The major element composition of sound-producing sand is reported together with rare-earth elements (REE) and other selected elements for the first time. Rare-earth element concentrations in beach sands from Miyagi an...The major element composition of sound-producing sand is reported together with rare-earth elements (REE) and other selected elements for the first time. Rare-earth element concentrations in beach sands from Miyagi and Tottori in Japan were determined by induction-coupled, argon-plasma spectrometry (ICP-MS) to characterize the REE of sound-producing and silent sands relative to the parental rocks. Sound-producing sand beaches are very common and all over in Japan: five beaches in Miyagi and 2 in Tottori are selected with other silent sand beaches in the areas. Both sound-producing sand and silent sand samples from Miyagi and Tottori contain more than 60wt% of SiO2 and are composed mainly of quartz and feldspar. Miyagi sand samples are characterized by light REE enrichment and flat chondrite-normalized patterns that are similar to those of local source sandstone. However, all sand samples from Miyatojima in Miyagi show positive Eu anomalies, a characteristic feature not shown in other sand samples from Miyagi. Tottori sand samples also are characterized by high REE contents and remarkable positive Eu anomalies. The sands containing lower REE contents are due to high quartz and feldspar contents. Miyatojima sand samples and Tottori sand samples have high REE contents and show remarkable positive Eu anomalies due to the presence of feldspar. The best results are obtained using all of the geological methods and the Principal Component Analysis (PCA) as a measure of the similarity between sound-producing sand and silent sand. The difference between sound-producing sand and silent sand is obtained from the PCA results.展开更多
A finite element algorithm combined with divergence condition was presented for computing three-dimensional(3D) magnetotelluric forward modeling. The finite element equation of three-dimensional magnetotelluric forwar...A finite element algorithm combined with divergence condition was presented for computing three-dimensional(3D) magnetotelluric forward modeling. The finite element equation of three-dimensional magnetotelluric forward modeling was derived from Maxwell's equations using general variation principle. The divergence condition was added forcedly to the electric field boundary value problem, which made the solution correct. The system of equation of the finite element algorithm was a large sparse, banded, symmetric, ill-conditioned, non-Hermitian complex matrix equation, which can be solved using the Bi-CGSTAB method. In order to prove correctness of the three-dimensional magnetotelluric forward algorithm, the computed results and analytic results of one-dimensional geo-electrical model were compared. In addition, the three-dimensional magnetotelluric forward algorithm is given a further evaluation by computing COMMEMI model. The forward modeling results show that the algorithm is very efficient, and it has a lot of advantages, such as the high precision, the canonical process of solving problem, meeting the internal boundary condition automatically and adapting to all kinds of distribution of multi-substances.展开更多
A higher-order acoustic-displacement based finite element procedure is presented in this paper to investigate one-dimensional sound propagation through a solid and the associated transmission loss. The acoustic system...A higher-order acoustic-displacement based finite element procedure is presented in this paper to investigate one-dimensional sound propagation through a solid and the associated transmission loss. The acoustic system consists of columns of standard air and a solid, with the upstream column of air subjected to a sinusoidal sound source. The longitudinal wave propagation in each medium is modeled using three-node finite elements. At the interfaces between the air and the solid medium, the continuity in acoustic displacements and the force equilibrium conditions are enforced. The Lagrange multipliers method is utilized to assemble the global equations of motion for the acoustic system. Numerical results obtained for various test cases using the procedure described in the paper are in excellent agreement with the analytical solutions and other independent solutions available in the literature.展开更多
To understand the characteristics of impact-sound transmission through a floor is very helpful for developing sound attenuation strategies to acquire a high quality of dwellings. Sound transmission through a floating ...To understand the characteristics of impact-sound transmission through a floor is very helpful for developing sound attenuation strategies to acquire a high quality of dwellings. Sound transmission through a floating floor to the room underneath was modeled by finite-element method (FEM). The sound pressure levels calculated by the FEM model on a scale of 1:4 was compared with the measured values, which demonstrate good agreement, particularly for impact sound of a relatively low frequency. The sound pressure level in a receiving room is strongly affected by the structural characteristics of both the floor and the room. The sound pressure transmitted through a clamped floor is lower than through a simply supported floor because of the larger rigidity of the clamped floor that contributes to the attenuation mechanism of stiffness. Increase in the thickness of the fiber-glass damping layer in the floor improves sound insulation. A larger room has a larger capacity to dissipate the sound pressure and thus has a lower sound pressure level. An asymmetric configuration of room avails sound attenuation because it has weaker structural and acoustic coupling than a symmetric one.展开更多
文摘The major element composition of sound-producing sand is reported together with rare-earth elements (REE) and other selected elements for the first time. Rare-earth element concentrations in beach sands from Miyagi and Tottori in Japan were determined by induction-coupled, argon-plasma spectrometry (ICP-MS) to characterize the REE of sound-producing and silent sands relative to the parental rocks. Sound-producing sand beaches are very common and all over in Japan: five beaches in Miyagi and 2 in Tottori are selected with other silent sand beaches in the areas. Both sound-producing sand and silent sand samples from Miyagi and Tottori contain more than 60wt% of SiO2 and are composed mainly of quartz and feldspar. Miyagi sand samples are characterized by light REE enrichment and flat chondrite-normalized patterns that are similar to those of local source sandstone. However, all sand samples from Miyatojima in Miyagi show positive Eu anomalies, a characteristic feature not shown in other sand samples from Miyagi. Tottori sand samples also are characterized by high REE contents and remarkable positive Eu anomalies. The sands containing lower REE contents are due to high quartz and feldspar contents. Miyatojima sand samples and Tottori sand samples have high REE contents and show remarkable positive Eu anomalies due to the presence of feldspar. The best results are obtained using all of the geological methods and the Principal Component Analysis (PCA) as a measure of the similarity between sound-producing sand and silent sand. The difference between sound-producing sand and silent sand is obtained from the PCA results.
基金Project(60672042) supported by the National Natural Science Foundation of China
文摘A finite element algorithm combined with divergence condition was presented for computing three-dimensional(3D) magnetotelluric forward modeling. The finite element equation of three-dimensional magnetotelluric forward modeling was derived from Maxwell's equations using general variation principle. The divergence condition was added forcedly to the electric field boundary value problem, which made the solution correct. The system of equation of the finite element algorithm was a large sparse, banded, symmetric, ill-conditioned, non-Hermitian complex matrix equation, which can be solved using the Bi-CGSTAB method. In order to prove correctness of the three-dimensional magnetotelluric forward algorithm, the computed results and analytic results of one-dimensional geo-electrical model were compared. In addition, the three-dimensional magnetotelluric forward algorithm is given a further evaluation by computing COMMEMI model. The forward modeling results show that the algorithm is very efficient, and it has a lot of advantages, such as the high precision, the canonical process of solving problem, meeting the internal boundary condition automatically and adapting to all kinds of distribution of multi-substances.
文摘A higher-order acoustic-displacement based finite element procedure is presented in this paper to investigate one-dimensional sound propagation through a solid and the associated transmission loss. The acoustic system consists of columns of standard air and a solid, with the upstream column of air subjected to a sinusoidal sound source. The longitudinal wave propagation in each medium is modeled using three-node finite elements. At the interfaces between the air and the solid medium, the continuity in acoustic displacements and the force equilibrium conditions are enforced. The Lagrange multipliers method is utilized to assemble the global equations of motion for the acoustic system. Numerical results obtained for various test cases using the procedure described in the paper are in excellent agreement with the analytical solutions and other independent solutions available in the literature.
基金the Excellent Young Teacher Foundation of Henan Province under the grant No. [2005]461.
文摘To understand the characteristics of impact-sound transmission through a floor is very helpful for developing sound attenuation strategies to acquire a high quality of dwellings. Sound transmission through a floating floor to the room underneath was modeled by finite-element method (FEM). The sound pressure levels calculated by the FEM model on a scale of 1:4 was compared with the measured values, which demonstrate good agreement, particularly for impact sound of a relatively low frequency. The sound pressure level in a receiving room is strongly affected by the structural characteristics of both the floor and the room. The sound pressure transmitted through a clamped floor is lower than through a simply supported floor because of the larger rigidity of the clamped floor that contributes to the attenuation mechanism of stiffness. Increase in the thickness of the fiber-glass damping layer in the floor improves sound insulation. A larger room has a larger capacity to dissipate the sound pressure and thus has a lower sound pressure level. An asymmetric configuration of room avails sound attenuation because it has weaker structural and acoustic coupling than a symmetric one.
