Mean current velocity measurement from a movable base

1994 ◽  
Vol 5 (5) ◽  
pp. 395-399
Author(s):  
N. P. Bulgakov ◽  
V. I. Remchukov ◽  
A. G. Evgushchenko
Keyword(s):  
Current Velocity ◽  
Velocity Measurement ◽  
Mean Current

The artificial object detection and current velocity measurement using SAR ocean surface images

2017 ◽  
Author(s):  
Valery V. Strotov ◽  
Boris A. Alpatov ◽  
Maxim D. Ershov ◽  
Vadim S. Muraviev ◽  
Alexander B. Feldman ◽  
...  
Keyword(s):  
Object Detection ◽  
Current Velocity ◽  
Velocity Measurement ◽  
Ocean Surface ◽  
Surface Images

Downstream and Lateral Transport of Nymphs of Two Mayfly Species (Ephemeroptera)

1983 ◽  
Vol 40 (11) ◽  
pp. 2025-2029 ◽  
Author(s):  
Jan J. H. Ciborowski
Keyword(s):  
Water Column ◽  
Velocity Gradient ◽  
Current Velocity ◽  
Lateral Transport ◽  
Cross River ◽  
Baetis Tricaudatus ◽  
Settling Behavior ◽  
Mean Current ◽  
Lateral Dispersal

By releasing live and dead nymphs of two mayfly species, Baetis tricaudatus Dodds and Ephemerella inermis Eaton, into the water column of a river and catching them downstream in a series of contiguous nets, I estimated settling and lateral dispersal rates. Live animals settled over shorter distances than dead individuals, and became more widely laterally dispersed for any given distance downstream and mean current velocity. Transport of suspended organisms in a river in which mean current velocity increases with increasing distance from shore may produce a skewed cross-river benthic distribution of animals. The degree of skewness will depend on the current velocity gradient and on suspended animals' settling behavior.

Influence of current velocity, density, and detritus on drift of two mayfly species (Ephemeroptera)

1983 ◽  
Vol 61 (1) ◽  
pp. 119-125 ◽  
Author(s):  
Jan J. H. Ciborowski
Keyword(s):  
Water Column ◽  
Linear Function ◽  
Current Velocity ◽  
Substantial Proportion ◽  
Positive Linear Function ◽  
Laboratory Streams ◽  
Indirect Consequence ◽  
Baetis Tricaudatus ◽  
Mean Current

Drift responses of Baetis tricaudatus Dodds and Ephemerella inermis Eaton larvae to manipulations of benthic density, sterile detritus, and current velocity were monitored in laboratory streams. The proportion of larvae departing from the substrate was independent of benthic density, amount of detritus, and interactions between these two variables. In spring, departure of larvae of both species was a positive linear function of current velocity during daylight hours. In darkness, departure of B. tricaudatus larvae became a negative linear function of current velocity. Nocturnal drift of E. inermis larvae was minimal at a mean current velocity of 25 cm∙s−1 and greater at both higher and lower velocities. None of the factors tested influenced departure of B. tricaudatus larvae in autumn experiments. Dead larvae were eroded from the substrate in much smaller proportions than were their live counterparts. This suggests that appearance in the water column of live animals is the direct or indirect consequence of individuals' behaviour. Departure of animals during daytime is largely passive in nature, whereas a substantial proportion of nocturnal drift probably results from active desertion of the substrate.

Optimum Swimming Speeds in Fish: The Problem of Currents

1980 ◽  
Vol 37 (7) ◽  
pp. 1086-1092 ◽  
Author(s):  
Clifford L. Trump ◽  
William C. Leggett
Keyword(s):  
Energy Expenditure ◽  
Swimming Speed ◽  
Current Velocity ◽  
Migration Behavior ◽  
Fish Swimming ◽  
Retrograde Motion ◽  
The Mean ◽  
The Relationship ◽  
Mean Current ◽  
A Current

A model is presented describing the energetic consequences of various behavioral responses to currents. To minimize the energy cost of migration, when confronted with currents, fish must optimize both the mean swimming speed and the degree to which swimming speed is altered in response to changes in current velocity. The optimum swimming speed in a current is U0 + 1/b where U0 = mean current speed and b is a constant in the equation E(t) = a ebW(t) describing the relationship between specific energy expenditure per unit time E(t) and swimming speed W(t). In a variable current, such as might occur in estuaries and coastal areas, energy expenditure is minimized when these variations are ignored and a constant speed through the water is maintained. This is true even in conditions where occasional retrograde motion over the bottom may occur. The added energy costs of swimming at mean speeds ≠ U0 + 1/b or of varying swimming speeds in response to changes in current velocity are rigorously defined. Predictions of the model are in general agreement with empirical data on fish swimming behavior.Key words: swimming speeds, currents, fish, theoretical ecology, mathematical models, energetics, migration, behavior

scholarly journals Using Orthogonal Combined Signals in Broadband ADCP for Improving Velocity Measurement

2020 ◽  
Vol 8 (6) ◽  
pp. 450
Author(s):  
Yujing Lin ◽  
Fei Yuan ◽  
En Cheng
Keyword(s):  
Current Velocity ◽  
Velocity Measurement ◽  
Water Environment ◽  
Acoustic Doppler Current Profiler ◽  
Processing Method ◽  
Velocity Measurements ◽  
Signal Parameters ◽  
Current Profiler ◽  
Signal Combination ◽  
Conventional Signal

Broadband Acoustic Doppler Current Profiler (BBADCP) is a widely used technology in velocity measurements. To adapt to the varied water environment and different measurement requirements, flexible tuning of transmitted signal parameters will improve the feasibility and accuracy of velocity measurement. Compared with the conventional signal, the orthogonal combined signal designed in this paper can generate a wealth of signal combination examples and improve the accuracy of the velocity measurement under the same conditions. The proposed orthogonal combined signal consists of two orthogonal sub-signals with a symmetrical spectrum. Each is designed based on time delay to eliminate or weaken the current velocity ambiguity. Then, the processing method of the received signal when the pulse signals are the same or different coded signal is discussed. The numerical simulation results show that, when using the proposed method, the standard deviation of the estimated current velocity has different degrees of reduction at different current velocities. Our simulation also shows that, compared to the convention method, the proposed method can improve the SNR by 10 dB. This can help significantly increase the scope of the configuration.

Particle velocity measurement in powder gas jets of coaxial powder nozzles for laser material deposition

2021 ◽  
Vol 33 (1) ◽  
pp. 012019
Author(s):  
Jonathan Schaible ◽  
Luis Andrea Hau ◽  
David Weber ◽  
Thomas Schopphoven ◽  
Constantin Häfner ◽  
...  
Keyword(s):  
Particle Velocity ◽  
Velocity Measurement ◽  
Laser Material ◽  
Gas Jets ◽  
Material Deposition ◽  
Particle Velocity Measurement
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