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One of the recent applications of fabrics is to use them for sound insulation. Accordingly, due to their low production cost and low relative density, fabrics have drawn attention in some of the industries such as the automotive and aircraft industries. The present study is aimed to investigate the effects of the fiber cross-section, porosity, thickness of samples and fuzzing of the knitted fabric on the sound absorption coefficient.

In the present study, fabrics with three different stitch densities were knitted by yarns consist of three different forms of fiber cross-section shapes (circular, elliptical and plus-shaped). In this work, the sound absorption coefficient of knitted fabrics was investigated with regard to the different fiber cross-sections and structural parameters using an impedance tube.

As indicated by the obtained results, the cross-section, porosity, thickness and mass per unit area of the fabrics were the determinant factors for the sound absorption coefficient. In addition to, the sound absorption coefficient and porosity were shown to have an inverse relationship.

A section of the present paper has been allocated to the investigation of the effect of the fiber cross-section and fuzzing of fabric on the sound absorption of plain knitted fabrics.

The purpose of this paper is to: investigate coating of polylactic acid by TiO₂ using low-temperature plasma technique, which is a clean and environmentally benign process; study the characteristics of the obtained samples; and survey the antibacterial effect of nano-TiO₂. This method, as an eco-friendly technology used on the biodegradable polymer, would be benefited by industries which want to set feet on the greener path and reduce the social costs resulting from the harmful effects of pollutants.

TiO₂ was coated on a textile by DC magnetron sputtering. In this study titanium as a pure Ti anode is coated on the sample surface in the plasma reactor by entering argon gas (Ar). Then titanium oxide appears through entering oxygen (O₂) into the reactor.

Scanning electron microscopy analysis is applied to show the morphology of the coated surface. The quantitative value of TiO₂ was evaluated as weight percentage using X-ray fluorescence (XRF) and washing stability of the samples is measured using the XRF machine. The highest degree of antibacterial effects and washing stability are all observed in 10 min.

In this process, contrary to common methods, pure Ti is used for coating. Finishing of textiles via this method has been useful to be used as disposable hospital clothing due to its biodegradable and antibacterial properties. So it will be helpful in reducing negative environmental impacts.

The purpose of this paper is to investigate the three-dimensional natural convection and entropy generation in a cuboid enclosure filled with two immiscible fluids of nanofluid and air.

One surface of the enclosure is jagged and another one is smooth. The finite volume approach is applied for computation. There are two partially side heaters. Furthermore, the Navier–Stokes equations and entropy generation formulation are solved in the 3D form.

The effects of different governing parameters, such as the jagged surface (JR=0, 0.02, 0.04, 0.08, 0.12 and 0.16), Rayleigh number (10³⩽Ra⩽10⁶) and solid volume fraction of nanofluid (φ=1, 1.5, 2 vol%), on the fluid flow, temperature field, Nusselt number, volumetric entropy generation and Bejan number are presented, comprehensively. The results indicate that the average Nusselt number increases with the increase in the Rayleigh number and solid volume fraction of nanofluid. Moreover, the flow structure is significantly affected by the jagged surface.

The originality of this work is to analyze the natural-convection fluid flow and heat transfer under the influence of jagged surfaces of electrodes in high-current lead–acid batteries.