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Calculation of resonant sound absorption parameters for performance evaluation of metal rubber material 总被引:1,自引:0,他引:1
The first resonant (anti-resonant) frequency and sound absorption coefficient of metal rubber (MR) material are theoretically
studied with hard backed samples and with air layer. The equations of the first resonant and anti-resonant frequencies of
MR are deduced from the undamped propagation characteristics of porous material. The first resonant and anti-resonance sound
absorption coefficients are induced according to the theoretical formula for the acoustic characteristic parameters of MR,
and the former is modified while the energy consumption at resonance is taken into consideration. The good agreement between
the calculation results of these resonant sound absorption parameters and the experimental results verifies the effectiveness
of this calculation method for the performance evaluation of MR as a sound absorption material. 相似文献
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An all-coefficient adaptive control method for a class of nonlinear time-varying systems 总被引:1,自引:0,他引:1
In this paper, the extension of the all-coefficient adaptive control method to nonlinear time-varying systems is studied. A novel discretizing method is first proposed to derive the discrete-time model for a class of nonlinear time-varying systems. The characteristics of the coefficients of the discrete-time model are derived by this method, based on which the all-coefficient adaptive control method is given for the class of nonlinear time-varying systems. Sufficient conditions on the closed-loop stability ... 相似文献
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1国内互联网发展简况 互联网发展到今天已经越来越实用化,社会各界对互联网的需求日趋强烈。根据中国互联网络信息中心2005年7月发布的“第16次中国互联网络发展状况统计报告”,截止到6月30日,我国上网用户总数为1.03亿人,其中宽带用户为5300万人,上网计算机总数为4560万台,网站总数67.7万个,cn下注册的域名总数为62.25万个, 相似文献
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Xue GuoQi Liu Lijuan WangHexiang Huang Dandan YangMei-Ling Cheng 《Materials Science and Engineering: B》2012,177(3):321-326
Multi-pods Au/FeOOH nanostructures were synthesized by a hydrothermal treatment of an aqueous solution of mixed micellar formed by gold nanoparticles, hexadecyltrimethyl ammonium bromide (CTAB), and (NH4)3[FeF6] at 160 °C for 48 h and sequential calcined at 290 °C for 1.5 h, resulting in the formation of multi-pods Au/Fe2O3 nanostructures. The as-obtained products were characterized by powder X-ray diffraction, transmission electron microscopy, selected area electron diffraction, field emission scanning electron microscopy, and UV-vis spectroscopy. Surface plasmon resonance band of gold nanoparticles was observed in the multi-pods Au/FeOOH nanostructures. However, a similar behavior was not seen with multi-pods Au/Fe2O3 nanostructures. The critical role of F− ions and CTAB molecules in the formation of FeO(OH) multipods and the probable mechanism of the formation of multi-pods Au/FeOOH and Au/Fe2O3 nanostructures were discussed. 相似文献
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Peng ZhangHongyan Hu Yuanyuan LiuYue Zhang Yuan FangXuejun Ren Bo LiaoQingxiang Yang 《Materials Science and Engineering: A》2011,528(3):1201-1204
Twin-roll strip casting technology is a new one to produce austenite stainless steel strip directly. However, during this process, the cracking occurs usually on the surface of the steel strip. The technique of in situ tension in transmission electron microscope was used to observe and analyze the crack initiation and propagation in austenite stainless steel produced by twin-roll strip casting technology in this work. The results show that the crack initiates in dislocation free-zone firstly and then propagates along the direction vertical to the tensile force. The crack may propagate in continuous propagation way and discontinuous one respectively. When the shear stress on the close-packing face and the normal stress on the secondary close-packing face are at the same side of the tensile force, the cracks propagate continuously. However, when the shear stress on the close-packing face and the normal stress on the secondary close-packing face are in two sides, the cracks propagate discontinuously. 相似文献
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