Reconfigurable intelligent surfaces (RISs) are an emerging field of research in wireless communications. A fundamental component for analyzing and optimizing RIS-empowered wireless networks is the development of simple but sufficiently accurate models for the power scattered by an RIS. By leveraging the general scalar theory of diffraction and the Huygens-Fresnel principle, we introduce simple formulas for the electric field scattered by an RIS that is modeled as a sheet of electromagnetic material of negligible thickness. The proposed approach allows us to identify the conditions under which an RIS of finite size can or cannot be approximated as an anomalous mirror. Numerical results are illustrated to confirm the proposed approach.

This work considers a point-to-point link where a reconfigurable intelligent surface assists the communication between a transmitter and a receiver. The system rate, energy efficiency, and their trade-off are optimized by tuning the number of reflecting elements to be activated and the phase shifts that they apply. Unlike most previous works, the considered resource allocation problem explicitly accounts, at the design stage, for the time and energy that are necessary for channel estimation and for reporting the optimal configuration of the phase shifts to the reconfigurable intelligent surface. Numerical results confirm the optimality of the proposed methods and show the potential gains of reconfigurable intelligent surfaces.

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In this paper, we introduce a new methodology for modeling and analyzing downlink cellular networks, where the base stations (BSs) constitute a motion-invariant point process (PP) that exhibits some degree of interactions among the points, i.e., spatial repulsion or spatial clustering. The proposed approach is based on the theory of inhomogeneous Poisson PPs (I-PPPs) and is referred to as inhomogeneous double thinning (IDT) approach. In a PP, the distribution of the distance from a randomly distributed (typical) user to its nearest BS depends on the degree of spatial repulsion or clustering exhibited by the PP. In addition, the average number of interfering BSs that lies within a given distance from the typical user is a function of the repulsion and clustering characteristics of the PP. The proposed approach consists of approximating the original motion-invariant PP with an equivalent PP that is made of the superposition of two conditionally independent I-PPPs. The inhomogeneities of both PPs are created from the point of view of the typical user ("user-centric"): the first one is based on the distribution of the user's distance to its nearest BS and the second one is based on the distance-dependent average number of interfering BSs around the user. The inhomogeneities are mathematically modeled through two distance-dependent thinning functions and a tractable expression of the coverage probability is obtained. Sufficient conditions on the parameters of the thinning functions that guarantee better or worse coverage compared with the baseline homogeneous PPP model are identified. The accuracy of the IDT approach is substantiated with the aid of empirical data for the spatial distribution of the BSs.

Reconfigurable intelligent surfaces (RISs) are an emerging field of research in wireless communications. A fundamental component for analyzing and optimizing RIS-empowered wireless networks is the development of simple but sufficiently accurate models for the power scattered by an RIS. By leveraging the general scalar theory of diffraction and the Huygens-Fresnel principle, we introduce simple formulas for the electric field scattered by an RIS that is modeled as a sheet of electromagnetic material of negligible thickness. The proposed approach allows us to identify the conditions under which an RIS of finite size can or cannot be approximated as an anomalous mirror. Numerical results are illustrated to confirm the proposed approach.

The various post-translational modifications of plant proteins have important regulatory roles in development. We therefore examined various modified proteins from strawberry stigmata and found that succinylation of lysine residues was the most abundant type of modification. We then subjected proteins from strawberry stigmata to an efficient enrichment method for succinylated peptides and identified 200 uniquely succinylated lysines in 116 proteins. A bioinformatics analysis revealed that these proteins are involved in important biological processes, including stress responses, vesicular transport, and energy metabolism. Proteomics, combined with immunoprecipitation and immunoblotting, revealed an obvious increase in succinylation of the assembly polypeptide 2 (AP2) and clathrin from 0.5 to 2 h after pollination, suggesting that succinylation is involved in the recognition of pollen-stigma signaling substances and vesicular transport. These results suggest that AP2/clathrin-mediated vesicular transport processes are regulated by lysine succinylation during pollen recognition.

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The melting rate of round and square steel bars with various initial temperatures and sizes, and steel bars immersed in a liquid steel bath with different temperatures were studied. A steel shell was immediately formed around the original steel bar after it was immersed into the liquid steel, and then melt back as the immersion time increases. An increase in the preheating temperature of the bar and the liquid steel bath temperature is beneficial to steel bar melt. The maximum thickness of the steel shell decreases with increasing the initial temperature. While an increase in the liquid steel bath temperature, leads to an increase in the maximum thickness of the shell. When the round bar and square bar melt under the same conditions, the melting time of square bar is longer. It was also found that the heating rate in the centre of the steel bar initially increases and then decreases as the immersion time increases. The experimental results are of great significance for scrap melting and burden distribution in the electric arc furnace.