A physically based numerical model to predict the microstructure evolution and yield strength of high Cu-to-Mg mass ratio Al-Cu-Mg-Ag alloys during the whole ageing process was developed.A thermodynamically-based prec...A physically based numerical model to predict the microstructure evolution and yield strength of high Cu-to-Mg mass ratio Al-Cu-Mg-Ag alloys during the whole ageing process was developed.A thermodynamically-based precipitation model,employing the classical nucleation and growth theories,was adapted to deal with the precipitation kinetics (evolution of radius and volume fraction of precipitates for Ω phase) of aged Al-Cu-Mg-Ag alloys.The model gives an estimation of the precipitation kinetics (evolution of radius and density of precipitates for both θ' and Ω phases) of the alloy.The strengthening model based on Orowan mechanism was deduced.The microstructural development and strength predictions of the model are generally in good agreement with the experimental data.展开更多
Existing theories of the globalisation of firms fall short of integrating evolutionary, self-reproductive mechanisms. This conceptual paper serves to provide an overview on existing literature in systems theory and to...Existing theories of the globalisation of firms fall short of integrating evolutionary, self-reproductive mechanisms. This conceptual paper serves to provide an overview on existing literature in systems theory and to develop a basic framework for the study of evolutionary processes in the globalisation of firms. Ontological, epistemological, and methodological consequences of an evolutionary social systems approach to globalisation will be discussed.展开更多
The solutions of dynamic optimization problems are usually very difficult due to their highly nonlinear and multidimensional nature. 13enetic algorithm （GA） has been proved to be a teasibte method when the gradient ...The solutions of dynamic optimization problems are usually very difficult due to their highly nonlinear and multidimensional nature. 13enetic algorithm （GA） has been proved to be a teasibte method when the gradient is difficult to calculate. Its advantage is that the control profiles at all time stages are optimized simultaneously, but its convergence is very slow in the later period of evolution and it is easily trapped in the local optimum. In this study, a hybrid improved genetic algorithm （HIGA） for solving dynamic optimization problems is proposed to overcome these defects. Simplex method （SM） is used to perform the local search in the neighborhood of the optimal solution. By using SM, the ideal searching direction of global optimal solution could be found as soon as possible and the convergence speed of the algorithm is improved. The hybrid algorithm presents some improvements, such as protecting the best individual, accepting immigrations, as well as employing adaptive crossover and Ganssian mutation operators. The efficiency of the proposed algorithm is demonstrated by solving several dynamic optimization problems. At last, HIGA is applied to the optimal production of secreted protein in a fed batch reactor and the optimal feed-rate found by HIGA is effective and relatively stable.展开更多
The processes of globalization, the consequences of which are evident in all comers and at all levels of the contemporary world are linked to an increasing homogenization. Disciplines of architecture and urban design ...The processes of globalization, the consequences of which are evident in all comers and at all levels of the contemporary world are linked to an increasing homogenization. Disciplines of architecture and urban design contribute to that process, which is affecting the very definitions of place and identity. A desire to maintain and （re）create local identity within the context of that increasingly global world is connected to reviving of the past or to various interpretations of history, and preservation of the built environment of the place. This paper identifies peculiar processes of creation and maintenance of identity of place in the precincts of Tokyo Yanaka, Nezu and Sendagi, known as Yanesen. The authors argue that in Yanesen innovation appears as the byproduct of complex and creative responses to the threats of globalization, within a perpetual interplay of persistence and change. The paper opens a number of questions of where and how innovation in built environment can contribute to persistence of place identity.展开更多
基金Project(2005CB623705-04) supported by the National Basic Research Program of ChinaProject(1810-752300020) supported by Central South University and Ministry of Education of China for the Domestic Exchange PhD student
文摘A physically based numerical model to predict the microstructure evolution and yield strength of high Cu-to-Mg mass ratio Al-Cu-Mg-Ag alloys during the whole ageing process was developed.A thermodynamically-based precipitation model,employing the classical nucleation and growth theories,was adapted to deal with the precipitation kinetics (evolution of radius and volume fraction of precipitates for Ω phase) of aged Al-Cu-Mg-Ag alloys.The model gives an estimation of the precipitation kinetics (evolution of radius and density of precipitates for both θ' and Ω phases) of the alloy.The strengthening model based on Orowan mechanism was deduced.The microstructural development and strength predictions of the model are generally in good agreement with the experimental data.
文摘Existing theories of the globalisation of firms fall short of integrating evolutionary, self-reproductive mechanisms. This conceptual paper serves to provide an overview on existing literature in systems theory and to develop a basic framework for the study of evolutionary processes in the globalisation of firms. Ontological, epistemological, and methodological consequences of an evolutionary social systems approach to globalisation will be discussed.
基金Supported by Major State Basic Research Development Program of China （2012CB720500）, National Natural Science Foundation of China （Key Program： Ul162202）, National Science Fund for Outstanding Young Scholars （61222303）, National Natural Science Foundation of China （21276078, 21206037） and the Fundamental Research Funds for the Central Universities.
文摘The solutions of dynamic optimization problems are usually very difficult due to their highly nonlinear and multidimensional nature. 13enetic algorithm （GA） has been proved to be a teasibte method when the gradient is difficult to calculate. Its advantage is that the control profiles at all time stages are optimized simultaneously, but its convergence is very slow in the later period of evolution and it is easily trapped in the local optimum. In this study, a hybrid improved genetic algorithm （HIGA） for solving dynamic optimization problems is proposed to overcome these defects. Simplex method （SM） is used to perform the local search in the neighborhood of the optimal solution. By using SM, the ideal searching direction of global optimal solution could be found as soon as possible and the convergence speed of the algorithm is improved. The hybrid algorithm presents some improvements, such as protecting the best individual, accepting immigrations, as well as employing adaptive crossover and Ganssian mutation operators. The efficiency of the proposed algorithm is demonstrated by solving several dynamic optimization problems. At last, HIGA is applied to the optimal production of secreted protein in a fed batch reactor and the optimal feed-rate found by HIGA is effective and relatively stable.
文摘The processes of globalization, the consequences of which are evident in all comers and at all levels of the contemporary world are linked to an increasing homogenization. Disciplines of architecture and urban design contribute to that process, which is affecting the very definitions of place and identity. A desire to maintain and （re）create local identity within the context of that increasingly global world is connected to reviving of the past or to various interpretations of history, and preservation of the built environment of the place. This paper identifies peculiar processes of creation and maintenance of identity of place in the precincts of Tokyo Yanaka, Nezu and Sendagi, known as Yanesen. The authors argue that in Yanesen innovation appears as the byproduct of complex and creative responses to the threats of globalization, within a perpetual interplay of persistence and change. The paper opens a number of questions of where and how innovation in built environment can contribute to persistence of place identity.
