钱塘江河势变迁与径潮流相互作用研究

基于平面二维水沙床耦合地貌模型,反演了1958年1月至1964年12月连续枯水年期间钱塘江尖山河段的主槽摆动过程,揭示了河势由顺直到弯曲的主要演变规律和内在机制.结果表明,在低径流和强潮流作用下,丰水年形成的北部落潮槽逐渐淤积形成浅滩,南部涨潮槽冲刷发展形成南、北两支,两槽间江心滩发育壮大,形成弯曲河势.河床冲淤主要集中在前两年内,潮汐周期内涨潮初期冲刷、涨憩和落潮初期淤积,区域淤积泥沙主要来源于下游杭州湾,北槽前期淤积为落潮型淤积,后期为涨潮型淤积.河势变化使得区域潮差增大潮动力增强,南槽涨落潮流速显著增大.顺直河势下,江心滩南北两侧分流比差异不大,涨潮期间南侧略高、落潮期间北槽略高.弯曲河势下,南槽水深和纳潮量增加,涨、落潮分流比均显著增大至75％以上.     

浮游生态系统非线性动力学研究

建立了新的藻类-浮游动物生态非线性动力学模型,该模型考虑了藻类与浮游动物之间的增长关系。研究了模型平衡点的稳定性,以及Hop f分岔现象。通过对选取的分岔参数进行分析,揭示了该系统的动力学特性。     

Impact of the surface temperature and vertical shear of zonal wind on the dynamics of a simple two-layer model of the atmosphere

The paper presents and analyzes, from the point of view of smooth dynamic systems theory, a two-layer baroclinic model of the troposphere in geostrophic approximation. The model describes airflow in β-channel within the tropospheric part of the main Hadley circulation cell. It enables to obtain, after application of the Galerkin method, a fairly simple low-parametric dynamic system describing the phenomena of non-linear interactions, bifurcations and blocking in the atmosphere. This enables to take into consideration such basic factors influencing the atmospheric dynamics like the heat exchange within the surface, orography, vertical variability of zonal wind and hydrostatic stability. Impact of zonal thermal variability of the surface and vertical shear of zonal wind in the troposphere on the orographic bifurcation was investigated and the oscillation character in the dynamic system after Hopf bifurcation of the second kind was analyzed. Additionally, the model dynamics was investigated in conditions including momentum forcing in the upper and lower parts of the troposphere and excluding orographic interaction, as well as in the conditions of thermal interaction between the troposphere and the surface for the vertical shear of zonal wind in both tropospheric layers. Impact of the mean zonal wind in the troposphere on the properties of model dynamics was assessed. It was proved that zonally varied surface temperature and layered mean zonal wind in the atmosphere are the parameters that have basic influence on the model dynamics. They cause numerous bifurcations and strongly influence the periods of oscillations of the model variables. They are often Hopf bifurcations of the second kind during which tropospheric states fairly distant from the ones before the bifurcations are generated. This significantly influences the model predictability.     

分岔隧道变形监测与施工对策研究

分岔隧道是一种新型结构形式的隧道。以八字岭分岔隧道为工程背景,首先介绍了分岔隧道现场变形监测方法;接着分析了在当前支护和施工方案条件下隧道纵向变形特点、大拱段伴随开挖和支护进行表现出来的施工动态响应特点及隧道开挖面表现出来的空间效应特点。最后,在分析隧道变形特点的基础上,给出了相应的施工对策。研究结果为分岔隧道的设计、施工提供了必要的依据。     

Classification of Motions for Generalization of the two Centers Problem on a Sphere

The generalization of a test particle motion in a central field of two immovable point-like centers to the case of a constant curvature space, on a three-dimensional sphere, is investigated in the paper. The bifurcation set in the plane of integrals of motion is constructed and the classification of the domains of possible motion is carried out on a two-dimensional sphere. The regularization of the Kepler’s problem on a two-dimensional sphere is carried out. This revised version was published online in July 2006 with corrections to the Cover Date.     

层状地基-非线性结构系统地震响应特性分析

根据从系统能量导出的地震动力方程,采用渐近解析法对层状地基 非线性结构系统的地震响应进行了分析,给出了共振区的振幅-频率以及相位-频率的解析公式,并对地基参数的不同取值,给出了一系列相应的计算结果。进而根据计算结果分析了地基参数对结构地震响应特性的影响,讨论了共振区畸变、振幅的分叉和突变现象以及“路径”效应等非线性动力特性。分析结果表明,同一类别地基的参数变化对结构的动力特性有显著的影响,按现行抗震设计方法对层状地基 非结构系统进行抗震分析时,可能产生较大的偏差,需考虑相互作用和非线性特性,以使设计参数更合理和优化。     

顺层边坡岩体结构的模态幅值研究

针对顺层边坡岩体结构变形的特点,利用后屈曲能量准则建立了平衡稳定模态幅值方程,给出了平衡分叉点附近的邻域及边坡坡脚剪切滑动的判据。根据岩体边坡渐近性破坏的机理和流变变形的特征,分析了可能影响模态幅值的各种因素,给出了以坡长为控制变量的平衡稳定模态幅值的极值。     

赤潮藻类生态营养模型非线性动力研究

基于营养盐、赤潮藻类、植食浮游动物之间的食物链关系,考虑到由于海洋内微生物分解动植物遗体对营养盐的补充以及物理因素导致的流失,文中建立了营养盐一赤潮藻类一植食性浮游动物相互作用的耦合生态动力学模型。运用现代非线性动力学理论,对模型解的动力学稳定性进行了分析。结果表明,随着参数的变化,系统稳定性也随之变化,甚至出现HOPF分岔现象。     

Wave propagation and strain localization in a fully saturated softening porous medium under the non‐isothermal conditions

The (THM) coupling effects on the dynamic wave propagation and strain localization in a fully saturated softening porous medium are analyzed. The characteristic polynomial corresponding to the governing equations of the THM system is derived, and the stability analysis is conducted to determine the necessary conditions for stability in both non‐isothermal and adiabatic cases. The result from the dispersion analysis based on the Abel–Ruffini theorem reveals that the roots of the characteristic polynomial for the THM problem cannot be expressed algebraically. Meanwhile, the dispersion analysis on the adiabatic case leads to a new analytical expression of the internal length scale. Our limit analysis on the phase velocity for the non‐isothermal case indicates that the internal length scale for the non‐isothermal THM system may vanish at the short wavelength limit. This result leads to the conclusion that the rate‐dependence introduced by multiphysical coupling may not regularize the THM governing equations when softening occurs. Numerical experiments are used to verify the results from the stability and dispersion analyses. Copyright © 2016 John Wiley & Sons, Ltd.     

CUSP突变模型在地壳形变和强震危险性判定中的应用

应用ＣＵＳＰ（尖角）突变模型研究了板内边界带地壳形变与强震的危险性判定及其预测的方法，并以鲜水河断裂带１９７３～１９８２年的动态大地测量和地震活动数据作了验证。结果表明：（１）强震前该断裂带地壳形变与蕴震系统经历了稳定平衡—不稳定平衡—稳定平衡—不稳定平衡—近于临界状态的过程。（２）系统的不稳定平衡状态在不同的观测点位具有同步性和持续性，且持续的时间与未来的地震强度有关。（３）预测未来事件发生的时间、震级、位移与实际发生的事件基本相符。