Numerical simulation of landslide impulsive waves by incompressible smoothed particle hydrodynamics

An incompressible‐smoothed particle hydrodynamics (I‐SPH) formulation is presented to simulate impulsive waves generated by landslides. The governing equations, Navier–Stokes equations, are solved in a Lagrangian form using a two‐step fractional method. Landslides in this paper are simulated by a submerged mass sliding along an inclined plane. During sliding, both rigid and deformable landslides mass are considered. The present numerical method is examined for a rigid wedge sliding into water along an inclined plane. In addition solitary wave generated by a heavy box falling inside water, known as Scott Russell wave generator, which is an example for simulating falling rock avalanche into artificial and natural reservoirs, is simulated and compared with experimental results. The numerical model is also validated for gravel mass sliding along an inclined plane. The sliding mass approximately behaves like a non‐Newtonian fluid. A rheological model, implemented as a combination of the Bingham and the general Cross models, is utilized for simulation of the landslide behaviour. In order to match the experimental data with the computed wave profiles generated by deformable landslides, parameters of the rheological model are adjusted and the numerical model results effectively match the experimental results. The results prove the efficiency and applicability of the I‐SPH method for simulation of these kinds of complex free surface problems. Copyright © 2007 John Wiley & Sons, Ltd.     

The stability of a Cournot oligopoly: the effects of adaptive expectations

It is crucial to characterize the long-term behaviour for oligopolistic firms by the analysis of asymptotic stability of the equilibrium. Convergent trajectories are usually preferred in the traditional market since unstable orbits may make the behaviour unpredictable. Under some fairly general and reasonable assumptions in an oligopolistic industry, a Cournot oligopoly model is constructed where each firm maximizes its profit in consideration of adaptive expectations with respect to its rivals' choices. We finally arrive at the conclusion that the introduction of adaptive expectations can contribute largely to the convergence to Nash equilibrium, making the long-run market behaviour more predictable.     

基于光纤光栅传感的管道滑坡监测方法研究

针对铺设在滑坡体内的管道,提出了基于光纤光栅传感的管道滑坡监测方法。阐述了已知管道上三点应力求最大应力的方法。采用温度自补偿式光纤光栅应变传感器监测管体应力,对传感器测量的5.12汶川地震后管体应力数据进行分析。结果表明:地震对滑坡有显著影响,发生了浅层滑动面的较大位移;管体的应力都有显著增长,但总应力水平还低于预警阈值,尚处于安全状态。     

石榴树包滑坡变形监测及演化趋势分析

石榴树包滑坡是长江三峡河段中大型滑坡之一———黄腊石滑坡群的一个重要组成部分,它位于巴东县城东1.5km的长江北岸,下距三峡坝址66km。该滑坡体现代变形活动自20世纪70年代以来渐趋明显,特别是三峡水库蓄水以来,滑坡的变形十分显著。本文在调查分析石榴树包滑坡形态特征、结构特征及变形破坏特征的基础上,基于滑坡10多年的变形监测资料,研究了石榴树包滑坡的影响因素和变形演化特征和规律,并利用灰色GM(1,1)模型预测了滑坡的变形发展趋势,为滑坡减灾防灾实践和滑坡治理方案的设计提供了依据。     

Coupling between finite element method and material point method for problems with extreme deformation

As a Lagrangian meshless method, the material point method (MPM) is suitable for dynamic problems with extreme deformation, but its efficiency and accuracy are not as good as that of the finite element method (FEM) for small deformation problems. Therefore, an algorithm for the coupling of FEM and MPM is proposed to take advantages of both methods. Furthermore, a conversion scheme of elements to particles is developed. Hence, the material domain is firstly discretized by finite elements, and then the distorted elements are automatically converted into MPM particles to avoid element entanglement. The interaction between finite elements and MPM particles is implemented based on the background grid in MPM framework. Numerical results are in good agreement with experimental data and the efficiency of this method is higher than that of both FEM and MPM.     

关于滑坡预报问题

边坡观测点位移-时间曲线出现变陡段作为滑坡预报的判据是不充分的。还有一些判据也是不充分的。本文对这些观点从经验和理论上作了阐述。     

Exploring the Interaction of G-quadruplex Binders with a (3 + 1) Hybrid G-quadruplex Forming Sequence within the PARP1 Gene Promoter Region

The enzyme PARP1 is an attractive target for cancer therapy, as it is involved in DNA repair processes. Several PARP1 inhibitors have been approved for clinical treatments. However, the rapid outbreak of resistance is seriously threatening the efficacy of these compounds, and alternative strategies are required to selectively regulate PARP1 activity. A noncanonical G-quadruplex-forming sequence within the PARP1 promoter was recently identified. In this study, we explore the interaction of known G-quadruplex binders with the G-quadruplex structure found in the PARP gene promoter region. The results obtained by NMR, CD, and fluorescence titration, also confirmed by molecular modeling studies, demonstrate a variety of different binding modes with small stabilization of the G-quadruplex sequence located at the PARP1 promoter. Surprisingly, only pyridostatin produces a strong stabilization of the G-quadruplex-forming sequence. This evidence makes the identification of a proper (3+1) stabilizing ligand a challenging goal for further investigation.     

土剪破坏次声监测试验研究

土质滑坡临滑会产生次声波, 次声监测可以作为判断土质滑坡临滑的一种技术手段. 在考虑到滑坡的力学方式是以剪切破坏为主的前提下, 为了探明土质滑坡过程中的次声信号响应特征, 设计了土体直剪实验次声-力-位移联合监测系统, 开展了土体剪破坏次声监测试验, 在次声事件自动拾取的基础上, 结合黏性土渐进性破坏理论, 分析了剪切过程中的微观声学机理, 结果表明: (1)黏性土剪切破坏时发出的次声信号主要来源于弹性阶段中黏土颗粒的相互挤压、弹塑性阶段中以黏土胶体团粒本身的拉张破裂和应变软化阶段中土颗粒间的摩擦; (2)在土体剪切载荷的不同阶段, 次声信号的幅值大小呈现出应变软化阶段<弹性阶段<弹塑性阶段的规律; (3)剪切力与次声信号之间存在较强的相关性, 次声事件的峰值包络线与剪切力趋势线相当吻合, 并且次声信号的均方功率峰值都在推力峰值之前, 平均提前为22.95 s. 研究对进一步利用次声开展土质滑坡的监测和稳定性评价具有重要的理论参考价值.      

塌陷型极值拟共形映射的性质

证明了如果f~μ是单位圆△上塌陷型极值拟共形映射,则存在与f~μ等价的极值拟共形映射f~(?)以及单位圆的子区域G,使得面(z)=0,(?)z∈G.