scholarly journals Validation of Components of Local Ties

2015 ◽  
pp. 21-28 ◽  
Author(s):  
Susanne Glaser ◽  
Mathias Fritsche ◽  
Krzysztof Sośnica ◽  
Carlos Javier Rodríguez-Solano ◽  
Kan Wang ◽  
...  
Keyword(s):  
Local Ties

scholarly journals ILRS Reference Point Determination Using Close Range Photogrammetry

2021 ◽  
Vol 11 (6) ◽  
pp. 2785
Author(s):  
Michael Lösler ◽  
Cornelia Eschelbach ◽  
Thomas Klügel ◽  
Stefan Riepl
Keyword(s):  
Reference Point ◽  
Reference Points ◽  
Geodetic Reference System ◽  
Unscented Transformation ◽  
Local Ties ◽  
Close Range Photogrammetry ◽  
Crucial Component ◽  
Space Geodetic Techniques ◽  
Close Range ◽  
Point Determination

A global geodetic reference system (GGRS) is realized by physical points on the Earth’s surface and is referred to as a global geodetic reference frame (GGRF). The GGRF is derived by combining several space geodetic techniques, and the reference points of these techniques are the physical points of such a realization. Due to the weak physical connection between the space geodetic techniques, so-called local ties are introduced to the combination procedure. A local tie is the spatial vector defined between the reference points of two space geodetic techniques. It is derivable by local measurements at multitechnique stations, which operate more than one space geodetic technique. Local ties are a crucial component within the intertechnique combination; therefore, erroneous or outdated vectors affect the global results. In order to reach the ambitious accuracy goal of 1 mm for a global position, the global geodetic observing system (GGOS) aims for strategies to improve local ties, and, thus, the reference point determination procedures. In this contribution, close range photogrammetry is applied for the first time to determine the reference point of a laser telescope used for satellite laser ranging (SLR) at Geodetic Observatory Wettzell (GOW). A measurement campaign using various configurations was performed at the Satellite Observing System Wettzell (SOS-W) to evaluate the achievable accuracy and the measurement effort. The bias of the estimates were studied using an unscented transformation. Biases occur if nonlinear functions are replaced and are solved by linear substitute problems. Moreover, the influence of the chosen stochastic model onto the estimates is studied by means of various dispersion matrices of the observations. It is shown that the resulting standard deviations are two to three times overestimated if stochastic dependencies are neglected.

scholarly journals TRANS-LOCALITY AMONG KURDS – THE CASE OF TURKEY

2020 ◽  
Vol 19 (2) ◽  
pp. 25-46
Author(s):  
Karol Kaczorowski
Keyword(s):  
Internal Migration ◽  
Diaspora Studies ◽  
Local Ties ◽  
Perceived Needs ◽  
Political Situation ◽  
Depth Interviews

The article aims at presenting trans-local aspects of Kurdish society and especially trans-local ties maintained by Kurds in Turkey, particularly in Istanbul. Inspired by transnational theories in migration and diaspora studies, the author proposes a categorization of Kurdish migration waves and waves of internal migration in Turkey. Drawing on in-depth interviews conducted with Kurds in Istanbul, the paper depicts ways of maintaining ties with the country’s Kurdish regions and types of social organizing around their culture and perceived needs. The paper also offers insights into contemporary Kurdish migration in Turkey, leading to the conclusion that although trans-locality has often been forced on Kurds, the socio-political situation in 2002–2015 led to the emergence of a new, trans-local, socially active Kurdish elite in Turkey

Co-location of SLR and GNSS techniques onboard Galileo and GLONASS satellites

2021 ◽  
Author(s):  
Grzegorz Bury ◽  
Krzysztof Sośnica ◽  
Radosław Zajdel ◽  
Dariusz Strugarek ◽  
Urs Hugentobler
Keyword(s):  
Orbital Plane ◽  
Terrestrial Reference Frame ◽  
Global Navigation Satellite Systems ◽  
Navigation Systems ◽  
Local Ties ◽  
Satellite Systems ◽  
The Impact ◽  
Space Ties ◽  
Gnss Observations

<p>All satellites of the Galileo and GLONASS navigation systems are equipped with laser retroreflector arrays for Satellite Laser Ranging (SLR). SLR observations to Global Navigation Satellite Systems (GNSS) provide the co-location of two space geodetic techniques onboard navigation satellites.</p><p>SLR observations, which are typically used for the validation of the microwave-GNSS orbits, can now contribute to the determination of the combined SLR+GNSS orbits of the navigation satellites. SLR measurements are especially helpful for periods when the elevation of the Sun above the orbital plane (β angle) is the highest. The quality of Galileo-IOV orbits calculated using combined SLR+GNSS observations improves from 36 to 30 mm for β> 60° as compared to the microwave-only solution. </p><p>Co-location of two space techniques allows for the determination of the linkage between SLR and GNSS techniques in space. Based on the so-called space ties, it is possible to determine the 3D vector between the ground-based co-located SLR and GNSS stations and compare it with the local ties which are determined using the ground measurements. The agreement between local ties derived from co-location in space and ground measurements is at the level of 1 mm in terms of the long-term median values for the co-located station in Zimmerwald, Switzerland.</p><p>We also revise the approach for handling the SLR range biases which constitute one of the main error sources for the SLR measurements. The updated SLR range biases consider now the impact of not only of SLR-to-GNSS observations but also the SLR observations to LAGEOS and the microwave GNSS measurements. The updated SLR range biases improve the agreement between space ties and local ties from 34 mm to 23 mm for the co-located station in Wettzell, Germany.</p><p>Co-location of SLR and GNSS techniques onboard navigation satellites allows for the realization of the terrestrial reference frame in space, onboard Galileo and GLONASS satellites, independently from the ground measurements. It may also deliver independent information on the local tie values with full variance-covariance data for each day with common measurements or can contribute to the control of the ground measurements as long as both GNSS and SLR-to-GNSS observations are available.</p>

Small business networks and local ties in Turkey

1995 ◽  
Vol 7 (3) ◽  
pp. 265-284 ◽  
Author(s):  
GÜL Berna Zcan
Keyword(s):  
Small Business ◽  
Business Networks ◽  
Local Ties

scholarly journals The Circulation of Scientific Articles in the Sphere of Web-Based Media: Citation Practices, Communities of Interests and Local Ties

PLoS ONE ◽  
2016 ◽  
Vol 11 (7) ◽  
pp. e0158393
Author(s):  
Muriel Lefebvre ◽  
Julie Renard
Keyword(s):  
Web Based ◽  
Local Ties ◽  
Citation Practices

On the impact of local ties on the datum realization of global terrestrial reference frames

2018 ◽  
Vol 93 (5) ◽  
pp. 655-667 ◽  
Author(s):  
Susanne Glaser ◽  
Rolf König ◽  
Karl Hans Neumayer ◽  
Tobias Nilsson ◽  
Robert Heinkelmann ◽  
...  
Keyword(s):  
Reference Frames ◽  
Local Ties ◽  
Terrestrial Reference Frames ◽  
The Impact

scholarly journals The effect of local ties, wages, and housing costs on migration decisions

2011 ◽  
Vol 40 (2) ◽  
pp. 132-140 ◽  
Author(s):  
Marios Michaelides
Keyword(s):  
Local Ties ◽  
Housing Costs ◽  
Migration Decisions
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