Research On Reliability Logistics Node Location Considering Curved Demands

With the "Belt and Road" initiative and the further development of China's transportation industry,the construction of transportation routes still has a sustained and stable peak construction period.In the construction of transportation routes,the cost of materials accounts for more than 60%,and these materials are often transported to the road section to be built through the logistics nodes established in advance.Therefore,scientific and reasonable logistics node location can not only ensure a reasonable supply of materials,but also control the cost of materials.For transportation line construction projects,the material requirements are continuously distributed along the transportation line,and the location problem of logistics nodes serving the curved demand is different from the classic facility location problem.In addition,in the classic facility location problem,it is generally assumed that once the facility is established,it will operate normally without failure for ever,that is,the facility is completely reliable.During the construction of transportation lines,some uncertain factors often occur,such as: natural disasters,technical factors,man-made accidents,etc.,causing the risk of failure of the logistics node.Once the logistics node fails,its service demand line needs to be served by the logistics node farther away,thereby increasing the transportation time.Compared with materials with stable performance such as rails,sand and gravel,it is more worthy of attention to make reliable logistics node location decisions for materials such as concrete that are more sensitive to time.Through the problem description and definition,the dissertation first introduces the reliability of the facility.On this basis,the distance function of the reliability logistics node location problem is defined.The line integral of the demand density is used to express the demand of a section of transportation line,and the transportation cost is constructed in combination with the downstream transportation rate.Finally,the continuous time penalty cost function is summarized,and further combined with the timesensitive characteristics of the concrete,two different penalty functions,linear and exponential,are used to reflect the change of its performance with time.Based on the foregoing,the dissertation aims at minimizing the sum of transportation costs and time penalty costs.First,two reliability logistics node location models under the linear and exponential time penalty cost functions with the same failure probability are constructed.According to the different properties of the two models,different methods are used to obtain the optimal locations of the two logistics nodes.Based on this,two reliability logistics node location models under two kinds of time penalty cost functions with different failure probabilities are constructed.When the probability correlation coefficient and the failure probability of one logistics node are fixed,how the optimal locations of the two logistics nodes changes with the probability of failure of another logistics node is analyzed.Through the analysis of numerical examples,it is found that when the failure probability of two logistics nodes are the same,as the probability of failure increases,the total cost of location gradually increases,and the two logistics nodes gradually approach the midpoint of the demand line,showing a "concentration effect",while the correlation coefficient will affect the strength of this "concentration effect";when the failure probability of two logistics nodes are different,logistics nodes with lower failure probabilities should be placed at the midpoint of the demand line.To a certain extent,the effectiveness of the model in this dissertation is proved,which provides a solution and reference for the location problem of reliability logistics nodes for different time-sensitive materials.The dissertation has 21 figures,11 tables,and 81 references.