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41.
A global higher-order shear deformation theory is devised to obtain the governing equations of composite plates under dynamic excitation. The time-harmonic solution leads to an eigenvalue problem for the natural frequencies of plates. The eigenvalue problem for rectangular plates is converted to a set of homogenous algebraic equations using differential quadrature method. The formulation of the problem allows direct application of various boundary conditions. Therefore, rectangular plates with mixed boundary conditions are also considered. To show the validity of results, the fundamental natural frequencies of composite plates with different boundary conditions and those of isotropic plates with mixed boundary conditions are compared against the results available in the literature. 相似文献
42.
A. M. Baghestani A. R. Fotuhi S. J. Fariborz 《Archive of Applied Mechanics (Ingenieur Archiv)》2013,83(11):1549-1567
The stress fields in an orthotropic layer containing climb and glide edge dislocations are obtained by means of the complex Fourier transform. Stress analysis in the intact layer under in-plane point loads is also carried out. These solutions are employed to derive integral equations for the layers weakened by several interacting cracks subject to in-plane deformation. The integral equations are of Cauchy singular type. These equations are solved numerically for the density of dislocations on a crack surface. The dislocation densities are utilized to derive stress intensity factor for cracks. Several examples are solved and the interaction between the two cracks is investigated. 相似文献
43.
A theoretical solution is presented for the convective heat transfer of Giesekus viscoelastic fluid in pipes and channels,
under fully developed thermal and hydrodynamic flow conditions, for an imposed constant heat flux at the wall. The fluid properties
are taken as constant and axial conduction is negligible. The effect of Weissenberg number (We), mobility parameter (α) and Brinkman number (Br) on the temperature profile and Nusselt number are investigated. The results emphasize the significant effect of viscous
dissipation and fluid elasticity on the Nusselt number in all circumstances. For wall cooling and the Brinkman number exceeds
a critical value (Br
1), the heat generated by viscous dissipation overcomes the heat removed at the wall and fluid heats up longitudinally. Fluid
elasticity shifts this critical Brinkman number to higher values. 相似文献
44.
Fareghi-Alamdari Reza Zekri Negar Mansouri Fariborz 《Research on Chemical Intermediates》2017,43(11):6537-6551
Research on Chemical Intermediates - Cu0.5Co0.5Fe2O4 magnetic nanoparticles were prepared, characterized and employed as bench-top, highly active and magnetically separable nanocatalysts for the... 相似文献
45.
Seyed Ahmad Mohajeri Hossein Hosseinzadeh Fariborz Keyhanfar Javad Aghamohammadian 《Journal of separation science》2010,33(15):2302-2309
A new molecularly imprinted polymer for extraction of crocin from saffron stigmas was prepared using gentiobiose (a glycoside moiety in crocin structure) as a template. Crocin binding to gentiobiose imprinted polymer (Gent‐MIP) was studied in comparison with a blank nonimprinted polymer in aqueous media. Affinity of the Gent‐MIP for the crocin was more than the nonimprinted polymer at all concentrations. In Scatchard analysis, the number of binding sites in each gram of polymer (maximum binding sites) and dissociation constant of crocin to binding sites were 18.4 μmol/g polymer and 11.2 μM, respectively. The Gent‐MIP was then used as the sorbent in an SPE method for isolation and purification of crocin from methanolic extract of saffron stigmas. The recovery of crocin, safranal and picrocrocin was determined in washing and elution steps. The Gent‐MIP had significantly higher affinity for crocin than other compounds and enabled selective extraction of crocin with a high recovery (84%) from a complex mixture. The results demonstrated the possibility of using a part of a big molecule in preparing a molecularly imprinted polymer with a good selectivity for the main structure. 相似文献
46.
47.
Phenylaziridine hydrazones react at 140°–160°C to provide sterically congested trisubstituted olefins in good yield. 相似文献
48.
Vocal Fold Elasticity in the Pig, Sheep, and Cow Larynges 总被引:1,自引:0,他引:1
49.
Mohammad Mahdi Moshrefi Fariborz Rashidi Hamid Reza Bozorgzadeh Mohammad Ehtemam Haghighi 《Plasma Chemistry and Plasma Processing》2013,33(2):453-466
A novel type of plasma reactor having a rotating electrode is proposed for CO2 reforming of methane without catalyst at room temperature and atmospheric pressure. Results indicated that employing rotating ground electrode leads to a stable discharge for any period of time. Effects of feed composition, feed flow rate, applied power and electrodes separation on the carbon dioxide and methane conversions as well as the products selectivity were investigated. Increasing CO2/CH4 molar ratio in the feed favors the reagents conversion and consequently promotes the formation of hydrogen and carbon monoxide. If the target product is hydrogen, it is proposed to operate the reactor at CO2/CH4 = 1 molar ratio and if the target product is carbon monoxide then CO2/CH4 = 3 molar ratio is the preferred option for feed composition. This reactor system has advantages of stable operation and high conversion ability. Also, the obtained syngas with flexible molar ratio of H2 to CO is suitable for vast industrial applications. 相似文献
50.
A.S. Deakin V. Elias A.H. Fariborz Ying Xue Fang Shi T.G. Steele 《The European Physical Journal C - Particles and Fields》1998,4(4):693-704
There is a need to go beyond the narrow resonance approximation for QCD sum-rule channels which are likely to exhibit sensitivity
to broad resonance structures. We discuss how the first two Laplace sum rules are altered when one goes beyond the narrow
resonance approximation to include possible subcontinuum resonances with nonzero widths. We show that the corresponding first
two finite energy sum rules are insensitive to the widths of such resonances, provided their peaks are symmetric and entirely
below the continuum threshold. We also discuss the reduced sensitivity of the first two finite energy sum rules to higher
dimensional condensates, and show these sum rules to be insensitive to dimension condensates containing at least one pair. We extract the direct single-instanton contribution to the sum rule for the longitudinal component of the axial-vector correlation function from the known single-instanton contribution
to the lowest Laplace sum rule for the pseudoscalar channel. Finally, we demonstrate how inclusion of this instanton contribution
to the finite-energy sum rule leads to both a lighter quark mass and to more phenomenologically reasonable higher-mass-resonance
contributions within the pseudoscalar channel.
Received: 15 September 1997 / Revised version: 15 November 1997 / Published online: 26 February 1998 相似文献