On the Energy-Efficiency Trade-off Between Active and Passive Communications with RIS-based Symbiotic Radio

Symbiotic radio (SR) is a promising technology of spectrum- and energy-efficient wireless systems, for which the key idea is to use cognitive backscattering communication to achieve mutualistic spectrum and energy sharing with passive backscatter devices (BDs). In this paper, a reconfigurable intelligent surface (RIS) based SR system is considered, where the RIS is used not only to assist the primary active communication, but also for passive communication to transmit its own information. For the considered system, we investigate the EE trade-off between active and passive communications, by characterizing the EE region. To gain some insights, we first derive the maximum achievable individual EEs of the primary transmitter (PT) and RIS, respectively, and then analyze the asymptotic performance by exploiting the channel hardening effect. To characterize the non-trivial EE trade-off, we formulate an optimization problem to find the Pareto boundary of the EE region by jointly optimizing the transmit beamforming, power allocation and the passive beamforming of RIS. The formulated problem is non-convex, and an efficient algorithm is proposed by decomposing it into a series of subproblems by using alternating optimization (AO) and successive convex approximation (SCA) techniques. Finally, simulation results are presented to validate the effectiveness of the proposed algorithm

Informacijski servisni sustav za poljoprivredni IoT

Internet of Things (IoT) was faced with some difficulties which contained mass data management, various standards of object identification, data fusion of multiple sources, business data management and information service providing. In China, some safety monitoring systems of agricultural product always adopt centralized system architecture in which the data is stored concentratively. These systems could not be connected with or accessed by each other. This paper proposed an information system of agriculture Internet of Things based on distributed architecture. A distributed information service system based on IoT-Information Service, Object Naming Service, Discovery Service is designed to provide public information service including of capturing, standardizing, managing and querying of massive business data of agriculture production. A coding scheme for agricultural product, business location and logistic unit is provided for data identification. A business event model of agriculture IoT is presented for business data management. The whole system realizes the tracking and tracing of agricultural products, and quality monitoring of agriculture production. The implementation of this information service system is introduced.Internet stvari suočen je s poteškoćama poput upravljanja s velikom količinom podataka, različitim standardnima identifikacije objekata, fuzije podataka iz više izvora, upravljanja poslovnim podatcima i pružanje informacijskih usluga. Sigurnosno nadgledanje poljoprivrednih proizvoda u Kini uvijek podliježe centraliziranoj arhitekturi gdje su podatci koncentrirani na jednom mjestu. Takvi sustavi ne mogu biti povezani jedni s drugim te jedan drugome ne mogu pristupati. U ovome radu predložen je informacijski sustav za poljoprivredni internet stvari temeljen na distribuiranoj arhitekturi. Distribuirani informacijski servisni sustav baziran na IoT (Internet stvari), sustav za imenovanje objekata i sustav za otkrivanje omogućuju javni informacijski servis uključujući prikupljanje, standardizaciju, upravljanje i ispitivanje velikih količina podataka o poljoprivrednim proizvodima. Prikazana je shema kodiranja za poljopoprivredne proizvode, poslovne lokacije i logističke jedinice za identifikaciju podataka. Poslovni model doga.aja za poljoprivredni IoT je prezentiran za upravljanje poslovnim podatcima. Cjelokupni sustav omogućuje praćenje poljoprivrednih proizvoda te nadgledanje njihove kvalitete. Rad tako.er daje uvid u implementaciju informacijskog servisnog sustava

Statistical analysis of micro-variability properties of the blazar S5 0716+714

The typical blazar S5 0716$+$714 is very interesting due to its rapid and large amplitude variability and high duty cycle of micro-variability in optical band. We analyze the observations in I, R and V bands obtained with the $1.0m$ telescope at Weihai observatory of Shandong University from 2011 to 2018. The model of synchrotron radiation from turbulent cells in a jet has been proposed as a mechanism for explaining micro-variability seen in blazar light curves. Parameters such as the sizes of turbulent cells, the enhanced particle densities, and the location of the turbulent cells in the jet can be studied using this model. The model predicts a time lag between variations as observed in different frequency bands. Automatic model fitting method for micro-variability is developed, and the fitting results of our multi-frequency micro-variability observations support the model. The results show that both the amplitude and duration of flares decomposed from the micro-variability light curves confirm to the log-normal distribution. The turbulent cell size is within the range of about 5 to 55 AU, and the time lags of the micro-variability flares between the I-R and R-V bands should be several minutes. The time lags obtained from the turbulence model are consistent with the fitting statistical results, and the time lags of flares are correlated with the time lags of the whole light curve.Comment: 12 pages, 11 figures, Accepted by Ap

Key technologies research on of soil-structure interaction base story isolated structure response in 3D seismic zone

The development of karst in Karst area leads to poor stability of stratum. If earthquake occurs, the area will produce destructive disaster. In order to improve the stability capacity of the grassroots in the region, this study investigates the seismic response of inter-story isolation structures considering soil-structure interaction (SSI) in three-dimensional earthquakes. A model of the inter-story isolation structure incorporating SSI was developed, and one-dimensional, two-dimensional, and three-dimensional ground motions were applied to compare the seismic response under different input conditions. A three-dimensional isolation system was introduced and compared with traditional horizontal isolation structures to address excessive tensile and compressive stresses on the isolation structure during three-dimensional ground motion. The results demonstrate that the seismic response to three-dimensional earthquakes surpasses one-dimensional and two-dimensional inputs. Furthermore, adding a three-dimensional isolation structure effectively isolates vertical ground motion and reduces structural seismic response. Moreover, it minimizes soil stresses on the foundation compared to traditional horizontal isolation structure, enhancing foundation stability. This study will provide theoretical value and practical guidance for the research on key technology of SSI base story isolation structure response in Karst Plateau 3D Seismic zone