Free economic zone (FEZ) has a long history and plays a more and more important role in the world economy. Most studies, however, focused on the theoretical analysis of benefit and cost as well as the economic role of...Free economic zone (FEZ) has a long history and plays a more and more important role in the world economy. Most studies, however, focused on the theoretical analysis of benefit and cost as well as the economic role of FEZ in the less developed countries and little attention has been paid to the evolution of FEZ. This paper will improve the above-mentioned studies and put forward the structural and spatial evolutionary model of FEZ by analyzing the development of objectives, preferential policy, governance structure, industrial sectors and location of FEZs based on the international economic and political development. FEZs develop towards: 1) more comprehensive and macro objectives, 2) more industry-oriented and multi-preferential policies, 3) more cross-national and combination zones with administrative areas, 4) more technology-intensive and multi-industries, 5) more flexible location and larger spatial dimensions, 6) more rapid evolution and typologies, and 7) more economic integration to the host economy.展开更多
Knowledge of transport phenomena and keyhole evolution is important for controlling laser welding process. However, it is still not well understood by far due to the complex phenomena occurring in a wide temperature r...Knowledge of transport phenomena and keyhole evolution is important for controlling laser welding process. However, it is still not well understood by far due to the complex phenomena occurring in a wide temperature range. A transient 3D model including heat transfer, fluid flow and tracking of free surface is built in this study. The transport phenomena are investigated by calculating the temperature and velocity fields. The 3D dynamic keyhole evolution process is revealed through tracking free surface using volume-of-fluid method. The results show that the keyhole deepening speed decreases with laser welding process before the quasi-steady state is reached. The plasma can greatly affect the keyhole depth through absorbing a great amount of laser energy and thus lowering the recoil pressure. Moreover, the relationship between keyhole depth and weld penetration is also discussed. This paper can help to better understand the dynamics in molten pool and then improve laser welding process.展开更多
Void swelling is an important phenomenon observed in both nuclear fuels and cladding materials in operating nuclear reactors. In this work we develop a phase-field model to simulate void evolution and void volume chan...Void swelling is an important phenomenon observed in both nuclear fuels and cladding materials in operating nuclear reactors. In this work we develop a phase-field model to simulate void evolution and void volume change in irradiated materials. Important material processes, including the generation of defects such as vacancies and self-interstitials, their diffusion and annihilation, and void nucleation and evolution, have been taken into account in this model. The thermodynamic and kinetic properties, such as chemical free energy, interfacial energy, vacancy mobility, and annihilation rate of vacancies and interstitials, are expressed as a function of temperature and/or defect concentrations in a general manner. The model allows for parametric studies of critical void nucleus size, void growth kinetics, and void volume fraction evolutions. Our simulations demonstrated that void swelling displays a quasi-bell shape distribution with temperature often observed in experiments.展开更多
The term solidarity is used extensively in the current political debate in Europe. Many times, the European Union is accused of a ＂lack of solidarity＂. But is this really the case？ From the perspective of political...The term solidarity is used extensively in the current political debate in Europe. Many times, the European Union is accused of a ＂lack of solidarity＂. But is this really the case？ From the perspective of political theory, Jurgen Habermas convincingly argues that solidarity beyond the nation state is indeed possible - even without a European demos. Since solidarity was artificially constructed within the nation state, it could very well expand into a form of transnational solidarity. However, the European Union is a complex sui generis institution, characterized by its multi-level governance. This paper therefore complements Habermas＇ concep- tion by Andrea Sangiovanni＇s reciprocity-based internationalism which differenti- ates more detailed between national, member state and transnational solidarity. Moreover, the paper argues that the democratic deficiencies and the economic liberalization in the European Union led to a fourth form of solidarity： a revived solidarity with the nation state. The current situation within the European Union is thus not the result of a lack of solidarity. On the contrary, there is plenty of solidarity around. However, the parallel existence of these different forms of solidarity could not persist without conflicts under the given discourse where solidarity is framed as a zero-sum game. Hence, the European Union does not suffer from a lack of solidarity but rather from a clash of multiple solidarities.展开更多
文摘Free economic zone (FEZ) has a long history and plays a more and more important role in the world economy. Most studies, however, focused on the theoretical analysis of benefit and cost as well as the economic role of FEZ in the less developed countries and little attention has been paid to the evolution of FEZ. This paper will improve the above-mentioned studies and put forward the structural and spatial evolutionary model of FEZ by analyzing the development of objectives, preferential policy, governance structure, industrial sectors and location of FEZs based on the international economic and political development. FEZs develop towards: 1) more comprehensive and macro objectives, 2) more industry-oriented and multi-preferential policies, 3) more cross-national and combination zones with administrative areas, 4) more technology-intensive and multi-industries, 5) more flexible location and larger spatial dimensions, 6) more rapid evolution and typologies, and 7) more economic integration to the host economy.
基金Projects(51804348,51804196) supported by the National Natural Science Foundation of China
文摘Knowledge of transport phenomena and keyhole evolution is important for controlling laser welding process. However, it is still not well understood by far due to the complex phenomena occurring in a wide temperature range. A transient 3D model including heat transfer, fluid flow and tracking of free surface is built in this study. The transport phenomena are investigated by calculating the temperature and velocity fields. The 3D dynamic keyhole evolution process is revealed through tracking free surface using volume-of-fluid method. The results show that the keyhole deepening speed decreases with laser welding process before the quasi-steady state is reached. The plasma can greatly affect the keyhole depth through absorbing a great amount of laser energy and thus lowering the recoil pressure. Moreover, the relationship between keyhole depth and weld penetration is also discussed. This paper can help to better understand the dynamics in molten pool and then improve laser welding process.
基金supported by the US Department of Energy’s Nuclear Energy Advance Modeling and Simulation (NEAMS) Program in Pacific Northwest National Laboratory, which is operated by Battelle Memorial Institute for the US Department of Energy (Grant No. DE-AC05- 76RL01830)Two of the authors (LI YuLan and GAO Fei) were partially supported by the Materials Sciences and Engineering Division, Office of Basic Energy Sciences, US Department of Energy
文摘Void swelling is an important phenomenon observed in both nuclear fuels and cladding materials in operating nuclear reactors. In this work we develop a phase-field model to simulate void evolution and void volume change in irradiated materials. Important material processes, including the generation of defects such as vacancies and self-interstitials, their diffusion and annihilation, and void nucleation and evolution, have been taken into account in this model. The thermodynamic and kinetic properties, such as chemical free energy, interfacial energy, vacancy mobility, and annihilation rate of vacancies and interstitials, are expressed as a function of temperature and/or defect concentrations in a general manner. The model allows for parametric studies of critical void nucleus size, void growth kinetics, and void volume fraction evolutions. Our simulations demonstrated that void swelling displays a quasi-bell shape distribution with temperature often observed in experiments.
文摘The term solidarity is used extensively in the current political debate in Europe. Many times, the European Union is accused of a ＂lack of solidarity＂. But is this really the case？ From the perspective of political theory, Jurgen Habermas convincingly argues that solidarity beyond the nation state is indeed possible - even without a European demos. Since solidarity was artificially constructed within the nation state, it could very well expand into a form of transnational solidarity. However, the European Union is a complex sui generis institution, characterized by its multi-level governance. This paper therefore complements Habermas＇ concep- tion by Andrea Sangiovanni＇s reciprocity-based internationalism which differenti- ates more detailed between national, member state and transnational solidarity. Moreover, the paper argues that the democratic deficiencies and the economic liberalization in the European Union led to a fourth form of solidarity： a revived solidarity with the nation state. The current situation within the European Union is thus not the result of a lack of solidarity. On the contrary, there is plenty of solidarity around. However, the parallel existence of these different forms of solidarity could not persist without conflicts under the given discourse where solidarity is framed as a zero-sum game. Hence, the European Union does not suffer from a lack of solidarity but rather from a clash of multiple solidarities.
