Traditional beamformers need to know the incident angle of the desired signal leading while its abili-ty to handle interference is limited.In this paper,the constrained steer vector of linearly constrained min-imum-va...Traditional beamformers need to know the incident angle of the desired signal leading while its abili-ty to handle interference is limited.In this paper,the constrained steer vector of linearly constrained min-imum-variance(LCMV)beamformer is modified to make sidelobe null to direction of powerful jammer.Inaddition,the state-space concept is used to describe the anti-jammer filter,and Kalman filter algorithm isdeduced by building the observation model and measurement equation.The new method is more efficient oncomputation and more robust to survive environment with large scale variation in interference strength.Fi-nally,simulation results shows that the new approach can form the null with its depth in proportion to powerin direction of jammer,and has steady convergence process.The novel method can effectively improve thesignal-to-jammer-plus-noise power ratio(SJNR)of GPS signals to make the correlation peak easy to track.展开更多
In this work,we prepared silicon nanowires(Si NWs) on both fluorine-doped SnO 2(FTO) coated glass substrate and common glass substrate by catalytic thermal chemical vapor deposition(CVD) using indium film as the catal...In this work,we prepared silicon nanowires(Si NWs) on both fluorine-doped SnO 2(FTO) coated glass substrate and common glass substrate by catalytic thermal chemical vapor deposition(CVD) using indium film as the catalyst.It is confirmed that indium can catalyze the growth of Si NWs.More importantly,we found that tin generated in situ from the reduction of SnO 2 by indium can act as catalyst,which greatly enhances the growth of Si NWs on FTO substrate.The obtained Si NWs have a uniform crystalline-amorphous core-shell structure that is formed via vapor-liquid-solid and vapor-solid growth of silicon sequentially.This work provides a strategy to prepare Si NWs in high yield by catalytic thermal CVD using the low melting point metal catalysts.展开更多
In this work,we develop a new many-body potential for alpha-hafnium(α-Hf)based on the second moment approximation of tight-binding(TB-SMA)theory by introducing an additional Heaviside step function into the potential...In this work,we develop a new many-body potential for alpha-hafnium(α-Hf)based on the second moment approximation of tight-binding(TB-SMA)theory by introducing an additional Heaviside step function into the potential model and a new analytical scheme of density function.All the parameters of the new potential have been systematically evaluated by fitting to ground-state properties including cohesive energy,lattice constants,elastic constants,vacancy formation energy,structure stability and equation of state.By using the present model,the melting point,melt heat,thermal expansion coefficient,point defects,and low-index surface energies ofα-Hf were calculated through molecular dynamics simulations.Comparing with experiment observations from others,it is shown that these properties can be reproduced reasonably by the present model,some results being more consistent to the experimental data than those by previous suggested models.This indicates that this work is sutiable in TB-SMA potential for hexagonal close packed metals.展开更多
基金Supported by the National High Technology Research and Development Programme of China (No. 2006AA701108)
文摘Traditional beamformers need to know the incident angle of the desired signal leading while its abili-ty to handle interference is limited.In this paper,the constrained steer vector of linearly constrained min-imum-variance(LCMV)beamformer is modified to make sidelobe null to direction of powerful jammer.Inaddition,the state-space concept is used to describe the anti-jammer filter,and Kalman filter algorithm isdeduced by building the observation model and measurement equation.The new method is more efficient oncomputation and more robust to survive environment with large scale variation in interference strength.Fi-nally,simulation results shows that the new approach can form the null with its depth in proportion to powerin direction of jammer,and has steady convergence process.The novel method can effectively improve thesignal-to-jammer-plus-noise power ratio(SJNR)of GPS signals to make the correlation peak easy to track.
基金supported by Solar Energy Initiative of the Knowledge Innovation Program of the Chinese Academy of Sciences (KGCX2-YW-395-3)
文摘In this work,we prepared silicon nanowires(Si NWs) on both fluorine-doped SnO 2(FTO) coated glass substrate and common glass substrate by catalytic thermal chemical vapor deposition(CVD) using indium film as the catalyst.It is confirmed that indium can catalyze the growth of Si NWs.More importantly,we found that tin generated in situ from the reduction of SnO 2 by indium can act as catalyst,which greatly enhances the growth of Si NWs on FTO substrate.The obtained Si NWs have a uniform crystalline-amorphous core-shell structure that is formed via vapor-liquid-solid and vapor-solid growth of silicon sequentially.This work provides a strategy to prepare Si NWs in high yield by catalytic thermal CVD using the low melting point metal catalysts.
基金supported by the National Natural Science Foundation of China(Grant Nos.51071018 and 51271018)
文摘In this work,we develop a new many-body potential for alpha-hafnium(α-Hf)based on the second moment approximation of tight-binding(TB-SMA)theory by introducing an additional Heaviside step function into the potential model and a new analytical scheme of density function.All the parameters of the new potential have been systematically evaluated by fitting to ground-state properties including cohesive energy,lattice constants,elastic constants,vacancy formation energy,structure stability and equation of state.By using the present model,the melting point,melt heat,thermal expansion coefficient,point defects,and low-index surface energies ofα-Hf were calculated through molecular dynamics simulations.Comparing with experiment observations from others,it is shown that these properties can be reproduced reasonably by the present model,some results being more consistent to the experimental data than those by previous suggested models.This indicates that this work is sutiable in TB-SMA potential for hexagonal close packed metals.
