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    Light Duty Vehicles' Emission Reduction Potentials in Megacities
    Using New Powertrain Technologies (Case Study: Tehran)

    , M.Sc. Thesis Sharif University of Technology Askariyeh, Mohammad Hashem (Author) ; Erhami, M. (Mohammad) (Supervisor) ; Pourzahedi, H. (Hossein) (Supervisor)
    Abstract
    Tehran is one of the most polluted megacities in the world, and based on different studies, vehicular sources are responsible for most of the criteria pollutant emissions in this city. The number of vehicles on the streets has been increased drastically leading to growing amount of emission and this trend is continuing. In order to reduce the amount of vehicular emission, it is vital to investigate the factors affecting vehicles emission in this city. This could help to find efficient solutions to improve the situation. Hence, a low-cost methodology to estimate the vehicular emissions is developed. In this... 

    Effect of Temperature Gradient on Ultrasonic Flowmeters

    , M.Sc. Thesis Sharif University of Technology Fathi, Shayan (Author) ; Sadrhosseini, H (Supervisor) ; Kazemzadeh Hannani, Siamak (Co-Advisor)
    Abstract
    Ultrasonic flowmeters are one of the common and profitable measurement tools and applied in many industrial fields.Ultrasonic flowmeters work based on transit-time technique. The transit-time utilizes the propagation time of the ultrasonic signal in the fluid. Since ultrasonic signals can also penetrate solid materials, a pair of transducers is installed on the surface of tube. Each transducer works alternatively as both transmitter and receiver of ultrasonic signals.In this study, effect of temperature gradient on flowmeter measurements by applying constant temperature and uniform heat flux on the boundary is investigated numerically for methane gas in laminar flow regime and the results... 

    Pressure Transient Analysis of Variable-rate Well Test Data

    , Ph.D. Dissertation Sharif University of Technology Mansoori Habib Abadi, Mehdi (Author) ; Rashtchian, Davood (Supervisor) ; Van den Hof, Paul (Supervisor) ; Jansen, Jan Dirk (Supervisor)
    Abstract
    This study presents a novel perspective on pressure-transient analysis (PTA) of downhole-pressure and flow-rate data by use of system-identification (SI) techniques as widely used in advanced process engineering. Key features of the algorithm are that it considers the classic PTA process from a system-theoretical perspective; derives the causal structure of the flow dynamics; proposes a method to deal with continuously varying pressure and flow-rate signals contaminated with correlated noise, which estimates physical reservoir parameters through a systematic matching procedure in the frequency domain; and can cope with arbitrary (i.e., not necessarily piecewise constant) flow-rate signals.... 

    Localized discriminative Gaussian process latent variable model for text-dependent speaker verification

    , Article 24th European Symposium on Artificial Neural Networks, Computational Intelligence and Machine Learning, ESANN 2016, 27 April 2016 through 29 April 2016 ; 2016 , Pages 183-188 ; 9782875870278 (ISBN) Maghsoodi, N ; Sameti, H ; Zeinali, H ; Sharif University of Technology
    i6doc.com publication  2016
    Abstract
    The duration of utterances is one of the effective factors on the performance of speaker verification systems. Text dependent speaker verification suffers from both short duration and unmatched content between enrollment and test segments. In this paper, we use Discriminative Gaussian Process Latent Variable Model (DGPLVM) to deal with the uncertainty caused by short duration. This is the first attempt to utilize Gaussian Process for speaker verification. Also, to manage the unmatched content between enrollment and test segments we proposed the localized-DGPLVM that trains DGPLVM for each phrase in dataset. Experiments show the relative improvement of 27.4% in EER on RSR2015  

    Investigation of cervical spine curvature in females with postural neck pain

    , Article Journal of Zanjan University of Medical Sciences and Health Services ; Volume 25, Issue 110 , 2017 , Pages 110-119 ; 16069366 (ISSN) Salahzadeh, Z ; Maroufi, N ; Ahmadi, A ; Behtash, H ; Hazhir Sahneh, S ; Parnianpour, M ; Sharif University of Technology
    Zanjan University of Medical Sciences and Health Services  2017
    Abstract
    Background and Objective: Changes in the cervical spine curvature leads to increased shear force and compression stress on cervical spine and axial loading in different cervical segments. The objective of this study was to compare the general and segmental curvature in the upper and lower cervical spine of women with postural neck pain and Forward Head Posture (FHP), women without neck pain but with FHP and healthy women. Material and Methods: 45 women were divided into three groups: 15 women with postural neck pain and FHP, 15 women without neck pain but with FHP and 15 healthy women. Photography was used to assess neck posture while cervical spine curvature was measured using fluoroscopy... 

    Experimental investigation of dual-purpose solar collector using with rectangular channels

    , Article Journal of Thermal Engineering ; Volume 3, Issue 1 , 2017 , Pages 1052-1059 ; 21487847 (ISSN) Kavoosi Balotaki, H ; Saidi, M. H ; Sharif University of Technology
    Yildiz Technical University  2017
    Abstract
    Solar heat energy, one of the typical renewable energy absorbs radiation energy from the sun and converts it into heat energy. Since it is sustainable and eco-friendly, it can be a good alternative to solve the problem of the depletion of fossil fuels. But it has low density. So, solar collector is very important to use more efficiently. There are some possible approaches to scaling-up the effectiveness of a collector by re-thinking of using the collector as a heat exchanger. In the design of dual-purpose collector with rectangular fin (DPCRF), can be used for heating air and water simultaneously using incident solar radiation resulting in optimum usage of energy and space  

    Thermoeconomic analysis and multi-objective optimization of an integrated solar system for hydrogen production using particle swarm optimization algorithm

    , Article Journal of Thermal Engineering ; Volume 7, Issue 4 , 2021 , Pages 746-760 ; 21487847 (ISSN) Keykhah, S ; Assareh, E ; Moltames, R ; Taghipour, A ; Barati, H ; Sharif University of Technology
    Yildiz Technical University  2021
    Abstract
    This study aims to investigate the hydrogen production process using an integrated system based on solar energy. This system includes an evacuated tube collector to absorb solar energy as input energy of the system. A parametric analysis was conducted to determine the most important design parameters and evaluate these parameters' impact on the system's objective functions. For identifying the optimum system conditions, multi-objective optimization was performed using particle swarm optimization (PSO) algorithm. The results obtained from the parametric analysis show that an increment in the collector mass flow rate and the turbine inlet temperature, as well as a decrement in the collector... 

    Towards a calculus for nondeterministic schemas in Z

    , Article International Journal of Software Engineering and Knowledge Engineering ; Volume 22, Issue 6 , September , 2012 , Pages 839-865 ; 02181940 (ISSN) Haghighi, H ; Mirian Hosseinabadi, S. H ; Sharif University of Technology
    World Scientific  2012
    Abstract
    In our previous work, we presented a Z-based formalism, called NZ, by which one can explicitly specify bounded, unbounded, erratic, angelic, demonic, loose, strict, singular, and plural nondeterminism. The NZ notation is mainly based on a new notion of operation schemas, called multi-schema. Since the operations of the Z schema calculus do not work on multi-schemas anymore, in this paper we augment NZ with a new set of schema calculus operations that can be applied on multi-schemas as well as ordinary operation schemas. To demonstrate the usability of the resulting formalism, we show how this formalism can assist to model game-like situations and concurrent systems as two well-known classes... 

    Adaptive sparse representation for MRI noise removal

    , Article Biomedical Engineering - Applications, Basis and Communications ; Volume 24, Issue 5 , October , 2012 , Pages 383-394 ; 10162372 (ISSN) Khalilzadeh, M. M ; Fatemizadeh, E ; Behnam, H ; Sharif University of Technology
    World Scientific  2012
    Abstract
    Sparse representation is a powerful tool for image processing, including noise removal. It is an effective method for Gaussian noise removal by taking advantage of a fixed and learned dictionary. In this study, the variable distribution of Rician noise is reduced in magnetic resonance (MR) images by sparse representation based on reconstruction error sets. Standard deviation of Gaussian noise is used to find these errors locally. The proposed method represents two formulas for local error calculation using standard deviation of noise. The acquired results from the real and simulated images are comparable, and in some cases, better than the best Rician noise removal method due to the... 

    Kinetics of swelling of cylindrical temperature-responsive hydrogel: a semi-analytical study

    , Article International Journal of Applied Mechanics ; Volume 12, Issue 8 , 2020 Namdar, A. H ; Mazaheri, H ; Sharif University of Technology
    World Scientific  2020
    Abstract
    Cylindrical hydrogels have a wide variety of applications, especially in microfluidics as micro-valves, micro-mixers, and micro-lenses. Main advantages of them can be mentioned as their simple geometry and autonomous functionality due to their responses to the environmental stimuli. In current research, kinetics of swelling, shrinking and force generation of cylindrical temperature-responsive hydrogels have been investigated analytically. According to this, models of fluid permeation and large deformation of the hydrogels were considered and an analytical solution was performed. In order to study the behavior of the cylindrical hydrogels, the temperature is changed between higher and lower... 

    Contributive representation-based reconstruction for online 3d action recognition

    , Article International Journal of Pattern Recognition and Artificial Intelligence ; 2020 Tabejamaat, M ; Mohammadzade, H ; Sharif University of Technology
    World Scientific  2020
    Abstract
    Recent years have seen an increasing trend in developing 3D action recognition methods. However, despite the advances, existing models still suffer from some major drawbacks including the lack of any provision for recognizing action sequences with some missing frames. This significantly hampers the applicability of these methods for online scenarios, where only an initial part of sequences are already provided. In this paper, we introduce a novel sequence-to-sequence representation-based algorithm in which a query sample is characterized using a collaborative frame representation of all the training sequences. This way, an optimal classifier is tailored for the existing frames of each query... 

    Contributive representation-based reconstruction for online 3d action recognition

    , Article International Journal of Pattern Recognition and Artificial Intelligence ; Volume 35, Issue 2 , 2021 ; 02180014 (ISSN) Tabejamaat, M ; Mohammadzade, H ; Sharif University of Technology
    World Scientific  2021
    Abstract
    Recent years have seen an increasing trend in developing 3D action recognition methods. However, despite the advances, existing models still suffer from some major drawbacks including the lack of any provision for recognizing action sequences with some missing frames. This significantly hampers the applicability of these methods for online scenarios, where only an initial part of sequences are already provided. In this paper, we introduce a novel sequence-To-sequence representation-based algorithm in which a query sample is characterized using a collaborative frame representation of all the training sequences. This way, an optimal classifier is tailored for the existing frames of each query... 

    The novel soliton solutions for the conformable perturbed nonlinear Schrödinger equation

    , Article Modern Physics Letters B ; Volume 36, Issue 8 , 2022 ; 02179849 (ISSN) Yépez-Martínez, H ; Pashrashid, A ; Gómez Aguilar, J. F ; Akinyemi, L ; Rezazadeh, H ; Sharif University of Technology
    World Scientific  2022
    Abstract
    The sub-equation method is implemented to construct exact solutions for the conformable perturbed nonlinear Schrödinger equation. In this paper, we consider three different types of nonlinear perturbations: The quadratic-cubic law, the quadratic-quartic-quintic law, and the cubic-quintic-septic law. The properties of the conformable derivative are discussed and applied with the help of a suitable wave transform that converts the governing model to a nonlinear ordinary differential equation. Furthermore, the order of the expected polynomial-type solution is obtained using the homogeneous balancing approach. Dark and singular soliton solutions are derived. © 2022 World Scientific Publishing... 

    Nonlinear free vibration analysis of in-plane Bi-directional functionally graded plate with porosities resting on elastic foundations

    , Article International Journal of Applied Mechanics ; Volume 14, Issue 1 , 2022 ; 17588251 (ISSN) Hashemi, S ; Shahri, P. K ; Beigzadeh, S ; Zamani, F ; Eratbeni, M. G ; Mahdavi, M ; Heidari, A ; Khaledi, H ; Abadi, M. R. R ; Sharif University of Technology
    World Scientific  2022
    Abstract
    This paper deals with the nonlinear free vibration analysis of in-plane bi-directional functionally graded (IBFG) rectangular plate with porosities which are resting on Winkler-Pasternak elastic foundations. The material properties of the IBFG plate are assumed to be graded along the length and width of the plate according to the power-law distribution, as well as, even and uneven types are taken into account for porosity distributions. Equations of motion are developed by means of Hamilton's principle and von Karman nonlinearity strain-displacement relations based on classical plate theory (CPT). Afterward, the time-dependent nonlinear equations are derived by applying the Galerkin... 

    On the complement of the intersection graph of submodules of a module

    , Article Journal of Algebra and its Applications ; Volume 14, Issue 8 , October , 2015 ; 02194988 (ISSN) Akbari, S ; Tavallaee, H. A ; Khalashi Ghezelahmad, S ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2015
    Abstract
    Let R be a ring with identity and M be a unitary left R-module. The complement of the intersection graph of submodules of M, denoted by Γ(M), is defined to be a graph whose vertices are in one-to-one correspondence with all nontrivial submodules of M and two distinct vertices are adjacent if and only if the corresponding submodules of M have zero intersection. In this paper, we consider the complement of the intersection graph of submodules of a module. We prove that, if Γ(M) is connected and Δ(Γ(M)) < ∞, then M is semisimple, where Δ(Γ(M)) is the maximum degree of Γ(M). We show that, if Γ(M) is a forest, then each component of Γ(M) is a star graph. Moreover, it is proved that, if Γ(M) is a... 

    Fsi simulation of a healthy coronary bifurcation for studying the mechanical stimuli of endothelial cells under different physiological conditions

    , Article Journal of Mechanics in Medicine and Biology ; Volume 15, Issue 5 , October , 2015 ; 02195194 (ISSN) Pakravan, H. A ; Saidi, M. S ; Firoozabadi, B ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2015
    Abstract
    Atherosclerosis is a world-spread and well-known disease. This disease strongly relates to the endothelial cells (ECs) function. Normally, the endothelial cells align in the flow direction in the atheroprotected sites; however, in the case of atheroprone sites these cells orient randomly. The mechanical stimuli such as wall shear stress and strains could determine the morphology and function of the endothelial cells. In the present study, we numerically simulated the left main coronary artery (LCA) and its branches to left anterior descending (LAD) and left circumflex coronary (LCX) artery using fluid-structure interaction (FSI) modeling. The results were presented as longitudinal and... 

    Study of Biomolecules Imaging Using Molecular Dynamics Simulations

    , Article Nano ; Volume 10, Issue 7 , October , 2015 ; 17932920 (ISSN) Kheirodin, M ; Nejat Pishkenari, H ; Moosavi, A ; Meghdari, A ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2015
    Abstract
    The process of imaging a biomolecule by atomic force microscope (AFM) is modeled using molecular dynamics (MD) simulations. Since the large normal force exerted by the tip on the biosample in contact and tapping modes may damage the sample structure and produce irreversible deformation, the noncontact mode of AFM (NC-AFM) is employed as the operating mode. The biosample is scanned using a carbon nanotube (CNT) as the AFM probe. CNTs because of their small diameter, high aspect ratio and high mechanical resistance attract many attentions for imaging purposes. The tip-sample interaction is simulated by the MD method. The protein, which has been considered as the biomolecule, is ubiquitin and a... 

    Subject-specific and function-specific applicability of a hand-forearm musculoskeletal model

    , Article Biomedical Engineering - Applications, Basis and Communications ; Volume 27, Issue 6 , 2015 ; 10162372 (ISSN) Hosseininejad, S ; Farahmand, F ; Fateh, H. R ; Forogh, B ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2015
    Abstract
    There is ambiguity on the quantitative validity of the predictions revealed by musculoskeletal models for muscle forces. This study investigated the consistency between the predictions of a musculoskeletal model of the upper limb and the experimental data for a number of different subjects and functional tasks. Six normal subjects performed isokinetic eccentric or isotonic concentric contraction tests of the wrist muscles in well controlled conditions, using a robotic apparatus, and the net joint torque and angular velocities, as well as the surface electromyograms (EMG) signals of the muscles, were recorded. The experiments were then simulated using a parametric musculoskeletal model of... 

    On the chaotic vibrations of electrostatically actuated arch micro/nano resonators: a parametric study

    , Article International Journal of Bifurcation and Chaos ; Volume 25, Issue 8 , July , 2015 ; 02181274 (ISSN) Tajaddodianfar, F ; Hairi Yazdi, M. R ; Nejat Pishkenari, H ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2015
    Abstract
    Motivated by specific applications, electrostatically actuated bistable arch shaped micro-nano resonators have attracted growing attention in the research community in recent years. Nevertheless, some issues relating to their nonlinear dynamics, including the possibility of chaos, are still not well known. In this paper, we investigate the chaotic vibrations of a bistable resonator comprised of a double clamped initially curved microbeam under combined harmonic AC and static DC distributed electrostatic actuation. A reduced order equation obtained by the application of the Galerkin method to the nonlinear partial differential equation of motion, given in the framework of Euler-Bernoulli beam... 

    An investigation on thermomechanical flexural response of shape-memory-polymer beams

    , Article International Journal of Applied Mechanics ; Volume 8, Issue 5 , 2016 ; 17588251 (ISSN) Molaaghaie Roozbahani, M ; Heydarzadeh, N ; Baghani, M ; Eskandari, A. H ; Baniassadi, M ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2016
    Abstract
    In this paper, the predictions of different beam theories for the behavior of a shape memory polymer (SMP) beam in different steps of a thermomechanical cycle are compared. Employing the equilibrium equations, the governing equations of the deflection of a SMP beam in the different steps of a thermomechanical cycle, for higher order beam theories (Timoshenko Beam Theory and von-Kármán Beam Theory), are developed. For the Timoshenko Beam Theory, a closed form analytical solution for various steps of the thermomechanical cycle is presented. The nonlinear governing equations in von-Kármán Beam theory are numerically solved. Results reveal that in the various beam length to beam thickness...