A Comprehensive Study of Gridding Methods for GPS Horizontal Velocity Fields

Mapping small-scale high-precision velocity fields is of great significance to oceanic environment research. Coastal acoustic tomography (CAT) is a frontier technology used to observe large-scale velocity field in the horizontal slice. Nonetheless, it is difficult to observe the velocity field using the CAT in small-scale areas, specifically where the flow field is complex such as ocean ranch and artificial upwelling areas. This paper conducted a sound transmission experiment using four 50 kHz CAT systems in the Panzhinan waterway. Notably, sound transmission based on the round-robin method was recommended for small-scale CAT observation. The travel time between stations, obtained by correlation of raw data, was applied to reconstruct the horizontal velocity fields using Tapered Least Square inversion. The minimum net volume transport was 8.7 m3/s at 12:32, 1.63% of the total inflow volume transport indicating that the observational errors were acceptable. The relative errors of the range-average velocity calculated by differential travel time were 1.54% (path 2) and 0.92% (path 6), respectively. Moreover, the inversion velocity root-mean-square errors (RMSEs) were 0.5163, 0.1494, 0.2103, 0.2804 and 0.2817 m/s for paths 1, 2, 3, 4 and 6, respectively. The feasibility and acceptable accuracy of the CAT method in the small-scale velocity profiling measurement were validated. Furthermore, a three-dimensional (3-D) velocity field mapping should be performed with combined analysis in horizontal and vertical slices.

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Taiwan Semi-kinematic Reference Frame Based on Surface Deformation Model Derived from GNSS Data, 2003 to 2019

10.5194/egusphere-egu2020-1922 ◽

2020 ◽

Author(s):

Kwo-Hwa Chen ◽

Kuo-En Ching ◽

Ray Y. Chuang ◽

Ming Yang ◽

He-Chin Chen

Keyword(s):

Coordinate System ◽

Reference Frame ◽

Surface Deformation ◽

Interpolation Method ◽

Velocity Model ◽

Velocity Fields ◽

Horizontal Velocity ◽

Dislocation Model ◽

Deformation Model ◽

Velocity Models

<p>Taiwan&#8217;s current horizontal coordinate system, TWD97[2010], is a static geodetic datum located at the boundary between Eurasian and Philippine Sea plates. Due to the relative motions between different plates, the accuracy of TWD97[2010] has been constantly decreasing. To maintain the internal accuracy of a national coordinate system at a high level, establishing a semi-kinematic reference frame is a practical solution. The semi-kinematic reference frame includes a static datum and a surface deformation model that is composed of velocity grid models and displacement grid models. In this study, observations of 437 continuous GNSS stations from January 2003 to December 2019 were adopted to estimate the horizontal velocity fields in Taiwan. We also integrated twelve horizontal velocity fields between 2003 and 2018 from 785 campaign-mode GNSS sites surveyed by the Central Geological Survey to derive the horizontal grid velocity models using the Kriging spatial interpolation method. Six coseismic displacement grid models from 2010 to 2018 were constructed using the dislocation model based on published coseismic source models. Independent GNSS observations of 1400 stations collected by the National Land Surveying and Mapping Center (NLSC) between 2013 and 2018 were also used for exterior checking on the accuracy of the surface deformation model. In addition, the network-based RTK system in Taiwan established by NLSC, named e-GNSS, is proposed to be used for assessing the accuracy of the velocity model and for the decision on the timing of velocity model renewal.</p>

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Assessment of horizontal velocity fields in square thermal convection cells with large aspect ratio

Experiments in Fluids ◽

10.1007/s00348-018-2626-9 ◽

2018 ◽

Vol 59 (11) ◽

Cited By ~ 3

Author(s):

Christian Kästner ◽

Christian Resagk ◽

Jasper Westphalen ◽

Manuela Junghähnel ◽

Christian Cierpka ◽

...

Keyword(s):

Aspect Ratio ◽

Thermal Convection ◽

Velocity Fields ◽

Horizontal Velocity ◽

Large Aspect Ratio

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Rotational Field and Velocity Dispersion in Globular Clusters: ω CEN and 47 TUC

Symposium - International Astronomical Union ◽

10.1017/s0074180900147291 ◽

1985 ◽

Vol 113 ◽

pp. 93-96

Author(s):

G. Meylan ◽

M. Mayor

Keyword(s):

Globular Clusters ◽

Virial Theorem ◽

Velocity Dispersion ◽

Rotational Velocity ◽

Velocity Fields ◽

Velocity Measurements ◽

Spatial Velocity ◽

Rotational Field ◽

Random Motions ◽

Comprehensive Study

Thanks to numerous and accurate radial velocity measurements obtained with CORAVEL, the rotational velocity fields, the spatial velocity dispersions from the centre to the edge and the ordered to random motions ratios are deduced for two globular clusters: ω Cen and 47 Tuc. Masses through virial theorem and M/L ratios are also given. A more comprehensive study will be published in Astron. & Astrophys.

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Multi-scale deep learning for estimating horizontal velocity fields on the solar surface

Astronomy and Astrophysics ◽

10.1051/0004-6361/202141743 ◽

2021 ◽

Author(s):

R. T. Ishikawa ◽

M. Nakata ◽

Y. Katsukawa ◽

Y. Masada ◽

T. L. Riethmüller

Keyword(s):

Deep Learning ◽

Solar Surface ◽

Velocity Fields ◽

Horizontal Velocity ◽

Multi Scale

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MODELLING OF PLANFORM INFLUENCE ON CIRCULATION IN HARBOURS

Coastal Engineering Proceedings ◽

10.9753/icce.v17.161 ◽

1980 ◽

Vol 1 (17) ◽

pp. 161

Author(s):

Roger A. Falconer

Keyword(s):

Numerical Solutions ◽

Velocity Fields ◽

General Nature ◽

Laboratory Model ◽

Model Studies ◽

Tidal Water ◽

Tidal Velocity ◽

Mean Water Level ◽

Water Elevations ◽

Comprehensive Study

A two dimensional numerical model has been developed which is capable of predicting the tidal water elevations, depth averaged velocity components and horizontal concentration distributions in narrow entranced harbours and marinas. Particular attention has been paid to the numerical treatment of the convective accelerations where, as a result of narrow harbour entrances and the general nature of planform geometries, the resulting highly non-uniform flow fields can readily lead to nonlinear instabilities and unstable numerical solutions. In order to check the validity of the numerical results, a comprehensive study was carried out to compare, with scaled laboratory model studies, the predicted tidal velocity fields and flushing characteristics for a number of rectangular harbours of constant planform area but different length to breadth ratios. The experimentally measured average per cycle exchange coefficients and the observed mean water level pathlines agreed reasonably well with the corresponding numerically predicted exchange coefficients and depth averaged velocity fields. The results of both the numerical and laboratory model studies confirmed conclusively that the maximum gross flushing characteristics occurred within a rectangular harbour when the length to breadth ratio was close to unity. Also, further tests showed that the insertion of impermeable barriers as a possible means of increasing the flushing efficiency proved to be unsatisfactory.

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Correlation between ore particle flow pattern and velocity field through multiple drawpoints under the influence of a flexible barrier

Open Geosciences ◽

10.1515/geo-2019-0043 ◽

2019 ◽

Vol 11 (1) ◽

pp. 533-541

Author(s):

Shikang Qin ◽

Qingfa Chen ◽

Qinglin Chen ◽

Fuyu Zhao

Keyword(s):

Vertical Velocity ◽

Side Wall ◽

Particle Method ◽

Velocity Fields ◽

Horizontal Velocity ◽

Particle Flow ◽

Flow Properties ◽

Flexible Barrier ◽

Velocity Equation ◽

The Relationship

Abstract By means of similar tests, the stope room is scaled and the process of multiple-drawpoint ore drawing under the influence of a flexible barrier is simulated by the marking particle method. Based on the experimental phenomena and data, the shape of the barrier, the draw column, and the numerical relations for the discharge between each drawpoint are analysed. The velocity equation for ore particles flowing through multiple drawpoints is established and the relationship between ore particle flow properties and velocity fields is found. Finally, the following results are derived: 1) For each layer, the morphology of marked particles is similar to that of vertical velocity. The particles are quasi-linear in the upper part of the model and wavy in the lower part. The amplitude increases with decreasing height. 2) The distribution of thirteen concentric points of horizontal velocity in each layer illustrate that the ore particles drawn from each drawpoint are from the centreline between it and the adjacent drawpoint. 3) The barrier and the marked particles are at the lowest sag points at the top of the number two and number six drawpoints (close to the model’s side wall) because of the combination of vertical velocity and horizontal velocity.

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VELOCITY FIELDS IN THE WAVE BKsAKka ZONK

Coastal Engineering Proceedings ◽

10.9753/icce.v12.27 ◽

1970 ◽

Vol 1 (12) ◽

pp. 27 ◽

Cited By ~ 3

Author(s):

M.D. Adeyemo

Keyword(s):

Velocity Fields ◽

Horizontal Velocity ◽

Velocity Measurements ◽

Time Asymmetry ◽

Qualitative And Quantitative ◽

Quantitative Correlation ◽

Velocity Magnitude ◽

History Of ◽

The Asymmetry ◽

Spilling Breakers

The paper deals with the velocity fields in the neighbourhood of the breakers and the correlation between the wave asymmetry and the velocity asymmetry. The velocity measurements were made on two beach slopes 1 9 and 1.18. Earlier work (3) showed that the two slopes produced different breaker types; the slope of 1:9 produced plunging breakers and the slope of 1 18 spilling breakers. The velocities (velocity - tune history) of the water particles were measured at a height of 5mm above the bed using the hydrogen bubble method combined with cine photography. Two types of horizontal velocity asymmetry were defined and investigated, namely (1) horizontal velocity (Magnitude) asymmetry and (2) horizontal velocity (time) asymmetry. It was found that there are both qualitative and quantitative correlation between the asymmetry of the wave, and the asymmetry of the resulting velocity field. As a result of the correlation two alternative expressions are given for the horizontal velocity (magnitude) asymmetry.

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