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| 1 | Structure and magneto-electrical properties of Fe-C films prepared by magnetron sputtering显示文摘Fe-doped amorphous Fe x C 1 x granular films were prepared on n-Si(100) substrates by d.c.magnetron sputtering.The structural properties of Fe x C 1 x films were investigated by X-ray diffraction(XRD),atomic force microscope(AFM) and Raman spectroscopy.The results show that the iron and carbon of as-deposited films are in amorphous state,and the Fe x C 1 x films are diamond-like carbon(DLC) films.After doping iron into the DLC films,a smooth surface morphology of the Fe x C 1 x films has been obtained with the surface roughness Ra of about 0.231 nm for x=18at%.The Fe x C 1 x films have good soft magnetic properties with the coercivity of approximately 20 Oe.A high positive magnetoresistance(MR) up to 93% with x=1at% was observed in a Fe x C 1 x granular film at 300 K.The resistance characteristic of Fe-C films is changed at about 230 K and the positive MR effect can be understood by the p-n heterojunction theory. | MA Lei LIU ZhongWu ZENG DeChang YU HongYa ZHONG XiaPing ZHANG XiaoZhong | 2012 | Science China(Physics,Mechanics & Astronomy)2012，55，9： | 3 |
| 2 | Mathematical model for computing precise local tie vectors for CMONOC co-located GNSS/VLBI/SLR stations显示文摘The seven co-located sites of the Crustal Movement Observation Network of China(CMONOC) in Shanghai, Wuhan, Kunming, Beijing, Xi'an, Changchun, and Urumqi are equipped with Global Navigation Satellite System(GNSS), very long baseline interferometry(VLBI), and satellite laser ranging(SLR) equipment. Co-location surveying of these sites was performed in 2012 and the accuracies of the solved tie vectors are approximately 5 mm.This paper proposes a mathematical model that handles the least squares adjustment of the 3D control network and calculates the tie vectors in one step, using all the available constraints in the adjustment. Using the new mathematical model, local tie vectors can be more precisely determined and their covariance more reasonably estimated. | Shen Yunzhong You Xinzhao Wang Jiexian Wu Bin Chen Junping Ma Xiaping Gong Xiuqiang | 2015 | Geodesy and Geodynamics2015，6，1： | 1 |
| 3 | Magnetic properties and magnetoresistance of Co_xC_(1-x) granular films prepared by magnetron sputtering显示文摘Amorphous CoxC1-x granular films were prepared on n-Si(100) substrate by dc magnetron sputtering.The effects of Co concentration,film thickness and annealing temperature on the magnetic properties and magnetoresistance(MR) were investigated.After annealing at 500°C for 0.5 hour,the Co(002) peak of the CoxC1-x(x>2.5 at.%) films was observed,but cracks appeared in the films.Saturation magnetization Ms increased steadily with the increase of Co concentration from 2.5 at.% to 50 at.% and also increased with annealing temperature from room temperature to 400°C.The coercivity of CoxC1-x films was less than 180 Oe.The as-deposited Co2.5C97.5 granular films with 80 nm thickness showed a highly positive MR,up to 15.5% at a magnetic field of 0.8 T,observed at T=300 K when the external magnetic field was perpendicular to the film surface.With increasing film thickness and annealing temperature,the value of MR was found to decrease gradually and changed from positive to negative.The MR effect of the CoxC1-x granular films can be explained by p-n heterojunction theory and interface scattering effect. | MA Lei LIU ZhongWu ZENG DeChang ZHONG XiaPing ZHANG XiaoZhong | 2011 | Science China(Physics,Mechanics & Astronomy)2011，54，7： | 1 |
| 4 | Evaluation of BDS and GPS RAIM availability based on data collected in June 2020显示文摘The satellite pseudo-range fault detection with the Receiver Autonomous Integrity Monitoring(RAIM)method is affected by several satellite observations and the geometric distribution of satellites.The poor geometry distribution of satellites will conceal the positioning errorcaused by the satellite pseudo-range fault,resulting in unreliable detection results.Therefore,the availability evaluation must be made before RAIM to ensure that the fault detection performance will not be affected.On June 23,2020,China successfully launched the 30 th(last)navigation satellite of BeiDou’s third-generation navigation satellite system(BDS-3),which is also the 55 th BeiDou navigation satellite.Combining all the available satellites of BDS-1,BDS-2 and BDS-3,the positioning performance of BDS can be greatly improved.In order to evaluate the RAIM availability of BeiDou Navigation Satellite System(BDS)and Global Positioning System(GPS)in China,this paper first deduces the mathematical models and their characteristics of the three RAIM availability evaluation methods.Then,the study area(N10°-70°,E60°-150°)is divided into 4536 grid points at intervals of 1°×1°in latitude and longitude,and the elevations of these grid points are taken from the global terrain data file.The Horizontal Protection Level(HPL)values of these grid points are calculated during 8-15 June 2020 using BDS and GPS ephemeris data.The RAIM availability differences between the two systems are compared and analysed.The analysis shows the Horizontal Protection Level method(HPLM)based on single-satellite pseudo-range fault is the most practical and convenient.During the 8-day observation period,the HPL values of BDS are significantly smaller than those of GPS in terms of geographic location and observation time,and the variation of HPL time series of BDS is also smaller than that of GPS,which indicates that the RAIM availability of GPS in China is not as good as that of BDS.Most importantly,in the four flight stages of the aircraft’s Oceanic/Continental lowdensity En-route,Continental En-route,Terminal En-route and Non-precision approach(NPA),BDS can completely satisfy its RAIM availability requirement,while GPS can only meet the availability requirement of the En-route(Oceanic/Continental low density)phase,and the availability of the other three phases can at least reach 99.714%. | Xiaping Ma Kegen Yu Ershen Wang Xiaoxing He Tieding Lu Qinzhen Li | 2021 | Geodesy and Geodynamics2021，12，3： | 0 |
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