1990 Fiscal Year Final Research Report Summary
Study on the Control Performance of Midwater Trawl Net
| Project/Area Number |
01560202
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
General fisheries
|
|---|
| Research Institution | Tokyo University of Fisheries |
|---|
Principal Investigator |
MATUDA Ko Tokyo UniV. Fish. Fisheries, Professor, 水産学部, 教授 (90026485)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
SATO Kaname Tokyo Univ. Fish. Fisheries, Professor, 水産学部, 教授 (20017073)
|
|---|
| Project Period (FY) |
1989 – 1990
|
| Keywords | Midwater trawl / Control performance / Canvas type midwater trawl / Dynamic control / Autoregressive model / Monte-Carlo simulation / Otter board / Wing parakite |
|---|
| Research Abstract |
A study to develop a midwater trawl system which is highly controllable was conducted. Three approaches were made to conduct the study namely ; flume experiment, field experiment and theoretical analysis.
The flume experiment was conducted to clarity the performance of the midwater trawl net using a new net-mouth opening device made of canvas by comparing its static and dynamic characteristics to that of the otter type. It was observed that the canvas type midwater trawl net was suited to low speed towing because its mouth opening area relative to the total drag of the gear was high at low speed. The control performance of both types of midwater trawl based on the working depth was compared by changing the current speed. The result showed that the time required to control the working depth at the same floating or sinking distance was shorter for the canvas type than the otter type.
The field experiment was conducted on board the R/V Shinyo-maru of Tokyo University of Fisheries at Wakasa
… More
Bay in Japan Sea in 1989 and 1990. The time series data of the working depth of the net, the height of the net-mouth, the wing spread, the tension fo the bridle, the depth of the otter boards, etc. were observed at variable towing speed and warp length.
The theoretical analysis was done by designing an experimental formula for calculating the net drag of the midwater trawl. The theoretical analysis was based on the midwater trawl system of the R/V Shinyo-maru. Good agreement was obtained between the experimental and the theoretical results.
Lastly, an autoregressive model to estimate the dynamic behavior of midwater trawl system by varying the towing speed was built and unknown parameters in the model were determined. The validity of the present model was statistically proven. A computer simulation was made on the model to compare it with the results of the field experiment. Similar characteristics of the dynamic behavior of the midwater trawl system for the model and the field experiment was obtained. Less
|
