Catenary - its history, significance and application

The catenary as an optimal architectural form has been known since ancient times. Its mathematical definition was discovered in 17th century and since then, this planar curve has become one of the most common shapes, not only in architecture, but also in the field of engineering

Catenary - its history, significance and application

The catenary as an optimal architectural form has been known since ancient times. Its mathematical definition was discovered in 17th century and since then, this planar curve has become one of the most common shapes, not only in architecture, but also in the field of engineering

Modeling, Motion Study, and Computer Simulation of Thomas Earnshaw’s Chronometer Detent Escapement Mechanism

The escapement is a very important horological invention and it is commonly used in theory of clocks and chronometers. It transfers energy to the timekeeping element and allows the number of its oscillations to be counted. The chronometer detent escapement used in marine chronometers was modified and simplified by Thomas Earnshaw, English renowned watchmaker, in order to make it available to the public. This chapter deals with 3D modeling and assembling of all escapement parts in SolidWorks, as well as constructive geometry of mechanism and computer simulation. The whole process has been accomplished in program “SolidWorks 2016,” where all parts are assembled by using standard mates since this approach is suitable for motion and dynamical analysis. Generated simulation results are very close to the real ones, thereby using computationally strong kinematic solvers

PROTECTION OF BUILDING HERITAGE - CASE STUDY OF GREEK BUILDINGS IN DIMITROVGRAD

During 2020, the Institute for the Protection of Cultural Monuments of Nis conducted extensive research in the part of the municipality of Dimitrovgrad in order to record buildings, sites or entities with monumental properties. On that occasion, among other things, a larger number of city villas was recorded. The paper presents three selected representative examples of this type of house. An architectural analysis of each of the observed buildings is presented, as well as ortho-photo attachments. The entire procedure of documenting the building is listed and explained, from field drawings, through the elaboration of documentation to the development of 3d models. One of the goals of the entire research procedure, in addition to preparing documentation for further legal protection of buildings, was to educate students in the field of protection of architectural heritage, on specific tasks

Microstructural and fracture analysis of microalloyed steel weld metal

In this paper is presented behavior of microalloyed steel weld metal with niobium during impact testing, as well as microstructural characterization. Impact tests were done on instrumented Charpy pendulum at room temperature, at -40 degrees C and -55 degrees C. At room temperature, crack propagation energy is much higher than crack initiation energy, while at -40 degrees C and -55 degrees C crack growth energy is lower than crack initiation energy. Fractographic investigation of the fracture surfaces has shown that at room temperature ductile trans-granular fracture is dominant, with a small amount of brittle trans-granular fracture. At lower temperature, the share of brittle fracture is increased, and inter-granular brittle fracture becomes dominan

Crack growth resistance of weldment constituents

The ovennatching can affect the occurrence of cold cracks after welding in high-strength low-alloyed steels of 770 MPa yield strength class. The welding consumable has been designed in a way to produce WM with slightly lower strength properties compared to BM (undennatching effect). The application of high-strength low-alloyed steel SUMIITEN 80P, required a large scope of testing for estimation of behavior of welded joints under different loading conditions, in order to give the reliable estimation of penstock safety

Application of the Improved Force Field Analysis on Airport Capacity Expansion Example

In this paper the process of force field analysis (hereafter: FFA) is analyzed, disadvantages of this method are noted and a mode is proposed which allows reducing those disadvantages and increasing the reliability of solving complex problems using the FFA. To improve FFA, a research is conducted, several different methods are applied, and more than 40 specialists are tested. A new model of FFA is offered which is improved by a decision making trial evaluation laboratory (hereafter: DEMATEL) method. Improvement of FFA by using DEMATEL method is explained in the case study that describes the determination by business success of air transport and airport various economic factors. The effect of those factors can be positive or negative. Based on the results of research in the case study it is concluded that the proposed model maintains all advantages of current model and reduces the disadvantages. Also, the improved method increases the reliability of FFA. In addition to the scientific contribution there is also a significant social contribution of this research, which is reflected in the application of the proposed model in decision-making process

Selecting hardfacing technologies for ventilation mill suction plates and extending its working life

This paper presents results of the suction plate surface modification by hardfacing, of the ventilation mill in the Kostolac B power plant. Before applying hardfaced suction plates to exploitation conditions, it is necessary to study model hardfaced samples for determining the optimal tech-nology and filler material for revitalization. Experimental tests of revitalized mill suction plates in real exploitation conditions show that the proposed modification, hardfacing technologies and filler materials give good results. The relative weight loss of the suction plates after 1440 h period of exploitation in real conditions is 1-3%. The application of this approach can reduce the number of possible repairs and extends the period between them, resulting in significant economic effects