古尔班通古特沙漠生境对植物群落格局的影响     

钱亦兵  吴兆宁  张立运  Shi Qingdong  JIANG Jin  TANG Lisong 《地理学报(英文版)》2004,14(4):447-455

This paper reports a geomorphologic landscape investigation, vegetation survey and soil sampling at 14 sites across the Gurbantunggut Desert between 87°37′09"-88°24′04"E and 44°14′04"-45°41′52′Nl. The study encountered 8 species of low trees and shrubs, 5 of perennial herbs, 8of annual plants and 48 of ephemeral and ephemeroid plants. These species of plants represent one-third of the species found in the Gurbantunggut Desert, and their communities make up a large proportion of desert vegetation with great landscape significance. In the investigation we found that the plant communities are accordingly succeeded with the spatial variation of macro-ecoenvironment.Using Principal Component Analysis (PCA) and Correlation Analysis (CA) we found that the micro-ecoenvironment heterogeneity of aeolian sandy soil′s physical and chemical properties such as soil nutrient, soil moisture, soil salt, pH etc. only impacted the diversity of herb synusia (PIEherb) of the desert, with a negative correlation. Meanwhile, the impact of microhabitat on the plant community pattern with an antagonistic interaction made vegetation′s eco-distribution in a temporary equilibrium.  相似文献   

Structural Evolution of Chepaizi Uplift and its Control on Stratigraphic Deposition in the Western Junggar Basin,China     

NI Minjie  CHEN Shi  LIU Zichao  SHANG Fengkai  QI Jiafu  WANG Lishuang 《《地质学报》英文版》2019,93(4):1060-1075

Geological mapping, interpreted cross sections, structural analyses and residual thickness maps were used to characterize the evolution of stress setting, structure and stratigraphic distribution of the Chepaizi Uplift, which is a NW-SE trending structure located in the Western Junggar Basin. The NS-trending faults show an important transpressional phase during the Late Permian, as demonstrated by tectonic stress field and stratigraphic thickness variations. A major compressional thrusting and strike-slip phase during the Late Jurassic created a series of NW-SE faults that originated by the large-scale uplift event in the Northern Tianshan. Faults were reactivated as thrust and dextral strike-slip faults. In addition, the angular unconformity observed between Jurassic and Cretaceous provide evidence of this tectonic event. Lots of normal faults indicate that the area records southward tilting and regional derived extensional stress that took place during the Neogene. Before that, thick Early Cenozoic strata are widely deposited. The balanced cross-section highlights the evolution of stress setting and stratigraphic distribution of the Chepaizi Uplift.  相似文献   

The time and frequency standard system for FAST receivers     

朱凯  范瑾  Kun Liang  Wei Tang  Zhi-Sheng Gao  Yan Zhu  Yi Feng  Wei-Wei Zhu  Lei Qian  You-Ling Yue  Jin-You Song  Xiang-Wei Shi  Xing-Yi Wang  Ming-Lei Guo  Hang Zhang  Heng-Qian Gan  Hong-Fei Liu  Cheng-Jin Jin  Peng Jiang 《天文和天体物理学研究(英文版)》2020,(5):148-154

This paper reports on the time and frequency standard system for the Five-hundred meter Aperture Spherical radio Telescope(FAST),including the system design,stability measurements and pulsar timing observations.The stability and drift rate of the frequency standard are calculated using 1-year monitoring data.The UTC-NIM Disciplined Oscillator(NIMDO)system improves the system time accuracy and stability to the level of 5 ns.Pulsar timing observations were carried out for several months.The weighted RMS of timing residuals reaches the level of less than 3.0μs.  相似文献   

The Impact of Bias Row Noise to Photometric Accuracy:Case Study Based on a Scientific CMOS Detector     

Li Shao  Hu Zhan  Chao Liu  Haonan Chi  Qiuyan Luo  Huaipu Mu  Wenzhong Shi 《天文和天体物理学研究(英文版)》2024,(2):230-248

We tested a new model of CMOS detector manufactured by the Gpixel Inc,for potential space astronomical application.In laboratory,we obtain some bias images under the typical application environment.In these bias images,clear random row noise pattern is observed.The row noise also contains some characteristic spatial frequencies.We quantitatively estimated the impact of this feature to photometric measurements,by making simulated images.We compared different bias noise types under strict paramete...  相似文献   

Resilient performance of self-centering hybrid rocking walls with curved interface under pseudo-static loading     

Su Xing  Yan Shi  Sun Xianglei  Wang Tao 《地震工程与工程振动(英文版)》2024,(1):65-85

Frame and rocking wall(FRW) structures have excellent resilient performance during earthquakes. However,the concrete at interfacial corners of rocking walls(RWs) is easily crushed due to local extreme compression during the rocking process. An innovative RW with a curved interface is proposed to prevent interfacial corners from producing local damage, enhancing its earthquake resilient performance(ERP). The precast wall panel with a curved interface is assembled into an integral self-centering h...  相似文献   

Distribution of the Pan-African Domains in East Antarctica and Adjacent Areas     

REN Liudong  ZONG Shi  WANG Yanbin  LI Chong 《《地质学报》英文版》2020,94(Z1):45-46

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Characteristics of the Seismic Waves from a New Active Source Based on Methane Gaseous Detonation   总被引：1，自引：0，他引：1  

WANG Weitao  WANG Xiang  MENG Chuanmin  DONG Shi  WANG Zhigang  XIE Junju  WANG Baoshan  YANG Wei  XU Shanhui  WANG Tao 《中国地震研究》2019,33(2):354-366

Active seismic sources are critical for obtaining high resolution images of the subsurface. For active imaging in urban areas, environment friendly and green seismic sources are required. In present work, we introduce a new type of green active source based on the gaseous detonation of methane and oxygen. When fired in a closed container, the chemical reaction, i.e. gaseous detonation, will produce high pressure air over 150MPa. Seismic waves are produced when high pressure air is quickly released to impact the surroundings. The first field experiment of this active source was carried out in December, 2017 in Jingdezhen, Jiangxi Province, where a series of active sources were excited to explore their potential in mine exploration. In current work, we analyzed the seismic waves recorded by near-field accelerators and a dense short-period seismic array and compared them with those from a mobile airgun source, another kind of active source by releasing high pressure air into water. The results demonstrate that it can be used for high resolution near surface imaging. Firstly, the gaseous detonation productions are harmless CO₂ and water, making it a green explosive source. Secondly, the dominant seismic frequencies are 10-80Hz and a single shot can be recorded up to 15km, making it suitable for local structure investigations. Thirdly, it can be excited in vertical wells, similar to traditional powder explosive sources. It can also act as an additional on-land active source to airgun sources, which requires a suitable water body as intermediate media to generate repeating signals. Moreover, the short duration and high frequency signature of the source signals make it safe with no damage to nearby buildings. These make it convenient to excite in urban areas. As a new explosive source, the excitation equipment and conditions, such as gas ratio, sink depth and air-releasing directions, need further investigation to improve seismic wave generation efficiency.  相似文献   

Three-dimensional limit variation analysis on the ultimate pullout capacity of the anchor cables based on the Hoek-Brown failure criterion     

ZUO Shi  ZHAO Lianheng  HU Shihong 《山地科学学报》2024,(3):1036-1047

Only simplified two-dimensional model and a single failure mode are adopted to calculate the ultimate pullout capacity(UPC) of anchor cables in most previous research. This study focuses on a more comprehensive combination failure mode that consists of bond failure of an anchorage body and failure of an anchored rock mass. The three-dimensional ultimate pullout capacity of the anchor cables is calculated based on the Hoek-Brown failure criterion and variation analysis method. The numerical solut...  相似文献   

A nonlinear coupled soil moisture-vegetation model   总被引：1，自引：0，他引：1  

LIU Shikuo  LIU Shi  FU Zuntao  SUN Lan 《大气科学进展》2005,22(3):337-342

Based on the physical analysis that the soil moisture and vegetation depend mainly on the precipitation and evaporation as well as the growth, decay and consumption of vegetation a nonlinear dynamic coupled system of soil moisture-vegetation is established. Using this model, the stabilities of the steady states of vegetation are analyzed. This paper focuses on the research of the vegetation catastrophe point which represents the transition between aridness and wetness to a great extent. It is shown that the catastrophe point of steady states of vegetation depends mainly on the rainfall P and saturation value v0, which is selected to balance the growth and decay of vegetation. In addition, when the consumption of vegetation remains constant, the analytic solution of the vegetation equation is obtained.  相似文献   

Review of the Study of Nonlinear Atmospheric Dynamics in China （1999-2002）   总被引：1，自引：0，他引：1  

DIAO Yin  FENG Guolin  LIU Shi  LIU Shikuo  LUO Dehai  HUANG Sixun  LU Weisong  CHOU Jifan 《大气科学进展》2004,21(3):399-406

Researches on nonlinear atmospheric dynamics in China (1999-2002) are briefly surveyed. This review includes the major achievements in the following branches of nonlinear dynamics: nonlinear stability theory,nonlinear blocking dynamics, 3D spiral structure in the atmosphere, traveling wave solution of the nonlinear evolution equation, numerical predictability in a chaotic system, and global analysis of climate dynamics.Some applications of nonlinear methods such as hierarchy structure of climate and scaling invariance, the spatial-temporal series predictive method, the nonlinear inverse problem, and a new difference scheme with multi-time levels are also introduced.  相似文献