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181.
M. Abolhassani  Y. Rostami 《Optik》2012,123(10):937-939
One of the common problems in classical and digital holography is presence of speckle in reconstructed images. Some methods have been predicted for speckle reduction. Speckle has a statistical distribution in size and intensity. Thus complete elimination of them is impossible. But, one can use this statistical characters to reduce its effects.In this paper a method is proposed for reduction of speckle effect by recording a hologram and then dividing it to several sub-holograms. Each sub-hologram is used to produce an image. Final image is constructed by superposition of these images. The final image has a smaller amount of speckle noise. Experimental results verify effectiveness of this technique.  相似文献   
182.
183.
Russian Journal of Organic Chemistry - A highly efficient procedure for the one-pot synthesis of polysubstituted pyrrole derivatives by the reaction between of aniline derivatives, β-diketones...  相似文献   
184.
Solution‐processed ultraviolet photodetectors based on passivated and unpassivated zinc oxide (ZnO) nanorods, in which the ZnO nanoparticles are synthesized by a hydrothermal method, are demonstrated and characterized. Photoconductive photodetectors fabricated using simple solution processing have recently been shown to exhibit high gains and outstanding sensitivities. One ostensible disadvantage of exploiting photoconductive gain is that the temporal response is limited by the release of carriers from trap states. Herein, specific chemical species are introduced onto the surfaces of ZnO nanoparticles to produce desired trap states with a carefully selected lifetime. Compared with conventional photodetectors based on ZnO nanoparticles, the proposed UV photodetectors have much higher photoresponses and faster response times in the UV region. The photoconductive gain of the fabricated photodetectors varies from 26.83 to 2.32×102 for passivated samples, which indicates high gain. The best temporal response for the fabricated detectors is 34 ms rise time and 132 ms decay time for ZnO nanoparticles passivated by hexamethylenetetramine.  相似文献   
185.
Generalizations of M-matrices which may not have a nonnegative inverse   总被引:1,自引:0,他引:1  
Generalizations of M-matrices are studied, including the new class of GM-matrices. The matrices studied are of the form sI-B with B having the Perron-Frobenius property, but not necessarily being nonnegative. Results for these classes of matrices are shown, which are analogous to those known for M-matrices. Also, various splittings of a GM-matrix are studied along with conditions for their convergence.  相似文献   
186.
This paper deals with the existence and the characteristics of the limit cycles in the fractional-order Arneodo system. The analysis is done using the describing function method. Our focus is on a special case where two limit cycles exist. The parametric range for the case of interest is derived, and the frequency and the amplitude of the oscillation are predicted. Numerical simulation results are presented to further demonstrate the reliability of the analysis.  相似文献   
187.
A straightforward and an efficient method for the synthesis of 2H‐pyrans via the one‐pot, reaction of alkyl bromides, carbon disulfide, secondary amines, activated acetylenes and isocyanides under solvent‐free conditions without using any catalyst at room temperature is reported. The method offers several advantages including high yields of products and an easy work‐up procedure. J. Heterocyclic Chem., (2011).  相似文献   
188.
A technique for probing the sample interior using the leading edge of an alternating evanescent magnetic field is suggested. It makes it possible to highlight and study physical processes taking place at the vortex front in superconductors. Successively increasing the field amplitude by equal amounts, one can study the formation and transformation of the magnetic microstructure in response to variation of the sample’s crystal microstructure. For samples with different microstructures, qualitatively new results are obtained. The technique suggested may be used for testing high-temperature superconductor epitaxial films and magnetic materials.  相似文献   
189.
Structurally diverse aromatic aldehydes were thioacetalated in a clean and efficient reaction with ethane‐1, 2‐dithiol and thiophenol based on the use of I2 generated in situ from Fe(NO3)3.9H2O/NaI. The reaction occurs in good to high yield in dichloromethane at room temperature and the use of toxic and corrosive molecular iodine is avoided.  相似文献   
190.
A one-pot triphenylarsine-catalyzed synthesis of trans-cyclopropane derivatives is achieved by means of the reaction between acetylenic esters and C-H acids in the presence of triphenylarsine. This procedure is simple and proceeds under mild reaction conditions. Its success depends on the choice of solvent, temperature and C-H acid used.  相似文献   
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