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    Variational formulation on Joule heating in combined electroosmotic and pressure driven microflows

    , Article International Journal of Heat and Mass Transfer ; Volume 61, Issue 1 , June , 2013 , Pages 254-265 ; 00179310 (ISSN) Sadeghi, A ; Saidi, M. H ; Waezi, Z ; Chakraborty, S ; Sharif University of Technology
    2013
    Abstract
    The present study attempts to analyze the extended Graetz problem in combined electroosmotic and pressure driven flows in rectangular microchannels, by employing a variational formulation. Both the Joule heating and axial conduction effects are taken into consideration. Since assuming a uniform inlet temperature profile is not consistent with the existence of these effects, a step change in wall temperature is considered to represent physically conceivable thermal entrance conditions. The method of analysis considered here is primarily analytical, in which series solutions are presented for the electrical potential, velocity, and temperature. For general treatment of the eigenvalue problem... 

    On nonlinear perturbation analysis of a structure carrying a circular cylindrical liquid tank under horizontal excitation

    , Article JVC/Journal of Vibration and Control ; Volume 25, Issue 5 , 2019 , Pages 1058-1079 ; 10775463 (ISSN) Khajeh Ahmad Attari, N ; Rahimzadeh Rofooei, F ; Waezi, Z ; Sharif University of Technology
    SAGE Publications Inc  2019
    Abstract
    The lateral response of a single degree of freedom structural system containing a rigid circular cylindrical liquid tank under harmonic and earthquake excitations at a 1:2 autoparametric resonance case is considered. The governing nonlinear differential equations of motion for the combined system are solved by means of a multiple scales method considering the first three liquid sloshing modes (1,1), (0,1), and (2,1), under horizontal excitation. The fixed points of the gyroscopic type of governing differential equations are determined and their stability is investigated employing the perturbation method. The obtained results reveal an increase in the stability region for a single-mode... 

    On the evolutionary characteristics of the acceleration records generated from linear time-variant systems

    , Article Scientia Iranica ; Volume 24, Issue 6 , 2017 , Pages 2817-2831 ; 10263098 (ISSN) Waezi, Z ; Rofooei, F. R ; Sharif University of Technology
    2017
    Abstract
    This paper discusses the time-varying characteristics of the output signals resulted from Linear Time Variant (LTV) systems using level-crossing properties. These systems, used for generating synthetic records based on a target record, contain two identification processes: 1) amplitude modulating function; and 2) time-varying Impulse Response Function (IRF) parameters. To track the IRF parameters efficiently, the zerocrossing and positive minima/negative maxima cumulative curves are usually utilized as the measures of the instantaneous spectral power. Using spectral moments, analytic relations for zero-crossing and positive minima/negative maxima cumulative count are developed with respect... 

    Stochastic non-stationary model for ground motion simulation based on higher-order crossing of linear time variant systems

    , Article Journal of Earthquake Engineering ; Volume 21, Issue 1 , 2017 , Pages 123-150 ; 13632469 (ISSN) Waezi, Z ; Rofooei, F. R ; Sharif University of Technology
    2017
    Abstract
    This article introduces a new time-varying model to generate synthetic non-stationary acceleration records using the modified Kanaii-Tajimi model with time-variant parameters. The proposed method can capture two different dominant frequencies per time which makes it suitable for synthesizing the near-field no-pulse earthquake records. A number of closed-form relationships are developed to describe the frequency dependent time-domain level crossings of the simulated records under white noise excitation. The model parameters are optimized using the crossing and Arias intensity properties of the synthetic and target records. The efficiency of the proposed model is demonstrated using a data base... 

    Simulation of the Near-Field Earthquake Records without Velocity Pulse Using Stochastic Approach

    , Ph.D. Dissertation Sharif University of Technology Waezi, Zakariya (Author) ; Rahimzadeh Rofouei, Fayyaz (Supervisor)
    Abstract
    The necessity of providing synthetic acceleration records suitable for seismic assessment of the structures in the regions whose seismological history has not enough instrumental recordings has become one of the main concerns of the earthquake engineers. Despite being accurate in estimating earthquake ground motion, physics-based methods involve complicated procedures and need the detailed information about source, path and the site conditions of the scenario event which is not available for lots of engineering problems. The main goal of this dissertation is to introduce a novel stochastic method for the simulation of the non-stationary earthquake acceleration records compatible enough with... 

    Simulation the Near-Fault Velocity Pulses from Form and Intensity Point of View

    , M.Sc. Thesis Sharif University of Technology Waezi, Zakariya (Author) ; Rahimzadeh Rofooei, Fayaz (Supervisor)
    Abstract
    Near-Field earthquakes have gained so much attention through their catastrophic consequences on structures in the vicinity of seismic sources during recent events. Based on recorded data, it is understood that these kinds of phenomena are often accompanied with a large energy pulse at the first times of record whose impulsive characteristic is primarily caused by “forward directivity”. Incapability of response spectra for depicting great demand for energy dissipation disqualifies this method for utilization. Thus it seems inevitable to analyze the models prone to this kind of hazard using time-history based analysis. Being simple enough in time domain, raises hopes for finding a mathematical... 

    A multi-peak evolutionary model for stochastic simulation of ground motions based on time-domain features

    , Article Journal of Earthquake Engineering ; 2018 ; 13632469 (ISSN) Waezi, Z ; Rofooei, F. R ; Hashemi, M. J ; Sharif University of Technology
    Taylor and Francis Ltd  2018
    Abstract
    This paper introduces an efficient stochastic method to produce fully nonstationary records having multiple peaks in power spectrum. The zero-crossing characteristics of the acceleration, velocity, and displacement time histories of the output signal are used to estimate the model parameters. This procedure is utilized to resimulate 252 non-pulse-like, horizontal near-field records with rupture distance of less than 10 km and strike–slip mechanism. The model parameters are regressed against moment magnitude, rupture distance, hypo-central depth, and shear wave velocity, enabling the scenario-based simulation of the records. The response spectra of the simulated records are compared with... 

    Controlling the seismic response of structures under near-field earthquakes with fluid/structure interaction of cylindrical liquid tanks

    , Article European Journal of Environmental and Civil Engineering ; Volume 26, Issue 2 , 2022 , Pages 570-593 ; 19648189 (ISSN) Waezi, Z ; Attari, N. K. A ; Rofooei, F. R ; Sharif University of Technology
    Taylor and Francis Ltd  2022
    Abstract
    In this paper, the effectiveness of using nonlinear fluid/structure interaction for controlling the seismic response of the structures under near-field earthquake is investigated. For this purpose an SDOF Structure is considered which is equipped with the circular cylindrical liquid tank. Considering its fundamental mode of vibration, the structure is an idealised model of multi-degree of freedom system. Under 72 horizontal near-field earthquake excitations, the dynamic response of this system is examined studying three liquid sloshing modes. The dynamic response is investigated in the neighbourhood of 1:1 resonance between first unsymmetrical sloshing mode and SDOF structural mode. For this... 

    Down from the pedestal: Revisiting the exploit of literature in EFL language classes

    , Article International Journal of Applied Linguistics and English Literature ; Volume 4, Issue 2 , 2015 , Pages 158-168 ; 22003592 (ISSN) Rezanejad, A ; Lari, Z ; Mosalli, Z ; Sharif University of Technology
    Australian International Academic Centre PTY LTD  2015
    Abstract
    According to Arthur (2006, p. 200), “Through the use of literature, a language learning experience might become at the same time a source of immediate pleasure and satisfaction for the student. This possibility makes literature an appealing teaching device for ESL teachers”. However, numerous factors may contribute to the teachers’ lack of interest in using literary texts as a teaching tool. This study was an attempt to investigate Iranian EFL teachers’ attitude toward using literature in language classes and their perception toward the probable reasons of some teachers’ lack of interest in doing so. Altogether forty-four language teachers (19 females and 25 males, with a mean age of 26)... 

    Inclusion of carbon nanotubes in a hydroxyapatite sol-gel matrix

    , Article Ceramics International ; Volume 35, Issue 7 , 2009 , Pages 2987-2991 ; 02728842 (ISSN) Najafi, H ; Nemati, Z. A ; Sadeghian, Z ; Sharif University of Technology
    2009
    Abstract
    In this study, the inclusion of multi-walled carbon nanotubes as the second phase in the hydroxyapatite matrix, in order to improve the mechanical strength, has been performed via the sol-gel process. The stability of carbon nanotube sol with the changes of pH and dispersant values (sodium dodecyl sulfate) was evaluated by zeta potential analysis. The results indicated that synthesis of hydroxyapatite particles in the presence of the carbon nanotubes had the best result in homogenization of the carbon nanotube dispersion and faster crystallization of hydroxyapatite. The crystallization of hydroxyapatite phase was investigated with differential scanning calorimetry (DSC) and X-ray diffraction... 

    Fourier optics approach in evaluation of the diffraction and defocus aberration in three-dimensional integral imaging

    , Article Computational Modelling of Objects Represented in Images: Fundamentals, Methods and Applications III - Proceedings of the International Symposium, CompIMAGE 2012 ; 2012 , Pages 81-84 ; 9780415621342 (ISBN) Esfahani, Z. E. A ; Kavehvash, Z ; Mehrany, K ; Sharif University of Technology
    CRC  2012
    Abstract
    The unwanted effects of diffraction and defocus aberration in three-dimensional integral imaging are taken into account by using the Fourier optics approach. The concepts of point spread function and optical transfer function widely in use for conventional two-dimensional imaging are generalized and applied to three-dimensional integral imaging systems. The effects of diffraction and defocus aberration are then studied and the performance of the conventional single lens imaging system is compared against that of the integral imaging  

    Multi-target sputter deposition of Ni50Ti 50 - XHfx shape memory thin films for high temperature microactuator application

    , Article Sensors and Actuators, A: Physical ; Volume 121, Issue 2 , 2005 , Pages 543-548 ; 09244247 (ISSN) Sanjabi, S ; Cao, Y. Z ; Barber, Z. H ; Sharif University of Technology
    2005
    Abstract
    High temperature shape memory NiTiHf thin films with varying hafnium contents up to 28.7 at.% were fabricated by DC magnetron sputtering using simultaneous sputter deposition from separate elemental targets. The required film composition was achieved by adjusting the power ratio to the targets. The as-deposited films were amorphous; a post deposition annealing was performed at 550 °C to crystallize the films. Two-micron thick films were characterized by energy dispersive spectroscopy in a scanning electron microscope, temperature controlled X-ray diffraction, differential scanning calorimetry, and atomic force microscopy. The results showed that above 10 at.% Hf additions the transformation... 

    Strong Revenue (Non-)Monotonicity of Single-parameter Auctions

    , Article EC 2023 - Proceedings of the 24th ACM Conference on Economics and Computation ; 2023 , Pages 452-471 ; 979-840070104-7 (ISBN) Chen, Z ; Huang, Z ; Majdi, D ; Yan, Z ; Sharif University of Technology
    Association for Computing Machinery, Inc  2023
    Abstract
    Consider Myerson's optimal auction with respect to an inaccurate prior, e.g., estimated from data, which is an underestimation of the true value distribution. Can the auctioneer expect getting at least the optimal revenue w.r.t. the inaccurate prior since the true value distribution is larger? This so-called strong revenue monotonicity is known to be true for single-parameter auctions when the feasible allocations form a matroid. We find that strong revenue monotonicity fails to generalize beyond the matroid setting, and further show that auctions in the matroid setting are the only downward-closed auctions that satisfy strong revenue monotonicity. On the flip side, we recover an approximate... 

    Subsidy cut and its effect on tehran electricity company: A system dynamics approach

    , Article Proceedings of the 2012 - Summer Computer Simulation Conference, SCSC 2012, Part of SummerSim 2012 Multiconference ; Volume 44, Issue 10 , 2012 , Pages 113-120 ; 9781618399847 (ISBN) Mehmanchi, E ; Fard, S. Z
    2012
    Abstract
    In recent years, subsidy payment has been made a main challenge for governments due to growth of population and energy price in global markets. Targeted subsidy plan has been implemented in Iran since last year, and this article discusses its effects on costs and revenues of Tehran Electricity Company as one of the major subdivisions of Iran's electricity industry. In the new system, structural changes have been made in electricity tariffs, so it is not possible to predict the future trends in electricity consumption only based on the past consumptions. In order to model the decision making structure in the recent conditions, a system dynamics method is applied. In addition to modeling the... 

    Interactions of coinage metal clusters with histidine and their effects on histidine acidity; Theoretical investigation

    , Article Organic and Biomolecular Chemistry ; Volume 10, Issue 47 , Oct , 2012 , Pages 9373-9382 ; 14770520 (ISSN) Javan, M. J ; Jamshidi, Z ; Tehrani, Z. A ; Fattahi, A ; Sharif University of Technology
    2012
    Abstract
    Understanding the nature of interaction between metal nanoparticles and biomolecules such as amino acids is important in the development and design of biosensors. In this paper, binding of M3 clusters (M = Au, Ag and Cu) with neutral and anionic forms of histidine amino acid was studied using density functional theory (DFT-B3LYP). It was found that the interaction of histidine with M3 clusters is governed by two major bonding factors: (a) the anchoring N-M and O-M bonds and (b) the nonconventional N-H⋯M and O-H⋯M hydrogen bonds. The nature of these chemical bonds has been investigated based on quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. In the next... 

    Can anion interaction accelerate transformation of cytosine tautomers? Detailed view form QTAIM analysis

    , Article Structural Chemistry ; Volume 23, Issue 6 , 2012 , Pages 1843-1855 ; 10400400 (ISSN) Jebeli Javan, M ; Tehrani, Z. A ; Fattahi, A ; Jamshidi, Z ; Sharif University of Technology
    2012
    Abstract
    The relative stabilities and noncovalent interactions of the six low-lying energy tautomers of cytosine nucleobase with some biological anions (such as F-, Cl-, and CN-) have been investigated in gas phase by density functional theory (DFT) method in conjunction with 6-311++G (d,p) atomic basis set. Furthermore, to systematically investigate all possible tautomerisms from cytosine induced by proton transfer, we describe a study of structural tautomer interconversion in the gas phase and in a continuum solvent using DFT calculation. We carried out geometrical optimizations with the integral equation formalism of polarizable continuum (IEF-PCM) model to account for the solvent effect, and the... 

    Interactions of glutathione tripeptide with gold cluster: Influence of intramolecular hydrogen bond on complexation behavior

    , Article Journal of Physical Chemistry A ; Volume 116, Issue 17 , 2012 , Pages 4338-4347 ; 10895639 (ISSN) Tehrani, Z. A ; Jamshidi, Z ; Javan, M. J ; Fattahi, A ; Sharif University of Technology
    2012
    Abstract
    Understanding the nature of the interaction between metal nanoparticles and biomolecules has been important in the development and design of sensors. In this paper, structural, electronic, and bonding properties of the neutral and anionic forms of glutathione tripeptide (GSH) complexes with a Au 3 cluster were studied using the DFT-B3LYP with 6-31+G**-LANL2DZ mixed basis set. Binding of glutathione with the gold cluster is governed by two different kinds of interactions: Auâ€"X (X = N, O, and S) anchoring bond and Au··•·•H-X nonconventional hydrogen bonding. The influence of the intramolecular hydrogen bonding of glutathione on the interaction of this peptide with the gold cluster has been... 

    Implementing distance line protection schemes among IEC61850-enabled substations

    , Article Proceedings of the IEEE Power Engineering Society Transmission and Distribution Conference ; April , 2014 , Page(s): 1 - 5 ; ISSN: 21608555 ; ISBN: 9781479936557 Falahati, B ; Darabi, Z ; Vakilian, M
    2014
    Abstract
    As digital technology has developed, relays have evolved from simple electro-mechanical devices into robust microprocessor-embedded intelligent electronic devices (IEDs). Distance protection, one of the most important and sophisticated forms of substation protection, quickly and selectively detects and clears phase faults in sub-transmission and transmission lines. The installation of a substation automation system (SAS) involves implementing control, monitoring, and protection logic by programming the IEDs and providing an appropriate communication network. IEC61850 has gradually satisfied the need for a standard communication protocol so that IEDs from different manufacturers can... 

    Efficient diastereo- and enantioselective synthesis of α,β-disubstituted γ-phosphono sulfonates

    , Article Tetrahedron Asymmetry ; Volume 20, Issue 21 , 2009 , Pages 2429-2431 ; 09574166 (ISSN) Enders, D ; Mirjafary, Z ; Saeidian, H
    2009
    Abstract
    The first asymmetric synthesis of α,β-disubstituted γ-phosphono sulfonates is reported. The key step is the Michael addition of a lithiated enantiopure sulfonate bearing an inexpensive chiral sugar auxiliary to α,β-unsaturated phosphonates in good diastereoselectivities. After chromatographic purification, the cleavage of the chiral sugar auxiliary proceeds without any epimerization or racemization to form the corresponding isopropyl sulfonate in very good overall yield (75%) and excellent diastereomeric and enantiomeric excess (de, ee ≥ 95%). © 2009 Elsevier Ltd. All rights reserved  

    High-performance UV‐Vis-NIR photodetectors based on plasmonic effect in Au nanoparticles/ZnO nanofibers

    , Article Applied Surface Science ; Volume 483 , 2019 , Pages 1110-1117 ; 01694332 (ISSN) Hosseini, Z. S ; Arab Bafrani, H ; Naseri, A ; Moshfegh, A. Z ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    In this study, UV‐Vis-NIR photodetectors based on decorated ZnO nanofibers (NFs) with optimized coverage of Au nanoparticles (NPs) fabricated via combined simple electrospinning and sputtering techniques are introduced. The effect of different coverages of Au NPs resulted from different Au nominal layer thicknesses on the morphology and optical properties of the ZnO fibers are investigated through various characterization methods. It is discovered that 4 nm Au nominal thickness provides the highest UV on/off ratio (~460), responsivity (~332 A/W), detectivity (~2.93×10 11 Jones) as well as faster rise and decay times as compared to pure ZnO nanofibers. A broad spectral response from UV to NIR...