Gold nanoparticle arrays fabricated via layerby-layer technique were investigated using grazing-incidence small-angle X-ray scattering(GISAXS) method.Samples containing two gold nanoparticle layers that were separated...Gold nanoparticle arrays fabricated via layerby-layer technique were investigated using grazing-incidence small-angle X-ray scattering(GISAXS) method.Samples containing two gold nanoparticle layers that were separated by 5,11,15 and 21 poly electrolyte(PE) interlayers were studied.By using different X-ray incident angles,correlations of gold nanoparticles(GNPs) in the same layer and in two different layers were investigated.It is found that both sideway correlations between GNPs in the same layer and vertical correlation between two gold nanoparticle layers depend on the thickness of PE interlayers.According to sideway correlation,the size of GNPs is determined to be(13.0±0.5) nm in all of the four samples,which was also proved by scanning electron microscopy(SEM) and theoretical calculation of form factor of spherical particles.From vertical correlation,distance between two gold nanoparticle layers was determined for sample with 11,15 and 21 PE layers.These distances can be reasonably explained with the number of PE layers and the thickness of single PE layer.These results indicate that by repeated depositing of oppositely charged PE layers,a true three-dimensional(3 D) nanostructure can eventually be designed.展开更多
In this paper,a massive multiple input multiple output(MIMO)channel measurement campaign with two setups is conducted in an indoor lobby environment.In the first setup,two types of 256-element virtual uniform rectangu...In this paper,a massive multiple input multiple output(MIMO)channel measurement campaign with two setups is conducted in an indoor lobby environment.In the first setup,two types of 256-element virtual uniform rectangular arrays(URAs),i.e.,the 4×64 virtual URA and the 64×4 virtual URA are used.The carrier frequency is 11 GHz;in the second setup,measurements are performed at 4,6,11,13,15,18 GHz at two different user locations.The channel characterization is presented by investigating the typical channel parameters,including average power delay profile(APDP),K factor,root mean square(RMS)delay spread,and coherence bandwidth.Moreover,the channel characteristics in angular domain are investigated by applying the space-alternating generalized expectation-maximization(SAGE)algorithm.The extracted multipath components(MPCs)are preliminarily clustered by visual inspection,and related to the interacting objects(IOs)in physical environment.Multipath structures at multiple frequency bands are examined.Direction spread of departure is estimated to evaluate the directional dispersion at the base station(BS)side.The results in this paper can help to reveal the propagation mechanisms in massive MIMO channels,and provide a foundation for the design and application of the practical massive MIMO system.展开更多
基金financially supported by the Framework Programme 7 Project NANOGOLD (No.ERAS-989409)。
文摘Gold nanoparticle arrays fabricated via layerby-layer technique were investigated using grazing-incidence small-angle X-ray scattering(GISAXS) method.Samples containing two gold nanoparticle layers that were separated by 5,11,15 and 21 poly electrolyte(PE) interlayers were studied.By using different X-ray incident angles,correlations of gold nanoparticles(GNPs) in the same layer and in two different layers were investigated.It is found that both sideway correlations between GNPs in the same layer and vertical correlation between two gold nanoparticle layers depend on the thickness of PE interlayers.According to sideway correlation,the size of GNPs is determined to be(13.0±0.5) nm in all of the four samples,which was also proved by scanning electron microscopy(SEM) and theoretical calculation of form factor of spherical particles.From vertical correlation,distance between two gold nanoparticle layers was determined for sample with 11,15 and 21 PE layers.These distances can be reasonably explained with the number of PE layers and the thickness of single PE layer.These results indicate that by repeated depositing of oppositely charged PE layers,a true three-dimensional(3 D) nanostructure can eventually be designed.
基金supported in part by the National Key Research and Development Program of China under Grant 2016YFE0200900 and 2018YFF0212103in part by NSFC under Grant 61725101, 61771037, 6181101396, and U1834210+4 种基金in part by the Beijing Natural Science Foundation under Grant 4182047 and L172020in part by the Fundamental research funds for the central universities under Grant 2017RC031 and Grant 2018JBM301in part by the Major projects of Beijing Municipal Science and Technology Commission under Grant Z181100003218010in part by the State Key Lab of Rail Traffic Control and Safety under Grant 2017JBM332, RCS2018ZZ007, and Grant RCS2018ZT014in part by the Teaching Reform Project under Grant 134496522
文摘In this paper,a massive multiple input multiple output(MIMO)channel measurement campaign with two setups is conducted in an indoor lobby environment.In the first setup,two types of 256-element virtual uniform rectangular arrays(URAs),i.e.,the 4×64 virtual URA and the 64×4 virtual URA are used.The carrier frequency is 11 GHz;in the second setup,measurements are performed at 4,6,11,13,15,18 GHz at two different user locations.The channel characterization is presented by investigating the typical channel parameters,including average power delay profile(APDP),K factor,root mean square(RMS)delay spread,and coherence bandwidth.Moreover,the channel characteristics in angular domain are investigated by applying the space-alternating generalized expectation-maximization(SAGE)algorithm.The extracted multipath components(MPCs)are preliminarily clustered by visual inspection,and related to the interacting objects(IOs)in physical environment.Multipath structures at multiple frequency bands are examined.Direction spread of departure is estimated to evaluate the directional dispersion at the base station(BS)side.The results in this paper can help to reveal the propagation mechanisms in massive MIMO channels,and provide a foundation for the design and application of the practical massive MIMO system.
