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Modeling of gas porosity and microstructure formation during dendritic and eutectic solidification of ternary Al-Si-Mg alloys

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Journal of Materials Science & Technology 2021年第17期76卷 76-85页

作者： Mengdan Hu Taotao Wang hui fang Mingfang Zhu Jiangsu Key Laboratory of Advanced Metallic Materials School of Materials Science and EngineeringSoutheast UniversityNanjing211189China

A two-dimensional(2-D)multi-component and multi-phase cellular automaton(CA)model coupled with the Calphad method and finite difference method(FDM)is proposed to simulate the gas pore formation and microstructures in solidification process of hypoeutectic Al-Si-Mg *** this model,the pore growth,and dendritic and eutectic solidification are simulated using a CA *** achieve the equilibrium among multiple phases during ternary Al-based alloy solidification,the phase transition thermodynamics and kinetics are evaluated by adopting the Calphad *** diffusion equations of hydrogen and two solutes are solved by *** developed CA-FDM coupled model can be used for simulating the evolution of gas microporosity and microstructures,involving dendrites and irregular binary and ternary eutectics,of ternary hypoeutectic Al-Si-Mg *** has the capability of reproducing the interactions between the hydrogen microporosity formation and the growth of dendrites and eutectics,the competitive growth among the growing gas pores of different sizes,together with the time-evolving concentration fields of hydrogen and *** simulated morphology of gas pore and microstructure has a good agreement with the experimental *** influences of the initial hydrogen concentration and cooling rate on the microporosity formation are *** is found that the main portion of porosity formation occurs in the eutectic solidification stage through analyzing the profiles of porosity percentage and solid fraction varying with solidification *** varying features of simulated porosity percentage,the maximum and average pores radii indicate that increasing initial hydrogen concentration promotes the formation of higher final porosity percentage and larger pores,while the size of gas pores will significantly reduce with increasing cooling rate,leading to a lower final porosity percentage.

关键词： Porosity Solidification microstructures Ternary Al-Si based alloys Diffusion Cellular automaton

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Perturbation to Mei Symmetry and Noether Adiabatic Invariants for Birkhoffian Systems

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Communications in Theoretical Physics 2008年第6期49卷 1410-1412页

作者： DING Ning fang Jian-hui Department of Physics and Electronics Science Binzhou University Binzhou 256600 China College of Physics Science and Technology China University of Petroleum Dongying 257061 China

Based on the concept of adiabatic invariant, the perturbation to Mei symmetry and Noether adiabatic invariants for Birkhoffian systems are studied. The exact invariants of Mei symmetry for the system without perturbation are given. The perturbation to Mei symmetry is discussed and the Noether adiabatic invariants induced from the perturbation to Mei symmetry of the system are obtained.

关键词： Mei symmetry perturbation Noether adiabatic invariant Birkhoffian system

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A New Type of Mei Adiabatic Invariant Induced by Perturbation to Mei Symmetry of Hamiltonian Systems

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Communications in Theoretical Physics 2009年第7期52卷 12-16页

Considering full perturbation to infinitesimal generators in the Mei structure equation,a new type of Meiadiabatic invariant induced by perturbation to Mei symmetry for Hamiltonian system was reported.

关键词： Mei symmetry perturbation Mei adiabatic invariant Hamiltonian system

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Lie Symmetry and Conserved Quantities for Nonholonomic Vacco Dynamical Systems

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Communications in Theoretical Physics 2006年第2X期46卷 265-268页

作者： DING Ning fang Jian-hui College of Physics and Technology China University of Petroleum Dongying 257061 China

In this paper the Lie symmetry and conserved quantities for nonholonomic Vacco dynamical systems are studied. The determining equation of the Lie symmetry for the system is given. The general Hojman conserved quantity... 详细信息

关键词： Vacco dynamical system Lie symmetry general Hojman conserved quantity Lutzky conserved quantity

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Ruzsa's Constant on Additive Functions

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Acta Mathematica Sinica,English Series 2013年第2期29卷 345-354页

作者： Jin hui fang Yong Gao CHEN Department of Mathematics Nanjing University of Information Science & Technology School of Mathematical Sciences and Institute of Mathematics Nanjing Normal University

A function f ： N → Ris called additive if f（mn） = f（m）＋f （n） for all m, n with （m, n） = 1. Let μ（x） = maxn≤x（f（n） - f（n ＋ 1）） and v（x） = maxn≤x（f（n ＋ 1） - f（n））. In 1979, Ruzsa proved ... 详细信息

A function f ： N → Ris called additive if f（mn） = f（m）＋f （n） for all m, n with （m, n） = 1. Let μ（x） = maxn≤x（f（n） - f（n ＋ 1）） and v（x） = maxn≤x（f（n ＋ 1） - f（n））. In 1979, Ruzsa proved that there exists a constant c such that for any additive function f, μ（x） ≤ cv（x^2）＋ cf, where cf is a constant depending only on f. Denote by Raf the least such constant c. We cMl Raf Ruzsa＇s constant on additive functions. In this paper, we prove that Raf≤ 20.

关键词： Additive function Ruzsa's constant

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Photoelectron momentum distributions of single-photon ionization under a pair of elliptically polarized attosecond laser pulses

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Chinese Physics B 2020年第7期29卷 313-320页

作者： hui-fang Cui Xiang-Yang Miao College of Physics and Information Engineering Shanxi Normal UniversityLinfen 041004China Key Laboratory of Spectral Measurement and Analysis of Shanxi Province Shanxi Normal UniversityLinfen 041004China

The attosecond ionization dynamics of atoms has attracted extensive attention in these ***,the role of the initial state is not clearly *** address this question,we perform simulations on the neon atom and its model atom with different initial states by numerically solving the corresponding two-dimensional time-dependent Schrodinger¨*** theoretically investigate atomic photoelectron momentum distributions(PMDs)by a pair of elliptically polarized attosecond laser *** find that the PMD is sensitive not only to the ellipticities of the pulses,the relative helicity,and time delay of the pulses,but also to the symmetry of the initial electronic *** are analyzed by the first-order time-dependent perturbation theory(TDPT)and offer a new tool for detecting the rotation direction of the ring currents.

关键词： photoelectron momentum distributions elliptically polarized attosecond laser pulses magnetic quantum numbers rotation direction of the ring currents

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Electrochemical reactions at the electrode/solution interface:Theory and applications to water electrolysis and oxygen reduction

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Science China Chemistry 2010年第3期53卷 542-551页

作者： fang, Ya hui Liu, Zhi Pan Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Department of Chemistry Fudan University Shanghai 200433 China

Theoretical simulations on complex electrochemical processes have been developed on the basis of the understanding in electrochemistry,which has benefited from quantum mechanics *** article reviews the recent progress on the theory and applications in *** representative reactions,namely water electrolysis and oxygen reduction,are selected to illustrate how the theoretical methods are applied to electrocatalytic *** microscopic nature of these electrochemical reactions under the applied potentials is described and the understanding of the reactions is *** thermodynamics and kinetics of the electrochemical reactions affected by the interplay of the electrochemical potential,the bonding strength and the local surface structure are addressed at the atomic level.

关键词： density functional theory electrode/solution interface water electrolysis oxygen reduction reaction review

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Stable and Total Fenchel Duality for Composed Convex Optimization Problems

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Acta Mathematicae Applicatae Sinica 2018年第4期34卷 813-827页

作者： Dong-hui fang Xian-yun WANG College of Mathematics and Statistics Jishou University

In this paper, we consider the composed convex optimization problem which consists in minimizing the sum of a convex function and a convex composite function. By using the properties of the epigraph of the conjugate functions and the subdifferentials of convex functions, we give some new constraint qualifications which completely characterize the strong Fenchel duality and the total Fenchel duality for composed convex optimiztion problem in real locally convex Hausdorff topological vector spaces.

关键词： Composed convex optimization problem constraint qualifications strong duality total duality

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Cathode Formed by Thermal Evaporation of Ba:Al Alloy and Estimations of Barrier Height in an Organic LED

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Chinese Physics Letters 2011年第6期28卷 287-290页

作者： DING Lei ZHANG fang-hui School of Electrical and Information Engineering Shaanxi University of Science and TechnologyXi'an 710021 Shaanxi Panel Display Engineering Center Xi'an 710021

It is demonstrated that barium and aluminum alloy synthesized by melting in a glass tube under low vacuum is applicable for organic laser emitting diodes(LEDs)as a thin film *** alloy film obtained by the thermal evaporation of pre-synthesized alloy is used in a single-boat organic LED device with the structure:indium tin oxide(ITO)/4,4'-bis[N−(1-naphthyl)-N−phenylamino]biphenyl(NPB)/tris-(8-hydroxyquinoline)aluminum(Alq3)/barium:aluminum *** experimental results show that devices with this alloy film cathode exhibit better current density-voltage-luminance characteristics than those with a conventional pure Al cathode,and more weight of barium in aluminum leads to better performance of the *** of current density versus voltage for the electron-only devices are fitted by the Richardson–Schottky emission model,indicating that the electron injection barrier has a decrease of about 0.3 eV by this alloy cathode.

关键词： alloy film Cathode

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Process Auxiliary Decision-making Based on Rough Sets and Regulation Distance Computing

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Chinese Journal of Mechanical Engineering 2009年第4期22卷 528-534页

作者： fang hui TAN Jianrong YIN Guofu LI Zhongkai State Key Laboratory of CAD and CG Zhejiang University Hangzhou 310027 China School of Manufacturing Science and Technology Sichuan University Chengdu 610065 China

Computer aided process planning（CAPP） is an important content of computer integrated manufacturing, and intelligentizing is the orientation of development of CAPP. Process planning has characters of empirical and time-consuming to finalize, and the same technical aim always can be achieved by different process schemes, so intelligentizing of process decision making always be a difficult point of CAPP and computer integrated manufacturing （CIM）. For the purpose of intelligent aided process decision making and reuse of process resource, this paper proposed a decision making method based on rough sets（RS） and regular distance computing. The main contents and methods of process planning decision making are analyzed under agile response manufacturing environment, the concept of process knowledge granule is represented, and the methods of process knowledge granule partitioning and granularity analysis are put forward. Based on the theory of RS and combined the method of process attributes importance identification, the paper brought forward a computing model for process scheme regulation distance under the same attribute conditions, and conflict resolution strategy was introduced to acquire process scheme fit for actual situation of enterprise＇s manufacturing resources, so as to realize process resources＇ conflict resolution and quick excavate and reuse of enterprises＇ existing process knowledge, to advance measures of process decision making and improve the rationality and capability of agile response of process planning.

关键词： process planning decision-making rough sets knowledge granule granularity regulation distance

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