Freezing rooted cluster morphisms and pro-cluster algebras

We provide a new tool for studying cluster algebras by introducing a new category fClus of rooted cluster algebras. We characterize isomorphisms in our new category and show that it is neither complete nor cocomplete. We give a recipe for constructing morphisms in fClus with an interesting geometric interpretation and study the corresponding inverse systems. We define and study a new family of algebras, called pro-cluster algebras, with clusterlike combinatorics. The pro-cluster algebras are generated inside inverse limits of inverse systems in the category fClus. Initially, the generators of a pro-cluster algebra are grouped into certain subsets, called pro-clusters, of an inverse limit. In this new setting pro-clusters take the role of clusters and we construct pro-cluster algebras which are modelled by the combinatorics of infinitely marked surfaces and prove that all triangulations of those surfaces arise as pro-clusters

On the modelling of Kerberos protocol in the Quality of Protection Modelling Language (QoP-ML)

The security modelling of IT systems is a very complicated task. One of the issues which must be analysed is the performance of IT systems. In many cases the guaranteed security level is too high in relation to the real threats. The overestimation of security measures can decrease system performance. The paper presents the analysis of Kerberos cryptographic protocol in terms of quality of protection performed by Quality of Protection Modelling Language (QoP-ML). The analysis concerns the availability attribute. In the article the Kerberos protocol was modelled and the QoP analysis of two selected versions was performed

ASSESSMENT OF VELOCITY ACCURACY OF AIRCRAFT IN THE DYNAMIC TESTS USING GNSS SENSORS

The paper presents a new model for determining the accurate and reliable flight speed of an aircraft based on navigation data from the three independent Global Navigation Satellite System (GNSS) receivers. The GNSS devices were mounted on-board of a Cessna 172 aircraft during a training flight in south-eastern Poland. The speed parameter was determined as the resultant value based on individual components from 3 independent solutions of the motion model. In addition, the standard deviation of the determined flight speed values for the Cessna 172 aircraft was determined in the paper. The resultant on-ground and flight speed of the Cessna 172 aircraft ranged from 0.23 m/s to 74.81 m/s, while the standard deviation of the determined speed values varied from 0.01 m/s to 1.07 m/s. In addition, the accuracy of research method equals to -0.46 m/s to +0.61 m/s, in respect to the RTK-OTF solution. The RMS parameter as an accuracy term amounts to 0.07 m/s for the presented research method

Determination of reliability parameters of HPL and VPL technical safety in the procedure of a non-precision landing approach NPA GNSS with using GPS and GLONASS navigation systems in air transport

The paper presents the results of determining the HPL and VPL safety parameters used to evaluate the reliability of aircraft positioning in air transport. The HPL and VPL security level parameters were determined using GPS and GLONASS systems for the NPA GNSS non-precision landing approach. The work also compares the HPL and VPL values with the technical standards published by ICAO

Application of the SBAS/EGNOS positioning method to determine UAV coordinates

Abstract: The article presents the results of research on determining the UAV (Unmanned Aerial Vehicle) position using the SBAS (Satellite Based Augmentation System) positioning method for the EGNOS (European Geostationary Navigation Overlay Service) support system. The experiment used a single-frequency AsteRx-m2 UAS receiver, which recorded GPS (Global Positioning System) satellite observations and EGNOS corrections. The test flight was performed in 2020 near Warsaw. Navigational calculations for determining the position of the UAV during the flight were made in the gLAB v.5.5.1 software. Based on the performed calculations, the following were determined: BSP coordinates in the ellipsoidal system BLh, mean errors of BSP coordinates, and values of DOP (Dilution of Precision) geometric coefficients. In addition, during the calculations, it was found that the mean error values of the determined BSP coordinates do not exceed 3.6 m, and the maximum value of the geometric coefficient GDOP (Geometric DOP) is less than 3.5. Keywords: SBAS, EGNOS, BSP, mean errors, DO

Analysis of the accuracy of EGNOS+SDCM positioning in aerial navigation

The article presents a modified scheme of determining the accuracy parameter of SBAS (Satellite Based Augmentation System) positioning with use of two supporting systems: EGNOS (European Geostationary Navigation Overlay Service) and SDCM (System of Differential Correction and Monitoring). The proposed scheme is based on the weighted mean model, which combines single solutions of EGNOS and SDCM positions in order to calculate the accuracy of position-ing of the aerial vehicle. The applied algorithm has been tested in a flight experiment conducted in 2020 in north-eastern Poland. The phase of approach to landing of a Diamond DA 20-C1 aircraft at the EPOD airport (European Poland Olsztyn Dajtki) was subjected to numerical analysis. The Septentrio AsterRx2i geodesic receiver was installed on board of the aircraft to collect and record GPS (Global Positioning System) observations to calculate the naviga-tion position of the aircraft. In addition, the EGNOS and SDCM corrections in the “*.ems” format were downloaded from the real time server data. The computations were realized in RTKPOST library of the RTKLIB v.2.4.3 software and also in Scilab application. Based on the conducted research, it was found that the accuracy of aircraft positioning from the EGNOS+SDCM solution ranged from -1.63 m to +3.35 m for the ellipsoidal coordinates BLh. Additionally, the accuracy of determination of the ellipsoidal height h was 1÷28% higher in the weighted mean model than in the arith-metic mean model. On the other hand, the accuracy of determination of the ellipsoidal height h was 1÷28% higher in the weighted mean model than for the single EGNOS solution. Additionally, the weighted mean model reduced the resultant error of the position RMS-3D by 1÷13% in comparison to the arithmetic mean model. The mathematical model used in this study proved to be effective in the analysis of the accuracy of SBAS positioning in aerial navigatio

STRUCTURE, ORGANIZATION AND FORMING THE POLISH THIRD BRIGADE

The aim of the authors is a definite description selected issues constituting the history of the military formations existing in 1915–1917, which was the Third Brigade of the Polish Legions. On the basis of archival materials and scientific literature, the authors show the constitution of this unit, which played an important role in the struggle for Polish independence during the I World War. The construction of this study was preceded by an initial consideration, which includes in its shortened form of both aspects of the purely military and political background related with the struggle of the Polish Legions character. Next, the authors present the conditioning of the formation of 4 Infantry Regiment. The continuation of this logic is to consider the structure of the 6 Infantry Regiment. The rest of the authors complement resume closer: cavalry, artillery, command posts and the Third Brigade. At the end of the exhaust conclusions fragmented

Polish Cadastre Modernization with Remotely Extracted Buildings from High-Resolution Aerial Orthoimagery and Airborne LiDAR

Automatic building extraction from remote sensing data is a hot but challenging research topic for cadastre verification, modernization and updating. Deep learning algorithms are perceived as more promising in overcoming the difficulties of extracting semantic features from complex scenes and large differences in buildings’ appearance. This paper explores the modified fully convolutional network U-Shape Network (U-Net) for high resolution aerial orthoimagery segmentation and dense LiDAR data to extract building outlines automatically. The three-step end-to-end computational procedure allows for automated building extraction with an 89.5% overall accuracy and an 80.7% completeness, which made it very promising for cadastre modernization in Poland. The applied algorithms work well both in densely and poorly built-up areas, typical for peripheral areas of cities, where uncontrolled development had recently been observed. Discussing the possibilities and limitations, the authors also provide some important information that could help local authorities decide on the use of remote sensing data in land administration

Multi-Camera Imaging System for UAV Photogrammetry

In the last few years, it has been possible to observe a considerable increase in the use of unmanned aerial vehicles (UAV) equipped with compact digital cameras for environment mapping. The next stage in the development of photogrammetry from low altitudes was the development of the imagery data from UAV oblique images. Imagery data was obtained from side-facing directions. As in professional photogrammetric systems, it is possible to record footprints of tree crowns and other forms of the natural environment. The use of a multi-camera system will significantly reduce one of the main UAV photogrammetry limitations (especially in the case of multirotor UAV) which is a reduction of the ground coverage area, while increasing the number of images, increasing the number of flight lines, and reducing the surface imaged during one flight. The approach proposed in this paper is based on using several head cameras to enhance the imaging geometry during one flight of UAV for mapping. As part of the research work, a multi-camera system consisting of several cameras was designed to increase the total Field of View (FOV). Thanks to this, it will be possible to increase the ground coverage area and to acquire image data effectively. The acquired images will be mosaicked in order to limit the total number of images for the mapped area. As part of the research, a set of cameras was calibrated to determine the interior orientation parameters (IOPs). Next, the method of image alignment using the feature image matching algorithms was presented. In the proposed approach, the images are combined in such a way that the final image has a joint centre of projections of component images. The experimental results showed that the proposed solution was reliable and accurate for the mapping purpose. The paper also presents the effectiveness of existing transformation models for images with a large coverage subjected to initial geometric correction due to the influence of distortion

Multi-Camera Imaging System for UAV Photogrammetry

In the last few years, it has been possible to observe a considerable increase in the use of unmanned aerial vehicles (UAV) equipped with compact digital cameras for environment mapping. The next stage in the development of photogrammetry from low altitudes was the development of the imagery data from UAV oblique images. Imagery data was obtained from side-facing directions. As in professional photogrammetric systems, it is possible to record footprints of tree crowns and other forms of the natural environment. The use of a multi-camera system will significantly reduce one of the main UAV photogrammetry limitations (especially in the case of multirotor UAV) which is a reduction of the ground coverage area, while increasing the number of images, increasing the number of flight lines, and reducing the surface imaged during one flight. The approach proposed in this paper is based on using several head cameras to enhance the imaging geometry during one flight of UAV for mapping. As part of the research work, a multi-camera system consisting of several cameras was designed to increase the total Field of View (FOV). Thanks to this, it will be possible to increase the ground coverage area and to acquire image data effectively. The acquired images will be mosaicked in order to limit the total number of images for the mapped area. As part of the research, a set of cameras was calibrated to determine the interior orientation parameters (IOPs). Next, the method of image alignment using the feature image matching algorithms was presented. In the proposed approach, the images are combined in such a way that the final image has a joint centre of projections of component images. The experimental results showed that the proposed solution was reliable and accurate for the mapping purpose. The paper also presents the effectiveness of existing transformation models for images with a large coverage subjected to initial geometric correction due to the influence of distortion