内蒙古锡林河流域空间生态学研究

本文从物种和景观两个组织水平上研究了气候、土壤、地形等自然环境因子和人类活动因子对生物空间分布格局的影响。基于锡林河流域地理信息系统各环境因子的专题数据，利用空间异质性分析方法研究了锡林河流域环境因子的空间分布格局;基于锡林河流域野外调查数据，运用空间异质性分析方法研究了重要物种的空间分布格局，并采用典范对应分析(Canomc Correspondence Analvsis，CCA)方法分析了物种分布与环境因子的关系：基于锡林河流域地理信息系统各环境因子的专题数据，研究了锡林河流域植被斑块的空间格局特征及其与环境因子的关系，并采用典范对应分析方法分析了植被类型组成与环境因子的关系：基于内蒙古草原生态系统定位研究站放牧样地的样方调查数据．采用空间异质性分析方法，研究了放牧压力对物种空间分布格局的影响：基于多年的卫星遥感数据，采用建模和对比等方法，研究了定居放牧方式下植被状况空间变化规律及植被状况时空变化与人类活动、社会经济发展的关系。通过上述分析，得到的主要结论如下： 1、锡林河流域各个环境因子都具有自己的空间特征尺度，共同形成多尺度等级体系，按特征尺度的大小可以分为如下3个组： ·小尺度组(15km左右)：有机暖、全N的较小的特征尺度 ·中尺度组(30～50km)：T1，碳酸钙含量．PER、全N和海拔高度的较小的特征尺度 ·大尺度组(100km左右)：ANNR，PER、全N和海拔高度的较大的特征尺度多尺度等级的生态学意义是它反映生态变量异质斑块的镶嵌和包含特征，环境因子多尺度等级体系反映共性，具有普遍性：反映生态关系，具有生态学意义。 2、对物种空间异质性的Mantel检验和半方差分析得到了一致的结果产即羊草、糙隐子草和星毛萎菱菜在锡林河流域的空间分布呈现随机特征，而大针茅和冷蒿则表现为十分显著的格局特征。按分布格局的显著程度从大到小排列为冷蒿>大针茅>星毛萎菱菜>糙隐子草>羊草。理论半方差图显示大针茅和冷蒿的空间自相关域分别为30．447公里和30公里。物种空间分布格局是受自然条件、人类活动以及它们自身的生理生态特征综合决定的，物种自身的生理生态特征决定了它们对外界环境变化的适应性反应机制，而自然与人类活动这两种因素在空间的交错配置决定了物种适应性反应的方向和程度，从而综合导致物种空间分布格局的形成。 3、对锡林河流域物种分布与环境因子关系的CCA分析和交叉半方差方法分析显示：1)气候因子(11个指标)、土壤性状因子(3个指标)和地形因子(3个指标)对物种分布的贡献率分别为11．2％、9．5％和11％，三者总和为31．7％。2)各个环境因子对物种分布空间作用方向具有一致性，物种分布与环境因子几乎都在135。和157．5。两个方向上具有相对明显的相关性，从锡林河流域来看，这两个方向反映了气候、土壤以及地形从东南往西北的变化梯度方向。 4、对锡林河流域14个植被景观指数进行的PCA分析表明，锡林河流域植被斑块空间分布的物理特征主要表现在斑块的数目和大小方面，其次是在斑块的多样性方面，并可将它们分为4个组，分别反映锡林河流域植被斑块的不同特征： ·第一组：NP、PRD、LPI、MPS、PSSD和TE，主要反映景观斑块在数量和大小方面的特征; ·第二组：SHDI、SIDI、SHEI和SIEI，主要反映景观斑块的多样性特征; ·第三组：PSCV和[J]．主要反映景观斑块之间的相互邻接程度; ·第四组：MSI和AWMSI，主要反映景观斑块的形状特征。 MPS和PSSD两个指数与环境因子无论是在相关系数的性质还是显著程度上都保持了很好的一致性，它们与纬度(LAT)及可能蒸散率(PER)呈极显著的正相关关系，而与经度(LNG)、海拔高度(ALT)、年平均降水量(ANNR)及土壤有机质含量(0RG)呈极显著的负相关关系：平均形状指数(MSI)只与LAT呈显著的正相关关系;多样性指数和扩散毗连指数与任何一个环境因子都没有表现出显著的相关性。 5、锡林河流域植被分布与环境因子的关系CCA排序方法分析表明，气候因子(11个指标)、土壤性状因子(3个指标)和地形因子(3个指标)对植被分布的贡献率分别为19.8%、11.1%和14.5%，三者总和为45.4％。环境因子在植被和物种两个水平上的贡献率表现了相似的特点，自然环境因子不能完全解释植被的空间分布，人类活动的影响应该受到重视。 6、放牧压力对物种空间分布格局的研究表明： ·牧压对温带典型草原物种的空间分布格局有明显的影响。随着牧云的增大，属于原生群落物种的羊草与大针茅空间分布的随机性减小，空间自相关尺度逐渐增大;而对于退化过程中的入侵物种冷蒿和星毛萎菱菜，其空间分布的随机性逐渐增大．空间自相关尺度也呈增大趋势。在牧压胁迫超过一定水平时，冷蒿空间分布的自相关尺度开始下降，而星毛萎菱菜的空间分布格局则表现出强烈的随机性。 ·物种空间格局的变化是反映群落演替过程较为稳定的特征，适用于不同放牧条件下 群落之间的比较。 7、利用遥感数据对人类活动对植被影响的研究表明： ·定居放牧方式下，NDVI随定居点距离的变化格局经历了3个阶段。第一阶段，草场处于原生阶段，NDVI不随距离变化;第二阶段，定居点附近开始局部退化，NDVI随距离增加而增大：第三阶段，退化区域扩大，NDVI不随距离变化。 ·在草场局部退化阶段，NDVI随距离的变化呈对数函数规律，定居点的放牧区具有放牧半径、原生NDVI值、NDVI变化率等特征。根据这些特征、NDVI对数规律以及NDVI与地上生物量的关系可以推测定居点的总载畜量。 ·锡林河流域从87年到85年NDVI值降低最大的区域为流域的中部和南部，这与这一区域人类活动强度以及社会经济发展具有密切关系。

Characteristic Dimensionless Numbers in Multi-Scale and Rate-Dependent Processes

For this sake, the macroscopic equations of mechanics and the kinetic equations of the microstructural transformations should form a unified set that be solved simultaneously. As a case study of coupling length and time scales, the trans-scale formulation

Synchronous Multi-Scale Observations on Rock Damage and Rupture

This paper reports a multi-scale study on damage evolution process and rupture of gabbro under uniaxial compression with several experimental techniques, including MTS810 testing machine, white digital speckle correlation method, and acoustic emission technique. In particular, the synchronization of the three experimental systems is realized for the study of relationship of deformation and damage at multiple scales. It is found that there are significant correlation between damage evolution at small and large length scales, and rupture at sample scale, especially it displays critical sensitivity at multiple scales and trans-scale fluctuations.

Extended self-similar scaling law of multi-scale eddy structure in wall turbulence

The longitudinal fluctuating velocity of a turbulent boundary layer was measured in a water channel at a moderate Reynolds number. The extended self-similar scaling law of structure function proposed by Benzi was verified. The longitudinal fluctuating velocity, in the turbulent boundary layer was decomposed into many multi-scale eddy structures by wavelet transform. The extended self-similar scaling law of structure function for each scale eddy velocity was investigated. The conclusions are I) The statistical properties of turbulence could be self-similar not only at high Reynolds number, but also at moderate and low Reynolds number, and they could be characterized by the same set of scaling exponents xi (1)(n) = n/3 and xi (2)(n) = n/3 of the fully developed regime. 2) The range of scales where the extended self-similarity valid is much larger than the inertial range and extends far deep into the dissipation range,vith the same set of scaling exponents. 3) The extended selfsimilarity is applicable not only for homogeneous turbulence, but also for shear turbulence such as turbulent boundary layers.

Multi-scale analysis of AFM tip and surface interactions

Thoroughly understanding AFM tip-surface interactions is crucial for many experimental studies and applications. It is important to realize that despite its simple appearance, the system of tip and sample surface involves multiscale interactions. In fact, the system is governed by a combination of molecular force (like the van der Waals force), its macroscopic representations (such as surface force) and gravitational force (a macroscopic force). Hence, in the system, various length scales are operative, from sub-nanoscale (at the molecular level) to the macroscopic scale. By integrating molecular forces into continuum equations, we performed a multiscale analysis and revealed the nonlocality effect between a tip and a rough solid surface and the mechanism governing liquid surface deformation and jumping. The results have several significant implications for practical applications. For instance, nonlocality may affect the measurement accuracy of surface morphology. At the critical state of liquid surface jump, the ratio of the gap between a tip and a liquid dome (delta) over the dome height (y(o)) is approximately (n-4) (for a large tip), which depends on the power law exponent n of the molecular interaction energy. These findings demonstrate that the multiscale analysis is not only useful but also necessary in the understanding of practical phenomena involving molecular forces. (c) 2007 Elsevier Ltd. All rights reserved.

Multi-scale Calculation of Settling Speed of Coarse Particles by Accelerated Stokesian Dynamics without Adjustable Parameter

The calculation of settling speed of coarse particles is firstly addressed, with accelerated Stokesian dynamics without adjustable parameters, in which far field force acting on the particle instead of particle velocity is chosen as dependent variables to consider inter-particle hydrodynamic interactions. The sedimentation of a simple cubic array of spherical particles is simulated and compared to the results available to verify and validate the numerical code and computational scheme. The improvedmethod keeps the same computational cost of the order O(N log N) as usual accelerated Stokesian dynamics does. Then, more realistic random suspension sedimentation is investigated with the help ofMont Carlo method. The computational results agree well with experimental fitting. Finally, the sedimentation of finer cohesive particle, which is often observed in estuary environment, is presented as a further application in coastal engineering.

Spallation analysis with a closed trans-scale formulation damage evolution

A closed, trans-scale formulation of damage evolution based on the statistical microdamage mechanics is summarized in this paper. The dynamic function of damage bridges the mesoscopic and macroscopic evolution of damage. The spallation in an aluminium plate is studied with this formulation. It is found that the damage evolution is governed by several dimensionless parameters, i.e., imposed Deborah numbers De* and De, Mach number M and damage number S. In particular, the most critical mode of the macroscopic damage evolution, i.e., the damage localization, is deter-mined by Deborah number De+. Deborah number De* reflects the coupling and competition between the macroscopic loading and the microdamage growth. Therefore, our results reveal the multi-scale nature of spallation. In fact, the damage localization results from the nonlinearity of the microdamage growth. In addition, the dependence of the damage rate on imposed Deborah numbers De* and De, Mach number M and damage number S is discussed.

Orientation-based Continuum Damage Models for Rocks

A general formulation of the Helmholtz free energy used in thermodynamics of damage process of rocks is derived within a multi-scale framework. Such a physically-based thermodynamic state potential has a hybrid, discrete/continuum, nature in the sense tha

Trans-Scale Mechanics: Looking For The Missing Links Between Continuum And Micro/Nanoscopic Reality

Problems involving coupled multiple space and time scales offer a real challenge for conventional frameworks of either particle or continuum mechanics. In this paper, four cases studies (shear band formation in bulk metallic glasses, spallation resulting from stress wave, interaction between a probe tip and sample, the simulation of nanoindentation with molecular statistical thermodynamics) are provided to illustrate the three levels of trans-scale problems (problems due to various physical mechanisms at macro-level, problems due to micro-structural evolution at macro/micro-level, problems due to the coupling of atoms/molecules and a finite size body at micro/nano-level) and their formulations. Accordingly, non-equilibrium statistical mechanics, coupled trans-scale equations and simultaneous solutions, and trans-scale algorithms based on atomic/molecular interaction are suggested as the three possible modes of trans-scale mechanics.

工程地质三维可视化技术及其工程应用研究

Study of 3D visualization technology of engineering geology and its application to engineering is a cross subject which includes geosciences, computer, software and information technology. Being an important part of the secondary theme of National Basic Research Program of China (973 Program) whose name is Study of Multi-Scale Structure and Occurrence Environment of Complicated Geological Engineering Mass(No.2002CB412701), the dissertation involves the studies of key problems of 3D geological modeling, integrated applications of multi-format geological data, effective modeling methods of complex approximately layered geological mass as well as applications of 3D virtual reality information management technology.The main research findings are listed below:Integrated application method of multi-format geological data is proposed,which has solved the integrated application of drill holes, engineering geology plandrawings, sectional drawings and cutting drawings as well as exploratory trenchsketch. Its application can provide as more as possible fundamental data for 3Dgeological modeling.A 3D surface construction method combined Laplace interpolation points withoriginal points is proposed, so the deformation of 3D model and the crossing error ofupper and lower surface of model resulted from lack of data when constructing alaminated stratum can be eliminated.3D modeling method of approximately layered geological mass is proposed,which has solved the problems of general modeling method based on the sections or points and faces when constructing terrain and concordant strata.The 3D geological model of VII dam site of Xiangjiaba hydropower stationhas been constructed. The applications of 3D geological model to the auto-plotting ofsectional drawing and the converting of numerical analysis model are also discussed.3D virtual reality information integrated platform is developed, whose mostimportant character is that it is a software platform having the functions of 3D virtualreality flying and multi-format data management simultaneously. Therefore, theplatform can load different 3D model so as to satisfy the different engineeringdemands.The relics of Aigong Cave of Longyou Stone Caves are recovered. Thereinforcement plans of 1# and 2# cave in phoenix hill also be expressed. The intuitiveexpression provided decision makers and designers a very good environment.The basic framework and specific functions of 3D geological informationsystem are proposed.The main research findings in the dissertation have been successfully applied to some important engineering such as Xiangjiaba hydropower station, a military airport and Longyou Stone Caves etc.