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首页> 外文期刊>Fisheries and Aquatic Sciences >Fluttering Characteristics of the Ropes and Nets as an Active Stimulating Device inside the Cod End of a Trawl Net
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Fluttering Characteristics of the Ropes and Nets as an Active Stimulating Device inside the Cod End of a Trawl Net

机译：拖网鳕鱼端内部作为主动刺激装置的网和网的波动特性

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摘要

An active stimulating device (ASD) consisting of a net panel or ropes fluttering in the turbulence inside the cod end was effective in driving fish near the cod end to reduce juvenile by-catch. The fluttering characteristics of the rope and net panel were examined by video observations and analyzed for fluttering amplitude and period in a water channel and in field experiments with a bottom trawl. The amplitude ratio of the fluttering ropes or nets in the tank test increased with the fluttering index as the diameter of the twine, mesh size, flexibility, and flow velocity changed, whereas the period decreased with the above factors. In bottom trawl experiments, the range of mean depth difference in the fluttering net panel was 12-17% of the length of the fluttering net, and the period of depth difference or three-dimensional (3D) tilt was revealed, with shorter ones ranging from 2 to 6 s. The amplitude as depth difference and period from field measurements were similar to those of nets in tank experiments and also to the period of 3D flow velocity inside the cod end. These results could be used to design an ASD that could be used for to the cod end of actual towed fishing gear to reduce juvenile by-catch.
机译：主动刺激装置（ASD）由在鳕鱼端内部湍流中飘动的网状板或绳索组成，可有效驱使鳕鱼端附近的鱼类减少幼鱼的副渔获物。通过视频观察检查了绳索和网板的颤动特性，并分析了水道中的颤动幅度和周期以及在底部拖网的野外实验中的颤动幅度和周期。箱式试验中，振颤绳或网的振幅比随振颤指数的增加而增加，随着麻线直径，网眼尺寸，柔韧性和流速的变化，而周期因上述因素而缩短。在底拖网实验中，颤动网板中平均深度差的范围为颤动网长度的12-17％，显示出深度差或三维（3D）倾斜的周期，范围更短2至6 s。作为深度差的幅度和来自实地测量的周期与罐实验中的网的幅度相似，并且与鳕鱼端内部的3D流速周期相似。这些结果可用于设计ASD，该ASD可用于实际拖曳渔具的鳕鱼端，以减少幼鱼的副渔获物。

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