This study is aimed at determining the diffusion coeffcient of net-work modifiers（mainly Na, K, and Ca） in a two-phase melt-NaCl system, in which the melts are granitic andthe system is NaCl-rich in composition. The...This study is aimed at determining the diffusion coeffcient of net-work modifiers（mainly Na, K, and Ca） in a two-phase melt-NaCl system, in which the melts are granitic andthe system is NaCl-rich in composition. The diffusion coefficients of Na, K, and Ca were measured at the temperatures of 750 -1400℃, pressures of 0. 001×108 - 2×108 Pa, and initialH2O contents of O wt% - 6. 9 wt% in the granitic melts. The diffusion coefficients of Fe andMg were difficuIt to resolve. In all experiments a NaCl melt was present as well. In the absence of H2O, the diffusion of net-work modifiers folows an Arrhanious equation at 1 ×105 Pa:lgDCa= - 3. 88 - 5140/ T, lgDK = - 3. 79 - 4040/ T, and lgDNa=- 4.99 - 3350/ T,where D is in cm2/s and T is in K. The diffusion coefficients of Ca, Na, K, and Fe increasenon-linearly with increasing H2O cOntent in the melt. The presence of about 2 wt% H2O inthe melt will lead to a dramatical increase in diffusivity, but higher H2O content has only a minor effect. This change is probably the result of a change in the melt structure when H2O ispresent. The diffusion coefficients measured in this study are significantly different from thosein previous woks. This may be understood in terms of the "transient two-liquid equilibrium"theory. Element interdiffusion dapends not only on its concentration, but also on its activity coefficient gradient, which is reflected by the distribution coefficient, of the two contactingmelts.展开更多
The paper combines Tobin's Q theory of real investment with the capital asset pricing model to produce a new and relatively simple procedure for the valuation of real assets using the income approach. Applications...The paper combines Tobin's Q theory of real investment with the capital asset pricing model to produce a new and relatively simple procedure for the valuation of real assets using the income approach. Applications of the new method are provided.展开更多
Based on the principles of Genetic Algorithms (GAs), a hybrid genetic algorithm used to optimize simple distillation column sequences was established. A new data structure, a novel arithmetic crossover operator and a ...Based on the principles of Genetic Algorithms (GAs), a hybrid genetic algorithm used to optimize simple distillation column sequences was established. A new data structure, a novel arithmetic crossover operator and a dynamic mutation operator were proposed. Together with the feasibility test of distillation columns, they are capable to obtain the optimum simple column sequence at one time without the limitation of the number of mixture components, ideal or non-ideal mixtures and sloppy or sharp splits. Compared with conventional algorithms, this hybrid genetic algorithm avoids solving complicated nonlinear equations and demands less derivative information and computation time. Result comparison between this genetic algorithm and Underwood method and Doherty method shows that this hybrid genetic algorithm is reliable.展开更多
文摘This study is aimed at determining the diffusion coeffcient of net-work modifiers（mainly Na, K, and Ca） in a two-phase melt-NaCl system, in which the melts are granitic andthe system is NaCl-rich in composition. The diffusion coefficients of Na, K, and Ca were measured at the temperatures of 750 -1400℃, pressures of 0. 001×108 - 2×108 Pa, and initialH2O contents of O wt% - 6. 9 wt% in the granitic melts. The diffusion coefficients of Fe andMg were difficuIt to resolve. In all experiments a NaCl melt was present as well. In the absence of H2O, the diffusion of net-work modifiers folows an Arrhanious equation at 1 ×105 Pa:lgDCa= - 3. 88 - 5140/ T, lgDK = - 3. 79 - 4040/ T, and lgDNa=- 4.99 - 3350/ T,where D is in cm2/s and T is in K. The diffusion coefficients of Ca, Na, K, and Fe increasenon-linearly with increasing H2O cOntent in the melt. The presence of about 2 wt% H2O inthe melt will lead to a dramatical increase in diffusivity, but higher H2O content has only a minor effect. This change is probably the result of a change in the melt structure when H2O ispresent. The diffusion coefficients measured in this study are significantly different from thosein previous woks. This may be understood in terms of the "transient two-liquid equilibrium"theory. Element interdiffusion dapends not only on its concentration, but also on its activity coefficient gradient, which is reflected by the distribution coefficient, of the two contactingmelts.
文摘The paper combines Tobin's Q theory of real investment with the capital asset pricing model to produce a new and relatively simple procedure for the valuation of real assets using the income approach. Applications of the new method are provided.
文摘Based on the principles of Genetic Algorithms (GAs), a hybrid genetic algorithm used to optimize simple distillation column sequences was established. A new data structure, a novel arithmetic crossover operator and a dynamic mutation operator were proposed. Together with the feasibility test of distillation columns, they are capable to obtain the optimum simple column sequence at one time without the limitation of the number of mixture components, ideal or non-ideal mixtures and sloppy or sharp splits. Compared with conventional algorithms, this hybrid genetic algorithm avoids solving complicated nonlinear equations and demands less derivative information and computation time. Result comparison between this genetic algorithm and Underwood method and Doherty method shows that this hybrid genetic algorithm is reliable.
