Risk assessment of financing renewable energy projects: A case study of financing a small hydropower plant project in Serbia

The production of rolling bearings is a complicated process that requires the use of many operations. The manufactured elements of rolling bearings should be of high quality while minimizing production costs. Despite many research studies related to the analysis of technological processes, there is still a lack of research and tools allowing us to satisfactorily assess the relationships between individual operations of the rolling bearing ring process of production and the quality. To perform such an assessment, one can use the concept of technological heredity phenomenon analysis. As the surface waviness of the bearing race is of key importance, the present paper aims at evaluating how the individual technological operations of the rolling bearing ring production process affect the formation of their surface waviness. The surface waviness of the bearing race was measured in both directions (two sections), i.e., along the circumference using the Talyrond 365 measurement system and across the circumference of the race using Talysurf PGI. The production of 6308-2z rolling bearings made of AISI (American Iron and Steel Institute) 52100 bearing steel was analyzed. The occurrence of the phenomenon of technological heredity in the production of rolling bearings was observed. The research results indicate that the turning operation reduces the surface waviness of the bearing rings obtained after forging, while the heat treatment causes a slight increase in surface waviness. On the other hand, grinding operation significantly reduces the waviness, with this reduction being greater for the outer ring. Furthermore, the research has shown that the waviness of the surface is an inheritance factor caused by individual operations of the rolling bearing rings manufacturing process.

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Analysis of Technological Heredity in the Production of Rolling Bearing Rings Made of AISI 52100 Steel Based on Waviness Measurements

This paper presents the results of voluminous experimental investigations conducted to analyze the influence of the welding procedure on the performance of regenerated gears. Cylindrical spur gears were tested, both newly manufactured and regenerated, in two fundamentally different ways: by hard facing (surfacing) with the “hard” filler metal (DUR 600-IG) and with the “soft” filler metal (EVB2CrMo) with subsequent cementation and quenching. The regeneration procedures were defined and executed, while, subsequently, the microstructure and microhardness of the hard-faced layers were established and measured, followed by checking the durability of the hard-faced teeth flanks. Finally, techno-economic analysis was performed to establish the rationality of the conducted regenerations, i.e., the costs of regenerated and newly manufactured teeth were compared. Based on the results of the conducted investigations, it was possible to establish the influence of the welding type on the performance characteristics (primarily the service life) of the regenerated gears. For individual reparatory hard facing, the procedure with the “hard” filler metal exhibited better characteristics, while for batch reparation of numerous damaged gears, the reparation with the “soft” filler metal, followed by cementation and heat treatment, might be more convenient.

https://www.mdpi.com/1996-1944/14/6/1496/pdf

Analysis of the Welding Type and Filler Metal Influence on Performance of a Regenerated Gear

Material Selection and Processing Techniques: Crucial Factors for Gear Engineering

Investigation of the heavy duty truck gear drive failure

Technological heredity – A decisive factor for tribological features of regenerated gears

At the end of the 19th century, Serbia was among the first European countries to start electrification. A very bad economic situation, caused by centuries-old slavery and lack of capital, did not prevent the Serbs to start introducing electricity into settlements and a few industrial plants. They had the idea of ​​introducing electricity implemented before many other more developed countries of Europe and the world. A great merit for this belongs to the Serbian scientist and inventor Nikola Tesla, as well as to his good friend Djordje M. Stanojevic, the professor and rector of Belgrade University. The first electric power plant in Serbia, which produced direct electric current by coal combustion, was put into operation in Belgrade, the Serbian capital, in 1893, twelve years after Edison’s first such plant in the world. Also, the first hydroelectric power plant with three-phase alternating electric current in Serbia began operating in 1900, four years after the first power plant of its kind in the world (Niagara Falls, 1896). This hydropower plant, the first in the Balkans and one of the first in Europe, is described in this paper.

The First Hydroelectric Power Plant in the Balkans Built on the Basis of Tesla’s Principles

Mathematical Background of U-joint Repair

This paper presents the results of Tesla’s work and research in the field of fountains that was accomplished and completed in 1917 In this period the inventor designed and developed five different models of table fountains The design of one table fountain was further modified and developed resulting in four completely distinguishable versions of the same device By exploring the original archival documents, the authors attempted to present the inventor’s research in this less known field and the unknown details of his rich achievements The authors also present CAD models based on original table fountain drawings, which are archived as a part of Tesla’s legacy in the Nikola Tesla Museum in Belgrade

Svetislav Marković

Papers

Technological heredity – A decisive factor for tribological features of regenerated gears

The First Hydroelectric Power Plant in the Balkans Built on the Basis of Tesla’s Principles

Mathematical Background of U-joint Repair

Unrealized Models of Tesla’s Table Fountains From 1917