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Signal quality analysis and quality check of BDS3 Precise Point Positioning in the Arctic Ocean

Acta Oceanologica Sinica 2022年第2期41卷 166-179页

作者： xiaoguo Guan Hongzhou Chai guorui xiao Zhenqiang Du Wenlong Qi Xueping Wang College of Urban and Environmental Sciences Xuchang UniversityXuchang 461000China Institute of Geospatial Information Information Engineering UniversityZhengzhou 450001China Department of Civil Engineering Henan Vocational College of Water Conservancy and EnvironmentZhengzhou 450001China

This study analyzes the signal quality and the accuracy of BeiDou 3 rd generation Satellite Navigation System(BDS3) Precise Point Positioning(PPP) in the Arctic Ocean. Assessment of signal quality of BDS3 includes signal to noise ratio(SNR), multipath(MP), dilution of precision(DOP), and code-minus-carrier combination(CC). The results show that, 5 to 13 satellites are visible at any time in the Arctic Ocean area as of September 2018, which are sufficient for positioning. In the mid-latitude oceanic region and in the Arctic Ocean, the SNR is 25–52 dB Hz and the MP ranges from-2 m to 2 m. As the latitude increases, the DOP values show large variation, which may be related to the distribution of BDS satellites. The CC values of signals B1 I and BIC range from-5 m to 5 m in the mid-latitude sea area and the Arctic Ocean, which means the effect of pseudorange noise is small. Moreover, as to obtain the external precise reference value for GNSS positioning in the Arctic Ocean region is difficult, it is hard to evaluate the accuracy of positioning results. An improved isotropy-based protection level method based on Receiver Autonomous Integrity Monitoring is proposed in the paper, which adopts median filter to smooth the gross errors to assess the precision and reliability of PPP in the Arctic Ocean. At first, the improved algorithm is verified with the data from the International GNSS Service Station Tixi. Then the accuracy of BDS3 PPP in the Arctic Ocean is calculated based on the improved algorithm. Which shows that the kinematic accuracy of PPP can reach the decimeter level in both the horizontal and vertical directions, and it meets the precision requirements of maritime navigation.

关键词： BDS3 Arctic Ocean signal quality analysis protection level quality check Precise Point Positioning satellite navigation

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Structural evolution and superconductivity tuned by valence electron concentration in the Nb-Mo-Re-Ru-Rh high-entropy alloys

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Journal of Materials Science & Technology 2021年第26期85卷 11-17页

作者： Bin Liu Jifeng Wu Yanwei Cui Qjnqing Zhu guorui xiao Siqi Wu Guang-han Cao Zhi Ren School of Science Westlake University18 Shilongshan RoadHangzhou310064China Institute of Natural Sciences Westlake Institute for Advanced StudyHangzhou310064China Department of Physics Fudan UniversityShanghai200433China Department of Physics Zhejiang UniversityHangzhou310027China

The crystal structure and physical properties of Nb_(25)Mo_(5+x)Re_(35)Ru_(25-x)Rh_(10)(0≤x≤10)and Nb_(5)Mo_(35-y)Re_(15+y)Ru_(35)Rh_(10)(0≤y≤15)high-entropy alloys(HEAs)have been studied by X-ray diffraction,electrical resistivity,magnetic susceptibility,and specific heat *** results show that the former HEAs with valence electron concentration(VEC)values of 6.7-6.9 crystallize in a noncentrosymmetric cubicα-Mn structure,while the latter ones with VEC values of 7.1-7.25 adopt a centrosymmetric hexagonal close-packed(hcp)*** different structures,both series of HEAs are found to be bulk superconductors with a full energy gap,and the superconducting transition temperature Tc tends to decrease with the increase of ***,the Tc values of the hcp-type HEAs are higher than those of theα-Mn-type ones,likely due to a stronger electron phonon ***,we show that VEC and electronegativity difference are two key parameters to control the stability ofα-Mn and hcp-type *** results not only are helpful for the design of such HEAs,but also represent the first realization of structurally different HEA superconductors without changing the constituent elements.

关键词： High-entropy alloys Hcp toα-Mn structural evolution Superconducting properties Valence electron concentration Electronegativity difference

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Superconductivity and strong spin-orbit coupling in a new noncentrosymmetric compound ThIrP

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Science China(Physics,Mechanics & Astronomy) 2021年第10期64卷 95-102页

作者： guorui xiao QinQing Zhu YanWei Cui WuZhang Yang BaiZhuo Li SiQi Wu Guang-Han Cao Zhi Ren Department of Physics Zhejiang UniversityHangzhou 310027China School of Science Westlake UniversityHangzhou 310064China Institute of Natural Sciences Westlake Institute for Advanced StudyHangzhou 310064China Department of Physics Fudan UniversityShanghai 200433China

A new noncentrosymmetric phosphide ThIrP has been synthesized and characterized. X-ray difraction analysis shows that this compound crystallizes in a LaPtSi-type tetragonal lattice(space group I41md, Z = 4), whose lattice parameters are a = b =4.0676(1) ?, c = 14.3354(2) ?, and V = 237.191(8) ?3. Moreover, ThIrP is discovered to be an intermediately coupled,type-Ⅱ superconductor with possibly multiple gaps below Tc= 5.07 K. The upper critical magnetic field, Sommerfield coefficient, and Ginzburg-Laudau parameter are determined based on physical property measurements, which are Bc2= 0.83 T, γ =7.5 mJ mol-1 K-2, and κGL= 7.5, respectively. The electronic band structure calculations point out nearly equal contributions of Ir and Th atoms on the density of states around the Fermi surface. In addition, the spin-orbit coupling induced band splitting reaches as large as 270 meV along the Γ-Z line. Our results suggest that ThIrP provides a platform to study the interplay between inversion-symmetry breaking, strong spin-orbit coupling, and superconductivity.

关键词： ThIrP noncentrosymmetric superconductivity spin-orbit coupling

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Galileo校正卫星天线参数特性及对PPP定位的影响

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武汉大学学报（信息科学版） 2022年第4期47卷 526-532页

作者：尹潇柴洪洲齐文龙肖国锐信息工程大学地理空间信息学院河南郑州450001

与先期采用消电离层组合仅估计相位中心偏差(phase center offset,PCO)参数不同,欧洲的伽利略(Galileo)系统发布的地面校正的卫星天线参数基于原始频点,且包含天线相位中心变化(phase center variation,PCV)参数。为此,分析了校正的卫... 详细信息

与先期采用消电离层组合仅估计相位中心偏差(phase center offset,PCO)参数不同,欧洲的伽利略(Galileo)系统发布的地面校正的卫星天线参数基于原始频点,且包含天线相位中心变化(phase center variation,PCV)参数。为此,分析了校正的卫星天线参数特性,发现其水平向PCO与卫星类型相关,FOC(full operational capability)卫星的PCV参数较IOV(in‐orbit validation)卫星稳定,仅依赖天底角。利用20个MGEX(multi‐GNSS experiment)测站连续15 d的数据分析校正天线参数对双频组合/非组合精密单点定位(precise point positioning,PPP)的影响,并与消电离层天线参数的定位结果比较,结果表明,其水平方向精度基本一致,双频组合PPP高程方向的精度提高约6.3%,双频非组合高程方向的精度提高约11.9%,基于原始频点的校正天线参数在双频非组合PPP定位中表现出更优的自洽性。

关键词：卫星天线参数原始频点精密单点定位 Galileo

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Comparison of attitude determination approaches using multiple Global Positioning System (GPS) antennas

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Geodesy and Geodynamics 2013年第1期4卷 16-22页

作者： Wang Bing Sui Lifen xiao guorui Duan Yu Qi Guobin Geospatial Information Institute Information Engineering University

GPS-based attitude system is an important research field, since it is a valuable technique for the attitude determination of platforms. There exist two classes approaches for attitude determination using the GPS. The one determines attitude via baseline estimates in two frames, the other one solves for attitude by incorporating the attitude parameters directly into the GPS measurements. However, comparisons between these two classes approaches have been unexplored. First of all, two algorithms are introduced in detail which on behalf of these two kinds of approaches. Then we present numerical simulations demonstrating the performance of our algorithms and provide a comparison evaluating.

关键词： GPS attitude determination baseline attitude matrix constrained LAMBDA multivariate constrained LAMBDA

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EMD De-Noising Theory Considering Static and Dynamic Conditions and Its Applications in INS

EMD De-Noising Theory Considering Static and Dynamic Conditi...

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第四届中国卫星导航学术年会

作者： Yu Gan Lifen Sui guorui xiao Yu Duan Geospatial Information Institute Information Engineering University

De-noising IMU data is an important approach to improve the accuracy of INS. Wavelet threshold de-noising has many limitations under certain conditions, especially in processing inertial sensor errors. Based on Empirical Mode Decomposition （EMD）, a novel systematic de-noising methodology for inertial sensor errors is established, including EMD compulsive de-noising, feasible in static conditions, and EMD threshold de-noising, feasible in dynamic conditions. For static data, EMD compulsive de-noising method first disposes IMFs of exceptional noise by 2sigma criterion and then the number of IMFs of high frequency noise is determined by correlation coefficient. The de-noising process is finally done by reconstructing the other IMFs. For dynamic data, EMD threshold de-noising method utilizes fractional Gaussian noise as the model of inertial sensor errors. The model parameter estimation method by power spectral density is given. Noise variance in IMFs is derived and noise thresholds of IMFs are estimated through the obtained variance.

关键词： INS · Empirical Mode Decomposition (EMD) · compulsive de-noising · threshold de-noising·colored noise·wavelet

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Interstitially carbon-alloyed refractory high-entropy alloys with a body-centered cubic structure

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Science China Materials 2022年第2期65卷 494-500页

作者： Yanwei Cui Qinqing Zhu guorui xiao Wuzhang Yang Yabin Liu Guang-Han Cao Zhi Ren School of Science Westlake UniversityHangzhou 310024China Institute of Natural Sciences Westlake Institute for Advanced StudyHangzhou 310024China Department of Physics Zhejiang UniversityHangzhou 310027China Department of Physics Fudan UniversityShanghai 200433China

The introduction of carbon interstitials into high-entropy alloys(HEAs)provides an effective way to improve their ***,all such HEA systems explored so far are limited to those with the face-centered-cubic(fcc)*** we report the structural,mechanical and physical properties of the refractory(Nb_(0.375)Ta_(0.25)Mo_(0.125)W_(0.125)Re_(0.125))_(100−x)C_(x) HEAs over a wide x range of 0≤x≤*** is found that,whereas the starting HEA(x=0)is composed of a major body-centered-cubic(bcc)phase with significant impurities,the bcc phase fraction increases with the C concentration and achieves almost 100%at x=***,the increase of C content x results in an expansion of the bcc lattice,an enhancement of the microhardness,an increase in residual resistivity and a small variation of density of states at the Fermi *** these features are consistent with the expectation that carbon atoms occupy the interstitial *** x≥11.1,the X-ray photoelectron spectroscopy indicates the bond formation between the carbon and metal atoms,suggesting that some carbon atoms may also reside in the lattice *** addition,a semiquantitative analysis shows that the enhanced mixing entropy caused by carbon addition plays a key role in stabilizing the(nearly)single solid-solution *** study not only provides the first series of carbon interstitial HEAs with a bcc structure,but also helps to better understand the alloying behavior of carbon in refractory HEAs.

关键词： body-centered cubic structure carbon-alloyed highentropy alloys

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三频非组合模型的GPS/BDS/Galileo精密定轨

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测绘学报 2021年第2期50卷 169-180页

作者：曾添隋立芬阮仁桂贾小林肖国锐 93216部队北京100085 信息工程大学河南郑州450001 地理信息工程国家重点实验室陕西西安710054 西安测绘研究所陕西西安710054

四大GNSS导航卫星系统发播三频及以上观测数据成为必然趋势。本文基于IGS钟差基准研究了三频非组合(UC)精密定轨模型及其模糊度固定方法。将载波相位硬件延迟分成时变和时不变参数,并进行参数重组,得到三频非组合定轨观测模型;类似精密... 详细信息

四大GNSS导航卫星系统发播三频及以上观测数据成为必然趋势。本文基于IGS钟差基准研究了三频非组合(UC)精密定轨模型及其模糊度固定方法。将载波相位硬件延迟分成时变和时不变参数,并进行参数重组,得到三频非组合定轨观测模型;类似精密定位中的超宽巷、宽巷、窄巷的分步模糊度固定策略,使用双差法推导了三频非组合模糊度固定方法。以发射三频信号的GPS IIF、BDS-2、Galileo卫星为例,进行1/2频点消电离层组合(IF)定轨、1/3频点IF定轨、1/2频点UC定轨和三频UC定轨共4种方案进行试验,使用外部轨道产品、天边界连接点、卫星激光测距3个手段对定轨结果进行验证,评定第三频点对轨道、钟差及其他参数的贡献。结果表明第3频点观测量对精密定轨贡献很小(不到5%);同时发现GPS三频定轨较L1/L2双频定轨可将定轨产品精度提升10%左右,原因可能是L5较L2频点具有更高的码片率和信号功率。

关键词：精密轨道确定 GNSS 三频模糊度固定非组合模型

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A new ambiguity resolution method applied to uncombined precise orbit determination

A new ambiguity resolution method applied to uncombined prec...

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第十一届中国卫星导航年会

作者： Tian Zeng xiaodong Qin Lifen Sui Rengui Ruan xiaolin Jia guorui xiao Information Engineering University State Key Laboratory of Geo-Information Engineering China Satellite Launch and Tracking Control Genetal

With the continuous refinement of multi-GNSS and multi-frequency data processing, there is an increasing interest for the observation model based on uncombined(UC) strategy. Ambiguity resolution is im

关键词： Uncombined observation model precise orbit determination GPS wide lane ambiguity MW combination

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Polymorphism and superconductivity in the V-Nb-Mo-Al-Ga high-entropy alloys

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Science China Materials 2020年第5期63卷 823-831页

作者： Jifeng Wu Bin Liu Yanwei Cui Qinqing Zhu guorui xiao Hangdong Wang Siqi Wu Guanghan Cao Zhi Ren Department of Physics Fudan UniversityShanghai 200433China School of Science Westlake UniversityHangzhou 310024China Institute of Natural Sciences Westlake Institute for Advanced StudyHangzhou 310024China Department of Physics Zhejiang UniversityHangzhou 310027China Department of Physics Hangzhou Normal UniversityHangzhou 310036China

High-entropy alloys(HEAs)are the focus of current research for their diverse properties,including superconductivity and structural ***,the polymorphic transition has been observed only in nonsuperconducting HEAs mostly under high *** we report the discovery of the superconductivity and temperature-driven polymorphism in(V0.5Nb0.5)3-xMoxAl0.5Ga0.5(0.2≤x≤1.4)HEAs,which are of a single body-centered cubic(bcc)structure for x=0.2 and a mixture of the bcc and A15 structures for higher x *** annealing,the bcc structure undergoes a polymorphic transformation to the A15 one and all HEAs exhibit bulk *** the sample with x=0.2,the bcc polymorph is not superconducting down to1.8 K,whereas the A15 polymorph has a superconducting transition temperature Tc of 10.2 K and estimated zero-temperature upper critical field Bc2(0)of 20.1 T,both of which are the highest among HEA *** increasing Mo content x,both Tc and Bc2(0)of the A15-type HEAs decrease,yet the large ratio of Bc2(0)/Tc signifies a disorder-induced enhancement of the upper critical field over a wide x *** decrease in Tc is attributed to the decrease in both the electronic specific-heat coefficient and electron-phonon coupling ***,the valence electron count dependence of Tc,which is different from both the binary A15 and other structurally different HEA superconductors,suggests that Tc may be increased further by reducing the number of valence *** results not only uncover HEA superconductors of a new structural type,but also provide the first example of polymorphism-dependent superconductivity in HEAs.

关键词： polymorphsim superconductivity V-Nb-Mo-Al-Ga high-entropy alloys

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