In this study, effects of alumina nanoparticles and stirring pass in mechanical behavior of friction stir welded AM magnesium alloy were studied. Microscopic analysis showed occurrence of dynamic recrystallization during plastic deformation in weld area and mechanical tests revealed optimum condition for hardness and tensile strength could be produced in rpm rotational speed not only in absence of reinforcing alumina nanoparticles but also in presence of them. Opposing effects of higher temperatures in grain growth and greater strains in lowering grain size should be considered. In lacking of alumina nanoparticles, grain size diminished with increasing stirring pass but in being nanoparticles, predominant mechanism in depressing grain size came from nanoparticles and negligible effect of stirring pass in grain size was found. XRD results showed increasing solubility of γ,-Mg phase as a result of stirring operation. Better toughness performance of weldment was produced via decreasing size of agglomerated alumina particles. Higher hardness and greater ultimate tensile strength were achieved in specimens with alumina nanoparticle with increasing rotational speed. In a constant rotational speed, higher hardness and greater ultimate tensile strength achieved in samples having alumina nanoparticles in contrast with free alumina nanoparticle samples.

The purpose of the present study is to produce biodiesel from fish-waste oil and methanol by combining mechanical stirring and microwave as a technique to accelerate this process. In this research, a microwave system was used including microwave source, stirrer, spiral tube and decanter. With the help of this system, the effects of multiple parameters on the conversion of fatty acid to methyl ester is investigated. These parameters include molar ratio of alcohol to oil (4 to 1, 6 to 1 and 8 to 1), catalyst concentration (0.5, 1 and 1.5 weight percent of oil), reaction time (5, 15 and 25 min) and microwave time (0.5, 1.5 and 2.5 min). Analyzing the obtained results is performed using the response surface method and Box Behnken layout in Design Expert 10.0 software. After analyzing the data and optimizing the biodiesel production reaction, the highest percentage of biodiesel conversion (92.62%) was found in the catalyst concentration of 1.13%, the reaction time of 24.61 minutes, the molar ratio of alcohol to oil of 5.55 and the microwave time of 0.5 minute. The regression model between independent variables and dependent variable (percent conversion) was obtained as a quadratic equation with R2=0.9953.

The continuous improvement of EAF performance is crucial for the increase in productivity and cost effectiveness and to render an environmental friendly process. RHI supports these targets by providing a diverse range of refractory and process solutions. Chemical energy in practical operation by injection of gaseous media like oxygen and natural gas, and solid materials like carbon have become a state of the art solutions for process improvement today. To understand the phenomena of the benefits, RHI has developed a mass and energy balance model. The objective of the model is to focus on the replacement ratio of electrical energy by chemical energy and the consequences for the overall CO2 emission of the process. CO2 emission certificate trading can become a new source for cash generation to be utilized for improvement investment budgets.Another valuable solution to decrease the energy consumption and the CO2 generation of the process is bottom purging in EAF. This technology can be introduced by the use of the directional porosity plug (DPP). The benefit of stirring in the furnace is that it enhances the interface reactions between the slag and the bath and homogenizes the liquid volume in the furnace. This results in achieving better operation parameters in terms of less power consumption and power-on time. Again a benefit in cost and a reduction in carbon dioxide emissions can obviously be attained.This paper shows the savings potential of the replacement of electrical energy by chemical energy by using the mentioned balance model. The benefit of the introduction of the DPP system is shown on the results of various steel plants.