Induction contour hardening of gear wheels belongs to effective heat treatment technologies especially recommended for high-tech applications in machinery, automotive and aerospace industries. In comparison with long term, energy consuming conventional heat treatment (carburizing and consequent quenching), its main positive features are characterized by high total efficiency, short duration and relatively low energy consumption. However, modeling of the process is relatively complicated. The numerical model should contain both multi-physic and non-linear formulation of the problem. The paper concentrates on the modeling of rapid induction heating being the first stage of the contour induction hardening process which is the time consuming part of the computations. It is taken into consideration that critical temperatures and consequently the hardening temperature are dependent on the velocity of the induction heating. Numerical modeling of coupled non-linear electromagnetic and temperature fields are shortly presented. Investigations are provided for gear wheels made of a special quality steel AISI 300M. In order to evaluate the accuracy of the proposed approach, exemplary computations of the full induction contour hardening process are provided. The exemplary results are compared with the measurements and a satisfactory accordance between them is achieved.

The simplicity of solar flat plate air collector and freely availability of solar energy sources attracts attention to collector optimization. This study aims to evaluate the effect of double pass airflow on the performance of flat plate air collectors. Indirect type solar dryer performance characteristics analysis was done through CFD simulation with three different shapes (smooth, rough, and V-grooved) keeping the collector insulated and drying chamber act as a vertical chimney. The average thermal efficiency of the V-grooved surface, smooth surface, and rough surface is 90%, 78%, and 62% respectively. The total area of the collector is 1.20 * 2.0 = 2.60 m2 with the drying cabinet 1.20 * 0.65 * 1.00 m (width * depth * height) and 0.005m thick glass cover. Observed pressure drop at the inlet of the drying chamber is high in the case of smooth surface, medium in a rough surface, and low in a v-grooved plate that will allow enough gas pressure to pass through all the compartment of the process at full-scale. The air mass flow rate is the most important and effective factor during drying. The humidity of the air, as well as air velocity, is also an important factor for improving the drying rate.

A laser beam machine is a non-traditional manufacturing technique that uses thermal energy to cut nearly all types of materials. The quality of laser cutting is significantly affected by process parameters. The purpose of this study is to use a genetic algorithm (GA) in conjunction with response surface approaches to improve surface roughness in laser beam cutting CO2 with a continuous wave of SS 304 stainless steel. The effects of the machining parameters, such as cutting speed, nitrogen gas pressure, and focal point location, were investigated quantitatively and optimized. The tests were carried out using the Taguchi L9 orthogonal mesh approach. Analysis of variance, main effect plots, and 3D surface plots were used to evaluate the impact of cutting settings on surface roughness. A multi-objective genetic algorithm in MATLAB was used to achieve a minimum surface roughness of 0.93746 μm, with the input parameters being 2028.712 mm/m cutting speed, 11.389 bar nitrogen pressure, and a focal point position of - 2.499 mm. The optimum results of each method were compared, as the results the response surface approach is less promising than the genetic algorithm method.

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