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.

Global Multi-isotopologue fit of measured rotation and vibration–rotation line positions of CO in X1Σ+ state and new set of mass-independent Dunham coefficients

Abstract: A set of mass-independent Umj and Δmj parameters globally describing vibration–rotation energy levels of the CO molecule in the X1Σ+ ground electronic state was fitted to more than 19,000 transitions of 12C16O, 13C16O, 14C16O, 12C17O, 13C17O, 12C18O, and 13C18O isotopologues collected from the literature. The maximal values of the vibrational V and the rotational J quantum numbers included in the fit was 41 and 128, respectively. The weighted standard deviation of the fit is .66. Fitted parameters were used for calculation of Dunham coefficients Ymj for nine isotopologues 12C16O, 13C16O, 14C16O, 12C17O, 13C17O, 14C17O, 12C18O, 13C18O, and 14C18O. Calculated transition frequencies based on the fitted parameters were compared with previously reported. A critical analysis of the CO HITRAN and HITEMP data is also presented.

Investigation of solution chemistry effects on sorption behavior of radionuclide 64Cu(II) on illite

Abstract: In this work, a series of batch experiments were carried out to investigate the effect of various environmental factors such as contact time, pH, ionic strength, coexisting electrolyte ions, humic substances and temperature on the sorption behavior of illite towards 64Cu(II). The results indicated that 64Cu(II) sorption on illite achieved equilibrium quickly. The pH- and ionic strength-dependent sorption suggested that 64Cu(II) sorption on illite was dominated by ion exchange or outer-sphere surface complexation at pH 7. A positive effect of humic substances on 64Cu(II) sorption was found at pH 6.5. The Langmuir and Freundlich models were used to simulate the sorption isotherms of 64Cu(II) at three different temperatures of 293, 313, and 333 K. The thermodynamic parameters (ΔH 0, ΔS 0, and ΔG 0) of 64Cu(II) sorption on illite were calculated from the temperature dependent sorption isotherms, and the results indicated that the sorption of 64Cu(II) on illite was endothermic and spontaneous. From the experimental results, it is possible to conclude that illite has good potentialities for cost-effective treatments of 64Cu(II)-contaminated wastewaters.

Correction of the Shear-Stress-Transfer Model with Account of the Curvature of Streamlines in Calculating Separated Flows of an Incompressible Viscous Fluid

Abstract: The necessity of correcting differential semiempirical turbulence models to calculate circulating flows of an incompressible viscous fluid is discussed. Approaches to taking account of the influence of the curvature of streamlines on turbulence characteristics are reviewed. Experience gained in modeling numerically two dimensional separated flows in a square and a cylindrical cavity on the wall of a plane-parallel channel is analyzed; an additional semiempirical constant in the expression for vortex viscosity of a modified shear-stress-transfer model is substantiated.