A remote antenna unit （RAU） selection model is presented, and two kinds of handoffs, intra-cell handoff （HO） and inter-cell HO, are defined in distributed mobile communications systems （DAS）. After that, an inte...A remote antenna unit （RAU） selection model is presented, and two kinds of handoffs, intra-cell handoff （HO） and inter-cell HO, are defined in distributed mobile communications systems （DAS）. After that, an inter-cell HO model is proposed, in which the average power of the active set （AS） is used to predict the position of the mobile station （MS）. The total power of the AS and the handoff set （HOS） are utilized to determine whether an inter-cell HO is necessary. Furthermore, the relationship between HO parameters and performance metrics is studied in detail based on RAU selection. Simulation results show that both the intra-cell HO and the inter-cell HO can achieve oerfect performance by aoprooriate settings of HO parameters.展开更多
Single-crystalline hematite （α-Fe2O3） nanorings （short nanotubes） and nanotubes were synthesized by a hydrothermal method. High-resolution transmission electron microscopy and selected-area electron diffraction c...Single-crystalline hematite （α-Fe2O3） nanorings （short nanotubes） and nanotubes were synthesized by a hydrothermal method. High-resolution transmission electron microscopy and selected-area electron diffraction confirm that the axial directions of both the nanorings and nanotubes are parallel to the crystalline c-axis. Intriguingly, the Morin transition occurs at about 210 K in the short nanotubes with a mean tube length of about 115 nm and a mean outer diameter of about 169 nm. However, it does not occur in the nanotubes with a mean tube length of about 317 nm and a mean outer diameter of about 148 nm. Detailed analysis of magnetization data, X-ray diffraction patterns, and room-temperature M6ssbauer spectra demonstrates that this very strong shape-dependence of Morin transition is intrinsic to hematite. We explain this intriguing shape- dependence quantitatively, in terms of the opposite signs of the surface mag- netic anisotropy constants of the surface planes parallel and perpendicular to the c-axis.展开更多
基金The National Natural Science Foundation of China(No60496311)
文摘A remote antenna unit （RAU） selection model is presented, and two kinds of handoffs, intra-cell handoff （HO） and inter-cell HO, are defined in distributed mobile communications systems （DAS）. After that, an inter-cell HO model is proposed, in which the average power of the active set （AS） is used to predict the position of the mobile station （MS）. The total power of the AS and the handoff set （HOS） are utilized to determine whether an inter-cell HO is necessary. Furthermore, the relationship between HO parameters and performance metrics is studied in detail based on RAU selection. Simulation results show that both the intra-cell HO and the inter-cell HO can achieve oerfect performance by aoprooriate settings of HO parameters.
基金This work was supported by the National Natural Science Foundation of China （No. 11174165）, the Natural Science Foundation of Ningbo （No. 2012A610051）, and the K. C. Wong Magna Foundation. VA acknowledges financial support from NIH and NIGMS under MBRS- RISE M.S.-to-Ph.D. Program （No. R25GM061331）.
文摘Single-crystalline hematite （α-Fe2O3） nanorings （short nanotubes） and nanotubes were synthesized by a hydrothermal method. High-resolution transmission electron microscopy and selected-area electron diffraction confirm that the axial directions of both the nanorings and nanotubes are parallel to the crystalline c-axis. Intriguingly, the Morin transition occurs at about 210 K in the short nanotubes with a mean tube length of about 115 nm and a mean outer diameter of about 169 nm. However, it does not occur in the nanotubes with a mean tube length of about 317 nm and a mean outer diameter of about 148 nm. Detailed analysis of magnetization data, X-ray diffraction patterns, and room-temperature M6ssbauer spectra demonstrates that this very strong shape-dependence of Morin transition is intrinsic to hematite. We explain this intriguing shape- dependence quantitatively, in terms of the opposite signs of the surface mag- netic anisotropy constants of the surface planes parallel and perpendicular to the c-axis.
