Harvesting energy from environmental sources such as solar and wind can mitigate or solve the limited-energy problem in wireless sensor networks. In this paper, we propose an energy-harvest-aware route-selection metho...Harvesting energy from environmental sources such as solar and wind can mitigate or solve the limited-energy problem in wireless sensor networks. In this paper, we propose an energy-harvest-aware route-selection method that incorporates harvest availability properties and energy storage capacity limits into the routing decisions. The harvest-aware routing problem is formulated as a lin- ear program with a utility-based objective function that balances the two conflicting routing objectives of maximum total and maxi- mum minimum residual network energy. The simulation results show that doing so achieves a longer network lifetime, defined as the time-to-first-node-death in the network. Additionally, most existing energy-harvesting routing algorithms route each traffic flow independently from each other. The LP formulation allows for a joint optimization of multiple trafic flows. Better residual energy statistics are also achieved by such joint consideration compared to independent optimization of each commodity.展开更多
Recently,battery capacity and charging speed have been the bottlenecks of mobile communication networks.Energy harvesting(EH)relaying has become a promising solution for green 5th generation mobile communication with ...Recently,battery capacity and charging speed have been the bottlenecks of mobile communication networks.Energy harvesting(EH)relaying has become a promising solution for green 5th generation mobile communication with the advancement of wireless power transfer technology.In this paper,we investigate EH relaying in vehicular networks and adopt distributed beamforming(DB)to enhance the reliability and capacity of EH relaying.To be more specific,we propose a DB solution based on the joint optimization of power-splitting(PS)factors.For amplify-and-forward relaying,to transform the optimization problem into a quasi-convex one,we apply the semidefinite relaxation(SDR)method so that we can effectively attain the global optimal solution,while the suboptimal DB solution with distributed optimal PS factor which only requires local channel state information is also proposed.For decode-and-forward relaying,to get the optimal PS factors,we set a signal-to-noise ratio threshold at the relays,which can reduce the system error rate caused by the poor transmission link.Simulation results demonstrate the efficiency of our proposed DB-based EH relaying scheme in vehicular networks.展开更多
We report a voltage generator based on a graphene network （GN）. In response to the movement of a droplet of ionic solution over a GN strip, a voltage of several hundred millivolts is observed under ambient condition...We report a voltage generator based on a graphene network （GN）. In response to the movement of a droplet of ionic solution over a GN strip, a voltage of several hundred millivolts is observed under ambient conditions. In the voltage-generation process, the unique structure of GN plays an important role in improving the rate of electron transfer. Given their excellent mechanical properties, GNs may find applications for harvesting vibrational energy in various places such as raincoats, umbrellas, windows, and other surfaces that are exposed to rain.展开更多
文摘Harvesting energy from environmental sources such as solar and wind can mitigate or solve the limited-energy problem in wireless sensor networks. In this paper, we propose an energy-harvest-aware route-selection method that incorporates harvest availability properties and energy storage capacity limits into the routing decisions. The harvest-aware routing problem is formulated as a lin- ear program with a utility-based objective function that balances the two conflicting routing objectives of maximum total and maxi- mum minimum residual network energy. The simulation results show that doing so achieves a longer network lifetime, defined as the time-to-first-node-death in the network. Additionally, most existing energy-harvesting routing algorithms route each traffic flow independently from each other. The LP formulation allows for a joint optimization of multiple trafic flows. Better residual energy statistics are also achieved by such joint consideration compared to independent optimization of each commodity.
基金This work was supported in part by National Key Research and Development Project under Grants 2017YFE0119300 and 2019YFB2102300in part by National Natural Science Foundation of China under Grants 61936014 and 61901302+2 种基金in part by Shanghai Aerospace Science and Technology(SAST)Innovation Fund under Grant SAST2019-091part by Fundamental Research Funds for the Central Universities(China)under Grant 22120190218Part of this work has been published in IEEE/CIC ICCC 2019[1].
文摘Recently,battery capacity and charging speed have been the bottlenecks of mobile communication networks.Energy harvesting(EH)relaying has become a promising solution for green 5th generation mobile communication with the advancement of wireless power transfer technology.In this paper,we investigate EH relaying in vehicular networks and adopt distributed beamforming(DB)to enhance the reliability and capacity of EH relaying.To be more specific,we propose a DB solution based on the joint optimization of power-splitting(PS)factors.For amplify-and-forward relaying,to transform the optimization problem into a quasi-convex one,we apply the semidefinite relaxation(SDR)method so that we can effectively attain the global optimal solution,while the suboptimal DB solution with distributed optimal PS factor which only requires local channel state information is also proposed.For decode-and-forward relaying,to get the optimal PS factors,we set a signal-to-noise ratio threshold at the relays,which can reduce the system error rate caused by the poor transmission link.Simulation results demonstrate the efficiency of our proposed DB-based EH relaying scheme in vehicular networks.
基金This work was supported by Beijing Science and Technology Program （No. D141100000514001） and the National Natural Science Foundation of China （No. 51372133）.
文摘We report a voltage generator based on a graphene network （GN）. In response to the movement of a droplet of ionic solution over a GN strip, a voltage of several hundred millivolts is observed under ambient conditions. In the voltage-generation process, the unique structure of GN plays an important role in improving the rate of electron transfer. Given their excellent mechanical properties, GNs may find applications for harvesting vibrational energy in various places such as raincoats, umbrellas, windows, and other surfaces that are exposed to rain.
