Search Results

1 - 7 of 7 items

  • Keyword: reference frame x
Clear All Modify Search
The problem of temporal validity of reference coordinates in the context of reliability of the ETRS89 system realization in Poland

ABSTRACT

The IAG (International Association of Geodesy) Sub-Commission for the European reference frame (EUREF) passed a resolution recommending application of the ETRF2000 frame as national realizations of the ETRS89 reference system during the XXth EUREF Symposium in Gävle (Sweden) in 2010. The PL-ETRF2000 system is comprised of EPN (EUREF Permanent Network) sites. Their coordinates and their temporal changes (velocities) were accurately determined on the basis of long-term GNSS observations. The transfer of the PLETRF2000 system onto the territory of Poland is realized by the ASG-EUPOS (Active Geodetic Network – European Position Determination System) permanent sites network. The ASG-EUPOS tasks include also system maintenance by continuous or periodical control of the coordinates and velocities constancy.

According to the current Regulation of the Ministry of Administration and Digitization concerning geodesic, gravimetric and magnetic warps, the accuracy of sites of the fundamental warp (EPN sites belonging to ASG-EUPOS) may not be worse than 0.01 m for horizontal position and 0.02 m for geodesic height. It results in the necessity to monitor the performance of the reference sites for proper maintenance of the reference system.

A new team for modeling deformations in Europe was established within the EUREF Working Group (The EUREF Working Group on Deformation Models) during the EUREF 2012 Symposium in Paris. One of its tasks is taking geo-kinematic models into consideration for national realizations of the ETRS89 and maximum usage of knowledge concerning the velocity field.

The paper deals with the problem of temporal validity of the catalogue coordinates and the necessity of periodical updating them on the basis of velocities derived from long-term observations. Although Poland is located in a tectonically calm area and the intraplate velocities are small, some of the EPN and ASG-EUPOS sites have significant velocities and are subject to vertical movements. Lack of periodical updating of the coordinates realizing the reference system will cause lack of fulfillment of the assumed accuracy criterion.

Analysis of horizontal and vertical velocities of sites belonging to the fundamental warp lead to assumption that two sites will exceed horizontal criterion in a period of time shorter than 10 years counting from the reference epoch (i.e. from 2011.0): KATO horizontal coordinates should be updated in 2014 and GWWL in 2021. Mores sites will exceed vertical criterion: BOGI (2021), GWWL (2015), KATO (2019), SWKI (2019) and ZYWI (2021). The vertical component updating will require of course changes of the horizontal component (coordinates are determined in the Cartesian orthogonal XYZ coordinate system and then recalculated for the ellipsoidal coordinates). Besides periodical coordinates updating it is recommended to conduct repeated processing for the entire network according to the EUREF standards for taking the current GNSS observations into consideration.

Open access
Sloppy, But Acceptable, Control of Biological Movement: Algorithm-Based Stabilization of Subspaces in Abundant Spaces

Abstract

In this paper, we develop an algorithm-based approach to the problem of stability of salient performance variables during motor actions. This problem is reformulated as stabilizing subspaces within high-dimensional spaces of elemental variables. Our main idea is that the central nervous system does not solve such problems precisely, but uses simple rules that achieve success with sufficiently high probability. Such rules can be applied even if the central nervous system has no knowledge of the mapping between small changes in elemental variables and changes in performance. We start with a rule ”Act on the most nimble” (the AMN-rule), when changes in the local feedback-based loops occur for the most unstable variable first. This rule is implemented in a task-specific coordinate system that facilitates local control. Further, we develop and supplement the AMN-rule to improve the success rate. Predictions of implementation of such algorithms are compared with the results of experiments performed on the human hand with both visual and mechanical perturbations. We conclude that physical, including neural, processes associated with everyday motor actions can be adequately represented with a set of simple algorithms leading to sloppy, but satisfactory, solutions. Finally, we discuss implications of this scheme for motor learning and motor disorders.

Open access
The Problem of Compatibility and Interoperability of Satellite Navigation Systems in Computation of User's Position

The Problem of Compatibility and Interoperability of Satellite Navigation Systems in Computation of User's Position

Actually (June 2011) more than 60 operational GPS and GLONASS (Satellite Navigation Systems - SNS), EGNOS, MSAS and WAAS (Satellite Based Augmentation Systems - SBAS) satellites are in orbits transmitting a variety of signals on multiple frequencies. All these satellite signals and different services designed for the users must be compatible and open signals and services should also be interoperable to the maximum extent possible. Interoperability definition addresses signal, system time and geodetic reference frame considerations. The part of compatibility and interoperability of all these systems and additionally several systems under construction as Compass, Galileo, GAGAN, SDCM or QZSS in computation user's position is presented in this paper. Three parameters - signal in space, system time and coordinate reference frame were taken into account in particular.

Open access
Exploring and Promoting Ecological Consciousness in Teacher Education: the Possibilities of Educational Action Research in Education for Sustainable Development

Exploring and Promoting Ecological Consciousness in Teacher Education: the Possibilities of Educational Action Research in Education for Sustainable Development

The paper reports on the findings of a qualitative study with 39 first year students of pre-school and primary school teacher education programmes who are taking an educational action research based study course "Environmental Pedagogy". The study aimed at engaging the students in reflection on their experiences of interaction with nature and uncovering their views on ecological consciousness. Qualitative content analysis sought emergent themes in students' reflections. A conceptual framework was identified containing three frames of reference: (1) inclusion-oriented frame of reference; (2) exclusion-determining frame of reference and (3) solution-oriented frame of reference. Conclusions were drawn about the possibilities of educational action research to encourage students' reflection on ecological consciousness and building sustainable and inclusive relationships with the world.

Open access
Awakening Pre-service Teachers to Children’s Social Exclusion in the Classroom

Abstract

Children’s social exclusion in the classroom is a threat to the sustainability of education. Teachers should be sensitised to this issue, which raises important implications for teacher education. This paper reports on an action research study in the context of pre-service teacher education aimed at enriching prospective early childhood educators’ perspectives on children’s social exclusion in the classroom and heightening their awareness of themselves as key figures in reducing it. A teacher capable of dealing with children’s social exclusion was the focus of investigation. The students engaged in envisioning through negotiation of meaning in written critical discourse with peers in an e-learning environment (google.docs spreadsheet). Qualitative content analysis of students’ writings suggests viewing pre-service teachers’ professional development towards readiness to address children’s social exclusion in the classroom as movement along a continuum. The study also implies that the performed action research was transformative in that it contributed to a heightened awareness of children’s social exclusion in the classroom among prospective early childhood educators and their awakened commitment to become teachers capable of addressing this problem.

Open access
New High-Precision Values of the Geodetic Rotation of the Major Planets, Pluto, the Moon and the Sun

Abstract

This investigation is continuation of our studies of the geodetic (relativistic) rotation of the Solar system bodies (Eroshkin and Pashkevich, 2007) and (Eroshkin and Pashkevich, 2009). For each body (the Moon, the Sun, the major planets and Pluto) the files of the values of the components of the angular velocity of the geodetic rotation are constructed over the time span from AD1000 to AD3000 with one day spacing, by using DE422/LE422 ephemeris (Folkner, 2011), with respect to the proper coordinate systems of the bodies (Seidelmann et al., 2005). For the first time in the perturbing terms of the physical librations for the Moon and in Euler angles for other bodies of the Solar system the most essential terms of the geodetic rotation are found by means of the least squares method and spectral analysis methods.

Open access
On the Geodetic Rotation of the Major Planets, the Moon and the Sun

On the Geodetic Rotation of the Major Planets, the Moon and the Sun

The problem of the geodetic (relativistic) rotation of the major planets, the Moon and the Sun was studied in the paper by Eroshkin and Pashkevich (2007) only for the components of the angular velocity vectors of the geodetic rotation, which are orthogonal to the plane of the fixed ecliptic J2000. This research represents an extension of the previous investigation to all the other components of the angular velocity vector of the geodetic rotation, with respect to the body-centric reference frame from Seidelmann et al. (2005).

Open access