https://ojs.nbu.bg/index.php/ANSD <p><strong>Annual of Natural Sciences Department</strong> is a journal of the Department of Natural Sciences, New Bulgarian University (NBU) and is published once a year. The Annual of Natural Sciences Department has been published since 2015 and is included in the National Reference List of Contemporary Bulgarian Scientific Publications with Scientific Review (http://nacid.bg/bg/NRS/). The jourmnal is Open Access, and all articles are freely available to users and institutions to which they are associated under the Creative Commons Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0).&nbsp;Annual of Natural Sciences Department includes manuscripts in Bulgarian with a summary in English. In order to more widely promote and take into account the interests of a wide range of researchers, teachers, students, PhD students, etc., manuscripts in English and Russian are also accepted. The Editorial Board and the Board of Reviewers are composed of recognized scientists in various fields of science, materials science and business from leading national and foreign universities.</p> New Bulgarian University en-US Annual of Natural Sciences Department 2367-6302 https://ojs.nbu.bg/index.php/ANSD/article/view/1402 <p>The analysis explores the growth of the used computer systems market in Bulgaria, highlighting economic and environmental benefits such as savings and reduced electronic waste. The system integration market is also growing due to European programs, with a focus on innovation and cybersecurity. Challenges in the used equipment market include technical issues and limited compatibility, but it remains attractive to small and medium-sized enterprises.</p> Georgi Petrov Borislav Mitov Copyright (c) 2025 Georgi Petrov, Borislav Mitov http://creativecommons.org/licenses/by-nc/4.0 2025-12-30 2025-12-30 10 1 11 10.33919/ansd.25.10.1 https://ojs.nbu.bg/index.php/ANSD/article/view/1403 <p>The paper elaborates the concept of the Intelligent School as a constituent of the smart city and as a bridge linking education, natural sciences, and technological innovation. The paper follows the evolution of the concept of the smart city and introduces the intelligent school as a micromodel of urban sustainable development. Special attention is paid to STEM education as the core of the intelligent school, with a focus on pedagogical innovations, the teachers' role, and challenges related to teachers' professional preparedness. The technological infrastructure of the intelligent school is covered by the convergence of IoT, artificial intelligence, virtual and augmented reality, and energy-efficient infrastructure. A conceptual model of intelligent education is proposed, as well as implementation and adaptation strategies. The paper also presents examples of best practices in STEM education in Bulgaria. The findings confirm that the smart school is not only a center of knowledge and innovation but also a driver of sustainable development and digital transformation in the smart city context.</p> Nikolay Nikolov Copyright (c) 2026 Nikolay Nikolov http://creativecommons.org/licenses/by-nc/4.0 2025-12-30 2025-12-30 10 12 24 10.33919/ansd.25.10.2 https://ojs.nbu.bg/index.php/ANSD/article/view/1404 <p>Research results of official statistical data on flood crises that occurred in Bulgaria for the period from 2010 to 2020 by region are presented. Monitoring their occurrence and spread is an important element for their prevention and contributes to achieving the sustainable development goals. The results show that flood crises are registered every year and in every region of our country. The results show that over 54% of these crises were in the period 2010–2013, with the peak in 2012. Their minimum were in 2018. Sliven, Smolyan and Burgas are the regions with the largest number of registered flood crises.</p> Ralitza Berberova Bilyana Kostova Copyright (c) 2025 Ralitza Berberova, Bilyana Kostova http://creativecommons.org/licenses/by-nc/4.0 2025-12-30 2025-12-30 10 25 31 10.33919/ansd.25.10.3 https://ojs.nbu.bg/index.php/ANSD/article/view/1405 <p>Results of the interpretation of official statistical data on natural disaster crises in Bulgaria for the period from 2010 to 2020 are presented. The study of natural hazards and the monitoring of the crises caused by them are important activities in terms of prevention and in the context of sustainable development, due to their impact on the economy, the environment and the people’s quality of life. Such crises are registered in our country every year. The results show that more than half of the occurring natural disaster crises are due to floods, and for the occurrence of some of them, the anthropogenic factor must be taken into account. A downward trend in the occurrence of natural disaster crises has been identified, with a significant peak in registered crises in 2012.</p> Ralitza Berberova Bilyana Kostova Copyright (c) 2025 Ralitza Berberova, Bilyana Kostova http://creativecommons.org/licenses/by-nc/4.0 2025-12-30 2025-12-30 10 32 39 10.33919/ansd.25.10.4 https://ojs.nbu.bg/index.php/ANSD/article/view/1406 <p>The concept of a "smart city" should not be associated solely with a "digital city". A city can be classified as a smart city if economic activities, mobility, environmental resources, relationships between people, housing policy and the way in which technological innovations are implemented are intelligently managed. The aim of the study is to establish the ecological footprint of smart cities through sustainable development indicators. The results show that Carbon dioxide (CO₂) emissions are associated with emissions from industrial processes, as well as from the burning of fossil fuels. The conclusion that can be reached is that although Sofia has lower CO₂ emissions per capita than Amsterdam in 2024, the trend is worrying, as emissions are increasing on an annual basis, while for Amsterdam and Vienna they are decreasing. For Sofia, the green area per capita is found to be 9 square meters per person. A comparison of the three cities shows that Vienna is the city with the largest amount of green space per capita. The capital of Austria is distinguished by over 55% green space of its total area, which means that each resident has an average of 120 square meters of green space, including parks, gardens, and other green areas. Annual average PM concentrations in Sofia are significantly higher than those recommended by the WHO. The data analysis shows that among the three cities studied, the average annual PM10 level is highest in Sofia, followed by Vienna. The indicator in Amsterdam has a significantly lower value.</p> Nikolay Nikolov Copyright (c) 2025 Nikolay Nikolov http://creativecommons.org/licenses/by-nc/4.0 2025-12-30 2025-12-30 10 40 50 10.33919/ansd.25.10.5 https://ojs.nbu.bg/index.php/ANSD/article/view/1407 Editorial Board Copyright (c) 2025 Editorial Board http://creativecommons.org/licenses/by-nc/4.0 2025-12-30 2025-12-30 10 https://ojs.nbu.bg/index.php/ANSD/article/view/1408 Editorial Board Copyright (c) 2025 Editorial Board http://creativecommons.org/licenses/by-nc/4.0 2025-12-30 2025-12-30 10