湛江湾外航道二侧浅滩冲淤变化的成因分析

摘 要：通过对湛江湾不同时期的海底地形图进行对比,发现近年来湛江湾外航道南北二侧的拦门沙体积在不断缩小,地貌形态由丘陵状逐渐向梳状地貌演变,其中航道南侧等深线一直向东海岛岸线逼近,岸线侵蚀严重。文章对导致这一变化的成因进行了系统全面的分析研究,结果表明,由于湛江湾内近年来大规模的围填海工程改变了整个湛江湾的纳潮量、泥沙来源、悬沙含量和潮流特征,使得原本处于平衡状态的湾外浅滩发生冲淤变化。     

扩大厦门高集海堤过水断面刻不容缓

半个世纪以来，厦门通过围海筑堤、填海造地等海岸工程，极大地改变了海域环境结构，涨域面积、纳潮量和水动力大幅减少，港湾出现淤积，湾口岸线侵蚀。为此，必须尽快扩大高订海堤的过水断面，恢复西海域生态平衡。     

半封闭海湾围填海对水动力 环境的影响分析

以东山湾为例,采用平面二维数学模型,从潮流、纳潮量和水交换3个方面探讨湾内围填海对东山湾水动力环境的影响.研究结果表明:随着填海面积的增加,影响范围及程度不断增大;湾口海域对填海区位置及填海范围的响应较为敏感,当填海范围扩大到湾口海域后,纳潮量减少10%以上,大潮平均水交换率均减小8.82%,小潮平均水交换率减小13.33%,易影响湾内的污染物扩散能力,从而引发水质和生态问题.     

深圳围海造地对海洋环境影响的分析

深圳市以山地丘陵地貌为主，平原地貌只占26．45％，城市建设用地非常紧张，沿岸港口、工业和城市建设，通常以围海造地补充不足，至2000年，深圳市围海造地面积已达2680hm^2，这给海洋环境带来不少的负面影响，主要表现在：(1)西部海岸地区滩槽演变剧烈，不稳定性加强，给今后西部港区运作环境带来威胁；(2)纳潮量迅速减少，经过20年的围垦，西部伶仃洋海岸地区纳潮量减少20～30％，深圳湾纳潮量减少15．6％，纳潮量的锐减使得潮流流速降低，流向发生变化，更加不利于污染物的稀释与扩散；(3)沿海水环境污染加重，深圳市西海岸海水普遍达不到3类水标准；(4)海岸生态承载力下降，仅1988—2000年深圳湾沿岸围垦占用红树林保护区面积达到147hm^2，占整个保护区面积48．8％，使得生物多样性降低，物种数量大幅减少．通过对上述海洋环境的影响分析，提出未来填海工程的指导策略和整治意见，以期做到海岸地区的可持续发展。     

海岸带开发对葫芦山湾水交换能力的影响

为评价2000年至2010年海岸带开发活动对葫芦山湾水交换能力的影响,本文通过数值模拟方法计算2000年、2005年和2010年葫芦山湾海域潮流场、纳湖量和海湾水交抉率的情况。研究表明,2000年至2010年葫芦山湾岸线减少2.1km,海域面积减少约14.8km2s2000年至2005年纳湖量平均减少了0.21×108m3,水交换率平均增大了3.15%;2005年至2010年纳潮量平均减小了0.11×108m3,水交换率平均减小了0.05%,说明葫芦山湾海岸带开发活动速成海湾纳潮量减小,导致环境容量的逐年减少,是海湾污染日益加剧的主要原因之一。     

七里海潟湖近百年水体交换能力变化特征

基于三重嵌套的非结构网格建立七里海潟湖水动力和物质输运模型，采用实测资料对模型的潮位、流速和流向进行验证，结合卫星遥感影像资料，模拟1950—2018年七里海潟湖地貌演变过程，利用水体冲刷时间尺度探究不同工况下潟湖水体交换能力的变化特征。结果表明，自然条件下，径流改变较海平面变化对水体交换能力的影响更为显著；挡潮闸的开闭是影响潟湖水体交换能力的关键因素，同时潟湖围垦降低了纳潮量也减弱了水体交换能力，但降低幅度较小；潮汐通道工程的变化是影响水体交换能力的主要原因，潮汐通道由弯曲变为顺直及其拓宽均增强了潟湖的水体交换能力。     

三沙湾纳潮量及湾内外的水交换

根据三沙湾多年实测潮位资料和2个临时潮位站的实测资料,分析了三沙湾潮汐特征,计算了纳潮量、海水的平均交换率和海水半更换期.结果表明:三沙湾潮差较大,有较强的纳潮能力.但由于其水域面积较大,地形也比较复杂,其整个区域海水的平均“更新能力”一般.当潮差累积率为20%(大潮)时,三沙湾的海水半更换期约为36个潮周期;当潮差累积率为50%(中潮)时,海水半更换期约为75个潮周期;当潮差累积率为80%(小潮)时,海水半更换期达到114个潮周期.     

湛江湾海区流场特征及其对水环境的影响

湛江湾海区的涨潮潮流流向主要向北,落潮潮流流向主要向南,且落潮流速大于涨潮流速。湛江湾潮流具有正规半日潮和不正规半日潮两种性质．潮流运动形式以往复流为主。海区余流总体效应是指向湾外;流场对湾内水环境有一定的影响．需要进行科学管理。     

有限体积海岸海洋模型模拟泉州湾人工岛建设对水交换的影响

以泉州湾秀涂人工岛的建设为例,基于有限体积海岸海洋模型,建立泉州湾三维数值模型,模拟分析建岛前、后水动力特征、潮致余流和纳潮量的变化.采用欧拉弥散方法模拟污染物浓度的对流扩散,对泉州湾的水交换能力进行分析.结果表明:建岛后,大部分海域的海潮流速约减小0.1 m·s^-1;石湖港区人工岛连线以西大部分区域的潮致余流变化不显著,但湾口的潮致余流出现较为明显的减少;纳潮量的变化较为明显,小潮期间纳潮量的变化率为10.09%,使小潮期间湾内水体与外海的交换能力变弱,更易遭受污染威胁;洛阳江流域和金屿的污染物浓度差变化较大,导致湾内水体的半交换时间约增加3 d.     

钦州湾潮流模拟及其纳潮量和水交换周期计算

根据FVCOM模式的模拟结果和2006年至2008年间对钦州湾海流的观测资料,分析钦州湾的潮流特征,并计算该湾在平均海平面的纳潮量和大、小潮的水交换半更换周期。结果表明,该湾潮差很大,潮流主要为往复流,平均潮差纳潮量为7．55×10^8m^3,大、小潮水交换的半更换周期分别为1．70个周期和4．53个周期。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to