A new GRASS GIS toolkit for Hortonian analysis of drainage networks

The aim of this paper is to present a new GRASS GIS toolset designed for Hortonian analysis of drainage networks. The r.stream toolset uses a multiple flow direction algorithm for stream network extraction as well as for calculating other hydrogeomorphological features in the catchment’s area. As all GRASS GIS toolsets, r.stream consists of several separate modules that can extract stream networks from a spectrum of accumulation maps, order the extracted network using several ordering methods, do advanced modeling of basin’s boundary, perform Hortonian statistics, calculate additional parameters such as flow path distance to watershed elements, partition ordered and unordered networks into near-straight-line sectors, and calculate sector directions. The package is free and open-source software, available for GRASS version 6.4 and later.     

基于极化雷达影像的海岛礁提取

提出了一种利用RADARSAT-2全极化SAR影像和极化特征参数提取精确的海岛礁范围的技术方法。极化特征熵参数描述了目标散射的随机性,与海水相比海岛礁处于较高的去极化状态,因此海岛礁的熵值明显大于海水的熵值。首先本文利用EM(Expectation Maximization,最大数学期望)算法自动计算的提取海岛礁最佳阈值对熵参数文件进行阈值分割,得到海岛礁的初始分割结果。由于受到船只和海水表面波浪的影响,海水部分也会存在与海岛礁近似的熵值。因此初步阈值分割得到的海岛礁结果会有部分海水和船只等,利用PSNR(Peak value signal-to-noise ratio,峰值信噪比)提取海水大致范围并剔除海水范围内初始分割结果中的噪声部分。最后根据TM影像提取的海岛礁范围进行精度评价,实验结果表明该技术方法能够从极化SAR影像上准确提取海岛礁范围。     

2000—2021年中国城市山地景观保护规划与立法中的界线划定模式

随着全球人口聚集增长,快速城市化地区的山地景观因市民生产和生活而变化,因而各国纷纷通过保护规划与立法保护景观特征及生态。现有研究已从4个切入角度揭示相关实践的广度和深度,但尚未就保护界线划定问题进行系统探讨。以当代中国内地城市为研究对象,基于内容分析法与空间制图法比较来自60个城市的76份山地景观保护规划或法规文本,分别从山地本体保护界线、山地内部管控强度、山地周边管控界线3个方面识别相关保护界线划定模式。研究发现:1)上述城市主要分布在东部低海拔地区,但其山地景观保护界线划定模式并不存在明显的地区性聚集规律;2)相关城市主要基于坡度、绝对高程、相对高程、山脊等地貌特征因子划定山地景观保护界线,同时根据行政区划、管控分区、特定用地类型与区位、视野及定性条件等经济社会因素进行修正。对中国部分城市山地景观保护界线划定问题进行系统总结,可为中国乃至世界其他城市的相关问题提供参考。     

影像引导放疗中交互式肿瘤靶区勾画方法

在图像引导放射治疗中肿瘤(靶区)和危险器官的勾画是制定放疗计划的重要环节。在临床应用中靶区勾 画通常是由医生手动完成，虽然这种方法普遍被认为可靠，但是耗时较多且精度受医生主观影响较大。由于临床 上人体组织结构的多样性和靶区目标影像的复杂性，自动勾画方法在精度和可靠性上并不能较好的满足实际临床 需求。文章提出了一种交互式轮廓勾画的方法，结合自动的活动轮廓模型和手动交互的多尺度曲线编辑方法实现 靶区的快速精确勾画。通过初始化轮廓调整使活动轮廓模型快速可靠地达到目标轮廓，然后使用多尺度数字曲线 编辑可实现对复杂形状轮廓的快速修正。医学临床实验结果验证了方法的有效性。     

宁夏中卫市饮用水水源地保护区划分

为加强水源地及其周边环境保护与污染防治,保障宁夏中卫市饮用水水质安全,根据中卫市地下水系统的水文地质条件和勘探数据,结合水源地水质和补给特点,按照污染物水平迁移时间的不同,划分了水源地一级、二级和准保护区．该划分成果可为中卫市地下水系统的环境管理和水质防护工作提供决策依据．     

YQ地区奥陶系碳酸盐岩岩溶储层地震属性预测

YQ地区奥陶系地层碳酸盐岩储层发育,储集类型以岩溶孔洞、裂缝型为主。由于储层非均质性极强,横向变化快,加之溶洞受填隙物及填充程度的影响,使得储层预测的难度很大。从奥陶系碳酸盐岩储层的地球物理响应特征出发,形成1套以地震属性优选、多属性融合、三维像素属性雕刻等为主的地震预测技术流程。利用这些技术手段对奥陶系岩溶孔洞类储层、风化壳顶面储层进行了预测,对这2类储层在平面和空间上的分布特征进行了定性描述和分析,其结果与实钻情况吻合,取得了较好的应用效果。     

Integrale Quantifizierung von Schadstoffmassenflüssen im Grundwasser – Konditionierung der numerischen Inversion der Konzentrationsganglinien von Immissionspumpversuchen

A series of integral pumping tests (IPTs) were conducted at a former gasworks site to quantify the contaminant mass flux and average concentration in groundwater along three control planes. The resulting concentration-time series were analysed numerically with the help of the inversion code CSTREAM and a flow and transport model representing the highly heterogeneous aquifer. Since the control planes cover the entire downstream width of the potentially contaminated area, they allow conclusions to be drawn about the current location and spread of the contaminant plume. Previous evaluations of integral pumping tests could calculate three scenarios concerning the spread of the plume around the IPT well: (i) the plume is located to the right of the well, (ii) to the left, or (iii) is distributed symmetrically around it. To create a more realistic picture of the plume position, a series of direct-push monitoring wells were installed along one control plane. The concentrations found in these wells were included in the numerical analysis to condition the inversion results, and resulted in a more pronounced plume centre and fringe, which supports the development of optimised remediation strategies.     

Application of HEC-HMS for flood forecasting in Misai and Wan'an catchments in China

The hydrologic model HEC-HMS(Hydrologic Engineering Center,Hydrologic Modeling System),used in combination with the Geospatial Hydrologic Modeling Extension,HEC-GeoHMS,is not a site-specific hydrologic model.Although China has seen the applications of many hydrologic and hydraulic models,HEC-HMS is seldom applied in China,and where it is applied,it is not applied holistically.This paper presents a holistic application of HEC-HMS.Its applicability,capability and suitability for flood forecasting in catchments were examined.The DEMs(digital elevation models)of the study areas were processed using HEC-GeoHMS,an ArcView GIS extension for catchment delineation,terrain pre-processing,and basin processing.The model was calibrated and verified using historical observed data.The determination coefficients and coefficients of agreement for all the flood events were above 0.9,and the relative errors in peak discharges were all within the acceptable range.     

采用高分辨率岩层穿透雷达圈定金伯利岩体

本文主要讲述用高分辨率岩层穿透雷达（GPR）圈定堪萨斯州赖利县的兰道夫1#和2#金伯利岩体的试验研究。在1#、2#试验区分别布置了6条平行探测线和5条放射状探测线。研究结果表明GPR可以用来圈定近地表金伯利岩体或由于岩浆浸入围岩而形成的其它类型的矿床。     

A new automated delineation method for SPECT lung scans using adaptive dual‐exponential thresholding

An accurate method for delineating lung contours in single photon emission computed tomography (SPECT) is critical to respiratory studies such as pulmonary embolism (PE) and respiratory aerosol deposition. Current delineation methods are not adaptive in nature and may require a priori information on lung volumes. We have developed a dual‐exponential thresholding method that solely requires SPECT scans, and is fast, accurate, and adaptive in nature. A dataset consisted of 90 patients was studied retrospectively. While most were suspected of PE, other pulmonary disorders were also present. SPECT ventilation scans were obtained after inhalation of ～40 MBq of 99mTc‐Technegas. Examination of the corresponding natural logarithmically transformed histograms revealed dual exponential functions like pattern. Adaptive thresholds were found as the intercept between the two exponential functions. 350 Monte Carlo simulations representative of normally‐ventilated scans with varying counts were used to quantitatively measure and evaluate the method. Our method correctly delineated lung volumes to above 97% agreement for 310 of the 350 Monte Carlo simulations with maximum count values greater than or equal to 31. The 40 low‐count simulations were included purely as extreme cases. For real patient scenario, an experienced physician was called upon to visually delineate a sample of 50 actual patient scans, and these delineated lung volumes were used as gold standard and compared with those delineated using our method. Our results had an average of 96% agreement. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 22–27, 2007