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991.
Based on the theories of nonlinear continuum mechanics, piezoelectricity and elastic waves in solids, theoretical analysis of Bleustein-Gulyaev surface acoustic wave propagation in a prestressed layered piezoelectric structure are described. Numerical calculations are performed for the case that the layer and the substrate are identical LiNbO(3) except that they are polarized in opposite directions. It is found that an almost linear behavior of the relative change in phase velocity versus the initial stress is obtained for both surface electrically free and shorted cases. Potential applications in the design of acoustic wave devices are suggested. 相似文献
992.
Ultracompact high-efficiency polarizing beam splitter with a hybrid photonic crystal and conventional waveguide structure 总被引:1,自引:0,他引:1
We propose an ultracompact high-efficiency polarizing beam splitter that operates over a wide wavelength range and is based on a hybrid photonic crystal and a conventional waveguide structure. Within a small area (15 microm x 10 microm), this polarizing beam splitter separates TM- and TE-polarized modes into orthogonal output waveguides. Results of simulations with the two-dimensional finite-difference time-domain method show that 99.3% of TM-polarized light is deflected by the photonic crystal structure (with a 28.0-dB extinction ratio), whereas 99.0% of TE-polarized light propagates through the structure (with a 32.2-dB extinction ratio). Wave vector diagrams are employed to explain the operation of a polarizing beam splitter. Tolerance analysis reveals a large tolerance to fabrication errors. 相似文献
993.
A simple optical interference method for fabricating two-dimensional square and trigonal lattices is demonstrated. A general formula for the interference contrast formed by two arbitrary polarized elliptical waves is deduced, the relation between wave vectors of incident light and the resultant pattern is analyzed, and polarization optimization of all beams to ensure uniform contrast is given. 相似文献
994.
M. Zhou Y.K. Zhang L. Cai J.Z. Zhou Z.H. Shen X.R. Zhang S.Y. Zhang 《Applied Physics A: Materials Science & Processing》2003,76(7):1113-1116
In this communication, we report a numerical model that predicts the mechanical deformations associated with the pulsed laser
irradiation of a film surface, based on thermal diffusion theory. The model is consequently advanced to produce a method for
evaluating film adhesion strength. The epicenter surface displacements within the irradiated fields have been measured using
a heterodyne interferometer. The comparison of the experimental data and the displacements calculated by the model shows good
agreement. By investigating the propagating acoustic modes under non-destructive and destructive modes, we reveal that, with
or without interface delamination, the phase structure of the longitudinal waves will be altered due to the change of reflection
mode at the interface. Applying shock dynamics theory, we evaluate the adhesion strength of the TiN/stainless interface. We
also indicate the strain rate can be up to 105∼106 s-1 during film interface delamination.
Received: 5 April 2002 / Accepted: 24 June 2002 / Published online: 26 February 2003
RID="*"
ID="*"Corresponding author. Fax: +86-511/879-1919, E-mail: mzhou@ujs.edu.cn 相似文献
995.
Chen Ximeng Wang Qiang Liu Zhaoyuan Cai Xiaohong Ma Shuxun Zhang Hualin 《Journal of Radioanalytical and Nuclear Chemistry》2003,258(1):189-190
The K X-ray relative transition probabilities Kb/Ka of some elements for atomic numbers 23Z33 induced by 3 MeV protons were measured. The experimental results are compared with the relativistic Hartree-Fock (RHF) calculations. Good agreements have been obtained considering the experimental error. 相似文献
996.
997.
Kawai K Takada T Nagai T Cai X Sugimoto A Fujitsuka M Majima T 《Journal of the American Chemical Society》2003,125(52):16198-16199
The hole transfer causes the long-lived charge-separated state in DNA during the photosensitized one-electron oxidation of DNA. The combination of the transient absorption measurement and DNA damage quantification by HPLC clearly demonstrated that the yield of the DNA damage correlates well with the lifetime of the charge-separated state. 相似文献
998.
Novel penniform superstructures of BaWO4 nanowires have been successfully synthesized in catanionic reverse micelles by using a double-hydrophilic block copolymer as the directing agent. This synthetic method is very simple, mild, and controllable, and it provides a novel method for direct solution-growth of hierarchical nanostructures based on inorganic nanowires. 相似文献
999.
[reaction: see text] A short and highly stereoselective synthesis of the novel steroid squalamine (1) was accomplished in nine steps from easily available methyl chenodeoxylcholanate 2. Our synthesis featured improved dehydrogenation of 4 followed by conjugate reduction to construct the trans AB-ring system and efficient asymmetric isopropylation of aldehyde 6 to introduce the C-24R-hydroxyl group. 相似文献
1000.
A series of novel chiral heterometal tetrahedral clusters have firstly been separated on cellulose tris-(3,5-dimethylphenylcarbamate) stationary phase by high-performance liquid chromatography using n-hexane as the mobile phase containing different alcohols as modifiers. The effects of concentration and structures of alcohols in the mobile phases and structures of chiral heterometal tetrahedral clusters on enantioseparation were investigated. The results showed that the concentration and structures of alcohols had large effects on enantioseparation. It also was found that both the metal in the tetrahedral core and the ligand coordinated to the atom in tetrahedral core had significant effects on their chromatographic behavior. 相似文献