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Abstract: Variational problem for irrotational, incompressible inviseid fluid in finite water depth is considered. Based on the variational principle, a special solution of the problem is presented under the assumption that the dispersion μ and the nonlinearity ε satisfied ε=O(μ2) as the Lagrange function is expanded up toO(μ8). It is shown that the elevation of the free surface should be expanded to μ4 order to ensure the Lagrange function is in μ8 order. Comparison the nonlinear free surface profiles obtained from the solution with the corresponding ones obtained from linear solutions showed that the wave crest of the nonlinear wave is steepened but the trough is flattened compared to the linear wave as expected.

A series of four block copolymers based on aromatic acetoxy-polysulphone (Ac-PSF), terephthalic acid (TPA), m-phthalic acid (MPA), acetoxy-benzoic acid (Ac-HBA), and a di(acetoxy)bisphenol monomer were synthesized. Their structures were determined by IR, thermal mechanical analyses and solubility tests. They all exhibit liquid crystalline behaviour.