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    Evaluating of Geometric Factors Effects on Seakeeping Performance of HARTH Vessels

    , M.Sc. Thesis Sharif University of Technology Mohammadi, Mostafa (Author) ; Seif, Mohammad Saeed (Supervisor)
    Performing research and development in the field of modern vessel types which serve several functions is considerably necessary because of their importance and rapid development. HARTH vessel is considered one of the important ships which has been recently attracted much attention from the world. In this respect, a full investigation of its performance could make a big contribution to its optimum design and appropriate exploitation.“HARTH” ship is the abbreviation for “High Aspect Ratio Twin Hull” is included in the catamaran vessel category with a high aspect ratio with respect to their underwater cross-section’s ratio of length to width.A host of crucial issues should be considered for... 

    Determination of Protein Absorption Profile at the Surface of Biocompatible Superparamagnetic Iron Oxide Nanoparticles using Gel Electrophoresis

    , M.Sc. Thesis Sharif University of Technology Ghasemi, Forough (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor) ; Mahmoudi, Morteza (Supervisor)
    Superparamagnetic Iron Oxide NPs (SPIONs) because of their multi-task capabilities (e.g. magnetic labeling, cell isolation, hyperthermiaand controlled drug release) have been recognized as one of the most promising NPs for theranosis applications.When NPs come in contact with a biological medium, the surfaces of them are covered by biomolecules (e.g., proteins, natural organic materials, and enzymes). Therefore, what a biological entity, such as cells, tissues, and organs, sees when interacting with NPs is different original pristine surface of the NPs and actually is hard protein corona. Shape of NPs has a great impact on proteins adsorb onto its surface and consequently on the way that... 

    Non-Equilibrium Interfacial Behavior of Dynamic Interfaces in Presence of Surfactants and Nanoparticles; Experimental and Computational Fluid Dynamic Investigations

    , Ph.D. Dissertation Sharif University of Technology Fayzi, Pouyan (Author) ; Bastani, Dariush (Supervisor) ; Lotfi, Marzieh (Supervisor)
    The present study has been performed for better understanding about the dynamic behavior of fluid interfaces in presence of surfactants, nanoparticles and their interactions in gas-liquid dispersion systems. One of the main purposes of this work is to investigate the influence of surface modified nanoparticles on the dynamic behavior of gas-liquid interfaces. For this purpose, the rising bubble experiment was used as one of the most conventional procedures. Local velocities of bubbles rising in nanoparticle solutions were determined experimentally. Influences of silica nanoparticles which were modified via three approaches were investigated in these experiments. Heat treatment was applied to... 

    Investigation of Effect of the Initial Bubble Shape on Rising Bubble Behaviour

    , M.Sc. Thesis Sharif University of Technology Ghamangiz Khararodi, Mohammad (Author) ; Bastani, Daruoosh (Supervisor)
    In this experimental work terminal velocity, velocity profile and aspect ratio of bubble with 1.49 mm diameter which ascend in pure water and infected by surfactant nonionic C10DMPO and surfactant ionic SDS in regime that surface tension is dominant, have been considered. Observations showed that with respect to entering nozzle, bubbles with this diameter have two initial stable shape; spherical and extended form on surface for horizontal needle and vertical nozzle. Results are (1) Bubbles with initial spherical shape had lower terminal velocity and higher aspect ratio with respect to bubbles with initial extended form, (2) Spherical bubble had aspect ratio about 1 at whole bubble column... 

    Application of Experimental Design for Synthesis and Controlling Aspect Ratio of Metallic Nanorods

    , M.Sc. Thesis Sharif University of Technology Robatjazi, Hossein (Author) ; Jalali-Heravi, Mehdi (Supervisor) ; ormozi Nezhad, Mohammad Reza (Supervisor)
    Aspect ratio dependant optical properties of silver and gold nanorods is responsible for great attention toward controlling the aspect ratio of this class of the nanostructure for their application in variety of area, such as medical diagnosis, drug delivery, biosensing and treatment. In this research, gold and silver nanorods have been synthesized using chemical reducation and growth based on seed mediated method, which is the newest and one of the best methods with less difficulty for producing silver and gold nanorods. Absorption of the visible light by gold and silver nanorods results in appearing the longitudinal and transverse Plasmon bands in their absorption spectra which is related... 

    Investigating the Effects of Specimen Size and Dimensions Ratio on Compressive Strength of Concrete

    , M.Sc. Thesis Sharif University of Technology Zabihi, Alireza (Author) ; Kazemi, Mohammad Tagi (Supervisor)
    Concrete is one of the most widely used building materials. Compressive strength of concrete is the most important property in designing reinforced concrete structures. Compressive strength test should be carried out on specimens with standard dimensions. In practice, dimensions of structural elements could be different from the dimensions of standard specimen. The dimensions’ ratio influences the strength of concrete specimen and the coefficient of strength variation. In the present study it is tried to obtain a meaningful relationship between size and strength based on the results of the tests on the specimens with different dimension ratios. Specimens examined in this study are C25 grade... 

    Incorporating aspect ratio in a new modeling approach for strengthening of MMCs and its extension from micro to nano scale

    , Article Advanced Composite Materials ; Volume 19, Issue 4 , Apr , 2010 , Pages 299-316 ; 09243046 (ISSN) Zehtab Yazdi, A ; Bagheri, R ; Zebarjad, S. M ; Razavi Hesabi, Z ; Sharif University of Technology
    The strengthening behavior of particle reinforced metal-matrix composites is primarily attributed to the dislocation strengthening effect and the load transfer effect. To account for these two effects in a unified way, a new multi-scale approach is developed in this paper incorporating the aspect ratio effect into the geometrically necessary dislocation strengthening relationships. By making use of this multi-scale approach, the deformation behavior of metal-matrix composites (MMCs) and metal-matrix nanocomposites (MMNCs) as a function of size, volume fraction, aspect ratio, etc. of the particles has been investigated. Comparison with the previously proposed models and the available... 

    On the sensitivity of the nanostructural parameters on youngg"s modulus of PLSNs in fully intercalated structures

    , Article Journal of Composite Materials ; Volume 43, Issue 24 , 2009 , Pages 2921-2941 ; 00219983 (ISSN) Zehtab Yazdi, A ; Bagheri, R ; Kazeminezhad, M ; Sharif University of Technology
    Polymer-layered silicate nanocomposites have been observed to demonstrate enhanced mechanical properties particularly at low weight fractions of silicate. Experimental and theoretical investigations reveal that numerous structural parameters strongly influence the modulus of such nanocomposites. A multiscale micromechanical model is developed which considers a wide range of different affecting parameters including the particle aspect ratio, the number of silicate layers per stack, the d-spacing ratio between the layers, the penetration of polymer chains along silicate sheets, the intercalation feature, and the particle volume fraction. The developed model illustrates the accuracy and... 

    Mass transport analysis of non-Newtonian fluids under combined electroosmotically and pressure driven flow in rectangular microreactors

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 508 , 2016 , Pages 345-359 ; 09277757 (ISSN) Yousefian, Z ; Saidi, M. H ; Sharif University of Technology
    Hydrodynamically fully developed flow of power-law fluids under combined action of electroosmotic and pressure gradient forces in rectangular microreactors is analyzed considering heterogeneous catalytic reactions. The Poisson-Boltzmann, Cauchy momentum, and concentration equations are considered in two dimensions and after being dimensionless are numerically solved applying a finite difference algorithm. Variation of axial concentration gradient, and axial and horizontal mass diffusions are taken into account as well. To accomplish a more general analysis, the velocity distribution is obtained by solving continuity and Cauchy momentum equations and is not considered as an average axial... 

    Free vibration of generally laminated plates with various shapes

    , Article Polymer Composites ; Volume 32, Issue 3 , FEB , 2011 , Pages 445-454 ; 02728397 (ISSN) Yousefi, P ; Kargarnovin, M. H ; Hosseini Hashemi, S. H ; Sharif University of Technology
    This article is focused on a simple approach for determining the natural frequency and mode shape of laminated angle-ply plates with various shapes by rectangular orthotropy. Since the boundary of the domain for all shapes are not natural to the material coordinate axes it seems appropriate to express the plate displacement amplitude in terms of a polynomial and a general shape function multiplication in the x and y coordinates. The boundary conditions considered are clamped and simply supported edges. The effect of the fiber orientation, layer number, and lamination sequence on the natural frequencies of plates is also considered. The natural frequency determinant has been generated using... 

    Incorporating multiscale micromechanical approach into PLSNs with different intercalated morphologies

    , Article Journal of Applied Polymer Science ; Volume 119, Issue 6 , September , 2011 , Pages 3347-3359 ; 00218995 (ISSN) Yazdi, A. Z ; Bagheri, R ; Kazeminezhad, M ; Heidarian, D ; Sharif University of Technology
    The objective of the present study is to predict Young's modulus of polymer-layered silicate nanocomposites (PLSNs) containing fully intercalated structures. The particular contribution of this article is to consider the changes in structural parameters of different intercalated morphologies in vicinity of each other. These parameters include aspect ratio of intercalated stacks, number of silicate layers per stack, d-spacing between the layers, modulus of the gallery phase, and volume fraction of each intercalated morphology. To do this, the effective particle concept has been employed and combined with the Mori-Tanaka micromechanical model. It has been shown that the simultaneous effects of... 

    Thermal buckling analysis of piezoelectric functionally graded plates with temperature-dependent properties

    , Article Mechanics of Advanced Materials and Structures ; Volume 22, Issue 10 , Nov , 2015 , Pages 864-875 ; 15376494 (ISSN) Yaghoobi, H ; Fereidoon, A ; Khaksari Nouri, M ; Mareishi, S ; Sharif University of Technology
    Taylor and Francis Inc  2015
    In this study, the thermal buckling analysis of hybrid laminated plates made of two-layered functionally graded materials (FGMs) that are integrated with surface-bonded piezoelectric actuators referred to as (P/FGM)s are investigated. Material properties for both substrate FGM layers and piezoelectric layers are temperature-dependent. Uniform temperature rise as a thermal load and constant applied actuator voltage are considered for this analysis. By definition of four new analytic functions, the five coupled governing stability equations, which are derived based on the first-order shear deformation plate theory, are converted into fourth-order and second-order decoupled partial differential... 

    Pressure effects on electroosmotic flow of power-law fluids in rectangular microchannels

    , Article Theoretical and Computational Fluid Dynamics ; Vol. 28, issue. 4 , 2014 , pp. 409-426 ; ISSN: 09354964 Vakili, M. A ; Sadeghi, A ; Saidi, M. H ; Sharif University of Technology
    In this paper, the fully developed electroosmotic flow of power-law fluids in rectangular microchannels in the presence of pressure gradient is analyzed. The electrical potential and momentum equations are numerically solved through a finite difference procedure for a non-uniform grid. A complete parametric study reveals that the pressure effects are more pronounced at higher values of the channel aspect ratio and smaller values of the flow behavior index. The Poiseuille number is found to be an increasing function of the channel aspect ratio for pressure assisted flow and a decreasing function of this parameter for pressure opposed flow. It is also observed that the Poiseuille number is... 

    Thermal transport characteristics pertinent to electrokinetic flow of power-law fluids in rectangular microchannels

    , Article International Journal of Thermal Sciences ; Vol. 79, issue , 2014 , p. 76-89 Vakili, M. A ; Saidi, M. H ; Sadeghi, A ; Sharif University of Technology
    In the present study, the thermal characteristics of electroosmotic flow of power-law fluids in rectangular microchannels in the presence of pressure gradient are investigated. The governing equations for fully developed flow under H1 thermal boundary conditions are first made dimensionless and subsequently solved through a finite difference procedure for a non-uniform grid. The influence of the major parameters on thermal features of the flow such as the temperature distribution and Nusselt number is discussed by a complete parametric study. The results reveal that the channel aspect ratio and the non-Newtonian characteristic of the fluid can affect the thermal behavior of the flow. It is... 

    Electrokinetically driven fluidic transport of power-law fluids in rectangular microchannels

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 414 , 2012 , Pages 440-456 ; 09277757 (ISSN) Vakili, M. A ; Sadeghi, A ; Saidi, M. H ; Mozafari, A. A ; Sharif University of Technology
    Electroosmosis is the predominant mechanism for flow generation in lab-on-chip devices. Since most biofluids encountered in these devices are considered to be non-Newtonian, it is vital to study the flow characteristics of common non-Newtonian models under electroosmotic body force. In this paper, the hydrodynamically fully developed electroosmotic flow of power-law fluids in rectangular microchannels is analyzed. The electrical potential and momentum equations are numerically solved through a finite difference procedure for a non-uniform grid. A thoroughgoing parametric study reveals that the Poiseuille number is an increasing function of the channel aspect ratio, the zeta potential, the... 

    Performance optimization of a long rod penetrator penetrating into a semi-infinite target considering bending characteristics

    , Article Turkish Journal of Engineering and Environmental Sciences ; Volume 33, Issue 1 , 2009 , Pages 9-20 ; 13000160 (ISSN) Vahedi, K ; Zohoor, H ; Nezamabadi, A ; Zolfaghari, M ; Sharif University of Technology
    In this article a new parameter is introduced that optimizes penetration depth of a long rod penetrating into a semi-infinite target. This parameter helps to optimize penetration depth when the projectile is subjected to transverse loading. This parameter is defined using a simple assumption governing bending moment and deflection of the rod as well as the experimental observation of long rod penetrators having aspect ratios (L/D) of greater than 30. In this article the length of the rod that sustains allowable bending stress but does not fail is calculated. Using the results of the bending analysis and solution of the Alekseevskii & Tate (AT) equation, an analytical method to optimize... 

    A modified saliency detection for content-aware image resizing using cellular automata

    , Article Proceedings of the 2010 International Conference on Signal and Image Processing, ICSIP 2010, 15 December 2010 through 17 December 2010 ; 2010 , Pages 175-179 ; 9781424485949 (ISBN) Toony, Z ; Jamzad, M ; Sharif University of Technology
    It is often required that image resizing be done brightly in order to preserve important content. Some image resizing techniques like scaling and cropping fail to identify and protect important objects, or they produce non-photorealistic images. But content aware image resizing schemes aim to change image aspect ratios while preserving visually outstanding features. In this paper, a novel method for content aware resizing is presented. Seam carving, an effective image resizing algorithm, fails to protect important objects in images, when either the energy content of the objects are low with respect to their surroundings, or, the number of seams removed are very large. Using saliency map as... 

    Investigation of particle dispersion and deposition in a channel with elliptic obstructions using lattice Boltzmann method

    , Article 2012 7th IEEE International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2012, 5 March 2012 through 8 March 2012 ; March , 2012 , Pages 523-528 ; 9781467311243 (ISBN) Tehrani, A ; Moosavi, A ; Sharif University of Technology
    Particle transport and deposition in a channel flow with elliptic obstruction is studied. Numerical simulation of fluid flow is performed using two-dimensional lattice Boltzmann method, while one-way coupling Lagrangian method for particle tracking is used. Standard particles are injected in the inlet of the channel. Gravity, Drag force, Brownian forces, and the Saffman lift are considered in equation of particle motion. The influence of geometrical parameter, ellipse aspect ratio, is studied on dispersion and deposition of particles as well as the flow parameters, such as Reynolds number. In addition, the effect of particles size -particles of 0.01-10μm in diameter- on dispersion and... 

    Influence of main and outer wings on aerodynamic characteristics of compound wing-in-ground effect

    , Article Aerospace Science and Technology ; Volume 55 , 2016 , Pages 177-188 ; 12709638 (ISSN) Tavakoli Dakhrabadi, M ; Seif, M. S ; Sharif University of Technology
    Elsevier Masson SAS 
    A practical mathematical model with low computational time and good accuracy is applied to investigate theaerodynamic characteristics and static height stability of the compound wing-in-ground effect (WIG). The compound WIG consists of a main wing with low aspect ratio and an endplate, and anouter wing with high aspect ratio. To validate the present mathematical model, a numerical simulation is performed so thatnumerical results had a good agreement with the experimental data. The analysis shows that the main wing is useful in the extreme ground effect zone and the outer wing enhances performance of the compound WIG in the weak ground effect zone. In order to satisfy the static height... 

    A new procedure to determine equivalent strut of infill walls with openings for engineering applications

    , Article Proceedings of the Institution of Civil Engineers: Structures and Buildings ; Volume 173, Issue 8 , 2020 , Pages 585-601 Tabeshpour, M. R ; Noorifard, A ; Sharif University of Technology
    ICE Publishing  2020
    In architecture, design of doors and windows for functional requirements, circulation, natural light and ventilation, aesthetics and view is inevitable. Parameters such as size, location and aspect ratio of the openings change the seismic behaviour of infilled frames. Ignoring these parameters in structural analysis may lead to substantial inaccuracy in predicting the lateral stiffness, strength and ductility of the frame. Despite numerous experimental and numerical studies on perforated infill walls in recent decades, the related provisions are rare in seismic codes and engineers tend not to use their results in analysis and design due to their complexity. The main purpose of this work was...