Online Survey of Heterogeneous Users and Their Usage of the Interactive Mapping Platform WorldMap

This article reports on the results of an online survey with 290 heterogeneous users of the interactive mapping platform WorldMap and provides insights into problems faced by such users. Heterogeneous users are users with a variety of GIS skills, educational background, gender, and age categories. We investigate how they interact with online maps and analyse their experience. WorldMap represents as a case study of an online mapping platform which aims to serve researchers and users across disciplines in viewing and creating online interactive maps. We concentrate on operations that are perceived as difficult and very difficult by the majority of users as well as operations that are rarely used. Our aim is to contribute to the discussions on how to improve the design of online GIS-based mapping platforms. We conclude the paper with reflections on the results of our study and ideas for further research.     

GIM和不同约束条件相结合的BDS差分码偏差估计

现阶段BDS卫星和地面跟踪站数量较少,用BDS单系统获取的DCB精度有限,针对此问题,本文基于CODE GIM,采用两种不同的"零均值"基准约束方案(分别称为约束1和约束2),选取2015年(DOY002-090)MGEX的BDS数据,求解BDS的DCB,并对其进行精度评估。结果表明,两种约束方案下,卫星DCB差值整体趋势一致,DCBC2I-C7I、DCBC2I-C6I的系统性偏差分别约为-3.3ns和1.2ns,接收机DCB的系统性偏差与卫星DCB大小相同,符号相反。相对于约束1,施加约束2后,IGSO和MEO卫星DCB估值更加稳定(DCBC2I-C7ISTD最大改善21%,DCBC2I-C6ISTD最大改善13%),IGSO和MEO卫星的稳定性(分别在0.1ns和0.2ns左右)优于GEO卫星(0.150.32ns)。约束2的DCB估值效果不仅与CAS/DLR产品有较好的一致性(Bias:-0.40.2ns),而且顾及了BDS卫星DCB间的稳定性差异。两种约束方案下,BDS接收机DCB的STD无明显变化,说明约束的选择对BDS接收机DCB的稳定性无明显影响。BDS接收机DCB稳定性整体上优于1ns,中高纬度区域较好(STD 0.4ns左右),低纬度区域稍差(STD 0.81ns)。     

利用DOM更新1：10000地形图平面精度的探讨

针对基础地理信息数据更新的现状,综合分析了利用数字正射影像图进行矢量化数据采集以更新DLG的误差源、未变要素在DLG与DOM中的偏差,并进行了更新成果精度分析,实例表明,分析结果合理、可行。     

宋代测绘史考＊

概述宋代测绘管理及机构职官设置,各类测量及地图状况,并介绍当时若干具有世界先进水平的测绘成果。     

Magnetic fabric and emplacement of the post-collisional Pomovaara Granite Complex in northern Fennoscandia

The Proterozoic Pomovaara Granite Complex in northern Finland comprises three separate highly magnetic granite stocks. They are discordant, apparently unfoliated and according to isotope data, a significant Archaean component characterizes the source of these granites. The three stocks are aligned in an array parallel to major trans-crustal faults as interpreted from both aeromagnetic and gravity data. Their younger age of 1.8 Ga, compared to the main tectonic events at 1.9 Ga in northern Fennoscandia, indicates their post-collisional nature with respect to these events. The anisotropy of magnetic susceptibility (AMS) was studied together with magnetic, gravity and geological data in order to assess the emplacement mechanisms of the Pomovaara Granite Complex, and the possible tectonic control of fault systems on the ascent and emplacement of granitic magma. The orientation of magnetic fabrics within the granite stocks indicates that the direction of the original magma upwelling was from the SW, parallel to the major fault zones that controlled, at the crustal scale, the ascent of granite magmas. The predominant NW–SE orientations of the minimum magnetic axes of the magnetic ellipsoid and the elongate shapes of the stocks indicate compression normal to the deep fault trend during the crystallization of the granite magma.     

Overview of a theory and method for prediction of mineral resources in China

A set of theories and methods has long been needed to enhance geological prospecting. Since 1982, we have been predicting mineral-resource potential based on geological research in China, using a comprehensive information theory and method (CIM), developed to identify mineral-resource domains. The key features of CIM are: (1) to establih comprehensive prospecting models on various scales on the basis of a metallogenic model; the prospecting models are statistical in nature and incorporate a range of ore indicators, (2) to compile detailed metallogenic maps that reflect metallogenic regularities, ore-controlling factors, prospecting indicators, and the positions of favorable target areas, and (3) to establish statistical prediction models of undiscovered mineral resources. This CIM method has been effective and has provided significant economic benefits in the past few years in China.     

Bathymetric Map of the Gorda Plate: Structural and Geomorphological Processes Inferred from Multibeam Surveys

Full-coverage multibeam bathymetric maps of the southern section of the Juan de Fuca Plate, also known as the Gorda Plate, are presented. The bathymetric maps represent the compilation of multibeam surveys conducted by the National Oceanic and Atmospheric Administration during the last 20 yrs, and illustrate the complex tectonic, volcanic, and geomorphologic features as well as the intense deformation occurring within this region. The bathymetric data have revealed several major, previously unmapped midplate faults. A series of gently curving faults are apparent in the Gorda Plate, with numerous faults offsetting the Gorda Plate seafloor. The multibeam surveys have also provided a detailed view of the intense deformation occurring within the Gorda Plate. A preliminary deformation model estimated from basement structure is discussed, where the southern part of the plate (south of ∼42°30′ N) seems to be deforming through a series of left-lateral strike-slip faults, while the northern section appears to be moving passively with the rest of the Juan de Fuca Plate. The bathymetry also demonstrates the Mendocino and Eel Canyons are prominent morphologic features in the northern California margin. These canyons are active depositional features with a large sediment fan present at the mouths of both the Mendocino and Eel canyons. The depositional lobes of these fan(s) are evident in the bathymetry, as are the turbidite channels that have deposited sediment along the fans over time. The Trinidad Canyon is readily evident in the margin morphology as well, with a large (∼10 km) plunge pool formed at the mouth of the canyon as it enters the Gorda Plate sediments. This revised version was published online in November 2006 with corrections to the Cover Date.     

Gulf of Mexico sediment sources and sediment transport trends from magnetic susceptibility measurements of surface samples

The magnetic properties from 200 trigger core-top and Van Veen grab sediment samples recovered from throughout the Gulf of Mexico have been analyzed and used to characterize sediment source and flow pattern distributions. Magnetic parameters included are anhysteretic remanent magnetism (ARM) and magnetic susceptibility (MS) measurements. Results from these measurements are compared to previously determined calcium carbonate percentages, and clay and hematite influx trajectories into the Gulf of Mexico for the same samples reported by Balsam and Beeson [Balsam, W.L. and Beeson, J.P., 2003. Sea-floor sediment distribution in the Gulf of Mexico, Deep-Sea Res. I, 50, 1421–1444.]. The ARM results give an estimate of magnetic grain size distributions, and by analogy, grain size distributions in general, whereas MS patterns show high detrital sediment accumulation zones within the Gulf. The dominant influx of modern high susceptibility sediment into the Gulf of Mexico appears to originate from the Red River, flow into Atchafalaya River Basin and out into the Gulf from Atchafalaya Bay, with significant additional contributions from the Mississippi River through the Southwest Pass of the Mississippi River Delta. This material then moves across the continental shelf and down through the Mississippi Canyon into the deep Gulf where it is redistributed at depths > 3600 m. The eastern shelf margins in the Gulf, offshore from Alabama and Florida, are accumulating calcite- or quartz-rich medium to fine-grained sediment that has a very low or diamagnetic MS signature. From the Louisiana to Texas Gulf coast margins, MS is moderate to high, suggesting a river influx of magnetic constituents from the volcanic fields in New Mexico, and from igneous and metamorphic sources in the Mississippi Basin. Offshore from western Mexico, the MS is high to moderate, but the Yucatan Shelf margin is characterized by low to diamagnetic MS values due to sediment dominated by calcite sands and oozes, a trend that continues to the east onto the West Florida Shelf. Additional measurements of samples collected in association with sites characterized by hydrocarbon seepage exhibit anomalously low MS values. The samples from the lower shelf and slope areas are typified by iron reduction by bacterial organisms in these samples. These results produce anomalous localized lows in the MS trends observed.     

Long baroclinic Rossby waves with periods of about 500d near 20°N in the northwest Pacific Ocean

1IntroductionThe oceanic Rossby waves play an importantrole in the large-scale oceanic circulations.In the o-ceans baroclinic Rossby waves have surface manifes-tations of just a fewcentimeters,and wavelengths atmid-latitudes of hundreds to thousands of ki…     

Horizontal and vertical variability of soil properties in a trace element contaminated area

The spatial distribution of some soil chemical properties and trace element contents of a plot affected by the Aznalcóllar mine spill were investigated using statistical and geostatistical methods to assess the extent of soil contamination. Total and EDTA-extractable soil trace element concentrations and total S content showed great variability and high coefficients of variation in the three examined depths. Soil in the plot was found to be significantly contaminated by As, Cd, Cu, Pb and Zn within a wide range of pH. Total trace element concentrations at all depths (0–60 cm) were much higher than background values of non-affected soil, indicating that despite the clean-up operations, the concentration of trace elements in the experimental plot was still high. The spatial distribution of the different variables was estimated by kriging to design contour maps. These maps allowed the identification of specific zones with high metal concentrations and low pH values corresponding to spots of residual sludge. Moreover, kriged maps showed distinct spatial distribution and hence different behaviour for the elements considered. This information may be applied to optimise remediation strategies in highly and moderately contaminated areas.