Longitudinal dispersion coefficient is a key variable for the description of the longitudinal transport in a river. In recent years, Artificial Neural Networks (ANNs) have become popular and useful tools for environmental modellers as they are perceived to overcome some of the difficulties associated with traditional statistical approaches. In these applications, however, little attention was g...

This paper presents the support vector machine approach to predict the longitudinal dispersion coefficients in natural rivers. Collected published data from the literature for the dispersion coefficient for wide range of flow conditions are used for the development and testing of the proposed method. The proposed SVM approach produce satisfactory results with coefficient of determination=0.9025...

The paper presents an analytical solution for dispersion of a solute in the peristaltic motion of a micropolar fluid in the presence of both homogeneous and heterogeneous chemical reactions. The average effective dispersion coefficient has been found using Taylor’s limiting condition under long wavelength approximation. The effects of various relevant parameters on the average coefficient of di...

waveguides with low confinement loss, low chromatic dispersion, and low nonlinear effects are used in optical communication systems. optical fibers can also be employed in such systems. besides optical fibers, photonic crystal fibers are also highly suitable transmission media for optical communication systems. in this paper, we introduce two new designs of index-guiding photonic crystal fiber ...

The longitudinal dispersion coefficient is used to describe the change in characteristics of a solute cloud, as it travels along the longitudinal axis of a pipe. Taylor [1954] proposed a now classical expression to predict the longitudinal dispersion coefficient within turbulent pipe flow. However, experimental work has shown significant deviation from his prediction for Re < 20000. This paper ...

a r t i c l e i n f o The longitudinal dispersion coefficient (D) is an important parameter needed to describe the transport of solutes in rivers and streams. The dispersion coefficient is generally estimated from tracer studies but the method can be expensive and time consuming, especially for large rivers. A number of empirical relations are available to estimate the dispersion coefficient; h...

The axial dispersion coefficient of hexachlorobenzene in supercritical carbon dioxide is investigated in a fixed-bed packed with glass beads. The on-line chromatographic pulse-response experiment is used in order to study the dynamics of a packed column under supercritical conditions. The radial dispersion is assumed negligible because of the packed column geometry. To estimate the axial disper...

Let a(x), b(x), p(x) be formal power series in the indeterminate x over C (i.e., elements of the ring C [[x]] of such series) such that ord a(x) = 0, ord p(x) = 1 and p(x) is embeddable into an analytic iteration group (π(s, x))s∈C in C [[x]]. By a covariant embedding of the linear functional equation φ(p(x)) = a(x)φ(x) + b(x), (L) (for the unknown series φ(x) ∈ C [[x]]) with respect to (π(s, x...

We analyze the dispersive properties of inhomogeneous nanostructures (INSs) composed of alternating layers of different materials. Analysis of the interaction between the propagating pulse and the INS provides modified dispersion characteristics. An approximate theoretical model predicting the dispersion properties of the INS is developed and compared with more accurate numeric computation resu...