基于等高线构建TIN模型的平三角形修正算法

设计了一种平三角形修正算法来修正TIN模型中可能出现的平三角形区域。该算法通过对由平三角形组成的区域进行分类,并针对不同的平区域采用交换边、增加点甚至不处理的修正方法,同时对由于等高线数据错误产生的一些特殊情况进行了分析处理。实验结果表明,该算法能够去除约束型狄洛尼三角网中所有应修正的平三角形,并生成对地形描述更为精确的三角网。     

冻土隧道冻胀力室内模型试验研究

详细地介绍了曲墙式、直墙式和圆形断面隧道衬砌在约束条件、隔热保温层及含水状况等因素变化情况下的相似材料冻胀力室内模型试验,通过分析试验得出不同衬砌断面在各种因素影响下衬砌和围岩间冻胀压力的量值和分布特征,以及由冻胀压力引起的结构内力分布特征。研究表明,直墙式断面受冰胀力最大,曲墙式次之,圆形面最小;曲墙式、直墙式断面冻胀力均呈分布荷载形态,前者拱脚及仰拱脚处冻胀力最大,后者边墙、底板处冻胀力最大。     

被动微波反演裸露区土壤水分综述

被动微波具有全天候、穿透性以及不受云的影响等特征,使其在反演土壤水分时具有很大的优势。通过研究发现,被动微波遥感是反演土壤水分的各种技术中最有效的方法之一。概括了主要的被动微波传感器并从被动微波遥感的原理出发,针对被动微波遥感裸露区地表随机粗糙面的模型以及土壤水分反演算法作了简要介绍。     

基于地图代数的数字地表流线模拟研究

降雨在地表上随地形流动自然形成沟谷线、汇流区、分水岭等流域形态,研究地表流水线的数字模拟对数字流域水文分析具有重要意义.提出数字地表流线模型的概念,只考虑地形因素,利用等高线图建立一个能获得区域内每滴雨水沿地表流动的轨迹模型.并运用地图代数的距离变换对等高线及所在空间进行全方位的距离度量,研究了数字地表流线模型的建立方法.实验表明,该模型利用距离变换信息而不是高程计算流向,可避免DEM高程误差对流向、流线的影响,且不需要在DEM上进行复杂的洼地、平地的识别与处理.该模型对原始数据要求不高,能有效应用于沟谷线的自动提取、汇流区自动分割和分水线网络的自动提取.     

Peierls dislocation modelling in perovskite (CaTiO<Subscript>3</Subscript>): comparison with tausonite (SrTiO<Subscript>3</Subscript>) and MgSiO<Subscript>3</Subscript> perovskite

We present here a numerical modelling study of dislocations in perovskite CaTiO₃. The dislocation core structures and properties are calculated through the Peierls–Nabarro model using the generalized stacking fault (GSF) results as a starting model. The GSF are determined from first-principles calculations using the VASP code. The dislocation properties such as collinear, planar core spreading and Peierls stresses are determined for the following slip systems: [100](010), [100](001), [010](100), [010](001), [001](100), [001](010), and All dislocations exhibit lattice friction, but glide appears to be easier for [100](010) and [010](100). [001](010) and [001](100) exhibit collinear dissociation. Comparing Peierls stresses among tausonite (SrTiO₃), perovskite (CaTiO₃) and MgSiO₃ perovskite demonstrates the strong influence of orthorhombic distortions on lattice friction. However, and despite some quantitative differences, CaTiO₃ appears to be a satisfactory analogue material for MgSiO₃ perovskite as far as dislocation glide is concerned.     

Ecological controls on biogeochemical lfuxes in the western Antarctic Peninsula studied with an inverse foodweb model

Sea ice in the western Antarctic Peninsula (WAP) region is both highly variable and rapidly changing. In the Palmer Station region, the ice season duration has decreased by 92 d since 1978. The sea-ice...     

Application of constrained sparse spike inversion in reservoir predication:a case study of Oriente Basin in South America

In the conditions of low Signal-to-Noise Ratio(SNR) of seismic data and a small quality of log information,the consequences of seismic interpretation through the impedance inversion of seismic data could be more precise. Constrained sparse spike inversion(CSSI) has advantage in oil and gas reservoir predication because it does not rely on the original model. By analyzing the specific algorithm of CSSI,the accuracy of inversion is controlled. Oriente Basin in South America has the low amplitude in geological...     

Eco-environmental spatial characteristics of Fildes Peninsula based on TuPu models

This study applies a TuPu analysis to investigate ecological and environmental aspects of an Antarctic ice-free area, using Fildes Peninsula as an example. The TuPu unit was determined using a vector-grid mixed data model. Information from the eco-environment elements was effectively extracted, and was generalized into different classes by means of data mining technol- ogy. A series of single-factor thematic information TuPu models, such as topography, soil, animal and vegetation, and human activities for Fildes Peninsula were built in this study. The topography TuPu model contained information on elevation and slope. The soil TuPu model involved soil development stages and soil thickness information. The animal and vegetation TuPu model contained the distribution of animals, plant types, lichen cover and lichen height. The human activities TuPu model included popu- lation density and human disturbance index information. The landscape comprehensive information TuPu model of Fildes Penin- sula also was established, and contains twenty-nine landscape units and twelve types of combined environments. The study quan- titatively revealed the spatial morphology and correlation of the regional eco-environment based on the analysis of these TuPu models. From these models, we can draw the conclusion that there is a regular differentiation of eco-environment from the coastal bands to the central hills in Fildes Peninsula, and that the eco-environment condition of the eastern coasts is different from that of the western coasts. The eco-environmental spatial variation also differs greatly from north to south. Based on analysis of spatial correlation, the vegetation in Fildes Peninsula has the greatest correlation with human activity, and has a certain correlation with topography and soil. This research may provide a new technical approach and scientific basis for the in-depth study of Antarctic eco-environments.     

Study on attribute characterization for reservoir dynamic monitoring by seismic

Study on characterizing reservoir parameters dynamic variations by time-lapse seismic attributes is the theoretical basis for effectively distinguishing reservoir parameters variations and conducting time-lapse seismic interpretation,and it is also a key step for time-lapse seismic application in real oil fields. Based on the rock physical model of unconsolidated sandstone,the different effects of oil saturation and effective pressure variations on seismic P-wave and S-wave velocities are calculated and analyzed. Using numerical simulation on decoupled wave equations,the responses of seismic amplitude with different offsets to reservoir oil saturation variations are analyzed,pre-stack time-lapse seismic attributes differences for oil saturation and effective pressure variations of P-P wave and P-S converted wave are calculated,and time-lapse seismic AVO (Amplitude Versus Offset) response rules of P-P wave and P-S converted wave to effective pressure and oil saturation variations are compared. The theoretical modeling study shows that it is feasible to distinguish different reservoir parameters dynamic variations by pre-stack time-lapse seismic information,including pre-stack time-lapse seismic attributes and AVO information,which has great potential in improving time-lapse seismic interpreta-tion precision. It also shows that the time-lapse seismic response mechanism study on objective oil fields is especially important in establishing effective time-lapse seismic data process and interpreta-tion scheme.