高分辨率遥感影像在云南澜沧老厂矿床地质研究中的应用

在云南澜沧老厂矿床地质研究中,高分辨率QuickBird 影像提供了丰富的地质异常信息:影像线-环结构反映出矿床的控矿环形构造及隐伏构造信息;影像色调异常斑块显示了地面围岩蚀变区域;遥感异常与物化探异常的高度吻合,为地质构造分析和成矿预测提供了有用信息和佐证.     

使用Python函数式编程进行空间回归分析

针对使用传统的编程方式进行空间回归分析过于繁杂的问题,本文提出将Python函数式编程引入空间回归分析方法,分析和探讨脚本语言＋函数式编程方式在GIS数据分析中的推广应用前景。编程实践证明,采用Python函数式编程,结合既有的开源软件包,可以有效提高编程效率,减少代码量,将实践人员的注意力集中在问题本身。     

热带风压场平衡特征及其对GRAPES系统中同化预报的影响研究I:平衡特征分析

本文基于GRAPES全球模式的短期预报误差样本,利用赤道波动正规模态研究了热带风、压场平衡特征,并根据这些特征分析了线性平衡方程(LBE)在该区域应用时存在的问题。结果表明:(1)赤道波动能成功解释热带短期预报误差样本的大部分分量,对流层中层为60%~80%,对流层顶和平流层低层为80%以上。(2)在可解释的误差方差中,赤道罗斯贝波(ER)占比仅为30%~55%,其他赤道波动的作用不可忽视。(3)在ER模态基础上引入其他赤道波动会大幅削弱原有风、压场平衡约束,重力惯性波与Kelvin波的作用最为显著。此时,对流层中层位势高度h与u风、v风间的约束接近于零,而平流层低层h-u的平衡特征由Kelvin波主导。(4)LBE主要表达了ER模态下的风、压场平衡特征,与实际情形相比高估了热带风、压场的耦合程度,进一步的改进中需削弱这一虚假平衡,使得热带风、压场分析变得更加独立。     

On turbulence in the quasi-perpendicular bow shock

In this paper we propose to review the fundamental aspects of turbulence theories and their relevance to particle distribution functions observed by the cluster satellites in the quasi-perpendicular shock. The paper focusses on the hierarchical model describing the different levels of plasma turbulence; from the linear theory, through the quasi-linear remedy, to strong turbulence theories in the context of the earth's bow shock. We will discuss very briefly the validity of these approximations, and their relevance as far as satellite observations are concerned. In particular, we will discuss the development of non-Gaussian features in the ion distribution functions through the evaluation of higher order moments such as the kurtosis or flatness and the skewness. We have found that the profile of the kurtosis versus skewness tends to collapse to a parabolic line. This in turn allows us to draw analogies with neutral fluid turbulence where such a collapse of the kurtosis-skewness profile has been observed.     

耦合高维排序权和对偶线性规划的综合指数算法

区域可持续与高质量发展需定期监测并科学评估。综合指数评价是应用最为广泛、信息传输效率最高的评估方法。该方法将表征区域发展质量不同侧面的系列指标加权聚合为单个指数,其核心是采用或客观或主观的方式确权。客观确权基于指标的数值统计特性实现,故权重值随指标值而改变,实非“客观”;主观确权能反映决策者智慧,但指标过多时难以实现。学界新提出的基于耦合排序权和熵权法的综合指标法允许决策者确权时仅给出权重排序,但仅支持低维情况（限制为3个指标）。本文在其基础上,借助对偶线性规划推导,使其适用性不再受限于指标数（即实现高维排序权）。同时,对指标的聚合方式进行修改,扩大了算法的适用范围;对熵权法的使用进行修正,增强了算法结果的可解译性。基于推导结果,本文进一步发展出单排序、复排序、全排序3种不同模式下的综合指数计算方法,以满足决策者主观性强、弱、无等不同情况。最后,将算法用于全球可持续发展格局的时空评价分析。本文新发展的算法同时适用于高低不同维度的指数聚合、可兼顾决策者不同层次的主观参与度,具有较强的普适性。     

BP神经网络在高程异常反演预测中的应用分析

利用C#语言编制了BP神经网络反演预测程序,基于具有代表性地区的高程异常数据,对BP神经网络在高程异常反演预测中的应用进行了分析。结果表明,本程序交互界面良好,具有很好的通用性;同时,在高程异常反演预测中取得良好的效果,说明神经网络在差异较大的数据反演预测方面仍具有较强的优势。     

Upper bound limit analysis using linear finite elements and non‐linear programming

A new method for computing rigorous upper bounds on the limit loads for one‐, two‐ and three‐dimensional continua is described. The formulation is based on linear finite elements, permits kinematically admissible velocity discontinuities at all interelement boundaries, and furnishes a kinematically admissible velocity field by solving a non‐linear programming problem. In the latter, the objective function corresponds to the dissipated power (which is minimized) and the unknowns are subject to linear equality constraints as well as linear and non‐linear inequality constraints. Provided the yield surface is convex, the optimization problem generated by the upper bound method is also convex and can be solved efficiently by applying a two‐stage, quasi‐Newton scheme to the corresponding Kuhn–Tucker optimality conditions. A key advantage of this strategy is that its iteration count is largely independent of the mesh size. Since the formulation permits non‐linear constraints on the unknowns, no linearization of the yield surface is necessary and the modelling of three‐dimensional geometries presents no special difficulties. The utility of the proposed upper bound method is illustrated by applying it to a number of two‐ and three‐dimensional boundary value problems. For a variety of two‐dimensional cases, the new scheme is up to two orders of magnitude faster than an equivalent linear programming scheme which uses yield surface linearization. Copyright © 2001 John Wiley & Sons, Ltd.     

Study on Variation of Fitting Goodness of Relation Between Earthquake Frequency and Magnitude before Moderately Strong Earthquakes (Ms≥5.0)

In this paper,characteristics of spatial and temporal variation of linear fitting goodness before some moderately strong earthquakes(Ms≥5.0)in the eastern part of China(east of longitude 180)are studied according to the famous Gutenberg-Richter's relation expressed as lgN=a-bM,by using the moderate and small events that occurred in and around the source area.The results show that the linear goodness of fitting varies abnormally prior to these moderately strong earthquakes.In the early stage of the earthquake preparatory process,distribution of the energy released through small events in and around the source area is isostatic and the fitting goodness approximates 1,while the distribution of the energy turns to be isostatic before moderately strong earthquakes,leading to the obvious decrease of the linear goodness of fitting.This phenomenon could be a medium term anomaly and a medium term criterion for moderately strong earthquake prediction.     

用线性规划法求解瞬变电磁场反射系数

讨论了在水平层状介质中的反射系数的物理意义 ,推出时间域含有以反射系数序列为未知项的欠定方程组 ,提出用线性规划法求解瞬变电磁场反射系数序列 ,并给出求解思路和程序框图。对两个理论模型进行了处理 ,计算出了其反射系数。算例分析结果表明 ,算法可靠 ,程序可行。这一方法可用于瞬变电磁成像数值计算中。     

Wave diffraction and near-trapping by a multi-column gravity-based structure

This paper is concerned with the diffraction of water waves by offshore structures, with the ultimate aim of proposing tools for guiding airgap design. The diffraction of monochromatic waves by an array of four bottom mounted cylinders and a gravity-based structure is studied in detail using linear and second order theory. The phenomenon of near-trapping is investigated, allowing guidelines for airgap design to be established. When contemplating airgap design, however, it is crucially important that consideration is given to the largest waves in a sea state. Therefore, in this study a design wave, called NewWave, is proposed as a realistic model for large ocean waves and is used as the incident wave field in the wave-structure diffraction analysis.