Capacity enhancement approaches are being intensively studied in the past few years to address the soaring capacity demands. The network densif ication technology is recognized as one promising solution. However,the u...Capacity enhancement approaches are being intensively studied in the past few years to address the soaring capacity demands. The network densif ication technology is recognized as one promising solution. However,the ultra-dense network scheme suffers from severe interference and frequent handovers,which degrade the system performance significantly. In this paper,a virtual sectorization system leveraging a C-plane(control signaling plane) and U-plane(user data plane) split scheme is proposed to overcome these two fundamental problems. Besides,a well-designed fi eld trial is conducted to evaluate its performance. The results show that the interference can be avoided,which leads to a tremendous increase in system capacity. In addition,the number of handovers is also greatly decreased. Thus,the trial results verify the huge potential of the C-plane and U-plane split scheme for system capacity and user experience enhancements.展开更多
The method of splitting a plane-wave finite-difference time-domain （SP-FDTD） algorithm is presented for the initiation of plane-wave source in the total-field / scattered-field （TF/SF） formulation of high-order sy...The method of splitting a plane-wave finite-difference time-domain （SP-FDTD） algorithm is presented for the initiation of plane-wave source in the total-field / scattered-field （TF/SF） formulation of high-order symplectic finite- difference time-domain （SFDTD） scheme for the first time. By splitting the fields on one-dimensional grid and using the nature of numerical plane-wave in finite-difference time-domain （FDTD）, the identical dispersion relation can be obtained and proved between the one-dimensional and three-dimensional grids. An efficient plane-wave source is simulated on one-dimensional grid and a perfect match can be achieved for a plane-wave propagating at any angle forming an integer grid cell ratio. Numerical simulations show that the method is valid for SFDTD and the residual field in SF region is shrinked down to -300 dB.展开更多
This study presents a new, simple method for reducing the back-lobe radiation of a microstrip antenna (MSA) by a partially removed ground plane of the antenna. The effect of the partial ground plane removal in differe...This study presents a new, simple method for reducing the back-lobe radiation of a microstrip antenna (MSA) by a partially removed ground plane of the antenna. The effect of the partial ground plane removal in different configurations on the radiation characteristics of a MSA are investigated numerically. The partial ground plane removal reduces the backlobe radiation of the MSA by suppressing the surface wave diffraction from the edges of the antenna ground plane. For further improving the front-to-back (F/B) ratio of the MSA, a new soft-surface configuration consisting of an array of stand-up split ring resonators (SRRs) are placed on a bare dielectric substrate near the two ground plane edges. Compared to the F/B ratio of a conventional MSA with a full ground plane of the same size, an improved F/B ratio of 9.7 dB has been achieved experimentally for our proposed MSA.展开更多
The in-plane tensile behaviors of bi-axial warp-knitted(BWK) composites under quasi-static and high strain rates loading were experimentally analyzed in this article. The tensile tests were conducted along warp direct...The in-plane tensile behaviors of bi-axial warp-knitted(BWK) composites under quasi-static and high strain rates loading were experimentally analyzed in this article. The tensile tests were conducted along warp direction( 0°) and weft direction( 90°) at quasi-static rate of 0. 001 s^(-1) and high strain rates ranging from 1 450 to 2 540 s^(-1),respectively. It is found that the significant strain rate sensitivity can be observed in the stress-strain curves of BWK composites. The fracture morphologies of BWK composites demonstrate that the tensile failure modes are shear failure and fiber breakage under the quasi-static testing condition while interface failure and fibers pullout are at high strain rates.展开更多
应用分裂平面波时域有限差分(Splitting Plane wave Finite Difference Time Domain,SP-FDTD)方法到三维时域有限差分(Finite Difference Time Domain,DFDTD)中引入高效平面波源.该方法基于分裂场思想,在一维FDTD上构造了新的迭代公式,...应用分裂平面波时域有限差分(Splitting Plane wave Finite Difference Time Domain,SP-FDTD)方法到三维时域有限差分(Finite Difference Time Domain,DFDTD)中引入高效平面波源.该方法基于分裂场思想,在一维FDTD上构造了新的迭代公式,使得一维FDTD和三维FDTD离散网格之间的数值相速度一致,消除了由于相速不一致而在总场区引起的泄漏误差以及插值带来的数值误差.通过数值算例验证了SP-FDTD方法对不同波源在任意角度(斜入射)下的平面波入射都是有效的,且泄露误差均在-300dB水平.展开更多
针对目前遥感商用软件影像镶嵌过程中人工干预过多、自动化程度不高和不易修改等问题,提出了基于平面剖分的遥感影像镶嵌模型。模型基于开源类库空间数据抽象库(geospatial data abstraction library,GDAL),在GNU/Linux平台下,使用Pytho...针对目前遥感商用软件影像镶嵌过程中人工干预过多、自动化程度不高和不易修改等问题,提出了基于平面剖分的遥感影像镶嵌模型。模型基于开源类库空间数据抽象库(geospatial data abstraction library,GDAL),在GNU/Linux平台下,使用Python语言,实现了遥感影像按研究区域进行掩模及镶嵌的功能,并采用模型—视图—控制器(model view controller,MVC)的设计模式,应用跨平台的图形用户界面(graphical user interface,GUI)库wx Python实现了软件的封装,提供了完整的、功能键全的GUI用户界面。程序可以基于GUI界面或命令行方式运行,参数简单、可定制性强、可以批处理数据,提高了影像镶嵌自动化水平,在东北土地利用数据库更新中被用于Landsat5 TM影像镶嵌。展开更多
基金supported by the National Science and Technology Major Project of China (No. 2013ZX03001018)
文摘Capacity enhancement approaches are being intensively studied in the past few years to address the soaring capacity demands. The network densif ication technology is recognized as one promising solution. However,the ultra-dense network scheme suffers from severe interference and frequent handovers,which degrade the system performance significantly. In this paper,a virtual sectorization system leveraging a C-plane(control signaling plane) and U-plane(user data plane) split scheme is proposed to overcome these two fundamental problems. Besides,a well-designed fi eld trial is conducted to evaluate its performance. The results show that the interference can be avoided,which leads to a tremendous increase in system capacity. In addition,the number of handovers is also greatly decreased. Thus,the trial results verify the huge potential of the C-plane and U-plane split scheme for system capacity and user experience enhancements.
基金supported by the National Natural Science Foundation of China(Grant Nos.60931002 and 61101064)the Universities Natural Science Foundation of Anhui Province,China(Grant Nos.KJ2011A002 and 1108085J01)
文摘The method of splitting a plane-wave finite-difference time-domain （SP-FDTD） algorithm is presented for the initiation of plane-wave source in the total-field / scattered-field （TF/SF） formulation of high-order symplectic finite- difference time-domain （SFDTD） scheme for the first time. By splitting the fields on one-dimensional grid and using the nature of numerical plane-wave in finite-difference time-domain （FDTD）, the identical dispersion relation can be obtained and proved between the one-dimensional and three-dimensional grids. An efficient plane-wave source is simulated on one-dimensional grid and a perfect match can be achieved for a plane-wave propagating at any angle forming an integer grid cell ratio. Numerical simulations show that the method is valid for SFDTD and the residual field in SF region is shrinked down to -300 dB.
文摘This study presents a new, simple method for reducing the back-lobe radiation of a microstrip antenna (MSA) by a partially removed ground plane of the antenna. The effect of the partial ground plane removal in different configurations on the radiation characteristics of a MSA are investigated numerically. The partial ground plane removal reduces the backlobe radiation of the MSA by suppressing the surface wave diffraction from the edges of the antenna ground plane. For further improving the front-to-back (F/B) ratio of the MSA, a new soft-surface configuration consisting of an array of stand-up split ring resonators (SRRs) are placed on a bare dielectric substrate near the two ground plane edges. Compared to the F/B ratio of a conventional MSA with a full ground plane of the same size, an improved F/B ratio of 9.7 dB has been achieved experimentally for our proposed MSA.
基金National Natural Science Foundations of China(Nos.11272087,11572085)Financial Supports from Foundation for the Fok Ying-Tong Education Foundation of China(No.141070)the Fundamental Research Funds for the Central Universities of China(No.170310103)
文摘The in-plane tensile behaviors of bi-axial warp-knitted(BWK) composites under quasi-static and high strain rates loading were experimentally analyzed in this article. The tensile tests were conducted along warp direction( 0°) and weft direction( 90°) at quasi-static rate of 0. 001 s^(-1) and high strain rates ranging from 1 450 to 2 540 s^(-1),respectively. It is found that the significant strain rate sensitivity can be observed in the stress-strain curves of BWK composites. The fracture morphologies of BWK composites demonstrate that the tensile failure modes are shear failure and fiber breakage under the quasi-static testing condition while interface failure and fibers pullout are at high strain rates.
文摘应用分裂平面波时域有限差分(Splitting Plane wave Finite Difference Time Domain,SP-FDTD)方法到三维时域有限差分(Finite Difference Time Domain,DFDTD)中引入高效平面波源.该方法基于分裂场思想,在一维FDTD上构造了新的迭代公式,使得一维FDTD和三维FDTD离散网格之间的数值相速度一致,消除了由于相速不一致而在总场区引起的泄漏误差以及插值带来的数值误差.通过数值算例验证了SP-FDTD方法对不同波源在任意角度(斜入射)下的平面波入射都是有效的,且泄露误差均在-300dB水平.
文摘针对目前遥感商用软件影像镶嵌过程中人工干预过多、自动化程度不高和不易修改等问题,提出了基于平面剖分的遥感影像镶嵌模型。模型基于开源类库空间数据抽象库(geospatial data abstraction library,GDAL),在GNU/Linux平台下,使用Python语言,实现了遥感影像按研究区域进行掩模及镶嵌的功能,并采用模型—视图—控制器(model view controller,MVC)的设计模式,应用跨平台的图形用户界面(graphical user interface,GUI)库wx Python实现了软件的封装,提供了完整的、功能键全的GUI用户界面。程序可以基于GUI界面或命令行方式运行,参数简单、可定制性强、可以批处理数据,提高了影像镶嵌自动化水平,在东北土地利用数据库更新中被用于Landsat5 TM影像镶嵌。
