developed method’s performance is assessed through experiments conducted on a standardized test suite. Additionally, comparisons are made by utilizing GWO alongside other advanced optimization techniques. The results of non-parametric studies validate the outperformance of the WLSGWO, thus proving the efficiency of the proposed strategy. © 2024 Copyright held by the owner/author(s).

关键词： Swarm intelligence

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Study on the Looseness Caused by Local Slip and Load Bearing Capacity of Threaded Connections Under Transverse Cyclic Loading

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Journal of Tribology 2025年第9期147卷 091103页

作者： Sun, Yu Qin, Wenjie Zhao, Zhenlong Ba, Mingsen School of Mechanical Engineering Beijing Institute of Technology Beijing100081 China State Key Laboratory of Engine and Powertrain System Weifang261000 China Weichai Power Cooperation Limited Shandong Weifang261000 China

Under transverse cyclic loading, slip will occur on the contact surfaces in a threaded connection, causing rotational loosening of the connection. It is necessary to detect and analyze the loosening behavior of threaded connections caused by slippage. In this article, a self-driven sensor based on the principles of triboelectric nanogenerators (TENGs) was used to monitor the rotational looseness of a tight threaded stud connection subjected to transverse cyclic loads. The finite element simulation was conducted on the contact slip in the stud connection in the experiment under transverse cyclic loading to reveal the loosening phenomenon of threaded connections caused by local slip propagation with the increase of load cycles. Under a certain preload, only when the amplitude of the lateral cyclic load does not exceed a critical value, will the thread contact surface not experience local slip propagation. Therefore, a local slip influence coefficient was proposed for calculating the critical transverse cyclic load amplitude, and its influencing factors were discussed. This study provides a new approach to the anti-loosening design of threaded connections. Copyright © 2025 by ASME.

关键词： Cyclic loads

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Geomorphon-based classification of multiscale lunar landform

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Journal of Applied Remote Sensing 2025年第1期19卷

作者： Li, Junjiao Wang, Jiao Shi, Yijian Cheng, Weiming China University of Geosciences School of Information and Engineering Beijing China Chinese Academy of Sciences Institute of Geographic Sciences and Natural Resources Research State Key Laboratory of Resources and Environmental Information System Beijing China

Landform classification can help us better understand the structure, composition, and evolution of the lunar surface, which is of great value for exploration engineering design and task execution. Currently, research on micro-lunar landform elements is limited due to the intricate morphology influenced by internal forces such as volcanic activities and tectonic processes, and external forces including impacts and space weathering. These forces create a wide range of morphological variations, making it challenging to identify and classify micro-lunar landforms using traditional methods. To address these challenges, this study proposes a scale-adaptive approach for effectively classifying diverse micro-lunar landforms. An algorithm based on geomorphons is introduced, which defines local ternary patterns by optimizing topographic parameters and classifies micro-level landform elements accordingly. The classification process aggregates lunar geomorphons using relief amplitude and slope, enabling the identification of multi-scale landforms across extensive regions. The proposed method achieves high classification performance, with an overall accuracy (OA) of 82.46% and a kappa coefficient (K) of 0.75. By integrating multi-scale units, a comprehensive lunar landform classification system is constructed, facilitating the efficient extraction and analysis of landform elements. Furthermore, the classified lunar landforms provide multi-scale landform units for more detailed analyses of lunar geomorphology and geology. © 2025 Society of Photo-Optical Instrumentation Engineers (SPIE).

关键词： Geomorphology

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Fault-induced gear meshing modulation sideband extraction and evaluation for fault diagnosis of planetary gearboxes

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Science China(Technological Sciences) 2025年第1期68卷 335-351页

作者： Peng ZHOU Xiaoluo YU Yang YANG Qingbo HE Zhike PENG State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China School of Mechanical Engineering Ningxia UniversityYinchuan 750021China Science and Technology on Vehicle Transmission Laboratory China North Vehicle InstituteBeijing 100072China

Gearboxes,known for their compact size and stable transmission capability,are widely used as power transmission structures in various types of mechanical equipment,such as wind turbines,helicopters,and special ***,due to harsh and non-stationary working conditions,gear surfaces often deteriorate,leading to faults such as wear,pitting,and ***,it is vital to monitor the working status of gearboxes and diagnose gear faults as early as *** faults can induce characteristic modulation effects near the gear meshing frequency(GMF),resulting in the appearance of faultinduced sidebands in a vibration *** of these sidebands allows for the diagnosis of gear faults in a ***,when faced with a planetary gearbox having a complex configuration,strong background noise and additional faultunrelated sidebands can interfere with fault-induced sidebands,making accurate diagnosis *** address these challenging issues,this paper proposes a novel fault-induced gear meshing modulation sideband extraction *** the process,the sidebands directly related to the gear fault near the GMF are first identified and then extracted by a variational harmonic mode decomposition(VHMD)***,a fault-related gear meshing modulation component(GMMC)can be accurately reconstructed by summing up the extracted fault-induced *** the GMMC,the gear fault severity can be assessed by evaluating its amplitude modulation(AM)*** superior performance of the proposed method is finally demonstrated by experimental data.

关键词： planetary gearbox gear meshing frequency modulation sideband signal decomposition fault diagnosis

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Design Considerations on Voltage and Current Transfer Ratio of High-Frequency Transformers

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CSEE Journal of Power and Energy systems 2025年第1期11卷 447-457页

作者： Chen Liu Lei Qi Xiang Cui China Electric Power Planning&Engineering Institute Beijing100120China State Key Laboratory for Alternate Electrical Power System Renewable Energy Sources(North China Electric Power University)Beijing102206China

A high frequency(HF)transformer is key equipment for dc-dc converter to achieve galvanic isolation and voltage *** operating frequency increases,voltage and current transfer ratio of HF transformer may significantly deviate from the turn ratio due to parasitic effects,failing to transfer expected voltage and current from the primary side to the secondary *** this paper,design considerations on voltage and current transfer ratio of the HF transformer are investigated to obtain expected transfer *** revealing parasitic effects on transfer characteristic(TC)of the HF transformer with load,deviation between voltage/current transfer ratio and turn ratio is correlated with the ratio of voltage/current TC resonant frequency and operating ***,constraints for parasitic parameters to obtain expected transfer ratio are proposed,and practical measures to achieve improvements in transformer design are discussed.A 20kHz HF transformer prototype is used as an application,by which evaluations on deviation of voltage/current transfer ratio and turn ratio are verified,and voltage/current transfer performance of the prototype are effectively improved by optimal design based on the proposed principles.

关键词： Capacitance transfer functions transformers

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Adaptive cyclic gradient methods with interpolation

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Computational Optimization and Applications 2025年 1-25页

作者： Xie, Yixin Sun, Cong Yuan, Ya-Xiang Beijing100876 China Ministry of Education Beijing100876 China State Key Laboratory of Scientific/Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing100190 China

Gradient method is an important method for solving large scale problems. In this paper, a new gradient method framework for unconstrained optimization problem is proposed, where the stepsize is updated in a cyclic way. The Cauchy step is approximated by the quadratic interpolation. And the cycle for stepsize update is adjusted adaptively. Combining with the adaptive nonmonotone line search technique, we prove the global convergence of the proposed method. Furthermore, its sublinear convergence rate for convex problems and R-linear convergence rate for problems with quadratic functional growth property are analyzed. Numerical results show that our proposed algorithm enjoys good performances in terms of both computational cost and obtained function values. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.

关键词： Interpolation

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A Novel Model for Describing Rail Weld Irregularities and Predicting Wheel-Rail Forces Using a Machine Learning Approach

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Computer Modeling in engineering & Sciences 2025年第1期142卷 555-577页

作者： Linlin Sun Zihui Wang Shukun Cui Ziquan Yan Weiping Hu Qingchun Meng State Key Laboratory of High-Speed Railway Track System China Academy of Railway Sciences Corporation LimitedBeijing100081China Railway Engineering Research Institute China Academy of Railway Sciences Corporation LimitedBeijing100081China School of Aeronautic Science and Engineering Beihang UniversityBeijing100191China

Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed *** can cause significant wheel-rail dynamic interactions,leading to wheel-rail noise,component damage,and *** researchers have employed the vehicle-track interaction dynamic model to study the dynamic interactions between wheel and rail induced by rail weld geometry ***,the cosine wave model used to simulate rail weld irregularities mainly focuses on the maximum value and neglects the geometric *** this study,novel theoretical models were developed for three categories of rail weld irregularities,based on measurements of the high-speed railway from beijing to *** vertical dynamic forces in the time and frequency domains were compared under different running *** forces generated by the rail weld irregularities that were measured and modeled,respectively,were compared to validate the accuracy of the proposed ***,based on the numerical study,the impact force due to rail weld irrregularity is modeled using an Artificial Neural Network(ANN),and the optimum combination of parameters for this model is *** results showed that the proposed model provided a more accurate wheel/rail dynamic evaluation caused by rail weld irregularities than that established in the *** ANN model used in this paper can effectively predict the impact force due to rail weld irrregularity while reducing the computation time.

关键词： Rail weld irregularity high-speed railway vehicle-track coupled dynamics wheel/rail dynamic vertical force artificial neural networks

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Comparison of gap-filling methods for generating landsat-like land surface temperatures under all-weather conditions

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ISPRS Journal of Photogrammetry and Remote Sensing 2025年 225卷 113-130页

作者： Guo, Jiali Quan, Jinling Zhan, Wenfeng Wen, Zhongguan State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources Research CAS Beijing100101 China College of Resources and Environment University of Chinese Academy of Sciences Beijing100190 China Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology International Institute for Earth System Science Nanjing University Jiangsu Nanjing210046 China College of Environmental Sciences and Engineering Peking University Beijing100871 China

Thermal infrared remote sensors provide cost-effective and widespread land surface temperatures (LSTs) but often with spatiotemporal gaps due to discrete sampling and synoptic disturbance, greatly limiting their reliability and application. Current gap-filling methods have been primarily developed and validated for medium- to low-resolution LSTs;however, with rising demand for spatiotemporally continuous, high-resolution (tens of meters like Landsat) LSTs across disciplines, there is an urgent need to assess these methods’ applicability and uncertainty at higher spatial resolutions under a unified framework. In this study, we apply eight typical and hybrid methods, including temporal interpolation, spatiotemporal interpolation, weight-based fusion, learning-based fusion, and four standard annual temperature cycle (ATC)-based hybrid reconstructions, to fill gaps in irregularly spaced Landsat series over Weishan, Huairou, and Yulin, China. These sites represent cropland in a sub-humid plain, forest in a sub-humid mountain region, and grassland in the semi-arid Loess Plateau. We evaluate their performance in terms of spatiotemporal pattern, statistical accuracy, sensitivity to input data quality and distribution, and adaptability to different synoptic and surface conditions based on cloudy Landsat data and in-situ measurements. Results reveal that the enhanced ATC (EATC) method is optimal among these methods, capturing all-weather spatiotemporal dynamics at the Landsat scale with superior accuracy and robustness under various input, cloud, and ground conditions. In addition, the ATC-based hybrid methods do not necessarily improve the statistical accuracy over their respective typical ones. This comprehensive evaluation provides valuable insights into the selection of appropriate gap-filling methods for generating Landsat-like LSTs under all-weather conditions and highlights the need for further advancements especially in addressing abrupt changes in land cover types an

关键词： Surface stress

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