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Application of three-dimensional discrete element face-to-face contact model with fissure water pressure to stability analysis of landslide in Panluo iron mine

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Science China(Technological sciences) 2005年第z1期48卷 146-156页

作者： ZHANG Lei1,2, WEI Zuoan1, LIU Xiaoyu1 & LI Shihai1 1.Institute of Mechanics, chinese academy of sciences, beijing 100080, China 2.graduate School, chinese academy of sciences, beijing 100060, China chinese Acad Sci Inst Mech Beijing 100080 Peoples R China chinese Acad Sci Grad Sch Beijing 100060 Peoples R China

Three-dimensional discrete element face-to-face contact model with fissure water pressure is established in this paper and the model is used to simulate three-stage process of landslide under fissure water pressure in the opencast mine, according to the actual state of landslide in Panluo iron mine where landslide happened in 1990 and was fathered in 1999. The calculation results show that fissure water pressure on the sliding surface is the main reason causing landslide and the local soft interlayer weakens the stability of slope. If the discrete element method adopts the same assumption as the limit equilibrium method, the results of two methods are in good agreement; while if the assumption is not adopted in the discrete element method, the critical φ numerically calculated is less than the one calculated by use of the limit equilibrium method for the sameC. Thus, from an engineering point of view, the result from the discrete element model simulation is safer and has more widely application since the discrete element model takes into account the effect of rock mass structures.

关键词： face-to-facecontactmodel, fissure water pressure, three-dimensional discrete element method,landslide.

Effects of various solar indices on accuracy of Earth’s thermospheric neutral density models

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Science China(Physics,Mechanics & Astronomy) 2009年第7期52卷 1120-1128页

作者： WANG HongBo1,2 & ZHAO ChangYin1 1 Purple Mountain Observatory, chinese academy of sciences, Nanjing 210008, China 2.graduate university of chinese academy of sciences, beijing 10004., China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China graduate university of chinese academy of sciences Beijing 100049 China

Four kinds of solar indices F10.7, E10.7, S10, Mg10 and four thermospheric neutral density models, i.e., CIRA72, DTM94, NRLMSISE00 and JB2006, are discussed. The CHAMP accelerometer data are used to calculate thermospheric total mass density. Based on the comparison of the model densities with CHAMP observations, the effects of various indices on the model accuracy are detected. It is found that under quiet and moderate solar conditions (F10.7200) the error’s standard deviation using E10.7 increases quickly and causes the models’ accuracy to fall down. With regard to S10, Mg10, their effects under quiet solar conditions are inconspicuous. If under active solar conditions, they can reduce the model error’s standard deviation by 5%-10%, implying that S10, Mg10 make the model error more stable. The JB2006 model, which was constructed by multi-solar-index (F10.7, S10, Mg10), is compared with DTM94 and NRLMSISE00 based on single-solar-index. It is found that JB2006’s accuracy is better than DTM94’s, and is close to NRLMSISE00 under the quiet solar condition. During the solar burst occurring on October 26, 2003, JB2006 has been in best agreement with CHAMP observations. All in all, the new indices may improve thermospheric density models’ accuracy under some special conditions. Concretely, E10.7 may reduce the average error of models and S10, Mg10 may prevent the error’s divergence.

关键词： solar radiation index CHAMP accelerometer data neutrals density model

A new class of symmetric periodic solutions of the spatial elliptic restricted three-body problem

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Science China(Physics,Mechanics & Astronomy) 2009年第9期52卷 1404-1413页

作者： XU XingBo1,2 & FU YanNing1 1 Purple Mountain Observatory, chinese academy of sciences, Nanjing 210008, China 2.graduate university of chinese academy of sciences, beijing 100039, China 1. Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China 2. graduate university of chinese academy of sciences Beijing 100039 China

We show that there exists a new class of symmetric periodic solutions of the spatial elliptic restricted three-body problem. In such a solution, the infinitesimal body is confined to the vicinity of a primary and moves on a nearly circular orbit. This orbit is almost perpendicular to the orbital plane of the primaries, where the line of symmetry of the orbit lies. The existence is shown by applying a corollary of Arenstorf's fixed point theorem to a periodicity equation system of the problem. And this existence doesn't require any restriction on the mass ratio of the primaries, nor on the eccentricity of their relative elliptic orbit. Potential relevance of this new class of periodic solutions to real celestial body systems and the follow-up studies in this respect are also discussed.

关键词： periodic orbits spatial restricted three-body problem symmetric orbits averaging

Terrestrial transect study on driving mechanism of vegetation changes

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Science China Earth sciences 2008年第7期51卷 984-991页

作者： ZHANG YuJin1,2 & ZHOU GuangSheng1 1 State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, chinese academy of sciences, beijing 100093, China 2.graduate university of chinese academy of sciences, beijing 10004., China 1. State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing 100093 China 2. graduate university of chinese academy of sciences Beijing 100049 China

In terms of chinese climate-vegetation model based on the classification of plant functional types, to- gether with climatic data from 1951 to 1980 and two future climatic scenarios (SRES-A2 and SRES-B2) in China from the highest and the lowest emission scenarios of greenhouse gases, the distribution patterns of vegetation types and their changes along the Northeast China Transect (NECT) and the North-South Transect of Eastern China (NSTEC) were simulated in order to understand the driving mechanisms of vegetation changes under climatic change. The results indicated that the vegetation distribution patterns would change significantly under future climate, and the major factors driving the vegetation changes were water and heat. However, the responses of various vegetation types to the changes in water and heat factors were obviously different. The vegetation changes were more sensi- tive to heat factors than to water factors. Thus, in the future climate warming will significantly affect vegetation distribution patterns.

关键词： driving mechanism vegetation terrestrial transect climatic change plant functional types

Effects of diatoms on reproduction and growth of marine copepods

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Progress in Natural Science:Materials International 2004年第10期14卷 1-7页

作者： ZHANG Guangtao 1,2 and SUN Song 1 (1.Key Laboratory of Marine Ecology&Environment sciences,Institute of Oceanology,chinese academy of sciences,Qingdao266071,China 2.graduate School,chinese academy of sciences,beijing100039,China) chinese Acad Sci Inst Oceanol Key Lab Marine Ecol & Environm Sci Qingdao 266071 Peoples R China chinese Acad Sci Grad Sch Beijing 100039 Peoples R China

Two hot spots in marine ecology,deleterious effects of diatoms and feeding selectivity of copepods,as well as new progress on these two issues achieved in the recent ten years,are *** two issues are considered correlated *** and their metabolites can induce deleterious effects on growth,reproduction and development of copepods,including increase of mortality and decrease of egg production,hatching and growth *** negative effects,resulting from either chemical toxin or nutritional defi-ciency,can be conquered in natural environments by diverse *** is therefore concluded that deleterious effects of diatoms observed in laboratory or during blooming period are only a special case that accommodation of feeding strategy of copepods is *** under-stand their feeding strategy in natural environments is a prerequisite to explaining the mechanisms of deleterious effects caused by diatoms,and makes it possible to re-evaluate the energy flow in marine ecosystems.

关键词： diatoms copepod feeding strategy reproduction deleterious effects

The influence of moderate ENSO on summer rainfall in eastern China and its comparison with strong ENSO

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chinese Science Bulletin 2008年第5期53卷 791-800页

作者： XUE Feng1 & LIU ChangZheng1,2 1 Institute of Atmospheric Physics, chinese academy of sciences, beijing 100029, China 2.graduate university of chinese academy of sciences, beijing 10004., China chinese Acad Sci Inst Atmospher Phys Beijing 100029 Peoples R China.

The 6 major ENSO events since 1979 are classified into the strong and moderate ENSO based on in-tensity. The composite analysis is performed to reveal the influence of ENSO on East Asian summer monsoon (EASM) and summer rainfall in eastern China. It is shown that the influence is changed with the seasonal cycle in summer, with a weaker influence in June and a stronger influence in August, in-dicating a long lagged effect of ENSO on EASM. Besides, the circulation and rainfall anomalies caused by the strong ENSO are also stronger with an earlier starting time, while the influence of the moderate ENSO is evident in August. The composite summer rainfall in eastern China for the moderate ENSO exhibits a northern rainfall pattern, which is totally different from the classical ENSO-type rainfall pat-tern. Based on the composite analysis, two moderate ENSO years with a similar intensity (i.e., 1995 and 2003) are compared. The result shows that, the response of EASM to the moderate ENSO during June and July is, to a certain degree, modulated by the circulation systems in mid-high latitudes of Eurasia and in the Southern Hemisphere, thereby inducing a different rainfall distribution in eastern China. In comparison with the strong ENSO in 1983, it is further revealed that, the strong ENSO plays a dominant role in summer rainfall anomalies in eastern China as well as in controlling the influence of the other factors on EASM. The strong ENSO is therefore different with the moderate ENSO.

关键词：中国东部海洋气象学厄尔尼诺现象东亚季风降雨

A cumulant-based parameter estimation algorithm for near-field sources

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Progress in Natural Science:Materials International 2007年第8期17卷 900-905页

作者： Liang Junli~(1,2*) Yang Shuyuan~(1,2) Zhang Junying~3 (1.Institute of Acoustics,chinese academy of sciences,beijing 100080,China 2.graduate School,chinese academy of sciences,beijing 100039,China 3.National Laboratory of Radar Signal Processing,Xidian university,Xi'an 710071,China) [a]Institute of Acoustics Chinese Academy of Sciences Beijing China [b]graduate School Chinese Academy of Sciences Beijing China [c]National Laboratary of Radar Signal Processing Xidian University Xi'an China

To efficiently use the array aperture and avoid the complicated parameter pairing computation,this paper proposes a new cumulant-based algorithm for localizing near-field narrowband ***,this algorithm proposes a symmetric uniform linear ar- ray (ULA),and constructs three cumulant matrices by using the fourth-order cumulants of some properly chosen sensor outputs;second- ly,unlike the conventional parallel factor (PARAFAC) analysis models in data or subspace domain,it forms a three-way array (TWA) in the fourth-order cumulant domain using the three matrices,and analyzes the uniqueness of its low-rank decomposition;thirdly,it jointly estimates the frequency,the direction-of-arrival (DOA),and the range of each near-field source from the matrices via the low-rank de- composition of the *** simulation results are presented to validate the performance of our proposed method.

关键词： array signal processing localization cumulant parallel factor (PARAFAC) analysis three-way array (TWA)

CH_4 uptake flux of Leymus chinensis steppe during rapid growth season in Inner Mongolia,China

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Science China Earth sciences 2010年第7期53卷 977-983页

作者： GENG YuanBo1, LUO GuangQiang1,2 & YUAN GuoFu1 1 Institute of Geographic sciences and Natural Resources Research, chinese academy of sciences, beijing 100101, China 2.graduate university of chinese academy of sciences, beijing 10004., China 1. Institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

The influence of near ground atmosphere CH4 concentration, soil water content, soil Eh, plants, soil temperature, and pH on CH4 uptake flux of Leymus chinensis steppe during rapid growth season was studied using field in-situ measurement in Xilin River basin of Inner Mongolia, China. The results showed that CH4 uptake flux was positively correlated with near ground atmosphere CH4 concentration and soil Eh but negatively correlated with soil water content. Precipitation may decrease the CH4 flux by increasing the soil water content. The average fluxes of three treatments during the observation period were 1.52 (natural conditions, 1.51 (aboveground plants were excluded), and 2.00 mg m?2 d?1 (all plants were removed), respectively. The difference between the CH4 flux of natural condition treatment and that of removing aboveground plants treatment is small, whereas the flux of removing all plants treatment is larger than the other two treatments. This means that the contribution of aboveground plants to CH4 uptake flux is smaller than that of roots or roots-removing process. CH4 uptake flux is not sensitive to soil temperature and the narrow-ranged soil pH (6.36–7.86). The Leymus chinensis steppe acts as a sink for CH4, and thus more studies should be focused on its affecting factors and related mechanisms.

关键词： CH4 uptake flux Leymus chinensis steppe affecting factors static opaque chamber/gas chromatography method

Effects of the grain size distribution on the temperature-dependent magnetic susceptibility of magnetite nanoparticles

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Science China Earth sciences 2010年第7期53卷 1071-1078页

作者： ZHAO XiangYu1,2 & LIU QingSong1 1 Paleomagnetism and Geochronology Laboratory (SKL-LE), Institute of Geology and Geophysics, chinese academy of sciences, beijing 100029, China 2.graduate university of chinese academy of sciences, beijing 10004., China 1. Paleomagnetism and Geochronology Laboratory (SKL-LE) Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Magnetite is an important magnetic remanence carrier in natural samples and therefore is of great interest in paleo-, rock-, and environmental magnetism. The magnetic properties of magnetite depend on many factors, e.g., concentration and grain size distribution (GSD). In this study, we theoretically investigated the temperature-dependent susceptibility (TDS) of magnetite nanoparticles with a lognormal GSD. Results show that the TDS is affected highly by the GSD mainly in three aspects. Firstly, the unblocking process becomes smoother with the increase of distribution width, characterizing as a wider Hopkinson peak on the TDS curve. Secondly, the blocking temperature increases with the increase of the median diameter or/and the distribution width. Thirdly, the maximum susceptibility decreases with the increase of distribution width, and has a logarithmic function relation with the standard deviation of the distribution. As a case study, this model was further applied to the thermal products of the chinese loess/paleosol samples to determine the granulometry of newly-formed magnetite upon heating based on TDS curves. The results demonstrate the fidelity and feasibility of this method to determine the GSD of nano-sized magnetic particles.

关键词： Néel theory temperature dependence of susceptibility grain size distribution