Mechanical properties of a rectangular purse seine in a special operation.

概要

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The mechanical properties with factors of forces (tension; F and drag; D), velocity (v)and distanc (s), in a special operation were studied. The special operation was done at both the pursing and the hauling stage by pulling one end of the purse line while fixing the other end. The mechanical properties at the equilibrium condition of the force were expressed as follows: in the pursing stage (suffix “1”) as; η1=e-2πμ1, F1=Fω cos⊗1, D1=2πη1Fω cos ⊗1, v1=(Vωcos⊗1)/(2πη1) and S1=(Vωcos⊗1/2πη1)t, where ⊗1=sin-1(W/Fω), and in the hauling stage (suffix “2”), in cas ⊗2=π/2, as;η2=(1+e-πμ2)/2, F2=Fω, D2=2πη2Fω-W, v2=Vω/(2η2)and s2=(Vω/2η2)(t-t1), where ⊗2=sin-1 {(D2+W)/Fω}. η1 and η2 are the mechanical efficiencies between the purse line and the ring, μ1 and μ2 are the kinetic friction coefficients between the purse line and the ring, Fω is the tension of the winch, W is the weight in water of the fishing gear, Vω is the velocity of the winch, and t1 and t2 are the time lapses during the fishing operations. If μi, μ2, Fω, W, Vω, t1 and t2 are given as known constants, each factor of the mechanical properties can be calculated.