A modified computational fluid dynamic (CFD) model has been developed to obtain oil removal efficiency for oily wastewater treatment in large-scale flotation tanks. According to the investigation of oil droplet/bubble interactions in a flotation tank, a modified Bloom–Heindel model is used to calculate the collision and attachment efficiencies between oil droplets and bubbles. Effects of the gas flow rate, oil diameter and oil concentration on oil removal efficiency of flotation tank were analyzed experimentally. The application scope of this modified CFD model is evaluated using experimental results. In addition, the comparison between the existing model and the modified model demonstrates that this modified CFD model can make a good prediction for the separation performance of the flotation tank.
Stealth technology is critical for the existence and the employment of the modern combat weapons systems. Electrochromic materials, which are known as a kind of novel intelligent stealth materials with multi-coloring effect under dynamic control, shows reversible color and emittance change under applied electric filed. Current emerging EC technologies utilizing electrochromism being widely used in intelligent stealth to produce more enhanced effects than traditional static options. This review mainly discusses recent advancement in the electrochromic materials with focus on its applications in the intelligent stealth technologies. Firstly, the principle and classification of electrochromic materials are presented along with summary of recent developments in electrochromism. Secondly, the potential applications of inorganic and organic electrochromism in visible and infrared stealth bands are highlighted. Finally, the challenges and further development approaches are emphasized; it will be intended to underline the future perspectives in realizing intelligent stealth for different applications.
TiO2/TiB2 materials are prepared by the carbothermal method and high-temperature calcination. Further, the phase composition, microstructure, dielectric and electromagnetic (EM) wave absorption characteristics are investigated. The results display that the product is composed of TiO2, TiB2 and impurity phases. The complex permittivity increases at elevated TiO2/TiB2 loading and slowly decreases with rising frequency in 2-18 GHz. When the TiO2/TiB2 content is 45 wt%, the minimum reflection loss (RLmin
) reaches -43.12 dB at 11.68 GHz with a thickness of 1.9 mm. The effective absorption band (EAB, RL<-10 dB) can reach 3.68 GHz at 2.3 mm as the TiO2/TiB2 content is 30 wt%. The enhanced EM wave absorption owes to the strong polarization loss and high conductivity loss. It goes without saying that TiO2/TiB2 materials can acquire important breakthroughs in the development of novel EM wave absorbers with outstanding absorption loss, wider EAB and smaller thicknesses.
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