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A good example of high-energy radiation delay event

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chinese Science Bulletin 1997年第4期42卷 313-315页

作者： GAN Weiqun and Rieger Erich1 Purple mountain {2., nanjing 2.0008, china 2. Max-Planck Institute of Extraterrestrial Physics, Garching 85740,Germany Purple mountain {2. Nanjing China Max-Planck Institute of Extraterrestrial Physics Garching Germany

THE delay of high-energy radiation of solar flares can be divided into two types: one is the energy-dependent delay in the hard X-ray regime, the other is the delay between the hard X-rays and instantaneous γ-ray line (GRL) emissions. Both types have different physical meanings. The former reflects the difference in acceleration or transportation of energetic electrons with various energies, while the latter reflects such a difference between the energetic electrons

关键词： sun. flare X-ray γ-ray.

CO observations of massive star forming regions at different evolutionary phases

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Science china(Physics,Mechanics & Astronomy) 2006年第5期49卷 626-640页

作者： CHEN Xi1,2. XU Ye1,3, SHEN Zhiqiang1,3 & LI Jingjing1,2.1. Shanghai Astronomical observatory, chinese Academy of {2., Shanghai 2.0030, china 2. Graduate School of the chinese Academy of {2., Beijing 100034, china 3. Joint Institute for Galaxy and Cosmology, Shanghai Astronomical observatory and the University of Science and Technology of china, Shanghai 2.0030, china Shanghai Astronomical observatory Chinese Academy of Sciences Shanghai China Graduate School of the chinese Academy of sciences Beijing China Joint Institute for Galaxy and Cosmology Shanghai Astronomical Observatory and the University of Science and Technology of China Shanghai China

The 12.O (J=1-0), 13CO (J=1-0) and C18O (J=1-0) emissions in 9 massive star forming regions, which are believed to be at different stages of massive star formation, were mapped with the 13.7 m millimeter wave telescope at Qinghai Station of Purple mountain {2.. Of the observed 9 sources, 13CO cores were detected in seven of them, and C18O cores in five of them. And only two sources associated with C18O cores and H2. masers showed the extended structures and strong outflows. This is the first detection of outflow associated with IRAS 2.566+582. in the observing field of S152.S153. The physical parameters of cores and outflows for these sources, derived from Local Thermal Equilibrium (LTE) analysis, are presented. These observing results suggest that the C18O cores will only appear when the gas density is high enough and the probability to have an outflow is very high when the clumps show the C18O and H2. maser simulta- neously.

关键词： star formation cloud core outflow H2. maser

Ecological Footprint and Ecological Security Evaluation in the Upper Min River Basin

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Wuhan University Journal of Natural sciences 2005年第4期10卷 641-646页

作者： TU Jian-jun 1, 2.1. School of Resources and Environment Science, Southwest china Normal University, Chongqing 400715, china 2. Institute of {2. Hazards and Environment, chinese Academy of sciences, Chengdu 610041, Sichuan, china School of Resources and Environment Science Southwest China Normal University Chongqing China Institute of mountain Hazards and Environment Chinese Academy of Sciences Chengdu Sichuan China

On the basis of the ecological footprint (EF) model, this paper studied theecological security in the Upper Min River Basin ecosystem. The result shows that with 2. 038 2.hm^2.er capita ecological capacity (0. 42. 2.hm^2.higher than per capita EF) ,and 165 82. hm^2.ecologysurplus , the ecosystem in Upper Min River is generally secure at present. But the arable land isoverweighed and omens an eco-security crisis. Meanwhile, problems such as low forest coverage rate,severe loss of water and soil,enlargement of arid-valley area, frequent occurrence of mountainhazards and degradation of pastures have been major threats to the eco-security of this region. Thecalculation result of ten-thousand-yuan ( RMB) GDP shows that the use of natural resources isextensive, and there will be a rapid increase tendency of EF in the future. In order to maintain thepresent eco-security, the ways of use natural resources must be improved in the Upper Min RiverBasin.

关键词： ecological security ecological footprint ecological capacity quantitativeevaluation the Upper Min River Basin

Magnetic energy injection in GRB 080913

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 262-264页

作者： LIU XueWen,WU XueFeng & LU Tan Purple mountain {2.,chinese Academy of sciences,nanjing 2.0008,china Purple mountain {2. Chinese Academy of Sciences Nanjing China

GRB 080913,with a spectroscopically determined redshift of z=6.7,was the record holder for being the most remote stellar object before the discovery of the recent gamma-ray burst GRB 09042.,whose redshift is about *** gradually accumulated high redshift GRB sample has shed light on the origin and physical properties of GRBs during the cosmic re-ionization ***,we present a detailed numerical fit to the multi-wavelength data of the optical afterglow of GRB 080913 and then constrain its circumburst environment and the other model *** conclude that the late optical/X-ray plateau at about one day since the burst is due to the Poynting-flux dominated injection from the central engine which is very likely a massive spinning black hole with super strong magnetic fields.

关键词： gamma-rays:bursts outflow black hole

A Note on the Mixing Length Theory and Massive Star Evolution

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chinese Journal of Astronomy and Astrophysics 2001年第1期1卷 50-56页

作者： Li-Cai Deng and Da-Run Xiong ( Beijing Astronomical observatory, chinese Academy of {2., Beijing 100012.Purple mountain observatory, chinese Academy of {2., nanjing2.0008 National Astronomical Observatories, chinese Academy of {2., Beij Beijing Astronomical observatory Chinese Academy of Sciences Beijing 100012 National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 CAS-Peking University Joint Beijing Astrophysical Center Beijing 100871 Purple mountain {2. Chinese Academy of Sciences Nanjing 210008

In this paper, we investigate the problem of supersonic convection caused by the application of the usual Mixing Length Theory (MLT), and give a modification to the original expression of the MLT. In the case of the usual MLT, a zone of supersonic convection exists when the stellar model goes into yellow-red supergiant phase. When the modification is applied, the models of late type supergiants possess shallower convective envelopes for a given temperature compared with the normal formalism of the MLT. Therefore the stellar models made with our new formalism move to lower effective temperature by 100-400 K depending on the luminosity of the star. Such a modification does not affect the convective envelope structure of lower luminosity late type stars, as both expressions of the MLT give the same result. In these stars.

关键词： convection - stars: supergiants - stars: massive stars - stars: evolution

Debris Flow Hazard Assessment Based on Support Vector Machine

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Wuhan University Journal of Natural sciences 2006年第4期11卷 897-900页

作者： YUAN Lifeng 1, 2., ZHANG Youshui 3 1. Institute of mountain Hazards and Environment, chinese Academy of {2., Chengdu 610041, Sichuan, china 2. Graduate University of chinese Academy of {2., Beijing 100049, china 3. Institute of Geographical {2. and Natural Resources Research, chinese Academy of {2., Beijing 100101, china Institute of mountain Hazards and Environment Chinese Academy of Sciences Chengdu Sichuan China Graduate University of chinese Academy of sciences Beijing China Institute of Geographical sciences and Natural Resources Research Chinese Academy of Sciences Beijing China

Seven factors, including the maximum volume of once flow , occurrence frequency of debris flow , watershed area , main channel length , watershed relative height difference , valley incision density and the length ratio of sediment supplement are chosen as evaluation factors of debris flow hazard degree. Using support vector machine （SVM） theory, we selected 2.9 basic data of 37 debris flow channels in Yunnan Province as learning samples in this study. We create a debris flow hazard assessment model based on SVM. The model was validated though instance applications and showed encouraging results.

关键词： debris flow hazard assessment support vector machine (SVM)

Risk and size estimation of debris flow caused by storm rainfall in mountain regions

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Science china(Technological sciences) 2003年第Z1期46卷 12-19页

作者： CHENG Genwei Institute of mountain Hazards and Environment, chinese Academy of {2. and Ministry of Water Resources, Chengdu 610041, china chinese Acad Sci Inst Mt Hazards & Environm Chengdu 610041 Peoples R China Minist Water Resources Chengdu 610041 Peoples R China

Debris flow is a common disaster in mountain regions. The valley slope, storm rainfall and amassed sand-rock materials in a watershed may influence the types of debris flow. The bursting of debris flow is not a pure random event. Field investigations show the periodicity of its burst, but no directive evidence has been found yet. A risk definition of debris flow is proposed here based upon the accumulation and the starting conditions of loose material in channel. According to this definition, the risk of debris flow is of quasi-periodicity. A formula of risk estimation is derived. Analysis of relative factors reveals the relationship between frequency and size of debris flow. For a debris flow creek, the longer the time interval between two occurrences of debris flows is, the bigger the bursting event will be.

关键词： debris flow, periodicity, estimating method.

The Optimal Cross-section Design of the “Trapezoid-V” Shaped Drainage Canal of Viscous Debris Flow

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Journal of mountain Science 2011年第1期8卷 103-107页

作者： YOU Yong Key Laboratory of mountain Hazards and Earth Surface Process Chinese Academy of Sciences Chengdu 610041 China Institute of mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China

Debris flow drainage canal is one of the most widely used engineering measures to prevent and manage debris flow *** shape and the sizes of the cross-section are important parameters when design debris flow drainage ***,how to design the appropriate shape and sizes of the cross-section so that the drainage canal can have the optimal drainage capacity is very important and few researched at home and *** study was conducted to analyze the hydraulic condition of a Trapezoid-V shaped drainage canal and optimize its *** assuming characteristic sizes of the cross-section,the paper deduced the configuration parameter of the cross-section of a Trapezoid-V shaped debris flow drainage *** theory analysis,it indicates that the optimal configuration parameter is only related to the side slope coefficient and the bottom transverse slope *** this study,the Heishui Gully,a first-order tributary of the lower Jinsha River,was used as an example to design the optimal cross-section of the drainage canal of debris flow.

关键词： Optimal cross-section design Trapezoid- V shaped Drainage canal Viscous debris flow

Impacts of permafrost changes on alpine ecosystem in Qinghai-Tibet Plateau

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Science china Earth sciences 2006年第11期49卷 1156-1169页

作者： WANG Genxu1,3 , LI Yuanshou2., WU Qingbai2.& WANG Yibo3 1. Institute of mountain Hazards and Environment, chinese Academy of {2., Chengdu 610041, china 2. Cold and Arid Regions Environmental and Engineering Research Institute, chinese Academy of {2., Lanzhou 730000, china 3. Resource and Environment School, Lanzhou University, Lanzhou 730000, china Institute of mountain Hazards and Environment Chinese Academy of Sciences Chengdu China Resource and Environment School Lanzhou University Lanzhou China Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China

Alpine cold ecosystem with permafrost environment is quite sensitive to climatic changes and the changes in permafrost can significantly affect the alpine ecosystem. The vegetation coverage, grassland biomass and soil nutrient and texture are selected to indicate the regime of alpine cold ecosystems in the Qinghai-Tibet Plateau. The interactions between alpine ecosystem and permafrost were investigated with the depth of active layer, permafrost thickness and mean annual ground temperature (MAGTs). Based on the statistics model of GPTR for MAGTs and annual air temperatures, an analysis method was developed to analyze the impacts of permafrost changes on the alpine ecosystems. Under the climate change and human engineering activities, the permafrost change and its impacts on alpine ecosystems in the permafrost region between the Kunlun mountains and the Tanggula Range of Qinghai-Tibet Plateau are studied in this paper. The results showed that the per- mafrost changes have a different influence on different alpine ecosystems. With the increase in the thickness of active layer, the vegetation cover and biomass of the alpine cold meadow exhibit a significant conic reduction, the soil organic matter content of the alpine cold meadow ecosystem shows an exponential decrease, and the surface soil materials become coarse and gravelly. The alpine cold steppe ecosystem, however, seems to have a relatively weak relation to the permafrost environment. Those relationships resulted in the fact that the distribution area of alpine cold meadow decreased by 7.98% and alpine cold swamp decreased by 2..11% under the permafrost environment degradation during recent 15 years. In the future 50 years the alpine cold meadow ecosystems in different geomorphologic units may have different responses to the changes of the permafrost under different climate warming conditions, among them the alpine cold meadow and swamp ecosystem located in the low mountain and plateau area will have a relatively

关键词： permafrost environment, alpine cold ecosystem, statistics relationship, climate change, impacts, Qinghai-Tibet Plateau.