The paper presents the results of computational evaluation of the hull-propeller interaction coefficients, also referred to propulsive coefficients, based on the unsteady RANS flow model. To obtain the propulsive coefficients, the ship resistance, the open-water characteristics of the propeller, and the flow past the hull with working propeller were computed. For numerical evaluation of propeller open-water characteristics, the rotating reference frame approach was used, while for self-propulsion simulation, the rigid body motion method was applied. The rotating propeller was modelled with the sliding mesh technique. The dynamic sinkage and trim of the vessel were considered. The free surface effects were included by employing the volume of fluid method (VOF) for multi-phase flows. The self-propulsion point was obtained by performing two runs at constant speed with different revolutions. The well-known Japan Bulk Carrier (JBC) test cases were used to verify and validate the accuracy of the case studies. The solver used in the study was the commercial package Star-CCM+ from SIEMENS.
ICP-MS method was optimized for the simultaneous analysis of 16 metals (Pb, Cd, As, Hg, Sn, Sb, Co, Ni, Cr, Mn, Mo, Se, Cu, Fe, Zn , Al) in types of medicinal herbs commonly used to produce functional foods. The conditions of samples digestion in a closed system using a microwave and an opened system in Kjeldahl method have been studied in order to flexibly apply different methods of sample preparation in practice. The method was validated with parameters such as calibration curve, limit of detection, limit of quantitation, repeatability RSDr % (0.98 - 19.7%), reproducibility RSDR% (2.72 - 23.5%) and recovery R% (80.3 -109%) meeting the AOAC performance requirements. The method was applied to determine heavy metals in 40 samples of medicinal herbs of apart from the risk of pollution with some toxic heavy metals such as lead and cadmium in medicinal herbs.
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