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Application of satellite techniques in geodesy and navigation in Poland

100%

Baran L. W., Oszczak S., Zieliński J. B.

Nauka

2008

issue 4

Contemporary geodesy is of global dimension. The reference frame is defined as the geocentric system with parameters related to the entire Earth body, e.g. the axis of rotation, and global geoid. The unified time scale is determined for the whole Earth territory as well. International services using different satellite techniques are engaged in the determination of this frame. Particularly important is the Global Positioning System GPS, which is the most important geodetic tool nowadays. In Poland a number of geodetic observatories are working in the frame of the international networks, Polish scientific groups contribute to the advancement of science in this domain. For the practical applications we are using the local networks that again are constructed with satellite techniques. In Europe the regional network EUREF exists while its part EUREF-POL and densification POLREF are in Poland. The modern network ASG-EUPOS is under construction. The GPS technique is used for surveying and navigation and for the positioning in motion, which is in-between the preceding traditional methods. Differential augmentation methods are designed to improve GPS signals such as DGPS and EGNOS. The new European satellite navigation system Galileo is in development. Poland is a member and coowner of this system. A number of Polish research institutions are working on new methods of the practical application of GNSS.

Perspectivism and special relativity

84%

Khalili M.

Teorie vědy (Theory of Science)

2021

vol. 43

issue 2

191-217

Th e special theory of relativity holds signifi cant interest for scientifi c perspectivists. In this paper, I distinguish between two related meanings of “perspectival,” and argue that reference frames are perspectives, provided that perspectival means “being conditional” rather than “being partial.” Framedependent properties such as length, time duration, and simultaneity, are not partially measured in a reference frame, but their measurements are conditional on the choice of frame. I also discuss whether the constancy of the speed of light depends on perspectival factors such as the idealized defi nition of the speed of light in a perfect vacuum and the Einstein synchronization convention. Furthermore, I argue for the view that the constancy of its speed is a robust property of light according to the conditions of currently acceptable experimental setups pertaining to special relativity, and conclude that this view supports perspectivism.

Speciální teorie relativity je obzvláště zajímavá z hlediska vědeckého perspektivismu. V tomto článku rozliším dva související významy pojmu „perspektiva“ a pokusím se ukázat, že vztažné soustavy lze chápat jako perspektivy za předpokladu, že perspektivou rozumíme spíše „být podmíněný“, a nikoli „být dílčí“. Vlastnosti závislé na vztažné soustavě, jako je délka, časové trvání a simultánnost, nejsou v dané vztažné soustavě měřeny neúplně, ale jejich měření jsou podmíněna výběrem vztažné soustavy. Rovněž se budu zabývat otázkou, zda stálost rychlosti světla závisí na perspektivních faktorech, jako je idealizovaná defi nice rychlosti světla v dokonalém vakuu a Einsteinova synchronizační konvence. Na závěr se pokusím ukázat, že konstantní rychlost je robustní vlastností světla dle podmínek aktuálně přijímaných experimentů týkajících se speciální relativity a že tento pohled podporuje perspektivismus.

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1 Nauka

1 Teorie vědy (Theory of Science)

1 Baran L. W.

1 Khalili M.

1 Oszczak S.

1 Zieliński J. B.

1 2021

1 2008

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Application of satellite techniques in geodesy and navigation in Poland

Perspectivism and special relativity