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Gholami R.M.,Islamic Azad University at Tehran | Borghei S.M.,Sharif University of Technology | Mousavi S.M.,Tarbiat Modares University
Hydrometallurgy | Year: 2011

A spent processing catalyst from an Iranian oil refinery was initially characterized physically and chemically. Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were used to mobilize Al, Co, Mo and Ni from the spent catalysts under optimized conditions in batch cultures. The characteristics of the bioleach solution (pH, Eh, cell concentration and Fe(II)/Fe(III) concentration) were determined along with the concentration of metal values extracted from the catalyst. The results showed that after bioleaching using A. ferrooxidans in the presence of ferrous sulfate, maximum extractions of 63% Al, 96% Co, 84% Mo and 99% Ni were achieved after 30 days at pH 1.8-2.0. However, the highest extractions using A. thiooxidans in the presence of sulfur were 2.4% Al, 83% Co, 95% Mo and 16% Ni after 30 days at pH 3.9-4.4. The recovery of these metals decreases the environmental impact of the waste catalyst and the recycled product can be further used for industrial purposes. © 2010 Elsevier B.V.

Hashemi M.,Islamic Azad University at Tehran
Iranian Journal of Pharmaceutical Research | Year: 2014

Ischemia Reperfusion injury is the tissue damage caused when blood supply returns to the tissue after a period of ischemia or lack of oxygen. In this study, the effect of pentoxyfylline on BCL-2 gene expression changes and cell injury in kidney of rat following Ischemia Reperfusion were evaluated. In this experimental study, 20 male wistar rats with average weight of 250-300 g were selected and then were accidently divided them on two tenth group of control and treatment groups. In the control group, celiotomy was performed by ventral midline incision. The left kidney was isolated, and then both the renal artery and vein were obstructed. After 60 minutes of warm ischemia, vessel obstruction resolved and the right kidney was removed. 72 hours after reperfusion, tissue samples were taken from left kidney for Tunel assay. We used quantitative real time PCR for detection of BCL-2 gene expression in treated groups and then compared them to control samples. In the treatment group, the cell death changes, showed lower level than the control group. The results also showed the BCL-2 gene expression was declined in ischemia group as campared to PNT drug group. The pentoxyfylline might have a role in control of apoptosis result from Ischemia- reperfusion and quantitative real-time PCR can be used as a direct method for detection BCL-2 gene expression in tested samples and normal samples. © 2014 by School of Pharmacy Shaheed Beheshti University of Medical Sciences and Health Services.

Jouki M.,Islamic Azad University at Tehran | Khazaei N.,Urmia University | Ghasemlou M.,University of Tehran | Hadinezhad M.,University of Tehran
Carbohydrate Polymers | Year: 2013

In this study an edible film plasticized with glycerol was successfully prepared from cress seed gum (CSG). The physical, optical, water vapor permeability (WVP) and mechanical properties of CSG films incorporated with three levels of glycerol (25%, 35%, and 50% w/w) as plasticizer were determined. Dynamic mechanical thermal analysis was used to determine the glass transition temperature. WVP of the films was found to increase as the glycerol content increased from 25% to 50% w/w in the formulation, resulted in improvement of films flexibility and significantly lower tensile strength and higher elongation at break. The color measurement values showed that increasing the glycerol concentration in polymer matrix caused the b and L values increased while ΔE value decreased. The electron scanning micrograph indicated smooth and uniform surface morphology without signs of phase separation between the film components. The results of the present study demonstrated that CSG can promisingly be used in producing edible films with improved quality characteristics. © 2013 Elsevier Ltd. All rights reserved.

Hosseini S.H.,Islamic Azad University at Tehran | Sadeghi M.,Islamic Azad University at Saveh
Current Applied Physics | Year: 2014

Aligned magnetic blend of polystyrene-polyvinylpyrrolidone (PS-PVP) nanofibers were prepared by this method. First, polystyrene-polyvinylpyrrolidone (PS-PVP) blend solution in THF was synthesized. Then magnetic of PS-PVP-Fe 3O4-polyethylene glycol (PEG) was prepared by masking method. Finally, magnetic nanofiber of PS-PVP-Fe3O4-PEG was prepared by electrospinning method, too. An electric potential difference of 25 kV was applied between the collector and a syringe tip, and the distance between the collector and the tip was 13 cm. Fe3O4 is exhibit various magnetic properties of which the complex permeability and the permittivity, in particular, are important in determining their high frequency characteristics. The magnetic oxide particles and nanofiber of nanometer size were characterized by TEM and SEM respectively. The thermal properties of nanofibers were determined by TGA and DSC. The magnetic characterization of the fibers was also performed by VSM and AFM techniques. On the other hand, nanofiber with diameters ranging from 30 to 40 nm, showing at room temperature, coercive field values of around 25 kV and saturation magnetization was 1.1 emu/g. Microwave reflection loss of the sample was tested at 8-12 GHz microwave frequencies and the results showed that magnetic nanofiber possessed the microwave absorbing properties. © 2014 Elsevier B.V. All rights reserved.

Asadi M.,Islamic Azad University at Tehran | Xie G.,Northwestern Polytechnical University | Sunden B.,Lund University
International Journal of Heat and Mass Transfer | Year: 2014

An impressive amount of investigations has been devoted to enhancing thermal performance of microchannels. The small size of microchannels and their ability to dissipate heat makes them as one of the best choices for the electronic cooling systems. In this paper, a comprehensive review of available studies regarding single and two-phase microchannels is presented and analyzed. 219 articles are reviewed to identify the heat transfer mechanisms and pressure drops in microchannels. This review looks into the different methodologies and correlations used to predict the heat transfer and pressure drop characteristics of microchannels along the channel geometries and flow regimes. The review shows that earlier studies (from 1982 to 2002) were largely conducted using experimental approaches, and discrepancies between analytical and experimental results were large, while more recent studies (from 2003 to 2013) used numerical simulations, correlations for predicting pressure drop and heat transfer coefficients were considerably more accurate. © 2014 Elsevier Ltd. All rights reserved.

Rashad A.M.,Aswan University | Abbasbandy S.,Islamic Azad University at Tehran | Chamkha A.J.,Public Authority for Applied Education and Training
Journal of Heat Transfer | Year: 2014

In recent years, nanofluids have attracted attention as a new generation of heat transfer fluids in building heating, heat exchangers, plants, and automotive cooling applications because of their excellent thermal performance. Various benefits of the application of nanofluids include improved heat transfer, heat transfer system size reduction, minimal clogging, microchannel cooling, and miniaturization of systems. In this paper, a study of steady, laminar, natural convection boundary-layer flow adjacent to a vertical cylinder embedded in a thermally stratified nanofluid-saturated non-Darcy porous medium is investigated. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis, and a generalized porous media model, which includes inertia and boundary effects, is employed. The cylinder surface is maintained at a constant nanoparticles volume fraction, and the wall temperature is assumed to vary with the vertical distance according to the power law form. The resulting governing equations are nondimensionalized and transformed into a nonsimilar form and then solved by Keller box method. A comparison is made with the available results in the literature, and our results are in very good agreement with the known results. A parametric study of the physical parameters is made, and a representative set of numerical results for the velocity, temperature, and volume fraction, as well as local shear stress and local Nusselt and Sherwood numbers, are presented graphically. The salient features of the results are analyzed and discussed. The results indicate that, when the buoyancy ratio or modified Grashof number increases, all of the local shear stress, local Nusselt number, and the local Sherwood number enhance while the opposite behaviors are predicted when the thermophoresis parameter increases. Moreover, increasing the value of the surface curvature parameter leads to increases in all of the local shear stress and the local Nusselt and Sherwood numbers while the opposite behaviors are obtained when either of the thermal stratification parameter or the boundary effect parameter increases. © 2014 by ASME.

Peyghan A.A.,Islamic Azad University at Tehran | Moradi M.,Iranian Materials and Energy Research Center
Thin Solid Films | Year: 2014

Using density functional theory including dispersion correction, we have studied adsorption of nitrous oxide (N2O) molecule on the pristine and antisite defected graphene-like silicon carbide (h-SiC) in terms of energetic, geometric and electronic properties. The N2O is weakly adsorbed on the pristine sheet releasing energies in the range of 14.2 to 28.9 kJ/mol. Electronic properties of the pristine h-SiC are not influenced by the adsorption process. It is predicted that the N2O molecule can strongly interact with the Si-antisite defected sheet (DSi) in such a way that its oxygen atom diffuses into the surface, releasing an N2 molecule. The energy of this reaction is calculated to be about 540.1 kJ/mol and the electronic properties of the DSi are slightly altered.

Sedaghat S.,Islamic Azad University at Tehran
Fullerenes Nanotubes and Carbon Nanostructures | Year: 2015

In this paper, hybrid nanocomposites of modified carbon nanotubes (MWNT-COOHs) (FCNTs) with silver nanoparticles and atenolol were prepared by wet chemical process and investigated by X-ray diffraction, scanning electron microscopy (SEM). About 29 nm of silver particle is determined in SEM micrographs. Silver nanoparticles were virtually fixed on the surface of the functionalized nanotubes. Nanocomposites have excellent antibacterial activities against Escherichia coli (E. coli), so in vitro antibacterial tests were performed to determine the antibacterial capability of the Ag/FCNTs nanocomposites. © 2014 Taylor and Francis Group, LLC.

Faghidian S.A.,Islamic Azad University at Tehran
International Journal of Solids and Structures | Year: 2014

A smoothed inverse eigenstrain method is developed for reconstruction of residual field from limited strain measurements. A framework for appropriate choice of shape functions based on the prior knowledge of expected residual distribution is presented which results in stabilized numerical behavior. The analytical method is successfully applied to three case studies where residual stresses are introduced by inelastic beam bending, laser-forming and shot peening. The well-rehearsed advantage of the proposed eigenstrain-based formulation 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. The smoothed inverse eigenstrain approach allows suppressing fluctuations that are contrary to the physics of the problem. Furthermore, a comprehensive discussion is performed on regularity of the asymptotic solution in the Tikhonov scheme and the regularization parameter is then exactly determined utilizing Morozov discrepancy principle. Gradient iterative regularization method is also examined and shown to have an excellent convergence to the Tikhonov-Morozov regularization results. © 2014 Elsevier Ltd. All rights reserved.

Parvizi A.,Islamic Azad University at Tehran | Abrinia K.,University of Tehran
International Journal of Mechanical Sciences | Year: 2014

In this paper, an upper bound solution is used to determine the ring rolling power and force. An admissible velocity field and strain rates are derived from the parametric definition of streamlines in the deforming zone. Minimizing the upper bound power with respect to neutral point position, the neutral point situation and the rolling force are determined. The present method is validated using experimental results extracted from ring rolling mill. Moreover, using ABAQUS/Explicit software, the ring rolling process was simulated in every respect. Comparison of the present upper bound results with those from experimental study, finite element simulation and our previous slab analysis, have proved the accuracy of the present analysis. As compared with the FEM simulation, this method is very much quicker and less expensive and could be used as an engineering tool in the ring rolling industrial applications. © 2013 Elsevier Ltd.

Jafari R.,Islamic Azad University at Tehran | Golnabi H.,Sharif University of Technology
Optics and Laser Technology | Year: 2011

In this article, two optical-fibre probes used in displacement measurements are reported. In one arrangement, two optical fibres with protective buffer jackets are placed together, while in the second arrangement, the protective buffer jackets are removed and the two fibres are placed with the claddings in contact, with a concomitant smaller centrecentre distance. As the core and cladding diameters are the same in both probes, the effect of the centrecentre distance on double-fibre designs can be investigated. The reflected output powers are recorded for the probes as a function of the axial distance from a reflective surface. A theoretical model is also implemented, which considers the effect of centre-to-centre separation of the optical fibres on the sensor performance, and the experimental results are compared with the theoretical predictions. The computed response curve includes a dead region where there is no response to displacement, an active region with an increasing reflection power with increasing displacement and a decaying region in which the reflected power decreases with increase in displacement. The operational performance criteria of the two probes are also investigated. The hysteresis, reproducibility and time stability of the probes are investigated. The hysteresis is approximately 1%, reproducibility approximately 1.1% and time stability is better than 1.5% (600 s time scale) in both probes. © 2010 Elsevier Ltd.

Mirzaaei M.,Islamic Azad University at South Tehran | Mirzaei M.,Islamic Azad University at Tehran
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2011

Density functional theory (DFT) calculations were performed to optimize the structures of representative (10,0) zigzag and (6,6) armchair gallium phosphide nanotubes (GaPNTs). Electric filed gradient (EFG) tensors were also calculated for the 69Ga atoms of the optimized structures and they were converted to quadrupole coupling constants (Qcc). Similar optimized properties were obtained for the zigzag and armchair GaPNTs. The computed Q cc parameters for the 69Ga atoms indicated that the electronic environments of the Ga atoms of the tips of nanotubes are significantly different from those of the bodies of the nanotubes; however, the Ga atoms of the bodies of nanotubes almost detect similar electronic environments. The trend reveals the dominant roles of the Ga atoms of the tips of nanotubes in determining the properties of the GaPNTs. © 2011 Elsevier B.V. All rights reserved.

Moghim M.N.,Isfahan University of Technology | Alizadeh F.,Islamic Azad University at Tehran
Coastal Engineering | Year: 2014

An empirical new berm recession formula is derived based on the assumption that the maximum wave force causing armor movement and berm recession is proportional to the maximum wave momentum flux near the structure toe. This concept introduces a more physics-based first principles approach to estimate the berm recession. Recession seems well predicted by the new formula for reshaping berm breakwaters. The results from this formula show a better estimation than earlier formulae used for estimating the berm recession. © 2013 Elsevier B.V.

Naimi B.,Islamic Azad University at Tehran | Voinov A.,University of Twente
Environmental Modelling and Software | Year: 2012

Stella is a popular system dynamics modeling tool, which helps to put together conceptual diagrams and converts them into numeric computer models. Although it can be very useful, especially in participatory modeling, it lacks the power and flexibility of a programming language. This paper presents the StellaR software which translates a Stella model into a model in R, an open source high level programming language. This allows using conceptual modeling tools provided in Stella, together with computational functionality and programming flexibility provided in R. It also opens access to powerful software libraries available in R, which is especially useful for spatial modeling. © 2012 Elsevier Ltd.

Achillea millefolium L., Anethum graveolens L., and Carum copticum L. comprise several relevant species that may be used for the food, cosmetic, perfumery and pharmaceutical industries. Gas chromatography/mass spectrometry analysis revealed thymol to be a major component of A. millefolium, A. graveolens and C. copticum, with its contribution to the essential oils (EOs) being 26.47%, 20.07% and 23.14%, respectively. All three EOs exhibited significant antimicrobial activity against all tested bacterial strains, the A. millefolium oil being the most potent. In addition, A. millefolium EO had the highest antioxidant activity in all conducted assays. The A. millefolium EO had significantly greater radical scavenging activity than C. copticum EO and the reference antioxidant Trolox (IC50 values of 22.11, 26.5 and 28.32 mg/ml, respectively). In addition, a correlation between antioxidant activity and the total phenolic content was found. The A. millefolium EO significantly inhibited nitric oxide production in lipopolysaccharide-activated macrophages (an in vitro model of inflammation). These results clearly show the antimicrobial, antioxidant and anti-inflammatory effects of the plant EOs. © 2015 Elsevier GmbH. All rights reserved.

Beheshtian J.,Shahid Rajaee Teacher Training University | Peyghan A.A.,Islamic Azad University at Tehran | Noei M.,Islamic Azad University at Mahshahr
Sensors and Actuators, B: Chemical | Year: 2013

Electronic sensitivity of pristine, Al- and Si-doped BC3 nanosheets to formaldehyde (H2CO) molecule was investigated by utilizing density functional theory. It was found that H2CO is weakly adsorbed on the sheet, releasing energy of 11.35 kcal/mol, and electronic properties of the sheet are not significantly changed. Although both Al and Si dopings make the sheet more reactive and sensitive to H2CO, Si doping seems to be a better strategy to manufacture H2CO chemical sensors due to the shorter recovery time and higher sensitivity of the Si-doped sheet. Our calculations show that the HOMO/LUMO gap of the Si-doped sheet is significantly decreased from 2.20 to 1.58 eV upon H2CO adsorption, which may increase the electrical conductance of the sheet. Therefore, the doped sheet might convert the presence of H2CO molecules to electrical signal. Moreover, the shorter recovery time of the Si-doped sheet is due to middle adsorption energy of -26.49 kcal/mol in comparison with -40.50 kcal/mol for the Al-doped sheet. © 2013 Elsevier B.V.

Pakrokh Ghavi P.,Islamic Azad University at Tehran
Journal of Food Processing and Preservation | Year: 2015

The technological conditions involved in ultrasound-assisted extraction process were optimized to achieve the maximum yield of crude polysaccharides from the roots of Althea officinalis using a response surface method. The antioxidant effects of polysaccharide extracted under optimal conditions in terms of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and hydroxyl radical-scavenging capacities were then investigated. The results showed that a second-order polynomial regression model with a high R2 value (0.985) can adequately fit the experimental data. The optimal conditions for the maximum yield (12.0%) within the experimental range of the variables studied were at ultrasound power of 86.44W, extraction time of 36.86min, extraction temperature of 79.93C and ratio of liquid/raw material of 39.99mL/g. Under this condition, the extracted polysaccharide effectively scavenged DPPH and OH free radicals, and more concentrations of this polysaccharide indicated potent antioxidant activity in a dose-dependent manner. Practical Applications: Antioxidant polysaccharides of Althea officinalis are conventionally extracted using traditional heating method, which is laborious, time-consuming and requires a large volume of solvent. A technique incorporating ultrasound technology has been developed in the current research, which can help to extract these macromolecules from the roots of this medicinal plant. An investigation is needed to determine the optimum extraction conditions to obtain a desirable yield with high antioxidant activity for the A.officinalis polysaccharide. Optimization of ultrasonic-assisted extraction of the studied polysaccharides can thus provide a functional component to use in food systems. © 2015 Wiley Periodicals, Inc.

Bagherizadeh M.,Islamic Azad University at Tehran | Eshghi M.,Shahid Beheshti University
Nanoscale Research Letters | Year: 2011

In this paper, two novel low-power and high-speed carbon nanotube full-adder cells in dynamic logic style are presented. Carbon nanotube field-effect transistors (CNFETs) are efficient in designing a high performance circuit. To design our full-adder cells, CNFETs with three different threshold voltages (low threshold, normal threshold, and high threshold) are used. First design generates SUM and COUT through separate transistors, and second design is a multi-output dynamic full adder. Proposed full adders are simulated using HSPICE based on CNFET model with 0.9 V supply voltages. Simulation result shows that the proposed designs consume less power and have low power-delay product compared to other CNFET-based full-adder cells. © 2011 Bagherizadeh and Eshghi.

Abdolmohammadi S.,Islamic Azad University at Tehran
Combinatorial Chemistry and High Throughput Screening | Year: 2013

A new, efficient, and solvent-free cyclocondensation reaction of arylmethylidenepyruvic acids with 6- aminouracils is presented that uses a catalytic amount of ZnO nanoparticles (ZnO Nps) as a recyclable catalyst at 70 °C. This protocol has the advantages of high yields (91-98%), easy work-up, very short reaction time (2 h), and using environmentally friendly procedure. © 2013 Bentham Science Publishers.

Dastan F.,Islamic Azad University at Tabriz | Haghparast M.,Islamic Azad University at Tehran
International Journal of Physical Sciences | Year: 2011

Quantum and reversible logic circuits have more advantages than the common circuits, like low power consumption. These circuits are good choice to design future computers. One of the important issues in reversible logic is parity preservation. If parity of inputs and outputs are equal in reversible gate, this gate will be parity preserve. Reversible circuits made by these gates are parity preserve. In this paper we propose a new fault tolerant reversible divider. The proposed fault tolerant reversible divider is the first effort to design fault tolerant reversible division circuit. In this circuit, we use some fault tolerant reversible components like fault tolerant reversible parallel adder, fault tolerant reversible shift register and fault tolerant reversible n-bit register. Hence, we also propose a new fault tolerant reversible full adder, a new fault tolerant reversible n+1-bit parallel adder and a new basic cell for PIPO fault tolerant reversible left-shift register. These parity preserving reversible components are also proposed for the first time in the literature. All the scales are in the nanometric area. © 2011 Academic Journals.

Peyghan A.A.,Islamic Azad University at Tehran | Noei M.,Islamic Azad University at Mahshahr | Yourdkhani S.,Islamic Azad University at Garmsar
Superlattices and Microstructures | Year: 2013

We investigated the electronic sensitivity of pristine and Al-doped BN sheets to para-nitrophenol (p-NP) by using density functional calculations. It was found that p-NP adsorption on the pristine sheet is endothermic and unfavorable. By replacing adsorbing boron atom of the sheet surface by an Al atom, the sheet becomes more reactive to p-NP, so energy of 20.4 kcal/mol is released upon adsorption process. Upon p-NP adsorption on the Al-doped BN sheet, HOMO/LUMO energy gap of the sheet is dramatically decreased from 5.39 to 1.23 eV and it becomes a p-type semiconductor. Thus, the Al-doped BN sheet may transform the presence of p-NP molecule into an electrical signal, and it might be potentially used in p-NP sensors. © 2013 Elsevier Ltd. All rights reserved.

Ardestani M.,Islamic Azad University at Tehran
International Journal of Materials Research | Year: 2015

Ag-°CuO (wt.%) nanocomposite powders were synthesized by calcination at 600 °C of precipitates of copper and silver nitrates and ammonium carbonate. The calcination temperature was determined according to the results of simultaneous thermal analysis of the precipitates. The particle size of the powders was about 50 nm; the crystallite size and the lattice strain of the calcined powders were 34 nm and 0.04 %, respectively. The nanocomposite powders were cold pressed and solid state sintered at 900 °C for 2 and 6 h. It was shown that the sintering duration has more influence on densification of the sintered samples than the cold pressure magnitude. The sintered compacts were re-pressed under 1 GPa. The relative density, hardness and electrical conductivity of the re-pressed samples were 94 %, 65 HRF and 69 % international annealed copper standard conductivity, respectively. © Carl Hanser Verlag GmbH & Co. KG ISSN 1862-5282.

Daeinabi K.,Islamic Azad University at Tehran | Korayem M.H.,Iran University of Science and Technology
Journal of Nanoparticle Research | Year: 2011

Atomic force microscopy is applied to measure intermolecular forces and mechanical properties of materials, nano-particle manipulation, surface scanning and imaging with atomic accuracy in the nano-world. During nano-manipulation process, contact forces cause indentation in contact area between nano-particle and tip/substrate which is considerable at nano-scale and affects the nano-manipulation process. Several nano-contact mechanics models such as Hertz, Derjaguin-Muller-Toporov (DMT), Johnson-Kendall-Roberts-Sperling (JKRS), Burnham-Colton-Pollock (BCP), Maugis-Dugdale (MD), Carpick-Ogletree-Salmeron (COS), Pietrement-Troyon (PT), and Sun et al. have been applied as the continuum mechanics approaches at nano-scale. In this article, indentation depth and contact radius between tip and substrate with nano-particle for both spherical and conical tip shape during nano-manipulation process are analyzed and compared by applying theoretical, semiempirical, and empirical nano-contact mechanics models. The effects of adhesion force, as the main contrast point in different nano-contact mechanics models, on nano-manipulation analysis is investigated for different contact radius, and the critical point is discussed for mentioned models. © 2010 Springer Science+Business Media B.V.

Sheshmani S.,Islamic Azad University at Tehran
Carbohydrate Polymers | Year: 2013

In this study, the effects of two variable parameters, namely the extractives and filler loading level, on the physical properties of composites were examined. Composites based on high density polyethylene (HDPE), bagasse flour (BF) as filler were made by injection molding. In order to increase the interphase adhesion, maleic anhydride grafted polyethylene (MAPE) was added as a coupling agent to all the composites studied. Three different solvents, ethanol-benzene, 1% NaOH and hot-water, were used to remove extractives. Physical properties, namely, water absorption (WA) and thickness swelling (TS) were investigated for a long period. At same filler loading, composites made with extracted bagasse had higher WA and TS values. In addition, the TS of samples showed a similar pattern to the water uptake data. The difference in WA between extracted and unextracted composites is due to blocking of -OH groups by extractives. The results also showed that as the BF content was increased, significant increase in WA and TS occurred. Statistical analysis confirmed that the effects of both variables and their interactions on the WA and TS properties were significant at 1% confidence level. © 2013 Elsevier Ltd. All rights reserved.

Arab A.,Islamic Azad University at Tehran | Ismail N.,University Putra Malaysia | Lee L.S.,University Putra Malaysia
Journal of Intelligent Manufacturing | Year: 2013

In this paper, a new approach to maintenance scheduling for a multi-component production system which takes into account the real-time information from workstations including remaining reliability of equipments as well as work-in-process inventories in each workstation is proposed. To model dynamics of the system, other information like production line configuration, cycle times, buffers' capacity and mean time to repair of machines are also considered. Using factorial experiment design the problem is formulated to comprehensively monitor the effects of each possible schedule on throughput of the production system. The optimal maintenance schedule is searched by genetic algorithm-based optimization engine implemented in a simulation optimization platform. The proposed approach exploits all of makespans of planning horizon to find the best opportunity to perform maintenance actions on degrading machines in a way that maximizes the system throughput and mitigates the production losses caused by imperfect traditional maintenance strategies. Finally the proposed method is tested in a real production line to magnify the accuracy of proposed scheduling method. The experimental results indicate that the proposed approach guarantees the operational productivity and scheduling efficiency as well. © 2011 Springer Science+Business Media, LLC.

Khojier K.,Islamic Azad University | Savaloni H.,University of Tehran | Amani E.,Islamic Azad University at Tehran
Applied Surface Science | Year: 2014

ZnO thin films have many applications in semiconductor devices, such as semiconductor lasers, amplifiers, solar cells, chemical and ultraviolet sensors. We produced ZnO thin films on Si (4 0 0) substrates, using e-beam technique and subsequently annealed them under different conditions (i.e., temperature (200-800), time (60 min and 180 min) and environment (air and oxygen flow). The ZnO (0 0 2) preferred orientation which increases in intensity with annealing temperature and annealing time is deduced from X-ray diffraction (XRD) results. Dislocation density was higher for the films annealed in air which may be caused by the impurities (nitrogen and other species in the air) embedded in the film structure. No significant change in the nano-strain of each group of the samples (annealed under different conditions) was observed. The FESEM images showed a granular structure for annealed samples at 200 C and 800 C and a mixed structure of nanowires and nanosheets for samples annealed at 350 C and 500 C. Two peaks of UV emission and green emission were observed in the photoluminescence (PL) spectra of the produced samples. The UV emission increased with annealing temperature and annealing time showing higher crystal quality while the behavior of the green emission was opposite to that of the UV emission. The ZnO films resulted from annealing in the air showed stronger green emission than those annealed with flow of oxygen indicating higher impurity concentration and oxygen vacancies in the sample. © 2013 Elsevier B.V.

Sadreddini S.,Islamic Azad University at Tehran | Afshar A.,Sharif University of Technology
Applied Surface Science | Year: 2014

In this study, the influences of different concentrations of SiO 2 nano sized particles in the bath on deposition rate, surface morphology and corrosion behavior of Ni-P-SiO2 Composite coatings were investigated. The deposition rate of coating was influenced by incorporation of SiO2 particles. The microstructure was investigated with field emission scanning electron microscopy (FESEM). The amount of SiO 2 was examined by Energy Dispersive Analysis of X-Ray (EDX) and amount of SiO2 nanoparticles co-deposited reached a maximum value at 4.5 %wt. Corrosion behavior of coated aluminum was evaluated by electrochemical impedance spectroscopy (EIS) and polarization techniques. The results illustrated that the corrosion rate decreases (6.5-0.6 μA/cm2) and the corrosion potential increases (-0.64 to -0.3) with increasing the quantity of the SiO2 nanoparticles in the bath. Moreover, Ni-p-SiO2 nano-composite coating possesses less porosity than that in Ni-P coating, resulting in improving corrosion resistance. © 2014 Elsevier B.V.

Haghayeghi R.,Islamic Azad University at Tehran | Kapranos P.,University of Sheffield
Materials Letters | Year: 2013

This work is based on investigations on the influence of electromagnetic fields and ultrasonic vibrations in the resulting microstructure of an AA5457 aluminium wrought alloy. Two different agitation mechanisms, electromagnetic (EM) force field and ultrasonic treatment (UT), are compared as to their respective degree of grain refinement and as a result, a combination of the two methods (EM+UT) is developed and employed in the casting of an AA5754 billet. The application of the compound electromagnetic and ultrasonic fields under optimum conditions delivers a refined and homogeneously distributed as-cast microstructure with clear improvements in mechanical properties. © 2013 Elsevier B.V.

Khademian N.,Islamic Azad University at Tehran | Gholamipour R.,Iranian Research Organization for Science and Technology
Journal of Non-Crystalline Solids | Year: 2013

Cu-based and Zr-based bulk metallic glasses matrix/tungsten fiber composites were produced by infiltration process at different temperatures and times. A characterization based on X-ray diffraction (XRD) and scanning electron microscopy (SEM) is presented. The composites were tested in compression and hardness. The quality of bulk metallic matrix composites is not only experienced by the properties of the matrix and reinforcement but also by the controlling of the infiltration conditions, such as infiltration temperature and time. These parameters are important for wet-ability and interface reaction of the liquid with the reinforcement. It has been found that the reaction layer cannot be detected between the wires and matrix for Cu-base BMGCs; this may be an important difference between Zr-base and Cu-base BMG matrices and their deformation mechanism. © 2013 Elsevier B.V.

Peyghan A.A.,Islamic Azad University at Tehran | Noei M.,Islamic Azad University at Mahshahr
Physica B: Condensed Matter | Year: 2014

Doping of several alkali and alkaline earth metals into sidewall of an armchair ZnO nanotube has been investigated by employing the density functional theory in terms of energetic, geometric, and electronic properties. It has been found that doping processes of the alkali and alkaline metals are endothermic and exothermic, respectively. Based on the results, contrary to the alkaline metal doping, the electronic properties of the tube are much more sensitive to alkali metal doping so that it is transformed from intrinsic semiconductor with HOMO-LUMO energy gap of 3.77 eV to an extrinsic semiconductor with the energy gap of ~1.11-1.95 eV. The doping of alkali and alkaline metals increases and decreases the work function of the tube, respectively, which may influence the electron emission from the tube surface. © 2013 Elsevier B.V.

Tabatabaei M.,Islamic Azad University at Tehran | Haeri M.,Sharif University of Technology
ISA Transactions | Year: 2010

In this paper the characteristic ratios and generalized time constant are defined for all-pole commensurate fractional order systems. The sufficient condition for stability of these systems in terms of their characteristic ratios is obtained. Also an analytical approach for characteristic ratio assignment (CRA) to have a non-overshooting fast closed loop step response is introduced. The proposed CRA method is then employed to design a fractional order controller. Computer simulation results are presented to illustrate the performance of the CRA based designed fractional order controllers. © 2010 ISA. Published by Elsevier Ltd. All rights reserved.

Farivar F.,Islamic Azad University at Tehran | Shoorehdeli M.A.,K. N. Toosi University of Technology
ISA Transactions | Year: 2012

In this paper, fault tolerant synchronization of chaotic gyroscope systems versus external disturbances via Lyapunov rule-based fuzzy control is investigated. Taking the general nature of faults in the slave system into account, a new synchronization scheme, namely, fault tolerant synchronization, is proposed, by which the synchronization can be achieved no matter whether the faults and disturbances occur or not. By making use of a slave observer and a Lyapunov rule-based fuzzy control, fault tolerant synchronization can be achieved. Two techniques are considered as control methods: classic Lyapunov-based control and Lyapunov rule-based fuzzy control. On the basis of Lyapunov stability theory and fuzzy rules, the nonlinear controller and some generic sufficient conditions for global asymptotic synchronization are obtained. The fuzzy rules are directly constructed subject to a common Lyapunov function such that the error dynamics of two identical chaotic motions of symmetric gyros satisfy stability in the Lyapunov sense. Two proposed methods are compared. The Lyapunov rule-based fuzzy control can compensate for the actuator faults and disturbances occurring in the slave system. Numerical simulation results demonstrate the validity and feasibility of the proposed method for fault tolerant synchronization. Copyright © 2011 Published by Elsevier Ltd on behalf of ISA. All rights reserved.

Parandin N.,Islamic Azad University at Kermanshah | Araghi M.A.F.,Islamic Azad University at Tehran
Soft Computing | Year: 2011

In recent years, many numerical methods have been proposed for solving fuzzy linear integral equations. In this paper, we use the divided differences and finite differences methods for solving a parametric of the fuzzy Fredholm integral equations of the second kind with arbitrary kernel and present some examples to illustrate this method. © 2010 Springer-Verlag.

Jouki M.,Islamic Azad University at Tehran
Radiation Physics and Chemistry | Year: 2013

In this study we evaluated the effects of gamma irradiation at doses of 0.0, 0.5, 2.0 and 4.0. kGy and frozen storage as a combination process on improvement of turkey breast meat shelf life. The samples were stored at -18 °C and were undergone microbial, chemical and sensory evaluation at 2-month intervals. However, 4. kGy dose reduced the counts of mesophilic bacteria and coliform by more than 5 log units, while Salmonella was not detected. Irradiation of samples significantly increased peroxide value but had no significant effect on total volatile nitrogen contents, while storage significantly increased the peroxide value and total volatile nitrogen. © 2012 Elsevier Ltd.

Ghiasi R.,Islamic Azad University at Tehran
Journal of Theoretical and Computational Chemistry | Year: 2015

In this work, the structural, electronic properties, 13C and 1H NMR parameters and ¯rst hyperpolarizability of a chromium carbene (OC)5Cr=C(OEt)(-C=C-Ph) complex were theoretically computed in gas phase and different solvents. Also, the solvent effect on structural parameters, frontier orbital energies,-C=C-and C=O stretching frequencies of complex has been carried out based on polarizable continuum model (PCM). The results indicate that the polarity of solvents has played a significant role on the structures and properties of complex. 1H and 13C NMR chemical shifts were calculated by using the gauge-independent atomic orbital (GIAO) method. In analyzing the structural characteristics of this structure, Cr-CO and Cr-Ccarbene bonds were identified and characterized in detail by topological parameters such as electron density ρ(r) and Laplacian of electron density r2ρ(r) from Bader's atom in molecules theory. © 2015 World Scientific Publishing Company.

Akhavein A.,Islamic Azad University at Tehran | Fotuhi Firuzabad M.,Sharif University of Technology
Energy Policy | Year: 2011

Reliability of energy supply is one of the most important issues of service quality. On one hand, customers usually have different expectations for service reliability and price. On the other hand, providing different level of reliability at load points is a challenge for system operators. In order to take reasonable decisions and obviate reliability implementation difficulties, market players need to know impacts of their assets on system and load-point reliabilities. One tool to specify reliability impacts of assets is the criticality or reliability importance measure by which system components can be ranked based on their effect on reliability. Conventional methods for determination of reliability importance are essentially on the basis of risk sensitivity analysis and hence, impose prohibitive calculation burden in large power systems. An approach is proposed in this paper to determine reliability importance of energy producers from perspective of consumers or distribution companies in a composite generation and transmission system. In the presented method, while avoiding immense computational burden, the energy producers are ranked based on their rating, unavailability and impact on power flows in the lines connecting to the considered load points. Study results on the IEEE reliability test system show successful application of the proposed method. © 2010 Elsevier Ltd.

Otadi M.,Islamic Azad University | Mosleh M.,Islamic Azad University | Abbasbandy S.,Islamic Azad University at Tehran
Soft Computing | Year: 2011

In this paper, a new hybrid method based on fuzzy neural network (FNN) for approximate solution of fuzzy linear systems of the form is a square matrix of fuzzy coefficients, are fuzzy number vectors, is presented. Here a neural network is considered as a part of a large field called neural computing or soft computing. Moreover, in order to find the approximate solution of an system of fuzzy linear equations that supposedly has a unique fuzzy solution, a simple algorithm from the cost function of the FNN is proposed. Finally, we illustrate our approach by some numerical examples. © 2011 Springer-Verlag.

Mousavi Anzehaee M.,Islamic Azad University at Tehran | Haeri M.,Sharif University of Technology
Journal of Process Control | Year: 2012

It is proposed to employ melting rate, heat input, and detaching droplet diameter as controlled variables to control heat and mass transfer to work piece in a gas metal arc welding process. A two-layer architecture with cascade configuration of PI and MPC controllers is implemented to incorporate existing constraints on the process variables, improve transient behavior of the closed-loop responses and reduce interaction level. Computer simulation results are presented to indicate usefulness of the proposed controlled variables selection and applying two-layer control architecture to control heat and mass transfer to work piece. © 2012 Elsevier Ltd.

Sinaei M.,Islamic Azad University | Mashinchian A.,Islamic Azad University at Tehran
Journal of Environmental Health Science and Engineering | Year: 2014

Background: Persian Gulf is an exposed and stressed area as a result of oil pollution and other fossil fuels containing PAHs. The susceptibility of using mudskippers to monitor marine pollution, like PAHs, points to the fact that mudskippers are able to accumulate and record the PAHs presented in the coastal environments. Methods: Polycyclic aromatic hydrocarbons (PAHs) were examined in the coastal waters, the sediments and biota (i.e., Boleophthalmus dussumieri) along the coast of the Persian Gulf. PAHs concentrations were measured with HPLC method. Results: Total PAH concentrations in the sea water, the sediments, the liver and the gill tissues ranged between 0.80-18.34 μg/l, 113.50-3384.34 ng g-1 (d w), 3.99-46.64 ng g-1 (d w) and 3.11-17.76 ng g-1 (d w), respectively. PAHs distribution patterns in the sediment and the liver tissue samples were dominated by three- and four-ring structures whereas two- and three-rings were dominated in the water and the gill. Conclusions: This finding revealed a negative eco-risk effects occasionally occur in this area. The higher presence of low condensate ring structures reflected a predominant origin of petrogenic and some cases of pyrolitic sources. © 2014 sinaei and Mashinchian; licensee BioMed Central Ltd.

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.

Rafiee M.,Institute for Advanced Studies in Basic Sciences | Shoaei S.M.,Islamic Azad University at Zanjan | Khalafi L.,Islamic Azad University at Tehran
Electrochimica Acta | Year: 2012

The reactions of electrochemically generated o-quinones, as Michael acceptors, from oxidation of catechols with trialkylphosphites as nucleophiles have been studied using cyclic voltammetry. The reaction mechanism is an EC mechanism and the products of reaction are believed to be dialkylphosphonate derivatives of catechol. The observed homogeneous rate constants (k obs) for reactions were estimated by comparing the experimental voltammetric responses with the digitally simulated results based on the proposed mechanism. A quantitative relation between half-wave potentials of catechols and the reactivities of their corresponding o-quinone were derived. Also the effects of substituted group of trialkylphosphites on rate constants of chemical reactions were studied. © 2012 Elsevier Ltd.

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.

Kazemi M.,Islamic Azad University at Tehran
Bangladesh Journal of Botany | Year: 2016

The present study reports the effect of application of nano-Zn oxide on chemical composition and antiinflammatory properties of Trachyspermum ammi Sprague essential oil and its main compounds. The essential oil was obtained from the seeds of the plant by hydrodistillation and analysed by GC/MS. The oil was predominantly composed of γ-terpinene (33.14%). Regarding the anti-inflammatory activity the oil exhibited a potent nitric oxide scavenging effect and inhibited the expression of inducible NO synthase. These results indicate that essential oil Trachyspermum ammi and its main compounds might be applicable in natural medicine as well as healthy food.

Kazemi M.,Islamic Azad University at Tehran
Natural Product Research | Year: 2015

The objectives of this study were to determine the antiaflatoxin B1 activity in vitro of the essential oil (EO) extracted from the seeds of Carum copticum and to evaluate its antifungal activity in vivo as a potential food preservative. The C. copticum EO exhibited noticeable inhibition on dry mycelium and synthesis of aflatoxin B1 (AFB1) by Aspergillus flavus, completely inhibiting AFB1 production at 4 μL/mL. C. copticum EOs showed the lowest percentages of decayed cherry tomatoes for all fungi compared with the control at 100 μL/mL with values of 5.01 ± 67% for A. flavus and 5.98 ± 54% for Aspergillus niger. The results indicated that the percentage of infected fruits is significantly (p < 0.01) reduced by the EO at 16°C for 30 days. In this case, the oil at 100 μL/mL concentration showed the highest inhibition of fungal infection with a value of 80.45% compared with the control. Thus, the EO of dill could be used to control food spoilage and as a potential source of food preservative. © 2014 Taylor & Francis.

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.

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.

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.

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.

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.

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.

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.

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.

Mazinan A.H.,Islamic Azad University at Tehran
Transactions of the Institute of Measurement and Control | Year: 2015

The present research is focused on the object tracking domain based upon a new probabilistic estimation approach. This is realized through a generalization of the particle filter framework (PFF), in association with a neural network, namely an intelligence-based PFF (IPFF). In this idea, a number of appropriate features of mobile objects should first be considered for use in the process of IPFF realization to make the estimation and better performance. The applicability of the proposed approach has been considered though three separated scenarios, including non-stationary, stationary/non-stationary and finally stationary objects, as long as the standard mean shift object tracking approach is realized as a benchmark approach. The experimental results verify the approach performance improvement. © SAGE Publications.

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.

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.

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.

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.

Sadat Hosseini S.S.,Tafresh University | Jafarnejad A.,Islamic Azad University at Tehran | Behrooz A.H.,Allame Tabatabaee University | Gandomi A.H.,Tafresh University
Expert Systems with Applications | Year: 2011

The optimal utilization of multiple combined heat and power (CHP) systems is a complex problem. Therefore, efficient methods are required to solve it. In this paper, a recent optimization technique, namely mesh adaptive direct search (MADS) is implemented to solve the combined heat and power economic dispatch (CHPED) problem with bounded feasible operating region. Three test cases taken from the literature are used to evaluate the exploring ability of MADS. Latin hypercube sampling (LHS), particle swarm optimization (PSO) and design and analysis of computer experiments (DACE) surrogate algorithms are used as powerful SEARCH strategies in the MADS algorithm to improve its effectiveness. The numerical results demonstrate that the utilized MADS-LHS, MADS-PSO, MADS-DACE algorithms have acceptable performance when applied to the CHPED problems. The results obtained using the MADS-DACE algorithm are considerably better than or as well as the best known solutions reported previously in the literature. In addition to the superior performance, MADS-DACE provides significant savings of computational effort. © 2010 Elsevier Ltd. All rights reserved.

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.

Karimiazari A.,Iran University of Science and Technology | Mousavi N.,Islamic Azad University at Tehran | Mousavi S.F.,University of Tehran | Hosseini S.,Iran University of Science and Technology
Expert Systems with Applications | Year: 2011

Construction industry faces a lot of inherent uncertainties and issues. As this industry is plagued by risk, risk management is an important part of the decision-making process of these companies. Risk assessment is the critical procedure of risk management. Despite many scholars and practitioners recognizing the risk assessment models in projects, insufficient attention has been paid by researchers to select the suitable risk assessment model. In general, many factors affect this problem which adheres to uncertain and imprecise data and usually several people are involved in the selection process. Using the fuzzy TOPSIS method, this study provides a rational and systematic process for developing the best model under each of the selection criteria. Decision criteria are obtained from the nominal group technique (NGT). The proposed method can discriminate successfully and clearly among risk assessment methods. The proposed approach is demonstrated using a real case involving an Iranian construction corporation. © 2011 Published by Elsevier Ltd.

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.

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.

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.

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.

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.

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.

Zendehdel M.,University of Tehran | Hassanpour S.,Islamic Azad University at Tehran
Journal of Physiological Sciences | Year: 2014

The purpose of this study was to examine the effects of intracerebroventricular injection of metoprolol (a β1 adrenergic receptor antagonist), ICI 118,551 (a β2 adrenergic receptor antagonist), and SR 59230R (a β3 adrenergic receptor antagonist) on ghrelin-induced food and water intake by 3-h food-deprived (FD3) cockerels. The chickens were randomly allocated to 4 treatment groups with 8 replicates in each group. A cannula was surgically implanted into the lateral ventricle of the brain. In experiment 1, chickens received the β1 adrenergic receptor antagonist (24 nmol) before injection of the ghrelin (0.6 nmol). In experiment 2, chickens received the β2 adrenergic receptor antagonist (5 nmol) before injection of the ghrelin (0.6 nmol). In experiment 3, birds were injected with ghrelin (0.6 nmol) after the β3 adrenergic receptor antagonist (20 nmol). Cumulative food and water intake were recorded 3-h post injection and analyzed by two-way analysis of variance. According to the results, ghrelin injection reduced food and water intake by broiler cockerels (p ≤ 0.05). The effect of ghrelin on food intake was significantly attenuated by pretreatment with the β receptor antagonist (p ≤ 0.05). Furthermore, the β2 receptor antagonist had no effect on water intake induced by ghrelin. Also, pretreatment with the β1 and β3 receptors antagonists had no effect on ghrelin-induced food and water intake. These results suggest that the effect of ghrelin on cumulative food intake by cockerels is mediated via β2 adrenergic receptors. © 2014 The Physiological Society of Japan and Springer Japan.

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.

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.

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

Matricaria recutita is a herbaceous plant belonging to the Asteraceae family. The present study reports the chemical composition and antimicrobial activity of M. recutita essential oil and its main compounds. The essential oil was obtained from the aerial parts of the M. recutita by hydrodistillation and analyzed by gas chromatography-mass spectrometry. The major components were -bisabolol oxide (38%), followed by camphene (9.11%), sabinene (4.87%), limonene (6%),1,8-cineole (7.12%), camphor (6.54%), and -pinene (6%). Essential oil of chamomile was evaluated for its antibacterial activities against three gram-positive and four gram-negative pathogenic bacteria. The essential oil and its main compounds were particularly active against Bacillus cereus, with the lowest minimum inhibitory concentration and minimum bactericidal concentration value (0.022 and 1.5 μg /mL). In conclusion, these results support the use of the essential oil and its main compounds for their antimicrobial properties. Copyright © Taylor & Francis Group, LLC.

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.

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.

Mousakhani M.,Islamic Azad University at Tehran
International Journal of Production Research | Year: 2013

This paper studies the problem of scheduling flexible job shops with setup times where the setups are sequence-dependent. The objective is to find the schedule with minimum total tardiness. First, the paper develops a mathematical model in the form of mixed integer linear programming and compares it with the available model in the literature. The proposed model outperforms the available model in terms of both size complexity and computational complexity. Then, an effective metaheuristic algorithm based on iterated local search is proposed and compared with a tabu search and variable neighbourhood search algorithms proposed previously for the same problem. A complete experiment is conducted to evaluate the algorithms for performance. All the results show the superiority of the proposed algorithm against the available ones. © 2013 Taylor and Francis.

Safara F.,Islamic Azad University at Tehran
Medical and Biological Engineering and Computing | Year: 2015

Past decades witnessed the expansion of linear signal processing methods in numerous biomedical applications. However, the nonlinear behavior of biomedical signals revived the interest in nonlinear signal processing methods such as higher-order statistics, in particular higher-order cumulants (HOC). In this paper, HOC are utilized toward heart sound classification. Heart sounds are presented by wavelet packet decomposition trees. Information measures are then defined based on HOC of wavelet packet coefficients, and three basis selection methods are proposed to prune the trees and preserve the most informative nodes for feature extraction. In addition, an approach is introduced to reduce the dimensionality of the search space from the whole wavelet packet tree to a trapezoidal sub-tree of it. This approach can be recommended for signals with a short frequency range. HOC features are extracted from the coefficients of selected nodes and fed into support vector machine classifier. Experimental data is a set of 59 heart sounds from different categories: normal heart sounds, mitral regurgitation, aortic stenosis, and aortic regurgitation. The promising results achieved indicate the capabilities of HOC of wavelet packet coefficients to capture nonlinear characteristics of the heart sounds to be used for basis selection. © 2015, International Federation for Medical and Biological Engineering.

Yeh A.,Bowling Green State University | Zerehsaz Y.,Islamic Azad University at Tehran
Quality and Reliability Engineering International | Year: 2013

Most of the existing literature on phase I control of simple linear profiles requires multiple observations because the profile parameters need to be estimated given each subgroup of observations. Such a requirement may not be attainable in practical applications in that the observations collected in phase I for assessing whether the process is in control and estimating the profile parameters may not necessarily follow what is prescribed by the existing phase I methods. This is particularly the case for processes in which only few observations or a single observation per subgroup can be obtained for phase I control. In this work, a control charting mechanism based on a change-point model is proposed for phase I control of simple linear profiles with individual observations. The proposed charting mechanism consists of two control charts. The first control chart, which is essentially based on a likelihood ratio test, is used to monitor the profile parameters. The error standard deviation is monitored using a second control chart, which is constructed on the basis of the recursive residuals. Simulation results show that the control charting mechanism is effective in detecting sustained changes in the profile parameters and/or error standard deviation. The proposed phase I control charting mechanism is used in an application to demonstrate how the proposed control charts can be applied in practice. Copyright © 2012 John Wiley & Sons, 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.

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.

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.

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.

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.

Sheshmani S.,Islamic Azad University at Tehran | Ashori A.,Iranian Research Organization for Science and Technology | Hamzeh Y.,University of Tehran
Journal of Applied Polymer Science | Year: 2010

In this study, nanocomposites based on polyethylene (PE), maleic anhydride grafted polyethylene (MAPE), recycled newsprint fibers, and organically modified montmorillonite (nanoclay) were made by injection molding. The effects of two variable factors, namely, the nanoclay and MAPE contents, on the composite physical properties were examined. All blends were made with a fiber-to-PE weight ratio of 30:70. The results show that the addition of MAPE and nanoclay in the nanocomposite formulation significantly improved both the stability and water absorption properties. The improving effect of MAPE could be explained by the improvement in the quality of adhesion between the polymer and fibers. Nanocomposites containing 5 wt % MAPE and nanoclay exhibited minimum water absorption during the whole duration of immersion. The results of this research study show that wood-plastic composites treated with a coupling agent and nanoclay will be desirable as building materials for outdoor applications. © 2010 Wiley Periodicals, Inc.

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.

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.

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.

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.

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.

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.

Mondali M.,Islamic Azad University at Tehran | Abedian A.,Sharif University of Technology
International Journal of Non-Linear Mechanics | Year: 2013

The creep deformation behavior of short fiber composites has been studied by an approximate analytical model. A perfect fiber/matrix interfacial bond is assumed and a power law function is considered for describing the steady state creep behavior of the matrix material. The results obtained from the proposed analytical solution satisfy the equilibrium and constitutive creep equations. Also, a parametric study was undertaken to define the effects of geometric parameters on the steady state creep strain rate of short fiber composites. The present model is then validated using the results of finite element method. The predicted strain rate and stress components by the proposed analytical approach exhibit good agreement with the finite element results. © 2013 Elsevier Ltd.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Nasirian N.,Islamic Azad University at Shoshtar | Almassi M.,Islamic Azad University at Tehran | Minaei S.,Tarbiat Modares University | Widmann R.,University of Duisburg - Essen
International Journal of Hydrogen Energy | Year: 2011

Lignocellulosic biomass contains approximately 70-80% carbohydrates. If properly hydrolyzed, these carbohydrates can serve as an ideal feedstock for fermentative hydrogen production. In this research, batch tests of biohydrogen production from acid-pretreated wheat straw were conducted to analyze the effects of various associated bioprocesses. The objective of the pretreatment phase was to investigate the effects of various sulfuric acid pretreatments on the conversion of wheat straw to biohydrogen. When sulfuric acid-pretreated solids at a concentration of 2% (w/v) were placed in an oven for 90 min at 120 °C, they degraded substantially to fermentative gas. Therefore, wheat straw that is pre-treated under the evaluated conditions is suitable for hydrolysis and fermentation in a batch test apparatus. Five different conditions were evaluated in the tests, which were conducted in accordance with standard batch test procedures (DIN 38414 S8): fresh straw, pre-treated straw, supernatants derived from acid hydrolyzation, Separate Hydrolysis and Fermentation (SHF) and Simultaneous Saccharification and Fermentation (SSF). The SSF method proved to be the most effective and economical way to convert wheat straw to biohydrogen. The hydrogen yield by this method was 1 mol H2/mol glucose, which resulted from 5% carbon degradation (ηC, gas) or the equivalent of 64% of the hydrogen volume that was produced in the reference test (glucose equivalent test). This method also proved to have the shortest lag phase for gas production. The supernatants derived from acid hydrolysis were very promising substances for continuous tests and presented excellent characteristics for the mass production of biohydrogen. For example, a 1.19 mol H2/mol glucose (76% glucose equivalent) yield was achieved along with a 52% carbon degradation. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

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.

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.

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.

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 Saveh
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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Pazouki S.,Islamic Azad University at Tehran | Haghifam M.-R.,Tarbiat Modares University | Moser A.,RWTH Aachen
International Journal of Electrical Power and Energy Systems | Year: 2014

Renewable energy based Distributed Energy Resources (DERs) are essential of coping with greenhouse gases emission and growing energy needs. Combined Heat and Power (CHP), Wind, Energy Storage technologies (ES) and Demand Response programs (DR) have been confirmed the valuable resources. In this paper, Energy Hub (EH) as a super node in electrical distribution network receives various energy carriers; gas, electricity and wind in its input, and then after conversion, storage, direct connection or shifting demands provides hub required demands; electricity, heat, gas and water. The hub is optimally operated based on objective function considering economic, greenhouse gases emission, reliability and efficiency terms in predicted and stochastic environment of wind, electricity demand and Real Time Pricing (RTP) market. A Monte Carlo simulation is employed to generate scenarios tree based predicted RTP, wind and electricity demand. GAMS; high level algebraic modeling software is employed to reduce and read scenarios for Stochastic Programming in Mixed Integer Linear Programming (MILP) model of proposed approach to endorse when and what technologies should be optimally operated to achieve minimum operation costs and maximum reliability improvement with comparison of nine different cases (wind, price and electricity demand certainties and uncertainties) to satisfy a commercial load. Impact of DERs and effect of wind, price and demand uncertainties are investigated on total hub operation costs and hub reliability and also on which technology most be operated. © 2014 Elsevier Ltd. All rights reserved.

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.

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.

Pashangpour M.,Islamic Azad University | Peyghan A.A.,Islamic Azad University at Tehran
Journal of Molecular Modeling | Year: 2015

The potential application of the intrinsic and extrinsic (8,0) zigzag single-walled C3N nansheets as chemical sensor for CO molecules has been investigated using density functional theory calculations. The calculation shows that the pristine sheet is a semiconductor with a HOMO-LUMO gap (Eg) of about 2.19 eV. The pristine and B-doped sheets can weakly adsorb a CO molecule with the adsorption energies of -4.8 and −4.6 kcal mol-1, and their electronic properties are not sensitive to this molecule. By replacing a C atom with an Al atom, localized impurity states are induced under the conduction level of the sheet. The binding interaction between the CO molecule and the Al-doped sheet becomes much stronger (Ead = −17.8 kcal mol-1). After the adsorption of CO on the Al-dope sheet, the Eg of the sheet is significantly decreased from 1.07 to 0.73 eV. This leads to a sizable increase in the resistance of the tube. Thus, the Al-doped sheet can show the presence of CO molecules by an electronic signal because of the change in its resistance and conductivity. © 2015, Springer-Verlag Berlin Heidelberg.

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.

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.

Mirjalili M.,Islamic Azad University at Yazd | Karimi L.,Islamic Azad University at Tehran
Journal of the Textile Institute | Year: 2013

Thermal properties, light reflection, dye absorption, and resistance against bacteria growth have made fibers and textiles very important and applicable in industry. These are mainly attributed to the structure and the surface characteristics, and their modification appears to be very contribute to improving the properties of textiles. Most of the methods aimed at such modifications are implemented in a liquid phase. However, cold plasma has some primacy; it can be done in dry areas, does not have any environmental harm or pollution, and reduces the required energy. In this study, polyester was used and its surface properties were investigated under plasma treatment in nitrogen gas for 2 min irradiation with 1 and 2 keV ions with intensities of 0.04, 0.05, 0.06, 0.08, and 0.1 mA. Changes in properties such as dyeability, thermal, and antibacterial activities of samples were investigated after plasma treatment. The results reveal that cold plasma treatment on polyester under nitrogen gas for 2 min has many suitable effects such as more disperse and acidic dye absorption, improvement of crystalline regions, and antibacterial activity in fabric. Besides, Fourier transform infrared shows that plasma treatment does not have any impact on the bulk properties of polyester fabric. © 2013 Copyright The Textile Institute.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Takabi B.,Islamic Azad University at Tehran | Salehi S.,University of Tehran
Advances in Mechanical Engineering | Year: 2014

This paper numerically examines laminar natural convection in a sinusoidal corrugated enclosure with a discrete heat source on the bottom wall, filled by pure water, Al2O3/water nanofluid, and Al 2O3-Cu/water hybrid nanofluid which is a new advanced nanofluid with two kinds of nanoparticle materials. The effects of Rayleigh number (103≤Ra≤106) and water, nanofluid, and hybrid nanofluid (in volume concentration of 0%≤φ≤2%) as the working fluid on temperature fields and heat transfer performance of the enclosure are investigated. The finite volume discretization method is employed to solve the set of governing equations. The results indicate that for all Rayleigh numbers been studied, employing hybrid nanofluid improves the heat transfer rate compared to nanofluid and water, which results in a better cooling performance of the enclosure and lower temperature of the heated surface. The rate of this enhancement is considerably more at higher values of Ra and volume concentrations. Furthermore, by applying the modeling results, two correlations are developed to estimate the average Nusselt number. The results reveal that the modeling data are in very good agreement with the predicted data. The maximum error for nanofluid and hybrid nanofluid was around 11% and 12%, respectively. © 2014 Behrouz Takabi and Saeed Salehi.

Hosseini S.A.,Islamic Azad University at Tehran
Journal of Materials Science: Materials in Electronics | Year: 2016

In this paper, cadmium tungstate (CdWO4) nanoparticles were synthesized via a precipitation method based on the reaction between cadmium nitrate hexahydrate and sodium tungstate dihydrate in water. Besides, three surfactant agents such as sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, and polyethylene glycol were used to investigate their effects on the morphology and particle size of CdWO4 nanoparticles. According to the vibrating sample magnetometer, cadmium tungstate (CdWO4) nanoparticles indicated a ferromagnetic behavior at room temperature. To evaluate the catalytic properties of nanocrystalline cadmium tungstate, the photocatalytic degradations of methyl orange under ultraviolet light irradiation were carried out. The structural, morphological, magnetic, and optical properties of as—obtained products were characterized by techniques such as XRD, SEM, EDX, VSM, and UV–Vis spectroscopy. © 2016 Springer Science+Business Media New York

Parsa J.,Islamic Azad University at Tehran | Etemad-Shahidi A.,Iran University of Science and Technology
Ocean Dynamics | Year: 2011

The main parameters that affect the salinity intrusion in estuaries are their geometric, hydrologic and hydrodynamic characteristics. The recognition of effective parameters and understanding their roles in the salinity intrusion are required for estuarine water management. In this study, the governing equations of the salinity intrusion processes were scaled to derive the effective dimensionless parameters. Then, a previously verified model, CE-QUAL-W2, was utilized as a virtual laboratory to investigate the effects of different governing parameters on the salinity intrusion. Analysis of the results showed that logarithmic functions can be used to describe the effect of dimensionless parameters obtained by scaling of governing equations. Finally, a formula was suggested to predict the salinity intrusion length based on geometrical and hydrodynamic characteristics of alluvial estuaries. © 2011 Springer-Verlag.

Heidari R.,Islamic Azad University at Tehran
Journal of Seismology | Year: 2016

In this study, the 11 August 2012 Mw 6.4 Ahar earthquake is investigated using the ground motion simulation based on the stochastic finite-fault model. The earthquake occurred in northwestern Iran and causing extensive damage in the city of Ahar and surrounding areas. A network consisting of 58 acceleration stations recorded the earthquake within 8–217 km of the epicenter. Strong ground motion records from six significant well-recorded stations close to the epicenter have been simulated. These stations are installed in areas which experienced significant structural damage and humanity loss during the earthquake. The simulation is carried out using the dynamic corner frequency model of rupture propagation by extended fault simulation program (EXSIM). For this purpose, the propagation features of shear-wave including (Formula presented.) value, kappa value (Formula presented.) , and soil amplification coefficients at each site are required. The kappa values are obtained from the slope of smoothed amplitude of Fourier spectra of acceleration at higher frequencies. The determined kappa values for vertical and horizontal components are 0.02 and 0.05 s, respectively. Furthermore, an anelastic attenuation parameter is derived from energy decay of a seismic wave by using continuous wavelet transform (CWT) for each station. The average frequency-dependent relation estimated for the region is (Formula presented.) Moreover, the horizontal to vertical spectral ratio (Formula presented.) is applied to estimate the site effects at stations. Spectral analysis of the data indicates that the best match between the observed and simulated spectra occurs for an average stress drop of 70 bars. Finally, the simulated and observed results are compared with pseudo acceleration spectra and peak ground motions. The comparison of time series spectra shows good agreement between the observed and the simulated waveforms at frequencies of engineering interest. © 2015, Springer Science+Business Media Dordrecht.

Salar Elahi A.,Islamic Azad University at Saveh | Ghoranneviss M.,Islamic Azad University at Tehran
IEEE Transactions on Plasma Science | Year: 2010

We presented a new simple diagnostic based on poloidal magnetic flux for the determination of the plasma position in the IR-T1 tokamak. This instrument consists of two semicircle wires which are installed toroidally on the inner and outer sides of the tokamak chamber and are connected with each other. In order to receive the poloidal flux on the last closed flux surface (LCFS), this instrument is installed on polar coordinates so that the projection of it on the midplane lies on the LCFS. In reality, this instrument receives the difference between the poloidal flux on the inner and outer sides of the LCFS, which we needed in calculating the plasma horizontal displacement. The main benefits of our proposed instrument are that it is a simple and solid loop and also that its output is directly related to the plasma horizontal displacement. Based on this technique, we determined the plasma position, and to compare the result obtained using this method, an array of four magnetic probes is also designed, constructed, and installed on the outer surface of the IR-T1 tokamak and the plasma position is obtained from it. The results are in good agreement with each other. © 2006 IEEE.

Nozari K.,Islamic Azad University at Sari | Pedram P.,Islamic Azad University at Tehran
Europhysics Letters | Year: 2010

In this paper we study the effects of the Generalized Uncertainty Principle (GUP) on the spectrum of a particle that is bouncing vertically and elastically on a smooth reflecting floor in the Earth's gravitational field (a quantum bouncer). We calculate energy levels and corresponding wave functions of this system in terms of the GUP parameter. We compare the outcomes of our study with the results obtained from elementary quantum mechanics. A potential application of the present study is discussed finally. Copyright © EPLA, 2010.

Ghomi H.,Shahid Beheshti University | Khoramabadi M.,Islamic Azad University at Tehran
Journal of Plasma Physics | Year: 2010

Using a two-fluid model, the ion transition from plasma sheath boundary is investigated taking into account the effect of the finite ion temperature. It is shown that by considering the effects of neutral-ion elastic collision on the sheath, there will be an upper as well as a lower limit for the ion transition velocity into the sheath. The dependency of upper and lower limits of the ion transition velocity on the ion temperature is investigated, and it is shown that the finite ion temperature only affects lower limits in non-hot plasmas. Copyright © Cambridge University Press 2009.

Pedram P.,Islamic Azad University at Tehran | Jalalzadeh S.,Shahid Beheshti University
General Relativity and Gravitation | Year: 2010

We present a Chaplygin gas Friedmann-Robertson-Walker quantum cosmological model in the presence of the cosmological constant. We apply the Schutz's variational formalism to recover the notion of time, and this gives rise to Wheeler-DeWitt equation for the scale factor. We study the early and late time universes and show that the presence of the Chaplygin gas leads to an effective positive cosmological constant for the late times. This suggests the possibility of changing the sign of the effective cosmological constant during the transition from the early times to the late times. For the case of an effective negative cosmological constant for both epoches, we solve the resulting Wheeler-DeWitt equation using the Spectral Method and find the eigenvalues and eigenfunctions for positive, zero, and negative constant spatial curvatures. Then, we use the eigenfunctions in order to construct wave packets for each case and obtain the time-dependent expectation value of the scale factors, which are found to oscillate between finite maximum and minimum values. Since the expectation value of the scale factors never tend to the singular point, we have an initial indication that this model may not have singularities at the quantum level. © Springer Science+Business Media, LLC 2009.

Hashemi M.,Payame Noor University | Afzal P.,Islamic Azad University at Tehran
Arabian Journal of Geosciences | Year: 2013

Geochemical anomaly separation and identification using the number-size (N-S) model at Bardaskan area, NE Iran is studied in this paper. Lithogeochemical data were used in this study which was conducted for the exploration for Au and Cu mineralization and enrichments in Bardaskan area. There are two major mineralization phases concluded epithermal gold and a disseminated systems. N-S log-log plots for Cu, Au, Sb, and As illustrated multifractal natures. Several anomalies at local scale were identified for Au (32 ppb), Cu (28 ppm), As (11 ppm), and Sb (0.8 ppm) and the obtained results suggest existence of local Au and Cu anomalies whose magnitudes generally are above 158 and 354 ppm, respectively. The most important mineralization events are responsible for presence of Au and Cu at grades above 1,778 and 8,912 ppm. The study reveals threshold values for Au and Cu are a consequence of the occurrence of anomalous accumulations of phyllic and silicification alteration zones and metamorphic rocks especially in tuffaceous sandstones and sericite schist types. The obtained results were correlated with fault distribution patterns, revealing a positive direct correlation between mineralization in anomalous areas and the faults present in the mineralized system. © 2012 Saudi Society for Geosciences.

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

In the present study, lanthanum doped copper ferrite (CuFe2−xLaxO4) nanoparticles were prepared via a green method with the aid of copper (II) nitrate, iron (III) nitrate, lanthanum (III) nitrate and starch. Starch plays role as capping agent, and reducing in the synthesis of CuFe2−xLaxO4 nanoparticles. The formation of pure crystallized CuFe2−xLaxO4 nanocrystals occurred when the precursor was heat-treated at 800 °C in air for 2 h. The structural, morphological and optical properties of as-obtained products were characterized by techniques such as XRD, EDS, SEM, and UV–visible. The magnetic properties of as-prepared CuFe2−xLaxO4 nanoparticles were also investigated with vibrating sample magnetometer. Furthermore, the photocatalytic properties of as-synthesized CuFe2−xLaxO4 were evaluated by degradation of methyl orange as water contaminant. © 2016 Springer Science+Business Media New York

Zakeri M.,Iranian Materials and Energy Research Center | Hasani E.,Islamic Azad University at Tehran | Tamizifar M.,Iran University of Science and Technology
International Journal of Minerals, Metallurgy and Materials | Year: 2013

TiO2-hydroxyapatite (HA) nanostructured coatings were produced by atmospheric plasma spray method. The effects of starting powder composition and grain size on their mechanical properties were investigated. The microstructure and morphology were characterized by X-ray diffraction and scanning electron microscopy (SEM). It is found that the coating with 10% HA has the best mechanical properties. Based on Rietveld refinement method, the mean grain size of the as-received powder (212 nm) extensively decreases to 66.4 nm after 20 h of high-energy ball milling. In spite of grain growth, the deposited coatings maintain their nanostructures with the mean grain size of 112 nm. SEM images show that there is a lower porosity in the coating with a higher HA content. Optical microscopy images show that uniform thickness is obtained for all the coatings. © 2013 University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

Heidari S.M.,Tarbiat Modares University | Ghaderi M.,Tarbiat Modares University | Afzal P.,Islamic Azad University at Tehran
Applied Geochemistry | Year: 2013

The aim of this study is to delineate and separate mineralization phases based on surface lithogeochemical Au, Ag, As and Cu data, using the Concentration-Area (C-A) fractal method in the Touzlar epithermal Au-Ag (Cu) deposit, NW Iran. Four mineralization phases delineated by multifractal modeling for these elements are correlated with the findings of mineralization phases from geological studies. The extreme phase of Au mineralization is higher than 3.38. ppm, which is correlated with the main sulfidation phase, whereas Ag extreme phase (higher than 52.48. ppm) is associated with silicic veins and veinlets. The resulting multifractal modeling illustrates that Au and Ag have two different mineralization trends in this area. Extreme (higher than 398.1. ppm) and high mineralization phases of Cu from the C-A method correlate with hydrothermal breccias and main sulfidation stage in the deposit, respectively. Different stages of Au mineralization have relationships with As enrichment, especially in high and extreme (higher than 7.9%) phases. The obtained results were compared with fault distribution patterns, showing a positive correlation between mineralization phases and the faults present in the deposit. Moreover, mineralization phases of these elements demonstrate a good correlation with silicification and silicic veins and veinlets. © 2013 Elsevier Ltd.

Akbar Hosseini S.,Islamic Azad University at Tehran
Journal of Materials Science: Materials in Electronics | Year: 2016

In this paper europium vanadate (EuVO4) nanoparticles were prepared via a sonochemical method based on the reaction between europium salt and ammonium metavanadate in water. Moreover, this method is free from any surfactant and organic solvents. The structural, morphological and optical properties of as-obtained products were characterized by techniques such as XRD, EDS, SEM, and UV–visible. The magnetic properties of as-prepared EuVO4 nanoparticles were also investigated with vibrating sample magnetometer. To evaluate the catalytic properties of nanocrystalline europium vanadium oxide, the photocatalytic degradation of methyl orange under ultraviolet light irradiation was carried out. © 2016 Springer Science+Business Media New York

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

A new way of preparing dysprosium titanate (Dy2Ti2O7) nanoparticles has been developed using the sol–gel auto-combustion route, with the aid of dysprosium nitrate, tetra-n-butyl titanate (TNBT) and tyrosine. Tyrosine plays role as fuel, capping agent, and reducing in the synthesis of Dy2Ti2O7 nanoparticles. The formation of pure crystallized Dy2Ti2O7 nanocrystals occurred when the precursor was heat-treated at 800 °C in air for 2 h. The structural, morphological and optical properties of as-obtained products were characterized by techniques such as XRD, EDS, SEM, and UV–visible. The magnetic properties of as-prepared dysprosium titanate nanoparticles were also investigated with vibrating sample magnetometer. Furthermore, the photocatalytic properties of as-synthesized Dy2Ti2O7 were evaluated by degradation of methyl orange as water contaminant. © 2016 Springer Science+Business Media New York

Peeri M.,Islamic Azad University at Tehran | Amiri S.,Tehran University of Medical Sciences
Medical Hypotheses | Year: 2015

While beneficial properties of physical activity and exercise on human health have been extensively reported in literature, the exact mechanism(s) underpinning impacts of exercise are not well understood. Focusing on metabolic disorders, as the main causes of social and economic burden in current century, exercise exhibited promising effects in prevention, alleviation and retardation of these disorders including, type 2 diabetes (T2D), Alzheimer's disease (AD), major depressive disorder (MDD) and obesity. Recent evidence has unmasked the role of mitochondrial dysfunction and chronic inflammation in pathophysiology of these disorders. Despite of the wealth of research on the etiology of metabolic disorders, intimate connections between these diseases, complex pathophysiology and their comorbidity still remains a challenging dilemma. In addition, although physical activity has improving effects on human health, it is not clear that how exercise is able to exert its modulatory effects on outcomes of metabolic disorders. Among several mechanisms, we assumed the hypothesis that exercise mitigates the production of mitochondrial-induced reactive oxygen species (ROS) and danger associated molecular patterns (DAMPs) as the main triggering factors for inflammasome formation. Since inflammasomes are of highly deleterious molecules relevant to pathogenesis of metabolic disorders, we hypothesized that beneficial effects of exercise may be associated with its ability to enhance the mitochondrial biogenesis and glucose transportation through generation of brain derived neurotrophic factor (BDNF). Also, we proposed that boosting impact of exercise on autophagy process accelerates the elimination of damaged mitochondria and thus, results in considerable decrease in production of ROS and DAMPs and consequently sterile inflammation. © 2015 Elsevier Ltd.

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.

Ahadi A.,Islamic Azad University at Tehran | Riahi M.A.,University of Tehran
Geophysics | Year: 2013

The aim of designing deconvolution operators is to extract the reflectivity series from seismic sections. Due to the noise, source signature inconsistency, reflection/transmission, anelastic attenuation, and multiples, the amplitude of a propagating seismic wave varies as a function of time. Because of these factors the frequency spectra of seismic signals narrow with time. Recognition of reflectors using upgoing waves is one of the notable properties of vertical seismic profiling (VSP) data. Designing a deconvolution operator for VSP data based on downgoing waves is considered to be one of the most ideal deconvolution methods intended to produce high-resolution images in routine processing of zero-offset VSP data. For such an analysis, the Gabor deconvolution operator has been designed using the downgoing wavefield and then was applied to the upgoing wavefield, and hyperbolic smoothing was used to estimate the wavelet. The final result of applying the deconvolution operator is a VSP section with superior resolution. To compare this method with customary methods of deconvolution, the Wiener deconvolution was applied to the synthetic and real data, and the results were compared with those of the Gabor deconvolution. © 2013 Society of Exploration Geophysicists.

Haroonabadi H.,Islamic Azad University at Tehran | Haghifam M.-R.,Tarbiat Modares University
Applied Soft Computing Journal | Year: 2011

Deregulation policy has caused some changes in the concepts of power systems reliability assessment and enhancement. In the present research, generation reliability is considered, and a method for its assessment is proposed using intelligent systems. Also, due to the stochastic behavior of power market and generators' forced outages, Monte Carlo Simulation is used for reliability evaluation. Generation reliability merely focuses on the interaction between generation complex and load. Therefore, in this research, based on the type of market and concentration, reserve margin and various future times, a Neuro-Fuzzy system is proposed for evaluation of generation reliability, which is valid and usable for all kinds of power pool markets. Finally, the proposed method is assessed on IEEE-Reliability Test System with satisfactory results. The results further showed that if market becomes more concentrated or price elasticity of demand increases, reliability will improve. © 2011 Elsevier B.V. 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.

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.

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.

Hani A.,Islamic Azad University at Saveh | 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.

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.

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.

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.

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.

Jahanshahi M.,Islamic Azad University at Tehran | Bistouni F.,Islamic Azad University at Qazvin
Microelectronics Reliability | Year: 2015

Systems with high computational capabilities are usually made of a large number of processing elements in order to solve complex problems efficiently. To achieve this purpose, the processing elements must be able to communicate with each other, which can be provided by interconnection networks. Meanwhile, multistage interconnection networks (MINs) are often recommended for use in such systems due to the efficiency and cost-effectiveness. However, there is a fundamental problem in the general structure of these networks called blocking. An important class of MINs is rearrangeable non-blocking MINs that can be used as a cost-effective solution to cope with the blocking problem. Benes network is one of the most popular rearrangeable non-blocking MINs, which has been considered by many researchers over the years. And yet its reliability improvement is an important factor that must be considered in the review of most systems, especially large-scale ones. Based on previous works, there are three main approaches to improve the reliability of MINs: (1) Adding a number of stages to MIN. (2) Using multiple MINs in parallel. (3) Using replicated MINs. In this paper, in order to find the best solution to improve the reliability of the Benes network, all three of these methods are investigated. Reliability analyses show that the use of multiple parallel Benes networks can obtain more advantages than other methods for Benes network. The approach improves the Benes network to be used in large-scale systems in various aspects of reliability namely time-independent terminal reliability, time-independent broadcast reliability, time-dependent terminal reliability, and time-dependent broadcast reliability. © 2015 Elsevier Ltd. All rights reserved.

Ashrafi N.,Islamic Azad University at Tehran
ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011 | Year: 2011

Effect of addition of viscoelastic additive on the stability and precision enhancement of the abrasive waterjet is studied. Cornstarch is chosen to be added to the mixture of water and abrasive for it is readily available in large quantities at low cost. Yet it shows major nonlinear properties valuable for waterjet machining. It is shown that the normal stresses developed in the nonlinear viscoelastic cornstarch remains substantially unchanged throughout effective jet length resulting in an almost completely prismatic jet, most desirable for precision and straight machining. Furthermore, the jet becomes more stable upon increasing the cornstarch percentage. The additive also causes the jet to produce less friction with the surrounding air avoiding possible jet disintegration. Clearly, due to the increase of elastic as well as viscous effects, there is restriction to the pump delivery upon adding the dilatant cornstarch. Different percentages of the additive are therefore examined. It is found that, a 22% additive results in the best performance based on the precision, available pump power and stability of the jet. The experiment was carried out on three products; marble, aluminum and glass. In all cases, kerf angle was reduced significantly. Simulation of the problem is in good agreement with the experimental observations. Copyright © 2011 by ASME.

Mozaffari S.A.,Iranian Research Organization for Science and Technology | Saeidi M.,Islamic Azad University at Tehran | Rahmanian R.,Iranian Research Organization for Science and Technology
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2015

Natural dye extracted from Siahkooti fruit with/without purification by solid phase extraction (SPE) technique was used in the fabrication of DSSC as natural sensitizer. The UV-Vis absorption spectroscopy and Fourier transform infrared (FTIR) were employed to indicate the presence of anthocyanins in the fruit of red Siahkooti. The photoelectrochemical performance and the efficiency of assembled DSSC using Siahkooti fruit dye extract were evaluated and efficiency enhancement was obtained by a preliminary purification of extracted dye. The efficiency and fill factor of the DSSC using purified Siahkooti fruit dye were 0.32% and 0.73%, respectively. The results successfully showed that the DSSC, using Siahkooti fruit extract as a dye sensitizer, is useful for the preparation of environmentally friendly, low-cost, renewable and clean sources of energy. © 2015 Elsevier B.V. All rights reserved.

Davood A.,Islamic Azad University at Tehran | Iman M.,Mashad University of Medical science
Medicinal Chemistry Research | Year: 2011

β-Phenylethylidenehydrazine (PEH) derivatives have been recognized as Gamma-aminobutyric acid aminotransferase (GABA-AT) inhibitors. In this research a group of newly synthesized of PEH analogs, possessing a variety of substituents (Me, OMe, Cl, and CF3) at the 2-, 3-, and 4-position of the phenyl ring, were subjected to docking study and quantitative structure activity relationship (QSAR) analysis. PEH analogs were built by HYPERCHEM program, and conformational studies were performed through semi-empirical method followed by PM3 method. QSAR descriptors were obtained from the EDRAGON and HYPERCHEM, and equations were derived from multilinear regression (MLR) method. The sums of the JGI2, H6m, and E2s were identified as the most significant descriptors. This simple equation can be used to estimate the GABA-AT inhibitory activity for new derivatives of this series of compounds. Docking study was performed by using AutoDock4 program on the all compounds. The obtained results show that the phenyl ring is inserted into the lipophilic pocket and that the NHNH2moiety is situated in a mainly polar region of the enzyme. These computational studies can offer some useful references for understanding the action mechanism and performing the molecular design or modification of this series of GABA-AT inhibitors. © Springer Science+Business Media, LLC 2010.

Canty A.J.,University of Tasmania | Ariafard A.,University of Tasmania | Ariafard A.,Islamic Azad University at Tehran | Sanford M.S.,University of Michigan | Yates B.F.,University of Tasmania
Organometallics | Year: 2013

A computational analysis of the Pd-catalyzed coupling of 3-methyl-2-phenylpyridine (mppH) with [Ph2I]BF4 to form mppPh is supportive of a prior synthetic and kinetic study implicating binuclear palladium species in a rate-limiting oxidation step. The Pd(OAc)2 precatalyst forms the "clamshell" orthopalladated complex [Pd(mpp)(μ-OAc)]2 (8) as the active catalyst, which is oxidized by [Ph2I]+ in a reaction having the highest energy requirement of all steps in the catalytic cycle. In the oxidation reaction, involving formal transfer of Ph+, the electrophilic iodine center interacts initially with a bridging acetate oxygen atom of [Pd(mpp)(μ-OAc)] 2 (8), "Pd-O···IPh2", which transforms to a transition structure with retention of the O·· ·I interaction and formation of a "Pd(μ-Ph-η1) I" bridge in a four-membered ring, "Pd··· Ph···I(Ph)···O-Pd", followed by elimination of PhI with formation of a binuclear Pd(III) cation containing a Pd-Pd bond, [Ph(mpp)Pd(μ-OAc)2Pd(mpp)]+ (14). Cation 14 undergoes mpp···Ph coupling at one Pd center to form the binuclear Pd(II) cation [(mppPh-N)Pd(μ-OAc)2Pd(mpp)]+ (Da). Cation Da may fragment to release mppPh and mononuclear palladium species, followed by orthopalladation at a mononuclear center. However, in an environment of very low acetate concentration and high nitrogen-donor concentration, it is considered far more likely that Da undergoes ligand exchange with release of mppPh and formation of [(mppH-N)Pd(μ-OAc) 2Pd(mpp)]+ (I). Computation shows a low-energy pathway for orthopalladation at cation I that involves nitrogen-donor reagents mppH and mppPh acting as bases to remove a proton as [HN-donor]+. This orthopalladation would complete the cycle and regenerate the catalyst, [Pd(mpp)(μ-OAc)]2 (8). A Hammett plot obtained from a computational analysis of the reaction of [(p-X-C6H 4)(Mes)I]BF4 (X = H, Me, OMe, F, Cl, COMe, CF3) has a reaction constant (ρ) of 1.8, which compares well with the experimental result (ρ = 1.7 ± 0.2). Consistent with this, the analysis reveals the dominant role of the interaction energy for palladium- and iodine-containing fragments in the transition structure. © 2013 American Chemical Society.

Monajjemi M.,Islamic Azad University at Tehran
Biophysical Chemistry | Year: 2015

Cell membrane has a unique feature of storing biological energies in a physiologically relevant environment. This study illustrates a capacitor model of biological cell membrane including DPPC structures. The electron density profile models, electron localization function (ELF) and local information entropy have been applied to study the interaction of proteins with lipid bilayers in the cell membrane. The quantum and coulomb blockade effects of different thicknesses in the membrane have also been specifically investigated. It has been exhibited the quantum effects can appear in a small region of the free space within the membrane thickness due to the number and type of phospholipid layers. In addition, from the viewpoint of quantum effects by Heisenberg rule, it is shown the quantum tunneling is allowed in some micro positions while it is forbidden in other forms of membrane capacitor systems. Due to the dynamical behavior of the cell membrane, its capacitance is not fixed which results a variable capacitor. In presence of the external fields through protein trance membrane or ions, charges exert forces that can influence the state of the cell membrane. This causes to appear the charge capacitive susceptibility that can resonate with self-induction of helical coils; the resonance of which is the main reason for various biological pulses. © 2015 Elsevier B.V. All rights reserved.

Bistouni F.,Islamic Azad University at Qazvin | Jahanshahi M.,Islamic Azad University at Tehran
Journal of Supercomputing | Year: 2014

Supersystems are shown to provide enough computational power to solve complex problems on a real-time basis. In all these systems, the computational parallelism is obtained from multiple processors. Multistage interconnection networks (MINs) play a vital role on the performance of these multiprocessor systems. This paper introduces a new fault-tolerant MIN named as improved extra group network (IEGN). IEGN is designed by existing extra group (EGN) network, which is a regular multipath network with limited fault tolerance. IEGN provides four times more paths between any source-destination pairs compared with EGN. The performance of IEGN has been evaluated in terms of permutation capability, fault tolerance, reliability, path length, and cost. It has also been proved that the IEGN can achieve better results in terms of fault tolerance, reliability, path length and cost-effectiveness, in comparison to known networks, namely, EGN, augmented baseline network, augmented shuffle-exchange network, fault-tolerant double tree, Benes network, and Replicated MIN. © 2014 Springer Science+Business Media New York.

Bistouni F.,Islamic Azad University at Qazvin | Jahanshahi M.,Islamic Azad University at Tehran
Journal of Supercomputing | Year: 2014

Interconnection networks (INs) are used in wide applications of multi-processor systems in order to set up connections between various nodes such as processors and memory modules. However, there is a fundamental problem in INs that has always been considered as one of the most challenging issues in this area. Blocking problem in these networks degrades network performance and consequently the performance of the whole system. In the meantime, the main option for dealing with this problem is the use of non-blocking crossbar networks. However, there are engineering and scaling difficulties when using these networks in large-scale systems. The number of pins on a VLSI chip cannot exceed a few hundreds, which restricts the size of the largest crossbar that should be integrated into a single VLSI chip. Using the idea of multistage implementation of crossbar network can resolve the problem. However, the next problem that arises with this idea is high hardware cost. Therefore, in this paper, a new implementation of crossbar network named scalable crossbar network (SCN) that is a non-blocking network is presented to cope with the aforementioned scaling problems. In addition, performance analysis results show that SCN outperforms multistage crossbar networks and multistage interconnection networks in terms of terminal reliability, mean time to failure, and system failure rate. © 2014, Springer Science+Business Media New York.

Mazinan A.H.,Islamic Azad University at Tehran
Robotics and Autonomous Systems | Year: 2015

With a focus on a number of state-of-the-art techniques in the area of autonomous non-rigid space systems control, realization of a comprehensive strategy is worthy of investigation to handle a set of parameters of the present overactuated processes with model uncertainties. In a word, the subject behind the research is to guarantee the desirable performance of a class of the autonomous space systems, which can be considered through the moments of inertia, the central of mass, the profile of the thrust vector and the misalignments of the propellant engine to deal with mission operation plans. There is the attitude cascade strategy including the low thrust three-axis engine off mode control, the low thrust x-axis engine on mode control and finally the high thrust y,z-axis engine on mode control, respectively. The control strategy is realized in a number of loops, as long as the on and off modes of the propellant engine are focused on the Euler angles control, in finite burn time, and quaternion vector control, in non-burn time, respectively, in line with parameters variations. It is to note that the parameters variations are coherently different in each one of the engine modes. The dynamics of high-low thrusters are taken into real consideration, where the control allocations in association with the pulse-width pulse-frequency modulators are employed to cope with a set of on-off reaction thrusters. The investigated results are finally analyzed in line with some related well-known benchmarks to verify the approach performance. The main contribution and motivation of the strategy investigated here is to propose a novel three-axis comprehensive cascade robust control solution to be able to deal with the parameters of autonomous non-rigid space systems under control with model uncertainties, in a synchronous manner, once the results regarding the tracking of the three-axis referenced commands are efficient with high accuracy along with the recent potential outcomes, researched in this area. © 2015 Elsevier B.V.

Golnabi H.,Sharif University of Technology | Haghighatzadeh A.,Islamic Azad University at Tehran
Optics and Lasers in Engineering | Year: 2010

Design and performance of a two-stage optical beam shaping system based on a plastic fiber-bundle prism-coupled waveguide is described in this study. Such systems offer practical means to modify and change the output beam shape at two stages and also provide quantitative information concerning the output beam intensity profile. It is possible to obtain reflection and image transmittance data by using a light source for the illumination and image analysis by a CCD/digital camera. Using the active lighting, the reflection data and image profiles for the output beam are obtained by a CCD camera and presented in this study. The photograph picture of the illuminating LED beam just at its output point shows a circular shape with a radius of about 5 mm. Picture of the fiber-bundle output beam is also taken, which shows a linear arrangement of circular spot lights almost similar in cross section. The output beam cross section at this stage is in rectangular shape with a dimension of 30 mm width and 3 mm height. In another study CCD images at prism exit face is obtained and image profile is investigated. The final output beam cross section at the second stage of beam shaping is a square with a dimension of about 5 by 5 mm. The transmitted output beam power is also measured at different stages. The conversion efficiency for the fiber bundle at first stage beam shaping is about 70% and for the overall system is about 15%. In another study the relative reflected light off the prism entering face is measured by using two fiber probes in the stripe cable, which shows the ability to monitor such reflections for selecting the prism duct with a lower reflection loss. © 2010 Elsevier Ltd. All rights reserved.

Poor A.,Islamic Azad University at Tehran
Advances in Environmental Biology | Year: 2014

Background: It has been a decade that pyramid marketing has caused a lot of harm to Iranians. Pyramid companies try to justify their activities as legal legitimate activity. But it must be considered whether or not these activities are consistent with state law and jurisprudence and whether or not the conditions in these contracts are consistent with those of legal contracts. The current study is to study aforementioned contracts on the basis of jurisprudence and state law of Iran. © 2013 AENSI Publisher All rights reserved.

Torshizian M.R.,Islamic Azad University at Tehran | Kargarnovin M.H.,Sharif University of Technology
Theoretical and Applied Fracture Mechanics | Year: 2010

An internal crack located within a functionally graded material (FGM) strip bonded with two dissimilar half-planes and under an anti-plane load is considered. The crack is oriented in an arbitrary direction. The material properties of strip are assumed to vary exponentially in the thickness direction and two half-planes are assumed to be isotropic. Governing differential equations are derived and to reduce the difficulty of the problem dealing with solution of a system of singular integral equations Fourier integral transform is employed. Semi closed form solution for the stress distribution in the medium is obtained and mode III stress intensity factor (SIF), at the crack tip is calculated and its validity was verified. Finally, the effects of nonhomogeneous material parameter and crack orientation on the stress intensity factor are studied. © 2010 Elsevier Ltd.

Mollaamin F.,Islamic Azad University at Qom | Monajjemi M.,Islamic Azad University at Tehran
Journal of Computational and Theoretical Nanoscience | Year: 2012

Polymer composites, in general, are made by incorporating filler particles into a polymer matrix. These materials are of major interest, especially when a combination of properties which cannot be obtained in a single material is required. carbon-nanotube (CNT) polymer composites have been a fertile area for modeling studies of microwave dynamics, percolation, and elasticity network formation. Nanocomposite materials have become increasingly important due to their extraordinary properties, which arise from the synergism between the properties of the parent components and their unique interfacial characteristics. Polymer Nanocomposites considerable interest because of the potential applications of these composites in many areas where a certain level of conductivity is required. The ubiquitous research that focus on multiscale modeling has broached different disciplines including solid mechanics, fluid mechanics, materials science, physics, mathematics, biological, and chemistry. In this work, the model has been considered for conductivity of carbonnanotube polymer composites (CNTC) focused on such polymer nanocomposites that can conduct electrical currents upon percolation theory and fractals. Copyright © 2012 American Scientific Publishers.

Uromeihy A.,Tarbiat Modares University | Farrokhi R.,Islamic Azad University at Tehran
Bulletin of Engineering Geology and the Environment | Year: 2012

Water leakage from a dam is always important, but particularly where the preservation of water is essential in semi-dry areas, such Iran. At Kamal-Saleh Dam, the rock mass rating (RMR) and geological strength index(GSI) systems were used to identify the quality of the rock mass, which is particularly important in a foliated material. The RMR results were compared with Lugeon tests undertaken in vertical and oblique holes along the dam foundation and abutments. Although the rock quality designation values could not be used to indicate the quality of the rock mass, they had a direct relationship with the Lugeon values. © 2011 Springer-Verlag.

Bistouni F.,Islamic Azad University at Qazvin | Jahanshahi M.,Islamic Azad University at Tehran
Journal of Parallel and Distributed Computing | Year: 2014

Interconnection networks are used for communication between nodes in multi-processor systems as well as super-systems. These systems require effective communication between the processor and memory blocks and therefore, interconnection networks are considered as the heart of the parallel processing and multi-processor systems. Multistage interconnection networks (MINs) are the main option for use in supercomputer environments that consist of thousands of processing elements. In this paper, a regular class of fault-tolerant MINs named Pars network along with its routing algorithm are presented. Analytical results demonstrate that the Pars network outperforms known regular networks, namely ABN, ASEN, EGN, and IEGN in terms of cost, fault-tolerance, terminal reliability, mean time to failure, and permutation capability. © 2014 Elsevier Inc. All rights reserved.

The research addresses a Lyapunov-based constrained control strategy to deal with the autonomous space system in the presence of large disturbances. The aforementioned autonomous space system under control is first represented through a dynamics model and subsequently the proposed control strategy is fully investigated with a focus on the three-axis detumbling and the corresponding pointing mode control approaches. The three-axis detumbling mode control approach is designed to deal with the unwanted angular rates of the system to be zero, while the saturations of the actuators are taken into consideration. Moreover, the three-axis pointing mode control approach is designed in the similar state to deal with the rotational angles of the system to be desirable. The contribution of the research is mathematically made to propose a control law in connection with a new candidate of Lyapunov function to deal with the rotational angles and the related angular rates of the present autonomous space system with respect to state-of-the-art. A series of experiments are carried out to consider the efficiency of the proposed control strategy, as long as a number of benchmarks are realized in the same condition to verify and guarantee the strategy performance in both modes of control approaches. © 2016 ISA.

Ashkarran A.A.,Islamic Azad University at Tehran
Current Applied Physics | Year: 2010

This paper presents a novel, inexpensive and one-step approach for synthesis of silver nanoparticles (Ag NPs) using arc discharge between titanium electrodes in AgNO3 solution. The resulting nanoparticles were characterized using UV-Vis spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Silver nanoparticles of 18 nm diameter were formed during reduction of AgNO3 in plasma discharge zone. Optical absorption spectroscopy of as prepared samples at 15 A arc current in AgNO3 solution shows a surface plasmon resonance around 410 nm. It was found that sodium citrate acts as a stabilizer and surface capping agent of the colloidal nanoparticles. SEM images exhibit the increase of reduced nanoparticles in 6 min arc duration compared with 1 min arc duration. TEM image of the sample prepared at 6 min arc duration shows narrow size distribution with 18 nm mean particle size. Antibacterial activities of silver nanoparticles were investigated at the presence of Escherichia coli (E-coli) bacteria. © 2010 Elsevier B.V. All rights reserved.

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

In this work, we have successfully prepared rod-like lead tungstate (PbWO4) nanostructures via sonochemical route by utilizing lead (II) acetate trihydrate and sodium tungstate dihydrate as starting materials in water as solvent without adding surfactant. The formation of as-produced nanostructures and their structure, shape and elemental composition were analyzed by means of several techniques including X-ray diffraction, energy dispersive X-ray microanalysis, scanning electron microscopy, and ultraviolet–visible spectroscopy. The magnetic properties of as-prepared lead tungstate nanostructures were also investigated with vibrating sample magnetometer. In addition, methyl orange was chosen as a dye water pollution to evaluate its degradation by as-synthesize lead tungstate under ultraviolet light irradiation. The photocatalysis results reveal that the decolorization of 72 % for methyl orange occurred with PbWO4 nanostructures in 70 min under ultraviolet light irradiation. © 2016 Springer Science+Business Media New York

Ehyaei M.A.,Islamic Azad University at Tehran | Mozafari A.,Sharif University of Technology
Energy and Buildings | Year: 2010

This paper studies the optimization of micro turbine application to meet the electrical, heating and cooling loads of a building by energy, economics and environmental analysis. In this study following three cases are considered: 1: A simple micro gas turbine to meet the electrical power of the building. 2: A simple micro gas turbine to meet the electrical power of the building as well as the power required by heat pump and mechanical refrigerator needed for heating, cooling and domestic hot water (DHW) systems. 3: A CHP micro gas turbine to meet the electrical power of the building as well as part of the power required by heat pump and mechanical refrigerator needed for heating, cooling and DHW systems. The remaining part of the power for heat pump and mechanical refrigerator is provided by the exhaust gases. The research shows that the initial investment is a considerable portion of electricity cost. For an annual interest rate of 10% this portion ranges from 31 to 40% depending on system design configurations, and the lower interest rates results in the smaller portions. It is also concluded that the number of turbine units and electricity cost are highly depended on electricity consumption management. © 2009 Elsevier B.V. All rights reserved.

Nasseri S.H.,University of Mazandaran | Ebrahimnejad A.,Islamic Azad University at Tehran
European Journal of Industrial Engineering | Year: 2010

One of the most interesting models of the linear programming is the flexible linear programming problem. It is shown that by using a suitable membership function for their constraints, we can obtain an equivalent Fuzzy Variable Linear Programming (FVLP) problem. Some methods have been developed for solving these problems by introducing and solving a certain auxiliary problem. Here, we first propose a fuzzy primal simplex algorithm for solving the flexible linear programming problem and then suggest the fuzzy primal simplex method to solve the flexible linear programming problems directly without solving any auxiliary problem. This method will also be especially useful for sensitivity analysis using the primal simplex tableaus. Thereafter, we shall illustrate our method with some examples. Copyright © 2010 Inderscience Enterprises Ltd.

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.

Rostampour E.,Islamic Azad University at Tehran
Journal of Computational Electronics | Year: 2016

Double-walled carbon nanotubes are coaxial nanostructures composed of exactly two single-walled carbon nanotubes, one nested in another. This unique structure offers advantages and opportunities for extending our knowledge and application of the carbon nanomaterials family. An emphasis is placed on the double wall physics that contributes to these structures’ complex inter-wall coupling of electronic and optical properties. The susceptibility tensor of double-walled carbon nanotubes of the “armchair” type the ABAB packing of layers is investigated theoretically in the weak and strong correlation regime. We calculated the spin and charge susceptibility tensor for of the (5,5)@(10,10) double-walled carbon nanotubes using the random-phase approximation in the weak correlation regime. The relationship with the Heisenberg limit (large U/t) is discussed. Our results show that the susceptibility spectra of the (5,5)@(10,10) double-walled carbon nanotubes shift peaks to lower energies with increase in the correlation parameter of the t–J model (Formula presented.). These results show that electronic correlation effects should be taken into account in theoretical studies of double-walled carbon nanotubes. We discuss the relevance of our results for the (Formula presented.) and (Formula presented.) fullerens and (5,5) nanotubes. © 2016 The Author(s)

Pedram P.,Islamic Azad University at Tehran
EPL | Year: 2010

Different candidates of quantum gravity such as string theory, doubly special relativity, loop quantum gravity and black-hole physics all predict the existence of a minimum observable length or a maximum observable momentum which modifies the Heisenberg uncertainty principle. This modified version is usually called the generalized (gravitational) uncertainty principle (GUP) and changes all Hamiltonians in quantum mechanics. In this letter, we use a recently proposed GUP which is consistent with string theory, doubly special relativity and black-hole physics and predicts both a minimum measurable length and a maximum measurable momentum. This form of GUP results in two additional terms in any quantum-mechanical Hamiltonian, proportional to αp3 and α2p4, respectively, where α∼1/M Plc is the GUP parameter. By considering both terms as perturbations, we study two quantum-mechanical systems in the framework of the proposed GUP: a particle in a box and a simple harmonic oscillator. We demonstrate that, for the general polynomial potentials, the corrections to the highly excited eigenenergies are proportional to their square values. We show that this result is exact for the case of a particle in a box. © 2010 Europhysics Letters Association.

Koohestani M.,Islamic Azad University at Tehran | Golpour M.,Tarbiat Modares University
Microwave and Optical Technology Letters | Year: 2010

This letter presents a rectangular slot antenna with a novel coplanar waveguide fed diamond patch covering frequency range from 2.27 to 10.63 GHz based on S11 < - 10 dB, 129φ%. The fabricated antenna has a small size as high as 42 x 42 mm2. The measured results are in good agreement with simulation results. The measured radiation patterns are nearly omni-directional over the most of the frequency bandwidth. The antenna gain ranges from 1.6 to 7.6 dBi. The simple structure, compact size, and good characteristics make the antenna easy to use in commercial ultra wideband systems. © 2009 Wiley Periodicals, Inc.

Sadeghi J.,Islamic Azad University at Qazvin | Sadeghi S.,Islamic Azad University at Tehran | Niaki S.T.A.,Sharif University of Technology
Computers and Operations Research | Year: 2014

In this research, a bi-objective vendor managed inventory model in a supply chain with one vendor (producer) and several retailers is developed, in which determination of the optimal numbers of different machines that work in series to produce a single item is considered. While the demand rates of the retailers are deterministic and known, the constraints are the total budget, required storage space, vendor's total replenishment frequencies, and average inventory. In addition to production and holding costs of the vendor along with the ordering and holding costs of the retailers, the transportation cost of delivering the item to the retailers is also considered in the total chain cost. The aim is to find the order size, the replenishment frequency of the retailers, the optimal traveling tour from the vendor to retailers, and the number of machines so as the total chain cost is minimized while the system reliability of producing the item is maximized. Since the developed model of the problem is NP-hard, the multi-objective meta-heuristic optimization algorithm of non-dominated sorting genetic algorithm-II (NSGA-II) is proposed to solve the problem. Besides, since no benchmark is available in the literature to verify and validate the results obtained, a non-dominated ranking genetic algorithm (NRGA) is suggested to solve the problem as well. The parameters of both algorithms are first calibrated using the Taguchi approach. Then, the performances of the two algorithms are compared in terms of some multi-objective performance measures. Moreover, a local searcher, named simulated annealing (SA), is used to improve NSGA-II. For further validation, the Pareto fronts are compared to lower and upper bounds obtained using a genetic algorithm employed to solve two single-objective problems separately. © 2013 Elsevier Ltd.

Taleizadeh A.A.,University of Tehran | Noori-Daryan M.,Islamic Azad University at Tehran
International Journal of Systems Science | Year: 2015

We studied a decentralised three-layer supply chain including a supplier, a producer and some retailers. All the retailers order their demands to the producer and the producer order his demands to the supplier. We assumed that the demand is price sensitive and shortage is not permitted. The goal of the paper is to optimise the total cost of the supply chain network by coordinating decision-making policy using Stackelberg-Nash equilibrium. The decision variables of our model are the supplier's price, the producer's price and the number of shipments received by the supplier and producer, respectively. To illustrate the applicability of the proposed model numerical examples are presented. © 2014 Taylor & Francis.

Arian M.,Islamic Azad University at Tehran
Carbonates and Evaporites | Year: 2012

Determination of tectonic setting and situation of salt domes in Central Iran is the main purpose of this study. Central Iran is a triangle zone that is bounded by Alborz and Zagros Mountains. According to age and geological setting of evaporitic deposits revealed by field work method, diapiric provinces of Central Iran have been determined and delineated from each other. The location and general trend of the six diapiric provinces are mapped from the border zones of Central Iran by investigation of ETM+ satellite images. Also, based on the shape and orientation investigations of salt domes, tectonic processes (external trigger) are predominant compared to halokinesis (internal trigger) in Central Iran. © 2012 Springer-Verlag.

Kakemam J.,Islamic Azad University at Mahabad | Peyghan A.A.,Islamic Azad University at Tehran
Computational Materials Science | Year: 2013

We have performed density functional theory calculations to investigate the influence of doping of C and Si atoms on the geometric, electronic, solvation, energetic, and field emission properties of a MgO nano-cage. It has been found that substitution of one of the Mg atoms of the nano-cage by either C or Si atom is energetically favorable while substituting an O atom with both of them is unfavorable. It has been also found that replacing Mg or O atom of the cluster by one C atom much more increases its conductance than that by Si one. In fact, HOMO/LUMO gap (Eg) of the cluster is reduced from 4.86 to 1.11 eV, upon replacing Mg atom by C. Based on the obtained results, substituting a Mg atom by either C or Si atom may significantly increase the field electron emission current from the cluster surface by reducing its work function. Overall, doping of Mg12O12 nano-cage by either C or Si atom increases its solubility, conductance, electric dipole moment, kinetic stability, and field electron emission while decreases the Eg and work function. © 2013 Elsevier B.V. All rights reserved.

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.

Taleizadeh A.A.,University of Tehran | Noori-Daryan M.,Islamic Azad University at Tehran | Cardenas-Barron L.E.,Monterrey Institute of Technology
International Journal of Production Economics | Year: 2015

This paper develops a Vendor Managed Inventory (VMI) model for a two-level supply chain comprised of one vendor and several non-competing retailers in which both the raw material and the finished product have different deterioration rates. It is assumed that the market demand for the finished product is deterministic and price sensitive. The proposed inventory model optimizes the retail price, the replenishment frequency of raw material, the replenishment cycle of the product, and the production rate jointly with main objective of maximizing the total profit of the entire chain. In the development of the inventory model the Stackelberg approach is considered between the chain partners where the vendor is leader and the retailers are the followers. Moreover, the concavity of the profit functions is proven and based on this a solution algorithm is developed to find the optimal solutions. At the end, a numerical example is provided to illustrate the use of the production-inventory model and perform a sensitivity analysis. Finally, some conclusions and future research directions are proposed. © 2014 Elsevier B.V. All rights reserved.

Nikoo M.R.,University of Tehran | Kerachian R.,University of Tehran | Karimi A.,Islamic Azad University at Tehran
Water Resources Management | Year: 2012

In this paper, a new methodology is proposed for simultaneous allocation of water and waste load in river basins. A nonlinear interval number optimization model is used to incorporate the uncertainties of model inputs and parameters. In this methodology, the bounds of the uncertain inputs are only required, not necessarily knowing their probability density or fuzzy membership functions. In the proposed model, the existing uncertainties in water demands and monthly available water are considered in the optimization model. Also the economic and environmental impacts of water allocation to the agricultural water users are taken into account. To have an equitable water and waste load allocation, benefits are reallocated to water users using some solution concepts of the cooperative game theory. Results of applying the methodology to the Dez river system in south-western part of Iran show its effectiveness and applicability for water and waste load allocation in an uncertain environment. © 2012 Springer Science+Business Media B.V.

Eskandari M.,Islamic Azad University at Tehran | Homaee M.,Tarbiat Modares University | Mahmodi S.,University of Tehran
Waste Management | Year: 2012

Landfill site selection is a complicated multi criteria land use planning that should convince all related stakeholders with different insights. This paper addresses an integrating approach for landfill siting based on conflicting opinions among environmental, economical and socio-cultural expertise. In order to gain optimized siting decision, the issue was investigated in different viewpoints. At first step based on opinion sampling and questionnaire results of 35 experts familiar with local situations, the national environmental legislations and international practices, 13 constraints and 15 factors were built in hierarchical structure. Factors divided into three environmental, economical and socio-cultural groups. In the next step, the GIS-database was developed based on the designated criteria. In the third stage, the criteria standardization and criteria weighting were accomplished. The relative importance weights of criteria and subcriteria were estimated, respectively, using analytical hierarchy process and rank ordering methods based on different experts opinions. Thereafter, by using simple additive weighting method, the suitability maps for landfill siting in Marvdasht, Iran, was evaluated in environmental, economical and socio-cultural visions. The importance of each group of criteria in its own vision was assigned to be higher than two other groups. In the fourth stage, the final suitability map was obtained after crossing three resulted maps in different visions and reported in five suitability classes for landfill construction. This map indicated that almost 1224. ha of the study area can be considered as best suitable class for landfill siting considering all visions. In the last stage, a comprehensive field visit was performed to verify the selected site obtained from the proposed model. This field inspection has confirmed the proposed integrating approach for the landfill siting. © 2012 Elsevier Ltd.

Mazinan A.H.,Islamic Azad University at Tehran
International Journal of Advanced Manufacturing Technology | Year: 2013

The main purpose of the present research is to organize an algorithm in the area of distillation column system based upon a new AI-based predictive control scheme. In this investigation, at first, an appropriate prediction of the system behavior needs to be accurately made through a number of investigated fuzzy-based model approaches and subsequently the corresponding control scheme is designed to cope with the system in a desirable manner. © 2012 Springer-Verlag London Limited.

Pedram P.,Islamic Azad University at Tehran
International Journal of Theoretical Physics | Year: 2012

We present the energy eigenvalues of a quantum bouncer in the framework of the Generalized (Gravitational) Uncertainty Principle (GUP) via quantum mechanical and semiclassical schemes. In this paper, we use two equivalent nonperturbative representations of a deformed commutation relation in the form [X,P]=ih{stroke}(1+βP 2) where β is the GUP parameter. The new representation is formally self-adjoint and preserves the ordinary nature of the position operator. We show that both representations result in the same modified semiclassical energy spectrum and agrees well with the quantum mechanical description. © 2012 Springer Science+Business Media, LLC.

Forghan B.,Islamic Azad University at Tehran
International Journal of Theoretical Physics | Year: 2012

We calculate the four-point function in λφ 4 theory by using Krein regularization and compare our result, which is finite, with the usual result in λφ 4 theory. The effective coupling constant (λ μ) is also calculated in this method. © 2011 Springer Science+Business Media, LLC.

Nikoo M.R.,Islamic Azad University at Tehran | Kerachian R.,University of Tehran | Niksokhan M.H.,University of Tehran
Water Resources Management | Year: 2012

This paper presents a new game theoretic methodology for equitable waste load allocation in rivers utilizing fuzzy bi-matrix games, Non-dominated Sorting Genetic Algorithms II (NSGA-II), cooperative game theory, Bayesian Networks (BNs) and Probabilistic Support Vector Machines (PSVMs). In this methodology, at first, a trade-off curve between objectives, which are average treatment level of dischargers and fuzzy risk of low water quality, is obtained using NSGA-II. Then, the best non-dominated solution is selected using a non-zero-sum bi-matrix game with fuzzy goals. In the next step, to have an equitable waste load allocation, some possible coalitions among dischargers are formed and treatment costs are reallocated to discharges and side payments are calculated. To develop probabilistic rules for real-time waste load allocation, the proposed model is applied considering several scenarios of pollution loads and the results are used for training and testing BNs and PSVMs. The applicability and efficiency of the methodology are examined in a real-world case study of the Zarjub River in the northern part of Iran. The results show that the average relative errors of the proposed rules in estimating the treatment levels of dischargers are less than 5 %. © 2012 Springer Science+Business Media Dordrecht.

Shahnazari-Shahrezaei P.,Islamic Azad University at Tehran | Tavakkoli-Moghaddam R.,University of Tehran | Kazemipoor H.,Islamic Azad University at Parand
International Journal of Advanced Manufacturing Technology | Year: 2013

Manpower scheduling is a complicated problem to solve that strives to satisfy employers' objectives and employees' preferences as much as possible by generating fairly desirable schedules. But sometimes, objectives and preferences may not be determined precisely. This problem causes manpower scheduling takes the fuzzy nature. This paper presents a new fuzzy multi-objective mathematical model for a multi-skilled manpower scheduling problem considering imprecise target values of employers' objectives and employees' preferences. Hence, a fuzzy goal programming model is developed for the presented mathematical model and two fuzzy solution approaches are used to convert the fuzzy goal programming model to two single-objective models. Since the complexity of a manpower scheduling problem is NP-hard, the single-objective models are solved by two meta-heuristics, namely particle swarm optimization and elite tabu search. Eventually, the performance of the proposed algorithms is verified and the results are compared with each other to select the best schedules. © 2012 Springer-Verlag London Limited.

Eslami R.,Islamic Azad University at South Tehran | Khoveyni M.,Islamic Azad University at Tehran
Computers and Industrial Engineering | Year: 2013

This study identifies types and values of right and left returns to scales (RTSs) of efficient decision making units (DMUs) in data envelopment analysis (DEA). In this research, we first introduce a new approach to estimate types of right and left returns to scales of efficient DMUs and then, values of right and left returns to scales of these DMUs are measured by presenting two new DEA models. One of the advantages our proposed approach for determining types of right and left RTSs is that our approach is always feasible for all target DMUs while Golany and Yu's RTS approach (Golany & Yu, 1997) is not always feasible, in this case, Golany and Yu have shown that no feasible solution means that there is no data to determine the right or left returns to scale. Other advantage is that our approach is capable of measuring values of right and left returns to scales of efficient DMUs. It is note worthy that, since an inefficient decision making unit (DMU) has more than one projection on the empirical function thus by applying our proposed approach, different types and values of right and left RTSs can be obtained for projections of the inefficient DMU. Lastly, we give an empirical example which motivates our development and contrasts the proposed approach with Golany and Yu's approach then some conclusions are discussed based on the results and also directions for future research are suggested. Note that proofs of some theorems are presented in the Appendix. © 2013 Elsevier Ltd. All rights reserved.

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

Methan has a large potential to adsorb and diffuse among h-BN and graphene surfaces as the suitable dielectric. With this background the nanoscale dielectric capacitors have been widely studied due to their ability to store a high amount of energy. In this research, I have modeled one which is composed of two graphene layers including insulating medium of a h-BN layers which are filed out (Methane)n,m {n=m=7). It has been indicated that the Methane molecule is the suitable gas for hetero-structures of the G/(h-BN)-(Methane)7,7/G capacitor compared to those nonpolar gases of 3 atoms. The quantum and coulomb blocked effects of h-BN/graphene including different numbers of Methane for multi dielectric properties of diûerent thicknesses have been studied. We have shown that Quantum effect has appeared in a small thickness of capacitor due to number of layers and Methane atoms.

Pakzad M.A.,Islamic Azad University at Tehran | Moaveni B.,Iran University of Science and Technology
WSEAS Transactions on Systems and Control | Year: 2013

In this article, an observer with delay-dependent stability conditions has been presented for time delay systems with unknown inputs, where the time delay terms exist in the state and output of the system. The designing of this observer, whose performance index is the H2 norm, has been formulated as a nonlinear optimization problem. By using the finite characterization of a Lyapunov functional equation, sufficient conditions have been proposed to guarantee the existence of a desirable H2 filter. This finite characterization can be calculated by means of a matrix exponential function. Several numerical examples have also been simulated to show the effectiveness and simplicity of the proposed observer.

Pedram P.,Islamic Azad University at Tehran
Journal of Physics A: Mathematical and Theoretical | Year: 2012

We present the exact energy spectrum and eigenfunctions of the one-dimensional hydrogen atom in the presence of the minimal length uncertainty. By requiring the self-adjointness property of the Hamiltonian, we completely determine the quantization condition. We indicate that the single-valuedness criterion of the eigenfunctions in a non-deformed case is an emergent condition and the semiclassical solutions exactly coincide with the quantum mechanical results. The behavior of the wavefunctions at the origin in coordinate space and in quasiposition space is discussed finally. © 2012 IOP Publishing Ltd.

Panahi Y.,Baqiyatallah Medical Sciences University | Badeli R.,Islamic Azad University at Tehran | Karami G.-R.,Baqiyatallah Medical Sciences University | Sahebkar A.,Mashhad University of Medical Sciences | Sahebkar A.,University of Western Australia
Phytotherapy Research | Year: 2015

Current medications have limited efficacy in controlling the symptoms of major depressive disorder (MDD), and are associated with several adverse events on long-term use. Curcuminoids are extremely safe and multifunctional phytopharmaceuticals that have been shown to alleviate depressive symptoms in a variety of experimental models. The present study aimed to investigate the efficacy of curcuminoids as an add-on to standard antidepressants in patients with MDD. One hundred and eleven subjects were assigned to standard antidepressive therapy plus curcuminoids-piperine combination (1000-10 mg/day; n = 61) or standard antidepressive therapy alone (n = 50) for a period of 6 weeks. Efficacy measures were changes in the psychological status on the basis of the Hospital Anxiety and Depression Scale (HADS) and Beck Depression Inventory II (BDI-II). The BDI-II and HADS total and subscale scores were reduced by the end of trial in both study groups. There were significantly greater reductions in total HADS score and subscales of anxiety and depression in the curcuminoids versus control group (p < 0.001). Likewise, reductions in BDI-II total score and scores of somatic and cognitive subscales were found to be greater in the curcuminoids compared with control group (p < 0.001). Co-administration of curcuminoids with piperine may be used as a safe and effective add-on to standard antidepressants in patients with MDD. Copyright © 2014 John Wiley & Sons, Ltd.

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

Nickel tungstate (NiWO4) nanoparticles were synthesized via a sonochemical method based on the reaction between nickel (II) nitrate hexahydrate and sodium tungstate dihydrate in an aqueous solution. To the best of authors’ knowledge, it is the first time that nickel tungstate was synthesized by ultrasonic method. The structural, morphological and optical properties of as-obtained products were characterized by techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive X-ray microanalysis, and ultraviolet–visible (UV–Vis) spectroscopy. The samples indicated a paramagnetic behavior, as evidenced by using vibrating sample magnetometer at room temperature. To evaluate the catalytic properties of nanocrystalline nickel tungstate, the photocatalytic degradation of methyl orange under ultraviolet light irradiation was carried out. © 2016, Springer Science+Business Media New York.

Heidari R.,Islamic Azad University at Tehran
Bulletin of the Seismological Society of America | Year: 2016

A reliable estimation of the earthquake magnitude and epicentral distance within a few seconds after the P-wave arrival is of great importance for earthquake early warning systems. This study aims to investigate the relations between the envelope of the initial part of the P wave with epicentral distance and magnitude of the earthquakes related to the tectonic conditions of Iran. To this end, the accelerometer waveforms of 17 earthquakes with moment magnitudes less than 7.8 and epicentral distances less than 150 km are considered. A simple function with the form of y = Bt. exp (-At) is fitted to the initial part of the waveform envelope on time windows of 2, 3, 4, and 5 s by the least-squares method, which is constructed simply by keeping the past maximum amplitude at every moment. Parameters A and B are obtained to scale magnitude and epicentral distance as well. The results show that - log Δ is proportional to log B, in which Δ denotes the epicentral distance. The distance-scaling relations for all of the time windows indicate standard deviations between ±0.16 and ±0.17 km for log Δ. Comparing to the adopted relation in the early warning system of the Japan Meteorological Agency, results illustrate a relatively distinct slope and intercept, which arises from differences in tectonic structure and features of the earthquake sources in two areas. The same process for records with epicentral distances less than 50 km is also repeated. Results indicate smaller standard deviations between ±0.13 and ±0.14 km for four time windows. Considering the arrangement of hazardous faults in many populated districts of Iran, including Tehran, utilization of the obtained relations is recommended for distances less than 50 km. Moreover, the current study represents two distance-dependent relations between magnitudes with Pmax and A × Pmax within the initial 3 s of P-wave arrivals with standard deviations of ±0.42 and ±0.46 magnitude units, respectively. © 2016, Seismological Society of America. All rights reserved.

Naser-Moghadasi M.,Islamic Azad University at Tehran
Applied Computational Electromagnetics Society Journal | Year: 2016

This paper presents a novel miniaturized parallel coupled-line bandpass filter by etching some slot resonators on the strip for suppressing the first spurious response. These slots perform a serious LC resonance property in certain frequency and suppress the spurious signals. By properly tuning these slot dimensions, multiple closed notches can be generated in the vicinity of spurious harmonic and a wide stopband can be obtained. Slot on the strip that is called Defected Microstrip Structure (DMS). The DMS interconnection disturbs the current distribution only across the strip, thereby giving a modified microstrip line with certain stop band and slow-wave characteristics. The simulation and measurement of a 4.7 GHz prototype bandpass filter are presented. The measured results show a satisfactory rejection level more than 30 dB at first spurious passband without affecting the passband response. Good agreement between the experimental and full-wave simulated results has been achieved. © 2016 ACES.

Ebrahimpour A.,Islamic Azad University at Tehran | Maerefat M.,Tarbiat Modares University
Energy Conversion and Management | Year: 2011

External shading affects the solar energy incident on a window and the transferred energy within the room through the window. In present study, the effect of advanced glazing and overhangs on the solar energy transmitted into or lost from the room through the fenestration areas have been evaluated for typical residential buildings in Tehran, using EnergyPlus× software. It was found that appropriate overhangs or side fins in the south, west and east windows would lead to the optimal reduction of the annual energy transferred into the buildings and can have an energetic behaviour equivalent to high performance glazing. The results have been summarized in a table to simple selecting the best window with different glazings, overhangs and side fins based on energy rating. © 2010 Elsevier Ltd. All rights reserved.

Faghidian S.A.,Islamic Azad University at Tehran
International Journal of Structural Integrity | Year: 2016

Purpose - The linear regression technique is widely used to determine empirical parameters of fatigue life profile while the results may not continuously depend on experimental data. Thus Tikhonov-Morozov method is utilized here to regularize the linear regression results and consequently reduces the influence of measurement noise without notably distorting the fatigue life distribution. The paper aims to discuss these issues. Design/methodology/approach - Tikhonov-Morozov regularization method would be shown to effectively reduce the influences of measurement noise without distorting the fatigue life distribution. Moreover since iterative regularization methods are known to be an attractive alternative to Tikhonov regularization, four gradient iterative methods called as simple iteration, minimum error, steepest descent and conjugate gradient methods are examined with an appropriate initial guess of regularized coefficients. Findings - It has been shown that in case of sparse fatigue life measurements, linear regression results may not have continuous dependence on experimental data and measurement error could lead to misinterpretations of the solution. Therefore from engineering safety point of view, utilizing regularization method could successfully reduce the influence of measurement noise without significantly distorting the fatigue life distribution. Originality/value - An excellent initial guess for mixed iterative-direct algorithm is introduced and it has been shown that the combination of Newton iterative approach and Morozov discrepancy principle is one of the interesting strategies for determination of regularization parameter having an excellent rate of convergence. Moreover since iterative methods are known to be an attractive alternative to Tikhonov regularization, four gradient descend methods are examined here for regularization of the linear regression problem. It has been found that all of gradient decent methods with an appropriate initial guess of regularized coefficients have an excellent convergence to Tikhonov-Morozov regularization results. © Emerald Group Publishing Limited.

Powers D.C.,Harvard University | Lee E.,Harvard University | Ariafard A.,University of Tasmania | Ariafard A.,Islamic Azad University at Tehran | And 4 more authors.
Journal of the American Chemical Society | Year: 2012

Oxidation of binuclear Pd(II) complexes with PhICl 2 or PhI(OAc) 2 has previously been shown to afford binuclear Pd(III) complexes featuring a Pd-Pd bond. In contrast, oxidation of binuclear Pd(II) complexes with electrophilic trifluoromethylating ("CF 3 +") reagents has been reported to afford mononuclear Pd(IV) complexes. Herein, we report experimental and computational studies of the oxidation of a binuclear Pd(II) complex with "CF 3 +" reagents. These studies suggest that a mononuclear Pd(IV) complex is generated by an oxidation-fragmentation sequence proceeding via fragmentation of an initially formed, formally binuclear Pd(III), intermediate. The observation that binuclear Pd(III) and mononuclear Pd(IV) complexes are accessible in the same reactions offers an opportunity for understanding the role of nuclearity in both oxidation and subsequent C-X bond-forming reactions. © 2012 American Chemical Society.

Alagheband M.R.,Islamic Azad University at Tehran | Aref M.R.,Sharif University of Technology
Security and Communication Networks | Year: 2013

Ubiquitousness of Radio Frequency Identification (RFID) systems with inherent weaknesses has been a cause of concern about their privacy and security. Therefore, secure protocols are essentially necessary for the RFID tags to guarantee privacy and authentication among them and the reader. This paper inspects privacy in the RFID systems. First, we survey four new-found RFID authentication protocols, and then, their weaknesses in formal privacy model are analyzed. Although the authors of the schemes claimed that their protocols completely resist privacy attacks, we formally prove that all of them suffer from the family of traceability attacks. Furthermore, not only are the four improved protocols proposed to prevent the aforementioned attacks, but also we provide formal analysis to guarantee the security and privacy of the proposed enhancements © 2012 John Wiley & Sons, Ltd.

Lotfi E.,Islamic Azad University at Tehran | Akbarzadeh-T M.-R.,Ferdowsi University of Mashhad
Cybernetics and Systems | Year: 2013

In this article, the brain emotional learning-based pattern recognizer (BELPR) is proposed to solve multiple input-multiple output classification and chaotic time series prediction problems. BELPR is based on an extended computational model of the human brain limbic system that consists of an emotional stimuli processor. The BELPR is model free and learns the patterns in a supervised manner and evaluates the output(s) using the activation function tansig. In the numerical studies, various comparisons are made between BELPR and a multilayer perceptron (MLP) with a back-propagation learning algorithm. The methods are tested to classify 12 UCI (University of California, Irvine) machine learning data sets and to predict activity indices of the Earth's magnetosphere. The main features of BELPR are higher accuracy, decreased time and spatial complexity, and faster training. © 2013 Copyright Taylor and Francis Group, LLC.

Ahmadi Peyghan A.,Tarbiat Modares University | Hadipour N.L.,Tarbiat Modares University | Bagheri Z.,Islamic Azad University at Tehran
Journal of Physical Chemistry C | Year: 2013

By using density functional theory, we investigated the reactivity and electronic sensitivity of pristine and structurally manipulated BC2N nanotubes (BC2NNT) to a HCN molecule. It was mainly found that (i) the pristine BC2NNT can weakly adsorb the HCN with adsorption energy of -1.1 kcal/mol, and its electronic properties are not sensitive to HCN; (ii) doping the tube by an Al atom can largely improve its reactivity to HCN, but it does not have a significant effect on its sensitivity; (iii) B-B antisite defect on the tube wall can improve both reactivity and sensitivity of the tube to HCN; (iv) N-N antisite could improve neither the reactivity nor the sensitivity. Upon the adsorption of HCN on the B-B antisite defect, the HOMO-LUMO energy gap of the tube is significantly reduced from 2.23 to 1.82 eV and energy of 6.3 kcal/mol is released. © 2013 American Chemical Society.

Amraee T.,K. N. Toosi University of Technology | Ranjbar S.,Islamic Azad University at Tehran
IEEE Transactions on Power Systems | Year: 2013

This paper presents a decision tree based method for out-of-step prediction of synchronous generators. For distinguishing between stable and out-of-step conditions, a series of measurements are taken under various fault scenarios including operational and topological disturbances. The data of input features and output target classes are used as the input-output pairs for decision tree induction and deduction. The merit of decision tree based detection of transient instability lies in robust classification of new unseen samples. The performance of the proposed method is verified on two test cases including a 9-bus dynamic network and the practical 1696-bus Iran national grid. The simulation results are presented for various input features and learning parameters. © 2013 IEEE.

Esmaili M.,Islamic Azad University at Tehran
IET Generation, Transmission and Distribution | Year: 2013

Distributed generations (DGs) are recently in growing attention as a solution to environmental and economical challenges caused by conventional power plants. In this study, a multi-objective framework as a nonlinear programming (NLP) is proposed for optimal placement and sizing of DG units. Objective functions include minimising the number of DGs and power losses as well as maximising voltage stability margin formulated as a function of decision variables. The objective functions are combined into one objective function. To avoid problems with choosing appropriate weighting factors, fuzzification is applied to objective functions to bring them into the same scale. DG units are placed at more efficient buses rather than end buses of radial links as usually determined by previous methods for improving voltage stability. Also, power system constraints including branch and voltage limits are observed in the problem. The proposed method not only is able to model all types of DG technologies but also it employs adaptive reactive limits for DGs rather than fixed limits. In addition, a three-stage procedure is proposed to gradually solve the multi-objective problem in order to prevent infeasible solutions. Also, a new technique is proposed to formulate the number of DGs without converting the NLP problem into mixed-integer NLP. Results of testing the proposed method show its efficiency. © The Institution of Engineering and Technology 2013.

Fazlollahtabar H.,Iran University of Science and Technology | Mahdavi I.,Mazandaran University of Science and Technology | Mohajeri A.,Islamic Azad University at Tehran
Applied Soft Computing Journal | Year: 2013

Supply chain design problems have recently raised a lot of interest since the opportunity of an integrated management of the supply chain can reduce the propagation of undesirable events through the network and can affect decisively the profitability of the members. Often uncertainties may be associated with demand and relevant costs. In most of the existing models uncertainties are treated as randomness and are handled by appealing to probability theory. Here, we propose a fuzzy mathematical programming model for a supply chain which considers multiple depots, multiple vehicles, multiple products, multiple customers, and different time periods. In this work not only demand and cost but also decision variables are considered to be fuzzy. We apply two ranking functions for solving the model. The aim of the fuzzy mathematical program is to select the appropriate depots among candidate depots, the allocation of orders to depots and vehicles, also the allocation of the returning vehicles to depots, to minimize the total costs. To validate the model some numerical experiments are worked out and a comparative analysis is investigated. Also, a regression model is considered to analyze the applied fuzzy ranking methods. © 2012 Elsevier B.V.

Yazdani-Chamzini A.,Islamic Azad University at Tehran | Yakhchali S.H.,University of Tehran
Tunnelling and Underground Space Technology | Year: 2012

The problem of Tunnel Boring Machine (TBM) selection has a significant impact on the speed and cost of excavating sector; so that it is a strategic issue. On the other hand, selecting the optimum TBM among a pool of alternatives is a multicriteria decision making (MCDM) problem. In this paper, an evaluation model based on the fuzzy analytic hierarchy process (AHP) and another fuzzy MCDM technique, namely fuzzy technique for order performance by similarity to ideal solution (TOPSIS) is developed to help the tunneling designers in the process of the TBM selection under fuzzy environment where the vagueness and uncertainty are taken into account with linguistic variables parameterized by triangular fuzzy numbers. The fuzzy AHP is applied to form the structure of the TBM selection problem and to determine weights of the evaluation criteria, and fuzzy TOPSIS method is utilized to acquire final ranking. A real world case study is illustrated in order to demonstrate the potential of the proposed model for the TBM selection issue. It demonstrates the effectiveness and capability of the proposed model. © 2012 Elsevier Ltd.

Mirzaei M.,Islamic Azad University at Tehran | Meskinfam M.,Islamic Azad University at Lahijan
Solid State Sciences | Year: 2011

Density functional theory (DFT) calculations were performed to investigate the effects of tubular lengths on the nuclear magnetic resonance (NMR) properties of boron phosphide (BP) nanotubes. To this aim, the properties of pristine and carbon decorated (C-decorated) models of representative zigzag and armchair BP nanotubes were investigated. The results indicated that the atoms at the edges of nanotubes do not detect any significant changes. The NMR properties of boron atoms only detect slight changes but those of phosphorous atoms are more notable. © 2011 Elsevier Masson SAS. All rights reserved.

Ashkarran A.A.,Islamic Azad University at Tehran
Journal of Cluster Science | Year: 2011

In this review, the importance of electrical arc discharge technique in liquids in synthesis of various nanostructures from carbon based materials to metal and metal oxide nanostructures with their general and specific properties, especially the photocatalytic performance of metal oxide nanostructures is studied. The effect of arc current on size distribution, morphology and physicochemical properties of metal and semiconductor nanostructures was investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray photoelectron spectroscopy (XPS) and UV-Vis spectroscopy. WO3 Cubic nanostructures with 30 nm mean particle size were formed during the discharge process in water. Discharge between zinc electrodes in water leads to formation of rod like and semi spherical ZnO nanostructures with 15-20 nm diameter range. ZrO2 nanoparticles were formed using zirconium electrodes in water. Photodegradation of Rhodamine B (Rh. B) shows that the as prepared nanostructures in this method have potential ability for environmental purifications. Also, using silver electrodes in water leads to formation of silver nanoparticles with 8-15 nm average particle size. Moreover, a novel method for synthesis of gold nanoparticles without using gold electrodes is presented. Finally, the future outlook of this technique in synthesis of various nanocrystalline materials is presented. © 2011 Springer Science+Business Media, LLC.

Reza Dousti M.,University of Technology Malaysia | Reza Dousti M.,Islamic Azad University at Tehran
Journal of Applied Physics | Year: 2013

The effect of silver nanoparticles (NPs) on the optical properties of Nd3+-doped sodium-lead tellurite glass prepared by melting-quenching technique is investigated. The X-ray diffraction patterns confirm the amorphous nature of the samples. The average size of silver NPs increases from 7 to 18nm by addition of AgNO3 content. The surface plasmon resonance band of the silver NPs was recorded at 522nm for 0.5 mol. % AgNO3. Large upconversion enhancements (∼16 and 10 times) are attributed to the enlarged local field in vicinity of silver NPs. Feasible interactions between the excitation light and Nd3+:Ag NP co-doped tellurite glass are discussed. © 2013 AIP Publishing LLC.

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

This article investigate the relationship between sense of community and level of participation in tourism activities in Shiraz, Iran. Pearson correlation has been used to determine the relationship between these variables. The findings through survey questionnaire showed that there are significant relation between sense of community and level of participation for local tourism development. According to the results, sense of community can have a catalytic effect on development of tourism industry through enhancement of local participation.

Abstract This study explains a simple method for characterization of interphase properties in polymer nanocomposites reinforced with spherical nanoparticles. The Leidner-Woodhams model which predicts the tensile strength of interphase (σi) is properly developed, in which the stress concentration parameter is correlated with "B" interfacial parameter in modified Pukanszky model. Also, the thickness of interphase "ri" is expressed as a function of "B" and "σi" and the effects of key parameters on the properties of interphase are well discussed. The suggested equations are applied to some samples from valid literature and the values of "B", "σi" and "ri" are calculated. The developed model suggests logical values for "σi" which shows the applicability of the proposed model for these polymer nanocomposites. A large range for "ri" and "σi" is obtained for the reported samples based on the various properties of matrix, nanofiller and interphase such as "σm", "r" and "B". In addition, the results show that a larger "B" and a smaller "σi" can provide a thicker interphase in the present nanocomposites. © 2015 Published by Elsevier Ltd.

Lotfi N.T.,Islamic Azad University at Tehran
International Journal of Applied Linguistics and English Literature | Year: 2014

Memory transcends the conventional socio- cultural paradigms, reproducing past, dynamically. Omnipresence of memory exposes it to miscellaneous interpretive strategies. Recalling is prone to egocentric fictionalization that defies the time/ space confinements. Accordingly, memory modifies into an influential narrative instrument to picture the unpresentable. As a discursive discourse, it appropriates contextually; it may preserve the dissident marginalized social voices such as migrant communities or it is utilized to protect individuals from psychological breakdowns, in traumatic events. Confessional nature of memory reveals the bitter familial, diasporic secrets, leading to constitution of a collective identity, among migrants. This study seeks to explore the contingent operations of memory in diverse contextual structures; in The Kitchen God’s Wife, by Amy Tan, memory operates as a continual strife to formulate a sense of belonging; whereas, The Child in Time by Ian McEwan is the manifestation of memory’s performance, in an outstanding individual level. © Australian International Academic Centre, Australia.

Mashaei P.R.,Islamic Azad University at Tehran | Shahryari M.,Communication Satellite Research Institute
Acta Astronautica | Year: 2015

Abstract A study on the behavior of nanofluid in a cylindrical heat pipe with two heat sources is performed to analyze the nanofluid application in heat-dissipating satellite equipment cooling. Pure water, Al2O3-water and TiO2-water nanofluids are used as working fluids. An analytical modeling is presented to predict the wall temperature profile for the heat pipe assuming saturated vapor and conduction heat transfer for porous media and wall, respectively. The effects of particle concentration levels (φ=0 (distilled water), 2, 4, and 8%), particle diameters (dp=10, 20, and 40 nm) on the local wall temperature, heat transfer coefficient, thermal resistance, and the size of the heat pipe are investigated. It is observed that the better wall temperature uniformity can be achieved using nanofluid which results in lower temperature difference between evaporators and condenser sections. Results reveal that applying nanoparticle with smaller size and higher concentration level increases heat transfer coefficient remarkably by reducing thermal resistance of saturated porous media. It is also found that the presence of nanoparticles in water can lead to a reduction in weight of heat pipe, and thus satellite, under nearly identical condition. The findings of this paper prove the potential of nanofluid in satellite equipment cooling application. © 2015 IAA.

A simple, rapid and sensitive analytical method for preconcentration and determination of tramadol in different biological samples have been developed using solvent bar microextraction (SBME) combined with gas chromatography-mass spectrometry (GC-MS). The target drugs were extracted from 12ml of aqueous sample with pH 12.0 (source phase; SP) into an organic extracting solvent (n-nonanol) located inside the pores and lumen of a polypropylene hollow fiber (receiving phase; RP). In order to obtain high extraction efficiency, the effect of different variables on the extraction efficiency was studied using an experimental design. The variables of interest were the type of organic phase, pH of the source phases, ionic strength, volume of the source phase, stirring rate, extraction time and temperature. The experimental parameters of SBME were optimized using a Box-Behnken design (BBD) after a Plackett-Burman screening design. The detection limits were 0.02μgL -1 with 4.5% RSD (n=5, c=10μgL -1) for tramadol. Finally, the applicability of the proposed method was evaluated by extraction and determination of the drugs in different biological samples. The results indicated that SBME method has excellent clean-up and high-preconcentration factor and can be served as a simple and sensitive method for monitoring of tramadol in the biological samples. © 2012 Elsevier B.V.

Pedram P.,Islamic Azad University at Tehran | Pedram P.,Institute for Research in Fundamental Sciences
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We exactly solve the Wheeler-DeWitt equation for the closed homogeneous and isotropic quantum cosmology in the presence of a conformally coupled scalar field and in the context of the generalized uncertainty principle. This form of generalized uncertainty principle is motivated by the black hole physics and it predicts a minimal length uncertainty proportional to the Planck length. We construct wave packets in momentum minisuperspace which closely follow classical trajectories and strongly peak on them upon choosing appropriate initial conditions. Moreover, based on the DeWitt criterion, we obtain wave packets that exhibit singularity-free behavior. © 2015 American Physical Society.

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.

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.

The Solver, Microsoft Excel 2000 powerful optimization package, has been used to perform non-linear least-squares curve fitting on the basis of Gauss-Newton method for the calculation of solvatochromic regression coefficients for the complexation of molybdenum(VI) with ethylenediamine-N,N'-diacetic acid and dissociation constants at 25 °C and constant ionic strength 0.1 mol·L-1 sodium perchlorate in different aqueous solutions of methanol. A combination of potentiometric and UV spectrophotometric methods have been used for experimental studies. Non specific and specific solute-solvent interactions were interpreted by correlating the equilibrium data with solvent parameters using the Kamlet-Abboud-Taft solvatochromic equation. Finally the influence of the solvent on the stability of the complex was discussed on the basis of the correlation results and the contribution of α (hydrogen-bond donor acidity), β (hydrogen-bond acceptor basicity) and π* (dipolarity/polarizability) parameters. © 2010 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Beheshtian J.,Shahid Rajaee Teacher Training University | Baei M.T.,Islamic Azad University | Peyghan A.A.,Islamic Azad University at Tehran
Surface Science | Year: 2012

Behavior of CO adsorption on the surface of BN, AlN, BP, and AlP nanotubes was investigated using density functional theory calculations, by means of B3LYP and B97D functionals. It was found that energetic feasibility of this process depends on several factors including LUMO energy level of tubes, electron density, and length of the surrounding bonds of adsorbing atoms plus their hybridization. These factors compete against each other to specify the adsorption behavior of the tubes. Frontier molecular orbital theory (FMO) and structural analyses show that high energy level of LUMO and short bond lengths of the tube surfaces prevent the adsorption of CO on BN nanotubes. The results suggest that the AlN nanotubes are energetically the most favorable cases toward the CO adsorption. It was found that B97D functional changes the absolute energy values of B3LYP results, but it doesn't change their relative-order of magnitudes. © 2012 Elsevier B.V. All rights reserved.

Ahmadi A.,Tarbiat Modares University | Hadipour N.L.,Tarbiat Modares University | Kamfiroozi M.,Islamic Azad University at Shiraz | Bagheri Z.,Islamic Azad University at Tehran
Sensors and Actuators, B: Chemical | Year: 2012

Semiconductive carbon nanotubes (CNTs) have demonstrated great sensitivity toward molecules such as NH 3, NO, and NO 2. Nevertheless, pristine CNTs cannot be used for detection of some highly toxic molecules such as formaldehyde (HCOH). In the present study, we examined the possibility of using aluminum nitride nanotubes (AlNNTs) as a potential gas sensor for HCOH detection by performing density functional theory (DFT) calculation. It was found that HCOH molecule can be chemisorbed on the surface of AlNNTs with Gibbs free energies of -0.59 to -0.64 eV, at standard temperature and pressure (STP, 1 atm and 298 K). In view of the high change of HOMO/LUMO en