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    Hydrodynamics of fingering instability in the presence of a magnetic field

    , Article Fluid Dynamics Research ; Volume 48, Issue 5 , 2016 ; 01695983 (ISSN) Mostaghimi, P ; Ashouri, M ; Ebrahimi, B ; Sharif University of Technology
    Institute of Physics Publishing 
    The hydrodynamics of two immiscible fluids in a rectangular Hele-Shaw cell under the influence of a magnetic field is studied, both theoretically and numerically. A linear stability analysis is conducted to determine the effect of magnetic fields on the formation of viscous fingers. As a result, an analytical solution is found to calculate the growth rate of perturbations. For numerical simulation of the two-phase flow, the interfacial tension is treated as a body force using the continuum surface force model and the interface tracking is performed by the volume of fluid method. The variations of the width and growth rate of fingers in an unstable displacement versus Hartmann number, a... 

    Fast aggregation scheduling in wireless sensor networks

    , Article IEEE Transactions on Wireless Communications ; Volume 14, Issue 6 , 2015 , Pages 3402-3414 ; 15361276 (ISSN) Yousefi, H ; Malekimajd, M ; Ashouri, M ; Movaghar, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Data aggregation is a key, yet time-consuming functionality introduced to conserve energy in wireless sensor networks (WSNs). In this paper, to minimize time latency, we focus on aggregation scheduling problem and propose an efficient distributed algorithm that generates a collision-free schedule with the least number of time slots. In contrast to others, our approach named FAST mainly contributes to both tree construction, where the former studies employ Connected 2-hop Dominating Sets, and aggregation scheduling that was previously addressed through the Competitor Sets computation. We prove that the latency of FAST under the protocol interference model is upper-bounded by 12R+Δ-2, where R... 

    On the performance of inclined rooftop solar chimney integrated with photovoltaic module and phase change material: A numerical study

    , Article Solar Energy ; Volume 211 , 2020 , Pages 1159-1169 Salari, A ; Ashouri, M ; Hakkaki Fard, A ; Sharif University of Technology
    Elsevier Ltd  2020
    In an attempt to prolong the performance of the conventional Solar Chimney (SC) and enhance its efficiency, this contribution presents a kind of novel compound SC with the Photovoltaic (PV) module and Phase Change Material (PCM) called the SC-PV-PCM system. Using PCM not only improves the PV module performance but also extends the productive period of the SC. A three-dimensional quasi-steady computational fluid dynamics (CFD) model of the proposed system is developed. The developed model is used to investigate the effect of using PCMs with different melting points on the performance of the proposed system. It is demonstrated that the RT-50 provides superior performance among the studied... 

    A new approach for multi-source data prediction in wireless sensor networks: Collaborative filtering

    , Article 2012 International Conference on Wireless Communications and Signal Processing, WCSP 2012 ; 2012 ; 9781467358293 (ISBN) Inanloo, M ; Ashouri, M ; Gheibi, S ; Hemmatyar, A. M. A ; Sharif University of Technology
    The prime shortcoming of Wireless Sensor Networks (WSNs) is their energy constraint. The main energy consumer in a sensor node is its radio transmitter. One of the most effective methods to reduce the data transmission rate is data prediction. By data prediction, the amount of transmitted data is reduced; which results in energy saving and the longevity of the network life. Environmental variations almost have similar effects on different sensor sources in a sensor device. So, considering the correlation between different sources reduces the noise impact and increases data prediction accuracy. In this paper, temporal and multi-source correlations are used, to reduce data transmission in... 

    A large plasticity deformation of unsaturated soil for 3d dynamic analysis of lower San-Fernando dam

    , Article Asian Journal of Civil Engineering ; Volume 12, Issue 1 , 2010 , Pages 1-25 ; 15630854 (ISSN) Khoei, A. R ; Anahid, M ; Zarinfar, M ; Ashouri, M ; Pak, A ; Sharif University of Technology
    In this paper, a large plasticity deformation finite element modeling is presented for three-dimensional dynamic analysis of unsaturated soils with special reference to the failure of lower San Fernando dam under the 1971 earthquake. The finite element method is applied to the governing equations for the spatial discretization, followed by a generalized Newmark scheme used for the time domain discretization. Time stepping scheme is used in the fully implicit coupled method and a direct solution procedure is used for the coupled equation system. The framework of generalized plasticity is presented and the numerical results of unsaturated soils are demonstrated based on the Pastor-Zienkiewicz...