University of Architecture, Civil Engineering and Geodesy

About: University of Architecture, Civil Engineering and Geodesy is a education organization based out in Sofia, Bulgaria. It is known for research contribution in the topics: Finite element method & Beam (structure). The organization has 3808 authors who have published 3822 publications receiving 30736 citations. The organization is also known as: Sofia Polytechnic.

General Form of Voronovskaja’s Theorem in Terms of Weighted Modulus of Continuity

Abstract: In the present paper we use weighted modulus \({\omega_\varphi(f;\,h)}\) introduced by Pǎltǎnea in (Bull Transilvania Univ Brasov 4(53).67–74, 2011), and defined as $$\omega_\varphi(f;\,h)=\sup\left\{|f(x)-f(y)| : x \ge 0,y \ge 0, |x-y|\le h\varphi\left(\frac{x + y}{2} \right)\right\},$$ where \({h\ge 0\varphi(x)=\frac{\sqrt{x}}{1+x^m}, x\in [0,\infty),m\in \mathbb{N},m\ge 2}\). We establish the general form of Voronovskaja’s theorem in terms of the modulus \({\omega_\varphi(f;h).}\) In Sect. 3 applications are given for the Szasz–Mirakyan, Baskakov operators and the Phillips operators.

Heat treatment of centrifugally cast high carbon high vanadium high speed steel mill roll

Abstract: The effects of austenitising temperature and temper treatment on the microstructure, hardness and abrasive wear resistance of a high carbon high vanadium high speed steel roll of composition 2·2–2·4C, 5·5–6·5V, 4·5–5·5Cr, 14·0–16·0(W+2Mo), 1·0–1·4Ni and 1·2–1·5Nb (wt-%) were investigated by light optical microscopy, scanning electron microscopy, backscattered electron image, X-ray diffraction and hardness and wear testing. It was found that the hardness increases as the austenitising temperature increases to a maximum of 1050°C, and then begins to decrease because of the increase in retained austenite. Moreover, retained austenite begins to transform into martensite with increasing tempering temperature. The retained austenite in the quenched structure leads to the temper hardening of the rolls, which promotes improved abrasive wear resistance. The roll life of high carbon high vanadium high speed steel compound rolls austenitised at 1050–1080°C and tempered at 540–560°C increased by 400% (single ...