We developed a new scheme to suppress the electric-field-screening effect in high growth density of a carbon nanotube(CNT) film during its intense pulsed emission.We synthesize the CNT film on a tridimensional surface...We developed a new scheme to suppress the electric-field-screening effect in high growth density of a carbon nanotube(CNT) film during its intense pulsed emission.We synthesize the CNT film on a tridimensional surface(t-CNT film).The tridimensional surface includes wet etched silicon pyramids,and the Ni layer is electroless plated thereon.The intense pulsed emission characteristics of the t-CNT and planar-grown CNT(p-CNT) films were measured using a diode structure in single-pulse mode.The even turn-on field decreased from 5.5 V/μm for p-CNTs to 2.8 V/m for t-CNTs,and the peak emission current increased from 232 A for p-CNTs to 324 A for t-CNTs at a peak field intensity ～12.2 V/m.The peak current of the t-CNT film increased by ～39.7% over the p-CNT film.It is clear that the micro-pyramid array can effectively suppress the field screening effect to improve the electron-emission of CNT films.展开更多
Nowadays,daily human life is closely intertwined with various networks.When natural disasters or malicious attacks break out,the failure of communication infrastructure due to direct destruction or indirect impact ten...Nowadays,daily human life is closely intertwined with various networks.When natural disasters or malicious attacks break out,the failure of communication infrastructure due to direct destruction or indirect impact tends to cause a massive outage of communications.Emergency communication networks play a significant role in rescue operations.Recently,a flexible and efficient solution has been provided for emergency communications using unmanned aerial vehicles(UAVs).By means of their excellent characteristics,UAVs,serving as aerial base stations(ABSs),can be rapidly deployed to temporarily rebuild a damaged communication network to restore the users’connectivity.In this study,we investigate the use of UAVs as ABSs for an emergency communication scene where user equipment is unevenly distributed and the communication infrastructure has completely failed due to a severe disaster.Effective communication probability(ECP),which integrates throughput coverage and connectivity,is used to evaluate the performance of a communication network.Through simulations,we analyze communication improvements that can be obtained by the flexible deployment of ABSs.The results show a noticeable increase in ECP when some ABSs are deployed in optimal locations.展开更多
基金supported by the National Natural Science Foundation of China (51072184,50972132,51002143 and 60801022)the Aeronautical Science Foundation of China (2009ZE55003 and 2010ZF55013)the Basic and Advanced Technology Program of Henan (092300410139)
文摘We developed a new scheme to suppress the electric-field-screening effect in high growth density of a carbon nanotube(CNT) film during its intense pulsed emission.We synthesize the CNT film on a tridimensional surface(t-CNT film).The tridimensional surface includes wet etched silicon pyramids,and the Ni layer is electroless plated thereon.The intense pulsed emission characteristics of the t-CNT and planar-grown CNT(p-CNT) films were measured using a diode structure in single-pulse mode.The even turn-on field decreased from 5.5 V/μm for p-CNTs to 2.8 V/m for t-CNTs,and the peak emission current increased from 232 A for p-CNTs to 324 A for t-CNTs at a peak field intensity ～12.2 V/m.The peak current of the t-CNT film increased by ～39.7% over the p-CNT film.It is clear that the micro-pyramid array can effectively suppress the field screening effect to improve the electron-emission of CNT films.
基金This work was supported by the National Natural Science Foundation of China(No.61573310)。
文摘Nowadays,daily human life is closely intertwined with various networks.When natural disasters or malicious attacks break out,the failure of communication infrastructure due to direct destruction or indirect impact tends to cause a massive outage of communications.Emergency communication networks play a significant role in rescue operations.Recently,a flexible and efficient solution has been provided for emergency communications using unmanned aerial vehicles(UAVs).By means of their excellent characteristics,UAVs,serving as aerial base stations(ABSs),can be rapidly deployed to temporarily rebuild a damaged communication network to restore the users’connectivity.In this study,we investigate the use of UAVs as ABSs for an emergency communication scene where user equipment is unevenly distributed and the communication infrastructure has completely failed due to a severe disaster.Effective communication probability(ECP),which integrates throughput coverage and connectivity,is used to evaluate the performance of a communication network.Through simulations,we analyze communication improvements that can be obtained by the flexible deployment of ABSs.The results show a noticeable increase in ECP when some ABSs are deployed in optimal locations.
