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Analysis of Galileo signal-in-space range error and positioning performance during 2015-2018

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Satellite Navigation 2020年第1期1卷 55-67页

作者： Weiwang Wu fei guo Jiazhu Zheng School of Geodesy and Geomatics Wuhan University129 Luoyu RoadWuhan 430079China College of Civil Engineering Nanjing Forestry University159 Lonpan RoadNanjing 210037China

A long-term analysis of signal-in-space range error (SISRE) is presented for all healthy Galileo satellites, and the first pair of full operational capability satellites in wrong elliptical orbits. Both orbit and clock errors for Galileo show an obvious convergence trend over time. The annual statistical analyses show that the average root mean squares (RMSs) of SISRE for the Galileo constellation are 0.58 m (2015), 0.29 m (2016), 0.23 m (2017), and 0.22 m (2018). Currently, the accuracy of the Galileo signal-in-space is superior to that of the global positioning system (GPS) Block IIF (0.35 m). In addition, the orbit error accounts for the majority of Galileo SISRE, while the clock error accounts for approximately one-third of SISRE due to the high stability of the onboard atomic clock. Single point positioning results show that Galileo achieves an accuracy of 2-3 m, which is comparable to that of GPS despite the smaller number of satellites and worse geometry. Interestingly, the vertical accuracy of Galileo, which uses the NeQuick ionospheric model, is higher than that of GPS. Positioning with single frequency E1 and E5 show a higher precision than E5a and E5b signals. Regarding precise point positioning (PPP), the results indicate that a comparable positioning accuracy can be achieved among different stations with the current Galileo constellation. For static PPP, the RMS values of Galileo-only solutions are within 1 cm horizontally, and the vertical RMSs are mostly within 2 cm horizontally. For kinematic PPP, the RMSs of Galileo-only solutions are mostly within 4 cm horizontally and 6 cm vertically.

关键词： Galileo Signal in space range error(SISRE) Single point positioning(SPP) Precise point positioning(PPP)

Existence of periodic solutions for second-order Hamiltonian systems with asymptotically linear conditions

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Frontiers of Mathematics in China 2018年第6期13卷 1313-1323页

作者： Xingfan CHEN fei guo Peng LIU School of Mathematics Tianjin UniversityTianjin 300354China

We consider a class of asymptotically linear nonautonomous second-order Hamiltonian systems. Using the Saddle Point Theorem, we obtain the existence result, which extends some previously known results.

关键词： Existence periodic solution second-order Hamiltonian systems Saddle Point Theorem

Global Dynamic Modeling of Electro-Hydraulic 3-UPS/S Parallel Stabilized Platform by Bond Graph

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Chinese Journal of Mechanical Engineering 2016年第6期29卷 1176-1185页

作者： ZHANG Lijie guo fei LI Yongquan LU Wenjuan Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University

Dynamic modeling of a parallel manipulator（PM） is an important issue. A complete PM system is actually composed of multiple physical domains. As PMs are widely used in various fields, the importance of modeling the global dynamic model of the PM system becomes increasingly prominent. Currently there lacks further research in global dynamic modeling. A unified modeling approach for the multi-energy domains PM system is proposed based on bond graph and a global dynamic model of the 3-UPS/S parallel stabilized platform involving mechanical and electrical-hydraulic elements is built. Firstly, the screw bond graph theory is improved based on the screw theory, the modular joint model is modeled and the normalized dynamic model of the mechanism is established. Secondly, combined with the electro-hydraulic servo system model built by traditional bond graph, the global dynamic model of the system is obtained, and then the motion, force and power of any element can be obtained directly. Lastly, the experiments and simulations of the driving forces, pressure and flow are performed, and the results show that, the theoretical calculation results of the driving forces are in accord with the experimental ones, and the pressure and flow of the first limb and the third limb are symmetry with each other. The results are reasonable and verify the correctness and effectiveness of the model and the method. The proposed dynamic modeling method provides a reference for modeling of other multi-energy domains system which contains complex PM.

关键词： screw bond graph multi-energy domains 3-UPS/S parallel mechanism electro-hydraulic servo system

Nuclear dynamics in multinucleon transfer reactions near Coulomb barrier energies

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Nuclear Science and Techniques 2018年第12期29卷 128-133页

作者： Peng-Hui Chen fei Niu Ya-fei guo Zhao-Qing Feng Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000 China University of Chinese Academy of Sciences Beijing 100190China South China University of Technology Guangzhou 510641China

The mechanism of multinucleon transfer reactions has been investigated within the dinuclear system model, in which the sequential nucleon transfer is described by solving a set of microscopically derived master equations. The transfer dynamics in the reaction of^(136)Xe+^(208)Pb near Coulomb barrier energies is thoroughly analyzed. It is found that the total kinetic energies of primary fragments are dissipated from the relative motion energy of two touching nuclei and exhibit a symmetric distribution along the fragment mass. The angular distribution of the projectile-like fragments moves forward with increasing beam energy. However, the target-like fragments exhibit an opposite trend. The shell effect is pronounced due to the fragment yields in multinucleon transfer reactions.

关键词：原子动力学转移反应精力库仑相对运动显微镜子转移原子核

Atomic origin of the traps in memristive interface

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Nano Research 2017年第6期10卷 1924-1931页

作者： Ye Tian Lida Pan Chuan fei guo Qian Liu CAS Center of Excellence for Nanoscience CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology No. 11 Beiyitiao Zhongguancun Beijing 100190 China School of Communication and Electronics Engineering Hunan City University Yiyang 413000 China Department of Physics and Astronomy Vanderbilt University Nashville TN 37235 USA Institute of Physics Chinese Academy of Sciences Beijing 100190 China Photonics Research Group Department of Information Technology Ghent University-IMEC Ghent B-9000 Belgium Department of Materials Science and Engineering South University of Science and Technology of China Shenzhen 518055 China

In recent years, trap-related interfacial transport phenomena have received great attention owing to their potential applications in resistive switching devices and photo detectors. Not long ago, one new type of memristive interface that is composed of F-doped SnO2 and Bi2S3 nano-network layers has demonstrated a bivariate-continuous-tunable resistance with a swift response comparable to the one in neuron synapses and with a brain-like memorizing capability. However, the resistive mechanism is still not clearly understood because of lack of evidence, and the limited improvement in the development of the interfacial device. By combining I-V characterization, electron energy-loss spectroscopy, and first- principle calculation, we studied in detail the macro/micro features of the memristive interface using experimental and theoretical methods, and confirmed that its atomic origin is attributed to the traps induced by O-doping. This implies that impurity-doping might be an effective strategy for improving switching features and building new interfacial memristors.

关键词： memristance interface trap state first principle calculation

On Distance Laplacian Spectra of Certain Finite Groups

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Acta Mathematica Sinica,English Series 2023年第4期39卷 603-617页

作者： Bilal Ahmad RATHER Shariefuddin PIRZADA guo fei ZHOU Department of Mathematics University of KashmirSrinagarIndia Department of Mathematics Nanjing UniversityNanjing 210093P.R.China

For a finite group G,the power graph P(G)is a simple connected graph whose vertex set is the set of elements of G and two distinct vertices x and y are adjacent if and only if x^(i)=y or y^(i)=x,for 2≤i,j≤*** this paper,we obtain the distance Laplacian spectrum of power graphs of finite groups such as cyclic groups,dihedral groups,dicyclic groups,abelian groups and elementary abelian p ***,we find the largest and second smallest distance Laplacian eigenvalue of power graphs of such groups.

关键词： Laplacian matrix distance Laplacian matrix finite groups power graphs

Empirical correction of kinetic model for polymer thermal reaction process based on first order reaction kinetics

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Chinese Journal of Chemical Engineering 2021年第10期34卷 132-144页

作者： Zhaoxiang Zhang fei guo Wei Song Xiaohong Jia Yuming Wang State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China Joint Research Center for Rubber and Plastic Seals Tsinghua UniversityBeijing 100084China State Key Laboratory of Advanced Forming Technology&Equipment China Academy of Machinery Science&TechnologyBeijing 100044China Tianding Sealing Technology(Beijing)Co. Ltd.Beijing 100072China

Based on the theory of first-order reaction kinetics,a thermal reaction kinetic model in integral form has been *** make the model more applicable,the effects of time and the conversion degree on the reaction rate parameters were *** types of undetermined functions were used to compensate for the intrinsic variation of the reaction rate,and two types of correction methods are *** model was explained and verified using published experimental data of different polymer thermal reaction systems,and its effectiveness and wide adaptability were *** the given kinetic model,only one parameter needs to be *** proposed empirical model is expected to be used in the numerical simulation of polymer thermal reaction process.

关键词： Thermal reaction Polymer processing Reaction kinetics Mathematical modeling Empirical correction

Effect of contact forms on the wear of hard silicon surfaces by soft polymers

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Friction 2021年第5期9卷 918-928页

作者： Zhaoxiang ZHANG Xiaohong JIA fei guo Zhongde SHAN Yuming WANG State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China Joint Research Center for Rubber and Plastic Seals Tsinghua UniversityBeijing 100084China State Key Laboratory of Advanced Forming Technology&Equipment China Academy of Machinery Science&TechnologyBeijing 100044China

The mechanism of hard surfaces worn by soft polymers is not clearly *** this paper,a new hypothesis has been proposed,it holds that the stress acting on the hard surface under certain working conditions is the main reason for wear of the hard surface by a soft *** hypothesis was investigated by changing the contact form between *** this,friction tests between six polymer spheres and smooth,rough,and inclined monocrystalline silicon surfaces were carried *** results show that for the same tribo-pair,the silicon surface will not be worn in some contact forms,but in other contact forms it will be *** believe the wear of hard surface by a soft polymer is the result of the combined stress state action on the hard surface.

关键词： polymers silicon surface wear combined stress

Accelerated Deterioration Mechanism and Reliability Evaluation of Concrete in Saline Soil Area

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Journal of Wuhan University of Technology(Materials Science) 2023年第3期38卷 582-590页

作者：付勇乔宏霞 HAKUZWEYEZU Theogene QIAO guobin guo fei School of Civil Engineering Lanzhou University of TechnologyLanzhou 730050China Western Civil Engineering Disaster Prevention and Mitigation Engineering Research Center Ministry of EducationLanzhou University of TechnologyLanzhou 730050China

To reveal the deterioration mechanism and service life of concrete durability in the western saline soil area,the indoor accelerated test of the concrete specimen was simulated in the coupled environment of salt erosion and dry-wet cycles in the west saline soil area of *** deterioration mechanism of concrete durability was revealed through the relative dynamic elastic modulus,relative quality evaluation parameters,SEM,and XRD evaluation *** Wiener distribution function was used for modeling life *** results show that the relative dynamic elastic modulus evaluation parameter as an evaluation index of concrete durability under various environmental coupling effects is more reliable than the relative quality,there were holes and cracks in the concrete,and needle-like and layered crystals grow from the internal *** corrosion products include ettringite,gypsum and other expansive crystals and non-gelling Mg(OH)_(2);the expansion stress caused by physical,chemical reaction,and temperature change under the action of drywet cycle aggravates the formation and development of *** random Wiener distribution function can describe the degradation process of concrete specimen durability,and the established concrete reliability function can intuitively reflect the service life of concrete specimens.

关键词： concrete saline soil area service prediction random wiener durability deterioration mechanism