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Showing 3 results for Fardi

A. Fraji, Gh. AsadollahFardi, A. Shevidi,
Volume 11, Issue 4 (Transaction A: December 2013)

Secondary clarifiers with large areas are widely applied in wastewater treatment plants. A pilot study was conducted to examine the possibility of applying one and two-stage inclined tube settlers instead of conventional secondary clarifiers. Tube diameter in the first stage of the two-stage settler was wide as the conventional ones, but in the second stage, it was narrow to improve the efficiency. The results indicated that in short detention times, the tube settler was more effective in shorter detention time than the conventional secondary sedimentation basin, and its effluent of TSS and turbidity was acceptable to discharge into the surface waters. The average removal of TSS, BOD5, and COD, in a 20-minute detention time in the tubes, in the one-stage tube settler pilot plants was 97.6%, 96.4%, and 96.36%, respectively, while in the conventional secondary sedimentation basin was 98.2%, 99%, and 98.6%, respectively. There was a good agreement between theoretical analyses and experimental results of the pilot plant. Two-stage tube settlers in the series could improve hydraulic condition and removal efficiency of TSS, in comparison with the one-stage tube settler. The average TSS removal, in shorter detention times than that the one-stage, was 97.8%.
E. Lotfi, S. Delfan, A. Hamidi, H. Shahir, Gh. Fardi,
Volume 12, Issue 1 (Transaction B: Geotechnical Engineering, January 2014)

In saturated soils, heating induces thermal expansion of both grains and the pore fluid. Lower thermal expansion coefficient of aggregates results in the increase of pore pressure and reduction of the effective stress besides subsequent volume changes due to the dissipation of pore pressure and heat transfer. Dissipation of thermally induced pore pressure with time is a coupled thermo-hydro-mechanical (THM) phenomenon, involving gradients of pore pressure and temperature, hydraulic and thermal flows within the mass of soil and changes in the mechanical properties with temperature. The objective of this paper is presentation of a numerical method to determine the effect of temperature on consolidation of clays. In this regard, the finite element code, PISA is used for one dimensional THM analysis of porous media. The analysis performed using both linear elastic and elastoplastic Cam clay models. Modified Cam clay model was applied in elastoplastic analysis. Variation of temperature, displacements and pore pressure determined with time and compared with numerical solutions of other researchers. Also it was indicated that implementation of coupled THM analysis yields better results for displacements compared to the hydro mechanical (HM) one. Application of elastoplastic constitutive model instead of linear elastic one indicated that preconsolidation pressure has an important effect on results of analysis.
Gholamreza AsadollahFardi,
Volume 14, Issue 4 (Transaction A: Civil Engineering 2016)

This paper presents a numerical model based on  the explicit finite difference method for contaminant transport under electrokinetic remediation process. The effect of adsorption, precipitation and water auto-ionization reactions were considered  to  set of algebraic equations. Also the effect of electrolysis reaction in anode and cathode cells was considered with appropriate boundary conditions. The model predictions are compared with experimental results of electrokinetic lead removal from kaolinite in the literature. The coefficient of determination and index of agreement between the lead concentration of experimental result and model prediction was 0.974 and 0.884, respectively. The coefficient of determination and index of agreement between the pH value of  the experiment and the pH prediction was 0.975 and 0.976, respectively

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