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    Greenhouse gas emission measurement and economic analysis of Iran natural gas fired power plants

    , Article Energy Policy ; Volume 60 , 2013 , Pages 200-207 ; 03014215 (ISSN) Shahsavari Alavijeh, H ; Kiyoumarsioskouei, A ; Asheri, M. H ; Naemi, S ; Shahsavari Alavije, H ; Basirat Tabrizi, H ; Sharif University of Technology
    2013
    Abstract
    This study attempts to examine the natural gas fired power plants in Iran. The required data from natural gas fired power plants were gathered during 2008. The characteristics of thirty two gas turbine power plants and twenty steam power plants have been measured. Their emission factor values were then compared with the standards of Energy Protection Agency, Euro Union and World Bank. Emission factors of gas turbine and steam power plants show that gas turbine power plants have a better performance than steam power plants. For economic analysis, fuel consumption and environmental damages caused by the emitted pollutants are considered as cost functions; and electricity sales revenue are... 

    A viscoelastic-viscoplastic constitutive model considering damage evolution for time dependent materials: Application to asphalt mixes

    , Article International Journal of Damage Mechanics ; Volume 25, Issue 7 , 2016 , Pages 921-942 ; 10567895 (ISSN) Shahsavari, H ; Naghdabadi, R ; Baghani, M ; Sohrabpour, S ; Sharif University of Technology
    SAGE Publications Ltd  2016
    Abstract
    In this paper, employing the definition of an effective configuration in the continuum damage mechanics, mechanical response of a compressible viscoelastic-viscoplastic material is investigated. We present a phenomenological viscoelastic-viscoplastic-viscodamage constitutive model, developed within the framework of irreversible thermodynamics. The formulation is based on the additive decomposition of the total strain into elastic, viscoelastic, and viscoplastic parts in the effective configuration. Thus, the Helmholtz energy is partitioned into elastic, elastic-viscoelastic, and viscoplastic parts. Then, each one is divided into deviatoric and volumetric energies. Considering the... 

    Continuum damage-healing constitutive modeling for concrete materials through stress spectral decomposition

    , Article International Journal of Damage Mechanics ; Volume 25, Issue 6 , 2016 , Pages 900-918 ; 10567895 (ISSN) Shahsavari, H ; Baghani, M ; Sohrabpour, S ; Naghdabadi, R ; Sharif University of Technology
    SAGE Publications Ltd  2016
    Abstract
    Self-healing concrete materials have the capability to recover a part of the weakened mechanical properties induced by damage. In this paper, a constitutive model is proposed to investigate damage and healing phenomena in concrete materials. In order to consider the different behavior of concretes in tension and compression, a spectral decomposition of the stress is utilized. In addition, employing the Clausius-Duhem inequality and considering the irreversible thermodynamics, conjugate forces of the damage and healing are expressed. The Gibbs potential energy is decomposed into three parts: elastic, damage and healing. In this regard, damage and healing behavior are distinguished from the... 

    A finite deformation viscoelastic-viscoplastic constitutive model for self-healing materials

    , Article Smart Materials and Structures ; Volume 25, Issue 12 , 2016 , Pages 1DUMMY- ; 09641726 (ISSN) Shahsavari, H ; Naghdabadi, R ; Baghani, M ; Sohrabpour, S ; Sharif University of Technology
    Institute of Physics Publishing  2016
    Abstract
    In this paper, employing the Hencky strain, viscoelastic-viscoplastic response of self-healing materials is investigated. Considering the irreversible thermodynamics and using the effective configuration in the Continuum Damage-Healing Mechanics (CDHM), a phenomenological finite strain viscoelastic-viscoplastic constitutive model is presented. Considering finite viscoelastic and viscoplastic deformations, total deformation gradient is multiplicatively decomposed into viscoelastic and viscoplastic parts. Due to mathematical advantages and physical meaning of Hencky strain, this measure of strain is employed in the constitutive model development. In this regard, defining the damage and healing... 

    A thermodynamically consistent viscoelastic–viscoplastic constitutive model for self-healing materials

    , Article Journal of Intelligent Material Systems and Structures ; Volume 29, Issue 6 , 2018 , Pages 1065-1080 ; 1045389X (ISSN) Shahsavari, H ; Baghani, M ; Naghdabadi, R ; Sohrabpour, S ; Sharif University of Technology
    SAGE Publications Ltd  2018
    Abstract
    Self-healing materials, as a class of intelligent materials, are capable to recover a part of the weakened mechanical properties induced by damage. In this article, based on the thermodynamics of irreversible processes, employing the effective configuration in the continuum damage-healing mechanics, a viscoelastic–viscoplastic constitutive model is presented. In the constitutive model development, we adopt an additive decomposition of the total strain into elastic, viscoelastic, and viscoplastic parts. In this regard, defining the damage and healing variables and employing the strain energy equivalence hypothesis, stress and strain tensors in the effective configuration are obtained.... 

    Phase equilibrium modeling of semi-clathrate hydrates of the CO2+H2/CH4/N2+TBAB aqueous solution system

    , Article Petroleum Science and Technology ; Volume 35, Issue 15 , 2017 , Pages 1588-1594 ; 10916466 (ISSN) Mesbah, M ; Soroush, E ; Roham, M ; Shahsavari, S ; Sharif University of Technology
    Taylor and Francis Inc  2017
    Abstract
    In this study, the semi-clathrate hydrate dissociation pressure for the CO2+N2, CO2+H2, CO2+CH4, and pure CO2 systems in the presence of different concentrations of TBAB aqueous solutions is predicted using a strong machine learning technique of multi-layer perceptron neural network (MLP-NN). The developed model, with an overall correlation coefficient (R2) of 0.9961 and mean square error (MSE) of 5.96E−02, presented an excellent accuracy in prognosticating experimental data. A complete statistical evaluation performed to promise the strength and generality of the multi-layer perceptron artificial neural network (MLP-ANN). In addition, the applicability of the proposed network and quality of... 

    Effect of preweld microstructure on HAZ liquation cracking of rene 80 superalloy

    , Article Materials Science and Technology ; Volume 23, Issue 5 , 2007 , Pages 547-555 ; 02670836 (ISSN) Shahsavari, H. A ; Kokabi, A. H ; Nategh, S ; Sharif University of Technology
    2007
    Abstract
    The objective of this work was to study the microstructure of as cast, solution treated and overaged Rene 80 superalloy before and after welding treatment. Studies focused on identifying heat affected zone (HAZ) liquation cracking mechanism and the effect of preweld microstructure on it. The formation of HAZ liquation cracking or microfissuring is found to be strongly dependent on constitutional liquation of grain boundary precipitates. These liquated precipitates in the as cast state contain MC carbides and particularly γ/γ' eutectic islands. While in the overaged condition they consist of the MC carbides and borides. Also HAZ grain boundary liquation and subsequent resolidification occur... 

    Supercritical carbon dioxide utilization in drug delivery: Experimental study and modeling of paracetamol solubility

    , Article European Journal of Pharmaceutical Sciences ; Volume 177 , 2022 ; 09280987 (ISSN) Bagheri, H ; Notej, B ; Shahsavari, S ; Hashemipour, H ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    In the present study, the solubility of paracetamol in supercritical CO2 is measured at temperatures between 311 and 358 K and pressures between 95 and 265 bar. It was shown that the solubility of paracetamol through a static solubility measurement method was between 0.3055 × 10−6 to 16.3582 × 10−6 based on mole fraction. The obtained experimental solubility data revealed the direct effect of pressure on the paracetamol experimental data, while the temperature has a dual effect of both increasing and decreasing effect considering the shifting point known as crossover pressure which was measured to be around 110 bar for paracetamol. Besides, two theoretical approaches were applied to predict... 

    Computational study on design parameters of a solar chimney

    , Article International Conference on Sustainable Mobility Applications, Renewables and Technology, 23 November 2015 through 25 November 2015 ; 2015 ; 9781467395298 (ISBN) Esfidani, M. T ; Raveshi, S ; Shahsavari, M ; Sedaghat, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Abstract
    Today, the production of energy and electricity is one of the major concerns of mankind. Electricity generation by solar energy is considered as one of the alternatives to fossil fuels. Solar chimneys mechanism is based on a natural phenomenon. In this process the solar energy heat up the earth's surface and the surrounding air. Due to the density difference between cold air and warm air, heated air ascends and causes air circulation. In this study, mathematical modelling of solar chimney and governing equations of this system will be discussed. In order to validate the numerical results, upwind velocity in chimney has been compared with a reliable reference results. As well as, the... 

    Experimental Study of Low Swirl Burners Interferences

    , M.Sc. Thesis Sharif University of Technology Shahsavari, Mohammad (Author) ; Farshchi, Mohammad (Supervisor)
    Abstract
    One of the problems associated with lean premixed combustion is their stability. Low swirl flame is a modern technology for reducing NOx emissions and increasing stability.In this thesis, first, the effect of geometric parameters on the flame stability was investigated. This study was carried out in high fuel and oxidizer mixture flow rate. Having find, the most stable burner, two other burners with the same geometrical parameters were built. Stability of these three burners were analyzed. Second, they were located in a ring together in three different relative positions. In each configuration stability and NOx emissions of the burners were determined.The study shows that NOx and CO... 

    Speech Activity Detection Using Deep Networks

    , M.Sc. Thesis Sharif University of Technology Shahsavari, Sajad (Author) ; Sameti, Hossein (Supervisor)
    Abstract
    In this paper, we introduce a new dataset for SAD and evaluate certain common methods such as GMM, ANN, and RNN on it. We have collected our dataset in a semi-supervised approach, using subtitled movies, with a labeling accuracy of 95%. This semi-automatic method can help us collect huge amounts of labeled audio data with very high diversity in language, speaker, and channel. We model the problem of SAD as a classification task to two classes of speech and non-speech. When using GMM for this problem, we use two separate mixtures to model speech and non-speech. In the case of neural networks, we use a softmax layer at the end of the network, with two neurons which represent speech and... 

    Large eddy simulation of low swirl flames under external flow excitations

    , Article Flow, Turbulence and Combustion ; Volume 100, Issue 1 , 2018 , Pages 249-269 ; 13866184 (ISSN) Shahsavari, M ; Farshchi, M ; Sharif University of Technology
    Springer Netherlands  2018
    Abstract
    Low swirl flame characteristics under external flow excitations are numerically investigated using large eddy simulations with a dynamically thickened flame combustion model. A finite volume scheme on a Cartesian grid with a dynamic one equation eddy viscosity subgrid scale model is used for large eddy simulations. The excitations are imposed on inlet velocity profiles by a sinusoidal forcing function over a wide range of amplitudes and frequencies. Present investigation shows that although, the swirling motion of the low swirl flame is not intense enough to induce a recirculation zone in ensemble averaged results, external flow excitations increase the local swirl number upstream of the... 

    Low Swirl Flame Dynamic under Vortical Flow Disturbances

    , Ph.D. Dissertation Sharif University of Technology Shahsavari, Mohammad (Author) ; Farshchi, Mohammad (Supervisor)
    Abstract
    Lean premixed combustion is highly susceptible to thermoacoustic instabilities. Such instabilities are compounded in low swirl flames by the fact that low swirl flames are stabilized aerodynamically at a relatively considerable distance downstream of the burner rim, such stabilization mechanism makes the flame more prone to both vertical and acoustic perturbations. The main objective of the present thesis is to evaluate effects of acoustic and hydrodynamic perturbations on low swirl flame features. To such aim, first, low swirl flame characteristics and stabilization mechanism are studied using large eddy simulations along with thickened flame combustion model. The obtained results show that... 

    Dynamics and Heat transfer of Two-phase Non-Newtonian Fluids in Superhydrophobic Channels

    , M.Sc. Thesis Sharif University of Technology Shahsavari, Arghavan (Author) ; Moosavi, Ali (Supervisor)
    Abstract
    When the fluid passes through the microchannel, some energy is lost due to drag force and pressure drop. One of the methods used in the last few decades to optimize energy consumption is creating superhydrophobic surfaces in microchannels. These surfaces, with their features such as increasing the contact angle and reducing the contact angle hysteresis, can reduce energy loss, which is due to the presence of unevenness on the surface, and by trapping air and creating a two-phase flow, they reduce the drag force. On the other hand, the air trapped inside these irregularities will also affect the heat transfer of the passing fluid in the microchannel, which by creating resistance in the... 

    Multifunctional Ag/AgCl/ZnTiO3 structures as highly efficient photocatalysts for the removal of nitrophenols, CO2 photoreduction, biomedical waste treatment, and bacteria inactivation

    , Article Applied Catalysis A: General ; Volume 643 , 2022 ; 0926860X (ISSN) Padervand, M ; Ghasemi, S ; Hajiahmadi, S ; Rhimi, B ; Nejad, Z. G ; Karima, S ; Shahsavari, Z ; Wang, C ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    Over the past few decades, biological hazards and organic pollution have become major environmental concerns. Photocatalysis has been found to be effective in minimizing the negative impacts of these issues in air and water. Lozenge shape Ag/AgCl/ZnTiO3 photocatalysts were fabricated by a facile two-step synthesis method, including hydrothermal and coprecipitation. The physicochemical characteristics and morphological properties of the structures were comprehensively described taking advantage of a multi-technique approach. The prepared photocatalysts offered excellent nitrophenol mineralization (>90%) after 90 min of visible light irradiation. Based on the spin-trapping ESR technique, •O2̅–... 

    Analytical investigation of composite sandwich beams filled with shape memory polymer corrugated core

    , Article Meccanica ; Volume 54, Issue 10 , 2019 , Pages 1647-1661 ; 00256455 (ISSN) Akbari Azar, S ; Baghani, M ; Zakerzadeh, M. R ; Shahsavari, H ; Sohrabpour, S ; Sharif University of Technology
    Springer Netherlands  2019
    Abstract
    Shape memory polymers (SMPs) are a class of smart materials which can recover their shape even after many shape changes in application of an external stimulus. In this paper, flexural behavior of a composite beam, constructed of a corrugated part filled with SMPs, is studied. This composite beam is applicable in sensor and actuator applications. Since the corrugated profiles display higher stiffness-to-mass ratio in the transverse to the corrugation direction, the beams with a corrugated part along the transverse direction are stiffer than ones with a corrugated part along the length. Employing a developed constitutive model for SMPs and the Euler–Bernoulli beam theory, the behavior of the... 

    Cyclometalated platinum(II) complexes of 2,2′-bipyridine N-oxide containing a 1,1′-bis(diphenylphosphino)ferrocene ligand: structural, computational and electrochemical studies

    , Article Dalton Transactions ; Volume 46, Issue 6 , 2017 , Pages 2013-2022 ; 14779226 (ISSN) Shahsavari, H. R ; Fereidoonnezhad, M ; Niazi, M ; Mosavi, S. T ; Habib Kazemi, S ; Kia, R ; Shirkhan, S ; Abdollahi Aghdam, S ; Sharif University of Technology
    Royal Society of Chemistry  2017
    Abstract
    The preparation and characterization of new heteronuclear-platinum(ii) complexes containing a 1,1'-bis(diphenylphosphino)ferrocene (dppf) ligand are described. The reaction of the known starting complex [PtMe(κ2N,C-bipyO-H)(SMe2)], A, in which bipyO-H is a cyclometalated rollover 2,2'-bipyridine N-oxide, with the dppf ligand in a 2:1 ratio or an equimolar ratio led to the formation of the corresponding binuclear complex [Pt2Me2(κ2N,C-bipyO-H)2(μ-dppf)], 1, or the mononuclear complex [PtMe(κ1C-bipyO-H)(dppf)], 2, respectively. According to the reaction conditions, the dppf ligand in 1 and 2 behaves as either a bridging or chelating ligand. All complexes were characterized by NMR spectroscopy.... 

    Statistical distribution of intensity fluctuations for underwater wireless optical channels in the presence of air bubbles

    , Article IWCIT 2016 - Iran Workshop on Communication and Information Theory, 3 May 2016 through 4 May 2016 ; 2016 ; 9781509019229 (ISBN) Jamali, M. V ; Khorramshahi, P ; Tashakori, A ; Chizari, A ; Shahsavari, S ; Abdollahramezani, S ; Fazelian, M ; Bahrani, S ; Salehi, J. A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Abstract
    In this paper, we experimentally investigate the statistical distribution of intensity fluctuations for underwater wireless optical channels under different channel conditions, namely fresh and salty underwater channels with and without air bubbles. To do so, we first measure the received optical signal with a large number of samples. Based on the normalized acquired data the channel coherence time and the fluctuations probability density function (PDF) are obtained for different channel scenarios. Our experimental results show that salt attenuates the received signal while air bubbles mainly introduce severe intensity fluctuations. Moreover, we observe that log-normal distribution precisely... 

    Mining DNA sequences based on spatially coded technique using spatial light modulator

    , Article IWCIT 2016 - Iran Workshop on Communication and Information Theory, 3 May 2016 through 4 May 2016 ; 2016 ; 9781509019229 (ISBN) Fazelian, M ; Abdollahramezani, S ; Bahrani, S ; Chizari, A ; Jamali, M. V ; Khorramshahi, P ; Tashakori, A ; Shahsavari, S ; Salehi, J. A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Abstract
    In this paper, we present an optical computing method for string data alignment applicable to genome information analysis. By applying moire technique to spatial encoding patterns of deoxyribonucleic acid (DNA) sequences, association information of the genome and the expressed phenotypes could more effectively be extracted. Such moire fringes reveal occurrence of matching, deletion and insertion between DNA sequences providing useful visualized information for prediction of gene function and classification of species. Furthermore, by applying a cylindrical lens, a new technique is proposed to map two-dimensional (2D) association information to a one-dimensional (1D) column of pixels, where... 

    Opportunistic Fair Resource Allocation for Multi-Cell Wireless Networks

    , M.Sc. Thesis Sharif University of Technology Shahsavari, Shahram (Author) ; Hossein Khalaj, Babak (Supervisor)
    Abstract
    In recent years, introduction of new technologies has highlighted the need to more data rate in mobile networks. Classical methods of resource allocation in mobile networks cannot respond to this huge demand for data rate because of their limitations. Resource allocation, as one of the operators’ tasks, plays a key role in the network efficiency and users’ data rate. Opportunistic resource allocation and scheduling have gained attention in recent years. On the other, using single-channel (frequency reuse-1) networks is also one of the methods to improve data rate in mobile networks. It is expected that the use of opportunistic scheduling in single-channel networks can repond to the huge...