We report a molecular dynamics study of structural and transport properties of liquid nickel under high pres- sures. Pressure dependencies of pair distribution function and pair correlation entropy along the melting l...We report a molecular dynamics study of structural and transport properties of liquid nickel under high pres- sures. Pressure dependencies of pair distribution function and pair correlation entropy along the melting line indicate that the configuration change along melting lines decreases with increasing pressure. The calculated diffusion coefficients and viscosity by using entropy-scaling laws with modified parameters and ideal parameters are compared with those extracted from mean-square displacement or the Stokes-Einstein relation. The results suggest that the entropy-scaling laws hold well for coefficients and viscosity increase moderately with liquid nickel under high-pressure conditions, and the diffusion pressure along melting lines.展开更多
Mantle peridotites entrained as xenoliths in the lavas of Ngao Bilta in the eastern branch of the continental Cameroon Line were examined to constrain mantle processes and the origin and nature of melts that have modi...Mantle peridotites entrained as xenoliths in the lavas of Ngao Bilta in the eastern branch of the continental Cameroon Line were examined to constrain mantle processes and the origin and nature of melts that have modified the upper mantle beneath the Cameroon Line.The xenoliths consist mainly of lherzolite with subordinate harzburgite and dunite.They commonly contain olivine,orthopyroxene,clinopyroxene and spinel although the dunite is spinel-free.Amphibole is an essential constituent in the lherzolites.Mineral chemistry differs between the three types of peridotite:olivines have usual mantle-like Mg#of around 90 in lherzolites,but follow a trend of decreasing Mg#(to 82)and NiO(to 0.06 wt.%)that is continuous in the dunites.Lherzolites also contain orthopyroxenes and/or clinopyroxenes with low-Mg#,indicating a reaction that removes Opx and introduces Cpx,olivine,amphibole and spinel.This is attributed to reaction with a silica-undersaturated silicate melt such as nephelinite or basanite,which originated as a low-degree melt from a depleted source as indicated by low Al2O3 and Na2O in Cpx and high Na2O/K2O in amphibole.Thermobarometric estimates place the xenoliths at pressures of 11–15 kbar(35–50 km)and temperatures of 863–957C,along a dynamic rift geotherm and shallower than the region where carbonate melts may occur.The melt/rock reactions exhibited by the Ngao Bilta xenoliths are consistent with their peripheral position in the eastern branch of the Cameroon Volcanic Line in an area of thinned crust and lithosphere beneath the Adamawa Uplift.展开更多
输电线路覆冰事故在中国冬季时常发生,基于介质损耗与集肤效应的高频融冰方法在发热方面比传统交直流融冰有着显著的优势。针对高频高压在线融冰时电源频率、电压设计问题,提出一种基于NSGA‐Ⅱ的高频在线融冰电源参数的多目标优化设计...输电线路覆冰事故在中国冬季时常发生,基于介质损耗与集肤效应的高频融冰方法在发热方面比传统交直流融冰有着显著的优势。针对高频高压在线融冰时电源频率、电压设计问题,提出一种基于NSGA‐Ⅱ的高频在线融冰电源参数的多目标优化设计方法。首先,基于均匀传输线理论,建立了高频激励下的覆冰导线的等效传输线电路模型;其次,从工程实际出发,结合高频在线融冰的热平衡原理,推导得到高频在线融冰目标函数及约束条件;再次,通过NSGA‐Ⅱ算法求解得到该多目标问题的Pareto最优解集,并根据优劣解距离法(technique for order preference by similarity to an ideal solution,TOPSIS)法选择融冰电源参数;最后,利用COMSOL软件,基于有限元方法进行仿真验证。仿真结果验证该文融冰模型的正确性及所选参数的有效性。展开更多
基金Supported by the Science and Research Foundation of Sichuan Educational Committee under Grant Nos 13ZB0211 and 13ZA0198the Open Research Fund of Computational Physics Key Laboratory of Sichuan Province under Grant No JSWL2014KF06
文摘We report a molecular dynamics study of structural and transport properties of liquid nickel under high pres- sures. Pressure dependencies of pair distribution function and pair correlation entropy along the melting line indicate that the configuration change along melting lines decreases with increasing pressure. The calculated diffusion coefficients and viscosity by using entropy-scaling laws with modified parameters and ideal parameters are compared with those extracted from mean-square displacement or the Stokes-Einstein relation. The results suggest that the entropy-scaling laws hold well for coefficients and viscosity increase moderately with liquid nickel under high-pressure conditions, and the diffusion pressure along melting lines.
基金funded by Australian Research Council grant FL180100134
文摘Mantle peridotites entrained as xenoliths in the lavas of Ngao Bilta in the eastern branch of the continental Cameroon Line were examined to constrain mantle processes and the origin and nature of melts that have modified the upper mantle beneath the Cameroon Line.The xenoliths consist mainly of lherzolite with subordinate harzburgite and dunite.They commonly contain olivine,orthopyroxene,clinopyroxene and spinel although the dunite is spinel-free.Amphibole is an essential constituent in the lherzolites.Mineral chemistry differs between the three types of peridotite:olivines have usual mantle-like Mg#of around 90 in lherzolites,but follow a trend of decreasing Mg#(to 82)and NiO(to 0.06 wt.%)that is continuous in the dunites.Lherzolites also contain orthopyroxenes and/or clinopyroxenes with low-Mg#,indicating a reaction that removes Opx and introduces Cpx,olivine,amphibole and spinel.This is attributed to reaction with a silica-undersaturated silicate melt such as nephelinite or basanite,which originated as a low-degree melt from a depleted source as indicated by low Al2O3 and Na2O in Cpx and high Na2O/K2O in amphibole.Thermobarometric estimates place the xenoliths at pressures of 11–15 kbar(35–50 km)and temperatures of 863–957C,along a dynamic rift geotherm and shallower than the region where carbonate melts may occur.The melt/rock reactions exhibited by the Ngao Bilta xenoliths are consistent with their peripheral position in the eastern branch of the Cameroon Volcanic Line in an area of thinned crust and lithosphere beneath the Adamawa Uplift.
文摘输电线路覆冰事故在中国冬季时常发生,基于介质损耗与集肤效应的高频融冰方法在发热方面比传统交直流融冰有着显著的优势。针对高频高压在线融冰时电源频率、电压设计问题,提出一种基于NSGA‐Ⅱ的高频在线融冰电源参数的多目标优化设计方法。首先,基于均匀传输线理论,建立了高频激励下的覆冰导线的等效传输线电路模型;其次,从工程实际出发,结合高频在线融冰的热平衡原理,推导得到高频在线融冰目标函数及约束条件;再次,通过NSGA‐Ⅱ算法求解得到该多目标问题的Pareto最优解集,并根据优劣解距离法(technique for order preference by similarity to an ideal solution,TOPSIS)法选择融冰电源参数;最后,利用COMSOL软件,基于有限元方法进行仿真验证。仿真结果验证该文融冰模型的正确性及所选参数的有效性。
