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Ghamari M.,Islamic Azad University at Tehran | Amadeh A.A.,University of Tehran
Transactions of the Institute of Metal Finishing | Year: 2017

In this work, Ni and Ni–Al2O3nanocomposite coatings were applied on AZ91 magnesium alloy using a pulse plating process and the corrosion resistance of coated samples was evaluated by means of the potentiodynamic polarisation method in 3.5 wt-% NaCl solution. Field emission scanning electron microscopy was employed to identify microstructure and morphology of the coatings. Vickers microhardness and pin-on-disc wear tests were also used to investigate mechanical properties of the coatings. The polarisation test revealed that the pure Ni coating on AZ91 along with the presence of nanoparticles were key factors leading to a reduction in the corrosion current density and the improvement of corrosion resistance so that the corrosion current density of 210.45 µA cm−2for the substrate (AZ91) decreases to 31.92 and 1.54 µA cm−2by applying pure Ni and Ni–Al2O3nanocomposite coatings, respectively. Furthermore, Ni–Al2O3nanocomposite coating increased the microhardness and wear resistance compared to the substrate up to 435 and 340%, respectively. © 2017 Institute of Materials Finishing Published by Taylor & Francis on behalf of the Institute.

Talebi R.,Islamic Azad University at Tehran
Journal of Materials Science: Materials in Electronics | Year: 2017

In this investigation we synthesize CoFe2O4 nanoparticles as a highly efficient photocatalyst for degradation of methyl orange. In addition, a green method for synthesis of CoFe2O4 magnetic nanoparticles with spherical morphology is proposed. We also investigated the effect of different carbohydrate sugars such as glucose, lactose and starch on morphology and particle size of nanoparticles. The crystal structures, morphology and chemical properties of the as-synthesized nanoparticles were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray, vibrating sample magnetometer techniques and UV–Vis diffuse reflectance spectroscopy. The photocatalytic activity of CoFe2O4 was investigated by degradation of methyl orange (MO) as cationic dye in aqueous solution under UV irradiation. The results indicate that about 77% of MO were degraded after 80 min. © 2017 Springer Science+Business Media New York

Peidaie M.M.,Islamic Azad University at Tehran | Sadeghimanesh M.,Islamic Azad University at Qazvin
International Journal of Services and Operations Management | Year: 2017

The purpose of this study is to design human resources dashboard. To refine the conceptual model and elements, fuzzy Delphi method was used and then a mathematical model based on ANFIS will be offered. The population is human resources personnel of Sepah Bank and 132 personnel are selected by Cochran formula for stratified sampling questionnaire including 61 questions based on indicators of two perspectives organised. In customer model, learning and growth has positive effect on output with 0.40 improvements; internal process has positive effect on output with 0.60 improvements. In financial model, learning and growth has negative effect on output with 0.29 decreases; internal process has negative effect on output with 0.14 decreases. It was found that the performance for first output (customer) is 38.80 and for second output (financial) is 39.00 (range of 0-100). Numbers that represent the performance is 50 for first element and 50 for second element. Copyright © 2017 Inderscience Enterprises Ltd.

Hosseini S.M.H.,Islamic Azad University at Tehran | Baravati P.R.,Islamic Azad University at Tehran
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2017

The first step of partial discharge (PD) detection is to obtain a model through which the winding behavior is monitored precisely in high frequencies. The multi-conductor transmission line (MTL) model is one of the best models conducting the PD studies. It is worth to say that one of the main problems of the MTL model is that it considers the windings in a parallel way as well as equal length. Solving the mentioned problem can decrease the simulation error relating to the PD detection. This paper presents an accurate approach in order to solve the problem. This modified MTL model uses the circular effect of windings. Considering the windings circular is one of the important parameters which should be evaluated with respect to PD signal propagation. This method has been applied on a 20 kV transformer winding. The simulation and experimental results show the powerful performance of circular multi-conductor transmission line (CMTL) model in comparison with the MTL model. © 1994-2012 IEEE.

Mosleh M.,Islamic Azad University at Tehran
Journal of Materials Science: Materials in Electronics | Year: 2017

In this paper, gadolinium tungstate Gd2(WO4)3 nanoparticles were synthesized via a new approach based on the reaction between gadolinium nitrate hexahydrate and Na2WO4.2H2O in water. Besides, three surfactants such as ethylene diaminetetraacetic acid (EDTA), sodium dodecyl sulfate (SDS), and polyvinylpyrrolidone (PVP) were used to investigate their effects on the morphology and particle size of Gd2(WO4)3 nanoparticles. According to the vibrating sample magnetometer, gadolinium tungstate Gd2(WO4)3 nanoparticles indicated a paramagnetic behavior at room temperature. The as-synthesized nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (UV–Vis), and energy dispersive X-ray microanalysis (EDX). To evaluate the catalytic properties of nanocrystalline gadolinium tungstate, the photocatalytic degradations of methyl orange under ultraviolet light irradiation were carried out. © 2017 Springer Science+Business Media New York

Zare Y.,Islamic Azad University at Tehran | Rhee K.Y.,Kyung Hee University
JOM | Year: 2017

In this paper, several models are introduced for tensile modulus and strength of polymer nanocomposites containing dispersed and networked carbon nanotubes (CNT) below and above percolation threshold. The model predictions are compared in similar conditions to determine the role of nanoparticle structure in the mechanical properties of polymer/CNT nanocomposites (PCNT). The predictions are also compared with the experimental data of several samples to offer the suitable models for the mechanical properties of PCNT. Lastly, the influences of the main parameters on the tensile modulus and strength of PCNT are studied. The networked nanoparticles cause higher levels of modulus and strength compared to the dispersed nanoparticles. The high level of the CNT aspect ratio causes a small percolation threshold in PCNT, but the Ouali model shows the ineffective role of this parameter in their predictions. © 2017 The Minerals, Metals & Materials Society

Pouraliakbar H.,Islamic Azad University at Tehran | Jandaghi M.R.,Islamic Azad University at Sāveh | Khalaj G.,Islamic Azad University at Sāveh
Materials and Design | Year: 2017

Al-Mn-Si specimens were severe plastic deformed (SPDed) through constrained groove pressing (CGP) by εeff = 1.16, 232, and 3.48. CGPed sheets were subsequently annealed at 150, 250 and 350 °C to investigate complementary treatment route on macro- and microscale properties of heavily strained alloy. Microstructure evolutions in deformed and post-annealed states along with their associated mechanisms such as recovery, recrystallization and strain induced grain boundary migration (SIGBM) were studied and analyzed. SIGBM as an indication for inhomogeneous grain growth was traced by transformations in grains' aspect ratio. Microanalysis of crystallographic characteristics by means of X-ray diffraction (XRD) patterns revealed that (111) planes were the main crystallographic index in CGPed and annealed alloys since preservation up to 350 °C had amplified the (200) and deteriorated the intensity of (311) planes. Dislocation density measurements implied the dynamic recovery occurrence in CGP (εeff = 2.32) which had affected mechanical characteristics, electrical conductivity and corrosion resistance of the utilized alloy. Mechanical properties through tension and hardness tests had been examined since the maximum YS, UTS, and hardness of 118 MPa and 141 MPa, 52 Hv obtained for CGPed specimen (εeff = 3.48) compared with annealed alloy with the values of 85 MPa and 112 MPa, and 29 Hv, respectively. © 2017 Elsevier Ltd

Haghayeghi R.,Islamic Azad University at Tehran | Qian M.,RMIT University
Materials Letters | Year: 2017

Step-by-step in situ near-atomic-resolution observations were presented for initial crystallization or nucleation in a liquid Al-10Mg (wt%) alloy containing spinel (MgAl2O4) seeds. Ordering of Al atoms was observed in the alloy at the interface with spinel at the superheat of 73 °C or at the melt temperature of 680 °C, where three ordered layers of Al atoms formed and disappeared alternately. When cooled to the approximate liquidus of the alloy, 607 °C, three similar but more stable ordered layers of Al atoms formed. Subsequent crystallization occurred first through the formation of partially close-packed Al atoms on the solid-like outer ordered layer of Al atoms, followed by further crystallization into more close-packed Al atoms. © 2017 Elsevier B.V.

Zarrabi F.B.,Islamic Azad University at Tehran | Naser-Moghadasi M.,Islamic Azad University at Tehran
Journal of Alloys and Compounds | Year: 2017

Plasmonic characteristic has been implemented for optical enhancement and the Fano resonance is noticed based on the interaction of the dark and bright mode at nano particle and for more enhancement, the second harmonic generation and multi Fano have been suggested. In this paper, we have designed a nano-antenna based on plasmonic, Fano, multi Fano and SHG modes and for this aim we have developed a single ring nano-particle with one and two split ring resonator elements for arousing multi Fano (SHG mode). Exactly, by arousing the Fano and multi Fano modes, the Extinction Cross Section is reduced in comparison with Plasmonic mode based on concentrating energy in the near field. We have shown that the angles of polarization have no effect on the extinction cross-section in multi Fano structure and it is independent of the polarization angle. We have revealed that how the multi Fano would be useful for light trapping and energy harvesting. We have obtained the wider bandwidth for the electric field in comparison with plasmonic and Fano structures which makes our proposed structure useful in energy harvesting applications such as solar cell at higher frequency ranges and an active area for wider bandwidth is achievable. For spectroscopy and optimal imaging, the figure of merit (FOM) is considered as a quality meter for the optical particles. The (FOM) of the external biological materials are compared for all three prototyped plasmonic, Fano and multi Fano structures. © 2017 Elsevier B.V.

Optimizing the manufacturing conditions of stable oil-in-water submicron emulsions using ultrasound assisted emulsification is a critical challenge in food and bio-industries. The influence of irradiation time (IT, 5–25 min) and ultrasonic applied power (UAP, 50–250 W) was studied on formation of stinging nettle essential oil (1.25 wt%)-nanoemulsions (SNEO-NEs) in aqueous solution of purified jujube polysaccharide (JCP-1, 1.5 wt%). Use of the single-factor and response surface methodologies showed an UAP of 165.87 W and an IT of 23.64 min can result in the best NE physicochemical properties including 86.75 nm droplet size, 0.079 polydispersity index, 1.331 refractive index, 34.5 mN/m surface tension, 4.49 mPa·s viscosity, 0.958 meq O2/kg oil peroxide value and 0.814 anisidine value. Kinetic analysis of stability and antioxidant losses of the optimal SNEO-NEs stored for 45 days demonstrated although there was no substantial difference in the droplets growth between 4 and 25 °C, a lower oxidative stability rate (24.1%) was monitored at 4 °C. The Gram-positive bacterium also was more inactivated by the optimal NE compared with the Gram-negative one (P < 0.05). This novel NE-based delivery system can be a successful strategy for the controlled release of other poorly water-soluble components with the improved functionalities. © 2017 Elsevier B.V.

Ahmadi A.,Islamic Azad University at Tehran | Rafibakhsh S.,Islamic Azad University at Tehran
International Journal of Theoretical Physics | Year: 2017

We study the baryonic potential between three static sources in the SU(3) gauge group through the thick center vortex model. We consider different open configurations where the line-like center vortex penetrates the Wilson loop in the Y, T and L ansatze. Our calculation shows that using uncorrelated center vortices, the data obtained from Y, L and T-shaped Wilson loops lie very close to each other at very large separations. Investigations on these three sets of data, one might conclude that the 3Q potential shows a little dependence on the flux tube meeting point only at intermediate distances. Comparing the slope of the three-quark potential in the Y, T and L form with the (Formula presented.) potential, we find (Formula presented.) at very large distances. In fact, the point to point ratio of the 3Q potential to the (Formula presented.) one varies from 1 -at small quark seperations- to 1.7 -at large distances. © 2017 Springer Science+Business Media New York

Hoseini S.A.,Islamic Azad University at Tehran
Journal of Materials Science: Materials in Electronics | Year: 2017

The effect of different acids such as cinnamic acid, salicylic acid, and oxalic acid on size, morphology and uniformity of PbTiO3 nanoparticles prepared via a auto-combustion sol–gel route was investigated. The structural, morphological, and optical properties of as-obtained products were characterized by techniques such as electron dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscopy and ultraviolet–visible spectroscopy. The estimated band gap shows that this product may be used as a photocatalyst, so the photocatalytic test was performed by photooxidation of methyl orange under UV irradiation and in the presence of PbTiO3. The results showed that methyl orange degradation was about 95% under for 50 min, so the synthesized product can be used as an effective photocatalyst. Vibrating sample magnetometer was used to study the magnetism properties of PbTiO3 sample. © 2017, Springer Science+Business Media New York.

Jafarinezhad M.R.,Islamic Azad University at Tehran | Eslami M.R.,Amirkabir University of Technology
Composite Structures | Year: 2017

This study deals with the response of an FGM annular plate under lateral thermal shock load. The equations of motion are obtained using the first order shear deformation plate theory. The governing equations are solved using the Laplace transformation and Galerkin finite element method. Finally, numerical inversion of the Laplace transform is carried out to obtain the results in real time domain. It is shown that coupling coefficient has a damping effect on the radial force resultant and deflection. © 2017 Elsevier Ltd

Zare Y.,Islamic Azad University at Tehran | Rhee K.Y.,Kyung Hee University
Composites Science and Technology | Year: 2017

The effective inverse aspect ratio (αeff) and volume fraction (φeff) of nanoparticles in polymer/CNT nanocomposites are defined accounting imperfect interfacial adhesion between polymer matrix and nanoparticles and percolation of interfacial regions as interphase percolation. After that, the tensile modulus and strength of nanocomposites are expressed by Halpin-Tsai and Pukanszky models to show the effects of radius (R) and length (l) of nanoparticles as well as the interphase thickness (t) and interfacial shear strength (τ) on the mechanical properties of nanocomposites. The best levels of “αeff” and “φeff” are obtained by the thinnest and the longest nanotubes as well as the highest values of “t” and “τ” factors. The best relative modulus of 8 is calculated by R < 13 nm and l > 6500 nm, while the strength slightly improves by R < 17 nm. Likewise, the relative modulus of 9 is calculated at t > 20 nm and τ > 170 MPa, while the best relative strength of 4.5 is shown at the highest levels of t = 25 nm and τ = 300 MPa. Conclusively, the interphase properties further affect the mechanical properties of nanocomposites compared to material parameters. © 2017 Elsevier Ltd

Zolfaghari M.,Islamic Azad University at Tehran | Pirouzfar V.,Islamic Azad University at Tehran | Sakhaeinia H.,Islamic Azad University at Tehran
Energy | Year: 2017

Today in the worldwide quest for production and economic preference, only industries will survive that have proper solutions for waste disposal and environmental pollution. In industrial applications, a blow down network of gases is used in order to control system pressure and safety instruments. At the end of this network, the excess gases are burnt in the flare tower, which have severe consequences on the environment. Different methods have been proposed and several alternatives have been introduced for reduction and recovery of flaring gases. In this paper, three methods including gas to liquid (GTL), gas turbines generation (GTG) and gas to ethylene (GTE) are introduced and compared with the best method from economic point of view being identified. For this purpose, a natural gas sample is taken from Asalloyeh Refinery Plant and the process has been simulated using Aspen HYSYS. Meanwhile, estimation of the capital and operating costs and evaluation of the processes involved were made using Aspen Capital Cost Estimator. According to the results obtained, production of the electric power from flaring gases is one of the most economical methods. GTG method, with an annual profit of about 480e+006 $, has a greater ROR percent. © 2017 Elsevier Ltd

Haghighi H.,Islamic Azad University at Tehran
Iranian Journal of Pharmaceutical Sciences | Year: 2016

The leaves of Arum conophalloides (Araceae) were used in some west areas of Iran as a dessert. The aerial parts of the herb were collected from Sahneh Mountains, Kermanshah Province, west of Iran and was hydrodistilled by Clevenger-type apparatus. Composition of the essential oil was determined by GC and GC/MS. Totally, 18 components (92% of total essential oil) were identified. The oil contains mainlyΤ-muurolol (%25.4), Ionone (%12.6), nonanal (%17.7), Τ-cadinol (%8.9), Fitone (%7.9), and Methyl palmitate (%7.0). The chemical composition of essential oils from the herbs is being reported for the first time. © 2016, Iranian Association of Pharmaceutical Scientists. All rights reserved.

Aghasi A.,Islamic Azad University at Tehran
30th Power System Conference, PSC 2015 | Year: 2015

Concerns related to climate change and security of energy supply are pushing various countries to make strategic energy planning decisions. In this regard, energy system modelling is an appropriate method to find out the utilization of current declining non-renewable energy resources and other possible scenarios. Consequently, it is available to consider various aspects of energy system decisions and some probable alternatives. This paper investigates different scenarios for Iran's electrical energy system applied in LEAP. Two different demand forecasting methods are used and the effects of applying four supply-side scenarios on CO2 emissions from power sector are finally compared. © 2015 IEEE.

Shahriari M.R.,Islamic Azad University at Tehran
Iranian Journal of Fuzzy Systems | Year: 2017

The current study set to extend a new VIKOR method as a compromise ranking approach to solve multiple criteria decision-making (MCDM) problems through intuitionistic fuzzy analysis. Using compromise method in MCDM problems contributes to the selection of an alternative as close as possible to the positive ideal solution and far away from the negative ideal solution, concurrently. Using Atanassov intuitionistic fuzzy sets (A-IFSs) may simultaneously express the degree of membership and non-membership to decision makers (DMs) to describe uncertain situations in decision-making problems. The proposed intuitionistic fuzzy VIKOR indicates the degree of satisfaction and dissatisfaction of each alternative with respect to each criterion and the relative importance of each criterion, respectively, by degrees of membership and non-membership. Thus, the ratings for the importance of criteria, DMs, and alternatives are in linguistic variables and expressed in intuitionistic fuzzy numbers. Using IFS aggregation operators and with respect to subjective judgment and objective information, the most suitable alternative is indicated among potential alternatives. Moreover, practical examples illustrate the procedure of the proposed method. © 2017, University of Sistan and Baluchestan. All rights reserved.

Zare Y.,Islamic Azad University at Tehran
Journal of Colloid and Interface Science | Year: 2017

The effect of percolation threshold on the mechanical properties of insulate polymer nanocomposites has been briefly investigated in literature. In this work, an approach is suggested to study the percolation threshold and interphase role in polymer/clay nanocomposites (PCN) by a model for tensile modulus. The percolation threshold is related to the aspect ratio of clay layers and the predictions of the suggested methodology are compared with the experimental data. A low percolation threshold is obtained by high aspect ratio of clay layers which increases the modulus. Also, the developed model suggests the accurate results compared to experimental data assuming the interphase role. According to the calculations, the best modulus of PCN is achieved by the thinnest clay layers and the thickest interphase between polymer and clay. © 2016

Khalaj Moazen M.,Islamic Azad University at Tehran | Ahmad Panahi H.,Islamic Azad University at Tehran
Journal of Separation Science | Year: 2017

Magnetic iron oxide nanoparticles are used for the extraction of a drug from an aqueous solution. In the current study, the magnetic iron oxide nanoparticles were synthesized via a facile coprecipitation approach, and then modified by (3-mercaptopropyl)trimethoxysilane followed by grafting thermosensitive polymer N-isopropylacrylamide and biopolymer chitosan. Structure, morphology, size, thermal resistance, specific surface area, and magnetic properties of the grafted nanosorbent were characterized by using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, elemental analysis, thermogravimetric analysis, specific surface area analysis and vibrating sample magnetometry. The effective parameters on sorption/desorption of letrozole on grafted magnetic nanosorbent were evaluated. The best sorption of letrozole via the grafted nanosorbent occurred at 20°C at an optimum pH of 7. The extraction of trace letrozole in human biological fluids is investigated and revealed 89.1 and 97.8% recovery in plasma and urine, respectively. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Afsharpour A.,Islamic Azad University at Tehran
Petroleum Science and Technology | Year: 2017

H2S solubility in MDEA aqueous solution at different solution compositions, temperatures, pressures, and acid gas loadings was correlated using electrolyte SRK-cubic plus association equation of state. A total of 302 experimental data were used in this work. At first pure components parameters were obtained from literatures. Then binary interaction parameters were calculated through binary subsystems investigation. Finally, ternary system modeled using a reactive bubble point pressure calculation method. Considering number of binary interaction parameters that should be optimized, three scenarios were proposed. All of the scenarios present good results with acceptable absolute average deviation percentage (AAD%) but the third one shows better outputs. The AAD% in this scenario is 17.02. © 2017 Taylor & Francis Group, LLC.

HAGHAYEGHI R.,Islamic Azad University at Tehran
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2017

The effects of ultrasonic treatment (UT) and electromagnetic stirring (EMS) forces, individually and in combination, prior to high pressure die-casting of AA5754 alloy were assessed. The liquid of alloy was subjected to UT, EMS and the combined style and then transferred to the shot chamber. The grain size, mechanical properties, gas content and hot tearing susceptibility were analyzed. The results suggest that the application of each process enhances grain refinement and decreases the porosity of the specimens. UT reduces the grain size from 140 to 82 μm and decreases the porosity from 5.5% to 1.4%. EMS reduces the grain size to 107 μm and the porosity to 3.3%. The combination of UT and EMS decreases the grain size and the porosity to 65 μm and 1.1%, respectively, which are the lowest grain size and porosity ever reported for this alloy achieved via physical processing. Intensive cavitation and stirring not only resulted in a refined microstructure but also significantly decreased the hot tearing susceptibility and improved the mechanical properties. All of the aforementioned characteristics are due to cavity formation, during each process. By combination of techniques, EMS could promote the nucleation process by providing more exogenous particles in the strong cavitation field of UT. Ultrasonic plays a major role in grain refining, decreasing the hot tearing susceptibility and the gas content by introducing a strong cavitation field. © 2017 The Nonferrous Metals Society of China

Razi M.,Islamic Azad University at Tehran | Haeri M.,Sharif University of Technology
International Journal of Systems Science | Year: 2017

This paper presents some computationally efficient algorithms for online tracking of set points in robust model predictive control context subject to state and input constraints. The nonlinear systems are represented by a linear model along with an additive nonlinear term which is locally Lipschitz. As an unstructured uncertainty, this term is replaced in the robust stability constraint by its Lipschitz coefficient. A scheduled control technique is employed to transfer the system to desired set points, given online, by designing local robust model predictive controllers. This scheme includes estimating the regions of feasibility and stability of the related equilibriums and online switching among the local controllers. The proposed optimisation problems for calculating the regions of feasibility and stability are defined as linear matrix inequalities that can be solved in polynomial time. The effectiveness of the proposed algorithms is illustrated by an example. © 2017 Informa UK Limited, trading as Taylor & Francis Group

Zare Y.,Islamic Azad University at Tehran | Rhee K.Y.,Kyung Hee University
Current Applied Physics | Year: 2017

In this paper, a simple model is developed to predict the tensile modulus of polymer/carbon nanotubes (CNT) nanocomposites (PCNT) above percolation threshold. Since the conventional models such as Ouali and Lyngaae-Jorgensen (L-J) cannot predict the accurate results, a developed model is presented which calculates proper modulus as a function of aspect ratio (α) and volume fraction of CNT at percolation threshold (ϕp). The developed model can present accurate data, which agree with the experimental results at all filler concentrations. The high ranges of “α” and low values of “ϕp” achieve a desirable modulus. However, a high “ϕp” causes the poor modulus at different “α” demonstrating that the role of “α” is highlighted at slight “ϕp”. It is also possible to calculate the “α” and “ϕp” parameters by applying the developed model to the experimental data of modulus. © 2017 Elsevier B.V.

Korayem M.H.,Iran University of Science and Technology | Nahavandi A.,Islamic Azad University at Tehran
Journal of Sound and Vibration | Year: 2017

The aim of the present study is to assess the force vibrational performance of tapering-shaped cantilevers, using Euler–Bernoulli theory. Tapering-shaped cantilevers have plan-view geometry consisting of a rectangular section at the clamped end and a triangular section at the tip. Hamilton's principle is utilized to obtain the partial differential equations governing the nonlinear vibration of the system as well as the corresponding boundary conditions. In this model, a micro cantilever, which is covered by two piezoelectric layers at the top and the bottom, is modeled at angle α. Both of these layers are subjected to similar AC and DC voltages. This paper attempts to determine the effect of the capillary force exerted on the cantilever probe tip of an atomic force microscope. The capillary force emerges due to the contact between thin water films with a thickness of hc which have accumulated on the sample and the probe. In addition, an attempt is made to develop the capillary force between the tip and the sample surface with respect to the geometry obtained. The smoothness or the roughness of the surfaces as well as the geometry of the cantilever tip have significant effects on the modeling of forces applied to the probe tip. In this article, the Van der Waals and the repulsive forces are considered to be the same in all of the simulations, and only is the capillary force altered in order to evaluate the role of this force in the atomic force microscope based modeling. We also indicate that the tip shape and the radial distance of the meniscus greatly influence the capillary force. The other objective of our study is to draw a comparison between tapering-and rectangular-shaped cantilevers. Furthermore, the equation for converting the tip of a tapering-shaped cantilever into a rectangular cantilever is provided. Moreover, the modal analysis method is employed to solve the motion equation. The mode shape function for the two tapering-shaped sections of the first and the second kind of Bessel functions is utilized. The nonlinear governing equation is solved by employing the Forward Time Simulation (FST). As the Atomic Force Microscopy cantilever switches from the attractive mode to the contact repulsive mode upon proximity to the surface and the reverse occurs during the departure from the sample surface, a hybrid mode is developed which is illustrated in the graphs. © 2016 Elsevier Ltd

The present research describes an approach to radar pulse separation through a set of state-of-the-art cluster validity indices in association with fuzzy-based representation. Detection of a number of radars during the separation process is an important applicable issue, which needs to be investigated more in both real and academic environments. It is obvious that the fuzzy-based clustering approach may be known as one of the intelligent solutions regarding the interleaved radar pulse separation. In a word, the study considers the optimal number of clusters on the basis of the cluster validity indices that are useful to determine the radars. To consider the performance of the proposed approach, the whole of cluster validity indices are simulated though a series of experiments in some applicable scenarios in the area of interleaved radar pulse separation. The outcomes indicate that W-index is known as a suitable candidate to guarantee the better performance with high accuracy, while the fuzzy c-means technique is realized. In fact, a purposeful integration of the fuzzy c-means in association with W-index aims us to separate the interleaved radar pulse trains, efficiently. Subsequently, the effectiveness of the approach performance is verified by demonstrating its accuracy to be resulted as 96.71 %, while 10 % of additional pulse and 2 % of noise are included. © 2015, Springer-Verlag Berlin Heidelberg.

Khoshnevis Yazdi S.,Islamic Azad University at Tehran | Shakouri B.,Islamic Azad University at Tehran
Energy Sources, Part B: Economics, Planning and Policy | Year: 2017

This study investigates the correlation among economic growth, renewable energy, energy consumption, capital fixed formation, globalization, trade openness, and urbanization for 1992 Q1–2014 Q4, using the auto-regressive distributed lag (ARDL) model in Iran. The ARDL approach demonstrates that renewable energy is positively correlated with economic growth. The results show that all the variables in the study are co-integrated and there is a long-run relationship among variables. The findings also show that the overall index of globalization has a positive effect on growth. Granger causality reports bidirectional causality among renewable energy consumption (REC), globalization, financial development, and economic growth. © 2017 Taylor & Francis Group, LLC

Ghadiri M.,Islamic Azad University at Tehran | Shirazian S.,University of Limerick
Environmental Science and Pollution Research | Year: 2017

Membrane-based non-dispersive solvent extraction is used in many chemical processes due to its significant benefits such as straightforward scale-up and low energy consumption. A mechanistic model was developed to predict recovery of benzoic acid (BA) from wastewater using membrane contactors. Model equations were derived for benzoic acid transport in the membrane module, and solved using FEM. The model findings were compared with experimental results, and an average deviation of 4% was observed between experimental and simulation results. Simulations showed that change in organic phase flowrate and initial concentration of BA does not have considerable effect on the removal efficiency of benzoic acid. In addition, increasing feed flowrate leads to the enhancement of convective mass transfer flux in the tube side of membrane contactor which decreases removal efficiency of benzoic acid. © 2017 Springer-Verlag Berlin Heidelberg

Mianehrow H.,Islamic Azad University at Tehran | Mianehrow H.,KTH Royal Institute of Technology | Abbasian A.,Islamic Azad University at Tehran
Journal of Cleaner Production | Year: 2017

With respect to the importance of energy consumption reduction in industrial plants, an attempt has been made to specify the most important parameters affecting energy consumption of plastic injection molding process as one of the most energy intensive processes in plastics industry. In this regard, the specific energy consumption of six hydraulic injection molding machines and the profile of their energy consumption over one cycle of injection molding process were measured to assess the effect of different machine related and process related parameters on energy consumption and realize energy saving opportunities in the injection molding process. Results showed that among all quantitative parameters, throughput and total cycle time, which are process related parameters, have the most important impact on the specific energy consumption of the process. Whereas, the most important effect of machine related parameters were found to be on the peak power of energy consumption, which gives an insight to industrial plants how to reduce the maximum electrical demand of the plant. In addition, it was proved that each hydraulic injection molding machine has a unique profile of energy consumption depending on the design of the machine and process, and then according to these profiles, three types of process designs were identified. © 2017 Elsevier Ltd

Mehrpooya M.,University of Tehran | Sayyad S.,Islamic Azad University at Tehran | Zonouz M.J.,University of Tehran
Journal of Cleaner Production | Year: 2017

A hybrid combined cooling, heating and power (CCHP) system which consists of molten carbonate fuel cell (MCFC), Stirling engine and double effect LiBr/H2O absorption chiller is introduced and analyzed. Molten carbonate fuel cell is the main power production source which its exhausted heat is used as heat source of the Stirling engine. Exhausted heat from the Stirling engine is used as heat source of the absorption chiller's generator. The produced power of the process is 6482 kW, also it provides 2137 kW heat duty and 1372 kW cold duty. Performance of the process is evaluated by energy and exergy analysis methods. Also sensitivity of the overall and electrical efficiencies to the fuel utilization factor, air flow rate to the burner, burner outlet temperature and oxidant flow rate are analyzed. Results of the energy analysis show that overall and electrical efficiencies are 71.71% and 42.28% respectively. Exergy analysis shows that molten carbonate fuel cell, Stirling engine and gas turbine have considerable efficiencies. Highest exergy destruction rate is related to the CH4 and H2 burners that mostly is because of the irreversible nature of the combustion. © 2017 Elsevier Ltd

Zare Y.,Islamic Azad University at Tehran | Rhee K.Y.,Kyung Hee University
Polymers for Advanced Technologies | Year: 2017

In this article, the effects of filler network and interphase between polymer matrix and nanoparticles on the tensile modulus of polymer/carbon nanotubes (CNT) nanocomposites are assumed by the effective volume fraction of nanoparticles. By this approach, the Takayanagi model is developed for polymer/CNT nanocomposites above percolation threshold. Also, the effective factors for filler network including the number (N), aspect ratio (α) and percolation threshold (ϕp) of CNT are correlated to three main parameters. The developed model is evaluated for some reported samples from previous papers, and the influences of main parameters on the modulus are examined. The acceptable predictability of the developed model for modulus of nanocomposites is illustrated by experimental results. The "α" and "N" parameters play positive roles in the modulus, while an inverse relation is observed between the modulus and the percolation threshold. The reasonable effects of these parameters on the tensile modulus of polymer/CNT nanocomposites are also discussed. © 2017 John Wiley & Sons, Ltd.

Yazdandoust M.,Islamic Azad University at Tehran
Soil Dynamics and Earthquake Engineering | Year: 2017

The widespread use of reinforced-soil walls, especially in seismic regions has led to extensive studies on seismic behavior of this structures. In this paper, to assess the behavior and performance of steel-strip reinforced-soil retaining walls during seismic loading, a series of 1-g shaking table tests were conducted on 0.9 m high reinforced-soil wall models with different strip lengths. The physical models were subjected to variable-amplitude harmonic excitation at different peak accelerations and durations. It was found that the deformation mode of walls highly depends on the length of strips. The observed predominant mode of deformation was combination of bulging of the facing and rotation about the wall base without base sliding. The pattern of the observed failure mechanisms included a moving block which is delineated by a combination of a slant and reverse curve with certain intersection point. Irrespective of different steel strip lengths, the threshold acceleration corresponding to the onset of plastic displacements was similar and equal to 0.6 g for all models and the threshold acceleration corresponding to the onset of the development of active wedge failure was dependent on strip length so that this critical acceleration increased with increasing the strip length. Also, a consistent range of ∆x/H' between 0.2% and 0.8% (or ∆x/H'=0.2–0.8%) representing a transitional state of the walls from quasi-elastic to plastic state and a consistent range of ∆x/H' between 4.5% and 4.9% (or ∆x/H'=4.5–4.9%) representing a transitional state of the walls from plastic to failure state were observed. On the other hand, according to the sudden increase in wall displacements caused by decreasing the nail length from 0.7H' to 0.5H', the L/H' ratio of 0.7 was presented as the critical ratio in seismic conditions. © 2017 Elsevier Ltd

Aboutalebi M.,Islamic Azad University at Tehran | Parsa S.,Iran University of Science and Technology
International Journal of Cooperative Information Systems | Year: 2017

In this paper, a novel business process engineering method based on quality assessment is proposed. In the proposed method, a goal model is used to estimate the operational costs of business processes. Goals scenarios in the goal model of desired information systems are applied as a basis for estimating the design cost. Qualities of business requirements models and business process models are also estimated. Based on the quality metrics, the process of business process modeling is examined. Then, using XOR operator in the goal model, a simple and direct mapping of the goal model to the business process model is introduced. Common activities in the business process model are further factored and summarized using pre- and post-factoring operations. The proposed business process modeling method is language-independent. An ICT office in Mazandaran Power Distribution Company is used as a case study to exemplify QABPEM. Our evaluation results demonstrates the capability of the proposed method compared with the existing ones. © 2017 World Scientific Publishing Company.

Rahimi A.,Islamic Azad University at Tehran | Monajjemi M.,Islamic Azad University at Tehran
Journal of Computational and Theoretical Nanoscience | Year: 2017

Fatty acids in liver are subject to different patterns of regulation and the importance of fat deposition began to be realized with the evolution of vertebrates and the liver was the initial site of deposition. Modern sharks frequently have massive livers containing cells loaded with triglycerides. Based on our previous works we have modeled and simulated various molecules of those fatty acids. A number of computational chemistry studies carried out to understand the of the fatty acid synthesis (FAS) for preventing the fatty liver disease. In this work the electrical properties such as electron densities, energy densities, potential energy densities, ELF, LOL, ellipticity of electron density, eta index and ECP for some of the fatty acids have been calculated. © 2017 American Scientific Publishers.

Asadpour S.H.,Islamic Azad University at Tehran
Applied Optics | Year: 2017

The properties of Goos-Hänchen (GH) shifts for transmitted and reflected light pulses in a cavity with an intracavity medium consist of carbon nanotube quantum dot nanostructures, which have been discussed theoretically by using the stationary phase theory. Our findings show that due to the presence of spin-orbit coupling, the maximum negative and positive shifts can be realized by modifying the absorption and dispersion properties of the intracavity medium. Moreover, the effect of the transverse magnetic field has been also considered as a new parameter for controlling the GH shifts in reflected and transmitted light beams. We hope that our proposed structure may be suitable for the generation of future all-optical system devices based on carbon nanotube quantum dot nanostructures. © 2017 Optical Society of America.

Abbasi A.,Islamic Azad University at Tehran | Poshtan J.,Iran University of Science and Technology
ISA Transactions | Year: 2017

In this paper, two approaches for robust state estimation of a class of Lipschitz nonlinear systems are proposed. First, a novel Unknown Input Observer (UIO) is designed without observer matching condition satisfaction. Then, an H∞ observer for approximate disturbance decoupling is proposed. Sufficient conditions for the existence of both proposed observers are derived based on a Lyapunov function. The achieved conditions are formulated in terms of a set of linear matrix inequalities (LMIs) and optimal gain matrices are obtained. The minimum values of the disturbance attenuation levels for both methods are obtained through solving optimization problems. Finally, the proposed approaches are compared by simulation studies of an automated highway system. © 2017 ISA.

Sadi-Nezhad S.,Islamic Azad University at Tehran | Noroozi-Yadak A.,Islamic Azad University at Tehran | Makui A.,Iran University of Science and Technology
Journal of Intelligent and Fuzzy Systems | Year: 2013

In this paper, a new triangular fuzzy distance is proposed for two triangular fuzzy numbers and this distance is developed and applied for two points in a K-dimensional space. In this fuzzy distance we use the left and right point. Its calculations are easier compared to the previous presented distances and its result is always a non negative fuzzy number. This distance can be widely used in Multiple Attribute Decision Making (MADM) techniques and data mining. Finally, some examples are presented to illustrate the benefits of this method. © 2009 - IOS Press and the authors.

Beheshtizadeh M.,Islamic Azad University at Tehran | Moslemi E.,Islamic Azad University at Tehran
Journal of Gastric Cancer | Year: 2017

Purpose: This study aimed to analyze G3BP1 and VEZT expression profiles in patients with gastric cancer, and examine the possible relationship between the expressions of each gene and clinicopathological factors. Materials and Methods: Expression of these genes in formalin-fixed paraffin embedded (FFPE) tissues, collected from 40 patients with gastric cancer and 40 healthy controls, was analyzed. Differences in gene expression among patient and normal samples were identified using the GraphPad Prism 5 software. For the analysis of real-time polymerase chain reaction products, GelQuantNET software was used. Results: Our findings demonstrated that both VEZT and G3BP1 mRNA expression levels were downregulated in gastric cancer samples compared with those in the normal controls. No significant relationship was found between the expression of these genes and gender (P-value, 0.4835 vs. 0.6350), but there were significant changes associated with age (P-value, 0.0004 vs. 0.0001) and stage of disease (P-value, 0.0019 vs. 0.0001). In addition, there was a direct relationship between VEZT gene expression and metastasis (P-value, 0.0462), in contrast to G3BP1 that did not demonstrate any significant correlation (P-value, 0.1833). Conclusions: The results suggest that expression profiling of VEZT and G3BP1 can be used for diagnosis of gastric cancer, and specifically, VEZT gene could be considered as a biomarker for the detection of gastric cancer progression. © 2017. Korean Gastric Cancer Association.

Sargazi Zadeh G.,Islamic Azad University at Tehran | Panahi N.,Islamic Azad University at Tehran
Clinical and Experimental Hypertension | Year: 2017

Several pharmacological activities of the essential oil of Trachyspermum ammi seeds (TAEO) have been previously studied. These include antitussive, antihypertensive, and antispasmodic effects. However, its action on isolated aorta has not yet been studied. This study was aimed to investigate the vasorelaxant activity of TAEO and characterize its mechanism of action. Extraction of TAEO was performed using Clevenger-type apparatus with the final content of 4.5% (v/w). To evaluate some probable mechanisms of action of TAEO, the action isometric tension was then measured in the aortic rings from Wistar rats which were precontracted with phenylephrine (PHE) (1 µM) or KCl (60 mM). The major constituents of TAEO included Thymol (38.1%), gamma-terpinene (33.3%), and p-cymene (23.1%), as was analyzed by GC-MS. The cumulative concentrations of TAEO reduced precontraction caused by PHE and KCl (p < 0.05) significantly, which was dose dependent. The vasorelaxation caused by TAEO was not influenced in the presence of methylene blue and L-NAME in the endothelium-intact and denuded aorta ring. The inhibitory effect of TAEO on the aortic rings precontracted with KCl and PHE was considerably reduced by nifedipine. These findings hypothesized that the vasorelaxation caused by TAEO is completely endothelium independent and the extracellular Ca2+ influx was also inhibited by TAEO. © 2017 Taylor & Francis.

Ahmadi S.,Islamic Azad University at Kermānshāh | Habibpour E.,Islamic Azad University at Tehran
Anti-Cancer Agents in Medicinal Chemistry | Year: 2016

The GA-MLR method is a potent search method based on the evolution of biological systems for QSAR modeling. In the current study we have studied the QSAR modeling of some arylthioindoles derivatives which obtained by replacing the 2-alkoxycarbonyl group with a bioisosteric five-membered heterocycle nucleus. The general hypothesis was that these derivatives might be useful for designing and synthesizing the anticancer drugs, since they are a class of powerful inhibitors of tubulin polymerization and cancer cell growth. The data set has been divided into the training and test subsets for external validation of QSAR model using random splitting method. The random splitting of training subset (80% of data) performed 20 times and the remaining compounds used as external validation subset. The GA-MLR and S-MLR methods have been applied as variable selection methods on 20 random training subsets. The best multivariate linear model based on (Formula Presented) values consist of four parameters in both GA-MLR and S-MLR methods and the (Formula Presented) values were 0.7242 and 0.3215 for GA-MLR and S-MLR methods, respectively. The results indicate that GA-MLR method is more powerful method for variable selecting in comparison with S-MLR method. © 2016 Bentham Science Publishers.

Heidarzadeh Hanzaee K.,Islamic Azad University at Tehran | Esmaeilpour F.,Islamic Azad University at Tehran
Journal of Islamic Marketing | Year: 2017

Purpose: The purpose of this paper is to examine how the moderating effect of restaurant type (fast food versus casual dining) affects the Generation Y’s customers’ reaction to reward time redemption (immediate versus delayed) and reward type (economic versus social). Design/methodology/approach: A 2 × 2 × 2 full-factorial, randomized, between-subject experimental design is conducted to test the research framework. The treatment groups are different from each other by manipulating reward type, reward timing and restaurant type through eight different scenario exposures. Findings: The findings of the study reveal that the loyalty is significantly higher for immediate than delayed rewards in the both examined restaurant segments. In the casual dining restaurant segment, the effect of rewards increases for social rewards more than economic ones. On the other hand, for fast food restaurant context, there is no difference in the effect of reward type, whether they are economic or social. Research limitations/implications: Due to the limitations of fine dining restaurants in Iran, the present study consists of only two types of restaurants (fast food vs casual dining). Originality/value: This study aims to contribute towards the understanding how restaurant type (fast food versus casual dining) affects the impact of restaurant reward programs on the loyalty of Generation Y’s customers. © 2017, © Emerald Publishing Limited.

Monajjemi M.,Islamic Azad University at Tehran
Journal of Molecular Liquids | Year: 2017

Liquid-phase exfoliation (LPE) of graphite towards graphene has been investigated theoretically. In this study we have shown the sulfonic groups in a surfactant are most effective for any dispersion in the LPE process. In addition the ionic surfactant has an excellent efficiency compared to those non-ionic or zwitterion forms. Generally these sequence can be suggested for any dispersion in the LPE process as cation > anion > zwitterion > nonionic. The aromatic and ionic surfactant interact with various carbon materials, such as, fullerenes, graphite and carbon nanotubes, through p-stacking that takes place between their electron-abundant aromatic cores and conjugated surfaces of the carbon materials. © 2017 Elsevier B.V.

Mahmoodi A.,Islamic Azad University at Tehran
UPB Scientific Bulletin, Series A: Applied Mathematics and Physics | Year: 2016

We characterize the approximate Connes-amenable Beurling algebras ℓ1(S,oω) through the existence of some specified nets in ℓ∞ (S × S)z.est;, where S is a discrete, weakly cancellative semigroup. For a discrete group G, we prove that approximate Connes-amenability and approximate amenability of ℓ1(G,ω) are the same. We show that Connes-amenability of a dual Banach algebra A and that of M (A) n are equivalent.

Nekouei F.,Islamic Azad University at Tehran | Nekouei S.,Islamic Azad University at Tehran
Journal of Alloys and Compounds | Year: 2017

This research is focused on two removal procedures namely adsorption and synergetic adsorption-photodegradation of methylene blue (MB) from aqueous solution by using bismuth oxychloride nanoplates loaded on activated carbon composite (BiOCl–NPls–AC composite) as a novel adsorbent/photocatalyst. In the present work, for the first time, the results of various and well-known kinetic and isotherm models of MB adsorption onto the BiOCl–NPls–AC composite (without UV irradiation) were reported and compared with those obtained from synergetic adsorption–photodegradation MB removal (under UV irradiation). After synthesizing the BiOCl–NPls by using a simple and low-cost method, the newly synthesized BiOCl–NPls and BiOCl–NPls–AC composite were characterized by using different methods (e.g. field emission scanning electron microscopy (FESEM), dynamic light scattering (DLS), Brunauer, Emmett and Teller (BET), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), UV–Vis and raman spectroscopy). The effects of BiOCl–NPls–AC dose, pH, initial MB concentration, and contact time on the removal efficiency of MB were also investigated and optimized values established. The Langmuir model yields, with maximum adsorption capacities of 17.470 and 84.021 mg g−1, could describe the adsorption processes better than other isotherm models for both adsorption and especially synergetic adsorption–photodegradation procedures. Moreover, the adsorption processes were fitted to the pseudo-second-order and Elovich models better than other kinetic models for both adsorption and synergetic adsorption-photodegradation procedures. The results showed that the removal efficiency and adsorption capacity (98.88% and 86.021 mg/g) are higher for synergetic photodegradation and adsorption under UV light irradiation than only adsorption of the MB onto the BiOCl–NPls–AC composite in a dark place (72.50% and 17.470 mg/g). Finally, the stability of the BiOCl–NPls–AC composite regarding Bi leaching was evaluated. © 2017 Elsevier B.V.

Lotfi E.,Islamic Azad University at Tehran | Neek-Amal M.,Shahid Rajaee Teacher Training University
Journal of Molecular Graphics and Modelling | Year: 2017

Graphene doped with nitrogen exhibits unique properties different than perfect graphene. The temperature distribution in nitrogen-doped graphene (N-graphene) and in the graphene with grain boundary is investigated using molecular dynamics simulations. The temperature distribution in nitrogen-doped graphene nanoribbon, containing two types of grain boundaries, was found to be sensitive to the number of dopants and grain boundary. We also found that there is a remarkable temperature gap in the temperature profile of N-graphene nanoribbon-containing a grain boundary. For any doping ratio N/C we found that the nitrogen atoms enhance roughness of N-graphene and decrease thermal conductivity. © 2017 Elsevier Inc.

Salari A.A.,Islamic Azad University at Tehran
Comptes Rendus Chimie | Year: 2017

It has been previously indicated that pristine graphene cannot detect NO2 gas. Nanographene is a segment of graphene whose end atoms are saturated with hydrogen atoms and its properties are different from those of graphene. Herein, we investigated the reactivity, electronic sensitivity, and structural properties of hexa-peri-hexabenzocoronene (HBC) nanographene toward NO2 gas using density functional theory calculations. It was found that the central and peripheral rings of HBC are aromatic but the middle rings are non-aromatic, following Clar's sextet rule of aromaticity. The NO2 molecule prefers to be adsorbed on the central ring with a nitro configuration, releasing an energy of about 13.2 kJ/mol. The NO2 molecule significantly stabilizes the LUMO level of the HBC, thereby reducing the HOMO-LUMO energy gap from 3.60 to 1.35 eV. This indicates that the HBC is converted from a semiconductor to a semimetal. It was shown that the adsorption of NO2 gas by HBC can produce an electrical signal selectively in the presence of O2, H2, N2, CO2, and H2O gases. A short recovery time about 1.9 ns is predicted and the effect of density functional is investigated. © 2017 Académie des sciences.

Rockburst is a typical dynamic disaster in underground coal mines which its occurrences relate to the mechanical quality of coal seam and surrounding rock mass and also the condition of stress distribution. The main aim of this paper is to study the potential of rockburst in a longwall coal mine by using of passive seismic velocity tomography and image subtraction technique. For this purpose, first by mounting an array of receivers on the surface above the active panel, the mining-induced seismic data as a passive source for several continuous days were recorded. Then, the three-dimensional tomograms using simultaneous iteration reconstruction technique (SIRT) for each day are created and by employing the velocity filtering, the overstressed zones are detected. In addition, the two-dimensional seismic velocity tomograms in coal seam level by slicing the three-dimensional tomograms are obtained. Then the state of stress changes in successive days by applying the image subtraction technique on these two-dimensional tomograms is considered. The results show that the compilation of filtered three-dimensional tomograms and subtracted images is an appropriate approach for detecting the overstressed zones around the panel and subsequent evaluation of rockburst potential. The research conclusion proves that the applied approach in this study in combination with field observations of rock mass status can effectively identify the rockburst-prone areas during the mining operation and help to improve the safety condition. © 2017 Springer Science+Business Media Dordrecht

Nezafati N.,Islamic Azad University at Tehran | Hessari M.,Research Institute of Cultural Heritage and Tourism RICHT
Periodico di Mineralogia | Year: 2017

The fourth season of archaeological excavations at Tappeh Shoghali which is located ca. 40 km southeast of Tehran has revealed numerous metallurgical relics of silver production from Sialk III-IV period (late fourth and early third millennium BCE). The feld examination of the objects together with mineralogical and geochemical investigations indicate that the litharge cakes and fragments, a silver-rich lead ingot, and several crucibles and furnaces, as well as miniature dishes are the remaining of a significant silver production activity out of an argentiferous ore in the site during the late fourth millennium/early third millennium BCE. This makes the site one of the earliest silver production workshops and one of the best preserved site hosting ancient silver extraction installations and relics in the Old World. The discovery of this early silver production site in north central Iran alongside the presence of other already known silver (and copper) production sites of early urbanization time in central Iran (e.g. Tappeh Sialk, Arisman, and Hissar) highlighted the relevance of central Iran in the early development of such an ancient technology.

Kamari Kaverlavani S.,Tarbiat Modares University | Moosavifard S.E.,Islamic Azad University at Tehran | Bakouei A.,Tarbiat Modares University
Chemical Communications | Year: 2017

Multilevel interior nanoporous CuCo2O4 microspheres have been for the first time developed using a facile self-templated method. Electrochemical results in three- and two-electrode systems show that the double-shelled hollow microsphere electrode is a promising candidate for high-performance supercapacitors. © The Royal Society of Chemistry.

khosrojerdi S.,Islamic Azad University at Tehran | Lavasani A.M.,Islamic Azad University at Tehran | Vakili M.,Iran University of Science and Technology
Solar Energy Materials and Solar Cells | Year: 2017

The use of nanofluids as the working fluid in systems for converting solar to thermal energy has led to remarkable progresses. This study has investigated the thermo-optical characteristics of nanofluids containing Graphene oxide nanoplatelets/deionized water as the working fluid for low-temperature direct absorption solar collectors (DASCs). The prepared samples of nanofluid contain graphene oxide nanoplatelets based on deionized water with weight percentages of 0.001, 0.005, 0.015 and 0.045. Results show that the applied nanofluid has suitable ability compared to the base fluid in absorbing solar energy, ranging from 200 to 2500 nm. Also, results from calculation of absorbed energy's fraction suggest that the minimum height or thickness of the nanofluid layer having the ability of full sun's energy, is for the nanofluid with weight percentage of 0.045 and height of 3 cm that has the ability of absorbing 99.6% of energy. The thermal conductivity coefficient of prepared samples was measured at temperature ranging 25–50. Results showed that increasing the weight percentage of nanofluid along with increase in temperature would improve nanofluid's thermal properties in comparison with the base fluid. Finally, by investigating the impact of weight percentage of the nanofluid's temperature on radiative properties and thermal conductivity, this nanofluid with strong absorption band in the range of 280–350 nm (nanometers) was introduced and proposed as the appropriate environment for using direct absorption solar collectors. © 2017 Elsevier B.V.

Rafibakhsh S.,Islamic Azad University at Tehran | Shahlaei A.,Islamic Azad University at Tehran
EPJ Web of Conferences | Year: 2017

We calculate the potential between static quarks in the fundamental representation of the F4 exceptional gauge group using domain structures of the thick center vortex model. As non-trivial center elements are absent, the asymptotic string tension is lost while an intermediate linear potential is observed. SU(2) is a subgroup of F4. Investigating the decomposition of the 26 dimensional representation of F4 to the SU(2) representations, might explain what accounts for the intermediate linear potential, in the exceptional groups with no center element. © The Authors, published by EDP Sciences, 2017.

Rostami H.,Baqiyatallah Medical Sciences University | Gharibzahedi S.M.T.,Islamic Azad University at Tehran
International Journal of Biological Macromolecules | Year: 2017

Enzyme-assisted extraction process of the water-soluble Malva sylvestris polysaccharides (MSPs) was optimized using response surface methodology (RSM). The highest yield (10.40%) of MSPs was achieved at 5.64% cellulase, 55.65 °C temperature, 3.4 h time, and 5.22 pH. Three homogeneous polysaccharide fractions (MSP-1, MSP-2, MSP-3) were purified by DEAE-cellulose and Sephadex G-100 chromatography, which were composed of galactose, glucuronic acid, arabinose, rhamnose and mannose in different molar ratios with molecular weight range of 2.6 × 105–8.8 × 105 Da. The fractions could significantly increase antioxidant, antitumor and antimicrobial activities in a dose-dependent pattern. MSP-2 revealed stronger antioxidant activities than MSP-1 and MSP-3, including reducing power and scavenging activity of DPPH and OH radicals. The antiproliferative activity of MSP-2 (1.0 mg/mL) on the growth of A549 and HepG2 cells was 45.1% and 53.2%, respectively. The Gram-positive bacteria (Bacillus cereus PTCC 1015 and Staphylococcus aureus PTCC 1112) compared with Gram-negative ones (Escherichia coli PTCC 1763 and Salmonella typhimurium PTCC 1709) showed less sensitivity against the various MSPs (3–15 mg/mL). © 2017 Elsevier B.V.

Fayyazbakhsh A.,Islamic Azad University at Tehran | Pirouzfar V.,Islamic Azad University at Tehran
Renewable and Sustainable Energy Reviews | Year: 2017

The present review investigates modification of diesel fuel formulation and development of a new model to enhance engine performance, improve fuel properties and reduce exhaust emissions. Emissions arising from the fuel can be controlled by blending an oxygenated fuel (renewable fuel) with the diesel fuel. The blending oxygenated fuels namely Methanol, Ethanol, and n-Butanol are examined in addition to their effects. This review paper studies the implication of different torques and various engine speeds. In some conditions, it can even cause an increase in the content of carbon monoxides (CO), carbon dioxide (CO2) and nitrogen oxides. This review showed that the engine speed has a negative effect on all of the air pollutants, so that increasing of the engine speed leads to reduction of the air pollutants. However, the engine load gives rise to most exhaust emissions. Adding the oxygenate fuels increases brake specific fuel consumption (BSFC), while brake thermal efficiency (BTE) decreases. In some researches, a nano-metal additive has been used in the fuel for improving the engine performance. In case of using the nano-metal additives to the diesel fuel (a nano-metal with small thermal conductivity coefficient), the engine performance is seen increased. © 2017 Elsevier Ltd

Vosoughifar M.,Islamic Azad University at Tehran
Journal of Materials Science: Materials in Electronics | Year: 2017

In this investigation, a facile precipitation route has been developed for the preparation of cadmium tungstate (CdWO4) nanoparticles by using cadmium nitrate hexahydrate and sodium tungstate dehydrate as cadmium and vanadate precursor, respectively. The effect of different capping agents such as glycine, valine, and alanine on the morphology and particle size of the products has been investigated. Facile preparation and separation are important features of this route. This work has provided a general, simple, and effective method to control the composition and morphology of cadmium tungstate in aqueous solution, which will be important for inorganic synthesis methodology. The morphology and particle size of products were investigated by scanning electron microscopy images, X-ray diffraction patterns, ultraviolet–visible and electron dispersive X-ray spectroscopy spectroscopy. The photocatalytic characteristics of as-obtained nanocrystalline cadmium tungstate were also examined by degradation of methyl orange dye as water contaminant. © 2017 Springer Science+Business Media New York

Talebi R.,Islamic Azad University at Tehran
Journal of Materials Science: Materials in Electronics | Year: 2017

Nanoparticles sphere-like barium tungstate (BaWO4) have been successfully synthesized via the co-precipitation method process by using barium nitrate hexahydrate, Na2WO4·2H2O and of different surfactants like cetyl trimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and ethylene diamine tetraacetic acid (EDTA). The as-synthesized nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (UV–Vis), and energy dispersive X-ray microanalysis (EDX). According to the vibrating sample magnetometer, barium tungstate (BaWO4) nanoparticles indicated a ferromagnetic behavior at room temperature. Photo-catalytic property of barium tungstate was examined by degradation of methyl orange as organic pollutant in water under UV light irradiation. The results showed that methyl orange degradation was about 80% under for 70 min, so the synthesized product can be used as an effective photocatalyst. © 2017 Springer Science+Business Media New York

Mosleh M.,Islamic Azad University at Tehran
Journal of Materials Science: Materials in Electronics | Year: 2017

In this work various morphologies of nickel molybdate (NiMoO4) nanostructures were synthesized via chemical reaction between nickel chloride hexahydrate, ammonium heptamolybdate tetrahydrate and different capping agents like alanine, asparagine, and phenylalanine. The products were also characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray energy dispersive spectroscopy (EDS) and diffuse reflectance spectroscopy (UV–Vis). Vibrating sample magnetometer (VSM) was used to study the magnetism properties of NiMoO4 sample. The photocatalytic behavior of nanoparticles was evaluated using the degradation of a methyl orange (MeO) aqueous solution (as an organic pollution) under ultraviolet (UV) light irradiation. The results confirm that nanoparticles are promising materials with excellent performance in photocatalytic applications. © 2017 Springer Science+Business Media New York

Abooshahab R.,Islamic Azad University at Tehran
Asian Pacific journal of cancer prevention : APJCP | Year: 2016

BACKGROUND: Adipokines are bioactive proteins that mediate metabolism, inflammation and angiogenesis. Changes in the secretion of key serum adipokines - adiponectin and letpin - may be associated with obesity, cancer and metabolic disorders. Thyroid cancer is one of the most important types of endocrine cancer. Therefore, investigating the association between serum levels of adiponectin and leptin and thyroid cancer might be important. The purpose of this study was to assess adiponectin and leptin levels in medullary thyroid carcinoma (MTC) cases in order to identify novel tumor markers.MATERIALS AND METHODS: This research was based on a case-control study, including 45 patients with medullary thyroid cancer (21 men and 24 women) and 45 healthy controls (24 males and 21 females). Adiponectin and leptin levels were measured by ELISA in both groups. Height and weight were measured and body mass index (kg/m2) was calculated.RESULTS: Adiponectin and leptin levels were not significantly different between medullary thyroid carcinomas and the control group. Also, there was no correlation among age and body mass index and the disease.CONCLUSIONS: These results suggest that changes in serum adiponectin and leptin levels do not play an important role in the diagnosis or could act as as biomarkers for medullary thyroid cancer.

Parhizgar A.R.,Islamic Azad University at Tehran
Iranian Journal of Medical Sciences | Year: 2017

Antimalarial drugs with the 4-aminoquinoline scaffold such as the important drugs, chloroquine (CQ) and amodiaquine (AQ), have been used to prevent and treat malaria for many years. The importance of these drugs is related to their simple usage, high efficacy, affordability, and cost-effectiveness of their synthesis. In recent years, with the spread of parasite resistance to CQ and cross-resistance to its other analogues have decreased their consumption in many geographical areas. On the other hand, AQ is an effective antimalarial drug which its usage has been restricted due to hepatic and hematological toxicities. The significance of the quinoline ring at quinoline-based antimalarial drugs has prompted research centers and pharmaceutical companies to focus on the design and synthesis of new analogues of these drugs, especially CQ and AQ analogues. Accordingly, various derivatives have been synthesized and evaluated in vitro and in vivo against the resistant strains of the malaria parasite to solve the problem of drug resistance. Also, the pharmacokinetic properties of these compounds have been evaluated to augment their efficacy and diminish their toxicity. Some of these analogues are currently in clinical and preclinical development. Consequently, the recent researches showed yet 4-aminoquinoline scaffold is active moiety in new compounds with antiplasmodial activity. Hence, the aim of this review article is to introduce of the novel synthetic analogues of CQ and AQ, which may constitute the next generation of antimalarial drugs with the 4-aminoquinoline scaffold. © 2016, Shiraz University of Medical Sciences. All rights reserved.

Chatrenour N.,Islamic Azad University at Tehran | Razmi H.,Islamic Azad University at Tehran | Doagou-Mojarrad H.,Islamic Azad University at Tehran
Energy Conversion and Management | Year: 2017

In this paper, an Improved Double Integral Sliding Mode MPPT Controller (IDISMC) for a stand-alone photovoltaic (PV) system is proposed. Performance of a sliding mode controller (SMC) is greatly influenced by the choice of the sliding surface. Switching surface coefficients were selected by the use of Hurwitz stability theorem. The IDISMC not only is robust against parametric and non-parametric uncertainties, but also has a very small steady-state error, thanks to the use of double integral of tracking voltage error in the definition of its sliding surface. For realistic simulation, Genetic Algorithm (GA) method was used to estimate parameters of solar panels model. The validity of the proposed double integral SMC in maximum power point tracking was approved by comparing the simulation results obtained for a sample PV system with the results of other methods. © 2017 Elsevier Ltd

Samimi A.,Islamic Azad University at Borūjerd | Nikzad M.,Islamic Azad University at Tehran | Siano P.,University of Salerno
Renewable Energy | Year: 2017

In this paper, an efficient stochastic framework is proposed to develop a coupled active and reactive market in smart distribution systems. Distributed Energy Resources (DERs) can offer active powers to the market and also offer their reactive powers via a multi-component bidding framework constructed based on their reactive power capability diagrams. Distribution Company (Disco) buys active and reactive powers from a wholesale market and sells them via this market. Aggregators on behalf of responsive loads can participate in the market using a demand buyback program (DBP). The uncertainties of forecasted loads and wind power generation are considered in the proposed framework. To model the stochastic variables, the scenario tree is created using the Weibull and the Gaussian probability density functions (PDFs). The cost objective function of the stochastic coupled market clearing consists of the expected costs of energy and reactive power purchased from the DERs and Disco, the expected penalty cost of CO2 emissions of DERs and the main grid as well as the expected cost of running DBP. The proposed market is cleared through a mixed-integer nonlinear optimization problem solved in GAMS software. The effectiveness of the proposed method is investigated based on a 22-bus 20-kV radial distribution test system. © 2017 Elsevier Ltd

Ghafouri R.,Islamic Azad University at Tehran | Ektefa F.,Islamic Azad University at Tehran
Journal of Molecular Structure | Year: 2017

We have applied density functional calculations to study the reactions CX3[Formula presented]20H20, and CX3[Formula presented]20F20 (X = H, F, Cl and Br) based on two pathways (H- or F-displacement and H- or F-abstraction from C20H20 and C20F20). Our results show that CH3[Formula presented] radical prefers H- or F- abstraction from C20H20 and C20F20 while F-displacement is favorable for the reaction of CF3[Formula presented] with the fullerenes. Exothermic characters of H- or F-abstraction with the lower potential barrier indicate that the H-abstraction will dominate the reaction CCl3[Formula presented]20H20 while endothermic characters with high potential barrier heights for two reaction pathways of C20H20 and C20F20 with CBr3[Formula presented] indicate unfavorable thermodynamically and kinetically pathways for these reactions. The exothermic reactions are proceed via reactant-like transition state while endothermic reactions will proceed via “late” and alkyl radical-like transition state, consistent with Hammond's postulate. These results are in line with the distribution of natural charges and electrostatic surface potentials (ESP) of reactants. Among these reactions, the reaction of CF3[Formula presented] with C20F20 is most favorable both thermodynamically and kinetically which indicate that reaction of CF3[Formula presented] with C20F20 and C20H20 is more favorable than CCl3[Formula presented] and CBr3[Formula presented] radicals. © 2016 Elsevier B.V.

Tamandani S.,Islamic Azad University at Tehran | Darvish G.,Islamic Azad University at Tehran
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2017

We present an analytical method to calculate photon absorption coefficient in mono and bilayer circular graphene quantum dots (CGQDs). We use kobo equation to extract new closed relation as the main goal. First, we calculate real and imaginary part of optical conductance separately. Then, joint density of states is obtained using a new relation that was extracted for the energy levels of mono and bilayer circular grapheme quantum dots. In this work we use closed equations to calculate energy levels in CGQDs. Next we obtain a new closed formula to calculate the photon absorption coefficient. The results show that the absorption coefficient is related to the size of CGQDs and number of layers. The photon absorption coefficient becomes lower with larger size of CGQDs. It is seen that the results of our method is compatible with the results of practical works. We also compare photon absorption in biased and unbiased bilayer CGQDs and investigate the effect of external magnetic field on photon absorption. © 2001 Elsevier Science. All rights reserved © 2016 Elsevier B.V.

The article describes a magnetic metal-organic framework (MOF) of the type MIL-101(Fe)/2-(propylamino-ethyl) dithiocarbamate on the surface of magnetite nanoparticles. The MOF is shown to be a viable material for speciation analysis of Cr(III) and Cr(VI) because it shows selectivity for Cr(VI) at pH values around 2.0, while at pH values around 5 both Cr(III) and Cr(VI) species are sorbed. Hence, preoxidation or reduction treatments are not needed. After optimization of the extraction conditions, chromium was quantified by ET-AAS. Feature of the determination of Cr(VI) include (a) a 1.0 ng L−1 limit of detection, (b) a linear analytical range that extends from 3 to 300 ng L−1, and (c) a relative standard deviation of 6.4%. The respective values for total chromium are 1.5 ng L−1, 4 to 325 ng L−1 and 7.5%, respectively. The method was validated by analyzing two certified reference materials. It also was successfully employed to the rapid extraction and speciation of Cr(III) and Cr(VI) in (spiked) water samples and of total chromium in tea samples. [Figure not available: see fulltext.] © 2017 Springer-Verlag Wien

Dezfooli S.,Islamic Azad University at Tehran | Mahmoudi Hashemi M.,Islamic Azad University at Tehran
Journal of Molecular Liquids | Year: 2014

A simple and efficient synthesis of spirooxindole derivatives by one-pot, three-component reaction of isatins, malononitrile and different nucleophiles under catalyst-free condition in deep eutectic solvent is reported. A series of biological importance, spirooxindole derivatives were synthesized via a multicomponent reaction of isatin, or acenaphthoquinone, and malononitrile or cyanoacetic ester with 1,3-dicarbonyl compounds, naphtol and 4-hydroxycumarin in biodegradable choline chloride based deep eutectic solvent in good yields (50-95%). This green procedure has the advantages of higher yields, shorter reaction times, environmental friendliness, and easy work-up. © 2014 Elsevier B.V.

Monfared V.,Islamic Azad University at Zanjan | Mondali M.,Islamic Azad University at Tehran
Materials and Design | Year: 2014

In this research work, semi-analytical method (SAM) is presented to predict composite creep strain rate and quasi shear-lag (QSL) formulation directly, as well as, finite element method (FEM) is employed for predicting partial creep debonding at the interface in steady state creep of short fiber composites under tensile axial stress. Also, new formulation QSL is introduced to obtain the average axial stress in fiber which its results are similar to the results of shear lag (SL) model. Then, it is shown that FEM can approximately predict the partial debonding in some regions of the interface. As a result, interfacial debonding can be caused by high tensile axial and circumferential stresses, high shear and equivalent stresses, and low compressive radial stresses with considering stress concentration. The results obtained from SAM are in good agreement with the available experimental results. Finally, it is concluded that FEM simulation can be useful for predicting some defects such as interfacial debonding and also better designing the fibrous composites. © 2013 Elsevier Ltd.

Ashoori A.,Islamic Azad University at Tehran | Barati A.,University of New England of Australia
Italian Journal of Zoology | Year: 2013

Breeding success was investigated in a mixed colony of three species of Ardeidae (Black-crowned Night Heron, Nycticorax nycticorax; Little Egret, Egretta garzetta; and Cattle Egret, Bubulcus ibis) in the Karfestan colony, south Caspian Sea, during the 2006 breeding season. Black-crowned Night Herons occupied higher locations for nesting (4.39 ± 1.44 m) than both Little Egrets (3.07 ± 1 m) and Cattle Egrets (2.8 ± 0.84 m). Clutch size appeared to be independent of the height of the nest from the ground in all species. Mean breeding success was 0.82 ± 0.24, 0.80 ± 0.16 and 0.77 ± 0.17 in the Black-crowned Night Heron, Little Egret and Cattle Egret respectively. Overall breeding success did not vary significantly among the three species. Fledging success and overall breeding success were associated with nest height in the Black-crowned Night Heron, with a tendency for the higher nests to be more successful. Nest height was also correlated with fledging success in the Cattle Egret but had no effect on breeding success in the Little Egret. © 2013 Copyright 2013 Unione Zoologica Italiana.

Shahidi S.,Islamic Azad University of Arak | Ghoranneviss M.,Islamic Azad University at Tehran
Progress in Organic Coatings | Year: 2011

In this research work, one side of polyester fabrics was coated by platinum using DC magnetron sputtering. The dye ability of coated and uncoated samples to different natural and synthetic dyes was evaluated. The antibacterial counting test was used for determination of antibacterial efficiency of both treated and untreated samples. The results show that, the existence of platinum nanolayer on the surface of PET fabrics causes improve the dyeability of fabrics. The improvement for natural dyes is more significant than for synthetic dye. According to antibacterial activity tests, platinum itself has no antibacterial effect against Staphylococcus aureus. However, the natural dyed Pt-coated samples show moderate antibacterial effect. © 2010 Elsevier B.V. All rights reserved.

Ganji S.S.,Islamic Azad University at Tehran | Barari A.,University of Aalborg | Ganji D.D.,Babol Noshirvani University of Technology
Computers and Mathematics with Applications | Year: 2011

MaxMin Approach (MMA) is applied to obtain an approximate solution of three practical cases in terms of a nonlinear oscillation system. After finding maximal and minimal solution thresholds of a nonlinear problem, an approximate solution of the nonlinear equation can be easily achieved using He Chengtian's interpolation. Numerical results indicate the effectiveness of the proposed method both in respect of the whole range of involved parameters as well as the excellent agreement with the approximate frequencies and periodic solutions with the exact ones. It is predicted that MMA can be found widely applicable in engineering. © 2010 Elsevier Ltd. All rights reserved.

Fazelpour F.,Islamic Azad University at Tehran | Soltani N.,Islamic Azad University at Tehran | Soltani S.,Islamic Azad University at Tehran | Rosen M.A.,University of Ontario Institute of Technology
Renewable and Sustainable Energy Reviews | Year: 2015

In recent years, wind energy utilization has become increasingly attractive on economic grounds. Wind turbines for electricity generation employ a proven technology, supply energy on a reliable and sustainable basis, and at good, windy sites may even be competitive with conventional sources of energy. In this paper, the statistical results are reported of an investigation of the potential of wind energy as a power source for the Iranian northwestern cities of Tabriz and Ardabil. A number of different methods were explored as well. In this study, the Weibull probability distribution function is employed using mean meteorological wind data measured at three-hour intervals. These data have been measured at a height of 10 m above ground level and gathered over a six-year period. Furthermore, the hourly, diurnal, seasonal, monthly, and annual wind speed variations are analyzed and the economics of the wind turbines is evaluated. The yearly values of the Weibull shape parameter vary from 1.81 to 2.13 m/s with a mean of 1.99 m/s for Tabriz and from 2.62 to 2.98 m/s with a mean of 2.86 m/s for Ardabil. Also, yearly values of the Weibull scale parameter vary from 3.35 to 4.45 m/s with a mean of 4.18 m/s for Tabriz and from 3.68 to 4.55 m/s with a mean of 4.16 m/s for Ardabil. The results show that the highest wind power potential occurs during months of August and July in Tabriz and during months of October and September in Ardabil. The results indicate that the monthly mean price of electricity generated from the 25 kW wind turbine in Tabriz and Ardabil, for most of the months of the year, are less than or approximately equivalent to the current purchase tariff of renewable energy in Iran. © 2015 Elsevier Ltd.

Moosazadeh M.,Islamic Azad University at Tehran | Ghobadi C.,Islamic Azad University at Urmia | Dousti M.,Islamic Azad University at Tehran
IEEE Antennas and Wireless Propagation Letters | Year: 2010

A monopole antenna, consisting of a square patch with square slots and a ground plane truncated with two mirror L-shaped notches is designed for ultrawideband (UWB) applications. The design employs a checkered-shaped semifractal patch with Lp × Wp squares. The proposed antenna operates in the 3.110.6-GHz band and has small overall dimensions of 12 × 18 × 1.6 mm 3. The effect of the ground plane notch on the optimization of the return loss is discussed in detail. © 2006 IEEE.

Moosazadeh M.,Islamic Azad University at Tehran | Esmati Z.,Islamic Azad University at Urmia
Microwave and Optical Technology Letters | Year: 2012

A coplanar waveguide fed (CPW-fed) ultra wideband (UWB) antenna with dual band- notched characteristics is proposed. In this antenna, an E-shaped patch and a ground plane truncated with two mirror notches are designed for UWB applications. Two notched frequency bands are achieved by adjusting the E-shaped form lengths in the radiation patch. The proposed antenna operates in the 3.1-10.6 GHz for a voltage standing-wave ratio (VSWR) less than 2, except two frequency notched bands of 3.3-4.23 and 5.05-5.87 GHz, and has small overall dimensions of 18 × 15 × 1.6 mm3. Experimental and simulated antenna results show that the proposed antenna has a desirable VSWR level and radiation pattern characteristics for the UWB frequency band range. © 2012 Wiley Periodicals, Inc.

Manocheri Z.,Islamic Azad University at Tehran
Research on Chemical Intermediates | Year: 2012

A convenient and rapid method for the electrophilic substitution reaction of indoles with carbonyl compounds has been developed by using deep eutectic solvent as green and reusable catalysts to afford the corresponding bis(indolyl) methanes in excellent yields at room temperature under mild reaction conditions. © Springer Science+Business Media B.V. 2012.

Saeedi Heydari M.,Islamic Azad University at Tehran
International Journal of Refractory Metals and Hard Materials | Year: 2015

Boron carbide (B4C) with good properties such as superior hardness, low density, high melting point, high modulus of elasticity and chemical neutrality is considered an appropriate substance for many high-temperature applications. However, this material has found limited use due to its difficult sintering and its low fracture toughness value. Titanium diboride (TiB2) is a ceramic which has been successfully added to B4C as a secondary phase. Many of the researchers have shown that by adding TiB2 to B4C, a composite with high fracture toughness and flexural strength and great hardness can be achieved. The method of sintering is an effective parameter on the properties of B4C-TiB2 composites that consist of the possibility of production of large and complicated parts, the final cost of the produced pieces, speed of sintering, reproducibility, safety and reliability. This paper has attempted to investigate the effects of different sintering methods for ceramics on the physical and mechanical characteristics and the sintering ability of B4C-TiB2 nanocomposites. © 2015 Elsevier Ltd. All rights reserved.

Sadeghzadeh H.,Islamic Azad University at Tehran | Ehyaei M.A.,Islamic Azad University | Rosen M.A.,University of Ontario Institute of Technology
Energy Conversion and Management | Year: 2015

The use of genetic and particle swarm algorithms in the design of techno-economically optimum shell-and-tube heat exchangers is demonstrated. A cost function (including costs of the heat exchanger based on surface area and power consumption to overcome pressure drops) is the objective function, which is to be minimized. Selected decision variables include tube diameter, central baffles spacing and shell diameter. The Delaware method is used to calculate the heat transfer coefficient and the shell-side pressure drop. The accuracy and efficiency of the suggested algorithm and the Delaware method are investigated. A comparison of the results obtained by the two algorithms shows that results obtained with the particle swarm optimization method are superior to those obtained with the genetic algorithm method. By comparing these results with those from various references employing the Kern method and other algorithms, it is shown that the Delaware method accompanied by genetic and particle swarm algorithms achieves more optimum results, based on assessments for two case studies. © 2015 Elsevier Ltd. All rights reserved.

Rafiee M.,Islamic Azad University of Arak | Mohammadi M.,Isfahan University of Technology | Sobhani Aragh B.,Islamic Azad University of Arak | Yaghoobi H.,Islamic Azad University at Tehran
Composite Structures | Year: 2013

Nonlinear vibration and dynamic response of simply supported piezoelectric functionally graded material (FGM) shells under combined electrical, thermal, mechanical and aerodynamic loading are studied in this paper. The material properties of the shell are assumed to be graded in the thickness direction according to a simple power-law distribution in terms of volume fractions of the constituents. The third-order piston theory is employed to evaluate the aerodynamic pressure. The governing equations are derived using improved Donnell shell theory ignoring the shallowness of cylindrical shells and kinematic nonlinearity and the physical neutral surface concept are taken into consideration. The Galerkin method, Volmir's assumption and the multiple time scales perturbation methods are used for the nonlinear dynamical analysis of shells to give the expression of natural frequencies, the nonlinear dynamic responses and the primary resonance phenomena. The influences of the shell geometry and piezoelectric thickness, temperature change, external constant electric voltage and aerodynamic loads on the nonlinear dynamic behavior of the piezoelectric functionally graded shells through a comprehensive parametric study are discussed in details. © 2013 Elsevier Ltd.

Rafiee M.,Islamic Azad University of Arak | Mohammadi M.,Isfahan University of Technology | Sobhani Aragh B.,Islamic Azad University of Arak | Yaghoobi H.,Islamic Azad University at Tehran
Composite Structures | Year: 2013

Nonlinear vibration and dynamic response of the simply supported piezoelectric functionally graded material (FGM) shells under combined electrical, thermal, mechanical and aerodynamic loading are studied in this paper. The material properties of the shell are assumed to be graded in the thickness direction according to a simple power-law distribution in terms of volume fractions of the constituents. The third-order piston theory is employed to evaluate the aerodynamic pressure. The governing equations are derived using improved Donnell shell theory ignoring the shallowness of cylindrical shells and kinematic nonlinearity and the physical neutral surface concept are taken into consideration. The Galerkin method, Volmir's assumption and the multiple time scales perturbation methods are used for the nonlinear dynamical analysis of shells to give the expression of natural frequencies, the nonlinear dynamic responses and the primary resonance phenomena. The influences of the shell geometry and piezoelectric thickness, temperature change, external constant electric voltage and aerodynamic loads on the nonlinear dynamic behavior of the piezoelectric functionally graded shells through a comprehensive parametric study are discussed in details. © 2013 Elsevier Ltd.

Mokhtarian M.N.,Islamic Azad University at Tehran | Hadi-Vencheh A.,Islamic Azad University at Khorasgan
Applied Soft Computing Journal | Year: 2012

The selection of a facility location among alternative locations is a multiple criteria decision making (MCDM) problem including both quantitative and qualitative criteria. In more cases, in real word situations, determining the exact values for MCDM problems and especially for facility location selection problems is difficult or impossible. So, the values of alternatives with respect to the criteria or/and the values of criteria weights, are considered as fuzzy values (fuzzy numbers) so that the conventional crisp approaches for solving facility location selection problems and other MCDM problems tend to be less effective for dealing with the imprecise or vagueness nature of the linguistic assessments. In such conditions, the fuzzy MCDM methods are applied for solving facility location selection problem and other fuzzy MCDM problems. In this paper, we propose a new fuzzy TOPSIS method based on left and right scores for solving fuzzy MCDM problems. We apply the proposed method for solving three numerical examples. The first two numerical examples are proposed for the purpose of comparison. The third numerical example is a real application in which the selection is an industrial zone among several industrial zones for constructing dairy products factory. As a result, we found that the proposed method is practical for solving facility location selection problem and other fuzzy MCDM problems. Moreover, it seems that the proposed fuzzy TOPSIS method is flexible and easy to use and has acceptable accurate. © 2012 Elsevier B.V.

Rad A.G.,Islamic Azad University at Roudehen | Abbasi H.,Islamic Azad University at Tehran | Afzali M.H.,Islamic Azad University at Tehran
Physics Procedia | Year: 2011

In this paper we report the synthesis of gold nanoparticles during laser ablation of a metal gold plate in distilled water. The experiments were performed with a first harmonic (1064 nm, 6 ns, 10 Hz) output of a Nd:YAG laser varying the operative fluency between 5 Jcm -2 and 15 Jcm -2. The results indicate that gold nanoparticles are synthesized at room temperature.In this paper we give an overview of the properties of gold relevant to its potential application in molecular-scale devices absorption spectroscopy and Transmission Electron Microscopy (TEM) were employed to determine the optical properties and size of gold nanoparticles. And novel applications of gold nanoparticles have been studied in various fields. © 2011 Published by Elsevier B.V.

Kamyab G.-R.,Islamic Azad University at Tehran | Fotuhi-Firuzabad M.,Sharif University of Technology | Rashidinejad M.,Shahid Bahonar University of Kerman
International Journal of Electrical Power and Energy Systems | Year: 2014

This paper presents a particle swarm optimization (PSO) based approach to solve the multi-stage transmission expansion planning problem in a competitive pool-based electricity market. It is a large-scale non-linear combinatorial problem. We have considered some aspects in our modeling including a multi-year time horizon, a number of scenarios based on the future demands of system, investment and operating costs, the N - 1 reliability criterion, and the continuous non-linear functions of market-driven generator offers and demand bids. Also the optimal expansion plan to maximize the cumulative social welfare among the multi-year horizon is searched. Our proposed PSO based approach, namely modified PSO (MPSO), uses a diversity controlled PSO to overcome the problem of premature convergence in basic PSO (BPSO) plus an initial high diversity swarm to cover the search space efficiently. The MPSO model is applied to the Garver six-bus system and to the IEEE 24-bus test system and compared to the BPSO model and a genetic algorithm based model. © 2013 Elsevier Ltd. All rights reserved.

Ghoranneviss M.,Islamic Azad University at Tehran | Shahidi S.,Islamic Azad University of Arak
Journal of Fusion Energy | Year: 2014

In this research work, cotton fabrics were pretreated with low temperature plasma (LTP) and then inoculated in various metallic salts and flame retardancy of cotton fabric was investigated. More polar functional groups were present on the substrate surface after LTP pretreatment. Titanium dioxide (TiO 2), zinc sulfate (ZnSO4), lead (II) acetate [Pb(C 2H3O2)2], aluminium sulfate [Al 2(SO4)3] and silver nitrate (AgNo3) were used as metallic salts. The flame retardancy of the samples was characterized by limiting oxygen index (LOI) and char yield. Good flame retardant activity for Al2(SO4)3 and AgNo 3 treated fabrics were achieved, however, the effect of TiO 2 and ZnSO4 on flame retardany of cotton fabrics was moderate. It was concluded that, nitrogen plasma pretreatment, improve the flame retardant properties of cotton samples. The plasma treated and Aluminium sulfate loaded cotton fabric sample has a LOI value of 23.3. It shows that, nitrogen plasma pretreatment has synergistic effect on metallic salts for improving the flame retardant properties of cotton samples. In this research work, the dyeability of samples after loading with metallic salts was investigated. Also effect of dyeing on flame retardant properties was studied. The cotton fabrics treated with metallic salts demonstrate an excellent dyeability property. Color intensities of the dyed fabrics were measured by using a UV VIS-NIR Reflective Spectrophotometer, over the range of 200-800 nm. The results showed that, by using silver nitrate as mordant before dying, the relative color strength (K/S values) of the dyed fabrics has been increased. Water drop test and wash fastness determination (ISO 105-C01) were conducted. Also Electronic Crock meter/Rubbing Fastness Tester AATCC 8 was used to determine the color fastness of textiles. We also concluded that dyeing the plasma treated and inoculated cotton fabrics do not have any negative effect on flame retardancy of cotton fabric. © 2013 Springer Science+Business Media New York.

Shahidi S.,Islamic Azad University of Arak | Ghoranneviss M.,Islamic Azad University at Tehran
Journal of Fusion Energy | Year: 2014

In this research work the effect of plasma treatment with nitrogen gas followed by nanoclay treatment on flame retardancy of cotton fabrics is studied. The flame retardancy of the samples was characterized by limiting oxygen index and the char yield. The thermal decomposition behaviors, the chemical structures and morphologies of the fabrics were investigated using thermo gravimetric analysis, Fourier transform infrared and scanning electron microscopy, respectively, and a possible flame retardant mechanism is discussed. It shows that, nitrogen plasma pretreatment has synergistic effect on nanoclay for improving the flame retardant properties of cotton samples. © 2013 Springer Science+Business Media New York.

Gandomi A.H.,Islamic Azad University at Tehran | Yang X.-S.,National Physical Laboratory United Kingdom | Talatahari S.,University of Tabriz
Computers and Mathematics with Applications | Year: 2012

The performance of an optimization tool is largely determined by the efficiency of the search algorithm used in the process. The fundamental nature of a search algorithm will essentially determine its search efficiency and thus the types of problems it can solve. Modern metaheuristic algorithms are generally more suitable for global optimization. This paper carries out extensive global optimization of unconstrained and constrained problems using the recently developed eagle strategy by Yang and Deb in combination with the efficient differential evolution. After a detailed formulation and explanation of its implementation, the proposed algorithm is first verified using twenty unconstrained optimization problems or benchmarks. For the validation against constrained problems, this algorithm is subsequently applied to thirteen classical benchmarks and three benchmark engineering problems reported in the engineering literature. The performance of the proposed algorithm is further compared with various, state-of-the-art algorithms in the area. The optimal solutions obtained in this study are better than the best solutions obtained by the existing methods. The unique search features used in the proposed algorithm are analyzed, and their implications for future research are also discussed in detail. © 2011 Elsevier Ltd. All rights reserved.

Pazand K.,Islamic Azad University at Tehran | Sarvestani J.F.,Shahid Bahonar University of Kerman
Environmental Earth Sciences | Year: 2013

Groundwater is the most important source of water supply in Iran and understanding the geochemical evolution of groundwater is important for sustainable development of the water resources in Tabas area. A total of 29 samples of groundwater in Tabas area have been analyzed for ions and major elements. Groundwater of the study area is characterized by the dominance of Na-Cl water type. Groundwater was generally acidic to high alkaline with pH ranging from 5.42 to 10.75. The TDS as a function of mineralization characteristics of the groundwater ranged from 479 to 10,957 mg/l, with a mean value of 2,759 mg/l. The Ca2+, Mg2+, SO4 2- and HCO3 - were mainly derived from the dissolution of calcite, dolomite and gypsum. The Cu, Pb and Zn ions are not mobile in recent pH-Eh, but these conditions controlled dissolved Se, V and Mo in groundwater. The As is released in groundwater as a result of the weathering of sulfide minerals like arsenopyrite. © 2012 Springer-Verlag Berlin Heidelberg.

Shahidi S.,Islamic Azad University of Arak | Ghoranneviss M.,Islamic Azad University at Tehran
Plasma Science and Technology | Year: 2013

Microbial contamination induces surface deformations and strength degradation of cotton fabrics by invading deeply into the fibers. In this study, the sterilization effects of low pressure plasmas on bacteria-inoculated cotton fabrics were investigated. Oxygen plasma treatment completely sterilized the cotton fabrics inoculated with various concentrations of staphylococcus aureus. Also, the influence of plasma treatment on physical properties of fabrics was examined. It was found that the plasma treatment did not affect ultimate tensile strength and surface morphology of the fabrics because it took advantage of relatively low plasma temperature.

Moosazadeh M.,Islamic Azad University at Tehran | Abbosh A.M.,University of Queensland | Esmati Z.,Islamic Azad University at Urmia
IET Microwaves, Antennas and Propagation | Year: 2012

A planar antenna with ultrawideband (UWB) performance and dual band-notched characteristics is proposed. The main features of the antenna are the compact dimensions and omnidirectional radiation across the whole band of operation. The radiator of the antenna is a slotted square patch. The ground plane is located at the bottom layer, which also includes a Φ-shaped conductor-backed plane used to widen the impedance bandwidth. Dual band-notched characteristics are achieved by an inverted T-shaped strip inside the slotted radiator and a pair of mirror inverted L-shaped slots at the two sides of the radiator. The measured results of the manufactured (12×16 mm) antenna on 1.6 mm FR4 substrate show that the antenna operates with voltage standing wave ratio (VSWR) less than two over the frequency band from 2.5 to 10.8 GHz. That wideband is featured by the existence of two notched bands (3.23-4.3 and 5-6 GHz), where the VSWR is more than nine, aimed at suppressing any interference from IEEE802.16 WiMAX (3.3-3.6 GHz), C-band systems (3.7-4.2 GHz) and IEEE802.11a WLAN (5.15-5.825 GHz). The antenna has an omnidirectional radiation across the whole UWB as validated by the measured radiation pattern and gain. © 2012 The Institution of Engineering and Technology.

Salahshour S.,Islamic Azad University at Mobarakeh | Allahviranloo T.,Islamic Azad University at Tehran
Soft Computing | Year: 2013

A natural way to model dynamic systems under uncertainty is to use fuzzy initial value problems (FIVPs) and related uncertain systems. In this paper, we express the fuzzy Laplace transform and then some of its well-known properties are investigated. In addition, an existence theorem is given for fuzzy-valued function which possess the fuzzy Laplace transform. Consequently, we investigate the solutions of FIVPs and the solutions in state-space description of fuzzy linear continuous-time systems under generalized H-differentiability as two new applications of fuzzy Laplace transforms. Finally, some examples are given to show the efficiency of the proposed method. © 2012 Springer-Verlag.

Samariha A.,Islamic Azad University at Tehran | Khakifirooz A.,Scientific board of Institute of Standards and Industrial Research of Research Center
BioResources | Year: 2011

The NSSC pulping process was investigated to produce pulp from bagasse for corrugating board manufacture. The chemical contents including cellulose, lignin, ash, and extractives soluble in alcohol-acetone measured 55.75, 20.5, 1.85, and 3.25, respectively. The average fiber length, fiber diameter, lumen width, and cell wall thickness of bagasse were 1.59 mm, 20.96, 9.72, and 5.64 μm, respectively. The optimum conditions, with a yield of 74.95%, were achieved using 20 percent chemicals on the basis of sodium oxide, cooking temperature of 170°C, and cooking time of 30 minutes. Pulp was refined to freeness 345 and 433 mL CSF according to Canadian standards. 127 g m -2 handsheets from both pulps were made and strength properties measured. Statistical analysis of results indicated that paper derived from freeness 345 and 433 mL CSF had better strength properties in all indices in comparison with NSSC pulp from hardwoods produced at Mazandaran Pulp and Paper factory, Iran.

Allahviranloo T.,Islamic Azad University at Tehran | Salahshour S.,Islamic Azad University at Mobarakeh
Soft Computing | Year: 2011

In this paper, we study the numerical method for solving hybrid fuzzy differential using Euler method under generalized Hukuhara differentiability. To this end, we determine the Euler method for both cases of H-differentiability. Also, the convergence of the proposed method is studied and the characteristic theorem is given for both cases. Finally, some numerical examples are given to illustrate the efficiency of the proposed method under generalized Hukuhara differentiability instead of suing Hukuhara differentiability. © 2010 Springer-Verlag.

Nouri J.,Islamic Azad University at Tehran | Nouri N.,Islamic Azad University at Tehran | Moeeni M.,Montclair State University
International Journal of Environmental Science and Technology | Year: 2012

In this study, environmental impacts of industrial waste disposal of used lubricating oils and sulphur wastes scenarios have been investigated and modeled. The life-cycle assessment methodology was selected among the environmental impact assessment methods. In this method environmental issues and burdens were quantitated in order to facilitate the comparison. In this regard, options with the least adverse impacts were suggested. Functional unit of the study has also been defined as amount of used lubricating oils and sulphur wastes in terms of kilograms based on capacity of transitional barrel. Accordingly, the system boundaries were selected for life cycle of the wastes produced in sulphur unit of Tehran Oil Refinery. Since the main disposal method applied in Tehran Oil Refinery was transference to the municipal landfill, two incineration and landfilling scenarios were modeled for used lubricating oils and sulphur wastes by means of Simapro-7.1 software. Then, the outputs of these scenarios were compared in terms of the least environmental impacts by EDIP 2003 and Ecoindicator 99 methods. Finally, incineration scenarios were recommended as the most efficient ones. © CEERS, IAU 2012.

Poursamad Bonab A.,Islamic Azad University at Tehran | Hosseini Hashemi B.,International Institute of Earthquake Engineering and Seismology
Journal of Constructional Steel Research | Year: 2012

In this research, 18 laced built-up columns with various geometric specifications were analyzed under different levels of axial load and cyclic lateral load using the finite element method. This research was performed as a continuation of the experimental investigation on the cyclic behavior of the laced columns. This study evaluated the effects of column's geometrical parameters and various levels of axial loads on the cyclic behavior of laced columns. A compression of the results shows that there is generally good agreement between the experimental and analytical results. The analytical results showed that as the axial load increased, the ductility of the laced columns decreased significantly. Further, at high levels of axial load (i.e., loads higher than 50% of the columns' compressive capacity), ductility was very poor. It was found that during lateral loading there is a bending moment in addition to the axial force in the lacing bars and the main chords, which affects the columns' behavior. The slenderness ratio of the main chords between the connecters and the shape of the cross-section of the lacing bars (i.e., bending strength of the lacing bars) are the main geometrical parameters affecting the laced columns' ductility. © 2012 Elsevier Ltd.

Behzadnia A.,Amirkabir University of Technology | Montazer M.,Islamic Azad University at Tehran | Rad M.M.,Shahid Beheshti University of Medical Sciences
Ultrasonics Sonochemistry | Year: 2015

In this study, N-doped ZnO/TiO2 core-shell nanocomposite was successfully sonosynthesized and sonofabricated on wool fabric through a facile one-step method under ambient pressure and low temperature (75-80 °C) as a novel photo-catalyst nanocomposite on textile material. The differences between crystalline phase transformation of conventional and ultrasound synthesized N-ZnO/TiO2 has been compared. The influence of different zinc acetate and titanium isopropoxide precursors in the formation of nanocomposite was studied and optimized through response surface methodology. The photocatalytic activity of the sonofabricated catalyst on the wool fabric surface was evaluated through decomposition of Methylene Blue as a model compound under sunlight irradiation. Also, N-doped ZnO/TiO2 nanocomposite sonosynthesized on wool fabric led to photo bleaching of wool fabric due to decomposition of the naturally occurred pigments under daylight irradiation. Further, yellowness index, antibacterial and antifungal activity against Escherichia coli, Staphylococcus aureus and Candida albicans, cell viability, char residual, alkali solubility, mechanical properties and water drop absorption time on the treated wool fabrics were evaluated. Also, the acid solubility of the synthesized nanopowder obtained from sonobath after treatment was characterized in acetic acid indicating higher acid resistance on N-doped ZnO/TiO2 nanocomposite. © 2015 Elsevier B.V. All rights reserved.

Sadeghi S.,Qazvin University of Medical Sciences | Sadeghi S.,Islamic Azad University at Tehran | Reisi Z.,Shahid Beheshti University of Medical Sciences | Azhdari-Zarmehri H.,Qazvin University of Medical Sciences | Haghparast A.,Shahid Beheshti University of Medical Sciences
Pharmacology Biochemistry and Behavior | Year: 2013

Previous studies have demonstrated that chemical stimulation of the lateral hypothalamus (LH) with carbachol has an important role in the induction of antinociception in tail-flick test as a model of acute pain. In this study, we tried to evaluate the involvement of orexin-1 receptors in the ventral tegmental area (VTA) and the nucleus accumbens (NAc) on antinociceptive responses induced by LH stimulation in rats. One hundred twenty adult male albino Wistar rats weighing 200-250 g were unilaterally implanted with two separate cannulae into the LH, and VTA or NAc. Antinociceptive effects for two doses of intra-LH carbachol (125 and 250 nmol/0.5 μl saline), as a cholinergic agonist, were evaluated in this study. In another set of experiments, animals received intra-VTA or -NAc infusions of SB334867 as a selective orexin-A receptor antagonist (0.3, 1, 3 and 10 nmol/rat), just 5 min before microinjection of an effective dose of carbachol into the LH. In the tail-flick test, antinociceptive responses of drugs were obtained by tail-flick analgesiometer and represented as maximal possible effects (%MPE) at 5, 15, 30, 45 and 60 min after their administrations. The results showed that unilateral intra-LH administration of carbachol (125 and 250 nmol/rat) induced antinociception in rats (P < 0.01). There were no significant differences between the antinociceptive effects of these two doses. In the second part of our study, intra-VTA and intra-accumbal administrations of different doses of SB334867, 5 min before microinjection of carbachol, could dose-dependently prevent the development of LH stimulation-induced antinociception in rats. However, this effect was less in the NAc. It is supposed that the orexinergic projections from the LH to the VTA and NAc are direct/indirectly involved in the antinociception induced by LH chemical stimulation, and orexin-1 receptors in the ventral tegmental area have a more substantial role in this phenomenon. © 2013 Elsevier Inc.

Hamzehloo H.,International Institute of Earthquake Engineering and Seismology | Mahood M.,Islamic Azad University at Tehran
Bulletin of the Seismological Society of America | Year: 2012

Predictive attenuation relationships have been developed for peak ground acceleration and spectral coordinates based on observed and simulated records for East Central Iran. First, the predictive relationships are derived based on observed records. The observed data set, which was considered, includes a total of 258 records from 109 earthquakes with a magnitude range of 5.0-7.4 on rock site. Then a suite of ground motions has been simulated for a range of magnitude and distances based on the stochastic finite fault ground-motion model. The theoretical-empirical attenuation relationship, which has been developed for the horizontal component of peak ground acceleration and spectral acceleration, is applicable to earthquakes of Mw 5.0-7.4 at a distance up to 100 km.

Azarmina M.,Shahid Beheshti University of Medical Sciences | Azarmina H.,Islamic Azad University at Tehran
Journal of Ophthalmic and Vision Research | Year: 2013

The sixth cranial nerve runs a long course from the brainstem to the lateral rectus muscle. Based on the location of an abnormality, other neurologic structures may be involved with the pathology related to this nerve. Sixth nerve palsy is frequently due to a benign process with full recovery within weeks, yet caution is warranted as it may portend a serious neurologic process. Hence, early diagnosis is often critical for some conditions that present with sixth nerve palsy. This article outlines a simple clinical approach to sixth nerve palsy based on its anatomy.

Zoghi A.,Islamic Azad University at Tehran | Khosravi-Darani K.,Shahid Beheshti University of Medical Sciences | Sohrabvandi S.,Shahid Beheshti University of Medical Sciences
Mini-Reviews in Medicinal Chemistry | Year: 2014

Removal of toxic metals and toxins using microbial biomass has been introduced as an inexpensive, new promising method on top of conventional methods for decontamination of food, raw material and concentrated. In this article the potential application of lactic acid bacteria and yeasts as the most familiar probiotics to eliminate, inactivate or reduce bioavailability of contamination in foods and feed has been reviewed. After fast glance to beneficial health effects and preservative properties of lactic acid bacteria, the mechanisms which explain antibacterial and antifungal efficiency as well as their antifungal metabolites are mentioned. Then the article has been focused on potential application of single strain or combination of lactic acid bacteria for removal of heavy metals (copper, lead, cadmium, chromium, arsenic), cyanotoxins (microcystin-LR, -RR, -LF) and mycotoxins (aflatoxin B1, B2, B2a, M1, M2, G1, G2, patulin, ochratoxin A, deoxynivalenol, fumonisin B1 and B2, 3-acetyldeoxynivalenol, deoxynivalenol, fusarenon, nivalenol, diacetoxyscirpenol, HT-2 and T-2 toxin, zearalenone and its derivative, etc) from aqueous solutions in vitro. Wherever possible the mechanism of decontamination and the factors influencing yield of removal are discussed. Some factors which can facilitate metal removal capacity of lactic acid bacteria including the strains, surface charge, pH, temperature, presence of other cations are introduced. The cell wall structure of lactic acid bacteria and yeasts are also introduced for further explanation of mechanism of action in complex binding of probiotic to contaminants and strength of mycotoxin-bacterium interaction. © 2014 Bentham Science Publishers.

Husseinzadeh Kashan A.,Islamic Azad University at Tehran | Rezaee B.,Bojnord University | Karimiyan S.,International Institute of Earthquake Engineering and Seismology
Pattern Recognition | Year: 2013

Fuzzy data clustering plays an important role in practical use and has become a prerequisite step for decision-making in fuzzy environment. In this paper we propose a new algorithm, called FuzzyGES for unsupervised fuzzy clustering based on adaptation of the recently proposed Grouping Evolution Strategy (GES). To adapt GES for fuzzy clustering we devise a fuzzy counterpart of the grouping mutation operator typically used in GES, and employ it in a two phase procedure to generate a new clustering solution. Unlike conventional clustering algorithms which should get the number of clusters as an input, FuzzyGES tries to determine the true number of clusters as well as providing the optimal cluster centroids after several iterations. The proposed approach is validated through using several data sets and results are compared with those of fuzzy c-means algorithm, particle swarm optimization algorithm (PSO), differential evolution (DE) and league championship algorithm (LCA). We also investigate the performance of FuzzyGES through using different cluster validity indices. Our results indicate that FuzzyGES is fast and provides acceptable results in terms of both determining the correct number of clusters and the accurate cluster centroids. © 2012 Elsevier Ltd.

Mehrjoo M.,Islamic Azad University at Tehran | Khaji N.,Tarbiat Modares University | Ghafory-Ashtiany M.,International Institute of Earthquake Engineering and Seismology
Applied Soft Computing Journal | Year: 2013

In this paper, a crack identification approach is presented for detecting crack depth and location in beamlike structures. For this purpose, a new beam element with a single transverse edge crack, in arbitrary position of beam element with any depth, is developed. The crack is not physically modeled within the element, but its effect on the local flexibility of the element is considered by the modification of the element stiffness as a function of crack's depth and position. The development is based on a simplified model, where each crack is substituted by a corresponding linear rotational spring, connecting two adjacent elastic parts. The localized spring may be represented based on linear fracture mechanics theory. The components of the stiffness matrix for the cracked element are derived using the conjugate beam concept and Betti's theorem, and finally represented in closed-form expressions. The proposed beam element is efficiently employed for solving forward problem (i.e., to gain accurate natural frequencies of beam-like structures knowing the cracks' characteristics). To validate the proposed element, results obtained by new element are compared with two-dimensional (2D) finite element results as well as available experimental measurements. Moreover, by knowing the natural frequencies, an inverse problem is established in which the cracks location and depth are identified. In the inverse approach, an optimization problem based on the new beam element and genetic algorithms (GAs) is solved to search the solution. The proposed approach is verified through various examples on cracked beams with different damage scenarios. It is shown that the present algorithm is able to identify various crack configurations in a cracked beam. © 2012 Elsevier B.V. All rights reserved.

Yas M.H.,Razi University | Pourasghar A.,Islamic Azad University at Tehran | Kamarian S.,Islamic Azad University at Kermānshāh | Heshmatia M.,Razi University | Heshmatia M.,Kermanshah University of Technology
Materials and Design | Year: 2013

This work deals with a study of the vibrational properties of functionally graded nanocomposite cylindrical panels reinforced by single-walled carbon nanotubes (SWCNTs) based on the three-dimensional theory of elasticity. The carbon nanotube reinforced (CNTRC) cylindrical panel have smooth variation of carbon nanotube (CNT) fraction in the radial direction and the material properties are estimated by the extended rule of mixture. Symmetric and asymmetric volume fraction profiles are provided in this paper for comparison. Suitable displacement functions that identically satisfy the boundary conditions at the simply supported edges are used to reduce the equilibrium equations to a set of coupled ordinary differential equation with variable coefficients, which can be solved by a generalized differential quadrature (GDQ) method. The results show that the kind of distribution and volume fraction of CNT have a significant effect on normalized natural frequency. © 2013 Elsevier Ltd.

Ghaderian S.M.H.,Shahid Beheshti University of Medical Sciences | Akbarzadeh Najar R.,Shahid Beheshti University of Medical Sciences | Tabatabaei Panah A.S.,Islamic Azad University at Tehran
Coronary Artery Disease | Year: 2010

Objectives: Matrix metalloproteinases (MMPs) play an important role in early atherosclerosis, plaque rupture, extracellular matrix remodeling, and myocardial infarction (MI). MMP gene polymorphisms contribute to the risk of developing cardiovascular disease. We designed to investigate the association of acute MI (AMI) with a polymorphism in the human MMP-1, 2, 3, and 9 genes in Iranian patients with AMI. Methods: Genomic DNA of 400 enrolled patients with AMI and 200 controls was extracted from their blood samples. The -1607 1G/2G MMP-1, -1306 C/T MMP-2, -1171 5A/6A MMP-3, -1562 C/T MMP-9 polymorphisms were detected. Plasma levels of MMPs were analyzed. Results: There are significant differences in MMP-3 '5A' allele and genotype in the patients with AMI comparing with controls. However, no significant differences were observed in MMP-1, 2, and 9 allele frequencies between the patients and controls. Differences between plasma levels of MMPs were significant in the patients than in controls. There were statistically significant differences between plasma MMP-3 in carriers of 5A allele compared with 6A allele. MMP-9 plasma levels were significantly higher in the carriers of -1306 TT and -1306 CT than CC. However, there were no statistically significant association between genetic variation of MMP-1, 2, and 3 in the patients and their plasma levels. Conclusion: These data suggest that MMP genotyping such as genetic polymorphism in MMP-3 might be helpful in determining susceptibility to AMI in Iranian patients. In addition, susceptibility to AMI might be related to MMP-9 gene expression, which affects its plasma levels. Copyright © 2010 Lippincott Williams & Wilkins.

Panji M.,Islamic Azad University at Tehran | Kamalian M.,International Institute of Earthquake Engineering and Seismology | Asgari Marnani J.,Islamic Azad University at Tehran | Jafari M.K.,International Institute of Earthquake Engineering and Seismology
Geophysical Journal International | Year: 2013

In this paper, a half-plane time-domain boundary element method (BEM) was presented for analysing the 2-D scalar wave problems in a homogenous isotropic linear elastic medium. Using the existing transient full-plane fundamental solution and asking for the assistance of method of source image to satisfy the stress-free boundary conditions, first, a half-plane time-domain fundamental solution was obtained for displacement and traction fields. Then, the condensed closed-form of half-plane time-convoluted kernels were extracted analytically by applying the time-convolution integral on the determined half-plane fundamental solutions. After implementing the half-plane time-domain BEM in computer codes, its applicability and efficiency were verified and compared with those of the published works by analysing several practical examples. The studies showed that the proposed method had good agreement with the existing solutions. Compared to the full-plane time-domain BEM, half-plane time-domain BEM had more capability and better accuracy as well as much shorter run time. It is obvious that this method can be practically used to analyse the site response in substituting the old-style time-domain BEM formulation as well. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.

Gorji S.G.,Shahid Beheshti University of Medical Sciences | Gorji E.G.,Islamic Azad University at Tehran | Mohammadifar M.A.,Shahid Beheshti University of Medical Sciences
Food Hydrocolloids | Year: 2014

The formation of electrostatic complexes between sodium caseinate and gum tragacanth (. Astragalus gossypinus, A.g) as a function of pH (7.00-2.50), the biopolymer mixing ratio and the total biopolymer concentration was studied by spectrophotometric and light scattering measurements.This multi-methodological approach allowed us to demonstrate the critical structure-forming pHs associated with the formation of soluble and insoluble complexes for the sodium caseinate/A.g mixture. The phase transition of sodium caseinate/A.g complexed/coacervated system was explained by monitoring the absorbance profiles as a function of time.Particle size measurements revealed a progressive decrease in the complex/aggregate size while lowering the pH until reaching a minimum (pH 4) at which nanoparticles (70nm) formed.As the mixing ratio of protein to polysaccharide increased from 1:1 to 3:1, the critical pHs shifted towards higher pH values. Conversely, for a constant mixing ratio, higher levels of total concentration resulted in an increase in the maximum turbidity but had no meaningful effect on pHC (~5.89) and pHΦ1 (~4.00). © 2012 Elsevier Ltd.

Haghparast M.,Islamic Azad University at Tehran | Navi K.,Shahid Beheshti University
International Journal of Quantum Information | Year: 2011

Reversible logic is an emerging area of research, having applications in nanotechnology, low power CMOS design, quantum computing, and DNA computing. In this paper, two different parity-preserving reversible error coding and detection circuits are studied. First we propose two new reversible Hamming code generator circuits. One of them is parity-preserve. We also propose a new parity-preserving reversible Hamming code error detector circuit. The proposed parity-preserving reversible Hamming code generator (PPHCG) and error detector circuits provide single error correctiondouble error detection (SECDED). The designs are better than the existing counterparts in terms of quantum cost (QC), number of constant inputs, and number of garbage outputs. Then we propose parity-preserving reversible cyclic code encoder/decoder circuits for the first time. A parity-preserving reversible D flip-flop is also proposed. Equivalent quantum representation of two parity-preserving 4 * 4 reversible gates, IG, and PPHCG, are also proposed. We show for the first time that IG has a QC of only 7 and PPHCG has a QC of only 6. © 2011 World Scientific Publishing Company.

Yaghobi M.,Islamic Azad University at Āmol | Vanaie H.R.,Islamic Azad University at Tehran
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2011

We have investigated the electronic transport properties of molecular junctions constructed by C58X2 and C68X 2 (X=B,N) molecules that are coupled through carbon (C), boron (B) and nitrogen (N) atoms to two semi-infinite SWCNT electrodes. For the systems under investigation, we study effects of contacts and Coulomb interaction. Our results indicate that the presence of Coulomb interaction decreases current and shifts the NDR behavior to higher voltage. © 2011 Elsevier B.V.

Motahari-Nezhad M.,Islamic Azad University at Tehran
Petroleum Science and Technology | Year: 2016

ABSTRACT: A heavy oil gasification model that can predict the hydrogen yield has been developed for a high pressure circulating fluidized bed. The model is based on the Aspen Plus package, which is a professional software for simulation of thermal process. To illustrate the effects of the steam/fuel ratio and temperature, several conditions have been examined. The results show that the gasification temperature plays a major role in the process. As gasification temperature increases from 600 to 800°C, the production of hydrogen increases dramatically. The influence of steam/fuel ratio (0.50–0.80) is also considerable, but shows a constant rate at the higher steam/fuel. Simulation results were validated against experimental data available in the literature. © 2016 Taylor & Francis Group, LLC.

Mahdavian M.,Iran Institute for Color Science and Technology | Naderi R.,Islamic Azad University at Tehran
Corrosion Science | Year: 2011

The corrosion inhibitive effect of zinc acetate, zinc acetylacetonate and zinc gluconate on the mild steel immersed in 3.5% NaCl solution was evaluated by electrochemical impedance spectroscopy (EIS). The results revealed superiority of zinc gluconate whilst zinc acetate showed inferior corrosion inhibition. The surface of the samples exposed to the inhibited solutions was analyzed using XRD and SEM techniques. The pH measurement of the test solutions before and after corrosion, also before and after addition of Fe+2 and Fe+3 revealed that the superior inhibition of zinc gluconate is related to formation of insoluble corrosion products on the mild steel surface. © 2010 Elsevier Ltd.

Aghazadeh M.,Islamic Azad University at Tehran | Hosseinifard M.,Islamic Azad University at Tehran
Ceramics International | Year: 2013

Formation of the negatively charged colloidal zirconia species i.e. [ZrO]- at the cathode surface and low adhesion of the hydroxide deposit to its surface are common problems in the cathodic electrodeposition of zirconia. Deposition experiments with the direct current mode led to the total spallation of the deposit from the cathode surface and no deposit was obtained in practice. In order to minimize these problems, pulse current deposition was applied in the electrodeposition of ZrO2. The results showed that the control of the base electrogeneration and deposit formation on the cathode surface is achievable using the pulse current mode. The XRD analysis and SEM observations revealed that the crystal structure, phase content and surface morphology of the prepared zirconia powders are significantly affected by the variation of toff or ton/toff ratio. This work clearly showed that the pulse current electrodeposition can be introduced as an alternative route in the ZrO2 cathodic electrodeposition and preparation of its nanostructured powder. © 2012 Elsevier Ltd and Techna Group S.r.l.

Hajiraissi R.,Islamic Azad University at Bushehr | Parvinzadeh M.,Islamic Azad University at Tehran
Applied Surface Science | Year: 2011

Influence of nanosilica on surface properties of poly(butylene terephthalate) was investigated by the use of Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), contact angle measurement (CAM), scanning electron microscopy (SEM) and reflectance spectroscopy (RS). FTIR results indicated that surface groups of silica have some interfacial interactions and bonding with carboxyl or hydroxyl end groups of PBT chains. AFM and SEM figures of the resultant nanocomposites illustrated increased surface roughness compared to pure PBT. Optical properties of nanocomposite films were finally determined by the aid of reflectance spectrophotometer. © 2011 Elsevier B.V. All rights reserved.

Ahmadi A.,Islamic Azad University at Tehran | Ziarati P.,Islamic Azad University at Tehran
Oriental Journal of Chemistry | Year: 2015

Maize is one of the oldest and most productive popular grains and can be consumed as food at various developmental stages from baby corn to mature grain. The maize can be processed in different products at traditional level as well as industrial scale. Due to vast corn consumption by people in this research the concentration of histamine, some trace and essential mineral and also heavy metals has been determined in 120 samples of popular brands of canned and frozen sweet corn in 2014. These samples (60 of them were canned corn and the rest were frozen) were collected from different local markets of Tehran, Iran. For reliable, accurate and precise measurements, all canned and frozen samples had the same date of producing. Samples were randomly purchased for analysis and analyzed according to standardized international protocols by wet digestion method. Histamine content was determined by Capillary Electrophoresis while metals were determined by Atomic absorption spectrometer. The results obtained revealed that, the mean ranges of the elements analyzed in (μg.g-1) between the frozen and canned food are as follows: Ni (0.31-17.44), Zn (204.14-266.76), Cu (6.22-8.03), Ca (1611-8557), Mg (1063-1208), Fe (1.98-87.23), Sn (19.01-350.8) respectively. Some of the measured values found, not only relatively high in canned compared to frozen food samples, but also exceeds the international tolerance levels. Histamine content in 95% of samples was lower than maximum level set by WHO. According to variance analyses of data, there was a positive correlation between the storage time and heavy metal contents especially tin, zinc and iron and they were varied significantly (p -< 0.001) after 3 months of storage.The monitoring of mineral and heavy metals in frozen and canned food samples is vital important challenge to control and improve the food industry strategies.

Savaloni H.,University of Tehran | Habibi M.,Islamic Azad University at Tehran
Applied Surface Science | Year: 2011

Ni thin films of 250 nm thicknesses were coated on type 304 and 316 stainless steels and post N + ion implanted at 15 keV energy with a fluence of 5 × 10 17 N + cm -2 at different substrate temperatures. Surface nano-structure of the samples were analysed using X-ray diffraction (XRD), atomic force microscopy (AFM) before corrosion test and scanning electron microscopy (SEM) after corrosion test. Corrosion behaviour of the samples in 1.0 M H 2SO 4 solution was investigated by means of potentiodynamic technique. Nano-structure and crystallography of the films showed the development of Ni 3N(1 1 1) and Ni 4N(2 0 0) orientations with a minimum surface roughness and grain size at 400 K substrate temperature. The highest corrosion resistance with a corrosion current of 0.01 μA cm -2 (for SS(316)) and 0.56 μA cm -2 (for SS(304)) was achieved in case of samples which were N + ion implanted at 400 K. Results for both types of stainless steels showed good agreement and the better performance of SS(316) was attributed to the 2% molybdenum contents in the alloy composition of this type of stainless steel, which enhances the effectiveness of nitrogen in retarding the corrosion process. © 2011 Elsevier B.V. All rights reserved.

Ardestani M.,Islamic Azad University at Tehran
Materiali in Tehnologije | Year: 2016

In this research, the chemical synthesis and densification behavior of Ag/ZnO metal-matrix composites were investigated. The initial precipitates were obtained by adding ammonium carbonate solution to silver and zinc nitrate solutions. The precipitates consisted of silver and zinc carbonates. The thermal behavior of the precipitates was studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The TGA curve showed three distinguishable mass-loss stages, related to the evaporation of physically adsorbed water and also the decomposition of silver and zinc carbonates into silver and zinc oxides, respectively. The mass-loss stages were associated with three endothermic reactions. According to the thermal-analysis results, the precipitates were calcined at 600 °C. The compressibility behavior of the synthesized Ag/ZnO powders was evaluated using the Heckel, Panelli and Ge models. The compaction data of the powders was best fitted to the Heckel equation. The synthesized powders were sintered at 930 °C. The results showed that by increasing the cold-compaction magnitude prior to sintering, the sinterability of the powders was enhanced. The microstructural evaluation of the synthesized composites carried out with a scanning electron microscope (SEM) confirmed a fine and homogenous dispersion of ZnO within the silver matrix.

Saidi P.,Islamic Azad University at Tehran
Journal of applied clinical medical physics / American College of Medical Physics | Year: 2011

This work presents experimental dosimetry results for a new 103Pd brachytherapy seed, in accordance with the AAPM TG-43U1 recommendation that all new low-energy interstitial brachytherapy seeds should undergo one Monte Carlo (MC) and at least one experimental dosimetry characterization. Measurements were performed using TLD-GR200A circular chip dosimeters using standard methods employing thermoluminescent dosimeters in a Perspex phantom. The Monte Carlo N-particle (MCNP) code, version 5 was used to evaluate the dose-rate distributions around this model 103Pd source in water and Perspex phantoms. The consensus value for dose-rate constant of the IR06-103Pd source was found equal to 0.690 cGy·h(-1)·U(-1). The anisotropy function, F(r, θ), and the radial dose function, g(L)(r), of the seed were measured in Perspex phantom and calculated in both Perspex and liquid water phantom. The measured values were also found in good agreement with corresponding MC calculations.

Ganji M.D.,Islamic Azad University at Tehran
Physics of the Solid State | Year: 2016

We perform detailed calculations for the interaction of molecular hydrogen with C20isomers in the framework of density functional theory method. The adsorption of H2 outside the C20-e isomer with parallel orientation with respect to the plane of the hexagon is found to be the most stable adsorption configuration. Thus this might have potential for the hydrogen storing. We have also investigated the number and the position of adsorption sites in the pentagon for the parallel configurations of the H2/C20 systems. We find two stable configurations of the molecule for the C20-bowl isomer that have a small difference in energy. Thus, surprisingly, despite their apparent simplicity these H2/C20-bowl systems are shown to exhibit the flip-flop motion by a small current pulse. Hence, it might be a candidate for multi-states monomolecular device. Convenient experimental techniques such as field emission microscopy are proposed to test these predictions. © 2016, Pleiades Publishing, Ltd.

Aref A.,Islamic Azad University at Tehran
Life Science Journal | Year: 2011

Education and learning are widely recognized as essential to processes of development and poverty reduction. In many developing countries, issues of educational access, equity, and quality have been identified as prerequisites to the achievement of development goals. The objective of this study is, through reviewing the available evidences and analyses in the role of education in rural poverty reduction, to identify weaknesses pertinent to basic education achieving poverty reduction and to come out with some conclusions that can be taken into consideration in planning successful basic education for poverty reduction. The findings through focus group groups indicated that there are some rural structural barriers in educational system on rural poverty reduction.

Esmaeili A.,Islamic Azad University at Tehran
Chemical Engineering Transactions | Year: 2012

Carbon dioxide (CO2) is emitted in a number of ways; it is spread naturally either through the carbon cycle or human activities like the burning of fossil fuels. One of most dominant pre-combustion methods for CO 2 sequestration is using solvent-based process in order to capture this gas from flue gas and then either store it in Earth layers or use in other industries. There has been a climb in carbon dioxide concentrations in the atmosphere of about 280 ppm in 1850 to 364 ppm in 1998. In recent study, sequestration methods of CO2 and also its absorption by Amine and Methanol solvents is investigated and related process is simulated by Aspen HYSYS (ver.2006) simulator, both models are done in two 10 and 15 stages columns while sequestration by Methanol consumes more solvent compared with using MEA even though the former is more economical than the latter. Copyright © 2012, AIDIC Servizi S.r.l.

Pourfakhar E.,Islamic Azad University at Dezful | Rahmani A.M.,Islamic Azad University at Tehran
Computer Communications | Year: 2010

In recent years wireless mesh networks have been deployed and grown in popularity in many metropolitan areas. The deployment of such networks has allowed clients to gain access to publicly available broadband networks. The lack of standards and support for multicasting over wireless mesh networks makes this area very challenging as well as providing much scope for improvement. For first time in this paper, we use CMAC neural network model to predict route or node disconnection probability and to control congestion and losses specifically in the gateways. This prediction leads to recover the network before fault occurrence. In this paper, we propose a new QoS multicast routing framework for WMNs to solve the problem of load balancing and to enhance the QoS in multicast communication among Internet hosts and Mesh hosts dynamically. We also present an optimized hybrid multicast protocol based on this framework called HMFPM provisioning problems in the Next-Generation IEEE 802.11 s. The proposed protocol combines Proactive and Reactive multicast routing to eliminate unnecessary delays and also minimize control overhead in setting up routes amongst the backbone mesh routers. It also supports multiple gateways for the gateway balancing and routing based on CMAC prediction in each node to have the routes with least miss ratio. © 2010 Elsevier B.V. All rights reserved.

Hatami-Marbini A.,Islamic Azad University at South Tehran | Saati S.,Islamic Azad University at Tehran | Tavana M.,Philadelphia University
Applied Soft Computing Journal | Year: 2010

Data envelopment analysis (DEA) is a widely used mathematical programming approach for evaluating the relative efficiency of decision making units (DMUs) in organizations. Crisp input and output data are fundamentally indispensable in traditional DEA evaluation process. However, the input and output data in real-world problems are often imprecise or ambiguous. In this study, we present a four-phase fuzzy DEA framework based on the theory of displaced ideal. Two hypothetical DMUs called the ideal and nadir DMUs are constructed and used as reference points to evaluate a set of information technology (IT) investment strategies based on their Euclidean distance from these reference points. The best relative efficiency of the fuzzy ideal DMU and the worst relative efficiency of the fuzzy nadir DMU are determined and combined to rank the DMUs. A numerical example is presented to demonstrate the applicability of the proposed framework and exhibit the efficacy of the procedures and algorithms. © 2009 Elsevier B.V. All rights reserved.

Khadem S.A.,Islamic Azad University at Tehran | Nategh S.,Islamic Azad University at Tehran | Yoozbashizadeh H.,Islamic Azad University at Tehran
Journal of Alloys and Compounds | Year: 2011

Al-5 vol.%SiC nanocomposite powder is produced by using attrition milling in this investigation. The particle size distribution has been determined based on the standard deviation and the coefficient of variation. The results show that the addition of hard SiC particles accelerates the milling process, leading to faster work hardening rate and fracture of the aluminum matrix. Furthermore, Al becomes smaller crystallite size during ball milling of Al powder in the presence of SiC particles. Finally, the scanning electron microscopy (SEM) analysis and the X-ray diffraction (XRD) experiments are used to investigate the effect of milling time on the structural changes of Al-5 vol.%SiC nanocomposite and pure aluminum powder. © 2010 Elsevier B.V. All rights reserved.

Mirjalili M.,Islamic Azad University at Yazd | Nazarpoor K.,Islamic Azad University at Yazd | Karimi L.,Islamic Azad University at Tehran
Journal of Cleaner Production | Year: 2011

Since the last decade, the application of natural dyes on textile materials is gaining popularity all over the world, possibly because of increasing awareness of environment, ecology, and pollution control. In this research, extraction of dyes from weld using soxhlet apparatus has been studied. The color components extracted and isolated from weld plant were characterized by Column Chromatography, Thin Layer Chromatography (TLC), NMR, mass, IR techniques. The natural dye extract obtained from the weld was used for the dyeing of wool fiber. The results indicated that the exhaustion rate for the extracted dye increases by 49% compared to the raw dye. This, in turn, leads to a considerable decrease in the amount of the extracted dye used to reach the same desired results. Finally, for comparative studies between synthetic and this natural dye, all dyed specimens were tested for wash and light fastness properties, making weld a viable alternative to synthetic acid dyes. © 2010 Elsevier Ltd. All rights reserved.

Ashori A.,Iranian Research Organization for Science and Technology | Sheshmani S.,Islamic Azad University at Tehran
Bioresource Technology | Year: 2010

In this research, hybrid composite materials were made from the combination of recycled newspaper fiber (RNF) and poplar wood flour (PWF) as reinforcement, recycled polypropylene (RPP) as polymer matrix, and maleated polypropylene (MAPP) as coupling agent, by using injection molding. The effects of weight fractions of fibers and coupling agent concentration on the physical properties of the composites in terms of water absorption and thickness were studied. Composites containing more fraction of RNF exhibited maximum water absorption during the whole duration of immersion. This effect can be explained by the presence of a high amount of holocellulose present in the RNF, compared to the PWF. The addition of MAPP exhibited a beneficial effect on both the water absorption and thickness swelling by improving the quality of adhesion between polymer and fibers. © 2010 Elsevier Ltd. All rights reserved.

Akbari Torkestani J.,Islamic Azad University at Tehran | Meybodi M.R.,Amirkabir University of Technology | Meybodi M.R.,Institute for Studies in Theoretical Physics and Mathematics IPM
Computer Networks | Year: 2010

In wireless ad hoc networks, due to the dynamic topology changes, multi hop communications and strict resource limitations, routing becomes the most challenging issue, and broadcasting is a common approach which is used to alleviate the routing problem. Global flooding is a straightforward broadcasting method which is used in almost all existing topology-based routing protocols and suffers from the notorious broadcast storm problem. The connected dominating set (CDS) formation is a promising approach for reducing the broadcast routing overhead in which the messages are forwarded along the virtual backbone induced by the CDS. In this paper, we propose an intelligent backbone formation algorithm based on distributed learning automata (DLA) in which a near optimal solution to the minimum CDS problem is found. Sending along this virtual backbone alleviates the broadcast storm problem as the number of hosts responsible for broadcast routing is reduced to the number of hosts in backbone. The proposed algorithm can be also used in multicast routing protocols, where the only multicast group members need to be dominated by the CDS. In this paper, the worst case running time and message complexity of the proposed backbone formation algorithm to find a 1 / (1 - ε) optimal size backbone are computed. It is shown that by a proper choice of the learning rate of the proposed algorithm, a trade-off between the running time and message complexity of algorithm with the backbone size can be made. The simulation results show that the proposed algorithm significantly outperforms the existing CDS-based backbone formation algorithms in terms of the network backbone size, and its message overhead is only slightly more than the least cost algorithm. © 2009 Elsevier B.V. All rights reserved.

Dabbaghchian S.,University of Tabriz | Ghaemmaghami M.P.,Islamic Azad University at Tehran | Aghagolzadeh A.,University of Tabriz
Pattern Recognition | Year: 2010

Discrete cosine transform (DCT) is a powerful transform to extract proper features for face recognition. After applying DCT to the entire face images, some of the coefficients are selected to construct feature vectors. Most of the conventional approaches select coefficients in a zigzag manner or by zonal masking. In some cases, the low-frequency coefficients are discarded in order to compensate illumination variations. Since the discrimination power of all the coefficients is not the same and some of them are discriminant than others, so we can achieve a higher true recognition rate by using discriminant coefficients (DCs) as feature vectors. Discrimination power analysis (DPA) is a statistical analysis based on the DCT coefficients properties and discrimination concept. It searches for the coefficients which have more power to discriminate different classes better than others. The proposed approach, against the conventional approaches, is data-dependent and is able to find DCs on each database. The simulations results of the various coefficient selection (CS) approaches on ORL and Yale databases confirm the success of the proposed approach. The DPA-based approaches achieve the performance of PCA/LDA or better with less complexity. The proposed method can be implemented for any feature selection problem as well as DCT coefficients. Also, a new modification of PCA and LDA is proposed namely, DPA-PCA and DPA-LDA. In these modifications DCs which are selected by DPA are used as the input of these transforms. Simulation results of DPA-PCA and DPA-LDA on the ORL and Yale database verify the improvement of the results by using these new modifications. © 2009 Elsevier Ltd. All rights reserved.

Torabi M.,City University of Hong Kong | Yaghoobi H.,Islamic Azad University at Tehran | Boubaker K.,University of Tunis
International Journal of Heat and Mass Transfer | Year: 2013

In this paper the analytical solutions for the motion of a spherical particle in a plane Couette Newtonian fluid flow are investigated, by using homotopy perturbation method (HPM) and Padé approximant and the Boubaker polynomials expansion scheme (BPES). The current results are then compared with those derived from HPM and the established fourth order Runge-Kutta method in order to verify the accuracy of the proposed method. It is found that this method can achieve more suitable results compare with HPM. © 2012 Elsevier Ltd. All rights reserved.

Moradi O.,Islamic Azad University at Tehran | Fakhri A.,Islamic Azad University at Tehran | Adami S.,Islamic Azad University at Tehran
Journal of Colloid and Interface Science | Year: 2013

The studies of kinetics and thermodynamics of adsorption of Ethidium bromide in aqueous solutions on single-walled carbon nanotube (SWCNT) and carboxylate group functionalized single-walled carbon nanotube (SWCNT-COOH) surfaces were by UV-Vis spectroscopy. The adsorption kinetics for SWCNT-COOH and SWCNTs were well described by a intra-particle diffusion model, while Langmuir, Freundlich, Harkins-Jura, and Halsey isotherms described the adsorption isotherms, and the adsorption thermodynamic parameters of equilibrium constant (K0), standard free energy (ΔG0), standard enthalpy (ΔH0), and standard entropy changes (ΔS0) were measured. The maximum surface coverage for SWCNTs is 36.10% and for SWCNT-COOH is 38.42%. The values of ΔH0 and ΔG0 suggested that the adsorption of EtBr on SWCNT-COOH and SWCNTs was endothermic and spontaneous. The adsorption of EtBr on SWCNT-COOH is more than SWCNTs surfaces. © 2012 Elsevier Inc.

Kefayati G.H.R.,Islamic Azad University at Tehran
International Communications in Heat and Mass Transfer | Year: 2013

In this paper, the effect of a magnetic field on natural convection in an open enclosure which subjugated to water/alumina nanofluid using Lattice Boltzmann method has been investigated. The cavity is filled with water and nanoparticles of Al2O3 at the presence of a magnetic field. Calculations were performed for Rayleigh numbers (Ra=104-106), volume fractions of nanoparticles (φ=0,0.02,0.04 and 0.06) and Hartmann number (0≤Ha≤90) with interval 30 while the magnetic field is considered horizontally. Results show that the heat transfer decreases by the increment of Hartmann number for various Rayleigh numbers and volume fractions. The magnetic field augments the effect of nanoparticles at Rayleigh number of Ra=106 regularly. Just as the most effect of nanoparticles for Ra=104 is observed at Ha=30, so the most influence of nanoparticles occurs at Ha=60 for Ra=105. © 2012 Elsevier Ltd.

Daemi H.,Islamic Azad University at Tehran | Rad R.R.,University of Tehran | Barikani M.,Iran Polymer And Petrochemical Institute | Adib M.,University of Tehran
Applied Catalysis A: General | Year: 2013

Polyurethane ionomers are well-known and user-friendly polymers. Here, we introduce their catalytic activity for organic reactions as a novel aspect of these polymers. We selected an isocyanide-based multicomponent reaction for proving the catalytic activity of polyurethane ionomers. Therefore, a convenient and very mild methodology is described for the preparation of 3-aminoimidazo[1,2-a]pyridines via a three component reaction between 2-aminopyridines, aldehydes and isocyanides in the presence of a cationic polyurethane dispersion at low reaction temperatures, in short reaction times and excellent yields.© 2013 Elsevier B.V. All rights reserved.

Hosseini J.,Islamic Azad University at Tehran | Bodaghi A.,Islamic Azad University at Tehran
Journal of Solid State Electrochemistry | Year: 2011

Pd nanoparticle/Ti electrodes are prepared by electroless plating of palladium on titanium plates. The morphology and surface analysis of Pd nanoparticle/Ti electrodes are investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The results indicate that palladium nanoparticles are homogeneously deposited on the surface of titanium plates. The electro-catalytic activity of Pd nanoparticle/Ti electrodes in the methanol electro-oxidation is studied by cyclic voltammetry and chronoamperometry methods. The results show that the electro-catalytic oxidation of methanol on the Pd nanoparticle/Ti electrode improved compare to pure palladium electrode and confirmed the better electro-catalytic activity and stability of these new electrodes. © 2010 Springer-Verlag.

Check G.R.,Islamic Azad University at Tehran | Mowla D.,Shiraz University
Ultrasonics Sonochemistry | Year: 2013

In this paper desalting/dehydration process of crude oil by ultrasonic irradiation in a novel batch standing-wave resonator reactor is studied both theoretically and experimentally. The effect of main parameters including ultrasonic irradiation parameters, namely irradiation input power and irradiation time, and also operating parameters, such as temperature and injected water, on the removal efficiencies of salt and water is examined. The obtained results demonstrate that finding the optimum values of the above mentioned parameters is important to prevent a significant decrease in the removal efficiencies of water and especially salt. Thus, crude oil was subjected to optimal ultrasonic irradiation with an input power of 57.7 W, and irradiation time of 6.2 min at temperature of 100 °C. The injected water to dissolve the salt of crude oil was 7 vol.%. Also, the applied settling time and dosage of chemical demulsifier were 60 min and 2 ppm, respectively. Under these optimum conditions the removal efficiencies of the desalting/dehydration process were 84% and 99.8%, respectively, which are suitable for refineries. Also, based on the optimal experimental data, two inferential estimators are developed to obtain the relationships between the salt and water removal efficiencies, and input energy density. These empirical relationships can offer a proper estimation for the salt and water removal efficiencies with irradiation input energy. © 2012 Elsevier B.V. All rights reserved.

Ghahari H.,Islamic Azad University at Tehran | Moulet P.,Museum Requien
Zootaxa | Year: 2012

The Iranian fauna of the Lygaeoidea (excluding Berytidae and Piesmatidae) is summarized in this paper. In total, 9 families, 7 subfamilies, 87 genera and subgenera, and 238 species and subspecies are listed from Iran. One species, Dieuches armatipes (Walker, 1872), is newly recorded from Iran. Copyright © 2012 Magnolia Press.

Hosseini S.A.,Islamic Azad University at Tehran | Ghassemian H.,Tarbiat Modares University
International Journal of Remote Sensing | Year: 2011

The support vector machine (SVM) has been a dominant machine-learning technique in the last decade and has demonstrated its efficiency in many applications. Research on classification of hyperspectral images have shown the efficiency of this method to overcome the Hughes phenomenon for classification of such images. A major drawback of classification by SVM is that this classifier was originally developed to solve binary problems, and the algorithms for multiclass problems usually have a high-computational load. In this article, a new and fast method for multiclass problems is proposed. This method has two stages. In the first stage, samples are classified by a maximum likelihood (ML) classifier, and in the second stage, SVM selects the final label of a sample among high-probability classes for that sample by a tree structure. So, for each sample, only some classes must be searched by SVM to find its label. The uncertainty of ML classification for a sample is obtained by the entropy of probabilities, and the number of classes that must be searched by SVM for a sample is obtained based on the uncertainty of that sample in the primary ML classification. This approach is compared with two widely used multiclass algorithms: one-against-one (OAO) and directed acyclic graph (DAGSVM). The obtained results on real data from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) revealed less computational time and better accuracy compared to these multiclass algorithms. © 2011 Taylor & Francis.

Eshagh M.,Islamic Azad University at Tehran | Eshagh M.,University College West
Geophysical Prospecting | Year: 2014

The idea of this paper is to present estimators for combining terrestrial gravity data with Earth gravity models and produce a high-quality source of the Earth's gravity field data through all wavelengths. To do so, integral and point-wise estimators are mathematically developed, based on the spectral combination theory, in such a way that they combine terrestrial data with one and/or two Earth gravity models. The integral estimators are developed so that they become biased or unbiased to a priori information. For testing the quality of the estimators, their global mean square errors are generated using an Earth gravity model08 model and one of the recent products of the gravity field and steady-state ocean circulation explorer mission. Numerical results show that the integral estimators have smaller global root mean square errors than the point-wise ones but they are not efficient practically. The integral estimator of the biased type is the most suited due to its smallest global root mean square error comparing to the rest of the estimators. Due largely to the omission errors of Earth gravity models the point-wise estimators are not sensitive to the Earth gravity model commission error; therefore, the use of high-degree Earth gravity models is very influential for reduction of their root mean square errors. Also it is shown that the use of the ocean circulation explorer Earth gravity model does not significantly reduce the root mean square errors of the presented estimators in the presence of Earth gravity model08. All estimators are applied in the region of Fennoscandia and a cap size of 2° for numerical integration and a maximum degree of 2500 for generation of band-limited kernels are found suitable for the integral estimators. © 2013 European Association of Geoscientists & Engineers.

In this study, a highly sensitive and selective sensor was fabricated on the basis of 4-hydroxy-2-(triphenylphosphonio)phenolate (HTP) and a multi-wall carbon nanotubes paste electrode (HTP-MWCNT-CPE) for the trace amounts quantification of folic acid (FA). The results show that the combination of multi-wall carbon nanotubes and a modifier causes a dramatic enhancement in the sensitivity of FA quantification. Kinetic parameters such as the electron transfer coefficient, α, and the catalytic electron transfer rate constant, k′, for the oxidation of FA at the modified electrode were estimated using cyclic voltammetry. The detection limit of 0.036 μM and two linear calibration ranges of 0.2-8.0 μM and 8.0-175.0 μM were obtained for FA determination at HTP-MWCNT-CPE using the differential pulse voltammetry (DPV). By DPV, the modified electrode could separate ascorbic acid (AA), FA, and uric acid (UA) signals into three well-defined voltammetric peaks. Finally, HTP-MWCNT-CPE proved to have good sensitivity and stability, and was successfully applied for the determination of FA in wheat flour and pharmaceutical samples, FA and AA in fruits, and AA, FA and UA in human urine samples. © 2011 Elsevier Ltd. All rights reserved.

Mamourian M.,Ferdowsi University of Mashhad | Milani Shirvan K.,Ferdowsi University of Mashhad | Mirzakhanlari S.,Islamic Azad University at Tehran | Rahimi A.B.,Ferdowsi University of Mashhad
Applied Thermal Engineering | Year: 2016

A 2-D numerical study and a sensitivity analysis of convective heat transfer in a channel with vortex generators for application in solar heat exchangers are investigated using a Lagrangian-Eulerian model along with determination of the Nanoparticles concentration distribution. Numerical simulations are carried out to study the effects of Reynolds number (50 ⩽ Re ⩽ 250), Nanoparticles volume fraction (0.01 ⩽ Ф ⩽ 0.04), distance between two vortex generators (10 mm ⩽ d ⩽ 20 mm) and the angles between them (30° ⩽ α and β ⩽ 150°) on the heat transfer performance and Nanoparticles distribution. In addition, an analysis on effective parameters is processed utilizing the Response Surface Methodology. The results show a 39.81% increase in the Nusselt number for Re numbers ranged from 150 to 250. Also, it is found that increasing in d and α and reduction of β and Ф increases the mean Nusselt number. Enhancement in d, α and β and also decreasing in Re number and Ф increases the homogeneity of the Nanofluid. Finally, it is shown that the sensitivity of the mean Nusselt number to the Re number, Ф and d parameters is more than the sensitivity of the Nanoparticles concentration ratio to these parameters. © 2016 Elsevier Ltd

Montazer M.,Amirkabir University of Technology | Pakdel E.,Islamic Azad University at Tehran | Behzadnia A.,Islamic Azad University at Tehran
Journal of Applied Polymer Science | Year: 2011

In this study, the antifelting and antibacterial features of wool samples treated with nanoparticles of titanium dioxide (TiO2) were evaluated. To examine the antifelting properties of the treated samples, the fabric shrinkage after washing was determined. The antimicrobial activity was assessed through the calculation of bacterial reduction against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. TiO 2 was stabilized on the wool fabric surface by means of carboxylic acids, including citric acid (CA) and butane tetracarboxylic acid (BTCA). Both oxidized samples with potassium permanganate and nonoxidized wool fabrics were used in this study. The relations between both the TiO2 and carboxylic acid concentrations in the impregnated bath and the antifelting and antibacterial properties are discussed. With increasing concentration in the impregnated bath, the amount of TiO2 nanoparticles on the surface of the wool increased; subsequently, lower shrinkage and higher antibacterial properties were obtained. The existence of TiO2 nanoparticles on the surface of the treated samples was proven with scanning electron microscopy images and energy-dispersive spectrometry. © 2011 Wiley Periodicals, Inc.

Kefayati G.R.,Islamic Azad University at Tehran
Theoretical and Computational Fluid Dynamics | Year: 2013

In this paper, the effects of a magnetic field on natural convection flow in filled long enclosures with Cu/water nanofluid have been analyzed by lattice Boltzmann method. This study has been carried out for the pertinent parameters in the following ranges: the Rayleigh number of base fluid, Ra = 10 3-105, the volumetric fraction of nanoparticles between 0 and 6 %, the aspect ratio of the enclosure between A = 0.5 and 2. The Hartmann number has been varied from Ha = 0 to 90 with interval 30 while the magnetic field is considered at inclination angles of θ = 0, 30, 60 and 90. Results show that the heat transfer decreases by the increment of Hartmann number for various Rayleigh numbers and the aspect ratios. Heat transfer decreases with the growth of the aspect ratio but this growth causes the effect of the nanoparticles to increase. The magnetic field augments the effect of the nanoparticles at high Rayleigh numbers (Ra = 105). The effect of the nanoparticles rises for high Hartmann numbers when the aspect ratio increases. The rise in the magnetic field inclination improves heat transfer at aspect ratio of A = 0.5. © 2012 Springer-Verlag Berlin Heidelberg.

Ardestani M.,Islamic Azad University at Tehran
Journal of Ceramic Processing Research | Year: 2016

Copper/chromium oxide (75%wt) nanocomposite powders were synthesized via chemical precipitation process. The process was included chemical precipitation of Cr-Cu containing precipitates, calcination and reduction of the precipitates. Based on thermogravimetric analysis of the precipitates, the optimum calcination temperature was determined as 700oC. The synthesized powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The observations revealed that the powder particles were agglomerated and their shape was mainly spherical. The powders were densified via spark plasma and presssureless sintering at 1000oC and 1100oC, respectively. The microstructural evaluation of the spark plasma sintered samples confirmed a near dense structure with a fine dispersion of the constituents. However, the microstructure of the pressureless sintered specimen showed a large number of pores between the powder particles. The relative density and micro-hardness of the spark plasma sintered samples were 95.8% and 1600 HV, respectively. © 2016, Hanyang University. All rights reserved.

Zare Y.,Islamic Azad University at Tehran
Macromolecular Materials and Engineering | Year: 2016

A two-step method is suggested to predict the Young's modulus of polymer nanocomposites assuming the interphase between polymer matrix and nanoparticles. At first, nanoparticles and their surrounding interphase are assumed as effective particles with core-shell structure and their modulus is predicted. At the next step, the effective particles are taken into account as a dispersed phase in polymer matrix and the modulus of composites is calculated. The predictions of the two-step method are compared with the experimental data in absence and presence of interphase and also, the influences of nanoparticles size as well as interphase thickness and modulus on the Young's modulus of nanocomposites are explored. The predictions of the suggested model show good agreement with the experimental data by proper ranges of interphase properties. Moreover, the interphase thickness and modulus straightly affect the modulus of nanocomposites. Also, smaller nanoparticles create a higher level of modulus for nanocomposites, due to the large surface area at interface and the strong interfacial interaction between polymer matrix and nanoparticles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ghanbari M.,University of Tehran | Check G.R.,Islamic Azad University at Tehran
Journal of Supercritical Fluids | Year: 2012

In this work, super-critical cohesion parameters for Soave-Redlich-Kwong (SRK) equation of state (EOS) were adjusted by fitting cohesion parameters to the reliable Joule-Thomson Inversion Curve (JTIC) data. For this purpose, the reliable JTIC data for CH 4 and CO 2 were adopted from literature. To evaluate the result, the modified SRK EOS was also compared to the EOSs including square-well (SW) EOS, four-parameter Trebble-Bishnoi (TB) EOS and Peng-Robinson (PR) EOS. Moreover, The JTICs obtained from the new EOS for nine substances Ar, Ne, N 2, O 2, C 2H 4, C 2H 6, CO 2, CH 4 and CO indicated new EOS abilities to present good predictions, while the SRK EOS produced the results underpredicted at high-temperature regions. In addition, a detailed analysis of the ideal curves including JTIC, Boyle curve and Zeno line and also compressibility factor curve, which were calculated by the new EOS was carried out. © 2011 Elsevier B.V. All rights reserved.

Tabari H.Z.,Islamic Azad University at Tehran | Nourbakhsh A.,Iranian Research Institute of Forests and Rangelands | Ashori A.,Iranian Research Organization for Science and Technology
Polymer Engineering and Science | Year: 2011

This article presents the effects of coupling agent and nanoclay (NC) on some properties of wood flour/polypropylene composites. The composites with different NC and maleic anhydride grafted polypropylene (MAPP) contents were fabricated by melt compounding in a twin-screw extruder and then by injection molding. The mass ratio of the wood flour to polymer was 40/60 (w/w). Results showed that applying MAPP on the surface of the wood flour can promote filler polymer interaction, which, in turn, would improve mechanical properties of the composite as well as its water uptake and thermal stability. Composite voids and the lumens of the fibers were filled with NC, which prevented the penetration of water by the capillary action into the deeper parts of composite. Therefore, the water absorption in composites fabricated using NC was significantly reduced. Scanning electron microscopy has shown that the treatment of composites with 5 wt% MAPP, promotes better fiber-matrix interaction, resulting in a few numbers of pull-out traces. In all cases, the degradation temperatures shifted to higher values after using MAPP. The largest improvement on the thermal stability of composites was achieved when NC was added. © 2010 Society of Plastics Engineers.

Mazinan A.H.,Islamic Azad University at Tehran
ISA Transactions | Year: 2015

The paper attempts to address a new control approach to spacecraft maneuvers based upon the modes of propellant engine. A realization of control strategy is now presented in engine on mode (high thrusts as well as further low thrusts), which is related to small angle maneuvers and engine off mode (specified low thrusts), which is also related to large angle maneuvers. There is currently a coarse-fine tuning in engine on mode. It is shown that the process of handling the angular velocities are finalized via rate feedback system in engine modes, where the angular rotations are controlled through quaternion based control (QBCL)strategy in engine off mode and these ones are also controlled through an optimum PID (OPIDH) strategy in engine on mode. © 2015 ISA.

The best solvent type and ratio for grafting of poly-n-isopropylacrylamide (PNIPAAm) on the surface of polystyrene is obtained under ultraviolet radiation. In this study, the effects of solvents, such as water, methanol, and their combinations, under ultraviolet radiation were investigated successfully. Attenuated total reflection Fourier transform infrared analysis showed the existence of the graft PNIPAAm on the substrate for all samples resolved in solvents. The best solvent ratio and NIPAAm concentration for grafting was obtained with 40% NIPAAm concentrations resolved in a solvent of 9:1 (v/v) water/methanol (120%). Scanning electron microscopic and atomic force microscopic images clearly showed that a 10% increase of methanol to water would increase the amount of grafting. Surface topography and graft thickness in atomic force microscopic images of the grafted samples showed that the thickness of these grafts was about 600 nm. The drop water contact angles of the best grafted sample at 37°C and 4°C were 43.3° and 60.4°, respectively, which demonstrated the hydrophilicity and hydrophobicity of the grafted surfaces. Differential scanning calorimetric analysis also revealed the low critical solution temperature of the grafted sample to be 32°C. Thermoresponsive polymers were grafted to dishes covalently, which allowed epithelial cells to attach and proliferate at 37°C. The cells were also detached spontaneously without using enzymes when the temperature dropped below 4°C. MTT analysis also showed good viability of cells on the grafted samples, suggesting that this type of grafted material had potential as a biomaterial for cell sheet engineering.

Monajjemi M.,Islamic Azad University at Tehran | Hosseini M.S.,Islamic Azad University at Tehran | Molaamin F.,Islamic Azad University at Qom
Fullerenes Nanotubes and Carbon Nanostructures | Year: 2013

To investigate the electromagnetic interaction of molecules inside the nanotubes, we studied the nuclear magnetic resonance properties(NMR) and shielding parameters between nanotubes, after optimizing the structure of nanotubes with a formula BxNx (x = 2,3,4,5) with hybrid density functional theory (B3LYP) using the EPR-II basis set. We also performed natural bond orbital (NBO) analysis, which revealed some important atomic and structural features. Besides structural characteristics, the lowest unoccupied molecular orbital and the highest occupied molecular orbital for the lowest energy were calculated to examine the structural stability of the nanotubes. In NBO calculation, graphs of number occupied orbital p of atoms B and N were plotted versus the coefficients linear combinations. © 2013 Taylor & Francis Group, LLC.

Sadeghi A.A.,Islamic Azad University at Tehran
Probiotics and Antimicrobial Proteins | Year: 2014

The present study was carried out to determine the effect of probiotic, Bacillus subtilis, on ash and calcium contents of tibia bone in unchallenged and challenged broiler chicks with Salmonella enteritidis. In a completely randomized design, 160 chicks were divided into four groups. Each group had four replicates with 10 birds each. Treatments were control group, probiotic-treated group, challenged group and challenged probiotic-treated group. Ash and calcium contents of tibia at 21 and 42 days of age were determined. At 21 days of age, the highest contents of ash and calcium were related to probiotic-treated group and the lowest means to challenged chicks (P < 0.05). At this period, inclusion of probiotic to diet of challenged chick increased (P < 0.05) ash and calcium contents of tibia. With increases in age, the negative effects of challenging and beneficial effects of probiotic on bone mineralization diminished; since at 42 days of age, challenging or probiotic treatment had no effect on ash and calcium contents of tibia. © 2014, Springer Science+Business Media New York.

Kholousi Y.,Islamic Azad University at Tehran
Research Journal of Applied Sciences, Engineering and Technology | Year: 2013

Performance evaluation is the evaluation and assessment process of the existing situation. It determines how to achieve good status with the specified criteria in a specificperiod of time with the goal of continuous improvement of the organization performance. Data Envelopment Analysis (DEA) is one of the most effective and popular ways to evaluate performance. The basic DEA model does not rank overall and only classifies the options into two groups: efficient and inefficient. However, over the past 10 years, many efforts have been made to classify the options completely with the DEA. This research is another effort to use the concept of DEA in a complete ranking of options by one of the most common methods of multi-criteria decision making, Analytical Hierarchy Process (AHP). AHP/DEA model which is investigated in this research is comprised of two stages. In this study, first the criteria are measured in comparison to each other and the paired comparisons matrix is obtained, using data envelopment analysis. Then, the most efficient branch is determined, using the Analytical Hierarchy Process. Performance evaluation of branches is carried out based on the input and output values. In this study, four input criteria (cost of movable property, labor costs, administrative costs and the number of branch personnel)and three output criteria (deposits, granted facilities and branch profits) are used to evaluate the efficiency of bank branches in the period of Aban 1384 until Day 1385 for sixteen bank branches in Iran's Sistan and Baluchistan province, using WinQSB and Expert Choice software and the AHP/DEA model. Results showed that the three branches Alavi, Centraland Joushkaran have the ranks highest weight respectively. In addition, the results indicated that the method of AHP/DEA is an efficient method for evaluating the performance andcan improve the weaknesses of traditional DEA method. © Maxwell Scientific Organization, 2013.

Biati A.,Islamic Azad University at Tehran | Karbassi A.R.,University of Tehran
Environmental Monitoring and Assessment | Year: 2012

Flocculation of dissolved Cu, Mn, Ni, Zn, and Pb during mixing of Siyahrud River water with water sample of Caspian Sea at nine different salinity regimes was investigated. The maximum flocculation of elements occurs in the salinities 1.67‰ to 3.67‰ (except for Zn). The flocculation trend of Zn (80.9) >Mn (58.3) > Cu (30.5) > Ni (25.9) > Pb (19.5) indicates that flocculation of metals have nonlinear behavior towards salinity changes during estuarine mixing. Electrical conductivity shows a linear behavior in different proportions of salinity which is in contrast with the behavior of other studied parameters. Cluster analysis indicates that pH and NO3 are governing factors in the flocculation of Cu, Mn, and Pb. The results of this research show that 80.9%, 19.5%, 25.9%, 30.5%, and 58.3% of dissolved Zn, Pb, Ni, Cu, and Mn flocculate during estuarine mixing. Total amount of studied dissolved element flowing in to the Caspian Sea would decrease from 5.62 to 2.76 t/year. © 2011 Springer Science+Business Media B.V.

Pazand K.,Islamic Azad University at Tehran
Arabian Journal of Geosciences | Year: 2015

In Iran, coal deposits from the upper Triassic-lower Jurassic era are limited to the Tabas and Alborz coal basins and three small independent carboniferous regions. One of the coalfields in the Alborz basin is the Abyek coalfield, the focus of our investigation. It is located in the northern mountain ranges of Iran, and we investigate the geochemical behavior of the rare earth elements in it. Five samples were collected and analyzed for trace and rare earth elements (REE) using inductively coupled plasma (ICP). The Abyek area is characterized by very high ash value. The content of total REY (REEs + Y) in the coals varies from 143.19 to 254.39 ppm and ranged 28–43.83 ppm in argillite. The abundance of light rare earth elements (LREES) is higher relative to heavy rare earth elements (HREEs). © 2014, Saudi Society for Geosciences.

Bistouni F.,Islamic Azad University at Qazvin | Jahanshahi M.,Islamic Azad University at Tehran
Reliability Engineering and System Safety | Year: 2014

Supercomputers and multi-processor systems are comprised of thousands of processors that need to communicate in an efficient way. One reasonable solution would be the utilization of multistage interconnection networks (MINs), where the challenge is to analyze the reliability of such networks. One of the methods to increase the reliability and fault-tolerance of the MINs is use of various switching stages. Therefore, recently, the reliability of one of the most common MINs namely shuffle-exchange network (SEN) has been evaluated through the investigation on the impact of increasing the number of switching stage. Also, it is concluded that the reliability of SEN with one additional stage (SEN+) is better than SEN or SEN with two additional stages (SEN+2), even so, the reliability of SEN is better compared to SEN with two additional stages (SEN+2). Here we re-evaluate the reliability of these networks where the results of the terminal, broadcast, and network reliability analysis demonstrate that SEN+ and SEN+2 continuously outperform SEN and are very alike in terms of reliability. © 2014 Elsevier Ltd. All rights reserved.

Dashti Khavidaki H.,Islamic Azad University at Tehran | Aghaie H.,Islamic Azad University at Tehran
Clean - Soil, Air, Water | Year: 2013

Using batch method, the adsorption of thallium(I) ions from aqueous solutions on eucalyptus leaves powder, as a low cost adsorbent, was studied. The effect of various modification of considered adsorbent on the adsorption percentage of Tl(I) is an important feature of this study. The results showed that the unmodified and acidic modified adsorbent are the poor adsorbents for the Tl(I) ions while basic modified adsorbent is a suitable adsorbent. Also, the effect of some experimental conditions such as solution initial pH, agitation speed, contact time, sorbent dosage, temperature, particle size, and thallium initial concentration was studied. The results showed that the adsorption percentage depends on the conditions and the process is strongly pH-dependent. The satisfactory adsorption percentage of Tl(I) ions, 81.5%, obtained at 25±1°C. The equilibrium data agreed fairly better with Langmuir isotherm than Freundlich and Temkin models. The value of qm that was obtained by extrapolation method is 80.65mgg-1. Separation factor values, RL, showed that eucalyptus leaves powder is favorable for the sorption of Tl(I). The negative values of ΔH0 and ΔS0 showed that the Tl(I) sorption is an exothermic process and along with decrease of randomness at the solid-solution interface during sorption, respectively. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Anafcheh M.,Islamic Azad University at Tehran | Ghafouri R.,Islamic Azad University at Tehran
Journal of Cluster Science | Year: 2013

We have performed a density functional theory study to investigate the effect of carbon doping on Stone-Wales (SW) defective sites in the armchair (4, 4), (5, 5) and (6, 6) BNNTs, in order to remove structural instability induced by homonuclear N-N and B-B bonds. Two different orientations of SW defect are considered, parallel and diagonal, and then C atoms are doped at different positions of the defect sites. In general, it seems that among the considered arrangements, C atoms prefer to be substituted for the homonuclear B-B bond. The larger HOMO-LUMO band gaps for the most stable configurations indicate that C doping at B-B sites is kinetically more favorable than the other ones. According to calculated nuclear quadrupole resonance (NQR) parameters as a result of C-doping on SW defective sites, the quadrupole coupling constants (C Q) of boron nuclei at defective sites decrease by about 0.508-1.406 MHz while 14N C Q of the defective sites, except for N8, increases. Interestingly, C Q of the N sites directly connected to dopant sites has maximum increment (0.612-2.596 MHz) while C Q of the N sites belonging to the B2N3 pentagon is undergone to some minor changes. © 2013 Springer Science+Business Media New York.

Solati E.,Islamic Azad University at Tehran | Mashayekh M.,Islamic Azad University at Tehran | Dorranian D.,Islamic Azad University at Tehran
Applied Physics A: Materials Science and Processing | Year: 2013

Silver nanoparticles were synthesized using pulsed laser ablation of Ag metal plate in acetone. The pulsed of a Q-switched Nd:YAG laser of 1064 and 532 nm wavelengths at 7 ns pulse width and different fluences is employed to irradiate the solid target in acetone. The UV-Visible absorption spectra of the Ag nanoparticles exhibit absorptions in the ultraviolet and in visible regions because of interband transition and surface plasmon resonance oscillations in Ag nanoparticles, respectively. In the case of nanoparticles produced with laser pulse of 1064 nm, TEM images indicate that with increasing the laser fluence, the average size of the spherical nanoparticles increases. It is found that Ag nanoparticles exhibit photoluminescence emission, at room temperature, in the UV-Visible region due to electron-hole recombination. © 2013 Springer-Verlag Berlin Heidelberg.

This in vitro study was performed to evaluate the effect of a diode laser and common disinfectants used in combination on mono-infected dental canals. One hundred and six single-rooted human premolars were prepared and contaminated with Enterococcus faecalis. After two weeks of incubation, samples were divided into two experimental groups (n = 48) and two control groups (n = 5). In the first group, the teeth were rinsed for 5 min with either sterile saline, 2.5% NaOCl, or MTAD, or for 1 min with 2% chlorhexidine gluconate (CHX). In the other group, samples were additionally irradiated with a 810-nm diode laser at 2 W output for 5 × 5 s. Intracanal bacterial sampling was done, and the samples were plated to determine the CFU count. In the first group, 2.5% NaOCl was as effective as 2% CHX and significantly more effective than MTAD (P < 0.008). In the second group, either MTAD, 2% CHX or 2.5% NaOCl in combination with laser treatment had a similar effect. Absence of growth was seen only for MTAD plus laser treatment. Complete elimination of E. faecalis was seen only for the combination of MTAD with diode laser irradiation. Combination therapy with MTAD irrigation and diode laser irradiation, within the parameters used in this study, can be recommended as an effective treatment option for complete elimination of E. faecalis from the root canal system.

Irani S.,Islamic Azad University at Tehran
International journal of nanomedicine | Year: 2011

The p53 tumor-suppressor gene encodes a nuclear phosphoprotein with cancer- inhibiting properties. The most probable cancerous mutations occur as point mutations in exons 5 up to 8 of p53, as a base pair substitution that encompasses CUA and GAT sequences. As DNA drug design represents a direct genetic treatment of cancer, in the research reported computational drug design was carried out to explore, at the Hartree-Fock level, effects of solvents on the thermochemical properties and nuclear magnetic resonance (NMR) shielding tensors of some atoms of CUA involved in the hydrogen-bonding network. The observed NMR shielding variations of the solutes caused by solvent change seemed significant and were attributed to solvent polarity, and solute-solvent and solvent-solute hydrogen-bonding interactions. The results provide a reliable insight into the nature of mutation processes. However, to improve our knowledge of the hydration pattern more rigorous computations of the hydrated complexes are needed.

Ghiasi R.,Islamic Azad University at Tehran
Acta Crystallographica Section E: Structure Reports Online | Year: 2011

In the title compound, [ZnBr2(C6H4N 2)2], the ZnII atom is four coordinated in a slightly distorted tetrahedral fashion by two pyridine N atoms and two Br - anions. π- π interactions between adjacent pyridine rings [centroid-centroid distance = 3.6229 (19) Å ] are the main factor controlling the packing and are effective in the stabilization of the crystal structure.

Samani M.R.,Islamic Azad University at Tehran | Borghei S.M.,Sharif University of Technology | Olad A.,University of Tabriz | Chaichi M.J.,University of Mazandaran
Journal of Hazardous Materials | Year: 2010

The adsorption of chromium compounds from solutions by a composite of polyaniline/poly ethylene glycol (PANi/PEG) was investigated in this study. Experiments were conducted in batch mode under various operational conditions including agitation time, solution pH, PANi/PEG dose and initial concentration of chromium salts. Results showed that concentration of PEG at synthesizing stage has a significant effect on the capacity of produced composite for removal of chromium. Morphologically, PANi/PEG composite is closely dependent on the concentration of PEG. Maximum removal of hexavalent chromium was experienced when 2. g/L of PEG was used in synthesis of PANi/PEG. Removal of hexavalent chromium by PANi/PEG composite included surface adsorption and reduction reaction. The optimum pH was 5 and the equilibrium time for hexavalent chromium removal was about 30. min. Investigation of the isothermal characteristics showed that chromium adsorption by PANi/PEG composite was in high accordance with Langmuir's isotherm. © 2010 Elsevier B.V.

Dolatshahi-Zand A.,Islamic Azad University at Tehran | Khalili-Damghani K.,Islamic Azad University at Tehran
Reliability Engineering and System Safety | Year: 2014

SCADA1 is an essential system to control critical facilities in big cities. SCADA is utilized in several sectors such as water resource management, power plants, electricity distribution centers, traffic control centers, and gas deputy. The failure of SCADA results in crisis. Hence, the design of SCADA system in order to serve a high reliability considering limited budget and other constraints is essential. In this paper, a bi-objective redundancy allocation problem (RAP) is proposed to design Tehrans SCADA water resource management control center. Reliability maximization and cost minimization are concurrently considered. Since the proposed RAP is a non-linear multi-objective mathematical programming so the exact methods cannot efficiently handle it. A multi-objective particle swarm optimization (MOPSO) algorithm is designed to solve it. Several features such as dynamic parameter tuning, efficient constraint handling and Pareto gridding are inserted in proposed MOPSO. The results of proposed MOPSO are compared with an efficient ε-constraint method. Several non-dominated designs of SCADA system are generated using both methods. Comparison metrics based on accuracy and diversity of Pareto front are calculated for both methods. The proposed MOPSO algorithm reports better performance. Finally, in order to choose the practical design, the TOPSIS algorithm is used to prune the Pareto front. © 2014 Elsevier Ltd.

Baei M.T.,Guangzhou University | Peyghan A.A.,Islamic Azad University at Tehran | Bagheri Z.,Islamic Azad University at Tehran
Solid State Communications | Year: 2013

By using density functional theory calculations, the adsorption of Cl - and F- ions on a BC2N nanotube was investigated. Adsorption energies in the most stable configurations are about -0.36 and -5.65 eV for Cl- and F- ions, respectively. The adsorption of F- ion much more influences the electronic properties of the tube, in comparison with the Cl- ion, so that it is transformed from an intrinsic semiconductor with HOMO/LUMO energy gap of 2.57 eV to an extrinsic n-type semiconductor with the gap of 0.67 eV. It was found that the adsorption of both anions on the tube would facilitate the field electron emission from its surface by shifting the Fermi level to higher energies and decreasing the work function, significantly. © 2013 Elsevier Ltd.

Atabi F.,Islamic Azad University at Tehran | Mirzahosseini S.A.H.,Islamic Azad University at Tehran
International Journal of Occupational Medicine and Environmental Health | Year: 2013

Objectives: The present study aimed to assess the risk of cancer due to benzene in the ambient air of gas stations and traffic zones in the north of Tehran. The cancer risk was estimated using the population distribution data for benzene levels and the unit risk for benzene proposed by the United States Environmental Protection Agency (US EPA). Material and Methods: Sixteen sampling locations were monitored, once every week, during 5 April 2010 to 25 March 2011. Results: The results showed that the mean annual benzene concentration was 14.51±3.17 parts per billion (ppb) for traffic zones and 29.01±1.32 ppb for outside gas stations. The risk calculated was 1026×10-6 for gas station 27 and 955×10-6 for gas station 139. Conclusions: According to our results, the annual benzene level in Tehran ambient air is 2 to 20 times higher than the respective value specified in International Standard (1.56 ppb). Moreover, the results showed a notable increase of cancer risks, ranging from 10% to 56%, for the vicinity population close to the gas stations in comparison to the vicinity population in the traffic zones. © 2013 Versita Warsaw and Springer-Verlag Wien.

Zare Y.,Islamic Azad University at Tehran
Mechanics of Materials | Year: 2015

The micromechanics models for composites usually underpredict the tensile strength of polymer nanocomposites. This paper establishes a simple model based on Kelly-Tyson theory for tensile strength of polymer/CNT nanocomposites assuming the effect of interphase between polymer and CNT. In addition, Pukanszky model is joined with the suggested model to calculate the interfacial shear strength (τ), interphase strength (σi) and critical length of CNT (Lc). The proposed approach is applied to calculate τ, σi and Lc for various samples from recent literature. It is revealed that the experimental data are well fitted to calculations by new model which confirm the important effect of interphase on the properties of nanocomposites. Moreover, the derived equations demonstrate that dissimilar correlations are found between τ and B (from Pukanszky model) as well as Lc and B. It is shown that a large B value obtained by strong interfacial adhesion between polymer and CNT is adequate to reduce Lc in polymer/CNT nanocomposites. © 2015 Elsevier Ltd. All rights reserved.

Parvinzadeh M.,Islamic Azad University at Tehran | Ebrahimi I.,Islamic Azad University at Tehran
Applied Surface Science | Year: 2011

Influence of atmospheric air plasma treatment on performance of nanoemulsion silicone softener on polyethylene terephthalate fibers was investigated by the use of fourier transform infrared spectroscopy (FTIR), bending lengths (BL), wrinkle recovery angles (WRA), fiber friction coefficient analysis (FFCA), moisture absorbency (MA), scanning electron microscopy (SEM) and reflectance spectroscopy (RS). Results indicated that the plasma pretreatment modifies the surface of fibers and increases the reactivity of substrate toward nanoemulsion silicone. Moisture regain and microscopic tests showed that the combination of plasma and silicone treatments on polyethylene terephthalate can decrease moisture absorption due to uniform coating of silicone emulsion on surface of fibers. © 2010 Elsevier B.V.

Hosseini S.H.,Islamic Azad University at Tehran | Mohseni S.H.,Iran University of Science and Technology | Asadnia A.,Imam Hossein University | Kerdari H.,Islamic Azad University at Sāveh
Journal of Alloys and Compounds | Year: 2011

Conductive polyaniline (PANi)-manganese ferrite (MnFe2O 4) nanocomposites with core-shell structure were synthesized by in situ polymerization in the presence of dodecyl benzene sulfonic acid (DBSA) as the surfactant and dopant and ammonium persulfate (APS) as the oxidant. The structure and magnetic properties of manganese ferrite nanoparticles were measured by using powder X-ray diffraction (XRD) and vibrating sample magnetometer (VSM), respectively. Its morphology, microstructure and DC conductivity of the nanocomposite were characterized by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and four-wire-technique, respectively. The microwave absorbing properties of the nanocomposite powders dispersing in resin acrylic coating with the coating thickness of 1.4 mm were investigated by using vector network analyzers in the frequency range of 8-12 GHz. A minimum reflection loss of -15.3 dB was observed at 10.4 GHz. © 2010 Elsevier B.V. All rights reserved.

Nayyeri M.J.,Islamic Azad University at Tehran | Khomamizadeh F.,Sharif University of Technology
Journal of Alloys and Compounds | Year: 2011

In the present article, the effect of Rare Earth elements on the microstructural development of as cast and semisolid Mg-4Al alloy produced by SIMA process is studied. Investigation conducted by metallographic observation, scanning electron microscope and quantitative metallographic methods. Results showed that alloy's dendrites turn into larger fully dendritic shape with sharp and narrow arms from equiaxed rosette type as the amount of RE elements increased from 0 through 4%. The effect of RE elements on the microstructure of the treated-alloys was detectable through elimination of vast number of intragranular liquid droplets as well as by decreasing kinetic of microstructural changes. It was shown that the trend of grain coarsening decreased drastically by addition of RE elements to the Mg-4Al alloy during partial remelting at 610 °C. Moreover, the effect of REs on the other parameters such as fraction of liquid, shape factor and particle size was studied. © 2010 Elsevier B.V. All rights reserved.

Esmaeili A.,Islamic Azad University at Tehran | Kalantari M.,Islamic Azad University at Tehran
World Journal of Microbiology and Biotechnology | Year: 2012

The objective of this paper was to study the potential for bioremoval of a textile dye, Reactive Red 198 (RR198), by a fungus isolated from soil collected from an effluent disposal area near a textile company. The fungus was identified as Aspergillus flavus, and its use as a low-cost live-cell biomass for the biodegradation of RR198 from contaminated water was investigated using batch studies. The effects of time, dye concentration, and pH as variable factors were examined in the process. Results showed that bioremoval of RR198 by A. flavus increased to over 84. 96% with increasing time until equilibrium was reached after a period of 24 h. A low pH was the most effective, as were lower levels of dye concentration. The decolorization was determined by the decrease in the absorption maximums of this dye by UV-visible spectroscopy. A. flavus was shown to be an efficient fungus for removal of RR198 from wastewater. © 2011 Springer Science+Business Media B.V.

Pouranvari M.,Sharif University of Technology | Alizadeh-Sh M.,Islamic Azad University at Tehran | Marashi S.P.H.,Amirkabir University of Technology
Science and Technology of Welding and Joining | Year: 2015

Weldability is one of the key requirements for automotive materials. This two-part paper aims at understanding the metallurgical phenomena during resistance spot welding of stainless steels, as interesting candidates for automotive body in white. Part I addresses the phase transformations in the fusion zone of three types of stainless steels including austenitic, ferritic and duplex types. The solidification and solid state phenomena including columnar to equiaxed transition, ferrite– austenite post-solidification transformation, martensitic transformation and carbide precipitation are discussed. Particular attention is given to the effect of high cooling rate of resistance spot welding process on the ferrite–austenite transformation. Key factors controlling the hardness of the fusion zone are highlighted. © 2015 Institute of Materials, Minerals and Mining.

Biodegradable polyurethanes have found widespread use in soft tissue engineering due to their suitable mechanical properties and biocompatibility. In this study, polyurethane samples were synthesized from polycaprolactone, hexamethylene diisocyanate, and a copolymer of 1,4-butanediol as a chain extender. Polyurethane scaffolds were fabricated by a combination of liquid-liquid phase separation and salt leaching techniques. The effect of the NCO:OH ratio on porosity content and pore morphology was investigated. Scanning electron micrographs demonstrated that the scaffolds had a regular distribution of interconnected pores, with pore diameters of 50-300 μm, and porosities of 64%-83%. It was observed that, by increasing the NCO:OH ratio, the average pore size, compressive strength, and compressive modulus increased. L929 fibroblast and chondrocytes were cultured on the scaffolds, and all samples exhibited suitable cell attachment and growth, with a high level of biocompatibility. These biodegradable polyurethane scaffolds demonstrate potential for soft tissue engineering applications.

Kiumarsi A.,Iran Institute for Color Science and Technology | Parvinzadeh M.,Islamic Azad University at Tehran
Journal of Applied Polymer Science | Year: 2010

This study confirms the structural changes of nylon 6 fibers using lipase by measuring the dyeability, hydrophilicity, chemical changes, and fastness properties. For this purpose, nylon 6 fabrics were first treated separately with different concentrations of lipase enzyme. The dyeing process was then carried out on the treated fabrics with two disperse and acid dyes. A UV-vis spectrophotometer was used for determination of dyebath exhaustion. Acid and disperse dyes showed higher dyebath exhaustion on the enzyme treated samples compared to raw material. The intensity of major peaks in FTIR spectra of the lipase treated samples are in favor of chemical changes of the polypeptide functional groups in fabric. Tensile strength of treated fabrics was decreased due to enzyme treatment. The results of color measurements in the CIELAB system showed that the darkness of the samples increased with an increase in the enzyme percentage in the solution. The results of moisture regain showed that treatment of nylon fabrics with lipolytic enzymes caused to increase the moisture absorbency. The wash and light fastness properties of samples were measured according to ISO 105-CO5 and Daylight ISO 105-BO1 and discussed. © 2010 Wiley Periodicals, Inc.

Torkaman H.,Islamic Azad University at Tehran | Afjei E.,Shahid Beheshti University
Progress in Electromagnetics Research | Year: 2012

This paper describes the performance characteristics and comparison results of three different types of two-phase switched reluctance motors (SRM). This collection includes conventional, stepped rotor and slanted rotor two-phase SRMs. These motors have four stator poles and two rotor poles, named 4/2 configuration. The main difference between these configurations is their rotor structures. The number of turns and areas of all stator pole faces jointly involving in torque production mechanism in the motors are taken to be equal. The terminal inductance per phase, flux linkage of each stator pole winding, and components of leakage inductances are determined and plotted for different rotor positions and excitation currents. Finally, the static torque for different forced current levels and rotor positions are also presented for each motor.

Amiri I.S.,Islamic Azad University at Tehran | Afroozeh A.,Islamic Azad University at Tehran | Bahadoran M.,Islamic Azad University at Tehran
Chinese Physics Letters | Year: 2011

A novel system of multisoliton generation using nonlinear equations of the propagating signals is presented. This system uses a PANDA ring resonator incorporated with an add/drop filter system. Using resonant conditions, the intense optical fields known as multisolitons can be generated and propagated within a Kerr-type nonlinear medium. The present simulation results show that multisolitons can be controlled by using additional Gaussian pulses input into the add port of the PANDA system. For the soliton pulse in the microring device, a balance should be achieved between dispersion and nonlinear lengths. Chaotic output signals from the PANDA ring resonator are input into the add/drop filter system. Chaotic signals can be filtered by using the add/drop filter system, in which multi dark and bright solitons can be generated. In this work multi dark and bright solitons with an FWHM and an FSR of 425pm and 1.145 nm are generated, respectively, where the Gaussian pulse with a central wavelength of 1.55 μm and power of 600 mW is input into the system. © 2011 Chinese Physical Society and IOP Publishing Ltd.

Hosseinifar M.,Islamic Azad University at Tehran | Ahmadi V.,Tarbiat Modares University | Abaeiani G.,Laser and Optics Research School
Journal of Lightwave Technology | Year: 2011

A novel structure of unitraveling carrier photodiodes (UTC-PDs) with high-speed, high-efficiency, and wavelength selective characteristics is presented. Including the essential features of resonant cavity enhanced photodiodes and waveguide photodiodes, we propose microring-based UTC-PDs (MR-UTC-PDs) which can achieve excellent high-speed and high-quantum efficiency characteristics simultaneously. The photoresponse of MR-UTC-PDs is based on a drift-diffusion model. Photoresponse characteristics of MR-UTC-PDs, which depend on device parameters and coupling conditions, are investigated and it is shown that the overcoupled structures are suitable for high-speed photodetection. The important features of the device, such as efficiency enhancement and wavelength selectivity are discussed and the trade-off between 3 dB bandwidth and efficiency is solved for nanoscaled absorption layer. Additionally, the bandwidth-efficiency product in the order of several hundreds gigahertz can be obtained even with low photoabsorption layers. © 2006 IEEE.

Pedram P.,Islamic Azad University at Tehran
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

In this Letter, we consider the effects of the Generalized (Gravitational) Uncertainty Principle (GUP) on the eigenvalues and the eigenfunctions of the Dirac equation. This form of GUP is consistent with various candidates of quantum gravity such as string theory, loop quantum gravity, doubly special relativity and black hole physics and predicts both a minimum measurable length and a maximum measurable momentum. The modified Hamiltonian contains two additional terms proportional to a(α→p)2 and a2(α→ .p)3 where αi are Dirac matrices and ã1/MPlc is the GUP parameter. For the case of the Dirac free particle and the Dirac particle in a box, we solve the generalized Dirac equation and find the modified energy eigenvalues and eigenfunctions. © 2011 Elsevier B.V.

Yahyaei H.,Islamic Azad University at Tehran | Monajjemi M.,Islamic Azad University at Tehran
Fullerenes Nanotubes and Carbon Nanostructures | Year: 2014

In this investigation, the interaction of Calixarene with amino acid (alanine) with double-walled carbon nanotubes (DWNTs) are examined, with OPLS, Amber and MM+ force field in molecular mechanic (MM) method. The calculations achieved by methods of Monte Carlo simulation in different temperatures. The calculations were carried out using HyperChem professional release 7.01 package of program. We investigate effects of gas phase (ε = 1) and in various solvent media with dielectric constants of water (ε = 78.39), DMSO (ε = 46.8), methanol (ε = 32.63), ethanol (ε = 24.55), CH 2Cl2 (ε = 8.93) at seven temperatures on interaction of Calixarene with DWNTs, utilizing these force fields. The interaction of Calixarene with DWNTs in gas phase and five solvents such as water, DMSO, methanol, ethanol and dichloromethane has been processed applying the ab initio calculations. The calculations have been done with the GAUSSIAN 98 program according to Hartree-Fock (HF) theory at the HF/3-21G level. Thus, by utilizing a Hartree-Fock method, we studied the effects of different solvents on interaction of Calixarene with DWNTs within the Onsager self-consistent reaction field (SCRF) model, as well as the temperature effects on the stability of the interaction between Calixarene with DWNTs in various solvents. © 2014 Taylor and Francis Group, LLC.

Ardalan T.,Islamic Azad University at Tehran | Ardalan P.,Islamic Azad University at Tehran | Monajjemi M.,Islamic Azad University at Tehran
Fullerenes Nanotubes and Carbon Nanostructures | Year: 2014

The physicochemical properties of a novel carbon cluster (C16) and C16 beside vitamin C have been evaluated using Density Functional Theory (DFT) calculation. NMR properties are calculated by using density functional method (B3LYP) with 6-31G, 6-311G* and cc-pvdz as the basis sets. Also natural bond orbital (NBO) and thermodynamic analysis has been performed for C16 cluster and C16 beside vitamin C. Our results indicate that Vitamin C can form stable bindings with C16 cluster via oxygen (O) active site. Thus, we arrive at the prediction that the C16 nanocluster can be implemented as a novel material for vitamin C carrier applications. © 2014 Copyright Taylor & Francis Group, LLC.

Mollaamin F.,Islamic Azad University at Qom | Monajjemi M.,Islamic Azad University at Tehran | Mehrzad J.,Islamic Azad University at Tehran
Fullerenes Nanotubes and Carbon Nanostructures | Year: 2014

The investigation of vinblastine intra single-walled carbon nanotube (SWCNT) has been studied by theoretical methods, and the best structural and functional vinblastine has been established. These results show the minimized structure of vinblastine intra SWCNT, calculated potential energy for important dihedral angles, and the effect of temperature on geometry of optimized structure. However, the vinblastine- SWCNT compound has been displayed different spectrum of gas phase and solvent NMR by GIAO and CSGT approximations, which appears the results of the determination of the number of active sites in vinblastine- SWCNT using the Onsager method that the O29 has the most shifting at indicated model, and it has been reflected mostly the transfer of vinblastine- SWCNT to a less polar environment. © 2014 Copyright Taylor & Francis Group, LLC.

Monajjemi M.,Islamic Azad University at Tehran | Najafpour J.,Islamic Azad University at Tehran
Fullerenes Nanotubes and Carbon Nanostructures | Year: 2014

The relationship between the natural electron charge density in NBO (Natural Bond Orbital) and the electron charge density in QTAIM (Quantum Theory of Atoms in Molecules) of armchair single-walled carbon nanotubes (SWCNTs) with 13C chemical shift are studied at B3LYP/6-31G and B3LYP/6-311+G(d) computational levels. It is shown that increasing the positive electron charge density in NBO is accompanied with increase of the 13C chemical shift. In vice versa the increasing of positive electron charge density in QTAIM is accompanied with decrease of the 13C chemical shift. However there is no relationship between chemical shift and NBO charge with variation of 6-311+G(d) basis set instead 6-31G basis set. © 2014 Copyright Taylor & Francis Group, LLC.

Monajjemi M.,Islamic Azad University at Tehran | Karachi N.,Islamic Azad University at Tehran | Mollaamin F.,Islamic Azad University at Qom
Fullerenes Nanotubes and Carbon Nanostructures | Year: 2014

To investigate carbon nanotubes (CNTs) as gene delivery vehicles, it is essential to characterize their interactions with mRNA. Messenger RNA is a powerful tool for controlling the expression of genes in biomedical applications. In the present report, we study the interactions of single-walled CNT with three codons of mRNA(UGC,GAC,CAG) by using MM, AM1,HF and DFT (B3LYP) methods with STO-3G and 3-21G basis sets in gas phase. To estimate the stability of Nanotubes- mRNA complexes total energy of the systems were determined. The varieties of obtained energy data suggest the relation between the stability of complexes as this order: CAG > GAC > UGC. According to the ability of NMR in providing detailed information about the structure and chemical environment of molecules, this technique has been carried out by supposing gauge-included atomic orbital (GIAO). Considering on the calculated results of NMR chemical shift consist of σiso, σaniso, Δσ, δ and η that are very sensitive to small changes in molecular geometry and chemical environments and the results of energy reveal that the characteristic's variety and the stability of these complexes is depend on the specific mrna base and nucleotide sequences. We can predict that diseases with special mutation and gene sequences are the better aim for special kinds of treatment. Current observations will allow the implementation of new strategies in the development of CNT: mRNA complexes as effective gene therapy. © 2014 Copyright Taylor & Francis Group, LLC.

Esmaeili A.,Islamic Azad University at Tehran | Tavassoli A.,Islamic Azad University at Tehran
Acta Biochimica Polonica | Year: 2010

Thymol is present in the essential oils from herbs and spices, such as thyme. It is produced by these plant species as a chemical defense against phytopathogenic microorganisms. Therefore, this compound has attracted great attention in food industry, i.e., it has been used as a natural preservative in foods such as cheese to prevent fungal growth. Previous studies concerning the biotransformation of nerol by Penicillium sp. and microbial transformation of citral by sporulated surface cultures method (SSCM) of Penicillium digitatum have been reported. The objective of this research was to study the pathway involved during biotransformation of citral by Penicillium sp. using two methods. The culture preparation was done using different microbial methods and incubation periods to obtain Penicillium for citral biotransformation. The biotransformation products were identified by gas chromatography (GC) and gas chromatography/mass spectroscopy (GC/MS). A comparison of the two methods showed that SSCM was more effective, its major products were thymol (21.5 %), geranial (18.6 %) and nerol (13.7 %). LM produced only one compound thymol with a low efficiency.

Jamilian A.,Islamic Azad University at Tehran
International journal of orthodontics (Milwaukee, Wis.) | Year: 2011

The aim of this study was to compare the effects of face mask and miniscrew combined with Class III traction on Class III malocclusion maxillary deficiency in growing patients. 10 patients were treated with facemask and 10 other patients were treated by means of miniscrew and Class III traction. Pre- and post-treatment cephalometric data were analyzed and compared between the two groups. Both groups were successfully treated; however, IMPA increased in miniscrew group while it decreased in facemask group.

Monajjemi M.,Islamic Azad University at Tehran | Ahmadianarog M.,Islamic Azad University at Tehran
Journal of Computational and Theoretical Nanoscience | Year: 2014

Carbon nanotubes have the occasion to act with effective structures that have high drug loading capacities drug delivery phenomena that is taking advantage of nanotube technology. Theoretical methods have been used for investigation of calculation of physical and chemical interaction between single-walled carbon nanotubes (SWCNT) and solforaphane and several similar compounds. Isothiocyanates, such as sulforaphane (SFN) formed in Broccoli vegetable family, are a candidate class of cancer preventive compounds. In this work, the CNT-SFN complex and several similar compounds are tested by nuclear magnetic resonance (NMR) and natural bond orbital (NBO) calculation by using HF, B3LYP, BLYP and B3PW91 methods with 6-31G 6-31G,6-31G* and 6-31+G basis sets by Gaussian 98 program. Atomic charges, energy (ΔE), chemical shift anisotropy (δ), asymmetry parameter (η), chemical shift anisotropy (Δσ) parameters have been gained via GIAO magnetic shielding approximation to analyze the electronic structural effect on CNT-SFN as an anti-cancer in a number of diverse species. Copyright © 2014 American Scientific Publishers.

Shalkouhi P.,Islamic Azad University at Tehran
Building Acoustics | Year: 2012

The goal of this letter is to comments on the article "Empirical Prediction of Speech Levels and Reverberation in Classrooms" by Hodgson (2001). Hodgson proposed an empirical equation for prediction of classroom early decay time. Hodgson EDT equation with regard to the classroom ceiling height was theoretically discussed and it was concluded that when a classroom ceiling height is decreased or increased, it is not reasonable to judge about the acoustical condition of the new space based on the Hodgson EDT equation if the average absorption coefficient of the additional walls is equal to the average absorption coefficient of the original space.

Lotfi N.T.,Islamic Azad University at Tehran
International Journal of Applied Linguistics and English Literature | Year: 2015

This essay is an attempt to examine the active interaction of history and memory, in formulation of a diasporic authentic picture of past, in Amy Tan’s The Bonesetter’s Daughter (2001). Amongst discursive disciplines, memory and history perform vitally, in picturing past; both attempt to reproduce events, by emblematic narrative acts. However, their erratic quality endorses the existence of counter- stories that endangers displaying a homogeneous past. Among miscellaneous categories of memories, autobiographical memory asserts to obtain an authentic presentation, but as any other forms of accounts, it exhibits an imprecise fictional image. This psychological alleviation ensures the future mental integrity of trauma victims. In memory narratives, the contingent temperament of power network and continual formulation of resisting frameworks might be explored. Tan’s diasporic assertion of authenticity, as a migrant writer, amalgamated with employment of fantasy is to obtain a shared diasporic identity, among her characters, although personal accounts of characters undergo an extensive amount of contingency. The newly forged identity is collective in nature and defies the geographical and temporal borders and grants a humane picture rather than a diasporic one; an identity that is established to venerate the cardinal role of personal memory, in endowing legitimate truth. © 2015, Australian International Academic Centre PTY LTD. All rights reserved.

Valadbeigi Y.,Islamic Azad University at Tehran
Molecular Physics | Year: 2016

Structural and thermodynamic properties of 48 trimolecular clusters containing one radicl and two protic molecules (H2O, NH3, H2O2, CH3OH, HOCl) were studied at B3LYP/6-311++G(3df,3pd) level of theory. These radical-clusters have non-cyclic structures and are stabilised via two inter-molecular hydrogen bonding interactions. The calculated enthalpies of formation of the radical-clusters were generally in the range of −30 to −50 kJ/mol. The calculated activation energies (Ea) of the intra-cluster hydrogen transfers were smaller than 70 kJ/mol. Also, structures and thermodynamics of 15 cyclic molecular clusters as well as multi-hydrogen transfers in them were investigated. The results showed that the stability of the cyclic clusters and activation energies of the multi-hydrogen transfers depend on the cluster size. © 2016 Informa UK Limited, trading as Taylor & Francis Group.

The significant reinforcement of polymer nanocomposites containing spherical nanoparticles which exceeds the predictions of classical models is commonly attributed to the formation of an interphase between polymer and nanoparticles. In this article, the Christensen-Lo model for Young's modulus of polymer composites is developed by an "a" interphase parameter. Firstly, the "a" interphase parameter is approximately expressed by nanofiller and interphase properties. Secondly, the Ji model suggested for three phase systems (matrix, filler and interphase) is used to calculate the interphase thickness and modulus. The experimental data of several samples are applied to the developed Christensen-Lo and Ji models to calculate the "a" parameter and interphase properties. At the final step, the "a" parameter is accurately defined as a function of the specific surface area (Ac), density (ρf), modulus (Ef) and radius (r) of nanofiller as well as the thickness (ri) and modulus (Ei) of interphase using the obtained calculations. All the predictions by the developed Christensen-Lo model demonstrate a right consistency with the experimental results, which validate the present analysis. The "a" values are obtained from 0.8 to 19 for several samples showing the different levels of interphase properties in the reported samples. Also, the calculations reveal an inverse correlation between "Ei" and "ri" in the polymer nanocomposites containing spherical nanoparticles. © The Royal Society of Chemistry.

Kazemi M.,Islamic Azad University at Tehran
International Journal of Food Properties | Year: 2015

The present work was designed to study the antioxidant activity and to identify the main active components of the essential oil of Achillea tenuifolia aerial parts. Gas chromatography-mass spectrometry analyses of the essential oil showed the presence of 22 compounds. The main constituents of the oil were thymol (15%), α-pinene (10.11%), Camphene (9.41%), β-pinene (7.54%), α-terpinene (7.21%), p-cymene (4%), 1,8-cineole (2.31%), γ-terpinene (7%), linalool (10%), and carvacrol (20.43%). The antioxidant and free radical scavenging activities of Achillea tenuifolia oil was evaluated by using 2,20-diphenyl-1-picrylhydrazyl assays. The oil exhibited a considerable dose-dependent antioxidant activity. Thymol showed clearly a higher activity (IC50 = 10.04 ± 0.1 μg/ml) followed by Achillea tenuifolia essential oil (15.12 ± 0.4 μg/ml). Antioxidant activity guided fractionation of the oil was carried out by the thin layer chromatography-bioautography screening and fractionation resulted in the separation of the main antioxidant compound which was identified as thymol (80%). Copyright © Taylor & Francis Group, LLC.

Kazemi M.,Islamic Azad University at Tehran
International Journal of Food Properties | Year: 2015

The aim of present study was to evaluation the antioxidant potential of Achillea millefolium on the basis of the chemical compositions of oils obtained by hydrodistillation. In the case of Achillea millefolium, 24 compounds were identified representing the 83.76% of the total oil. The major constituents of the oil were described as α-pinene (10.12%), camphene (4.23%), limonene (5%), borneol (5%), γ-terpinene (8%), carvone (5%), bornyl acetate (2.43%), thymol (15.32%), and carvacrol (20.43%). The oils were also subjected to screening for their possible antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl assays. Thymol (12.0 ± 0.1 g/mL) and carvacrol (14.43 ± 0.0 g/mL) showed appreciable antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl test. Antioxidant activity guided fractionation of the oil was carried out by The TLC-bioautography screening and fractionation resulted in the separation of the main antioxidant compound which were identified as thymol (65%) and carvacrol (25%). © Taylor and Francis Group, LLC.

Abdolmohammadi S.,Islamic Azad University at Tehran | Balalaie S.,K. N. Toosi University of Technology
Combinatorial Chemistry and High Throughput Screening | Year: 2012

A simple one-pot method for the preparation of 7-amino-2,4-dioxo-5-aryl-1, 2,3,4-tetrahydropyrido[2,3- d]pyrimidine-6-carbonitriles 4 from aromatic aldehydes, malononitrile and 4(6)-aminouracil in the presence of ZrO2 nanoparticles (ZrO2 NPs) as an efficient heterogeneous catalyst is described. The procedure has the advantages of high yields (86-97%), short reaction time (2h) and an environmentally friendly specificity. (Figure presented). © 2012 Bentham Science Publishers.

Ghasemzadeh A.,Islamic Azad University at Tehran | Ghasemzadeh N.,Islamic Azad University
Journal of Medicinal Plant Research | Year: 2011

Flavonoids and phenolic acids make up one of the most pervasive groups of plant phenolics. Due to their importance in plants and human health, it would be useful to have a better understanding of flavonoid concentration and biological activities that could indicate their potentials as therapeutic agents, and also for predicting and controlling the quality of medicinal herbs. Plants and herbs consumed by humans may contain thousands of different phenolic acid and flavonoid components. The effect of dietary phenolics is currently of great interest due to their antioxidative and possible anticarcinogenic activities. Phenolic acids and flavonoids also function as reducing agents, free radical scavengers, and quenchers of singlet oxygen formation. In addition, flavonoids and phenolic acids components play important roles in the control of cancer and other human diseases. © 2011 Academic Journals.

Chehri K.,Islamic Azad University at Tehran
African Journal of Microbiology Research | Year: 2011

Plant diseases caused by Fusarium spp. will results in yield losses and are becoming more significant in Iran. In this study, infected plant samples suspected to Fusarium infection, plant debris and rhizosphere soil were collected from the most important crops that is, wheat, rice, corn, barley, potato, cucurbits from different provinces in Iran during 2002 to 2009. A total of 2,500 Fusarium isolates were obtained and classified into 30 species based on morphological characters. Fusarium sporotrichioides, F. chlamydosporum, F. graminearum and F. pseudograminearum were obtained only from tissue samples whereas F. scirpi, F. longipes and F. eumartii were from soils. Among the isolates, 41% were recovered from plant tissue, 36% from soil and 23% from plant debris samples. In cereals tissues, F. graminearum, F. pseudograminearum, F. sambucinum, F. culmorum, F. crookwellense, Fusarium proliferatum, F. verticillioides, F. fujikuroi and F. nygamai were predominant species. Fusarium spp. recovered from potato tissues were F. sambucinum, F. culmorum, F. crookwellense, F. trichothecioides, F. proliferatum, F. verticillioides, F. subglutinans and F. anthophilum whereas F. solani and F. oxysporum were predominant in cucurbits, sorghum, tomato, sugar beet and bean. To our knowledge this is the first comprehensive report on the identification of large number of Fusarium spp. in different crops from Iran. © 2011 Academic Journals.

Kianersi D.,Islamic Azad University at Tehran | Mostafaei A.,Islamic Azad University at Tehran | Amadeh A.A.,University of Tehran
Materials and Design | Year: 2014

In this paper, we aim to optimize welding parameters namely welding current and time in resistance spot welding (RSW) of the austenitic stainless steel sheets grade AISI 316L. Afterward, effect of optimum welding parameters on the resistance spot welding properties and microstructure of AISI 316L austenitic stainless steel sheets has been investigated. Effect of welding current at constant welding time was considered on the weld properties such as weld nugget size, tensile-shear load bearing capacity of welded materials, failure modes, failure energy, ductility, and microstructure of weld nuggets as well. Phase transformations that took place during weld thermal cycle were analyzed in more details including metallographic studies of welding of the austenitic stainless steels. Metallographic images, mechanical properties, electron microscopy photographs and micro-hardness measurements showed that the region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. Backscattered electron scanning microscopic images (BE-SEM) showed various types of delta ferrite in weld nuggets. Three delta ferrite morphologies consist of skeletal, acicular and lathy delta ferrite morphologies formed in resistance spot welded regions as a result of non-equilibrium phases which can be attributed to the fast cooling rate in RSW process and consequently, prediction and explanation of the obtained morphologies based on Schaeffler, WRC-1992 and Pseudo-binary phase diagrams would be a difficult task. © 2014 Elsevier Ltd.

Shirgholami M.A.,Islamic Azad University at Yazd | Shateri Khalil-Abad M.,Islamic Azad University at Yazd | Khajavi R.,Islamic Azad University at Tehran | Yazdanshenas M.E.,Islamic Azad University at Yazd
Journal of Colloid and Interface Science | Year: 2011

Superhydrophobic cotton textiles are prepared by a simple, one-step and inexpensive phase separation method under ambient conditions by which a layer of polymethylsilsesquioxane (PMSQ) nanostructures is covered onto the cellulose fibers. By changing the silane precursor concentration, PMSQ nanostructures with various shapes, morphologies and sizes were fabricated. Nanostructures were characterized using SEM, EDS, and attenuated total reflectance FTIR. The wettability of the modified cellulose surfaces was characterized with contact-angle goniometry and sliding angle technique, respectively. The water contact angle of modified cotton is measured to be higher than 150°, which is high enough to exhibit the lotus effect as a result of the superhydrophobicity. Tunable water-repellent properties of the fabric are also demonstrated, with sliding contact angles varying from " sticky" to " slippery" depending upon different nanostructures on the surface of the fibers. It is expected that this simple technique will accelerate the large-scale production of superhydrophobic cellulosic materials with new industrial applications. © 2011 Elsevier Inc.

Najafi A.,Islamic Azad University | Khademi-Eslam H.,Islamic Azad University at Tehran
BioResources | Year: 2011

The aim of the research was to study the potential of lignocellulosic fillers such as flour of rice hull, wood saw dust, sanding flour from Medium Density Fiberboard (MDF), and sawdust from particleboard as reinforcement for recycled high density polyethylene. Natural filler HDPE composites were made from recycled HDPE and lignocellulosic fillers at 60% by weight filler loadings using a dry blend/hot press method. In all compounds 3 per hundred compound (phc) Maleic Anhydride Polyethylene (MAPE) was used. Nominal density and dimensions of the panels were 1g/cm 3 and 35×35×1 cm. Physical properties of panels including short and long-term of water absorption and thickness swelling and mechanical properties, including flexural modulus, flexural strength, strain at yield, and energy to yield point were studied. Composites containing sanding flour from MDF showed higher short-term values of water absorption and thickness swelling. For the long term, such as maximum values of water absorption and thickness swelling and diffusion coefficient, composites including wood sawdust showed higher values, and composites contain rice hulls exhibited the lowest values. In addition, composites made from sanding flour from MDF showed high value of the swelling rate parameter. Water absorption behavior of studied composites followed Fick's model. The flexural properties of composites were investigated with reference to the effect of filler type. Composites containing sanding flour from MDF and particleboard sawdust exhibited better flexural properties than others and composites containing wood sawdust showed the lowest values.

Yaghoobi H.,Islamic Azad University at Tehran | Torabi M.,Semnan University
Powder Technology | Year: 2012

In this paper, the acceleration motion of a vertically falling non-spherical particle in incompressible Newtonian media was investigated. The instantaneous velocity and acceleration were carried out by using the differential transformation method (DTM) which is an analytical solution technique. The current results were also compared with those derived from the variational iteration method (VIM) and the established fourth-fifth order Runge-Kutta-Fehlberg method in order to verify the accuracy of the proposed method. The analytic solution was found to be in good agreement with the direct numerical solution. After such verifications, the effects of parameters such as sphericity, φ, and the integrated added mass coefficient, C A, on the velocity and acceleration profiles of a falling non-sphere particle in different Newtonian fluids are illustrated and explained. An infinity medium of water, glycerin or ethylene-glycol was considered as liquid phase. Moreover, the results demonstrate that the DTM is very effective in generating analytical solutions for even highly nonlinear problems. © 2012 Elsevier B.V.

Meibodi S.E.,Islamic Azad University at Tehran
World journal of orthodontics | Year: 2010

To investigate the effect of a modified tongue crib appliance in Class II Division 1 patients with anterior tongue thrust and mandibular deficiency. Twenty-three patients (14 females, 9 males) with a mean age of 10.09 ± 1.02 years, a moderate Class II Division 1 occlusion due to a mandibular deficiency, and a mean overbite of -1.1 ± 0.8 mm were treated with a mandibular tongue crib device. Pre- and posttreatment lateral cephalograms were obtained and traced, and various angular and linear variables were measured. These measurements were compared using the paired t test. The statistical assessment indicated that SNB, facial angle, B-VL, Pog-VL, and interincisal angle increased significantly. IMPA, 1-SN, ANB, and Wits appraisal were significantly decreased (P<.05). The changes of Jarabak Index, SN-MP, SNA, and Y-axis were not significant. In addition, the overjet was reduced. During the mixed dentition phase, a tongue crib appliance in the mandible is helpful to impede tongue thrust and stimulate mandibular growth. COPYRIGHT © 2009 BY QUINTESSENCE PUBLISHING CO, INC.

Asemi S.R.,Islamic Azad University at Damavand | Farajpour A.,Islamic Azad University at Tehran | Mohammadi M.,Islamic Azad University at Ahvāz
Composite Structures | Year: 2014

In this paper, a nonlinear continuum model is developed for the large amplitude vibration of nanoelectromechanical resonators using piezoelectric nanofilms (PNFs) under external electric voltage. Hamilton's principle in conjunction with von Karman's theory is employed to derive the differential equations of motion. Size effects are incorporated into both the governing equations and in-plane boundary conditions using nonlocal continuum mechanics. Explicit expressions are presented for the nonlinear natural frequencies and critical electric voltages of PNFs. In comparison to the available experimental data and molecular dynamics simulation results, the present nonlocal model with reasonable small scale parameters results in more accurate estimation of natural frequencies than the classical theory of plates. It is anticipated that the results of the present work would be helpful in experimental characterization of the mechanical properties of piezoelectric nanoresonators. © 2014 Elsevier Ltd.

Ghorbanzadeh Ahangari M.,University of Mazandaran | Fereidoon A.,Semnan University | Jahanshahi M.,Institute of Chemical Technology | Sharifi N.,Islamic Azad University at Tehran
Composites Part B: Engineering | Year: 2014

Microcapsules containing self-healing agents have been used to repair microcracks in polymeric matrices. These microcapsules must possess special properties, such as appropriate strength and stability in the surrounding matrix. Herein, poly(urea-formaldehyde) (PUF) microcapsules containing dicyclopentadiene (DCPD) were prepared by in situ polymerization. The elastic modulus and hardness of the microcapsules with and without a nanocomposite shell wall reinforced with carbon nanotubes and nanoalumina were examined using the nanoindentation method. The surface morphology, topography and roughness were investigated with scanning electron microscopy (SEM), optical microscope (OM), as well as atomic force microscopy (AFM). The results demonstrated significant increases in the elastic modulus and hardness due to the presence of reinforcement nanoparticles. In addition, it has been founded that the microcapsules with nanoalumina in the shell wall were stiffer and harder than the other microcapsules. The surface roughness parameters obtained from the AFM images showed that the nanoalumina nanoparticles resulted in a smoother surface of the microcapsules. In addition, the absence of nanoparticles in the shell wall resulted in the formation of microcapsules with rougher surfaces. Finally, the calculated plasticity index for the microcapsules increased with the addition of the nanoparticles. The results indicate that the PUF shell behaves as a viscoelastic-plastic material. © 2013 Elsevier Ltd. All rights reserved.

Esmaeili A.,Islamic Azad University at Tehran | Niknam S.,Islamic Azad University at Tehran
Flavour and Fragrance Journal | Year: 2013

Nanocapsules loaded with bioactive compounds derived from medicinal plants have numerous possibilities in the development of biochemical delivery systems. Elaeagnus angustifolia L., commonly known as Russian olive, is used in traditional medicinal in the Middle East as an analgesic for arthritis and joint pain. Because E. angustifolia contains vitamin A, vitamin B, abundant calcium, and vitamin K, an effective coagulant, it has been considered as potentially beneficial in wound healing and scar formation, as well as in the treatment or prevention of osteoporosis. Nanocapsules containing an E. angustifolia-filled core can be fabricated employing polymerization. In this process, nanocapsules are prepared using poly ethylene glycol-poly butylene adipate-poly ethylene glycol (PEG-PBA-PEG) as a shell surrounding a core of E. angustifolia and olive oil. In this study, the relative proportions of polymer and oil, concentrations of polymer and bioactive compound, and presence or absence of various surfactants in different concentrations were investigated in relation to the particle size of the final product. A comparison of samples obtained using the surfactants Tween 80, Tween 60, poly vinyl alcohol (PVA), mixed Tween 80 and PVA, and mixed Tween 80 and Tween 60 showed Tween 80 to result in the smallest particle size. An oil-to-polymer ratio of 1:0.25 resulted in the smallest nanoparticle size. Smaller nanoparticles sizes were obtained using lower concentrations of polymer and higher concentrations of the bioactive compound. Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, particle size analysis, and scanning electron microscopy were used to identify and characterize the nanocapsules. © 2013 John Wiley & Sons, Ltd.

Nazari A.G.,Islamic Azad University at Tehran | Mozafari M.,Amirkabir University of Technology
Advanced Powder Technology | Year: 2012

In this study, structural features of alumina-titanium diboride nanocomposite (Al 2O 3-TiB 2) were simulated from the mixture of titanium dioxide, boric acid and pure aluminum as raw materials via mechanochemical process using the optimized artificial neural network. The phase transformation and structural evolutions during the mechanochemical process were characterized using X-ray powder diffractometry (XRD). For better understanding the refining crystallite size and amorphization phenomena during the milling, XRD data were modeled and simulated by artificial neural network (ANN). An ANN consisting of three layers of neurons was trained using a back-propagation learning rule. Also, the ANN was optimized by Taguchi method. Additionally, the crystallite size, interplanar distance, amorphization degree and lattice strain were compared for the simulated values and experimental results. © 2011 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

Montazer M.,Amirkabir University of Technology | Pakdel E.,Islamic Azad University at Tehran | Moghadam M.B.,Allame Tabatabaee University
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2011

One of the main problems of wool as an important proteinous fiber is low resistance against alkali media. Finding a way to solve this problem without any influences on other fiber characteristics is still a matter of research. Using nano particles on textile materials is a new approach to produce novel properties. Here, nano titanium dioxide (NTO) particles along with butane tetra carboxylic acid (BTCA) were sonicated in the ultra sound bath and applied as a nano colloid on the wool fabric. BTCA played different roles as wool cross-linker, a polyanionic agent, and stabilizer for nano TiO2. Various concentrations of NTO and BTCA were applied through impregnation of the fabric in ultrasonic bath followed by curing. The resistance of fabrics against alkali was assessed by solubility in sodium hydroxide and the hydrophilicity monitored by the water drop absorption time and the contact angle before and after UV irradiation. Interestingly, the alkali solubility of the nano TiO2 treated wool fabrics reduced while the fabric became more hydrophilic. This fact was shown by the testing results and is thoroughly discussed in the article. The response surface methodology (RSM) was also applied to find the optimum conditions for the wool fabric treatment. © 2010 Elsevier B.V.

Shirazi M.M.A.,Islamic Azad University at Omidieh | Kargari A.,Amirkabir University of Technology | Shirazi M.J.A.,Islamic Azad University at Tehran
Desalination and Water Treatment | Year: 2012

Membrane distillation (MD) is a non-isothermal membrane separation process. It is based on the phenomenon that pure water in its vapor state can be extracted from aqueous solutions, with vapor passing through a hydrophobic microporous membrane when a temperature difference is established across it. In this work, three commercially available hydrophobic microporous membranes were used for seawater desalination via direct contact MD. The effects of pertinent operating parameters on the permeation flux have been studied. A plate and frame module was used for seawater desalination. Long-term performance evaluation was carried out to evaluate the process as a stand-alone desalination alternative. The results indicated that polytetrafluoroethylene membrane had the best performance when a hot feed temperature of 80 °C with 800 ml/min flow rate was used. At optimum condition a 99.99% salt rejection was achieved. © 2012 Desalination Publications. All rights reserved.

Sadi-Nezhad S.,Islamic Azad University at Tehran | Damghani K.K.,Islamic Azad University at Tehran
Applied Soft Computing Journal | Year: 2010

In this paper we have presented a TOPSIS approach based on preference ratio and an efficient fuzzy distance measurement for a Fuzzy Multiple Criteria Group Decision-Making Problem (FMCGDMP). Preference ratio with a moderate modification for negative fuzzy numbers was used as an efficient ranking method for fuzzy numbers in a relative manner. As human reasoning persuades that distances between two fuzzy numbers should be a fuzzy measure, so all distances between fuzzy numbers (i.e. distances between alternatives, Fuzzy Positive Ideal solutions, and Fuzzy Negative Ideal solutions) have been calculated as fuzzy numbers using an efficient fuzzy distance measurement. The aforementioned arguments make the proposed algorithm unique and well posed for real-life problem modeling. Moreover, the main novelties of the proposed procedure (i.e. the fuzzy distance measurement and Preference Ratio) have been developed for Generalized Fuzzy Numbers (GFNs). The proposed algorithm has efficiently been applied in assessment of traffic police centers which is treated as a FMCGDMP. © 2009 Elsevier B.V. All rights reserved.

Kutanaee H.N.,Islamic Azad University at Tehran
African Journal of Microbiology Research | Year: 2011

This paper reports preparation of four samples of styrene - acrylic emulsion copolymers. It was performed in the presence of acrylic- acid, acryl amid, ammonium persulfate as a free radical initiator and sodium dodecyl benzene sulfate as an anionic emulsifier at 80°C. The resulting Ag nanoparticleloaded grafted fabric was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis. The Ag nanoparticles were almost nodisperse in nature and their average diameter was approximately 12.5 nm. The fabric shows antibacterial activity against Escherichia coli depending upon the extent of grafting of the polymer network onto the fabric and the amount of nano Ag loaded into the grafted fabric. The synthesized emulsion copolymers was formulated by pigmented printing paste in the presence of an acrylic thickener in two different concentrations of 3 and 5% then printed on cotton and polyester/ cotton blend fabrics and then dried at 95°C at 2 min and then fixation at 150°C at 3 min. The characteristics of cured prints such as paste add-on, colour fastness K/S together with fabrics stiffness. The highest K/S is obtained and the fastness properties range between good and excellent for samples printed using methyl metha acrylate styrene (MMA) and lowest K/S is obtained in case of using ethyl acrylate styrene (EA) as a commercial binder. © 2011 Academic Journals.

Rashidian M.,Islamic Azad University at Tehran | Dorranian D.,Islamic Azad University at Tehran
Optical Engineering | Year: 2012

The effect of concentration on the optical nonlinearity of gold nanoparticles is investigated. Gold nanoparticles were synthesized by nanosecond-pulsed laser ablation of a high-purity gold plate in distilled water. The size of nanoparticles was measured using dynamic light scattering (DLS) method and was calculated from full width half maximum of their plasmonic absorption peak using Mie theory. Different nonlinear characteristics of gold nanoparticles are observed by considering their effects under irradiation with a second harmonic beam of a continuouswave low power Nd-YAG laser at 532 nm. Low-power optical limiting with low limiting threshold is obtained in the sample using different apertures at different points of the laser beam path. The nonlinear optical responses are characterized by measuring the intensity dependent refractive index of medium using the z-scan technique. Results show that the linear absorption coefficient and nonlinear refractive index of samples are increased with increasing the concentration of gold nanoparticles in distilled water. Increasing the intensity of the probe beam leads to increasing the magnitude of nonlinear refractive index. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).

Azizi A.,Islamic Azad University at Tehran | Rezaee M.,Islamic Azad University at Tehran
Dermatology Research and Practice | Year: 2012

Background and Objective. Oral lichen planus (OLP) is a common chronic mucocutaneous disease. OLP can occur in different oral sites such as gingiva. The purpose of study was to evaluate the periodontal status of OLP patients with desquamative gingivitis (DG) and compare it with that of healthy control. Methods. This study was case-control. 32 patients with gingival OLP as a case group and 32 healthy subjects as a control group were selected. The periodontal status of all subjects including plaque index (PI), bleeding on probing (BOP), and clinical attachment level (CAL) was evaluated in both groups. Finally data were analyzed by t-test. Results. The mean values of periodontal parameters were observed to be higher in case group compared with control group, and this was significant (P<0.05). Conclusion. Our results showed that periodontal status is worse in gingival OLP if compared with healthy controls. © 2012 Arash Azizi and Massoud Rezaee.

Biati A.,Islamic Azad University at Tehran | Karbassi A.R.,University of Tehran
International Journal of Environmental Science and Technology | Year: 2010

During estuarine mixing, dissolved metals come into the particulate phase due to the flocculation processes. Such processes are biologically vital. In the present study, controlling mechanisms of elemental flocculation during estuarine mixing in northern and southern estuaries of Iran in relation to the various physical and chemical parameters of waters have been compared. Except for zinc and lead, for other studied elements in Minab River, water flocculate at higher rates in comparison with the rivers flowing into the Caspian Sea. Redox potential might have negative effect on flocculation process in Minab Estuary. Contrary to rivers flowing into the Caspian Sea, in Minab River elemental flocculation is governed by dissolved organic carbon and it shows a non-liner and conservative behavior during estuarine mixing which implies that dissolved organic carbon originates from terrigenous source. The results also shows that maximum removal of elements occurs in lower salinities (1.5 to 5.8 ‰) for the rivers in North of Iran and 3.3 to 11.4 ‰ for Minab River in South of Iran. Flocculation of studied metal in different rivers results in reduction of overall metal pollution load by various percentages. The initial metal contents on river water and mean discharge of river might lead to higher flocculation rates. © IRSEN, CEERS, IAU.

Zare Y.,Islamic Azad University at Tehran
Synthetic Metals | Year: 2015

Carbon nanotubes (CNT) show significant mechanical, thermal, and electrical properties. Therefore, CNT is a good candidate for enhancement of polymer properties. Many researchers have tried to study the various characteristics of polymer/CNT nanocomposites (PCNTs) from experimental and theoretical points of view. This paper aims to predict the tensile modulus of PCNTs by a simple methodology. The experimentally measured modulus of many PCNTs from valid literature is correlated with various powers of CNT volume fractions ("φ", "φ1/2" and "φ2/3") and the best equation is chosen from analysis of calculations. It is found that the experimental moduli are well connected to "φ2/3" by maximum 10% disagreement between experimental and theoretical results. © 2015 Elsevier B.V.

Elahi A.S.,Islamic Azad University at Tehran | Ghoranneviss M.,Islamic Azad University at Tehran
Journal of Fusion Energy | Year: 2012

An analytical technique for the determination of toroidal plasma displacement is presented. First, the plasma horizontal position is calculated from the external vertical field coil characteristics. The calculation is made focusing on the external vertical field coil current and voltage changes due to a horizontal displacement of plasma column. Also for comparison of result, a set of magnetic probes were designed, constructed and used. The results from these two techniques are compared and discussed. © Springer Science+Business Media, LLC 2011.

Hasheminejad S.M.,Islamic Azad University at Tehran | Motaaleghi M.A.,Islamic Azad University at Tehran
International Journal of Structural Stability and Dynamics | Year: 2014

In this paper, active flutter suppression of a simply supported circular sandwich cylindrical shell with a tunable electrorheological fluid (ERF) core, under axial supersonic gas flow, is studied. The structural analysis is based on the classical thin shell theory, the ERF core is modeled as a first-order Kelvin-Voigt material, and the Krumhaar's modified supersonic piston theory is utilized to model the aerodynamic loading. Hamilton's principle is used to formulate the dynamic equations of motion together with the relevant boundary conditions. The generalized Fourier expansions in the circumferential and axial directions in conjunction with the classical Galerkin method are employed to set up the governing equations in the state-space domain. The critical free stream static pressures at which unstable oscillations arise are calculated for selected applied electric field strengths and cylinder length ratios. The Runge-Kutta time integration algorithm is used to determine the open-loop aeroelastic response of the system in two basic loading configurations, namely, a concentrated impulse point load and a sonic boom line load. Subsequently, a sliding mode control (SMC) strategy is adopted to actively suppress the closed loop system dynamic response in supersonic flight condition. Simulation results demonstrate performance and effectiveness of the adopted ERF-based SMC scheme. Limiting cases are considered and good agreements with the data available in the literature are obtained. © 2014 World Scientific Publishing Company.

Yazdani-Chamzini A.,Islamic Azad University at Tehran
Journal of Civil Engineering and Management | Year: 2014

Tunnels are artificial underground spaces that provide a capacity for particular goals such as storage, under-ground transportation, mine development, power and water treatment plants, civil defence. This shows that the tunnel construction is a key activity in developing infrastructure projects. In many situations, tunnelling projects find themselves involved in the situations where unexpected conditions threaten the continuity of the project. Such situations can arise from the prior knowledge limited by the underground unknown conditions. Therefore, a risk analysis that can take into account the uncertainties associated with the underground projects is needed to assess the existing risks and prioritize them for further protective measures and decisions in order to reduce, mitigate and/or even eliminate the risks involved in the project. For this reason, this paper proposes a risk assessment model based on the concepts of fuzzy set theory to evaluate risk events during the tunnel construction operations. To show the effectiveness of the proposed model, the results of the model are compared with those of the conventional risk assessment. The results demonstrate that the fuzzy inference system has a great potential to accurately model such problems. © 2014 Copyright © 2014 Vilnius Gediminas Technical University (VGTU) Press.

Yazdani-Chamzini A.,Islamic Azad University at Tehran
Journal of Civil Engineering and Management | Year: 2014

The problem of handling equipment selection plays a significant role in the total cost of a mining project; so that it can affect the activity and continuity of the project and is a strategic problem. In this study, an integrated model based on two fuzzy multi-criteria decision making techniques for handling equipment selection is proposed. The proposed evaluation model is derived from group decision making, fuzzy set theory, analytical hierarchy process (AHP), and Technique to Order Preference by Similarity to Ideal Solution (TOPSIS) methods. The fuzzy AHP (FAHP) method is utilized to calculate the relative importance of the evaluation criteria, then, fuzzy TOPSIS (FTOPSIS) is applied for evaluating the feasible handling equipment in order to select the best handling system among a pool of the possible alternatives. The model is applied for a real world case study to demonstrate the capability and effectiveness of the proposed model. To investigate the result sensitiveness to the changes of the criteria weights, a sensitivity analysis is finally conducted. © 2014 Vilnius Gediminas Technical University (VGTU) Press.

Najafi M.,Islamic Azad University at Tehran | Enjilela V.,Islamic Azad University at Tehran
Engineering Analysis with Boundary Elements | Year: 2014

The meshless local Petrov-Galerkin (MLPG) method is extended using an improved primitive variable formulation to solve the two-dimensional laminar natural convection equations. The extended method solves the natural convection heat transfer problems at high Rayleigh numbers. The method uses the fractional step scheme for discretization, and the moving least square (MLS) interpolation for approximation of the field variables. For the proposed technique, a weighting function of unity is used. The improved method considers the natural convection in a square cavity for up to and including Ra=108, in a concentric square outer cylinder and circular inner cylinder annulus for up to and including Ra=107, and in a two concentric circular cylinders annulus for up to and including Ra=105. Comparing the results of the three test cases obtained using the present method with those obtained using the conventional methods shows very good agreement existing among the appropriate results, hence, verifying the proposed improved meshless numerical technique. © 2014 Elsevier Ltd.

Rashidi Mehrabadi M.H.,Islamic Azad University at Tehran | Saghafian B.,Islamic Azad University at Tehran | Haghighi Fashi F.,Soil Conservation and Watershed Management Research Institute
Resources, Conservation and Recycling | Year: 2013

Global demand for clean water supplies is on the rise due to population growth. This is also true in most cities of Iran. Non-conventional water resources must be developed to partially offset the increasing demand. In this study, the applicability and performance of rainwater harvesting (RWH) systems to supply daily non-potable water were assessed. Storage of rain falling on the roofs of residential buildings and directed into installed tanks was simulated in three cities of varying climatic conditions, namely Tabriz (Mediterranean climate), Rasht (humid climate), and Kerman (arid climate). Daily rainfall statistics for a period of 53 years as well as the information on the contributing roof area, available tank volumes and non-potable water demand were collected in each city. Typical residential buildings with roof areas of 60, 120, 180 and 240 m2 with an average of four residents in each house were considered for the study. According to the results in humid climate, it is possible to supply at least 75% of non-potable water demand by storing rainwater from larger roof areas for a maximum duration of 70% of the times. For roofs with small surface area, the supply meets 75% of non-potable water demand for a maximum duration of 45% of the times. Moreover, for Mediterranean climate, it is possible to supply at least 75% of non-potable water demand in buildings with larger roof areas for a maximum duration of 40% of the times. It is also found that in arid climate, similar duration is only 23% of the times. © 2013 Elsevier B.V.

Karimi-Nasab M.,Islamic Azad University at Tehran | Sabri-Laghaie K.,Iran University of Science and Technology
International Journal of Production Research | Year: 2014

This paper formulates a new imperfect production problem that generates defectives randomly. The production manager conducts total inspections to screen defectives (including reworkable and non-reworkable items) from non-defectives. But, the inspection is error-prone due to different sources. The model determines rates of main and rework processes, batch size and backlog. As the model is a nonlinear programme and it is difficult to obtain an algebraic closed-form solution, three randomised approximation algorithms are developed. Under certain conditions, the algorithms can find the global optimum in polynomial time. Finally numerical analyses are reported. © 2013 Taylor & Francis.

Hani A.,Islamic Azad University at Sāveh | Pazira E.,Islamic Azad University at Tehran
Environmental Monitoring and Assessment | Year: 2011

A detailed investigation was conducted to evaluate heavy metal sources and their spatial distribution in agricultural fields in the south of Tehran using statistics, geostatistics, and a geographic information system. The content of Cd, Cu, Co, Pb, Zn, Cr, and Ni were determined in 106 samples. The results showed that the primary inputs of Cr, Co, and Ni were due to pedogenic factors, while the inputs of Zn, Pb, and Cu were due to anthropogenic sources. Cd was associated with distinct sources, such as agricultural and industrial pollution. Ordinary kriging was carried out to map the spatial patters of heavy metals, and disjunctive kriging was used to quantify the probability of heavy metal concentrations higher than their recommended threshold values. The results show that Cd, Cu, Ni, and Zn exhibit pollution risk in the study area. The sources of the high pollution levels evaluated were related to the use of urban and industrial wastewater and agricultural practices. These results are useful for the development of proper management strategies for remediation practices in the polluted area. © 2010 Springer Science+Business Media B.V.

Samadizadeh M.,Islamic Azad University at Central Tehran | Rastegar S.F.,Islamic Azad University at Tehran | Peyghan A.A.,Islamic Azad University at Tehran
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2015

Adsorption of two anions (F- and Cl-) and two cations (Li+ and Na+) on the surface of aluminum nitride nanotubes (AlNNTs) is investigated by density functional theory. The reactions are site-selective, so that the cations and anions prefer to be adsorbed atop the N and Al atoms of the tube surface, respectively. The adsorption energies of anions (-4.46 eV for F- and -1.12 eV for Cl-) are much higher than those of cations (about -0.17 eV for Li+ and -0.12 eV for Na+) which can be explained using frontier molecular orbital theory. It was found that the adsorption of anions may facilitate the electron emission from the AlNNT surface by reducing the work function due to the charge transfer occurs from the anions to the tube. It has been predicted that in contrast to the cations the adsorption of anions also obviously increases the electrical conductivity of AlNNT. © 2015 Published by Elsevier B.V.

Peyghan A.A.,Islamic Azad University at Tehran | Noei M.,Islamic Azad University at Mahshahr
Computational Materials Science | Year: 2014

We investigated the electronic sensitivity of a BC2N nanotube to a HF molecule by density functional calculations at B3LYP (augmented with an empirical dispersion term) level of theory. It was found that the HF molecule prefers to be weakly adsorbed on the tube with the adsorption energy of 23.1 kcal/mol and without significant effect on its electronic properties. Al and Si dopings into the wall of the tube increase the reactivity of the tube toward the HF molecule, so that calculated adsorption energies are about 92.8 and 73.0 kcal/mol, respectively. Contrary to the Al doping, the Si doping significantly enhances the electronic sensitivity of the tube to the HF molecule. We believe that Si-doped BC2N nanotube can convert the presence of HF molecules to an electrical signal which will be useful in the detection process. © 2013 Elsevier B.V. All rights reserved.

Mousavi Anzehaee M.,Islamic Azad University at Tehran | Haeri M.,Islamic Azad University at Tehran
ISA Transactions | Year: 2011

New estimators are designed based on the modified force balance model to estimate the detaching droplet size, detached droplet size, and mean value of droplet detachment frequency in a gas metal arc welding process. The proper droplet size for the process to be in the projected spray transfer mode is determined based on the modified force balance model and the designed estimators. Finally, the droplet size and the melting rate are controlled using two proportionalintegral (PI) controllers to achieve high weld quality by retaining the transfer mode and generating appropriate signals as inputs of the weld geometry control loop. © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

Haghighatzadeh A.,Islamic Azad University at Tehran | Golnabi H.,Sharif University of Technology
Optics Communications | Year: 2011

In this paper, an optical beam shaping system is theoretically and experimentally investigated. The optical system design software ZEMAX is used to simulate and analyze the reported beam shaping design. By using this software ray tracing diagrams are presented with the aim of studying the direct beam propagation, total reflection rays, and the lost rays. The prism duct output beam shape and radiance profiles in both position space and angle space are also studied. For experimental investigation, a two-stage beam shaping design including a fiber-bundle and a prism duct is used. A source light is used for the fiber-bundle illumination and the photograph image of the output beam is taken by a digital camera. The fiber-bundle output beam cross section is a rectangular shape with a dimension of 25.65 mm width and 2.44 mm height. In another experiment, the prism output beam is captured by a CCD camera. The prism output beam shape depends on the prism exit face, which is a rectangle (4.15 mm × 3.55 mm) for this case. The image date of the prism output beam is converted to a response curve, which is approximately a flat-top profile. The experimental image profiles are compared with the simulated image profiles and there is a good agreement between the observed results. © 2011 Elsevier B.V. All rights reserved.

Kord B.,Islamic Azad University | Hemmasi A.H.,Islamic Azad University at Tehran | Ghasemi I.,Iran Polymer And Petrochemical Institute
Wood Science and Technology | Year: 2011

In this research, composites based on polypropylene (PP), beech wood flour, and organomodified montmorillonite (OMMT) were prepared and characterized for their properties. The blend nanocomposites were prepared by melt mixing of PP/WF at 50% weight ratios with various amounts of OMMT (0, 3, and 6 per hundred compounds (phc)) in a Hakee internal mixer. Then the samples were made by injection molding. The influence of organomodified montmorillonite contents on clay dispersion, physical and mechanical properties of PP/wood flour composites were investigated. Results indicated that the flexural strength and modulus, tensile strength and modulus increased by addition of 3 per hundred compounds (phc) of organomodified montmorillonite (OMMT), but decreased with 6 phc OMMT addition. However, impact strength, water absorption and thickness swelling of the composites decreased with increasing nanoclay loading. X-ray diffraction patterns (XRD) and transmission electron microscopy (TEM) revealed that the nanocomposites formed were intercalated. Also, morphological findings showed that samples containing 3 phc of OMMT had higher order of intercalation. © 2010 Springer-Verlag.

Montazer M.,Amirkabir University of Technology | Pakdel E.,Islamic Azad University at Tehran
Journal of the Textile Institute | Year: 2011

Wool is a textile material that is valued for its strength, warmth, water resistance, and texture. But this natural fiber of the protein keratin lacks the stain resistance of synthetic fabrics and is also generally susceptible to harsh processing conditions. In this study, raw and oxidized wool fabrics were treated with nano titanium dioxide (TiO2) powder in an ultrasonic bath. These particles were linked to the wool surface by butane tetra carboxylic acid and also sodium hypophosphite was used as a catalyst. The photo-catalytic activity of TiO2 nanoparticles deposited on the wool fabrics was followed by the degradation of Acid Blue 113 as a stain and also determined by the degradation rate of food stains such as coffee, tea, and fruit juice under the ultraviolet rays. The results showed that increasing the amount of nano TiO2 leads to improved degradation of stains on the treated fabric. © 2011 The Textile Institute.

Majlesi K.,Islamic Azad University at Tehran | Rezaienejad S.,Islamic Azad University at Tehran
Journal of Chemical and Engineering Data | Year: 2011

Potentiometric and UV spectroscopic measurements have been carried out to determine the stability constants for the complexation of the MoO 4 2- ion with d-(-)-quinic acid {(1R,3R,4S,5R)-(-)-1,3,4,5- tetrahydroxycyclohexane-1-carboxylic acid} in sodium chloride aqueous solutions for ionic strengths between (0.10 to 1.00) mol·L-1 of sodium chloride at T = 298 K. The Job method of continuous variations was applied for the determination of the metal-to-ligand ratio which was 1:1 at pH = 6.50. Extended Debye-Hückel type (EDH), specific ion interaction theory (SIT), and parabolic equations were investigated to derive the necessary ionic strength dependence parameters, and the results were justified. © 2011 American Chemical Society.

Dehghani S.,Islamic Azad University at Tehran
Oriental Journal of Chemistry | Year: 2016

The electronic structure and magnetic properties of Al2 O3 , GaN and Fe3 O4 @ Calix (8) COOH have been studied using ONIOM and DFT methods. The studies focus on how to improve the adsorption of some nano particles solution aqueous for achieving good magnetic and functionalized potential performances. The results revealed that the Fe3O4@ Calix (8) COOH and some of its derivations exhibited better thermodynamic stability. Furthermore, the particle size and magnetic property of the GaN@ Calix (8) COOH nanoparticles can be controlled by the aqueous. The electrical properties such as NMR Shielding, electron densities, energy densities, potential energy densities, ELF, LOL, ellipticity of electron density, eta index and ECP for nanoparticles@ Calix (8)COOH have been calculated.

Nourimajd Z.,Islamic Azad University at Tehran
Oriental Journal of Chemistry | Year: 2016

In this work we have simulated our system based on the various distribution diameters of SWCNTs, SWBNNTs and DWCNTs in three forms of zigzag, armchair and chiral. We have start for answering to some question about the mechanical, electronical and thermochemical properties of the diameter distribution on the various nanotubes, band gape, and potential difference between two layers of a nano cylindrical and finally the radial charge distribution of those systems. It is found that the energy gaps and the energy of those SWBNNTs are strongly dependent on their Chirality and diameters. The energy gap of the formed double-walled (DW-C&BN-NTs )can even be much reduced due to the coupled effect of wall buckling difference and inter-wall p-p∗ hybridization.

Ghiasi R.,Islamic Azad University at Tehran | Mokarram E.E.,Islamic Azad University at Tehran
Russian Journal of Coordination Chemistry/Koordinatsionnaya Khimiya | Year: 2011

The electronic structure and properties of the heterocyclic platinabenzenes isomers have been investigated using the hybrid density functional B3LYP theory. Basic measures of aromatic character were derived from the structure and nucleus-independent chemical shift (NICS). The energetic criterion suggests that the ortho-isomer enjoy conspicuous stabilization where heteroatom is P or As. But the meta-isomer is most stable isomer, where heteroatom is N. The NICS values calculated at several points above the ring center to gave the result consistent with that cased on the relative energy. The atoms in molecules analysis indicates a correlation between NICS(1.0) and the electron density of ring critical point in all species. The natural bond orbital analysis has been used to study the bond characterizations in all species. © 2011 Pleiades Publishing, Ltd.

Pazand K.,Islamic Azad University at Tehran
Environmental Nanotechnology, Monitoring and Management | Year: 2015

Abstract About 478 coal and coaly shale samples were collected to study the selenium content and distribution pattern in Iranian coals in different coal basins. Most Iranian coals have selenium coals lower than 31.5 ppm. The average Se content in Iranian coals is about 1.2 ppm, close to that in the world. The Ksashan coal basin has lowest levels of average Se (0.9 ppm) accumulation. The Se concentration in Iranian coals is influenced by metamorphism and tectonic conditions. The highest concentration of Se in coal-bearing deposits is at Kalishur (31.5 ppm) in Tabas coal basin. © 2014 The Author.

Hajjari T.,Islamic Azad University at Firoozkooh | Abbasbandy S.,Islamic Azad University at Tehran
Expert Systems with Applications | Year: 2011

Recently, Asady [(2010). The revised method of ranking LR fuzzy number based on deviation degree. Expert Systems with Applications, 37, 5056-5060] pointed out that Wang et al.'s method has some drawback by a numerical example and then Wang's method is modified to present an easy way to rank fuzzy numbers. In this note, we will indicate that Asady's revision has a shortcoming exactly as the same as Wang's method. © 2010 Elsevier Ltd. All rights reserved.

Azadi M.,Islamic Azad University at Tehran | Saen R.F.,Islamic Azad University at Karaj
Expert Systems with Applications | Year: 2011

Outsourcing in logistics is a very significant theme and third-party reverse logistics (3PL) provider evaluation and selection has to be realized in a careful manner in order to provide the expected benefits. In this paper a new chance-constrained data envelopment analysis (CCDEA) approach is proposed to assist the decision makers to determine the most appropriate third-party reverse logistics (3PL) providers in the presence of both dual-role factors and stochastic data. A numerical example demonstrates the application of the proposed model. © 2010 Elsevier Ltd. All rights reserved.

Saghaei H.,Islamic Azad University at Tehran | Ebnali-Heidari M.,Shahrekord University | Moravvej-Farshi M.K.,Tarbiat Modares University
Applied Optics | Year: 2015

Using numerical analysis, we compare the results of optofluidic and rod filling techniques for the broadening of supercontinuum spectra generated by As2Se3 chalcogenide photonic crystal fibers (PCFs). The numerical results show that when air-holes constituting the innermost ring in a PCF made of As2Se3-based chalcogenide glass are filled with rods of As2S3-based chalcogenide glass, over a wide range of mid-IR wavelengths, an ultra-flattened near-zero dispersion can be obtained, while the total loss is negligible and the PCF nonlinearity is very high. The simulations also show that when a 50 fs input optical pulse of 10 kW peak power and center wavelength of 4.6 μm is launched into a 50mm long rod-filled chalcogenide PCF, a ripple-free spectral broadening as wide as 3.86 μm can be obtained. © 2015 Optical Society of America.

Khajavi R.,Islamic Azad University at Tehran | Berendjchi A.,Islamic Azad University at Tehran
ACS Applied Materials and Interfaces | Year: 2014

In this study, the effect of dicarboxylic acid chain length on the amount of TiO2 nanoparticles (TiO2NPs) adsorption-produced self-cleaning property and washing durability on cotton fabrics were investigated. First, cotton fabric samples were treated with three kinds of dicarboxylic acids-oxalic, succinic, and adipic acids-and then dipped in TiO2NP solution with a certain concentration. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used to investigate bonds formation between dicarboxylic acid groups and hydroxyl groups of cellulose, and a scanning electron microscope (SEM) was applied for the analysis of surface morphology in specimens. Drop absorbency time was determined for samples using the AATCC TM 79:2000. Washing stability and the amount absorption of TiO2NPs were determined by weighing and absorption spectrophotometry procedures, and the stain removal evaluation was conducted to assess the self-cleaning property. Results showed that all of the dicarboxylic acids used in this experiment improved the amount of TiO2NPs absorbed onto cotton samples and their durability to washing. In addition, color variation of samples treated with oxalic acid after 180 min of UV irradiation and drop absorbency time for samples treated with succinic acid were significantly increased by about 126 and 600%, respectively. The best durability was obtained from adipic acid, while a better self-cleaning property was obtained from oxalic acid. © 2014 American Chemical Society.

Zare Y.,Islamic Azad University at Tehran
Composites Part A: Applied Science and Manufacturing | Year: 2016

The dispersion/accumulation of nanoparticles and interphase condition significantly affect the mechanical properties of polymer particulate nanocomposites. In this article, the roles of these parameters on the tensile modulus and strength of polymer nanocomposites are studied by original or developed models and equations. The main focus is performed on the concentration, size and modulus of nanoparticles as well as the thickness, modulus and strength of interphase. The accumulation of nanoparticles and poor interphase weaken the modulus of nanocomposites. Moreover, the strength of nanocomposites intensely depends on the interphase properties. The high concentration of nanoparticles can improve the strength of nanocomposites only when a thick and strong interphase is provided between polymer matrix and nanoparticles. However, big particles due to the accumulation of nanoparticles decrease the strength of nanocomposites at different levels of interphase properties. © 2016 Elsevier Ltd

Hasanabad M.G.,Islamic Azad University at Tehran
AIP Conference Proceedings | Year: 2015

In this paper, BEM was used for free surface modeling in OWC chamber and out of it. Linear kinematic and dynamic boundary conditions were used for free surface out of OWC chamber and nonlinear forms were used for free surface in the chamber. These boundary conditions were discretized by finite differences method. Also, some thermodynamics relations were applied for trapped air behavior modeling in OWC chamber. Wave specifications in Chabahar region were used in modeling because these waves have an acceptable power for electricity generation. The results show a good agreement with results of other researches. © 2015 AIP Publishing LLC.

Ali Faghidian S.,Islamic Azad University at Tehran
Latin American Journal of Solids and Structures | Year: 2015

A modified stress function approach is developed here to reconstruct induced stress, residual stress and eigenstrain fields from limited experimental measurements. The present approach is successfully applied to three experimental measurements set in surface peened plates with shallow shot peening affected zone. The well-rehearsed advantage of the proposed approach is that it not only minimizes the deviation of measurements from its approximations but also will result in an inverse solution satisfying a full range of continuum mechanics requirements. Also, the effect of component thickness as a geometric parameter influencing the residual stress state is comprehensively studied. A key finding of present study is that the plate thickness has no influence on the maximum magnitude of eigenstrain profile and compressive residual stresses within the shot peening affected zone while having a great influence on the magnitude of tensile residual stress and the gradient of linear residual stresses present in deeper regions. © 2015, Brazilian Association of Computational Mechanics. All rights reserved.

Soltanifar M.,Islamic Azad University at Semnan | Hosseinzadeh Lotfi F.,Islamic Azad University at Tehran
Computers and Industrial Engineering | Year: 2011

Making optimal use of available resources has always been of interest to humankind, and different approaches have been used in an attempt to make maximum use of existing resources. Limitations of capital, manpower, energy, etc.; have led managers to seek ways for optimally using such resources. In fact, being informed of the performance of the units under the supervision of a manager is the most important task with regard to making sensible decisions for managing them. Data envelopment analysis (DEA) suggests an appropriate method for evaluating the efficiency of homogeneous units with multiple inputs and multiple outputs. DEA models classify decision making units (DMUs) into efficient and inefficient ones. However, in most cases, managers and researchers are interested in ranking the units and selecting the best DMU. Various scientific models have been proposed by researchers for ranking DMUs. Each of these models has some weakness(es), which makes it difficult to select the appropriate ranking model. This paper presents a method for ranking efficient DMUs by the voting analytic hierarchy process (VAHP). The paper reviews some ranking models in DEA and discusses their strengths and weaknesses. Then, we provide the method for ranking efficient DMUs by VAHP. Finally we give an example to illustrate our approach and then the new method is employed to rank efficient units in a real world problem. © 2010 Published by Elsevier Ltd. All rights reserved.

Jassbi J.,Islamic Azad University at Tehran | Mohamadnejad F.,Islamic Azad University at Tehran | Nasrollahzadeh H.,Imam Sadiq University
Expert Systems with Applications | Year: 2011

The Balanced Scorecard (BSC) is a widely adopted performance management framework first introduced in the early 1990s. More recently, it has been proposed as the basic for a strategic management system. Strategy mapping is the most important task in building a Balanced Scorecard system. Strategy mapping is the process for visually making cause and effect relationships between all possible strategic objectives in an organization. The process for building and constructing a strategy map is a human centric activity which could be considered as the combination and integration of all knowledge and preferences of the managerial boards. From the view point of strategic decision making in an organization, the process for building a strategy map could be viewed in a general body of a unified group decision making context. If we see the strategy map, as a structural modeling framework for making the cause and effect relationships among the strategic objectives, it is possible to deploy Decision Making Trial and Evaluation Laboratory (DEMATEL) as a framework for structural modeling approach subject to the problem. The DEMATEL method gathers collective knowledge to capture the causal relationships between strategic criteria. The model is especially practical and useful for visualizing the structure of complicated causal relationships with matrices or digraphs. Generally speaking, because in building any strategy map, the assigned preferences between the objectives are not crisp necessarily, and experts' domain knowledge could be extracted in a fuzzy environment, then the extended fuzzy DEMATEL is proposed to deal with the ambiguities inherent of such the judgments. © 2010 Elsevier Ltd. All rights reserved.

Bananej M.,Islamic Azad University at Tehran | Karimi-Sori A.,Islamic Azad University at Tehran | Zarrindast M.R.,Tehran University of Medical Sciences | Ahmadi S.,University of Kurdistan
Journal of Psychopharmacology | Year: 2012

Involvement of the dopamine receptors in the basolateral amygdala (BLA) in the effects of histamine on anxiety-like behaviors of the elevated plus maze in male Wistar rats was investigated. The results showed that bilateral intra-BLA injections of histamine (2.5, 5 and 7.5 μg/rat) induced an anxiogenic-like effect, revealed by decreases in percentage of open arm time (%OAT) and open arm entries (%OAE). Intra-BLA administration of dopamine D1 receptor agonist, SKF38393 (0.25 μg/rat), and dopamine D2 receptor agonist, quinpirole (0.03 and 0.05 μg/rat), decreased %OAT but not %OAE. Conversely, intra-BLA administration of dopamine D1 receptor antagonist, SCH23390 (0.5 and 1 μg/rat), and dopamine D2 receptor antagonist, sulpiride (0.3 and 0.5 μg/rat), increased %OAT and %OAE, suggesting an anxiolytic-like effect for both drugs. Interestingly, co-administration of a silent dose of SCH23390 or sulpiride prevented anxiogenic-like effects of SKF38393 and quinpirole, respectively. Conjoint administration of a sub-effective dose of SKF38393 (0.125 μg/rat) or quinpirole (0.01 μg/rat) along with lower doses of histamine (1 and 2.5 μg/rat) induced anxiolytic-like effects. On the other hand, intra-BLA pretreatment with a silent dose of SCH23390 (0.25 μg/rat) or sulpiride (0.1 μg/rat) prevented the anxiogenic-like effect of higher doses of histamine (5 and 7.5 μg/rat). No significant change was observed in total closed arm entries, as an index for motor activity of the animals. It can be concluded that the dopamine D1 and D2 receptors in the BLA may be involved in the anxiogenic-like effects induced by histamine. © The Author(s) 2012.

Ghanbari M.,Islamic Azad University at Tehran | Haeri M.,Sharif University of Technology
Signal Processing | Year: 2010

This paper deals with estimation of fractional order and pole locator in fractional order systems. The estimation is based on Bode diagram of the system that is obtained using input and output measurements. Here the magnitude diagram is approximated with number of straight lines depending on the level of complexity and in consequence a very good estimation of fractional order and acceptable approximations of pole locators are determined. Relying on the proposed method, complexity of fractional order system identification which is mostly due to the estimation of fractional order is substantially resolved. Some example simulation results are provided to explain the work and show its effectiveness. © 2010 Elsevier B.V. All rights reserved.

Saghaei A.,Islamic Azad University at Tehran | Didehkhani H.,Islamic Azad University at Tehran
Expert Systems with Applications | Year: 2011

Six sigma is one of the most popular tools to eliminate waste in organizations, reduce the cost and improve quality. The process of creating and evaluating projects is an initial activity in implementing six sigma. This paper aims at proposing a comprehensive methodology for the evaluation and selection of the six sigma projects. For the evaluation of projects, reviewing the literature and decision team's opinion, we identified three main categories of criteria including business criteria, technological & process criteria and financial criteria which contain eight sub-criteria. For deriving the overall utility of projects, we designed an adaptive neuro fuzzy inference system which is capable to consider interrelations among criteria. Then, applying a fuzzy weighted additive goal programming model, we obtained the optimal portfolio of projects which should be implemented. Finally, we applied the proposed model in a leading company in Iran to illustrate the applicability of the model. © 2010 Elsevier Ltd. All rights reserved.

Damghani K.K.,Islamic Azad University at Tehran | Sadi-Nezhad S.,Islamic Azad University at Tehran | Aryanezhad M.B.,Iran University of Science and Technology
Expert Systems with Applications | Year: 2011

In this paper, we have developed a modular Decision Support System (DSS) in order to select an optimum portfolio of several chances for investments in presence of uncertainty. The investments are considered as the projects so as their initial investment costs, profits, resource requirement, and total available budget are assumed to be uncertain. This uncertainty has been modeled using fuzzy concepts. The proposed DSS has two main modules. The first one is a fuzzy binary programming model which represents the mathematical model of the associated fuzzy capital-budgeting problem. It involves finding optimum combination of investment portfolio considering a multi-objective measurement function and subject to several set of constraints. The results of optimistic and pessimistic analysis of the aforementioned fuzzy binary programming model plus a managerial Confidence Level (CL) value are treated as input of a fuzzy rule based system which is the second module of the proposed DSS. Although some projects are simple to make a decision about at the final step of the first module but the unique output of the second module of the proposed DSS is Risk of Investment (ROI) for all remained project. The logic relations between precedence parts of the rules as well as CL value will work in favor of computational efforts in second module through diminishing some unessential rules. This will help to define a complete set of fuzzy IF-THEN rules more efficiently. The proposed DSS can help the decision makers to select an optimum investment portfolio with minimum risk in a complete ambiguous condition. © 2010 Elsevier Ltd. All rights reserved.

Rahbardehghan S.,Islamic Azad University at Tehran | Pejhan H.,Islamic Azad University at Tehran
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

In this paper, vacuum expectation value (VEV) of the energy-momentum tensor for a conformally coupled scalar field in de Sitter space-time is investigated through the Krein-Gupta-Bleuler construction. This construction has already been successfully applied to the de Sitter minimally coupled massless scalar field and massless spin-2 field to obtain a causal and fully covariant quantum field on de Sitter background. We also consider the effects of boundary conditions. In this respect, Casimir energy-momentum tensor induced by Dirichlet boundary condition on a curved brane is evaluated. © 2015.

Zare Y.,Islamic Azad University at Tehran
Journal of Colloid and Interface Science | Year: 2016

In this work, the strength (σi) and thickness (t) of interphase in polymer nanocomposites reinforced with spherical nanoparticles are modeled by the developed form of Leidner-Woodhams and Pukanszky models for tensile strength. The "σi" and "t" are expressed as functions of "B" parameter in Pukanszky model and the properties of matrix and nanofiller such as the strength of matrix and the nanoparticles radius and volume fraction. Additionally, the effects of the mentioned parameters on "σi" and "t" are discussed.The calculations show that "B" has dissimilar effects on "σi" and "t" levels. A high level of "B" in Pukanszky model suggests a high level of "σi", while a thin interphase is obtained in this condition. Also, the content of nanoparticles plays different roles in the levels of "σi" and "t" based on the extent of interfacial adhesion between polymer and nanoparticles (B value). The influences of "B" on "t" at different nanofiller contents are described by the possibility of nanoparticles aggregation at various values of "B". © 2015.

Zare Y.,Islamic Azad University at Tehran
Journal of Colloid and Interface Science | Year: 2016

In this paper, some models for yield strength of polymer nanocomposites are developed to determine the properties of interphase and agglomerated nanoparticles. In this regard, "Bagg" parameter is defined assuming the agglomerates size (Dagg) and interphase properties. Additionally, the influences of "Bagg" and "Dagg" on the thickness and strength of interphase are evaluated by the developed equations.The agglomeration of nanoparticles causes contradictory effects on interphase properties in samples with different levels of interfacial bonding. Also, "Bagg" more depends to interphase properties compared to "Dagg". It is found that upon increasing in "Bagg" and "Dagg", the strength of interphase improves and reaches the most level at the highest values of "Bagg" and "Dagg". Therefore, controlling the levels of "Bagg" and "Dagg" is crucial to obtain a strong interphase. © 2016.

Pakzad S.,Islamic Azad University at Tehran | Pakzad M.A.,Islamic Azad University at Tehran
WSEAS Transactions on Systems and Control | Year: 2011

many natural systems have intrinsic delays, caused by input, output or state variables. In an openloop system, input delay doesn't affect the stability but if feedback of the state is utilized for controlling the systems, the delay is transferred to closed-loop state and would affect the stability of the system. It is important to evaluate/examine the stability of continuous and discrete delayed-systems. In continuous systems existence of delay increases system dimension to infinity (number of poles is infinite). In discrete systems, number of poles increases but it is finite. Due to the lack of proper and powerful tools in discrete systems, the evaluations of stability in these systems are very important. In this paper, an approach has been proposed based on Lyapunov equation and frequency domain stability analysis for systems which have delay in their states. In this approach, stability conditions have been obtained for discrete systems with delay in a specific interval. All previous works on discrete systems are often for single-delay in state. The purpose of this paper is to extend the existence approaches for systems that have multiple delays in their states. Performance of the proposed method has been studied in several examples.

Husseinzadeh Kashan A.,Islamic Azad University at Tehran
CAD Computer Aided Design | Year: 2011

The league championship algorithm (LCA) is a new algorithm originally proposed for unconstrained optimization which tries to metaphorically model a League championship environment wherein artificial teams play in an artificial league for several weeks (iterations). Given the league schedule, a number of individuals, as sport teams, play in pairs and their game outcome is determined given known the playing strength (fitness value) along with the team formation (solution). Modelling an artificial match analysis, each team devises the required changes in its formation (a new solution) for the next week contest and the championship goes for a number of seasons. In this paper, we adapt LCA for constrained optimization. In particular: (1) a feasibility criterion to bias the search toward feasible regions is included besides the objective value criterion; (2) generation of multiple offspring is allowed to increase the probability of an individual to generate a better solution; (3) a diversity mechanism is adopted, which allows infeasible solutions with a promising objective value precede the feasible solutions. Performance of LCA is compared with comparator algorithms on benchmark problems where the experimental results indicate that LCA is a very competitive algorithm. Performance of LCA is also evaluated on well-studied mechanical design problems and results are compared with the results of 21 constrained optimization algorithms. Computational results signify that with a smaller number of evaluations, LCA ensures finding the true optimum of these problems. These results encourage that further developments and applications of LCA would be worth investigating in the future studies. © 2011 Elsevier Ltd. All rights reserved.

Ali J.S.,Islamic Azad University at Tehran | Maryam M.,Islamic Azad University at Tehran
Human and Ecological Risk Assessment | Year: 2014

A dam's construction always imposes some risks to the environment. In this article, the environmental risks of the Polrood dam, located in a northern province of Iran, during its construction phase, were identified, ranked, and evaluated. The risk factors were initially identified by Delphi questionnaire and then rated using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). Subsequently, the Analytical Hierarchy Process (AHP) was applied to classify the risk factors into four major categories, and Expert Choice software was used to weight them. Based on the obtained results, Physicochemical; Biological; Economic, Social, and Cultural; and Health and Safety risks were rated by the weights of 0.124, 0.080, 0.048, and 0.021, respectively. Among the physicochemical risks, Erosion and Sedimentation weighted 0.061 and 0.047, respectively, were identified as the most serious risks. Among the biological risks, the highest negative impact was assigned to Land Cover with the weight of 0.189. In the third category, the most important risk was Population Displacement, weighted 0.114. Workers' Falls with the weight of 0.109 was also determined as the highest risk in the last category. A comprehensive risk response plan will be required for dealing with the identified risks and their mitigation. © 2014 Copyright Taylor and Francis Group, LLC.

Mazinan A.H.,Islamic Azad University at Tehran
Journal of Central South University | Year: 2015

A novel Lyapunov-based three-axis attitude intelligent control approach via allocation scheme is considered in the proposed research to deal with kinematics and dynamics regarding the unmanned aerial vehicle systems. There is a consensus among experts of this field that the new outcomes in the present complicated systems modeling and control are highly appreciated with respect to state-of-the-art. The control scheme presented here is organized in line with a new integration of the linear-nonlinear control approaches, as long as the angular velocities in the three axes of the system are accurately dealt with in the inner closed loop control. And the corresponding rotation angles are dealt with in the outer closed loop control. It should be noted that the linear control in the present outer loop is first designed through proportional based linear quadratic regulator (PD based LQR) approach under optimum coefficients, while the nonlinear control in the corresponding inner loop is then realized through Lyapunov-based approach in the presence of uncertainties and disturbances. In order to complete the inner closed loop control, there is a pulse-width pulse-frequency (PWPF) modulator to be able to handle on-off thrusters. Furthermore, the number of these on-off thrusters may be increased with respect to the investigated control efforts to provide the overall accurate performance of the system, where the control allocation scheme is realized in the proposed strategy. It may be shown that the dynamics and kinematics of the unmanned aerial vehicle systems have to be investigated through the quaternion matrix and its corresponding vector to avoid presenting singularity of the results. At the end, the investigated outcomes are presented in comparison with a number of potential benchmarks to verify the approach performance. © 2015, Central South University Press and Springer-Verlag Berlin Heidelberg.

Amin G.R.,Islamic Azad University at Tehran | Emrouznejad A.,Aston University
Expert Systems with Applications | Year: 2011

When a query is passed to multiple search engines, each search engine returns a ranked list of documents. Researchers have demonstrated that combining results, in the form of a "metasearch engine", produces a significant improvement in coverage and search effectiveness. This paper proposes a linear programming mathematical model for optimizing the ranked list result of a given group of Web search engines for an issued query. An application with a numerical illustration shows the advantages of the proposed method. © 2011 Elsevier Ltd. All rights reserved.

Norouzi M.,Islamic Azad University at Tehran | Zare Y.,Islamic Azad University at Tehran | Kiany P.,Amirkabir University of Technology
Polymer Reviews | Year: 2015

Along with the rising trend of stringent fire safety regulations, demands for reduction in the fire hazard caused by highly combustible materials such as textiles and polymers have become a matter of significant importance. Therefore, numerous attempts have been made to improve the flame retardation of textiles for a variety of applications. The present paper aims to review the recent developments in the flame retardant nanocomposites of natural and synthetic textile polymers. We survey the application of different nanoparticles or a combination of nanoparticles and conventional flame retardants. Furthermore, a comprehensive discussion on mechanisms and optimized conditions of flame retardation and thermal stability is presented. © 2015 Copyright © Taylor & Francis Group, LLC.

Naseh M.R.,Islamic Azad University at Tehran | Haeri M.,Sharif University of Technology
International Journal of Circuit Theory and Applications | Year: 2011

The control signal magnitude and energy are among the limiting and therefore important factors to be addressed in the practical applications of a synchronization scheme. In this paper, we present an algorithm to find control parameters in an active sliding mode controller in order to reduce the control effort in synchronizing non-identical chaotic systems. We also determine uncertainties bound on the systems dynamics for which the calculated control parameters still guarantee the occurrence of the sliding motion of the error states. The proposed controller was practically applied on an experimental setup, consisting of two chaotic circuits, which resembles Chen and Lu systems behavior. Experimental results confirm our theoretical reasoning as well as the effectiveness of the proposed control design technique. Copyright © 2010 John Wiley & Sons, Ltd.

Nikmaram F.R.,Islamic Azad University at Tehran
Journal of Structural Chemistry | Year: 2016

The radial distribution of hydrogen on C20(cage) and C19Si(cage), and C19B(cage) fullerene structures is investigated at different temperatures (273 K, 293 K, 320 K, and 400 K) for the pressure range between 1 MPa and 30 MPa using the (N,V,T) Monte Carlo simulation. The gravimetric storage capacity and radial distribution function parameters show that, under the identical temperature and pressure conditions, the magnitude of the hydrogen radial distribution on the C19B surface is larger than that on C19Si and C20. The calculated maximum of the gravimetric storage capacity for C19B at 273 K and 30 MPa is 7.6%. © 2016, Pleiades Publishing, Ltd.

Saeb A.,Islamic Azad University at Tehran | Razzazi F.,Islamic Azad University at Tehran
ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings | Year: 2012

In this paper, a new fast compressive sensing (CS) algorithm for phoneme classification is introduced. In this approach, unlike common CS classification approaches that use CS as a classifier, we use CS as an N-best class selector to limit the secondary classifier input into certain classes. In addition, we use a tree search strategy to select most similar training set for the specific test sample. This makes the system adapted to each test utterance and reduces the empirical risk. By this approach, we obtain promising results comparing with other well known classifiers. In addition, the employed CS approach is a fast l 0 norm algorithm which dramatically reduced the computational complexity in the recognition phase. © 2012 IEEE.

Yary T.,Islamic Azad University at Tehran | Aazami S.,Islamic Azad University at Tehran
Biological Trace Element Research | Year: 2012

Depression is an important cause of morbidity, and World Health Organization has predicted that it will be the second leading contributor to the global burden of disease by 2020. Postgraduate students are at high risk for depression caused by the stress of examinations, the academic environment, and relationship problems with peers, lecturers, and family members. Physical inactivity, advancing age, unmarried status, and many other factors contribute to the development of depression in humans. Associations between symptoms of depression and the intake of nutrients such as magnesium have been investigated; however, the relationship between zinc intake and depression has not received as much attention. The purpose of the present study was to examine the relationship between dietary intake of zinc and depression in postgraduate students. This study was conducted on 402 participants with a mean age of 32.54 ± 6.22 years, including 173 (43%) women and 229 (57%) men. In this study, we found an inverse relationship between dietary intake of zinc and depression. The results persisted even after we controlled for several potential confounding variables related to depression symptoms, including age, sex, years of education, smoking status (current and past), and physical activity. The results of this study show that long-term intake of zinc may modulate symptoms of depression. © 2011 Springer Science+Business Media, LLC.

Saadat N.,Islamic Azad University at Tehran | Rahmani A.M.,Islamic Azad University at Tehran
Future Generation Computer Systems | Year: 2012

In recent years, grid technology has had such a fast growth that it has been used in many scientific experiments and research centers. A large number of storage elements and computational resources are combined to generate a grid which gives us shared access to extra computing power. In particular, data grid deals with data intensive applications and provides intensive resources across widely distributed communities. Data replication is an efficient way for distributing replicas among the data grids, making it possible to access similar data in different locations of the data grid. Replication reduces data access time and improves the performance of the system. In this paper, we propose a new dynamic data replication algorithm named PDDRA that optimizes the traditional algorithms. Our proposed algorithm is based on an assumption: members in a VO (Virtual Organization) have similar interests in files. Based on this assumption and also file access history, PDDRA predicts future needs of grid sites and pre-fetches a sequence of files to the requester grid site, so the next time that this site needs a file, it will be locally available. This will considerably reduce access latency, response time and bandwidth consumption. PDDRA consists of three phases: storing file access patterns, requesting a file and performing replication and pre-fetching and replacement. The algorithm was tested using a grid simulator, OptorSim developed by European Data Grid projects. The simulation results show that our proposed algorithm has better performance in comparison with other algorithms in terms of job execution time, effective network usage, total number of replications, hit ratio and percentage of storage filled. © 2011 Elsevier B.V. All rights reserved.

Saeedi P.,Islamic Azad University at Tehran
Bioengineered | Year: 2012

The properties of bacteriorhodopsin (BR) can be manipulated by genetic engineering. Therefore, by the methods of gene engineering, Asp85 was replaced individually by two other amino acids (D85V, D85S). The resulting recombinant proteins were assembled into soybean vesicles retinylated to form functional BR-like nano-particles. Proton translocation was almost completely abrogated by the mutant D85S, while the D85V mutant was partially active in pumping protons. Compared with wild type, maximum absorption of the mutants, D85V and D85S, were 563 and 609 nm, which illustrated 5 nm reductions (blue shift) and 41 nm increases (red shift), respectively. Since proton transport activity and spectroscopic activities of the mutants are different, a wide variety of membrane bioreactors (MBr) have been developed. Modified proteins can be utilized to produce unique photo/Electro-chromic materials and tools.

Khalesi N.,Islamic Azad University at Tehran | Rezaei N.,Islamic Azad University at Tehran | Haghifam M.-R.,Tarbiat Modares University
International Journal of Electrical Power and Energy Systems | Year: 2011

Distribution system companies intend to supply electricity to its customers in an economical and reliable manner whereas customers in most distribution system are outspread and connect to distribution system with different type of equipments. These equipment usually have various types and resistance together, that produce highest loss and lowest reliability for distribution systems and customers that are not appreciated in networks. Distributed generations (DGs) are one of the best reliable solutions for these problems if they are allocated appropriately in the distribution system. This paper presents multi-objective function to determine the optimal locations to place DGs in distribution system to minimize power loss of the system and enhance reliability improvement and voltage profile. Time varying load is applied in this optimization to reach pragmatic results meanwhile all of the study and their requirement are based on cost/benefit forms. Finally to solve this multi-objective problem a novel approach based on dynamic programming is used. The proposed methodology is successfully applied to a study case and simulation results are reported to verify the proposed approach. © 2010 Elsevier Inc. All rights reserved.

Elahi A.S.,Islamic Azad University at Tehran | Ghoranneviss M.,Islamic Azad University at Tehran
Fusion Engineering and Design | Year: 2011

In this contribution we measured the plasma horizontal displacement using the two semi-empirical techniques in the IR-T1 tokamak. First, the plasma horizontal position is calculated from the vertical field coil characteristics. The calculation is made focusing on the vertical field coil current and voltage changes due to the horizontal displacement of plasma column. Also a modified Rogowski and Saddle Sine coil based on the multipole moments method were designed, constructed, and used. The results from these two techniques are compared and discussed. © 2011 Elsevier B.V.

Haghifam M.R.,Tarbiat Modares University | Manbachi M.,Islamic Azad University at Tehran
International Journal of Electrical Power and Energy Systems | Year: 2011

Many subsystems are involved in the reliability modeling of combined heat and power (CHP) systems, but in most studies these subsystems have not been classified and in many cases have been considered separately. Furthermore, calculating the reliability from the generation point to the consumer has not yet been studied. Herein, we classify combined heat and power subsystems and model their reliability, availability and mean-time-to-failure indices based on interactions between subsystems from the generation site to consumer delivery. The proposed CHP reliability and availability model is based on the state space and the continuous Markov method with electricity-generation, fuel-distribution and heat-generation subsystems. The effects of fuel- and water-distribution networks at the CHP site and the hot-water-distribution network on the consumer-utility reliability of CHP systems were fully assessed in an applicable case study. Additionally, we present a sensitivity analysis for island, standby and parallel operational modes of CHP systems. The results from the case study prove that improving the gas-distribution network, the network delivering hot water to the consumers and the water-delivery network to the CHP, in addition to optimizing the failure and repair rates of CHP systems, have considerable effects on the reliability improvement of the complete integrated system and have major roles in technical and economic feasibility studies of CHP systems. © 2010 Elsevier Ltd. All rights reserved.

Sajedi F.,Islamic Azad University at Tehran
Construction and Building Materials | Year: 2012

Although the use of slag has many advantages, the low hydration of slag at early age causes the strength to be low. Hence, its uses are restricted, and should be activated. In this investigation, a mechanical method was used to activate ordinary Portland cement (OPC)-slag mortars (OSM). Fourteen OSMs were made, two of them as control. Three groups of mortars were used. The first group includes both the ground slag and OPC. In the second group ground slag and ungrounded OPC were used, and in the third group ground OPC and ungrounded slag used. For the first group, 7- and 28-day strengths were attained as 65 and 80 MPa, respectively. Finally, the results showed that the optimum strengths attributed to the first group, especially at early ages. All the mix proportions were made for water-binder and sand-binder ratios as 0.33 and 2.25, with 50% level of slag, respectively. © 2011 Elsevier Ltd. All rights reserved.

Soleymani S.,Islamic Azad University at Tehran
International Journal of Electrical Power and Energy Systems | Year: 2011

This paper proposes a new method that uses the combination of particle swarm optimization (PSO) and simulated annealing (SA) to predict the bidding strategy of Generating Companies (Gencos) in an electricity market where they have incomplete information about their opponents and market mechanism of payment is pay as bid. In the proposed methodology, Gencos prepare their strategic bids according to Supply Function Equilibrium (SFE) model and they change their bidding strategies until Nash equilibrium points are obtained. Nash equilibrium points constitute a central solution concept in game theory and they are computed with solving a global optimization problem. In this paper a new computational intelligence technique is introduced that can be used to solve the Nash optimization problem. This new procedure, is based on the PSO algorithm, which uses SA method to avoid becoming trapped in local minima or maxima and improve the velocity's function of particles. The performance of this procedure is compared with results of other computational intelligence techniques such as PSO, Genetic Algorithm (GA), and a mathematical method (GAMS/DICOPT). The IEEE 39-bus test system is employed to illustrate and verify the results of the proposed method. © 2011 Elsevier Ltd. All rights reserved.

Bavafa M.,Islamic Azad University at Tehran
Proceedings - 2011 International Conference on Energy, Automation and Signal, ICEAS - 2011 | Year: 2011

Smart grid is a relatively new term that refers to the application of information technology to power systems. Due to the complexity of such systems, the possibilities have yet to be clearly defined. Smart Grid will be a new way to the development of the power network. In the development of Smart Grid, how to integrate the Renewable Energy and the Distributed Generation (DG) safely and reliably is a problem urgent to be solved. Siting and sizing of DG planning in Smart Grid construction are researched in this paper. A multi-objective optimal model is established and normalized in the DG number, location and individual capacity of uncertainty. The improved Evolutionary programming is used to solve this optimization problem. Finally, the validity of the method proposed in the paper is proved by an example. © 2011 IEEE.

Shirzad T.,Islamic Azad University at Tehran | Shomali Z.H.,University of Tehran | Shomali Z.H.,Uppsala University
Geophysical Journal International | Year: 2013

In this study, we present an application of the ambient noise tomography (ANT) to study the near-surface geological structures of the metropolitan Tehran/Iran region. Short-period fundamental mode Rayleigh wave Green's functions were estimated using cross-correlations of the vertical component of the ambient noise from 2009 October to 2011 May using a variety of seismic sensors, for example, accelerometers and seismometers, deployed in the Tehran area. Standard common lowfrequency processing procedures were applied to the cross-correlations, and shorter time-windows comprising 10-min segments were used in the processing step to enhance the time resolution of the signal in the frequency range of interest (1-10 s). Stacking was also conducted using the rms of the estimated empirical Green's functions. Our results demonstrate that ambient seismic noise tomography is a viable technique at periods of 1-10 s in length, even when different sensor types are present. Analysis of the empirical Green's functions indicates that the dominant sources of ambient seismic noise originated from the same origin, and no significant seasonal or spatial variations in the ambient noise sources were observed. Multiple-filter analysis was used to extract the group velocities from the estimated empirical Green's functions,whichwere then inverted to image the spatially varying dispersion at periods of lengths between 1 and 7 s using tomographic inversion of the traveltimes estimated for each frequency. The resulting group velocity maps show high correlations with known geological and tectonic features of the study region. In general, most of the Tehran basin, with certain exceptions, could be clearly resolved with low group velocities, whereas the mountain ranges were found to be correlated with high group velocities. In the Tehran basin, for 2 and 3 s periods, the low-velocity zone deepens towards the south-southwest, which reflects thicker sediments in the southern part of the basin than in the north. This feature has also been observed in other geological studies. The Vs models also show that bedrock depth varies between 400 and 1400m from north to south within the Tehran basin. At longer periods main faults are associated with abrupt transitions between regions of high- to low-velocity anomalies. In general, our results indicate that ANT can be a flexible and effective approach for studying near-surface heterogeneity using short-period surface wave data. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.

Mosleh M.,Islamic Azad University at Tehran
Journal of Materials Science: Materials in Electronics | Year: 2016

This work has provided a general, simple, and effective method to control the composition and morphology of CoTiO3 nanoparticles, which revealed potential new insight into inorganic synthesis methodology. CoTiO3 nanoparticles were synthesized via a novel route based on the reaction between cobalt salt and tetra-n-butyl titanate (TNBT) in ethanol. Results of this investigation demonstrate that CoTiO3 with very uniform sphere-like shape, small grain size and pure rhombohedral phase could be synthesized by different capping agents such as asparagine, alanine, and leucine. XRD, SEM, EDS, and UV–vis spectroscopy were employed to characterize structural, morphological, and optical properties of CoTiO3 nanoparticles. According to the vibrating sample magnetometer (VSM) result, CoTiO3 nanoparticles indicated a paramagnetic behavior at room temperature. Furthermore, the photocatalytic properties of as synthesized CoTiO3 were evaluated by degradation of methyl orange (MO) as water contaminant. © 2016 Springer Science+Business Media New York

Vosoughifar M.,Islamic Azad University at Tehran
Journal of Materials Science: Materials in Electronics | Year: 2016

In the current study, an attempt is made to synthesize europium vanadate (EuVO4) nanoparticles via a simple method with the aid of europium nitrate hexahydrate and ammonium metavanadate. Capping agents are frequently used in colloidal synthesis to inhibit nanoparticle overgrowth and aggregation as well as to control the structural characteristics of the resulted nanoparticles in a precise manner. Sulfanilic acid, cinnamic acid, and salicylic acid were applied as capping agents. XRD, SEM, EDS, and UV–vis spectroscopy were employed to characterize structural, morphological, and optical properties of EuVO4 nanoparticles. According to the vibrating sample magnetometer result, EuVO4 nanoparticles indicated a paramagnetic behavior at room temperature. Furthermore, the photocatalytic properties of as synthesized EuVO4 were evaluated by degradation of methyl orange as water contaminant. © 2016 Springer Science+Business Media New York

Vosoughifar M.,Islamic Azad University at Tehran
Journal of Materials Science: Materials in Electronics | Year: 2016

Manganese tungstate (MnWO4) nanoparticles, has been successfully prepared via a novel method. In this method, manganese salt and Na2WO4·2H2O were applied as starting reagents to fabricate MnWO4 nanoparticles. The effect of different amino acids like valine, glycine and asparagine on the morphology and particle size of the products has been investigated. The as-synthesized nanostructures were characterized by X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy (UV–Vis), and energy dispersive X-ray microanalysis. According to the vibrating sample magnetometer, MnWO4 nanoparticles indicated a paramagnetic behavior at room temperature. To evaluate the catalytic properties of nanocrystalline manganese tungstate, the photocatalytic degradations of methyl orange under ultraviolet light irradiation were carried out. © 2016 Springer Science+Business Media New York

Monajjemi M.,Islamic Azad University at Tehran | Wayne Jr. R.,University of Texas at Austin | Boggs J.E.,University of Texas at Austin
Chemical Physics | Year: 2014

In this work, we have applied a statistical method by computing statistical nucleus-independent chemical shifts (SNICS) in point of probes motions within a spatial shielding and de-shielding spaces around the OH groups of some amino acids. NMR contour maps as a new parameter have been created for amino-acyl-tRNA conjugation, by using a computational method to identify this model theoretically, it is critical to understand the reasons for tRNA-amino acid conjugation. DFT, NMR, 3D Gaussian distribution and Monte Carlo methods have been applied for Methionine, Serine, Histidine, Glycine and Glutamine to investigate the structural stability in the active parts of the amino acid-tRNA linkage by chemical shielding effects. In this work we have exhibited the dielectric effect in an incorrect tRNA-amino acid conjugation. © 2014 Elsevier B.V. All rights reserved.

Jalal M.,Islamic Azad University at Tehran | Ramezanianpour A.A.,Amirkabir University of Technology
Composites Part B: Engineering | Year: 2012

Enhancement of strength and ductility is the main reason for the extensive use of fiber reinforced polymer (FRP) jackets to provide external confinement to reinforced concrete columns especially in seismic areas. Therefore, numerous researches have been carried out in order to provide a better description of the behavior of FRP-confined concrete for practical design purposes. This study presents a new approach to obtain strength enhancement of concrete cylinders confined with carbon fiber reinforced polymer (CFRP) composites by applying artificial neural networks (ANNs). The proposed ANN model is based on experimental results collected from literature. It represents the ultimate strength of concrete cylinders after CFRP confinement which is also given in explicit form in terms of geometrical and mechanical parameters. The accuracy of the proposed ANN model is quite satisfactory as compared to experimental results. Moreover the results of proposed ANN model are compared with five important theoretical models proposed by researchers so far and considered to be in good agreement. © 2011 Elsevier Ltd. All rights reserved.

Mosleh M.,Islamic Azad University at Tehran
Journal of Materials Science: Materials in Electronics | Year: 2016

This paper describes the synthesis of terbium vanadate (TbVO4) with different morphologies prepared through a new approach by using terbium nitrate hexahydrate, ammonium metavanadate and different capping agents. This study aimed to investigate the effects of different capping agents such as histidine, asparagine, and cysteine on the morphology, particle size, and crystal structure of final products. According to the vibrating sample magnetometer, TbVO4 nanoparticles indicated a paramagnetic behavior at room temperature. To evaluate the catalytic properties of nanocrystalline TbVO4, the photocatalytic degradations of methyl orange under ultraviolet light irradiation were carried out. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray microanalysis and ultraviolet–visible spectroscopy were employed to characterize structural, morphological, and optical properties of TbVO4 nanoparticles. © 2016 Springer Science+Business Media New York

Golestani B.,Islamic Azad University at Tehran | Moghadas Nejad F.,Amirkabir University of Technology | Sadeghpour Galooyak S.,Islamic Azad University at Tehran
Construction and Building Materials | Year: 2012

Polymeric nanocomposites have been widely acknowledged recently. In this study, the effects of nanoclay on two grades of styrene-butadiene-styrene (SBS) modified asphalts, linear and branch, have been investigated. The physical, mechanical and rheological properties of original binder, polymer modified asphalts and nanocomposite modified asphalts have been studied and compared. The results have shown that nanoclay can improve the physical properties, rheological behaviors and the storage stability of the polymeric asphalts. Linear SBS-nanocomposite modified asphalt may form an exfoliated structure, whereas the Branch SBS-nanocomposite modified asphalt may form an intercalated structure, based on the X-ray diffraction (XRD) results. © 2012 Elsevier Ltd. All rights reserved.

Ghafouri R.,Islamic Azad University at Tehran
Materials Chemistry and Physics | Year: 2016

We have applied density functional calculations to investigate Stone Wales (SW) and carbon ad-dimer (CD) defect formation in triangular graphene quantum dots (GQDs). According to our results, defect formation energies depend on the positions of SW defects, such that the rotation of the CC bond located near the vertex of triangular GQD is easier than the rotation of other CC bonds. Therefore, the multiply defective GQDs with isolated SW defect sites are the most favorable while the formation of pentalene like structures in the connected SW defect sites costs larger formation energies. Introducing of carbon dimer defects on a triangular GQD induces a curvature at the defective sites, which leads to a more complex defect configuration with cone-like structure in the CD defective GQD with three defective sites. Then, formation energies for CD defective GQDs are higher than those for SW defective ones. The electrophilicity values calculated for SW and CD defective GQDs are greater than those for pristine GQDs. Moreover, perturbation of strong sp2 bonding network of graphitic carbons on the GQD, leading to the formation of more localized CC bonds, results in further electron deficiency of multiply SW and CD defective GQDs with increasing of electrophilicity values. © 2016 Elsevier B.V.

Mazinan A.H.,Islamic Azad University at Tehran
Human-centric Computing and Information Sciences | Year: 2015

A high-precision full quaternion based finite-time three-axis cascade attitude control strategy is considered in the present research with respect to state-of-the-art to deal with a class of overactuated space systems. The main idea behind the subject is to design a new quaternion based proportional derivative approach, which is realized along with the linear quadratic regulator method. In a word, the control technique proposed here is organized based upon an inner closed loop control to handle the angular rates in the three axes and the corresponding outer closed loop to handle the rotational angles in the same three axes, as well. It aims us to cope with the present complex and complicated systems, in the productive and constructive manner, in a number of programmed space missions such as orbital, communicational, thermal and so on maneuvers. It can be shown that the proposed cascade control strategy is organized in association with a set of pulse-width pulse-frequency modulators to drive a number of on–off reaction thrusters. It should be noted that these ones could significantly be increased w. r. t. the investigated control efforts, in order to provide overall accurate performance of the present space systems. There is currently a control allocation realization to complete the process of the approach presentation and organization. At last, the investigated results are presented in comparison with some potential benchmarks to guarantee and verify the approach performance. © 2015, Mazinan.

Khodaii A.,Amirkabir University of Technology | Kazemi Tehrani H.,Islamic Azad University at Tehran | Haghshenas H.F.,Amirkabir University of Technology
Construction and Building Materials | Year: 2012

Beneficial effects of using hydrated lime to reduce moisture susceptibility of Hot Mix Asphalts are well recognized and widely used in industry. In present study, the effect of varying percentages of hydrated lime (from 0% to 2%) on the moisture susceptibility of warm mix asphalt was evaluated. Based on the obtained results it was shown that increasing hydrated lime content reduces the moisture susceptibility of dense graded warm mix asphalt. However, 80% of tensile strength ratio was reached without utilization of hydrated lime in some prepared samples with gap grading, using polymer modified bitumen. © 2012 Elsevier Ltd. All rights reserved.

Khodaii A.,Amirkabir University of Technology | Haghshenas H.F.,Amirkabir University of Technology | Kazemi Tehrani H.,Islamic Azad University at Tehran
Construction and Building Materials | Year: 2012

Response surface methodology was employed to evaluate the effect of lime content and grading on the dry and saturated indirect tensile strength as well as Tensile Strength Ratio of hot mix asphalt. The statistical significance of linear, quadratic and interactive terms of these factors were examined and second order polynomial models were successfully fitted to the experiment data. It was shown that maximum Tensile Strength Ratio was achieved at 1% lime content and with grading containing most coarse aggregate. It was further concluded that decreasing the aggregate size and increase in mastic asphalt would increase the stripping potential of hot mixes asphalt. © 2012 Elsevier Ltd. All rights reserved.

Hasheminejad S.M.,Iran University of Science and Technology | Gheshlaghi B.,Islamic Azad University at Tehran
Composite Structures | Year: 2012

A three-dimensional semi-analytic analysis based on the linear elasticity theory is offered to study the transient vibration characteristics of an arbitrarily thick, simply supported, functionally graded (FGM) rectangular plate, resting on a linear Winkler-Pasternak viscoelastic foundation, and subjected to general distributed driving forces of arbitrary temporal and spatial variations. The problem solution is obtained by adopting a laminate model in conjunction with the powerful state space solution technique involving a global transfer matrix and Durbin's numerical Laplace inversion algorithm. Numerical calculations are carried out for the transient displacement and stress responses of aluminum-zirconia FGM square plates of selected thickness parameters and compositional gradients, resting on " soft" or " stiff" elastic foundations, under the action of moving transverse forces as well as uniformly distributed blast loads. Also, the response curves for the FGM plates are compared with those of equivalent bilaminate plates containing comparable total volume fractions of constituent materials. It is observed that the material gradient variation is substantially more influential on the dynamic stress concentrations induced across the plate thickness than on the displacement response of the inhomogeneous plates. In particular, the displacement response of the equivalent bilaminate plates can provide an accurate estimate for prediction of the dynamic response of the corresponding FGM plates, especially for thick plates resting on a stiff foundation. Limiting cases are considered and good agreements with the data available in the literature as well as with the computations made by using a commercial finite element package are obtained. © 2012 Elsevier Ltd.

In this paper, "a" interfacial parameter in Nicolais-Narkis model is expressed by thickness "ri" and strength "σi" of interphase between polymer and nanoparticles as well as material properties. "a" parameter is connected to "B1" interfacial parameter in modified Pukanszky model and the effects of "ri" and "σi" on "a" are explained.The negligible difference between "a" values calculated by fitting the experimental results to Nicolais-Narkis model and also, by "B1" results confirms the accurateness of the suggested relation between "a" and "B1" parameters. Additionally, an inverse relation is found between "a" and "B1" parameters for nanocomposites containing spherical nanoparticles. The results demonstrate that the slight levels of "ri" and "σi" data give a large value of "a" which indicates the poor interfacial adhesion. © 2016 Elsevier Inc.

Mazinan A.H.,Islamic Azad University at Tehran
Computers and Electrical Engineering | Year: 2014

State-of-the-art in real-time simultaneous objects tracking through automated probabilistic estimation framework has been considered. The approach proposed here is dealt with in association with a novel self-correcting particle filter to track a number of moving objects. This idea is applicable to track most of simultaneous non-rigid objects, since 3D image is analyzed. Due to the fact that the captured frames are taken into account as two dimensional data matrices, some appropriate extracted features of the processed frames could be utilized to make the third dimension. The whole of suitable features of moving objects, which cannot directly be applied to the process of posterior probability calculation, need to be fed to a neural network for the purpose of making the third dimension. Subsequently, the probabilistic estimation of the present self-correcting particle filter in each frame is corrected through the neural network results to estimate each identified object, appropriately, in its current frame. The effectiveness of the proposed approach performance is guaranteed, once the results of three known particle filter-based procedures are taken into real consideration as benchmark approaches. Experimental results demonstrate that the proposed approach outperforms the traditional tracking systems for various challenging scenarios. It is shown that the accuracy of the proposed approach is improved, while its tracking error is correspondingly decreased. © 2014 Elsevier Ltd. All rights reserved.

Sakha M.,Islamic Azad University at Tehran
Comparative Clinical Pathology | Year: 2016

This study was performed to evaluate the effect of induction of clinical ketosis or pregnancy toxemia (PT) and subsequent effects on serum biochemical factors. Seven native pregnant ewes aged 3–4 years, 45–50 kg weight with BCS of 3.5–4 on a 0–5 scale were selected. The pregnancy of ewes was confirmed by ultrasound examination. Blood samples were harvested from the jugular vein before and after the induction of PT by food deprivation. Serum β-hydroxybutyrate (BHBA), Nonesterified fatty acids (NEFA), BUN, glucose, calcium, total protein, and cortisol concentrations were measured. Serum BHBA, NEFA, BUN, and cortisol concentrations after induction of PT were significantly higher (P < 0.01), and calcium showed significantly lower concentrations (P < 0.01) but glucose and total protein measures did not show significant changes (P > 0.01). © 2016, Springer-Verlag London.

Dehghan A.A.,University of Yazd | Dehghani A.R.,Islamic Azad University at Tehran
International Journal of Thermal Sciences | Year: 2011

Thermal performance of a traditional, underground cold-water reservoir (cistern) is investigated both experimentally and analytically. An innovative analytical solution technique for determination of the temperature distribution in the reservoirs is developed by employing a linearized boundary condition at the water surface. The theoretical predictions are then compared with the extensive experimental measurements obtained in a traditional underground cold-water reservoir located in the city of Yazd in central region of Iran. Good agreement between the analytical and the experimental results demonstrates the validity of the proposed analytical solution method. Both the experimental data and analytical results show that a stable thermal stratification develops within the water reservoir and is preserved throughout the entire course of water withdrawal cycle. Both results demonstrate that while the outside ambient temperature reaches 42 °C during the summer time, cool drinking water with the temperature ranging from 12 to 13 °C is readily available from the water withdrawal tap of the reservoir. Parametric studies show that decreasing induced wind velocity over the water surface or increasing the ambient temperature leads to an increase in the top water layer temperature, while the bottom water layers are not significantly affected. This finding is important as it confirms that the traditional cold storage reservoirs are capable of protecting the bottom cold-water layers from harsh outdoor environment. Further, it is observed that for these water reservoirs and for selected storage aspect ratios beyond one, bottom layers temperatures are not influenced by the variation of the reservoir aspect ratio. Utilizing the experimental results, an energy and exergy analysis shows that around 80% of the cooling capacity stored in the winter can be retrieved during the summer time at a desired temperature. Comparing the exergy content of the stratified reservoir with that of the fully mixed tank shows that the formation of stable thermal stratification is responsible for preserving the quality of the extracted cold energy. © 2011 Elsevier Masson SAS. All rights reserved.

Nasiri S.H.,Islamic Azad University at Tehran | Moravvej-Farshi M.K.,Tarbiat Modares University | Faez R.,Sharif University of Technology
IEEE Electron Device Letters | Year: 2010

We present a Nyquist stability criterion based on transmission line modeling for graphene nanoribbon (GNR) interconnects. This is the first instance that such an analysis has been presented for GNR, so far. In this analysis, the dependence of the degree of relative stability for multilayer GNR (MLGNR) interconnects on the geometry of each ribbon has been acquired. It is shown that, increasing the length and width, MLGNR interconnects become more stable. © 2006 IEEE.

Faghidian S.A.,Islamic Azad University at Tehran
Journal of Strain Analysis for Engineering Design | Year: 2015

A modified stress function approach is developed for reconstruction of residual stress and eigenstrain fields from limited experimental measurements. The modified approach is successfully applied to three experimental case studies where residual stresses are introduced by surface peening. The smooth reconstructed residual fields not only minimize the deviation of measurements from its approximation but also satisfy all continuum mechanics requirements. Furthermore, a comprehensive discussion is performed on regularity of the solution in Tikhonov scheme and the regularization parameter is then determined utilizing Morozov discrepancy principle. Newton iterative method is also shown to have an excellent fast convergence to the regularization parameter while effectively reduces the computational cost. © IMechE 2014.

Ashori A.,Iranian Research Organization for Science and Technology | Ornelas M.,University of Madeira | Sheshmani S.,Islamic Azad University at Tehran | Cordeiro N.,University of Madeira
Carbohydrate Polymers | Year: 2012

Agro-residues fibers are inexpensive environmentally friendly alternatives to synthetic fibers in fiber-reinforced polymer composites. The natural fiber properties and bondability with adhesive can be modified by subjecting the fibers to a pre-treatment procedure. The knowledge of the modified fibers surface properties is essential to explain and predict their applications. The present study is focused on the effect of alkaline treatment on the surface characteristics of stalk fibers from rapeseed, tobacco, cotton, lemon balm and kiwi. The chemical composition of fibers and Fourier transform infrared spectroscopy show components extraction and the X-ray diffraction show improvement in the crystallinity index of the treated fibers. But only the IGC analysis allows us to know in detail the alterations on the fiber surface and the effect on the adhesion of the fibers. IGC shows that alkaline treatment produces changes in the nature and number of the active sites, responsible for the physico-chemical activity of the surface of the fibers. The fiber hydrophobicity was improved by the increase of more energetic and active sites in the surface. Also, the creation of new basic active sites and removal of acidic active sites from the fiber surface due to alkaline treatment has been clearly shown. © 2012 Elsevier Ltd. All rights reserved.

Montazer M.,Amirkabir University of Technology | Alimohammadi F.,Islamic Azad University at Tehran | Shamei A.,Islamic Azad University at Tehran | Rahimi M.K.,Islamic Azad University at Tehran
Carbohydrate Polymers | Year: 2012

This study introduces a new green method synthesis of silver nanoparticles on the cotton fabric surface through using Tollens' reagent. In this approach, silver nitrate (AgNO3) was transformed to Ag2O followed by an aqueous solution with ammonia; subsequently, silver nanoparticles were synthesized on the cotton fabric directly. The main objective of this research was to successfully employ the reducing and stabilizing features of cellulose to synthesize nano silver. Accordingly, the antibacterial efficiency was evaluated against two common pathogenic bacteria: S. aureus and E. coli. Additionally, the color variation on the cotton fabric and durability of the antibacterial properties on the fabric were assessed and reported. The Raman spectra, CHN elemental analysis, SEM images, XRD patterns, and EDS spectrum were employed to characterize the treated cotton fabrics. The treated fabrics demonstrated an excellent antibacterial activity against the mentioned bacteria. A slight decrease in the antibacterial feature of the cotton fabrics was observed after successive washings. However, an efficient antibacterial activity remained on the fabrics. © 2011 Elsevier Ltd. All rights reserved.

Moghaddasi R.,Islamic Azad University at Tehran | Pour A.A.,Islamic Azad University at Tehran
Energy Reports | Year: 2016

In this study we investigated the relation between energy consumption and growth of total factor productivity (TFP) of agriculture in Iran from 1974 to 2012 using Solow residual method. The results from estimated aggregate Cobb–Douglas production function showed that one percent change in the value of labor, capital and energy will lead to 4.07, 0.09 and 0.49 percent change in agriculture value added, respectively. Also in a long term, based on the Johansen cointegration test, there is a negative relation between TFP growth and energy consumption in Iranian agriculture which might be due to cheap and inefficient energy use in this sector. Gradual liberalization of energy price and use of so called green box support policies is recommended. © 2016 The Author(s)

Yousefi R.,Islamic Azad University at Tehran | Saghafi K.,Shahed University | Moravvej-Farshi M.K.,Tarbiat Modares University
IEEE Transactions on Electron Devices | Year: 2010

In this paper, we investigate the transport properties of carbon nanotube field-effect transistors (CNTFETs), with a nonequilibrium Green's function (NEGF) method. Tunneling leakage currents with respect to gate voltages are known effects for MOSFET-like CNTFETs (MOSCNTs). To minimize this phenomenon, we have proposed a structure with a simple modification of the MOSCNT by using lightly doped regions between the intrinsic channel and the highly doped source and drain regions, which we call the lightly doped drain and source CNTFET (LDDS-CNTFET). Simulations have shown that LDDS-CNTFET characteristics are related to the lightly doped region concentration. In comparison with an MOSCNT and a linearly doped CNTFET (LD-CNTFET), an LDDS-CNTFET with appropriately doped lightly doped drain and source regions has demonstrated a larger on current (Ion), a larger on off ratio (Ion/Ioff), a superior ambipolar characteristic, a shorter delay time, and also a smaller powerdelay product. Furthermore, our results show that the channel length for an LDDS-CNTFET is shorter than that for an LD-CNTFET having the same off-state characteristics. Finally, the effect of the unavoidable Schottky barriers at the interface of the heavily doped source/drain regions and their metal electrodes has been taken into account. Simulations have demonstrated that these Schottky barriers have almost the same deteriorating effects on the characteristics for both LD-CNTFETs and LDDS-CNTFETs. Hence, all discussions regarding the superiority of the proposed structure are also valid in presence of the Schottky barriers. © 2010 IEEE.

Fard M.J.S.,Islamic Azad University at Tehran | Morsali A.,Tarbiat Modares University
Journal of Inorganic and Organometallic Polymers and Materials | Year: 2010

Nano-structure of a new 1D double-chain Pb(II) coordination polymer, [Pb(μ-HPDC)(μ-Br)(H 2O)] n (1), {H 2PDC = 2,3-pyrazinedicarboxylic acid} was synthesized by a sonochemical method. The new nano-structure was characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. The structure of compound 1 was determined by single crystal X-ray diffraction and consists of 1D double-chain polymeric units. The coordination number in compound 1 is six and each lead atom is coordinated by two oxygen atoms of HPDC -, two nitrogen atoms of HPDC - ligands, one bromide atom and one oxygen of H 2O molecule. The thermal stability of compound 1 was studied by thermal gravimetric and differential thermal analyses. Calcination of the nano-belts of compound 1 at 500 °C under air atmospheres yielded nano-sized particles of PbBr(OH) that characterized by scanning electron microscopy and X-ray powder diffraction. © 2010 Springer Science+Business Media, LLC.

Amoli P.V.,Islamic Azad University at Tehran
International Journal of Electrical and Computer Engineering | Year: 2016

Nowadays, Underwater Sensor Networks (UWSN), in which data is collected through underwater sensors, have drawn lots of concern. Generally, wireless sensor network (WSNs) have important applications such as remote environmental monitoring and target tracking. This possibility is enabled by the available smaller and cheaper sensors. These sensors are equipped with wireless interfaces which they form a network. However, there are various problems specified to underwater environments, including the communication medium. Designs of these types of networks significantly depend on their application, and factors such as environment, design objectives of the application, cost, hardware and system constraints. The goal of this work is to review the literature on various aspects of UWSNs, and present an overview of several new applications and their challenges. Publications are reviewed to show the statistics of published works in several aspects of the topic based upon the year of publication. This survey gives the readers a view on the place of underwater sensor networks on researches and industries. The readers can track what have been highly interests in recent years and what are yet on challenges. Copyright © 2016 Institute of Advanced Engineering and Science. All rights reserved.

Ghiasi R.,Islamic Azad University at Tehran
Russian Journal of Coordination Chemistry/Koordinatsionnaya Khimiya | Year: 2011

The electronic structures and properties of the platinabenzene and mono- and difluorinated platinabenzenes isomers have been investigated using hybrid density functional B3LYP theory. Basic measures of aromatic character were derived from structure, molecular orbital, and nuclear independent chemical shift (NICS). An energetic criterion suggests that ortho isomer of monofluorinated and F15 isomer of difluorinated platinabenzenes enjoy conspicuous stabilization. The polarizability and molecular orbital analysis are compatible with this result. NICS values calculated at several points above the ring center fail to give the result consistent with that based on relative energy, polarizability, and molecular orbital analysis. The atoms in molecules analysis indicates a correlation between NICS (1.0) and the electron density of the ring critical point (ρrcp) in monofluorinated platinabenzenes. There is a similar correlation in difluorinated platinabenzenes (except for F12 and F24 isomers) between NICS (0.5) and ρrcp. © 2011 Pleiades Publishing, Ltd.

Mohammadi S.,Islamic Azad University at Tehran | Mohammadi A.,Islamic Azad University at Gachsaran
International Journal of Electrical Power and Energy Systems | Year: 2014

Energy storage systems (ESS) are designed to accumulate energy when production exceeds demand and to make it available at the user's request. They can help match energy supply and demand, exploit the variable production of renewable energy sources (e.g. solar and wind), increase the overall efficiency of the energy system and reduce CO2 emissions. This paper presents a unit commitment formulation for micro-grid that includes a significant number of grid parallel PEM-Fuel Cell Power Plants (PEM-FCPPs) with ramping rate and minimum up and down time constraints. The aim of this problem is to determine the optimum size of energy storage devices like hydrogen, thermal energy and battery energy storages in order to schedule the committed units' output power while satisfying practical constraints and electrical/thermal load demand over one day with 15 min time step. In order to best use of multiple PEM-FCPPs, hydrogen storage management is carried out. Also, since the electrical and heat load demand are not synchronized, it could be useful to store the extra heat of PEM-FCPPs in the peak electrical load in order to satisfy delayed heat demands. Due to uncertainty nature of electrical/thermal load, photovoltaic and wind turbine output power and market price, a two-stage scenario-based stochastic programming model, where the first stage prescribes the here-and-now variables and the second stage determines the optima value of wait-and-see variables under cost minimization. Quantitative results show the usefulness and viability of the suggested approach. © 2014 Elsevier Ltd. All rights reserved.

Mousavi S.M.,Islamic Azad University at Tehran | Mostafavi E.S.,Isfahan University of Technology | Hosseinpour F.,Islamic Azad University at Central Tehran
Computers and Industrial Engineering | Year: 2014

This study proposes a new gene expression programming (GEP) approach for the prediction of electricity demand. The annual population, gross domestic product, stock index, and total revenue from exporting industrial products were used to predict the electricity demand of the same year in Thailand. Several statistical criteria were used to verify the validity of the model. Further, the contributions of the influencing variables to the prediction of the electricity demand were analyzed. Correlation coefficient, root mean squared error and mean absolute percent error were used to evaluate the performance of the model. In addition to its high accuracy, the derived model outperforms regression and other soft computing-based models. © 2014 Elsevier B.V. All rights reserved.

Jahanshahi M.,Islamic Azad University at Tehran | Bistouni F.,Islamic Azad University at Qazvin
Computers and Electrical Engineering | Year: 2014

Because of their cost-effectiveness, multistage interconnection networks are widely used in parallel multiprocessor systems to make a connection among the processors and memory modules. One of the most important requirements for these communication systems is reliability. Adding a number of stages to these networks is one of the main approaches to promote this issue. Despite its modest cost and ease of implementation, this approach improves the reliability only to a small extent, which is not desirable, especially for large-scale systems. In this paper, we propose a new approach to improve reliability of the networks, called reducing nodes. Extensive reliability analyses from two major perspectives, terminal and broadcast, demonstrate that this idea can achieve a tremendous advantage over the aforementioned approach. © 2014 Elsevier Ltd. All rights reserved.

Pakzad M.A.,Islamic Azad University at Tehran | Nekoui M.A.,K. N. Toosi University of Technology
International Journal of Control, Automation and Systems | Year: 2014

In this paper, a novel method is presented to study the stability map of linear fractional order systems with multiple delays against uncertainties in delays. It is evident from the literature that the stability question of this class of dynamics has not been resolved yet. The backbone of the new methodology is inspired by an advanced clustering with frequency sweeping technique which enables the exhaustive determination of stability switching curves in the space of the delays. The proposed method detects all the stability regions exactly, in the parametric space of the time delays. An illustrative example is presented to confirm the proposed method results. © 2014 Institute of Control, Robotics and Systems and The Korean Institute of Electrical Engineers and Springer-Verlag Berlin Heidelberg.

Shahriari S.,University of Aveiro | Shahriari S.,Islamic Azad University at Tehran | Neves C.M.S.S.,University of Aveiro | Freire M.G.,University of Aveiro | Coutinho J.A.P.,University of Aveiro
Journal of Physical Chemistry B | Year: 2012

Among the numerous and interesting features of ionic liquids is their ability to form aqueous biphasic systems (ABSs) when combined with inorganic or organic salts in aqueous media. In this work, a wide range of salts was studied, aiming at gathering a detailed picture on the molecular mechanisms that govern the ability of the salt ions to induce the formation of ionic-liquid-based ABSs. For that purpose, 1-butyl-3-methylimidazolium trifluoromethanesulfonate was chosen due to its facility to undergo liquid-liquid demixing in aqueous media containing conventional salts. The corresponding ternary phase diagrams, tie-lines, and tie-line lengths were determined at 298 K and atmospheric pressure. With the large body of data measured in this work, it was possible to establish a scale on the salt cation and anion abilities to induce the formation of ionic-liquid-based ABSs, which follows the Hofmeister series, and to show that the molar entropy of hydration of the salt ions is the driving force for aqueous two-phase system formation. © 2012 American Chemical Society.

Amini K.,Islamic Azad University at Tehran | Nategh S.,Islamic Azad University at Tehran | Shafyei A.,Isfahan University of Technology
Materials and Design | Year: 2010

This experimental study investigated the effect of cryogenic treatments on the wear behavior of 80CrMo12 5 tool steel. For this purpose, two different cryogenic temperatures were used: -80 °C as the shallow cryogenic temperature and -196 °C as the deep cryogenic temperature. The results showed that the cryogenic treatments decrease retained austenite, which is more effective in the case of the deep cryogenic treatment (DCT). As a result, a remarkable improvement in the wear resistance of the cryogenically treated specimens was observed. In addition, DCT increases the percentage of carbides and their homogeneity in distribution. An optimum holding time was found in the deep cryogenic temperature, in which the hardness and wear resistance show maximum values. Moreover, the wear debris and worn surfaces showed that the dominant mechanism in the wear test is adhesive. © 2010 Elsevier Ltd.

Rezaee A.A.,Islamic Azad University at Tehran | Yaghmaee M.H.,Ferdowsi University of Mashhad | Rahmani A.M.,Islamic Azad University at Tehran | Mohajerzadeh A.H.,Ferdowsi University of Mashhad
Journal of Network and Computer Applications | Year: 2014

wireless sensor networks consist of a large number of small, lo-poer sensors that communicate through wireless links. wireless sensor networks for healthcare have emerged in recent years as a result of the need to collect data about patients' physical, physiological, and vital signs in the spaces ranging from personal to hospital and availability of the lo cost sensors that enables this data collection. One of the major challenges in these networks is to mitigate congestion. In healthcare applications, such as medical emergencies or monitoring vital signs of patients, because of the importance and criticality of transmitted data, it is essential to avoid congestion as much as possible (and in cases hen congestion avoidance is not possible, to control the congestion). In this paper, a data centric congestion management protocol using AQM (Active Queue Managements) is proposed for healthcare applications ith respect to the inherent characteristics of these applications. This study deals ith end to end delay, energy consumption, lifetime and fairness. The proposed protocol hich is called HOCA avoids congestion in the first step (routing phase) using multipath and QoS (Quality of Service) aare routing. And in cases here congestion cannot be avoided, it ill be mitigated via an optimized congestion control algorithm. The efficiency of HOCA as evaluated using the OPNET simulator. Simulation results indicated that HOCA as able to achieve its goals. © 2013 Elsevier Ltd.

Amirfakhrian M.,Islamic Azad University at Tehran
Journal of Intelligent and Fuzzy Systems | Year: 2011

In this research an algebraic fuzzy equation of degree n with crisp coefficients and fuzzy variable has been introduced and presented an iterative method to find the fuzzy roots of it, numerically. An algorithm also has been presented to generate a sequence that can be converged to the root of an algebraic fuzzy equation. © 2011 - IOS Press and the authors. All rights reserved.

Keshavarzi R.,Islamic Azad University at Tehran
Lasers in Engineering | Year: 2011

In oil and gas well completion, perforating is a process of creating tunnels through the cemented steel casing and rock formation to let the formation fluid flow into the well. Current explosive shaped charge perforating methods can cause formation damage that results in a reduction of the permeability and necessitates costly post-perforation operations. Fracturing is also the process of initiation and propagation of a crack by pumping fluid at relatively high flow rates to enhance the production of oil and gas wells. This fluid pressure initiates a fracture and extends it into the rock medium. One of the newest technologies recommended as a suitable alternative for conventional perforating methods and fracture initiation is high power laser technology. This paper assesses the efficacy of high power lasers in perforation and fracture initiation of oil and gas wells. © 2011 Old City Publishing, Inc.

Fakhri A.,Islamic Azad University at Tehran | Adami S.,Islamic Azad University at Tehran
Journal of the Taiwan Institute of Chemical Engineers | Year: 2014

The adsorption characteristics of Cephalosporins antibiotics from aqueous solution were investigated using magnesium oxide (MgO) nanoparticles. Liquid phase adsorption experiments were conducted. Batch adsorption studies are carried out by observing the effect of experimental parameters, namely amount of adsorbents, pH, temperature and contact time. The drug removal data were fitted on Langmuir adsorption equations. The pseudo second-order kinetic model was indicated with the activation energy of 7.6682 and 5.3745kJ/mol for Cephalexin and Cefixime, respectively. The values of the enthalpy (δH#) and entropy of activation (δS#) were 5.0851kJ/mol and -286.67J/molK for Cephalexin; 3.1952kJ/mol and -303.70J/molK for Cefixime, respectively. The free energy of activation (δG#) at 30°C was 97.9kJ/mol. Thermodynamic analysis showed negative values of δG° indicating adsorption was favourable and spontaneous, negative values of δH° indicating exothermic physical adsorption of Cephalosporins using MgO nanoparticles. © 2013 Taiwan Institute of Chemical Engineers.

Chehreh Chelgani S.,Islamic Azad University at Tehran | Jorjani E.,Islamic Azad University at Tehran
Fuel | Year: 2011

Artificial neural network was used to predict the effects of operational parameters on coal desulfurization using peroxyacetic acid from microwave pretreated coal. Coal particle size (150-1125 μm), leaching temperature (25-85 °C), leaching time (0-120 min), microwave irradiation power (0-1000 W) and time (0-110 s) were used as inputs to the network. The outputs of the model were organic and inorganic sulfur reductions for 40 of the data sets. The GRNN artificial neural network with spread of 0.3 was used to estimate both organic and inorganic sulfur reduction from a combined database, which was established from microwave pretreatment and leaching experiments. Thirty-two data sets were used for training and eight data sets for testing. Simulated values obtained from the neural network, correspond closely to the experimental results. Satisfactory correlations of R2 = 0.99 and 0.97 were achieved during the testing stages of the prediction of inorganic and organic sulfur reductions respectively. © 2011 Elsevier Ltd. All rights reserved.

Razani M.,Islamic Azad University at Tehran | Yazdani-Chamzini A.,Islamic Azad University at Tehran | Yakhchali S.H.,University of Tehran
Safety Science | Year: 2013

Roof fall is one of the most important hazards connected with underground coal mines, because significantly affects financial and human losses. On the other hand, according to different parameters make a significant impact on roof fall and these factors are ill-defined or even immeasurable, this problem is an uncertain and complex issue. Fuzzy logic is a useful tool to handle the existing uncertainty to be more adapted to the real world problems. In this paper, fuzzy inference system (FIS) is applied to predict roof fall rate more accurate, precise, and sure for controlling, mitigating, and/or even eliminating the risk of roof fall. The model utilizes subtractive clustering method to generate fuzzy rules based on 109 data of roof performance from US coal mines. The established model is evaluated by testing dataset based on three indices, including coefficient of determination (R2), mean absolute error (MAE), and root mean square error (RMSE). The results derived from the FIS model in comparison with artificial neural network (ANN) and multivariate regression (MVR) model demonstrate that prediction of roof fall rate by the FIS model is more accurate and satisfied. © 2012 Elsevier Ltd.