Metasurfaces 3.0: a New Paradigm for Enabling Smart Electromagnetic Environments

So far, the environment has been considered as a source of fading, clutter, blockage, etc., with detrimental consequences for the efficiency and robustness of communication systems. However, the intense research developed toward beyond-5G communications is leading to a paradigm change, in which the environment is exploited as a new degree of freedom and plays an active role in achieving unprecedented system performances. For implementing this challenging paradigm, it has been recently proposed the use of intelligent surfaces able to control almost at will the propagation of electromagnetic waves. In this framework, metasurfaces have emerged as a promising solution, thanks to their field manipulation capabilities achieved through low-cost, lightweight, and planar structures. The aim of this paper is to review some recent applications of metasurfaces and cast them in the scenario of next-generation wireless systems. In particular, we show their potentialities in overcoming some detrimental effects presented by the environment in wireless communications, and discuss their crucial role towards the practical implementation of a smart electromagnetic environment

Agrobiodiversity of Vegetable Crops in Agroecosystems in Iran

Preservation and increase of biodiversity is one of the main components to achieve sustainability in agricultural systems. In this study, biodiversity evaluation indexes were used to evaluate and compare agrobiodiversity of vegetable crop systems among all provinces of Iran. In this study the biodiversity evaluation indexes included Shannon-Wiener, Simpson and Evenness. In order to compare the alpha and beta biodiversity in different regions of Iran, the country was divided to 5 different weather and geographic regions, then alpha and beta biodiversity were calculated by species – area relationship according to these areas. The results showed nearly 31 vegetable species are cultivated in Iran that the highest planted area after that tomato, potato and onion was related to aubergine with 6.07% of the total vegetable lands of Iran. The whole of vegetable lands area was 495412 ha that the Fars province with 8.83% of the total vegetable lands of the country, was the first and it was the major producer of 9 species of vegetables. The highest vegetable species richness was related to Esfahan and Mazandaran (29 species) and the lowest was for Chaharmahal bakhtiari (5 species). The Shannon index for these species in total vegetable lands (H) was 0.628 besides this index in highest level has been discovered in Yazd (2.70) and the Shannon index for these species of the total arable lands of the country ( ) was 0.210 besides this index in highest level had been discovered in Hormozgan (1.01). The highest (0.459) and lowest (0) of alpha biodiversity was calculated in north and south regions, respectively. In the other hand, the highest (1.41) and lowest (0.375) beta biodiversity was related to south and north regions, respectively

Intelligence enabled by 2D metastructures in antennas and wireless propagation systems

The development of the next generation of wireless systems is bringing renewed attention to the physical layer of the communication link. Indeed, the new low-latency requirements cannot be satisfied relying only upon the extreme virtualization of the hardware functions. Moreover, conventional wireless systems with fixed characteristics and functionalities are not appropriate to modern electromagnetic environments, which undergo continuous and fast variations. Embedded smartness is a required feature for widening the range of the possible electromagnetic responses to support advanced and novel functionalities. In this paper, we show how the combination of 2D metastructures with conventional antennas and reflectors enables an unprecedented electromagnetic behavior, which is at the basis of new properties, capabilities, and applications. In particular, we propose an emerging design approach based on the shifting of the reconfigurability, adaptivity, sensing, and power management of a wireless system at the physical level, thanks to the use of properly designed 2D metastructures to be coupled with standard antennas and reflectors