A hydro-power generating system including an anchor adjacent to a river, a platform floating on the river, and an arm assembly connecting the anchor to the platform, the arm assembly including a plurality of arms connected together such that the level of the platform may vary directly with the level of the river. The pavement scanning system also includes at least one processor that resamples the multiple captured sequential images to compensate for difference in collection time and calculates surface gradient and albedo for each point on the pavement surface or directly uses the multiple images to detect surface features. The post has two outer post members pivotably attached to a center securing member. Also, in order to forward data to a specific group, the relay multicast system connects local multicast domains, in which it is possible to multicast or broadcast on a small scale as in a local area network or a company network in which multicast members of the group are included, without changing an existing 1:1 unicast based Internet infrastructure. A fourth step involves mutually comparing the subdivided sections of offset log to find a condition of best comparison therebetween and thereby generate one or more error terms.