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1.
早在五十年代,海洋科技工作者已开始利用浮标布设海洋调查仪器,进行海上观测的试验工作。目前被采用的浮标系统,大体有三种类型:(1)锚泊浮标系统,利用各类自含式海洋调査仪器进行测量,定期收回资料;(2)遥测浮标系统,利用无线电遥控和收发各种海洋观测数据;(3)漂移浮标系统,利用浮标本身的漂移,进行海流和其他要素的观测。本文主要介绍浅海锚泊浮标系统的设计和使用情况。
对锚泊浮标系统的研究和实验,许多国家已做了大量有成效的工作。目前关于浮标的设计和锚泊方法尚无統一意见,但是可以看出,大多趋向于采用水下浮标张缆锚泊。这种方法使得浮标系统比起遥测浮标系统来,较为轻小、经济、方便,适合于进行多站同步观测。国外在海洋调查中经常利用这种系统作较长期的海流观测。
我所在六十年代初就已开始了锚泊浮标系统的研究、实验,1964年进行了新的研究设计工作,并在“全国海洋仪器会战”期间,完成了整套系统的计算设计与海上实验,经过鉴定,建议作小批量生产。
近年来,国家海洋局第一海洋研究所、中国科学院南海海洋研究所利用该浮标系统作过多次海上试用,取得了海流长期观测资料,初步考验了该系统的性能。我们最近又对某些部件作了一定的改进,并进行了海上实验。但是,实验也表明:此方法不宜在渔场区和台风盛行季节使用,因易被渔网拖损和丢失。现综合报告如下。 相似文献
2.
《制图学和地理信息科学》2013,40(4):331-346
This paper presents the first data structure for a variable scale representation of an area partitioning without redundancy of geometry. At the highest level of detail, the areas are represented using a topological structure based on faces and edges; there is no redundancy of geometry in this structure as the shared boundaries (edges) between neighbor areas are stored only once. Each edge is represented by a Binary Line Generalization (BLG)-tree, which enables selection of the proper representation for a given scale. Further, there is also no geometry redundancy between the different levels of detail. An edge at a higher importance level (less detail) does not contain copies of the lower-level edges or coordinates (more detail), but it is represented by efficiently combining their corresponding BLG trees. Which edges have to be combined follows from the generalization computation, and this is stored in a data structure. This data structure turns out to be a set of trees, which will be called the (Generalized Area Partitioning) GAP-edge forest. With regard to faces, the generalization result can be captured in a single tree structure for the parent-child relationships—the GAP face-tree. At the client side there are no geometric computations necessary to compute the polygon representations of the faces, merely following the topological references is sufficient. Finally, the presented data structure is also suitable for progressive transfer of vector maps, assuming that the client maintains a local copy of the GAP-face tree and the GAP-edge forest. 相似文献
3.
《制图学和地理信息科学》2013,40(3):267-280
The GeoJabber concept, protocol, and working prototype software introduced here enable same-time, different-place collaborative geovisualization. The key problem this work addresses is how to turn geovisual software states into persistent textual representations that can be shared between users. In the current implementation, GeoJabber leverages three key Open Source technologies: the GeoViz Toolkit, the Jabber protocol, and XStream. GeoJabber is the first project to support same-time different-place geovisualization tool state sharing. As part of this effort, this paper presents a typology of sharable geovisualization software states, rooted in the concepts of data, display, and category. 相似文献
4.
《African Journal of Marine Science》2013,35(1):263-279
St Lucia is one of the largest estuarine systems in Africa, and attracts thousands of anglers each year. Catchcard data from the National Marine Linefish System for the years 1986–1999 were analysed to determine catch composition, catch per unit effort (cpue) and seasonality of catches by recreational anglers. Because not all anglers completed catch cards, estimates of total catch were made using additional data on the number of private boat outings, the number of boat trailers at boat slipways and the number of boats recorded entering the campsite gates during 1992 and 1993. In all, 27 fish families, constituting 55 species, were recorded by recreational anglers. Dusky kob Argyrosomus japonicus, spotted grunter Pomadasys commersonnii, perch Acanthopagrus berda, Natal stumpnose Rhabdosargus sarba, springer Elops machnata and mini-kob Johnius dorsalis were the most prominent species caught in terms of numbers and mass. Catch rates expressed numerically (fish angler?1 h?1) peaked during the summer and early winter. However, in terms of mass, catch rates peaked during late winter and spring, when there were increased landings of large dusky kob. Fluctuations in cpue were linked to salinity and estuary mouth conditions (i.e. mouth closure). Despite annual fluctuations in cpue, regression analysis revealed an overall downward trend for the dominant species (dusky kob and spotted grunter) and a gradual increase for stumpnose, perch and springer, but with the exception of stumpnose, these trends were not significant. Socio-economic aspects of the fishery were also investigated by conducting an independent boat-angler survey. The value of the recreational fishery, in terms of accommodation and direct angler expenditure, was estimated to be in the region of R9 million during 1992. Angler attitudes towards fishing regulations were positive and anglers generally had a good knowledge of the regulations for target species. Based on this assessment, a number of suggestions are made regarding the future management of the recreational fishery at St Lucia. 相似文献
5.
《African Journal of Marine Science》2013,35(3):603-612
Reproductive features of the poorly known oceanic squid Octopoteuthis sicula are described and quantified to gain insight into the reproductive biology of the species. The data are based on 39 complete and partial specimens from southern African waters, collected between 1975 and 2005. The specimens ranged in mantle length from 38 mm to 290 mm and included juveniles and mature females and males. The species shows female-biased sexual size dimorphism. Ovulation is asynchronous, indicating a repeated spawning strategy. Males transfer spermatophores presumably by using their long terminal organ. Spermatangia (discharged spermatophores) were found implanted in several parts of the body in both females and males, including in the anterior dorsal and ventral rugose, semi-gelatinous mantle tissue of maturing and mature females. This modified mantle tissue was only well developed in females. The morphologies of the spermatophore and the spermatangium of O. sicula are described. The spermatophoric reaction is reconstructed, using various stages of discharge, to provide insight into the process of intradermal implantation of spermatangia of this species. 相似文献
6.
《制图学和地理信息科学》2013,40(3):140-153
A hybrid system that integrates two-dimensional (2D) GIS and three-dimensional (3D) visualization has been developed to provide unique solutions to application domains where traditional 2D GIS and 3D visualization cannot alone provide a solution. In this paper, we focus on three key issues in realizing such an integrated system, including large-scale terrain rendering, 2D and 3D combination display (for example, rendering 2D GIS layers in 3D space), expanding traditional 2D GIS analysis functions into a 3D environment, and visualizing 3D geographical data. A generic framework is developed to integrate 3D visualization with various types of 2D GIS, such as commercial GIS software, open source GIS software and spatial databases. A prototype 2D and 3D hybrid system that seamlessly integrates 2D GIS (developed with ArcEngine) and 3D rendering engine (developed with DirectX) is then developed based on the framework. In this hybrid system, 2D and 3D data are viewed within the same scene. Multiple 2D GIS layers are overlaid on the base terrain using a Level of Detail (LOD) model. Advanced query functions, data accessing, data management and spatial analysis, which are executed in the traditional 2D GIS, are provided to users in a 3D environment by continuously transforming information between the 2D GIS subsystem and the 3D subsystem. The 3D data are organized and displayed by Keyhole Markup Language (KML) and textured 3D models in the COLLAborative Design Activity (COLLADA) format. The prototype demonstrates that this hybrid system has effectively addressed the three key issues identified above and that it can seamlessly integrate 2D GIS and 3D visualization. The hybrid system has great potential to be employed in many application domains, such as urban planning, landscape design and environmental decision making, among others, to enhance the 3D design capability and facilitate public participation in the planning, design and decision-making process. 相似文献
7.
《制图学和地理信息科学》2013,40(2):131-147
Part of a cuboctahedron-based geodesic map projection by Buckminster Fuller is expanded to spherical quadrilaterals with opposite sides equal. Points on such a quadrilateral can be described by intersections of geodesics, which provide parameterized coordinate values in a Geodesic Coordinate System. Through a linear transform of the geodesic coordinates, a spherical quadrilateral maps to a parallelogram. The resulting map has the same constant scale on all four sides. Within the map, all lines parallel to the sides correspond to geodesics on the globe. Spherical rectangles, spherical squares, and diamonds (spherical rhombi) are specifically examined; various tiling sets of diamonds can be used to cover the globe. Non-projection applications in geometry, astronomy, and computer graphics are described. 相似文献
8.
《African Journal of Marine Science》2013,35(1):37-51
Information on the vertical chlorophyll structure in the ocean is important for estimating integrated chlorophyll a and primary production from satellite. For this study, vertical chlorophyll profiles from the Benguela upwelling system and the Angola-Benguela front were collected in winter to identify characteristic profiles. A shifted Gaussian model was fitted to each profile to estimate four parameters that defined the shape of the curve: the background chlorophyll concentration (B 0), the height parameter of the peak (h), the width of the peak (σ) and the depth of the chlorophyll peak (zm ). A type of artificial neural network called a self-organizing map (SOM) was then used on these four parameters to identify characteristic profiles. The analysis identified a continuum of chlorophyll patterns, from those with large surface peaks (>10 mg m?3) to those with smaller near-surface peaks (<2 mg m?3). The frequency of occurrence of each chlorophyll pattern identified by the SOM showed that the most frequent pattern (～12%) had a near-surface peak and the least frequent pattern (～2%) had a large surface peak. These characteristic profile shapes were then related to pertinent environmental variables such as sea surface temperature, surface chlorophyll, mixed layer depth and euphotic depth. Partitioning the SOM output map into environmental categories showed large peaks of surface chlorophyll dominating in water with cool temperature, high surface chlorophyll concentration and shallow mixed layer and euphotic depth. By contrast, smaller peaks of subsurface chlorophyll were in water with warmer temperature, lower surface chlorophyll concentration, intermediate mixed layer and deep euphotic depth. These relationships can be used semi-quantitatively to predict profile shape under different environmental conditions. The SOM analysis highlighted the large variability in shape of vertical chlorophyll profiles in the Benguela. This suggests that an ideal typical chlorophyll profile, as used in the framework of biogeochemical provinces, may not be applicable to this dynamic upwelling system. 相似文献
9.
《African Journal of Marine Science》2013,35(1):141-159
Trends in the spatial pattern of spawning of pilchard Sardinops ocellatus and anchovy Engraulis capensis during the period 1971–1985 were examined in relation to large-scale environmental anomalies outside the spawning area. Shifts in the locality of peak spawning of anchovy often coincided with that of pilchard, although sometimes anchovy were slower to respond to an environmental change. With negative sea surface temperature (SST) anomalies spawning shifted northwards, whereas with positive anomalies spawning took place both in the north and farther south. With a transition from negative SST anomalies early in the spawning season to zero or positive anomalies later in the spawning season, the impact on anchovy and pilchard spawning differed. Anchovy spawning was either reduced or absent during the negative phase of transitional seasons, thus avoiding unfavourable conditions. Pilchard, on the other hand, were spawning mainly in the north during the negative phase of the transitional seasons, but also in the south during the zero to positive phase. The shifts in spawning locality in response to environmental anomalies outside the spawning area imply that explanations for such shifts need not be sought in changes in biomass or age structure or in the fact that stocks may be genetically different, all theories previously advanced. 相似文献
10.
《制图学和地理信息科学》2013,40(3):261-282
A great convergence of cartography, secrecy, and power occurred during the Cold War. In the American case, a complex series of interactions between secret and classified programs and institutions and their publicly accessible counterparts accomplished both traditional and novel objectives of military geographic intelligence. This process also yielded the World Geodetic System, a mass-centered "figure of the earth" at accuracies adequate for warfare with intercontinental ballistic missiles. A structural and institutional separation developed between enterprises charged with overhead data acquisition systems, which were classified at increasingly high levels of secrecy, and those responsible for data reduction, analysis, and mapping systems, which remained largely unclassified and publicly accessible, in part to conceal the classified data acquisition systems. This structural separation destabilized photogrammetric mapping by displacing systems that privileged dimensional stability with systems that privileged novel sensor types more appropriate to Cold War geo-political objectives and constraints. Eventually, photogrammetric mapping systems were re-stabilized by successfully implementing analytical solutions imposed in digital mapping and data management systems. This achievement re-privileged dimensional stability, now redefined to the new media of geo-referenced digital data. In the early 1970s these developments culminated in advanced research projects of Military Geographic Intelligence Systems (MGIS). Their deployment in the Vietnam War was both their apex and their undoing. In the aftermath, classified mapping and database systems diverged from civilian versions of MGIS, which became known as Geographic Information Systems (GIS). 相似文献