检索结果-南通市图书馆

Concatenating construction of the multisymplectic schemes for 2+1-dimensional sine-Gordon equation

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2004年第1期47卷 18-30页

作者： WANG Yushun, WANG Bin & QIN MengzhaoLASG, Institute of atmospheric physics, chinese academy of sciences,{3., china School of Mathematics and Computer Science, Nanjing Normal University, Nanjing 210097, china School of Mathematics and System Science, chinese academy of sciences, beijing 100080, china LASG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China School of Mathematics and Computer Science Nanjing Normal University Nanjing China School of Mathematics and System Science Chinese Academy of Sciences Beijing China

In this paper, taking the 2+1-dimensional sine-Gordon equation as an example, we present the concatenating method to construct the multisymplectic schemes. The method is to discretizee independently the PDEs in different directions with symplectic schemes, so that the multisymplectic schemes can be constructed by concatenating those symplectic schemes. By this method, we can construct multisymplectic schemes, including some widely used schemes with an accuracy of any order. The numerical simulation on the collisions of solitons are also proposed to illustrate the efficiency of the multisymplectic schemes.

关键词： 2+l-climensional sine-Gordon equation multisymplectic scheme concatenating method solitons

“Tali Glaciation” on Massif Diancang

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2007年第11期50卷 1685-1692页

作者： YANG JianQiang1, CUI ZhiJiu2, YI ChaoLu1, SUN JiMin3.& YANG LiRong3.1 Institute of Tibetan Plateau Research, chinese academy of sciences, beijing 100085, china 2 College of Environmental {3., Peking University, beijing 100871, china 3.Institute of Geology and Geophysics, chinese academy of sciences, beijing 10002., china Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China College of Environmental sciences Peking University Beijing China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China

The term of ''Tali Glaciation'' is nominated from Massif Diancang in Yunnan Province. The confusing process of the term''s being put forward is confirmed through literature checking. Based on several times of field trip, the glacial landforms in this region are studied in detail, and the magnitude of the glaciation was determined. According to the numerical ages from TL, AIMS ^(14)C and OSL dating, the earliest glacial advance on Massif Diancang occurred at 3.—40 ka BP, followed by the advances at the last stage of the last glaciation, the late glacial and neoglations in turn, until glaciers vanished at 1.2—1.5 ca. a BP in this region. It can be concluded that glaciers were limited above 3.00 m a.s.l., and no glaciers existed on the lower part and adjacent mountains since the last glaciation.

关键词： Massif Diancang,Tali Glaciation,glacial landform,glaciation sequence,numerical dating

The dynamical properties of Rydberg hydrogen atom near a metal surface

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2005年第6期48卷 667-675页

作者： GE Meihua1, ZHANG Yanhui1, WANG Dehua2, DU Mengli3.& LIN Shenglu1 1. College of physics and Electronics, Shandong Normal University, Jinan 250014, china 2. Department of Mathematics and physics, Shandong Institute of Architecture and Engineering, Jinan 250014, china 3. Institute of Theoretical physics, chinese academy of sciences, beijing 100080, china College of physics and Electronics Shandong Normal University Jinan China Department of Mathematics and physics Shandong Institute of Architecture and Engineering Jinan China Institute of Theoretical physics Chinese Academy of Sciences Beijing China

The dynamical properties of Rydberg hydrogen atom near a metal surface are presented by using the methods of phase space analysis and closed orbit theory. Transforming the coordinates of the Hamiltonian, we find that the phase space of the system is divided into vibrational and rotational region. Both the Poincaré surface of section and the closed orbit theory verify the same conclusion clearly. In this paper we choose the atomic principal quantum number as n = 20. The dynamical character of the exited hydrogen atom depends sensitively on the atom-surface distance d. When d is sufficiently large, the atom-surface potential can be expressed by the traditional van der Waals force and the system is integrable. When d becomes smaller, there exists a critical value dc. For d > dc, the system is near-integrable and the motion is regular. While chaotic motion appears for d < dc, and the system tends to be non-integrable. The trajectories become unstable and the electron might be captured onto the metal surface.

关键词： Rydberg hydrogen atom, van der Waals interaction, Poincaré surface of section, closed orbit theory, chaos.

Local and non-local sources of airborne particulate pollution at beijing——The ratio of Mg/Al as an element tracer for estimating the contributions of mineral aerosols from outside beijing

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2005年第3期48卷 253-264页

作者： HAN Lihui1, ZHUANG Guoshun1,2,3. SUN Yele1 & WANG Zifa3.1. The Center for atmospheric Environmental Study, Department of Chemistry, beijing Normal University, beijing 100875,{3. 2. Center for atmospheric Chemistry Study, Department of Environmental Science & Engineering, Fudan University, Shanghai 20043.,{3. 3. LAPC/NZC, Institute of atmospheric physics, CAS, beijing 10002.,{3. The Center for atmospheric Environmental Study Department of Chemistry Beijing Normal University Beijing China Center for atmospheric Chemistry Study Department of Environmental Science & Engineering Fudan University Shanghai China Institute of atmospheric physics CAS LAPC/NZC Beijing China

A new element tracer technique has firstly been established to estimate the contri-butions of mineral aerosols from both inside and outside beijing. The ratio of Mg/Al in aerosol is a feasible element tracer to distinguish between the sources of inside and outside beijing. Mineral aerosol, inorganic pollution aerosol mainly as sulfate and nitrate, and organic aerosol are the major components of airborne particulates in beijing, of which mineral aerosol accounted for 3.%―67% of total suspended particles （TSP）, 10%―70% of fine particles （PM2.5）, and as high as 74% and 90% of TSP and PM2.5, respectively, in dust storm. The sources from outside beijing contributed 62% （3.%―86%） of the total mineral aerosols in TSP, 69% （52%―90%） in PM10, and 76% （59%―93.） in PM2.5 in spring, and 69% （52%―83.）, 79% （52%―93.）, and 45% （7%―79%） in TSP, PM10, and PM2.5, respectively, in winter, while only20% in summer and autumn. The sources from outside beijing contributed as high as 97% during dust storm and were the dominant source of airborne particulates in beijing. The contributions from outside Bei-jing in spring and winter are higher than those in summer, indicating clearly that it was related to the various meteorological factors.

关键词： mineral aerosol local sources non-local sources dust storm re-suspended dust element tracer technique.

Population information extraction in Chaohu watershed based on RS and GIS

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

chinese Science Bulletin 2003年第2期48卷 181-183页

作者： LIU Jianjun1,2 & LI Chunlai3.1. Institute of Geochemistry, chinese academy of sciences, Guiyang 550002, china 2. Graduate School, chinese academy of sciences, {3. 10003., china 3. National Astronomical Observatories, chinese academy of sciences, {3. 100012, china Correspondence should be addressed to Liu Jianjun (e-mail: dhsliujj@ ***) Institute of Geochemistry Chinese Academy of Sciences Guiyang China Graduate School Chinese Academy of Sciences Beijing China National Astronomical Observatories Chinese Academy of Sciences Beijing China

It is always difficult to extract population in-formation of small watershed during the region environment assessment. The report adopted compound areal interpola-tion to study the population in Chaohu watershed with the GIS technique and landuse interpretation data from remote sensing. The result indicated that the method is effective to extract population information of small watershed.

关键词：巢湖流域人口分布信息提取 RS GIS 小流域生态环境评价

A high-resolution late Pleistocene record of pollen vegetation and climate change from Jingning, NW china

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2006年第2期49卷 154-162页

作者： LI Chunhai12, TANG Lingyu1, FENG Zhaodong3.4, ZHANG Hucai2, WANG Weiguo3.& AN Chenbang3.1. Nanjing Institute of Geology and Palaeontology, chinese academy of sciences, Nanjing 210008, china 2. Nanjng Institute of Geography and Limnology, chinese academy of sciences, Nanjing 210008, china 3. Environment and Resources College, Lanzhou University, Lanzhou 73.000, china 4. beijing Normal University, beijing 100875, china Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing China Nanjng Institute of Geography and Limnology Chinese Academy of Sciences Nanjing China Environment and Resources College Lanzhou University Lanzhou China beijing Normal University Beijing China

With the support of 18 AMS-14C data, a high-resolution pollen record from the Suancigou section at Jingning, Gansu Province was established. Our results showed that the vegetation ex-perienced a series of changes characterized by the alternative growth and decline of forest and steppe components during the period from 44.2 to 11 ka B.P. in the Jingning area. Over the period of 44―29 ka B.P. (MIS3., coniferous forests were flourishing, indicating a humid climate with the tem-perature being lower than that of the present. Since 23.ka B.P., the vegetation was dominated by steppe-desert steppe under a cold and dry condition, and entered the Last Glacial Maximum domi-nated by desert steppe. Several periods of the marked decrease in the arborous pollen content in Suancigou well corresponded to the North Atlantic Heinrich events, especially to Heinrich event 3. further supporting that the Heinrich events were well reflected by the pollen record in the Loess Pla-teau as well.

关键词： Western Loess Plateau, pollen record, climatic change, late Pleistocene.

Inorganic chemical composition and source signature of PM2.5 in beijing during ACE-Asia period

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2003年第10期48卷 1002-1005页

作者： ZHANG Renjian, XU Yongfu & HAN Zhiwei LAPC, Institute of atmospheric physics, chinese academy of sciences,{3., china LAPC Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

Aerosol samples for PM2.5 were collected in beijing for 3. consecutive days from March to April 2001 using an IMPROVE Sampler. Concentrations of 20 elements in PM2.5 were determined using a PIXE method. Results show that the average mineral dust concentration of PM2.5 was 14.6 mg/m3.during the observation period. On the sand-dust event days of March 21 and April 10, dust PM2.5 mass concentrations were 62.4 and 54.1 mg/m3. respectively. These demonstrate that fine particle pollution by dust event in beijing was very severe. The enrichment factors of S and Cu reached minimums on the dusty days and were high on the non-dusty days. It is considered that enrichment factors of elements in PM2.5, which are associated with human activities, can probably provide an effective method to distinguish local sources from external sources of dust. Factor analysis on the chemical composition in PM2.5 shows that sources of crustal matters, anthropogenic emission, and oil combustion contributed to PM2.5 levels in air in the springtime of 2001 in beijing.

关键词： dust ACE-Asia PM2.5 chemical composition source apportionment.

Approaches to improving critical current density of YBCO superconducting thick films deposited by electrophoresis

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2004年第2期47卷 165-172页

作者： ZHU Yabin1,2, ZHOU Yueliang2, LIU Zhen2, WANG Shufang2, CHEN Zhenghao2, L?Huibin2, YANG Guozhen2, XIAO Ling3. REN Hongtao3. JIAO Yulei3.& ZHENG Minghui3.1. Department of physics, College of Science, beijing Jiaotong University, beijing 100044,{3. 2. Laboratory of Optical physics, Institute of physics and Center for Condensed Matter physics, chinese academy of sciences, beijing 100080,{3. 3. General Research Institute for Nonferrous Metals, beijing 100088,{3. Correspondence should be addressed to Zhu Yabin (email: ybzhu@***) Department of physics College of Science Beijing Jiaotong University Beijing China Laboratory of Optical physics Institute of physics and Center for Condensed Matter physics Chinese Academy of Sciences Beijing China General Research Institute for Nonferrous Metals Beijing China

Fabrication of YBCO superconducting thick films by electrophoresis has been widely reported. However, the value of critical current density (J c) is far from what the practical application requires. The superconducting thick films are obtained using top-seeded melt growth method with different proportional Y2BaCuO5 (Y211) addition. High-pressure oxygen has been used in the annealing process to improve the uniformity of the oxygen content in the superconducting thick films. When 40mol% Y211 powder is added to the YBa2Cu3.7–5 (Y123. powder,J c for the superconducting thick film by approaches described above reaches 7.008×103.A/cm2 (77 K, 0 T), which is greater than the value ever reported.

关键词： YBCO thick films, electrophoretic deposition, melt-textured.

The relationship between short-range motion of atmosphere and ocean and conservative and nonconservative scheme

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2003年第10期48卷 999-1001页

作者： LIN Wantao, JI Zhongzhen & WANG Bin LASG,Institute of atmospheric physics, chinese academy of sciences,{3., china LASG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

Taking one-dimensional shallow water wave equation as an example, a comparative analysis on the computational stability related to the short-range motion of atmosphere and ocean is carried out for the conservative and nonconservative scheme, and it is pointed out that the computational stability of conservative scheme is absolutely different from that of the nonconservative scheme. The relationship between the short-range motion of atmosphere and ocean and the conservative and nonconservative scheme is further discussed. The constructed conservative scheme is proved to be stable by the numerical experiment for the short-range motion of atmosphere and ocean while the CTCS scheme is unstable. So that the conservative scheme for the solution of this kind of problem has more advantages.

关键词： short-range motion of atmosphere and ocean conservative scheme nonconservative scheme computational stability.