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901.
GPS动态定位数据的处理广泛采用卡尔曼滤波技术,而应用卡尔曼滤波要求运动模型准确可靠,但由于载体真实运动的复杂多变,任何单一模型都难以全面描述,致使单一模型的滤波都容易出现模型误差。针对这一问题,将机动目标跟踪领域广泛应用的交互式多模型算法引入到车载导航中。通过分析车辆的运动特点,选取匀速直线模型和当前统计模型进行交互;同时考虑到车载终端计算能力有限,将状态变量在各方向解耦。仿真显示,在机动时改进的算法和单一模型的自适应算法基本相当,但在非机动时改进的算法明显占优。 相似文献
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904.
Revisiting Peruvian anchovy (Engraulis ringens) trophodynamics provides a new vision of the Humboldt Current system 总被引:6,自引:4,他引:2
The Peruvian anchovy or anchoveta (Engraulis ringens) forages on plankton and is a main prey for marine mammals, seabirds, fish, and fishers, and is therefore a key element of the food web in the Humboldt Current system (HCS). Here, we present results from the analysis of 21,203 anchoveta stomach contents sampled during 23 acoustic surveys over the period 1996–2003. Prey items were identified to the genus level, and the relative dietary importance of different prey was assessed by determination of their carbon content. Variability in stomach fullness was examined relative to the diel cycle, the distance from the coast, sea surface temperature, and latitude, using generalized additive models (GAMs). Whereas phytoplankton largely dominated anchoveta diets in terms of numerical abundance and comprised >99% of ingested prey items, the carbon content of prey items indicated that zooplankton was by far the most important dietary component, with euphausiids contributing 67.5% of dietary carbon followed by copepods (26.3%). Stomach fullness data showed that anchoveta feed mainly during daytime between 07h00 and 18h00, although night-time feeding also made a substantial contribution to total food consumption. Stomach fullness also varied with latitude, distance from the coast, and temperature, but with substantial variability indicating a high degree of plasticity in anchoveta feeding behaviour. The results suggest an ecological role for anchoveta that challenges current understanding of its position in the foodweb, the functioning of the HCS, and trophic models of the HCS. 相似文献
905.
地理信息系统在海岸海洋地貌研究中的应用 总被引:4,自引:0,他引:4
随着现代海洋观测技术的发展,通过海岸海洋地貌调查获得的数据急剧增长。运用地理信息系统(GIS)将不同学科、不同来源、不同格式的数据进行集成管理、分析和表达已成为当前海岸海洋地貌研究的重点。系统介绍了GIS技术在海岸海洋地貌研究中新的方法体系,包括数据获取、数据处理、数据分析和数据表达四个部分,重点研究了GIS空间技术、海底地形建模和用三维可视化技术解译海洋地学,探索陆海交互作用中隐含信息的方法,并将其应用到沿海城市规划、海港选址、大陆架岛礁地貌环境研究的具体实例中,研究范围从陆到海涵盖整个海陆交互作用带,为海岸海洋社会发展、经济建设及外交权益提供科学基础和决策支持。通过上述方法体系与应用研究说明,以GIS为核心建立的多源地理空间信息平台使传统海岸海洋地貌研究的范围、内容及方法都发生了重大变化,但多源数据信息的精确解译和成功应用必须同时具有空间信息学和地貌学专家知识。 相似文献
906.
珠江口盆地白云凹陷陆坡区10.5 Ma以来的沉积体系 总被引:2,自引:0,他引:2
通过对珠江口盆地白云凹陷陆坡区10.5Ma以来的地震相分析,共识别出席状平行亚平行地震相、透镜状前积地震相、深切河谷地震相、帚状地震相和杂乱地震相,不同的地震相分别代表不同的沉积体系类型。综合所识别的地震相类型,分析了陆架边缘下切谷、浊积扇和陆架边缘三角洲3种主要的沉积体系及其配置关系。物源供给是影响陆坡区沉积体系发育的最重要因素,是沉积体系发育的物质基础,海平面变化和构造运动为沉积体系发育提供了可容纳空间,3种影响因素共同影响了陆坡区沉积体系的发育。 相似文献
907.
Over 3000 predominantly small-scale fishers have exited the New Zealand's quota management system (QMS) between its inception in 1986 and 2000. This study, based on the Ministry of Fisheries database and a questionnaire sent to the exiters, establishes that compliance costs in general, and those specifically related to the QMS, were one of the most consistent reasons for exit. Uncertainty about future QMS policy and the high cost of quota were also significant factors. It appears that the small fishers’ perception of high compliance cost can be supported by industry data. 相似文献
908.
As a popular solution for mooring an FPSO (Floating Production, Storage and Offloading) permanently in shallow water, the soft yoke mooring system has been widely used in ocean oil production activities in the Bohai Bay of China. In order to simulate the interaction mechanism and conduct dynamic analysis of the soft yoke mooring system, a theoretical model with basic dynamic equations is established. A numerical iteration algorithm based on error estimation is developed to solve the equations and calculate the dynanfic response of the mooring system due to FPSO motions. Validation is conducted by wave basin experimentation. It is shown that the numerical simulation takes only a few iteration times and the final errors are small. Furthermore, the calculated results of both the static and dynamic responses agree well with those ones obtained by the model test. It indicates that the efficiency, the precision, the reliability and the validity of the developed numerical algorithm and program are rather good. It is proposed to develop a real-time monitoring system to further monitor the dynamic performance of the FPSO with a soft yoke mooring system under various real sea environments. 相似文献
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