针对软件定义网络(Software Defined Network,SDN)技术在机动通信网络中的应用问题,给出软件定义机动通信网体系架构;结合OpenStack云管理系统,设计了基于云环境下的多模式联合仿真平台,采用虚拟化仿真建模技术模拟机动通信网络的体系...针对软件定义网络(Software Defined Network,SDN)技术在机动通信网络中的应用问题,给出软件定义机动通信网体系架构;结合OpenStack云管理系统,设计了基于云环境下的多模式联合仿真平台,采用虚拟化仿真建模技术模拟机动通信网络的体系结构和系统组成,数字仿真实现对无线环境的模拟并将无线传输效果叠加到网络仿真系统中,弥补虚拟化仿真在无线环境模拟方面的不足;通过搭建仿真演示环境,对比分析了软件定义机动通信网基于带内和带外传输的控制开销,推动了软件定义机动通信网的研究。展开更多
We report the ferroelectric,dielectric and piezoelectric properties of a dense and crack-free lead zirconate titanate (Pb(Zro.52 Tio.48)O3,PZT) thick film containing micro- and nano-crystalline particles. The results ...We report the ferroelectric,dielectric and piezoelectric properties of a dense and crack-free lead zirconate titanate (Pb(Zro.52 Tio.48)O3,PZT) thick film containing micro- and nano-crystalline particles. The results show that these electrical properties are dependent strongly on the annealing temperature and film thickness. For the different-annealing-temperature and different-thickness films,the higher-annealing-temperature thicker ones show the larger remnant polarization and smaller coercive field. The dielectric results show that relative dielectric constant achieves the largest value at annealing temperature of 700℃,and increases with the increasing film thickness.For the piezoelectric properties,the longitudinal piezoelectric coefficient increases linearly with the film thickness increasing and the 4-μm-thick PZT film shows the largest value of about 200.65 pC/N.Therefore,the PZT thick films present good electric properties and enlarged potential in MEMS applications.展开更多
This paper reports that dense and crack-free(100)oriented lead zirconate titanate(Pb(Zr0.52Ti0.48)O3,PZT)thick film embedded with PZT nanoparticles has been successfully fabricated on Pt/Cr/SiO2/Si substrate by using ...This paper reports that dense and crack-free(100)oriented lead zirconate titanate(Pb(Zr0.52Ti0.48)O3,PZT)thick film embedded with PZT nanoparticles has been successfully fabricated on Pt/Cr/SiO2/Si substrate by using PT transition layer and PVP additive.The thick film possesses single-phase perovskite structure and perfectly(100)oriented.The(100)orientation degree of the PZT films strongly depended on annealing time and for the 4 μm-thick PZT film which was annealed at 700 ℃ for 5 min is the largest.The(100)orientation degree of the PZT thick film gradually strengthen along with the thickness of film decreasing.The 3 μm-thick PZT thick film which was annealed at 700 ℃ for 5 min has the strongest(100)orientation degree,which is 82.3%.展开更多
We study the mechanism of microwave response properties of SiCv/paraffin nanocomposites and propose a mi- crowave absorption model of nanocomposites based on the conservation law of energy and the theory of electro- m...We study the mechanism of microwave response properties of SiCv/paraffin nanocomposites and propose a mi- crowave absorption model of nanocomposites based on the conservation law of energy and the theory of electro- magnetic scattering. Using the model we calculate the reflectivity of SiCp/paraffin nanocomposites ranging from 2 GHz to 18 GHz. The calculated results are very consistent with the experimental data in the frequency range investigated.展开更多
The geometrical and electronic structures of nitrogen-doped β-SiC are investigated by employing the first principles of plane wave ultra-soft pseudo-potential technology based on density functional theory. The struct...The geometrical and electronic structures of nitrogen-doped β-SiC are investigated by employing the first principles of plane wave ultra-soft pseudo-potential technology based on density functional theory. The structures of SiC1-xNx （x = 0, 1/32, 1/16, 1/8, 1/4） with different doping concentrations are optimized. The results reveal that the band gap of β-SiC transforms from an indirect band gap to a direct band gap with band gap shrinkage after carbon atoms are replaced by nitrogen atoms. The Fermi level shifts from valence band top to conduction band by doping nitrogen in pure β-SiC, and the doped β-SiC becomes metallic. The degree of Fermi levels entering into the conduction band increases with the increment of doping concentration; however, the band gap becomes narrower. This is attributed to defects with negative electricity occurring in surrounding silicon atoms. With the increase of doping concentration, more residual electrons, more easily captured by the 3p orbit in the silicon atom, will be provided by nitrogen atoms to form more defects with negative electricity.展开更多
文摘针对软件定义网络(Software Defined Network,SDN)技术在机动通信网络中的应用问题,给出软件定义机动通信网体系架构;结合OpenStack云管理系统,设计了基于云环境下的多模式联合仿真平台,采用虚拟化仿真建模技术模拟机动通信网络的体系结构和系统组成,数字仿真实现对无线环境的模拟并将无线传输效果叠加到网络仿真系统中,弥补虚拟化仿真在无线环境模拟方面的不足;通过搭建仿真演示环境,对比分析了软件定义机动通信网基于带内和带外传输的控制开销,推动了软件定义机动通信网的研究。
基金Supported by the National High-Technology Research and Development Program of China under Grant No 2007AA03Z103the National Natural Science Foundation of China under Grant Nos 50742007 and 10974053the Key Laboratory Foundation of Sonar Technology of China under Grant No 9140C24KF0901。
文摘We report the ferroelectric,dielectric and piezoelectric properties of a dense and crack-free lead zirconate titanate (Pb(Zro.52 Tio.48)O3,PZT) thick film containing micro- and nano-crystalline particles. The results show that these electrical properties are dependent strongly on the annealing temperature and film thickness. For the different-annealing-temperature and different-thickness films,the higher-annealing-temperature thicker ones show the larger remnant polarization and smaller coercive field. The dielectric results show that relative dielectric constant achieves the largest value at annealing temperature of 700℃,and increases with the increasing film thickness.For the piezoelectric properties,the longitudinal piezoelectric coefficient increases linearly with the film thickness increasing and the 4-μm-thick PZT film shows the largest value of about 200.65 pC/N.Therefore,the PZT thick films present good electric properties and enlarged potential in MEMS applications.
基金Sponsored by 863 Scientific Project of China (Grant No.2007AA03Z103)the National Natural Science Foundation of China (Grant No.50742007)the Key Laboratory Foundation of Sonar Technology of China(Grant No. 9140C24KF0901)
文摘This paper reports that dense and crack-free(100)oriented lead zirconate titanate(Pb(Zr0.52Ti0.48)O3,PZT)thick film embedded with PZT nanoparticles has been successfully fabricated on Pt/Cr/SiO2/Si substrate by using PT transition layer and PVP additive.The thick film possesses single-phase perovskite structure and perfectly(100)oriented.The(100)orientation degree of the PZT films strongly depended on annealing time and for the 4 μm-thick PZT film which was annealed at 700 ℃ for 5 min is the largest.The(100)orientation degree of the PZT thick film gradually strengthen along with the thickness of film decreasing.The 3 μm-thick PZT thick film which was annealed at 700 ℃ for 5 min has the strongest(100)orientation degree,which is 82.3%.
文摘We study the mechanism of microwave response properties of SiCv/paraffin nanocomposites and propose a mi- crowave absorption model of nanocomposites based on the conservation law of energy and the theory of electro- magnetic scattering. Using the model we calculate the reflectivity of SiCp/paraffin nanocomposites ranging from 2 GHz to 18 GHz. The calculated results are very consistent with the experimental data in the frequency range investigated.
文摘The geometrical and electronic structures of nitrogen-doped β-SiC are investigated by employing the first principles of plane wave ultra-soft pseudo-potential technology based on density functional theory. The structures of SiC1-xNx （x = 0, 1/32, 1/16, 1/8, 1/4） with different doping concentrations are optimized. The results reveal that the band gap of β-SiC transforms from an indirect band gap to a direct band gap with band gap shrinkage after carbon atoms are replaced by nitrogen atoms. The Fermi level shifts from valence band top to conduction band by doping nitrogen in pure β-SiC, and the doped β-SiC becomes metallic. The degree of Fermi levels entering into the conduction band increases with the increment of doping concentration; however, the band gap becomes narrower. This is attributed to defects with negative electricity occurring in surrounding silicon atoms. With the increase of doping concentration, more residual electrons, more easily captured by the 3p orbit in the silicon atom, will be provided by nitrogen atoms to form more defects with negative electricity.
