This paper presents the method named acoustic holography which can be used to identify noise sources. A new formula of holography reconstruction is obtained, based on the Kirchhoff integral formula. Some simulating te...This paper presents the method named acoustic holography which can be used to identify noise sources. A new formula of holography reconstruction is obtained, based on the Kirchhoff integral formula. Some simulating tests are carried out using the new formula. The comparison with other reconstruction formulas proves that the new formula is more effective. By using acoustic holography method, some interesting results about the noise of a vehicle are shown. The results proves that acoustic holography is an effective method for the identification of the complex noise sources.展开更多
For the interior sound field formed by the complex vibrating structure, an identifi- cation approach of panel acoustic contribution based on equivalent source method （ESM） was presented. The normal velocity on the s...For the interior sound field formed by the complex vibrating structure, an identifi- cation approach of panel acoustic contribution based on equivalent source method （ESM） was presented. The normal velocity on the surface of vibrating structure was first reconstructed by using interior nearfield acoustic holography based on ESM and the prediction of whole interior enclosed sound field was realized. Then the sound pressure produced by each panel at the interested field point was respectively replaced by the radiated pressure of the enclosed interior sound field which is formed by the equivalent virtual sources located near the surface of the cav- ity. Combining with the reconstructed normal surface velocity, the acoustic contribution of each panel to any position in the cavity was obtained by transforming the complex enclosed non-free field into the simple interior free field. Numerical simulations and experiments are conducted, and the influences of the number of the equivalent sources and the distance between them and the reconstructed surface have been investigated. The results show that the proposed method is easier to be implemented with the same accuracy than the traditional analysis method.展开更多
Under low temperature stress,theplasmamembrane and chloroplast of plant cellsare impaired,resulting in electrolyte leakage and al-teration of chlorophyll fluorescence which can bemeasured with conductometer and fluore...Under low temperature stress,theplasmamembrane and chloroplast of plant cellsare impaired,resulting in electrolyte leakage and al-teration of chlorophyll fluorescence which can bemeasured with conductometer and fluoremeter.The cold tolerance of excised leaves of several ricevarieties were determined with these two instru-ments at seedling and heading stages to compare展开更多
基金This work wassupportedby the Natural Science Foundation of China(No.59775020).
文摘This paper presents the method named acoustic holography which can be used to identify noise sources. A new formula of holography reconstruction is obtained, based on the Kirchhoff integral formula. Some simulating tests are carried out using the new formula. The comparison with other reconstruction formulas proves that the new formula is more effective. By using acoustic holography method, some interesting results about the noise of a vehicle are shown. The results proves that acoustic holography is an effective method for the identification of the complex noise sources.
基金supported by the National Natural Science Foundation of China(11274087)
文摘For the interior sound field formed by the complex vibrating structure, an identifi- cation approach of panel acoustic contribution based on equivalent source method （ESM） was presented. The normal velocity on the surface of vibrating structure was first reconstructed by using interior nearfield acoustic holography based on ESM and the prediction of whole interior enclosed sound field was realized. Then the sound pressure produced by each panel at the interested field point was respectively replaced by the radiated pressure of the enclosed interior sound field which is formed by the equivalent virtual sources located near the surface of the cav- ity. Combining with the reconstructed normal surface velocity, the acoustic contribution of each panel to any position in the cavity was obtained by transforming the complex enclosed non-free field into the simple interior free field. Numerical simulations and experiments are conducted, and the influences of the number of the equivalent sources and the distance between them and the reconstructed surface have been investigated. The results show that the proposed method is easier to be implemented with the same accuracy than the traditional analysis method.
文摘Under low temperature stress,theplasmamembrane and chloroplast of plant cellsare impaired,resulting in electrolyte leakage and al-teration of chlorophyll fluorescence which can bemeasured with conductometer and fluoremeter.The cold tolerance of excised leaves of several ricevarieties were determined with these two instru-ments at seedling and heading stages to compare
