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| 1 | Precise orbit determination of Beidou Satellites with precise positioning显示文摘Chinese Beidou satellite navigation system constellation currently consists of eight Beidou satellites and can provide preliminary service of navigation and positioning in the Asia-Pacific Region.Based on the self-developed software Position And Navigation Data Analysis(PANDA) and Beidou Experimental Tracking Stations (BETS),which are built by Wuhan University,the study of Beidou precise orbit determination,static precise point positioning (PPP),and high precision relative positioning,and differential positioning are carried out comprehensively.Results show that the radial precision of the Beidou satellite orbit determination is better than 10 centimeters.The RMS of static PPP can reach several centimeters to even millimeters for baseline relative positioning.The precision of kinematic pseudo-range differential positioning and RTK mode positioning are 2-4 m and 5-10 cm respectively,which are close to the level of GPS precise positioning.Research in this paper verifies that,with support of ground reference station network,Beidou satellite navigation system can provide precise positioning from several decimeters to meters in the wide area and several centimeters in the regional area.These promising results would be helpful for the implementation and applications of Beidou satellite navigation system. | SHI Chuang ZHAO QiLe LI Min TANG WeiMing HU ZhiGang LOU YiDong ZHANG HongPing NIU XiaoJi LIU JingNan | 2012 | Science China Earth Sciences2012，55，7： | 61 |
| 2 | Earthquake-related Tectonic Deformation of Soft-sediments and Its Constraints on Basin Tectonic Evolution显示文摘The authors introduced two kinds of newly found soft-sediment deformation-syn-sedimentary extension structure and syn-sedimentary compression structure,and discuss their origins and constraints on basin tectonic evolution.One representative of the syn-sedimentary extension structure is syn-sedimentary boudinage structure,while the typical example of the syn-sedimentary compression structure is compression sand pillows or compression wrinkles.The former shows NW-SE-trending contemporaneous extension events related to earthquakes in the rift basin near a famous Fe-Nb-REE deposit in northern China during the Early Paleozoic(or Mesoproterozoic as proposed by some researches),while the latter indicates NE-SW-trending contemporaneous compression activities related to earthquakes in the Middle Triassic in the Nanpanjiang remnant basin covering south Guizhou,northwestern Guangxi and eastern Yunnan in southwestern China.The syn-sedimentary boudinage structure was found in an earthquake slump block in the lower part of the Early Paleozoic Sailinhudong Group,20 km to the southeast of Bayan Obo,Inner Mongolia,north of China.The slump block is composed of two kinds of very thin layers—pale-gray micrite(microcrystalline limestone)of 1?2 cm thick interbedded with gray muddy micrite layers with the similar thickness.Almost every thin muddy micrite layer was cut into imbricate blocks or boudins by abundant tiny contemporaneous faults,while the interbedded micrite remain in continuity.Boudins form as a response to layer-parallel extension(and/or layer-perpendicular flattening)of stiff layers enveloped top and bottom by mechanically soft layers.In this case,the imbricate blocks cut by the tiny contemporaneous faults are the result of abrupt horizontal extension of the crust in the SE-NW direction accompanied with earthquakes.Thus,the rock block is,in fact,a kind of seismites.The syn-sedimentary boudins indicate that there was at least a strong earthquake belt on the southeast side of the basin during the early stage of the Sailinhudong Group.This may be a good constraint on the tectonic evolution of the Bayan Obo area during the Early Paleozoic time.The syn-sedimentary compression structure was found in the Middle Triassic flysch in the Nanpanjiang Basin.The typical structures are compression sand pillows and compression wrinkles.Both of them were found on the bottoms of sand units and the top surface of the underlying mud units.In other words,the structures were found only in the interfaces between the graded sand layer and the underlying mud layer of the flysch.A deformation experiment with dough was conducted,showing that the tectonic deformation must have been instantaneous one accompanied by earthquakes.The compression sand pillows or wrinkles showed uniform directions along the bottoms of the sand layer in the flysch,revealing contemporaneous horizontal compression during the time between deposition and diagenesis of the related beds.The Nanpanjiang Basin was affected,in general,with SSW-NNE compression during the Middle Triassic,according to the syn-sedimentary compression structure.The two kinds of syn-sedimentary tectonic deformation also indicate that the related basins belong to a rift basin and a remnant basin,respectively,in the model of Wilson Cycle. | LU Hongbo ZHANG Yuxu ZHANG Qiling XIAO Jiafei | 2006 | Acta Geologica Sinica(English Edition)2006，80，5： | 13 |
| 3 | Quality assessment of onboard GPS receiver and its combination with DORIS and SLR for Haiyang 2A precise orbit determination显示文摘The GPS,DORIS,and SLR instruments are installed on Haiyang 2A(HY2A)altimetry satellite for Precise Orbit Determination(POD).Among these instruments,the codeless GPS receiver is the state-of-art Chinese indigenous onboard receiver,and it is the first one successfully used for Low Earth Orbit(LEO)satellite.Firstly,the contribution assesses the performance of the receiver through an analysis of data integrity,numbers of all tracked and valid measurements as well as multipath errors.The receiver generally shows good performance and quality despite a few flaws.For example,L2 observations are often missing in low elevations,particularly during the ascent of GPS satellites,and the multipath errors of P1 show a slightly abnormal pattern.Secondly,the PCO(Phase Center Offset)and PCV(Phase Center Variation)of the antenna of the GPS receiver are determined in this contribution.A significant leap for Z-component of PCO up to-1.2 cm has been found on 10 October 2011.Thirdly,the obtained PCO and PCV maps are used for GPS only POD solutions.The post-fit residuals of ionosphere-free phase combinations reduce almost 50%,and the radial orbit differences with respect to CNES(Centre National d’Etudes Spatiales)Precise Orbit Ephemeris(POEs)improve about 13.9%.The orbits are validated using the SLR data,and the RMS of SLR Observed minus Computed(O-C)residuals reduces from 17.5 to 15.9 mm.These improvements are with respect to the orbits determined without PCO and PCV.Fourthly,six types of solutions are determined for HY2A satellite using different combinations of GPS,DORIS,and SLR data.Statistics of SLR O-C residuals and cross-comparison of orbits obtained in the contribution and the CNES POEs indicate that the radial accuracy of these orbits is at the 1.0 cm level for HY2A orbit solutions,which is much better than the scientific requirements of this mission.It is noticed that the GPS observations dominate the achievable accuracy of POD,and the combination of multiple types of observations can reduce orbit errors caused by data gaps and maintain more stable and continuous orbits. | GUO Jing ZHAO QiLe GUO Xiang LIU XiangLin LIU JingNan ZHOU Quan | 2015 | Science China Earth Sciences2015，58，1： | 13 |
| 4 | High Precision Orbit Determination of CHAMP Satellite显示文摘The precision orbit determination of challenging minisatellite payload(CHAMP) satellite was done based on position and navigation data analyst(PANDA) software which is developed in Wuhan University, using the onboard GPS data of year 2002 from day 126 to 131. The orbit accuracy was assessed by analyzing the difference from GFZ post-processed science orbits (PSO), the GPS carrier and pseudo-range data residuals and the satellite laser ranging (SLR) residuals. | ZHAO Qile LIU Jingnan GE Maorong | 2006 | Geo-Spatial Information Science2006，9，3： | 9 |
| 5 | 用Amplatzer房间隔封堵器堵闭边缘不足的房间隔缺损效果观察显示文摘目的 探讨用Amplatzer房间隔缺损封堵器经导管堵闭部分边缘缺乏或不足(<5mm)的房间隔缺损的可行性。方法 1999年7月至2 0 0 1年9月对芝加哥大学儿童医院的2 3例边缘<5mm的房间隔缺损患儿试用Amplatzer封堵器进行堵闭,其中男10例,女13例,平均年龄10 7岁。2 0例经食管超声心动图或心内超声心动图测量的房间隔缺损前缘0~4mm ,2例下缘为2mm ,1例后缘为2mm。同期,4 8例房间隔缺损边缘>5mm的患儿作对照。结果 全部2 3例边缘<5mm的房间隔缺损患儿和4 8例对照儿均成功安装了封堵器。两组间年龄、缺损大小和所用封堵器大小差异无显著性意义(P >0 . 0 5 )。2 3例边缘<5mm的患儿中17例(73. 9% )即刻完全堵闭,对照组4 4例(91 .7% )即刻完全堵闭(P <0 .0 5 ) ;2 4h复查边缘<5mm患儿及对照组的完全堵闭率分别是91 3%和93 8% (P >0. 0 5 ) ;6个月复查两组完全堵闭率分别是95 7%和95 8% (P >0 . 0 5 )。缺损边缘<5mm患儿及对照组手术时间分别为(72 . 5±2 6 .5 )min和(6 1. 4±2 1 .9)min ;X线暴光时间分别为(12 .6±7 .0 )min和(9. 8±4 . 2 )min ,与对照组比较手术时间稍长。两组患儿术中和术后均未出现并发症。结论 前、后或下缘<5mm的房间隔缺损仍可以用Amplatzer房间隔缺损封堵器经导管堵闭。 | 杜忠东 Cao Qiling Ziyad M Hijazi | 2005 | 中国实用儿科杂志2005，20，3： | 8 |
| 6 | Transplant outcomes of 100 cases of living-donor ABO-incompatible kidney transplantation显示文摘Background:Although ABO-incompatible(ABOi)kidney transplantation(KT)has been performed successfully,a standard preconditioning regimen has not been established.Based on the initial antidonor ABO antibody titers,an individualized preconditioning regimen is developed,and this study explored the efficacy and safety of the regimen.Methods:From September 1,2014,to September 1,2020,we performed 1668 consecutive living-donor KTs,including 100 ABOi and 1568 ABO-compatible(ABOc)KTs.ABOi KT recipients(KTRs)with a lower antibody titer(≤1:8)were administered oral immunosuppressive drugs(OIs)before KT,while patients with a medium titer(1:16)received OIs plus antibody-removal therapy(plasma exchange/double-filtration plasmapheresis),patients with a higher titer(≥1:32)were in addition received rituximab(Rit).Competing risk analyses were conducted to estimate the cumulative incidence of infection,acute rejection(AR),graft loss,and patient death.Results:After propensity score analyses,100 ABOi KTRs and 200 matched ABOc KTRs were selected.There were no significant differences in graft and patient survival between the ABOi and ABOc groups(P=0.787,P=0.386,respectively).After using the individualized preconditioning regimen,ABOi KTRs showed a similar cumulative incidence of AR(10.0%vs.10.5%,P=0.346).Among the ABOi KTRs,the Rit-free group had a similar cumulative incidence of AR(P=0.714)compared to that of the Rittreated group.Multivariate competing risk analyses revealed that a Rit-free regimen reduced the risk of infection(HR:0.31;95%CI:0.12–0.78,P=0.013).Notably,antibody titer rebound was more common in ABOi KTRs receiving a Rit-free preconditioning regimen(P=0.013)than those receiving Rit.ABOi KTRs with antibody titer rebound had a 2.72-fold risk of AR(HR:2.72,95%CI:1.01–7.31,P=0.048).ABOi KTRs had similar serum creatinine and estimated glomerular filtration rate compared to those of ABOc KTRs after the first year.Conclusions:An individualized preconditioning regimen can achieve comparable graft and patient survival rates in ABOi KT with ABOc KT.Rit-free preconditioning effectively prevented AR without increasing the risk of infectious events in those with lower initial titers;however,antibody titer rebound should be monitored. | Saifu Yin Qiling Tan Youmin Yang Fan Zhang Turun Song Yu Fan Zhongli Huang Tao Lin Xianding Wang | 2022 | Chinese Medical Journal2022，135，19： | 7 |
| 7 | Metal composition of layered double hydroxides(LDHs) regulating ClO_4^- adsorption to calcined LDHs via the memory effect and hydrogen bonding显示文摘A series of calcined carbonate layered double hydroxides(CLDHs) with various metal compositions and different M2+/M3+ ratios were prepared as adsorbents for perchlorate. Adsorption isotherms fit Langmuir model well, and the adsorption amount followed the order of MgAl-CLDHs > MgFe-CLDHs >>> ZnAl-CLDHs. The isotherms of MgAl-CLDHs and MgFe-CLDHs displayed a two-step shape at low and high concentration ranges and increased with an increase in the M2+/M3+ ratio from 2 to 4. The two-step isotherm was not observed for ZnAl-CLDHs, and the adsorption was minimally affected by the M2+/M3+ ratio. The LDHs, CLDHs and the reconstructed samples were characterized by X-ray diffraction, SEM, FT-IR and Raman spectra to delineate the analysis of perchlorate adsorption mechanisms. The perchlorate adsorption of MgAl-CLDHs and MgFe-CLDHs was dominated by the structural memory effect and the hydrogen bonds between the free hydroxyl groups on the reconstructed-LDHs and the oxygen atoms of the perchlorates. For ZnAl-CLDHs, the perchlorate adsorption was controlled by the structural memory effect only, as the hydroxyl groups on the hydroxide layers preferred to form strong hydrogen bonds with carbonate over perchlorate, which locked the intercalated perchlorate into a more confined nano-interlayer. Several distinct binding mechanisms of perchlorate by CLDHs with unique M2+ ions were proposed. | Yajie Lin Qile Fang Baoliang Chen | 2014 | Journal of Environmental Sciences2014，26，3： | 6 |
| 8 | Effects of As on As uptake, speciation, and nutrient uptake by winter wheat (Triticum aestivum L.) under hydroponic conditions显示文摘一个水耕法的实验被进行调查砷的效果(作为) 生长上的应力,营养并且作为在冬小麦(Triticum aestivum L.) 的射击和根的举起,和种形成。冬小麦有高忍耐到作为。在根被积累的大多数,并且一是 4,421 mg/kg 的集中是在 20 mg/L 的答案集中被观察。在根的砷集中比在射击的那些大约 40 100 倍。在冬小麦根和射击的砷作为 As3+ 和 As5+ 种类发生了,尽管 As3+ 是在冬小麦纸巾的主要种类。砷显著地减少了在冬小麦织物的微型元件和宏元素的冬小麦射击和根和影响吸收和运输的生物资源。砷处理显著地在射击增加了全部的镁(Mg ) 和钙(Ca ) 的集中并且从根提高了 Mg 和 Ca 的运输到射击,但是减少钾(K) ,氮(N) ,和在射击和根的磷(P) 集中,特别地 P 的集中。在冬小麦射击的铁,铜,和锌的集中是否定地与有关作为率与 0.93, 0.94,和 0.97 的相关系数(R2 ) ,分别地。 | LIU Quanji HU Chengxiao TAN Qiling SUN Xuecheng SU Jingjun LIANG Yuexiang | 2008 | Journal of Environmental Sciences2008，20，3： | 5 |
| 9 | The relationships of vitamin D, vitamin D receptor gene polymorphisms, and vitamin D supplementation with Parkinson's disease显示文摘In recent years,many studies have investigated the correlations between Parkinson's disease(PD)and vitamin D status,but the conclusion remains elusive.The present review focuses on the associations between PD and serum vitamin D levels by reviewing studies on the associations of PD with serum vitamin D levels and vitamin D receptor(VDR)gene polymorphisms from PubMed,Web of Science,Cochrane Library,and Embase databases.We found that PD patients have lower vitamin D levels than healthy controls and that the vitamin D concentrations are negatively correlated with PD risk and severity.Furthermore,higher vitamin D concentrations are linked to better cognitive function and mood in PD patients.Findings on the relationship between VDR gene polymorphisms and the risk of PD are inconsistent,but the Fokl(C/M)polymorphism is significantly linked with PD.The occurrence of Fokl(CT)gene polymorphism may influence the risk,severity,and cognitive ability of PD patients,while also possibly influencing the effect of Vitamin D3 supplementation in PD patients.In view of the neuroprotective effects of vitamin D and the close association between vitamin D and dopaminergic neurotransmission,interventional prospective studies on vitamin D supplementation in PD patients should be conducted in the future. | Lingling Lv Xuling Tan Xinke Peng Rongrong Bai Qile Xiao Ting Zou Jieqiong Tan Hainan Zhang Chunyu Wang | 2020 | Translational Neurodegeneration2020，9，3： | 5 |
| 10 | Predicting the growth performance of growing-finishing pigs based on net energy and digestible lysine intake using multiple regression and artificial neural networks models显示文摘Backgrounds:Evaluating the growth performance of pigs in real-time is laborious and expensive,thus mathematical models based on easily accessible variables are developed.Multiple regression(MR)is the most widely used tool to build prediction models in swine nutrition,while the artificial neural networks(ANN)model is reported to be more accurate than MR model in prediction performance.Therefore,the potential of ANN models in predicting the growth performance of pigs was evaluated and compared with MR models in this study.Results:Body weight(BW),net energy(NE)intake,standardized ileal digestible lysine(SID Lys)intake,and their quadratic terms were selected as input variables to predict ADG and F/G among 10 candidate variables.In the training phase,MR models showed high accuracy in both ADG and F/G prediction(R^(2)_(ADG)=0.929,R^(2)_(F/G)=0.886)while ANN models with 4,6 neurons and radial basis activation function yielded the best performance in ADG and F/G prediction(R^(2)_(ADG)=0.964,R^(2)_(F/G)=0.932).In the testing phase,these ANN models showed better accuracy in ADG prediction(CCC:0.976 vs.0.861,R^(2):0.951 vs.0.584),and F/G prediction(CCC:0.952 vs.0.900,R^(2):0.905 vs.0.821)compared with the MR models.Meanwhile,the“over-fitting”occurred in MR models but not in ANN models.On validation data from the animal trial,ANN models exhibited superiority over MR models in both ADG and F/G prediction(P<0.01).Moreover,the growth stages have a significant effect on the prediction accuracy of the models.Conclusion:Body weight,NE intake and SID Lys intake can be used as input variables to predict the growth performance of growing-finishing pigs,with trained ANN models are more flexible and accurate than MR models.Therefore,it is promising to use ANN models in related swine nutrition studies in the future. | Li Wang Qile Hu Lu Wang Huangwei Shi Changhua Lai Shuai Zhang | 2022 | Journal of Animal Science and Biotechnology2022，13，6： | 5 |
| 11 | Enhanced grain refinement of Al-Si alloys by novel Al-V-B refiners显示文摘Al-V-B master alloy is promising for refining Al-Si alloys,yet its optimal composition with superior efficacy remains to be explored.In this work,the evolution of refining phases in the Al-10 Si/Al-V-B system with different V:B ratios was evaluated by thermodynamic calculations,based on which the Al-V-B refiners with V:B=1:1 and 5:1 were designed.Refining trails demonstrated that they could significantly reduce the grain size of Al-10 Si(wt.%)alloy from 1736 to 184-245μm with industrial addition amount.Detailed examinations results clarify that when V:B ratio is 1:1 the nucleation particle is(V,Al)B_(2),which has a VB_(2)-AlB_(2) core-shell structure and therefore presents the nucleation capability as AlB_(2) particle.When V:B ratio is as high as 5:1,the nucleation particle is pure VB_(2).Density functional theory(DFT)calculation indicates that(0001)VB_(2)/(111)α-Al interface has the lowest interfacial energy such that highest nucleation potency among other types of diboride/α-Al interfaces under consideration.The outcomes of this work provide fundamental guidance to develop superior V-B based refiners for Al-Si alloys. | Chenxi Zhao Yang Li Jin Xu Qun Luo Ying Jiang Qiling Xiao Qian Li | 2021 | Journal of Materials Science & Technology2021，，35： | 4 |
| 12 | Precise orbit determination for BDS satellites显示文摘Since the frst pair of BeiDou satellites was deployed in 2000,China has made continuous eforts to establish its own independent BeiDou Navigation Satellite System(BDS)to provide the regional radio determination satellite service as well as regional and global radio navigation satellite services,which rely on the high quality of orbit and clock products.This article summarizes the achievements in the precise orbit determination(POD)of BDS satellites in the past decade with the focus on observation and orbit dynamic models.First,the disclosed metadata of BDS satellites is presented and the contribution to BDS POD is addressed.The complete optical properties of the satellite bus as well as solar panels are derived based on the absorbed parameters as well the material properties.Secondly,the status and tracking capabilities of the L-band data from accessible ground networks are presented,while some low earth orbiter satellites with onboard BDS tracking capability are listed.The topological structure and measurement scheme of BDS Inter-Satellite-Link(ISL)data are described.After highlighting the progress on observation models as well as orbit perturbations for BDS,e.g.,phase center corrections,satellite attitude,and solar radiation pressure,diferent POD strategies used for BDS are summarized.In addition,the urgent requirement for error modeling of the ISL data is emphasized based on the analysis of the observation noises,and the incompatible characteristics of orbit and clock derived with L-band and ISL data are illuminated and discussed.The further researches on the improvement of phase center calibration and orbit dynamic models,the refnement of ISL observation models,and the potential contribution of BDS to the estimation of geodetic parameters based on L-band or ISL data are identifed.With this,it is promising that BDS can achieve better performance and provides vital contributions to the geodesy and navigation. | Qile Zhao Jing Guo Chen Wang Yifei Lyu Xiaolong Xu Chao Yang Junqiang Li | 2022 | Satellite Navigation2022，3，1： | 4 |
| 13 | Precise Relative Orbit Determination of Twin GRACE Satellites显示文摘当形成飞时,太空船被用作站台获得土面向的观察,在这些太空船之间的精确基线总是是必要的。严肃恢复和气候实验(优雅) 使命针对印射全球严肃地和它的变化。优雅卫星的精确基线为当模特儿的严肃地是必要的。成双的卫星的运动学、减少的动态相对轨道的决心为动态相对轨道在 2 公里的这份报纸,和精确性被学习了,为运动学的 5 公里能被获得,大多数在 GPS 歧义上的双差别由此被解决。 | ZHAO Qile HU Zhigang GUO Jing LI Min GE Maorong | 2010 | Geo-Spatial Information Science2010，13，3： | 3 |
| 14 | Screening high-quality fetal bovine serum for porcine oocyte maturation in vitro显示文摘Fetal bovine serum(FBS) is widely used in cell cultures due to its high stability and easy access. It was also used as a substitute for porcine follicular fluid(PFF) in previous studies. However, FBS components are unclear, and the presence of FBS in culture media may introduce a variation from batch to batch. This study aimed to establish an effective method to screen FBS in place of PFF in the culture media for porcine oocytes in vitro. We screened FBS from different sources by using porcine fetal fibroblast cells. The effects of six FBS samples on porcine fetal fibroblast cell growth were tested via frozen cell survival assay, cell clone formation assay, cell growth curve, and cell passage activity assay. The best serum that we called GFBS(heat-inactivated FBS, cat. no. 10500-64;Gibco) showed a similar effect on the maturation and development of porcine oocytes to that of PFF and can be used as a good substitute for PFF. These results suggested that the porcine fetal fibroblast cell culture test can be used as a valuable method to screen FBS for porcine oocyte maturation and embryonic development in vitro. | Xueqing Liu Qiaoli Lang Meng Wu Xiaoyan You Qiling He Ling Luo Zijia Liu Puying Xiao Nan Huang Xi Yang Liangpeng Ge | 2019 | Animal Models and Experimental Medicine2019，2，4： | 3 |
| 15 | Non-Darcy flow seepage characteristics of saturated broken rocks under compression with lateral constraint显示文摘sing an MTS816.03 test system and self-designed seepage apparatus,seepage tests of saturated broken rocks were conducted,and the influence of lithology,axial stress,grain size distribution and loading rate on seepage characteristics was analyzed.The results show that:(1) Under the same axial stress(12 MPa)the permeability of different lithologic samples increases in the order:gangue < mudstone < sand stone < limestone.The permeability of gangue is 3 magnitudes lower than that of limestone.The absolute value of the non-Darcy coefficient β increases in the order:limestone < sandstone < mudstone < gangue The non-Darcy coefficient β of limestone,which is positive,is 5 magnitudes lower than that of gangue.(2)With increasing axial stress,the permeability of saturated broken sandstone decreases,and the absolute value of the non-Darcy coefficient β increases.After the axial stress exceeds 12 MPa,the curves of perme ability and non-Darcy coefficient β all tend to be stable.(3) With increasing Talbol power exponent,the permeability increases,and the absolute value of the non-Darcy coefficient β decreases.(4) With increas ing loading,the permeability increases,and the absolute value of the non-Darcy coefficient β decreases When the loading rate is 0.5 kN/s,the non-Darcy coefficient β is positive. | Yu Bangyong Chen Zhanqing Ding Qile Wang Luzhen | 2016 | International Journal of Mining Science and Technology2016，26，6： | 2 |
| 16 | Precise relative positioning using real tracking data from COMPASS GEO and IGSO satellites显示文摘 | Chuang Shi Qile Zhao Zhigang Hu Jingnan Liu | 2013 | GPS Solutions2013，，1： | 2 |
| 17 | Reducing Influence of Gravity Model Error in Precise Orbit Determination of Low Earth Orbit Satellites显示文摘Based on the orbit integration and orbit fitting method, the influence of the characters of the gravity model, with different precisions, on the movement of low Earth orbit satellites was studied. The way and the effect of absorbing the influence of gravity model error on CHAMP and GRACE satellite orbits, using linear and periodical empirical acceleration models and the so-called 'pseudo-stochastic pulses' model, were also analyzed. | GUO Jinlai HU Min ZHAO Qile GUO Daoyu | 2007 | Geo-Spatial Information Science2007，10，2： | 2 |
| 18 | Near-field surface displacement and permanent deformation induced by the Alaska Mw 7.5 earthquake determined by high-rate real-time ambiguity-fixed PPP solutions显示文摘High-rate GPS data from the United States continuously operating reference stations in the Alaska region are processed using the recently developed precise point positioning(PPP) technique. The traditional PPP technique does not fix ambiguities into their integers because these ambiguities do not have an integer nature when data from a single receiver, as well as precise orbit and clock corrections, are used. Additional corrections, i.e.,uncalibrated phase delay(UPD), are needed to fix integer ambiguities and consequently improve positioning accuracy. This study proposes a methodology to compute for wide-lane and L2(the second L-band frequency) UPDs using the geometry-based model and subsequently applies these parameters to the computation for ambiguity-fixed solutions. The instantaneous displacements of near-field sites, as well as the permanent deformations after the earthquake, are therefore obtained for the January 5, 2013,Alaska earthquake. The real-time performance of PPP solutions are assessed by considering realistic data latency and data interval of corrections. Ambiguity-fixed solutions are compared with ambiguity-float ones. The comparison shows that the positioning accuracy can be improved significantly when the ambiguities are fixed correctly. Thesolutions using the real-time corrections are also compared with those using post-processing corrections, i.e., Center for Orbit Determination in Europe final orbit and clock.Although the accuracy is somehow degraded because of the data latency and data interval, the real-time results are satisfactory for use in monitoring the small-scale deformation(1–2 cm) caused by the Alaska earthquake. In addition, the kinematic ambiguity-fixed PPP solutions for7 days around the earthquake are calculated to obtain permanent pre- and post-earthquake deformations. The deformations computed from real-time and post-processing corrections do not appear to be significantly different. | Gang Chen Qile Zhao | 2014 | Chinese Science Bulletin2014，59，34： | 2 |
| 19 | A variant of raw observation approach for BDS/GNSS precise point positioning with fast integer ambiguity resolution显示文摘The Precise Point Positioning(PPP)technique uses a single Global Navigation Satellite System(GNSS)receiver to collect carrier-phase and code observations and perform centimeter-accuracy positioning together with the precise satellite orbit and clock corrections provided.According to the observations used,there are basically two approaches,namely,the ionosphere-free combination approach and the raw observation approach.The former eliminates the ionosphere effects in the observation domain,while the latter estimates the ionosphere effects using uncombined and undifferenced observations,i.e.,so-called raw observations.These traditional techniques do not fix carrier-phase ambiguities to integers,if the additional corrections of satellite hardware biases are not provided to the users.To derive the corrections of hardware biases in network side,the ionosphere-free combination operation is often used to obtain the ionosphere-free ambiguities from the L1 and L2 ones produced even with the raw observation approach in earlier studies.This contribution introduces a variant of the raw observation approach that does not use any ionosphere-free(or narrow-lane)combination operator to derive satellite hardware bias and compute PPP ambiguity float and fixed solution.The reparameterization and the manipulation of design matrix coefficients are described.A computational procedure is developed to derive the satellite hardware biases on WL and L1 directly.The PPP ambiguity-fixed solutions are obtained also directly with WL/L1 integer ambiguity resolutions.The proposed method is applied to process the data of a GNSS network covering a large part of China.We produce the satellite biases of BeiDou,GPS and Galileo.The results demonstrate that both accuracy and convergence are significantly improved with integer ambiguity resolution.The BeiDou contributions on accuracy and convergence are also assessed.It is disclosed for the first time that BeiDou only ambiguity-fixed solutions achieve the similar accuracy with that of GPS/Galileo combined,at least in China's Mainland.The numerical analysis demonstrates that the best solutions are achieved by GPS/Galileo/BeiDou solutions.The accuracy in horizontal components is better than 6 mm,and in the height component better than 20 mm(one sigma).The mean convergence time for reliable ambiguity-fixing is about 1.37 min with 0.12 min standard deviation among stations without using ionosphere corrections and the third frequency measurements.The contribution of BDS is numerically highlighted. | Qile Zhao Jing Guo Sijing Liu Jun Tao Zhigang Hu Gang Chen | 2021 | Satellite Navigation2021，2，1： | 2 |
| 20 | Precise relative positioning using real tracking data from COMPASS GEO and IGSO satellites显示文摘 | Chuang Shi Qile Zhao Zhigang Hu Jingnan Liu | 2013 | GPS Solutions2013，，1： | 2 |
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