Showing papers by "University of Architecture, Civil Engineering and Geodesy published in 2023"
01 Feb 2023
TL;DR: The first section of the narrow-gauge railway line was put into operation in the distant 1926, and the last sixth stage of it was completed in 1945 as mentioned in this paper , which is a single line, non-electrified, with a track gauge of 760mm, which makes it unique for Bulgaria and the Balkans.
Abstract: Abstract The first section of the narrow-gauge railway line Septemvri-Dobrinishte was put into operation in the distant 1926, and the last sixth stage of it was completed in 1945. It is single line, non-electrified, with a track gauge of 760mm, which makes it unique for Bulgaria and the Balkans. Apart from its track gauge, the line impresses with its spiral ascents, maximum longitudinal slopes - up to 32 ‰, minimum radii of horizontal curves of 50m and the highest station on the Balkan Peninsula, Avramovo 1267.4m above sea level. Within a total length of 125 km, 35 tunnels, 23 bridges, retaining walls and numerous culverts have been built. The article presents the current state of the major engineering facilities along the line - bridges and tunnels, as well as the state of the superstructure of the railway. Its technical characteristics, which makes it a unique achievement, both in terms of transport structural facilities and for railway construction in general, are also commented.
11 Apr 2023
TL;DR: In this paper , a knowledge-oriented learning resource recommendation method based on user interest model was proposed to solve the problem that the current traditional English classroom teaching in large classes has higher teaching efficiency, but it is difficult to take care of every student, and it was difficult to meet the needs of students' personalized learning.
Abstract: Abstract In order to solve the problem that the current traditional English classroom teaching in large classes has higher teaching efficiency, but it is difficult to take care of every student, and it is difficult to meet the needs of students' personalized learning, this paper combines user interest modeling and collaborative filtering algorithms to propose a knowledge-oriented learning resource recommendation method. Moreover, this paper proposes an algorithm based on user interest model. In addition, on the basis of obtaining the user's historical interest model, this paper combines user behavior information to obtain the user interest model and calculates the similarity between the candidate items and the user, and makes TOP-N recommendation based on the similarity calculation result. Finally, this paper conducts experiments on the news dataset, and compares the results with the benchmark algorithm to prove the effectiveness of the algorithm. The results show that this paper has achieved certain results in the research of combining multi-data source user interest modeling and recommendation and has made a little contribution to the research of interest modeling.
09 Jun 2023
TL;DR: In this paper , the authors generalize an old result due to Lowenthal and a more recent one due to Hamada on the order of finite generation of the rotation group SO (3 ) both for fixed and arbitrary compound transformations.
Abstract: We generalize an old result due to Lowenthal [1] and a more recent one due to Hamada [2] on the order of finite generation of the rotation group SO ( 3 ) both for fixed and arbitrary compound transformations. Unlike the above cited authors, we consider decompositions into factors with more than two invariant axes and provide rather intuitive geometric proofs. Thus, we derive a simple estimate for the number of factors in a decomposition and discuss possible means of optimization as well as particular examples of potential interest for the applications.
TL;DR: In this paper , the structural stability failure is a critical factor for arch bridges which are not transversally braced and that must be considered when the bearing capacity has to be determined.
Abstract: Abstract The structural stability failure is a critical factor for arch bridges which are not transversally braced and that must be considered when the bearing capacity has to be determined. One of the main parameters dictating the behaviour of arched structures in case of loss of stability is their slenderness. Accordingly, structures with high stiffness and low flexibility are expected to have significantly increased bearing capacity. The current paper consists analysis of complex 3-dimensional FE models, where the non – linear behaviour of geometry and materials is considered. The methodology is based on typical for bridge construction geometry, where are used typical cross – sections. The critical forces in the analysis are limited by the bending bearing capacity of the cross – sections. The results provide information about the advantages and disadvantages of the different structural solutions.
TL;DR: In this article , an elaborated inspection of the existing condition and operational capacity of the structure of a tunnel beneath the National Palace of Culture was carried out, together with the collected data and conclusion concerning the capacity of a top slab of the tunnel to undertake an additional load from a secondary track from a light rail load.
Abstract: Abstract The current paper considers and summarize the elaborated inspection of the existing condition and operational capacity of the structure of a tunnel beneath the National Palace of Culture and together with the collected data and conclusion concerning the capacity of the top slab of the structure to undertake an additional load from a secondary track from a light rail load. It also includes an assessment concerning the durability of the structure and the compliance with the regulation requirements. The report includes - review and analysis of the available design and other documentation for the site; Surveying and scanning of the main structural elements, incl. localization and registration of visible defects of the structure; performing static and dynamic field testing; structural analysis and calculation of the actual bearing capacity of the reinforced concrete slab of the tunnel according to the regulatory requirements.
03 Apr 2023
TL;DR: In this article , the determination of the natural frequencies and periods of a body with a fixed point is given, and two main approaches are considered: an analytical solution based on the principles of Lagrangian mechanics and a finite element analysis.
Abstract: Abstract In the current paper the determination of the natural frequencies and periods of a body with a fixed point is given. Two main approaches are considered. The first one is an analytical solution based on the principles of Lagrangian mechanics and the second is a finite element analysis. Although some equations are provided, the implementation of the analytical solution is achieved via MATLAB codes for simplicity and easier calculations. A finite element program (SAP2000) is used for the numerical solution. Different loading patterns are considered and the results of the two methods are compared. As the geometry of the problem is three-dimensional, some peculiarities of the model are discussed as well.