Scientific journal: 

I am very pleased to present the newest issue of the Scientific Journal of Gdynia Maritime University. The quarterly, interdisciplinary journal has been published continuously for more than 40 years and it is a continuation of „Zeszyty Naukowe Akademii Morskiej w Gdyni”. The aim of the journal is to promote and disseminate the latest scientific achievements of maritime sector, including our university faculties’ researchers. Since January 2019 the journal has been published entirely in English. In the current issue, we publish results of latest research from the fields of commodity science, electrical engineering and automation presented in five articles. The section devoted to electrical engineering includes three articles. Two of them present problems of advancements in signal processing and related mathematical tools applied in modern telecommunication systems which are intensively explored in the last several years.

The first paper overviews development of integer factoring algorithms. It starts from the classical sieve of Eratosthenes, covers the Fermat algorithm and explains the quadratic sieve, which is a good representative of modern factoring algorithms. The second paper presents some basic operations like signal sampling, amplitude quantization and signal recovery from its samples, performed on signals in the digital signal processing as well as in the network calculus, all from the perspective of the operator theory. The next article in electrical engineering section presents simulation models of the tap changer controller working in a HV/MV station. The construction of all subsystems of the model, various methods of implementation of current compensation and the subsystems of the model have been discussed.

The articles on commodity science include results regarding influence of addition of vegetables to fruit yogurts on selected quality features of yogurts presented. The obtained results of study allowed to state that this supplement increases the content of extract and fat content in yogurt, which has a beneficial effect on the nutritional value of yogurts. The last article presents analysis of the storage stability of selected freeze-dried vegetables and fruit powders based on the characteristics of sorption properties.

I would like to take this opportunity to encourage authors representing different fields of research areas to publish their research in the Scientific Journal of Gdynia Maritime University. I also would like to thank all authors for their valuable impact in preparing this issue and Prof. PhD., D.Sc., Eng. Janusz Mindykowski who is its subject area editor.

Ireneusz Czarnowski

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