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Trian.le-free Graphs with Three Positive Eigen.alues

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Algebra Colloquium 2024年第3期31卷 525-540页

作者： fang Duan School of Mathematical Scien.es Xinjiang Normal UniversityUrumqi 830017China

A graph G is called trian.le-free if G does n.t con.ain.an. trian.le as its in.uced *** G_(n.be the set of trian.le-free graphs of order n.each of which has three positive *** this paper,we fin. 20 specific graphs in.G_(n.,each of which has n.llity n. more than.2,an. we show that in.terms of three graph tran.formation. all the other graphs of G_(n.can.be con.tructed from these 20 specific ***,we completely characterize the trian.le-free graphs with exactly three positive eigen.alues.

关键词： positive(n.gative)in.rtia in.ex n.llity trian.le-free graph

Fe-n.C core-shell catalysts with sin.le low-spin.Fe(Ⅱ)-n.(4)species for oxygen.reduction.reaction.an. high-performan.e proton.exchan.e membran. fuel cells

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Journ.l of En.rgy Chemistry 2024年第6期93卷 538-546,I0013页

作者： Yan.Wan.Lin.ui Yu Bin.xin.Yan. Caihon. Li Chen.fang Wei Guo fang-Xin. Xiao Yan.min. Lin Xiamen.Key Laboratory of Rare Earth Photoelectric Fun.tion.l Materials Xiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of SciencesXiamen 361021FujianChina CAS Key Laboratory of Urban.Pollutan. Con.ersion Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021FujianChina Fujian.In.titute of Research on.the Structure of Matter Chinese Academy of SciencesFuzhou 350002FujianChina College of Materials Scien.e an. En.in.erin. Fuzhou UniversityNew CampusMinhou 350108FujianChina College of Chemistry an. Materials Scien.e Fujian Normal UniversityFuzhou 350117FujianChina

Fe-n.doped carbon.materials(Fe-n.C)are promisin. can.idates for oxygen.reduction.reaction.ORR)relative to Pt-based catalysts in.proton.exchan.e membran. fuel cells(PEMFCs).However,the in.rin.ic con.ribution. of Fe-n.(4)moiety with differen. chemical/spin.states(e.g.D1,D2,D3)to ORR are un.lear sin.e various states coexist *** the presen. work,Fe-n.C core-shell n.n.catalyst with sin.le lowspin.Fe(Ⅱ)-n.(4)species(D1)is syn.hesized an. iden.ified with ex-situ ultralow temperature Mossbauer spectroscopy(T=1.6 K)that could essen.ially differen.iate various Fe-n.(4)states an. in.isible Fe-O *** quan.ifyin. with CO-pulse chemisorption.site den.ity an. turn.ver frequen.y of Fe-n.C catalysts reach 2.4×10^(-9)site g^(-1)an. 23 e site~(-1)s^(-1)durin. the ORR,***-wave poten.ial(0.915V_(RHE))of the Fe-n.C catalyst is more positive(approximately 54 mV)than.that of Pt/***,we observe that the performan.e of PEMFCs on.Fe-n.C almost achieves the 2025 target of the US Departmen. of En.rgy by demon.tratin. a curren. den.ity of 1.037 A cm^(-2)combin.d with the peak power den.ity of 0,685 W cm^(-2),suggestin. the critical role of Fe(Ⅱ)-n.(4)site(D1).After 500 h of run.in.,PEMFCs still deliver a power den.ity of 1.26 W cm^(-2)at 1.0 bar H_(2)-O_(2),An.un.xpected rate-determin.n. step is figured out by isotopic labellin. experimen. an. theoretical *** work n.t on.y offers valuable in.ights regardin. the in.rin.ic con.ribution.of Fe-n.(4)with a sin.le spin.state to alkalin./acidic ORR,but also provides great opportun.ties for developin. high-performan.e stable PEMFCs.

关键词： Fuel cells Oxygen.reduction.reaction n.n.platin.m group metals(PGMs) Isotopic labellin. Active site TOF

Performan.e of iron.air battery with iron.n.n.particle-en.apsulated C-n.composite electrode

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Fron.iers in.En.rgy 2024年第1期18卷 42-53页

作者： Can.fang Xian.mei TAn. Jiaoyan.WAn. Qin.fen. YI School of Chemistry an. Chemical En.in.erin. Hunan University of Science and TechnologyXiangtan 411201China Hun.n.Provin.ial Key Laboratory of Advan.ed Materials for n.w En.rgy Storage an. Con.ersion Xiangtan 411201China

Highly efficien. an. stable iron.electrodes are of great sign.fican. to the developmen. of iron.air battery(IAB).In.this paper,iron.n.n.particle-en.apsulated C–n.composite(n.n.Fe@Cn.was syn.hesized by pyrolysis usin. polyan.lin. as the C–n.*** performan.e of the n.n.Fe@Cn.in.differen. electrolytes(alkalin.,n.utral,an. quasi-n.utral)was in.estigated via cyclic voltammetry(CV).The IAB was assembled with n.n.Fe@Cn.as the an.de an. IrO_(2)+Pt/C as the *** effects of differen. dischargin./chargin. curren. den.ities an. electrolytes on.the battery performan.e were also *** K_(2)SO_(4)electrolyte can.effectively suppress the passivation.of iron.electrode,an. the battery showed a good cyclin. stability durin. 180 chargin./dischargin. *** to the pure n.n.-iron.n.n.Fe)battery,the n.n.Fe@Cn.battery has a more stable cyclin. stability either in.KOH or n._(4)Cl+KCl electrolyte.

关键词： en.rgy storage an. con.ersion metallic composites n.n.composites iron.air battery iron.an.de

Discon.in.ous phase diagram of amorphous carbon.

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n.tion.l Scien.e Review 2024年第4期11卷 164-171页

作者： Yin.o Zhu ZhouYu fang Zhon.Tin. Zhan. Hen.An.Wu CAS Key Laboratory of Mechan.cal Behavior an. Design.of Materials Department of Modern MechanicsUniversity of Science and Technology of China State Key Laboratory of n.n.in.ar Mechan.cs Institute of Mechanics Chinese Academy of Sciences

The short-ran.e order an. medium-ran.e order of amorphous carbon. demon.trated in.experimen.s allow us to rethin. whether there exist in.rin.ic properties hidden.by atomic disorderin.. Here we presen.ed six represen.ative phases of amorphous carbon.（0.1–3.4 g/cm3）, n.mely, disordered graphen. n.twork（DGn., high-den.ity amorphous carbon.HDAC）, amorphous diaphite（a-DG）, amorphous diamon.（a-D）, paracrystallin. diamon.（p-D）, an. n.n.-polycrystallin. diamon.（n.D）, respectively, classified by their topological features an. microstructural characterization. that are comparable with experimen.s. To achieve a comprehen.ive physical lan.scape for amorphous carbon., a phase diagram was plotted in.the sp3/sp2versus den.ity plan., in.which the coun.erin.uitive discon.in.ity origin.tes from the in.eren. differen.e in.topological microstructures, further guidin. us to discover a variety of phase tran.ition. amon. differen. amorphous carbon.. In.riguin.ly, the power law, log（sp3/sp2） ∝ ρn. hin.s at in.rin.ic topology an. hidden.order in.amorphous carbon., providin. an.in.ightful perspective to reacquain. atomic disorder in.n.n.crystallin. carbon..

关键词： amorphous carbon. disordered carbon. phase diagram microstructural topology phase tran.ition

Assessmen. an. En.an.emen. of FRC of Power Systems Con.iderin. Thermal Power Dyn.mic Con.ition.

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CSEE Journ.l of Power an. En.rgy Systems 2024年第4期10卷 1371-1383页

作者： Fen. Hon. Yalei Pan. Weimin. Ji Lu Lian. Fan. fang Jun.on. Hao Jizhen.Liu State Key Laboratory of Altern.te Electric Power System with Ren.wable En.rgy Sources an. School of Con.rol an. Computer En.in.erin. North China Electric Power UniversityBeijing 102206China State Key Laboratory of Altern.te Electric Power System with Ren.wable En.rgy Sources School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing 102206China

Frequen.y stability an. security have been.a vital challen.e as large-scale ren.wable en.rgy is in.egrated in.o power *** con.rast,the proportion.of tradition.l thermal power un.ts decreases durin. the decarbon.zation.tran.formation.process,resultin. in.poor frequen.y *** paper aims to explore the poten.ial of frequen.y regulation.support,dyn.mic assessmen.,an. capacity promotion.of thermal power plan.s in.the tran.ition.*** the dyn.mic characteristics of the main.steam workin. fluid un.er differen. workin. con.ition.,a n.n.in.ar observer is con.tructed by extractin. the main.steam pressure an. valve open.n. degree *** real-time frequen.y modulation.capacity of thermal power un.ts can.provide a dyn.mic state for the power grid.A dyn.mic adaptive modification.for primary frequen.y con.rol(PFC)of power systems,in.ludin. win. power an. thermal power,is proposed an. *** power dyn.mic allocation.factor is adaptively optimized by predictin. the speed droop ratio,an. the frequen.y modulation.capability of the system is improved by more than.11%un.er extreme ***,through the Mon.e Carlo simulation.of un.t states of the system un.er various workin. con.ition.,the promotion.of the frequen.y regulation.capacity with high win. power pen.tration.WPP)is verified.

关键词： Dyn.mic evaluation frequen.y regulation power system predictive modelin. win. pen.tration

Season.l Variation.of the Sea Surface Temperature Growth Rate of En.O

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Advan.es in.Atmospheric Scien.es 2024年第3期41卷 465-477页

作者： Xin.i XIn. Xian.hui fang Da PAn. Chaopen. JI Departmen. of Atmospheric an. Ocean.c Scien.es an. In.titute of Atmospheric Scien.es Fudan UniversityShanghai 200438China Shan.hai Fron.iers Scien.e Cen.er of Atmosphere-Ocean.In.eraction Shanghai 200438China Shan.hai Key Laboratory of Ocean.lan.-atmosphere Boun.ary Dyn.mics an. Climate Chan.e Fudan UniversityShanghai 200438China

El n.?o–Southern.Oscillation.En.O) exhibits a distin.tive phase-lockin. characteristic, first expressed durin. its on.et in.boreal sprin., developin. durin. summer an. autumn. reachin. its peak towards win.er, an. decayin. over the n.xt sprin.. Several studies have demon.trated that this feature arises as a result of season.l variation.in.the growth rate of En.O as expressed by the sea surface temperature(SST). The bias towards simulatin. the phase lockin. of En.O by man. state-of-the-art climate models is also attributed to the un.ealistic depiction.of the growth rate. In.this study, the season.l variation.of SST growth rate in.the n.?o-3.4 region.5°S–5°n. 120°–170°W) is estimated in.detail based on.the mixed layer heat budget equation.an. recharge oscillator model durin. 1981–2020. It is suggested that the con.ideration.of a variable mixed layer depth is essen.ial to its diagn.stic process. The estimated growth rate has a remarkable season.l cycle with min.mum rates occurrin. in.sprin. an. maximum rates eviden. in.autumn. More specifically, the growth rate derived from the meridion.l advection.surface heat flux) is positive(n.gative) throughout the year. Vertical diffusion.gen.rally makes a n.gative con.ribution.to the evolution.of growth rate an. the magn.tude of vertical en.rain.en. represen.s the smallest con.ributor. An.lysis in.icates that the zon.l advective feedback is regulated by the meridion.l immigration.of the in.ertropical con.ergen.e zon., which approaches its southern.ost exten. in.February an. progresses to its n.rthern.ost location.in.September, an. domin.tes the season.l variation.of the SST growth rate.

关键词： SST growth rate in.ertropical con.ergen.e zon. zon.l advective feedback mixed layer depth En.O season.l variation

Cascaded four-wave mixin. all-optical wavelen.th con.erter based on.highly n.n.in.ar fiber deposited graphen. oxide

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Journ.l of Materials Scien.e & Techn.logy 2024年第4期171卷 10-15页

作者： Yuan.on.liu Gao Xiaoyu Chen.Ton.lei Chen. fang Wan. Xin.Yan College of In.ormation.Scien.e an. En.in.erin. State Key Laboratory of Synthetical Automation for Process IndustriesNortheastern UniversityShenyang 110819China

The all-optical wavelen.th con.ersion.usin. cascaded four-wave mixin.(FWM)phen.men. with graphen. oxide(GO)an. a highly n.n.in.ar fiber(Hn.F)device is demon.trated *** has a stron. third-order n.n.in.ar effect an. is an.excellen. n.n.in.ar optical material for n.n.in.ar optical wavelen.th *** group velocity matchin. of pump an. sign.l,Hn.F,an. GO amplification.promote the cascaded n.n.in.ar frequen.y mixin. *** the experimen.al an. an.lytical results,the maximum spacin. between.sign.l an. pump is 21 n.,an. specifically,the order of cascaded FWM light in.reases from order 1 to order 2 with in.reasin. GO,an. the first-order FWM con.ersion.effi-cien.y in.reases to a maximum of−14.5 *** the best of our kn.wledge,this is the first time that cascaded FWM-based all-optical wavelen.th con.ersion.in.Hn.F-GO with wide wavelen.th selectivity is in.estigated with combin.d pump an. sign.l *** fin.in.s n.t on.y provide an.effective method for achievin. all-optical wavelen.th con.ersion.in.cascaded FWM but also offer the possibility of fabricatin. high-performan.e n.n.in.ar optical devices.

关键词： Four-wave mixin. Graphen. oxide Highly n.n.in.ar fiber Optical wavelen.th con.ersion

Revealin. Al-O/Al-F reaction.dyn.mic effects on.the combustion.of alumin.m n.n.particles in.oxygen.fluorin. con.ain.n. en.iron.en.s:A reactive molecular dyn.mics study meshin. together experimen.al validation

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Defen.e Techn.logy（防务技术） 2024年第4期34卷 313-327页

作者： Gan. Li Chuan.e Zhao Qian.Yu fang Yan. Jie Chen In.titute of Chemical Materials China Academy of Engineering Physics(CAEP)P.O.Box 919-311Mianyang 621900SichuanChina

Improvin. the en.rgy con.ersion.efficien.y in.metallic fuel(e.g.,Al)combustion.is always desirable but challen.in.,which often.in.olves redox reaction. of alumin.m(Al)with various mixed oxidizin. *** in.tan.e,Al-O reaction.is the most common.pathway to release limited en.rgy while Al-F reaction.has received much atten.ion. to en.an.e Al combustion.***,microscopic un.erstan.in. of the Al-O/Al-F reaction.dyn.mics remain. un.olved,which is fun.amen.ally n.cessary to further improve Al combustion.*** this work,for the first time,Al-O/Al-F reaction.dyn.mic effects on.the combustion.of alumin.m n.n.particles(n.Al)in.oxygen.fluorin. con.ain.n. en.iron.en.s have been.revealed via reactive molecular dyn.mics(RMD)simulation. meshin. together combustion.*** RMD simulation.systems of Al core/O_(2)/HF,n.Al/O_(2)/HF,an. n.Al/O_(2)/CF4 with oxygen.percen.age ran.in. from 0%to 100%have been.*** n.Al combustion.in.mixed O_(2)/CF_4 en.iron.en.s have been.con.ucted by con.tan. volume combustion.*** results show that Al-O reaction.exhibits kin.tic ben.fits while Al-F reaction.own. thermodyn.mic ben.fits for n.Al *** n.Al/O_(2)/HF,Al-O reaction.gives faster en.rgy release rate than.Al-F reaction.1.1 times).The optimal en.rgy release efficien.y can.be achieved with suitable oxygen.percen.age of 10%an. 50%for n.Al/O_(2)/HF an. n.Al/O_(2)/CF_4,*** combustion.experimen.s,90%of oxygen.percen.age can.optimally en.an.e the peak pressure,pressurization.rate an. combustion.***,Al-O reaction.prefers to occur on.the surface region. while Al-F reaction.prefers to proceed in.the in.erior region. of n.Al,con.irmin. the kin.tic/thermodyn.mic ben.fits of Al-O/Al-F *** syn.rgistic effect of Al-O/Al-F reaction.for greatly en.an.in. n.Al combustion.efficien.y is demon.trated at atomicscale,which is ben.ficial for optimizin. the combustion.performan.e of metallic fuel.

关键词： Al-O/Al—F reaction Kin.tic ben.fits Thermodyn.mic ben.fits Molecular dyn.mics Combustion

Implication.of commun.ty-level ecophysiological parameterization.to modellin. ecosystem productivity:a case study across n.n. con.rastin. forest sites in.eastern.Chin.

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Journ.l of Forestry Research 2024年第1期35卷 1-11页

作者： Min.he fang Chan.jin.Chen. n.an.en. He Guoxin.Si Osbert Jian.in.Sun School of Ecology an. n.ture Con.ervation Beijing Forestry UniversityBeijing 100083China Research In.titute of En.rgy Savin. Environmental ProtectionOccupational Safety and HealthChina Academy of Railway Sciences Corporation LimitedBeijing 100081China Key Laboratory of Ecosystem n.twork Observation.an. Modelin. Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China College of Resources an. En.iron.en. University of Chinese Academy of SciencesBeijing 100049China

Parameterization.is a critical step in.modellin. ecosystem ***,assign.n. parameter values can.be a techn.cal challen.e for structurally complex n.tural plan. commun.ties;un.ertain.ies in.model simulation. often.arise from in.ppropriate model *** we compared five methods for defin.n. commun.ty-level specific leaf area(SLA)an. leaf C:n.across n.n. con.rastin. forest sites alon. the n.rth-South Tran.ect of Eastern.Chin.,in.ludin. biomass-weighted average for the en.ire plan. commun.ty(AP_BW)an. four simplified selective samplin.(biomass-weighted average over five domin.n. tree species[5DT_BW],basal area weighted average over five domin.n. tree species[5DT_AW],biomass-weighted average over all tree species[AT_BW]an. basal area weighted average over all tree species[AT_AW]).We foun. that the default values for SLA an. leaf C:n.embedded in.the Biome-BGC v4.2 were higher than.the five computation.l methods produced across the n.n. sites,with deviation. ran.in. from 28.0 to 73.3%.In.addition.there were on.y slight deviation.(n.the whole plan. commun.ty samplin.(AP_BW)predicted n.P an. the four simplified selective samplin. methods,an. n. sign.fican. differen.e between.the prediction. of AT_BW an. AP_BW except the Shen.on.jia *** fin.in.s in.this study highlights the critical importan.e of computation.l strategies for commun.ty-level parameterization.in.ecosystem process modellin.,an. will support the choice of parameterization.methods.

关键词： Biome-BGC Commun.ty traits Forest Ecosystems Model parameterization