The influence of plasma nitriding on the microstructure of X153CrMoV12 and X165CrV12 steels

This study presents the results of research into the influence of the time of the plasma nitriding process on the microstructure of the coatings obtained on cold-work tool steels X153CrMoV12 and X165CrV12. The processes were carried out under industrial conditions using an Ionit system (Oerlikon Metaplas) with variable process times of 2, 4 and 6 hours. Nitriding mixture consisting of 5 % nitrogen and 95 % hydrogen was chosen, which allowed the expected diffusion layer to be obtained without a white layer (composed of iron nitrides). Analysis of relative elemental concentrations indicates that the presence and content of nitride-forming elements influences the formation of alloy additive nitrides in the microstructure of the diffusion layer. Nitrides of alloying additives, present in the diffusion layer, indicating that investigated steels are the most suitable for plasma nitriding

DEMATEL-based multi-criteria evaluation of public transportation systems for Cracow

Praca poświęcona jest wieloatrybutowej ocenie perspektywicznych wariantów systemu transportowego dla miasta Krakowa i jego regionu. Rozpatrzono 4 warianty pozwalające na usprawnienie obecnie funkcjonującego, nieefektywnego systemu komunikacyjnego. Istotnym atutem pracy jest wykorzystanie w tym celu interesującej, lecz stosunkowo słabo znanej i wykorzystywanej na świecie metody DEMATEL (ang. DEcision MAking Trial and Evaluation Laboratory). Jej wykorzystanie pozwala pogłębić wyniki oryginalnej analizy, przeprowadzonej przy użyciu metody AHP/ANP.Multi-criteria evaluation of perspective public transportation systems for the city of Cracow and Cracow agglomeration is dealt with in the paper. Four distinct system alternatives are included. A little known multi-criteria decision analysis method, namely extended DEMATEL is applied with this regard. Its utilisation makes validation of outcomes of original AHP-based analysis of the same problem possible. It also extends analysis results providing decision maker with additional information with regard to relations between considered decision making alternatives

Distant Measurement of Plethysmographic Signal in Various Lighting Conditions Using Configurable Frame-Rate Camera

Videoplethysmography is currently recognized as a promising noninvasive heart rate measurement method advantageous for ubiquitous monitoring of humans in natural living conditions. Although the method is considered for application in several areas including telemedicine, sports and assisted living, its dependence on lighting conditions and camera performance is still not investigated enough. In this paper we report on research of various image acquisition aspects including the lighting spectrum, frame rate and compression. In the experimental part, we recorded five video sequences in various lighting conditions (fluorescent artificial light, dim daylight, infrared light, incandescent light bulb) using a programmable frame rate camera and a pulse oximeter as the reference. For a video sequence-based heart rate measurement we implemented a pulse detection algorithm based on the power spectral density, estimated using Welch’s technique. The results showed that lighting conditions and selected video camera settings including compression and the sampling frequency influence the heart rate detection accuracy. The average heart rate error also varies from 0.35 beats per minute (bpm) for fluorescent light to 6.6 bpm for dim daylight

Corrosion behaviour of polished and sandblasted titanium alloys in PBS solution

In this work, we performed comparative studies of the effect of surface preparation of Ti6Al4V and Ti6Al7Nb biomedical alloys and the influence of endothelial cells on their corrosion behaviour in PBS (Phosphate Buffered Saline). Two different methods of surface modification were applied – polishing and sandblasting. The polished Ti6Al7Nb alloy was found to have the best resistance against general corrosion in PBS. It was characterized by the lowest corrosion rate, the widest passive range and the lowest reactivity. Both alloys prepared by sandblasting exhibited worse corrosion properties in comparison to the polished ones. This can be associated with a greater development of their surface and the presence of Al2O3 grains which caused an increase of corrosion potential but might also influence the weakening of the passive layer. Results of potentiodynamic anodic polarization indicated that more resistant to pitting corrosion was Ti6Al7Nb alloy regardless of the method of surface preparation. In those cases, anodic polarization caused only an increase of passive layer, while in the case of sandblasted Ti6Al4V alloy it caused a pitting corrosion. The results obtained allowed us to conclude that the niobium-titanium alloys had higher corrosion resistance than titanium alloys with vanadium. Moreover, it was stated that endothelial cells improved the corrosion resistance of all the titanium alloys examined