共查询到20条相似文献，搜索用时 109 毫秒
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珠江口内伶仃洋沿岸土地利用动态分析 总被引：4，自引：0，他引：4
珠江口内伶仃洋沿岸地区近年来大规模填海造田,使虎门、蕉门、洪奇沥和横门四大口门日益缩窄,水泄不畅,对环境造成很大影响。根据2003年在珠江口内伶仃洋水域获得的海洋地质环境与地质灾害综合调查资料,结合调查区5个时相的遥感影像资料,运用遥感影像机助解译方法、GIS空间分析方法、GPS定位方法以及相应的数理统计方法,综合分析了内伶仃洋沿岸老城区土地利用动态变化的特点及若干驱动因素,认为内伶仃洋沿岸的土地利用已从早期的填海造田、围海养殖,转向用于发展工业及高新技术的厂房和港口建设的土地开发。 相似文献
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GIS在港口规划建设管理中的应用模型 总被引：3，自引：0，他引：3
GIS（GEOGRAPHIC INFORMATION SYSTEM）又名空间地理信息系统,与空间位置有关的领域都是GIS的重要应用领域。GIS应用于港口规划建设与土地管理,通过GIS的开发应用,逐步实现相应管理工作的自动化和图形管理,规范业务工作流程,为电子口岸的建设提供物理空问的数据平台。基于对于港口规划建设管理需求的理解,结合GIS在国内外港口应用的现状和发展趋势,探讨了港口规划建设管理系统的框架模型和不同层次的开发建议。同时对于作为规划建设管理的基础平台的港口GIS信息数据平台及其结构框架也进行了讨论。 相似文献
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福建琅岐岛土地演化与发展趋势 总被引：1，自引：0，他引：1
本文根据野外调查,并参考前人研究成果,讨论了闽江口琅岐岛的土地分异、土地演化与地质构造和构造运动、水文泥沙运动以及历史因素的关系,分析了今后该岛土地发展的趋势。 相似文献
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西沙群岛和南沙群岛自古以来就是中国领土不可分割的组成部分。中国通过“发现”和“有效占有”取得了对南海诸岛的领土主权,这在历史和法理上,都具有无可辩驳的充分根据。一、国际法上的发现和有效占有在国际法上,发现和有效占有是先占制度中两个相互关联的阶段。先占是国际法上领土取得和变更的一种古老方式,其含义是一个国家通过占有取得无主土地的主权,而无主土地是指当时不在任何其他国家主权管辖之下的土地。在古代和中世纪,国家领土被视为君主 相似文献
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A marine magnetic survey was conducted over the Dellwood Knolls area of the northeast Pacific in September 1977 using a proton precession magnetometer and Loran-C positioning. Geomagnetic field reference stations were located at Victoria and Port Hardy. In addition, a recently developed ocean bottom magnetometer was deployed in the survey area. The cross-over error, a measure of survey accuracy, and the factors contributing to it are discussed. In high magnetic gradient regions, the part of the error related to the uncertainty in ship position implies that the repeatability of the Loran-C navigation system is of the order of 30 metres. Part of the error is also due to time variations of the geomagnetic field. This latter effect can be significantly reduced by correcting to a well located reference station. Because of the areal distribution of the geomagnetic coast effect, a land station close to the survey area may not be as effective as a more distant site. Referencing to an ocean bottom magnetometer, at least to moderate levels of disturbance, is comparable to correcting to a well located land station. Using a combination of land and ocean bottom reference data produced a reduction in the cross-over error from 25 to 11 nT for this survey, effectively removing the geomagnetic variation term. This technique should prove even more useful for surveys conducted during periods of higher geomagnetic activity.Contribution from the Earth Physics Branch No. 824. 相似文献
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在海洋地磁测量中地磁日变的影响不可忽视,由于海底地磁日变观测站可建在测区内或附近,通常情况下能较好地反映测区范围内的地磁日变状况.但从实际观测资料对比发现,海底地磁观测站站位水深对地磁有效信息的保留存在一定的相关性.随着水深增大,其保留的信息量逐渐减少,即水层对地磁信息有着明显的衰减作用. 相似文献
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黄河三角洲前沿的陆地由于受地面沉降的影响,使地面高程不断发生变化.在水深测量中,深度基准面是根据陆地水准点高程确定的,陆地水准点高程的变化影响深度基准面的确定,从而影响水深测量的准确性.又由于黄河海港附近有一无潮点,其附近的潮汐性质变化大,在黄河三角洲前沿大范围水深测量中,根据测区潮位变化设立足够的验潮站及统一各个验潮站的水尺零点到同一个深度基准面上,是保证水深测量结果可靠的关键.通过黄河三角洲前沿陆地高程的变化和验潮获得的资料,介绍了黄河三角洲前沿深度基准面的变化和潮位变化情况. 相似文献
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莱州湾具有典型的大陆架结构，潮汐性质复杂。本研究根据莱州湾沿岸4处典型验潮站的多年数据计算了各站深度基准面值及保证率，并与相关涉海部门现采用值进行了比对分析。结果表明：个别验潮站计算值与相关涉海单位采用的深度基准面值有明显差异。本文就此进行了分析并提出了合理性建议。4处验潮站周边均埋设了高等级水准点，通过历年实施的高等级水准联测来监测各站高程基准点变化量，计算结果可用以维持区域垂直基准，为今后莱州湾港口建设、航道施工、水深测量、船舶通航及信息发布等提供更加准确的基础资料。 相似文献
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This paper presents soft computing approach for estimation of missing wave heights at a particular location on a real-time basis using wave heights at other locations. Six such buoy networks are developed in Eastern Gulf of Mexico using soft computing techniques of Artificial Neural Networks (ANN) and Genetic Programming (GP). Wave heights at five stations are used to estimate wave height at the sixth station. Though ANN is now an established tool in time series analysis, use of GP in the field of time series forecasting/analysis particularly in the area of Ocean Engineering is relatively new and needs to be explored further. Both ANN and GP approach perform well in terms of accuracy of estimation as evident from values of various statistical parameters employed. The GP models work better in case of extreme events. Results of both approaches are also compared with the performance of large-scale continuous wave modeling/forecasting system WAVEWATCH III. The models are also applied on real time basis for 3 months in the year 2007. A software is developed using evolved GP codes (C++) as back end with Visual Basic as the Front End tool for real-time application of wave estimation model. 相似文献
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The full-wave modeling of storm seismoacoustic field propagation in oceanic waveguides and at the ocean-continent border in
the low-frequency range from 0.01 to 1 Hz using the numerical grid method is considered. The 2D model proposed by Press and
Ewing for planar waveguides above the homogeneous elastic halfspace was chosen as a basis. The influence of a layer of deposits
and features of the crust of the oceanic- and continent-type was taken into account in the more complex model. The effects
of the carrier frequency, orientation of directivity diagram of the signal source, and steepness of the continental slope
were investigated. A system of the second-order linear partial differential equations of hyperbolic type was solved in the
process of modeling. The inertia properties and attenuation in the medium were taken into consideration. Fast-operating locally
recursive nonlocally asynchronous parallel algorithms were used in the modeling, which were developed at the Keldysh Institute
of Applied Mathematics of the Russian Academy of Sciences for modeling of plasma processes. At present, these algorithms are
adapted for modeling of geophysical fields. A computing system consisting of two computers based on eight-core processors
is used for computations. As a result, instantaneous pictures of microseism field propagation were constructed at the specified
cross sections of the medium at sequential time moments, and the microseism’s frequency spectra and synthetic seismograms
were obtained for some characteristic points of aqueous medium, bottom sediment, and land. The considered algorithms of full-wave
numerical modeling and the computing system can be easily adapted to the 3D variant of anisotropic and inhomogeneous media
specified by analytical expressions. 相似文献
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The Newlyn Tidal Observatory is the most important sea level station in the United Kingdom. It commenced operations in 1915 as part of the Second Geodetic Levelling of England and Wales, and the mean sea level determined from the tide gauge during the first six years (May 1915–April 1921) defined Ordnance Datum Newlyn (ODN) which became the national height datum for the whole of Great Britain. The 100 years of sea level data now available have contributed significantly to many studies in oceanography, geology, and climate change. This paper marks the centenary of this important station by reviewing the sea level (and, more recently, detailed land level) measurements and Newlyn's contributions to UK cartography, geodesy and sea-level science in general. Recommendations are made on how sea and land level measurements at Newlyn might be enhanced. 相似文献