Innovations
Vol. 13 (2025), Issue 1

Table of Contents

  • INNOVATION POLICY AND INNOVATION MANAGEMENT

    • On application of generative artificial intelligence in higher education: insights from bulgarian students

      pg(s) 3-6

      The rapid integration of generative artificial intelligence (Generative AI) tools into higher education has significantly influenced student learning behaviour and academic practices. This research paper explores the ways in which undergraduate students at Sofia University “St. Kliment Ohridski” apply these technologies for both academic and non-academic purposes. The results reveal that students predominantly use Generative AI for academic support, such as explaining complex concepts, conducting research, and assisting in writing tasks. At the same time, they also engage with Generative AI for personal productivity, communication, and creative exploration. Despite having generally positive perceptions of academic effectiveness, students show critical awareness of risks related to information accuracy, privacy, and ethical use.

    • Application of Cybersecurity Awareness Training and End-User Behavioural Protection Simulation Platforms into Higher Education

      pg(s) 7-9

      As cyber threats continue to grow in scale and complexity, the demand for robust cybersecurity education has become increasingly urgent. This paper examines the application of cybersecurity awareness training and end-user behavioral protection simulation platforms within higher education settings. It analyses the challenges universities face in delivering both theoretical knowledge and hands-on experience in cybersecurity and highlights the pedagogical value of integrating simulation-based tools into undergraduate and postgraduate curricula. The study also underscores the importance of collaboration between academia, industry, and government to develop strategies for cultivating cyber competencies. By leveraging interactive platforms, institutions can better prepare students to recognize, respond to, and mitigate cyber risks in real-world environments.

  • INNOVATIVE SOLUTIONS

    • Innovative technical solution for emergency repair of a pressure tunnel water supply pipeline during its air passage over a river bed

      pg(s) 10-13

      The pressure water supply pipeline from the „Iskar Dam“, which has existed since 1981, is the main one for the water supply of the city of Sofia with drinking water. The water pipeline, for the most part executed as a concrete vault tunnel (mantel), passes through complex mountainous terrain with a large difference in elevation. During the long-term active operation, the steel part of the air passage of the water pipeline over the „Porkolitsa River” suffered a serious accident – internal pressure implosion of the steel pipe. The latter prevented the normal water supply to the city and an urgent repair was required by replacing the air-passing steel pipe of the water pipeline. The report discusses a proposed and successfully implemented innovative technical solution for monolithic installation of a steel pipeline in existing tunnel excavations with concrete lining by using self-compacting concrete with shrinkage compensated admixture and with the participation of special an internal crystallization chemical admixture, tailored to the specific requirements of the site. A prescribed composition of self-compacting concrete has been developed, the necessary control has been carried out during the batching plant production of the fresh concrete with monitoring of technical indicators. A technological regulation has been developed for the transport, laying and care of the concrete. During the site laying, standard sampling and testing have been carried out to prove the compressive strength at different ages of the concrete. Based on the above, in conclusion, the effectiveness of the developed and implemented innovative technical solution is certified.

    • Effect of organosilicate application on thermo-pressure bonding of metals and composites with thermoplastic matrix

      pg(s) 14-17

      The paper deals with application of organosilicate sol-gel to improve the adhesion of overlapped joints of metallic non-ferrous alloy thin sheets and continuous fibre reinforced composites by heat and pressure. The organosilicate layer showed a significant increase in adhesion of EN AW 6082 T6 and AZ91 alloys to glass fibre reinforced polypropylene matrix composite.

    • Optimization of femtosecond laser parameters on surface morphology of lithium disilicate glass ceramic

      pg(s) 18-21

      Lithium disilicate glass-ceramic is one of the most commonly used aesthetic materials in fixed prosthetics that requires surface pre-treatment. Recent studies have begun to propose a femtosecond laser for processing to improve surface morphology and microstructure, but without defined parameters. Therefore, the aim of this study is to determine the optimal parameters for the surface morphology of lithium disilicate glass-ceramics. The untreated sample of lithium disilicate glass-ceramic was observed with an optical profilometer. It was then treated with a femtosecond laser, forming squares on the surface of the sample, which were observed with an optical profilometer, and the surface morphology was analysed with a scanning electron microscope. The results show that laser treatment with higher energy densities leads to an increased roughness of the surface.

    • Electrical and hydrodynamic conditions in electrolyte-plasma treatment of internal surfaces

      pg(s) 22-26

      A method has been developed for performing electrolyte-plasma treatment (EPT) of internal surfaces. The method is based on the use of an electrode device that moves along the inner surface of the tubular workpiece and provides the necessary electrical and hydrodynamic conditions. The design of the electrode device combines a counter-electrode and a nozzle for supplying polarized electrolyte to the treated surface. The study presents the results of investigations into the electrical and hydrodynamic conditions during EPT of internal surfaces, as well as the influence of hydrodynamic characteristics on current parameters, metal removal rate, and the quality of the resulting surface.

    • Nanosized BaTiO3 powder prepared via mechanochemical activation

      pg(s) 27-29

      The technological possibilities for the synthesis of barium-titanate phases were investigated by applying mechanochemical activation (from 30 min. to 2 h) of the starting charges and thermal treatment of the compositions up to 900°C (with an isothermal delay of 1 h). The applied laboratory regime for the preparation of the experimental samples is in accordance with the preliminary thermodynamic calculations. The identification of the obtained phases was carried out by X-ray phase analysis (XRD). Based on the experimental results, the necessary technological conditions for the synthesis of titanate monophasic product by heat treatment at lower temperature values than those typical for standard classical synthesis have been established. The potential possibilities of application of the synthesized phases for the deposition of thin layers on metal surfaces and the preparation of various coatings with different functional purposes are considered.

    • Comparative Study of Bayesian-Optimized 1-D CNN, Bi-LSTM and MLP for Bearing Fault Classification from Raw Vibration Signals

      pg(s) 30-33

      This study evaluates the performance of newly designed deep-learning model—bidirectional long short-term memory network (Bi-LSTM), with baseline to a conventional multilayer perceptron (MLP)—for classification faults of rolling-element bearings from raw vibration signals. The models are benchmarked against a previously optimised one-dimensional convolutional neural network (1-D CNN), originally obtained via Bayesian hyperparameter search. A carefully selected dataset of 3600 one-second segments was captured under varying speed conditions and dynamically enhanced with Gaussian noise during processing. On the test set, the Bi-LSTM achieves 100 % accuracy, the 1-D CNN 97.9 %, and the MLP 53.3 %. Training dynamics, confusion patterns, and model complexity were thoroughly analysed, highlighting the trade-offs between accuracy, latency and deployment cost in edge-computing scenarios.

    • Photoluminescence properties of coatings on A356 containing Al2O3, Sm2O3 and ZrO2 synthesized by zol-gel technology

      pg(s) 34-36

      Thin coatings of aluminum oxide (Al2O3), zirconium oxide (ZrO2) and samarium oxide (Sm2O3) on aluminum alloy Al7SiMg (A356) were prepared by sol-gel method and immersion technique. The materials were characterized in detail by X-ray diffraction. The luminescent properties at room temperature were also investigated. Luminescence analysis showed that the Al2O3 coating containing ZrO2 exhibits broad excitation and emission bands, peaking at 328 nm and 392 nm, respectively. Photoluminescence data for the Al2O3 coating containing ZrO2 and Sm2O3 indicated effective excitation at 404 nm and strong broadband emission, which is due to the co-emission of ZrO2 and Sm2O3. Chromaticity coordinate analysis revealed that Al2O3 coating containing ZrO2 and Al2O3 coating containing ZrO2 and Sm₂ O₃ emit in the blue-purple and pale pink regions, respectively.The chromaticity coordinates, color purity and CIE (Commission Internationale de L’Eclairage) color-correlated temperature were determined.