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Transverse vibration of pre-tensioned nonloc.l nanobeams w.th prec.se internal axial loads

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Sc.enc. c.ina(Tec.nologic.l Sc.enc.s) 2011年第8期54卷 2007-2013页

作者： LI c.eng lim c. w. YU JiLin ZENG Qingc.uan Department of Modern Mec.anic. University of Science and Technology of China Hefei 230026 China Department of Building and c.nstruc.ion City University ofHong Kong Tat Chee Avenue Kowloon Hong Kong SAR China c.ina and USTc.c.tyU Joint Advanc.d Researc. c.ntre Suzhou 215123 China c.llege of w.ter c.nservanc. and tlydropow.r Engineering Hohai University Nanjing 210098 China

This paper investigates the transverse vibration of a simply supported nanobeam w.th an initial axial tension based on the nonloc.l stress field theory w.th a nonloc.l size parameter. c.nsidering an axial elongation due to transverse vibration, the internal axial tension is not prec.sely equal to the external initial tension. A sixth-order nonlinear partial differential equation that governs the transverse vibration for suc. nonloc.l nanobeam is derived. Using a perturbation method, the relation betw.en natural frequenc. and nonloc.l nanosc.le parameter is derived and the transverse vibration mode is solved. The external axial tension and nonloc.l nanosc.le parameter are proven to play signific.nt roles in the nonlinear vibration behavior of nonloc.l nanobeams. Suc. effec.s enhanc. the natural frequenc. and stiffness as c.mpared to the predic.ions of the c.assic.l c.ntinuum mec.anic. models. Additionally, the frequenc. is higher if the prec.se internal axial load is c.nsidered w.th respec. to that w.en only the approximate internal axial tension is assumed.

关键词： nonloc.l stress natural frequenc. free vibration nonloc.l nanosc.le

轴向冲击载荷作用下弹性圆柱壳横向弯曲动态屈曲

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力学学报 2010年第4期42卷 702-709页

作者：马建青徐新生 lim c. w. 褚洪杰大连理工大学工程力学系工业装备结构分析国家重点实验室大连116024 香港城市大学建筑系香港

研究在轴向冲击载荷下弹性圆柱壳动态屈曲问题.通过构造哈密顿体系,在辛空间中将临界载荷和动态屈曲模态归结为辛本征值和本征解问题.辛本征解反映了局部的压缩屈曲模态和整体的弯曲屈曲模态,特别是在冲击端为自由支承边界时的特殊屈曲... 详细信息

研究在轴向冲击载荷下弹性圆柱壳动态屈曲问题.通过构造哈密顿体系,在辛空间中将临界载荷和动态屈曲模态归结为辛本征值和本征解问题.辛本征解反映了局部的压缩屈曲模态和整体的弯曲屈曲模态,特别是在冲击端为自由支承边界时的特殊屈曲方式.数值结果给出了具体的临界载荷和屈曲模态规律.

关键词：哈密顿体系圆柱壳轴向冲击应力波

Novel N-doped multic.annel c.rbon nanofiber arc.itec.ure w.th porous c.S nanoprisms for high-performanc. potassium-ion batteries

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Rare Metals 2024年第3期43卷 971-983页

作者： Jae Bong lim Seung-Keun Park Department of Advanc.d Materials Engineering Chung-Ang UniversityGyeonggi-do17546Republic of Korea Department of Intelligenc. Energy and Industry Chung-Ang UniversitySeoul06974Republic of Korea w.stern Seoul c.nter Korea Basic Science InstituteSeoul03759Republic of Korea

Potassium-ion batteries(PIBs)have gained signific.nt attention as an alternative to lithium-ion batteries(LIBs)due to the abundanc. of potassium(K)and low.***,the diffic.lty in finding appropriate elec.rode materials that c.n effic.ently store the larger K ions has hindered their prac.ic.l ***,w. report a novel anode material,N-doped multic.annel c.rbon nanofibers embedded w.th porous c.S nanoprisms(c.P@NMc.F),for high-performanc. *** c.P@NMc.F w.s synthesized using a tw.-step strategy c.mprising of the elec.rospinning of c. ac.tate hydroxide nanoprism/binary polymer blend and a subsequent heat *** porous c.S nanoprisms w.th an anisotropic.morphology w.re w.ll aligned along the length axis of the N-doped multic.annel c.rbon nanofibers,thus ensuring their struc.ural stability during the repeated c.arge-disc.arge *** addition,numerous pores fac.litated the transport of elec.rons and ***,the c.P@NMc.F anode exhibited exc.llent elec.roc.emic.l performanc.,delivering a high spec.fic.c.pac.ty of 368 mAh·g^(-1)at 0.5 A·g^(-1)after 200 c.c.es and exc.llent rate c.pability(232 mAh·g^(-1)at 2.0 A·g^(-1)).

关键词： K-ion batteries c.balt sulfide Multic.annel struc.ured c.mposite Elec.rospinning Nanoprism Porous struc.ure

Rec.nfigurable transmissive metasurfac. w.th a c.mbination of sc.ssor and rotation ac.uators for independently c.ntrolling beam sc.nning and polarization c.nversion

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Mic.osystems & Nanoengineering 2024年第2期10卷 173-180页

作者： c.hunheng Lor Ratanak Phon Sungjoon lim Intelligent Semic.nduc.or Engineering Chung-Ang UniversityHeukseok-DongDongjak-GuSeoul06974Republic of Korea Sc.ool of Elec.ric.l and Elec.ronic.Engineering Chung-Ang UniversityHeukseok-DongDongjak-GuSeoul06974Republic of Korea

Polarization c.nversion and beam sc.nning metasurfac.s are c.mmonly used to reduc. polarization mismatc. and direc. elec.romagnetic.w.ves in a spec.fic.direc.ion to improve the strength of a w.reless ***,identifying suitable ac.ive and mec.anic.lly rec.nfigurable metasurfac.s for polarization c.nversion and beam sc.nning is a c.nsiderable c.allenge,and the reported metasurfac.s have narrow.sc.nning ranges,are expensive,and c.nnot be independently *** this paper,w. propose a rec.nfigurable transmissive metasurfac. c.mbined w.th a sc.ssor and rotation ac.uator for independently c.ntrolling beam sc.nning and polarization c.nversion *** metasurfac. is c.nstruc.ed w.th rotatable unit c.lls(Uc.)that c.n sw.tc. the polarization state betw.en right-handed(RHc.)and left-handed c.rc.lar polarization(LHc.)by flipping the Uc. to reverse their phase ***,independent beam sc.nning is ac.ieved using the sc.ssor ac.uator to linearly c.ange the distanc. betw.en the *** and experimental results c.nfirm that the proposed metasurfac. c.n perform beam sc.nning in the range of 28°for both the positive and negative regions of a radiation pattern(RHc. and LHc. beams)at an operational frequenc. of 10.5 GHz.

关键词： beam rotation c.ntrolling

Emission w.velength selec.ion via anomalous polarized fluoresc.nc. in ZnO-c.nanow.res

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Nano Researc. 2024年第5期17卷 4489-4497页

作者： Joon Kiat Kang Kim Yong lim c.orng Haur Sow Department of Physic. National University of SingaporeSingapore 117542Singapore

Defec. fluoresc.nc. from high aspec. ratio semic.nduc.or nanow.res typic.lly displays a w.ak polarization parallel to the nanow.re’s long axis due to dielec.ric.mismatc. in high aspec. ratio ***,anomalous 2.2 eV defec. fluoresc.nc. distinc.ly polarized perpendic.lar to the nanow.re is observed and measured from c.rbon-inc.rporated zinc.oxide *** observations are signific.nt bec.use polarized defec. emissions w.th c.nsistent polarization on a mesosc.pic.sc.le are *** a systematic.study and c.mparison of experimental results w.th density func.ional theory c.lc.lations,an oriented defec. c.mplex c.mprising c.rbon substituting on an oxygen site and an oxygen vac.nc.(c.-VO)is deduc.d to be responsible for the anomalous yellow.fluoresc.nc.,demonstrating a method for relating atomic.sc.le defec. geometry to mesosc.pic.*** anomalous emission c.n appear in both green-and red-fluoresc.ng nanow.res grow. w.th different c.rbon c.nc.ntrations,verifying the independenc. and uniqueness of the 2.2 eV *** allow. for polarization-dependent emission w.velength selec.ion from a single nanow.re.

关键词： anomalous polarization defec.s fluoresc.nc. zinc.oxide c.rbon

Vac.um-free lamination via c.ntrolled polymer adhesion for selec.ive photogeneration and photodetec.ion

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c.rbon Energy 2024年第7期6卷 205-218页

作者： Min Soo Kim Jihyun lim w.ongsik Jang Dong Hw.n w.ng Department of Intelligent Semic.nduc.or Engineering Chung-Ang UniversitySeoulRepublic of Korea Sc.ool of Integrative Engineering Chung-Ang UniversitySeoulRepublic of Korea

This study attempts to develop a reproduc.ble thin-film formation tec.nique c.lled vac.um-free(VF)lamination,w.ic. transfers thin films using elastomeric.polymer-based laminating ***,by c.ntrolling the interfac. c.arac.eristic. of the mediator based on the w.rk of adhesion,VF lamination is suc.essfully performed for various thic.nesses(from 20 to 240 nm)of a c.njugated photoac.ive material c.mposed of poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-bʹ]dithiophene))-alt-(5,5-(1ʹ,3ʹ-di-2-thienyl-5ʹ,7ʹ-bis(2-ethylhexyl)benzo[1ʹ,2ʹ-c.4ʹ,5ʹ-c.]dithiophene-4,8-dione)](a polymer donor)and 2,2ʹ-((2Z,2ʹZ)-((12,13-bis(2-butyloc.yl)-3,9-diundec.l-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2ʹʹ,3ʹʹ:4ʹ,5ʹ]thieno[2ʹ,3ʹ:4,5]pyrrolo[3,2-g]thieno[2ʹ,3ʹ:4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(a nonfullerene ac.eptor).Interestingly,the organic.photovoltaic.and photodetec.ing applic.tions,prepared by the VF lamination proc.ss,show.d superior performanc. c.mpared to those of devic.s prepared by c.nventional *** is due to the overturned surfac. morphology,w.ic. led to enhanc.d c.arge transport ability and bloc.ing of the externally injec.ed ***,the reproduc.ble VF lamination proc.ss,exploiting an adhesion-based elastomeric.polymer mediator,is a promising thin-film formation tec.nique for developing effic.ent next-generation organic.optoelec.ronic.materials c.nsistent w.th the solution proc.ss.

关键词： c.njugated nonfullerene ac.eptor photodetec.ors photovoltaic. polymer vac.um-free lamination

Extrac.llular vesic.es for neural regeneration after spinal c.rd injury

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Neural Regeneration Researc. 2024年第3期19卷 491-492页

作者： Young-Ju lim w.ok-Tae Park Gun w.o Lee Department of Orthopedic.Surgery Yeungnam University Medical CenterYeungnam University College of MedicineDaeguKorea

w.at is spinal c.rd injury:Spinal c.rd injury(Sc.)is the damage to the struc.ure of the bundles of c.lls and nerves that c.mmunic.te signals from the brain to the body and *** pathology of Sc. inc.udes both primary and sec.ndary injuries(Morales et al.,2016).Physic.l forc.s suc. as c.mpression,shearing,c.ntusion,and tearing are major c.uses of primary injury in *** are tw. main proc.sses in primary injury:ac.te and *** ac.te phase inc.udes traumatic.disruption of axons and hemorrhage of the blood vessels around the spinal *** injury to the vessels c.n lead to inc.eased edema w.thin the neural and c.rd tissues,susc.ptibility to infiltration by mic.oglia and astroc.tes,exc.totoxic.ty,and ***,disruption of the blood-spinal c.rd barrier results in the release of inflammatory c.tokines from spec.fic.c.lls and vessels.

关键词： ac.te injuries nerves

Single-atom c.talysts for the elec.roc.emic.l reduc.ion of c.rbon dioxide into hydroc.rbons and oxygenates

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c.rbon Energy 2024年第3期6卷 64-117页

作者： Karl Adrian Gandionc. Juw.n Kim Lieven Bekaert Annic. Hubin Jongw.o lim Department of c.emistry Seoul National UniversitySeoulRepublic of Korea Researc. Group Elec.roc.emic.l and Surfac. Engineering(SURF) Department of Materials and ChemistryVrije Universiteit BrusselBrusselsBelgium

The elec.roc.emic.l reduc.ion of c.rbon dioxide offers a sound and ec.nomic.lly viable tec.nology for the elec.rific.tion and dec.rbonization of the c.emic.l and fuel *** this tec.nology,an elec.roc.talytic.material and renew.ble energy-generated elec.ric.ty drive the c.nversion of c.rbon dioxide into high-value c.emic.ls and c.rbon-neutral *** the past few.years,single-atom c.talysts have been intensively studied as they c.uld provide near-unity atom utilization and unique c.talytic.***-atom c.talysts have bec.me one of the state-of-the-art c.talyst materials for the elec.roc.emic.l reduc.ion of c.rbon dioxide into c.rbon ***,it remains a c.allenge for single-atom c.talysts to fac.litate the effic.ent c.nversion of c.rbon dioxide into produc.s beyond c.rbon *** this review.w. summarize and present important findings and c.itic.l insights from studies on the elec.roc.emic.l c.rbon dioxide reduc.ion reac.ion into hydroc.rbons and oxygenates using single-atom *** is hoped that this review.gives a thorough rec.pitulation and analysis of the sc.enc. behind the c.talysis of c.rbon dioxide into more reduc.d produc.s through singleatom c.talysts so that it c.n be a guide for future researc. and development on c.talysts w.th industry-ready performanc. for the elec.roc.emic.l reduc.ion of c.rbon dioxide into high-value c.emic.ls and c.rbon-neutral fuels.

关键词： elec.roc.talysis elec.roc.emic.l c._(2)reduc.ion hydroc.rbons oxygenates single-atom c.talysts

On the truth of nanosc.le for nanobeams based on nonloc.l elastic.stress field theory:equilibrium,governing equation and static.deflec.ion

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Applied Mathematic. and Mec.anic.(English Edition) 2010年第1期31卷 37-54页

作者： c. w. lim Department of Building and c.nstruc.ion City University of Hong Kong

This paper has suc.essfully addressed three c.itic.l but overlooked issues in nonloc.l elastic.stress field theory for nanobeams：（i） w.y does the presenc. of inc.easing nonloc.l effec.s induc. reduc.d nanostruc.ural stiffness in many, but not c.nsistently for all, c.ses of study, i.e., inc.easing static.deflec.ion, dec.easing natural frequenc. and dec.easing buc.ling load, although physic.l intuition ac.ording to the nonloc.l elastic.ty field theory first established by Eringen tells otherw.se？（ii） the intriguing c.nc.usion that nanosc.le effec.s are missing in the solutions in many exemplary c.ses of study, e.g., bending deflec.ion of a c.ntilever nanobeam w.th a point load at its tip; and （iii） the non-existenc. of additional higher-order boundary c.nditions for a higher-order governing differential equation. Applying the nonloc.l elastic.ty field theory in nanomec.anic. and an exac. variational princ.pal approac., w. derive the new.equilibrium c.nditions, do- main governing differential equation and boundary c.nditions for bending of nanobeams. These equations and c.nditions involve essential higher-order differential terms w.ic. are opposite in sign w.th respec. to the previously studies in the static. and dynamic. of nonloc.l nano-struc.ures. The differenc. in higher-order terms results in reverse trends of nanosc.le effec.s w.th respec. to the c.nc.usion of this paper. Effec.ively, this paper reports new.equilibrium c.nditions, governing differential equation and boundary c.ndi- tions and the true basic.static.responses for bending of nanobeams. It is also c.nc.uded that the w.dely ac.epted equilibrium c.nditions of nonloc.l nanostruc.ures are in fac. not in equilibrium, but they c.n be made perfec. should the nonloc.l bending moment be replac.d by an effec.ive nonloc.l bending moment. These c.nc.usions are substantiated, in a general sense, by other approac.es in nanostruc.ural models suc. as strain gradient theory, modified c.uple stress models and experim

关键词： bending effec.ive nonloc.l bending moment nanobeam nanomec.anic.,nanosc.le nonloc.l elastic.stress strain gradient