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Science china(Technological Sciences) 2007年第4期50卷 385-401页

作者： ZHANG HanXin1,2.3, ZHANG Zhao1,3, YUAN XianXu1,2. LIU Wei1, XIE YuFei1,2.& YE YouDa1,2.1 china Aerodynamics research and Development {2., Mianyang 62.000, china 2.National Laboratory for Computational Fluid Dynamics, beijing university of Aeronautics and Astronautics, beijing 100083, china 3 School of Aerospace, tsinghua university, beijing 100084, china 1. china Aerodynamics research and Development {2. Mianyan 621000 China 2. National Laboratory for Computational Fluid Dynamics Beijing University of Aeronautics and Astronautics Beijing 100083 China 3. School of Aerospace Tsinghua University Beijing 100084 China

Analytical methods of nonlinear dynamics and numerical simulations for the cou-pling equations of Navier-Stokes and flight mechanics are used to study the dynamic behaviour of pitching motions of reentry capsules with the variation of Mach number, and rocking motions of swept wings with the variation of angle of attack. Conditions under which the dynamic instability, Hopf bifurcation and saddle-node bifurcation occur are obtained. The node-saddle-node topological structure in the phase portrait, i.e. the state of bi-attractors (attracting basins) is described. The evolving process of dynamic behaviour and flow fields are given. The theories are compared with some numerical simulations conducted by the authors. Besides, some verifiable experi-mental results are cited. The agreement between them is very well.

关键词： physical analysis numerical simulation pitching oscillation rocking motion bifurcation

Simulating the impacts of climate variation and land-cover changes on basin hydrology: A case study of the Suomo basin

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Science china Earth Sciences 2005年第9期48卷 1501-1509页

作者： CHEN Junfeng1,2. LI Xiubin2.& ZHANG Ming2.1. Institute of Remote Sensing & GIS, Peking university, beijing 100871, {2. 2. Institute of Geographical Sciences and Natural Resources research, Chinese Academy of Sciences, beijing 100101, {2. 1. Institute of Remote Sensing & GIS Peking University 100871 Beijing China 2. Institute of Geographical Sciences and Natural Resources research Chinese Academy of Sciences 100101 Beijing Chin

Impacts of land cover changes on watershed hydrology have been a long-term academic concern with acute dispute. But little attention has been paid to such effects on mesoscale river basins, where the society has a closer link to river hydrology. The present study focuses on a mesoscale river basin, the Suomo Basin that is located on the upper reaches of the Yangtze River. Land covers in the basin in the years 1970, 1986 and 1999 were mapped. A lumped hydrologic model, CHARM, and a distributed hydrologic model, SWAT, were used to model the impacts of both land-cover change and climate variation on river runoff during the past four decades. The results show that the contribution of climate variation to the change of runoff regime makes up 60%―80%, while that of land cover changes only 2.%.

关键词： climate variation, land-cover changes, Suomo Basin, CHARM model, SWAT model.

Effects of binders on the performance of electric double-layer capacitors of carbon nanotube electrodes

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Progress in Natural Science:Materials International 2005年第5期15卷 453-457页

作者： LI Chensha1*, WANG Dazhi1, ZHANG Baoyou2. WANG Xiaofeng1, CAO Maosheng3 and LIANG Ji1(1. Department of Mechanical Engineering, tsinghua university, beijing 100084, {2. 2. center for Analysis and Measurement, Harbin Institute of Technology, Harbin 150001, {2. 3. School of Material Science and Engineering, tsinghua university, beijing 100084, {2.) Department of Mechanical Engineering Tsinghua University Beijing 100084 China center for Analysis and Measurement Harbin Institute of Technology Harbin 150001 China School of Material Science and Engineering Tsinghua University Beijing 100084 China

Polarizable electrodes of electric double layer capacitor (EDLCs) were made from carbon nanotubes. Effects of different binders, which are phenolic resin (PF) and polytetrafluoroethylene (PTFE), on the properties of polarizable electrodes are studied. Results indicate that the microstructure, pore size distribution and specific capacitance of the electrodes with PTFE binder are superior to those electrodes with PF binder after carbonization. The suitable binder (PTFE) for carbon nanotubes electrodes is proposed.

关键词： carbon nanotubes electric double-layer capacitors phenolic resin polytetrafluoroethylene.

Observation results of relativistic electrons detected by Fengyun-1 satellite and analysis of relativistic electron enhancement (REE) events

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Science china(Physics,Mechanics & Astronomy) 2008年第12期51卷 1947-1956页

作者： YANG XiaoChao1,2. & WANG ShiJin1 1 center for Space Science and Applied research, Chinese Academy of Sciences, {2. 100190, china 2.Graduate university of Chinese Academy of Sciences, {2. 100049, china 1. center for Space Science and Applied research Chinese Academy of Sciences Beijing 100190 China 2. Graduate university of Chinese Academy of Sciences Beijing 100049 China

The space particle component detector on Fengyun-1 satellite which works at the sun-synchronous orbit of about 870 km altitude has detected relativistic electrons for a long time. In comparison with the SAMPEX satellite observations during 1999–2.04, the relativistic electron data from Fengyun-1 satellite from June 1999 to 2.05 are used to analyze the relativistic electron enhancement (REE) events at the low earth orbit, and the possible correlation among REE events at the low earth orbit, high-speed solar wind and geomagnetic storms is discussed. The statistical result presents that 45 REE events are found in total during this time period, and the strong REE events with the maximum daily average flux > 400 cm?2.srt-1·s?1 occur mostly during the transition period from solar maximum to solar minimum. Among these 45 REE events, four strong REE events last a longer time period from 2.-to 51-day and correlate closely with high speed solar wind and strong geomagnetic storms. Meanwhile, several strong geomagnetic storms occur continuously before these REE events, and these continuous geomagnetic storms would be an important factor causing these long-lasting strong REE events. The correlation analysis for overall 45 events indicates that the strength of the REE events correlates with the solar wind speed and the strength of the geomagnetic storm, and the correlation for strong REE events is much stronger than that for weak REE events.

关键词： relativistic electron enhancement low earth orbit high-speed solar wind geomagnetic storm

Large field of view computed laminography with the asymmetric rotational scanning geometry

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Science china(Technological Sciences) 2010年第8期53卷 2261-2271页

作者： FU Jian 1,2.,JIANG BaiHong&LI Bin 1 School of Mechanical Engineering and Automation,Beihang university,beijing 100191,{2. 2.research center of Digital Radiation Imaging and Biomedical Imaging,Beihang university,beijing 100191,{2. 1. School of Mechanical Engineering and Automation Beihang University Beijing 100191 China2. Research Center of Digital Radiation Imaging and Biomedical Imaging Beihang University Beijing 100191 China

X-ray computed laminography(CL)is used in the fields of industrial inspection and medical *** can provide the internal structure three-dimensional(3D)information of a region of the objects *** is important to the clinical diagnosis and the quality control of flat objects like printed circuit boards,aircraft wings and satellite solar *** the restriction that the imaging region must be within the X-ray beam formed by the X-ray source and the detector,the imaging field of view of CL is limited by the size of detector.A new CL method with an asymmetric rotational cone-beam scanning geometry,called large field of view CL,is presented to overcome the existing *** can extend the imaging region when the imaging spatial resolution keeps the same as that of the conventional *** can also improve the imaging spatial resolution when the imaging region keeps the same as that of the conventional *** asymmetric configuration can be achieved by offsetting the detector from the conventional symmetric *** does not,however,require new detectors and X-ray source nor alter the scanning mechanical *** filtered back-projection(FBP)reconstruction algorithm and the data truncation smoothing functions have been deduced to reconstruct the images directly from the data acquired with this asymmetric *** performed numerical studies and experiments to demonstrate and validate the proposed approach. Results in these studies and experiments confirm that the proposed method can enlarge the imaging region and improve the spatial *** proposed approach may find applications in the CL system with the rotational scanning geometry.

关键词： computed laminography image reconstruction reconstruction algorithm imaging field of view imaging spatial resolution

A Novel network Management Model Based on XML for Service and Resource

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计算机工程 2002年第S1期28卷 77-81页

作者： ZHANG JinxiangWU JianpingWANG Jilong(network research {2. of tsinghua university, beijing 100084,china, jxzhang@***) network research {2. of tsinghua university Beijing 100084China j xzhang ***

XML can allow for the interchange of data between management applications using different information models. Furthermore, CORBA technique is increasingly used in the management of service and resource in the heterogeneous network environment. As the scheme of information arrangement of CORBA is flat file style, which handles querying, deleting, and insertinginformation inefficiently, this paper puts forward a novel network management model based on XML in the domain of the management of CERNET ({2. Education and research network), which has used a tree structure of managed objects arrangement to provide efficient operation on managed objects. In addition, arrangement, definition, implementation and finding schemes for CORBA managed objects using XML are also given by the tree structure, and thus can arrange and retrieve managed objects efficiently.

关键词： XMLCORBAnetwork managementModel

Empirical likelihood confidence regions of the parameters in a partially linear single-index model

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Science china Mathematics 2005年第10期48卷 1333-1348页

作者： XUE Liugen~1 & ZHU Lixing~2.1. College of Applied Sciences,beijing university of Technology,beijing 10002.,china 2. Department of Mathematics,Hong Kong Baptist university,Hong Kong,china 1. College of Applied Sciences Beijing University of Technology 100022 Beijing China 2. Department of Mathematics Hong Kong Baptist University Hong Kong China

In this paper, a partially linear single-index model is investigated, and three empirical log-likelihood ratio statistics for the unknown parameters in the model are suggested. It is proved that the proposed statistics are asymptotically standard chi-square under some suitable conditions, and hence can be used to construct the confidence regions of the parameters. Our methods can also deal with the confidence region construction for the index in the pure single-index model. A simulation study indicates that, in terms of coverage probabilities and average areas of the confidence regions, the proposed methods perform better than the least-squares method.

关键词： partially linear single-index model, empirical likelihood, confidence region, chi-square distribution, coverage probability.

Dipole anomaly in the Arctic atmosphere and winter Arctic sea ice motion

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Science china Earth Sciences 2005年第9期48卷 1529-1536页

作者： WU Bingyi1, ZHANG Renhe1 & WANG Jia2.1. Chinese Academy of Meteorological Sciences, beijing 100081, china 2. International Arctic {2. center, university of Alaska Fairbanks, AK 99775, USA 1. Chinese Academy of Meteorological Sciences 100081 Beijing China 2. International Arctic research center University of Alaska Fairbanks 99775 AK USA

This paper investigates a previously-ignored atmospheric circulation anomaly-di- pole structure anomaly in the arctic atmosphere, and its relationship with the winter sea ice mo- tion, based on analyses of the International Arctic Buoy Programme Data (1979―1998) and datasets from the National center for Environmental Prediction (NCEP) and the National center for Atmospheric {2. (NCAR) for the period of 1960―2.02. The dipole structure anomaly is the second-leading mode of EOF of monthly mean SLP north of 70°N during the winter season (Oct.―Mar.), which accounts for 13% of the variance. One of its two anomaly centers is over the Canadian Archipelago; the other is situated over northern Eurasia and the Siberian marginal seas. Due to the dipole structure anomaly’s strong meridionality, it becomes an important mechanism to drive both anomalous sea ice export out of the Arctic Basin and cold air outbreaks into the Barents Sea, the Nordic Seas and northern Europe.

关键词： dipole anomaly, winter season, Arctic, sea ice motion, sea ice export.

Effects of elevated CO_2.on growth and carbon partitioning in rice

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Chinese Science Bulletin 1998年第23期43卷 1982-1986页

作者： LIN Weihong\+1 and WANG Dali\+2.1. Department of Plant Nutrition, china Agricultural university, {2. 100094, china 2. Department of Systems Ecology, research center for Eco_Environmental Science, Chinese Academy of Sciences, {2. 100085, china Department of Plant Nutrition China Agricultural University Beijing China Department of Systems Ecology Research Center for Eco-Environmental Science Chinese Academy of Sciences Beijing China

Rice (\%Oryza sativa\% cv. Jindao 1187) was grown in open_top chambers which contained ambient and enriched CO\-2. CO\-2.elevation stimulated rice tillering during early vegetative stage. However, panicle dry weight per plant did not change at maturity stage. Root biomass was enhanced by high CO\-2. Root / shoot ratio was increased under high CO\-2.at maturity, indicating more carbon allocation to the below_bround part in rice under high CO\-2.

关键词： CO 2 elevation growth carbon partitioning rice (\%Oryza sativa cv\%. Jindao 1187).

Virus rejection with two model human enteric viruses in membrane bioreactor system

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Science china Chemistry 2007年第3期50卷 397-404页

作者： ZHENG Xiang1,2.& LIU JunXin1 1 research center for Eco-Environmental Sciences, Chinese Academy of Sciences, {2. 100085, china 2.School of Environment & Natural Resources, Renmin university of china, {2. 100872. china 1. research center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China 2. School of Environment & Natural Resources Renmin University of China Beijing 100872 China

A membrane bioreactor (MBR) with gravity drain was tested for virus rejection with two coliphages, T4 and f2. which were used as surrogates for human enteric viruses. Virus rejection was investigated by PVDF and PP membrane modules, with the pore sizes of 0.2. and 0.1 μm, respectively. In tap water system, 2.1 lg rejection of coliphage T4 could be achieved by PVDF membrane compared with complete rejection by PP membrane, while for coliphage f2.with smaller diameter, 0.3―0.5 lg rejection of the influent virus was removed by the two membranes. In domestic wastewater system, cake layer and gel layer on the membrane surface changed the cut-off size of the membrane so that there was no significant difference between PP and PVDF for each coliphage. The removal ratios of coliphage T4 and f2.in the MBR were more than 5.5 and 3.0 lg, respectively. Compared with 5.5 lg removal for virus T4 in the MBR system, only 2.1 lg (96.8%―99.9%) removal rate was observed in the conventional activated sludge system with the influent virus concentration fluctuating from 1830 to 57000 PFU/mL. Only 0.8%―2.% virus removal was the effect of adsorption to activated sludge, which showed a decreasing tendency with the retention time, while 75%―98% was the effect of virus inactivation by microbial activity. It indicated that the major mechanism of virus removal was not the transfer of viruses from the water phase to the sludge phase but inactivation in the biological treatment process.

关键词： MBR model virus enteric virus inactivation