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Dong Xia,Ling Chen,Huizhong Chen,Xuyu Luo,Tao Deng 한국기상학회 2016 Asia-Pacific Journal of Atmospheric Sciences Vol.52 No.4
The atmospheric aerosols can absorb moisture from the environment due to their hydrophilicity and thus affect atmospheric radiation fluxes. In this article, the ultraviolet radiation and relative humidity (RH) data from ground observations and a radiative transfer model were used to examine the influence of RH on ultraviolet radiation flux and aerosol direct radiative forcing under the clear-sky conditions. The results show that RH has a significant influence on ultraviolet radiation because of aerosol hygroscopicity. The relationship between attenuation rate and RH can be fitted logarithmically and all of the R2 of the 4 sets of samples are high, i.e. 0.87, 0.96, 0.9, and 0.9, respectively. When the RH is 60%, 70%, 80% and 90%, the mean aerosol direct radiative forcing in ultraviolet is −4.22W m−2, −4.5W m−2, −4.82W m−2 and −5.4W m−2, respectively. For the selected polluted air samples the growth factor for computing aerosol direct radiative forcing in the ultraviolet for the RH of 80% varies from 1.19 to 1.53, with an average of 1.31.
Full-phase optimization of PDC bit cutter layout to reduce lateral force based on zoning method
Tong Cao,Kaian Yu,Xuyue Chen,Hongwu Zhu,Rui Zhang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.3
Balancing lateral force is essential to reduce bit vibrations and prolong bit service life. During the process of cutting, the instantaneous cutting situation is governed by the previous blades cutting. This paper introduces a notion called “zoning method” based on the cutting geometry of bit-rock interface, which is dedicated to distinguishing different phases of cutting. Furthermore, a full-phase optimization model is developed to optimize cutter layout for minimizing the lateral force in each cutting phase, the NSGA-II is used to solve for the Paretooptimal solutions, and the fuzzy comprehensive evaluation method is used to select the optimal solution. Finally, a case study of full-phase optimization of PDC bit cutter layout is conducted to highlight the advantage of the zoning method. The case study results show that the lateral force is reduced significantly in each cutting phase by using zoning method, which can help to achieve the real lateral force balance of PDC bit.