Jacek Pietraszek

This paper describes a part of research related to the elimination of adverse phenomenon involving the occurrence of a negative oxygen balance of combustion products of missile engines during their firing from aircrafts. It also presents the results of comparative tests of rocket engines equipped with an additional oxidizer charge.

The paper presents a study on microstructure and microhardness changes obtained in the spun carbon steel tube after shaping by a laser beam. The surface of a pipe was machined circumferentially using a 1500 W CO2 laser beam at various diameters (distance from the focus). As a result, plastic deformations such as convex and narrowing shape changes were observed. The conducted research, including microhardness measurements, shows that, in comparison to the unprocessed material, the microstructure was significantly changed, both in the convex and narrowed layer.

Kształtowanie laserowe rur stalowych

Streszczenie

W pracy przedstawiono badania zmian mikrostruktury i mikrotwardości warstwy wierzchniej wyoblonej i przewężonej rury ze stali węglowej po laserowym kształtowaniu. Powierzchnia rury była skanowana po obwodzie wiązką lasera CO2 o mocy 1500 W przy różnych średnicach (odległościach od ogniska). W efekcie uzyskano odkształcenia plastyczne, takie jak wyoblenie i przewężenie rury. Przeprowadzone badania, w tym pomiary mikrotwardości, wykazują, że mikrostruktura uległa istotnej zmianie w stosunku do materiału rodzimego, zarówno w warstwie wyoblonej, jak i przewężonej. 

W artykule badano wpływ obróbki laserowej na właściwości powłok nanoszonych elektroiskrowo. Ocenę właściwości powłok po obróbce laserowej przeprowadzono na podstawie obserwacji mikrostruktury, analizy składu fazowego oraz pomiarów struktury geometrycznej powierzchni i mikrotwardości. Badania przeprowadzono, wykorzystując elektrody WC-Cu, które zostały wytworzone przez spiekanie nanostrukturalnych proszków. Do nanoszenia powłok elektroiskrowych użyto urządzenie model EIL-8A. Obróbkę laserową nałożonych powłok elektroiskrowych wykonano laserem Nd:YAG, model BLS 720.

The paper is concerned with the performance properties of electro-spark deposited coatings. The properties were assessed by analyzing the coating microstructure, X-ray diffraction, microgeometry, microhardness, and corrosion tests. The studies were conducted using WC-Co-Al2O3 electrodes produced by the sintering of powders. The anti-wear coatings were electrospark deposited over C45 carbon steel by means of an EIL-8A. These coatings are likely to be applied in sliding friction pairs and as protective coatings.

The estimation of a variance for a semi-parametric neural network model variance for geometric properties of sintered metal will be done on the basis of jackknife subsampling method. Calculation results are of great practical significance because it will be possible to use proposed approach in similar microscale modelling. The proposed approach is simple and has many advantages if model identification procedure is computational expensive.

Shainin’s approach is a specific sequential heuristic aimed at finding and ranking the most important factors which impact the investigated process. The sequential aspect of the approach is simultaneously its strongest and weakest side, because just after detection of the most important factor, the further analysis is stopped without any additional cost. However, such a detection may take place at the end of the whole sequence. This paper tries to answer the question if the dominant factor may be hidden by interactions with other factors.

The well-known statistical tests have been developed on the basis of many additional assumptions, among which the normality of a data source distribution is one of the most important. The outcome of a test is a p-value which may is interpreted as an estimation of a risk for a false negative decision i.e. it is an answer to the question “how much do I risk if I deny?”. This risk estimation is a base for a decision (after comparing with a significance level α): reject or not. This sharp trigger – p-level greater than α or not – ignores the fact that a context is rather smooth and evolves from “may be” through “rather not” to “certainly not”. An alternative option for such assessments is proposed by a fuzzy statistics, particularly by Buckley’s approach. The fuzzy approach introduces a better scale for expressing decision uncertainty. This paper compares three approaches: a classic one based on a normality assumption, Buckley’s theoretical one and a bootstrap-based one

The paper summarizes the quantity assessment of GPU processing and supporting CUDA technology on the efficiency of BLENDER rendering program.