Recently, “environment-to-human” transmission has become a new pattern in the spread of COVID-19, and novel coronavirus variants with increased infectivity have appeared in many countries. With considering the “environment-to-human” transmission and virus mutations of the novel coronavirus, the SEIQR model of infectious disease dynamics was established to simulate the development trend of the epidemic. The results showed that, the increased infectivity of virus variants and “environment-to-human” transmission positively affects the spread and speed of COVID-19 epidemic, in which the virus variants had a more significant impact, and the “environment-to-human” transmission will promote the outbreak time of the epidemic to be greatly advanced. For the virus variants with higher infectivity, elevating the intensity of interventions has a more remarkable effect on controlling the spread of COVID-19 variants.

In order to explore the internal mechanism and laws of the evolution of the Silk Road Economic Belt production networks with ecological environment in the perspective of complexity science. System dynamics method is used to build the coupled system dynamic model, and simulation analysis is conducted. The coupling system dynamic evolution process and evolution rules are explained under three different scenarios: the evolution of natural development model, production network to accelerate development mode and development mode of ecological environment. It is found that the Silk Road Economic Belt production network and the coupling development of ecological environment is the premise of the evolution of the development of production networks. Driven by the Belt and Road Initiative, Continuously promoting the development and evolution of the production network of the Silk Road Economic Belt is an effective way to promote the high-quality and sustainable development of the Silk Road Economic Belt

In view of the competitive marketing of various products and the competitive dissemination of various information in social networks, the deterministic social influence maximization problem was studied considering the competitive and deterministic factors, and the integer programming model of the problem was constructed, and the large-scale approaching algorithm was designed. The experimental results showed that the marginal influence correction algorithm based on diffusion information showed good scalability and stability, and the reduction of the leading degree of solving quality was more than 20%. The solving time only accounted for a small proportion of the time cost of greedy algorithm and commercial software. It provides a feasible optimization scheme for the practical application of enterprises in the diffusion of competition.

Entrepreneurial opportunity window affects the first-action and late-action decision-making of entrepreneurial enterprises. The z-Tree system simulates the decision-making process of first and late start-up enterprises based on the market entry order, recruiting 60 college students to participate in the experiment, and uses the rank sum test model to process the data collected by the experiment. The main conclusions include: 1) When the opportunity window is not opened, the first start-ups always have market advantages, while the second start-ups have market disadvantages. The advantage gap between the two types of start-ups is relatively fixed. 2) Under the technology opportunity window, the change of technology gap between first start-ups and second start-ups has a significant impact on the output and profit of first start-ups, but has no significant impact on the output and profit of second start-ups. Second start-ups can narrow the market advantage gap between first start-ups and second start-ups by developing technology. 3) Under the institutional opportunity window, the change of institutional cost has a significant impact on the profits of first and second start-ups. The government can adjust the change of market advantage between the two types of start-ups through institutional cost.

In order to study the application of complex network in quality management, we construct the PCB quality factors control network from the perspective of the combination of quality management tools and complex network. We analyze this network using knowledge of complex network theory. The results show that the PCB quality factors control network approximately obeys a power law distribution. we identify the key quality factors that need to be prevented from the PCB quality factors control network.The complex network can help companies establish a zero-defect quality system and reduce the occurrence of quality defects. Complex network can be used as an effective tool for quality management to solve quality management problems in actual production activities and provide a new research perspective for quality improvement and prevention and control, and improve the efficiency and level of quality management.

It is very meaningful to get a new model of multi-agent system based on Nash equilibrium. Combining the practice and using the graph theory method, this paper constructs a new class of model which is different from the general model and Tanner model: iso-neighbor model. We first introduce the unique characteristics of this kind of model from the point of view of graph theory, then analyze the differences of controllability between iso-neighbor model and other models in multi-agent system, and draw the following conclusions: The iso-neighbor model can produce the same controllability as other models under fixed conditions.

Clarifying the mechanism among disease, economic growth and relative poverty will help consolidate the results of the fight against poverty. Based on complex adaptive system and computer simulation, a multi-agent simulation platform was constructed with Sichuan Liangshan Yi Autonomous Prefecture as a case. The results indicated there is a significant correlation between disease, economic growth and relative poverty, and reducing the incidence of disease, increasing medical insurance, enhancing family risk resistance, and increasing the degree of green development can significantly reduce the number of relatively poor people. Therefore, in addition to improving basic medical insurance, the policy to solve poverty caused by illness needs to be comprehensively designed from the perspective of improving the family′s ability to resist risks and transforming the economic growth mode.

In order to study the evolution characteristics of conventional energy trade network, based on the energy international trade data from 2010 to 2019 and the complex network theory, this paper constructs a directed weighted network to analyze the overall characteristics of the network and the changes of the characteristics of trade core countries and China in the network. The results show that the scale of conventional energy trade is becoming larger and larger; The United States, the Netherlands and China have strong ability to control trade; China is the core node connecting the network. It is suggested that all countries should observe the trade trend of the United States, the Netherlands and China and adjust the trade volume; The United States, Japan and China are the preferred trading partners of trading countries; Countries with insufficient resources and high demand establish trade relations with Saudi Arabia, Russia and other countries.

Knowledge transfer has a positive role in promoting the accumulation and creation of enterprise knowledge, and it is also one of the key ways to shape the competitive advantage of the entrepreneurial ecosystem. According to ecological theory, the enterprises in the entrepreneurial ecosystem are divided into two types of heterogeneous enterprises, symbiosis and competition, and a knowledge transfer model between heterogeneous enterprises is constructed. The general expression of the number of knowledge regeneration is derived from the model, and the balance point of knowledge transfer is obtained. The existence and stability of the system have been verified. Combined with numerical simulation, it is found that the frequency of inter-firm contact, the time of knowledge integration, and the proportion of the two types of enterprises will all affect the number of knowledge regeneration, which in turn affects the balance of knowledge transfer, and when the number of knowledge regeneration is greater than 1, the proportion of symbiotic enterprises will increase. As the number of knowledge reproduction increases, the activity of knowledge transfer within the system will also be enhanced; the increase in the degree of openness of the system can significantly promote knowledge transfer.

In fuzzy demand market environment, considering manufacturer's fairness preference behavior, a Stackelberg game model for dual-channel green supply chain composed of a manufacturer and a retailer is established. Then the equilibrium strategies of product price and carbon emission reduction level are derived. Finally, numerical examples are presented to explore the influence of consumer's environmental awareness and green manufacturer's fairness preference on the decisions and profits of green supply chain members. It is shown that: As the uncertainty of market demand increases, the product price, the product carbon emission reduction level and the expected profits of the dual-channel supply chain players increase. The higher consumer's environmental awareness is conducive to encouraging the green manufacturer to improve energy conservation and emission reduction technology. The manufacturer's fairness preference behavior will make them pay more attention to the fairness of profit distribution between channels, and lead to the decrease of supply chain operation performance.