Modeling the reliability of storm water drainage systems encounters a number of methodological difficulties, especially in the selection of a reliable rainfall scenario. Many methods for creating reference hyetographs are described in the literature. The aim of the work was the analysis of the shapes of local precipitation hyetographs and the verification of the reference shapes of rainfall hyetographs used for the drainage systems designing and modeling its operation in Poland (Euler type II and DVWK models). The research material was represented by historical records of rainfall data from the measuring station located in Jelenia Góra (Poland). Rainfall were grouped due to the similarity of physical features, using various methodologies: Huff, cluster analysis using the Ward and k-means methods. The k-means method proved to be especially useful for selecting precipitation in terms of shape hyetographs. The statistical analysis of the similarity of the rainfall hyetograph shapes was performed within the separated genetic clusters, based on the parameters of mass distributions and unevenness over time. The comparative analysis allowed for the positive verification of the Euler type II and DVWK models for the tested station.
In this work, the tungsten carbide reinforcement in cobalt matrix (WC-Co-Cr) coatings was studied. The deposition process was carried out by high-velocity oxy-fuel spraying (HVOF). The study aimed to investigate the influence of one of the key process parameters, namely spray distance, on the coatings’ microstructure and phase composition, as well as their mechanical and tribological properties. The manufactured coatings were analysed by scanning electron microscopy, X-ray diffraction (XRD), instrumented indentation test, pull-off adhesion test and ball-on-disc method. The results revealed that selection of proper spray distance caused a high index of carbide retention (ICR) amounting to 0.95, which promoted higher hardness and better wear resistance. Instrumental microhardness was in the range of 14.2–14.8 GPa, whereas the Young modulus exhibited values from 336 GPa up to 342 GPa. The bond strength of deposited coatings was in the range of 55–65 MPa. Wear factor values were in the range of 73–81 × 10−7 mm3/(N · m) and the friction coefficient was about 0.4. The dominant wear mechanism is abrasion and adhesive mode supported by the fatigue-induced material delamination.
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