Human Enteroviruses replicate in gastrointestinal tract and are excreted to the sewage system through feces, so isolation of Enteroviruses from sewage can be considered as a sensitive indicator for virus circulation in society. They are originally given the name of Enteroviruses, but the inadequacy of this term became apparent when some Coxackie and Echoviruses were also found in acute respiratory infections. Therefore, these viruses can produce acute or preclinical infections, the shedding of virus are more than 1010 virus per each gram of feaces. In this study, 63 sewage samples were obtained from the 6 main sewage disposal systems in Tehran by grab sampling: Direct, Pellet, Two-Phase methods. In 2 sensitive cell lines (Hep2 & RD) and neutralization test were used to determine Enterovirus circulation in one year. None-Typable Enteroviruses, E11 and E25 were isolated more frequently than other Entroviruses. Out of 63 sewege specimens, we isolated 13 (20.63%), 25 (39.68%) & 27 (42.83%) Enteroviruses by Direct, Pellet and Two-Phase methods respectively.      

In this paper we consider a nonlinear Two-Phase Stefan problem in onedimensional space. The problem is mapped into a nonlinear Volterra integral equation for the free boundary.

The lack of variable-speed drives for Two (single) induction motor is a reality. This article attempts mainly to investigate the reasons for this lack of variable-speed drives. This paper deals with literature survey of various existing converter topologies, which have been proposed for adjustable speed single Phase induction motor drives. Various converter topologies have been compared in this paper. Among these converter topologies, the adjustable frequency PWM inverter is the best choice for single-Phase induction motor drives. However, adjustable-frequency drives have not been widely used with single-Phase Induction motors. The open-loop constant V/F control law cannot be used with the single-Phase induction motor drives as it is used with three Phase motors. The variation of the operating frequency at lower speed range with constant load torque causes variation in motor's slip. A constant V/F control is suitable only over the upper speed range.

Continuous gas lift process is used to boost oil production in many mature reservoirs, which can no longer produce under natural drive. In this article, application of mechanistic flow maps as well as the correlations estimating pressure drop in a gas lifted well, as the most complex and time consuming part of the gas lift modeling is examined. Using the black-oil model to compute the Two-Phase pressure drop in a gas lifted well leads to a substantial error due to the changes in composition and bubble point pressure along the well. In order to describe the thermodynamic behavior of the hydrocarbon fluid, a multicomponent compositional description has been applied using the reduced parameter method. The results show that the empirical maps and correlations lead to severe discontinuities at transition points between the different flow regimes. This causes an unacceptable error when computing the pressure drop.

In this study, we investigated the Phase behavior of rods with square ( ) and circular (diameter D) cross sections between Two hard walls using the Parsons-Lee theory and applying the Zwanzig approximation. Our focus is to find wall-to-wall separations (H) and the size of particles in which the Phase of the system changes without occurring a Phase transition. It was determined that if the distance between the plates is smaller than the length of the particles, for any particle whose length (L) to diameter ratio is greater than 1, the second order Phase transition occurs, and most of the particles are placed in a certain direction parallel to the plates, which this type of Phase transition takes place at lower densities with increasing particle’s aspect ratio. We also came to the conclusion that if the distance between the plates is greater than and , despite the Phase change of the system with increasing particle density, no Phase transition will occur. In addition, it was found that the cylindrical shaped particles show some unexpected behaviors, which could be due to the inappropriate performance of the applied theory or their real physical behavior, which requires more detailed studies to resolve the ambiguity.

Different measures may be taken into account in order to reduce the destructive effects of flow over spillways, one of which is the application of stepped spillways in an attempt to dissipate the flow energy. This method also influences the economic justification of the project and reduces the costs. The present study simulated the free surface and the Two-Phase flow patterns over the stepped spillway employing the Fluent software, and adopting the mixture model as well as the standard K - E turbulence model. The numerical model verification was conducted utilizing the data of air concentration distribution in water, and the velocity at different discharge rates collected in experiments performed by Chamani utilizing a physical model at Hydraulic Laboratory conducted at the University of Alberta. The numerical simulation results and experimental data were in good agreement. Concentration profiles led to a stair like distribution of the concentration, and the discharge effects on the shapes of velocity profiles were comparable. The results showed that as the inlet discharge increased, velocity profiles widened and spread more, and flow height and maximum flow velocity rose, which in turn reduced the flow dissipation.

The corrections for log law must be taken into account the presence of bubbles in the Two Phase turbulent boundary layer. In the present study, a logarithmic law for the wall based on the supposition of additional turbulent viscosity associated with bubble wakes in the boundary layer was proposed for bubbly flows. An empirical constant accounting both for shear induced turbulence interaction and for non-linearity of bubble was determined for the new wall law, this constant was deduced from experimental measurements. In the case of a turbulent boundary layer with millimetric bubbles developing on a vertical flat plate, the wall friction prediction achieved with the wall law was compared to the experiences. We obtained a good concordance between experimental and numerical result. This significant agreement for wall friction prediction was particularly important for the low void fraction when bubble induced turbulence have a considerable role.