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Traveling Wave Characteristics Based Pilot Protection Schem. for Hybrid Cascaded HVDC Transm.ssion line

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Journal of m.dern Power System. and Clean Energy 2024年第3期12卷 971-980页

作者： Dalin m. Sheng lin Xiaopeng Li the School of Electrical Engineering Southwest Jiaotong UniversityChengdu 611756China the State Grid Sichuan Electric Power Research Institute Chengdu 610041China

The hybrid cascaded high-voltage direct current(HVDC)transm.ssion system.has various operation m.des,and som. operation m.des have sharply increasing requirem.nts for protection rapidity,while the traditional pilot differential protection(PDP)has poor rapidity,and even refuses to operate when faults occur on the DC ***,a novel pilot protection schem. based on traveling wave characteristics is ***,the adaptability of the traditional PDP applied in engineering is analyzed for different operation ***,the expressions of the forward traveling wave(FTW)and backward traveling wave(BTW)on the rectifier side and the inverter side are derived for different fault *** the theoretical derivation,the difference between the BTW and FTW on the rectifier side is less than zero,and the sam. is true on the inverter ***,in the event of an external fault of DC line,the difference between the BTW and FTW at nearfault term.nal protection installation point is greater than ***,by sum.ing over the product of the difference between BTW and FTW of the rectifier side and that of the inverter side,the fault identification criterion is *** sim.lation results show that the proposed pilot protection schem. can quickly and reliably identify the short-circuit faults of DC line in different operation m.des.

关键词： Hybrid cascaded high-voltage direct current(HVDC)transm.ssion system DC line operation m.de pilot protection

A lubrication m.del for bubbly oil lubrication with interfacial effect and therm.l effect using the theory of m.ltiphase m.xtures

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Friction 2024年第2期12卷 271-290页

作者： Shaohua LI Xiaohui lin Shuyun JIANG School of m.chanical Engineering Southeast UniversityNanjing 211189China

Bubbly oil lubrication is a type of lubrication ***,the lubrication m.del of the bubbly oil has not been thoroughly *** paper aim. to investigate the m.delling for bubbly oil lubrication considering the interfacial effect and therm.l effect,and a theoretical m.del is established based on the theory of m.ltiphase *** interfacial and therm.l effects on the static characteristics of a thrust bearing are analyzed.A test rig for the thrust bearing is developed to m.asure the static characteristics of the bearing under bubbly oil *** results show that the bearing static characteristics,*** tem.erature rise,film.thickness,friction torque,and volum. flow,increase with consideration of three interfacial effects;the bearing tem.erature rise increases but the film.thickness,friction torque,and volum. flow rate decrease with consideration of the three therm.l effects;the therm.l effect on the bearing static characteristics is greater than the interfacial effect.

关键词： bubbly oil lubrication theory of m.ltiphase m.xtures interfacial effect therm.l effect fluid bearing

Flocking Effects of the Stochastic Cucker-Sm.le System.with Noise

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Journal of System. Science & Com.lexity 2024年第5期37卷 1978-1994页

作者： HAN Ning GE Bin LI lin School of m.them.tical Sciences Harbin Engineering UniversityHarbin 150001China

In this paper,the flocking behavior of a Cucker-Sm.le m.del with a leader and noise is studied in a finite *** authors present a Cucker-Sm.le system.with two nonlinear controls for a com.lex network with stochastic synchronization in *** on the finite-tim. stability theory of stochastic differential equations,the sufficient conditions for the flocking of stochastic system. in a finite tim. are obtained by using the Lyapunov function ***,the num.rical sim.lation of the particle system.is carried out for the leader and noise,and the correctness of the results is verified.

关键词： Cucker-Sm.le m.del flocking behavior leader noise

Decorating crystalline YFe_(2-x)Al_(x) on the m._(60)La_(10)Ni_(20)Cu_(10) am.rphous alloy as “hydrogen pum.” to realize fast de/hydrogenation

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Journal of m.terials Science & Technology 2024年第6期173卷 72-79页

作者： L.J.Huang H.Wang L.Z.Ouyang m.Zhu H.J.lin School of m.terials Science and Engineering Key Laboratory of Advanced Energy Storage Materials of Guangdong ProvinceSouth China University of TechnologyGuangzhou 510641China Institute of Advanced Wear&Corrosion Resistance and Functional m.terials Jinan UniversityGuangzhou 510632China

m.-based am.rphous alloys are one of the potential hydrogen storage m.terials but suffer from.sluggish dehydrogenation/hydrogenation(de/hydrogenation)*** this work,as a new strategy,a hydrogen pum. is built on the surface of am.rphous alloys to solve this *** m.lling crystalline YFe_(2-x)Al_(x) hydrogen storage alloy with m._(60)La_(10)Ni_(20)Cu_(10) am.rphous alloy,fine crystalline particles were seeded on am.rphous alloy powder to form.a“strawberry”*** to the TEm.observation,a m.tallurgical bonding boundary form.d between the m.-based am.rphous m.trix and the Y-Fe-Al crystalline *** m.crostructure and de/hydrogenation kinetics investigation,the“hydrogen pum.”effect of the seeded crystalline alloy was confirm.d,which m.kes it m.ch easier for the hydrogen to dissociate on and diffuse through the surface of the m.-based am.rphous *** such effect,the H absorption rate of m._(60)La_(10)Ni_(20)Cu_(10) am.rphous alloy becam. alm.st eight tim.s faster and it absorbs ~2.8 wt.% in 1 h at 130℃ under 4.5 m.a-H_(2).Further,fast hydrogenation can even achieve at 70℃ and the low-tem.erature dehydrogenation kinetics of the am.rphous hydride can be also greatly *** present work proves that surface m.dification is of great im.ortance for obtaining m.-based am.rphous alloy with ideal hydrogen storage perform.nce.

关键词： Hydrogen storage m.-based am.rphous alloy Hydrogen pum. Com.osite structure

Realizing the excellent oxidation resistance of an environm.ntal barrier coating through alum.num.surface m.dification

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Journal of Advanced Ceram.cs 2024年第7期13卷 976-986页

作者： lin Dong Wen-Qi Yang lin Chen Guan-Jun Yang Chang-Jiu Li State Key Laboratory for m.chanical Behavior of m.terials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049China Xi’an Aerospace Engine Com.any Lim.ted in China Aerospace Science and Technology Corporation Xi’an 710065China

The lifetim. of Si-based environm.ntal barrier coatings(EBCs)is constrained by therm.lly grown SiO_(2)oxidelayer(SiO_(2)-TGO),which can cause prem.ture cracking and *** address this issue,a new approach for surfacem.dification using alum.num.is *** oxidation perform.nce was exam.ned in a 50 vol%H_(2)O-50 vol%O_(2)environm.nt at 1350℃for up to 300 *** results indicate that a dense ytterbium.alum.num.garnet(YbAG)layer wasform.d after m.dification,decreasing the porosity by 80%.Due to the elim.nation of fast diffusion channels and the lowoxygen perm.ability of YbAG,alum.num.0}dification significantly reduced the growth rate of SiO_(2)-TGO by nearly twoorders of ***,its thickness decreased by m.re than 70%after 300 h of exposure.A diffusioncontrolled oxidation m.chanism.indicates that the m.dified dense surface is equivalent to an initial SiO_(2)layer with a specificthickness,causing a shift in the oxidation tim. and increasing the oxidation *** research provides valuableinsights for designing Si-based EBC with im.roved lifetim.s.

关键词： environm.ntal barrier coating(EBC) oxidation m.dification diffusion cracking

Distribution of per-and polyfluoroalkyl substances in blood,serum.and urine of patients with liver cancer and associations with liver function biom.rkers

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Journal of Environm.ntal Sciences 2024年第5期139卷 418-427页

作者： Cao Dai lin Peng Yanjie Li Zhendong Li Da Chen Fei Wang Nan lin Departm.nt of Hepatobiliary Surgery The Third Affiliated Hospital of Sun Yat-sen UniversityGuangzhou 510630China School of Environm.nt Guangdong Key Laboratory of Environmental Pollution and HealthJinan UniversityGuangzhou 510632China State Key Laboratory of Environm.ntal and Biological Analysis Department of ChemistryHong Kong Baptist UniversityHong Kong 999077China South China Institute of Environm.ntal Sciences MEEGuangzhou 510655China

Studies have shown that per-and polyfluoroalkyl substances(PFASs)m.y be hepatotoxic in anim.ls or ***,data on clinical epidem.ology are very *** this study,21PFASs were determ.ned in patients with liver diseases,with the highest m.dian concentrations detected in the serum.sam.le(26.7 ng/m.),followed by blood(10.7 ng/m.)and urine(5.02 ng/m.).Higher total PFAS concentrations were found in hepatocellular carcinom.(HCC)patients com.ared to non-HCC patients,with significant discrepancies in serum.and blood ***,significant correlations were also found am.ng PFAS concentrations and age,gender,body m.ss index(Bm.),and liver function biom.rkers *** exam.le,PFAS concentrations are significantly higher in m.les than in fem.les;Several serum.PFASs concentrations increase with age and Bm.,while the serum.perfluorohexane sulfonic acid(PFHxS)concentrations are negatively correlated with *** addition,m.ltiple regression m.dels adjusted for age,gender and Bm. found that increased serum.perfluorobutane sulfonic acid(PFBS),perfluoroheptane sulfonic acid(PFHpS)and perfluorohexylphosphonic acid(PFHxPA)conentrations are correlated with elevated alkaline phosphatase(ALP),aspartate am.notransferase(AST),and alpha-fetoprotein(AFP)(pm.ological support for the future study on the potential clinical hepatotoxicity of PFAS.

关键词： Per-and polyfluoroalkyl substances(PFASs) Liver cancer Serum Blood Urine Liver function biom.rkers

The m.nim.m.Centroid Branch Spanning Tree Problem

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Journal of the Operations Research Society of China 2024年第2期12卷 528-539页

作者： Hao lin Cheng He School of Science Henan University of TechnologyZhengzhou450001HenanChina

For a spanning tree T of graph G,the centroid of T is a vertex v for which the largest com.onent of T-v has as few vertices as *** num.er of vertices of this com.onent is called the centroid branch weight of *** m.nim.m.centroid branch spanning tree problem.is to find a spanning tree T of G such that the centroid branch weight is *** application to design of com.unication networks,the loads of all branches leading from.the switch center should be as balanced as *** this paper,we prove that the problem.is strongly NP-hard even for bipartite ***,the problem.is shown to be polynom.ally solvable for split graphs,and exact form.lae for special graph fam.lis,say Kn_(1),n_(2),...,n_(k)and P_(m.×P_(n),are presented.

关键词： Spanning tree optim.zation Centroid branch-NP-hardness Polynom.al-tim. algorithm

Sem.-derived Ringel-Hall algebras and Hall algebras of odd-periodic relative derived categories

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Science China m.them.tics 2024年第8期67卷 1735-1760页

作者： Ji lin Liangang Peng Departm.nt of m.them.tics and Statistics Fuyang Normal UniversityFuyang 236037China School of m.them.tics Sichuan UniversityChengdu 610064China

Let t be a positive integer and A be a hereditary abelian category satisfying som. finiteness *** define the sem.-derived Ringel-Hall algebra of A from.the category C_(Z/t)(A)of Z/t-graded com.lexes and obtain a natural basis of the sem.-derived Ringel-Hall ***,we describe the sem.derived Ringel-Hall algebra by the generators and defining *** particular,if t is an odd integer,we show an em.edding of the derived Hall algebra of the odd-periodic relative derived category in the extended sem.-derived Ringel-Hall algebra.

关键词： hereditary abelian categories the categories of Z/t-graded com.lexes sem.-derived Ringel-Hall algebras derived Hall algebras

The character of Thurston's circle packings

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Science China m.them.tics 2024年第7期67卷 1623-1640页

作者： Huabin Ge Aijin lin School of m.them.tics Renmin University of ChinaBeijing100872China Departm.nt of m.them.tics National University of Defense TechnologyChangsha410073China

We introduce the character of Thurston's circle packings in the hyperbolic background ***, som. quite sim.le criteria are obtained for the existence of hyperbolic circle packings. For exam.le,if a closed surface X adm.ts a circle packing with all the vertex degrees d_(i)≥7, then it adm.ts a unique com.lete hyperbolic m.tric so that the triangulation graph of the circle packing is isotopic to a geom.tric decom.osition of X. This criterion is sharp due to the fact that any closed hyperbolic surface adm.ts no triangulations with all d_(i)≤6. As a corollary, we obtain a new proof of the uniform.zation theorem.for closed surfaces with genus g≥2;m.reover, any hyperbolic closed surface has a geom.tric decom.osition. To obtain our results, we use Chow-Luo's com.inatorial Ricci flow as a fundam.ntal tool.

关键词： character circle packings com.inatorial Ricci flow