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Number of results: 11
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Abstract

The mathematical model and numerical simulations of the solidification of a cylindrical shaped casting, which take into account the process of filling the mould cavity by liquid metal and feeding the casting through the riser during its solidification, are presented in the paper. Mutual dependence of thermal and flow phenomena were taken into account because have an essential influence on solidification process. The effect of the riser shape on the effectiveness of feeding of the solidifying casting was determined. In order to obtain the casting without shrinkage defects, an appropriate selection of riser shape was made, which is important for foundry practice. Numerical calculations of the solidification process of system consisting of the casting and the conical or cylindrical riser were carried out. The velocity fields have been obtained from the solution of momentum equations and continuity equation, while temperature fields from solving the equation of heat conductivity containing the convection term. Changes in thermo-physical parameters as a function of temperature were considered. The finite element method (FEM) was used to solve the problem.
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Abstract

The aim of the study was to compare anaesthesia protocol utilizing combination ketamine/ medetomidine with epidural lidocaine or morphine to orthopaedic surgery in rabbits. All rabbits received intramuscularly medetomidine (0.5 mg/kg) and ketamine (20 mg/kg). In group L (n=13) epidural injection was performed with lidocaine (3 mg/kg) and in group M (n=13) with morphine (0.1 mg/kg) diluted with sterile saline to 0.6 ml. Rabbits underwent bilateral mosaicplasty surgery. Heart rate (HR), systolic (SBP), diastolic (DBP) and mean arterial blood pressure (MAP), arte- rial oxygen saturation (SpO2) and respiratory rate (RR) were measured every 5 minute during surgical procedure. Duration of sensory blockade was measured based on toe pinch reflex and recorded. Hemodynamic parameters were comparable at baseline in both groups. We did not observe significant differences in HR, RR, SBP, DBP, MAP between group L and M. Intragroup statistical analysis revealed differences at different time points in group M in terms of HR, SBP, DBP, MAP. In rabbits in group M blood pressure dropped while HR increased over time. In both groups a decrease in SpO2 was observed. Mean duration of loss of the toe pinch reflex was similar between group L and M, and amounted to 72.79±34.48 and 82.80±17.85 minutes, respectively.
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Abstract

In this paper, the mathematical model and numerical simulations of the molten steel flow by the submerged entry nozzle and the filling process of the continuous casting mould cavity are presented. In the mathematical model, the temperature fields were obtained by solving the energy equation, while the velocity fields were calculated by solving the momentum equations and the continuity equation. These equations contain the turbulent viscosity which is found by solving two additional transport equations for the turbulent kinetic energy and its rate of dissipation. In the numerical simulations, coupling of the thermal and fluid flow phenomena by changes in the thermophysical parameters of alloy depending on the temperature has been taken into consideration. This problem (2D) was solved by using the finite element method. Numerical simulations of filling the continuous casting mould cavity were performed for two variants of liquid metal pouring. The effect of the cases of pouring the continuous casting mould on the velocity fields and the solid phase growth kinetics in the process of filling the continuous casting mould was evaluated as these magnitudes have an influence on the high quality of the continuous cast steel slab.
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