Recent many works have concentrated on dynamically turning on/off some base stations (BSs) in order to improve energy efficiency in radio access networks (RANs). In this survey, we broaden the research over BS switching operations, which should competition up with traffic load variations. The proposed method formulate the traffic variations as a Markov decision process which should differ from ...

Wireless sensor networks (WSNs) have been considered as a promising method for reliably monitoring both civil and military environments under hazardous or dangerous conditions. Due to such environments ,the power supplies for sensors in the network are not usually rechargeable or replaceable. Therefore, the energy efficiency is critical for the lifetime and cost of WSN. Numerous mechanisms have...

This paper presents the design and implementation of an LED lighting module powered by a wireless power transfer system. The overall system achieves an efficiency of 82% with an output power of 36 W when the load resistance in the receiver is 30 Ω, which is the turn-on resistance of the LED lighting module. The transmitter of the system adopts ClassE power amplifier structure instead of Class-D...

Conventional two-state dc to dc voltage converters have in their small signal transfer function a right half planzero in pole-zero plane whichthis zero result in speed reduction and lowfrequency operation, especially, because position of the zero is not fixed andmovesby the load variation. To remedy this problem the tri-state boost converters have been introduced. These converters haven’t the m...

an irreversible stirling heat pump cycle using ferromagnetic materials as a cyclic working substance is established. the influences of finite-rate heat transfer, heat leak, regeneration time, regenerative lossand the internal irreversibility on the cyclic performance of magnetic heat pumps are taken into account. on the basis of the thermodynamic properties of ferromagnetic materials, the perfo...

During the flight mission of hypersonic aircraft, severe aerodynamic heating will occur on surface, so thermal protection system (TPS) is required to protect load-bearing structure aircraft. The present paper develops an engineering software for automatic optimization thickness tile-type TPS reusable For requirements aircraft in reentry stage, method heat flow-time curve enveloping, material se...

Wind energy penetration in power system has been increased very fast and large amount of capitals invested for wind farms all around the world. Meanwhile, in power systems with wind turbine generators (WTGs), the value of Available transfer capability (ATC) is influenced by the probabilistic nature of the wind power. The Mont Carlo Simulation (MCS) is the most common method to model the uncerta...

Solar Energy Applications Laboratory , Colorado State University . Fort Collins , CO 80523 Design of a vapor transport solar water heater using R-123 is optimized to maximize thermal performance and minimize life cycle cost. Optimal systems for one and twostory homes are identified in a parametric study of collector area, condenser heat transfer area, water storage tank volume and circulating r...