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    Navigating towards sustainable development: A system dynamics approach

    , Article Futures ; Volume 38, Issue 1 , 2006 , Pages 74-92 ; 00163287 (ISSN) Hjorth, P ; Bagheri, A ; Sharif University of Technology
    2006
    Abstract
    Traditional fragmented and mechanistic science is unable to cope with issues about sustainability, as these are often related to complex, self-organizing systems. In the paper, sustainable development is seen as an unending process defined neither by fixed goals nor by specific means of achieving them. It is argued that, in order to understand the sources of and the solutions to modern problems, linear and mechanistic thinking must give way to non-linear and organic thinking, more commonly referred to as systems thinking. System Dynamics, which operates in a whole-system fashion, is put forward as a powerful methodology to deal with issues of sustainability. Examples of successful... 

    The extent of EFQM effectiveness in routine and non-routine organizations based on multivariate techniques: an empirical study

    , Article Operational Research ; 2016 , Pages 1-31 ; 11092858 (ISSN) Bagheri, F ; Noorossana, R ; Najmi, M ; Sharif University of Technology
    Springer Verlag  2016
    Abstract
    Despite the fact that a variety of analyses are conducted based on the performance of business excellence models according to organization type such as ownership, size and etc., the performance of organizations based on the factor of being routine or non-routine has not been investigated yet. In this paper, implementation of the European Foundation for Quality Management (EFQM) model for these types of organizations (routine and non-routine) has been examined. In order to do that, first we have developed a methodology to classify organizations into routine and non-routine categories. Then we have used discriminant analysis based on three factors, including process uncertainty, knowledge... 

    The extent of EFQM effectiveness in routine and non-routine organizations based on multivariate techniques: an empirical study

    , Article Operational Research ; Volume 19, Issue 1 , 2019 , Pages 237-267 ; 11092858 (ISSN) Bagheri, F ; Noorossana, R ; Najmi, M ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    Despite the fact that a variety of analyses are conducted based on the performance of business excellence models according to organization type such as ownership, size and etc., the performance of organizations based on the factor of being routine or non-routine has not been investigated yet. In this paper, implementation of the European Foundation for Quality Management (EFQM) model for these types of organizations (routine and non-routine) has been examined. In order to do that, first we have developed a methodology to classify organizations into routine and non-routine categories. Then we have used discriminant analysis based on three factors, including process uncertainty, knowledge... 

    On competence of vendor managed inventory in supply chains using basic mathematical inventory models

    , Article Scientia Iranica ; Vol. 21, issue. 3 , 2014 , p. 1061-1071 Jasemi, M ; Haji, A ; Gharibi, M ; Sharif University of Technology
    Abstract
    In this study, a two-echelon single-vendor supply chain is selected to do a cost-based comparison between short-term performances of a Vendor Managed Inventory (VMI) and a Retailer Managed Inventory (RMI). While the inventory costs include ordering and storing expenses, the rate of consumption and the price of goods are constant, the rate of production and pace of transportation are infinite and shortage is not allowed. This paper, after a comprehensive literature review, is followed by three cases of single retailer, n-retailer and two-retailer chains. Unlike the second case, in the first case, VMI shows an absolute superiority to RMI, and this is the reason for devising the third case in... 

    Enhanced separation performance of PVDF/PAN blend membrane based on PVP tuning

    , Article Desalination and Water Treatment ; Volume 57, Issue 26 , 2016 , Pages 12090-12098 ; 19443994 (ISSN) Anvari, A ; Safekordi, A ; Hemmati, M ; Rekabdar, F ; Tavakolmoghadam, M ; Azimi Yancheshme, A ; Gheshlaghi, A ; Sharif University of Technology
    Taylor and Francis Inc  2016
    Abstract
    Ultrafiltration (UF) membranes were prepared from blends of poly(vinylidene fluoride) (PVDF)/polyacrylonitrile (PAN) via phase inversion method induced by immersion precipitation. Polyvinylpyrrolidone (PVP) was used as pore former and hydrophilic polymeric additive. N,N-dimethylacetamide (DMAc) and water were used as solvent and coagulant (non-solvent), respectively. The effect of different concentrations of PVP on the morphology and performance of the prepared membranes was investigated. Performance of the membranes was evaluated based on pure water flux and filtration of buffered bovine serum albumin (BSA) solution. The contact angle measurements indicated that the hydrophilicity of... 

    Development of the group malmquist productivity index on non-discretionary factors

    , Article International Journal of Environmental Research ; Volume 3, Issue 1 , 2009 , Pages 109-116 ; 17356865 (ISSN) Abbaspour, M ; Hosseinzadeh Lofti, F ; Karbassi, A. R ; Roayaei, E ; Nikoomaram, H ; Sharif University of Technology
    2009
    Abstract
    Data envelopment analysis (DEA) measures the relative efficiency of a homogenous set of decision-making units (DMUs) when multiple inputs and outputs are present. The DEA-based Malmquist productivity index measuring the productivity change of DMUs over time has proven itself to be a valid tool to compare group performance. However, in the previous models developed for this purpose, it was supposed that all factors were controllable or discretionary. It is noteworthy that in most real cases, there are some inputs and outputs that are non-discretionary or semi-discretionary. Therefore, the main objective of the present study was to develop the DEA-based Malmquist productivity index on such... 

    Flux enhancement of thin-film composite membrane by graphene oxide incorporation

    , Article Journal of Environmental Health Science and Engineering ; Volume 17, Issue 1 , 2019 , Pages 377-382 ; 2052336X (ISSN) Jalali, S ; Rashidi Mehrabadi, A ; Shayegan, J ; Mirabi, M ; Madaeni, S. S ; Sharif University of Technology
    BioMed Central Ltd  2019
    Abstract
    Reverse Osmosis (RO) is a rapid-developing desalination technology; however, it suffers from inefficient energy consumption. To reduce energy consumption, in this study, reverse osmosis thin-film composite membrane (TFC) module was prepared and composed of m-phenylenediamine (MPD), graphene oxide, and 1,3,5-benzenetricarbonyl chloride (TMC) by interfacial polymerization on the surface of a polysulfone substrate. The graphene oxide was embedded in the mentioned thin-film composite by adding it to MPD aqueous solution to enhance permeation flux and, thus, reduce energy consumption. This study assessed the performance of the membrane using a lab-scale RO setup and evaluated permeability and... 

    Experimental modeling of twin-entry radial turbine

    , Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 32, Issue 6 , December , 2008 , Pages 571-584 ; 10286284 (ISSN) Aghaali, H ; Hajilouy Benisi, A ; Sharif University of Technology
    2008
    Abstract
    In this paper the performance characteristics of a turbocharger twin-entry radial inflow gas turbine with asymmetrical volute and rotor tip diameter of 73.6 mm in steady state and under full and partial admission conditions are investigated. The employed method is based on one dimensional performance prediction which is developed for partial admission conditions. Furthermore, this method is developed for the asymmetrical volute of the turbine considering the flow specifications. Experimental investigation of the research was carried out on special test facilities under full and partial admission conditions for a wide range of speeds. A comparison of experimental and modeling results shows... 

    A tunable high-Q active inductor with a feed forward noise reduction path

    , Article Scientia Iranica ; Volume 21, Issue 3 , 2014 , Pages 945-952 ; ISSN: 10263098 Moezzi, M ; Bakhtiar, M. S ; Sharif University of Technology
    Abstract
    The analysis and design of a tunable low noise active inductor is presented. The noise performance of the proposed gyrator-based active inductor is improved without either degrading its quality factor or consuming more power using a linear Feed Forward Path (FFP). The proposed low noise active inductor has been designed and fabricated using standard 0.18-μm CMOS technology. The measurements show a 3 fold improvement in the input noise current compared to that of conventional active inductors. The active inductor was tuned and measured at the resonance frequency of 2.5 GHz, which could be extended as high as 5.5 GHz, with a quality factor of 30. The circuit draws 4.8 mA from a 1.8 V supply  

    Performance of a single chamber microbial fuel cell at different organic loads and pH values using purified terephthalic acid wastewater

    , Article Journal of Environmental Health Science and Engineering ; Volume 13, Issue 1 , April , 2015 ; 2052336X (ISSN) Marashi, S. K. F ; Kariminia, H. R ; Sharif University of Technology
    BioMed Central Ltd  2015
    Abstract
    Background: Purified terephthalic acid (PTA) wastewater from a petrochemical complex was utilized as a fuel in the anode of a microbial fuel cell (MFC). Effects of two important parameters including different dilutions of the PTA wastewater and pH on the performance of the MFC were investigated. Methods: The MFC used was a membrane-less single chamber consisted of a stainless steel mesh as anode electrode and a carbon cloth as cathode electrode. Both power density and current density were calculated based on the projected surface area of the cathode electrode. Power density curve method was used to specify maximum power density and internal resistance of the MFC. Results: Using 10-times,... 

    Investigation of photocatalytic performance of TiO2 network and fiber geometries

    , Article Desalination and Water Treatment ; Volume 57, Issue 50 , 2016 , Pages 23644-23650 ; 19443994 (ISSN) Koohestani, H ; Sadrnezhaad, S. K ; Kheilnejad, A ; Sharif University of Technology
    Taylor and Francis Inc  2016
    Abstract
    In typical photocatalytic processes slurry reactors are used in which catalyst particles have to be separated from the solution after the process ends which means much higher time and costs. Hence, immobilizing process is carried out on the catalyst to overcome this problem. In this work, fiber and network geometries were produced by particle precipitation on substrates. The obtained structures were characterized by XRD, SEM, and Brunauer–Emmett–Teller analyses. Photocatalytic performance of the samples was investigated by methyl orange degradation and also by hydrogen generation from water/methanol splitting. From the SEM images, the size range of the TiO2 particles in the network... 

    Investigating morphology and performance of cellulose acetate butyrate electrospun nanofiber membranes for tomato industry wastewater treatment

    , Article Desalination and Water Treatment ; Volume 64 , 2017 , Pages 127-135 ; 19443994 (ISSN) Hosseini, S. A ; Soltanieh, M ; Mousavi, S. M ; Sharif University of Technology
    Desalination Publications  2017
    Abstract
    In this research, cellulose acetate butyrate (CAB) electrospun nanofiber membrane (ENM) was prepared by electrospinning method in order to separate the contaminants of an industrial wastewater. The influence of various electrospinning parameters on morphology and average fiber diameter of the membranes were investigated by scanning electron microscopy and image analysis. The permeability of the membranes was evaluated by measuring pure water flux. In order to investigate the performance of the prepared membranes for tomato wastewater treatment, the rejection of the pollution indices and flux were determined. The results demonstrated the potential of using CAB nanofiber membrane for... 

    Performance of the general circulation models in simulating temperature and precipitation over Iran

    , Article Theoretical and Applied Climatology ; 2018 , Pages 1-19 ; 0177798X (ISSN) Abbasian, M ; Moghim, S ; Abrishamchi, A ; Sharif University of Technology
    Springer-Verlag Wien  2018
    Abstract
    General Circulation Models (GCMs) are advanced tools for impact assessment and climate change studies. Previous studies show that the performance of the GCMs in simulating climate variables varies significantly over different regions. This study intends to evaluate the performance of the Coupled Model Intercomparison Project phase 5 (CMIP5) GCMs in simulating temperature and precipitation over Iran. Simulations from 37 GCMs and observations from the Climatic Research Unit (CRU) were obtained for the period of 1901–2005. Six measures of performance including mean bias, root mean square error (RMSE), Nash-Sutcliffe efficiency (NSE), linear correlation coefficient (r), Kolmogorov-Smirnov... 

    Performance of the general circulation models in simulating temperature and precipitation over Iran

    , Article Theoretical and Applied Climatology ; Volume 135, Issue 3-4 , 2019 , Pages 1465-1483 ; 0177798X (ISSN) Abbasian, M ; Moghim, S ; Abrishamchi, A ; Sharif University of Technology
    Springer-Verlag Wien  2019
    Abstract
    General Circulation Models (GCMs) are advanced tools for impact assessment and climate change studies. Previous studies show that the performance of the GCMs in simulating climate variables varies significantly over different regions. This study intends to evaluate the performance of the Coupled Model Intercomparison Project phase 5 (CMIP5) GCMs in simulating temperature and precipitation over Iran. Simulations from 37 GCMs and observations from the Climatic Research Unit (CRU) were obtained for the period of 1901–2005. Six measures of performance including mean bias, root mean square error (RMSE), Nash-Sutcliffe efficiency (NSE), linear correlation coefficient (r), Kolmogorov-Smirnov... 

    A new approach for bidding strategy of gencos using particles swarm optimization combined with simulated annealing method

    , Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 31, Issue 3 , 2007 , Pages 303-315 ; 03601307 (ISSN) Soleymani, S ; Ranjbar, A. M ; Bagheri Shouraki, S ; Shirani, A. R ; Sadati, N ; Sharif University of Technology
    2007
    Abstract
    This paper describes a procedure that uses particle swarm optimization (PSO) combined with the simulated annealing (SA) to analyze the bidding strategy of Generating Companies (Gencos) in an electricity market where they have incomplete information about their opponents. In the proposed methodology, Gencos prepare their strategic bids according to the Supply Function Equilibrium (SFE) model and they change their bidding strategies until Nash equilibrium points are obtained. Nash equilibrium points constitute a central solution concept in the game theory and are computed with solving a global optimization problem. In this paper a new computational intelligence technique is introduced that can... 

    A hardwired discrete simulation algorithm

    , Article Scientia Iranica ; Volume 14, Issue 6 , 2007 , Pages 566-570 ; 10263098 (ISSN) Nojumi, M. H ; Sharif University of Technology
    Sharif University of Technology  2007
    Abstract
    The architecture of a hardwired simulator for implementation of a discrete event-driven simulation of digital systems at the logic level is presented. In the design of this system, attempts have been made to utilize techniques of high performance computing to have a system capable of simulating the digital circuits rapidly. The centralized event-driven simulation algorithm chosen here, has the advantages of being efficient and conceptually straightforward. The high reliability of the simulator has been taken care of through a collection of handshake signals between each two of the three main modules. © Sharif University of Technology, December 2007  

    Second law analysis of a magnetohydrodynamic plasma generator

    , Article Energy ; Volume 32, Issue 9 , 2007 , Pages 1603-1616 ; 03605442 (ISSN) Saidi, M. H ; Montazeri, A ; Sharif University of Technology
    Elsevier Ltd  2007
    Abstract
    The performance of an MHD generator utilizing plasma as working fluid has been assessed from the viewpoint of the second law of thermodynamics. The plasma flow in the generator linear duct has been solved by dividing the channel cross-section to an inviscid core region and the viscous boundary layers in the vicinity of the walls. The Hall effect has been taken into account and equilibrium ionization has been assumed. The dependence of the plasma properties such as Hall parameter, the coefficients of thermal and electrical conductivity, and viscosity on the plasma state has also been considered. Using the information obtained on the plasma behaviour in the generator, the entropy generation... 

    A rule-based advanced static var compensator control scheme for transient stability improvement

    , Article Scientia Iranica ; Volume 13, Issue 4 , 2006 , Pages 327-336 ; 10263098 (ISSN) Abazari, S ; Ehsan, M ; Zolghadri, M. R ; Mahdavi, J ; Sharif University of Technology
    Sharif University of Technology  2006
    Abstract
    The paper presents the application of a rule- based control scheme for an Advanced Static Var Compensator (ASVC) to improve power system transient stability. The proposed method uses a current reference, based on the Transient Energy Function (TEF) approach. The proposed scheme provides, also, a continuous control of the reactive power flow. The performance of the proposed approach is compared with that of a system using a conventional control method and of a system without ASVC. A single-machine system and an IEEE three machine system are used to verify the performance of the proposed method. © Sharif University of Technology  

    Performance analysis of per tone equalization in DMT-based systems

    , Article Scientia Iranica ; Volume 13, Issue 4 , 2006 , Pages 355-363 ; 10263098 (ISSN) Changiz Rezaei, S. S ; Pakravan, M. R ; Sharif University of Technology
    Sharif University of Technology  2006
    Abstract
    The Per Tone equalization algorithm is a novel discrete multitone (DMT) equalization method with practical applications in subscriber digital loop systems. Unlike time domain DMT equalizers (TEQ), which equalize all DMT tones in a combined fashion, the Per Tone equalizer equalizes each tone separately. In this paper, the performance and complexity of this technique is investigated and compared with that of other TEQs. Furthermore, the behavior of this technique in different simulation conditions, such as over different standard CSA loops and in the presence of additive white Gaussian noise with variable power spectral density level and near end crosstalk (NEXT), is studied and compared with... 

    Extended and Unscented Kalman filters for parameter estimation of an autonomous underwater vehicle

    , Article Ocean Engineering ; Vol. 91, issue , 2014 , p. 329-339 Sabet, M. T ; Sarhadi, P ; Zarini, M ; Sharif University of Technology
    Abstract
    In this paper, a high performance procedure for estimating of hydrodynamic coefficients in Autonomous Underwater Vehicles (AUV's) is proposed. In modeling of an AUV, experimental data should be verified and validated using appropriate techniques. Due to implementation complexity in calculating methods, computation of hydrodynamic parameters is challenging. This paper presents analytical approaches for estimating an AUV's hydrodynamic coefficients. Nonlinear Kalman Filter (KF) algorithms are implemented to estimate unknown augmented states (coefficients). A comparative study is conducted which shows the superior performance of Unscented Kalman Filter (UKF) in comparison with Extended Kalman...