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One of the commonly used stabilization systems for rock tunnel is shotcrete. However, the hydration of shotcrete is usually accompanied by the development of internal defects and micro damage under high temperature. Additionally, in the actual high‐temperature engineering, the temperature of the rock tunnel exhibits irregular changes. Therefore, in this study, the curing conditions of constant temperature (23°C, 40°C, 60°C, 80°C) and variable temperature (23–40–60–80°C, 80–60–40–23°C) are set, respectively. The mechanical properties and structural properties of polyurethane shotcrete and ordinary Portland shotcrete are introduced. It is determined that the limit temperature for inhibiting the development of sprayed concrete's compressive and splitting strength is between 60°C and 80°C, and the limit temperature for inhibiting the development of bond strength is about 40°C. Meanwhile, the influence of high temperature on the thermal insulation performance of shotcrete is considered. The results that the self‐foaming performance of polymer(polyurethane) reduces the thermal conductivity of shotcrete. Based on this phenomenon, the heat transfer model of shotcrete at room and high temperature is established to clarify the heat transfer process of shotcrete. Results will provide theoretical basis for further research of durability and heat insulation performance of protective spraying material for tunnel under high temperature. [ABSTRACT FROM AUTHOR]

In this work the fuzzy adaptive control issue is investigated for multiple‐input multiple‐output (MIMO) uncertain nonlinear systems in strict‐feedback form. The controlled systems under consideration of this work contain the immeasurable states, unknown control gain functions and input time delays. The immeasurable states are estimated by constructing a fuzzy state observer, and the uncertain nonlinear functions are approximated by utilizing the fuzzy logic systems (FLSs). In addition, the Pade approximation method is employed to handle the input time delays problem. An observer‐based fuzzy adaptive centralized control algorithm is presented by employing the adaptive backstepping control design technique and constructing the Logarithm Lyapunov functions. The designed fuzzy adaptive robust control algorithm can make sure that all signals in the closed‐loop system are semi‐globally uniformly ultimately boundedness (SGUUB). Finally, a numerical simulation example and a practical system example are considered to testify the availability of the designed centralized controllers. [ABSTRACT FROM AUTHOR]

Node localisation technology is one of the most challenging and important issues in wireless sensor networks. This study puts forward a novel and high accuracy estimation method by combining distance‐measuring with angle‐measuring. An anchor node equipped with a directional antenna periodically sends beacons containing its position and antenna orientation to unknown nodes. By observing the variation of received signal strength indication values of beacons and the time of flight values, an unknown node can estimate the distance and orientation relative to the beacon node simultaneously. This study proposed an online modelling method to calibrate the shift of the estimated distance. Meanwhile, an angle estimation method is presented to avoid an ambiguous result, which is a new weighted curve fitting method based on least square principle. The experimental results show that the proposed ranging and angle measurement reaches a better localisation accuracy compared with the original ranging and angle method. [ABSTRACT FROM AUTHOR]

In order to find a way to solve the contradiction among storage space, transmission capacity and the data volume in the embedded systems, a data compression scheme based on block matching with an identifier is presented by using the technology of digital integrated circuit. The scheme can achieve lossless real‐time data compression and reduce the volume of the data. Through statistical analysis on the data source, the authors can obtain that such a scheme has many advantages in real‐time performance, a complication of implement, efficiency and practicability. So the digital circuit is considered as a method which can present the encoding process. With the help of QUARTUS II, they combine Verilog and schematic to finish the design hierarchically and code the decompression program by using C language for comparison. The accuracy and efficiency of the circuit are verified with simulation and relevant experiments. The average compression rate is 52.3% with 12 MHz clock frequency and the compression speed on average is 352% faster than the one by using block‐match software algorithm. The scheme would have good performance in many embedded systems. [ABSTRACT FROM AUTHOR]

Review: 42 refs. [ABSTRACT FROM AUTHOR]