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We give a characterization of structurally stable diffeomorphisms by making use of the notion of L
p
-shadowing property. More precisely, we prove that the set of structurally stable diffeomorphisms coincides with the C
1-interior of the set of diffeomorphisms having L
p
-shadowing property. 相似文献
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In this paper, the Lp(Rn)-boundedness of the commutators generalized by BMO(Rn) function and the singular integral operator T with rough kernel Ω∈ Llog+ L(Sn-1) is proved by using the Bony's formula for the paraproduct of two functions. 相似文献
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Hsicn-YangLin Chien-ChingMa 《Acta Mechanica Sinica》2002,18(2):95-102
Multilayer piezoelectric stack actuators are widely used in many industrial applications and the investigation on the dynamic behavior of this element is needed. In this study, two optical interferometric techniques called amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) and laser Doppler vibrometer (LDV) are used to experimentally investigate the vibration characteristics of a single-layer piezoelectric disc and a multilayer piezoelectric stack actuator. These two techniques are full-field measurement for AF-ESPI and point-wise displacement measurement for LDV. Because the clear fringe patterns obtained by the AF-ESPI method will be shown only at resonant frequencies, both the resonant frequencies and corresponding vibration mode shapes of the piezoelectric disc and the multilayer piezoelectric stack actuator are obtained simultaneously by the AF-ESPI method. Interferometric fringe patterns for both the in-plane and out-of-plane vibration mode shapes are demonstrated. In addition to the proposed two optical techniques, numerical computations based on a commercially available finite element package are presented for comparison with the experimental results. Good agreement between the measured data by experimental methods and the numerical results predicted by FEM is found in resonant frequencies and mode shapes for the single-layer piezoelectric disc. However, some discrepancies are observed for the results obtained by AF-ESPI and impedance analysis for the multilayer piezoelectric stack actuator. A detailed discussion is made to address important issues of this problem. 相似文献
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提出了一种同时嵌入鲁棒水印和易损水印的算法.利用离散小波变换的多分辨率特性以及离散余弦变换的解相关和能量压缩能力,在中低频区嵌入鲁棒水印;在小波域的高频区嵌入易损水印.水印的嵌入采用量化的方法,提取水印信号时不需要原始音频信号.实验结果表明,文中算法的水印鲁棒性高,适于音频作品的版权保护;而文中的易损水印对音频攻击具有很强的敏感性,可同时认证音频作品的内容完整性、 相似文献
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当你在闲暇之际,静心品味通过激光唱片放出的富有浪漫情调的优美乐曲时,是否考虑过激光唱片是谁发明的?它是集激光技术、计算机技术、数字技术、超大规模集成电路技术和精密机械技术于一身的高科技产品,蕴涵着许多科学知识。1877年美国大发明家爱迪生利用包有一层锡箔的圆筒来记录声音,人类从此进入了记录声音的新纪元。1895年贝利那通过对爱迪生录音技术的改造,将锡箔圆筒改为蜡质圆筒,随后又改为圆盘形蜡片,并将已录音的蜡片制成模板,进行大量复制。后来又改为虫胶压制唱片,并且采用发条来驱动唱片转动。这是唱片的第一次革命。唱片的第二次革命始于20世纪20年代。 相似文献