针对我国大部分海域处于低流速区的情况,设计了针对低流速的小功率海流能发电能量收集系统,实现了发电机能量捕获、电能存储及负载供电控制和数据信息的采集记录。通过调节DC-DC电路输出电流,用最大功率跟踪(Maximum Power Point Tracki...针对我国大部分海域处于低流速区的情况,设计了针对低流速的小功率海流能发电能量收集系统,实现了发电机能量捕获、电能存储及负载供电控制和数据信息的采集记录。通过调节DC-DC电路输出电流,用最大功率跟踪(Maximum Power Point Tracking,MPPT)的方法,避免了传统调节方式存在对控制要求高,效率低的弊端,提高了系统的稳定性和效率。实验测试表明,系统功能满足设计要求,具有一定的应用参考价值。展开更多
Photochromic and photoluminescence materials show bright colors under different excitation conditions,and thus,these functional materials have been applied in many fields.Based on the photochromic and photoluminescenc...Photochromic and photoluminescence materials show bright colors under different excitation conditions,and thus,these functional materials have been applied in many fields.Based on the photochromic and photoluminescence theories,a block copolymer,which could be directly processed into nanofibers by electrospinning,was successfully prepared through atom transfer radical polymerization(ATRP).To synthesize the block copolymer,a vinyl monomer containing a spiropyran unit was employed to prepare the photochromic chain segment,and a polymethyl methacrylate(PMMA)chain segment was introduced to improve the processability of the block copolymer.Acting as the photoluminescence unit,the rare earth complex was linked to the side chain through coordination bonding between the rare earth ions and the ester groups of PMMA.When the photochromic and photoluminescence block copolymer was exposed to different wavelengths of ultraviolet(UV)light and visible(Vis)light,it could show white,red,green,yellow,and blue-purple.These results provide the potential of the as-prepared photochromic and photoluminescence block copolymer for application in fibers and fabrics.展开更多
A polarized reconfigurable patch antenna is proposed in this paper.The proposed antenna is a dual cross-polarized patch antenna with a programmable power divider.The programmable power divider consists of two branch l...A polarized reconfigurable patch antenna is proposed in this paper.The proposed antenna is a dual cross-polarized patch antenna with a programmable power divider.The programmable power divider consists of two branch line couplers(BLC)and a digital phase shifter.By adjusting the phase of the phase shifter,the power ratio of the power divider can be changed,and thus the feed power to the antenna input port can be changed to reconfigure the antenna polarization.The phase-controlled power divider and the cross dual-polarized antenna are designed,fabricated and tested,and then they are combined to realize the polarized reconfigurable antenna.By moving the phase of the phase shifter,the antenna polarization is reconfigured into vertical polarization(VP),horizontal polarization(HP),and circular polarization(CP).The test is conducted at the frequency of 915 MHz,which is widely used for simultaneous wireless information and power transfer(SWIPT)in radio-frequency identification(RFID)applications.The results demonstrate that when the antenna is configured as CP,the axial ratio of the antenna is less than 3 dB,and when the antenna is configured as HP or VP,the axial ratio of the antenna exceeds 20 dB.Finally,experiments are conducted to verify the influence of antenna polarization changes on wireless power transmitting.As expected,the reconfigured antenna polarization can help improve the power transmitting efficiency.展开更多
文摘针对我国大部分海域处于低流速区的情况,设计了针对低流速的小功率海流能发电能量收集系统,实现了发电机能量捕获、电能存储及负载供电控制和数据信息的采集记录。通过调节DC-DC电路输出电流,用最大功率跟踪(Maximum Power Point Tracking,MPPT)的方法,避免了传统调节方式存在对控制要求高,效率低的弊端,提高了系统的稳定性和效率。实验测试表明,系统功能满足设计要求,具有一定的应用参考价值。
基金Application Fundamental and Advanced Technology Research Proposal Project of Tianjin,China(No.18JCZDJC38300)。
文摘Photochromic and photoluminescence materials show bright colors under different excitation conditions,and thus,these functional materials have been applied in many fields.Based on the photochromic and photoluminescence theories,a block copolymer,which could be directly processed into nanofibers by electrospinning,was successfully prepared through atom transfer radical polymerization(ATRP).To synthesize the block copolymer,a vinyl monomer containing a spiropyran unit was employed to prepare the photochromic chain segment,and a polymethyl methacrylate(PMMA)chain segment was introduced to improve the processability of the block copolymer.Acting as the photoluminescence unit,the rare earth complex was linked to the side chain through coordination bonding between the rare earth ions and the ester groups of PMMA.When the photochromic and photoluminescence block copolymer was exposed to different wavelengths of ultraviolet(UV)light and visible(Vis)light,it could show white,red,green,yellow,and blue-purple.These results provide the potential of the as-prepared photochromic and photoluminescence block copolymer for application in fibers and fabrics.
文摘A polarized reconfigurable patch antenna is proposed in this paper.The proposed antenna is a dual cross-polarized patch antenna with a programmable power divider.The programmable power divider consists of two branch line couplers(BLC)and a digital phase shifter.By adjusting the phase of the phase shifter,the power ratio of the power divider can be changed,and thus the feed power to the antenna input port can be changed to reconfigure the antenna polarization.The phase-controlled power divider and the cross dual-polarized antenna are designed,fabricated and tested,and then they are combined to realize the polarized reconfigurable antenna.By moving the phase of the phase shifter,the antenna polarization is reconfigured into vertical polarization(VP),horizontal polarization(HP),and circular polarization(CP).The test is conducted at the frequency of 915 MHz,which is widely used for simultaneous wireless information and power transfer(SWIPT)in radio-frequency identification(RFID)applications.The results demonstrate that when the antenna is configured as CP,the axial ratio of the antenna is less than 3 dB,and when the antenna is configured as HP or VP,the axial ratio of the antenna exceeds 20 dB.Finally,experiments are conducted to verify the influence of antenna polarization changes on wireless power transmitting.As expected,the reconfigured antenna polarization can help improve the power transmitting efficiency.
