To determine the essence of the environmental carrying capacity (ECC), namely “threshold value of the human activities”, the paper established the optimization model of ECC using an inexact fuzzy multiobjective programming (IFMOP) method. It was solved to obtain the scale of economy, the size of the population, chemical oxygen demand (COD), sulfur dioxide emissions, and water and energy consumption using LINGO software in Wuhan city. Results showed that the available energy is the bottleneck restricting the economic development. And the available water resources and environmental capacity of sulfur dioxide played strong limit role. In the end, suggestion was proposed to further improve the Wuhan general urban planning.
In this study, the influence of pulling velocity on temperature field, fluid field and grain structure of a unidirectionally solidified superalloy DZ417G cylindrical casting was investigated by using a 3D cellular automaton finite element (CAFE) model within commercial software CALCOSOFT. The predictions show that temperature distribution in the casting is well in accordance with the experiment result. The solidification front and fluid field are sensitive to changes in pulling velocity. And the pulling velocity should be controlled less than 0.5 mm/s in our experiment so as to effectively decrease the grain number and mean grain deviation.
A macro-scale ProCAST and a meso-scale Cellular Automaton Finite Element model (CAFE) are used to simulate the grain selection during solidification with different simulation conditions. To improve the efficiency of the spiral grain selector, the effects of spiral geometries, boundary conditions and nucleation parameters on the grain selection are investigated. Simulation results reveal that the spiral geometries affect the height where the single crystal occurs in the spiral selector when volume nucleation is neglected. The average orientation deviation and grain number is relatively insensitive to volume nucleation and thermal boundary conditions around grain selector, and the thermal boundary conditions in the top of grain selector being of lesser importance.
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