排序方式: 共有13条查询结果,搜索用时 15 毫秒
1.
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
2.
3.
4.
5.
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
6.
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
7.
8.
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
9.
用扫描隧道显微镜[1-3](STM)探测原子量级的表面结构,是大家熟知的.除了观察材料表面的原子和分子外,在工业上人们常用STM来研究样晶的表面特征,扫描范围可以从0.01μm到 200.00 μm..这样的分辨率,扫描电镜(SEM)也能达到.不过,SEM测不出Z方向的微小距离,而STM却可保持在Z方向有较高的分辨率.因此,在工业上用STM观察在Z方向有微小高差特征的表面结构,例如光滑轴承表面的抛光情况,衍射光栅上锯齿形刻槽的深度,圆珠笔中圆珠表面的粗糙程度等,是十分有效的.这里,我们将介绍用STM测量袖珍唱片(CD)和集成电路(IC)所得到的结果. CD片… 相似文献
10.