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.

Bio-inspired optimization of weighted-feature machine learning for strength property prediction of fiber-reinforced soil

Abstract: The fiber-reinforcement of soil is an effective and reliable ground improvement technique for increasing the strength and stability of soil for various purposes (including retaining structures, embankments, foundations, slopes and pavements). Numerous scholars have developed methods to identify factors that influence the shear strength and to predict the peak friction angle of fiber-reinforced soil (FRS). The accuracy of theoretical and empirical models for predicting the shear strength (peak friction angle) of FRS is questionable because of the difficulty of using these simplified models to describe the complex mechanism of soil-fiber interaction. Solutions to this problem require ever-increasing predictive accuracy, and ML-based methods have been confirmed to provide potential solutions to real-world engineering problems. Therefore, this study develops weighted-feature least squares support vector regression (WFLSSVR) that is optimized by a novel metaheuristic algorithm, jellyfish search (JS) algorithm, to predict the peak friction angle of FRS. Analytical results demonstrate that JS-WFLSSVR outperforms baseline, ensemble, and hybrid machine learning models as well as empirical methods in literature. Notably, analysis of the weight values that were obtained by JS-WFLSSVR enables the identification of new feature combinations that provide much higher accuracy than current models. Therefore, the JS-WFLSSVR model not only significantly provides better predictive accuracy than methods in the literature; it is also a good feature selection method, and can help geotechnical engineers in estimating the shear strength of FRS. Geotechnical engineers can use the proposed model to predict the shear strength and control the quality of FRS structures.

On the kinetics of pozzolanic reaction in metakaolin–lime–water system

Abstract: The kinetics of pozzolanic reaction metakaolin–lime is studied in the present work. Metakaolin is prepared by calcination of enriched kaolin (deposit “Senovo”, Bulgaria) at temperature of 830 ± 10 °C in a labscale muffle oven. The reaction is performed in intensively stirred water suspension at different temperatures in the range 20–100 °C. The kinetics is analyzed by comparing the experimental data with theoretical curves, derived according to appropriate kinetic and diffusion models taking into account the grain size distribution of metakaolin. The macroscopic mechanism and activation energy of the reaction are determined. It is found, that the activation energy decreases gradually from 71 to 45 kJ/mol[Ca(OH)2] with the increase of the reaction degree from 0.2 up to 0.6, respectively, which is a characteristic for transition regime reactions.

A review of calcined clays and ceramic wastes as sources for alkali-activated materials

Abstract: Expanding and optimising the raw materials base in accordance with increasing ecological and technical requirements is one of the determining factors of a promising future for the constantly evolvi...

Dynamic Response of a Pre-Stressed Transversely Isotropic Plate to Impact by an Elastic Rod

Abstract: This article considers the problem of normal impact of a long thin elastic cylindrical rod upon an infinite pre-stressed elastic transversely isotropic plate possessing cylindrical anisotropy. The impact takes place at the center of the plate, whose equations of motion take both rotary inertia and shear deformations into account. During the shock interaction of the rod with the plate, waves with strong discontinuities are generated in the plate and begin to propagate. Behind the fronts of these waves, the solution is constructed in terms of ray series, the coefficients of which are the different order discontinuities in partial-time derivatives of the desired functions, and the time elapsed after the wave arrival at the point (of the plate) under consideration is a variable. The ray series coefficients are determined from recurrent equations within the accuracy of arbitrary constants, which are determined from the conditions of the dynamic contact interaction between the impactor and the target. These arb...