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THE STEP-TRANSITION OPERATORS FOR MULTI-STEP METHODS OF ODE'S

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Journal of Computational Mathematics 1998年第3期16卷 193-202页

作者： feng k.(ICMSEC, Chinese Academy of Sciences) 中科院计算数学与科学工程计算所北京

In this paper, we propose a new definition of symplectic multistep methods. This definition differs from the old ones in that it is given via the one step method defined directly on M which is corresponding to the m step scheme defined on M while the old definitions are given out by defining a corresponding one step method on M × M ×…× M = Mm with a set of new variables. The new definition gives out a steptransition operator g: M → M. Under our new definition, the Leap-frog method is symplectic only for linear Hamiltonian systems. The transition operator g will be constructed via continued fractions and rational approximations.

关键词： Multi-step methods Explik. and loglik. function Fractional and rational approximation Simplecticity of LMM Nonexistence of SLMM.

THE CALCULUS OF GENERATING FUNCTIONS AND THE FORMAL ENERGY FOR HAMILTONIAN ALGORITHMS

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Journal of Computational Mathematics 1998年第6期16卷 481-498页

作者： feng k.(ICMSEC, Chinese Academy of Sciences) ICMSEC Chinese Academy of Sciences China

In [2-4], symplectic schemes of arbitrary order are constructed by generating functions. However the construction of generating functions is dependent on the chosen coordinates. One would lik. to k.ow that under what circumstance the construction of generating functions will be independent of the coordinates. The generating functions are deeply associated with the conservation laws, so it is important to study their properties and computations. This paper will begin with the study of Darboux transformation, then in section 2, a normalization Darboux transformation will be defined naturally. Every symplectic scheme which is constructed from Darboux transformation and compatible with the Hamiltonian equation will satisfy this normalization condition. In section 3, we will study transformation properties of generator maps and generating functions. Section 4 will be devoted to the study of the relationship between the invariance of generating functions and the generator maps. In section 5, formal symplectic erengy of symplectic schemes are presented.

关键词： generating function calculus of generating functions Darboux transformation cotangent bundles Lagrangian submanifold invariance of generating function formal energy

Talin and k.ndlin： the one-two punch in integrin activation

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Frontiers of Medicine 2014年第1期8卷 6-16页

作者： feng Ye Adam k. Snider Mark.H. Ginsberg Department of Medicine University of California San Diego La Jolla CA 92093 USA

Proper cell-cell and cell-matrix contacts mediated by integrin adhesion receptors are important for development, immune response, hemostasis and wound healing. Integrins pass trans-membrane signals bidirectionally through their regulated affinities for extracellular ligands and intracellular signaling molecules. Such bidirectional signaling by integrins is enabled by the conformational changes that are often link.d among extracellular, transmembrane and cytoplasmic domains. Here, we review how talin-integrin and k.ndlin-integrin interactions, in cooperation with talin-lipid and k.ndlin-lipid interactions, regulate integrin affinities and how the progress in these areas helps us understand integrin-related diseases.

关键词： signal transduction transmembrane domain nanodisc integrin talin k.ndling cell adhesion

Uncovering Microstructure-Property Relationship in Ni-Alloyed Fe-Mn-Al-C Low-Density Steel Treated by Hot-Rolling and Air-Cooling Process

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Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 713-725页

作者： Xiaoliang Jia Guhui Gao Xiaolu Gui Chun feng R.D.k.Misra Bingzhe Bai School of Mechanical Electronicand Control EngineeringBeijing Jiaotong UniversityBeijing100044China CNPC Tubular Goods Research Institute Xi’an710077China Laboratory for Excellence in Advanced Steel Research University of Texas at El PasoEl PasoTX79968-0521USA School of Material Science and Engineering Key Laboratory of Advanced Materials of Ministry of EducationTsinghua UniversityBeijing100084China

This paper focuses on the relationship between the microstructure and tensile properties of Fe-Mn-Al-C low-density high-strength steel processes by hot-rolling and air-cooling process. The microstructure analysis reveals that the combination of hot-rolling and air-cooling results in the formation of heterogeneous structures comprising different-sized γ and B_(2) phases in the low-density steel with the addition of nick.l (Ni). The addition of Ni promotes the formation of the B_(2) phase and induces the pinning of B_(2) phase particles at the γ grain boundaries. This pinning effect effectively hinders the growth of the γ grains, leading to grain refinement. The tensile test results demonstrate that LDS-5Ni (low-density steel, LDS) exhibits excellent high strength and ductility combination, e.g., a tensile strength of 1535 MPa, yield strength of 1482 MPa, and elongation of 23.3%. These remark.ble mechanical properties are primarily attributed to the combined strengthening contributions of grain refinement and duplex nano-sized second-phase precipitation hardening.

关键词： Low-density steel Microstructure B_(2)phase κ-Carbide Tensile properties

Enhanced activity and durability of FeCoCrMoCBY nanoglass in acidic hydrogen evolution reaction

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Journal of Materials Science & Technology 2024年第3期170卷 212-220页

作者： Mengyang Yan Shuangqin Chen Shangshu Wu Xuechun Zhou Shu Fu Di Wang Christian k.bel Horst Hahn Si Lan Tao feng Herbert Gleiter Institute of Nanoscience School of Material Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China Institute of Nanotechnology Karlsruhe Institute of TechnologyKarlsruhe 76021Germany

In the present work.a multi-element nanoglass(m-NG)of FeCoCrMoCBY is obtained first time by the laser ablation combined with inert gas condensation(laser-IGC)*** with the conventional rapid-quenched metallic glass(MG)with identical composition,the Fe-based m-NG demonstrates a superior performance as a self-supported electrocatalyst for hydrogen evolution reaction(HER)in acidic *** enhanced HER activity of m-NG is proposed to be closely related to its high en-ergy states,which is originated from the unique inhomogeneous nanostructures with a high density of low-coordinated ***,the Fe-based m-NG exhibits an outstanding comprehensive catalytic performance even beyond the commercial Pt/C catalyst in long-term test due to its self-optimization *** work.not only opens the way to the preparation of m-NGs by the novel laser-IGC technique,but also mak.s a great contribution to developing low-cost,high-efficient,and super-durable HER electrocat-alysts in acidic environment.

关键词： Nanoglass Inert gas condensations High energy states Hydrogen evolution reactions

Jack.on-type inequalities on high-dimensional spheres

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Science China Mathematics 2024年第11期67卷 2571-2586页

作者： Yeli Niu feng Dai Department of Mathematics Shanghai Normal University Department of Mathematical and Statistical Sciences University of Alberta

We study Jack.on's inequality on high-dimensional spheres with respect to the modulus of smoothness defined via the rotation *** obtain a version of Jack.on's inequality with a dimensionfree constant,extending Newman and Shapiro's well-k.own results in 1964 from the case of r = 1 and p = ∞ to more general *** results partially overcome the curse of *** also establish similar results on the equivalence of the k.functional and modulus of smoothness.

关键词： modulus of smoothness $k.-functional Jack.on's inequality high-dimensional approximation

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Plasma-assisted ammonia synthesis under mild conditions for hydrogen and electricity storage:Mechanisms,pathways,and application prospects

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Frontiers in Energy 2024年第4期18卷 418-435页

作者： feng GONG Yuhang JING Rui XIAO k.y Laboratory of Energy Thermal Conversion and Process Measurement and Control of the Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China

Ammonia,with its high hydrogen storage density of 17.7 wt.%(mass fraction),cleanliness,efficiency,and renewability,presents itself as a promising zero-carbon ***,the traditional Haber−Bosch(H−B)process for ammonia synthesis necessitates high temperature and pressure,resulting in over 420 million tons of carbon dioxide emissions annually,and relies on fossil fuel *** contrast,dielectric barrier discharge(DBD)plasma-assisted ammonia synthesis operates at low temperatures and atmospheric pressures,utilizing nitrogen and hydrogen radicals excited by energetic electrons,offering a potential alternative to the H−B *** method can be effectively coupled with renewable energy sources(such as solar and wind)for environmentally friendly,distributed,and efficient ammonia *** review delves into a comprehensive analysis of the low-temperature DBD plasma-assisted ammonia synthesis technology at atmospheric pressure,covering the reaction pathway,mechanism,and catalyst system involved in plasma nitrogen *** from current research,it evaluates the economic feasibility of the DBD plasmaassisted ammonia synthesis technology,analyzes existing dilemmas and challenges,and provides insights and recommendations for the future of nonthermal plasma ammonia processes.

关键词： plasma catalysis nitrogen fixation ammonia synthesis hydrogen storage catalyst carbon neutralization

Efficient Monolithic Perovsk.te/Silicon Tandem Photovoltaics

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Energy & Environmental Materials 2024年第3期7卷 268-281页

作者： Yong Wang Yu Wang feng Gao Deren Yang State k.y Laboratory of Silicon Materials and School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang UniversityHangzhou 310014China Department of Physics Chemistry and Biology(IFM)Linköping UniversityLinköping 58183Sweden

Tunable bandgaps mak. halide perovsk.tes promising candidates for developing tandem solar cells(TSCs),a strategy to break.the radiative limit of 33.7%for single-junction solar *** perovsk.tes with mark.t-dominant crystalline silicon(c-Si)is particularly attractive;simple estimates based on the bandgap matching indicate that the efficiency limit in such tandem device is as high as 46%.However,state-of-the-art perovsk.te/c-Si TSCs only achieve an efficiency of~32.5%,implying significant challenges and also rich *** this review,we start with the operating mechanism and efficiency limit of TSCs,followed by systematical discussions on wide-bandgap perovsk.te front cells,interface selective contacts,and electrical interconnection layer,as well as photon management for highly efficient perovsk.te/c-Si *** highlight the challenges in this field and provide our understanding of future research directions toward highly efficient and stable large-scale wide-bandgap perovsk.te front cells for the commercialization of perovsk.te/c-Si TSCs.

关键词： 2-terminal electrical interconnection perovsk.te/silicon tandem photovoltaics photon management wide-bandgap perovsk.tes

A new method for identifying flow pattern of spouted fluidized bed by coupling Hilbert-Huang transform characteristics of differential pressure signals in different zones

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Particuology 2024年第6期89卷 67-78页

作者： Yongzhi Mei Yang Wang Lihui Zhang feng Duan School of Energy and Environment Anhui University of TechnologyMaanshan243002China Wuhu Technology and Innovation Research Institute Wuhu241000China Wuhu Cigarette Factory of China Tobacco Anhui Industrial Co. Ldt.Wuhu241002China

On a cold spouted fluidized bed,this study compares the characteristic differences in intrinsic mode function(IMF)energy and Hilbert–Huang spectrum between the spout zone and annulus zone under different combinations of spouted gas and fluidized gas flow rates for five typical flow *** energy distribution characteristics under different flow patterns are also *** Hilbert–Huang spectrum and IMF energy of pressure difference signals exhibit distinct variations in different zones as the flow pattern ***,there exists a correlation between the energy in the middle-frequency range and the flow *** the k.means algorithm,the middle-frequency range energy of IMFs in the spout zone and annulus zone is subjected to clustering analysis,leading to the identification of partition boundaries for each flow *** on this,a flow pattern identification method of spouted fluidized bed coupled with middle-frequency range energy in spout zone and annulus zone is proposed,which has very high identification accuracy.

关键词： Spouted fluidized bed Flow pattern Zoning signal Flow pattern transition Hilbert-Huang transform