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Effects of ba.fle position in serpentine flow cha.nel on the performance of proton excha.ge membra.e fuel cells

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Chinese Journa. of Chemica. Engineering 2024年第5期69卷 250-262页

作者： Guodong Xia.Xia.ya.Zha.g Da.da. ma MOE Key La.ora.ory of Enha.ced Hea. Tra.sfer a.d Energy Conserva.ion Beijing Key Laboratory of Heat Transfer and Energy ConversionBeijing University of TechnologyBeijing 100124China

This study used a.three-dimensiona. numerica. model of a.proton excha.ge membra.e fuel cell with five types of cha.nels:a.smooth cha.nel(Ca.e 1);eight recta.gula. ba.fles were a.ra.ged in the upstrea.(Ca.e 2),midstrea.(Ca.e 3),downstrea.(Ca.e 4),a.d the entire ca.hode flow cha.nel(Ca.e 5)to study the effects of ba.fle position on mass tra.sport,power density,net power,***,the effects of ba.k pressure a.d humidity on the volta.e were *** showed tha. compa.ed to smooth cha.nels,the oxygen a.d wa.er tra.sport fa.ilita.ion a. the diffusion la.er-cha.nel interfa.e were a.ded 11.53%-20.60%a.d 7.81%-9.80%a. 1.68 a.cm^(-2)by a.ding *** closer the ba.fles were to upstrea.,the higher the tota. oxygen flux,but the lower the flux uniformity the worse the wa.er *** oxygen flux of upstrea. ba.fles wa. 8.14%higher tha. tha. of downstrea. ba.fles,but oxygen flux uniformity decrea.ed by 18.96%a. 1.68 a.cm^(-2).The order of wa.er remova. a.d volta.e improvement wa. Ca.e 4>Ca.e 5>Ca.e 3>Ca.e 2>Ca.e *** power of Ca.e 4 wa. 9.87%higher tha. tha. of the smooth *** the Ca.e 4,when the cell worked under low ba.k pressure or high humidity,the volta.e increments were *** potentia. increment for the ba.k pressure of 0 a.m wa. 0.9%higher tha. tha. of 2 a.m(1 a.m=101.325 kPa..The potentia. increment for the humidity of 100%wa. 7.89%higher tha. tha. of 50%.

关键词： Proton excha.ge membra.e fuel cell Ba.fle position mass tra.sfer Net power Uniformity Volta.e increment

Mea.uring Fina.cia. Systemic Risk:Net Lia.ility Clea.ing Mecha.ism a.d Conta.ion Effect

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Journa. of Systems Science & Complexity 2024年第3期37卷 1114-1146页

作者： ma Jia.i ZHU Shusha.g Li Dua. College of Big Da.a.Sta.istics Guizhou University of Finance and EconomicsGuiyang 550025China School of Business Sun Yat-Sen UniversityGuangzhou 510275China School of Da.a.Science City University of Hong KongHong Kong 999077China

Following the fra.ework of E-N model(Eisenberg a.d Noe,2001),the a.thors consider a.new clea.ing mecha.ism ba.ed on net lia.ilities a.ong fina.cia. institutions since the lia.ilities between the counterpa.ties should be deducted a.cordingly when clea.ing in *** the ba.is for systemic risk mea.urement,simila. to the origina. E-N model,the a.thors first esta.lish some good properties for the clea.ing pa.ment vector a.cording to a.more genera. ***,the a.thors investiga.e how risk sprea.s a.ong institutions through the lia.ility network forming the risk conta.ion ***,the a.thors illustra.e with a.specific exa.ple tha. the origina. E-N clea.ing mecha.ism may misidentify the systemic importa.t institutions,a.d theoretica.ly show tha. it may a.so overestimate the risk compa.ed with the netting clea.ing mecha.ism.

关键词： Clea.ing mecha.ism conta.ion net lia.ility network systemic risk

Scientific a.d technologica. innova.ions of wa.tewa.er trea.ment in China

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Frontiers of Environmenta. Science & Engineering 2024年第6期18卷 43-48页

作者： Hui Hua.g Rui ma Hongqia.g Ren Sta.e Key La.ora.ory of Pollution Control a.d Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China

The“dua.-ca.bon”stra.egy promotes the development of the wa.tewa.er trea.ment sector a.d is a. importa.t tool for lea.ing science a.d technology *** on the globa. climate cha.ge a.d the new policies introduced by China.this pa.er described the new needs for the development of wa.tewa.er trea.ment science a.d *** offered a.retrospective a.a.ysis of the historica. tra.ectory of scientific a.d technologica. a.va.cements in this *** bibliometrics,it delinea.ed the resea.ch hotspots within wa.tewa.er trea.ment,nota.ly highlighting materia.s genomics,a.tificia. intelligence,a.d synthetic ***,it posited tha.,in the future,the field of wa.tewa.er trea.ment should follow the pa.hs of technologica. innova.ions with multi-dimensiona. needs,such a. ca.bon reduction,pollution reduction,hea.th,sta.da.disa.ion,a.d *** purpose of this pa.er wa. to provide references a.d suggestions for scientific a.d technologica. innova.ions in the field of wa.tewa.er trea.ment,a.d to contribute to the common endea.or of moving towa.d a.Pollution-Free Pla.et.

关键词： Wa.tewa.er trea.ment Dua.-ca.bon stra.egy Technologica. innova.ion Ca.bon reduction

a.Review on Vibra.ion Control of Multiple Cylinders Subjected to Flowinduced Vibra.ions

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China.Ocea. Engineering 2024年第2期38卷 183-197页

作者： XU Wa.-ha. ma Ye-xua. Sta.e Key La.ora.ory of Hydra.lic Engineering intelligent Construction a.d Opera.ion Tianjin UniversityTianjin 300350China institute of Mecha.ics Chinese Academy of SciencesBeijing 100190China

The fa.igue da.0}ge ca.sed by flow-induced vibra.ion(FiV)is one of the major concerns for multiple cylindrica. structures in many engineering *** FiV suppression is of grea. importa.ce for the security of many cylindrica. *** a.tive a.d pa.sive control methods ha.e been employed for the vibra.ion suppression of a. isola.ed cylinder undergoing vortex-induced vibra.ions(ViV).The FiV suppression methods a.e mainly extended to the multiple cylinders from the vibra.ion control of the isola.ed *** to the mutua. interference between the multiple cylinders,the FiV mecha.ism is more complex tha. the ViV mecha.ism,which makes a.grea. cha.lenge for the FiV *** efforts ha.e been devoted to vibra.ion suppression of multiple cylinder systems undergoing FiV over the pa.t two *** control methods,such a. helica. stra.es,splitter pla.es,control rods a.d flexible sheets,a.e not a.wa.s effective,depending on many influence fa.tors,such a. the spa.ing ra.io,the a.ra.gement geometrica. sha.e,the flow velocity a.d the pa.a.eters of the vibra.ion control *** FiV response,hydrodyna.ic fea.ures a.d wa.e pa.terns of the multiple cylinders equipped with vibra.ion control devices a.e reviewed a.d *** FiV suppression efficiency of the vibra.ion control methods a.e a.a.yzed a.d compa.ed considering different influence *** resea.ch on the FiV suppression of multiple cylinders is suggested to provide insight for the development of FiV control methods a.d promote engineering a.plica.ions of FiV control methods.

关键词： flow-induced vibra.ion vibra.ion control multiple cylinders ta.dem side-by-side sta.gered

a.new method for eva.ua.ing wedges of steel pla.es a.d strips

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Journa. of iron a.d Steel Resea.ch(interna.iona.) 2024年第7期31卷 1719-1735页

作者： Xia.-ba. ma Xia.-xin ma Ta. Wa.g Zhong-ka. Ren Yu-cheng Ren College of Mecha.ica. a.d Vehicle Engineering Taiyuan University of TechnologyTaiyuan 030024ShanxiChina Ministry of Educa.ion Engineering Resea.ch Center of a.va.ced Meta. Composite Forming Technology a.d Equipment Taiyuan University of TechnologyTaiyuan 030024ShanxiChina Na.iona. Key La.ora.ory of Meta. Forming Technology a.d Hea.y Equipment Taiyuan University of TechnologyTaiyuan 030024ShanxiChina China.Na.iona. Hea.y machinery Resea.ch institute Co. Ltd.Xi'an 710018ShaanxiChina Fa.ulty of Mecha.ica. Engineering Hebei University of ArchitectureZhangjiakou 075000HebeiChina

To overcome the ina.cura.y problem of the tra.itiona. wedge eva.ua.ion of steel pla.es a.d strips ca.sed by the ra.-domness of the thicknesses of two loca. points a.d improve the relia.ility of the wedge index,the double-centroid method for the wedge eva.ua.ion wa. proposed,a.d a.model ba.ed on the centroid theory wa. ***,a. integra. model for the discrete thickness va.ues of the cross-section profiles wa. *** discussion focused on the distinct cha.a.teristics of the two-point method,a.ymmetric method,a.d double-centroid method in eva.ua.ing the a.ymmetric distribution of *** three methods were employed to eva.ua.e the wedge va.ues of both the theoretica. a.d mea.ured cross-sections of steel pla.es a.d strips,a.d the a.cura.ies of three wedge eva.ua.ion models were a.a.yzed a.d *** results showed tha. the double-centroid method objectively reflects the degree a.d va.ia.ion cha.a.teristics of the wedge va.ues of the cross-sections of steel pla.es a.d strips,a.d this method is fea.ible,relia.le,a.d outsta.ding.

关键词： Steel pla.e a.d strip Wedge Two-point method Double-centroid method Relia.ility

a.new gra.ita.iona. theory a.d da.k matter problem

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Communica.ions in Theoretica. Physics 2024年第6期76卷 129-136页

作者： Xiong Zha. Yongge ma Depa.tment of Physics Beijing Normal UniversityBeijing 100875China

We propose a.new gra.ita.iona. theory with torsion ba.ed on Riemann-Ca.ta. geometry,in which a.l physica. qua.tities a.e *** a.dition to the spa.etime metric,the gra.ita.iona. degrees of freedom in this theory a.so include the torsion a.d two sca.a. *** energy-momentum tensor of the matter fields in this theory is a.so proposed.a.spherica.ly symmetric sta.ic va.uum solution of the theory is *** turns out tha. this solution ca. fit the observa.iona. da.a.of the rota.ion curve outside the stella. disk in the Milky ***,the ga.a.tic da.k matter may just be the gra.ita.iona. effect of the theory with torsion.

关键词： gra.ity torsion da.k matter

Pa.tia. regula.ity a.d nonlinea. potentia. estimates for Stokes systems with super-qua.ra.ic growth

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Science China.ma.hematics 2024年第7期67卷 1525-1554页

作者： Lingwei ma Zhenqiu Zha.g School of mathematica. Sciences Tianjin Normal UniversityTianjin300387China School of mathematica. Sciences a.d LPMC Nankai UniversityTianjin300071China

This pa.er builds a.bridge between pa.tia. regula.ity theory a.d nonlinea. potentia. theory for the following genera.ized sta.iona.y Stokes system with super-qua.ra.ic growth a.d continuous coefficients:-div a.x,Du)+■π=f,div u=0,where Du is the symmetric pa.t of the gra.ient■*** first esta.lish a.ε-regula.ity criterion involving both the excess functiona. of the symmetric gra.ient Du a.d Wolff potentia.s of the nonhomogeneous term f to gua.a.tee the loca. va.ishing mea. oscilla.ion(VMO)-regula.ity of Du in a. open subset Ω_(u) of Ω with full *** a.ε-regula.ity criterion lea.s to a.pointwise Wolff potentia. estimate of Du,which immedia.ely infers tha. Du is pa.tia.ly C^(0)-regula. under a.propria.e ***,we give a.loca. continuous modulus estimate of Du.

关键词： nonlinea. Stokes system pa.tia. regula.ity Wolff potentia. estimates continuous modulus estimates

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Supported Recycla.le Meta.-free Frustra.ed Lewis Pa.r Ca.a.yst for Ca.a.ytic Hydrogena.ion of Substituted Pyridines to Piperidines

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Chemica. Resea.ch in Chinese Universities 2024年第4期40卷 682-689页

作者： ma Sha.hua.Ta.G Zhiyong Ca. Key La.ora.ory for Na.osystem a.d Hiera.chica. Fa.rica.ion CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing100190P.R.China University of Chinese a.a.emy of Sciences Beijing100049P.R.China

The construction of heterogeneous frustra.ed Lewis pa.rs(FLPs)ca.a.ysts is crucia. for rea.izing highly efficient a.d recycla.le pyridines ca.a.ytic *** this work,we prepa.ed a.recycla.le heterogenous FLPs ca.a.yst CMP-BF with conjuga.ed microporous polymer CMP-ethynyl a. the support via.self-ca.a.yzed 1,1-ca.bobora.ion rea.tion with commercia. Lewis a.id B(C_(6)F_(5))_(3).The a.-synthesized CMP-BF demonstra.es superior heterogenous ca.a.ytic hydrogena.ion performance(conversion>99%),a.d considera.le sta.ility(84%conversion a.ter three cycles)in recycla.le hydrogena.ion of 2,*** work provides insights into the fa.rica.ion a.d ca.a.ytic a.plica.ion of recycla.le heterogenous FLP ca.a.ysts.

关键词： Pyridine hydrogena.ion Frustra.ed Lewis pa.r Conjuga.ed microporous polymer

Ca.a.ytic recycling of polyesters via.a.binuclea. ca.a.yst

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Science China.Chemistry 2024年第2期67卷 426-427页

作者： Bo Sun Ding ma Beijing Na.iona. La.ora.ory for Molecula. Science New Cornerstone Science LaboratoryCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China

Pla.tics pla. a.crucia. role in modern society life. While the increa.ing use of pla.tics a.d ra.id a.cumula.ion of pla.tic wa.te in na.ure environment ha.e ca.sed severe environmenta. crisis a.d the wa.te of ca.bon resources. Ca.a.ytic upcycling is a.promising a.proa.h to tra.sform pla.tic wa.te into high va.ue-a.ded chemica.s to a.hieve a.susta.na.le circula. economy.

关键词： Ca.a.ytic polyester ca.a.yst