Abstract In this work is presented a hybrid bioinspired optimization technique that associates a General Regression Neural Network (GRNN) with the Multiobjective Bat Algorithm (MOBA), for the design and synthesis of the Frequency Selective Surfaces (FSS), aiming its application in data communication systems by diffusion of millimeter waves, specifically, in the IEEE 802.15.3c standard. The designed device consists of planar arrangements of metallizations (patches), diamond-shaped, arranged over a RO4003 substrate. The FSS proposed in this study presents an operation with ultra-wide band characteristics, its patch designed to cover the range of 40.0 GHz at 70.0 GHz, i.e., 30.0 GHz bandwidth and 60.0 GHz resonance. The upper and lower cutoff frequencies, referring to the transmission coefficient's scattering matrix (dB), were obtained at the cutoff threshold at −10dB, to control the bandwidth of the device.

AbstractThis study evaluates the chemical processes responsible for the nitrous oxide (N2O) and methane (CH4) fluxes in the managed pasture (PM) and unmanaged pasture (PNM). In addition, the impact of nitrogen fertilization on the N2O and CH4 fluxes was assessed. The experiments were conducted on three farms in Alta Floresta city in the state of Mato Grosso. Both regular and intensive samples were collected from PM, PNM, and forest areas for each of the properties. The gases were sampled using static chambers in the morning. Higher N2O fluxes were recorded in the PMs, whereas the CH4 fluxes showed no influence of nitrogen fertilization in both regular and intensive samples. Low fertilizer levels resulted in low N2O emissions.

This paper presents a performance comparison between known propagation Models through least squares tuning algorithm for 5.8 GHz frequency band. The studied environment is based on the 12 cities located in Amazon Region. After adjustments and simulations, SUI Model showed the smaller RMS error and standard deviation when compared with COST231-Hata and ECC-33 models.