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Thermal stability of permafrost under U-shaped crushed rock embankment of the Qinghai-Tibet Railway

Advances in Climate Change Research 2024年第1期15卷 158-169页

作者： Kun-Ming XU Guan-li jiANG ji CHEN Qing-Bai wu State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Beiluhe Observation Station of Frozen Soil Environment and Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000China

The U-shaped crushed rock embankment(UCRE),of which widely utilized in the permafrost regions along the Qinghai-Tibet Railway,has the capability to rapidly reduce the ground temperature of the underlying ***,there remains uncertainty regarding the adaptation of UCRE to climate change and its long-term cooling *** study focuses on nine UCRE monitoring sites along the Qinghai-Tibet Railway to analyze the dynamic variations of the ground temperature underlying permafrost from 2006 to *** efficiency of UCRE in stabilizing permafrost temperature in different permafrost zones is evaluated by considering the permafrost table,ground temperature,and MAGT,as well as the temperature difference between the top and bottom of the crushed rock layer and the ground temperature variation index(GTVI).The results show that UCRE is suitable for application in extremely unstable warm permafrost regions where the MAGT is higher than-0.5℃.Moreover,UCRE effectively diminishes the disparity in permafrost thermal stability between the sunny and shaded shoulders of the *** short-term and long-term effect of cooling permafrost is experiencing a change related with permafrost ***,in stable cold permafrost regions with MAGT lower than-1.5℃,the long-term cooling effect of UCRE on permafrost seems to gradually di-minishes,but UCRE continues to fulfill the role of stabilizing the underlying permafrost thermal state over the *** results show that UCRE can quickly restore and stabilize the thermal state of permafrost in the early stages of construction,and adapt to the influence of future climate *** findings provide important guidance for understanding the variations of permafrost thermal stability beneath the embankment in permafrost regions,as well as for improving the embankment stability and operational safety of the Qinghai-Tibet Railway.

关键词： Qinghai-Tibet Railway U-shaped crushed rock embankment Climate change Permafrost zone Ground temperature variation index Long-term coolingrole

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Electrical discharge and arc milling with automatic tracking of optimal flushing direction:A novel high-efficiency compound machining method

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Chinese Journal of Aeronautics 2024年第3期37卷 351-364页

作者： Xinlei wu Yonghong liU Pengxin ZHANG liang QI Dege li Chi MA Renjie ji College of Mechanical and Electronic Engineering China University of Petroleum(East China)Qingdao 266580China School of Mechanical and Power Engineering Nanjing Tech UniversityNanjing 211816China

The arc milling method has the advantages of high machining efficiency and low cost and is independent of the strength and hardness of machined ***,frequent electrode back-offs and the risk of workpiece burning may occur if erosion products are not removed *** this study,it was found that the flushing method of the working medium had a significant impact on the machining performance of arc *** on this,a novel highefficiency compound machining method of electrical discharge and arc milling with automatic tracking of the optimal flushing direction was *** automatic tracking optimizer for external working medium injection was designed to determine the optimal external flushing direction according to the feed *** influence of flushing methods,working mediums,and machining parameters on the machining efficiency,tool electrode wear rate,machining error,and surface integrity of titanium alloys were *** results indicated that better machining performance and environmental friendliness were achieved using the compound flushing method of outer compressed air and inner deionized ***,the automatic tracking flushing method in the opposite direction of the feed direction showed superior results compared to other *** material removal rate with the opposite direction injection could be increased up to 1.62 times that of the same direction,and the relative electrode wear rate could be reduced by 14.76%.This novel method has broad application prospects for machining parts with difficult-to-cut materials in aerospace and military industries.

关键词： Arc milling Dielectric Difficult-to-cut materials Electric discharge machining Erosion Material removal rate

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Enhanced thermoelectric and mechanical properties of Bi_(0.5)Sb_(1.5)Te_(3) alloy with dispersed yttrium oxide ceramic nanoparticles

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Rare Metals 2024年第4期43卷 1758-1768页

作者： Cun-Cheng li Ming-Wei Zhang ji-wu Xin Lei Wei Wen-Yu Zhao School of Materials Science and Engineering Shandong University of TechnologyZibo255000China School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore639798Singapore State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan430070China

Reducing thermal conductivity while avoiding adverse interfacial reactions during sintering is crucial for improving the thermoelectric performance of Bi_(2)Te_(3)based *** ceramic nanoparticles are good candidates for achieving this *** this study,we designed and prepared a series of p-type Bi_(0.5)Sb_(1.5)Te_(3)nanocomposites decorated with Y_(2)O_(3)ceramic nanoparticles via ball-milling dispersion and spark-plasma *** to the chemical stability of the ceramics,no traces of atomic doping or interfacial reactions were *** measurements revealed that the Y_(2)O_(3)nanoparticles distributed along the grain boundaries acted as energy-dependent carrier-filtering centers to improve the scattering parameter and Seebeck coefficient,contributing to the elevated power factor even with a decreased electrical ***,the incorporated Y_(2)O_(3)nanoparticles and various defect structures they induced effectively strengthened the phonon scattering and suppressed the lattice thermal ***,a peak figure of merit(ZT)of 1.23 at 313 K was achieved for 0.4%Y_(2)O_(3)/Bi_(0.5)Sb_(1.5)Te_(3),which is 13%higher than that of the *** addition,the Vickers hardness of the composite material was 35%higher than that of the *** study demonstrates the effectiveness of ceramic nanoparticles in synergistic ally improving the thermoelectric and mechanical properties,which may be further extended to other thermoelectric systems.

关键词： Bi_(0.5)Sb_(1.5)Te_3 alloy Y_(2)O_(3) ceramic nanoparticles Microstructures Thermoelectric performance Mechanical properties

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Unknown system dynamics estimator-based impedance control for lower limb exoskeleton with enhanced performance

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Control Theory and Technology 2024年第1期22卷 56-68页

作者： Wenhao Zhang Peng Song Mingying wu Qiang li Xinmin Mo Pingxin ji Northwest Institute of Mechanical and Electrical Engineering Xianyang712099ShaanxiChina Xi’an Exo-Smart Dynamics Technology Ltd. Xi’an712046ShaanxiChina Department of Mechanical and Engineering Beijing Institute of TechnologyBeijing100081China

In this article, an unknown system dynamics estimator-based impedance control method is proposed for the lower limb exoskeleton to stimulate the tracking flexibility with the terminal target position when suffering parametric inaccuracies and unexpected disturbances. To reinforce the robust performance, via constructing the filtering operation-based dynamic relation, i.e., invariant manifold, the unknown system dynamics estimators are employed to maintain the accurate perturbation identification in both the hip and knee subsystem. Besides, a funnel control technique is designed to govern the convergence process within a minor overshoot and a higher steady-state precision. Meanwhile, an interactive complaint result can be obtained with the aid of the impedance control, where the prescribed terminal trajectory can be adjusted into the interaction variable-based target position by the force–position mapping, revealing the dynamic influence between the impedance coefficient (stiffness and damping) and the adjusted position magnitude. A sufficient stability analysis verifies the ultimately uniformly bounded results of all the error signals, and even the angle errors can be regulated within the predefined funnel boundary in the whole convergence. Finally, some simulations are provided to demonstrate the validity and superiority including the enhanced interaction flexibility and robustness.

关键词： Trajectory tracking Invariant manifold Funnel control Impedance control Lower limb exoskeleton

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Interfaces engineering of heterostructured Ni Co P/Ni Fe LDH@CC for attaining high catalytic activity in long-lasting rechargeable Zn–air batteries

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Rare Metals 2024年第10期43卷 4961-4972页

作者： Xiao-lin Hu ji-Chuan Fan Xiang li Zhen-Kun wu Yuan-Yi li Chao-He Xu School of Science Chongqing Key Laboratory of New Energy Storage Materials and DevicesChongqing University of Technology jiNSHAN Science&Technology (Group) Co. Ltd. National Engineering Research Center for Magnesium Alloys Chongqing University College of Aerospace Engineering Chongqing University

Zinc-air batteries (ZABs) offer tremendous potential in various industries and daily life due to their excellent energy density,safety and ***,the practical application of ZABs has been severely hindered by challenges such as high low round-trip efficiencies and overpotential,primarily attributed to the inherent sluggish kinetics in the oxygen evolution reaction(OER) of air *** address these issues effectively and economically,heterojunction engineering accompanied by interfacial chemistry emerges as an ideal approach to designing efficient OER ***,a novel heterogeneous interfacial chemical structure,namely NiCoP/NiFe LDH (layered double hydroxide),needle-like NiCoP and NiFe LDH nanosheets were assembled from cores and shells,***,the NiCoP/NiFe LDH-based ZABs have an exceptionally long cycle life of 238 h,far superior to Pt/C+Ir/C batteries (～97 h).Theoretical calculations and experimental results demonstrate that NiCoP/NiFe LDH possesses tunable interfacial chemistry,demonstrating significant electronic,coordination,geometric and synergistic *** enhancements dramatically improve the active site density,intrinsic activity and electrochemical durability of the *** summary,this work provides a solid foundation for the development of costeffective OER electrocatalysts for electrochemical energy devices.

关键词： Coupling effects Interface catalysis Oxygen evolution reaction Theoretical simulation Zinc–air batteries

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Progress of Radiation Belt Exploration by a Constellation of Small Satellites TGCSS/SGRB, COSPAR

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空间科学学报 2024年第4期44卷 746-750页

作者： wu ji YANG Xiaochao DAI Lei DENG li National Space Science Center Chinese Academy of SciencesBeijing 100190

A COnstellation of Radiation BElt Survey(CORBES)program is proposed by the Sub-Group on Radiation Belt(SGRB)of TGCSS,*** address the open qustions about the dynamics of the Earth’s radiation belt,CORBES mission would use a constellation of small/CubeSats to take an ultra-fast survey of the Earth’s radiation *** concept,science objectives and preliminary technical design of CORBES are *** mission is an international multilateral cooperation mission coordinated by *** SGRB Science Activities and COSPAR HQs Coordinate Activities on CORBES are summaried.

关键词： Radiation belts Ultra-fast survey Constellation

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Multiple factors influencing high-purity indium electrolytic refining

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Chinese Journal of Chemical Engineering 2024年第7期71卷 148-160页

作者： Hong-Qiang Fan Fei li Hong-Xing Zheng wu-ji Pan Mei-Zhen wu Yashar Behnamian Ju-Bo Peng Dong-Hai lin State Key Laboratory of Advanced Special Steel&School of Materials Science and Engineering Shanghai UniversityShanghai 200444China Shanghai Engineering Research Center for Integrated Circuits and Advanced Display Materials Shanghai UniversityShanghai 200444China Research&Development Center Yunnan Tin Group(Holding)Limited CompanyKunming 650032China Department of Chemical and Materials Engineering University of AlbertaEdmonton T6G 2V4AlbertaCanada School of Energy and Materials Shanghai Key Laboratory of Engineering Materials Application and EvaluationShanghai Polytechnic UniversityShanghai 201209China

The effects of various contaminants in the electrolytic refinement of indium were investigated using a glow discharge mass spectrometer(GDMS).The effects of several factors such as the indium ion(In3+)concentration,the sodium chloride(NaCl)concentration,the current density,the gelatin concentration,the pH,and the electrode distance,were *** variations in impurity levels concerning gelatin concentration were *** the gelatin and In3+concentration were moderately positively correlated with the Pb *** Sb concentration was associated positively with the NaCl concentration,while the Ti concentration had an adverse correlation with the NaCl *** Bi element content was positively linked to the electrode *** the current density increased,Cu,Pb,and Bi impurities initially rose and then eventually ***,a critical current density of 45 A·m^(-2) was identified in this behavior.

关键词： High-purity indium Electrolysis Multiple factors Electrochemistry Purification

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Anisotropic Mechanical Response of Nacre to Heat Treatment Under Indentation:Effect of Structural Orientation

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Journal of Bionic Engineering 2024年第3期21卷 1453-1464页

作者： Simin liang Yingying li Hongmei ji Xiaowu li Department of Materials Physics and Chemistry School of Materials Science and EngineeringKey Laboratory for Anisotropy and Texture of MaterialsMinistry of EducationNortheastern UniversityShenyang110819China

It is generally considered that heat treatments have a negative impact on the mechanical properties of nacre due to thermal decomposition of the organic ***,the present work investigated the microindentation behavior on fresh and heat-treated nacres from two orthogonal directions,and the results demonstrate that both hardness value and damage tolerance can remain almost unchanged on the cross-section with the organic matrix degeneration,despite a significant deterioration on the platelet *** analyses suggest that the anisotropic response of indentation behavior to heat treatment in nacre is primarily caused by its structural ***,compared with a single layer of irregular interplatelet interfaces in cross-sectional specimens,the multiple layers of parallel interlamellar interfaces in in-plane specimens exhibit a much greater ability to impede indenter-triggered destruction,and heat treatments would reduce the in-plane hardness but nearly have no effect on the cross-sectional ***,the deeper embedding of platelets in cross-sectional specimens enhances their resistance to interface cracking caused by organic matrix degradation at high temperatures,leading to a reduced sensitivity to ***,the indentation behavior of nacre shows different tendencies in response to variations in the organic matrix state along normal and parallel directions.

关键词： Nacre Structural orientation Heat treatment Indentation behavior Organic matrix

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Genomic and phenotypic signatures provide insights into the wide adaptation of a global plant invader

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Plant Communications 2024年第4期5卷 275-290页

作者： Yan Hao Xin-Feng Wang Yaolin Guo Tian-Yang li ji Yang Malika LAinouche Armel Salmon Rui-Ting Ju ji-Hua wu lin-Feng li Bo li National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary and Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering Institute of Biodiversity Science and Institute of Eco-ChongmingSchool of Life SciencesFudan UniversityShanghai 200438China State Key Laboratory of Biocontrol Guangdong Provincial Key Laboratory of Plant ResourcesSchool of Life SciencesSun Yat-sen UniversityGuangzhou 510275China UMR CNRS 6553 Universite´of RennesCampus de Beaulieu35042 Rennes Cedex ParisFrance State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems College of EcologyLanzhou UniversityLanzhou 730000China Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology and Centre for Invasion BiologyInstitute of BiodiversitySchool of Ecology and Environmental ScienceYunnan UniversityKunmingYunnan 650504China

Invasive alien species are primary drivers of biodiversity loss and species *** cordgrass(Spartina alterniflora)is one of the most aggressive invasive plants in coastal ecosystems around the ***,the genomic bases and evolutionary mechanisms underlying its invasion success have remained largely ***,we assembled a chromosome-level reference genome and performed phenotypic and population genomic analyses between native US and introduced Chinese *** phenotypic comparisons showed that introduced Chinese populations have evolved competitive traits,such as earlyflowering time and greater plant biomass,during secondary introductions along China’s *** genomic and transcriptomic inferences revealed distinct evolutionary trajectories of low-and high-latitude Chinese *** particular,genetic mixture among different source populations,together with in-dependent natural selection acting on distinct target genes,may have resulted in high genome dynamics of the introduced Chinese *** study provides novel phenotypic and genomic evidence showing how smooth cordgrass rapidly adapts to variable environmental conditions in its introduced ***,candidate genes related toflowering time,fast growth,and stress tolerance(i.e.,salinity and submergence)provide valuable genetic resources for future improvement of cereal crops.

关键词： adaptation natural selection invasive species population genomics Spartina alterniflora Hao Y. Wang X.-F. Guo Y. li T.-Y. Yang J. Ainouche M.L. Salmon A. Ju R.-T. wu J.-H. li L.-F. and li B.(2024).Genomic and phenotypic signatures provide insights into the wide adaptation of a global plant invader.

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Doping suppresses lattice distortion of vacant quadruple perovskites to activate self-trapped excitons emission

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Nano Research 2024年第4期17卷 3068-3078页

作者： Zhipeng Chen Fei Zhang Dongwen Yang Huifang ji Xu Chen Di wu Xinjian li Yu Zhang Zhifeng Shi Key Laboratory of Materials Physics of Ministry of Education School of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China State Key Laboratory on Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China

The vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),as a newly-emerging lead-free perovskite system,has attracted great research interest due to its excellent stability and direct band ***,the poor luminescence performance limits its application in light-emitting diodes(LEDs)and other ***,for the first time,an Ag^(+)ion doping strategy was proposed to greatly improve the emission performance of Cs_(4)CdBi_(2)Cl_(12) synthesized by hydrothermal *** functional theory calculations combined with experimental results evidence that the weak orange emission from Cs_(4)CdBi_(2)Cl_(12) is attributed to the phonon scattering and energy level crossing due to the large lattice distortion under excited ***,Ag^(+)ion doping breaks the intrinsic crystal field environment of Cs_(4)CdBi_(2)Cl_(12),suppresses the crossover between ground and excited states,and reduces the energy loss in the form of nonradiative *** a critical doping amount of 0.8%,the emission intensity of Cs_(4)CdBi_(2)Cl_(12):Ag^(+)reaches the maximum,about eight times that of the pristine ***,the doped Cs_(4)CdBi_(2)Cl_(12) still maintains excellent stability against heat,ultraviolet irradiation,and environmental oxygen/*** above advantages make it possible for this material to be used as solid-state phosphors for white LEDs applications,and the Commission International de I’Eclairage color coordinates of(0.31,0.34)and high color rendering index of 90.6 were *** importantly,the white LED demonstrates remarkable operation stability in air ambient,showing almost no emission decay after a long working time for 48 *** believe that this study puts forward an effective ion-doping strategy for emission enhancement of vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),highlighting its great potential as efficient emitter compatible for practical applications.

关键词： Cs_(4)CdBi_(2)Cl_(12) self-trapped excitons ion doping emission enhancement stability

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