压电俘能器能够为自然界中低功率的微机电系统持续供能.为了模拟机翼的沉浮-俯仰二自由度运动和有效俘获气动弹性振动能量,本文提出一种新颖的翼型颤振压电俘能器.基于非定常气动力模型,推导翼型颤振压电俘能器流-固-电耦合场的数学模型...压电俘能器能够为自然界中低功率的微机电系统持续供能.为了模拟机翼的沉浮-俯仰二自由度运动和有效俘获气动弹性振动能量,本文提出一种新颖的翼型颤振压电俘能器.基于非定常气动力模型,推导翼型颤振压电俘能器流-固-电耦合场的数学模型.建立有限元模型,模拟机翼的沉浮-俯仰二自由度运动,获得机翼附近的涡旋脱落和流场特性.搭建风洞实验系统,制作压电俘能器样机.利用实验验证理论和仿真模型的正确性,仿真分析压电俘能器结构参数对其气动弹性振动响应和俘获性能的影响.结果表明:理论分析、仿真模拟和实验研究获得的输出电压具有较好的一致性,验证建立数学和仿真模型的正确性.仿真分析获得机翼附近的压力场变化云图,表明交替的压力差驱动机翼发生二自由度沉浮-俯仰运动.当风速超过颤振起始速度时,压电俘能器发生颤振,并表现为极限环振荡.当偏心距为0.3和风速为16 m/s时,可获得最大输出电压为17.88 V和输出功率为1.278 m W.功率密度为7.99 m W/cm^(3),相比较于其他压电俘能器,能实现优越的俘获性能.研究结果对设计更高效的翼型颤振压电俘能器提供重要的指导意义.展开更多
Integrated data and energy transfer(IDET)enables the electromagnetic waves to transmit wireless energy at the same time of data delivery for lowpower devices.In this paper,an energy harvesting modulation(EHM)assisted ...Integrated data and energy transfer(IDET)enables the electromagnetic waves to transmit wireless energy at the same time of data delivery for lowpower devices.In this paper,an energy harvesting modulation(EHM)assisted multi-user IDET system is studied,where all the received signals at the users are exploited for energy harvesting without the degradation of wireless data transfer(WDT)performance.The joint IDET performance is then analysed theoretically by conceiving a practical time-dependent wireless channel.With the aid of the AO based algorithm,the average effective data rate among users are maximized by ensuring the BER and the wireless energy transfer(WET)performance.Simulation results validate and evaluate the IDET performance of the EHM assisted system,which also demonstrates that the optimal number of user clusters and IDET time slots should be allocated,in order to improve the WET and WDT performance.展开更多
Flotation is considered as an effective and energy efficient method for harvesting microalgae.However,the interaction mechanism between bubble-algae cell and cell-cell interfacial boundaries in microalgae flotation is...Flotation is considered as an effective and energy efficient method for harvesting microalgae.However,the interaction mechanism between bubble-algae cell and cell-cell interfacial boundaries in microalgae flotation is not completely clear.To better understand the effects of surface characteristics on microalgae flotation performance,the hydrophobicity and the zeta potential of two different microalgae species were quantified based on experimental measurements and the extended DLVO(Derjagin–Landau–Verwey–Overbeek)theory.Flotation experiments were then carried out and the effects of surface characteristics on microalgae flotation performance were analyzed.Algae Chlorella vulgaris and Anabaena vasriabilis show naturally hydrophilic and hydrophobic properties,respectively.The addition of a cationic surfactant(C16TAB)can modify hydrophilic microalgae cells into hydrophobic and further Chlorella hydrophobicity is enhanced with increased C16TAB concentrations.The zeta potentials of both algae strains are negative in the tested pH range.Compared with Chlorella vulgaris,the magnitude of zeta potential of Anabaena vasriabilis is found larger at the same pH,resulting in a more dispersed distribution in the suspension.In addition,flotation experiments demonstrated that microalgae hydrophobicity and zeta potential have significant impacts on the harvesting efficiency and concentration factor.The hydrophobic attraction is found to play a more important role in determining the harvesting performance than electrostatic repulsion between the interacting surfaces,especially for hydrophobicity algae in the present study.Finally,the highest flotation efficiency and the highest concentration factor could not be concurrently obtained for both algae strains,suggesting that optimized flotation conditions should be selected as a compromise.展开更多
文摘压电俘能器能够为自然界中低功率的微机电系统持续供能.为了模拟机翼的沉浮-俯仰二自由度运动和有效俘获气动弹性振动能量,本文提出一种新颖的翼型颤振压电俘能器.基于非定常气动力模型,推导翼型颤振压电俘能器流-固-电耦合场的数学模型.建立有限元模型,模拟机翼的沉浮-俯仰二自由度运动,获得机翼附近的涡旋脱落和流场特性.搭建风洞实验系统,制作压电俘能器样机.利用实验验证理论和仿真模型的正确性,仿真分析压电俘能器结构参数对其气动弹性振动响应和俘获性能的影响.结果表明:理论分析、仿真模拟和实验研究获得的输出电压具有较好的一致性,验证建立数学和仿真模型的正确性.仿真分析获得机翼附近的压力场变化云图,表明交替的压力差驱动机翼发生二自由度沉浮-俯仰运动.当风速超过颤振起始速度时,压电俘能器发生颤振,并表现为极限环振荡.当偏心距为0.3和风速为16 m/s时,可获得最大输出电压为17.88 V和输出功率为1.278 m W.功率密度为7.99 m W/cm^(3),相比较于其他压电俘能器,能实现优越的俘获性能.研究结果对设计更高效的翼型颤振压电俘能器提供重要的指导意义.
基金supported in part by the MOST Major Research and Development Project(Grant No.2021YFB2900204)the National Natural Science Foundation of China(NSFC)(Grant No.62201123,No.62132004,No.61971102)+3 种基金China Postdoctoral Science Foundation(Grant No.2022TQ0056)in part by the financial support of the Sichuan Science and Technology Program(Grant No.2022YFH0022)Sichuan Major R&D Project(Grant No.22QYCX0168)the Municipal Government of Quzhou(Grant No.2022D031)。
文摘Integrated data and energy transfer(IDET)enables the electromagnetic waves to transmit wireless energy at the same time of data delivery for lowpower devices.In this paper,an energy harvesting modulation(EHM)assisted multi-user IDET system is studied,where all the received signals at the users are exploited for energy harvesting without the degradation of wireless data transfer(WDT)performance.The joint IDET performance is then analysed theoretically by conceiving a practical time-dependent wireless channel.With the aid of the AO based algorithm,the average effective data rate among users are maximized by ensuring the BER and the wireless energy transfer(WET)performance.Simulation results validate and evaluate the IDET performance of the EHM assisted system,which also demonstrates that the optimal number of user clusters and IDET time slots should be allocated,in order to improve the WET and WDT performance.
基金the National Natural Science Foundation of China(41230314,51208059)the Special Fund for basic Scientific Research of Central Colleges,Chang’an University(310829163406).
文摘Flotation is considered as an effective and energy efficient method for harvesting microalgae.However,the interaction mechanism between bubble-algae cell and cell-cell interfacial boundaries in microalgae flotation is not completely clear.To better understand the effects of surface characteristics on microalgae flotation performance,the hydrophobicity and the zeta potential of two different microalgae species were quantified based on experimental measurements and the extended DLVO(Derjagin–Landau–Verwey–Overbeek)theory.Flotation experiments were then carried out and the effects of surface characteristics on microalgae flotation performance were analyzed.Algae Chlorella vulgaris and Anabaena vasriabilis show naturally hydrophilic and hydrophobic properties,respectively.The addition of a cationic surfactant(C16TAB)can modify hydrophilic microalgae cells into hydrophobic and further Chlorella hydrophobicity is enhanced with increased C16TAB concentrations.The zeta potentials of both algae strains are negative in the tested pH range.Compared with Chlorella vulgaris,the magnitude of zeta potential of Anabaena vasriabilis is found larger at the same pH,resulting in a more dispersed distribution in the suspension.In addition,flotation experiments demonstrated that microalgae hydrophobicity and zeta potential have significant impacts on the harvesting efficiency and concentration factor.The hydrophobic attraction is found to play a more important role in determining the harvesting performance than electrostatic repulsion between the interacting surfaces,especially for hydrophobicity algae in the present study.Finally,the highest flotation efficiency and the highest concentration factor could not be concurrently obtained for both algae strains,suggesting that optimized flotation conditions should be selected as a compromise.
