Rapid progress in manufacturing greatly challenges to the VLSI physical design in both speed and performance. A fast detailed placement algorithm, FAME is presented in this paper, according to these demands. It inhe...Rapid progress in manufacturing greatly challenges to the VLSI physical design in both speed and performance. A fast detailed placement algorithm, FAME is presented in this paper, according to these demands. It inherits the optimal positions of cells given by a global placer and exact position to each cell by local optimization. FM Mincut heuristic and local enumeration are used to optimize the total wirelength in y and x directions respectively, and a two way mixed optimizing flow is adopted to combine the two methods for a better performance. Furthermore, a better enumeration strategy is introduced to speed up the algorithm. An extension dealing with blockages in placement has also been discussed. Experimental results show that FAME runs 4 times faster than RITUAL and achieves a 5% short in total wirelength on average.展开更多
Being physically intuitionistic and computationally efficient, the flamelet model has obtained increasing attention and becomes popular in numerical simulations of supersonic combustion. However, the flamelet model wa...Being physically intuitionistic and computationally efficient, the flamelet model has obtained increasing attention and becomes popular in numerical simulations of supersonic combustion. However, the flamelet model was firstly built for simulations of the low-speed flows. Therefore it is still unclear whether the assumption of the fiamelet model is reasonable in supersonic combustion. This paper tries to identify the existence of the flamelet mode in supersonic combustion. Firstly, the interaction of the turbulent fluctuation and the flame is discussed, based on which the combustion regime is distinguished. Then the charac- teristic length scale of the turbulent flows and the combustion inside the scramjet combustor are calculated and compared, which are used to identify whether the assumption of the flamelet model is reasonable in supersonic flows. The results show that for premixed combustion, due to the low fluctuation velocity in the recirculafion zone and the shear layer, the assumption of the flamelet model is established for all the flight Mach numbers, while for non-premixed combustion the assumption is also established for most of the flight Mach numbers except for very high Mach number under which the slow reaction mode dominates the combustion. In order to quantitatively examine the combustion mode, numerical calculations are performed to simulate the strut-injection supersonic combustion which has been experimentally investigated in German Aerospace Center. The results show that the supersonic combustion occurs in the fully-developed turbulent regions and the assumption of the flamelet model is established in the whole flow field.展开更多
基金Project Supported by National Natural Science Foundation of China( Grant No.697760 2 7) and by National973 Key Projectof China (
文摘Rapid progress in manufacturing greatly challenges to the VLSI physical design in both speed and performance. A fast detailed placement algorithm, FAME is presented in this paper, according to these demands. It inherits the optimal positions of cells given by a global placer and exact position to each cell by local optimization. FM Mincut heuristic and local enumeration are used to optimize the total wirelength in y and x directions respectively, and a two way mixed optimizing flow is adopted to combine the two methods for a better performance. Furthermore, a better enumeration strategy is introduced to speed up the algorithm. An extension dealing with blockages in placement has also been discussed. Experimental results show that FAME runs 4 times faster than RITUAL and achieves a 5% short in total wirelength on average.
基金supported by the National Natural Science Foundation of China (Grant No. 50906098)
文摘Being physically intuitionistic and computationally efficient, the flamelet model has obtained increasing attention and becomes popular in numerical simulations of supersonic combustion. However, the flamelet model was firstly built for simulations of the low-speed flows. Therefore it is still unclear whether the assumption of the fiamelet model is reasonable in supersonic combustion. This paper tries to identify the existence of the flamelet mode in supersonic combustion. Firstly, the interaction of the turbulent fluctuation and the flame is discussed, based on which the combustion regime is distinguished. Then the charac- teristic length scale of the turbulent flows and the combustion inside the scramjet combustor are calculated and compared, which are used to identify whether the assumption of the flamelet model is reasonable in supersonic flows. The results show that for premixed combustion, due to the low fluctuation velocity in the recirculafion zone and the shear layer, the assumption of the flamelet model is established for all the flight Mach numbers, while for non-premixed combustion the assumption is also established for most of the flight Mach numbers except for very high Mach number under which the slow reaction mode dominates the combustion. In order to quantitatively examine the combustion mode, numerical calculations are performed to simulate the strut-injection supersonic combustion which has been experimentally investigated in German Aerospace Center. The results show that the supersonic combustion occurs in the fully-developed turbulent regions and the assumption of the flamelet model is established in the whole flow field.
