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Minimal least eigenvalue of connected graphs of order n and size m=n+k(5≤k≤8)

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Frontiers of Mathematics in China 2019年第6期14卷 1213-1230页

作者： Xin LI jiming guo Zhiwen WANG Department of Mathematics Bast China University of Science and TechnologyShanghai 200237China

The least eigenvalue of a connected graph is the least eigenvalue of its adjacency *** characterize the connected graphs of order n and size n+k(5≤k≤8 and n≥k+5)with the minimal least eigenvalue.

关键词： Least eigenvalue adjacency matrix graph

Distance signless Laplacian eigenvalues of graphs

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Frontiers of Mathematics in China 2019年第4期14卷 693-713页

作者： Kinkar Chandra DAS Huiqiu LIN jiming guo Department of Mathematics Sungkyunkwan University Suwon 16419 Republic of Korea Department of Mat hematics East China University of Science and Technology Shanghai 200237 China

Suppose that the vertex set of a graph G is V(G) ={v1,v2,...,vn}.The transmission Tr(vi) (or Di) of vertex vi is defined to be the sum of distances from vi to all other *** Tr(G) be the n × n diagonal matrix with its (i,i)-entry equal to TrG(vi).The distance signless Laplacian spectral radius of a connected graph G is the spectral radius of the distance signless Laplacian matrix of G,defined as L(G) =Tr(G) + D(G),where D(G) is the distance matrix of *** this paper,we give a lower bound on the distance signless Laplacian spectral radius of graphs and characterize graphs for which these bounds are best *** obtain a lower bound on the second largest distance signless Laplacian eigenvalue of ***,we present lower bounds on the spread of distance signless Laplacian matrix of graphs and trees,and characterize extremal graphs.

关键词： Graph distance signless Laplacian spectral radius second largest eigenvalue of distance signless Laplacian matrix spread

Assessment of tomographic window and sampling rate efects on GNSS water vapor tomography

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Satellite Navigation 2023年第1期4卷 155-166,I0005页

作者： Fei Yang Yilin Sun Xiaolin Meng jiming guo Xu Gong College of Geoscience and Surveying Engineering China University of Mining and Technology-BeijingBeijing 100083China College of Architecture and Civil Engineering Beijing University of TechnologyBeijing 100124China School of Geodesy and Geomatics Wuhan UniversityWuhan 430079China

The ground-based Global Navigation Satellite System(GNSS)water vapor tomography is increasingly important in GNSS *** the multi-GNSS and more ground-based GNSS sites can be incorporated into the regional water vapor tomographic model,determining the tomographic window and sampling rate is crucial for the modelling of the water vapor *** two factors afect not only the number of available signal rays from the satellites,but also the number of tomographic voxels crossed by the signal *** study uses Hong Kong as the research area to explore the impact of 12 schemes with diferent tomographic window and sampling rate on the three water vapor tomography methods,including Least squares,Kalman fltering,and Multiplicative Algebraic Reconstruction Technique(MART).Numerical results show that the tomographic results with the three methods get better as the width of the tomographic window decreases and the sampling rate increases in these 12 schemes,and it is found that the Least squares method is most afected by the two factors,followed by Kalman fltering and MART *** is recommended to set a tomographic window width of 10 min and a sampling rate of 300 s in a GNSS water vapor tomographic experiment with dense GNSS site like Hong Kong.

关键词： GNSS meteorology Water vapor Tomography

The Least Eigenvalue of Unicyclic Graphs with Application to Spectral Spread

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Algebra Colloquium 2022年第2期29卷 265-272页

作者： jiming guo Gege Zhang Zhiwen Wang Panpan Tong School of Mathematics East China University of Science and Technology Shanghai 200237China

Let U^(g)_(n)be the set of connected unicyclic graphs of order n and girth *** C(T_(1),T_(2),…,T_(g))∈U^(g)_(n)be obtained from a cycle v_(1)v_(2)…v_(g)v_(1)(in an anticlockwise direction)by identifying v_(i)with the root of a rooted tree T_(i)of order n_(i)for each i=1,2,…,g,where n_(i)≥1 and∑^(g)_(i=1)n_(i)=*** this note,the graph with the minimal least eigenvalue(and the graph with maximal spread)in C(T_(1),T_(2),…,T_(g))is determined.

关键词： adjacency matrix least eigenvalue eigenvector unicyclic graph

Development and evaluation of the refined zenith tropospheric delay(ZTD)models

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Satellite Navigation 2021年第1期2卷 296-304页

作者： Fei Yang Xiaolin Meng jiming guo Debao Yuan Ming Chen College of Geoscience and Surveying Engineering China University of Mining and Technology-Beijing100083 BeijingChina Global Geospatial Engineering Ltd. The Sino-UK Geospatial Engineering Centre18 Radford Bridge RoadNottingham NG81NAUK School of Geodesy and Geomatics Wuhan University129 Luoyu RoadWuhan 430079China National Geomatics Center of China Beijing 100830China.

The tropospheric delay is a significant error source in Global Navigation Satellite System(GNSS)positioning and *** is usually projected into zenith direction by using a mapping *** is particularly important to establish a model that can provide stable and accurate Zenith Tropospheric Delay(ZTD).Because of the regional accuracy difference and poor stability of the traditional ZTD models,this paper proposed two methods to refine the Hopfield and Saastamoinen ZTD *** is by adding annual and semi-annual periodic terms and the other is based on Back-Propagation Artificial Neutral Network(BP-ANN).Using 5-year data from 2011 to 2015 collected at 67 GNSS reference stations in China and its surrounding regions,the four refined models were *** tropospheric products at these GNSS stations were derived from the site-wise Vienna Mapping Function 1(VMP1).The spatial analysis,temporal analysis,and residual distribution analysis for all the six models were conducted using the data from 2016 to *** results show that the refined models can effectively improve the accuracy compared with the traditional *** the Hopfield model,the improvement for the Root Mean Square Error(RMSE)and bias reached 24.5/49.7 and 34.0/52.8 mm,*** values became 8.8/26.7 and 14.7/28.8 mm when the Saastamoinen model was refined using the two *** exploration is conducive to GNSS navigation and positioning and GNSS meteorology by providing more accurate tropospheric prior information.

关键词： GNSS Tropospheric delay ZTD Refined model ANN

Planar Graphs whose Second Largest Eigenvalue Smaller than ■

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Journal of Mathematical Research with Applications 2024年第1期44卷 1-6页

作者： Zihao GENG jiming guo Department of Mathematics East China University of Science and Technology

A graph G is said to be planar if G can be drawn on the plane in such a way that its edges intersect only at their *** this paper,all the planar graphs without isolated vertices whose second largest eigenvalue smaller... 详细信息

关键词： planar graph the second largest eigenvalue complete product

The Laplacian spectral radii of unicyclic and bicyclic graphs with n vertices and k pendant vertices

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Science China Mathematics 2010年第8期53卷 2135-2142页

作者： guo jiming Department of Applied Mathematics,China University of Petroleum,Dongying 257061,China 1. Department of Applied Mathematics China University of Petroleum Dongying 257061 China

In this paper,we determine graphs with the largest Laplacian spectral radius among the unicyclic and the bicyclic graphs on n vertices with k pendant vertices,respectively.

关键词： Laplacian matrix Laplacian spectral radius unicyclic graph bicyclic graph

Data Transformation for Super-totalstation Positioning System Integrated by GPS and Totalstation

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Geo-Spatial Information Science 2003年第1期6卷 38-42页

作者： guo jiming ZHANG Zhenglu LUO Nianxue HUANG Quanyi School of Geodesy and Geomatics Wuhan University

This paper focuses on the integration and data transformation between GPS and *** emphasizes on the way to transfer the WGS84 Cartesian coordinates to the local two_dimensional plane coordinates and the orthometric height GPS receiver,totalstation,radio,notebook computer and the corresponding software work together to form a new surveying system,the super_totalstation positioning system(SPS) and a new surveying model for terrestrial *** the help of this system,the positions of detail points can be measured.

关键词： GPS TPS SPS data transformation

Single Point Positioning with Sequential Least-Squares Filter and Estimated Real-Time Stochastic Model

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Geo-Spatial Information Science 2008年第1期11卷 13-16页

作者： WU Yun guo jiming School of Geodesy and Geomatics Wuhan University 129 Luoyu Road Wuhan 430079 China 不详

To obtain higher accurate position estimates, the stochastic model is estimated by using residual of observations, hence, the stochastic model describes the noise and bias in measurements more realistically. By using GPS data and broadcast ephemeris, the numerical results indicating the accurate position estimates at sub-meter level are obtainable.

关键词： GPS single point positioning functional model stochastic model sequential least-square filter