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Effects of errors-in-variables on the internal and external reliability measures

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Geodesy and Geodynamics 2024年第6期15卷 568-581页

作者： yanxiong liu Yun Shi Peiliang Xu Wenxian Zeng Jingnan liu First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China School of Geomatics Xi'an University of Science and TechnologyXi'an 710048China Disaster Prevention Research Institute Kyoto UniversityUjiKyoto 611-0011Japan School of Geodesy and Geomatics Wuhan UniversityWuhan 430079China Research Center of GNSS Wuhan UniversityWuhan 430079China

The reliability theory has been an important element of the classical geodetic adjustment theory and methods in the linear Gauss-Markov model. Although errors-in-variables(EIV) models have been intensively investigated, little has been done about reliability theory for EIV models. This paper first investigates the effect of a random coefficient matrix A on the conventional geodetic reliability measures as if the coefficient matrix were deterministic. The effects of such geodetic internal and external reliability measures due to the randomness of the coefficient matrix are worked out, which are shown to depend not only on the noise level of the random elements of A but also on the values of parameters. An alternative, linear approximate reliability theory is accordingly developed for use in EIV models. Both the EIV-affected reliability measures and the corresponding linear approximate measures fully account for the random errors of both the coefficient matrix and the observations, though formulated in a slightly different way. Numerical experiments have been carried to demonstrate the effects of errors-in-variables on reliability measures and compared with the conventional Baarda's reliability measures. The simulations have confirmed our theoretical results that the EIV-reliability measures depend on both the noise level of A and the parameter values. The larger the noise level of A, the larger the EIV-affected internal and external reliability measures;the larger the parameters,the larger the EIV-affected internal and external reliability measures.

关键词： Weighted least squares Errors-in-variables model Nonlinear adjustment Total least squares Reliability theory

Trace detection of Ce^(3+) by adsorption strip voltammetry at a carbon paste electrode modified with ion imprinted polymers

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Journal of Rare Earths 2018年第10期36卷 1121-1126页

作者： Jin Chen Huiping Bai Jieren Xia Xiaolan liu yanxiong liu Qiu'e Cao Key Laboratory of Medicinal Chemistry for Nature Resource Ministry of Education School of Chemical Science and TechnologyYunnan University School of Materials Science and Engineering Yunnan University

To develop a convenient method for sensitive and selective determination of Ce3＋ in aqueous phase with complicated matrices, a carbon paste electrode（CPE） modified with ion imprinted polymers（IIPs） were fabricated. The polymers were prepared by precipitation polymerization using Ce3＋ as template, allyl phenoxyacetate（APA） as monomer, ethylene glycol dimethacrylate（EGDMA） as crosslinker and azobisisobutyronitrile（AIBN） as initiator under the molar ratio of Ce3＋, APA and EGDMA as 1：4：40, respectively. Ce3＋ was detected directly by differential pulse adsorptive stripping voltammetry（DPASV） and its oxidation peak appears at about 0.93 V. All parameters affecting the sensor＇s response are optimized and a calibration curve is plotted at a linear range of 1.0 × 10^（-6）-1.0 x 10^（-5） mol/L and 1.0×10^（-5）-2.0 × 10^（-4）mol/L with the detection limit of 1.5 × 10^（-7） mol/L. All other rare earth ions have no interference with the determination of Ce^（3＋） even at a concentration 500 times higher than that of Ce^（3＋）.This sensor was successfully applied to determination of Ce^（3＋） in two catalyst sample solutions with RSD≤3.3%（n = 5）and recoveries in the range of 99.2%-106.5% at our optimal conditions.

关键词： Cerium Electrochemical sensor Ion-imprinted polymers Carbon paste electrode Rare earths

Vibration Deformation Monitoring of Offshore Wind Turbines Based on GBIR

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Journal of Ocean University of China 2021年第3期20卷 501-511页

作者： MA Deming LI Yongsheng liu yanxiong CAI Jianwei ZHAO Rui The First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China College of Environmental Science and Engineering Ocean University of ChinaQingdao 266100China The Predecessor of the Institute of Crustal Dynamics China Earthquake AdministrationBeijing 100085China China Center for Resource Satellite Data and Applications Beijing 100094China State Nuclear Electric Power Planning Design and Research Institute Company Limited Beijing 100094China

In view of the disadvantages of vibration safety monitoring technology for offshore wind turbines,a new method is proposed to obtain deformation information of towering and dynamic targets in real-time by the ground-based interferometric ra-dar(GBIR).First,the working principle and unique advantages of the GBIR system are ***,the offshore wind turbines in Rongcheng,Shandong Province are selected as the monitoring objects for vibration safety monitoring,and the GPRI-II portable radar interferometer is used for the health diagnosis of these wind ***,the interpretation method and key processing flow of data acquisition are described in *** experiment shows that the GBIR system can accurately identify the millimeter-scale vibration deformation of offshore wind turbines and can quickly obtain overall time series deformation images of the target bodies,which demonstrate the high-precision deformation monitoring ability of the GBIR *** accuracy meets the requirements of wind turbine vibration monitoring,and the method is an effective spatial deformation monitoring means for high-rise and dynamic *** study is beneficial for the further enrichment and improvement of the technical system of wind turbine vibration safety monitoring in *** also provides data and technical support for offshore power engineering management and control,health diagnosis,and disaster prevention and mitigation.

关键词： wind turbine vibration deformation monitoring GBIR key technology technology support

Seafloor geodetic network establishment and key technologies

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Science China Earth Sciences 2020年第8期63卷 1188-1198页

作者： Yuanxi YANG yanxiong liu Dajun SUN Tianhe XU Shuqiang XUE Yunfeng HAN Anmin ZENG State Key L aboratory of Geo-Information Engineering Xi'an Research Institute of Surveying and MappingXi'an 710054China First Institute of Oceanography Ministry of Natural ResourceQingdao 266061China College of Underwater Acoustic Engineering Harbin Engineering UniversityHarbin 150001China Institute of Space Sciences Shandong UniversityWeihai 264209China Chinese Academy of Surveying and Mapping Beijing 100830China

Seafloor geodetic network construction involves the development of geodetic station shelter, network configuration design, location selection and layout, surveying strategy, observation model establishment and optimization, data processing strategy and so on. This paper tries to present main technological problems involved in the seafloor geodetic network construction, and seek the technically feasible solutions. Basic conceptions of developing seafloor geodetic station shelters for shallow sea and deep-sea are described respectively. The overall criteria of seafloor geodetic network construction for submarine navigation and those of network design for crustal motion monitoring are both proposed. In order to enhance application performances of the seafloor geodetic network, the seafloor network configuration should prefer a symmetrical network structure. The sea surface tracking line measurements for determining the seafloor geodetic station position should also adopt an approximately symmetrical configuration, and we recommend circle tracking line observations combined with cross-shaped line(or double cross-shape line) observations for the seafloor positioning mode. As to the offset correction between the Global Navigation Satellite System antenna phase center and the acoustic transducer, it is recommended to combine the calibration through external measurements and model parameter estimation. Besides, it is suggested to correct the sound speed error with a combination of observation value correction and parameterized model correction, and to mainly use the model correction to reduce the influence of acoustic ray error on the seafloor positioning. Following the proposed basic designs, experiments are performed in shallow sea area and deep-sea area respectively. Based on the developed seafloor geodetic shelter and sufficient verification in the shallow sea experiment, a long-term seafloor geodetic station in the deep-sea area of 3000 m depth was established for the

关键词： Seafloor geodesy Seafloor geodetic network Seafloor shelter Undersea navigation Acoustic positioning

REMOTE SENSING OF WATER VAPOR CONTENT USING GROUND-BASED GPS DATA

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Geo-Spatial Information Science 2000年第3期3卷 64-68页

作者： liu yanxiong Chen Yongqi liu Jingnan GPS Research Center WTUSM Wuhan China

Spatial and temporal resolution of water vapor content is useful in improving the accuracy of short_term weather *** and continuously tracking regional GPS arrays will play an important role in remote sensing atmospheric water vapor *** this study,a piecewise linear solution method was proposed to estimate the precipitable water vapor (PWV) content from ground_based GPS observations in Hong *** evaluate the solution accuracy of the water vapor content sensed by GPS,the upper air sounding data (radiosonde) that are collected locally was used to calculate the precipitable water vapor during the same ***_month results of PWV from both ground_based GPS sensing technique and radiosonde method are in agreement within 1～2 *** encouraging result will motivate the GPS meteorology application based on the establishment of a dense GPS array in Hong Kong.

关键词： GPS water vapor content precipitable water vapor

Equivalence of Network-Solution and PPP-Solution

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Geo-Spatial Information Science 2006年第2期9卷 99-102页

作者： PENG Lin liu yanxiong ZHOU Xinghua WU Yongting the First Oceanography Institute SOA 6 Xianxialing Road High-Tech District Qingdao 266061 China

The technique of precise point positioning (PPP) is gradually becoming a popular method in GPS data-processing. In GPS observation equation, the unknown parameters can be separated into two parts: global parameters and local parameters. The global parameters include orbit, satellite clock and geodynamic parameters. The local parameters are site-occupation-specific, such as position, tropospheric delay, etc. The formulas of local parameters are firstly derived under the network-solution and the PPP-solution conditions respectively. If the weight matrix of global parameters in PPP-solution is small enough, the cofactor matrices of local parameters are the same as that in network-solution. Then, 16 daily solutions are obtained in both PPP mode and network mode. Three sites are selected to compare the solutions. The experimental results demonstrated that the difference between two solutions in coordinates and tropospheric delays are only few millimeters. This level of difference can be neglected so that the solutions from both PPP mode and network mode can be taken as the same in the actual application.

关键词： network-solution precise point positioning equivalence network-solution ~ precise point positioning~ equivalence

DETERMINATION OF WEIGHTED MEAN TROPOSPHERIC TEMPERATURE USING GROUND METEOROLOGICAL MEASUREMENTS

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Geo-Spatial Information Science 2001年第1期4卷 14-18页

作者： liu yanxiong Chen Yongqi liu Jingnan GPS Center Wuhan University Wuhan China

The weighted mean tropospheric temperature is a critical parameter in the conversion of wet zenith delay to precipitable water vapor in GPS *** parameter can not be calculated from the radiosonde data in real time through the conventional *** this study,we first discuss the admissible error of weighted mean temperature to enable the accuracy of the conversion better than 1 mm,then summarize the performance of some of the existing methods. An empirical formula is established that satisfies the real_time requirement in GPS meteorology using Sequential Regression Analysis *** is shown that this real_time formula as compared with other empirical methods is more accurate for local applications.

关键词： weighted mean tropospheric temperature conversion parameter sequential regression analysis

MONITORING THE DYNAMIC CHARACTERISTICS OF TALL BUILDINGS BY GPS TECHNIQUE

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Geo-Spatial Information Science 2000年第4期3卷 61-66页

作者： Luo Zhicai Chen Yongqi liu yanxiong School of Geo-sclence and Surveying Engineering WTUSM Wuhan China

Dynamic characteristics of large structures,such as tall buildings,long_span suspension,cable_stayed bridges and tall chimneys,are key to assess their drift and stress *** dynamic characteristics of large structures are difficult to measure directly under the condition of earthquakes or strong winds using traditional techniques such as laser collimator,total station and *** there is a great need for developing new method or technique for this *** advances in Global Positioning System (GPS) technology provide a great opportunity to monitor long_period changes of structures *** receivers capable to gauge the motion at the centimeter or sub_centimeter level with sampling frequency 10Hz or even 20 Hz are now available from several *** the authors’ knowledge,the capability of identifying dynamic characteristics from GPS observations has not been widely *** the feasibility study on using kinematic GPS technology to identify the dynamic characteristics of tall buildings,some experiments were conducted in a simulative *** paper discusses in detail the experiment device,and the ways through them GPS data are recorded,processed and *** post_processing version of NovAtel’s Softsurv software and auto_regressive (AR) spectral analysis method,relative displacements and corresponding vibrating frequencies have been derived from GPS *** results indicate that the dynamic characteristics can be identified accurately by kinematic GPS technology.

关键词： kinematic GPS technology dynamic characteristics tall buildings auto_regressive spectral analysis

Recent Advances in Marine Geodesy of China

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Journal of Geodesy and Geoinformation Science 2023年第3期6卷 58-66页

作者： Shuqiang XUE Tianhe XU yanxiong liu Anmin ZENG Baogui KE Shuang ZHAO Chinese Academy of Surveying and Mapping Beijing 100036China School of Space Science and Physics Shandong Uni-versity(Weihai)Weihai 264209China The First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China Xi’an Institute of Surveying and Mapping Xi’an 710054China

The ocean accounts for approximately 71%of the total area of the *** it is studying the shape of the Earth itself through geodesy or the future development of earth system science,strengthening the construction of ocean geodesy disciplines and innovating ocean geodetic observation technologies have evident theoretical and practical *** recent years,the discipline of ocean geodesy in China has been continuously developing and growing,and notable breakthroughs have been made in ocean satellite geodesy and seafloor geodetic observation *** on ocean geodetic observation models and algorithms has also made great progress.

关键词： ocean gravity vertical datum seafloor geodesy data processing