The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching(OBS) nodes with limited wavelength conversion capability(LWCC) . T...The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching(OBS) nodes with limited wavelength conversion capability(LWCC) . The relevant system architectures of limited range and limited number of wavelength converters(WCs) deployed by a share-per-fiber(SPF) mode were developed,and the novel theoretical analysis of node blocking probability was derived by combining the calculation of discouraged arrival rate in a birth-death process and two-dimensional Markov chain model of SPF. The simulation results on single node performance verify the accuracy and effectiveness of the analysis models. Under most scenarios,it is difficult to distinguish the plots generated by the analysis and simulation. As the conversion degree increases,the accuracy of the analysis model worsens slightly. However,the utmost error on burst loss probability is far less than one order of magnitude and hence,still allows for an accurate estimate. Some results are of actual significance to the construction of next-generation commercial OBS backbones.展开更多
DC distribution networks are often employed in isolated power systems like in marine and aeronautical applications. An interesting alternative to DC machines for the supply of DC grids is constituted by a three-phase ...DC distribution networks are often employed in isolated power systems like in marine and aeronautical applications. An interesting alternative to DC machines for the supply of DC grids is constituted by a three-phase alternator feeding an AC/DC rectifier. In this paper, alternative solutions are investigated where the AC alternator is equipped with more （iV） three-phase windings and feeds the DC load through more （N） cascade-connected rectifiers. The advantages of this solution with respect to the conventional three-phase topology are highlighted along with their dependence on the number （N） of the alternator windings. For this purpose, test results are reported and discussed on a prototype generator whose stator coils can be differently connected to obtained one, two, three or four windings. The major benefits （in terms of DC output current quality and field current ripple） are found when passing from the three-phase solution to the dual winding topology; conversely, relatively little advantage is gained by increasing the number of stator windings above two.展开更多
随着以IPv6为核心的下一代互联网的发展,现有路由器体系结构在性能、复杂性、扩展能力和节能等方面存在许多难以克服的问题,特别是随着网络规模的扩展,如何实现大容量IPv6 FIB(forwarding information base)线速查找是下一代高性能路由...随着以IPv6为核心的下一代互联网的发展,现有路由器体系结构在性能、复杂性、扩展能力和节能等方面存在许多难以克服的问题,特别是随着网络规模的扩展,如何实现大容量IPv6 FIB(forwarding information base)线速查找是下一代高性能路由器设计面临的重大挑战.文中提出一种与目前分布转发集中交换结构不同的新型路由器体系结构-MPFS(massive parallel forwarding and switching).MPFS基于FIS(forwarding in switching)思想,将网络处理器嵌入到可扩展多级交换网络中,通过流水和分布并行方式实现转发.与MPP(massive parallel processing)一样,MPFS通过互连大量简单同构的FSN(forwarding and switching node)实现可扩展的转发和交换.重点研究了MPFS中IPv6 FIB查表问题,提出了将IPv6 FIB映射到多级FSN上的方法.模拟和计算表明基于现有DRAM器件和Tree Bitmap查找技术,MPFS可在40Gbps接口上实现包含1M个IPv6前缀的FIB的线速查找.最后提出了一种基于MPFS体系结构的吞吐率为160Tbps的核心路由器实现方案.展开更多
Highly luminescent upconversion nanoparticles （UCNPs） with small sizes are highly desirable for bioapplications. A facile in situ cation exchange strategy has been developed to greatly enhance the UC luminescence of...Highly luminescent upconversion nanoparticles （UCNPs） with small sizes are highly desirable for bioapplications. A facile in situ cation exchange strategy has been developed to greatly enhance the UC luminescence of hexagonal phase NaYF4 NPs while maintaining their small particle size and shape. Via a cation exchange treatment by hot-injecting Gd3＋ precursors into the as-prepared NPs solution without pre-separation, the naked-eye visible UC emission of the NPs was enhanced about 29 times under 980 nm near infrared （NIR） excitation with unchanged particle size. The cation exchange process was further demonstrated for the case of NaYF4 nanorods （NRs）. After the cation exchange, the nanorod was broken into two NPs with stronger emission. The cation exchanged hydrophobic UCNPs were further encapSulated with poly（amino acid） and successfully applied for targeted cancer cell UC luminescence imaging.展开更多
基金Project(60632010) supported by the National Natural Science Foundation of China
文摘The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching(OBS) nodes with limited wavelength conversion capability(LWCC) . The relevant system architectures of limited range and limited number of wavelength converters(WCs) deployed by a share-per-fiber(SPF) mode were developed,and the novel theoretical analysis of node blocking probability was derived by combining the calculation of discouraged arrival rate in a birth-death process and two-dimensional Markov chain model of SPF. The simulation results on single node performance verify the accuracy and effectiveness of the analysis models. Under most scenarios,it is difficult to distinguish the plots generated by the analysis and simulation. As the conversion degree increases,the accuracy of the analysis model worsens slightly. However,the utmost error on burst loss probability is far less than one order of magnitude and hence,still allows for an accurate estimate. Some results are of actual significance to the construction of next-generation commercial OBS backbones.
文摘DC distribution networks are often employed in isolated power systems like in marine and aeronautical applications. An interesting alternative to DC machines for the supply of DC grids is constituted by a three-phase alternator feeding an AC/DC rectifier. In this paper, alternative solutions are investigated where the AC alternator is equipped with more （iV） three-phase windings and feeds the DC load through more （N） cascade-connected rectifiers. The advantages of this solution with respect to the conventional three-phase topology are highlighted along with their dependence on the number （N） of the alternator windings. For this purpose, test results are reported and discussed on a prototype generator whose stator coils can be differently connected to obtained one, two, three or four windings. The major benefits （in terms of DC output current quality and field current ripple） are found when passing from the three-phase solution to the dual winding topology; conversely, relatively little advantage is gained by increasing the number of stator windings above two.
文摘随着以IPv6为核心的下一代互联网的发展,现有路由器体系结构在性能、复杂性、扩展能力和节能等方面存在许多难以克服的问题,特别是随着网络规模的扩展,如何实现大容量IPv6 FIB(forwarding information base)线速查找是下一代高性能路由器设计面临的重大挑战.文中提出一种与目前分布转发集中交换结构不同的新型路由器体系结构-MPFS(massive parallel forwarding and switching).MPFS基于FIS(forwarding in switching)思想,将网络处理器嵌入到可扩展多级交换网络中,通过流水和分布并行方式实现转发.与MPP(massive parallel processing)一样,MPFS通过互连大量简单同构的FSN(forwarding and switching node)实现可扩展的转发和交换.重点研究了MPFS中IPv6 FIB查表问题,提出了将IPv6 FIB映射到多级FSN上的方法.模拟和计算表明基于现有DRAM器件和Tree Bitmap查找技术,MPFS可在40Gbps接口上实现包含1M个IPv6前缀的FIB的线速查找.最后提出了一种基于MPFS体系结构的吞吐率为160Tbps的核心路由器实现方案.
文摘Highly luminescent upconversion nanoparticles （UCNPs） with small sizes are highly desirable for bioapplications. A facile in situ cation exchange strategy has been developed to greatly enhance the UC luminescence of hexagonal phase NaYF4 NPs while maintaining their small particle size and shape. Via a cation exchange treatment by hot-injecting Gd3＋ precursors into the as-prepared NPs solution without pre-separation, the naked-eye visible UC emission of the NPs was enhanced about 29 times under 980 nm near infrared （NIR） excitation with unchanged particle size. The cation exchange process was further demonstrated for the case of NaYF4 nanorods （NRs）. After the cation exchange, the nanorod was broken into two NPs with stronger emission. The cation exchanged hydrophobic UCNPs were further encapSulated with poly（amino acid） and successfully applied for targeted cancer cell UC luminescence imaging.
