Tubular reactor stability is reconsidered for a wide variety of situations where there is dispersion outside the reactor.A complete set of boundary conditions are proposed from which the Danckwetts boundary conditions arise as a special case. While the multiplicity and stability characteristics are found to be the same as those found with Danckwerts boundary conditions (no dispersion outside th...

The aim of this paper is to study the L1-stability of periodic stationary solutions of scalar convection-diffusion equations. We obtain dispersion in L2 for all space dimensions using Kružkov type entropy. And when the space dimension is one, we estimate the number of sign changes of a solution to obtain L1-stability. Keyword : L-stability, periodic stationary solutions, entropy, dispersion ine...

In this article we are concerned with the instability and stability properties of traveling wave solutions of the double dispersion equation utt − uxx + auxxxx − buxxtt = −(|u|u)xx for p > 1, a ≥ b > 0. The main characteristic of this equation is the existence of two sources of dispersion, characterized by the terms uxxxx and uxxtt. We obtain an explicit condition in terms of a, b and p on wave...

We analyze the influence of spectrally modulated dispersion and loss on the stability of mode-locked oscillators. In the negative dispersion regime, a soliton oscillator can be stabilized in a close proximity to zero-dispersion wavelength, when spectral modulation of dispersion and loss are strong and weak, respectively. If the dispersion is close to zero but positive, we observe chaotic mode-l...

enhancement of antioxidant capacity of plants by natural antioxidants obtained from medicinal plants can be a simple way to produce stress tolerant plants. zataria multiflora essential oil (zo) is one of the useful antioxidants with potent antioxidant activity. zo is insoluble in water and can be degraded by light, oxygen, and high temperature. incorporation of zo into poly vinyl alcohol (pva) ...

We introduce the theory of modulational instability (MI) of electromagnetic waves in fibers with random polarization mode dispersion. Applying a linear stability analysis and stochastic calculus, we show that the MI gain spectrum reads as the maximal eigenvalue of a constant effective matrix. In the limiting cases of small or large fluctuations, we give explicit expressions for the MI gain spec...

Ultraviolet–Visible (UV–Vis) spectroscopy was used, in the current investigation, to explore the dispersion and stability of titania nanoparticles in an aqueous media with different types of dispersants. Hydrochloric and nitric acids as well as ammonia were used to determine the stability of the suspension in the acidic region (pH=2.5) and basic area (pH=9.5), respectively. In addition, for mea...

The stability of stratified Rivlin-Ericksen fluid in porous medium in the presence of suspended particles and magnetic field has been investigated. Upon application of normal mode technique, the dispersion relation was obtained. The important results obtained in this paper include the instability of non-oscillatory modes and the stability of oscillatory modes. Also, it was found that the system...

Create three-dimensional network of siloxane polymer in the epoxy resin is an appropriate mechanical properties .Dispersion of nanoclay in these coating was prepared by ultrasonication method. Mechanical properties of nanocomposit coatings such as abrasion, hardness and adhesion was increased by addition of nanoclay montmorillonite. Different percentages of nanoclay in coating showed that even ...

Aqueous dispersions of functionalized carbon nanotubes (CNTs) are now widely used for biomedical applications. Their stability in different in vitro or in vivo environments, however, depends on a wide range of parameters, such as pH and salt concentrations of the surrounding medium, and length, aspect ratio, surface charge, and functionalization of the applied CNTs. Although many of these aspec...