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    Stress field in the thermoelastic rolling contact of graded coatings

    , Article Archive of Applied Mechanics ; Volume 88, Issue 10 , 2018 , Pages 1805-1814 ; 09391533 (ISSN) Nili, A ; Adibnazari, S ; Karimzadeh, A ; Sharif University of Technology
    Springer Verlag  2018
    Abstract
    The thermoelastic rolling contact problem for an FGM-coated half plane under the plane strain deformation is studied in this paper. A rigid roller rolls over the surface of coating with constant translational velocity generating frictional heating in the slip zones of the contact patch. The material properties of the FGM vary exponentially along the thickness direction. It is assumed that the contact area consists of a central stick zone and two slip zones of the same sign. The transfer matrix method and Fourier integral transform technique are used to achieve a system of two Cauchy singular integral equations. The coupling effect of tangential traction is eliminated by adapting the... 

    Rolling contact mechanics of graded coatings involving frictional heating

    , Article Acta Mechanica ; Volume 230, Issue 6 , 2019 , Pages 1981-1997 ; 00015970 (ISSN) Nili, A ; Adibnazari, S ; Karimzadeh, A ; Sharif University of Technology
    Springer-Verlag Wien  2019
    Abstract
    The two-dimensional thermoelastic tractive rolling contact problem for a half-plane which is coated with a functionally graded material (FGM), under the plane strain deformation, is studied in this paper. A rigid cylinder rolls over the surface of an FGM coating with constant translational velocity, generating frictional heating in the slip zones of the contact area. Thermomechanical properties of the FGM vary exponentially along the thickness direction. It is assumed that the contact area consists of a central stick zone and two slip zones of the same sign. The transfer matrix method and Fourier integral transform technique are used to achieve a system of two Cauchy singular integral... 

    The Effect of Political Systems on Economic Performance in Resource-Rich Countries

    , M.Sc. Thesis Sharif University of Technology Hosseini, Mohammad (Author) ; Nili, Farhad (Supervisor) ; Nili, Masoud (Co-Advisor)
    Abstract
    In this research, the effect of political system on economic performance of resource abundant countries is studied. We use political economy litreture to develop a theoritical model in this issue. Here, the politcal systems are divided to democracy and dictatory and in each of them other institutional variable will be introduced. Policy indicator is based on the difference between social welfare in each situation and its optimal amount when maximized. We show that if democracy does not come with high accountability it reduces social welfare more than dictatory. Also, if politician are myopic, democracy aggravates economic performance in those countries. In addition, easy access to income... 

    A novel aerodynamic design method for centrifugal compressor impeller

    , Article Journal of Applied Fluid Mechanics ; Vol. 7, issue. 2 , July , 2014 , p. 329-344 Nili-Ahmadabadi, M ; Durali, M ; Hajilouy, A ; Sharif University of Technology
    2014
    Abstract
    This paper describes a new quasi-3D design method for centrifugal compressor impeller. The method links up a novel inverse design algorithm, called Ball-Spine Algorithm (BSA), and a quasi-3D analysis. Euler equation is solved on the impeller meridional plane. The unknown boundaries (hub and shroud) of numerical domain are iteratively modified by BSA until a target pressure distribution in flow passage is reached. To validate the quasi-3D analysis code, existing compressor impeller is investigated experimentally. Comparison between the quasi-3D analysis and the experimental results shows good agreement. Also, a full 3D Navier-Stokes code is used to analyze the existing and designed compressor... 

    Real Effects of Financial Frictions: The Role of Working Capital

    , Ph.D. Dissertation Sharif University of Technology Mahmoudzadeh Ahmadinejad, Amineh (Author) ; Nili, Masoud (Supervisor) ; Nili, Farhad (Co-Advisor)
    Abstract
    Our study investigates the real consequences of variations in the first and second moments of working capital requirement (WCR) in the presence of financial frictions. We introduce a theoretical link from imperfect information about WCR to firms’ performance. Firms choose non-prepaid factors of production with uncertainty about required prepayments, where their access to credit is constrained by collateral. After realization, firms with higher WCR may face financial constraints. This uncertainty influences their demand for inputs, albeit risk-neutrality. Unable to employ the projected level of prepaid input, constrained firms encounter capacity underutilization, leading to misallocation of... 

    Population splitting of rodlike swimmers in Couette flow

    , Article Soft Matter ; Volume 13, Issue 25 , 2017 , Pages 4494-4506 ; 1744683X (ISSN) Nili, H ; Kheyri, M ; Abazari, J ; Fahimniya, A ; Naji, A ; Sharif University of Technology
    Royal Society of Chemistry  2017
    Abstract
    We present a quantitative analysis on the response of a dilute active suspension of self-propelled rods (swimmers) in a planar channel subjected to an imposed shear flow. To best capture the salient features of the shear-induced effects, we consider the case of an imposed Couette flow, providing a constant shear rate across the channel. We argue that the steady-state behavior of swimmers can be understood in the light of a population splitting phenomenon, occurring as the shear rate exceeds a certain threshold, initiating the reversal of the swimming direction for a finite fraction of swimmers from down- to upstream or vice versa, depending on the swimmer position within the channel.... 

    Experimental and numerical investigation of a centrifugal compressor

    , Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 3 , 2010 , Pages 447-458 ; 9780791849170 (ISBN) Karrabi, H ; Hajilouy Benisi, A ; Nili Ahmadabadi, M ; Sharif University of Technology
    2010
    Abstract
    In this research, centrifugal compressor of a gas turbine is investigated experimentally and numerically. Operation line of the compressor as a component of the gas turbine is obtained experimentally by measurements of impeller rotational speed, and flow parameters at the compressor inlet and outlet during the gas turbine operation. The flow field inside the impeller and diffusers are analyzed numerically using a full 3D Navier-Stokes program with SST turbulence model. Boundary conditions for the numerical simulation are specified from the experimental measurements. The operation line of the compressor is obtained numerically, which is compared with that of the experimental results, and... 

    A novel QUASI-3D design method for centrifugal compressor meridional plane

    , Article Proceedings of the ASME Turbo Expo, 14 June 2010 through 18 June 2010 ; Volume 7, Issue PARTS A, B, AND C , 2010 , Pages 919-931 ; 9780791844021 (ISBN) Nili Ahmadabadi, M ; Durali, M ; Hajilouy Benisi, A ; Sharif University of Technology
    2010
    Abstract
    This paper is concerned with a quasi-3D design method for centrifugal compressor impeller in the meridional plane. The method links up a novel inverse design algorithm, called Ball-Spine Algorithm (BSA), and a quasi-3D analysis code. The Euler equation is solved on the meridional plane for a numerical domain of which some unknown boundaries (hub and shroud) are iteratively modified under the BSA until a prescribed pressure distribution is reached. In BSA, the unknown walls are composed of a set of virtual balls that move freely along the specified directions called spines. The difference between target and current pressure distribution causes to deform flexible boundary at each modification... 

    Using distance on the Riemannian manifold to compare representations in brain and in models

    , Article NeuroImage ; Volume 239 , 2021 ; 10538119 (ISSN) Shahbazi, M ; Shirali, A ; Aghajan, H ; Nili, H ; Sharif University of Technology
    Academic Press Inc  2021
    Abstract
    Representational similarity analysis (RSA) summarizes activity patterns for a set of experimental conditions into a matrix composed of pairwise comparisons between activity patterns. Two examples of such matrices are the condition-by-condition inner product and correlation matrix. These representational matrices reside on the manifold of positive semidefinite matrices, called the Riemannian manifold. We hypothesize that representational similarities would be more accurately quantified by considering the underlying manifold of the representational matrices. Thus, we introduce the distance on the Riemannian manifold as a metric for comparing representations. Analyzing simulated and real fMRI... 

    , M.Sc. Thesis Sharif University of Technology (Author) ; Nili, Massoud (Supervisor)
    Abstract
    Theory says that prudential fiscal policies can mitigate the unintended consequences of business cycles. Does evidence support the effectiveness of fiscal policies is still a challenging question. In this thesis, I focus on the relationship between fiscal policies and aggregate movements in oil producing countries. I found significant pro-cyclicality in these countries in which questions the goal of their policy making. Furthermore, I show that in my sample of oil producers,data doesn’t support the poorer is the country, the higher is the pro-cyclicality of their fiscal policies  

    Duct design in subsonic and supersonic flow regimes with and without normal shock waves using Flexible String Algorithm

    , Article Scientia Iranica ; Volume 17, Issue 3 B , MAY-JUNE , 2010 , Pages 179-193 ; 10263098 (ISSN) Nili Ahmadabadi, M ; Durali, M ; Hajilouy Benisi, A ; Ghadak, F ; Sharif University of Technology
    2010
    Abstract
    In this investigation, the Flexible String Algorithm (FSA) used before for the inverse design of 2D subsonic ducts is developed and applied for the inverse design of subsonic and supersonic ducts with and without normal shock waves. In this method, the duct wall shape is changed under a novel algorithm based on the deformation of a virtual flexible string in a flow. Deformation of the string due to the local fl.ow conditions resulting from changes in the wall geometry is performed until the target shape satisfying the. prescribed walls pressure distribution is achieved. The flow field at each shape modification step is analyzed using an Euler equation solution by the. A USM method. Some... 

    A novel 2D incompressible viscous inverse design method for internal flows using flexible string algorithm

    , Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 132, Issue 3 , 2010 , Pages 0314011-03140110 ; 00982202 (ISSN) Nili Ahmadabadi, M ; Hajilouy Benisi, A ; Ghadak, F ; Durali, M ; Sharif University of Technology
    2010
    Abstract
    In this investigation, the flexible string algorithm (FSA), used before for inverse design of subsonic and supersonic ducts in compressible flows with and without normal shock, is developed and applied for inverse design of 2D incompressible viscous internal flow with and without separation. In the proposed method, the duct wall shape is changed under an algorithm based on deformation of a virtual flexible string in flow. At each modification step, the difference between current and target wall pressure distributions is applied to the string. The method is an iterative inverse design method and utilizes the analysis code for the flow field solution as a black-box. Some validation test cases... 

    Inverse design of 2-D subsonic ducts using flexible string algorithm

    , Article Inverse Problems in Science and Engineering ; Volume 17, Issue 8 , 2009 , Pages 1037-1057 ; 17415977 (ISSN) Nili Ahmadabadi, M ; Dural, M ; Hajilouy Benisi, A ; Ghadak, F ; Sharif University of Technology
    2009
    Abstract
    The duct inverse design in fluid flow problems usually involves finding the wall shape associated with a prescribed distribution of wall pressure or velocity. In this investigation, an iterative inverse design method for 2-D subsonic ducts is presented. In the proposed method, the duct walls shape is changed under a novel algorithm based on the deformation of a virtual flexible string in flow. The deformation of the string due to the local flow conditions resulting from changes in wall geometry is observed until the target shape satisfying the prescribed wall's pressure distribution is reached. The flow field at each step is analysed using Euler equations and the advection upstream splitting... 

    Duct design in subsonic & supersonic flow regimes with and without normal shock wave using flexible string algorithm

    , Article Proceedings of the ASME Turbo Expo, 8 June 2009 through 12 June 2009, Orlando, FL ; Volume 7, Issue PART A , 2009 , Pages 513-523 ; 9780791848883 (ISBN) Nili Ahmadabadi, M ; Hajilouy Benisi, A ; Durali, M ; Ghadak, F ; Sharif University of Technology
    2009
    Abstract
    In this investigation, the Flexible String Algorithm (FSA), used before for 2D subsonic ducts inverse design, is developed and applied to inverse design of supersonic ducts with and without normal shock wave. In this method, the duct wall shape is changed under an algorithm based on deformation of a virtual flexible string in a flow. The deformation of the string due to the local flow conditions resulting from changes in wall geometry is performed until the target shape satisfying the prescribed walls pressure distribution is achieved. The flow field at each step is analyzed using Euler equations solutions by the AUSM method. Some validation test cases and design examples in subsonic and... 

    Investigation of a centrifugal compressor and study of the area ratio and TIP clearance effects on performance

    , Article Journal of Thermal Science ; Volume 17, Issue 4 , December , 2008 , Pages 314-323 ; 10032169 (ISSN) Nili Ahmadabadi, M ; Hajilouy Benisi, A ; Durali, M ; Ghadak, F ; Sharif University of Technology
    2008
    Abstract
    In this research, the centrifugal compressor of a turbocharger is investigated experimentally and numerically. Performance characteristics of the compressor were obtained experimentally by measurements of rotor speed and flow parameters at the inlet and outlet of the compressor. Three dimensional flow field in the impeller and diffuser was analyzed numerically using a full Navier-Stokes program with SST turbulence model. The performance characteristics of the compressor were obtained numerically, which were then compared with the experimental results. The comparison shows good agreement. Furthermore, the effect of area ratio and tip clearance on the performance parameters and flow field was... 

    Addressing the growth failure of the oil economies: The role of financial development

    , Article Quarterly Review of Economics and Finance ; Volume 46, Issue 5 , 2007 , Pages 726-740 ; 10629769 (ISSN) Nili, M ; Rastad, M ; Sharif University of Technology
    2007
    Abstract
    The oil exporting countries have experienced a relatively continuous fall in GDP per capita over the last 30 years. This is in spite of benefiting from a more than average of the rest of the world investment rate. The findings of this paper, report a lower level of financial development for the oil economies when compared with the rest of the world. We will show in this paper that the higher rate of investment of the oil economies can be explained mainly by the oil revenues and surprisingly, financial development has a net dampening effect on investment for these economies. The paper also shows that the weakness of financial institutions, contributes to the poor performance of economic... 

    Linking an autonomy-supportive climate and employee creativity: the influence of intrinsic motivation and company support for creativity

    , Article European Business Review ; Volume 34, Issue 5 , 2022 , Pages 666-688 ; 0955534X (ISSN) Nili, F ; Tasavori, M ; Sharif University of Technology
    Emerald Group Holdings Ltd  2022
    Abstract
    Purpose: Employees’ creativity is critical for the growth and survival of firms. Therefore, the purpose of this study is to propose a motivational model of creativity to address the effect of an autonomy-supportive climate on employee creativity. This study investigates whether this effect is mediated by intrinsic motivation in employees and depends on company support for creativity. Design/methodology/approach: This study used a quantitative approach to collect data by conducting a survey in a developing country using paper-based questionnaires. From 220 questionnaires distributed, 151 usable survey responses were gathered for this study. In addition, structural equation modeling was used... 

    Long Term Effective Factors on House Price of Metropolises of Iran

    , M.Sc. Thesis Sharif University of Technology Moeeni, Safoura (Author) ; Nili, Masoud (Supervisor)
    Abstract
    The notable share of housing sector in GDP (approximately five percent) shows this sector’s relation with macroeconomic activities. On the other hand, House as an asset leads housing sector to be affected by monetary and fiscal variables. A dynamic panel data was used in this study to evaluate the relations between housing sector and some macroeconomic variables in metropolises of Iran. As results show, in long term growth of liquidity, GDP per capita and sharp ratio have positive effects, and land per capita has negative effect on housing price in metropolises of Iran. Price increases have not been equal in different cities. Inequality of land price between metropolises and between... 

    Estimating an Index of Iran’s Informal Economy in 1350-1386 With Concentration on the Impact of Government’s Intervention by EMIMIC Model (The Multiple Indicators-Multiple Causes Model and Error-Correction Model)

    , M.Sc. Thesis Sharif University of Technology Khandan, Abbas (Author) ; Nili, Masoud (Supervisor)
    Abstract
    In this research, an Index of Iran informal economy in response to the government interventions in credit, labor and product markets is stimated by EMIMIC model. To do this, first these interventions are measured using principal components analysis. In the model, the variables GDP and employment are used as indicators and taxation rates, government distortions in credit, labor and product markets, government expenditure, per capita income, unemployment and inflation as causes of the informal economy. We conclude these government interventions have affected Iran informal economy and their influence is more than indirect interventions influence such as taxation. The estimated index of Iran... 

    The Political Economy Aspects of the Redistributive Role of Government in a General Equilibrium Micro-founded Macro Model

    , M.Sc. Thesis Sharif University of Technology Zakeri, Hassan (Author) ; Nili, Masoud (Supervisor)
    Abstract
    The role of government in economy has been a controversial subject in economics. Lately, there has been some fundamental change in evaluating this subject. One could mention two of these as 1) realizing the importance of micro-founded macro model for evaluating policy, and 2) taking into consideration the rent-seeking behavior of politicians. In this research, a general equilibrium in a micro-founded macro model will be discussed and then in political economics framework, the effect of government on this equilibrium will be investigated. Only the redistribution role of government has been considered. First, the model in which a benevolent government is seeking optimal policy is Discussed....