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To determine the propagation characteristics in building for fifth-generation (5G) wireless communication, it is necessary to obtain the complex permittivities of the construction materials at millimeter wave (mmWave) band. Cloth materials are widely used in house, which have a great impact on the propagation of mmWave; however, their dielectric properties in mmWave band are rarely reported. In this communication, a new method for the estimation of the complex permittivities based on quantum-behaved particle swarm optimization (QPSO) algorithm and free-space measurement is proposed. Compared with classical particle swarm optimization (PSO) and chaos PSO (CPSO), QPSO is robust and efficient in searching the global optima. The complex permittivities of four cloth materials (linen, leatherette, polyester fiber, and latex mattress) are extracted from the measured transmission and reflection coefficients for perpendicular polarization over 40–50 GHz, and the accuracy is verified by comparing the calculated and measured reflection coefficients at other incident angles. The results presented in this communication are helpful for modeling the propagation of mmWave in indoor environment, and the proposed estimation method can serve as a good tool for the determination of dielectric properties of construction materials in wireless network planning. [ABSTRACT FROM AUTHOR]

During COVID-19 pandemic, wearing a mask has become a usual custom as a personal protection in every activity. The growth in consumption of face masks leads the increasing of mask waste and became a particular problem in environment. This study uses analytic hierarchy process (AHP) to determine appropriate material for making environmentally friendly non-medical mask. Filtration efficiency, breathability, and environmental impact index are defined as main criteria and carried out 26 alternative material from previous study. AHP presents a ranking of priority for all the alternative materials with Quilt and Cotton 600 TPI are the best values and fulfilled the material characteristics required by WHO. The sensitivity analysis generates some material with constant global priority results, such as Quilt, Cotton 600 TPI, Quilting cotton, Polycotton, and Polypropylene fabric 1. Quilting cotton with woven structure becomes the third ranking of alternative material, and Polypropylene fabric 1 is the worst material for making environmentally friendly non-medical mask. Selection for material alternative for environmentally friendly non-medical masks to reduce environmental impact caused by increasing mask waste during COVID-19 pandemic. Unlabelled Image • Increasing the consumption of masks during the pandemic of COVID 19 leads the mask waste and environmental problem. • Cloth mask as personal protection become a usual custom. • Various alternative material cloth properties for making non-medical masks. • Selection alternative material based on filtration efficiency, breathability, and environmental impact. • Environmentally friendly cloth material for mask to reduce the environmental impact from used masks. [ABSTRACT FROM AUTHOR]