Composite stiffened cylindrical shells are widely used as primary elements in aerospace structures. In the recent years, there has been a growing research interest in optimum design of composite stiffened cylindrical shell structures for stability under buckling load.  This paper focuses upon the development of an efficient optimization of ring-stringer stiffened cylindrical shell. The opti...

It is shown that the existence of static, cylindrically symmetric wormholes does not require violation of the weak or null energy conditions near the throat, and cylindrically symmetric wormhole geometries can appear with less exotic sources than wormholes whose throats have a spherical topology. Examples of exact wormhole solutions are given with scalar, spinor and electromagnetic fields as so...

This study aims to investigate the effects of geometric imperfections on buckling of thin cylindrical shells due to global shear. To this end, more than 320 finite element models of cylindrical shells with different diameter to thickness ratios were prepared. Random imperfections with different amplitudes were applied to numerical models. The results revealed that global buckling of cylindrical...

Fe:TiO2 nano particles were deposited through sol-gel techniques, and the influence of pH values on structural, morphological, optical, photoluminescence spectral behaviors was studied. Iron doped titanium dioxide nanopowders analyzed using XRD, SEM, UV–ViS, PL. Nano crystallized samples (72 nm, 77 78 83 nm) gained from X-Ray diffraction data showed that there creation unalloyed anatase ructile...

efflux time measurements are carried out for gravity draining of a liquid from a large cylindrical tank (where the flow is essentially laminar) through single exit pipe in the absence and presence of cetyl pyridinium chloride (cpc) surfactant solutions. the variables considered are initial height of liquid in the tank, dia. of tank, length of the exit pipe and concentration of surfactant. the d...

this study aimed to investigate the effects of stiffeners on buckling of thin cylindrical shells under uniform axial compression. to this end, more than 300 finite element models of stiffened cylindrical shells were prepared. the variables considered are shell thickness, number, dimension and the location of the vertical and horizontal stiffeners as well as circular symmetrical imperfections. r...

free vibration of simply supported circular cylindrical shell made of functionally graded material (fgm) under internal pressure was investigated. the effective material properties are assumed to vary continuously along the thickness direction according to a volume fraction power law distribution. first order shear deformation theory based on love's first approximation theory was utilized in th...

Spectral intensities of quadrupolar nuclei and the radiofrequency (rf) pulse lengths for selective and non-selective excitation of any single-quantum NMR transition in the solid state are calculated. When nuclei of the same element occupy sites which experience different electric field gradients, the spectra are quantitatively reliable only when the length of the rf pulse is much smaller than n...