New doctoral dissertation

VILNIUS TECH Library invites you to follow the published new dissertations. The dissertation „Development and Investigation of Nanometric-Resolution Piezoelectric Systems for Nanosatellites Operating under Varying Environmental Temperature Conditions“ prepared at VILNIUS TECH by Laurynas Šišovas. The doctoral dissertation was prepared at Vilnius Gediminas Technical University in 2021–2025. Supervisor – Assoc. Prof. Dr Sergejus Borodinas, consultant – Assoc. Prof. Dr Andrius Čeponis.

The dissertation was defended at the public meeting of the Dissertation Defence Council of the Scientific Field of Mechanical Engineering in the Aula Doctoralis Meeting Hall of Vilnius Gediminas Technical University at 10 a.m. on 13 April 2026.

The dissertation investigates the application of piezoelectric actuators in nanosatellites. The research object is piezoelectric actuation systems operating at nanometre-level precision under temperature variations, vibrations, and other conditions typical of nanosatellites. The main objective of the dissertation is to develop a nanometre-resolution piezoelectric inertial rotary actuator intended for nanosatellite subsystems and to study it numerically and experimentally. The study aims to evaluate the influence of temperature on the actuator’s electromechanical characteristics and its response to dynamic loads. To achieve the study’s aim, a set of consecutive tasks is carried out: a literature review is performed to identify the operating principles of piezoelectric systems and their applicability in space missions; a numerical model of the Low Earth Orbit thermal environment is developed to assess how electromechanical characteristics depend on nanosatellite temperature profiles; based on these results, a numerical model of a nanometre-resolution piezoelectric rotary actuator is created and its characteristics are determined; and finally, experimental investigations are conducted to evaluate the electromechanical characteristics of the developed prototype under temperature conditions typical for nanosatellites. The dissertation consists of an introduction, four chapters, general conclusions, and lists of the referenced literature and the author’s publications on the dissertation topic. The Introduction discusses the research problem, the relevance of the work, and the research object. It formulates the aim and tasks, describes the research methodology, presents the scientific novelty and practical value of the results, and states the defended propositions. The First Chapter provides a literature analysis related to nanometre-resolution piezoelectric systems and their applications in space missions. The chapter concludes with a summary and refinement of the dissertation objectives. The Second Chapter describes the design of the nanometre-resolution piezoelectric rotary actuator intended for nanosatellites, including its structural composition and the interrelationships among its components. The Third and Fourth Chapters present the numerical and experimental results of piezoelectric transducer investigations, followed by their analysis and generalisation. Three scientific articles have been published on the dissertation topic: two in journals indexed in the Clarivate Analytics Web of Science database and one in conference proceedings, also indexed in the database. A patent related to the dissertation topic has been registered at the Lithuanian Patent Office. Six conference presentations related to the dissertation were delivered in Lithuania and abroad.

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