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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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High welding strength of fused silica and stainless steel by picosecond laser with large defocus

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Ceramics International 2025年第13期51卷 18154-18165页

作者： Shen, Hong Yang, Zhaoyang Tian, Chenyun Ren, Haodong Wei, Xingyu School of Mechanical Engineering Shanghai Jiao Tong University Shanghai200240 China State Key Laboratory of Mechanical System and Vibration Shanghai200240 China

Ultrafast laser technology has markedly improved the welding efficiency and quality of glass and metals, yet it is still challenging to achieve a welding strength comparable to the tensile strength of the glass. In this study, a picosecond laser with large defocus amounts was used to weld fused silica and stainless steel, and a high strength was achieved with a defocus amount of −800 μm and a pulse energy of 40 μJ. This welding strength reached 64 % of the tensile strength of fused silica (30.73 MPa). A perspective along the weld seam was employed to analyze the weld seam morphology, coupled with the energy density at the interface of the glass and metal, to provide a deeper understanding of the evolution of the molten pool during the welding process. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Picosecond lasers

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Comparative study on vibro-acoustic properties of sandwich shells containing functionally-graded porous materials in a thermal environment

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Applied Mathematics and Mechanics(English Edition) 2025年第5期46卷 947-964页

作者： Xinbiao XIAO Xinte WANG Jian HAN Yuanpeng HE State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong UniversityChengdu 611756China School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 611756China

The dynamics of functionally-graded(FG) sandwich shells with varied pore distributions in thermal environments is investigated,focusing on their free vibration behaviors and sound transmission loss(STL) *** effective material parameters are calculated by integrating the graded distribution through three distinct pore distribution *** dynamic governing equations are derived by means of the first-order shear deformation theory,guided by Hamilton's *** solutions for the natural frequency and acoustic transmission loss factor are obtained from the shell's free vibration general solution and the acoustic displacement function,respectively.A detailed numerical analysis is conducted to assess the impacts of the structural and geometric parameters,as well as the ambient temperature,on the vibro-acoustic *** results indicate that vibro-acoustic coupling is most significant in shells with a symmetric non-uniform pore distribution,and the resonance frequency shifts towards lower frequencies as the power-law index *** findings offer valuable insights for enhancing the design of materials aimed at vibration damping and acoustic management.

关键词： functionally-graded(FG)porous material cylindrical shell thermal environment sound transmission loss(STL) vibro-acoustic coupling

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Differential Protection Method of Stator and Rotor Current with Different Frequencies for Variable Speed Pumped Storage Units

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IEEE Transactions on Power Delivery 2025年第3期40卷 1531-1539页

作者： Qiao, Jian Yu, Haoyuan Wang, Yikai Wang, Kai Yin, Xin Chen, Linxu State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources Baoding China Wuhan University of Technology School of Automation Wuhan China

Rotor winding short-circuit fault (RWSF) is a common fault type of variable speed pumped storage unit (VSPSU). However, the RWSF protection in engineering typically depends on the integrated over-current protection of the AC excitation system, which has poor sensitivity to reflect the RWSF and makes it difficult to fulfill the requirements of safe operation of VSPSU. Inspired by transformer differential protection, a different frequency differential protection method using both stator and rotor phase currents is proposed. In terms of working principle and structure, the stator and rotor windings of the VSPSU are similar to the primary and secondary windings of the transformer, and there are conditions for differential protection. Furthermore, the Clark transformation is used to analyze the characteristic changes of stator and rotor currents after the RWSF. On this basis, the criterion form of different frequency differential protection is constructed based on the trapezoidal area method. Finally, the effectiveness of the proposed method is verified by dynamic simulation experiments. © 1986-2012 IEEE.

关键词： Stators

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Development of a high-performance bend-actuated piezoelectric tip/tilt stage with low power and simple operation

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Science china Technological Sciences 2025年第6期68卷 1-12页

作者： Guan, Jinghan Zhang, Shijing Deng, Jie Chen, Weishan Liu, Junkao Liu, Yingxiang State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

Piezoelectric tip/tilt stages (PZT stages), which precisely and quickly control laser beam deflection, are widely used in laser communications. Most are driven by piezoelectric stack actuators (PSAs) and have high capacitance and power consumption. The negative voltage causes irreversible damage to PSAs. Therefore, negative voltage operation needs to be prohibited, which complicates manipulating the bidirectional deflection of the mirror. However, the aerospace field places higher requirements on power consumption and ease of operation, which makes the PZT stage require reduced power consumption and simple operation. This paper presents a high-performance bend-actuated PZT stage, which uses ceramic plates for driving, with a capacitance of only 26.4 nF/axis and a power of only 27 mW (at operating conditions of 1 mrad and 100 Hz). The sandwich structure allows for bi-directional voltage, which makes the operation easier. Two channels control two degrees of freedom (DOFs). A theoretical mod el suitable for bend-actuated structures is proposed. It is used to calculate the deflection angle and resonance frequency, and its validity is verified by finite element analysis. Experimental results show that it has a deflection angle of ±2.97 mrad (x-axis), ±3.24 mrad (y-axis) at 600 V_p-p, an unloaded first-order resonance frequency of 1728 Hz, and a quasi-static hysteresis of only 7.5%, which is less than that of PSAs (>10%). With the constructed laser beam deflection system, a circular trajectory is realized, which has the potential for beam steering. © Science china Press 2025.

关键词： bending piezoelectric actuator laser beam deflection piezoelectric ceramic pseudo-rigid body model tip/tilt stage

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High-Order Fully Actuated system Approach-Based Attitude Stabilization for Underactuated Rigid and Flexible Spacecraft

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IEEE Transactions on Automation Science and Engineering 2025年 22卷 15094-15105页

作者： Jia, Shixiang Qiu, Jianbin Wang, Tong Harbin Institute of Technology State Key Laboratory of Robotics and Systems Harbin150001 China Research Institute of Intelligent Control and Systems Harbin Institute of Technology Harbin150080 China

This paper addresses the challenge of attitude stabilization for a class of underactuated rigid and flexible spacecrafts by utilizing only two control inputs. The attitude stabilization problem of underactuated spacecraft poses substantial challenges to the High-Order Fully Actuated (HOFA) system approach, due to the fact that it heavily depends on the full actuation characteristics of the system. To circumvent the aforementioned limitation, we first derive a HOFA system for underactuated rigid spacecraft using homogeneity theory and averaged system approach. Subsequently, we design a controller based on the HOFA system approach, which yields a linear closed-loop system. This methodology is then extended to address the simplified attitude stabilization problem of underactuated flexible spacecraft. By utilizing the HOFA system approach in tandem with an observer for estimating modal variables, we propose a control strategy that not only stabilizes the attitude but also actively suppresses elastic vibration. The performance of the proposed control schemes are demonstrated through simulation studies. © 2004-2012 IEEE.

关键词： Satellites

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An Untethered Bionic Soft Robotic Vehicle With Magnetic Actuation and Control for Multi-Scenario Applications

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IEEE robotics and Automation Letters 2025年第6期10卷 5289-5296页

作者： Yang, Wenguang Qiao, Zezheng Gao, Zhizheng Yu, Haibo Yantai University School of Electromechanical and Automotive Engineering Yantai264005 China Chinese Academy of Sciences State Key Laboratory of Robotics Shenyang Institute of Automation Shenyang110016 China

In this study, a bionic soft robotic vehicle is designed with overall dimensions of 22.7 mm in length and 22 mm in width and weighs just 1.69 g. The robotic vehicle can realize precise motion control through a rotating magnetic field generated by Helmholtz coils. In the rotating magnetic field environment, by changing the parameters of the input current waveform, the vehicle can perform a variety of modes of motion, such as forward, backward, steering, and more. Furthermore, the robotic vehicle exhibits excellent motion performance. It is capable of moving stably on a variety of surfaces, including glass, wooden board, frosted board, and sandy soil, and can even successfully climb over obstacles as high as 30°. In particular, it can climb over a 20° barrier at 11.87 mm/s when loaded with three times its own weight (5 g). At the functional level, the robotic vehicle showcases its capabilities in obstacle clearance, path planning, and detection, underscoring its potential for performing complex tasks. © 2016 IEEE.

关键词： Motion planning

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Introducing deep trap states for high dielectric strength of aramid-based composite films

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High Voltage 2025年第1期10卷 197-207页

作者： Wenqi Zhang Qibin Wang Guangyi Shen Sidi Fan Xiaozhou Fan Rui Yang Yunpeng Liu Xiang Yu Fangcheng Lv School of Electrical and Electronic Engineering North China Electric Power UniversityBeijingChina Hebei Provincial Key Laboratory of Power Transmission Equipment Security Defense North China Electric Power UniversityBaodingChina State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijingChina

Aramid nanofiber(ANF)-based composites have drawn tremendous interest in high-voltage electrical systems due to their superior insulation strength,thermal stability,and mechanical ***,the filler agglomeration and interface compatibility have retarded further improvement of the dielectric ***,the nano-titanium dioxide(TiO_(2))particles treated by aminopropyl triethoxysilane(APTES)serve as the inorganic fillers,which are doped in the ANF to prepare the composite nano-paper via the blade coating *** electrostatic interaction between the ANF and fillers highly promotes their uniform *** to the pure ANF paper,the composite paper has a denser structure with reduced pores and defects,which significantly improves its dielectric performance with inhibited partial discharge *** a filler loading of 3 wt%(mass fraction),the breakdown strength is increased by 70.5%to a maximum value of 358.1 kV/mm,while the bulk conductivity is minimised to 5.2×10^(-17)S/m,representing an 88.1%*** analysing the energy band structure of each component,energy barriers at the interface for electrons(1.48 eV)and holes(0.40 eV)are *** values indicate deepened trap energy levels,which greatly strengthen the carrier trapping effect for improved dielectric performance.

关键词： composite dielectric strength

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Gradient maturation experiment on hairs implies taphonomic changes in fossil hairs

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Science china Earth Sciences 2025年第1期68卷 62-73页

作者： Xin LI Yibo ZHOU Tao ZHAO Xingjian HE Yanhong PAN State Key Laboratory for Mineral Deposits Research Center for Critical Earth Material CyclingCentre for Research and Education on Biological Evolution and Environment and Frontiers ScienceSchool of Earth Sciences and EngineeringNanjing UniversityNanjing210023China Institute of Palaeontology Yunnan Key Laboratory of Earth System ScienceYunnan Key Laboratory for PalaeobiologyYunnan UniversityKunming650500China

Mammalian hair,as a key feature related to endothermy,physical protection,and camouflage,has a long geohistorical record that dates back even to the ***,the limited information on the taphonomy of hair hinders the understanding of its evolutionary significance in deep *** address this,we conducted taphonomic experiments to simulate the transformation process of black *** changes in the morphological structure,microscopic characteristics,and chemical composition of hair during the simulated fossilization process were documented by scanning electron microscopy,Fourier transform infrared(FTIR)spectroscopy,and Raman *** results revealed that damage to the morphology of hair began at a mild temperature(150–175℃),and hair transformed into a fluid-like mass at a relatively high temperature(200℃).In addition,the morphological structure of melanosomes had relatively greater preservation potential than keratins did,and the microscopic features of melanosomes were persistently *** Raman and FTIR spectra indicated that the characteristic melanin and keratin peaks changed as the temperature *** the chemical signals were not lost completely,the variations in the characteristic amide bands in the FTIR spectra indicate that the keratins severely degraded at high temperatures(>200℃),whereas the characteristic melanin bands in the Raman spectra suggested that melanin signals were still recognizable,even at high temperatures(>200℃).These results were confirmed by principal component analysis(PCA)and principal component analysis linear discriminant analysis(PCA–LDA).In addition,the Raman signals of all the samples in the simulated experiments were distinguished from the signals of common geological carbonaceous materials(humic acid),which suggested that Raman spectroscopy can be used to detect melanin in fossils.

关键词： Mammalian hair Melanin Keratin Fossilization Experimental taphonomy

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A comparison on the effects of coal fines and sand fouling on the shear behaviors of railway ballast using large scale direct shear tests

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Journal of Traffic and Transportation Engineering(English Edition) 2025年第1期12卷 52-67页

作者： Xu Zhang Shunying Ji Yang Feng Yongjun Li Chunfa Zhao School of Civil and Transportation Engineering Guangdong University of TechnologyGuangzhou 510006China State Key Laboratory of Rail Transit Vehicle System Southwest jiaotong UniversityChengdu 610031China State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDalian University of TechnologyDalian 116024China

Railway ballast is easily contaminated by different fouling material and the fouled ballast always causes the deterioration of railway *** previous studies focused on the effect of a certain kind of fouling material on ballast performance,but few studies compared the influence of different fouling *** paper presents a series of direct shear tests on the clean ballast and the fouled ballast mixed with coal fines or sand to understand the effects of different fouling material.A unified empirical model is proposed to well capture the shear stress-displacement responses of the clean and fouled *** equations are also obtained to characterize the variation of the nonlinear shear strength envelope of the fouled ballast with the fouling *** on these equations,a simple method is proposed to predict the shear strength of the fouled ballast using the shear test results of clean *** measured results demonstrate significant differences between the effects of coal fines and sand on the shear behaviors of ballast,to which particular attention should be paid in order to take targeted maintenance measures for the fouled *** mechanisms for the different effects of coal fines and sand are also analyzed to understand the roles that various fouling material plays in the fouled ballast.

关键词： Railway ballast Fouled ballast Shear strength Direct shear test Contamination

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