The Experts below are selected from a list of 204147 Experts worldwide ranked by ideXlab platform
Oleg Titov - One of the best experts on this subject based on the ideXlab platform.
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combination of Long Time Series of troposphere zenith delays observed by vlbi
Journal of Geodesy, 2007Co-Authors: R Heinkelmann, J Boehm, H Schuh, S Bolotin, G Engelhardt, D S Macmillan, Monia Negusini, E Skurikhina, V Tesmer, Oleg TitovAbstract:Within the International Very Long Baseline Interferometry (VLBI) Service for Geodesy and Astrometry (IVS), Long Time-Series of zenith wet and total troposphere delays have been combined at the level of parameter estimates. The data sets were submitted by eight IVS Analysis Centers (ACs) and cover January 1984 to December 2004. In this paper, the combination method is presented and the Time-Series submitted by the eight IVS ACs are compared with each other. The combined zenith delays are compared with Time-Series provided by the International Global Navigation Satellite System (GNSS) Service (IGS), and with zenith delays derived from the European Centre for Medium-Range Weather Forecasts (ECMWF). Before the combination, outliers are eliminated from the individual Time-Series using the robust BIBER (bounded influence by standardized residuals) estimator. For each station and AC, relative weight factors are obtained by variance component estimation. The mean bias of the IVS ACs’ Time-Series with respect to the IVS combined Time-Series is 0.89 mm and the mean root mean square is 7.67 mm. Small differences between stations and ACs can be found, which are due to the inhomogeneous analysis options, different parameterizations, and different treatment of missing in-situ pressure records. Compared to the IGS zenith total delays, the combined IVS Series show small positive mean biases and different Long-term trends. Zenith wet delays from the ECMWF are used to validate the IVS combined Series. Inconsistencies, e.g., Long-term inhomogeneity of the in-situ pressure data used for the determination of VLBI zenith delays, are identified.
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Combination of Long Time-Series of troposphere zenith delays observed by VLBI
Journal of Geodesy, 2007Co-Authors: R Heinkelmann, Harald Schuh, J Boehm, S Bolotin, G Engelhardt, Monia Negusini, E Skurikhina, V Tesmer, Daniel Macmillan, Oleg TitovAbstract:Within the International Very Long Baseline Interferometry (VLBI) Service for Geodesy and Astrometry (IVS), Long Time-Series of zenith wet and total troposphere delays have been combined at the level of parameter estimates. The data sets were submitted by eight IVS Analysis Centers (ACs) and cover January 1984 to December 2004. In this paper, the combination method is presented and the Time-Series submitted by the eight IVS ACs are compared with each other. The combined zenith delays are compared with Time-Series provided by the International Global Navigation Satellite System (GNSS) Service (IGS), and with zenith delays derived from the European Centre for Medium-Range Weather Forecasts (ECMWF). Before the combination, outliers are eliminated from the individual Time-Series using the robust BIBER (bounded influence by standardized residuals) estimator. For each station and AC, relative weight factors are obtained by variance component estimation. The mean bias of the IVS ACs’ Time-Series with respect to the IVS combined Time-Series is 0.89 mm and the mean root mean square is 7.67 mm. Small differences between stations and ACs can be found, which are due to the inhomogeneous analysis options, different parameterizations, and different treatment of missing in-situ pressure records. Compared to the IGS zenith total delays, the combined IVS Series show small positive mean biases and different Long-term trends. Zenith wet delays from the ECMWF are used to validate the IVS combined Series. Inconsistencies, e.g., Long-term inhomogeneity of the in-situ pressure data used for the determination of VLBI zenith delays, are identified.
R Heinkelmann - One of the best experts on this subject based on the ideXlab platform.
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combination of Long Time Series of troposphere zenith delays observed by vlbi
Journal of Geodesy, 2007Co-Authors: R Heinkelmann, J Boehm, H Schuh, S Bolotin, G Engelhardt, D S Macmillan, Monia Negusini, E Skurikhina, V Tesmer, Oleg TitovAbstract:Within the International Very Long Baseline Interferometry (VLBI) Service for Geodesy and Astrometry (IVS), Long Time-Series of zenith wet and total troposphere delays have been combined at the level of parameter estimates. The data sets were submitted by eight IVS Analysis Centers (ACs) and cover January 1984 to December 2004. In this paper, the combination method is presented and the Time-Series submitted by the eight IVS ACs are compared with each other. The combined zenith delays are compared with Time-Series provided by the International Global Navigation Satellite System (GNSS) Service (IGS), and with zenith delays derived from the European Centre for Medium-Range Weather Forecasts (ECMWF). Before the combination, outliers are eliminated from the individual Time-Series using the robust BIBER (bounded influence by standardized residuals) estimator. For each station and AC, relative weight factors are obtained by variance component estimation. The mean bias of the IVS ACs’ Time-Series with respect to the IVS combined Time-Series is 0.89 mm and the mean root mean square is 7.67 mm. Small differences between stations and ACs can be found, which are due to the inhomogeneous analysis options, different parameterizations, and different treatment of missing in-situ pressure records. Compared to the IGS zenith total delays, the combined IVS Series show small positive mean biases and different Long-term trends. Zenith wet delays from the ECMWF are used to validate the IVS combined Series. Inconsistencies, e.g., Long-term inhomogeneity of the in-situ pressure data used for the determination of VLBI zenith delays, are identified.
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Combination of Long Time-Series of troposphere zenith delays observed by VLBI
Journal of Geodesy, 2007Co-Authors: R Heinkelmann, Harald Schuh, J Boehm, S Bolotin, G Engelhardt, Monia Negusini, E Skurikhina, V Tesmer, Daniel Macmillan, Oleg TitovAbstract:Within the International Very Long Baseline Interferometry (VLBI) Service for Geodesy and Astrometry (IVS), Long Time-Series of zenith wet and total troposphere delays have been combined at the level of parameter estimates. The data sets were submitted by eight IVS Analysis Centers (ACs) and cover January 1984 to December 2004. In this paper, the combination method is presented and the Time-Series submitted by the eight IVS ACs are compared with each other. The combined zenith delays are compared with Time-Series provided by the International Global Navigation Satellite System (GNSS) Service (IGS), and with zenith delays derived from the European Centre for Medium-Range Weather Forecasts (ECMWF). Before the combination, outliers are eliminated from the individual Time-Series using the robust BIBER (bounded influence by standardized residuals) estimator. For each station and AC, relative weight factors are obtained by variance component estimation. The mean bias of the IVS ACs’ Time-Series with respect to the IVS combined Time-Series is 0.89 mm and the mean root mean square is 7.67 mm. Small differences between stations and ACs can be found, which are due to the inhomogeneous analysis options, different parameterizations, and different treatment of missing in-situ pressure records. Compared to the IGS zenith total delays, the combined IVS Series show small positive mean biases and different Long-term trends. Zenith wet delays from the ECMWF are used to validate the IVS combined Series. Inconsistencies, e.g., Long-term inhomogeneity of the in-situ pressure data used for the determination of VLBI zenith delays, are identified.
Wei Wang - One of the best experts on this subject based on the ideXlab platform.
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finding maximal significant linear representation between Long Time Series
International Conference on Data Mining, 2018Co-Authors: Yang Wang, Peng Wang, Jian Pei, Wei WangAbstract:In some applications on Time Series data, finding linear correlation between Time Series is important. However, it is meaningless to measure the global correlation between two Long Time Series. Moreover, more often than not, two Time Series may be correlated in various segments. To tackle the challenges in measuring linear correlation between two Long Time Series, in this paper, we formulate the novel problem of finding maximal significant linear representation. The major idea is that, given two Time Series and a quality constraint, we want to find the Longest gapped Time interval on which a Time Series can be linearly represented by the other within the quality constraint requirement. We develop a point-based approach, which exploits a novel representation of linear correlation between Time Series on segments, and transforms the problem into geometric search. We present a systematic empirical study to verify its efficiency and effectiveness.
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ICDM - Finding Maximal Significant Linear Representation between Long Time Series
2018 IEEE International Conference on Data Mining (ICDM), 2018Co-Authors: Yang Wang, Peng Wang, Jian Pei, Wei WangAbstract:In some applications on Time Series data, finding linear correlation between Time Series is important. However, it is meaningless to measure the global correlation between two Long Time Series. Moreover, more often than not, two Time Series may be correlated in various segments. To tackle the challenges in measuring linear correlation between two Long Time Series, in this paper, we formulate the novel problem of finding maximal significant linear representation. The major idea is that, given two Time Series and a quality constraint, we want to find the Longest gapped Time interval on which a Time Series can be linearly represented by the other within the quality constraint requirement. We develop a point-based approach, which exploits a novel representation of linear correlation between Time Series on segments, and transforms the problem into geometric search. We present a systematic empirical study to verify its efficiency and effectiveness.
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DASFAA (1) - A Distributed Multi-level Composite Index for KNN Processing on Long Time Series
Database Systems for Advanced Applications, 2017Co-Authors: Xiaqing Wang, Peng Wang, Zicheng Fang, Ruiyuan Zhu, Wei WangAbstract:Recently, sensor-based applications have emerged and collected plenty of Long Time Series. Traditional whole matching similarity search can only query full length Time Series. However, for Long Time Series, similarity search on arbitrary Time windows is more attractive and important. In this paper, we address the problem of window-based KNN search of Time Series data on HBase. Based on PAA approximation, we propose a composite index structure comprising Horizontal Segment Tree and Vertical Inverted Table. VI-Table is capable to prune Time Series by data summary in high levels, while HS-Tree leverages data summary in low levels to reduce access of the raw Time Series data. Both VI-Table and HS-Tree can be built parallel and incrementally. Our experiment results show the effectiveness and robustness of the proposed approach.
Monia Negusini - One of the best experts on this subject based on the ideXlab platform.
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combination of Long Time Series of troposphere zenith delays observed by vlbi
Journal of Geodesy, 2007Co-Authors: R Heinkelmann, J Boehm, H Schuh, S Bolotin, G Engelhardt, D S Macmillan, Monia Negusini, E Skurikhina, V Tesmer, Oleg TitovAbstract:Within the International Very Long Baseline Interferometry (VLBI) Service for Geodesy and Astrometry (IVS), Long Time-Series of zenith wet and total troposphere delays have been combined at the level of parameter estimates. The data sets were submitted by eight IVS Analysis Centers (ACs) and cover January 1984 to December 2004. In this paper, the combination method is presented and the Time-Series submitted by the eight IVS ACs are compared with each other. The combined zenith delays are compared with Time-Series provided by the International Global Navigation Satellite System (GNSS) Service (IGS), and with zenith delays derived from the European Centre for Medium-Range Weather Forecasts (ECMWF). Before the combination, outliers are eliminated from the individual Time-Series using the robust BIBER (bounded influence by standardized residuals) estimator. For each station and AC, relative weight factors are obtained by variance component estimation. The mean bias of the IVS ACs’ Time-Series with respect to the IVS combined Time-Series is 0.89 mm and the mean root mean square is 7.67 mm. Small differences between stations and ACs can be found, which are due to the inhomogeneous analysis options, different parameterizations, and different treatment of missing in-situ pressure records. Compared to the IGS zenith total delays, the combined IVS Series show small positive mean biases and different Long-term trends. Zenith wet delays from the ECMWF are used to validate the IVS combined Series. Inconsistencies, e.g., Long-term inhomogeneity of the in-situ pressure data used for the determination of VLBI zenith delays, are identified.
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Combination of Long Time-Series of troposphere zenith delays observed by VLBI
Journal of Geodesy, 2007Co-Authors: R Heinkelmann, Harald Schuh, J Boehm, S Bolotin, G Engelhardt, Monia Negusini, E Skurikhina, V Tesmer, Daniel Macmillan, Oleg TitovAbstract:Within the International Very Long Baseline Interferometry (VLBI) Service for Geodesy and Astrometry (IVS), Long Time-Series of zenith wet and total troposphere delays have been combined at the level of parameter estimates. The data sets were submitted by eight IVS Analysis Centers (ACs) and cover January 1984 to December 2004. In this paper, the combination method is presented and the Time-Series submitted by the eight IVS ACs are compared with each other. The combined zenith delays are compared with Time-Series provided by the International Global Navigation Satellite System (GNSS) Service (IGS), and with zenith delays derived from the European Centre for Medium-Range Weather Forecasts (ECMWF). Before the combination, outliers are eliminated from the individual Time-Series using the robust BIBER (bounded influence by standardized residuals) estimator. For each station and AC, relative weight factors are obtained by variance component estimation. The mean bias of the IVS ACs’ Time-Series with respect to the IVS combined Time-Series is 0.89 mm and the mean root mean square is 7.67 mm. Small differences between stations and ACs can be found, which are due to the inhomogeneous analysis options, different parameterizations, and different treatment of missing in-situ pressure records. Compared to the IGS zenith total delays, the combined IVS Series show small positive mean biases and different Long-term trends. Zenith wet delays from the ECMWF are used to validate the IVS combined Series. Inconsistencies, e.g., Long-term inhomogeneity of the in-situ pressure data used for the determination of VLBI zenith delays, are identified.
G Engelhardt - One of the best experts on this subject based on the ideXlab platform.
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combination of Long Time Series of troposphere zenith delays observed by vlbi
Journal of Geodesy, 2007Co-Authors: R Heinkelmann, J Boehm, H Schuh, S Bolotin, G Engelhardt, D S Macmillan, Monia Negusini, E Skurikhina, V Tesmer, Oleg TitovAbstract:Within the International Very Long Baseline Interferometry (VLBI) Service for Geodesy and Astrometry (IVS), Long Time-Series of zenith wet and total troposphere delays have been combined at the level of parameter estimates. The data sets were submitted by eight IVS Analysis Centers (ACs) and cover January 1984 to December 2004. In this paper, the combination method is presented and the Time-Series submitted by the eight IVS ACs are compared with each other. The combined zenith delays are compared with Time-Series provided by the International Global Navigation Satellite System (GNSS) Service (IGS), and with zenith delays derived from the European Centre for Medium-Range Weather Forecasts (ECMWF). Before the combination, outliers are eliminated from the individual Time-Series using the robust BIBER (bounded influence by standardized residuals) estimator. For each station and AC, relative weight factors are obtained by variance component estimation. The mean bias of the IVS ACs’ Time-Series with respect to the IVS combined Time-Series is 0.89 mm and the mean root mean square is 7.67 mm. Small differences between stations and ACs can be found, which are due to the inhomogeneous analysis options, different parameterizations, and different treatment of missing in-situ pressure records. Compared to the IGS zenith total delays, the combined IVS Series show small positive mean biases and different Long-term trends. Zenith wet delays from the ECMWF are used to validate the IVS combined Series. Inconsistencies, e.g., Long-term inhomogeneity of the in-situ pressure data used for the determination of VLBI zenith delays, are identified.
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Combination of Long Time-Series of troposphere zenith delays observed by VLBI
Journal of Geodesy, 2007Co-Authors: R Heinkelmann, Harald Schuh, J Boehm, S Bolotin, G Engelhardt, Monia Negusini, E Skurikhina, V Tesmer, Daniel Macmillan, Oleg TitovAbstract:Within the International Very Long Baseline Interferometry (VLBI) Service for Geodesy and Astrometry (IVS), Long Time-Series of zenith wet and total troposphere delays have been combined at the level of parameter estimates. The data sets were submitted by eight IVS Analysis Centers (ACs) and cover January 1984 to December 2004. In this paper, the combination method is presented and the Time-Series submitted by the eight IVS ACs are compared with each other. The combined zenith delays are compared with Time-Series provided by the International Global Navigation Satellite System (GNSS) Service (IGS), and with zenith delays derived from the European Centre for Medium-Range Weather Forecasts (ECMWF). Before the combination, outliers are eliminated from the individual Time-Series using the robust BIBER (bounded influence by standardized residuals) estimator. For each station and AC, relative weight factors are obtained by variance component estimation. The mean bias of the IVS ACs’ Time-Series with respect to the IVS combined Time-Series is 0.89 mm and the mean root mean square is 7.67 mm. Small differences between stations and ACs can be found, which are due to the inhomogeneous analysis options, different parameterizations, and different treatment of missing in-situ pressure records. Compared to the IGS zenith total delays, the combined IVS Series show small positive mean biases and different Long-term trends. Zenith wet delays from the ECMWF are used to validate the IVS combined Series. Inconsistencies, e.g., Long-term inhomogeneity of the in-situ pressure data used for the determination of VLBI zenith delays, are identified.
