Aiming at the estimation of Doppler shift factor in underwater acoustic communication, a new method based on current velocity measurement is proposed. By analyzing the relationship between current velocity and the Doppler shift factor, the calculation process of underwater acoustic communication system is simplified, the measurement method and ability of electromagnetic current meter is studied, and some on-site error sources are analyzed. The results indicate that the piecewise linear method can effectively characterize the measurement of electromagnetic current meter. Zero offset drift has to be modified frequently. The displacement effect is the main factor affecting the measurement results of the current meter, and the maximum indication error can be up to 10%. © 2021 IEEE

Flow data are key information for effective river management. In recent years, the UAV (Unmanned Aerial Vehicle) technology has been experiencing rapid development and has exhibited unique advantages in the field of ground surveying and mapping. A recent advancement in river flow measurement involves the use of UAV as an aerial platform for acquiring water surface flow velocity distributions through Large Scale Particle Image Velocimetry (LSPIV). In this paper, a uniform rotation platform has been first developed to mimic water motion and used to study the influences of time interval and UAV drift on the measurement. The results show that it is crucial to choose the appropriate time interval of the image pairs so as to reduce the calculation errors of cross correlation between PIV interrogation windows. In addition, it has been found crucial to carry out image rectification to eliminate the influence of UAV drift before cross-correlation calculation. The SURF (Speeded-Up Robust Features) method has been used for image rectification and has been illustrated to be an effective and practical method in the real-world survey of the water surface flow field on Qinhuai River, Nanjing, China and River Cam in the UK. © 2021 IEEE.

文章分析目前声学多普勒剖面流速仪（ADCP）的历史现状,实验室计量检测主要是针对ADCP的底跟踪性能、水跟踪性能、测深性能、声性能、定向性能和纵横摇性能6个方面进行的。本文着重介绍ADCP的5个检测平台,重点说明速度检测平台中的水跟踪速度的微纳米气泡法检测。以RDI-WHR600-1ADCP为例说明了检测过程以及试验数据处理过程。最后得出实纳米气泡是静水槽检测ADCP水跟踪较好声学反射物质。为拖曳水槽实现ADCP检测改造建设提供了技术思路。给出了ADCP实验室检测的建议及ADCP检测发展的趋势。

雷达水位计在水文测验中的应用越来越广泛,目前此类产品存在的一个问题是不能排除船只、漂浮物等外界环境因素的干扰,进而导致水位测量出现误差。本文提出一种基于FMCW雷达水位计的区分水面与其它干扰物体的方法,在快速傅里叶变换的基础上根据水面的特性进行区分,并根据研究成果制作了雷达水位计样机。实验结果表明,方法合理可行,能够有效的解决干扰物对水位测量的影响,具有良好的应用前景。

针对雷达天线前端模拟电路复杂、成本高的问题,设计了一种基于毫米波传感器IWR1642的77GHz雷达水位计。完整的设计了雷达水位计所需要的部件包括平面微带天线,硬件电路以及外壳,采用加速度传感器矫正安装角度、RS485通讯传递数据。叙述了雷达水位计软件的工作流程,采用在快速傅里叶变换的基础上进行选带傅里叶变换的算法计算差频信号的频率。制作了水位计测试样机,并在实验室中完成测试,测量误差小于1cm,满足雷达水位计的测量要求。

Based on the analysis of the current situation of hydrologic emergency monitoring capability of barrier lake, and consider the actual needs of portability, environmental adaptability, technological advancement, accuracy suitability, reliability, etc. The overall structure of the improvement of hydrologic emergency monitoring capability of the barrier lake was designed, and the detailed program were carried out on data collection, data transmission, data processing and monitoring and guarantee. Through the improvement of emergency monitoring capacity, can provide better basic support for emergency disposal of barrier lake.

In recent years, there have been some barrier lakes formed by earthquakes or landslides in China, such as the Tangjiashan barrier lake in 2008 and the Baige barrier lakes (twice) in 2018. The barrier lake often brings huge destructive risks to the upstream and downstream affected areas. In order to protect the lives and property of the people, it is necessary to carry out corresponding scientific disposal. The premise of disposal is to obtain detailed and reliable dynamic monitoring information. And hydrological monitoring information is the basis of various types of information. Therefore, hydrological emergency monitoring must be carried out to obtain the information. This paper summarizes and puts forward the design of the high-risk barrier lake hydrological emergency monitoring system based on PDCA theory, which can provide support and guidance for the implementation of hydrological emergency monitoring in the future, and it has a strong practical significance. © Published under licence by IOP Publishing Ltd.

In 2015, China issued the "Guiding Opinions on Actively Promoting "Internet+" Actions", and implemented a top-level design for the implementation of the "Internet+" action plan for all walks of life. The essence of "Internet +" is connectivity, and it is a cross-border integration. This paper explores how to effectively integrate traditional Internet monitoring with Internet technologies such as mobile Internet, cloud computing, and big data to solve the "inefficient point" of traditional hydrological monitoring, and to achieve sustainable development of the hydrological industry and meet various economic and social fields. © Published under licence by IOP Publishing Ltd.

Space-Time Image Velocimetry (STIV) is a time-averaged velocity estimation method, which has been used for nonintrusive flow measurements from micro scale to large scale over the past decade. It takes a testing line as the Interrogation Area (IA), and detects the texture orientation of a generated Space-Time Image to determine the 1D velocity. Since STIV is superior to the Large-Scale Particle Image Velocimetry (LSPIV) in spatial resolution and time complexity, it has great potential in real-time monitoring of river flow. However, its practicality is still limited by the deficiencies of performance evaluation and sensitivity analysis due to its complexity and uncertainty. To simplify the detection of texture orientation in spatial domain, an FFT-STIV method was proposed based on Fast Fourier Transform, which detected the orientation of magnitude spectra in frequency domain. Then, a theoretical evaluation was provided, including measuring accuracy, measuring range and computational complexity. Finally, the sensitivities of image size, sampling rate, edge threshold, calibration accuracy, and tracing condition were analyzed based on a Rolling Painting Model (RPM). Results showed that the random errors of FFT-STIV could be controlled within +/- 5%, where the systematic error was about +/- 1%.

After the occurrence of the barrier lake, the rapid and effective development of hydrological emergency monitoring plays a key role in formulating emergency plans and reducing the losses caused by secondary disasters. This paper introduces the main characteristics of hydrological emergency monitoring of barrier lake, and the overall situation of emergency monitoring of 11.3 Baige Barrier Lake in Jinsha River in 2018. The scheme of hydrological emergency monitoring of barrier lake is designed, and two non-contact hydrological emergency monitoring methods based on radar and LSPIV technology are proposed according to the existing emergency monitoring methods of barrier lake. It has practical guiding significance for hydrological emergency monitoring of Barrier Lake.