Daoming Dai’s research while affiliated with Hefei University of Technology and other places

People can choose to be vaccinated to prevent diseases at their own expense. There are specific vaccines for many diseases. Meanwhile, for a particular disease, there might be multiple vaccines available to choose from. Based on that, we constructed a stylized vaccine supply chain (VSC) model for the market where domestic vaccines and imported vaccines co-exist. We explored the effect of government tariff policies on the game behaviors between a domestic vaccine manufacturer (DVM) and an imported vaccine manufacturer (IVM). This paper analyzes the short-term game and long-term evolutionary game behaviors of the VSC from both the entirely rational and boundedly rational perspectives. The analysis considers three tariff policies: no tariffs on imported vaccines, tariffs borne by the IVM, and tariffs borne by buyers. Results suggest that in the short-term game, buyers bearing tariffs on imported vaccines can enable the DVM to gain the most market share. The buyers willingness-to-pay is relatively low for imported vaccines, which makes the DVM more profitable. Imposing tariffs on imported vaccines can reduce the IVMs profit margin. However, the IVM still prefers to bear the tariffs itself. Lowering the cold chain transportation level and reducing the retail price of imported vaccines are both feasible solutions for the IVM to relieve the pressure from tariffs. It is also feasible for the IVM to increase the retail price of imported vaccines when the buyers willingness to pay for imported vaccines is high. In long-term evolutionary game, the DVM can gain more room for price adjustment if the IVM bears tariffs. The IVM can obtain greater cost tolerance if buyers bear tariffs. However, from governments prospective, tariffs borne by buyers is the optimal option, which makes the VSC stable and controllable.

Purpose The purpose of this study is to analyze the short-term development pattern and long-term development trend of the digital supply chain. Design/methodology/approach This study uses the combination of short-term game and long-term evolutionary game theory. Findings Findings of this study suggest that irrational decisions can make the evolutionary path of the digital supply chain complex and unpredictable. Originality/value This study proposes an evolutionary game model for the digital supply chain that can provide good guidance for the digitalization process of enterprises.

The popularity of new energy vehicles is undoubtedly the best response to the current global call to protect the environment, and the subsequent waste battery recycling and remanufacturing industry is quietly emerging under government promotion. This paper considers the government provides production subsidy or consumption subsidy for a supply chain consisting of a manufacturer and a remanufacturer. The main theme of this research is to explore the impacts of these two types of subsidy on the short-term game and long-term evolutionary game behaviors of the manufacturer and the remanufacturer. To be specific, a Cournot model is built to exam short-term game behaviors in case of production subsidy and consumption subsidy, respectively. Furthermore, we investigate a nonlinear dynamic system to study the long-term evolutionary trend of the supply chain, including long-term operation strategies, the stability of the equilibrium, and how different subsidies impact the system. Results suggest that: (a) the production subsidy is better for higher output of remanufactured products when the eco-design cost of new products is relatively low. And this subsidy works better when consumers are more environmentally conscious. (b) The government is more likely to choose consumption subsidy when consumers have less acceptance of remanufactured products. (c) In the long-term market, the consumption subsidy is more beneficial for the market to remain stable. Nevertheless, excessive adjustments in output by the manufacturer and the remanufacturer can still lead the market to be uncontrolled.

This paper discusses the short-term game and long-term evolutionary game behaviors of the supply chain composed of duopoly vehicle manufacturers which produce fuel vehicles $(\mathrm{FVs})$ and hybrid electric vehicles (HEVs) respectively. The FVs manufacturer intends to swell stakeholder's welfare by fulfilling corporate social responsibility (CSR), and $\mathrm{HEV}$ s manufacturer expands the substitution degree between the FVs and HEVs through green R\&D effort level. At first, we construct two game models (non-cooperative, cooperative) in the short-term game, and obtain the optimal profits of the FVs manufacturer and HEVs manufacturer under these two game models. Then, we use the non-cooperative game model as the benchmark model to analyze the long-term evolutionary game behavior of the system and perform numerical simulations on it. In this part, we focus on the impact of time-delay and characteristic parameters on system stability, and obtain the critical conditions for system instability caused by time-delay. Our analysis shows that when the system goes into chaos due to the excessive adjustment parameter of the FVs' output (HEVs' output), the chaos will only make the FVs manufacturer's profit (HEVs manufacturer's profit) decline, but it will increase the profit of the HEVs manufacturer (FVs manufacturer). The impacts of the customers' sensitivity to green $R \& D$ effort level and substitution degree between FVs and HEVs on HEVs manufacturer in the short-term game and the long-term evolutionary game are completely opposite.

The development of COVID-19 vaccine is highly concerned by all countries in the world. So far, many kinds of COVID-19 vaccines have entered phase III clinical trial. However, it is difficult to deliver COVID-19 vaccines efficiently and safely to the areas affected by the epidemic. This paper focuses on vaccine transportation in a supply chain model composed of one distributor and one retailer (clinic or hospital), in which the distributor procures COVID-19 vaccines from the manufacturer and then resells them to the retailer. Distributor detects the activity level of the vaccines, and retailer is responsible for transportation of the vaccines. Firstly, we establish a difference equations model with time-delay. Secondly, we investigate the impact of time-delay on the stability of vaccine supply chain. In addition, we explore the influence of decision adjustment speed of the distributor (or retailer) on the stability of vaccine supply chain. Finally, we verify the theoretical results by a two-dimensional bifurcation diagram, the largest Lyapunov exponent, entropy, and domain of attraction. The results show that when the decision delay-time or the adjustment speed of decision variables exceeds a certain threshold, it brings a negative impact on the stability of vaccine supply chain system. The stability domain of the system shrinks as customers’ sensitivity to cold chain transportation decreases and by contrast expends as customers’ sensitivity to vaccine prices decreases. When the vaccine supply chain is in a state of chaos, the effect of external control over the system is superior to that of internal control over the system.

In this paper, we investigate a supply chain consisting of an OEM (i.e., original equipment manufacturer) and a CM (contract manufacturer), in which the OEM decides design effort level and marketing level, and the CM makes decision on product manufacturing effort level. We establish a three-dimensional discrete dynamic model with time delay. Firstly, the sufficient conditions for Neimark-Sacker bifurcation are obtained by using different combinations of decision delay periods as bifurcation parameters, and the effect of the adjustment speeds of decision variables on the system stability and impact of time delay on the system stability are discussed, respectively. Secondly, we perform numerical simulation of this model from the perspective of entropy theory. Finally, we propose two methods to control chaos. Results show that when the time delay or the adjustment speed of decision variable exceed a certain threshold, the system will be led into a chaotic state and the entropy of the system will increase. For alleviating the negative effects of chaotic systems, we introduce control parameters to make efficient control on the chaos. At the critical point, the critical value of the adjustment speed of design effort level (or marketing level) of OEM increases as the adjustment speed of the manufacturing effort level of CM decreases, and vice versa.

Due to the important role of the vaccines in the prevention of global epidemics, this paper focuses on a vaccine transportation supply chain composed of one distributor and one retailer. Based on the assumption that the decision-maker does not make a decision instantaneously, we present a decision-making time-delay model. Firstly, we captured some sufficient conditions of delay-induced bifurcation for the model by regarding different combinations of the decision delay periods as the bifurcation parameters and analyzed how the speed of decision-making adjustment of distributor or retailer affects the critical point of system stability. Secondly, we made a numerical simulation on the model by using a two-dimensional bifurcation diagram, largest Lyapunov exponent, and entropy and chaotic attractor, respectively. Finally, we used two coordination methods to control chaos and compared them. The results show that when the decision delay exceeds a certain threshold, the system will lose stability or go into chaos. The precipitous speed of decision variable adjustment of the distributor or retailer will increase the entropy of the system and lead the system into a chaotic state. When the vaccine supply chain is in chaos, the effect of external control on chaos is better than that of internal control on chaos.

Taking the carbon emissions per unit product as the standard to measure the low-carbon technology level of the enterprise, this article analyzed how the technology supplier enterprises realize low-carbon production and achieve a win-win situation for both supply and demand through technology sharing through technology research and development. Based on the positive effect of low-carbon technology level on product demand, we studied the optimal pricing strategy and the optimal low-carbon technology level in the technology supply enterprises under the Stackelberg game in 3 conditions (i.e., without technology research and development or technology sharing, with technology research and development but no technology sharing, and with both technology research and development and technology sharing). We also drew a comparative analysis of the optimal product price, the optimal low-carbon technology level, and the optimal profit in the three scenarios. Besides, by constructing a delayed differential price game model, we studied the equilibrium strategy of price competition between technology supply and demand companies and the local asymptotic stability of the game system at the equilibrium point. In addition, the effects of delay strategy on game equilibrium strategy, the influence of the degree of adjustment of decision variables on the stability of the game system, and the stability of the game system on the evolution trend of the game are also explored. By comparing and analyzing the game results of the oligopoly enterprises in the stable system and the unstable system, it confirmed that the system instability usually causes serious harm to the enterprise.

This paper constructs a continuous dual-channel closed-loop supply chain (DCLSC) model with delayed decision under government intervention. The existence conditions of the local stability of the equilibrium point are discussed. We analyze the influence of delay parameters, the adjustment speed of wholesale price, recovery rate of waste products, direct price, carbon quota subsidy, and carbon tax on the stability and complexity of model by using bifurcation diagram, entropy diagram, attractor, and time series diagram and so on. Besides, the delay feedback control method is adopted to control the unstable or chaotic system effectively. The main conclusions of this paper show that the variables mentioned above must be within a reasonable range. Otherwise, the model will lose stability or enter chaos. The government can effectively adjust manufacturers' profit through carbon tax and carbon quota subsidy, and encourage manufacturers to reduce carbon emissions and increase the remanufacturing of waste products.