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The current issue of the Scientific Journal of Gdynia Maritime University contains publications on a variety of subjects, covering issues from several different scientific disciplines, including: mechanical engineering, automation, electronics and electrotechnology, as well as management and quality sciences.

The paper “Comparison of calculating algorithms of logarithmic decrements applied for welded joints assessment” addresses the subject of vibrodiagnostic tests used for assessing the quality of welded joints between dissimilar materials. The authors assessed different algorithms related to the approximation of logarithmic decrement calculations. Based on model studies they conclude that the most advantageous approximation method is a 4th degree polynomial.

The paper “The influence of TIG welding technology on the properties and quality of joints made of dissimilar steels” presents the technology of dissimilar boiler steel welding, as developed by the authors. One welded material was
a medium-carbon non-alloy steel (ASTM A106), the other alloy steel (13CrMo 4-5). The materials were joined using method 141 (TIG). The welding process was used to prepare samples, which were then subjected to the following non-destructive tests: visual observation, penetration and radiographic. The tests demonstrated that the resulting weld achieved quality class B.

The publication “Speed variations of cage induction motors under sinusoidal voltage modulation” concerns numerical calculations using the finite element method and assessment of the impact of phase angles on subharmonic and interharmonic components of electric currents on changes in speed of a 3 kW rated power inductive cage motor. The parameters of the model were identified based on the engine structural data and experimental results. The test results should contribute to a better understanding of the phenomena occurring in asynchronous motors affected by power voltage fluctuations, in particular under fluctuation frequencies matching the natural frequency of the torsional free vibrations of the rotating mass.

The paper “High-speed binary-to-residue converter design using 2-bit segmentation of the input word” proposes a new approach to designing fast binary converters, which enable attaining high pipelining speeds at the FA level. This is achieved by segmenting input words into 2-bit segments. The segmentation procedure is described in detail and illustrated with appropriate examples.

The purpose of the study “Examination of authenticity of selected dark chocolates” was to use cocoa shell determination to test the authenticity of dark chocolates available on Polish and other European markets. The experiments demonstrated that all the tested chocolates met the requirements of the Directive of the European Parliament no. 2000/36/CE and contained no more that 5% of cocoa shells. In the authors’ opinion, the information value of chocolate packagings is insufficient. For example, they lack information on the geographical origin of the cocoa grains and the grain variety used to produce the particular chocolate. It was also observed that the colour of the test chocolates did not depend on the fat content.

The authors of the paper “The phenomenon of food waste among consumers of generations X, Y and Z” conducted a survey study among people from three age groups: aged 60 and over, 31-59, and 18-30. The study concerned the handling of unused food products. It was shown that generational differences differentiate approaches to food wastage. It was found that the low level of knowledge on food waste among the youngest generation translates into their everyday behaviour. Almost half the respondents from this generation (45.5%) throw unconsumed food away. Attempts to use (process) unconsumed food were made primarily by older people.

The paper “The consumer versus innovative dairy products” concerns consumer opinions on dairy products. The study was conducted using the CAWI survey method and an original survey form. The study demonstrated that consumers consume dairy products frequently and consider them an important part of their diets. When buying innovative products, they mainly followed the health impact of those products, positive opinions and attractive prices, while promotion and advertisement were the least important. The survey results led to the conclusion that consumers are open to innovation on the dairy product market, but they have specific expectations towards them in terms of their composition, health benefits, price and packaging.

Robert Starosta