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ON THE ASYMPTOTIC SOlUTIONS OF BOUNDARY VAlUE PROBlEMS FOR A ClASS OF SYSTEMS OF NONlINEAR DIFFERENTIAl EQUATIONS (Ⅰ)

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Applied Mathematics and Mechanics(English Edition) 2001年第3期22卷 282-293页

作者： JIANG Fu-ru(江福汝) Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 P R China

A new method is applied to study the asymptotic behavior of solutions of boundary value problems for a class of systems of nonlinear differential equations u' = nu, epsilon nu' + f(x, u, u')nu' - g(x, u, u') nu = 0 (0 lon much less than 1). The asymptotic expansions of solutions are constructed, the remainders are estimated. The former works are improved and generalized.

关键词： system of nonlinear differential equations boundary value problems asymptotic solution

Spectral Dimension of a Modified Checker Board Fractal lattice

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Chinese Physics letters 1996年第5期13卷 325-328页

作者： CHEN Shu YANG Zhan-ru CCAST(World laboratory) P.O.Box 8730Beijing 100080 Department of Physics and Institute of Theoretical PhysicsBeijing Normal UniversityBeijing 100875

We present a kind of modified checker board lattice and investigate the random uualk on the frac *** spectral dimension is determined via renormalization procedures and the inverse matrix method is used to renormalize... 详细信息

关键词： random inverse Modified

TWO-SCAlE FEM FOR EllIPTIC MIXED BOUNDARY VAlUE PROBlEMS WITH SMAll PERIODIC COEFFICIENTS

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Journal of Computational Mathematics 2001年第5期19卷 549-560页

作者： Jin-ru Chen Jun-zhi Cui School of Mathematics and Computer Sciences Nanjing Normal UniversityNanjing 210097China ICMSEC Academy of Mathematics and Systems SciencesChinese Academy of SciencesBeijing 100080China

Presents a study which proposed a dual approximate expression of the exact solution for mixed boundary value problems of second order elliptic partial differential equation with small periodic coefficients. Dual appro... 详细信息

关键词： two-scale FEM mixed boundary value small periodic coefficients

Dynamics of a prestressed Timoshenko beam subject to arbitrary external load

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第11期11卷 898-907页

作者： Ji-qing JIANG Gui-ru YE Department of Civil Engineering Zhejiang University Hangzhou 310058 China

The free vibration and transient wave in a prestressed Rayleigh-Timoshenko beam subject to arbitrary transverse forces are analyzed by the newly developed method of reverberation-ray matrix (MRRM). The effects of shear deformation and rotational inertia are taken into consideration. With a Fourier transform technique, the general wave solutions with two sets of unknown amplitude coefficients are obtained in the transformed domain for an unbonded prestressed beam under the action of arbitrary external excitations. From the coupling at joints and the compatibility of displacements in each member, the free and forced vibration responses of a beam with various boundary conditions are finally evaluated through certain numerical algorithms. Results are presented for a simply-supported beam subject to either a point fixed load or moving load. Good agreement with the finite element method (FEM) is obtained. The present work is instructive for high-speed railway bridge design and structural health monitoring.

关键词： Reverberation-ray analysis Prestressed Timoshenko beam Free vibration Dynamic responses

Theoretical Studies on the Isomerization of Peroxynitrite to Nitrate Mediated by Peroxynitrous Acid

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Chinese Journal of Structural Chemistry 2008年第2期27卷 171-176页

作者： lIU Yong-Dong ZHONG ru-Gang College of life Science ＆ Bioengineering Beijing University of Technology Beijing 100022 China

The conversion of peroxynitrite （ONOO-） to nitrate （NO3-） mediated by peroxynitrous acid （ONOOH） has been investigated at the CCSD/6-311G（d）//B3lYP/6-31 1＋G（d,p） level. Two kinds of pathways for the title reaction were found. The results show that the energy barrier of isomerization through pathway 1 is around 25 kcal/mol in the gas phase. This value is significantly lower than that of isomerization without any catalysts. Thus, it indicates that ONOOH definitely makes the conversion from ONOO- to NO3- feasible. Although pathway 2 does not decrease the energy barrier of this isomerization, peroxynitric acid （O2NOOH） was obtained; moreover, this is a new pathway for this formation. In view of the results that peroxynitrate anion can decompose into nitrite and dioxygen, we conclude that our results are consistent with the experimental observation that nitrate, nitrite, and dioxygen are the main final products of the decay of peroxynitrite around pH 7.

关键词： peroxynitrite peroxynitrous acid isomerization DFT

Towards a Theoretical Background for Strong-Scattering Inversion–Direct Envelope Inversion and Gel’fand-levitan-Marchenko Theory

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Communications in Computational Physics 2020年第6期28卷 41-73页

作者： ru-Shan Wu Modeling and Imaging laboratory Earth and Planetary SciencesUniversity of CaliforniaSanta Cruz95060CAUSA

Strong-scattering inversion or the inverse problem for strong scattering has different physical-mathematical foundations from the weak-scattering *** inversion based on wave equation for strong scattering cannot be directly solved by Newton’s local optimization method which is based on weak-nonlinear *** I try to illustrate the connection between the Schr̈odinger inverse scattering(inverse problem for Schr̈odinger equation)by GlM(Gel’fand-levitan-Marchenko)the-ory and the direct envelope inversion(DEI)using reflection *** difference between wave equation and Schr̈odinger equation is that the latter has a potential independent of frequency while the former has a frequency-square dependency in the potential.I also point out that the traditional GlM equation for potential inversion can only recover the high-wavenumber components of impedance profile.I propose to use the Schr̈odinger impedance equation for direct impedance inversion and introduce a singular impedance function which also corresponds to a singular potential for the reconstruction of impedance profile,including discontinuities and long-wavelength velocity structure.I will review the GlM theory and its application to impedance inversion including some numerical *** I analyze the recently developed multi-scale direct envelope inversion(MS-DEI)and its connection to the inverse Schr̈odinger *** is conceivable that the combination of strong-scattering inversion(inverse Schr̈odinger scattering)and weak-scattering inversion(local optimization based inversion)may create some inversion methods working for a whole range of inversion problems in geophysical exploration.

关键词： Strong-scattering strong nonlinear inversion GlM theory envelope inversion

Contact force and mechanical loss of multistage cable under tension and bending

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Acta Mechanica Sinica 2016年第5期32卷 891-904页

作者： Yanyun ru Huadong Yong Youhe Zhou Key laboratory of Mechanics on Disaster and Environment in Western China Ministry of Education of China Department of Mechanics and Engineering Sciences College of Civil Engineering and Mechanics Lanzhou University

A theoretical model for calculating the stress and strain states of cabling structures with different loadings has been developed in this paper. We solve the problem for the first- and second-stage cable with tensile or bending strain. The contact and friction forces between the strands are presented by two-dimensional contact model. Several theoretical models have been proposed to verify the results when the triplet subjected to the tensile strain, including contact force, contact stresses, and mechanical loss. It is found that loadings will affect the friction force and the mechanical loss of the triplet. The results show that the contact force and mechanical loss are dependent on the twist pitch. A shorter twist pitch can lead to higher contact force, while the trend of mechanical loss with twist pitch is complicated. The mechanical loss may be reduced by adjusting the twist pitch reasonably. The present model provides a simple analysis method to investigate the mechanical behaviors in multistage-structures under different loads.

关键词： Contact force Friction force Tension Bending Mechanical loss

An in-vitro Investigation of Iron-Containing Hydroxyapatite/Titanium Composites

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Journal of Materials Science & Technology 2011年第6期27卷 546-552页

作者： Q. Chang H.Q. ru D.l. Chen X.Y. Yue l. Yu C.P. Zhang Key laboratory for Anisotropy and Texture of Materials (Ministry of Education) Northeastern University Shenyang 110004 China Department of Mechanical and Industrial Engineering Ryerson University 350 Victoria Street Toronto Ontario M5B 2K3 Canada

The in-vitro biological behavior of a newly-developed iron-containing hydroxyapatite/titanium（HA/Ti） composite was investigated by immersing the composites in the simulated body fluid（SBF） for up to 5 *** addition of iron was observed to have a significant influence on the in-vitro biological behavior of the *** obtained results revealed that the stability of the composites in the physiological solution was markedly *** solubility decreased in the order of pure HA,HA/5（Ti-33Fe）,and HA/15（Ti33Fe）.Precipitation occurred on the surface of HA/5（Ti-33Fe） composite,showing a good combination of physiostability with bioactivity,while HA/15（Ti-33Fe） composite exhibited superior physiostability since there was no obvious change on the surface of HA/15（Ti-33Fe）.

关键词： Hydroxyapatite composite Iron Titanium Simulated body fluid Biological behavior

Influence of Photovoltaic Effect on Photorefractive Phase Gratings

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Chinese Physics letters 1995年第10期12卷 617-620页

作者： ZHANG Guoquan GUO ru Department of Physics Nankai UniversityTianjin 300071

We solve the Kukhtarev’s nonlinear equations of the photorefractive effect with the participation of diffusion,drift and the photovoltaic effect without the approximation of linear generation and linear recombination,and especially discuss in detail the effects of photovoltaic field on the photorefractive grating and its equivalence to an applied electric field in the photovoltaic photorefractive materials.

关键词： materials. equivalence approximation