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SYMPLECTIC COMPUTATION OF HAMILTONIAN SYSTEMS (I)

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Journal of Computational Mathematics 2002年第3期20卷 267-276页

作者： Yi-fa Tang(LSEC,ICMSEC,academy of Mathematics and System sciences, chinese academy of sciences,beijing 100080, china) 中科院数学与系统科学院 LSEC ICMSEC CAS 北京 100080

Presents information on a study which discussed a symplectic computation of hamiltonian systems. Terms of formal energy of mid-point rule; Analysis of the mathematical pendulum to test the convergence of the formal en... 详细信息

关键词： mid-point rule formal energy

A NOTE ON THE CONSTRUCTION OF SYMPLECTIC SCHEMES FOR SPLITABLE HAMILTONIAN H = H^((1)) + H^((2)) + H^((3))

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Journal of Computational Mathematics 2002年第1期20卷 89-96页

作者： Yi-fa Tang (LSEC ICMSEC academy of Mathematics and System sciences, chinese academy of sciences, beijing 100080, china) 中科院数学与系统科学院 LSEC ICMSEC CAS 北京 100080

In this note, we will give a proof for the uniqueness of 4th-order time-reversible sym- plectic difference schemes of 13th-fold compositions of phase flows φtH(1) , φtH(2) , φtH(3) with different temporal parameter... 详细信息

关键词： Time-Reversible symplectic scheme Splitable hamiltonian.

A NEW STABILIZED FINITE ELEMENT METHOD FOR SOLVING THE ADVECTION-DIFFUSION EQUATIONS

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Journal of Computational Mathematics 2002年第1期20卷 57-64页

作者： Huo-yuan Duan (Institute of Mathematics, academy of Mathematics and System sciences, chinese academy of sciences, beijing 100080, china) Institute of Mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences 北京 100080

Focuses on a study on the development of a stabilized finite element method for solving the advection-diffusion equations with a zero Dirichlet boundary condition. Problem formulation; Error analysis.

关键词： advection-diffusion equation stabilized finite element method

SYNTHESIS AND CHARACTERIZATION OF NEW STABILIZERS WITH OPTIMAL MOLECULAR WEIGHT

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chinese Journal of Polymer Science 2001年第4期19卷 341-350页

作者： Jiang-qing Pan Institute of Chemistry chinese academy of sciences, beijing 100080 china 中科院化学所北京

Over 2 x 10(8) tons of polymers are produced every year, and a large portion of polymers faces the degradation problem. There are many effective methods to protect polymers against degradation and the addition of stabilizers to polymer remains the most convenient and effective way of enhancing polymer life and performance. In this article, a series of effective stabilizers with optimal molecular weight (MW), including common, monomeric and polymeric stabilizers (antioxidant and light stabilizer) were synthesized using isocyanation, controlled isocyanation, hydrosilylation, epoxide addition, macroreaction of stabilizing functional compounds and polymerization of monomeric stabilizers. The structure and performance of these new stabilizers were characterized by using IR, NMR, MS, UV-spectra, XPS and elemental analysis. The current development of stabilizer synthesis was also reviewed.

关键词： preparation of stabilizer antioxidant hindered amine light stabilizer isocyanation hydrosilylation

A PRELIMINARY STUDY ON THE VARIATION FEATURES OF GRAIN YIELD OF china IN RECENT 40 YEARS

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Journal of Geographical sciences 1996年第2期6卷 42-49页

作者： Zhang Yu(chinese academy of Mcteorological sciences, beijing 100081 People’s Republic of china ) chinese academy meteorological Sci Beijing 100081 China

Based on grain yield data of china, the vanation features of grain yield in china in recent 40 years and their relationships with the associated factors were analyzed. Results show that the total grain yield increased gradually, and its interannual variation is influenced principally by unit area crop yield (about 70 percent in average). The influences of agricultural technology, social factors and weather conditions on thet area crop yield can be separated because of their unique variation trends and time scales. The influence of agricultural technology is in a smoothly and gradually incremental trend, and the influence of the social factors is oscillated with three waves in recent 40 years, and the influence of weather conditions is fiuctuated sharply from year to year. Their mean effects on the inter-annual variation of unit area crop yield are about 35 to 40 percent, 10 to 15 percent and 50 percent respectively. In the view point of predictions, the effects of weather conditions are much more important.

关键词： crop yield agricultural technology social factors weather conditions,yield inter-annual vanation

Simulations for terrestrial planets formation

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Science china(Physics,Mechanics & Astronomy) 2009年第5期52卷 794-803页

作者： ZHANG Niu 1,2 &JI JiangHui 2,3 1Graduate University of chinese academy of sciences,beijing 100049,china 2Purple Mountain Observatory,chinese academy of sciences,Nanjing 210008,china 3 National Astronomical Observatories,chinese academy of sciences,beijing 100012,china Graduate University of chinese academy of sciences Beijing China Purple Mountain Observatory Chinese Academy of Sciences Nanjing China National Astronomical Observatories Chinese Academy of Sciences Beijing China

In this paper,the formation of terrestrial planets in the late stage of planetary formation is investigated using the two-planet *** that time,the protostar formed for about 3 Ma and the gas disk *** the model,the perturbations from Jupiter and Saturn are *** of the mass of outer planet,and the initial eccentricities and inclinations of embryos and planetesimals are also *** results show that,terrestrial planets are formed in 50 Ma,and the accretion rate is about 60%-80%.In each simulation,3-4 terrestrial planets are formed inside"Jupiter"with masses of 0.15 -3.6M⊕.In the 0.5-4 AU,when the eccentricities of planetesimals are excited,planetesimals are able to accrete material from wide radial *** plenty of water material of the terrestrial planet in the Habitable Zone may be transferred from the farther places by this *** could also happen a few times between two major planets only if the outer planet has a moderate mass and the small terrestrial planet could survive at some resonances over time scale of 10 8 *** one of our simulations,commensurability of the orbital periods of planets is very ***,a librating-circulating 3:2 configuration of mean motion resonance is found.

关键词： astrophysics exoplanet planetary formation n-body simulation

Sea-salt aerosol transport patterns over the Northern Hemisphere inferred from two subarctic ice core records

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Science china Earth sciences 2005年第4期48卷 576-584页

作者： YAN Yuping1,2, KANG Shichang2,3,5, SUN Junying4,5, Paul A. Mayewski2 & QIN Dahe5 1. National Climate Center, china meteorological Administration, beijing 100081, china 2. Climate Change Institute, University of Maine, Orono, ME 04469, USA 3. Institute of Tibetan Plateau Research, chinese academy of sciences, beijing 100085, china 4. chinese academy of meteorological sciences, beijing 100081, china 5. Key Laboratory of Ice Core and Cold Regions Environment, Cold and Arid Environmental and Engineering Research Institute, chinese academy of sciences, Lanzhou 730000, china National Climate Center China Meteorological Administration Beijing China Climate Change Institute University of Maine Orono ME USA Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China Key Laboratory of Ice Core and Cold Regions Environment Cold and Arid Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China chinese academy of meteorological sciences Beijing China

Atmospheric circulation reconstruction based on glaciochemical records requires knowledge of chemical concentration controls, such as source, transport pathway and strength. To gain insight into these processes, the relationships between glaciochemical records from two Northern Hemisphere sites (Mt. Logan in Yukon Territory and 20D in southern Greenland) and instrumental sea level pressure (SLP) series are investigated. Calibrations between Mt. Logan sea-salt sodium (ssNa+) concentration and SLP series show that ssNa+ concentrations are closely correlated with the autumntime (SON) Aleutian Low and the summertime (JJA) North Pacific Subtropical High. Both the deepened Aleutian Low and enhanced North Pacific Sub- tropical High strengthen the transport of sea-salt aerosols from the North Pacific to the Mt. Logan region. Calibrations between 20D ssNa+ concentrations and SLP series indicate that ssNa+ concentrations are closely related to the wintertime (Jan.) Icelandic Low. A deepening of the Icelandic Low strengthens winter storms and frequent cyclogenesis over the North Atlantic and pushes more sea-salt laden air masses to the Greenland ice sheet. Therefore, ice core ssNa+ records from the Mt. Logan region can be considered as a proxy for reconstructing the au- tumntime Aleutian Low and summertime North Pacific Subtropical High, and the ssNa+ records from Greenland ice core (20D) may provide a proxy for reconstructing the wintertime Icelandic Low.

关键词： sea-salt aerosol, ice core records, sea level pressure, subarctic regions.

A 12-bit multichannel ADC for pixel detectors in particle physics and nuclear imaging

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Science china(Technological sciences) 2010年第5期53卷 1208-1214页

作者： WEI Wei1,2,3,WANG Zheng1,3 & ZHAO JingWei1,3 1 Institute of High Energy Physics,chinese academy of sciences,beijing 100049,china 2 Graduate University of chinese academy of sciences,beijing 100049,china 3 Key Lab of Nuclear Detection Technology and Nuclear Electronics of chinese academy of sciences,beijing 100049,china Institute of High Energy Physics Chinese Academy of Sciences Graduate University of chinese academy of sciences Key Lab of Nuclear Detection Technology and Nuclear Electronics of chinese academy of sciences

Modern pixel detectors in nuclear and particle physics experiments and also in nuclear imaging,starve for highly integrated application specified integrated circuit(ASIC),whereas in china the study of ASIC still stays far away from practical *** lack of ASIC strictly limits the research and development of domestic high energy physics field.A 12-bit multichannel ADC designed for high density readout is introduced as a major candidate for solution.A precise model is discussed and the simulation fully agrees with the model,which indicates a key principle of *** is performed according to the given rule,and novel layout techniques are carried *** results in all aspects are also obtained,showing an excellent real performance,which satisfies the practical requirement.

关键词： application specified integrated circuit high density readout Wilkinson ADC multi-channel ADC

Chemical and mineralogical characterizations of a copper converter slag

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Rare Metals 2002年第3期21卷 175-181页

作者： DENG Tong and LING YunhanInstitute of Chemical Metallurgy, chinese academy of sciences, beijing 00080, china Institute of Chemical Metallurgy Chinese Academy of Sciences 北京 100080

A copper converter slag was examined chemically and mineralogically to determine its existing phases, in particular those containing Co and Cu. The slag consists predominantly of fayalite and magnetite, together with some glass, chalcocite, and metallic copper. Copper is entrapped in the slag mostly as chalcocite and metallic copper, as well as trace copper oxide. There was no indication of any independent Co mineral in the slag, but Co was found to be enriched in fayalite and megnetite as solid solution, although Co was detected in all the phases of the slag by SEM-EDX (scanning electron microscopy equipped with model EDAX-9100 energy dispersive spectrometer) and WDS (model WDX-2A X-ray wave-length dispersive spectrometer).

关键词： Cu Co converter slag characterization