L_n范数准则和地学模型误差及模型参数估计

本文论述了模型误差及模型参数估计的有关问题,具体包括:1)L_n范数准则;2)模型误差的一般表达式;3)线性化模型及模型含误差时的模型参数估计;4)模型的改善与优化;5)计算方案;6)模型误差与L_n范数准则。本文的论述为建立和分析各种具体的地学模型提供了必要的理论和方法。     

岳阳市土地利用结构变化与土地利用绩效的关联度分析

利用信息熵、灰色关联等分析方法对岳阳市2009—2015年土地利用结构信息熵变化规律、土地利用绩效指数以及它们之间的内在联系进行系统分析。结果表明:1时间上,岳阳市土地利用结构信息熵持续增长,土地利用变化主要表现为城镇村及工矿用地、交通运输用地、耕地的大幅增加以及园地、林地、水域及水利设施用地等地类的减少;2空间上,岳阳市各地区信息熵存在较大差异,中心城区信息熵明显高于其他区域,且经济发展水平与信息熵值呈正相关;3岳阳市土地利用绩效指数逐年上升,其中经济绩效对综合绩效的带动作用最明显,公平绩效则相对滞后;4与土地利用绩效相关性最显著的是城镇村及工矿用地、交通运输用地,但关联系数都较低。     

云南北部山原红壤成土年龄的初步研究

根据红壤成土过程中的元素迁移模型，本文初步求解了云南北部山原红壤成土过程中的硅迁移强度值（Px），并对不同海拔高程上的山原红壤发育年龄进行了计算。     

Volume scattering model of the sea surface and its application

In this paper the stochastic Green function method is used to solve random wave equation of the electromagnetic field. The volume scattering coefficient formula of the sea surface containing bubbles is given. It is also point out that when the incident angle of the electromagnetic wave is less than 30°, the surface scattering model is not sufficient. The joint problem of the volume scattering and the surface scattering coefficient in the neighbourhood of incident angle 30° is discussed.     

Dynamic Response of Fluid-Single Leg Gravity Platform-Soil Interaction System

- An approximate method is presented to investigate the earthquake response of the fluid-single leg (shortened for S. L.) gravity platform-soil interaction system. By assuming a suitable form of the velocity potential of the radiation waves and by using the motion equation and the boundary conditions, the unknown coefficients can be obtained. Thereafter the function of frequency for the interaction system may also be obtained. In this paper, the difference of the system dynamic response between rigid foundation is analyzed and the influences of the various foundation geometric dimension and the various water-depth on the hydrodynamic loading and dynamic response of the system is illustrated.     

A Numerical Model for Mixing Areas of Pollutant Discharging into Tidal Flows

- A combined numerical model for computing mixing areas of pollution vertical jet discharging into tidal flows has been developed. This numerical model is composed of a 2-D depth-averaged dynamic far-field numerical model and a 2-D vertical dynamic near-field numerical model. The former uses finite node method to compute velocity, and improved finite node method to compute pollutant concentration distribution; the latter is a k-e turbulence model, and uses SIMPLE (Semi-Implicit Method for Pressure Linked Equations) method to compute velocity. At the same time, the former provides boundary conditions for the latter. This model can simulate both far- field pollutant concentration distribution and near-field vertical recirculation quickly and precisely. This model has been verified by measured data of pollutant F of the Dachang reach of the Changjing River and test data presented by Chen el al. (1992). On the basis of verification, the authors use a designed hydrograph to compute this mixing area for a cer     

Resistive instabilities in rapidly rotating fluids: Linear theory of the convective modes

Abstract

This paper analyzes the linear stability of a rapidly-rotating, stratified sheet pinch in a gravitational field, g, perpendicular to the sheet. The sheet pinch is a layer (O ? z ? d) of inviscid, Boussinesq fluid of electrical conductivity σ, magnetic permeability μ, and almost uniform density ρ _o; z is height. The prevailing magnetic field. B _o(z), is horizontal at each z level, but varies in direction with z. The angular velocity, Ω, is vertical and large (Ω ? V_A/d, where V_A = B₀√(μρ₀) is the Alfvén velocity). The Elsasser number, Λ = σB² ₀/2Ωρ₀, measures σ. A (modified) Rayleigh number, R = gβd²/ρ₀V² _A, measures the buoyancy force, where β is the imposed density gradient, antiparallel to g. A Prandtl number, P_K = μσK, measures the diffusivity, k, of density differences.     

琼东南盆地天然气水合物与浅层气共生体系成藏特征

继我国在神狐海域两次天然气水合物试采成功之后,近几年来在琼东南盆地的勘探证实了天然气水合物的存在,而且钻探表明其与浅层气具有复杂的共生关系.为揭示琼东南盆地深水区天然气水合物与浅层气共生体系成藏特征,结合岩心、测井及三维地震数据,阐明了天然气水合物与浅层气的空间分布特征,研究结果表明,天然气水合物主要赋存在海底以下200 m范围内的沙质沉积物中,且其形成过程与浅层气的垂向运移有关.对天然气水合物与浅层气共生体系成藏特征的深入分析表明,深部热成因气和浅部生物成因气是其重要的气体来源,第四系未固结沙层是良好的储层,且天然气水合物和浅层气共生体系的分布主要受深部气烟囱和断层的控制.浅层气藏为天然气水合物提供稳定的气源条件;第四系块体流沉积与含天然气水合物地层能有效地封堵浅层气的纵向运移,进一步促进浅层气的成藏.因此,天然气水合物的形成与浅层气的发育具有正反馈的相互作用关系,有利于形成更大规模的天然气水合物矿体和浅层气藏,具有良好的商业开发潜力.