In this paper, we present a comparative numerical analysis to determine the refractive index of photonic crystal fibers (PCFs) by using FDFD method and used the results to evaluate the confinement losses of PCFs by considering the effects of air-hole rings in the cladding. It is shown that by increasing the wavelength, the imaginary part of refraction index rises, resulting in increase of conf...

Introduction. Dedekind has determined all groups whose subgroups are all normal (see, e.g., [5, Theorem 12.5.4]). Partially generalizing this, Wielandt showed that a finite group is nilpotent, if and only if all its subgroups are subnormal, and also if and only if all maximal subgroups are normal [5, Corollary 10.3.1, 10.3.4]. Huppert [7, Sätze 23, 24] has shown that if all 2nd-maximal subgroup...

We have reached our goal of implementing a computationally cheap algorithm for realtime rendering of realistic two-dimensional fire. The fire is simulated using computational fluid dynamics, vorticity confinement, and combustion modelling and visualized using black-body radiation. Small rotationally homogenous fires like torches and candles viewed in front are the best candidates when using thi...

We study the BV-α-Deconvolution model. It is a family of regularizations of the Barotropic Vorticity (BV) model that generalize the BV-α model and improve its accuracy. A both unconditionally stable and optimally convergent scheme for the BV-α-Deconvolution model is proposed and we show that it is O(α), where N is the deconvolution order, whereas the BV-α model is at most second order accurate....

Proton transfer (PT) and methyl group transfer (MGT) occurring in small biomimetic systems, Formamide-Formamidic acid (FA-FI), and N-formyl-N-methylformamide-(E)-methyl N-formylformimidate (NMFA-NMFI) are investigated in the gas phase and in single-walled carbon nanotubes by using the density functional theory and the ONIOM approach. It is shown that PT reaction is disfavoured in single-walled ...

In this paper, a novel design of all-solid photonic bandgap fiber with ultra-low confinement loss is proposed. The confinement loss is reduced remarkably by managing the number of rods rings, up-doping level, pitch value, and rods diameters. Moreover, the designed PCF shows ultra-flattened dispersion in L- and U-band. Furthermore, a new design, based on introducing of an extra ring of air h...

Rolling vortices and chaotic swirling are the most visually compelling aspect of smoke. Standard numerical simulation techniques for the animation of smoke suffer from a loss of these vortex patterns due to numerical damping. The majority of methods in computer animation use techniques such as vorticity confinement [3] to re-capture them. In this work, a Lagrangian method is presented which exp...

We investigate the influence of volume viscosity on a planar shock/hydrogen bubble interaction. The numerical model is two dimensional and involve complex chemistry and detailed transport. All transport coefficients are evaluated using algorithms which provide accurate approximations rigourously derived from the kinetic theory of gases. Our numerical results show that volume viscosity has an im...