This study focused on differences in vehicle-to-vehicle radio channel characteristics in the same region but different traffic density and speeds at 5.9 GHz(congestion and non-congestion). The continuous measurement c...This study focused on differences in vehicle-to-vehicle radio channel characteristics in the same region but different traffic density and speeds at 5.9 GHz(congestion and non-congestion). The continuous measurement campaign was conducted on a city expressway through the complex dense urban area in Wuhan, China. Small-scale channel characteristics including power delay profile, amplitude fading distribution, K-factor, delay spread and Doppler shift were obtained, respectively. Specifically, the cumulative distribution function of root mean square delay spreads and root mean square Doppler spreads in the non-congested scenario and congested scenario were all fitted well with Lognormal distribution. We also found out that different intensity of traffic and speed of vehicles have little effect on root mean square delay spreads, but have a big impact on root mean square Doppler spreads and level crossing rate. According to estimation outcomes, the V2 V channel characteristics for urban areas in Chinese big city were different from the previous measured results under similar scenarios in Europe. Delay spread and level crossing rate in this study can provide significant references to design the wireless communication system for vehicle-to-vehicle channel.展开更多
Metallic nanostructures are becoming increasingly important for both fundamental research and practical devices.Many emerging applications employing metallic nanostructures often involve unconventional substrates that...Metallic nanostructures are becoming increasingly important for both fundamental research and practical devices.Many emerging applications employing metallic nanostructures often involve unconventional substrates that are flexible or nonplanar,making direct lithographic fabrication very difficult.An alternative approach is to transfer prefabricated structures from a conventional substrate;however,it is still challenging to maintain high fidelity and a high yield in the transfer process.In this paper,we propose a high-fidelity,clean nanotransfer lithography method that addresses the above challenges by employing a polyvinyl acetate(PVA)film as the transferring carrier and promoting electrostatic adhesion through triboelectric charging.The PVA film embeds the transferred metallic nanostructures and maintains their spacing with a remarkably low variation of<1%.When separating the PVA film from the donor substrate,electrostatic charges are generated due to triboelectric charging and facilitate adhesion to the receiver substrate,resulting in a high large-area transfer yield of up to 99.93%.We successfully transferred the metallic structures of a variety of materials(Au,Cu,Pd,etc.)with different geometries with a<50-nm spacing,high aspect ratio(>2),and complex 3D structures.Moreover,the thin and flexible carrier film enables transfer on highly curved surfaces,such as a single-mode optical fiber with a curvature radius of 62.5μm.With this strategy,we demonstrate the transfer of metallic nanostructures for a compact spectrometer with Cu nanogratings transferred on a convex lens and for surface-enhanced Raman spectroscopy(SERS)characterization on graphene with reliable responsiveness.展开更多
基金supported by Norwegian Research Council(No.256309)supported by an International Cooperation Project:5G-Channel Measurement and Channel Modeling for Ocean Scenario(No.20172h0046)+3 种基金Hubei college excellent young science and technology innovation team project:Fast Varying Channel Modeling and Analysis(No.T201736)Young Scientists Found of National Natural Science Foundation of China(No.61701356)Fundamental Research Funds for the Central Universities(No.2017-JL-004)(China Scholarship Council) CSC agency for funding and the Super Radio AS
文摘This study focused on differences in vehicle-to-vehicle radio channel characteristics in the same region but different traffic density and speeds at 5.9 GHz(congestion and non-congestion). The continuous measurement campaign was conducted on a city expressway through the complex dense urban area in Wuhan, China. Small-scale channel characteristics including power delay profile, amplitude fading distribution, K-factor, delay spread and Doppler shift were obtained, respectively. Specifically, the cumulative distribution function of root mean square delay spreads and root mean square Doppler spreads in the non-congested scenario and congested scenario were all fitted well with Lognormal distribution. We also found out that different intensity of traffic and speed of vehicles have little effect on root mean square delay spreads, but have a big impact on root mean square Doppler spreads and level crossing rate. According to estimation outcomes, the V2 V channel characteristics for urban areas in Chinese big city were different from the previous measured results under similar scenarios in Europe. Delay spread and level crossing rate in this study can provide significant references to design the wireless communication system for vehicle-to-vehicle channel.
基金supported by the Research Grants Council of the Hong Kong Special Administrative Region (Awards No.17207419,17209320,C7018-20G,and AoE/P-701/20)the Platform Technology Funding programme,and the Seed Funding Programme for Basic Research (202011159235 and 202010160046)of the University of Hong KongShenzhen Government (Grant No.K20799112).
文摘Metallic nanostructures are becoming increasingly important for both fundamental research and practical devices.Many emerging applications employing metallic nanostructures often involve unconventional substrates that are flexible or nonplanar,making direct lithographic fabrication very difficult.An alternative approach is to transfer prefabricated structures from a conventional substrate;however,it is still challenging to maintain high fidelity and a high yield in the transfer process.In this paper,we propose a high-fidelity,clean nanotransfer lithography method that addresses the above challenges by employing a polyvinyl acetate(PVA)film as the transferring carrier and promoting electrostatic adhesion through triboelectric charging.The PVA film embeds the transferred metallic nanostructures and maintains their spacing with a remarkably low variation of<1%.When separating the PVA film from the donor substrate,electrostatic charges are generated due to triboelectric charging and facilitate adhesion to the receiver substrate,resulting in a high large-area transfer yield of up to 99.93%.We successfully transferred the metallic structures of a variety of materials(Au,Cu,Pd,etc.)with different geometries with a<50-nm spacing,high aspect ratio(>2),and complex 3D structures.Moreover,the thin and flexible carrier film enables transfer on highly curved surfaces,such as a single-mode optical fiber with a curvature radius of 62.5μm.With this strategy,we demonstrate the transfer of metallic nanostructures for a compact spectrometer with Cu nanogratings transferred on a convex lens and for surface-enhanced Raman spectroscopy(SERS)characterization on graphene with reliable responsiveness.
