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Permutation orbifolds of vertex operator superalgebras and associative algebras

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Science China Mathematics 2025年第1期68卷 19-38页

作者： Chongying Dong Feng xu Nina Yu Department of Mathematics University of California at Santa CruzSanta CruzCA 95064USA Department of Mathematics Huzhou UniversityHuzhou 313000 China Department of Mathematics University of California at RiversideRiversideCA 92521USA School of Mathematical Sciences Xiamen UniversityXiamen 361005China

Let V be a vertex operator superalgebra and g=(12···k)be a k-cycle which is viewed as an automorphism of the tensor product vertex operator superalgebra V^(■k).In this paper,we construct an explicit isomorphism from A_(g)(V^(■k))to A(V)if k is odd and to Aσ(V)if k is even whereσis the canonical automorphism of V of order 2 determined by the superspace structure of *** recover previous results by Barron(2016)and Barron and Vander Werf(2014)that there is a one-to-one correspondence between irreducible g-twisted V^(■k)-modules and irreducible V-modules(***σ-twisted V-modules)when k is odd(***).This explicit isomorphism is expected to be useful in our further study on the Zhu algebra of the fixed point subalgebra.

关键词： permutation orbifold vertex operator superalgebra Zhu algebra

A polynomial resultant approach to algebraic constructions of extremal graphs

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Science China Mathematics 2025年第2期68卷 485-506页

作者： Tao Zhang Zixiang xu Gennian Ge Institute of Mathematics and Interdisciplinary Sciences Xidian UniversityXi’an 710071China School of Mathematical Sciences Capital Normal UniversityBeijing 100048China

The Turán problem asks for the largest number of edges ex(n,H)in an n-vertex graph not containing a fixed forbidden subgraph H,which is one of the most important problems in extremal graph ***,the order of magnitude of ex(n,H)for bipartite graphs is known only in a handful of *** particular,giving explicit constructions of extremal graphs is very challenging in this *** this paper,we develop a polynomial resultant approach to the algebraic construction of explicit extremal graphs,which can efficiently decide whether a specified structure exists.A key insight in our approach is the multipolynomial resultant,which is a fundamental tool of computational algebraic *** main results include the matched lower bounds on the Turán number of 1-subdivision of K3,t1and the linear Turán number of the Berge theta hypergraph■_(3,t_(2))^(B).where t_(1)=25 and t_(2)=***,the constant t1improves the random algebraic construction of Bukh and Conlon(2018)and makes the known estimation better on the smallest value of t1concerning a problem posed by Conlon et al.(2021)by reducing the value from a magnitude of 10^(56)to the number 25,while the constant t_(2)improves a result of He and Tait(2019).

关键词： Turan number resultant algebraic construction subdivision Berge theta hypergraph

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医院科研激励机制存在的问题及策略

中华医学科研管理杂志 2016年第6期29卷 412-415页

作者：张鹏俊苗苗许扬于玲玲冯宝华彭博杨杰孚国家老年医学中心北京医院科研处 100730 首都医科大学卫生管理与教育学院

科技水平是医院的核心竞争力之一.医院科研人员是从事科研创新活动的主体.建立科学有效的科研激励机制是激发科研人员创新潜能、促进医院发展的重要途径.本文通过文献调研并结合所在医院科研激励实施过程中的体会,总结了目前医院科研激... 详细信息

科技水平是医院的核心竞争力之一.医院科研人员是从事科研创新活动的主体.建立科学有效的科研激励机制是激发科研人员创新潜能、促进医院发展的重要途径.本文通过文献调研并结合所在医院科研激励实施过程中的体会,总结了目前医院科研激励机制普遍存在的问题,提出相应的措施及建议,为完善科研激励机制提供思路.

关键词：医院科学研究激励机制

Novel Matching Strategy for the Coupling of Heat Flux in Furnace Side and CO_(2)Temperature in Tube Side to Control the Cooling Wall Temperatures

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Journal of Thermal Science 2021年第4期30卷 1251-1267页

作者： LIU Chao miao Zheng xu Jinliang xu Zeyu LI Mingjia Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power UniversityBeijing 102206China Key Laboratory of Power Station Energy Transfer Conversion and System North China Electric Power UniversityMinistry of EducationBeijing 102206China Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education School of Energy&Power EngineeringXi’an Jiaotong UniversityXi’an 710049China

Required by the supercritical carbon dioxide(s CO_(2))coal-fired power cycle,s CO_(2)entering a boiler has a high temperature and can cause overheating of *** eliminate the pressure drop penalty effect,the s CO_(2)boiler consists of several modules,each having different heat flux received from the furnace side(q)and different CO_(2)temperature in the cooling wall tube(T_f).We aim to search for the best matching strategy coupling furnace side and tube side to obtain the lowest temperature of *** theoretically analyzing the wall temperature influenced by q,T_f and a comprehensive thermal resistance C,two matching methods are introduced:the heat flux-temperature matching(HTM)which matches higher q with lower T_f,and the heat flux-heat flux matching(HHM)that matches higher q with higher allowable-heat-flux at the temperature limit of *** is a conventional method but HHM is newly proposed *** show that,if C is identical for different modules,the two methods coincide;otherwise,HHM is *** a s CO_(2)boiler driving 1000 MWe power plant,smaller cooling wall temperatures are obtained by HHM than *** on HHM,the mid-partition wall,heat transfer enhancement,and downward flow are comprehensively used,decreasing the wall temperature significantly.

关键词： sCO_(2)power cycle sCO_(2)modular boiler cooling wall temperature allowable heat flux matching strategy

Translative containment measure and symmetric mixed isohomothetic inequalities

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Science China Mathematics 2015年第12期58卷 2593-2610页

作者： LUO miao xu Wenxue ZHOU JiaZu School of Mathematics and Statistics Southwest University School of Mathematics and Computer Science Guizhou Normal University School of Mathematical Sciences Kaili University Department of Computer Science Southeast Guizhou Vocational College of Technology for Nationalities

We first investigate the translative containment measure for convex domain K0 to contain, or to be contained in, the homothetic copy of another convex domain K1, i.e., given two convex domains K0, K1 of areas A0, A1, respectively, in the Euclidean plane R2, is there a translation T so that t(T K1)  K0 or t(T K1) ? K0 for t > 0? Via the translative kinematic formulas of Poincar′e and Blaschke in integral geometry,we estimate the symmetric mixed isohomothetic deficit σ2(K0, K1) ≡ A201- A0A1, where A01 is the mixed area of K0 and K1. We obtain a sufficient condition for K0 to contain, or to be contained in, t(T K1). We obtain some Bonnesen-style symmetric mixed isohomothetic inequalities and reverse Bonnesen-style symmetric mixed isohomothetic inequalities. These symmetric mixed isohomothetic inequalities obtained are known as Bonnesen-style isopermetric inequalities and reverse Bonnesen-style isopermetric inequalities if one of domains is a disc. As direct consequences, we obtain some inequalities that strengthen the known Minkowski inequality for mixed areas and the Bonnesen-Blaschke-Flanders inequality.

关键词： translative containment measure symmetric mixed isohomothetic deficit symmetric mixed isohomothetic inequality Bonnesen-style symmetric mixed isohomothetic inequality reverse Bonnesen-style symmetric mixed isohomothetic inequality

Quantile-based optimization under uncertainties for complex engineering structures using an active learning basis-adaptive PC-Kriging model

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Chinese Journal of Aeronautics 2025年第1期38卷 340-352页

作者： Yulian GONG Jianguo ZHANG Dan xu Ying HUANG School of Reliability and Systems Engineering Beihang UniversityBeijing 100191China

The Reliability-Based Design Optimization(RBDO)of complex engineering structures considering uncertainties has problems of being high-dimensional,highly nonlinear,and timeconsuming,which requires a significant amount of sampling simulation *** this paper,a basis-adaptive Polynomial Chaos(PC)-Kriging surrogate model is proposed,in order to relieve the computational burden and enhance the predictive accuracy of a *** active learning basis-adaptive PC-Kriging model is combined with a quantile-based RBDO ***,five engineering cases have been implemented,including a benchmark RBDO problem,three high-dimensional explicit problems,and a high-dimensional implicit *** with Support Vector Regression(SVR),Kriging,and polynomial chaos expansion models,results show that the proposed basis-adaptive PC-Kriging model is more accurate and efficient for RBDO problems of complex engineering structures.

关键词： Reliability-based design optimization Quantile-based Basis-adaptive PC-Kriging Complex engineering structures Active learning Uncertainty

Decoupling the roles of grain boundary strength and grain size hidden in grain-level electro-chemo-mechanical failure of solid-state electrolyte

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Journal of Energy Chemistry 2025年第2期101卷 685-691页

作者： Ming xu xuyang Wang Zhengqian Jin Xingxing Jiao Ya Gao Zhongxiao Song Xieyu xu Kai Xi Yangyang Liu School of Chemistry Engineering Research Center of Energy Storage Materials and Devices Ministry of Education Xi'an Jiaotong University State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Research Institute of Frontier Science Southwest Jiaotong University School of Instrument Science and Technology Xi'an Jiaotong University

Garnet lithium lanthanum zirconium oxide(Li7La3Zr2O12,LLZO) is a benchmark solid-state electrolyte（SSE） material receiving considerable attention owing to its high conductivity and chemical stability against Li *** its electro-chemo-mechanical failure mechanisms have been much investigated,the equivocal roles of grain boundary strength and grain size of LLZO remain under-explored,hindering further performance *** we decoupled the effects of grain size and grain boundary strength of polycrystalline LLZO via the combination of electrochemical kinetics and the cohesive zone *** discovered that the disintegration of LLZO is initiated by the accumulation of local displacements,which strongly relates to the changes in both grain size and grain boundary ***,variations in grain boundary strength affect the diffusion and propagation pathways of damage,while the failure of LLZO is determined by the grain *** LLZO grains facilitate transgranular damage under low grain boundary strength,which can alter local chemo-mechanics within the bulk of LLZO,leading to more extensive damage *** results showcase the structure optimization pathways by preferentially controlling the growth of lithium dendrites at grain boundaries and their penetration in garnet-type SSE.

关键词： Electro-chemo-mechanics Grain boundary Growth of lithium metal Solid-state electrolyte

Understanding the iodine electrochemical behaviors in aqueous zinc batteries

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Journal of Energy Chemistry 2025年第2期101卷 402-415页

作者： xuefang Xie Xiaoxin xu Shuquan Liang Guozhao Fang College of Physical Science and Technology Xinjiang University Xinjiang Key Laboratory of Solid State Physics and Devices Xinjiang University School of Materials Science & Engineering Key Laboratory of Electronic Packaging and Advanced Functional Materials of Hunan Province Central South University National Energy Metal Resources and New Materials Key Laboratory Central South University

Iodine is widely used in aqueous zinc batteries（ZBs） due to its abundant resources,low cost,and active redox *** addition to the active material in zinc-iodine batteries,iodine also plays an important role in other ZBs,such as regulating the electrochemical behavior of zinc ions,promoting the reaction kinetic and reversibility of other redox pairs,catalytic behaviors related to iodine reactions,coupling with other halogen ions,shuttle behaviors of polyiodides,***,there is currently a lack of comprehensive discussion on these ***,this review provides a comprehensive overview of the electrochemical behaviors of iodide in the aqueous *** effect of iodine ions on the Zn2+desolvation behaviors and the interfacial behaviors of Zn anode was *** redox pairs boosting other redox pairs,such as MnO2/Mn2+redox pair and vanadium redox pair to obtain high reversibility and capacity was also ***,the catalytic behaviors related to iodine reactions in aqueous ZBs,synergistic reaction with other halogen ions and suppression of shuttle behaviors for high performance zinc-iodine batteries were systematically ***,future prospects for designing effective iodine electrochemical behaviors with practicability are proposed,which will provide scientific guidance for the practical application of iodine-related aqueous ZBs.

关键词： Catalytic behavior Iodide ion Redox pairs Shuttle effect Zinc batteries

Applications of in-situ solid-state nuclear magnetic resonance in methanol to olefins reaction

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Science China Chemistry 2025年第1期68卷 134-151页

作者： Jing Niu Shutao xu Yingxu Wei Zhongmin Liu National Engineering Research Center of Lower-Carbon Catalysis Technology Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China University of Chinese Academy of Sciences Beijing 100049China

The methanol-to-olefins(MTO)reaction offers an alternative pathway for the production of low-carbon olefins from non-oil *** research has been impeded by a lack of comprehensive understanding of its underlying mechanism,despite the significant progress made in ***-situ solid-state nuclear magnetic resonance(ss NMR)spectroscopy has emerged as a pivotal tool,offering crucial insights into key species under real-time operando ***,the host–guest interaction between zeolites or surface species residing on zeolites and the reactant/active intermediates is revealed by the combination of in-situ^(13)C MAS NMR and 2D correlation ***,recent technological advancements in hyperpolarization(HP)methods,including HP^(129)Xe NMR and dynamic nuclear polarization(DNP),have significantly improved the sensitivity of ssNMR,enabling detailed structural and kinetic analysis as well as the detection of trace *** this feature article,we summarized recent advancements in(in-situ)ssNMR spectroscopy applied to MTO reaction processes,encompassing mechanistic investigations at various stages and the intricate host–guest *** theoretical insights into the dynamic evolution of MTO reactions lay a solid foundation for the optimization of catalytic processes and the development of efficient catalysts,thereby advancing the techniques towards more sustainable and economical production route for olefins.

关键词： MTO zeolites in-situ ssNMR reactive intermediates reaction mechanism