Search

In order to study the effect of high temperatures on the thermomechanical properties of reinforced concrete (RC) beams, fire and mechanical tests were carried out on four fully dimensioned simply supported beams. A numerical analysis model based on the measured information was developed, and validated through experimental tests and theoretical calculations. The effects of fire exposure time, different physical parameters and concrete spalling parameters on the thermodynamic properties were further analysed. The results show that the measured vibration frequencies exhibit a fluctuating trend of decay with increasing fire exposure time. The simulated frequency decays as a power function of fire exposure time. The frequency decreases with increasing span-to-height ratio and increases with section width, elasticity modulus of the concrete and reinforcement ratio. Cross-sectional temperature field is most significantly affected by spalling depth, and increases rapidly with an increase in this parameter. With the increase in spalling area ratio, the increase in the temperature field gradually becomes smaller. The effect of spalling area ratio was relatively stable after more than 15%. Flexural bearing capacity shows a linear trend of decrease with increase in spalling depth. With the increase in spalling area ratio, it shows a power function of the decreasing trend. [ABSTRACT FROM AUTHOR]

The feasibility of CuI and C60 as hole transport layer and electron transport layer in the perovskite solar cell is tested by using the software Solar Cell Capacitance Simulator (SCAPS). It is found that the thicknesses of the absorption layer, electron transport layer and hole transport layer, and the Interface Density of Defect State of their interface have a key influence on the efficiency of the perovskite solar cells. After optimization, the efficiency was as twice as that before, 22.70% to 11.62%, and the fill factor can still be at a high value, 76%.

Post-silking heat stress is one of the main stresses affecting grain filling and yield formation of summer maize in the Huang-Huai-Hai plains. At present, it has been confirmed that increasing nitrogen application can alleviate the inhibition of post-silking heat stress on the yield formation of wheat, maize, and rice, but the regulatory pathways and physiological mechanisms remain unclear. In this study, two maize varieties Zhengdan 958 (ZD958) and Xianyu 335 (XY335) were selected in pot experiment. To study the effects of increased nitrogen application on carbon and nitrogen metabolism of maize under heat stress during post-silking stage, two temperature treatments [ambient temperature (CK) and heat stress (HS)], three nitrogen application levels [low nitrogen application rate (LN): 120 kg hm-2, middle nitrogen application rate (MN): 240 kg hm-2, and high nitrogen application rate (HN): 360 kg hm-2] were set. The results showed that the dry weight of ZD958 and XY335 cultivars at maturity stage decreased by 10.6%-19.3% after 20 days of post-silking heat stress (35°C) compared with the ambient temperature. However, the decrease of kernel dry weight under heat stress was gradually decreased with the increase of nitrogen application rate, and the decrease rate (10.6%-11.2%) of kernel dry weight under medium nitrogen application rate (MN) and high nitrogen application rate (HN) was lower than that (16.2%-19.3%) under low nitrogen application rate (LN), which indicating that increased nitrogen application could significantly increase maize kernel dry weight under post-silking heat stress. This was mainly due to the increasing application of nitrogen effectively alleviated the inhibitory effect of early post-silking heat stress on maize grain nitrogen metabolism, and significantly increased the activities of key enzymes of nitrogen metabolism such as glutamine synthetase (GS) and glutamate synthetase (GOGAT). At the same time, the activities of sucrose phosphate synthetase (SPS) and sucrose synthetase (SS), which were key enzymes of carbon metabolism, were maintained, and the synthesis of soluble sugar in grains was increased, thus ensuring a larger amount of material for grain filling. In conclusion, increasing nitrogen application can alleviate the inhibition of post-silking heat stress on grain carbon and nitrogen metabolism and promote the accumulation of assimilates in grain and increase the kernel weight and yield, which provides a way for the resistant cultivation of summer maize in the Huang-Huai-Hai plains. [ABSTRACT FROM AUTHOR]

With the popularity of spatiotemporal big data applications, more and more sensitive data are generated by users, and the sharing and secure storage of spatiotemporal big data are faced with many challenges. In response to these challenges, the present paper puts forward a new technology called CSSoB (Classified Secure Storage Technology over Blockchain) that leverages blockchain technology to enable classified secure storage of spatiotemporal big data. This paper introduces a twofold approach to tackle challenges associated with spatiotemporal big data. First, the paper proposes a strategy to fragment and distribute space–time big data while enabling both encryption and nonencryption operations based on different data types. The sharing of sensitive data is enabled via smart contract technology. Second, CSSoB's single-node storage performance was assessed under local and local area network (LAN) conditions, and results indicate that the read performance of CSSoB surpasses its write performance. In addition, read and write performance were observed to increase significantly as the file size increased. Finally, the transactions per second (TPS) of CSSoB and the Hadoop Distributed File System (HDFS) were compared under varying thread numbers. In particular, when the thread number was set to 100, CSSoB demonstrated a TPS improvement of 7.8% in comparison with HDFS. Given the remarkable performance of CSSoB, its adoption can not only enhance storage performance, but also improve storage security to a great extent. Moreover, the fragmentation processing technology employed in this study enables secure storage and rapid data querying while greatly improving spatiotemporal data processing capabilities. [ABSTRACT FROM AUTHOR]