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Wyszukujesz frazę "Ligas, Marcin" wg kryterium: Autor

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    Wyświetlanie 1-4 z 4
    Tytuł:
    A method for local approximation of a planar deformation field
    Autorzy:
    Ligas, Marcin
    Banaś, Marek
    Szafarczyk, Anna
    Powiązania:
    https://bibliotekanauki.pl/articles/106795.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Warszawska. Wydział Geodezji i Kartografii
    Tematy:
    deformation analysis
    polar decomposition
    affine transformation
    rotation matrix
    stretch tensor
    analiza deformacji
    rozkład biegunowy operatora
    transformacja afiniczna
    macierz obrotu
    Opis:
    We present a method of approximation of a deformation eld based on the local ane transformations constructed based on n nearest neighbors with respect to points of adopted grid. The local ane transformations are weighted by means of inverse distance squared between each grid point and observed points (nearest neighbors). This work uses a deformation gradient, although it is possible to use a displacement gradient instead – the two approaches are equivalent. To decompose the deformation gradient into components related to rigid motions (rotations, translations are excluded from the deformation gradient through dierentiation process) and deformations, we used a polar decomposition and decomposition into a sum of symmetric and an anti-symmetric matrices (tensors). We discuss the results from both decompositions. Calibration of a local ane transformations model (i.e., number of nearest neighbors) is performed on observed points and is carried out in a cross-validation procedure. Verication of the method was conducted on simulated data-grids subjected to known (functionally generated) deformations, hence, known in every point of a study area.
    Źródło:
    Reports on Geodesy and Geoinformatics; 2019, 108; 1-8
    2391-8365
    2391-8152
    Pojawia się w:
    Reports on Geodesy and Geoinformatics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Prediction of Earth Rotation Parameters With the Use of Rapid Products From IGS, Code and GFZ Data Centres Using ARIMA and Kriging - A Comparison
    Autorzy:
    Michalczak, Maciej
    Ligas, Marcin
    Kudrys, Jacek
    Powiązania:
    https://bibliotekanauki.pl/articles/2174952.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Centrum Badań Kosmicznych PAN
    Tematy:
    ARIMA
    kriging
    polar motion
    length of day
    earth rotation parameters
    Opis:
    Real-time prediction of Earth Orientation Parameters is necessary for many advanced geodetic and astronomical tasks including positioning and navigation on Earth and in space. Earth Rotation Parameters (ERP) are a subset of EOP, consisting of coordinates of the Earth’s pole (PMx, PMy) and UT1-UTC (or Length of Day - LOD). This paper presents the ultra-short-term (up to 15 days into the future) and short-term (up to 30 days into the future) ERP prediction using geostatistical method of ordinary kriging and autoregressive integrated moving average (ARIMA) model. This contribution uses rapid GNSS products EOP 14 12h from IGS, CODE and GFZ and also IERS final products - IERS EOP 14 C04 12h (IAU2000A). The results indicate that the accuracy of ARIMA prediction for each ERP is better for ultra-short prediction. The maximum differences between methods for first few days of 15-day predictions are around 0.32 mas (PMx), 0.23 mas (PMy) and 0.004 ms (LOD) in favour of ARIMA model. The maximum differences of Mean Absolute Prediction Errors (MAPEs) on the last few days of 30-day predictions are 1.91 mas (PMx), 0.30 mas (PMy) and 0.026 ms (LOD) with advantage to kriging method. For all ERPs the differences of MAPEs for time series from various analysis centres are not significant and vary up to maximum value of around 0.05 mas (PMx), 0.04 mas (PMy) and 0.005 ms (LOD).
    Źródło:
    Artificial Satellites. Journal of Planetary Geodesy; 2022, 57, Special Issue 1; 275--289
    2083-6104
    Pojawia się w:
    Artificial Satellites. Journal of Planetary Geodesy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Geodesy: General theory and methodology 2015–2018
    Autorzy:
    Borkowski, Andrzej
    Kosek, Wiesław
    Ligas, Marcin
    Powiązania:
    https://bibliotekanauki.pl/articles/145489.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    niezawodność
    szereg czasowy
    szacowanie
    robust estimation
    reliability
    time series
    polar motion
    least squares collocation
    Opis:
    The summary of research activities concerning general theory and methodology performed in Poland in the period of 2015–2018 is presented as a national report for the 27th IUGG (International Union of Geodesy and Geophysics) General Assembly. It contains the results of research on new or improved methods and variants of robust parameter estimation and their application, especially to control network analysis. Reliability analysis of the observation system and an integrated adjustment approach are also given. The identifiability (ID) index as a new measure for minimal detectable bias (MDB) in the observation system of a network, has been introduced. A new method of covariance function parameter estimation in the least squares collocation has been developed. The robustified version of the Shift-Msplit estimation, termed as Shift-M*split estimation, which enables estimation of parameter differences (robustly), without the need of prior estimation of the parameters, has been introduced. Results on the analysis of geodetic time series, particularly Earth orientation parameter time series, geocenter time series, permanent station coordinates and sea level variation time series are also provided in this review paper. The entire bibliography of related works is provided in the references.
    Źródło:
    Geodesy and Cartography; 2019, 68, 1; 145-162
    2080-6736
    2300-2581
    Pojawia się w:
    Geodesy and Cartography
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Development of a precise local quasigeoid model for the city of Krakow – QuasigeoidKR2019
    Autorzy:
    Banasik, Piotr
    Bujakowski, Kazimierz
    Kudrys, Jacek
    Ligas, Marcin
    Powiązania:
    https://bibliotekanauki.pl/articles/1396889.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Warszawska. Wydział Geodezji i Kartografii
    Tematy:
    local quasi geoid
    GNSS
    levelling data
    height anomaly
    QuasigeoidKR2019
    cross-validation
    Opis:
    A geoid or quasigeoid model allows the integration of satellite measurements with ground levelling measurements in valid height systems. A precise quasigeoid model has been developed for the city of Krakow. One of the goals of the model construction was to provide a more detailed quasigeoid course than the one offered by the national model PL-geoid2011. Only four measurement points in the area of Kraków were used to build a national quasigeoid model. It can be assumed that due to the small number of points and their uneven distribution over the city area, the quasigeoid can be determined less accurately. It became the reason for developing a local quasigeoid model based on a larger number of evenly distributed points. The quasigeoid model was based on 66 evenly distributed points (from 2.5 km to 5.0 km apart) in the study area. The process of modelling the quasigeoid used height anomalies determined at these points on the basis of normal heights derived through levelling and ellipsoidal heights derived through GNSS surveys. Height anomalies coming from the global geopotential model EGM2008 served as a long-wavelength trend in those derived from surveys. Analyses showed that the developed height anomaly model fits the empirical data at the level of single millimetres – mean absolute difference 0.005 m. The developed local model QuasigeoidKR2019, similar to the national model PL-geoid2011, are models closely related to the reference and height systems in Poland. Such models are used to integrate GNSS and levelling observations. A comparison of the local QuasigeoidKR2019 and national PL-geoid2011 model was made for the reference frame PL-ETRF2000 and height datum PL-KRON86-NH. The comparison of the two models with respect to GNSS/levelling height anomalies shows a triple reduction in the values of individual quartiles and a mean absolute difference for the developed local model. These summary statistics clearly indicate that the accuracy of the local model for the city of Krakow is significantly higher than that of the national one.
    Źródło:
    Reports on Geodesy and Geoinformatics; 2020, 109; 25-31
    2391-8365
    2391-8152
    Pojawia się w:
    Reports on Geodesy and Geoinformatics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-4 z 4

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