The Tilted tilted transversely isotropic(TTI)media,a kind of anisotropic medium,widely exists within the earth.For faster calculation of travel times in the TTI anisotropic media,we modifi ed a minimum traveltime tree...The Tilted tilted transversely isotropic(TTI)media,a kind of anisotropic medium,widely exists within the earth.For faster calculation of travel times in the TTI anisotropic media,we modifi ed a minimum traveltime tree algorithm with high effi ciency by dynamical modifi cation of the secondary wave propagation region during the spread of seismic waves.To manage the wavefront points in the modified version,we used a novel minimum heap sorting technique to reduce the time spent on selecting secondary waves points.In this study,seismic group velocities were obtained from analytical solutions in terms of phase angle,and the corresponding phase angles were determined by binary search rather than approximate equations for weakly anisotropic media.For the most time-consuming part of the secondary wave traveltime calculation,the parallel computation was initially performed using multiple cores and threads.Numerical examples showed that the improved method can calculate seismic travel times and ray paths faster and accurately in a 3D TTI medium.For four cores and eight threads,the computing speed increased by six times when compared to the conventional method.展开更多
A precedence order is defined based on the release dates of jobs＇ direct successors. Using the defined precedence order and Heap Sort, a new polynomial algorithm is provided which aims to solve the parallel schedulin...A precedence order is defined based on the release dates of jobs＇ direct successors. Using the defined precedence order and Heap Sort, a new polynomial algorithm is provided which aims to solve the parallel scheduling problem P｜pj = 1, r j, outtree｜ ∑Cj Cj. The new algorithm is shown to be more compact and easier to implement.展开更多
基金funded by the National Key R&D Program of China (No. 2020YFA0710600)National Science Foundation of China (No. 41374098)the Special Fund of the Institute of Geophysics,China Earthquake Administration (No. DQJB19B40)
文摘The Tilted tilted transversely isotropic(TTI)media,a kind of anisotropic medium,widely exists within the earth.For faster calculation of travel times in the TTI anisotropic media,we modifi ed a minimum traveltime tree algorithm with high effi ciency by dynamical modifi cation of the secondary wave propagation region during the spread of seismic waves.To manage the wavefront points in the modified version,we used a novel minimum heap sorting technique to reduce the time spent on selecting secondary waves points.In this study,seismic group velocities were obtained from analytical solutions in terms of phase angle,and the corresponding phase angles were determined by binary search rather than approximate equations for weakly anisotropic media.For the most time-consuming part of the secondary wave traveltime calculation,the parallel computation was initially performed using multiple cores and threads.Numerical examples showed that the improved method can calculate seismic travel times and ray paths faster and accurately in a 3D TTI medium.For four cores and eight threads,the computing speed increased by six times when compared to the conventional method.
基金This work was supported by the National Natural Science Foundation of China(No.60474023)Science and Technology Key Project Fund of theMinistry of Education(No.03184)the Major State Basic Research Development Program of China(No.2002CB312200).
文摘A precedence order is defined based on the release dates of jobs＇ direct successors. Using the defined precedence order and Heap Sort, a new polynomial algorithm is provided which aims to solve the parallel scheduling problem P｜pj = 1, r j, outtree｜ ∑Cj Cj. The new algorithm is shown to be more compact and easier to implement.
