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The mathematical weighting of GNSS observations based on different types of receivers/antennas and environmental conditions

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Geodesy and Geodynamics 2023年第5期14卷 521-540页

作者： Kamal Parvazi Saeed Farzaneh Abdolreza Safari School of surveying and Geospatial engineering College of EngineeringUniversity of TehranNorth Kargar Street***TehranIran

Stochastic models play an important role in achieving high accuracy in positioning,the ideal estimator in the least-squares(LS)can be obtained only by using the suitable stochastic *** study investigates the role of variance component estimation(VCE)in the LS method for Precise Point Positioning(PPP).This estimation is performed by considering the ionospheric-free(IF)functional model for code and the phase observation of Global Positioning System(GPS).The strategy for estimating the accuracy of these observations was evaluated to check the effect of the stochastic model in four modes:a)antenna type,b)receiver type,c)the tropospheric effect,and d)the ionosphere *** results show that using empirical variance for code and phase observations in some cases caused erroneous estimation of unknown components in the PPP *** is because a constant empirical variance may not be suitable for various receivers and antennas under different *** were compared in two cases using the stochastic model of nominal weight and weight estimated by *** position error difference for the east-west,north-south,and height components was 1.5 cm,4 mm,and 1.8 cm,***,weight estimation with LS-VCE can provide more appropriate ***,the convergence time based on four elevation-dependent models was evaluated using nominal weight and LS-VCE *** to the results,the LS-VCE has a higher convergence rate than the nominal *** weight estimation using LS-VCE improves the convergence time in four elevation-dependent models by 11,13,12,and 9 min,respectively.

关键词： Stochastic model Global positioning system Variance component estimation Least-squares Precise point positioning Elevation-dependent model

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Layout graph model for semantic façade reconstruction using laser point clouds

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Geo-Spatial Information Science 2021年第3期24卷 403-421页

作者： Hongchao Fan Yuefeng Wang Jianya Gong department of Civil and Environmental engineering Norwegian University of Science and TechnologyTrondheimNorway State Key Laboratory of Information engineering in surveying Mapping and Remote SensingWuhan UniversityWuhanChina

Building façades can feature different patterns depending on the architectural style,function-ality,and size of the buildings;therefore,reconstructing these façades can be *** particular,when semantic façades are reconstructed from point cloud data,uneven point density and noise make it difficult to accurately determine the façade *** inves-tigating façade layouts,Gestalt principles can be applied to cluster visually similar floors and façade elements,allowing for a more intuitive interpretation of façade *** propose a novel model for describing façade structures,namely the layout graph model,which involves a compound graph with two structure *** the proposed model,similar façade elements such as windows are first grouped into clusters.A down-layout graph is then formed using this cluster as a node and by combining intra-and inter-cluster spacings as the ***,a top-layout graph is formed by clustering similar *** extracting relevant parameters from this model,we transform semantic façade reconstruction to an optimization strategy using simulated annealing coupled with Gibbs *** façade point cloud data with different features were selected from three datasets to verify the effectiveness of this *** experimental results show that the proposed method achieves an average accuracy of 86.35%.Owing to its flexibility,the proposed layout graph model can deal with different types of façades and qualities of point cloud data,enabling a more robust and accurate reconstruc-tion of façade models.

关键词： Building façade semantic reconstruction point cloud compound graph model stochastic process

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Assessment of GNSS zenith tropospheric delay responses to atmospheric variables derived from ERA5 data over Nigeria

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Satellite Navigation 2023年第1期4卷 167-182,I0005页

作者： Ifechukwu Ugochukwu Nzelibe Herbert Tata Timothy Oluwadare Idowu department of surveying and Geoinformatics Federal University of Technology AkureAkureNigeria

Tropospheric delay is a major error caused by atmospheric refraction in Global Navigation Satellite System(GNSS)*** study evaluates the potential of the European Centre for Medium-range Weather Forecast(ECMWF)Reanalysis 5(ERA5)atmospheric variables in estimating the Zenith Tropospheric Delay(ZTD).Linear regression models(LRM)are applied to estimate ZTD with the ERA5 atmospheric *** ZTD are also estimated using standard ZTD models based on ERA5 and Global Pressure and Temperature 3(GPT3)atmospheric *** ZTD estimates are evaluated using the data collected from the permanent GNSS continuously operating reference stations in the Nigerian *** results reveal that the Zenith Hydrostatic Delay(ZHD)from the LRM and the Saastamoinien model using ERA5 surface pressure are of identical accuracy,having a Root Mean Square(RMS)error of 2.3 mm while the GPT3-ZHD has an RMS of 3.4 *** the Zenith Wet Delay(ZWD)component,the best estimates are derived using ERA5 Precipitable Water Vapour(PWV).These include the ZWD derived by the LRM having an average RMS of 20.9 mm and Bevis equation having RMS of 21.1 mm and 21.0 mm for global and local weighted mean temperatures,*** evaluation of GPT3-ZWD estimates gives RMS of 45.8 *** study has provided a valuable insight into the application of ERA5 data for ZTD *** line with the fndings of the study,the ERA5 atmospheric variables are recommended for improving the accuracy in ZTD estimation,required for GNSS positioning.

关键词： ECMWF reanalysis 5(ERA5) Global navigation satellite systems(GNSS) Global pressure and temperature 3(GPT3) Modelling Nigeria Zenith tropospheric delay(ZTD)

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Object-based classification of hyperspectral data using Random Forest algorithm

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Geo-Spatial Information Science 2018年第2期21卷 127-138页

作者： Saeid Amini Saeid Homayouni Abdolreza Safari Ali A.Darvishsefat School of surveying and Geospatial engineering College of EngineeringUniversity of TehranTehranIran department of Geography Environment and GeomaticsUniversity of OttawaOttawaCanada Faculty of Natural Resources Department of ForestryUniversity of TehranKarajIran

This paper presents a new framework for object-based classification of high-resolution hyperspectral *** multi-step framework is based on multi-resolution segmentation(MRS)and Random Forest classifier(RFC)*** first step is to determine of weights of the input features while using the object-based approach with MRS to processing such *** the high number of input features,an automatic method is needed for estimation of this ***,we used the Variable Importance(VI),one of the outputs of the RFC,to determine the importance of each image ***,based on this parameter and other required parameters,the image is segmented into some homogenous ***,the RFC is carried out based on the characteristics of segments for converting them into meaningful *** proposed method,as well as,the conventional pixel-based RFC and Support Vector Machine(SVM)method was applied to three different hyperspectral data-sets with various spectral and spatial *** data were acquired by the HyMap,the Airborne Prism Experiment(APEX),and the Compact Airborne Spectrographic Imager(CASI)hyperspectral *** experimental results show that the proposed method is more consistent for land cover mapping in various *** overall classification accuracy(OA),obtained by the proposed method was 95.48,86.57,and 84.29%for the HyMap,the APEX,and the CASI datasets,***,this method showed better efficiency in comparison to the spectralbased classifications because the OAs of the proposed method was 5.67 and 3.75%higher than the conventional RFC and SVM classifiers,respectively.

关键词： Object-based classification Random Forest algorithm multi-resolution segmentation(MRS) hyperspectral imagery

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Evaluation of vertical crustal movements and sea level changes around Greenland from GPS and tide gauge observations

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Acta Oceanologica Sinica 2021年第1期40卷 4-12页

作者： Jiachun An Baojun Zhang Songtao Ai Zemin Wang Yu Feng Chinese Antarctic Center of surveying and Mapping Wuhan UniversityWuhan 430079China State Key Laboratory of Information engineering in surveying Mapping and Remote SensingWuhan UniversityWuhan 430079China department of Brewing engineering Moutai InstituteRenhuai 564507China

To better monitor the vertical crustal movements and sea level changes around Greenland,multiple data sources were used in this paper,including global positioning system(GPS),tide gauge,satellite gravimetry,satellite altimetry,glacial isostatic adjustment(GIA).First,the observations of more than 50 GPS stations from the international GNSS service(IGS)and Greenland network(GNET)in 2007–2018 were processed and the common mode error(CME)was eliminated with using the principal component analysis(PCA).The results show that all GPS stations show an uplift trend and the stations in southern Greenland have a higher vertical ***,by deducting the influence of GIA,the impact of current Gr IS mass changes on GPS stations was analysed,and the GIA-corrected vertical velocity of the GPS is in good agreement with the vertical velocity obtained by gravity recovery and climate experiment(GRACE).Third,the absolute sea level change around Greenland at 4 gauge stations was obtained by combining relative sea level derived from tide gauge observations and crustal uplift rates derived from GPS observations,and was validated by sea level products of satellite *** results show that although the mass loss of Gr IS can cause considerable global sea level rise,eustatic movements along the coasts of Greenland are quite complex under different mechanisms of sea level changes.

关键词： Greenland ice sheet GPS vertical crustal movement tide gauge sea level change

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Using geophysical logs to identify Milankovitch cycles and to calculate net primary productivity(NPP) of the Late Permian coals,western Guizhou,China

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Journal of Palaeogeography 2019年第1期8卷 31-42页

作者： Zhi-Ming Yan Long-Yi Shao David Large Hao Wang Baruch Spiro College of Geoscience and surveying engineering China University of Mining and Technology (Beijing) Faculty of engineering University of Nottingham department of Earth Sciences Natural History MuseumLondon

Milankovitch periodicities of 123 kyr(eccentricity), 35.6 kyr(obliquity), and 21.2 kyr(precession) were identified in geophysical logs of three Late Permian coals: 17#, 18#, and 17 + 18#, from the Songhe mining area in western Guizhou Province. Based on the astronomic temporal framework, the periods of deposition of the 17#(5.6 m), 18#(6.4 m), and 17 + 18#(5.4 m) coals were constrained to 140.8–119.8 kyr, 160–136.2 kyr, and 135–114.9 kyr,respectively. The overall depositional period of the 18# coal of 160–136.2 kyr was further subdivided using the wavelet analysis method, into short and precise periods corresponding to the Milankovitch periodicities. It includes one eccentricity periodicity(123 kyr), three obliquity periodicities(35.6 kyr), and five precession periodicities(21.2 kyr). Different thicknesses of the subdivided coal sections, equivalent to the same time span of deposition, indicate different rates of coal deposition, i.e., thicker sections imply higher rates while the thinner sections represent lower rates. The combination of the measured average carbon concentration with the density of the coals gave rise to long-term average values of carbon accumulation rates for the Late Permian coals, in the range of 42.4–50.6 g?C?m^(-2)?a^(-1). This range corresponds to the long-term average carbon accumulation rates for the initial peat in the range of 60.6–72.3 g?C?m^(-2)?a^(-1). Based on the known quantitative relation between net primary productivity(NPP)values and long-term average carbon accumulation rates for the Holocene tropical peatlands, the range of NPP values for the Late Permian tropical peatlands was estimated as 242.4–433.8 g?C?m^(-2)?a^(-1).A comparison of existing information about peatland NPP levels of various ages and latitudes indicated that when conditions of high rain and high humidity prevail in the palaeo-peatland at given latitude, the NPP rates will vary with changes in atmospheric concentration of CO_2 and O_2. This relationship may le

关键词： Milankovitch cycle Coal deposition Peatland Long-term average carbon accumulation rate Net primary productivity Late Permian Guizhou Province

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Land use structural optimization of Lilin based on GMOP-ESV

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中国有色金属学会会刊：英文版 2011年第S3期21卷 738-742页

作者： ZHANG He-bing, ZHANG Xiao-hu School of surveying & Land Information engineering, Henan Polytechnic University, Jiaozuo 454000, China School of surveying & Land Information engineering Henan Polytechnic University Jiaozuo 454000 China

Land use structural optimization is an effective approach to realize land sustainable utilization and allocate limited land resource rationally. Grey multiple objectives programming (GMOP) model based on China terrestrial ecosystem service value was constructed and applied to Lilin town. The result shows that GMOP model has more practical applicability and takes ecologic, social and comprehensive benefit into consideration. There are three programs after optimization. Program Ⅰ is comprehensive improvement and constructing ecological economy type, program Ⅱ is gross cultivated land dynamic balance type and program Ⅲ is compromise type. There are still problems in programs Ⅱ and Ⅲ, such as distribution in disorder, land left unused or abandoned. Based on the benefits above, Program Ⅰ>Program Ⅲ> Program Ⅱ. Program Ⅰ is the optimal case. Its comprehensive benefit is 8.43208×107 RMB yuan/a.

关键词： land use structure optimization grey multiple objective programming ecosystem service value Lilin town

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Water distribution extracted from mining subsidence area using Kriging interpolation algorithm

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中国有色金属学会会刊：英文版 2011年第S3期21卷 723-726页

作者： DAI Hua-yang, REN Li-yan, WANG Meng, XUE Hai-bing College of Geosicence and surveying engineering, China University of Mining & Technology, Beijing 100083, China College of Geosicence and surveying engineering China University of Mining & Technology Beijing 100083 China

By comprehensively analyzing the data of geology and mining, Kriging algorithm was introduced to analyze the thematic information of geological data, to rapidly extract mining parameters for predicting mining subsidence, and to effectively integrate geomorphology and predict information. As a result, the change information of water body is successfully detected from the prediction of surface subsidence due to mining activity. Analysis shows that the elevation of farmland in the west side of water body will be lower than ever, and the west part farmland will be submerged. However, there is no evidence for impacting the villages. All the information provides a reference for efficiently assessing environmental impact due to mining activity, which can help to govern the subsidence of the area reasonably.

关键词： Kriging interpolation water body mining subsidence prediction parameters data fusion

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Emergy analysis of ecosystem at reclamation area

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Journal of Coal Science & engineering(China) 2008年第2期14卷 299-302页

作者：陈秋计姚顽强 department of surveying engineering Xi'an University of Science and TechnologyXi'an 710054China College of Surveying and Land Information EngineeringHenan Polytechnic UniversityJiaozuo 454000China department of surveying engineering Xi'an University of Science and TechnologyXi'an 710054China

The emergy theory was used to analyze the emergy structure of the ecosystem at reclamation area in order to find the problem existed in the reclamation ecosystem through compared with the modern *** research results show that the propor- tion of assistant emergy input into the system is higher which indicate that the productivity of reclamation land has not resumed and a lot of assistant emergy needed to improve the *** ecosystem overly depend on chemical fertilizer,which is bad to agricul- tural ecosystem;the agricultural ecosystem in reclamation area belongs to traditional agriculture because the main power come from manpower and the usage of organic ferti- lizer is little,through compare the index of emergy with modern agriculture,the value of EyR and ED in reclamation area is less than the modern agriculture.

关键词： emergy ecosystem reclamation

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Effects of Bifidobacterium lactis BLa80 on fecal and mucosal flora and stem cell factor/c-kit signaling pathway in simulated microgravity rats

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World Journal of Gastroenterology 2025年第1期31卷 93-109页

作者： Ping Zhang Ying Zhu Pu Chen Tong Zhou Zhe-Yi Han Jun Xiao Jian-Feng Ma Wen Ma Peng Zang Ying Chen Graduate School Hebei North UniversityZhangjiakou 075000Hebei ProvinceChina Key Laboratory of Aerospace Nutrition and Food engineering China Astronaut Research and Training CenterBeijing 100094China department of Gastroenterology The Air Force Medical CenterBeijing 100142China department of Blood Transfusion Air Force Medical CenterBeijing 100142China

BACKGROUND Simulated microgravity environment can lead to gastrointestinal motility *** pathogenesis of gastrointestinal motility disorders is closely related to the stem cell factor(SCF)/c-kit signaling pathway associated with intestinal flora and Cajal stromal ***,intestinal flora can also affect the regulation of SCF/c-kit signaling pathway,thus affecting the expression of Cajal stromal *** cells are the pacemakers of gastrointestinal *** To investigate the effects of Bifidobacterium lactis(***)BLa80 on the intestinal flora of rats in simulated microgravity and on the gastrointestinal motility-related SCF/c-kit *** The internationally recognized tail suspension animal model was used to simulate the microgravity environment,and 30 rats were randomly divided into control group,tail suspension group and drug administration tail suspension group with 10 rats in each group for a total of 28 *** tail group was given *** BLa80 by intragastric administration,and the other two groups were given water intragastric administration,the concentration of intragastric administration was 0.1 g/mL,and each rat was 1 mL/***&eosin staining was used to observe the histopathological changes in each segment of the intestine of each group,and the expression levels of SCF,c-kit,extracellular signal-regulated kinase(ERK)and p-ERK in the gastric antrum of each group were detected by Western blotting and *** fecal flora and mucosal flora of rats in each group were detected by 16S *** Simulated microgravity resulted in severe exfoliation of villi of duodenum,jejunum and ileum in rats,marked damage,increased space between villi,loose arrangement,shortened columnar epithelium of colon,less folds,narrower mucosal thickness,reduced goblet cell number and crypts,and significant improvement after probiotic *** microgravity reduced the expressions of SCF and c-kit,and increased the express

关键词： Simulated microgravity Rat Intestinal flora Gastrointestinal motility Stem cell factor/c-kit signaling pathway

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