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SECHHyperbolic Secant
SECHScreened Exchange Plus Coulomb Hole Method
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TABLE 1: RK4 sech (x) solution of the NLSE, (29), computed at x = 1.
Pulse wings exhibit some wiggles around [[xi].sub.0] = [pi]/2 (after one soliton period), but asymptotically the shape is not much different from a chirped sech again at least in its central part.
Equating the exponents and the coefficients of each pair of the sech functions, we find
[[rho].sub.1] (t) = [+ or -] [cube root of 2w/[sigma]] [9/11 sech (t [square root of [[OMEGA].sub.1]]) + 2/11 [sech.sup.3] (t [square root of [[OMEGA].sub.1]]) .
Efficiency Change, pech = Pure Efficiency Change, sech = Scale
v (x, y, t) = [alpha + [eta] + [omega]/6[mu] - sech (kx + vy + [omega]t) + 3 (k[alpha] + 8k[mu] + 2[mu][omega])/[alpha](3k + [omega]) [sech.sup.2] (kx + vy + [omega]t).
Since both (PECH) and (SECH) are positive and greater than unity, depict improvements in efficiency of trap fishing for small boats at north Gulf.
Technical efficiency (TE), pure technical efficiency (PTE), scale efficiency (SE), total factor productivity change index (TFPCH), technical efficiency change index (EFFCH), technological change index (TECHCH), pure efficiency change index (PECH) and scale efficiency change index (SECH).
From the Taylor's series expansion of sech z we have sech z [is greater than or equal to] 1 - (1/2)[z.sup.2].
= [a.sub.0] [e.sup.-at]/1 + [e.sup.-2at] = [a.sub.0]/2 2/[] + [e.sup.-at] = [a.sub.0] sech (-at) (1)