双烟囱结构在自然风作用下存在气动干扰效应,从而诱发较大风致振动,威胁结构安全.合理计算和预测风振响应是双烟囱抗风设计的关键.以某中心距为8倍平均直径的双烟囱结构为研究对象,开展刚性模型测力和气弹模型测振风洞试验,将试验结果...双烟囱结构在自然风作用下存在气动干扰效应,从而诱发较大风致振动,威胁结构安全.合理计算和预测风振响应是双烟囱抗风设计的关键.以某中心距为8倍平均直径的双烟囱结构为研究对象,开展刚性模型测力和气弹模型测振风洞试验,将试验结果与中国规范、欧洲规范和CICIND(International Committee on Industrial Construction)规范计算值进行比较,详细研究双烟囱在不同风向角下的风致响应特性.研究结果表明:在烟囱串列布置下,迎风侧烟囱具有遮挡和干扰效应,一方面使得背风侧烟囱底部弯矩减小,另一方面使其横风向位移大于在其他风向角下的值;由于厂房的干扰效应,风振系数中国规范计算值与试验值接近;当烟囱高度超过厂房高度后,计算值较试验值偏大;对于横向响应,中国规范计算值较试验值大37.1%,欧洲规范计算值与试验值接近,仅偏小6.9%,CICIND规范计算值比试验值小17.1%.展开更多
Silicon(Si)is widely used as a lithium‐ion‐battery anode owing to its high capacity and abundant crustal reserves.However,large volume change upon cycling and poor conductivity of Si cause rapid capacity decay and p...Silicon(Si)is widely used as a lithium‐ion‐battery anode owing to its high capacity and abundant crustal reserves.However,large volume change upon cycling and poor conductivity of Si cause rapid capacity decay and poor fast‐charging capability limiting its commercial applications.Here,we propose a multilevel carbon architecture with vertical graphene sheets(VGSs)grown on surfaces of subnanoscopically and homogeneously dispersed Si–C composite nanospheres,which are subsequently embedded into a carbon matrix(C/VGSs@Si–C).Subnanoscopic C in the Si–C nanospheres,VGSs,and carbon matrix form a three‐dimensional conductive and robust network,which significantly improves the conductivity and suppresses the volume expansion of Si,thereby boosting charge transport and improving electrode stability.The VGSs with vast exposed edges considerably increase the contact area with the carbon matrix and supply directional transport channels through the entire material,which boosts charge transport.The carbon matrix encapsulates VGSs@Si–C to decrease the specific surface area and increase tap density,thus yielding high first Coulombic efficiency and electrode compaction density.Consequently,C/VGSs@Si–C delivers excellent Li‐ion storage performances under industrial electrode conditions.In particular,the full cells show high energy densities of 603.5 Wh kg^(−1)and 1685.5 Wh L^(−1)at 0.1 C and maintain 80.7%of the energy density at 3 C.展开更多
文摘双烟囱结构在自然风作用下存在气动干扰效应,从而诱发较大风致振动,威胁结构安全.合理计算和预测风振响应是双烟囱抗风设计的关键.以某中心距为8倍平均直径的双烟囱结构为研究对象,开展刚性模型测力和气弹模型测振风洞试验,将试验结果与中国规范、欧洲规范和CICIND(International Committee on Industrial Construction)规范计算值进行比较,详细研究双烟囱在不同风向角下的风致响应特性.研究结果表明:在烟囱串列布置下,迎风侧烟囱具有遮挡和干扰效应,一方面使得背风侧烟囱底部弯矩减小,另一方面使其横风向位移大于在其他风向角下的值;由于厂房的干扰效应,风振系数中国规范计算值与试验值接近;当烟囱高度超过厂房高度后,计算值较试验值偏大;对于横向响应,中国规范计算值较试验值大37.1%,欧洲规范计算值与试验值接近,仅偏小6.9%,CICIND规范计算值比试验值小17.1%.
基金Guangdong Basic and Applied Basic Research Foundation,Grant/Award Number:2020A1515110762Research Grants Council of the Hong Kong Special Administrative Region,China,Grant/Award Number:R6005‐20Shenzhen Key Laboratory of Advanced Energy Storage,Grant/Award Number:ZDSYS20220401141000001。
文摘Silicon(Si)is widely used as a lithium‐ion‐battery anode owing to its high capacity and abundant crustal reserves.However,large volume change upon cycling and poor conductivity of Si cause rapid capacity decay and poor fast‐charging capability limiting its commercial applications.Here,we propose a multilevel carbon architecture with vertical graphene sheets(VGSs)grown on surfaces of subnanoscopically and homogeneously dispersed Si–C composite nanospheres,which are subsequently embedded into a carbon matrix(C/VGSs@Si–C).Subnanoscopic C in the Si–C nanospheres,VGSs,and carbon matrix form a three‐dimensional conductive and robust network,which significantly improves the conductivity and suppresses the volume expansion of Si,thereby boosting charge transport and improving electrode stability.The VGSs with vast exposed edges considerably increase the contact area with the carbon matrix and supply directional transport channels through the entire material,which boosts charge transport.The carbon matrix encapsulates VGSs@Si–C to decrease the specific surface area and increase tap density,thus yielding high first Coulombic efficiency and electrode compaction density.Consequently,C/VGSs@Si–C delivers excellent Li‐ion storage performances under industrial electrode conditions.In particular,the full cells show high energy densities of 603.5 Wh kg^(−1)and 1685.5 Wh L^(−1)at 0.1 C and maintain 80.7%of the energy density at 3 C.
