Current research on wind energy piezoelectric energy harvesters(PEHs)mainly focuses on tandem smooth cylinder energy harvesters;however,the traditional tandem smooth cylinder energy harvester has low voltage output an...Current research on wind energy piezoelectric energy harvesters(PEHs)mainly focuses on tandem smooth cylinder energy harvesters;however,the traditional tandem smooth cylinder energy harvester has low voltage output and narrow energy harvest bandwidth.In this study,a D-type bionic fin is designed and installed on a smooth cylindrical surface to improve its performance.The influence of the spacing ratio on the amplitude and voltage of PEHs with D-type bionic fins added under elastic interference was investigated through wind tunnel tests.Three installation positions were designed:only installed upstream,only installed downstream,and not installed upstream and downstream(BARE).It was found that the maximum displacement of the upstream PEH(UPEH)was not apparently affected by the D-type bionic fin.Contrastingly,the fin changed the maximum amplitude from a small to a large spacing ratio for the downstream PEH(DPEH).D-type bionic fin can enhance energy harvest performance by coupling“coupled vortex-induced vibration”and wake induced galloping,increasing the surface velocity of PEHs and expanding the bandwidth of the voltage harvested by the PEHs.Analysis of the power under the experimental wind speed showed that installing D-type fins in the PEHs can increase the output power of the upstream and downstream PEHs by 392.28%and 13%,respectively,compared with that of the BARE-PEH.Additionally,computational fluid dynamics was used to analyze the flow pattern,wake structure,and lift coefficient of the PEHs,and to explain why the upstream D-type bionic fin installation has an impact on the harvest performance of the upstream and downstream PEHs at a spacing ratio of 1.5.This study provides an efficient and simple scheme for designing wind PEHs.展开更多
In this study,four types of spiral fins with varying parameters were mounted on an upstream cylinder,and the effects of spiral fins on the vibration response of heat exchange tubes and the vortex structure in cross fl...In this study,four types of spiral fins with varying parameters were mounted on an upstream cylinder,and the effects of spiral fins on the vibration response of heat exchange tubes and the vortex structure in cross flow were studied through experiments and numerical simulations.The results indicate a strong dependency of the cylinder's vibration response on the fin parameters.The results indicate that the vibration response and wake structure of the cylinder are significantly influenced by the parameters of the fins.The introduction of a finned cylinder affects both its own vibration amplitude and frequency,as well as the downstream cylinder.The amplitudes of finned cylinders Ⅰ and Ⅲ are reduced by 57.8% and 59.9%,respectively,compared to the bare cylinder.This reduction helps to restrain vibration and diminishes the amplitudes of the downstream cylinder.Although finned cylinder Ⅱ slightly decreases its own vibration,it increases the amplitude of the downstream cylinder by 13.7%.The mean drag coefficient and the root mean square of the lift coefficient of the finned cylinder are higher than those of the bare cylinder when the finned cylinder is positioned upstream.Smaller pitch and larger equivalent diameter will lead to increased drag,resulting in enhanced vortex shedding in the wake,which amplifies the vibrations of the cylinder in that wake.The downstream of finned cylinder Ⅱ has the widest wake and higher vortex strength,and the dynamic load and vibration of the downstream cylinder are increased.The vortex intensity decays faster in the wake of finned cylinder Ⅲ,and the vibration of the downstream cylinder is weaker.展开更多
In this paper,we introduce the harmonic Hardy space on Tn and study some algebraic properties of dual Toeplitz operator on the harmonic Hardy space on Tn.
Blue emitting perovskite ink obtained from cesium lead halide quantum dots bearing chlorine(CsPbClxBr3-x,0<x<3)suffers from the low photoluminescence quantum yield and poor stability.Cesium lead bromine(CsPbBr3)...Blue emitting perovskite ink obtained from cesium lead halide quantum dots bearing chlorine(CsPbClxBr3-x,0<x<3)suffers from the low photoluminescence quantum yield and poor stability.Cesium lead bromine(CsPbBr3)quantum dots free of chlori ne have more stable crystalstructure and fewer crystal defects.Precise control of crystal sizes and surface passivation comporients of CsPbBr3 quantum dots is crucial for the best use of quantum confinement effect and blueshift of emission wavelength to blue region.Here,by polymerizing acrylamide under UV-light irradiation to form polymer gel networks in dimethyl sulfoxide(DMSO)with CsPbBr3 precursors and passivating agents trapped,wesuccessfully prepared novel sustained release tablets with different shapes and sizes.Thanks to the limitation of the polymer networks onsolve nt releasi ng,the resulting CsPbBr3 qua ntum dots have the average size of 1.1±0.2 nm.On the basis of the excelle nt quantum confin eme nteffect and optimized surface passivation,the obtained PQD ink can emit high quality blue light for more than 6 weeks.This work elucidates anew and convenient technique to prepare blue emission perovskite quantum dots ink with high stability and photoluminescence qua ntumyield and provides a great potential technology for the preparation of perovskite optoelectronic devices.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.21978202).
文摘Current research on wind energy piezoelectric energy harvesters(PEHs)mainly focuses on tandem smooth cylinder energy harvesters;however,the traditional tandem smooth cylinder energy harvester has low voltage output and narrow energy harvest bandwidth.In this study,a D-type bionic fin is designed and installed on a smooth cylindrical surface to improve its performance.The influence of the spacing ratio on the amplitude and voltage of PEHs with D-type bionic fins added under elastic interference was investigated through wind tunnel tests.Three installation positions were designed:only installed upstream,only installed downstream,and not installed upstream and downstream(BARE).It was found that the maximum displacement of the upstream PEH(UPEH)was not apparently affected by the D-type bionic fin.Contrastingly,the fin changed the maximum amplitude from a small to a large spacing ratio for the downstream PEH(DPEH).D-type bionic fin can enhance energy harvest performance by coupling“coupled vortex-induced vibration”and wake induced galloping,increasing the surface velocity of PEHs and expanding the bandwidth of the voltage harvested by the PEHs.Analysis of the power under the experimental wind speed showed that installing D-type fins in the PEHs can increase the output power of the upstream and downstream PEHs by 392.28%and 13%,respectively,compared with that of the BARE-PEH.Additionally,computational fluid dynamics was used to analyze the flow pattern,wake structure,and lift coefficient of the PEHs,and to explain why the upstream D-type bionic fin installation has an impact on the harvest performance of the upstream and downstream PEHs at a spacing ratio of 1.5.This study provides an efficient and simple scheme for designing wind PEHs.
基金financially supported by the National Natural Science Foundation of China(22478286)。
文摘In this study,four types of spiral fins with varying parameters were mounted on an upstream cylinder,and the effects of spiral fins on the vibration response of heat exchange tubes and the vortex structure in cross flow were studied through experiments and numerical simulations.The results indicate a strong dependency of the cylinder's vibration response on the fin parameters.The results indicate that the vibration response and wake structure of the cylinder are significantly influenced by the parameters of the fins.The introduction of a finned cylinder affects both its own vibration amplitude and frequency,as well as the downstream cylinder.The amplitudes of finned cylinders Ⅰ and Ⅲ are reduced by 57.8% and 59.9%,respectively,compared to the bare cylinder.This reduction helps to restrain vibration and diminishes the amplitudes of the downstream cylinder.Although finned cylinder Ⅱ slightly decreases its own vibration,it increases the amplitude of the downstream cylinder by 13.7%.The mean drag coefficient and the root mean square of the lift coefficient of the finned cylinder are higher than those of the bare cylinder when the finned cylinder is positioned upstream.Smaller pitch and larger equivalent diameter will lead to increased drag,resulting in enhanced vortex shedding in the wake,which amplifies the vibrations of the cylinder in that wake.The downstream of finned cylinder Ⅱ has the widest wake and higher vortex strength,and the dynamic load and vibration of the downstream cylinder are increased.The vortex intensity decays faster in the wake of finned cylinder Ⅲ,and the vibration of the downstream cylinder is weaker.
基金Supported by the National Natural Science Foundation of China(Grant Nos.1167106511301047)
文摘In this paper,we introduce the harmonic Hardy space on Tn and study some algebraic properties of dual Toeplitz operator on the harmonic Hardy space on Tn.
基金The work is supported by the National Natural Science Foundation of China(No.21761132007)the National Key R&D Program of China(No.2016YFE0114900).
文摘Blue emitting perovskite ink obtained from cesium lead halide quantum dots bearing chlorine(CsPbClxBr3-x,0<x<3)suffers from the low photoluminescence quantum yield and poor stability.Cesium lead bromine(CsPbBr3)quantum dots free of chlori ne have more stable crystalstructure and fewer crystal defects.Precise control of crystal sizes and surface passivation comporients of CsPbBr3 quantum dots is crucial for the best use of quantum confinement effect and blueshift of emission wavelength to blue region.Here,by polymerizing acrylamide under UV-light irradiation to form polymer gel networks in dimethyl sulfoxide(DMSO)with CsPbBr3 precursors and passivating agents trapped,wesuccessfully prepared novel sustained release tablets with different shapes and sizes.Thanks to the limitation of the polymer networks onsolve nt releasi ng,the resulting CsPbBr3 qua ntum dots have the average size of 1.1±0.2 nm.On the basis of the excelle nt quantum confin eme nteffect and optimized surface passivation,the obtained PQD ink can emit high quality blue light for more than 6 weeks.This work elucidates anew and convenient technique to prepare blue emission perovskite quantum dots ink with high stability and photoluminescence qua ntumyield and provides a great potential technology for the preparation of perovskite optoelectronic devices.
