Identification of the diffusion coefficient for a semi-linear hyperbolic-parabolic problem with discontinuous nonlinear terms

Numerical computations concerning geochemical processes in porous media require a knowledge of the values of the macroscopic parameters. In the context of the interpretation of leaching tests one such parameter is the apparent macroscopic diffusivity. In this paper, a mathematical model for dissolution in the presence of diffusion is considered. It is shown that the constant diffusion coefficient can be identifiable when the time integral of the flux is known. Moreover, a practical algorithm for computing the diffusion coefficient is proposed. This revised version was published online in August 2006 with corrections to the Cover Date.     

岩石力学联锁咬合岩块结构稳定性分析

首次建立了岩石力学中的多种联锁咬合岩块结构模型,介绍了块体理论的进展,并采用改进的DDA（块体不连续变形分析）法对块体进行了稳定性分析。     

钢筋混凝土结构倒塌分析的前沿研究

结构倒塌分析主要涉及三个难点，即不连续位移场的描述、接触碰撞分析以及结构倒塌过程中大位移、大转动的描述。本文就国内外研究现状针对结构倒竭的评定标准以及上述三个难点做出评述，同时介绍了作者近期工作，并对今后研究工作做了展望，以供参考。     

无单元法在三维断裂力学中的应用

介绍了无单元法在三维断裂力学问题中的应用。无单元法基于滑动最小二乘拟合,只需结点信息就可建立离散模型。采用罚函数法来满足无单元法的本征边界条件。用可视准则来处理裂纹面对高斯点影响域的隔离作用,推导了裂纹两表面的相互作用对整体平衡方程组的贡献方程。利用单点位移公式来计算三维裂纹前缘点的应力强度因子。通过算例验证了应用该法确定三维裂纹前缘应力强度因子的有效性。     

冲击地压的非线性非连续特征

从冲击地压的现象出发,通过煤岩摩擦滑动试验研究,探讨了冲击地压的非线性非连续特性。在此基础上,提出了冲击地压的控制途径。     

ERRORS OF KINEMATIC-WAVE AND DIFFUSION-WAVE APPROXIMATIONS FOR SPACE-INDEPENDENT FLOWS ON INFILTRATING SURFACES

Error equations for the kinematic-wave and diffusion-wave approximations were derived under simplified conditions for space-independent flows occurring on infiltrating planes or channels. These equations specify error as a function of time in the flow hydrograph. The kinematic-wave, diffusion wave and dynamic-wave solutions were parameterized through a dimensionless parameter γ which is dependent on the initial conditions. This parameter reflects the effect of initial flow depth, channel-bed slope, lateral inflow and channel roughness when the initial condition is non-vanishing; and it reflects the effect of bed slope, channel roughness, lateral inflow and infiltration when the initial condition is vanishing. The error equations were found to be the Riccati equation.     

The morphology and geomorphic evolution of a large chain-of-ponds river system

Rivers with discontinuous watercourses are part of the spectrum of river diversity. Chain-of-ponds types contain irregularly spaced, steep-sided ponds that are separated by preferential flow paths on swampy valley fill. They often contain endangered ecological communities and are receiving greater attention for conservation and restoration. Very little is known about how these river types form, how they have evolved and how they function. Here we present the Late-Quaternary evolution of one of the last remaining large-scale chain-of-ponds systems in Australia, the Mulwaree Ponds. The chain-of-ponds was fully formed by 4.5 ka, with the position and alignment of the ponds being related to the position of pools of a palaeo-river that is up to 100 ka old. Contemporary hydrogeomorphic processes are insufficient to create the ponds, but sufficient to maintain and keep them open. The phases of evolution for this chain-of-ponds system are synchronous with Late-Quaternary changes in fluvial activity documented for other rivers in southeastern Australia. The ponds at Mulwaree have significant preservation potential over thousands of years. In the current landscape they are rare forms, providing significant grounds for conservation and protection of their distinctive geodiversity. © 2020 John Wiley & Sons, Ltd.     

活动断裂对深埋隧洞影响的研究概述

简要叙述了南水北调西线工程面临的活动断裂的问题;介绍了活动断裂的运动方式、几何特征、运动的力学机制及其与地震的关系;详细讨论了活动断裂对隧洞工程的影响机理,并且总结了活动断裂的研究手段,系统地阐述了关于活动断裂的数值模拟方法并提出了有待进一步解决的问题。     

Mantle flow beneath the Asian continent and its force to the crust

Introduction In order to understand the formation of the geological structure and its evolution of the Asian continent, it is needed to investigate the driving forces from the around continents and oceans and from its underlying mantle as well. The super parallel computer has been used to simulate the geodynamical processes in the lithosphere and mantle for a long time in many international works (Bird, 1995; Tackley, 1995). We also calculated the patterns of the global mantle convection on o…     

二维浅水波方程的间断-连续Galerkin方法

将基于二维简化浅水波模型的间断Galerkin有限元与连续Galerkin有限元耦合方法推广至形式更为复杂的浅水波方程,并给出了误差分析以及模型问题的数值算例。