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41.
Exact analytical solutions of in-plane static problems of circular beams with uniform cross-section made of functionally graded material (FGM) are obtained. Material properties are assumed to be varying arbitrarily through the thickness. The effects of axial extension and shear deformations are considered. The differential equation system is solved exactly using the initial values method. The circumferential stress distribution on the cross-section is also obtained. The results are compared with those of rather complex approaches in the literature, such as elasticity approach, and the comparison shows an excellent agreement. Effects of power law exponent and radius-to-height ratio of the beam on circumferential stress distribution and displacements are investigated. 相似文献
42.
Ekmel Ozbay Irfan Bulu Koray Aydin Humeyra Caglayan Kaan Guven 《Photonics and Nanostructures》2004,2(2):87-95
In this article, we investigate how the photonic band gaps and the variety of band dispersions of photonic crystals can be utilized for various applications and how they further give rise to completely novel optical phenomena. The enhancement of spontaneous emission through coupled cavity waveguides in a one-dimensional silicon nitride photonic microcrystal is investigated. We then present the highly directive radiation from sources embedded in two-dimensional photonic crystals. The manifestation of novel and intriguing optical properties of photonic crystals are exemplified experimentally by the negative refraction and the focusing of electromagnetic waves through a photonic crystal slab with subwavelength resolution. 相似文献
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H. Aydin Sh. A. Mansour C. Aydin Ahmed A. Al-Ghamdi Omar A. Al-Hartomy Farid El-Tantawy F. Yakuphanoglu 《Journal of Sol-Gel Science and Technology》2012,64(3):728-733
Boron doped NiO films were prepared by sol–gel method. The effects of B content on the morphological and optical properties of NiO films were studied with atomic force microscopy, and optical characterization method. The average transmittance at the visible region is reached to 75 % for lower doped films (0.1 and 0.2 % B), whereas, the recorded average value of transmittance was about 62 % for doped film with 1 % B throughout the region. The optical energy gap value for pure NiO film was found to be 3.73 eV. These values were affected by B doping with non-monotonic variation and reached to 3.64 eV for 0.1 % B doped NiO. Also, the refractive index dispersion and dielectric constants of the NiO films were studied throughout the investigated range of wavelengths. The obtained results indicate that the optical parameters of the NiO film are controlled with boron doping. 相似文献
46.
The 1,2-bis-(2-benzimidazolyl)-1,2-ethanediol (EH2) and 1,4-bis-(2-benzimidazolyl)-1,2,3,4-butanetetraol (TH4) ligands form 4-coordinate mono- and bi-metallic complexes with PdCl2, respectively. In Pd(EH2)Cl2 the ligand acts as a bidentate through two of the nitrogen atoms. On the other hand, in Pd2(TH4)Cl4 the ligand coordinates to two palladium atoms through both bis-benzimidazole nitrogen atoms and two oxygen atoms of the hydroxy groups, forming two different isomers. The complexes were characterised by analytical data, magnetic susceptibility, molar conductivity, and also by i.r., 1H- and 13C-n.m.r. spectra. 相似文献
47.
In this study, thermally developing laminar forced convection in a pipe including viscous dissipation and wall conductance
is investigated numerically. The constant heat flux is assumed to be imposed at the outer surface of the pipe wall. The finite
volume method is used. The distributions for the developing temperature and local Nusselt number in the entrance region are
obtained. The dependence of the results on the Brinkman number and the dimensionless thermal conductivity are shown. The viscous
heating effect on the wall is shown. Significant viscous dissipation effects have been observed for large Br. 相似文献
48.
Russian Journal of Organic Chemistry - Chiral oxazoline ligands containing an aromatic ring were prepared from norephedrine and pyrrole-2-carbonitrile or 2-hydroxybenzoyl chloride. The synthesized... 相似文献
49.
We consider the quasilinear systems of difference equations with periodic coefficients in linear terms. We obtain estimates for the attraction domain of the zero solution and establish inequalities for the norms of solutions. The results are stated in terms of Lyapunov-type matrix series. 相似文献
50.
A multi-element preconcentration-separation technique for heavy metal ions in environmental samples has been established. The procedure is based on coprecipitation of gold(III), bismuth(III), cobalt(II), chromium(III), iron(III), manganese(II), nickel(II), lead(II), thorium(IV) and uranium(VI) ions by the aid of Cu(II)-9-phenyl-3-fluorone precipitate. The Cu(II)-9-phenyl-3-fluorone precipitate was dissolved by the addition 1.0 mL of concentrated HNO3 and then the solution was completed to 5 mL with distilled water. Iron, lead, cobalt, chromium, manganese and nickel levels in the final solution were determined by flame atomic absorption spectrometer, while gold, bismuth, uranium and thorium were determined by inductively coupled plasma mass spectrometer. The optimal conditions are pH 7, amounts of 9-phenyl-3-fluorone: 5 mg and amounts of Cu(II): 1 mg. The effects of concomitant ions as matrix were also examined. The preconcentration factor was 30. Gold(III), bismuth(III), chromium(III), iron(III), lead(II) and thorium(IV) were quantitatively recovered from the real samples. The detection limits for the analyte elements based on 3 sigma (n = 15) were in the range of 0.05-12.9 μg L−1. The validation of the presented procedure was checked by the analysis of two certified reference materials (Montana I Soil (NIST-SRM 2710) and Lake Sediment (IAEA-SL-1)). The procedure was successfully applied to some environmental samples including water and sediments. 相似文献