VILNIUS TECH Methodological Guidelines for the preparation of Final Theses, Internship Reports

VILNIUS TECH Library invites you to follow the published new dissertations. The dissertation „Development and Property Studies of Structures with Acoustic Metamaterial Made from Recycled Plastic“ („Konstrukcijų su akustine metamedžiaga iš perdirbto plastiko kūrimas ir savybių tyrimai“) prepared at VILNIUS TECH by Andrej Naimušin. The dissertation was prepared in 2021–2026. Scientific consultant – Assoc. Prof. Dr Tomas Januševičius. The dissertation was defended at the public meeting of the Dissertation Defence Council of the Scientific Field of Environmental Engineering in the Aula Doctoralis Meeting Hall of Vilnius Gediminas Technical University at 9 a.m. on 15 May 2026. The dissertation examines plastic constructions and an acoustic metamaterial that is based on the Helmholtz resonator’s operating principle. The main object of the research is a structure made of a metamaterial from recyclable plastic, which has good sound insulation and sound absorption properties. The dissertation aims to create a structure made of metamaterial from recycled plastic to improve sound insulation for indoor partitions and room sound absorption. The following tasks are solved in the work: the first task concerns the development of metamaterials and the study of their non-acoustic and acoustic properties; the second task is related to theoretical calculations for individual metamaterial resonators using the transfer matrix method; the third and fourth tasks characterise acoustic properties using an interferometer and a sound transmission chamber, and the design of sound-absorbing panels made of recycled plastic metamaterial and sound-insulating systems with recycled plastic metamaterial; and the fifth task is the prediction of the sound insulation and sound absorption of the final engineering solution using modelling programmes. The dissertation consists of an introduction, three chapters, general conclusions, a list of used literature, and a list of the author’s publications on the topic of the dissertation. The introductory chapter describes the research problem and the work’s relevance, describes the object of the research, formulates the aim and tasks of the work, indicates the research methodologies, the scientific novelty of the work and the practical significance of the work results, and presents defended statements. The introduction closes by listing the author’s publications and conference presentations on the dissertation topic and by providing the dissertation’s structure. The First Chapter examines the possibilities of recycling plastic waste to improve indoor acoustics and analyses scientific research on sound insulation and sound absorption. The Second Chapter presents methodologies for sample calculation and preparation, determination of acoustic and non-acoustic properties, and modelling of sound insulation and absorption. The Third Chapter presents the results of theoretical, sound insulation, sound absorption, and static air resistance research and their analysis. Five scientific articles have been published on the dissertation topic: three in scientific journals included in the Web of Science database; one in the Scopus-referenced conference proceedings; and one in a conference proceedings publication referenced in other international databases. Five presentations on the dissertation topic were given at conferences in Lithuania and abroad. Doctoral dissertation readers can search via VILNIUS TECH Virtual Library.

VILNIUS TECH Library invites you to follow the published new dissertations. The dissertation „Economic assessment of agricultural sector in the context of sustainability“  prepared at VILNIUS TECH by Ahmad Bathaei. The dissertation was prepared in 2021–2026. Scientific consultant – Prof. Dr Dalia Štreimikienė. The dissertation was defended at the public meeting of the Dissertation Defence Council of the Scientific Field of Economics in the Aula Doctoralis Meeting Hall of Vilnius Gediminas Technical University at 2 p.m. on 14 May 2026. This dissertation explores the economic assessment of the agricultural sector within the broader context of sustainability, with a particular focus on the Baltic States. As agriculture continues to play a central role in rural economies and food security, integrating sustainability principles into economic evaluation has become increasingly important. Despite numerous studies on sustainable agriculture, there remains a lack of comprehensive frameworks that combine multidimensional indicators with region-specific data and stakeholder input. This research develops an integrated methodology for gap-filling to identify, evaluate, and prioritise sustainability indicators, and to develop the indicators across the economic, environmental, and social domains. The work comprises four interconnected pieces of research. First, a systematic review of the literature conducted under the SALSA (Search, Appraisal, Synthesis, and Analysis) and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) protocols identified 101 indicators, which will serve as a basis for the subsequent analyses. Second, a focused review of the conjunction of renewable energy and agriculture identified 84 indicators and demonstrated the importance of energy efficiency and resource circularity for sustainable farming practices. Third, this research applied the TOPSIS (Technique for Order of Preference by Similarity to the Ideal Solution) method for the first time to rank sustainability indicators in the Baltic States, integrating expert opinions with Eurostat statistical data. The assessment examined the environmental priorities of soil health, water and fertiliser management, and the social and economic dimensions. Finally, eleven economic indicators identified through the Delphi and the Best–Worst Method (BWM) were selected and ranked, and investment intensity, income diversification, labour productivity, and market access were found to be the most important economic indicators of agricultural sustainability. The studies allow for drawing up evidence-based policy formulation and strategic planning. The dissertation presents a new model for evaluating sustainable agriculture. It provides a practical, regionally specific, and empirically precise understanding of the sustainability problem. The framework helps policy makers, researchers, and practitioners, particularly in post-transition economies, identify areas that require intervention and investment, such as Lithuania, Latvia, and Estonia. The adaptability of this work to other parts of the world facing the same problem is a means of assisting countries in achieving sustainable agricultural development through economic evaluation. Doctoral dissertation readers can search via VILNIUS TECH Virtual Library.