Sharif Digital Repository

A novel approach for mesoscale modelling of concrete composites is proposed by combining enriched scaled boundary finite element methods with quad-tree mesh. The concrete meso-structures are comprised of randomly distributed aggregates, mortar matrix, and interface transition zone. An improved random aggregate generation technique is developed to construct digital images of mesoscale concrete models. Based on the quadtree decomposition algorithm, meshes can be generated automatically from the digital images of concrete mesostructure. The whole mesh generation process is highly efficient without any artificial interference and eliminates the issue of hanging nodes faced by standard finite... 

Photothermally heated and mesh-gridded membrane distillation (PHMD) system is proposed for desalination of high saline aqueous solutions. A triple-layered membrane, composed of a photothermal top nanofibrous layer containing polyacrylonitrile and dispersed carbon black nanoparticles and a polyvinylidene fluoride porous membrane supported on a nonwoven polyester, was prepared. A polypropylene mesh was used to hold the membrane. A 3D numerical simulation of the PHMD system was carried out by COMSOL and the appropriate length of the membrane module was determined. The effects of various operating parameters including solar radiation intensity on the permeate flux and thermal efficiency were... 

Unreinforced masonry (URM) buildings are rather popular around the globe due to low construction costs, even though they can be prone to substantial damage caused by even moderate earthquakes. Numerous URM buildings that have experienced damages from past earthquakes require to be upgraded or at least return to their undamaged state in order to be able to withstand future earthquakes. In many cases, reconstruction is not the best choice because of financial and time restrictions. As such, repair/retrofit is the best choice, assuring the post-earthquake serviceability. Furthermore, seismic repair/retrofit can be a cost-efficient method to avoid reconstruction complexities and expenses. In... 

In an attempt to explore the significance of transport theory in neutron noise, localization of a noise source by Green's function based on transport theory is investigated. There are considerable differences between Green's functions based on diffusion and transport, such as small dimensions, near edges, high heterogeneity medium and high-frequency source of perturbation. These differences are expected to significantly impact unfolding, reconstruction, and identification of the neutron noise source. Improvement in noise source unfolding methods is essential in terms of safety aspects and reactor performance enhancement. Since gaining the ability to monitor nuclear reactor based on noise... 

The design and development of efficient approaches for water–oil separation have had widespread interest. Most previously introduced techniques and materials used for development of the successful separation of oily wastewater could not answer all the desired demands, such as being efficient and environmentally and economically friendly. Therefore, in seeking a novel method capable of answering these expectations, surfaces with special wettability were introduced. A novel, reusable, and recyclable superhydrophilic and superoleophobic poly(Vsim-Vim)@PFOA@SiO2 nanocomposite-coated stainless steel mesh was synthesized through a facile preparation process. Since the most important factors of... 

Superhydrophobic surfaces demonstrate significant characteristics which make them suitable for a wide variety of applications. In this study, we propose a facile, one-step, and cost-effective anodizing scheme using aluminum nitrate/stearic acid mixture solution to create a superhydrophobic surface on an aluminum mesh. The surface outperforms the surface anodized by the widely used oxalic acid solution in terms of superhydrophobicity and water-surface friction behavior. The proposed surface reduced the friction by 11% on average respective to the surface prepared by oxalic acid. The durability of the introduced superhydrophobic surface has also been investigated. The proposed surface retained... 

Seven half-scale reinforced concrete (RC) columns with supporting beam were experimentally studied under combined axial and lateral cyclic loading. The specimens were categorized in two groups based on reinforcement ratios. Three specimens were strengthened with carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) sheets. Other specimens were strengthened using a high strength mortar reinforced with textile mesh (textile reinforced concrete (TRC)). Strengthening of specimens were carried out using a vertical layer and a horizontal layer of FRP sheet or two vertical and two horizontal layers of textile meshes for TRC specimens. Since the weight of each layer of... 

Nonprecious and effective electrocatalyst development is an essential requirement for boosting water-splitting efficiency to obtain clean and sustainable fuels for future renewable energy demands. Herein, we reported an ultrafast and feasible strategy for constructing an S-doped bimetallic iron/nickel oxy(hydroxide) (S-(Fe/Ni)OOH) as a superior electrocatalyst for oxygen evolution reaction (OER). It is prepared by consequent electroplating of nickel nanocone arrays (NiNCAs) on carbon cloth (CC) and stainless-steel mesh (SSM) and then formation of S-(Fe/Ni)OOH layers on them by ultrafast one-step oxidation solution-phase method in the solution of Fe3+ and sodium thiosulfate at room... 

A surface to separate oil–water mixtures is a global concern and highly needed particularly in oil industries. The present study was conducted to create a novel superhydrophilic/superoleophobic nanocomposite coating on the stainless-steel mesh for the aim of oil/water separation. Different hydrophilic resins along with PFOA as oleophobic agent with 15 flours in its chemical structure and various oxide nanoparticles containing SiO2 and TiO2 at different concentrations were studied to achieve superhydrophilic/superoleophobic surface. The fabricated nanocomposites were fully characterized via field-emission scanning microscopy (FESEM), atomic force microscopy (AFM) and Fourier-transform... 

The design and development of efficient approaches for water–oil separation have had widespread interest. Most previously introduced techniques and materials used for development of the successful separation of oily wastewater could not answer all the desired demands, such as being efficient and environmentally and economically friendly. Therefore, in seeking a novel method capable of answering these expectations, surfaces with special wettability were introduced. A novel, reusable, and recyclable superhydrophilic and superoleophobic poly(Vsim-Vim)@PFOA@SiO2 nanocomposite-coated stainless steel mesh was synthesized through a facile preparation process. Since the most important factors of... 

Here, an excellent superhydrophobic and highly oleophobic nanocomposite coating composed of fluoroethylene-vinyl ether (FEVE) resin as a matrix for modified SiO2 nanoparticles was synthesized on a stainless-steel wire mesh substrate via a facile sol-gel method. The surface morphology, microstructure, composition, and roughness of the coatings were investigated by field emission scanning electron microscopy (FESEM) equipped with energy-dispersive spectroscopy (EDS) and atomic force microscopy (AFM). The most efficient coating with superhydrophobicity and high oleophobicity feature indicates the water and oil repellency with contact angles (CAs) of 152° and 141°, respectively, with the high... 

The objective of this study is to develop and apply an arbitrary Lagrangian-Eulerian unstructured finite-volume lattice-Boltzmann method (ALE-FVLBM) for solving two-dimensional compressible inviscid flows around moving bodies. The two-dimensional compressible form of the LB equation is considered and the resulting LB equation is formulated in the ALE framework on an unstructured body-fitted mesh to correctly model the body shape and properly incorporate the mesh movement due to the body motion. The spatial discretization of the resulting system of equations is performed by a second-order cell-centered finite-volume method on arbitrary quadrilateral meshes and an implicit dual-time stepping... 

In this paper, a numerical model is developed based on the X-FEM technique to simulate the transport of dense solute in a single fluid phase through the fractured porous media. The governing equation is based on the mass conservation law which is applied to the fluid phase and the solute in both matrix and fracture domain. The integral governing equations of the mass exchange between the fracture and the surrounding matrix is derived. The extended finite element method (X-FEM) is applied by employing appropriate enrichment functions to model the fractured porous domain. The superiority of the X-FEM is that the FE mesh is not necessary to be conformed to the fracture geometry, so the regular... 

We report the effect of the geometric parameters on transparency and conductivity in a metallic nanowire mesh as a transparent electrode. Today, indium tin oxide and fluorine-doped tin oxide are used as the transparent electrode for displays and solar cells. Still, there is a definite need for their replacement due to drawbacks such as brittleness, scarcity, and adverse environmental effects. Metallic nanowire mesh is likely the best replacement option, but the main issue is how to find the optimal structure and how to get the best performance. Since the interaction of light with nanowire mesh is complicated, there is no straightforward rule with a simple analytical solution. We developed a... 

Accurate estimation of the capacity curve of offshore jacket structures to achieve performance levels and ductility is of great importance. Proper modeling of compressive members to correctly investigate global and local buckling is crucial in estimation of the capacity curve. Buckling modes and deformations due to local buckling can be considered, if the compressive braces are modeled by shell or solid elements. The purpose of this paper is to achieve the correct compressive behavior of braces with solid type elements and investigate the effects of five different parameters such as D/t, L/D, mesh size, mesh size ratio, and imperfections. ABAQUS FE software is used for this purpose. The... 

The separation of water-oil mixtures has attracted widespread attention because of the increasing amounts of oily wastewater produced from the daily activities of humans and different industrial processes. Therefore, the development of facile and efficient oil-water separation technologies is imperative. In this work, a new highly superhydrophilic-superoleophobic coated stainless steel mesh was fabricated using virtue of the surface modification of poly (BzVimBr-Vim)@PFOA@SiO2 nanoparticles (NPs) through a facile preparation process. The new fabricated superhydrophilic and highly oleophobic coating exhibits good adhesive properties. The oil contact angle (OCA) and water contact angle (WCA)... 

Optical networks-on-chip are introduced as an alternative for electrical interconnects in many-core systems, due to their low delay and power consumptions, as well as their high bandwidths. Despite these advantages, physical characteristics of the photonic components are highly sensitive to thermal variations, which results in optical data misrouting through the optical networks at the presence of temperature fluctuation. In this paper, we propose a thermally-resilient all-optical communication approach which improves reliability, as well as performance of the optical networks. For this purpose, we take advantages of auxiliary waveguides and a novel wavelength assignment approach to avoid... 

Accurate estimation of the capacity curve of offshore jacket structures to achieve performance levels and ductility is of great importance. Proper modeling of compressive members to correctly investigate global and local buckling is crucial in estimation of the capacity curve. Buckling modes and deformations due to local buckling can be considered, if the compressive braces are modeled by shell or solid elements. The purpose of this paper is to achieve the correct compressive behavior of braces with solid type elements and investigate the effects of five different parameters such as D/t, L/D, mesh size, mesh size ratio, and imperfections. ABAQUS FE software is used for this purpose. The... 

This paper presents the improvements of cavitation modelling for marine propellers particularly developing tip vortex cavitation. The main purpose of the study is to devise a new approach for modelling tip vortex cavitation using Computational Fluid Dynamics (CFD) methods with commercial software, STAR-CCM+. The INSEAN E779A model propeller was used for this study as a benchmark propeller. Utilizing this propeller, firstly, validation studies were conducted in non-cavitating conditions together with grid and time step uncertainty studies. Then, the cavitation was simulated on the propeller using a numerical cavitation model, which is known as the Schnerr–Sauer model, based on the... 

Accurate estimation of the capacity curve of offshore jacket structures to achieve performance levels and ductility is of great importance. Proper modeling of compressive members to correctly investigate global and local buckling is crucial in estimation of the capacity curve. Buckling modes and deformations due to local buckling can be considered, if the compressive braces are modeled by shell or solid elements. The purpose of this paper is to achieve the correct compressive behavior of braces with solid type elements and investigate the effects of five different parameters such as D/t, L/D, mesh size, mesh size ratio, and imperfections. ABAQUS FE software is used for this purpose. The...