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<br />. <br /> <br />A pure network algorithm does not directly allow for system <br />gains or losses as a function of flow or storage in the system. <br />Jensen and Barnes (1980) developed a "network with gains" <br />minimum cost flow algorithm which is able to directly account <br />for channel losses as a function of flow rate. Computational <br />experience shows that computer processing time is about two <br />to three times that of a pure network algorithm. Since return <br />flows, stream depletions and reservoir evaporation must still <br />be computed by an iterative process on the pure network, it <br />was concluded that it is more efficient to include channel loss <br />in the iterative process and be able to use the faster pure <br />network algorithm. <br /> <br />Pure network optimization techniques are particularly <br />efficient procedures for the microcomputer since most <br />calculations are integer-based rather than requiring more time <br />consuming real number computations as in standard linear <br />programming codes using the revised simplex method. This <br />greatly facilitates the speed of MODSIM and the ability to <br />run it successfully on lower accuracy microcomputers. <br /> <br />Computation may begin with infeasible solutions, unlike linear <br />programming algorithms that require an imitialization <br />procedure for fmding feasibile solutions. <br /> <br />Extremely large (in terms of network components) problems <br />can be solved. Since network algorithms are so efficient, it <br />becomes feasible to perform many iteration so as to consider <br />certain nonlinear or dynamic system features. <br /> <br />Changes in system components can be easily incorporated by <br />manipulation of the previously constructed network. <br /> <br />It is believed that a major advantage in application of <br />MODSIM to a water supply system will be to facilitate a <br />totally integrated management approach which can also foster <br />better coordination with other water users in the region. <br /> <br />6 <br />