Shipping problems with body clock constraints

Time window has been a common form of time constraint considered in the literature. Basically, a time window is a time period, defined by the earliest and latest times, when a node is available for traveling through. Although many variants of transportation problem in time-window networks have been proposed, no one consider the possibility that time windows may be associated with the moving travelers or vehicles so that they can travel only in these time periods. In this paper, this new variant of time-window constraint, called body clock constraint, is proposed. We assume that each vehicle has its own body clock and a capacity limitation for carrying goods, and we are requested to determine a minimal time schedule for sending a certain amount of goods from source to destination in a time-window network. Specifically, the problem is studied in two cases, where the first case considers single-vehicle scheduling and the second multiple vehicles. For both of them, algorithms are presented to find the optimum schedule.