| The typhoon storm surge disaster has a wide range of disasters,and the casualties and economic losses caused by it rank first in natural disasters.China is one of the countries affected by storm surge disasters.According to the relevant plans of storm surge disaster,the main measures to prevent storm surge disaster in China are to carry out hidden danger investigation in advance,formulate emergency plans,and organize the masses in the risk area to transfer and avoid danger before the arrival of typhoon.However,at this stage,the emergency evacuation personnel allocation scheme mostly relies on the experience and judgment of decision makers to adopt the nearby resettlement method,which may cause resource preemption and lead to insufficient optimization of the evacuation plan.Based on this background,this paper studies the application of transportation model and linear programming model in emergency evacuation based on the actual needs of emergency evacuation plan for storm surge disaster prevention,aiming to construct a scientific and efficient emergency evacuation plan and provide auxiliary support for relevant departments.The main research contents and achievements of this paper include :(1)The minimum vehicle emergency evacuee allocation model with capacity constraints(MVEEACC)is proposed.The model takes the minimum total travel cost as the objective function,and takes into account the capacity constraints of the disaster shelter and the passenger capacity of the vehicles for transporting the masses,and gives the assumptions,constraints and mathematical formulas of the model.(2)Solving the MVEEACC problem model based on linear programming and transportation problems.In the traditional transportation model,the transportation cost is linearly related to the number of people transferred,and the higher the number of people transferred,the higher the cost.In the case of emergency evacuation,the transportation cost is related to the passenger capacity of the transfer vehicle,and the transportation cost of one vehicle transporting one person and multiple people(not exceeding the passenger capacity)can be regarded as the same.Based on this,this paper designs and proposes a linear programming model for solving the MVEEACC problem model by adding new constraint variables and equations,which can solve the exact solution in the case of smaller problem size.For larger scale problems,the heuristic algorithm(Shortest distance converted to least number of trips,DTT algorithm)is proposed in this paper.The DTT algorithm is divided into two steps.The first step solves the allocation scheme of disaster victims with integer multiple of passenger capacity,and the second step allocates the remaining disaster victims.The nearest neighbor algorithm idea is used to test the algorithm with simulated data.The results show that although the exact algorithm can find the optimal solution,the solution speed is slow and can solve the problem on a small scale.DTT algorithm has obvious advantages in solving large-scale problem cases,with the average solution time within 5s when the number of evacuees exceeds one million,and can save up to 16% of the total evacuation mileage compared with the empirical algorithm of nearest neighbor placement.(3)Design and implementation of emergency evacuation WebGIS system.An emergency evacuation system based on B/S architecture and GIS technology is developed,which takes the responsible personnel of emergency evacuation as the user object.By relying on Baidu map API,Node.js,Rserve,RSclient and other technologies,the interactive function of the map is realized,and users can customize the input of relevant information.Considering the actual traffic situation and the real road network,the distance matrix is obtained by using Baidu map driving route planning.The problem model and algorithm are integrated into the system,and the algorithm results are visualized through the front and back end interface calls.The architecture pattern of front and back end separation reduces the degree of coupling of the system and enhances the maintainability of the system.In this paper,the transportation model in graph theory is introduced into the field of storm surge emergency evacuation,and the MVEEACC problem model and the corresponding accurate algorithm and DTT algorithm are proposed,which enriches the related theoretical research in the field of emergency evacuation,provides scientific reference for the formulation of emergency evacuation plans,and the developed WebGIS system can provide tool support for the relevant departments of emergency evacuation. |
