Mating electrodes made of copper alloys are commonly used for welding galvanized steel sheets used in the production of car bodies. These alloys are characterized by high mechanical properties, a high level of electrical and thermal conductivity as well as the stability of these properties under changing conditions of current, thermal and mechanical load. Much careful attention was paid to the essence of the ongoing structural changes as well as to the mechanical properties in the welding process (RSW – Resistant Spot Welding) of steel sheets, including high-strength ones. There is a lack of research on structural changes and the related mechanical properties occurring in welding electrodes made of copper alloys caused by the welding process.
This study is devoted to these issues and contains a critical review of the research results enabling a better understanding of the relationships between the structure and properties of welding electrodes caused by the cyclic welding process. In order to illustrate the phenomena occurring during the welding process, both in the material to be welded and in the tip electrodes, hardness and structural tests were carried out on electrode samples before and after their exploitation. The data collected in the article supplements a certain lack of information in the literature regarding the microstructural aspects of the welding process of galvanized steel sheets for the production of car bodies. The conducted research may be the starting point for the search for more effective materials for the tip electrodes.

The aim of the study was to develop a method of laparoscopic embryo transfer in pigs and to compare different variants of this method. Two catheter diameters (1.6 mm and 1.0 mm), the method and site of embryo deposition (oviduct or uterus), the embryo development stage (2 – 4 cell or blastocyst), the method for oviduct or uterus stabilization, the potential for cryopreserved embryo transfer, the developmental potential of the embryos after transfer to the oviduct, patomorphology of the oviduct after transfer and possible clinical complications were taken into consideration. Two studies compared two variants of transfer to the uterus, and five variants of transfer to the fallopian tube. The transfer of embryos by the infundibulum may be of limited use due to handling problems and very low efficiency (pregnancy was not achieved). Very low efficiency was shown after transfer of vitrified embryos. Transfer to the fallopian tube by puncture of the fallopian tube, regardless of the developmental stage of the embryo, is the recommended method of embryo transfer. The histopathological examination of the fallopian tube revealed possible changes within the puncture site. The numerous clinical complications observed did not affect the effectiveness of the method.

Analysis of granulation kinetics was carried out using a laboratory disc granulator with a diameter D of 0.5 m. A liquid binder was delivered to the tumbling bed at a constant flow rate with a nozzle generating droplets with a size of approx. 4-5 mm. Fine-grained chalk was used as a model of raw material and water or disaccharide solution with concentrations of 20 - 40% as a wetting liquid. Different times of droplet delivery ranging from 2 to 6 min were utilized. Granulometric composition of the bed for selected lengths of process, bed moisture and the moisture of individual size-fractions were assessed. Mass of granulated material, which was transferred from nuclei fraction to other size fractions was determined on the basis of mass balance analysis and the assessment of liquid migration between fractions. The influence of disaccharide concentration in wetting liquid on the aforementioned phenomena was also examined.

The quality of the supplied power by electricity utilities is regulated and of concern to the end user. Power quality disturbances include interruptions, sags, swells, transients and harmonic distortion. The instruments used to measure these disturbances have to satisfy minimum requirements set by international standards. In this paper, an analysis of multi-harmonic least-squares fitting algorithms applied to total harmonic distortion (THD) estimation is presented. The results from the different least-squares algorithms are compared with the results from the discrete Fourier transform (DFT) algorithm. The algorithms are assessed in the different testing states required by the standards.