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Interfacial instability of ferrofluid flow under the influence of a vacuum magnetic field

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Applied Mathematics and Mechanics(English Edition) 2021年第8期42卷 1171-1182页

作者： Mingjun li li zhu School of Mathematics and Computation Science Xiangtan UniversityXiangtan 411105Hunan ProvinceChina Hunan National Center for Applied Mathematics Xiangtan 411105Hunan ProvinceChina

This study is to numerically test the interfacial instability of ferrofluid flow under the presence of a vacuum magnetic *** ferrofluid parabolized stability equations(PSEs)are derived from the ferrofluid stability equations and the Rosensweig equations,and the characteristic values of the ferrofluid PSEs are given to describe the ellipticity of ferrofluid *** numerical models representing specific cases considering with/without a vacuum magnetic field or viscosity are created to mathematically examine the interfacial instability by the computation of characteristic *** investigation shows strong dependence of the basic characteristic of ferrofluid Rayleigh-Taylor instability(RTI)on viscosity of ferrofluid and independence of the vacuum magnetic *** the shock wave striking helium bubble,the magnetic field is not able to trigger the symmetry breaking of bubble but change the speed of the bubble *** the process of droplet formation from a submerged orifice,the collision between the droplet and the liquid surface causes symmetry *** the viscosity and the magnetic field exacerbate symmetry *** computational results agree with the published experimental results.

关键词： interfacial instability ferrofluid vacuum magnetic field parabolized stability equation(PSE)

Diophantine Inequality by Unlike Powers of Primes

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Chinese Annals of Mathematics,Series B 2022年第1期43卷 125-136页

作者： li zhu School of Statistics and Mathematics Shanghai Lixin University of Accounting and FinanceShanghai 201209China

Suppose that λ_(1),…,λ_(5) are nonzero real numbers,not all of the same sign,satisfying that λ_(1)/λ_(2) is *** for any given real number η and ε>0,the inequality |λ_(1)p_(1)+λ_(2)p_(2)^(2)+λ_(3)p_(3)^(3)+λ_(4)p_(4)^(4)+λ_(5)p_(5)^(5)+η|<(max_(1≤j≤5)p_(j)^(j))^(-19/756+ε) has infinitely many solutions in prime variables p_(1),…,p_(5).This result constitutes an improvement of the recent results.

关键词： Prime Davenport-Heilbronn method Diophantine inequalities

The density-and isospin-dependent■-formation cross section and its decay width

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Science China(Physics,Mechanics & Astronomy) 2019年第7期62卷 76-81页

作者： QingFeng li zhu Xia li School of Science Huzhou University Institute of Modern Physics Chinese Academy of Sciences China Institute of Atomic Energy

The energy-, density-, and isospin-dependent ?-formation cross section σ_(Nπ→?)~* and ?-decay width are calculated based on the relativistic BUU approach in which the effective mass splitting of nucleon and ? baryons in isospin-asymmetric matter is considered by the inclusion of the δ meson exchange in the effective Lagrangian density and the density-dependent coupling constants of Hofmann et al. The results show that the σ_(Nπ→?)~* is decreased(increased) moderately with increasing density with(without)the consideration of medium modifications on pion mass. Meanwhile, if the invariant mass of the system is not far from the ?pole mass, the ?-decay width is also weakly dependent on density. The mass splitting effect of differently charged nucleon and ?baryons on σ_(Nπ→?)~* is found to be more obvious than that of pion mesons but much weaker than the mass splitting in the hard ?production channel NN → N?. Further, the largest mass-splitting influence is seen in the π^-p → ?~0 and π^+n → ?^+ channels but not in the production of ?^- and ?^(++) isobars.

关键词： ■-formation cross section decay width symmetry energy

liouville Integrable System and Associated Integrable Coupling

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Communications in Theoretical Physics 2009年第12期52卷 987-991页

作者： li zhu College of Mathematics and Information Science Xinyang Normal University Xinyang 464000 China

liouville integrable discrete integrable system is derived based on discrete isospectral problem. It is shown that the hierarchy is completely integrable in the liouville sense and possesses bi-Hamiltonian structure. ... 详细信息

关键词： isospectral problem Hamiltonian structure integrable coupling semi-direct sums

Numerical simulation study on penetration performance of depleted Uranium(DU)alloy fragments

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Defence Technology（防务技术） 2021年第1期17卷 50-55页

作者： Fu-lin zhu Yang Chen Gui-li zhu Sichuan Aerospace System Engineering Institute Chengdu610100SichuanChina

Due to its high strength,high density,high hardness and good penetration capabilities,Depleted uranium alloys have already shined in armor-piercing *** should also be a lot of room for improvement in the application of fragment killing ***,regarding the performance of the depleted uranium alloy to penetrate the target plate,further investigation is needed to analyze its advantages and disadvantages compared to tungsten *** study the difference in penetration performance between depleted uranium alloy and tungsten alloy fragments,firstly,a theoretical analysis of the adiabatic shear sensitivity of DU and tungsten alloys was given from the perspective of material constitutive ***,taking the cylindrical fragment penetration target as the research object,the penetration process and velocity characteristics of the steel target plates penetrated by DU alloy fragment and tungsten alloy fragment were compared and analyzed,by using finite element software ANSYS/LS-DYNA and Lagrange ***,the influence of different postures when impacting target and different fragment shapes on the penetration results is carried out in the *** results show that in the penetration process of the DU and tungsten alloy fragments,the self-sharpening properties of the DU alloy can make the fragment head sharper and the penetrating ability *** the same conditions,the penetration capability of cylindrical fragment impacting target in vertical posture is better than that in horizontal posture,and the penetration capability of the spherical fragment is slightly better than that of cylindrical fragment.

关键词： Depleted uranium alloy Constitutive model Adiabatic shear Penetration performance Numerical simulation

Laguerre Geoinetry of Surfaces in R^3

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Acta Mathematica Sinica,English Series 2005年第6期21卷 1525-1534页

作者： Tong zhu li School of Mathematical Sciences Peking University Beijing 100871 P. R. China

Let f ： M → R3 be an oriented surface with non-degenerate second fundamental form. We denote by H and K its mean curvature and Gauss curvature. Then the Laguerre volume of f, defined by L（f） = f（H2 - K）/KdM, is an invariant under the Laguerre transformations. The critical surfaces of the functional L are called Laguerre minimal surfaces. In this paper we study the Laguerre minimal surfaces in R^3 by using the Laguerre Gauss map. It is known that a generic Laguerre minimal surface has a dual Laguerre minimal surface with the same Gauss map. In this paper we show that any surface which is not Laguerre minimal is uniquely determined by its Laguerre Gauss map. We show also that round spheres are the only compact Laguerre minimal surfaces in R^3. And we give a classification theorem of surfaces in R^3 with vanishing Laguerre form.

关键词： Laguerre transformation Laguerre Gauss map Laguerre minimal surface

Floristics and Plant Biogeography in China

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Journal of Integrative Plant Biology 2008年第7期50卷 771-777页

作者： De-zhu li Key Laboratory of Biodiversity and Biogeography Kunming Institute of Botany the Chinese Academy of Sciences and Plant Germplasm and Genomics Center Germplasm Bank of Wild Species Kunming 650204 China

In 1998, a revolutionary system of angiosperm classification, the Angiosperm Phylogeny Group system was published. Meanwhile, another new system of classification of angiosperms, the eight-class system was proposed by C.Y. Wu and colleagues based on long term work on the flora of China. The Flora Reipublicae Popularis Sinicae project was initiated in 1959 and completed by 2004. It is the largest Flora so far completed in the world, including 31 228 species of vascular plants, or one-eighth of the global plant diversity. The English-language and updated Flora of China （FOC） is an international joint effort initiated in 1988 and accelerated in 1998. Up to now, 15 of the 24 volumes of the FOC have been published. Based on the floristic data, the composition, characteristics, floristic divisions and affinities of the flora of China have been studied by Wu and colleagues since 1965. In the past 10 years, analyses of the available floristic data have been very productive. The East Asiatic Floristic Kingdom was proposed in 1998. All 346 families of angiosperms in China, according to the eight-class system of classification, were comprehensively discussed by using knowledge of current and historical distribution of seed plants in the world, together with some morphological and molecular data. A scheme of distribution patterns or areal-types of families and genera of seed plants in China was modified and elucidated, together with a proposed scheme of areal-types of the world. Molecular phylogenetic and biogeographical studies of angiosperms in China in the past 10 years also witnessed a progressive development. Integration of morphological and molecular data and fossil evidence revealed some significant results. Eastern Asia, which used to be regarded as an important center of survival during the ice age, is likely an important center of diversification of angiosperms.

关键词： biogeography center of diversification eastern Asia floristics phylogenetics.

Super-resolution image reconstruction based on three-step-training neural networks

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Journal of Systems Engineering and Electronics 2010年第6期21卷 934-940页

作者： Fuzhen zhu Jinzong li Bing zhu Dongdong Ma Institute of Image Information Technology and Engineering Harbin Institute of Technology Heilongjiang 150001 R R. China

A new method of super-resolution image reconstruction is proposed, which uses a three-step-training error backpropagation neural network （BPNN） to realize the super-resolution reconstruction （SRR） of satellite image. The method is based on BPNN. First, three groups learning samples with different resolutions are obtained according to image observation model, and then vector mappings are respectively used to those three group learning samples to speed up the convergence of BPNN, at last, three times consecutive training are carried on the BPNN. Training samples used in each step are of higher resolution than those used in the previous steps, so the increasing weights store a great amount of information for SRR, and network performance and generalization ability are improved greatly. Simulation and generalization tests are carried on the well-trained three-step-training NN respectively, and the reconstruction results with higher resolution images verify the effectiveness and validity of this method.

关键词： image reconstruction super-resolution three-steptraining neural network BP algorithm vector mapping.

Improved clustering method based on artificial immune

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Journal of Systems Engineering and Electronics 2010年第6期21卷 1111-1115页

作者： lin zhu Bo li School of Management Tianjin University Tianjin 300072 E R. China

An improved clustering method based on artificial immune is proposed. To obtain the better initial solution, the initial antibody network is introduced by self organizing map （SOM） method. In the process of the clustering iteration, a series of optimization and evolution strategies are designed, such as clustering satisfaction, the threshold design of scale compression, the learning rate, the clustering monitoring points and the clustering evaluations indexes. These strategies can make the clustering thresholds be quantified and reduce the operator’s subjective factors. Thus, the local optimal and the global optimal clustering simultaneously are proposed by the synthesized function of these strategies. Finally, the experiment and the comparisons demonstrate the proposed method effectiveness.

关键词： artificial immune system (AIS) clustering self organizing map (SOM).