Recently, the application and development of flexible microwave-absorption composites based on silicone rubber have gradually become a research hot spot. In this study, methyl vinyl phenyl silicone rubber (MPVQ)/carbonyl iron particles (CIPs)/graphene (GR) composites were prepared by mechanical blending, and the effects of thermal-ageing temperature on the microwave-absorption properties of the composites were investigated. The mechanism of the thermal-ageing temperature’s effects on microwave-absorption behaviour was identified. The results show that unaged composites have superior microwave-absorption properties, with a minimum reflection loss (RLmin) of − 87.73 dB, a lowest thickness of 1.46 mm, and an effective absorption bandwidth (EAB, RL < − 10 dB) reaching 5.8 GHz (9.9–15.7 GHz). With ageing at 240 °C for 24 h, the RLmin at a frequency of 5.48 GHz is − 45.55 dB with a thickness of 2.55 mm, and the EAB value reaches 2 GHz (range 4.6–6.6 GHz). In the thermal-ageing process, a crosslinking reaction occurs in MPVQ with an increase in crosslinking density from 5.88 × 10−5 mol g−1 (unaged) to 4.69 × 10−4 mol g−1 (aged at 240 °C). Simultaneously, thermal degradation of the composites leads to a reduction in the rubber concentration. In addition, a small amount of CIPs are oxidized to Fe3O4, and the remaining CIPs aggregate to generate more electrically conductive pathways. Consequently, the dielectric loss of the composites will be significantly improved, resulting in poor impedance matching. The microwave-absorption properties of the composites gradually decrease with increasing thermal-ageing temperature from 200 to 240 °C.
In order to simply the design process and reduce the cost, a virtual prototype of spreader was built in this paper, which was used to simulate the operating condition of spreader in the open coal mine. Then the method of test and verification in engineering application is put forward. Finally, it obtains the parameters of system model of spreaders that satisfy the requirements in actual operating condition by analyzing the test results. The results indicate that the virtual prototype could simulate the real condition and provide exact data for the stable operation and maintenance of spreaders.
The Alfresco development tool, which includes Apache Tomcat, MySQL and WebService, is an open platform for building a functional database system in a Java website. In order to improve the enterprises’ management efficiency in specialized industrial townships, a micro-information system based on Alfresco development tool has been proposed. In the construction of the micro-information system, Alfresco database exhibits great superiority in network database architecture, data query with Lucene search engine, data management and data security. In this paper, the general design ideas, functions, key technologies and realization methods of the Alfresco database are introduced.
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