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New evidence for lack of CMB power on large scales

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Science china(Physics,Mechanics & Astronomy) 2010年第3期53卷 567-570页

作者： LIU Hao1 & LI TiPei1,2,3 1 Key Laboratory of Particle astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, beijing 100049, china 2 Department of Physics & center for astrophysics, tsinghua university, beijing 100084, china 3 Department of Engineering Physics & center for astrophysics, tsinghua university, beijing 100084, china Key Laboratory of Particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Department of Physics & center for astrophysics Tsinghua University Department of Engineering Physics & center for astrophysics Tsinghua University

A digitalized temperature map is recovered from the first light sky survey image published by the Planck team, from which an angular power spectrum of the cosmic microwave background (CMB) is derived. The amplitudes of the low multipoles (low-l) measured from the preliminary Planck power spectrum are significantly lower than those reported by the WMAP team. Possible systematical effects are far from enough to explain the observed low-l differences.

关键词： cosmology cosmic microwave background data analysis

Constraints on Cardassian universe from Gamma ray bursts

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Science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1720-1725页

作者： WANG TaiShan1 & LIANG Nan2 1 Department of Physics & center for astrophysics,tsinghua university,beijing 100084,china 2 Department of Astronomy,beijing Normal university,beijing 100875,china tsinghua university Department of Physics &amp center for astrophysics Beijing China (GRID:grid.12527.33) (ISNI:***) beijing Normal university Department of Astronomy Beijing China (GRID:grid.20513.35) (ISNI:***)

Constraints on the original Cardassian model and the modified polytropic Cardassian model are examined from the recently derived 42 gamma-ray bursts(GRBs) data calibrated with the method that can avoid the circularity *** results show that GRBs can be an optional observation to constrain the Cardassian *** the GRBs data with the newly de-rived size of baryonic acoustic oscillation peak from the Sloan Digital Sky Survey(SDSS),and the position of the first acoustic peak of the Cosmic Microwave Background radiation(CMB) from Wilkinson Microwave Anisotropy Probe(WMAP),we find Ωm0=0.27+0.02-0.02,n=0.06+0.07-0.08(1σ) for the original Cardassian model,and Ωm0=0.27+0.23-0.02,n=-0.09+0.23-1.91,β=0.82+2.10-0.62(1σ) for the modified polytropic Cardassian model.

关键词： Cardassian Gamma ray burst Cosmic Microwave Background baryonic acoustic oscillation

Inconsistency between WMAP data and released map

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Chinese Science Bulletin 2010年第10期55卷 907-909页

作者： LIU Hao1 & LI TiPei1,2,3 1 Key Laboratory of Particle astrophysics,Institute of High Energy Physics,Chinese Academy of Sciences,beijing 100049,china 2 Department of Physics & center for astrophysics,tsinghua university,beijing 100084,china 3 Department of Engineering Physics & center for astrophysics,tsinghua university,beijing 100084,china Key Laboratory of Particle astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China Department of Physics & center for astrophysics Tsinghua University Beijing China Department of Engineering Physics & center for astrophysics Tsinghua University Beijing China

A remarkable inconsistency between the calibrated differential time-ordered data (TOD) of the Wilkinson Microwave Anisotropy Probe (WMAP) mission,which is the input for map-making,and the cosmic microwave background (CMB) temperature maps published by the WMAP team is revealed,indicating that there must exist a serious problem in the map making routine of the WMAP *** inconsistency is easy to be confirmed without the use of WMAP map-making *** view of the importance of this issue for cosmology study,we invite readers to check it by themselves.

关键词：威尔金森微波各向异性探测器 WMAP 地图制作宇宙微波背景有序数据制作软件 TOD CMB

A MESSAGE-DRIVING FORMALISM FOR MODELING AND SIMULATION OF MULTI-AGENT SUPPLY CHAIN SYSTEMS

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Journal of Systems Science and Systems Engineering 2011年第4期20卷 385-399页

作者： Wenzhe TAN1 Yueting CHAI2 Yi LIU3 1Department of Automation, tsinghua university, beijing, 100084, china 2Department of Automation, tsinghua university, beijing, 100084, china 3Department of Automation, tsinghua university, beijing, 100084, china Department of Automation Tsinghua University Beijing China

To acquire a competitive advantage in the expanding market, manufacturing enterprises should be able to manage their supply chains as effectively as possible. It is now becoming popular to model supply chains as multi-agent systems and use discrete event simulation to learn more about their behaviors or investigate the implications of alternative configurations. In order to enhance the computational efficiency and keep the simulation credibility, this paper proposes a message-driving formalism for the simulation of multi-agent supply chain systems. Through the message-driving formalism, the problem of shared variables is addressed and the parallel operation of agents is implemented. Simulation experiments with a prototype implementation show that the message-driving formalism is able to provide credible results in significantly less simulation time.

关键词： Supply chain multi-agent system modeling and simulation parallel discrete event simulation message-driving formalism

Extremal eigenvalues of measure differential equations with fixed variation

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Science china Mathematics 2010年第10期53卷 2573-2588页

作者： ZHANG MeiRong 1,2 1 Department of Mathematical Sciences,tsinghua university,beijing 100084,china 2 Zhou Pei-Yuan center for Applied Mathematics,tsinghua university,beijing 100084,china Department of Mathematical Sciences Tsinghua University Zhou Pei-Yuan center for Applied Mathematics Tsinghua University

In this paper we will study eigenvalues of measure differential equations which are motivated by physical problems when physical quantities are not absolutely *** taking Neumann eigenvalues of measure differential equations as an example,we will show how the extremal problems can be completely solved by exploiting the continuity results of eigenvalues in weak* topology of measures and the Lagrange multiplier rule for nonsmooth *** results can give another explanation for extremal eigenvalues of SturmLiouville operators with integrable potentials.

关键词： measure differential equation eigenvalue extremal value weak* topology Frechét derivative sub-differential

HIGH ACCURACY NUMERICAL METHOD OF THIN-FILM PROBLEMS IN MICROMAGNETICS

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Journal of Computational Mathematics 2003年第1期21卷 33-40页

作者： Zhongyi Huang (Deft, of Mathematical Sciences, tsinghua university, beijing, 100084, china) Dept. of Mathematical Sciences Tsinghua University 北京 100084

In this paper, a new high accuracy numerical method for the thin-film problems of micron and submicron size ferromagnetic elements is proposed. For the computation of stray field, we use the finite element method(FEM) by introducing a semi-discrete artificial boundary condition [1, 2]. In our numerical experiments about the domain patterns and their movement, we can see that the results are accordant to that of experiments and other numerical methods. Our method are very convenient to deal with arbitrary shape of thin films such as a polygon with high accuracy.

关键词： Thin-film Micromagnetics stray field Semi-discrete artificial boundary condition.

SOME PROPERTIES OF LSQR FOR LARGE SPARSE LINEAR LEAST SQUARES PROBLEMS

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Journal of Systems Science & Complexity 2010年第4期23卷 815-821页

作者： Zhongxiao JIA Department of Mathematical Sciences,tsinghua university,beijing 100084,china. Department of Mathematical Sciences Tsinghua University

It is well-known that many Krylov solvers for linear systems,eigenvalue problems,andsingular value decomposition problems have very simple and elegant formulas for residual *** not only allow us to further understand the methods theoretically but also can be usedas cheap stopping criteria without forming approximate solutions and residuals at each step beforeconvergence takes *** for large sparse linear least squares problems is based on the Lanczosbidiagonalization process and is a Krylov ***,there has not yet been an analogouslyelegant formula for residual *** paper derives such kind of *** addition,the authorgets some other properties of LSQR and its mathematically equivalent CGLS.

关键词： CGLS krylov subspace lanczos bidiagonalization least squares lsqr normal equations.

Timing in the Time Domain: Cygnus X-1

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Chinese Journal of Astronomy and astrophysics 2001年第4期1卷 313-332页

作者： Ti-Pei Li (Department of Physics and center for astrophysics, tsinghua university, beijing 100084 High Energy astrophysics Lab., Institute of High Energy Physics, Chinese Academy of Sciences, beijing 100039)E-mail:litp@*** Department of Physics and center for astrophysics Tsinghua University High Energy astrophysics Lab. Institute of High Energy Physics Chinese Academy of Sciences

Quantities characterizing temporal property, e.g., power density, coherence, and time lag, can be defined and calculated directly in the time domain without using the Fourier transformation. Spectral hardness, variability duration, and correlation between different characteristic quamtities on different time scale can be studied in the time domain as well. The temporal analysis technique in the time domain is a powerful tool, particularly in studying rapid variability on short time scales (or in high frequencies). Results of studying variabilities of X-rays from Cyg X-1 with the analysis technique in the time domain and RXTE data reveal valuable clues to understanding production and propagation processes of X-rays and structure of accretion disk in the black hole system.

关键词： methods: data analysis - stars: individual (Cygnus X-1) - X-rays: stars

THE NAGUMO EQUATION ON SELF-SIMILAR FRACTAL SETS

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Chinese Annals of Mathematics,Series B 2002年第4期23卷 519-530页

作者： HU JIAXINDepartment of Mathematics, tsinghua university, beijing 100084, china. Department of Mathematics Tsinghua University Beijing 100084 China

The Nagumo equation ut = △u+ bu(u-a)(1-u), t＞0is investigated with initial data and zero Neumann boundary conditions on post-critically finite (p.c.f.) self-similar fractals that have regular harmonic structures and satisfy the separation condition. Such a nonlinear diffusion equation has no travelling wave solutions because of the 'pathological' property of the fractal. However, it is shown that a global Holder continuous solution in spatial variables exists on the fractal considered. The Sobolev-type inequality plays a crucial role, which holds on such a class of p.c.f self-similar fractals. The heat kernel has an eigenfunction expansion and is well-defined due to a Weyl's formula. The large time asymptotic behavior of the solution is discussed, and the solution tends exponentially to the equilibrium state of the Nagumo equation as time tends to infinity if b is small.

关键词： Fractal set Spectral dimension Sobolev-type inequality Strong (Weak) solution