As a constraint for smart devices,energy consumption has attract people's attention for a long time period. How to get higher resource utilization with less energy consumption is a challenge for cognitive radio ne...As a constraint for smart devices,energy consumption has attract people's attention for a long time period. How to get higher resource utilization with less energy consumption is a challenge for cognitive radio networks. Secondary users have to participate in spectrum sensing at the cost of energy and access idle spectrum without interfering primary users. However,not all participating secondary users can access idle spectrum. How to ensure the participation users access spectrum efficiently with a larger probability is an urgent problem to be solved. We propose an Energy Efficiency-based Decision Making(EEDM) for cognitive radio networks,which fully considers residual energy and probability of obtaining spectrum resources. Simulation and analysis show that the proposed scheme can maximize proportion of allocated users under the premise of ensuring the accuracy of spectrum sensing,then balance users' energy consumption and access efficiency,so as to effectively improve the utilization of spectrum resources.展开更多
Due to the good controllability and high energy efficiency in adsorption processes,photoresponsive adsorbents are intriguing for CO2 capture.Nevertheless,most reported photoresponsive adsorbents are designed based on ...Due to the good controllability and high energy efficiency in adsorption processes,photoresponsive adsorbents are intriguing for CO2 capture.Nevertheless,most reported photoresponsive adsorbents are designed based on weak adsorption sites,regulating CO2 adsorption through structural change or steric hindrance.In addition,ultraviolet(UV)light is commonly involved in the regulation of adsorption capacity.Here we report for the first time the smart adsorbents for CO2 capture,which makes strong adsorption sites respond to visible(Vis)light.The adsorbents were fabricated by introducing primary amine and Dispersed Red 1(DR1,a kind of push-pull azobenzene that responds to Vis light rapidly)units to mesoporous silica,which act as strong adsorption sites and triggers,respectively.The primary amine sites make the adsorbents highly selective in the adsorption of CO2 over CH4.Without light irradiation,azobenzene is in the form of trans configuration,which leads to decreased electrostatic potential of primary amines and subsequently,exposure of active sites and liberal adsorption of CO2.Upon Vis-light irradiation,cis isomers are formed,which results in increased electrostatic potential of primary amines and subsequently shelter of active sites.Even on such strong adsorption sites,the alteration of CO2 adsorption capacity can reach 40%for the adsorbent with and without Vis-light irradiation.Moreover,the trans/cis isomerization of DR1 units can be triggered reversibly by Vis light.The present smart system endows adsorbents with selective adsorption capacity and avoids the employment of UV light,which is unlikely to be achieved by conventional photoresponsive adsorbents.展开更多
基金supported by the National Natural Science Foundation of China (NO.61602358,No.61373170,NO.U1401251,No.U1536202)Fundamental Research Funds for the Central Universities(No.JB150114)the Natural Science Basic Research Plan in Shaanxi Province,China (No.2014JQ8308)
文摘As a constraint for smart devices,energy consumption has attract people's attention for a long time period. How to get higher resource utilization with less energy consumption is a challenge for cognitive radio networks. Secondary users have to participate in spectrum sensing at the cost of energy and access idle spectrum without interfering primary users. However,not all participating secondary users can access idle spectrum. How to ensure the participation users access spectrum efficiently with a larger probability is an urgent problem to be solved. We propose an Energy Efficiency-based Decision Making(EEDM) for cognitive radio networks,which fully considers residual energy and probability of obtaining spectrum resources. Simulation and analysis show that the proposed scheme can maximize proportion of allocated users under the premise of ensuring the accuracy of spectrum sensing,then balance users' energy consumption and access efficiency,so as to effectively improve the utilization of spectrum resources.
基金the Excellent Young Scientists Fund from the National Natural Science Foundation of China(21722606)the National Natural Science Foundation of China(21676138,21878149 and 21808110)China Postdoctoral Science Foundation(2018M632295 and 2019T120419)。
文摘Due to the good controllability and high energy efficiency in adsorption processes,photoresponsive adsorbents are intriguing for CO2 capture.Nevertheless,most reported photoresponsive adsorbents are designed based on weak adsorption sites,regulating CO2 adsorption through structural change or steric hindrance.In addition,ultraviolet(UV)light is commonly involved in the regulation of adsorption capacity.Here we report for the first time the smart adsorbents for CO2 capture,which makes strong adsorption sites respond to visible(Vis)light.The adsorbents were fabricated by introducing primary amine and Dispersed Red 1(DR1,a kind of push-pull azobenzene that responds to Vis light rapidly)units to mesoporous silica,which act as strong adsorption sites and triggers,respectively.The primary amine sites make the adsorbents highly selective in the adsorption of CO2 over CH4.Without light irradiation,azobenzene is in the form of trans configuration,which leads to decreased electrostatic potential of primary amines and subsequently,exposure of active sites and liberal adsorption of CO2.Upon Vis-light irradiation,cis isomers are formed,which results in increased electrostatic potential of primary amines and subsequently shelter of active sites.Even on such strong adsorption sites,the alteration of CO2 adsorption capacity can reach 40%for the adsorbent with and without Vis-light irradiation.Moreover,the trans/cis isomerization of DR1 units can be triggered reversibly by Vis light.The present smart system endows adsorbents with selective adsorption capacity and avoids the employment of UV light,which is unlikely to be achieved by conventional photoresponsive adsorbents.
