scholarly journals Formation Design for Single-Pass GEO InSAR Considering Earth Rotation Based on Coordinate Rotational Transformation

2020 ◽  
Vol 12 (3) ◽  
pp. 573
Author(s):  
Zhiyang Chen ◽  
Xichao Dong ◽  
Yuanhao Li ◽  
Cheng Hu
Keyword(s):  
Coordinate System ◽  
Earth Rotation ◽  
Design Method ◽  
Observation Time ◽  
Single Pass ◽  
The Earth ◽  
Simulation Results ◽  
Elevation Model ◽  
Rotational Transformation ◽  
Formation Design

The single-pass geosynchronous synthetic aperture radar interferometry (GEO InSAR) adopts the formation of a slave satellite accompanying the master satellite, which can reduce the temporal decorrelation caused by atmospheric disturbance and observation time gap between repeated tracks. Current formation design methods for spaceborne SAR are based on the Relative Motion Equation (RME) in the Earth-Centered-Inertial (ECI) coordinate system (referred to as ECI-RME). Since the Earth rotation is not taken into account, the methods will lead to a significant error for the baseline calculation while applied to formation design for GEO InSAR. In this paper, a formation design method for single-pass GEO InSAR based on Coordinate Rotational Transformation (CRT) is proposed. Through CRT, the RME in Earth-Centered-Earth-Fixed (ECEF) coordinate system (referred to as ECEF-RME) is derived. The ECEF-RME can be used to describe the accurate baseline of close-flying satellites for different orbital altitudes, but not limited to geosynchronous orbit. Aiming at the problem that ECEF-RME does not have a regular geometry as ECI-RME does, a numerical formation design method based on the minimum baseline error criterion is proposed. Then, an analytical formation design method is proposed for GEO InSAR, based on the Minimum Along-track Baseline Criterion (MABC) subject to a fixed root mean square of the perpendicular baseline. Simulation results verify the validity of the ECEF-RME and the analytical formation design method. The simulation results also show that the proposed method can help alleviate the atmospheric phase impacts and improve the retrieval accuracy of the digital elevation model (DEM) compared with the ECI-RME-based approach.

The Terrestrial Coordinate System and International Earth-rotation Services

1985 ◽  
Vol 38 (02) ◽  
pp. 216-217
Author(s):  
G. A. Wilkins
Keyword(s):  
Coordinate System ◽  
Earth Rotation ◽  
Reference System ◽  
New Techniques ◽  
Crustal Movements ◽  
Earth Observations ◽  
The Earth ◽  
External Reference ◽  
External Objects ◽  
Rotation Of The Earth

New techniques of measurement make it possible in 1984 to determine positions on the surface of the Earth to a much higher precision than was possible in 1884. If we look beyond the requirements of navigation we can see useful applications of global geodetic positioning to centimetric accuracy for such purposes as the control of mapping and the study of crustal movements. These new techniques depend upon observations of external objects, such as satellites or quasars rather than stars, and they require that the positions of these objects and the orientation of the surface of the Earth are both known with respect to an appropriate external reference system that is ‘fixed’ in space. We need networks of observing stations and analysis centres that monitor the motions of the external objects and the rotation of the Earth. Observations of stars by a transit circle are no longer adequate for this purpose.

scholarly journals Procedure for VLBI Estimates of Earth Rotation Parameters Referred to the Nonrotating Origin

1991 ◽  
Vol 127 ◽  
pp. 77-84 ◽  
Author(s):  
N. Capitaine ◽  
A.M. Gontier
Keyword(s):  
Earth Rotation ◽  
Partial Derivatives ◽  
The Earth ◽  
Earth Rotation Parameters ◽  
Vlbi Data ◽  
Rotation Parameters ◽  
Derivatives Of ◽  
Rotational Transformation

AbstractThis paper investigates the practical use of the nonrotating origin (NRO) (Guinot 1979) for estimating the Earth Rotation Parameters from VLBI data, which is based on the rotational transformation between the geocentric celestial and terrestrial frames as previously derived by Capitaine (1990). Numerical checks of consistency show that the transformation referred to the NRO is equivalent to the classical one referred to the equinox and considering the complete “equation of the equinoxes” (Aoki & Kinoshita 1983). The paper contains the expressions for the partial derivatives of the VLBI geometric delay to be used for the adjustment of the pole coordinates, UT1 and deficiencies in the two celestial coordinates of the Celestial Ephemeris Pole (CEP) in the multiparameters fits to VLBI data. The use of the NRO is shown to simplify the estimates of these parameters and to free the estimated UT1 parameter from the model for precession and nutation.

scholarly journals The Observations of the Earth Rotation and the Stellar System

1986 ◽  
Vol 109 ◽  
pp. 133-141
Author(s):  
Koichi Sato ◽  
Koichi Yokoyama ◽  
Kiyotaka Tanikawa ◽  
Yukio Goto
Keyword(s):  
Coordinate System ◽  
Earth Rotation ◽  
Stellar System ◽  
Proper Motions ◽  
Earth Orientation Parameters ◽  
Reference Coordinate System ◽  
Earth Orientation ◽  
The Earth ◽  
Orientation Parameters ◽  
Fundamental Reference

The fundamental reference of the Earth rotation observation by the method of optical astrometry, such as VZT, PZT, astrolabe, transit instrument and so on, relies upon the stellar system. Hence the stellar positions and proper motions, and the celestial reference coordinate system are essential to preserve the system of the Earth orientation parameters determined by the optical astrometry.

Reference Coordinate System Requirements for Geophysics

1975 ◽  
Vol 26 ◽  
pp. 87-92
Author(s):  
P. L. Bender
Keyword(s):  
Coordinate System ◽  
Polar Motion ◽  
Main Part ◽  
Measurement Techniques ◽  
Reference Points ◽  
Angular Motion ◽  
Coordinate Systems ◽  
Axis Of Rotation ◽  
The Earth ◽  
Fixed System

AbstractFive important geodynamical quantities which are closely linked are: 1) motions of points on the Earth’s surface; 2)polar motion; 3) changes in UT1-UTC; 4) nutation; and 5) motion of the geocenter. For each of these we expect to achieve measurements in the near future which have an accuracy of 1 to 3 cm or 0.3 to 1 milliarcsec.From a metrological point of view, one can say simply: “Measure each quantity against whichever coordinate system you can make the most accurate measurements with respect to”. I believe that this statement should serve as a guiding principle for the recommendations of the colloquium. However, it also is important that the coordinate systems help to provide a clear separation between the different phenomena of interest, and correspond closely to the conceptual definitions in terms of which geophysicists think about the phenomena.In any discussion of angular motion in space, both a “body-fixed” system and a “space-fixed” system are used. Some relevant types of coordinate systems, reference directions, or reference points which have been considered are: 1) celestial systems based on optical star catalogs, distant galaxies, radio source catalogs, or the Moon and inner planets; 2) the Earth’s axis of rotation, which defines a line through the Earth as well as a celestial reference direction; 3) the geocenter; and 4) “quasi-Earth-fixed” coordinate systems.When a geophysicists discusses UT1 and polar motion, he usually is thinking of the angular motion of the main part of the mantle with respect to an inertial frame and to the direction of the spin axis. Since the velocities of relative motion in most of the mantle are expectd to be extremely small, even if “substantial” deep convection is occurring, the conceptual “quasi-Earth-fixed” reference frame seems well defined. Methods for realizing a close approximation to this frame fortunately exist. Hopefully, this colloquium will recommend procedures for establishing and maintaining such a system for use in geodynamics. Motion of points on the Earth’s surface and of the geocenter can be measured against such a system with the full accuracy of the new techniques.The situation with respect to celestial reference frames is different. The various measurement techniques give changes in the orientation of the Earth, relative to different systems, so that we would like to know the relative motions of the systems in order to compare the results. However, there does not appear to be a need for defining any new system. Subjective figures of merit for the various system dependon both the accuracy with which measurements can be made against them and the degree to which they can be related to inertial systems.The main coordinate system requirement related to the 5 geodynamic quantities discussed in this talk is thus for the establishment and maintenance of a “quasi-Earth-fixed” coordinate system which closely approximates the motion of the main part of the mantle. Changes in the orientation of this system with respect to the various celestial systems can be determined by both the new and the conventional techniques, provided that some knowledge of changes in the local vertical is available. Changes in the axis of rotation and in the geocenter with respect to this system also can be obtained, as well as measurements of nutation.

scholarly journals The effect of earthquakes on the ERP during 1977–1985

1988 ◽  
Vol 128 ◽  
pp. 399-404 ◽  
Author(s):  
Richard S. Gross
Keyword(s):  
Earth Rotation ◽  
The Earth ◽  
Time Period ◽  
Earth Rotation Parameters ◽  
Rotation Parameters ◽  
Large Earthquakes

The effect on the Earth Rotation Parameters (ERP) of all the large earthquakes that occurred during 1977–1985 is evaluated. It is found that they cannot have caused the variations observed in the ERP during this time period.

Intelligent Information of TS Fuzzy PID Control System of BLDCM

2013 ◽  
Vol 846-847 ◽  
pp. 313-316 ◽  
Author(s):  
Xiao Yun Zhang
Keyword(s):  
Control System ◽  
Dynamic Model ◽  
Pid Control ◽  
Control Method ◽  
Design Method ◽  
Fuzzy Pid ◽  
Fuzzy Pid Control ◽  
Control Precision ◽  
Simulation Results ◽  
Intelligent Information

This paper presented a new method based on the Fuzzy self - adaptive PID for BLDCM. This method overcomes some defects of the traditional PID control. Such as lower control precision and worse anti - jamming performance. It dynamic model of BLDCM was built, and then design method for TS fuzzy PID model is given, At last, it compared simulation results of PID control method with TS Fuzzy PID control method. The results show that the TS Fuzzy PID control method has more excellent dynamic antistatic performances, as well as anti-jamming performance. The experiment shows that TS fuzzy PID control has the stronger adaptability robustness and transplant.

A Design Method of LS-SVM Based Stable Adaptive Controller for a Class of Nonlinear Systems

2011 ◽  
Vol 48-49 ◽  
pp. 17-20
Author(s):  
Chun Li Xie ◽  
Tao Zhang ◽  
Dan Dan Zhao ◽  
Cheng Shao
Keyword(s):  
Nonlinear Systems ◽  
Design Method ◽  
Nonlinear Function ◽  
Lyapunov Stability Theory ◽  
Adaptive Controller ◽  
Control Law ◽  
Continuous Systems ◽  
Control Schemes ◽  
Closed Systems ◽  
Simulation Results

A design method of LS-SVM based stable adaptive controller is proposed for a class of nonlinear continuous systems with unknown nonlinear function in this paper. Due to the fact that the control law is derived based on the Lyapunov stability theory, the scheme can not only solve the tracking problem of this class of nonlinear systems, but also it can guarantee the asymptotic stability of the closed systems, which is superior to many LS-SVM based control schemes. The effectiveness of the proposed scheme is demonstrated by simulation results.

An Inverter can be Used in Hybrid Wind-Solar Grid-Connected Power System

2012 ◽  
Vol 512-515 ◽  
pp. 70-73 ◽  
Author(s):  
Yang Tian ◽  
Ru Cheng Han ◽  
Chen Li
Keyword(s):  
Global Warming ◽  
Power System ◽  
Sustainable Energy ◽  
Future Generations ◽  
Energy Sources ◽  
Grid Security ◽  
Operational Analysis ◽  
Harmonic Content ◽  
The Earth ◽  
Simulation Results

With increasing concern of global warming, many are looking at sustainable energy solutions to protect the earth for the future generations.. This paper presents a new inverter which can be used in hybrid wind/photovoltaic grid-connected power system. This inverter allows the two sources to work separately or simultaneously depending on the availability of the energy sources. Harmonic content is detrimental for the Grid security. The introduction of the inverter can effectively reduce the harmonics generated by the system. Operational analysis of the proposed system will be discussed in this paper. Simulation results are given to highlight the merits of the proposed inverter.

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