Ferdowsi University of Mashhad

About: Ferdowsi University of Mashhad is a education organization based out in Mashhad, Iran. It is known for research contribution in the topics: Population & Catalysis. The organization has 11407 authors who have published 20810 publications receiving 263263 citations.

Transient simulations of cavitating flows using a modified volume-of-fluid (VOF) technique

Abstract: In this study, transient 2D/axisymmetric simulations of cavitating flows are performed using a modified 'Volume-of-Fluid' (VOF) technique. Simulation of the cavitation is based on a homogenous equilibrium flow model. To predict the shape of the cavity, the Navier-Stokes equations in addition to an advection equation for the liquid volume fraction are solved. Mass transfer between the phases is treated as a sink term in the VOF equation. The numerical method is used for different geometries in a wide range of cavitation numbers. Computed shapes of cavities were found to be in good agreement with those of the reported experiments. The simulation results also compared well with those obtained from analytical relations.

Green Synthesis of Gold Nanoparticles Using Sumac Aqueous Extract and Their Antioxidant Activity

Abstract: Green synthesis of nanoparticles which have eco-friendly favourable solvent systems and environmentally reducing agents is of excessive importance. In this paper, we aimed to develop environmentally friendly, rapid and simple producer for the synthesis gold nanoparticles (Au-NPs) using aqueous extract of sumac as reducing agents for gold ions as well capping agent for the bio-formed Au-NPs. The bio-synthesized Au-NPs were characterized by the UV-visible spectroscopy, FTIR, TEM, and zeta-potential measurements. The surface plasmon resonance band centred at 520 nm for Au-NPs was characterized by UV-visible spectrophotometer. The probable bio-molecules are polyphenols may responsible for reduction of gold ions were recognized through FT-IR. The TEM result shows the bioformed Au-NPs are spherical in shapes with the mean size of 20.83 ±4.4 nm. The capping of anionic bio-molecules on the surface of Au-NPs was confirmed by zeta potential assessment (-25.3 mV) and is responsible for the electrostatic stability. In vitro antioxidant activity studies showed that DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2, 2'-azino-bis 3-ethylbenzthiazoline-6-sulfonic acid) activities increased in a dose dependent manner. The bio-synthesized nanoparticles can potentially useful in pharmaceutical and biomedical applications.

Co-Optimal Placement of Measurement Devices and Their Related Communication Infrastructure in Wide Area Measurement Systems

Abstract: The term wide area measurement system (WAMS) implies a system including new digital metering devices (e.g., phasor measurement unit) together with communication system which is designed for monitoring, operating, and controlling power systems. Generally, a WAMS process includes three main functions: data acquisition, data transmitting, and data processing performed by measurement devices, communication systems, and energy management systems, respectively. While these three functions are seriously interdependent, most researches carried out on this topic investigate these functions independently. In this paper, meters placement and their required communication infrastructure for state estimation program are co-optimized simultaneously. To perform this, these two planning issues are jointly formulated in a single genetic algorithm (GA) problem. Then, three IEEE test networks without any conventional measurements and communications are used to investigate the advantages of considering dependability of optimization of these two sections. The results confirm that the proposed method is advantageous over the techniques optimizing each section independently. The results indicate that while the total number of measurement devices for system observability may increase (and therefore, the observability is improved), the total cost for the plan is reduced.