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    Temporal output profile of gain-coupled distributed feedback dye laser

    , Article Laser Physics ; Volume 27, Issue 8 , 2017 ; 1054660X (ISSN) Pasandideh, K ; Souri, S ; Gohari Kamel, N ; Sadighi Bonabi, R ; Sharif University of Technology
    Institute of Physics Publishing  2017
    Abstract
    The lasing mechanism and temporal output profile of distributed feedback dye lasers is investigated, using a model based on induced polarization in the dye solution, where a more accurate behavior of the laser output is predicted. It is found that the temporal output profile of the laser is mostly determined by the concentration of dye solution and the lifetime of the upper laser level of dye molecules. To a large extent, the results of this work agree with experimental studies, even at high-level pump intensities where the self Q-switched model fails to be applied. Especially, the experimentally observed irregular intensity profile of laser output is explained. It is also shown that, when... 

    Efficient carrier utilization induced by conductive polypyrrole additives in organic-inorganic halide perovskite solar cells

    , Article Solar Energy ; Volume 207 , 2020 , Pages 1300-1307 Zarenezhad, H ; Balkan, T ; Solati, N ; Halali, M ; Askari, M ; Kaya, S ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    The morphology of the perovskite layer, the effective extraction of the charge carriers, and their transport are the main factors determining the power conversion efficiency (PCE) of the perovskite solar cells (PSCs). In this work, we demonstrated that the geometric and electronic structures of the PSCs could be modified by using a conductive polymer additive in the lead (Pb) halide layer prepared by a two-step deposition method. Polypyrrole (PPy) as a conductive polymer is used in the perovskite layers which could increase the PCE of CH3NH3PbI3-xClx mixed-halide PSCs. By adding an optimized amount of PPy, PCE has been raised from 10.4 to 13.2%. PPy acts as a conductive channel facilitating... 

    DNAPL flow and complex electrical resistivity evolution in saturated porous media: A coupled numerical simulation

    , Article Journal of Contaminant Hydrology ; Volume 248 , 2022 ; 01697722 (ISSN) Koohbor, B ; Deparis, J ; Leroy, P ; Ataie Ashtiani, B ; Davarzani, H ; Colombano, S ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    Induced Polarization (IP) is a non-intrusive geophysical method to monitor Dense Non-Aqueous Phase Liquid (DNAPL) contamination and remediation processes underground. In this study, an advanced numerical code simulating DNAPL flow and complex electrical resistivity is presented. The model was validated against existing IP results and image measurements that were carried out previously in a series of 2D tank experiment. Multiphase flow modeling in porous media is coupled with electrical current modeling to simulate the process of DNAPL migration and the associated IP response. This brings a broader view of the contamination in space and time compared to surface and borehole measurements,...