scholarly journals Construction of STHA-model of geometric geoid on the Lviv region area

2021 ◽  
Vol 42 (II) ◽  
pp. 49-56
Author(s):  
F. ZABLOTSKYI ◽  
◽  
B. DZHUMAN ◽  
Keyword(s):  
Regularization Parameter ◽  
Geometric Model ◽  
Regional Model ◽  
Practical Significance ◽  
Independent Data ◽  
Geoid Model ◽  
Static Mode ◽  
High System ◽  
Rms Error ◽  
Gnss Measurements

Nowadays there is a need to modernize the high system of Ukraine, which requires its integration in the European Vertical Reference System EVRS. In this regard there is also a need to build a regional model of the geoid on the territory of our country, which would be well consistent with the model of the European geoid EGG2015. To obtain the optimal model, it is necessary to use both gravimetric and geometric data. In this case, the model is called gravimetric-geometric. This approach is used both when building a model of the European geoid and when building geoid models on the territory of different European countries. Aim. The purpose of this work is to build a regional geometric STHA-model of the geoid on the Lviv region area and assess its accuracy. In the future it is planned to build a gravimetric STHA-model of the geoid in the same area and compare the results. Methods. To build a geometric STHA-model of the geoid on the Lviv region area, the heights of the geometric geoid, obtained from GNSS-observations at the points of SGN of I, II and III classes, were used. RMS error of determination of geodetic heights , obtained from GNSS leveling in static mode, did not exceed 15 mm. 205 values of the calculated heights of the geoid were used to build the geoid model. 8 values were not involved in the construction of the model, because they were used for an independent assessment of model accuracy. Results. The regional model of geoid within the “Remove–Compute–Restore” procedure with introduction of regularization parameter is obteined. RMS error of the obtained model, calculated on the basis of the data used in its construction, is 12 mm, and on other independent data is 25 mm. Scientific novelty and practical significance. For the first time STHA-functions were tested to build a regional geoid model. The geometric model of the geoid on the Lviv region are is calculated and the accuracy of the obtained model is estimated on the basis of dependent and independent data. The RMS error of the obtained model was about 2 cm, which corresponds to the accuracy of GNSS-measurements. The obtained model can be used as a transformation field on the Lviv region area.

scholarly journals Sea Topography of the Ionian and Adriatic Seas Using Repeated GNSS Measurements

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 812
Author(s):  
Sotiris Lycourghiotis
Keyword(s):  
Satellite System ◽  
Geoid Model ◽  
Sea Surface Topography ◽  
Mean Sea Surface ◽  
The Mean ◽  
A New Technique ◽  
Gnss Measurements ◽  
Global Navigation Satellite ◽  
Constant Slope ◽  
Ionian And Adriatic Seas

The mean sea surface topography of the Ionian and Adriatic Seas has been determined. This was based on six-months of Global Navigation Satellite System (GNSS) measurements which were performed on the Ionian Queen (a ship). The measurements were analyzed following a double-path methodology based on differential GNSS (D-GNSS) and precise point positioning (PPP) analysis. Numerical filtering techniques, multi-parametric accuracy analysis and a new technique for removing the meteorological tide factors were also used. Results were compared with the EGM96 geoid model. The calculated differences ranged between 0 and 48 cm. The error of the results was estimated to fall within 3.31 cm. The 3D image of the marine topography in the region shows a nearly constant slope of 4 cm/km in the N–S direction. Thus, the effectiveness of the approach “repeated GNSS measurements on the same route of a ship” developed in the context of “GNSS methods on floating means” has been demonstrated. The application of this approach using systematic multi-track recordings on conventional liner ships is very promising, as it may open possibilities for widespread use of the methodology across the world.

scholarly journals Extraction of geoid heights from shipborne GNSS measurements along the Weser River in northern Germany

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
D. Lavrov ◽  
G. Even-Tzur ◽  
J. Reinking
Keyword(s):  
Measurement Data ◽  
Geoid Height ◽  
Theoretical Background ◽  
Geoid Model ◽  
Measuring Techniques ◽  
Systematic Effects ◽  
Gnss Measurements ◽  
Accuracy Assessments

AbstractIn-land geoid models rely on several measuring techniques. The quality of those models is directly related to the spatial resolution of the measurement data. Occasionally, a local geoid model does not cover the coastal area at all and a local marine geoid simply does not exist. ShipborneGNSS measurementsmay provide away of overcoming this problem in coastal areas. However, several corrections to the raw measurements must be applied in order to account for systematic effects induced by ship dynamics and other static and dynamic impacts from tides, atmospheric pressure or wind stress. This paper presents the theoretical background for the method and the results of a case study in the estuary of the Weser River in Germany. A series of GNSS measurements were carried out aboard a ship and the approximate geoid height along the river was derived. For accuracy assessments of this method, the resultswere compared to the German Combined QuasiGeoid 2011 (GCG2011). The results are very promising and indicate the ability to extract geoid heights from shipborne GNSS measurements.

scholarly journals Development of the One Centimeter Accuracy Geoid Model of Latvia for GNSS Measurements

2015 ◽  
Vol 96 ◽  
pp. 012037
Author(s):  
J Balodis ◽  
G Silabriedis ◽  
D Haritonova ◽  
M Kaļinka ◽  
I Janpaule ◽  
...  
Keyword(s):  
Geoid Model ◽  
Gnss Measurements ◽  
The One

Expansion and Improvement of the Israeli Geoid Model by Shipborne GNSS Measurements

2017 ◽  
Vol 143 (2) ◽  
pp. 04016022 ◽  
Author(s):  
Dany Lavrov ◽  
Gilad Even-Tzur ◽  
Jörg Reinking
Keyword(s):  
Geoid Model ◽  
Gnss Measurements

scholarly journals Investigation of the operation of a ship’s synchronous generator based on a numerical model

2021 ◽  
Vol 2061 (1) ◽  
pp. 012004
Author(s):  
AV Grinek ◽  
IP Boychuk ◽  
A M Fishenko ◽  
NV Savosteenko ◽  
O N Gerasimenko
Keyword(s):  
Numerical Model ◽  
Geometric Model ◽  
Harmonic Component ◽  
Low Frequency ◽  
Synchronous Generator ◽  
Diagnostic Model ◽  
Electrical Machine ◽  
Static Mode ◽  
Design Calculations ◽  
Mechanical Defect

Abstract The article presents the results of modeling a ship’s synchronous generator. Based on preliminary design calculations, a geometric model of the generator was built. The static and overclocking processes of the generator are investigated. For static modes, the frequency response of the process is obtained. A numerical model was used to identify a mechanical defect. On the example of a simulated defect of an electrical machine - the eccentricity of the generator rotor, the signature of the defect signal is obtained. The study revealed that the presence of rotor eccentricity leads to the appearance of a harmonic component in the spectrum of the force of large amplitude with a maximum value at a low frequency. Transient analysis was carried out using wavelet transformations. The results of the study of dynamics show how the rotor speed increases. The simulation revealed three frequency regions of the signal under study: the region of the increase in speed, the achievement of the critical speed (between the second and third seconds), and the exit to the steady-state. A diagram of a system for diagnosing defects in an electrical machine using a digital twin - a numerical model is proposed. Generator defects (mechanical and electromechanical) can be identified based on model data. Databases of defect signatures in a static mode and a diagnostic model, which contains algorithms for deciding on the presence of a defect, can serve as the basis of information for an operator to decide.

scholarly journals Analysis of erypsoidal heights errors based on GNSS-leveling results

2021 ◽  
Vol 41 (I) ◽  
pp. 37-45
Author(s):  
A. FEDORCHUK ◽  
Keyword(s):  
Real Time ◽  
Statistical Characteristics ◽  
Practical Significance ◽  
Static Mode ◽  
Real Time Mode ◽  
First Case ◽  
Urgent Task ◽  
Measurement Results ◽  
National University ◽  
The Impact

Research the influence of errors on the measurement results is always an urgent task. Analysis of such values makes it possible to assess the nature of the change and the magnitude of the impact of errors for their further consideration or compensation, or minimization. In this paper, the errors in determining ellipsoidal heights from GNSS observations are considered. In determining the ellipsoidal heights, this method can achieve an accuracy of 1–2 cm in static mode (Static) and 2–4 cm in real time mode (RTK). Thus, the accuracy of the chosen mode of observations will indicate the initial limits of the ellipsoidal heights errors influence, and the factors that arise directly during observations and data processing will determine the extent to which these errors will change relative to the initial limits. The purpose of this work is to analyze the errors of ellipsoidal heights based on the results of GNSS-leveling obtained in the static and RTK modes. Method. The study used GNSS-leveling data at 17 points (wall and soil benchmarks) of leveling lines of I–II classes, which are located within a radius of 15 km from the permanent station SULP of the Lviv Polytechnic National University. Observations were performed in static mode (4-hour) and RTK (8–10 measurements). Points are divided into three categories (5–6 points): 1) statics on wall benchmarks; 2) real-time mode on wall benchmarks; 3) static mode on soil benchmarks. By combining methods and categories, four GNSS networks were formed, including 11, 11, 12 and 17 points. Results. For each category, the percentages within which the errors of ellipsoidal heights change in static observation mode and real-time mode using the GNSS leveling method are presented. On the basis of the received information it is established that for the first case errors of ellipsoidal heights on the average change within ± 43 %, for the second ± 36 %, and for the third ± 14 %. The analysis of statistical characteristics for each category shows that the standard deviation of the static mode data is 2 % and 19 %, and the RTK mode – 12 %, respectively. Scientific novelty and practical significance. The nature of the change in the error limits of the ellipsoidal heights determination gives an idea of what accuracy should be expected when performing GNSS-leveling depending on the mode of observation. Such data play an important role in solving scientific and applied problems by GNSS leveling, such as the constructions of new leveling networks or monitoring the height points of existing networks.

scholarly journals Method for the fuzzy control system synthesis for the analytical approximation characteristics of the typical nonlinear elements characteristics

2020 ◽  
Vol 224 ◽  
pp. 01013
Author(s):  
V Lubentsov ◽  
E Shakhrai ◽  
E Lubentsova
Keyword(s):  
Control System ◽  
Fuzzy Controller ◽  
Piecewise Linear ◽  
Continuous Functions ◽  
Analytical Approximation ◽  
Practical Significance ◽  
Piecewise Linear Approximation ◽  
Static Mode ◽  
System Synthesis ◽  
Control System Synthesis

The solution of the problem concerning the control system synthesis with a fuzzy controller on the basis of typical nonlinear analytical approximation characteristics with continuous differentiable functions like sigmoid type has been considered. A method of synthesis which is based on the fact that the rulebase and membership function are formed by the way of comparing the control or corrective impacts of the fuzzy controller (prototype) or a controller with approximating control (CAC) has been suggested for problem solving. For the CAC construction the closest coincidence of graphically installed controllers’ impacts are taken. This makes it possible to exclude subjective errors connecting with a possible non-representative ruleset for the rulebase forming. The result of the work is to obtain a new class of controllers based on the approximating continuous functions, which are simpler for constructing multi-mode control systems. The practical significance lies in the fact, that the tuning of the fuzzy controller based on the analytical continuous approximation of the typical nonlinear elements’ characteristics comes down to two basic parameters: the coefficient that determines the curvature (slope) of the characteristic in the transit mode and the parameter that determines the control impact value in the static mode. The advantage of this smooth characteristic in relation to the piecewise linear approximation is that there is no need to determine the moments (points) of switching nonlinear characteristics during the system operation.

scholarly journals On the accuracy of (quasi) geoid models relatively UELN/EVRS2000 height systems

2021 ◽  
Vol 41 (I) ◽  
pp. 29-36
Author(s):  
F. ZABLOTSKYY ◽  
◽  
B. DZHUMAN ◽  
I. BRUSAK ◽  
◽  
...  
Keyword(s):  
Gravitational Field ◽  
High Precision ◽  
Zero Point ◽  
Border Region ◽  
Geoid Model ◽  
Static Mode ◽  
Earth’S Gravitational Field ◽  
Starting Point ◽  
Height System ◽  
The Baltic

Nowadays the Baltic Height System 1977 operates in Ukraine, the starting point of which is the zero of the Kronstadt banchmark. However, the current height system in Ukraine is morally obsolete primarily due to the great distance from the zero-point of height (about 2 thousand km) and the difficulty of adapting to the use of satellite surveying methods. Therefore, today it does not correspond to the level of development of modern geospatial technologies and it needs to be modernized. The most optimal way to modernize the height network of Ukraine is its integration into the United European Leveling Network UELN, the zero point of which is the Amsterdam banchmark. Within the framework of such integration it is necessary to create a high-precision geoid model for the territory of Ukraine, connected to the UELN/EVRS2000 height system. Aim. The purpose of the work is to compare the accuracy of different geoid/quasigeoid models and the global gravitational field of the Earth on the Western Ukraine area (border region) relative to the heights of points in the height system UELN/EVRS2000, where GNSSleveling is performed, and to determine the most optimal model in relation to which a high-precision geoid model can be created, consistent with the UELN/EVRS2000 height system.Method. To obtain the heights of leveling points on the Ukraine area in the UELN/EVRS2000 height system we performed I class leveling on two lines from the fundamental benchmarks on the territory of Ukraine (heights are known in the Baltic height system 1977) to I class benchmarks on the Poland area (UELN/EVRS2000 height system). GNSS-leveling in static mode (1-second sampling observations for more than 6 hours) was performed on all fundamental and ground benchmarks, as well as horizontal marks. Results. The heights of the quasigeoid at 26 points are obtained from the performed measurements. The heights are compared with three global models of the Earth’s gravitational field: EGM2008, EIGEN-6C4 and XGM2019e_2159 (the maximum order of all these models is 2190), as well as with the European geoid EGG2015. It is established that the best accuracy (≈ 7 cm) allows to obtain the European geoid EGG2015. Scientific novelty and practical significance. For the first time the accuracy of the Earth’s gravitational field models and geoid models on the Ukraine area is investigated at points where the height in the UELN/EVRS2000 height system is known. We established that when constructing a high-precision quasigeoid using the “Remove–Restore” procedure, it is best to use the European geoid EGG2015 as a systematic component.

scholarly journals HIGH-PRECISION SATELLITE LEVELING AND INVESTIGATION OF THE LOCAL GEOID MODEL IN THE TERRITORY OF KASHKADARYA REGION

2020 ◽  
pp. 31-35
Author(s):  
Fazilova D.Sh ◽  
Magdiev H.N ◽  
Halimov B.T
Keyword(s):  
High Precision ◽  
Reference System ◽  
Reference Data ◽  
Height Anomaly ◽  
Geopotential Model ◽  
Geoid Model ◽  
Geopotential Models ◽  
Normal Heights ◽  
Gnss Measurements ◽  
Local Geoid

In this paper, a study of the accuracy of obtaining normal heights using Global Geopotential Models EGM2008, EIGEN-6C4, GECO and GNSS measurements for the territory of the Kashkadarya region in Uzbekistan is carried out. The heights obtained by the classical leveling in Baltic reference system were used as reference data. EIGEN-6C4 and GECO models were recommended for definition a preliminary quasi  geoid model of the region. KEYWORDS: GNSS and classical leveling, Global Geopotential Model, height anomaly

scholarly journals GEODESY, CARTOGRAPHY AND AERIAL PHOTOGRAPHY

2021 ◽  
Vol 94, 2021 (94) ◽  
pp. 5-12
Author(s):  
Petro Dvulit ◽  
◽  
Stepan Savchuk ◽  
Iryna Sosonka ◽  
◽  
...  
Keyword(s):  
Time Series ◽  
High Precision ◽  
Systematic Errors ◽  
Seasonal Effects ◽  
Practical Significance ◽  
Distribution Law ◽  
Empirical Distributions ◽  
Theory Of Measurements ◽  
Gnss Measurements ◽  
Subjective Estimates

The aim of the research is to diagnose the metrological characteristics of high-precision GNSS-observations by methods of non-classical error theory of measurements (NETM) based on Ukrainian reference stations. Methodology. We selected 72 GNSS reference stations, downloaded daily observation files from the LPI analysis center server, and created time series in the topocentric coordinate system. The duration of the time series is almost two years (March 24, 2019 - January 2, 2021). Using a specialized software package, the time series have been cleaned of offsets and breaks, seasonal effects, and the trend component has been removed. Verification of empirical distributions of errors was provided by the procedure of NETM on the recommendations offered by G. Jeffries and on the principles of hypothesis tests the theory according to Pearson's criterion. The main result of the research. It is established that the obtained time series of coordinates of reference GNSS stations do not confirm the hypothesis of their conformity to the normal Gaussian distribution law. NETM diagnostics of the accuracy of high-precision GNSS measurements, which is based on the use of confidence intervals for assessing the asymmetry and kurtosis of a significant sample, followed by the Pearson test, confirms the presence of weak, not removed from GNSS-processing, sources of systematic errors. Scientific novelty. The authors use the possibility of NETM to improve the processing of high-precision GNSS measurements and the need to take into account the sources of systematic errors. Failure to take into account certain factors creates the effect of shifting the time coordinate series, which, in turn, leads to subjective estimates of station velocity, i.e. their geodynamic interpretation. Practical significance. Research of the reasons for deviations of errors distribution from the established norms provides metrological literacy of carrying out high-precision GNSS measurements of large samples.

Sign in / Sign up

Export Citation Format

Share Document