Optimization off ishing operation for Danish seine gears by numerical analysis of fishing gear dynamics

本文建立了丹麦围网渔具在作业过程中的配置和张力分布的数值模拟方法。在实际试验中，测量了围网船的运行轨迹、经长、牵引速度等作业参数和网口深度、围网船与网之间的距离等齿轮运动参数。根据实测的运行参数，对丹麦围网网具的网形和张力分布进行了数值模拟，并将实测参数与计算参数进行了对比。在捕鱼作业期间围网的垂直和水平行为的测量和计算之间观察到非常好的一致性，证明了我们的方法的有效性。此外，还提出了利用经纱载荷和牵引速度来评价围网渔船上绞车的机械功的方法，以及利用从海底接收的齿轮摩擦力来评价对海底的物理冲击的方法。在不同拖期和相同拖距的两个试验中，比较了网片触底时绞车的计算机械功和对海底的物理冲击。绞车牵引周期短的机械功高于牵引周期长的机械功。但短期内对海底的物理冲击小于长期。

In this study a numerical simulation method of configuration and tension distribution for Danish seine gears during fishing operation was developed. Operation parameter such as tracks of a seine boat, warp lengths, and hauling speeds and gear movement parameter such as depths of the net mouth and distance between the seine boat and the net were measured in the actual experiments. The net configuration and tension distribution of the Danish seine gear were simulated by numerical simulations based on the measured operation parameter, and then the measured and the calculated parameters were compared. Very good agreement was observed between the measurements and the calculations of the vertical and horizontal behaviour of the seine net during fishing operations, demonstrating the validity of our method. In addition, methods of evaluating the mechanical work of the winches on the seine boat using loads of the warps and the hauling speed and of evaluating the physical impact to the sea bottom using friction force of the gear received from the sea bottom were developed. In two experiments of different hauling period and same towing distance when the net touched it at the sea bottom, the calculated mechanical works of the winches and physical impact to the sea bottom were compared. The mechanical work in the case of short hauling period of the winch was higher than that in the case of long hauling period. However, the physical impact to the bottom in the short period was lower than that in the long period.