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Maliheh Khatibi Moghaddam Amir Reza Attari Mir Mojtaba Mirsalehi 《Photonics and Nanostructures》2010,8(1):47-53
We investigate a photonic crystal (PC) waveguide coupler which is formed by two closely spaced linear waveguides in a two-dimensional triangular lattice of air holes. Our study shows that shifting one row of the air holes between the waveguides affects the dispersion curves of the guided modes and if the triangular lattice of air holes between the waveguides is replaced by a rectangular lattice, this modification results in an ultra-short coupling structure with coupling length less than 3a, where a is the lattice constant. Also, we investigate the effect of changing the radii of air holes that are adjacent to or between the waveguides on the coupling length and show that increasing the radius of air holes between the waveguides decreases the coupling length. We analyze the output spectrum of an ultra-short channel drop filter designed based on this structure. 相似文献
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Reza Sepahvand Mohsen Adeli Bandar Astinchap Roya Kabiri 《Journal of nanoparticle research》2008,10(8):1309-1318
Metal-carbon nanotube-graft-polymer (MCNT-g-P) nanocomposites were synthesized and characterized successfully. In this work, multiwall carbon nanotubes (MWCNT) were
opened using HNO3/H2SO4 mixture and filled by metal nanoparticles such as silver nanoparticles through wet chemistry method. Then MWCNT containing
metal nanoparticles were used as macroinitiator for ring opening polymerization of ε-caprolactone and MCNT-g-P nanocomposites were obtained. Length of grafted polymer arms onto the MWCNT was controlled using MWCNT/ε-caprolactone ratio.
Structure and properties of nanocomposites were evaluated by TEM, DSC, TGA, and spectroscopy methods. 相似文献
228.
Dizaji RM Chapman NR Kirlin RL 《The Journal of the Acoustical Society of America》2002,111(2):800-808
An inversion method based on the concept of back wave propagation (BWP) is described in this paper for estimation of geoacoustic parameters from acoustic field data. A phase-regulation technique is introduced to increase the sensitivity of the method for geoacoustic model parameters having low sensitivity. The case of data consisting of signal plus additive noise is also addressed. It is shown theoretically that the sensitivity can be increased by a factor alpha using the phase regulation procedure, and that the spatial resolution of signal energy that is concentrated by BWP at the known source position is increased when a increases. This result suggests an effective criterion for use in the inversion, based on the spatial distribution of signal energy around the true source location. The basis for the criterion is the spatial variance of the back-propagated pressure field in a window around the known source location. A multistep search process is proposed to avoid using a complicated multidimensional search process. Inversion results from both simulations and experimental data are given. The real data were taken from the Pacific Shelf experiment carried out in shallow water off the West Coast of Vancouver Island in the Northeast Pacific Ocean. 相似文献
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A new, mild, and novel method is described for the efficient deoxygenation of sulfoxides to their corresponding sulfides with 1,3-dithiane at room temperature in the presence of catalytic amounts of N-bromosuccinimide (NBS), 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TABCO), or Br(2) as the source of electrophilic bromine. 相似文献
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Mohammad Reza R. Moghaddam 《Monatshefte für Mathematik》1984,97(3):191-206
The present paper is devoted to calculation of the Baer-invariants of the dihedral and the quaternion groups of order 8, and also a certain class ofp-groups with respect to the variety of nilpotent groups. 相似文献