1.1 Reverse logistics
American scholar Stock (1992) first proposed the concept of “reverse logistics” in 1992, and it was included in the research report of the American Association of Logistics Management. Fleischmann (2001), the master of reverse logistics, gave a relatively broad definition of reverse logistics in 2001: “Reverse logistics is the process of effectively planning, implementing and controlling the inflow and storage of second-hand products and related information, which is in the opposite direction of the traditional supply chain., whose purpose is to restore the value of the product and dispose of it properly.”
Reverse logistics comes from circular logistics, which is also called green logistics, including forward logistics and reverse logistics (Wilson M et al. 2021). Compared with forward logistics, reverse logistics includes not only basic material flow, but also energy flow and information flow. Forward logistics and reverse logistics are two different ways of material circulation between enterprises that are formed on the basis of circular economy, industrial ecology and green logistics theory in order to maximize economic, social and environmental benefits. The specific relationship is shown in Figure 1. The main body of the eco-industrial chain is divided into supply-oriented enterprises, production-oriented enterprises, consumer-oriented enterprises and decomposing enterprises, which correspond to the three links of producers, consumers and decomposers in the ecosystem.
The eco-industrial park came into being under the pursuit of people to reduce waste of resources, care for the environment, and achieve the harmonious development of the environment and society. Reverse logistics is to coordinate resources and recycle waste for recycling, it is a powerful concept of circular economy in the eco-industrial park support and specific performance (Yu Ying 2017). Therefore, reverse logistics is a concrete manifestation of the circular economy of the park and a key link of the circular economy of the park. Combining the theory of reverse logistics to improve the industrial chain of the park can not only improve the correlation between the industrial network and the industrial chain in the park, reduce the production cost of the park, but also save natural resources and comply with the social requirements of environmental protection.
1.2 Geographic information system
In recent years, with the rapid development of eco-industrial parks, a common problem has become increasingly prominent: Although there is a planned construction plan, there is a lack of technical means to support the smooth implementation of the plan (ZHANG Jing et al. 2015).
Geographic Information System (GIS) can analyze and process spatial information and provide rich spatial data information for spatial decision-making. Based on GIS technology, it can not only tap potential industrial symbiosis opportunities more efficiently, improve resource utilization efficiency and reduce waste generation, but also be applied to the planning and management of eco-industrial parks, such as corporate site selection, spatial layout, and waste in terms of recycling and reuse (WANG Xue et al. 2017). Therefore, the use of GIS technology in the planning process of the eco-industrial park can make the park's spatial layout more practical and use land, better realize the circular economy, and alleviate environmental pollution problems.
1.3 Goal achievement matrix
The goal achievement matrix (GAM) was proposed by Hill in the 1860s. It is a quantitative evaluation method for evaluating whether a planning plan meets the predetermined goals (Niu Xinyi et al. 2008). It is often used to evaluate various planning plans. The specific method is as follows. First, the planning principle is embodied into z predetermined goals (O1, O2, O3...Oz), and the conflict rate between the planning plan under each goal and the predetermined goal is calculated, and then the calculation of each plan is the conflict index Eo,i and the comprehensive conflict index Ei under each goal. The calculation formulas for conflict rate and conflict index are:
Among them, CMA is the conflict rate, A is the planning plan, B is the predetermined goal, and AI B is the conflict range between the planning plan and the predetermined goal.
Among them, Wo is the weight value of the o-th predetermined target, CMAo,i is the conflict rate of the -th scheme under the i-th predetermined target, and z is the total number of targets.