Sharif Digital Repository

Application of construction and demolition (C&D) wastes were considered as sustainable development goals (SDGs) for maintaining raw materials. Also, lightweight concretes such as aerated autoclaved concrete (AAC) were used for partitioning spaces in the building industry. Moreover, the waste products of the mentioned materials were increased due to the rise of old construction demolitions. This study contributes a calcinated aerated autoclaved concrete (CAAC) which is efficient, powerful, highly rapid, non-expensive and novel adsorbent for the removal of cationic dyes including malachite green (MG), methyl violet (MV) and methylene blue (MB) form water samples. The impacts of different... 

In the present work, a series of polysulfone (PSf) mixed-matrix nanofiltration membranes containing highly water stable UiO-66 metal-organic framework (MOF) were prepared via a simple phase inversion technique. At first, UiO-66 particles were synthesized via a solvothermal technique, activated via two various activation methods, including Soxhlet extraction and centrifugation methods. Then their adsorption performance was investigated for adsorption of anionic methyl orange (MO)/methyl red (MR) and cationic methylene blue (MB)/malachite green (MG) dyes from water. The activated UiO-66 particles via the Soxhlet extraction method (named S-UiO-66) showed better performance for dye adsorption... 

A novel integrated aeroelastic model of flapping wings (FWs) undergoing a prescribed rigid body motion is presented. In this respect, the FW nonlinear structural dynamics is enhanced via a newly proposed modification of implicit condensation and expansion (MICE) method that better considers the structural nonlinear effects. In addition, the unsteady aerodynamic model is also an extension of the widely utilized modified strip theory (MST) in which the flexibility effects are accounted for (MST-Flex). The integrated utility of the proposed generalized MICE and MST-Flex is demonstrated to be more realistic for elastic FW flight simulation applications. The prescribed rigid body motion is... 

Application of construction and demolition (C&D) wastes were considered as sustainable development goals (SDGs) for maintaining raw materials. Also, lightweight concretes such as aerated autoclaved concrete (AAC) were used for partitioning spaces in the building industry. Moreover, the waste products of the mentioned materials were increased due to the rise of old construction demolitions. This study contributes a calcinated aerated autoclaved concrete (CAAC) which is efficient, powerful, highly rapid, non-expensive and novel adsorbent for the removal of cationic dyes including malachite green (MG), methyl violet (MV) and methylene blue (MB) form water samples. The impacts of different... 

In this paper, a wideband coupled-resonator microstrip bandpass filter is designed and experimentally demonstrated in the S-Band. The filter is comprised of quarter-wavelength hair-pin resonators, reducing resonator and filter footprint compared to conventional hairpin designs. Additionally, it is considerably forgiving to fabrication tolerances and yields remarkably close matched results between theory, simulation, and measured results. One demonstration presented has minimal insertion loss ${(< 1{dB})}$ for the entire wide bandwidth of 3.4 GHz to 4.2 GHz. Wider bandwidths up to 60% are also observed using the design. The proposed filter is an attractive solution when space is a critical... 

A Non-rigid Air Flow Active Sensor (NAFAS) to detect the respiratory patterns is introduced in this paper. The main part of NAFAS is an ionic electroactive polymer-based ( ${i}$ -EAP) soft sensor. It can accurately detect breathing patterns and has promising features to develop low cost, wearable, and ubiquitous spirometers. Patients with respiratory diseases need to take pulmonary function tests consistently. Hence, it is time-consuming and expensive. To address these problems, NAFAS presents point-of-care testing (POCT) of the respiratory system's function. The proposed ${i}$ -EAP based sensor is a small strip of Ionic Polymer Metal Composite (IPMC) that has been fabricated using a Nafion... 

Herein, a magnetic zirconium-based metal-organic framework nanocomposite was synthesized by a simple solvothermal method and used as an adsorbent for the removal of direct and acid dyes from aqueous solution. To enhance its adsorption performance, poly(propyleneimine) dendrimer was used to functionalize the as-synthesized magnetic porous nanocomposite. The dendrimer-functionalized magnetic nanocomposite was characterized by field-emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption/desorption isotherms, and vibration sample magnetometer. The obtained results revealed the successful synthesis and functionalization of the... 

Activated carbon (AC) is an inert adsorbent material that has widely been used in water treatment or removing of environmental pollutants from water. In order to improve the adsorption of AC, which highly depends on its pore size and surface area, we prepared highly porous adsorbent composites of activated carbon (AC)/chromium-based MOF (MIL-101(Cr)). The composite has a high specific surface area of 2440 m2 g−1 and total pore volume of 1.27 cm3 g−1. To show the efficiency of the composite as an adsorbent, the removal kinetics of anionic dyes (Direct Red 31 and Acid Blue 92) from aqueous solutions dependent on the amount of composite, adsorption time, concentration of dye and pH is... 

In this research, UiO-66 and its composite nanoparticles with thermally oxidized nanodiamond (OND) were synthesized via a simple solvothermal method and utilized as solid adsorbent for the removal of anionic methyl red (MR) dye and cationic malachite green (MG) dye from contaminated water. The synthesized adsorbents were analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), N2 adsorption–desorption, and zeta potential analyzer. The influences of various factors such as initial concentrations of the dyes, adsorption process time, solution pH, solution temperature and ionic... 

The respiratory system is a vital organ system which makes breathing and gas exchange possible for human's body. The loss of functionality in this system is due to either genetical problems or environmental issues like pollution or toxic gases which in many cases is inevitable. These circumstances may cause different respiratory diseases which may not be curable presently but their side effects can be partly controlled by careful and timely analysis improving the quality of patient's life. So, an appropriate device for conducting different analysis can be effective for people who suffer from respiratory diseases such as chronic obstructive pulmonary disease (COPD), asthma, occupational lung... 

This study describes the concept and design of a low-cost super broadband dipole antenna with a passive matching network. The proposed dipole antenna is designed in three steps. First, a simple planar dipole antenna with six different loads and a balanced to unbalanced (Balun) transformer is designed by the genetic algorithm optimisation. The position and value of the loads are optimised to achieve an acceptable radiation pattern and voltage standing wave ratio (VSWR) over the desired frequency bandwidth. In the next step, the shape of the printed strip dipole antenna is optimised to improve the frequency response of the designed antenna. Finally, an LC network is added to the antenna feed... 

Kinetics and isotherms of adsorption behavior of nanoscale Zr-based metal-organic framework for the removal of three organic dyes including acidic, direct and basic ones from aqueous solutions were studied by sorption models. Nanocube-shaped UiO-66 particles with an average edge length of 215 nm, specific surface area of 1215 m2/g, total pore volume of 0.58 cm3/g, and average pore diameter of 1.8 nm were prepared by solvothermal methods. Analyzing of the equilibrium isotherms indicates that direct dye removal is best fitted with the Langmuir isotherm. Study of the adsorption kinetics also determines that direct dye adsorption follows pseudo-first-order model (R2=0.99). The kinetics of basic... 

Recently, graphitic carbon nitride (g-C3N4) has attracted great interest for photo(electro)chemical applications such as sensing, solar energy exploitation, photocatalysis, and hydrogen generation. This paper presents the potential application and benefits of g-C3N4 nanolayers as a green and highly efficient electrode modifier for the detection of trace lead ions in drinking water and urban dust samples. Carbon nitride nanosheets with a thickness of ∼6 A° and lateral of 100–150 nm were prepared through high-temperature polymerization of melamine followed by sonication-assisted liquid exfoliation. A glassy carbon electrode (GCE) was modified by a thin layer of g-C3N4 through drop casting and... 

This study is aimed to improve Zarnick’s (1978, A nonlinear mathematical model of motions of a planing boat in regular waves. David W. Taylor Naval Ship Research and Development Center, Bethesda, MD, USA) analytical model for motions of planing vessels. A nonlinear time domain mathematical model was developed for dynamic behaviour of longitudinal motion of high-speed planing crafts in regular waves. This model was based on two-dimensional strip theory method using expanding wedge theory and momentum. Due to the nonlinearity and complex dynamic behaviour of these vessels, the time-domain simulation was adopted. Total resistance, heave and pitch motions as well as acceleration were found very... 

This study is aimed to improve Zarnick’s (1978, A nonlinear mathematical model of motions of a planing boat in regular waves. David W. Taylor Naval Ship Research and Development Center, Bethesda, MD, USA) analytical model for motions of planing vessels. A nonlinear time domain mathematical model was developed for dynamic behaviour of longitudinal motion of high-speed planing crafts in regular waves. This model was based on two-dimensional strip theory method using expanding wedge theory and momentum. Due to the nonlinearity and complex dynamic behaviour of these vessels, the time-domain simulation was adopted. Total resistance, heave and pitch motions as well as acceleration were found very... 

In this work, cold rolling behavior of stainless steel 304L is investigated and the effects of different process parameters on the occurrence of strain-induced martensite and mechanical properties are studied. The rolling experiments are conducted under different rolling speeds and reductions in which a set of samples is deformed at room temperature and the other set is first cooled to the temperature of − 10 °C and then rolled. Afterward, the developed microstructures and mechanical properties of the rolled steel are evaluated employing different testing techniques. In order to justify the results, mathematical modeling of cold rolling operation is also performed using Abaqus/Explicit to... 

The asphalt industry has been at the forefront of sustainable development. Warm Mix Asphalt (WMA) has been developed to cope with issues such as high energy prices and air pollution. These mixes require less energy and generate fewer pollutants during production in comparison with conventional Hot Mix Asphalt (HMA). Although a promising technology, the durability of WMA is not clear because long-term WMA field performance data is limited. This study investigated the susceptibility of Sasobit-modified WMA to moisture, since moisture damage is a major cause of premature pavement failure in asphalt concrete. To this end, WMA samples were made using different concentrations of Sasobit and the... 

An integrated model based on finite-element method has been proposed to examine the mechanical and thermal responses of strips and work-rolls in tandem and reverse cold rolling operations. The model has been developed such that the influence of various process parameters, such as lubrication, rolling speed, frictional state and back-up rolls, can be examined. Thermal behaviors of the rolled material and the work-rolls have been analyzed using stream-line upwind Petrov-Galerkin approach, in order to make the model applicable to high-speed rolling processes, as well. The results have been compared to the actual on-line measurements and shown to be of acceptable accuracy. Such modeling approach... 

The stability of a viscoelastic plate strip, subjected to an axial load with the Kelvin–Voigt fractional order constitutive relationship is studied. Based on the classical plate theory, the structural formulation of the plate is obtained by using the Newton’s second law and the aerodynamic force due to the fluid flow is evaluated by piston theory. The Galerkin method is employed to discretize the equation of motion into a set of ordinary differential equations. To determine the stability margin of plate the obtained set of ordinary differential equations are solved using the Laplace transform method. The effects of variation of the governing parameters such as axial force, retardation time,... 

In this paper, a novel method is exposed to improve the performance of the Golden code. In fact, we recommend using the octagonal reconfigurable isolated orthogonal element (ORIOL) antennas instead of a conventional microstrip patch antenna. In order to obtain a dramatic improvement, the ORIOL antenna should be employed in both the transmitter and the receiver sides. Accordingly, in this paper, we recommend space-time-polarization diversity instead of space-time singly; therefore, it is obvious that by employing this technique, the system obtains more strength against destructive fading. The simulations for different rates have confirmed that utilizing the ORIOL antenna outperforms patch...