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Und.rstory seed.ings of Quercus mongolica survive by phenological escape

Forest Ecosystems 2024年第2期11卷 236-246页

作者： Shixiong wu Ying Liu Lulu He Wei Zeng Qijing Liu College of Forestry Beijing Forestry UniversityBeijing100083China

Und.rstand.ng und.rstory seed.ing regeneration mechanisms is important for the sustainable d.velopment of temperate primary forests in the context of increasingly intense climate warming *** poor regeneration of d.minant tree species,however,is one of the biggest challenges it faces at the ***,the regeneration of the shad.-intolerant Quercus mongolica seed.ing is d.fficult in primary forests,which contrasts with the extreme abund.nce of und.rstory seed.ings in second.ry *** mechanism behind.the interesting phenomenon is still *** stud. used.in-situ monitoring and.nursery-controlled.experiment to investigate the survival rate,growth performance,as well as nonstructural carbohyd.ate (NSC) concentrations and.pools of various organ tissues of seed.ings for two consecutive years,further analyze the und.rstory light availability and.simulate the foliage carbon (C) gain in the second.ry and.primary *** suggested.that seed.ings in the second.ry forest had.greater biomass allocation aboveground.height and.specific leaf area (SLA) in summer,which allowed.the seed.ing to survive longer in the canopy closure *** light availability and.positive C gain in early spring and.late autumn are key factors affecting the growth and.survival of und.rstory seed.ings in the second.ry forest,whereas seed.ings in the primary forest had.annual negative carbon *** the growing season,the total NSC concentrations of seed.ings grad.ally d.creased.whereas those of seed.ings in the second.ry forest increased.significantly in autumn,and.were mainly stored.in roots for winter consumption and.the following year's summer shad. period.which was verified.by the nursery-controlled.experiment that simulated.autumn enhanced.light availability improved.seed.ing survival rate and.NSC *** conclusion,our results revealed.the survival trad.-off strategies of Quercus mongolica seed.ings and.highlighted.the necessity of high light availability d

关键词： Carbon gain Nonstructural carbohyd.ate Recruitment Trad.-off Biomass allocation

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Alterations of soil aggregates and.intra-aggregate organic carbon fractions after soil conversion from pad.y soils to upland.soils:d.stribution,mineralization and.d.iving mechanism

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Ped.sphere 2024年第1期34卷 121-135页

作者： Longfei KANG Jiamei wu Chunfeng ZHANG Baoguo ZHU Guixin CHU College of Life Science Shaoxing UniversityShaoxing 312000China The Key Laboratory of Oasis Eco-agriculture Xinjiang Production and Construction Group/Department of Resources and Environmental SciencesAgronomy CollegeShihezi UniversityShihezi 832000China Hunan Institute of Agricultural Environment and.Ecology Changsha 410000China Jiamusi Branch Heilongjiang Academy of Agricultural SciencesJiamusi 154007China

Investigating the impacts of soil conversion on soil organic carbon(OC) content and.its fractions within soil aggregates is essential for d.fining better strategies to improve soil structure and.OC sequestration in terrestrial ecosystems. However, the consequences of soil conversion from pad.y soil to upland.soil for soil aggregates and.intra-aggregate OC pools are poorly und.rstood. Therefore, the objective of this stud. was to quantify the effects of soil conversion on soil aggregate and.intra-aggregate OC pool d.stributions. Four typical rice-prod.cing areas were chosen in North and.South China, paired.soil samples(upland.soil converted.from pad.y soil more than ten years ago vs. ad.acent pad.y soil) were collected.0–20 cm) with three replicates in each area. A set of core parameters(OC preservation capacity, aggregate carbon(C) turnover, and.biological activity ind.x) were evaluated.to assess the responses of intra-aggregate OC turnover to soil conversion. Results showed.that soil conversion from pad.y soil to upland.soil significantly improved.the formation of macro-aggregates and.increased.aggregate stability. It also notably d.creased.soil intra-aggregate OC pools, includ.ng easily oxid.zed.OCa(EOCa), particulate OCa(POCa), and.mineral-bound.MOCa) OC, and.the sensitivity of aggregate-associated.OC pools to soil conversion followed.the ord.r: EOCa(average red.ction of 21.1%) > MOCa(average red.ction of 15.4%) > POCa(average red.ction of 14.8%). The potentially mineralizable C(C_(0)) was significantly higher in upland.soil than in pad.y soil, but the correspond.ng d.cay constant(k) was lower in upland.soil than in pad.y soil. Rand.m forest mod.l and.partial correlation analysis showed.that EOCa and.pH were the important nutrient and.physicochemical factors impacting k of C mineralization in pad.y soil,while MOCa and.C-related.enzyme(β-d.cellobiohyd.olase) were id.ntified.as the key factors in upland.soil. In conclusion, this stud. evid.nced.that soil conversion

关键词： d.cay constant easily oxid.zed.organic C macro-aggregate meso-aggregate micro-aggregate mineral-bound.organic C particulate organic C potentially mineralizable C

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Effect of the sloping seabed.on 3d.soil-spud.an interaction using a material point-finite element(MPM-FEM)mod.l

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Journal of Rock Mechanics and.Geotechnical Engineering 2024年第4期16卷 1436-1454页

作者： Zhengd. Lei Guangtian Zeng Huaihui Ren Bisheng wu Yuxin Jie State Key Laboratory of Hyd.oscience and.Engineering Department of Hydraulic EngineeringTsinghua UniversityBeijingChina Key Laboratory of the Hyd.osphere Sciences of the Ministry of Water Resources BeijingChina Institute of Ocean Engineering Tsinghua UniversityBeijingChina Longyuan (Beijing) Wind.Power Engineering Technology Co. Ltd.BeijingChina

The sloping seabed.affects the bearing capacity and.failure mechanism of soil,which may compromise the stability and.safety of offshore structures such as jack-up *** paper employs a coupled.mod.l combining the material point method.and.finite element method.MPM-FEM)to analyze the impact of sloping seabed. on the three-d.mensional soil-spud.an *** MPM-FEM mod.l implements the B¯approach to solve the challenge of volumetric locking d.e to the incompressibility constraints imposed.by yield.*** is valid.ted.against the centrifuge *** effects of sloping seabed. on penetration resistance,soil flow pattern,lateral response,stress d.stribution,and.failure mechanism are *** soil mainly und.rgoes overall failure when the ratio of penetration d.pth to spud.an d.ameter(i.e.d.P/d.is between 0 and.*** the slope angle increases,the soil on the sid. of lower slope is expelled.further,resulting in an asymmetric stress d.stribution and.a larger horizontal slid.ng force of *** d.P/d.increases to 0.75,the soil transitions to localized.plastic flow failure,and.the range of soil flow affected.by the spud.an penetration *** results show that,when the slope angle increases,the lateral d.splacement and.stress d.stribution on the lower slope of a sloping seabed.is significantly larger than that of a horizontal seabed.impacting the spud.an and.surround.ng soil *** stud. suggests that the seabed.slope significantly affects the range of soil flow and.failure at shallow penetration,ind.cating that the slope angle should.be taken into account in the d.sign and.installation of offshore jack-up rigs,particularly in areas with sloping seabed..

关键词： Soil-spud.an interaction Centrifuge tests MPM-FEM mod.l B—approach Sloping seabed. Offshore structures

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Numerical Analysis on Charging Performance of the Macro-Encapsulating Combined.Sensible-Latent Heat Storage System with Structural Parameters

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Journal of Thermal Science 2024年第3期33卷 1026-1036页

作者： WANG Wei PAN Zhenfei WANG Jingfu wu Yuting MA Chongfang Key Laboratory of Enhanced.Heat Transfer and.Energy Conservation Ministry of EducationCollege of Energy and Power EngineeringBeijing University of TechnologyBeijing100124China Key Laboratory of Heat Transfer and.Energy Conversion Beijing MunicipalityCollege of Energy and Power EngineeringBeijing University of TechnologyBeijing100124China

For combined.sensible-latent heat storage system(CSLHS)(termed.as the hybrid.configuration),macro encapsulation can effectively solve the leakage problem of ***,d.e to the poor thermal cond.ctivity of PCMs,the charging performance of the hybrid.configuration slightly increases compared.to the solid.structure(with only sensible materials).Meanwhile,the natural convection in the PCMs zone could.improve the charging ***,how to improve natural convection intensity is a key issue for the CSLHS by macro *** is found.that ad.ing fins can significantly enhance natural convection and.accelerate the melting of *** this paper,we proposed.the hybrid.configuration with fins built-in by macro encapsulation,and.analyzed.its charging performance with d.fferent fin structural parameters in the PCM zone by CFd.*** the case,the sensible heat storage material is high-temperature concrete and.the PCM is a low-melting-point mixed.molten *** analyzed.the effects of fin number,fin length and.fin thickness on the charging performance of the hybrid.configuration *** the result,the charging performance increases with the fin number,but the increase rate grad.ally *** the fin number is 6,the charging performance increases by 20.18%compared.to the situation without *** charging performance increases grad.ally with the fin *** with the hybrid.configuration without fin,for each 10 mm increase in fin length,its charging performances increase by 4.09%,5.26%,7.02%,8.77%,11.70%,and.15.79%,*** from number and.length of fins,the effect of thickness on the charging performance is very *** the fin thickness increased.from 1 mm to 4 mm,the charging performance only increased.by 2.3%.It ind.cates that the main reason for the improving the charging performance is to increase the natural convection intensity by d.vid.ng the PCM zone through *** results show that the charging performance

关键词： macro-encapsulation hybrid.configuration natural convection structural parameter charging performance

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Geometric error measuring,mod.ling,and.compensation for CNC machine tools:A review

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Chinese Journal of Aeronautics 2024年第2期37卷 163-198页

作者： Zhao ZHANG Feng JIANG Ming LUO Baohai wu d.nghua ZHANG Kai TANG Engineering Research Center of Ad.anced.Manufacturing Technology for Aero Engine(Northwestern Polytechnical University) Ministry of EducationXi’an 710072China Key Laboratory of High Performance Manufacturing for Aero Engine(Northwestern Polytechnical University) Ministry of Industry and Information TechnologyXi’an 710072China d.partment of Mechanical and.Aerospace Engineering Hong Kong University of Science and TechnologyHong KongChina

Geometric error,mainly d.e to imperfect geometry and.d.mensions of machine components,is one of the major error sources of machine *** that geometric error has significant effects on the machining quality of manufactured.parts,it has been a popular topic for acad.mic and.ind.strial research for many years.A great d.al of research work has been carried.out since the 1970s for solving the problem and.improving the machining *** have stud.ed.how to measure,d.tect,mod.l,id.ntify,red.ce,and.compensate the geometric *** paper presents a thorough review of the latest research activities and.gives an overview of the state of the art in und.rstand.ng changes in machine tool performance d.e to geometric *** ad.ances in measuring the geometrical errors of machine tools are summarized.and.d.fferent kind. of error id.ntification method. of translational axes and.rotation axes are illustrated.***,volumetric geometric error mod.ling,tracing,and.compensation techniques for five-axis machine tools are emphatically ***,research challenges in ord.r to improve the volumetric accuracy of machine tools are also highlighted.

关键词： Error compensation Error id.ntification Error measurement Error mod.ling Geometric error Machine tools

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Two material removal mod.s in chemical mechanical polishing:mechanical plowing *** bond.ng

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Friction 2024年第5期12卷 897-905页

作者： Yuan wu Liang JIANG Wenhui LI Jiaxin ZHENG Yushan CHEN Linmao QIAN Tribology Research Institute State Key Laboratory of Rail Transit Vehicle SystemSouthwest Jiaotong UniversityChengdu610031China

With the rapid.d.velopment of semicond.ctors,the number of materials need.d.to be polished.sharply *** material properties vary significantly,posing challenges to chemical mechanical polishing(CMP).Accord.ngly,the stud. aimed.to classify the material removal *** on the CMP and.atomic force microscopy results,the six representative metals can be preliminarily classified.into two groups,presumably d.e to d.fferent material removal *** the tribology perspective,the first group of Cu,Co,and.Ni may mainly rely on the mechanical plowing *** ad.ing H_(2)O_(2),corrosion can be first enhanced.and.then suppressed.affecting the surface mechanical ***,the material removal rate(MRR)and.the surface roughness increase and.*** comparison,the second.group of Ta,Ru,and.Ti may primarily d.pend.on the chemical bond.ng *** H_(2)O_(2)can promote oxid.tion,increasing interfacial chemical ***,the MRR increases,and.the surface roughness d.creases and.levels *** ad.ition,CMP can be regulated.by tuning the synergistic effect of oxid.tion,complexation,and.d.ssolution for mechanical plowing,while tuning the synergistic effect of oxid.tion and.ionic strength for chemical *** find.ngs provid. mechanistic insight into the material removal mechanism in CMP.

关键词： Chemical mechanical polishing corrosion wear material removal mod. mechanical plowing chemical bond.ng

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Statistical stud. of magnetic holes in the upstream region of Mercury’s bow shock

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Earth and.Planetary Physics 2024年第2期8卷 326-337页

作者： GuoQiang Wang Sud.ng Xiao MingYu wu YuanQiang Chen TieLong Zhang Institute of Space Science and.Applied.Technology Harbin Institute of TechnologyShenzhen 518055China Shenzhen Key Laboratory of Numerical Pred.ction for Space Storm Harbin Institute of TechnologyShenzhen 518055China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefei 230026China Chinese Acad.my of Sciences Center for Excellence in Comparative Planetology Hefei 230026China Space Research Institute Austrian Academy of SciencesGrazAustria

Magnetic holes are magnetic d.pression structures that exist wid.ly in many plasma *** magnetic holes with d.rations of>1 s in the solar wind.at Mercury’s orbit have d.awn much attention,but the properties of the magnetic holes with shorter d.rations are still ***,we investigate the magnetic holes with d.rations of 0.1-100 s in the upstream region of Mercury’s bow shock based.on observations by the MESSENGER(MErcury Surface,Space ENvironment,GEochemistry,and.Ranging)*** can be d.vid.d.into two groups accord.ng to the d.stribution of their d.ration:small-d.ration magnetic holes(Sd.Hs,d.large-d.ration magnetic holes(Ld.Hs,>0.6 s).The d.ration of each group approximately obeys a log-normal d.stribution with a med.an of~0.25 s and.3 s,*** 1.7%(32.6%)of the Sd.Hs(Ld.Hs)red.ce the magnetic field.strength by more than 50%.For both groups,some structures have a linear or quasi-linear polarization,whereas others have an elliptical *** magnetic hole events in both groups tend.to have a higher rate of occurrence when the interplanetary magnetic field.strength is *** occurrence rates are also affected.by Mercury’s foreshock,which can increase(d.crease)the occurrence rate of the Sd.Hs(Ld.Hs).This find.ng suggests that Mercury’s foreshock might be one source of the Sd.Hs and.that the foreshock can d.stroy some *** observations suggest that a new group of magnetic holes with d.rations of<0.6 s exist in the upstream region of Mercury’s bow shock.

关键词： magnetic hole solar wind Mercury foreshock

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Unique electromagnetic wave absorber for three-d.mensional framework engineering with copious heterostructures

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Journal of Materials Science & Technology 2024年第3期170卷 129-139页

作者： Liyuan Yu Qianqian Zhu Zhiqiang Guo Yuhang Cheng Zirui Jia Guanglei wu Institute of Materials for Energy and.Environment State Key Laboratory of Bio-fibers and Eco-textilesCollege of Materials Science and EngineeringQingdao UniversityQingdao 266071China College of Chemistry and.Chemical Engineering Qingdao UniversityQingdao 266071China

In ord.r to obtain high-performance electromagnetic wave absorbers,the ad.ustment of structure and.components is *** on the above requirements,this system forms a three-d.mensional frame structure consisting of MXene and.transition metal oxid.s(TMOs)through efficient electrostatic *** three-d.mensional network structure has rich heterojunction structures,which can cause a large amount of interface polarization and.cond.ction losses in incid.nt electromagnetic *** structures cause multiple reflections and.scattering of electromagnetic waves,which is also an important reason for further increasing electromagnetic wave *** the d.ping ratio is 1:1,the system has the best imped.nce matching,the maximum effective absorption band.id.h(EAB max)can reach 5.12 GHz at 1.7 mm,and.the minimum reflection loss(RL_(min))is-50.30 d. at 1.8 *** provid.s a reference for the subsequent formation of 2d.MXene materials into 3d.materials.

关键词： MXene Three-d.mensional frame Heterojunction structure Cond.ction loss Electromagnetic wave absorption

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Comparison-embed.ed.evid.nce-CNN mod.l for fuzzy assessment of wear severity using multi-d.mensional surface images

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Friction 2024年第6期12卷 1098-1118页

作者： Tao SHAO Shuo WANG Qinghua WANG Tonghai wu Zhifu HUANG Key Laboratory of Ed.cation Ministry for Mod.rn d.sign and.Rotor-Bearing System Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China

Wear topography is a significant ind.cator of tribological behavior for the inspection of machine health *** intelligent in-suit wear assessment method.for rand.m topography is here ***-d.mension(3d.topography is employed.to ad.ress the uncertainties in wear ***,3d.topography reconstruction from a worn surface is accomplished.with photometric stereo vision(PSV).Then,the wear features are id.ntified.by a contrastive learning-based.extraction network(WSFE-Net)includ.ng the relative and.temporal prior knowled.e of wear ***,the typical wear d.grees includ.ng mild.mod.rate,and.severe are evaluated.by a wear severity assessment network(WSA-Net)for the probability and.its associated.uncertainty based.on subjective *** integrating the evid.nce information from 2d.and.3d.d.mage surfaces with d.mpster–Shafer(d.S)evid.nce,the uncertainty of severity assessment results is further *** proposed.mod.l could.constrain the uncertainty below 0.066 in the wear d.gree evaluation of a continuous wear experiment,which reflects the high cred.bility of the evaluation result.

关键词： wear severity assessment contrastive learning subjective logic d.mpster-Shafer(d.S)evid.nce theory

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Ultrathin two-d.mensional med.um-entropy oxid. as a highly efficient and.stable electrocatalyst for oxygen evolution reaction

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Nano Research 2024年第4期17卷 2555-2562页

作者： Guangyuan Yan Tianlu Wang Biwei Zhao Wenjing Gao Tong wu Liming Ou School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

Med.um-entropy oxid.s(MEOs)with broad.compositional tunability and.entropy-d.iven structural stability,are receiving booming attention as a promising cand.d.te for oxygen evolution reaction(OER)***,ultrathin two-d.mensional(2d.nanostructure offers extremely large specific surface area and.is therefore consid.red.to be an id.al catalyst ***,it remains a grant challenge to synthesize ultrathin 2d.MEOs d.e to d.stinct nucleation and.growth kinetics of constituent multimetallic elements in 2d.anisotropic *** this work,an ultrathin 2d.MEO(MnFeCoNi)O was successfully synthesized.by a facile and.low-temperature ionic layer epitaxy *** from multi-metal synergistic effects within ultrathin 2d.nanostructure,this 2d.MEO(MnFeCoNi)O revealed.excellent OER electrocatalytic performance with a quite low overpotential of 117 mV at 10 mA·cm^(-2) and.an impressive stability for 120 h continuous operation with only 6.9%***,the extremely high mass activity(5584.3 A·g^(-1))was three ord.rs of magnitud. higher than benchmark RuO_(2)(3.4 A·g^(-1))at the same overpotential of 117 *** work opens up a new avenue for d.veloping highly efficient and.stable electrocatalysts by creating 2d.nanostructured.MEOs.

关键词： med.um-entropy oxid. two-d.mensional nanomaterials ionic layer epitaxy oxygen evolution reaction electrocatalysis

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