Transformer oil-based nanofluids with TiO2 semiconductive nanoparticles exhibit substantially higher AC and positive impulse breakdown voltage levels than that of pure transformer oils. Thermally stimulated current method (TSC) and pulse electroacoustic technique (PEA) have been used to measure charge trap and transportation characteristics of pure oils and nanofluids. It is found that electron shallow trap density and charge decay rate are greatly increased in nanofluids, i.e., fast electrons may be converted to slow electrons by electron trapping and de-trapping in shallow traps of nanofluids, resulting in improved breakdown performance compared to that of pure oil.

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When user turns head in an interactive Cloud VR service, such as the Cloud VR games, the black edge artifact often appears at the boundary of the viewport due to the inevitable latency, which significantly affects the user experience. In this paper, we focused on the interactive Cloud VR gaming services and investigated the influence of the black edge artifact on the user experience. The appearance of the black edge artifact during the playing period was regarded as a series of black edge events. The user experience on a single black edge event was first evaluated combining the influential factors of the area ratio and duration of the black edge artifact. Then, a pooling strategy was proposed to evaluate the user's overall experience. Experimental results showed that the proposed model can accurately predict the user experience that influenced by the black edge artifact for the Cloud VR services. This work can be served as a guideline for service providers and network operators to improve their services.

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