The candidate started his PhD studies in 2021 and from the beginning showed a clear interest in defining a structured study plan covering individual research steps, expected publication outputs and an international internship. The plan was followed successfully throughout the study and most modifications represented positive developments, such as completing additional research stays beyond the original plan. The candidate approached his work actively and responsibly. Communication was frequent and productive. He regularly proposed his own ideas, interpretations and directions for further work. Overall, the candidate demonstrated a high level of commitment and responsibility throughout the PhD study.

The candidate demonstrated a high level of independence throughout the PhD study. He proposed experimental approaches, prepared testing procedures and performed experiments independently. The evaluation of results and preparation of scientific manuscripts required only limited supervision. His very good English skills significantly accelerated manuscript preparation and simplified both internal and external review processes. He was also able to present the obtained results at leading international conferences and discuss them with experts from academia and industry. Besides activities directly related to the dissertation, the candidate actively participated in several research projects. Some of these projects were closely related to the thesis topic, while others addressed different tribological problems. The candidate was also significantly involved in the development of a testing methodology for top-of-rail products. This methodology is currently routinely used within the research group, not only for internal research activities but also in cooperation with industrial partners. Through these activities, the candidate demonstrated a high level of responsibility, technical competence and the ability to work independently.

The thesis addresses an important knowledge gap related to the performance of top-of-rail products under contaminated conditions. Although these products have been used in railway practice for many years, their interaction with environmental contaminants has not been systematically studied. The candidate focused on the influence of contamination, particularly water, on the frictional performance of top-of-rail products, as well as the effects of contamination on wear and rolling contact fatigue. The research activities at Brno University of Technology focused on frictional performance, while wear and rolling contact fatigue were studied during his stays at Southwest Jiaotong University, where he broadened his expertise in wheel-rail tribology. Based on the results of the thesis, general recommendations for the application and operation of top-of-rail products under different contamination conditions were proposed. The candidate also contributed to the development of testing methodologies that are currently used for the evaluation of top-of-rail products. The results of the thesis were published in three first-author journal papers and one co-authored paper. The papers were published in leading tribology journals, including Wear, Tribology International and Tribology Letters. My only comment regarding the presented work is that part of the results could have been further validated under field conditions or using a full-scale testing approach. Nevertheless, the overall scientific contribution of the thesis is significant and the obtained findings have both scientific and practical relevance.

PhD thesis is an independent scientific work that presents a novel solution to a significant problem in the research area and demonstrates the candidate’s ability to conduct independent research.

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