The Ni, Fe, Co and Cu single and multilayer nanowire arrays to make perpendicular magnetic recording media were fabricated with nanoporous anodic aluminum oxide (AAO) templates from Watt solution and additives by the ...The Ni, Fe, Co and Cu single and multilayer nanowire arrays to make perpendicular magnetic recording media were fabricated with nanoporous anodic aluminum oxide (AAO) templates from Watt solution and additives by the DC electrodeposition. The results show that the diameters of Ni, Fe, Co and Cu single and multilayer nanowires in AAO templates are 40-80 nm and the lengths are about 30 μm with the aspect ratio of 350-750. The magnetic properties of the prepared nanowires are different under different electrodepositing conditions. The remanences (Br) of Ni/Cu/Fe multilayer nanowires are lower than those of others multilayer nanowires, and coercivity (Hc) of Ni/Cu/Fe multilayer nanowires are lower than those of others multilayer nanowires. These are compatible with the required conditions of high density magnetic media devices that should have the low coercivity to easily success magnetization and high remanence to keep magnetization after removal of magnetic field.展开更多
Nowadays,China BeiDou Navigation Satellite System(BDS)has been developed well and provided global services with highly precise positioning,navigation and timing(PNT)as well as unique short-message communication,partic...Nowadays,China BeiDou Navigation Satellite System(BDS)has been developed well and provided global services with highly precise positioning,navigation and timing(PNT)as well as unique short-message communication,particularly global system(BDS-3)with higher precision multi-frequency signals.The precise point positioning(PPP)can provide the precise position,receiver clock,and zenith tropospheric delay(ZTD)with a stand-alone receiver compared to the traditional double differenced relative positioning mode,which has been widely used in PNT,geodesy,meteorology and so on.However,it has a lot of challenges for multi-frequency BDS PPP with different strategies and more unknown parameters.In this paper,the detailed PPP models using the single-,dual-,triple-,and quad-frequency BDS observations are presented and evaluated.Firstly,BDS system and PPP method are introduced.Secondly,the stochastic models of time delay bias in BDS-2/BDS-3 PPP including the neglection,random constant,random walk and white noise are presented.Then,three single-frequency,four dual-frequency,four triple-frequency and four quad-frequency BDS PPP models are provided.Finally,the BDS PPP models progress and performances including theoretical comparison of the models,positioning performances,precise time and frequency transfer,ZTD,inter-frequency bias(IFB)and differential code bias(DCB)are presented and evaluated as well as future challenges.The results show that the multi-frequency BDS observations will greatly improve the PPP performances.展开更多
文摘The Ni, Fe, Co and Cu single and multilayer nanowire arrays to make perpendicular magnetic recording media were fabricated with nanoporous anodic aluminum oxide (AAO) templates from Watt solution and additives by the DC electrodeposition. The results show that the diameters of Ni, Fe, Co and Cu single and multilayer nanowires in AAO templates are 40-80 nm and the lengths are about 30 μm with the aspect ratio of 350-750. The magnetic properties of the prepared nanowires are different under different electrodepositing conditions. The remanences (Br) of Ni/Cu/Fe multilayer nanowires are lower than those of others multilayer nanowires, and coercivity (Hc) of Ni/Cu/Fe multilayer nanowires are lower than those of others multilayer nanowires. These are compatible with the required conditions of high density magnetic media devices that should have the low coercivity to easily success magnetization and high remanence to keep magnetization after removal of magnetic field.
基金the National Natural Science Foundation of China(NSFC)Project(Grant No.41761134092)Jiangsu Province Distinguished Professor Project(Grant No.R2018T20)Startup Foundation for Introducing Talent of NUIST(Grant No.2243141801036).
文摘Nowadays,China BeiDou Navigation Satellite System(BDS)has been developed well and provided global services with highly precise positioning,navigation and timing(PNT)as well as unique short-message communication,particularly global system(BDS-3)with higher precision multi-frequency signals.The precise point positioning(PPP)can provide the precise position,receiver clock,and zenith tropospheric delay(ZTD)with a stand-alone receiver compared to the traditional double differenced relative positioning mode,which has been widely used in PNT,geodesy,meteorology and so on.However,it has a lot of challenges for multi-frequency BDS PPP with different strategies and more unknown parameters.In this paper,the detailed PPP models using the single-,dual-,triple-,and quad-frequency BDS observations are presented and evaluated.Firstly,BDS system and PPP method are introduced.Secondly,the stochastic models of time delay bias in BDS-2/BDS-3 PPP including the neglection,random constant,random walk and white noise are presented.Then,three single-frequency,four dual-frequency,four triple-frequency and four quad-frequency BDS PPP models are provided.Finally,the BDS PPP models progress and performances including theoretical comparison of the models,positioning performances,precise time and frequency transfer,ZTD,inter-frequency bias(IFB)and differential code bias(DCB)are presented and evaluated as well as future challenges.The results show that the multi-frequency BDS observations will greatly improve the PPP performances.
