Location And Allocation Optimization Of Collaborative Fire Emergency Facilities Under Hypercube Queuing Equilibrium

With the acceleration of urbanization in China,urban disasters such as high-rise residential fires,personnel-intensive fires and leakage of dangerous chemicals have become more frequent.In addition,the scale of disasters and the degree of difficulty of rescue have increased.In view of the lack of research on the key technologies such as the strategic layout of fire emergency resources in China and the lack of scientific and effective optimization methods for resource allocation,this paper carries out fire risk assessment of urban fire disasters,response mechanisms analysis of Chinese urban fire emergency service,fire station locations under cooperative rescue and partial coverage,fire vehicle allocation optimization under hypercube queuing equilibrium,and integrated optimization of fire emergency resources location and allocation problem.Based on the Fine Kinney risk assessment theory and the Dematel risk assessment theory,a framework for urban fire disaster risk assessment is established.By assessing the similarity of disaster types,environmental exposure of the disaster and the consequences of disasters,the urban fire disaster risk assessment model is proposed,and the disaster risk assessment level is finalized.Taking a large shopping mall building in Harbin as a research object,the fire risk index and fire risk rating are then evaluated.In the analysis of the urban fire emergency service response mechanisms,three factors including the classification response mechanism,the graded response mechanism and the nearest dispatch mechanism are summarized and elaborated.Based on these mechanisms and the gradual coverage theory for facility location,the partial coverage constraints on vehicle-quantity and vehicle distance considerations,as well as the vehicle cooperative rescue constraint,are proposed.The fire station strategic location model under these mechanisms is constructed and applied to a small-scale network.The results show that the model can calculate the collaborative partial coverage of different levels and types of demands by urban fire resource.Considering the uncertainties of fire emergency service resources,the hypercube queuing model is introduced into the vehicle deployment optimization model under China's fire emergency response mechanism.By relaxing some constraints of the classical hypercube queuing model,a more general form is proposed,namely a hypercube spatial queuing equalization model that is suitable for vehicle coordination modes.The sensitivity analyses on demand arrival rate ratio at different kinds of demand points and the rescue efficiency of the collaborative vehicle combination are carried out.The important performances such as system loss probability,fire vehicle workload and dispatch frequency under different scenarios are obtained.The proposed hypercube queuing theory model is then added to a vehicle deployment optimization model.The results show that the numbers,spatial distributions,and deployment policies of firefighting vehicles will have a significant impact on the effectiveness of fire service systems.Based on the “location-allocation” optimization problem,the cooperative vehicle deployment model under hypercube queuing equilibriums is embedded into the strategic location model for partial coverage and collaborative rescue provided fire stations.The location-allocation optimization model for Chinese fire rescue mechanism is proposed.Considering the complexity in solving this problem,a hybrid heuristic algorithm combining “random search algorithm” and “improved steepest descent method” is used.In the case analyses,the results in different scenarios were compared,and the sensitivity analysis on key parameters,such as the cost of fire resource,the capacity of the fire station and the connecting cost of satellite fire stations,were analyzed.The optimization results confirm the effectiveness of the algorithm and reflect the problems in the existing fire facilities site location and fire vehicle allocation.A useful reference for decisions of fire resource construction and management is also provided.