Workload balancing on identical parallel machines is concerned with the assignment of a set of jobs with positive integer processing times to a set of identical parallel machines so that a prespecified balancing criterion is optimized. A wellestablished criterion is the normalized sum of squared workload deviations (NSSWD) which has been proposed by Ho et al. (2009).
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Ho, J.C.; Tseng, T.L.B.; RuizTorres, A.J.; López, F.J. (2009): Minimizing the normalized sum of square for workload deviations on m parallel processors. Computers & Industrial Engineering 56, 186–192.