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Depth zonation of Arenigian acritarchs in South China

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Chinese Science Bulletin 1997年第3期42卷 248-251页

作者： XU WanhongDepartment of Earth Sciences, nanjing University, nanjing 210093, China Department of Earth Sciences Nanjing University Nanjing China

STAPLIN revealed that palaeoenvironment changes seem to control acritarch distribution patterns. However, scientists have been puzzled by the fact that characteristic offshore acritarchs occur with nearshore ones. This note demonstrates depth zonation of Arenigian acritarchs in South China and reveals the variation of water depth in South China during the Arenig Age.

关键词： South China Arenigian acritarch depth zonation.

THE BLOWUP OF RADIALLY SYMMETRIC SOLUTIONS FOR 2-D QUASILINEAR WAVEEQUATIONS WITH CUBIC NONLINEARITY

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Chinese Annals of Mathematics,Series B 1999年第4期20卷 455-472页

作者： YIN HUICHENG ZHENG QIN(Department of Mathematics, nanjing University nanjing 210093, China) Department of Mathematics Nanjing University Nanjing 210093 China

For a special class of quasilinear wave equations with small initial data which satisfy the nondegenerate assumption, the authors prove that the radially symmetric solution develops singularities in the second order derivatives in finite time while the first order derivatives and the solution itself remain continuous and small. More precisely, it turns out that this solution is a "geometric blowup solution of cusp type", according to the terminology posed by S. Alinhac[2].

关键词： Lifespan Geometric blowup Nash-M■ser iteration

The Origin of Infrared Emission from the Infrared Luminous Galaxy NGC 4418

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Chinese Journal of Astronomy and Astrophysics 2005年第2期5卷 117-125页

作者： Lei Shi and Qiu-Sheng Gu Department of Astronomy, nanjing University, nanjing 210093 qsgu@*** Department of Astronomy Nanjing University Nanjing 210093

We present a study of the origin of infrared (IR) emission in the opticallynormal, infrared luminous galaxy NGC 4418. By decomposing the stellar absorption features andcontinua in the range of 3600-8000 A from the Sloan Digital Sky Survey into a set of simple stellarpopulations, we derive the stellar properties for the nuclear region of NGC 4418. We compare theobserved infrared luminosity with the one derived from the starburst model, and find thatstar-forming activity contributes only 7% to the total IR emission, that as the IR emission regionis spatially very compact, the most possible source for the greater part of the IR emission is adeeply embedded AGN, though an AGN component is found to be unnecessary for fitting the opticalspectrum.

关键词： galaxies: general galaxies: active galaxies: stellar content galaxies:individual (NGC 4418)

An Accurate Rate Control Algorithm for Mobile Wireless Channel

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China Communications 2009年第1期6卷 119-122页

作者： Ma Guoqiang1 , Bi Houjie2 1nanjing University, nanjing 210093, China 2nanjing University of Posts and Telecommunications, nanjing 210093, China nanjing University Nanjing 210093 China nanjing University of Posts and Telecommunications Nanjing 210093 China

A novel rate control algorithm for extremely low bit rate and wireless channels is specified in this paper. The algorithm does rate analysis at an MB (Macro Block) level, and extracts the energy from motion and texture characteristics, finally allocates bits and controls the fluctuation according to the MB energy. Experimental results show that a higher accuracy of allocation of bit rate is achieved and the output bit rate is much smoother, as well as the improvement of subjective quality is considerable.

关键词： rate control low bitrate wireless channel video coding

Regular n-simplices in R^n with vertices in Z^(n)

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Science China Mathematics 2004年第1期47卷 104-113页

作者： XIA Jianguo & QIN HourongDepartment of Mathematics, nanjing Normal University, nanjing 210097, China (email: jgxia@***) Department of Mathematics, nanjing University, nanjing 210093, China Dept. of Math. Nanjing Normal Univ. Nanjing 210097 China Dept. of Math. Nanjing Univ. Nanjing 210093 China

In this paper the Ⅰ and Ⅱ regular n-simplices are introduced. We prove that the sufficient and necessary conditions for existence of an Ⅰ regular n-simplex in Rn are that if n is even then n = 4m(m + 1), and if n is odd then n = 4m + 1 with that n + 1 can be expressed as a sum of two integral squares or n = 4m - 1, and that the sufficient and necessary condition for existence of a Ⅱ regular n-simplex in Rn is n = 2m2 - 1 or n = 4m(m+1)(m 6 N). The connection between regulars-simplex in Rn and combinational design is given.

关键词： regular n-simplex in Rn, quadratic form.

Binomial coefficients,Catalan numbers and Lucas quotients

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Science China Mathematics 2010年第9期53卷 2473-2488页

作者： SUN ZhiWei Department of Mathematics,nanjing University,nanjing 210093,China Department of Mathematics Nanjing University Nanjing China

Let p be an odd prime and let a,m ∈ Z with a > 0 and p ︱ *** this paper we determinep ∑k=0 pa-1(2k k=d)/mk mod p2 for d=0,1;for example,where(-) is the Jacobi symbol and {un}n≥0 is the Lucas sequence given by u0 =... 详细信息

关键词： congruences binomial coefficients Catalan numbers Lucas quotients

On contactomorphism group of contact structure overtwisted at infinity on R^3

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Science China Mathematics 2007年第8期50卷 1087-1092页

作者： Li YU Department of Mathematics,nanjing University,nanjing 210093,China Department of Mathematics Nanjing University Nanjing China

We compute all the homotopy groups of the compactly supported contactomorphism group of a contact structure on R^3 which is overtwisted at infinity.

关键词： contactomorphism overtwisted contact structure

Study on the Relationship between Lamellar Spacing and Growth Rate inthe Regular Eutectic Growthby Monte-Carlo Simulation

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Journal of Materials Science & Technology 2002年第4期18卷 322-324页

作者： Weimin WANG, Junming LIU and Zhiguo LIULaboratory of Solid State Microstructures, nanjing University, nanjing 210093, China Lab. of Solid State Microstructures Nanjing Univ. Nanjing 210093 China

A modified Monte-Carlo(MC) method to simulate the regular growth of binary eutectic alloys is presented. It is found that the growth rate has a linear dependence on the chemical potential difference between the solid and liquid; the relation between the lamellar spacing A and growth rate R accords well with the prediction of Jackson-Hunt(JH) theory unless the growth rate is very low.

关键词： Eutectic Monte-Carlo simulation Growth

Formation flying in elliptic orbits with the J_2 perturbation

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Research in Astronomy and Astrophysics 2012年第11期12卷 1563-1575页

作者： Xi-Yun Hou, Yu-Hui Zhao and Lin Liu School of Astronomy and Space Science, nanjing University, nanjing 210093, China Institute of Space Environment and Astrodynamics, nanjing University, nanjing 210093, China School of Astronomy and Space Science Nanjing University Nanjing 210093 China Institute of Space Environment and Astrodynamics Nanjing University Nanjing 210093 China

Relative dynamics between the chief satellite and the deputy ones in for- marion flying is crucial to maintaining the formation. A good choice of the forma- tion usually requires a lower control frequency or less control energy. For formation flying missions in highly elliptic orbits, the well-known C-W equation is not accu- rate enough. Instead, Lawden＇s equation is often used. First, the solution to Lawden＇s equation with a very simple form is deduced. Then the J2 perturbation is added. It is found that Lawden＇s solution is not necessarily valid when the J2 perturbation is con- sidered. Completely discarding Lawden＇s solution and borrowing the idea of mean orbit elements, two rules to initialize the formation are proposed. The deviation speed is greatly reduced. Different from previous studies on the J2 perturbation, except for the relatively simple expression for the semi-major axis, the tedious formulae of the long period terms and the short period terms of other orbital elements are not used. In addition, the deviation speed is further reduced by compensation of the nonlinear effects. Finally, a loose control strategy of the formation is proposed. To test the ro- bustness of this strategy, a third body perturbation is added in numerical simulations.

关键词： celestial mechanics