Seasonal velocity variations over the entire Kuroshio path part II: dynamical interpretation for the current speed variation

2021 ◽  
Author(s):  
Zhen-Long Zhang ◽  
Hirohiko Nakamura ◽  
Xiao-Hua Zhu
Keyword(s):  
Current Speed ◽  
Speed Variation ◽  
Kuroshio Path ◽  
Velocity Variations ◽  
Dynamical Interpretation

A case study of wear-type rail corrugation prediction and control using speed variation

2009 ◽  
Vol 325 (1-2) ◽  
pp. 85-105 ◽  
Author(s):  
P.A. Meehan ◽  
P.A. Bellette ◽  
R.D. Batten ◽  
W.J.T. Daniel ◽  
R.J. Horwood
Keyword(s):  
Rail Corrugation ◽  
Speed Variation ◽  
Prediction And Control ◽  
And Control

scholarly journals Effect of Cutting Ratio and Catch on Drag Characteristics and Fluttering Motions of Midwater Trawl Codend

2021 ◽  
Vol 9 (3) ◽  
pp. 256
Author(s):  
Wei Liu ◽  
Hao Tang ◽  
Xinxing You ◽  
Shuchuang Dong ◽  
Liuxiong Xu ◽  
...  
Keyword(s):  
Drag Force ◽  
Mesh Size ◽  
Current Speed ◽  
Midwater Trawl ◽  
Minimum Drag ◽  
Fish Catch ◽  
Spatial Geometry ◽  
By Catch ◽  
Trawl Fisheries ◽  
Crucial Part

The codend of a trawl net is the rearmost and crucial part of the net for selective fish catch and juvenile escape. To ensure efficient and sustainable midwater trawl fisheries, it is essential to better understand the drag characteristics and fluttering motions of a midwater trawl codend. These are generally affected by catch, cutting ratio, mesh size, and twine diameter. In this study, six nylon codend models with different cutting ratios (no cutting, 6:1, 5:1, 4:1, 7:2, and 3:1) were designed and tested in a professional flume tank under two conditions (empty codends and codends with catch) and five current speeds to obtain the drag force, spatial geometry, and movement trend. As the cutting ratio of empty codends decreased, the drag force decreased, and the drag coefficient increased. The unfolding degree of codend netting and the height of empty codends were found to be directly proportional to the current speed and inversely proportional to the cutting ratio. The positional amplitude of codend with cutting ratio 4:1 was the smallest for catch. The drag force of codends with catch increased as the current speed increased, and first decreased and then increased as the cutting ratio decreased. To ensure the best stability and minimum drag force of the codend, it is recommended to use the 4:1 cutting ratio codend.

scholarly journals Physics-Based Relationship for Pore Pressure and Vertical Stress Monitoring Using Seismic Velocity Variations

2021 ◽  
Vol 13 (14) ◽  
pp. 2684
Author(s):  
Eldert Fokker ◽  
Elmer Ruigrok ◽  
Rhys Hawkins ◽  
Jeannot Trampert
Keyword(s):  
Pore Pressure ◽  
Seismic Velocity ◽  
Pressure Head ◽  
Groundwater Table ◽  
Surface Velocity ◽  
Seismic Velocities ◽  
Stress Monitoring ◽  
Near Surface ◽  
Velocity Variations ◽  
Velocity Changes

Previous studies examining the relationship between the groundwater table and seismic velocities have been guided by empirical relationships only. Here, we develop a physics-based model relating fluctuations in groundwater table and pore pressure with seismic velocity variations through changes in effective stress. This model justifies the use of seismic velocity variations for monitoring of the pore pressure. Using a subset of the Groningen seismic network, near-surface velocity changes are estimated over a four-year period, using passive image interferometry. The same velocity changes are predicted by applying the newly derived theory to pressure-head recordings. It is demonstrated that the theory provides a close match of the observed seismic velocity changes.

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