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VILNIUS TECH Library invites you to follow the published new dissertations. The dissertation „Performance investigation of a hybrid car engine fuelled with gasoline and gaseous mixtures“ („Benziną ir dujų mišinius naudojančio hibridinio automobilio variklio efektyvumo tyrimas“) prepared at VILNIUS TECH by Tadas Vipartas. The dissertation was prepared in 2021–2026. Scientific consultant – Prof. Dr Alfredas Rimkus. The dissertation was defended at the public meeting of the Dissertation Defence Council of the Scientific Field of Transport Engineering in the Aula Doctoralis Meeting Hall of Vilnius Gediminas Technical University at 9 a.m. on 12 June 2026. This dissertation investigates the use of alternative fuels (natural gas and hydrogen) to increase the efficiency of a spark-ignition engine. The impact of different fuels and engine control algorithms on the combustion process and on energy and ecological indicators was determined and evaluated by analysing the emerging technological constraints within the context of a power-split (series-parallel) hybrid powertrain. The dissertation presents a review of scientific literature, analysing the directions for internal combustion engine improvement, the properties of gaseous fuels and the challenges of their application, along with the operating principles of automotive hybrid powertrains. Bench tests were conducted to investigate the effect of late intake valve closing timing on an engine operating on natural gas, and the influence of hydrogen additives on the combustion process and knock control. The numerical analysis of the engine’s combustion process was performed using AVL BOOST™ software, while the energy and ecological indicators of the hybrid vehicle were evaluated through experimental research and numerical simulation in the AVL CRUISE™ software. The following main results were obtained in the dissertation: retarding the intake valve closing timing increased the brake thermal efficiency and NOx emissions while reducing carbon dioxide emissions when the engine operates on natural gas. It was determined that a hydrogen additive in the fuel improves the engine’s energy indicators, but increases nitrogen oxides emissions and the risk of engine knock. Engine knock is effectively managed by retarding the ignition advance angle. Numerical simulation results confirmed that these trends persist during the Worldwide Harmonized Light-duty Vehicles Test Cycle: the use of hydrogen reduces fuel consumption and carbon dioxide emissions, but increases nitrogen oxides emissions. The dissertation results revealed the potential of these technologies and strategies for their application. The obtained data can be applied in the development and selection of advanced engine control algorithms and in the formulation of technologically sound environmental standards. Nine scientific articles have been published on the topic of the dissertation: six in scientific journals indexed in the Clarivate Analytics Web of Science database with an impact factor, one in a scientific journal indexed in the Clarivate Analytics Web of Science database without an impact factor, one in conference proceedings indexed in the Clarivate Analytics Web of Science Conference Proceedings Citation Index, and one in peer-reviewed conference proceedings not indexed in international databases. The research results were presented at three scientific conferences in Lithuania and Poland. Doctoral dissertation readers can search via VILNIUS TECH Virtual Library.

VILNIUS TECH Library invites students, academic staff, and researchers to take advantage of the KTU Press eBooks platform, a valuable resource for academic and scholarly literature. The platform provides access to peer-reviewed textbooks, monographs, course materials, and other academic publications across a wide range of disciplines, including technology, engineering, informatics, social sciences, humanities, physical sciences, and related fields. The KTU eBooks platform offers the following features: online reading and downloading of books for offline use; creation of personalized bookshelves; highlighting of text, note-taking, and bookmarking; full-text search within publications; automatic generation of citations and export of bibliographic data; printing of selected sections of publications in accordance with the publisher’s licensing terms. The platform is accessible on various devices, including computers, tablets, and smartphones. Its collection is continuously expanded with newly published KTU Press titles, ensuring convenient access to up-to-date academic and research literature. Access to the platform is available exclusively through the VILNIUS TECH network. Off-campus access is provided via the VPN service. To ensure secure remote access, users must authenticate using two-factor authentication , either through a mobile authentication application or by phone call verification.