The Research of Terminal Distribution Network Path Optimization ()
1. Introduction
In the process of logistic distribution network optimization, two stages are included: the first stage is the path optimization of distribution between nodes, namely the goods in the process of continuous distribution, the path between source node distribution to the target distribution optimization process; the second stage is the terminal distribution route optimization, namely by the target distribution node to the path optimization process between multiple clients. So this article mainly aims at terminal distribution route optimization problem. The terminal distribution route optimization is in the process of building dynamic optimization algorithm, from the target distribution node distribution vehicle, and delivering goods to N customers, in the most appropriate distribution route to the minimum distribution distance and optimizing the terminal distribution path.
2. Research Overview of the Logistics Distribution Network Path Optimization Problem
2.1. Distribution Network Path Optimization Research
Path optimization problem in logistics distribution network with the traditional path optimization problem has certain difference, path optimization problems in network aiming at the condition of the traverse network point or edge can be divided into arc routing problem and point path problem. Among them, the arc routing problem consider is to service in the network edge, and some path problem is main consideration of neutral network service. A typical representative of the typical point path is traveling salesman problem and vehicle routing problem.
In view of the distribution network and its path optimization, Niu Yongliang [1] proposed a “three level” such as logistics distribution network structure, this structure with conform to the actual network structure of enterprise, on the principle of “quadtree” partition to the customer, using a two-phase heuristic algorithm to optimize the vehicle driving route. Wang Rumei [2] , such as the freedom of the traditional annealing algorithm into directional annealing algorithm, and the examples show that this algorithm improves the efficiency. Jiang Zhongzhong [3] , in the research of vehicle routing optimization problem, starting from the actual situation in the process of delivery, considering the uncertainty of vehicle travel time and customer service time, the logistics distribution network composed of distribution center and customer two kinds of nodes is not completely undirected graph representation, established a fuzzy programming model of logistics distribution vehicle routing optimization. Liu Qiusheng [4] , such as vehicle loading optimization model is established, using the dynamic programming method to obtain the optimal solution.
Ko Hyun-Jeung and Geraldw. Evans (2007) [5] from the perspective of third-party logistics enterprises to build and optimize the mixed integer nonlinear programming model of reverse logistics, and puts forward the genetic algorithm based on heuristic algorithm to solve the model, Ma Zujun [6] from the Angle of the operating cost minimum, establishes the mixed integer linear programming model, in order to determine the number of facilities, location, and every reasonable logistics path through put.
H. A. Eliselt [7] mainly explores several categories such as: Chinese postman algorithm to the Chinese postal problems, have no to China post road, windy China postal problems, mixed China post road, heuristic China postal problems. G. Groves [8] study the profit maximization of China post road. W. L. Pharn [9] in combination with a variety of graph theory algorithm, at the same time considering the vehicle routing and scheduling management two aspects of the path optimization problem. Qin Wenqing [10] , from the cooperation of supply chain level (horizontal), optimizes distribution network. The purpose is to improve the whole service level of the supply chain logistics network.
2.2. Literature Review
Most scholars in the research question will focus on the algorithm was improved, and focused on the goal of optimization design, but most of the studies did not fully combined with the actual distribution of the characteristics of the transportation network, most researchers think in between any two points can be directly to the model and algorithm on the basis of the design, so the logistics distribution route optimization problem with distribution of transportation network connectivity, remains to be further studied.
In most of these studies focused on the path of the logistics distribution network under normal conditions for optimization problems, due to the logistics distribution network not only include the traditional “positive” logistics distribution network, at the same time also includes return and old product recycling in the reuse of reverse logistics network, so in view of the combination of forward and reverse logistics distribution network in the path optimization problem remains to be further discussed.
2.3. Research Purposes
In view of the different nature and function of logistics distribution network nodes, the phases to solve the problem of logistics distribution network path optimization ideas and methods.
In logistics distribution network structure and based on the operation process of logistics distribution network, on the basis of logistics enterprises in the operating process of the path optimization of logistics distribution network can be divided into different stages. According to the characteristics of the second phase terminal distribution route optimization, constructing closed-loop dynamic optimization algorithm, and validate through the case.
3. The Terminal Distribution Operation Process Ease
1) Distribution location of dispatching personnel according to the customer, to customer order classification, divided into basic distribution area.
2) The nature of the goods, goods dispatching personnel according to user’s need to classify the goods, will be the similar goods together, complete vehicle loading.
3) According to the required time to the customer order, determine the order of distribution, order of the identified here is tentative, because the further optimization needs according to the specific situation.
4) Operator according to the situation of the goods, the cost to arrange vehicles, according to the actual situation to choose outsourcing transportation or their own transport.
5) The operator according to the customer’s position, the time of delivery requirements and local traffic condition, to determine the distribution line, as far as possible to meet customer request at the same time, the lowest transportation cost.
6) Determine after distribution line, according to the principle of minimum saving mileage, can determine the distribution order.
7) On the basis of certain distribution order, send before they are installed, after send first loading principle, loading, then transportation [11] .
8) The customer sign for it, the owner customer and salesman, has its own team or other service providers to point the goods after the sign or seal on the delivery form, by a solicitor, has its own team or other service providers will bring the relevant papers and documents back. Distribution stage at the end of the operation flow chart shown in figure 1.
From the point of view of the operation process of distribution between nodes, the key lies in the order in the shipping transit transfer process between the nodes, so in different constant goods distribution, the distribution of nodes by the source of goods distribution node to the target distribution by repeated movement-pause-sportspause. Through the analysis of enterprise logistics distribution system, can pause in the abstract into node, movement can be abstract as chain. Such goods distribution can be defined as the goods between distribution node in network of nodes and lines that connect the direction of the movement in the transfer process. From the operation process of the end of delivery, the key point is that the goods allocation process between customers, that is, from a process of distribution network at the grass-roots level to multiple clients. Because of the node of the two phase involves different, operation process is also different, so the path of the distribution network optimization problem was divided into different stages [12] .
4. Terminal Distribution Path Optimization Research
4.1. The Terminal Distribution Route Optimization Task Model
The terminal distribution of the path optimization of logistics distribution network is goods from grassroots target distribution path optimization process between the node to multiple clients. The problem set from a primary distribution node from the system (1) is assumed to be node sends a vehicle to each customer within the system for material distribution, distribution again after the completion of the each customer returns and recycling materials back to the primary distribution node 1. Research on material distribution vehicle shortest path and route. So it is a combination of forward logistics and reverse logistics of closed-loop path on closed-loop logistics network optimization process, as shown in figure 1. Lines represent different nodes in the network transport of goods between the moving route, there may be multiple transport routes between any pair of nodes are linked together, these lines represent the different mode of transportation, transportation routes or different goods.
Mentioned in this paper, the closed-loop logistics refers to the full consideration in the process of traditional logistics distribution in reverse logistics, and put forward logistics and reverse logistics distribution system analysis and processing, make the logistics distribution system more reasonable, it is in the reverse logistics and forward logistics distribution is put forward on the basis of the combination of. As a result, the composition of closed-loop logistics network should include the following two parts: traditional “positive” logistics distribution