In this paper, by using the fast iterative method of mode decomposition[12], source range-depth localization performance of MMP for three kinds of vertical array (short, sparse and short-sparse arrays) in shallow wate...In this paper, by using the fast iterative method of mode decomposition[12], source range-depth localization performance of MMP for three kinds of vertical array (short, sparse and short-sparse arrays) in shallow water with a downward refraction sound-speed profile in the surnmertime is discussed; the accuracy of mode decomposition is measured by its rootmean-square error, RMS. The numerical results illustrate that the accuracy of source range and depth estimation are raised and the sidelobes are effectively suppressed. The short-sparse vertical array not only has shorter length and fewer hydrophones, but also can be applied to the different sea areas with various depth, so it is a practical type of vertical arrny in the engineering project of the passive source localization.展开更多
Ground motions are significantly influenced by dynamic characteristics of overburden soil layers near ground surface,as thick and soft soil layers would obviously amplify the ground motion strength. The conventional r...Ground motions are significantly influenced by dynamic characteristics of overburden soil layers near ground surface,as thick and soft soil layers would obviously amplify the ground motion strength. The conventional research method on soil nonlinear dynamic characteristics under strong motions is based on experiments in laboratories for the deficiency of observation data,but it is difficult to reliably simulate the complex factors of soils in actual earthquake durations,including loading paths,boundary conditions,and drainage conditions. The incremental data of the vertical downhole observation array,which is comprised of at least one observation point on ground surface and one observation point in a downhole rock base, makes it possible to study soil nonlinear dynamics according to in situ observation data,and provides new basic data and development opportunities to soil nonlinear dynamics studies.展开更多
文摘In this paper, by using the fast iterative method of mode decomposition[12], source range-depth localization performance of MMP for three kinds of vertical array (short, sparse and short-sparse arrays) in shallow water with a downward refraction sound-speed profile in the surnmertime is discussed; the accuracy of mode decomposition is measured by its rootmean-square error, RMS. The numerical results illustrate that the accuracy of source range and depth estimation are raised and the sidelobes are effectively suppressed. The short-sparse vertical array not only has shorter length and fewer hydrophones, but also can be applied to the different sea areas with various depth, so it is a practical type of vertical arrny in the engineering project of the passive source localization.
基金funded by the Special Research Fund for Seismology(201408020)the Natural Science Foundation of China (51578514,U1434210)
文摘Ground motions are significantly influenced by dynamic characteristics of overburden soil layers near ground surface,as thick and soft soil layers would obviously amplify the ground motion strength. The conventional research method on soil nonlinear dynamic characteristics under strong motions is based on experiments in laboratories for the deficiency of observation data,but it is difficult to reliably simulate the complex factors of soils in actual earthquake durations,including loading paths,boundary conditions,and drainage conditions. The incremental data of the vertical downhole observation array,which is comprised of at least one observation point on ground surface and one observation point in a downhole rock base, makes it possible to study soil nonlinear dynamics according to in situ observation data,and provides new basic data and development opportunities to soil nonlinear dynamics studies.
