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Along the East Asian coast, the interdecadal variation in tropical cyclone (TC) landfall activities in the early 2010s shows a tripole change pattern characterized by significantly increased (decreased) TC landfalls to the north of 30°N and to the south of 20°N (between 20° and 30°N). The increased TC landfalls in the East Asian subregion north to 30°N mean greater TC damage in the most populous regions, including southeastern China, the Korean Peninsula, and Japan, since the early 2010s. The present work uses an objective clustering technique to analyze the internal dynamical causes of this interdecadal variation. The increased TC landfall activities in the East Asian subregion north of 30°N are attributed to the increase in TCs with a northwestward-moving track (cluster defined as C1), whereas the increased TC landfall activities to the south of 20°N and the decrease between 20° and 30°N are mainly due to the southward shift of TCs with a westward-moving track (cluster defined as C2). This work focuses on different TC track groups (C1 and C2) based on daily data, showing that the interdecadal changes in the synoptic-scale monsoon trough and subtropical high provide important environment for different groups of TCs. The ascending phase of the PDO with significant warming over the central Pacific favors the interdecadal tripole changes in TC landfalls. [ABSTRACT FROM AUTHOR]

The effects of the silica surface treated by coupling agents KH550, KH560 and KH570 on the rheological properties of bismaleimide (BMI) resin system were investigated. The rigidity, coefficient of thermal expansion (CTE) and thermal stability of the copper clad laminate (CCL) were studied by DMA, TMA and TGA. The resin system containing silica surface treated by KH-560, comparing to KH550, KH570 and without surface treatment resin system has better rheological properties and low melt viscosity. The comprehensive properties of the copper clad laminate can be effectively improved by the introduction of silica in the resin system, exhibiting higher storage modulus and lower CTE compare to no silica in the CCL. When the silica mass fraction is 50%, the storage modulus is increased by 83% at 50℃, and the CTE below the glass transition temperature is decreased by 153%.

Due to their weak weather ability, the ageing process of organic silicone rubber composites remarkably influences the service performance of composite insulators and bushings, especially in high-voltage transmission lines. In this study, laser-induced breakdown spectroscopy (LIBS) was used for analysing ageing composite insulator sheds for potential on-site application. A spectrum was recorded after each laser pulse and the element composition of ablated materials with different depth was observed. A calibration curve that revealed linear relationship between C, Si, Al spectrum line intensity and corresponding element concentration was established with the result of X-ray photoelectron spectroscopy test. Regularly line intensities of C, Si and Al changed dramatically from the surface to the bulk layer. Given the number of laser pulses with varying element concentrations, as well as the linear relationship described above, the depth of ageing layer could be calculated immediately. Also, the result was verified by secondary ion mass spectrometry and scanning electron microscope. LIBS method can be a promising and efficient technique to assess the ageing state of composite materials on site.