In this paper, the energy-efficient power control problem in cognitive radio （CR） networks is studied not only to provide energy-efficient transmission, but also to guarantee the normal operation of primary users （...In this paper, the energy-efficient power control problem in cognitive radio （CR） networks is studied not only to provide energy-efficient transmission, but also to guarantee the normal operation of primary users （PUs）. Moreover, the static energy-efficient power control （SEPC） algorithm is proposed in static scenario to maximize the capacity of secondary users （SUs） and to reduce the power consumption according to the interference from PU to SU. Furthermore, based on the analysis of PU＇s dynamic feature with Markov chain and SEPC algorithm,the dynamic energy-efficient power control （DEPC） algorithm is proposed taking into account the probability of detection and false alarm caused by sensing errors. Extensive simulation results show that the performance of the proposed algorithms is significantly improved compared with the existing algorithm.展开更多
The solid-state magnetic cooling(MC)method based on the magnetocaloric effect(MCE)is recognized as an environmentally friendly and high-energy-efficiency technology.The search or design of suitable magnetic materials ...The solid-state magnetic cooling(MC)method based on the magnetocaloric effect(MCE)is recognized as an environmentally friendly and high-energy-efficiency technology.The search or design of suitable magnetic materials with large MCEs is one of the main targets at present.In this work,we apply the chemical and hydrostatic pressures in the Ni_(35)Co_(15)Mn_(35-x)Fe_(x)Ti_(15) all-d-metal Heusler alloys and systematically investigate their crystal structures,phases,and magnetocaloric performances experimentally and theoretically.All the alloys are found to crystallize in an ordered B2-type structure at room temperature and the atoms of Fe are confirmed to all occupy at sites Mn(B).The total magnetic moments decrease gradually with increasing Fe content and decreasing of volume as well.The martensitic transformation temperature decreases with the increase of Fe content,whereas increases with increasing hydrostatic pressure.Moreover,obviously enhanced magnetocaloric performances can also be obtained by applied pressures.The maximum values of magnetic entropy change and refrigeration capacity are as high as 15.61(24.20)J(kg K)^(−1) and 109.91(347.26)J kg^(−1) withΔH=20(50)kOe,respectively.These magnetocaloric performances are superior to most of the recently reported famous materials,indicating the potential application for active MC.展开更多
基金the National Natural Science Foundation of China，Beijing Municipal Natural Science Foundation，the Key Project of Ministry of Industry and Information Technology，the National Youth Science Foundation
文摘In this paper, the energy-efficient power control problem in cognitive radio （CR） networks is studied not only to provide energy-efficient transmission, but also to guarantee the normal operation of primary users （PUs）. Moreover, the static energy-efficient power control （SEPC） algorithm is proposed in static scenario to maximize the capacity of secondary users （SUs） and to reduce the power consumption according to the interference from PU to SU. Furthermore, based on the analysis of PU＇s dynamic feature with Markov chain and SEPC algorithm,the dynamic energy-efficient power control （DEPC） algorithm is proposed taking into account the probability of detection and false alarm caused by sensing errors. Extensive simulation results show that the performance of the proposed algorithms is significantly improved compared with the existing algorithm.
基金supported by the National Natural Science Foundation of China(52001102 and 91963123)the Ten Thousand Talents Plan of Zhejiang Province of China(2018R52003)the Fundamental Research Funds for the Provincial University of Zhejiang(GK199900299012-022)。
文摘The solid-state magnetic cooling(MC)method based on the magnetocaloric effect(MCE)is recognized as an environmentally friendly and high-energy-efficiency technology.The search or design of suitable magnetic materials with large MCEs is one of the main targets at present.In this work,we apply the chemical and hydrostatic pressures in the Ni_(35)Co_(15)Mn_(35-x)Fe_(x)Ti_(15) all-d-metal Heusler alloys and systematically investigate their crystal structures,phases,and magnetocaloric performances experimentally and theoretically.All the alloys are found to crystallize in an ordered B2-type structure at room temperature and the atoms of Fe are confirmed to all occupy at sites Mn(B).The total magnetic moments decrease gradually with increasing Fe content and decreasing of volume as well.The martensitic transformation temperature decreases with the increase of Fe content,whereas increases with increasing hydrostatic pressure.Moreover,obviously enhanced magnetocaloric performances can also be obtained by applied pressures.The maximum values of magnetic entropy change and refrigeration capacity are as high as 15.61(24.20)J(kg K)^(−1) and 109.91(347.26)J kg^(−1) withΔH=20(50)kOe,respectively.These magnetocaloric performances are superior to most of the recently reported famous materials,indicating the potential application for active MC.
