In this paper, a transfer matrix and a three-dimensional dynamic response of a layered half-space to an arbitrary buried source are derived with the aid of a technique which combines the Laplace and two-dimensional Fo...In this paper, a transfer matrix and a three-dimensional dynamic response of a layered half-space to an arbitrary buried source are derived with the aid of a technique which combines the Laplace and two-dimensional Fourier transforms in a rectangular coordinate system. This method is clear in concept, and the corresponding formulas given in the paper are simple and convenient for marine seismic prospecting and other fields' applications. An example is presented and the calculated results are in good agreement with those of the finite element method (FEM).展开更多
In this study, we attempt the analysis of the passage flow in the centrifugal impeller using FEM with/without the turbulence model, and compare this result with the experimental result. The turbulence model is the low...In this study, we attempt the analysis of the passage flow in the centrifugal impeller using FEM with/without the turbulence model, and compare this result with the experimental result. The turbulence model is the low Reynolds k-ε model proposed by Chien. We use the GSMAC method for the Reynolds averaged Navier-Stokes equstions, the Euler explicit method for the transport equations of the turbulent kinetic energy and the dissipation rate. All equations are discretized by the Galerkin’s method. At the midpassage of the centrifugal impeller the passagewise velocity component tends to increase in the pressure-to-suction direction, and the other component toward the pressure surface tends to be large in the region of the middle blade-to-blade to the hub side. The tip leakages appear around the region of the middle blade-to-blade near the casing together with the secondary flow toward the suction surface. These phenomena correspond with the experimental result, qualitatively.展开更多
In the deep Earth, hydrogen mainly occurs as structural hydroxyl and molecular water in minerals and melts, constituting mobile and immobile aqueous components. Hydrous minerals contain hydrogen which occupies a speci...In the deep Earth, hydrogen mainly occurs as structural hydroxyl and molecular water in minerals and melts, constituting mobile and immobile aqueous components. Hydrous minerals contain hydrogen which occupies a specific structural position and constitutes an indispensable component of chemical formulae. On the other hand, nominally anhydrous minerals do not contain hydrogen in their chemical formulae, but can host trace amounts of water in structural position and lattice defect. The molecular water may occur in the lattice defect as fluid/melt inclusions in minerals. Even though the water content of nominally anhydrous minerals is very limited generally in the order of ppm(parts per million), they may play a significant role in influencing the physicochemical properties of mineral and rock systems. With the continuous improvement of modern instrumentations, the analytical methodology exhibits trends for higher spatial resolution, lower detection limit and integral multiple methods on the water amount and its isotopic ratio. Among these methods, Fourier transform infrared spectrometry remains the most widely used, while secondary ion mass spectrometry, continuous flow mass spectrometry, elastic recoil detection analysis and Raman spectrometry are promising. This paper provides a brief review on the methodological progress and their applications to the analysis of structural water in nominally anhydrous minerals.展开更多
基金funded by the Natural Science Foundation Projeet of State(40174030)the Natural Science Foundation Project of Shandong Province(Y2000E05)
文摘In this paper, a transfer matrix and a three-dimensional dynamic response of a layered half-space to an arbitrary buried source are derived with the aid of a technique which combines the Laplace and two-dimensional Fourier transforms in a rectangular coordinate system. This method is clear in concept, and the corresponding formulas given in the paper are simple and convenient for marine seismic prospecting and other fields' applications. An example is presented and the calculated results are in good agreement with those of the finite element method (FEM).
文摘In this study, we attempt the analysis of the passage flow in the centrifugal impeller using FEM with/without the turbulence model, and compare this result with the experimental result. The turbulence model is the low Reynolds k-ε model proposed by Chien. We use the GSMAC method for the Reynolds averaged Navier-Stokes equstions, the Euler explicit method for the transport equations of the turbulent kinetic energy and the dissipation rate. All equations are discretized by the Galerkin’s method. At the midpassage of the centrifugal impeller the passagewise velocity component tends to increase in the pressure-to-suction direction, and the other component toward the pressure surface tends to be large in the region of the middle blade-to-blade to the hub side. The tip leakages appear around the region of the middle blade-to-blade near the casing together with the secondary flow toward the suction surface. These phenomena correspond with the experimental result, qualitatively.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41373010 & 41590624)
文摘In the deep Earth, hydrogen mainly occurs as structural hydroxyl and molecular water in minerals and melts, constituting mobile and immobile aqueous components. Hydrous minerals contain hydrogen which occupies a specific structural position and constitutes an indispensable component of chemical formulae. On the other hand, nominally anhydrous minerals do not contain hydrogen in their chemical formulae, but can host trace amounts of water in structural position and lattice defect. The molecular water may occur in the lattice defect as fluid/melt inclusions in minerals. Even though the water content of nominally anhydrous minerals is very limited generally in the order of ppm(parts per million), they may play a significant role in influencing the physicochemical properties of mineral and rock systems. With the continuous improvement of modern instrumentations, the analytical methodology exhibits trends for higher spatial resolution, lower detection limit and integral multiple methods on the water amount and its isotopic ratio. Among these methods, Fourier transform infrared spectrometry remains the most widely used, while secondary ion mass spectrometry, continuous flow mass spectrometry, elastic recoil detection analysis and Raman spectrometry are promising. This paper provides a brief review on the methodological progress and their applications to the analysis of structural water in nominally anhydrous minerals.
