A fixed net method to determine the vertical migration of plankton

The use of water-saving irrigation techniques has been encouraged in rice fields in response to irrigation water scarcity. Straw return is an important means of straw reuse. However, the environmental impact of this technology, e.g., nitrogen leaching loss, must be further explored. A two-year (2017–2018) experiment was conducted to investigate the vertical migration and leaching of nitrogen in paddy fields under water-saving and straw return conditions. Treatments included traditional flood irrigation (FI) and two water-saving irrigation regimes: rain-catching and controlled irrigation (RC-CI) and drought planting with straw mulching (DP-SM). RC-CI and DP-SM both significantly decreased the irrigation input compared with FI. RC-CI increased the rice yield by 8.23%~12.26%, while DP-SM decreased it by 8.98%~15.24% compared with FI. NH4+-N was the main form of the nitrogen leaching loss in percolation water, occupying 49.06%~50.97% of TN leaching losses. The NH4+-N and TN concentration showed a decreasing trend from top to bottom in soil water of 0~54 cm depth, while the concentration of NO3−-N presented the opposite behavior. The TN and NH4+-N concentrations in percolation water of RC-CI during most of the rice growth stage were the highest among treatments in both years, and DP-SM showed a trend of decreasing TN and NH4+-N concentrations. The NO3−-N concentrations in percolation water showed a regular pattern of DP-SM > RC-CI > FI during most of the rice growth stage. RC-CI and DP-SM remarkably reduced the amount of N leaching losses compared to FI as a result of the significant decrease of percolation water volumes. The tillering and jointing-booting stages were the two critical periods of N leaching (accounted for 74.85%~86.26% of N leaching losses). Great promotion potential of RC-CI and DP-SM exists in the lower reaches of the Yangtze River, China, and DP-SM needs to be further optimized.

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Diel, lunar and seasonal vertical migration in the deep western Gulf of Mexico evidenced from a long-term data series of acoustic backscatter

Progress In Oceanography ◽

10.1016/j.pocean.2021.102562 ◽

2021 ◽

pp. 102562

Author(s):

Laura Ursella ◽

Sara Pensieri ◽

Enric Pallàs-Sanz ◽

Sharon Z. Herzka ◽

Roberto Bozzano ◽

...

Keyword(s):

Gulf Of Mexico ◽

Vertical Migration ◽

Acoustic Backscatter ◽

Data Series ◽

Term Data

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Sparse damage detection via the elastic net method using modal data

Structural Health Monitoring ◽

10.1177/14759217211021938 ◽

2021 ◽

pp. 147592172110219

Author(s):

Rongrong Hou ◽

Xiaoyou Wang ◽

Yong Xia

Keyword(s):

Damage Detection ◽

Structural Damage ◽

Damage Identification ◽

Measurement Data ◽

Elastic Net ◽

Sensitivity Matrix ◽

Regularization Technique ◽

Modal Data ◽

Regularization Techniques ◽

Net Method

The l1 regularization technique has been developed for damage detection by utilizing the sparsity feature of structural damage. However, the sensitivity matrix in the damage identification exhibits a strong correlation structure, which does not suffice the independency criteria of the l1 regularization technique. This study employs the elastic net method to solve the problem by combining the l1 and l2 regularization techniques. Moreover, the proposed method enables the grouped structural damage being identified simultaneously, whereas the l1 regularization cannot. A numerical cantilever beam and an experimental three-story frame are utilized to demonstrate the effectiveness of the proposed method. The results showed that the proposed method is able to accurately locate and quantify the single and multiple damages, even when the number of measurement data is much less than the number of elements. In particular, the present elastic net technique can detect the grouped damaged elements accurately, whilst the l1 regularization method cannot.

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Diel vertical migration of mesozooplankton in the northern Yellow Sea

Journal of Oceanology and Limnology ◽

10.1007/s00343-020-0170-y ◽

2021 ◽

Author(s):

Ruping Ge ◽

Hongju Chen ◽

Guangxing Liu ◽

Yanzhong Zhu ◽

Qiang Jiang

Keyword(s):

Vertical Migration ◽

Yellow Sea ◽

Diel Vertical Migration ◽

Northern Yellow Sea

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Online size distribution measurement of dense iron green pellets using an efficient and multiscale nested U-net method

Powder Technology ◽

10.1016/j.powtec.2021.04.045 ◽

2021 ◽

Vol 387 ◽

pp. 584-600

Author(s):

Xin Wu ◽

Xiaoyan Liu ◽

Jiaxu Duan

Keyword(s):

Size Distribution ◽

Distribution Measurement ◽

Net Method

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VERTICAL MIGRATION OF EUGLENA SP. ON THE SAND BANKS OF A NORTH CAROLINA PIEDMONT STREAM

Journal of Phycology ◽

10.1046/j.1529-8817.1999.00001-109.x ◽

2000 ◽

Vol 36 (s3) ◽

pp. 36-37

Author(s):

Kingston

Keyword(s):

North Carolina ◽

Vertical Migration ◽

North Carolina Piedmont

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Role of large-scale advection and small-scale turbulence on vertical migration of gyrotactic swimmers

Physical Review Fluids ◽

10.1103/physrevfluids.4.124304 ◽

2019 ◽

Vol 4 (12) ◽

Author(s):

C. Marchioli ◽

H. Bhatia ◽

G. Sardina ◽

L. Brandt ◽

A. Soldati

Keyword(s):

Vertical Migration ◽

Large Scale ◽

Small Scale ◽

Scale Turbulence

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A laboratory study of vertical migration

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1955.0062 ◽

1955 ◽

Vol 144 (916) ◽

pp. 329-354 ◽

Cited By ~ 24

Keyword(s):

Light Intensity ◽

Vertical Migration ◽

Time Course ◽

Tap Water ◽

Low Light ◽

Overhead Light ◽

Light Intensities ◽

Orientation Response ◽

Reduced Light ◽

Characteristic Maximum

In a tank filled with a suspension of indian ink in tap water, a population of Daphnia magna will undergo a complete cycle of vertical migration when an overhead light source is cyclically varied in intensity. A ‘dawn rise’ to the surface at low intensity is followed by the descent of the animals to a characteristic maximum depth. The animals rise to the surface again as the light decreases, and finally show a typical midnight sinking. The light intensities at the level of the animals in this experiment are of the same order as those which have been reported in field observations; the time course of the movement also repeats the natural conditions in the field. The process is independent of the duration of the cycle and is related only to the variation in overhead light intensity. At low light intensity the movement of the animal is determined solely by positive photo-kinesis; the dawn rise is a manifestation of this, and is independent of the direction of the light. At high light intensities there is an orientation response which is superimposed upon an alternating positive (photokinetic) phase and a negative phase during which movement is inhibited. The fully oriented animal shows a special type of positive and negative phototaxis, moving towards the light at reduced light intensities and away from it when the light intensity is increased. In this condition it follows a zone of optimum light intensity with some exactness. Experiments show that an animal in this fully oriented condition will respond to the slow changes of intensity characteristic of the diurnal cycle, while being little affected by transient changes of considerable magnitude.

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