检索结果-南通市图书馆

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, {2. Normal University, {2. 100875, China 2. Center for Atmospheric Chemistry Study, Department of Environmental Science & Engineering, Fudan University, Shanghai 2.043., China 3. LAPC/NZC, Institute of Atmospheric Physics, CAS, {2. 10002., China 1. The Center for Atmospheric Environmental Study Department of Chemistry Beijing Normal University 100875 Beijing China 2. Center for Atmospheric Chemistry Study Department of Environmental Science & Engineering Fudan University 200433 Shanghai China 3. Institute of Atmospheric Physics CAS LAPC/NZC 100029 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 only2.% 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.

Numerical simulation of topography effects on the “00.7” severe rainfall in beijing

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2005年第9期15卷 818-826页

作者： ZHANG Chaolin1**, JI Chongping1, KUO Yinghwa2. FAN Shuiyong1, XUAN Chunyi3.and CHEN Min1(1. Institute of Urban Meteorology, China Meteorological Administration, beijing 100089, China 2. Mesoscale and Microscale Meteorology Division, National Center for Atmospheric Research, Boulder, CO 803.7-3.00, USA 3. beijing Meteorological Bureau, beijing 100089, China) Institute of Urban Meteorology China Meteorological Administration Beijing 100089 China. Mesoscale and Microscale Meteorology Division National Center for Atmospheric Research Boulder CO 80307-3000 USA. beijing Meteorological Bureau Beijing 100089 China

In an effort to study the severe rainfall event of 4—5th July 2.00 in beijing (with 2.h accumulated precipitation of 2.0 mm), we perform numerical simulations to investigate this event using the MM5v3.6 model. The model is initialized with the MM5/WRF 3.VAR analysis, which incorporates the ground-based GPS precipitable water vapor, automatic and conventional meteorological observations in its assimilation step. For 2. h accumulated precipitation forecast, the threat scores are 0.72. 0.76, 0.67 and 0.63. for thresholds of 1, 5, 10, and 2. mm, respectively. Holding other factors unchanged, sensitivity experiments were conducted with different topographic resolutions of 110, 50 and 3.7 km to investigate the topographic effects on precipitation over the beijing area. In these sensitivity experiments, we attempt to preserve the realistic orographic distribution in the model topography under the condition of keeping the dynamic-thermodynamic consistency of the initial model atmosphere to the extent possible. Results indicate that the unique topographic distribution and variations in the beijing area play an important role in determining the location, distribution and intensity of heavy precipitation.

关键词： topography heavy rainfall 3.VAR ground-based GPS numerical simulation.

A novel endorectal RF coil for high resolution MRI and spectroscopy of the prostate

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2005年第5期15卷 472-476页

作者： ZHANG Hongjie 1,2. SONG Xiaoyu1, WANG Xiaoying3. XU Pingfang1 and BAO Shanglian1*(1. beijing Key Laboratory of Medical Physics & Engineering, {2. University, beijing {3. China 2. Navy General Hospital, beijing 10003., China 3. {2. University First Hospital, beijing 10003., China) beijing Key Laboratory of Medical Physics & Engineering Peking University Beijing 100871 China Navy General Hospital Beijing 100037 China peking University First Hospital Beijing 100034 China

The diagnosis of prostate diseases by magnetic resonance imaging (MRI) in vivo is sometimes difficult for the lower signal to noise ratio (SNR). To increase the SNR of the prostate image, we designed a RF coil that can be inserted into rectum and was named endorectal coil. The properties of RF coil were evaluated using a network analyzer. Moreover the images and spectroscopy of a special phantom were acquired and the results were compared to those of the commercial TORSO coil (G.E. Medical Systems, USA). Our coil gave a significantly higher SNR at the region of interest (ROI). The achieved high local SNR and resulting high spatial resolution would add more anatomic and biochemical information to the diagnosis of prostate diseases.

关键词： MRI RF coil endorectal coil.

Study on the two and three-parameter working stability regions of 3.-TZP suspension

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(Technological Sciences) 2006年第5期49卷 547-568页

作者： CHEN Youqiang1, 2. ZHANG Xinni3. CHEN Sha’ou3.& QI Ping3.1. Department of Chemistry, Qingdao University, Qingdao 2.6071, China 2. Department of Chemistry, Tsinghua University, beijing 100084, China 3. Department of Physics, Qingdao University, Qingdao 2.6071, China 1. Department of Chemistry Qingdao University Qingdao 266071 China 2. Department of Chemistry Tsinghua University Beijing 100084 China 3. Department of Physics Qingdao University Qingdao 266071 China

We determined the variation tendency of viscosity (η) at various solids load- ing (α) for 3.-TZP suspension as a function of dispersant concentration (Cw) using vis- cosity measurement, measured the diameter of particles as a function of Cw in very dilute suspension using light scattering method, and obtained the surface features of the sedi- ment of suspension with different Cw using SEM. We also discussed the influence of the microstructure of adsorbed polymer layers on particles and their interactions in the dis- persing medium on the stability of suspension. Then two different stable states and two different unstable states for 3.-TZP suspension were given. Accordingly, the (Cw, η), (Cw, α), and (α, η) two-parameter, and (Cw, α, η) three-parameter stability maps were con- structed. Based on the DLVO theory calculations, the dispersant concentration, particle distance (r), and interparticle potential energy (VT) maps with various solids loading for 3.-TZP aqueous suspension were also constructed. In (Cw, r) two-parameter coordinate system, the stable motion region map for particles was established. The Cw, α, and VT,max (the highest potential energy) surface of the potential barrier map was obtained through calculation and simulation on the basis of the surfaces of Cw, r, VT maps introduced above. The (Cw, α) two-parameter stability map was then obtained from the Cw, α, VT,max map. The results showed that this theoretical map can qualitatively prove the experimentally obtained results—the existence of different dispersed states of particles in suspension system and the variation tendency of suspension stability with changing each parame- ter—were reasonable.

关键词： 3.-TZP, suspension, stability, DLVO theory, interparticle potential energy.

Zhang-Xuan thermal uplift and its genesis

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2005年第8期15卷 725-732页

作者： SHAO Ji'an1*, NIU Shuyin2. ZHANG Lüqiao3.and LI Hongyang2.1. School of Earth and Space Sciences, peking University, {2. 1.0871. China 2. Shijiazhuang University of Economics, Shijiazhuang 05003., China 3. Geological Bureau of Inner Mongolia, Huhhot 01002., China) School of Earth and Space Sciences Peking University Beijing 100871 China. Shijiazhuang University of Economics Shijiazhuang 050031 China. Geological Bureau of Inner Mongolia Huhhot 010020 China

Based on the researches of the Mesozoic thermal evolution history, the deformed structures, and fission track analysis of the Zhangjiakou-Xuanhua area, we obtained the following knowledge: the area experienced in 140 Ma an underplating which is marked by emplacement of mantle derived magma; during 13.—110 Ma a series of eruptions and intrusions happened, and during 80—10 Ma a rising process occurred which is synchronous with the adjacent Taihang and Yanshan Mountains and was accompanied by a series of structures down slipping from the just formed Zhang-Xuan uplift toward its periphery. Combining the Zhang-Xuan thermal lift with the large detachment structure in Baoding depression of the North China Basin in the Late Mesozoic confirms that an even larger extensional tectonic background existed in North China during this period.

关键词： Zhang-Xuan area underplating thermal uplift fission track extensional structure.

Petrogenesis of Songshugou dunite body in the Qinling orogenic belt, Central China: Constraints from geochemistry and melt inclusions

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 Earth Sciences 2005年第8期48卷 1146-1157页

作者： SU Li1,2. SONG Shuguang3.& ZHOU Dingwu1 1. Key Laboratory of Continental Dynamics of the Ministry of Education, Department of Geology, Northwestern University, Xi’an 710069, China 2. The Geological Lab Center, China University of Geosciences (beijing), beijing 100083. China 3. Key Laboratory of Orogenic Belts of the Ministry of Education, Department of Geology, peking University, beijing 1.0871. China 1. Key Laboratory of Continental Dynamics of the Ministry of Education Department of Geology Northwestern University 710069 Xi’an China 2. The Geological Lab Center China University of Geosciences 100083 (Beijing)Beijing China 3. Key Laboratory of Orogenic Belts of the Ministry of Education Department of Geology Peking University 100871 Beijing China

The Songshugou dunite body, which occupies an area of about 2. km2. is the largest ultramafic massif in the eastern Qinling orogenic belt, Central China. The major compo-nent of this body is dunitic rocks including mylonitic dunite and coarse-grained dunite; they oc-cupy about 95 vol% of the total body. Petrography, mineral composition, major and trace ele-ments and primitive melt inclusions have been investigated in this paper; all revealed that this dunite body is the product of melt-rock interaction by porous percolation flow. In comparison with dunite sills or veins in harzburgite from the basal part of Oman ophiolite, this dunite body is characterized by lower contents of Al2.3. CaO and HREE but higher content of highly incom-patible elements and Zr and Hf. The LREE enriched patterns and primitive mantle normalized spidergrams of trace elements are also different from the Oman dunite. Combining with melt in-clusions observed in olivines, we conclude that this dunite body is the product of large- scale porous percolation flow of high-MgO melts within depleted mantle peridotites. The high-MgO magma, in essence, was most probably produced at the hot head of an upwelling mantle plume. The occurrence of the Songshugou dunite body is closely associated with the activity of mantle super-plume in Neo-Proterozoic era in the Yangtze Craton.

关键词： Songshugou dunite body, geochemistry, melt inclusion, mantle plume, Qinling orogenic belt.

Dehydration melting of solid amphibolite at 2.0 GPa: Effects of time and temperature

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2005年第8期48卷 1120-1133页

作者： ZHOU Wenge1, XIE Hongsen1, LIU Yonggang1, ZHENG Xiaogang1, ZHAO Zhidan2.& ZHOU Hui3.1. Laboratory of Material in the Earth’s Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002. China 2. Department of Geology, China University of Geosciences, beijing 100083. China 3. Department of Geology, peking University, beijing {3. China 1. Laboratory of Material in the Earth’s Interior Institute of Geochemistry Chinese Academy of Sciences 550002 Guiyang China 2. Department of Geology China University of Geosciences 100083 Beijing China 3. Department of Geology Peking University 100871 Beijing China

Two sets of dehydration-melting with a natural solid amphibolite, collected from North Himalayan structure zone, Tibet, have been carried out in multi-anvil apparatus at 2.0 GPa and 800―1000℃, for 12.2.0 h. One is keeping the pressure at 2.0 GPa and the annealing time of 12.h, changing the temperature (800―1000℃). The other is keeping the pressure at 2.0 GPa and temperature at 850℃, varying the annealing time (12.2.0 h). The products are inspected with microscope and electron probe. The results indicate that at 2.0 GPa, annealing time of 12.h, garnets, melts and clinopyroxenes occur in amphibolite gradually with increasing temperature and the chemical compositions of melt vary from tonalite to granodiorite, and then to tonalite. However, at 2.0 GPa and 850℃, with the annealing time increasing, the garnets, melts and cli-nopyroxenes also occur in amphibolite gradually and the chemical compositions of melt vary from tonalite to granodiorite. In both cases, melts interconnect with each other when the contents of melt are over the 5 vol.%. the viscosities of the melt produced in amphibolite at temperature higher than 850℃ are on a level with 104 Pa·s. The interconnected melt with such a viscosity may segregate from the source rock and form the magma over reasonable geological time. Therefore, it is believed that at the lower part of the overthickened crust, the tonlitic and grano-dioritic magma may be generated through the dehydration melting of amphibolite.

关键词： solid amphibolite, high pressure, high temperature, time, partial melting.

Paleotemperature changes over the past 3.00 years in eastern beijing, China: A reconstraction based on Mg/Sr records in a stalagmite

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2003年第4期48卷 395-400页

作者： MA Zhibang1, LI Hongchun2. XIA Ming1, KU Tehlung2. PENG Zicheng3. CHEN Yushu4 & ZHANG Zhaofeng3.1. Institute of Geology and Geophysics, Chinese Academy of Sciences, {2. 10002., China 2. Department of Earth Sciences, University of Southern California, Los Angeles, CA90089-0740, USA 3. Department of Earth and Space Science, University of Science and Technology of China, Hefei 2.0}02., China 4. {2. Foshan Tourist Service Centre, {2. 1012.1, China Institute of Geology and Geophysics. Chinese Academy of Sciences Beijing 100029 China

The Mg/Sr ratio in a stalagmite, which is di-rectly proportional to DMg/Ca, the solid-liquid distribution coefficient of Mg, is proposed as a geochemical thermometer to estimate paleotemperature changes. The paleotempera-ture change in eastern beijing over the past 3.00 years has been reconstructed by using this thermometer in the stalag-mite ZFFS-1 from Jingdong Cave. The records can be di-vided into two periods: 3.00—2.00 aBP, cool and wet, the air temperature averaging 9.8℃; and 2.00 aBP—present, hot and dry, the air temperature being 1℃ higher than the mean value (11.7℃) of the past 3.00 years. During 500—2.0 aBP, the air temperature was about 1.2. lower than that of the present, corresponding to the Little Ice Age in Europe. Like d 18O and d 13., Mg/Sr (or DMg/Ca) reflects an obviously warming trend of the past 2.0 years. These results are sup-ported by historic records.

关键词：北京京东溶洞石笋 Mg/Sr记录古气温测年 3.00年

On the periodic solutions of a type of differential-iterative equations

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1998年第3期43卷 204-206页

作者： GE Weigao 1, LIU Zhengrong 2.and YU Yuanhong 3.1. Department of Applied Mathematics, beijing Institute of Technology, beijing 100081, China 2. Department of Mathematics, Yunnan University, Kunming 650091, China 3. Institute of Applied Mathematics, C Department of Applied Mathematics Beijing Institute of Technology Beijing China Department of Mathematics Yunnan University Kunming China Institute of Applied Mathematics Chinese Academy of Sciences Beijing China

Sufficient conditions for the existence of periodic solutions to a type of nonautonomous differential_iterative equations are given.

关键词： differential_iterative equation periodic solution fixed point.