A description of a mathematical algorithm for simulating grain structures with straight and hyperbolic interfaces is shown. The presence of straight and hyperbolic interfaces in many grain structures of metallic mater...A description of a mathematical algorithm for simulating grain structures with straight and hyperbolic interfaces is shown. The presence of straight and hyperbolic interfaces in many grain structures of metallic materials is due to different solidification conditions, in- eluding different solidification speeds, growth directions, and delaying on the nucleation times of each nucleated node. Grain growth is a complex problem to be simulated; therefore, computational methods based on the chaos theory have been developed for this purpose. Straight and hyperbolic interfaces are between columnar and equiaxed grain structures or in transition zones. The algorithm developed in this work involves random distributions of temperature to assign preferential probabilities to each node of the simulated sample for nucleation according to previously defined boundary conditions. Moreover, more than one single nucleation process can be established in order to gen- erate hyperbolic interfaces between the grains. The appearance of new nucleated nodes is declared in sequences with a particular number of nucleated nodes and a number of steps for execution. This input information influences directly on the final grain structure （grain size and dislribution）. Preferential growth directions are also established to obtain equiaxed and columnar grains. The simulation is done using rou- tines for nucleation and growth nested inside the main function. Here, random numbers are generated to place the coordinates of each new nucleated node at each nucleation sequence according to a solidification probability. Nucleation and growth routines are executed as a func- tion of nodal availability in order to know if a node will be part of a grain. Finally, this information is saved in a two-dimensional computa- tional array and displayed on the computer screen placing color pixels on the corresponding position forming an image as is done in cellular automaton.展开更多
Interface automata are one of the prominent formalisms for specifying interface behaviors of componentbased systems. However, only one-to-one communication is allowed in the composition of interface automata. This pap...Interface automata are one of the prominent formalisms for specifying interface behaviors of componentbased systems. However, only one-to-one communication is allowed in the composition of interface automata. This paper presents multicast interface automata which generalize the classic interface automata and accommodate multicast communication mechanism. The multicast interface automata endorse both bottom-up and top-down design methodologies. Theoretical results on compatibility and refinement are established for incremental design and independent implementability.展开更多
文摘A description of a mathematical algorithm for simulating grain structures with straight and hyperbolic interfaces is shown. The presence of straight and hyperbolic interfaces in many grain structures of metallic materials is due to different solidification conditions, in- eluding different solidification speeds, growth directions, and delaying on the nucleation times of each nucleated node. Grain growth is a complex problem to be simulated; therefore, computational methods based on the chaos theory have been developed for this purpose. Straight and hyperbolic interfaces are between columnar and equiaxed grain structures or in transition zones. The algorithm developed in this work involves random distributions of temperature to assign preferential probabilities to each node of the simulated sample for nucleation according to previously defined boundary conditions. Moreover, more than one single nucleation process can be established in order to gen- erate hyperbolic interfaces between the grains. The appearance of new nucleated nodes is declared in sequences with a particular number of nucleated nodes and a number of steps for execution. This input information influences directly on the final grain structure （grain size and dislribution）. Preferential growth directions are also established to obtain equiaxed and columnar grains. The simulation is done using rou- tines for nucleation and growth nested inside the main function. Here, random numbers are generated to place the coordinates of each new nucleated node at each nucleation sequence according to a solidification probability. Nucleation and growth routines are executed as a func- tion of nodal availability in order to know if a node will be part of a grain. Finally, this information is saved in a two-dimensional computa- tional array and displayed on the computer screen placing color pixels on the corresponding position forming an image as is done in cellular automaton.
基金This work was supported by the Chinese National 973 Plan （2010CB328003）, the National Natural Science Foundation of China （Grant Nos. 61272001, 60903030, 91218302）, the Chinese National Key Technology R＆D Program （SQ2012BAJY4052）, the Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions （YETP0167）, and the Tsinghua University Initiative Scientific Research Program.
文摘Interface automata are one of the prominent formalisms for specifying interface behaviors of componentbased systems. However, only one-to-one communication is allowed in the composition of interface automata. This paper presents multicast interface automata which generalize the classic interface automata and accommodate multicast communication mechanism. The multicast interface automata endorse both bottom-up and top-down design methodologies. Theoretical results on compatibility and refinement are established for incremental design and independent implementability.
