This study attempts to investigate how the slippery surface of Nepenthes alata pitchers restricts the attachment ability of ant Camponotus japonicus Mayr, via climbing behavior observation and friction force measureme...This study attempts to investigate how the slippery surface of Nepenthes alata pitchers restricts the attachment ability of ant Camponotus japonicus Mayr, via climbing behavior observation and friction force measurement. Ants exhibited ineffective climbing behaviors and rather small friction forces when attached to upward-oriented slippery surfaces, but opposite phenomena were shown when on inverted surfaces. Friction forces of intact, claw tip-removed and pad-destroyed ants were measured on intact and de-waxed slippery surfaces, exploring the roles of wax crystals and lunate cells in restricting ant＇s attachment. On downward-directed slippery surfaces, greater forces were exhibited by intact and pad-destroyed ants; on the two slippery sur- faces, pad-destroyed ants presented slightly smaller forces and clawless ants generated considerably smaller forces. Somewhat different force was provided by clawless ants on upward and downward oriented slippery surfaces, and slightly higher force was shown when ants climbed on wax-removed surface. Results indicate that the lunate cells contribute greatly to decrease the friction force, whereas the wax crystals perform a supplementary role. Mechanical analysis suggests that the directionally growing lunate cells possess a sloped structure that effectively prevents the claw＇s mechanical interlock, reducing the ant＇s attachment ability considerably. Our conclusion supports a further interpretation of slippery surface＇s anti-attachment mecha- nism, also provides theoretical reference to develop biomimetic slippery plate to trap agricultural insect.展开更多
Through 5 years of phenological observations on Larix principis-rupprechtii Mayr. in primary seed orchard and studies on population and individuals of clones, the annual periodic phenological laws were revealed and th...Through 5 years of phenological observations on Larix principis-rupprechtii Mayr. in primary seed orchard and studies on population and individuals of clones, the annual periodic phenological laws were revealed and the annual phe-nological periodic table was drawn up. The correlation between various phenophases, the air temperature and active accumu-lated temperature were analyzed and expounded. The authors also analyzed the similarities and differences of phenophases among clonal individuals as well as the blooming properties of male and female flowers at the same time. This study could pro-vide theoretical reference for working out the production plan of improved varieties and other management measures in seed orchard of Larix principis-rupprechtii.展开更多
为研究多间隙灭弧结构遭雷电过电压击穿后熄灭工频续流电弧的能力,分析了多间隙灭弧室内的灭弧过程及可能的熄弧方式,并基于Mayr电弧模型理论,针对10 k V电压等级,建立了多间隙灭弧结构击穿后的电弧动态模型,计算了工频续流过零时电弧...为研究多间隙灭弧结构遭雷电过电压击穿后熄灭工频续流电弧的能力,分析了多间隙灭弧室内的灭弧过程及可能的熄弧方式,并基于Mayr电弧模型理论,针对10 k V电压等级,建立了多间隙灭弧结构击穿后的电弧动态模型,计算了工频续流过零时电弧的熄灭过程,对影响熄弧效果的因素进行了分析;最后利用冲击与工频续流试验相结合的联合试验平台对具有多间隙结构的装置进行了联合试验。仿真与试验结果表明:较小的时间常数以及较高的耗散功率有利于工频续流电弧的熄灭,而多间隙灭弧结构能拉长电弧的特点能同时满足以上两点要求;联合试验时,多间隙灭弧结构能在闪络后的续流阶段快速熄灭电弧,熄弧发生在续流的第一个过零点时刻,熄弧后随着工频电压的恢复,该结构不会发生再次击穿;由于电弧在工频续流阶段存在一定的弧道压降,可保证输电线路不会发生短路性过流保护引发的跳闸事故。展开更多
基金We acknowledge Zhao Lei （The State Key Labo- ratory of Tribology, TsingHua University） for helping in the SWLI examinations. We sincerely thank the National Natural Science Foundation of China （No. 51205107）, the Natural Science Foundation of Hebei province （No. E2014208056）, and the Tribology Science Fund of State Key Laboratory of Tribology （No. SKLTKF13B05） for their financial supports.
文摘This study attempts to investigate how the slippery surface of Nepenthes alata pitchers restricts the attachment ability of ant Camponotus japonicus Mayr, via climbing behavior observation and friction force measurement. Ants exhibited ineffective climbing behaviors and rather small friction forces when attached to upward-oriented slippery surfaces, but opposite phenomena were shown when on inverted surfaces. Friction forces of intact, claw tip-removed and pad-destroyed ants were measured on intact and de-waxed slippery surfaces, exploring the roles of wax crystals and lunate cells in restricting ant＇s attachment. On downward-directed slippery surfaces, greater forces were exhibited by intact and pad-destroyed ants; on the two slippery sur- faces, pad-destroyed ants presented slightly smaller forces and clawless ants generated considerably smaller forces. Somewhat different force was provided by clawless ants on upward and downward oriented slippery surfaces, and slightly higher force was shown when ants climbed on wax-removed surface. Results indicate that the lunate cells contribute greatly to decrease the friction force, whereas the wax crystals perform a supplementary role. Mechanical analysis suggests that the directionally growing lunate cells possess a sloped structure that effectively prevents the claw＇s mechanical interlock, reducing the ant＇s attachment ability considerably. Our conclusion supports a further interpretation of slippery surface＇s anti-attachment mecha- nism, also provides theoretical reference to develop biomimetic slippery plate to trap agricultural insect.
文摘Through 5 years of phenological observations on Larix principis-rupprechtii Mayr. in primary seed orchard and studies on population and individuals of clones, the annual periodic phenological laws were revealed and the annual phe-nological periodic table was drawn up. The correlation between various phenophases, the air temperature and active accumu-lated temperature were analyzed and expounded. The authors also analyzed the similarities and differences of phenophases among clonal individuals as well as the blooming properties of male and female flowers at the same time. This study could pro-vide theoretical reference for working out the production plan of improved varieties and other management measures in seed orchard of Larix principis-rupprechtii.
文摘为研究多间隙灭弧结构遭雷电过电压击穿后熄灭工频续流电弧的能力,分析了多间隙灭弧室内的灭弧过程及可能的熄弧方式,并基于Mayr电弧模型理论,针对10 k V电压等级,建立了多间隙灭弧结构击穿后的电弧动态模型,计算了工频续流过零时电弧的熄灭过程,对影响熄弧效果的因素进行了分析;最后利用冲击与工频续流试验相结合的联合试验平台对具有多间隙结构的装置进行了联合试验。仿真与试验结果表明:较小的时间常数以及较高的耗散功率有利于工频续流电弧的熄灭,而多间隙灭弧结构能拉长电弧的特点能同时满足以上两点要求;联合试验时,多间隙灭弧结构能在闪络后的续流阶段快速熄灭电弧,熄弧发生在续流的第一个过零点时刻,熄弧后随着工频电压的恢复,该结构不会发生再次击穿;由于电弧在工频续流阶段存在一定的弧道压降,可保证输电线路不会发生短路性过流保护引发的跳闸事故。
