Concepts and Applications of Backup Coverage
提出备份覆盖作为应急服务选址的决策标准，在经典覆盖模型中权衡首次覆盖与备份覆盖，并展示如何扩展到多次覆盖，通过实例说明可在不显著损失首次覆盖下提供大量备份覆盖。
Backup coverage, the second coverage of a demand node, is suggested as a decision criterion in modelling the location of emergency services on a network. The efficient handling of stochastic demand by vehicles which can respond to only one call at a time may require backup coverage in areas of high demand as a means to maintain a more uniform level of service. This new criterion is applied in the context of the classic covering models, the Location Set Covering Problem and the Maximal Covering Location Problem. First coverage as defined in these models is traded off against backup coverage in the present work. Other efforts which incorporate additional levels of coverage are reviewed. We also show how to extend these models to third as well as subsequent coverage. Based on an example problem we show that significant levels of backup coverage may possibly be provided within a system without substantial loss of first coverage.