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Performance of Absolute Real-Time Multi-GNSS Kinematic Positioning

Abstract

Recently, we observe the rapid development of the Global Navigational Satellite Systems (GNSS), including autonomous positioning techniques, such as Precise Point Positioning (PPP). The GNSS have different conceptions, different spacecraft and use different types of orbits which is why the quality of real-time orbit and clock products is inconsistent, thus, the appropriate approach of the multi-GNSS observation processing is needed to optimize the solution quality. In this paper, the kinematic field experiment is conducted in order to examine multi-GNSS real-time Standard Point Positioning (SPP) and PPP performance. The test was performed on the 26 km-long car route through villages, forests, the city of Wrocław, crossing under viaducts and a high tension line. For the first time, the solution is based on GPS + GLONASS + Galileo + BeiDou observations using streamed corrections for orbits and clocks with two different weighting scenarios. Thanks to the usage of the multi-GNSS constellation the number of positioning epochs possible to determine increases by 10%. The results show also that the appropriate weighting approach can improve the root mean square error in the SPP solution by about 13% and 42% for the horizontal and vertical coordinate components, respectively. In the case of PPP, the maximum quality improvement equals 70% for the horizontal component and the results for the vertical component are comparable with those obtained for the GPS-only solution.

Open access
Quality Control Process of Manufactured Composite Structures

Abstract

The paper includes a description of the composite material used in the aviation industry. It presents the technological development of composites in terms of their use in the most important elements of the aircraft structures, such as a spar and aircraft wing sheathing, which are subjected to high loads during operation. The type of the material implemented for production was listed and the most commonly occurred incompatibilities during the carbon pre-impregnate manufacture and transport were described.

The manufacture diagram of composite elements with a polymer matrix was presented and the quality control system carried out at each mentioned stage (material storage, defrosting, cutting of dies, structure forming, polymerisation) was discussed.

The methods of non-destructive tests of carbon laminates in a polymer matrix were also listed, describing the most effective of them, i.e. a method of ultrasonic tests.

The conclusions were drawn and the development possibilities of ultrasonic tests both in terms of quality improvement and reduction of time for detecting incompatibilities in composite structures were described.

Open access