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Time-variation of the near 5-month period of sunspot numbers

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Chinese Science Bulletin 2002年第23期47卷 1969-1973页

作者： HAN Yanben1 & HAN Yonggang1,2.. National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012. china 2. department of Applied Mathematics, Beijing {2. university, Beijing 10002., china National Astronomical Observatories Chinese Academy of Sciences Beijing China department of Applied Mathematics Beijing Polytechnic University Beijing China

The variation of the near 5-month period of sunspot numbers is discussed on the basis of the wavelet transform of the daily sunspot number series in the 14th-2.nd solar cycles. The result shows that the period exists in every cycle and its energy density (amplitude) is comparatively large in the peak section of the cycle. In the distinct cycle, the length and intensity of the period is different, which means that the period varies with time. The near 2.-day period is also analyzed and it is found to be time-variable and even not very stable in the peak section of the cycle. The variations of the two periods show that the near 5-month period should not be simply regarded as the multiples of the near 2.-day period.

关键词： solar activity sunspot time-variation wavelet.

A theoretical model of turbulent fiber suspension and its application to the channel flow

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Science china(Physics,mechanics & Astronomy) 2010年第9期53卷 1659-1670页

作者： LIN JianZhong1,2.& SHEN SuHua1 1 department of mechanics,Zhejiang {2.,Hangzhou 31002.,china 2.4} Jiliang {2.,Hangzhou 310018,china 1. department of mechanics Zhejiang University Hangzhou 310027 China2. China Jiliang University Hangzhou 310018 China

A theoretical model of turbulent fiber suspension is developed by deriving the equations of Reynolds averaged Navier-Stokes,turbulence kinetic energy and turbulence dissipation rate with the additional term of *** order to close the above equations,the equation of probability distribution function for mean fiber orientation is also *** theoretical model is applied to the turbulent channel flow and the corresponding equations are solved *** numerical results are verified by comparisons with the experimental *** effects of Reynolds number,fiber concentration and fiber aspect-ratio on the velocity profile,turbulent kinetic energy and turbulent dissipation rate are *** on the numerical data,the expression for the velocity profile in the turbulent fiber suspension channel flow,which includes the effect of Reynolds number,fiber concentration and aspect-ratio,is proposed.

关键词： theoretical model turbulent fiber suspension numerical simulation channel flow modification of velocity profile

Numerical modelling of sand beach evolution around coastal structures

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Acta Oceanologica Sinica 2000年第2期19卷 127-136页

作者： Zhang Haiwen1 Tao Jianhua2.(1. department of mechanics, Tianjin {2., Tianjin 300072. china. Present address: Tianjin Institute of Urologic Surgery, Tianjin 3002.1, china 2. department of mechanics, Tianjin {2., Tianjin 300072. china) Tianjin Inst. of Urologic Surgery Tianjin 300211 China

A systematic study of waves, nearshore currents and sediment transport related to the coastal evolution of sand beach under the action of wave, has been carried out. On the basis of the re sults, a numerical model of sand beach evolution around coastal structures has been established. To pre dict the bed topography, the sediment transport rates of bedload and suspended load under the action of wave and nearshore current as well as the effects of wave on the sediment are considered. The sand beach evolutions caused by a breakwater and a settled ship near the shore are simulated.

关键词： Wave nearshore current Sand beach evolution

Spectral anomalies and spectral switches of partially coherent and polychromatic light diffracted at an aperture

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Science china(Physics,mechanics & Astronomy) 2004年第1期47卷 24-35页

作者： Lü Baida1, 3 & PAN Liuzhan1, 2.1. Institute of Laser Physics and Chemistry, Sichuan university, Chengdu 610064, china 2. {2. of Physics, Luoyang Normal College, Luoyang 47102., china 3. State Key Laboratory of Laser Technology, Huazhong university of Science and Technology, Wuhan 430074, china Correspondence should be addressed to L Baida (email: badalu@***) Received July 10, 2.03 1. Institute of Laser Physics and Chemistry Sichuan University 610064 Chengdu China 2. State Key Laboratory of Laser Technology Huazhong University of Science and Technology 430074 Wuhan China 3. department of Physics Luoyang Normal College 471022 Luoyang China

Based on the propagation theory of partially coherent light in the space-frequency domain, the anomalous spectral behavior and spectral switches in the far field of partially coherent and polychromatic light diffracted at an aperture are studied. It is shown that, as compared with spatially fully coherent and polychromatic light whose spectral anomalies are induced only by aperture diffraction, the spectral anomalies and spectral switches of partially coherent and polychromatic light depend on the aperture diffraction, spatial correlationβ and bandwidth of the original spectrum. Detailed numerical calculations are made to illustrate the behavior of spectral switches of partially coherent and polychromatic light, and the results for spatially fully coherent and polychromatic light are treated as a special case ofβ=1 and included in our theory.

关键词： spectral anomaly spectral switch partially coherent and polychromatic light far field aperture diffraction

Superconductivity of small metal grains

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Science china(Physics,mechanics & Astronomy) 2005年第4期48卷 431-441页

作者： ZHENG Renrong1 CHEN Zhiqian2.& ZHU Shunquan1,3 1. department of Physics, Shanghai Normal university, Shanghai 2.02.4,{2. 2. department of Physics, Southwest Normal university, Chongqing 400715,{2. 3. department of Computer and Electric Technology, Shanghai Business School, Shanghai 2.1400,{2. 1. department of Physics Shanghai Normal University 200234 Shanghai China 2. department of Physics Southwest Normal University 400715 Chongqing China 3. department of Computer and Electric Technology Shanghai Business School 201400 Shanghai China

The formulas of the energy gap and superconducting critical temperature appropriate for systems with both odd and even number of electrons are derived; the bases of the derivations are BCS theory and energy level statistics. Numerical results qualitatively agree with the experimental phenomena. i.e., the superconductivity of small metallic grains will first enhance then decrease to zero when the grain are getting smaller and smaller. The calculations indicate that the above phenomena happen in the metallic grains belonging to Gaussian Orthogonal Ensemble (GOE) and Gaussian Unitary ensemble (GUE) with zero spin; The superconductivity of small metallic grains in Gaussian Symplectic Ensemble (GSE) will monotonically decrease to zero with the decreasing of the grain size. The analyses suggest that the superconductivity enhancements come from pairing and the balance of the strengths between spin-orbital coupling and external magnetic field. In order to take the latter into account, it is necessary to include the level statistics given by Random Matrix Theory (RMT) in describing small metallic grains.

关键词： size effect, superconductivity enhancements, small metallic grains.

Modulation on the collective response behavior by the system size in two-dimensional coupled cell systems

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Science china(Physics,mechanics & Astronomy) 2006年第3期49卷 304-312页

作者： ZHANG Jiqian1, SHEN Chuansheng1,2.& CUI Zhifeng1 1. College of Physics and Electronic Information, Anhui Normal university, Wuhu 2.1000, china 2. {2. of Educational Technology, Anqing Teachers College, Anqing 2.6011, china College of Physics Electronic Information Anhui Normal University Wuhu 241000 China department of Educational Technology Anqing Teachers College Anqing 246011 China

By the intracellular calcium ionic minimal model proposed by Berridge, we investigated the collective response of two-dimensional (N×N) coupled cell systems to the external stimulation using numerical simulation methods. With a coupled intensity fixed and an appropriate coupled cell number chosen, the kinetic system size resonance was discovered. At the same time, it was found that the system size responding to the external stimulation for different coupled intensities transferred too, especially when the coupled intensity increased, the range of the corresponding system size extended. These phe- nomena illustrate that the coupled cell number and the coupled intensity can play con- structive roles in noisy coupled systems, by which the biology system would probably improve its capability to respond to the external stimulation.

关键词： cell coupling,collective response,system size resonance

MD simulation of the effect of contact area and tip radius on nanoindentation

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Science china(Physics,mechanics & Astronomy) 2004年第1期47卷 101-112页

作者： CHEN Shangda1,2.& KE Fujiu1,2.1. department of Applied Physics, Beijing university of Aeronautics and Astronautics, Beijing 100083,{2. 2. State Key Laboratory of Non-linear mechanics (LNM), Institute of mechanics, Chinese Academy of Sciences, Beijing 100080,{2. Correspondence should be addressed to Chen Shangda (email: chensd@***) Received August 2., 2.03 1. department of Applied Physics Beijing University of Aeronautics and Astronautics 100083 Beijing China 2. State Key Laboratory of Non-linear mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences 100080 Beijing China

Molecular dynamics simulations of nanoindentation are performed on monocrystal copper. A new contact atoms method is presented for calculating the contact area. Compared with conventional methods, this method can provide the contact area more accurately not only for sink-in but also for pile-up situation. The effect of tip radius on indentation is investigated too. The results indicate that the measured hardness of the material will become higher as the tip radius increases.

关键词： nanoindentation, molecular dynamics, contact area, zero point of penetration depth, nano- hardness.

Theoretical model of particle orientation distribution function in a cylindrical particle suspension subject to turbulent shear flow

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Progress in Natural Science:Materials International 2006年第1期16卷 16-20页

作者： ZHANG Lingxin1, LIN Jianzhong1and ZHANG Weifeng 2.1.department of mechanics, State Key Laboratory of Fluid Power Transmission and Control, Zhejiang {2., Hangzhou 31002., china 2. Institute of Marine and Coastal Sciences, Rutgers {2., New Brunswick, New Jersey, USA) [a]department of mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou China [b]Institute of Marine and Coastal Sciences Rutgers University' New Brunswick New Jersey USA

The equation for the orientation probability function of slender cylindrical particles suspended in planar turbulent flows was investigated. After ensemble averaging, the equations for the mean and fluctuating probability function were derived. The equation for the fluctuating probability function appearing in the equation of mean probability function was solved by using the method of characteristics analysis. The orientational dispersion terms due to the random motion of cylindrical particles in the equation of mean probability function are related to the mean probability function and the Lagrangian fluid velocity correlations. The evolution of the mean probability function was described by a modified oriental ion-space-convection equation, where the dispersion terms account for the randomizing effect of the turbulence.

关键词： dispersion cylindrical particle suspensions turbulent flow probability function.

The complex variable reproducing kernel particle method for elasto-plasticity problems

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Science china(Physics,mechanics & Astronomy) 2010年第5期53卷 954-965页

作者： CHEN Li1 & CHENG YuMin2.1 department of Engineering mechanics,Chang’an {2.,Xi’an 710064,china 2.Shanghai Institute of Applied Mathematics and mechanics,Shanghai {2.,Shanghai 2.0072.china 1. department of Engineering mechanics Chang’an University Xi’an 710064 China2. Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

On the basis of reproducing kernel particle method(RKPM),using complex variable theory,the complex variable reproducing kernel particle method(CVRKPM) is discussed in this *** advantage of the CVRKPM is that the correction function of a two-dimensional problem is formed with one-dimensional basis function when the shape function is *** the CVRKPM is applied to solve two-dimensional elasto-plasticity *** Galerkin weak form is employed to obtain the discretized system equation,the penalty method is used to apply the essential boundary *** then,the CVRKPM for two-dimensional elasto-plasticity problems is formed,the corresponding formulae are obtained,and the Newton-Raphson method is used in the numerical *** numerical examples are given to show that this method in this paper is effective for elasto-plasticity analysis.

关键词： meshless method reproducing kernel particle method(RKPM) complex variable reproducing kernel particle method(CVRKPM) correction function elasto-plasticity