滇西褐煤伴生元素锗的富集及评价

阐述了滇西褐煤中锗富集规律及其评价方法和回收利用等问题。指出在滇西122个第三系聚煤盆地中,仅有几个矿区褐煤中富锗,而它们仅分布在澜沧江以西大片花岗岩出露区,可见富锗煤矿区只在特定的地球化学环境中才能形成。含锗价值较大矿区在富锗段最小勘探网度应不小于100m,进一步圈定留待开采过程中加密取样。在充分利用了煤的热值后,应在烟尘及煤灰中回收锗,吨煤中锗的价值比煤本身高得多。     

从企业地理角度研究我国区域发展的一个分析构架

从我国的国情出发,在企业地理学内容的一个方面－－企业对地区经济发展的影响。探讨了仍中国特色的企业地理分析构架,文章说明我于理需要研究区域企业群本身的行为以及区域发展中政府行为对企业群的影响,最后从目前世界范围内跨国公司当地经的战略行为出发进一步指出了从企业地理角度研究区域发展的重要性。     

Drained instability analysis of sand under biaxial loading using a 3D material model

The diffused and localized instabilities in sand under drained biaxial loading have been analyzed here following a plane strain bifurcation framework, where the rate independent material is defined using a generalized 3D non-associative constitutive model. This study is focused on how various instability modes emerge with respect to initial density, confining pressure, and the applied boundary conditions. Results from large deformation framework have been compared with those from small deformation approximation and the later is noticed to fail in capturing the emergence of diffused modes and predicts delayed onset of localization. The theoretical predictions compares well with existing experimental observations.     

The role of non‐coaxiality in the simulation of strain localization based on classical and Cosserat continua

It is normally accepted that materials inside the shear band undergo severe rotation of the principal stress direction, which causes non‐coaxiality between the principal stress and principal plastic strain rate. However, classical plasticity flow theory implicitly assumes that the principal stress and the principal plastic strain rate are coaxial; thus, it may not correctly predict the onset of the shear band. In addition, classical continuum does not contain any internal length scales; as a result, it cannot provide a reasonable shear band thickness. In this study, the original vertex non‐coaxial plastic model based on the classical continuum is extended to the Cosserat continuum. The corresponding codes are implemented via the interface of the user defined element subroutine in ABAQUS. Through a simple shear test, the effectiveness of the user's codes is verified. Through a uniaxial compression test, the influence of non‐coaxiality on the onset, the orientation, and the thickness of the shear band is investigated. Results show that the onset of the shear localization is delayed, and the thickness of the shear band is widened when the non‐coaxial degree increases, while the orientation of the shear band is little affected by the non‐coaxial degree. In addition, it is found that the non‐coaxiality can weaken the micro‐polar effect to some extent; nonetheless, the Cosserat non‐coaxial model still has its advantage over the classical non‐coaxial model in capturing the pre‐bifurcation as well as the post‐bifurcation behaviors of strain localization. Copyright © 2016 John Wiley & Sons, Ltd.     

A stabilized Smoothed Particle Hydrodynamics,Taylor–Galerkin algorithm for soil dynamics problems

Modelling of failure under dynamic conditions in geomaterials with finite elements presents a series of complex problems, among which we can mention those of (i) volumetric locking, which results on higher failure loads, (ii) influence of mesh alignment, resulting to unrealistic failure surfaces, (iii) diffusion of the shear band over some element widths, (iv) nonoptimal propagation properties (numerical diffusion and dispersion), (v) fulfilling Babuska–Brezzi conditions when using the same order of interpolation for displacement and pressures in coupled problems and (vi) large deformation analysis. This paper is based on previous work done by the authors, who developed a mixed approximation based on (i) casting the dynamic problem in the form of a system of first order PDEs and (ii) using stresses and velocities as nodal variables. The equations were discretized following a Taylor–Galerkin algorithm, first in time using a Taylor expansion and then in space using Galerkin method. The model was limited to small deformations. The purpose of this paper is to show how Taylor–Galerkin method can be extended to meshless formulations, such as the SPH method. The algorithm consists of (i) discretizing in time using a Taylor series expansion complemented with integration of source terms using a Runge–Kutta scheme and then (ii) discretizing in space using the SPH method. It is shown how the proposed method keeps the advantages of the Taylor–Galerkin method in Finite Elements (good propagation properties and capturing of shear bands) and avoids the tensile instability. A set of test problems ranging from elastic propagation of a wave in a bar to failure of a slope on a cohesive softening material are used to assess the performance of the method. Copyright © 2011 John Wiley & Sons, Ltd.     

Spectral analysis of nonlocal regularization in two‐dimensional finite element models

Strain‐softening in geomaterials often leads to ill‐posed boundary‐valued problems (BVP), which cannot be solved with finite element methods without introducing some kind of regularization such as nonlocal plasticity. Hereafter we propose to apply spectral analysis for testing the performance of nonlocal plasticity in regularizing ill‐posed BVP and producing mesh‐independent solutions when local plasticity usually fails. The spectral analysis consists of examining the eigenvalues and eigenvectors of the global tangential stiffness matrix of the incremental equilibrium equations. Based on spectral analysis, we propose a criterion for passing or failing the test of constitutive regularization in the context of BVP. If the eigenvalues of the tangential operator are all positive then the regularization succeeds, otherwise it fails and may not prevent artificial mesh‐dependent solutions from appearing. The approach is illustrated in the particular case of a biaxial compression with strain‐softening plasticity. In this particular case, local softening plasticity is found to produce negative eigenvalues in the tangential stiffness matrix, which indicates ill‐posed BVP. In contrast, nonlocal softening plasticity always produces positive eigenvalues, which regularizes ill‐posed BVP. The dominant eigenvectors, which generate localized deformation patterns, have a bandwidth independent of mesh size, provided that the mesh is fine enough to capture localization. These mesh‐independent eigenmodes explain why nonlocal plasticity produces numerical solutions that are mesh‐independent. Copyright © 2011 John Wiley & Sons, Ltd.     

基于广义S变换时频滤波的MT数据去噪

针对油气勘探中大地电磁(MT)数据易受各类干扰的污染,且信噪难以分离的问题,把基于广义S变换的时频滤波技术应用于MT数据处理中来,得到MT数据的S域时频分布,分析受噪MT数据在S域的时频分布特征,再在S变换时频域进行时频阈值去噪,并对滤波后的S域时频谱进行逆变换重构,分离得到去噪后的MT数据。给出了基于广义S域时频滤波的方法原理与应用步骤,对被污染的仿真和实测MT数据进行了时频阈值滤波,并与小波阈值去噪方法进行了比较研究。结果表明：基于广义S变换的时频滤波方法可有效抑制MT数据中的干扰,从噪声信号中分离出有效的大地电磁数据,且减少了人为参与,提高了MT勘测的数据质量。     

岩石受压状态的损伤分析

以损伤力学的方法对岩石在受压状态下的破坏行为进行了分析，损伤力学（CDM）方法近年来在金属、混凝土及复合材料等工程材料的蠕变、断裂等问题的研究中得到大量应用。损伤演变是物质内部结构的不可逆变化过程，损伤变量是与塑性变形一样的内变量，文中据实验数据推导出某类岩石的损伤变量演化曲线，以及损伤与应力的变化关系，以期用损伤学方法研究岩石变形的局部化行为。     

Highly Localized Vernacular Regionalization in the Allentown-Bethlehem Area,PA-NJ*

Yi-Fu Tuan's cognitive theory of the construction of place suggests the need for a higher level of resolution in research on American local vernacular regions. A survey-based case study of the Allentown-Bethlehem area demonstrates that municipal data can substantially refine an existing county-based delimitation by revealing previously undocumented regions and subregions, areas with mixed regional identity, and areas lacking regional identity. The resulting delimitations of subcounty vernacular regions are sufficiently precise to disclose a striking correspondence with area school districts.     

论边缘定位：玢岩型铁硫多金属矿床定位的动力学机制

通过庐枞中生代火山岩地区成矿时空结构的研究,提出了玢岩型铁硫多金属矿床定位的动力学——边缘定位机制,总结出该区的4种边缘定位形式和引起边缘定位的两方面动力学因素,最后建立了该区构造、火山—岩浆、岩性多因素控制的边缘定位模式.