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91.
INS/GPS组合导航系统直接法滤波中是直接以导航系统输出的导航参数(位置、速度等)作为状态,所以系统方程为非线性方程。UKF(Unscented Kalman Filter)是一类以UT变换为基础,以卡尔曼线性滤波为框架,采用确定性采样策略逼近非线性分布的非线性滤波算法。由于它是对后验概率密度进行近似来得到滤波估计,所以避免了非线性系统中状态方程的线性化问题,能较好地解决系统方程非线性问题。论文INS/GPS组合导航系统中采取直接法,建立非线性模型进行UKF滤波解算,并与EKF方法比较,实验结果显示UKF方法能更好地解决系统状态方程非线性的问题,并得到更高的导航精度。 相似文献
92.
Protecting privacy on the Web is becoming increasingly complicated because of the considerable amount of personal and sensitive information left by users in many locations during their Web browsing and the silent actions of third party sites that collect data, aggregate information and build personal profiles of Internet users in order to provide free and personalized services. On the other hand, most of people are unaware that their information may be collected online, and that, after their aggregation from multiple sources, could be used for secondary purposes, such as linked to allow identification, without user’s notice. 相似文献
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Teija Vainio 《Digital Creativity》2013,24(1):26-39
While there have been many studies of navigation design guidelines for integrating maps in mobile devices, we argue that the research focus should turn more towards the design of multimodal navigation aids, which would reflect the impact of typical human wayfinding behaviour. Therefore, we suggest an interdisciplinary design approach, i.e. building on urban design practice that focuses on supporting the navigation of pedestrians in urban areas. The design implications are explored in this study with the subjects being pedestrians accomplishing wayfinding tasks in an unfamiliar, urban area. The main areas that this paper contributes to are: investigating the design implications of multimodal navigation aids; evaluating these in the context of mobile wayfinding tasks; and reflecting the results according to the user's wayfinding strategies and spatial anxiety. It is concluded that through designing multimodal tracks into mobile navigation applications we can help users to find their way in unfamiliar, urban environments. 相似文献
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虞东亮 《水利水电工程设计》2011,30(1):4-8
桃源水电站是沅水最末一个梯级电站,枢纽主要由泄洪闸、土石副坝、电站厂房、船闸等建筑物组成。可研阶段水工共提出3类9种枢纽布置方案,初选3种方案作重点比较。针对不同的枢纽布置,施工总计提出了12个分期导流及通航方案进行研究,并提出推荐方案供枢纽布置优选决策。方案比选研究思路及成果可供类似工程借鉴。 相似文献
99.
水电枢纽建设改善了库区航运条件,但电站泄流会对坝下游航道产生影响,需要对此研究以实现水电开发与航运建设的协调发展.在分析大量研究文献与资料的基础上,总结了电站下游流量、泥沙、水位在电站建设前后变化与沿程变化的特性,归纳了电站泄流对坝下游设计最低通航水位、通航水流条件(沿程流速、流向与比降)、河床演变的影响,以及提出了应对策略与措施等研究成果,最后指出了有待进一步研究的问题,以期推动本领域研究的深入开展. 相似文献
100.
Navigation‐induced physical forces have been suggested to modify the structure of riverine fish assemblages by impeding especially the recruitment of littoral bound species. To investigate the effect of vessel frequency on fish, we compared the composition and seasonal succession of young‐of‐the‐year (YOY) fish assemblages in three similarly degraded river reaches differing in average vessel passages (2, 6 and 41 per day). Fish were caught by electrofishing biweekly between May and September. Multivariate tests were used to analyse differences between YOY‐fish assemblages and hurdle regression models applied to determine abiotic factors predicting fish occurrence and abundance. Roach (Rutilus rutilus) and perch (Perca fluviatilis) densities were compared. Roach larvae remain in the littoral zone while perch larvae shift to the pelagic zone immediately after hatch. YOY‐fish assemblage structure substantially changed along the traffic intensity gradient. In the high traffic intensity reach, species number and total fish density were markedly reduced compared to the other reaches. Roach densities were lowest in the high traffic intensity reach whereas perch densities did not decline along the gradient. Hurdle regressions confirmed a stronger effect of commercial navigation traffic intensity on roach than on perch. The total zooplankton biomass was highest in the high traffic intensity reach. Our results provide empirical evidence that intensive commercial navigation impoverishes fish assemblages in width‐restricted waterways. They underlined that in particular those species that have their first nursery habitats in shoreline areas were more affected by intensive commercial navigation than species whose larvae live predominantly pelagic. The results indicate that the negative effect of intensive navigation on riverine fish results primarily from the navigation‐induced hydraulic disturbances along the banks. Therefore, mitigation of navigation‐induced hydraulic forces is required to prevent degradation of fish communities in waterways. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献