By increasing the application of smart wearables, their electrical energy supply has drawn great attention in the past decade. Sources such as the human body and its motion can produce electrical power as renewable energy using piezoelectric yarns. During the last decade, the development of the piezoelectric fibers used in smart clothes has increased for energy-harvesting applications. Therefore, the energy harvesting from piezoelectric yarns and saving process is an important subject. For this purpose, a new control system was developed based on the combination of the sliding mode and particle swarm optimization (PSO). Using this method, due to the piezoelectric yarn cyclic deformation process, electrical power is produced. This power is considered the input voltage to the controlling system modeled in this article. This system supplies constant voltage to be saved in a battery. The battery supplies power for the electrical elements of smart fabric structure for different applications, such as health care. It is shown that the presence of PSO led to the improvement of system response and error reduction by more than 30%.
PurposeIn this article, the authors intended to analyze the shielding properties of a fabric frequency selective surface (FSS) structure to the basis of substrate fabric properties. For this purpose, the effect of the properties and structural parameters of the substrate fabric layer were analyzed on the shielding properties of the developed FSS.Design/methodology/approachThe experimental and theoretical evaluations were done at the frequency band of 1,805–1,880 MHz and computer simulation technology (CST) was used in modeling. In experiments were developed the FSS structures by different fabrics as the substrate layers and the copper as the patch cells. The shielding properties of these samples were measured experimentally by the developed setup.FindingsConfirming resonant frequencies, transmission coefficients, and the bandwidths results obtained from modeling and experiments show that the thickness, weight and interweaving structure parameters were affect the porosity of the substrate fabric. Porosity of the fabric moves the resonant frequency due to the changing of the dielectric properties of the fabric. Therefore, shielding properties of the FSS structure were affected by these parameters as the important characteristics of the substrate fabric. In addition, shielding properties of the samples (resonant frequencies and transmission coefficients) in different incident angles are not same in two modes of transverse electric and transfer magnetic.Originality/valueThe experimental results suggest that the introduced flexible FSS structures are suitable for shielding applications in the proposed frequency band.
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