We present numerical modeling of SH-wave propagation for the recently proposed whole Moon model and try to improve our understanding of lunar seismic wave propagation. We use a hybrid PSM/FDM method on staggered grids...We present numerical modeling of SH-wave propagation for the recently proposed whole Moon model and try to improve our understanding of lunar seismic wave propagation. We use a hybrid PSM/FDM method on staggered grids to solve the wave equations and implement the calculation on a parallel PC cluster to improve the computing efficiency. Features of global SH-wave propagation are firstly discussed for a 100-km shallow and900-km deep moonquakes, respectively. Effects of frequency range and lateral variation of crust thickness are then investigated with various models. Our synthetic waveforms are finally compared with observed Apollo data to show the features of wave propagation that were produced by our model and those not reproduced by our models. Our numerical modeling show that the low-velocity upper crust plays significant role in the development of reverberating wave trains. Increasing frequency enhances the strength and duration of the reverberations.Surface multiples dominate wavefields for shallow event.Core–mantle reflections can be clearly identified for deep event at low frequency. The layered whole Moon model and the low-velocity upper crust produce the reverberating wave trains following each phases consistent with observation. However, more realistic Moon model should be considered in order to explain the strong and slow decay scattering between various phases shown on observation data.展开更多
The GAMMA paradigm is recently proposed by Banatre and M6tayer to describe the systematic construction of parallel programs without introducing artificial sequentiality. This paper presents two synchronous execution m...The GAMMA paradigm is recently proposed by Banatre and M6tayer to describe the systematic construction of parallel programs without introducing artificial sequentiality. This paper presents two synchronous execution models for GAMMA and discusses how to implement them on MasPar MP-1, a massively data parallel computer. The results show that GAMMA paradigm can be implemented very naturally on data parallel machines, and very high level language, such as GAMMA in which parallelism is left implicit, is suitable for specifying massively parallel applications.展开更多
Speedup is considered as the criterion of determining whether a parallel algorithm is optimal. But broadcast-class problems, existing only on parallel computer system, have no sequential algorithms at all. Speedup sta...Speedup is considered as the criterion of determining whether a parallel algorithm is optimal. But broadcast-class problems, existing only on parallel computer system, have no sequential algorithms at all. Speedup standard becomes invalid here. Through this research on broadcast algorithms under several typical parallel computation models,a model-independent evaluation standard min C2 is developed, which can be not only used to determine an optimal broadcasting algorithm, but also normalized to apply to any parallel algorithm. As a new idea, min C2 will lead to a new way in this field.展开更多
基金supported by the National Natural Science Foundation of China(Grants 41374046 and41174034)
文摘We present numerical modeling of SH-wave propagation for the recently proposed whole Moon model and try to improve our understanding of lunar seismic wave propagation. We use a hybrid PSM/FDM method on staggered grids to solve the wave equations and implement the calculation on a parallel PC cluster to improve the computing efficiency. Features of global SH-wave propagation are firstly discussed for a 100-km shallow and900-km deep moonquakes, respectively. Effects of frequency range and lateral variation of crust thickness are then investigated with various models. Our synthetic waveforms are finally compared with observed Apollo data to show the features of wave propagation that were produced by our model and those not reproduced by our models. Our numerical modeling show that the low-velocity upper crust plays significant role in the development of reverberating wave trains. Increasing frequency enhances the strength and duration of the reverberations.Surface multiples dominate wavefields for shallow event.Core–mantle reflections can be clearly identified for deep event at low frequency. The layered whole Moon model and the low-velocity upper crust produce the reverberating wave trains following each phases consistent with observation. However, more realistic Moon model should be considered in order to explain the strong and slow decay scattering between various phases shown on observation data.
文摘The GAMMA paradigm is recently proposed by Banatre and M6tayer to describe the systematic construction of parallel programs without introducing artificial sequentiality. This paper presents two synchronous execution models for GAMMA and discusses how to implement them on MasPar MP-1, a massively data parallel computer. The results show that GAMMA paradigm can be implemented very naturally on data parallel machines, and very high level language, such as GAMMA in which parallelism is left implicit, is suitable for specifying massively parallel applications.
文摘Speedup is considered as the criterion of determining whether a parallel algorithm is optimal. But broadcast-class problems, existing only on parallel computer system, have no sequential algorithms at all. Speedup standard becomes invalid here. Through this research on broadcast algorithms under several typical parallel computation models,a model-independent evaluation standard min C2 is developed, which can be not only used to determine an optimal broadcasting algorithm, but also normalized to apply to any parallel algorithm. As a new idea, min C2 will lead to a new way in this field.
