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.
This paper presents a verification of the performance of the stormwater drainage system in Gaj and Tarnogaj residential developments in Wrocław with regard to climate changes, by means of a calibrated hydrodynamic model created within the SWMM software. The verification was carried out for two criterial rainfalls: the Euler model rainfall with occurrence frequency C = 3 years and an actual rainfall with C = 5 years. Two parameters: degree of flooding (DOF) and specific flood volume (SFV) were adopted to indicate potential system overloads. The simulations showed numerous outflows from the sewers, which means, that the investigated system needs adapting to climate changes. The causes of this should be sought in the too small diameters of the sewers and so in the insufficient hydraulic capacity of the sewerage system dimensioned in the past using methods which are inadequate today.
Standards for the dimensioning and assessment of reliable operations of area drainage systems under conditions of climate change Standardy wymiarowania i oceny niezawodności działania systemów odwodnień terenów w warunkach zmian klimatu Abstract Contemporary area drainage dimensioning standards are presented in this paper. Hazards for drainage systems arising from climate changes are discussed and trends of changes in the precipitation structure are presented using the example of data obtained from Wrocław. The need for changes within precipitation scenarios is indicated for modelling overflow in channels and a research methodology and assessment criteria of the degree of reliability of the drainage system are proposed. Results are presented of an analysis of the operation of the rainwater drainage system in the Gaj and Tarnogaj housing estates in Wrocław -these were conducted using a calibrated hydrodynamic model in SWMM software. It was proved that the examined system does not meet the standards of PN-EN 752:2008, DWA-A 118:2006 and Merkblatt no. 4.3/3:2009 with regard to instances of flooding from channels and that adaptation to climate change is required.
Abstract. On the basis of field studies of canalized storm water catchment of Gaj and Tarnogaj estate in Wrocław the rules of construction of hydrodynamic models in SWMM program were presented. The process of identification of hydrological and hydraulic parameters of the model, in the course of its calibration and validation were presented. To assess the quality of model the rates and statistical criteria were proposed to compare the results of stream simulation and volume of runoff of effective precipitation with the results of the measurements.
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