Effect of filtration on the morphology and mechanical properties of Mg molten alloy entering the mould cavity

In this research, the experiments were carried out in two methods. In the first, the foam filter has been placed at the gate or runner of the mould, and in the second, no filter was used. In both methods, the casting temperatures were 680 °C and 750 °C. A pyrex glass plate was used on one side of the mould cavity in order to evaluate the morphological behaviour of entering melt into the cavity. The height of filtered molten Mg–Al–Zn alloy in mould was increased step-by-step with the filling time. This showed that the filtered molten alloy flows in mould cavity with different velocities. In case of no filtered molten alloy this was not observed. The reliability of the results of bending tests has been evaluated by Weibull analysis. The filters had absorbed the inclusions very well. A fracture toughness of 260 MPa was obtained in specimen poured at 680 °C with ceramic filters. The Weibull plots showed that the castings filtered at the gate at temperature of 680 °C had the best reliability.     

Effects of Fe2O3 Nanoparticles on Water Permeability and Strength Assessments of High Strength Self-Compacting Concrete

In this work,compressive,flexural and split tensile strength together with coefficient of water absorption of high performance self-compacting concrete containing different amount of Fe2O3 nanoparticles have been investigated.The strength and the water permeability of the specimens have been improved by adding Fe2O3 nanoparticles in the cement paste up to 4.0 wt%.Fe2O3 nanoparticle as a foreign nucleation site could accelerate C-S-H gel formation as a result of increased crystalline Ca(OH)2 amount especially at the early age of hydration and hence increase the strength of the specimens.In addition,Fe2O3 nanoparticles are able to act as nanofillers and recover the pore structure of the specimens by decreasing harmful pores to improve the water permeability.Several empirical relations have been presented to predict the flexural and the split tensile strength of the specimens by means of the corresponding compressive strength at a certain age of curing.Accelerated peak appearance in conduction calorimetry tests,more weight loss in thermogravimetric analysis and more rapid appearance of peaks related to hydrated products in X-ray diffraction results indicate that Fe2O3 nanoparticles up to 4 wt% could improve the mechanical and the physical properties of the specimens.     

Optimization of proteases pretreatment on natural dyeing of wool using response surface methodology

Natural dyes and enzymes have attracted a lot of attention due to their non-hazardous nature. In this research, wool fabrics were pretreated with the commercial protease at different concentrations over various times. The dyeing process was then carried out on the treated fabrics with the commercial madder and cochineal. Also, the central composite design analysis was used to design the relation between dye exhaustion and some properties of dyed wool including tensile strength, alkaline solubility, water drop absorption, and weight loss based on Design of Expert software. The response surface methodology was also applied to find the optimum conditions for the wool fabric pretreatment. The scanning electron microscopy was employed to indicate the influences of proteases on the fabric surface. The optimized proteases pretreatment on the wool surfaces has considerably improved the absorption of madder and cochineal and minimized the damage to appropriate physical properties. The adsorption kinetic of madder and cochineal on enzymatic wool fiber was fitted with a pseudo-second-order model. The rate of dyeing at different temperatures, as well as the values of standard affinity, entropy, and enthalpy, was calculated. The activation energy of dyeing with madder and cochineal at different temperatures are 23.79 and 30.96 kJ/mol, respectively, considering that these values are in the typical activation energy for physisorption. It was also found that wash, light, wet and dry rub fastness properties of the samples dyed along with protease have not changed significantly. This can be easily scaled up in the industry as a simple method using the commercial materials.     

Analysis of Thermal Nonequilibrium Inverse Heat Transfer in a Porous Channel

This article is concerned with the one-dimensional transient inverse heat conduction between two parallel plates filled with a porous medium under a nonthermal equilibrium condition between the solid and the fluid phases. The estimation of transient heat flux using the conjugate gradient method (CGM) along with the differential adjoint equations has been carried out under nonthermal equilibrium conditions between two phases. Derivation of the adjoint differential equations in the case of nonthermal equilibrium and calculation of gradient function from coupled adjoint equations are presented in detail here. The transient wall heat flux imposed on the porous boundary is estimated using the aforementioned method, and results show that sensor locations and existing error in the measured data have important effects on the calculated heat flux. Nonetheless, accurate heat flux estimation is quite achievable.