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Entropy generation analysis of thermally developing forced convection in fluid-saturated porous medium
, Article Applied Mathematics and Mechanics (English Edition) ; Volume 29, Issue 2 , 2008 , Pages 229-237 ; 02534827 (ISSN) ; Ejlali, A ; Hooman, F ; Sharif University of Technology
2008
Abstract
Entropy generation for thermally developing forced convection in a porous medium bounded by two isothermal parallel plates is investigated analytically on the basis of the Darcy flow model where the viscous dissipation effects had also been taken into account. A parametric study showed that decreasing the group parameter and the Péclet number increases the entropy generation while for the Brinkman number the converse is true. Heatline visualization technique is applied with an emphasis on the Br < 0 case where there is somewhere that heat transfer changes direction at some streamwise location to the wall instead of its original direction, i.e., from the wall. © 2008 Editorial Committee of...
Entropy generation for forced convection in a porous channel with isoflux or isothermal walls
, Article International Journal of Exergy ; Volume 5, Issue 1 , 2008 , Pages 78-96 ; 17428297 (ISSN) ; Hooman, F ; Mohebpour, S. R ; Sharif University of Technology
Inderscience Publishers
2008
Abstract
A numerical study is reported to investigate the entropy generation due to forced convection in a parallel plate channel filled by a saturated porous medium. Two different thermal boundary conditions are considered being isoflux and isothermal walls. Effects of the Poclet number, the porous medium shape factor, the dimensionless temperature difference for isothermal walls, the dimensionless heat flux for isoflux walls, and the Brinkman number on the Bejan number as well as the local and average dimensionless entropy generation rate are examined. Copyright © 2008 Inderscience Enterprises Ltd
Reliability-based Evaluation and Calibration of Load Combinations for the Design of Steel Building Structures of Iran
, M.Sc. Thesis Sharif University of Technology ; Mahsuli, Mojtaba (Supervisor) ; Ghasemi, Hooman ($item.subfieldsMap.e)
Abstract
The objective of this thesis is to evaluate and calibrate design load combinations of steel building structures of Iran based on the reliability theory. The importance of this research stems from recognition that the design load combinations for steel structures in Section 6 of the National Building Code of Iran have been completely adopted from the ASCE/SEI 7-10 standard, whereas the factors that affect these load combinations differ in Iran from those of the United States. Examples are the difference in the construction industry economy, lower quality of here and the differences in probability distributions for the specifications of steel. Hence, the load combinations need to be calibrated...
Wind turbine productivity considering electrical subassembly reliability
, Article Renewable Energy ; Volume 35, Issue 1 , 2010 , Pages 190-197 ; 09601481 (ISSN) ; Oraee, H ; Tavner, P.J ; Sharif University of Technology
2010
Abstract
This paper proposes a reliability model for the electrical subassemblies of geared wind turbine systems with induction generators. The model is derived considering the failure of main subassemblies and their parameters are calculated. A productivity comparison is performed between the selected wind turbine systems including reliability issues. Two methods of modification for variable-speed wind turbines with Doubly Fed Induction Generators (DFIG) to improve their availability are finally suggested
Reliability comparison of direct-drive and geared-drive wind turbine concepts
, Article Wind Energy ; Volume 13, Issue 1 , 2010 , Pages 62-73 ; 10954244 (ISSN) ; Tavner, P. J ; Oraee, H ; Sharif University of Technology
2010
Abstract
This paper proposes for wind turbines (WTs) an analytical reliability method, used on other engineering systems, to compare the reliability of different turbine concepts. The main focus of the paper is to compare the reliability of geared generator and direct-drive concept WTs. Modification methods are also recommended for improving the availability of WTs and geared generator concept incorporating doubly fed induction generator
Failure Modes and Effects Analysis (FMEA) for wind turbines
, Article International Journal of Electrical Power and Energy Systems ; Volume 32, Issue 7 , 2010 , Pages 817-824 ; 01420615 (ISSN) ; Oraee, H ; Tavner, P. J ; Sharif University of Technology
2010
Abstract
The Failure Modes and Effects Analysis (FMEA) method has been used to study the reliability of many different power generation systems. This paper now applies that method to a wind turbine (WT) system using a proprietary software reliability analysis tool. Comparison is made between the quantitative results of an FMEA and reliability field data from real wind turbine systems and their assemblies. These results are discussed to establish relationships which are useful for future wind turbine designs. The main system studied is an existing design 2 MW wind turbine with a Doubly Fed Induction Generator (DFIG), which is then compared with a hypothetical wind turbine system using the Brushless...
Optimal reactive power planning in harmonic distored power system using genetic algorithm
, Article IEEE TENCON 2004 - 2004 IEEE Region 10 Conference: Analog and Digital Techniques in Electrical Engineering, Chiang Mai, 21 November 2004 through 24 November 2004 ; Volume C , 2004 , Pages C347-C350 ; Ranjbar, A .M ; Arabian, H ; Mirjafari, M ; Sharif University of Technology
2004
Abstract
A continuous growth in nonlinear loads may cause an increment in harmonic distortion and some other important problems in power systems so considering power quality effects in optimal reactive power planning has become more crucial than before. In this paper, optimal reactive power planning based on voltage profile deviation and voltage THD decrement is studied. The planning problem is studied using reactive power injection in each bus bar and genetic algorithm is also used for solving optimization problem. Obtained results for 5-bus and 30-bus IEEE standard networks are also presented. ©2004IEEE
On the optimization of sphalerite bioleaching; the inspection of intermittent irrigation, type of agglomeration, feed formulation and their interactions on the bioleaching of low-grade zinc sulfide ores
, Article Chemical Engineering Journal ; Volume 187 , 2012 , Pages 217-221 ; 13858947 (ISSN) ; Azad, R. R ; Arabian, D ; Molaie, A ; Nemati, F ; Sharif University of Technology
2012
Abstract
In this study, we have investigated the bioleaching potential of a native strain of Acidithiobacillus ferrooxidans isolated from zinc and lead sulfide mines under varied ambient conditions of growth and substrate consumption. The effects of intermittent irrigation, type of agglomeration, feed formulation in terms of acid, enriched salt solution, initial number of microorganism, and their interactions on the bioleaching of low-grade zinc sulfide ores (containing 5.78% zinc) on growth and biooxidation efficiency of the bacteria have been evaluated. Bioleaching capacities of the isolate were optimized by the utilization the Taguchi method (e-qualitic-4) for design of experiments. As a result,...
Enhancing bioleaching and iron oxidation efficiency of native strain of acidithiobacillus ferrooxidans, by optimizing the ambient growth conditions
, Article Pollution Research ; Volume 28, Issue 3 , 2009 , Pages 329-336 ; 02578050 (ISSN) ; Nemati, F ; Roostaazad, R ; Shitole, M. G ; Gade, W. N ; Sharif University of Technology
2009
Abstract
In this study, we have investigated the bioleaching potential of a native strain of Acidithiobacillus ferrooxidans isolated from zinc and lead sulfide mines under varied ambient conditions of growth and substrate consumption. In the process of standardizing growth conditions to improve iron oxidation, bioleaching of zinc and lead is also found to be enhanced. The effects of pH, temperature, initial inoculum, Fe2+ and ammonium sulphate concentration on growth and bio-oxidation efficiency of the bacteria have been evaluated. The results indicate that the optimum pH required for the growth of the bacterium is 1.8; however, the same for maximum efficiency is 1.5. It is also found that pH has a...
Reliability Model of Wind Turbine System with BDFG
, Ph.D. Dissertation Sharif University of Technology ; Oraee, Hashem (Supervisor) ; Fotuhi Firouzabad, Mahmud (Supervisor)
Abstract
Considerable attention has been given in recent years to renewable energy sources due to concerns about dwindling fuel reserves and the potential impact of conventional energy systems on the environment. Wind power is one form of renewable energy resources and also considered as Dispersed Generation (DG). Widespread utilization of wind power imposes many effects on planning and operation of power system. In other side, reliability evaluation and enhancement is an important factor in modern power system planning and operation. So, reliability assessment of wind turbines is of great importance and will receive more attention in the future according to increase of WT utilization. The...
Biodegradation of Polycyclic Aromatic Hydrocarbons in a New Reactor
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor) ; Arabian, Daryoush (Co-Advisor)
Abstract
TPPB are characterized by a cell-containing aqueous phase, and an immiscible and biocompatible organic phase that partitions toxic/insoluble substrates to the cells base on their metabolic demand and the thermodynamic equilibrium of the system. Surface areas, Mass transfer coefficient, Hydrophobicity of polycyclic aromatic hydrocarbons (PAH) are considered as limitation in two phase partition bioreactors (TPPB). For solving of this challenge, in this project used solid particle for increment of mss transfer and surface area, and also solid particles can eliminate limitation of initial concentration of polycyclic aromatic hydrocarbon and ratio of aqueous/organic phases. Naphthalene is used as...
Response surface methodology as an approach to optimize growth medium of indigenous strain of Bacillus mycoides for production of biosurfactant
, Article ICBEE 2010 - 2010 2nd International Conference on Chemical, Biological and Environmental Engineering, Proceedings, 2 November 2010 through 4 November 2010 ; 2010 , Pages 146-152 ; 9781424487479 (ISBN) ; Rahimpour, M. R ; Jahanmiri, A. H ; Roostaazad, R ; Arabian, D ; Soleimani, M ; Sharif University of Technology
2010
Abstract
In this study, we have investigated the potential of a native bacterial strain isolated from an Iranian oil field for the production of biosurfactant. The bacterium was identified to be Bacillus mycoides by biochemical tests and 16S ribotyping. The biosurfactant, which was produced by this bacterium, was able to reduce the surface tension of media to 34 mN/m. Biosurfactant production was optimized by the combination of central composite design (CCD) and response surface methodology (RSM). The factor selected for optimization of growth conditions were pH, temperature, glucose and salinity concentrations. The empirical model developed through RSM in terms of effective operational factors...
Enhancing biosurfactant production from an indigenous strain of Bacillus mycoides by optimizing the growth conditions using a response surface methodology
, Article Chemical Engineering Journal ; Volume 163, Issue 3 , October , 2010 , Pages 188-194 ; 13858947 (ISSN) ; Rahimpour, M. R ; Jahanmiri, A. H ; Roostaazad, R ; Arabian, D ; Ghobadi, Z ; Sharif University of Technology
2010
Abstract
In this study, we have investigated the potential of a native bacterial strain isolated from an Iranian oil field for the production of biosurfactant. The bacterium was identified to be Bacillus mycoides by biochemical tests and 16S ribotyping. The biosurfactant, which was produced by this bacterium, was able to reduce the surface tension of media to 34. mN/m. Compositional analysis of the produced biosurfactant has been carried out by thin layer chromatography (TLC) and FT-IR. The biosurfactant produced by the isolate was characterized as lipopeptide derivative. Biosurfactant production was optimized by the combination of central composite design (CCD) and response surface methodology...
Interactive optimization of biosurfactant production by Paenibacillus alvei ARN63 isolated from an Iranian oil well
, Article Colloids and Surfaces B: Biointerfaces ; Volume 82, Issue 1 , 2011 , Pages 33-39 ; 09277765 (ISSN) ; Rahimpour, M. R ; Jahanmiri, A. H ; Roostaazad, R ; Arabian, D ; Soleimani, M ; Jamshidnejad, Z ; Sharif University of Technology
2011
Abstract
The potential of an indigenous bacterial strain isolated from an Iranian oil field for the production of biosurfactant was investigated in this study. After isolation, the bacterium was characterized to be Paenibacillus alvei by biochemical tests and 16S ribotyping. The biosurfactant, which was produced by this bacterium, was able to lower the surface tension of media to 35. mN/m. Accordingly, thin layer chromatography (TLC) and FT-IR has been carried out to determine compositional analysis of the produced biosurfactant. After all the tests related to characterization of the biosurfactant produced by the isolated bacterium, it was characterized as lipopeptide derivative. The combination of...
Comparison and modification of models in production of biosurfactant for Paenibacillus alvei and Bacillus mycoides and its effect on MEOR efficiency
, Article Journal of Petroleum Science and Engineering ; Volume 128 , April , 2015 , Pages 177-183 ; 09204105 (ISSN) ; Roostaazad, R ; Soleimani, M ; Arabian, D ; Moazed, M. T ; Rahimpour, M. R ; Mazinani, S ; Sharif University of Technology
Elsevier
2015
Abstract
Biosurfactant production from two indigenous consortia has already been investigated in two previous studies. In this study, comparison and modification of those models for having as much biosurfactant as possible was conducted. After characterization of bacteria by biochemical tests and 16S ribotyping, a fully modification on the final models was presented. Response surface methodology has the ability to investigate the liability of the parameters and models by the help of Desirability mode and R2 coefficient in Design Expert software. Our models in the previous works follow the style of (y=f(A,B,. . .)) and two Desirability of 0.968 and 0.996 for Paenibacillus alvei ARN63 and Bacillus...
A checkpointing technique for rollback error recovery in embedded systems
, Article 2006 International Conference on Microelectronics, ICM 2006, Dhahran, 16 December 2006 through 19 December 2006 ; 2006 , Pages 174-177 ; 1424407656 (ISBN); 9781424407651 (ISBN) ; Miremadi, S. G ; Fazeli, M ; Arabian Consulting Engineering Center; Saudi Binladin Group; Advanced Electronics Company; HEIP ; Sharif University of Technology
2006
Abstract
In this paper, a general Checkpointing technique for rollback error recovery for embedded systems is proposed and evaluated. This technique is independent of used processor and employs the most important feature in control flow error detection mechanisms to simplify checkpoint selection and to minimize the overall code overhead. In this way, during the implementation of a control flow checking mechanism, the checkpoints are added to the program. To evaluate the Checkpointing technique, a pre-processor is implemented that selects and adds the checkpoints to three workload programs running in an 8051 microcontroller -based system. The evaluation is based on 3000 experiments for each...