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Copyright of Railway Investigation & Surveying is the property of Railway Investigation & Surveying Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ordnance Industry Automation is the property of Editorial Board for Ordnance Industry Automation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrographic Surveying & Charting / Haiyang Cehui is the property of Hydrographic Surveying & Charting Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Neck cutoff as an extreme geomorphic process, occurred in flood season of July 2018 in the lower Black River in the Yellow River Source region. Neck cutoff strongly adjusting flow structure is of great importance to understand the hydrodynamic mechanism of meander cutoff. Acoustic Doppler Current Profiler (ADCP) was used to conduct field measurements on a total of 45 cross-sections in May 2019 and August 2020 in order to compare and analyze three- dimensional flow structure in different cross sections. Results demonstrated that due to the influence of channel shape, boundary conditions, hydrological conditions and other factors, the flow structure in the upstream straight reach is less affected by the neck cutoff, while the flow structure of the bend section is obviously adjusted after neck cutoff. The specific performance is that the neck cutoff has little effect on the spatial distribution of velocity and circulation intensity in the straight reach. It will change the transverse distribution of the maximum velocity at the top of the bend and the section distribution of circulation structure, and affect the scale and distribution position of the separation area. The results also deepen the understanding of the impact of flow structure adjustment after neck cutoff on deposition of oxbow lake, scouring and depositing of riverbed in separation area and scouring of new channel. [ABSTRACT FROM AUTHOR]

Bend flow structure plays an important role in the evolution of natural river morphology. In order to further deepen the understanding of circulation structures and turbulence characteristics in the bends. Taking the continuous bend in Huanghuacheng reach of the Three Gorges Reservoir area as the research object, Acoustic Doppler Current Profiler(ADCP) was used to carry out prototype three-dimensional instantaneous velocity measurements. Scale distribution characteristics of bend circulation structures and turbulence structures were further analyzed. Results show the presence of macro- scale channel circulation structures in the Huanghuacheng reach. Due to the influence of local backwater and riverbed topography, measured vertical lines were characterized by full- depth circulation structure or double- circulation structure. Very large-scale turbulence structures still exist in the continuous curved rivers of the reservoir area, but their scale and distribution are greatly affected by the curved circulation structures. [ABSTRACT FROM AUTHOR]

Copyright of Hydrographic Surveying & Charting / Haiyang Cehui is the property of Hydrographic Surveying & Charting Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrographic Surveying & Charting / Haiyang Cehui is the property of Hydrographic Surveying & Charting Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Influenced by external magnetic interference, bottom tracking bias due to bedload movement and instrument precision, the accurate azimuth and reference of boat velocity are difficult to establish and even incorrect when measured by a acoustic Doppler current profiler (ADCP), which causes ADCP flow measurement to be invalid and thus limit ADCP application. To overcome the shortcomings of the traditional ADCP measurement, this paper puts forward a new method of high-accuracy ADCP measurement by means of an external sensor array. The assignment of the external sensors such as GPS compass array or fiber optic gyrocompass was studied and the resettlement program determined. Calculation models for parameters such as the installation error of ADCP transducer, the attitude parameters (roll, pitch and heading) of vessel, the absolute vessel velocity and the azimuth of ADCP transducer are provided. Based on these parameters in reference to the ADCP measurement principles, a set of new models for determining ADCP flow velocity by replacing the absolute vessel velocity, azimuth and attitude provided by ADCP with those provided by the external sensors were developed. The proposed method and models are validated by an experiment conducted on the Yangtze Estuary. These experimental results show that this proposed method improves the accuracy of the measurement of flow velocity, and enhances the range of applications for ADCP measurement. [ABSTRACT FROM AUTHOR]