Multiscale anisotropic diffusion for ringing artifact suppression in geophysical deconvolution data

Ringing artifact degradations always appear in the deconvolution of geophysical data. To address this problem, we propose a postprocessing approach to suppress ringing artifacts that uses a novel anisotropic diffusion based on a stationary wavelet transform (SWT) algorithm. In this paper, we discuss the ringing artifact suppression problem and analyze the characteristics of the deconvolution ringing artifact. The deconvolution data containing ringing artifacts are decomposed into different SWT subbands for analysis, and a new multiscale adaptive anisotropic filter is developed to suppress these degradations. Finally, we demonstrate the performance of the proposed method and describe the experiments in detail.     

Application of Fractal Models to Distinguish between Different Mineral Phases

Fractal modeling is demonstrated to be an effective and rapid tool to distinguish between mineral phases in rock samples. It supplements work that previously could be performed only by observing the interpenetrational or metasomatic phenomena between different minerals with the aid of mineralographic microscope. The Gejiu tin district in southwestern China was chosen as a study area for the recognition and characterization of the spatial distribution of two phases (Types I and II) of cassiterite. Vector patterns used for this study were extracted from digital photomicrographs and analyzed with the aid of MapGIS. Perimeter–area fractal dimension, cumulative number–area exponent, and shape index were determined in order to quantify geometrical irregularities and spatial cassiterite phase distribution characteristics. The results show that fractal dimensions based on area and perimeter are larger for crystals of Type I than for those of Type II. The mean shape index (SI) increases from 0.54 (Type I) to 0.64 (Type II), indicating an increase in regularity. The number–area exponent also increases from 0.88 to 1.15, indicating the smaller crystals of Type II. The cumulative number–shape index log–log plot shows two separate straight-line segments. One of these probably represents a background shape realized during the original process of natural crystallization, whereas the other likely represents anomalous shapes because of weathering or other superimposed processes. Two parallel lines can be constructed on the perimeter–area log–log plots. The upper line, with a larger intercept, represents crystals with lower SI. The lower line represents crystals with higher SI, indicating that the intercept provides a measure of the irregularity of grains. By combining the perimeter–area model with cumulative number–area plot and shape index, the two phases of cassiterite can be distinguished and characterized. One phase has fewer crystals of large size, and the other has smaller crystals. This difference can be explained by assuming that under higher-temperature conditions, the large cassiterite crystals formed earlier than the smaller crystals. Consequently, the large cassiterites underwent longer, high-intensive weathering than the small crystals so that their shapes became more irregular. The younger, more abundant small cassiterites retained their original regular shapes.     

Simulation and control of the linked systems of water quantity–water quality–socio-economics in the Huaihe River basin

Abstract

This work makes explicit an algebraic expression giving the matrix of transient influence coefficients associated with a one-dimensional semi-confined aquifer model. The domain studied is divided into a series of connected and completely mixed compartments over which the governing equation is discretized. The discrete equations obtained are solved for the compartmental hydraulic head and used to derive the algebraic expression in question. The basic properties of the so-called algebraic influence coefficients are investigated. In particular, their consistency with the exact Green function is highlighted. Finally, the newly derived influence coefficients are applied to a simplified aquifer system in order to formulate and solve the problem of identifying illegal groundwater pumping.     

基于直方变差图的土地覆盖数据集多尺度精度评价

针对目前精度评价尺度单一的问题,提出基于直方变差图的多尺度精度评价方法,分别在像元尺度和亚像元尺度进行土地覆盖数据集精度评价。在像元尺度利用驻点作为采样工具直接评价数据集精度;亚像元尺度上,则利用非严格定义的驻点和驻点直方变差图对不同面积和空间结构的优势类进行精度评价。并以浙江北部典型区域为实验区,Landsat TM/ETM+为参考数据,对UMD、IGBP DISCover、MOD12Q1-2001、GLC2000、GlobCover2009等5种大尺度土地覆盖数据集进行多尺度精度评价实验。结果表明,多尺度精度评价方法能够全面地评价土地覆盖数据集的精度,提供更加丰富的多尺度精度信息。像元尺度精度评价可在一定程度上消除由于参考数据与数据集间的空间匹配造成的误差,评价结果更加客观;亚像元尺度精度评价能有效反映亚像元尺度优势地物面积及空间结构与精度的关系。     

压力分散型预应力锚索张拉试验及应力损失探讨

以某边坡工程压力分散型预预应力锚索的张拉试验为基础,介绍了压力分散型预应力锚索工作机理及张拉试验过程,并对应力损失、预应力筋的伸长量及桩身变形进行分析和初步探讨。     

基于土地利用分类模型和重力模型耦合的人口分布模拟——以武汉市人口数据为例

将土地分类模型和重力模型耦合形成新模型,并以武汉市人口数据为例,用耦合后的新模型模生成武汉市人口网格数据.经数据验证表明,耦合后的新模型在计算精度方面有了较大的提高.     

Coastal Wetlands of China: Changes from the 1970s to 2007 Based on a New Wetland Classification System

A new classification of coastal wetlands along the coast of China has been generated that is compatible with the Ramsar Convention of 1971. The coastal wetlands have been divided into two broad categories with overall nine subcategories. On this basis, a series of coastal wetland maps, together covering the coast of mainland China, have been produced based on topographic maps acquired in the 1970s and satellite images acquired in 2007. These document substantial wetland losses over this period. In the 1970s, the total coastal wetland area in China was 5.76?×?10⁴?km², whereas in 2007, it was 5.36?×?10⁴?km², indicating a loss of 7 %. Over this approximately 40-year period, the area of natural coastal wetlands decreased from 5.74?×?10⁴ to 5.09?×?10⁴?km², while that of artificial coastal wetlands increased from 240 to 2,740 km². Due to shoreline and sea-level changes, newly formed coastal wetlands amounted to 2,460 km², while coastal wetland loss amounted to 6,310 km² in the period from the 1970s to 2007. When excluding shallow coastal waters (depths between 0 and ?5 m), nearly 16 % of Chinese coastal wetlands have been lost between the 1970s and 2007.     

依兰盆地达连河组油页岩成矿模式及类型

提要：达连河油页岩含矿区位于黑龙江省依兰地区,该区是一个半地堑式断陷盆地。古近系达连河组为一个完整的三级层序,油页岩形成于水进体系域和高水位体系域发育时期。本文认为达连河组油页岩存在两种成矿模式,即湖泊-沼泽相油页岩成矿模式、浅湖相-半深湖相油页岩成矿模式;不同成矿类型油页岩分布于层序的不同体系域,古地貌型、沉积密集段型油页岩成矿常分布于水进体系域,沉积密集段型、气候型油页岩成矿位于高水位体系域。     

北山泥盆纪碰撞造山火山－磨拉石地质构造及地球化学特征

本区早泥盆世旱山微大陆与塔里木板块的北山地体间发生对接，原洋区变为残留滨浅海区。中泥盆世该区形成中央断块山，相应南带的断陷山间洼地内形成陆相磨拉石堆积，北带与南蒙古洋毗邻，形成陆缘滨浅海火山－磨拉石沉积。经计算，中带造山隆起侵蚀速率为０．１５４ｍｍ／ａ。晚泥盆世火山岩显示弱碱性和深熔岩浆喷溢特点，表明陆壳演化尚未达到完全稳定的阶段。