A broadband tunable metamaterial graphene absorber is investigated in this paper. The unit cell of the proposed metamaterial graphene absorber is composed of four patch resonators. By tuning the chemical potential of graphene and the geometric size of each patch, the simulated total reflectivity is less than −10 dB from 22.02 to 36.61 THz and with the total thickness of 0.76 um (only 0.09λ at the lowest frequency). The analysis of the surface current, magnetic field and power flow distributions has been performed to better understand the absorption mechanism. Moreover, this proposed absorber achieves its bandwidth tunable characteristics through a voltage biasing of the graphene’s Fremi level. This proposed metamaterial graphene absorber (MGA) could be used as smart absorbers, photovoltaic devices and tunable sensors.

This paper examines the dual-channel supply chain in which the differentiation of the environmental sustainability of channels is considered. We analyze the influences of the level of environmental sustainability of channels on the pricing policies for the supply chain members in both centralized and decentralized models using the Stackelberg game model under inconsistent price policy. We obtain the optimal level of environmental sustainability of channels and pricing decisions for the players in the centralized and decentralized dual-channel supply chains. Results show that the influence mechanisms of the level of environmental sustainability of channels on the pricing decisions are different in the centralized and decentralized models. Furthermore, numerical analysis has been conducted to investigate the effects of the cross-environmental-sustainability sensitivity factor and the initial proportion of consumers who prefer the retail channel on the level of environmental sustainability of channels, pricing policies and players’ profits.

The paper explores the pricing policies and green strategies in a duopoly green supply chain with vertical and horizontal competition, which includes a green manufacturer, a traditional manufacturer and a common retailer. The purpose of the paper is to address the following research problems: (1) How manufacturers’ market power influences the pricing policies and green strategies of supply chain members in a green supply chain? (2) What conditions do first-mover advantage and green competitive advantage be effective simultaneously? We establish the linear demand functions of the duopoly green supply chain and obtain the players’ optimal decisions under channel members’ different market power. Further, we conduct sensitivity analysis and numerical examples of players’ optimal decisions about consumer’s environmental awareness and greening cost effector. Based on the theoretical and numerical analysis, we find that green manufacturer would benefit from the increment of consumer’s environmental awareness but be depressed by the increase of greening cost, which is contrary to the traditional manufacturer. Additionally, correlations of retailer’ optimal decisions and profits between consumer’s environmental awareness and greening cost effector are related to the manufacturers’ market power structures. Furthermore, we find that the green competitive advantage is more effective than first-mover advantage while first-mover advantage does not always effective in the duopoly green supply chain. Specially, traditional manufacturer always prefers to be the follower competing with the green manufacturer, no matter with the variety of consumer’s environmental awareness and greening cost effector, while green manufacturer would like to be the leader only when the consumer’s environmental awareness is relatively high or the greening cost effector is relatively low.

Disruptive computer viruses have inflicted huge economic losses. This paper addresses the development of a cost-effective dynamic control strategy of disruptive viruses. First, the development problem is modeled as an optimal control problem. Second, a criterion for the existence of an optimal control is given. Third, the optimality system is derived. Next, some examples of the optimal dynamic control strategy are presented. Finally, the performance of actual dynamic control strategies is evaluated.