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Kashan, Iran

The University of Kashan, located in the city of Kashan in Iran, 230 kilometers south of the capital of Tehran. Educating an estimated 6,000 students in many different fields including engineering, physics, mathematics, chemistry, art, and humanities. Wikipedia.

Mahmoodi M.,University of Kashan
International Journal of Thermal Sciences | Year: 2011

In the present paper, free convection fluid flow and heat transfer of various water based nanofluids in a square cavity with an inside thin heater has been investigated numerically. The left and right walls of the cavity are maintained at constant temperature Tc, while its top and bottom walls are insulated. A thin heater with the temperature of Th (T h > Tc) is located inside the cavity which its location and length is varying. The governing equations were discretized using the finite volume method and SIMPLER algorithm. Using the developed code, a parametric study was undertaken, and the effects of pertinent parameters, such as, Rayleigh number, the position and location of the heater, the volume fraction of the nanoparticles, and various types of the nanofluids on the fluid flow and heat transfer inside the cavity were investigated. It was observed from the results that at low Rayleigh numbers the horizontal positioned heater have higher Nusselt number compared to the vertical positioned heater while at high Rayleigh numbers the position of the heater does not affect the heat transfer rate. For a horizontal heater when it is located in lower half of the cavity, more heat transfer occurs compared to the case of heater located in upper half of the cavity. Moreover, it was found that at high Rayleigh numbers, the Ag-water nanofluid is more effective to enhance the heat transfer rate while at low Rayleigh numbers the type of nanofluids does not affect the heat transfer rate. © 2011 Elsevier Masson SAS. All rights reserved. Source

Mahmoodi M.,University of Kashan
International Journal of Thermal Sciences | Year: 2011

The present paper focuses on problem of free convection fluid flow and heat transfer of Cu-water nanofluid inside L-shaped cavities. The governing equations are discretized using the finite volume method while the SIMPLER algorithm is employed to couple velocity and pressure fields. Using the developed code, the effects of the Rayleigh number, the aspect ratio of the L-shaped cavity, and the volume fraction of the Cu nanoparticles on the flow and thermal fields and heat transfer inside the cavity are investigated. The obtained results show that the average Nusselt number for all rage of cavity aspect ratio increases with increase in the Rayleigh number and the solid volume fraction of the nanofluid. Also the Rayleigh number in which transition from conduction to convection occurs postpones with decreasing the aspect ratio of cavity. Moreover it is found that the rate of heat transfer increases with decreasing the aspect ratio of the cavity. © 2011 Elsevier Masson SAS. All rights reserved. Source

Fath-Tabar G.H.,University of Kashan
Match | Year: 2011

In this paper, some bounds for the first and second Zagreb indices of graphs are presented. A new graph invariant, named third Zagreb index, is introduced. Some mathematical properties of this new graph invariant are also presehted. Source

Tahghighi H.,University of Kashan
Earthquake Engineering and Structural Dynamics | Year: 2011

Unique to the near-source region of a large earthquake is the occurrence of strong impulsive ground motion and surface faulting referred to as 'fling-step' motion. The objective of this study is to synthesize broad-band time histories over a wide range of frequencies by characterizing rupture directivity and fling effects from the comprehensive strong motion database of the near-fault Chi-Chi event. To aid in the generation of these special types of ground motions, a hybrid modeling technique is introduced based on the stochastic finite-fault radiation method and an efficient analytical approach to incorporate the observed low-frequency features in the records close to the ruptured fault. The results show that the overall agreement among the developed hybrid methodology and recorded waveforms and response spectra is quite satisfying. A brief discussion on the design of infrastructures near seismic fault is also included. © 2011 John Wiley & Sons, Ltd. Source

Rahimi M.,University of Kashan
Renewable and Sustainable Energy Reviews | Year: 2014

This paper studies the dynamic behavior of doubly fed induction generators (DFIGs) modeled with the stator flux orientation regarding rotor- and grid-side converter control strategies. The investigations include modal and sensitivity analysis, and using them to identify and characterize the instability mode, stator dynamics analysis, and time domain simulations. The paper first deals with the modal analysis of the DFIG for different control strategies and operating conditions. Then the dynamic and transient performance of the DFIG under voltage dips and large disturbances are investigated, and the effects of rotor and grid-filter control strategies on the DFIG transient behavior are examined. Increasing the rotor and grid-filter closed loop bandwidths, rotor current active damping, and compensation of back-emf voltages can improve the rotor and grid-filter dynamics, decrease tracking error and limit the rotor current transients. However they can lead to poorly stator modes and deteriorate the DFIG transient performance. Thus, appropriate selection of rotor controller parameters has an important effect on the DFIG transient performance, and consequently on the future interconnected power system. © 2014 Elsevier Ltd. Source

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