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Monitoring the thickness changes of channel siltation is paramount in safeguarding navigation and guiding dredging.This paper presents a novel method for realizing the field monitoring of channel siltation in real time.The method is based on the bistatic scattering theory and concerned more with the receiving and processing of multipath signal at high-frequency and small grazing angle.By use of the multipath propagation structure of underwater acoustic channel,the method obtains the silt thickness by calculating the relative time delay of acoustic signals between the direct and the shortest bottom reflected paths.Bistatic transducer pairs are employed to transmit and receive the acoustic signals,and the GPS time synchronization technology is introduced to synchronize the transmitter and receiver.The WRELAX (Weighted Fourier transform and RELAX) algorithm is used to obtain the high resolution estimation of multipath time delay.To examine the feasibility of the presented method and the accuracy and precision of the developed system,a series of sea trials are conducted in the southwest coast area of Dalian City,north of the Yellow Sea.The experimental results are compared with that using high-resolution dual echo sounder HydroBoxTM,and the uncertainty is smaller than ±0.06 m.Compared with the existing means for measuring the silt thickness,the present method is innovative,and the system is stable,efficient and provides a better real-time performance.It especially suits monitoring the narrow channel with rapid changes of siltation. 相似文献
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随着科学技术的发展,学生学习的方式和获取知识的途径发生了改变.地理信息技术作为地理重要的研究工具,不应该再停留在纸面概念的学习,应该成为学生解决地理问题的工具.本文分析了QGIS在地理项目式学习中的适用性,以定量分析人口分布与地形关系为例,探索QGIS在地理项目式学习活动中的应用. 相似文献
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