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Kouhi M.,Islamic Azad University at Tabriz
Journal of Nanophotonics | Year: 2017

The effect of aluminum mole fraction and incident light intensity on linear, nonlinear, and total optical absorption coefficients in GaN/AlxGa1-xN core-defected shell nanowire is theoretically investigated. The presented nanostructure is a cylindrical quantum wire including a defected shell around the cylinder core. Based on the density matrix approach and the effective mass approximation, the intersubband optical absorption coefficients are numerically calculated. The results show that the magnitude and peaks positions of optical absorption coefficients can be adjustable by varying aluminum mole fraction. The resonance peak positions of optical absorption coefficients are blueshifted by increasing of the shell region potential due to increasing of the energy difference between two energy levels. © 2017 Society of Photo-Optical Instrumentation Engineers (SPIE).

Sheikholeslami F.,Islamic Azad University at Tabriz | Navimipour N.J.,Islamic Azad University at Tabriz
Swarm and Evolutionary Computation | Year: 2017

Cloud computing is an emerging Internet-based computing paradigm, with its built-in elasticity and scalability. In cloud computing field, a service provider offers a large number of resources like computing units, storage space, and software for customers with a relatively low cost. As the number of customer increases, fulfilling their requirements may become an important yet intractable matter. Therefore, service allocation is one of the most challenging issues in the cloud environments. The problem of service allocation in the cloud computing is thought to be a combinatorial optimization problem to a large company for numbers of their customers and owned resources could be huge enough. This paper considers three conflicting objectives, namely maximizing revenue for users and providers as well as finding the optimal solution at desired time. We use a Multi-Objective Particle Swarm Optimization based on Crowding Distance (MOPSO-CD) to solve the problem because MOPSO-CD is highly competitive in converging towards the Pareto front and generates a well-distributed set of non-dominated solutions. In addition, fuzzy set theory is employed to specify the best compromise solution. We simulate the proposed method using Matlab and compare the performance of the method against the performance of two other multi-objective algorithms, in order to prove that the proposed method is highly competitive with respect to them. Finally, the experiments results show that the method improves the speed of the execution of the resources allocation algorithm while generating high revenue for both the users and the providers and increasing the resource utilization. © 2017 Elsevier B.V.

Pashazadeh H.,Islamic Azad University at Tabriz | Teimournezhad J.,University of Tehran
Materials and Design | Year: 2014

The objective of this study was to develop a numerical model for the prediction of temperature distributions, effective plastic strain distributions, and especially material flow in Friction Stir Welding of copper plates. DEFORM-3D was used by incorporating the Arbitrary Lagrangian Eulerian (ALE) formulation. Three-dimensional results of the material flow pattern extracted using the point tracking are in good agreement with the experiment. It was shown that the main part of material flow occurs near the top surface. Material near the top surface at the behind of tool stretches from retreating side towards advancing side, leads to non-symmetrical shape of the stir zone. The stir zone shape in FSW of copper alloys, predicted by simulation, does not lean completely towards any sides of welding line. © 2013 Elsevier Ltd.

Mehmannavaz M.R.,Islamic Azad University at Mashhad | Sattari H.,Islamic Azad University at Tabriz
Laser Physics Letters | Year: 2015

We propose a model for a quintuple coupled quantum dot system based on a GaAs/AlGaAs heterostructure. Then, we analyze the optical bistability (OB) and optical multistability (OM) behaviours and transition between the regimes at a wavelength of λ = 1.550 μm. We take the benefit of consecutive and parallel interdot tunnelling and an incoherent pumping field for electrical and even optical control of the processes. It is shown that OB, OM and transition between them can be accomplished and controlled by adjusting the rate of the inter-dot tunnellings (electrical bias), probe wavelength detuning and rate of the optical incoherent pumping field. By proper choice of the controlling parameters, the bistable hysteresis loop becomes narrower, which makes it easier for the cavity field to reach saturation. We interpret the OB and OM behaviours by discussing the absorption of the active medium. We also investigate switching time between the two stable states when the output field jumps from a lower branch to an upper branch. Such a controllable OB/OM and transition between them in multiple QD molecules at a wavelength of 1.550 μm, may provide some new possibilities for technological applications in optoelectronics, solid-state quantum information science and systems dealing with signal processing. © 2015 Astro Ltd.

Souri A.,Islamic Azad University at Tabriz | Jafari Navimipour N.,Islamic Azad University at Tabriz
Expert Systems with Applications | Year: 2014

Grid computing is the federation of resources from multiple locations to facilitate resource sharing and problem solving over the Internet. The challenge of finding services or resources in Grid environments has recently been the subject of many papers and researches. These researches and papers evaluate their approaches only by simulation and experiments. Therefore, it is possible that some part of the state space of the problem is not analyzed and checked well. To overcome this defect, model checking as an automatic technique for the verification of the systems is a suitable solution. In this paper, an adopted type of resource discovery approach to address multi-attribute and range queries has been presented. Unlike the papers in this scope, this paper decouple resource discovery behavior model to data gathering, discovery and control behavior. Also it facilitates the mapping process between three behaviors by means of the formal verification approach based on Binary Decision Diagram (BDD). The formal approach extracts the expected properties of resource discovery approach from control behavior in the form of CTL and LTL temporal logic formulas, and verifies the properties in data gathering and discovery behaviors comprehensively. Moreover, analyzing and evaluating the logical problems such as soundness, completeness, and consistency of the considered resource discovery approach is provided. To implement the behavior models of resource discovery approach the ArgoUML tool and the NuSMV model checker are employed. The results show that the adopted resource discovery approach can discovers multi-attribute and range queries very fast and detects logical problems such as soundness, completeness, and consistency. © 2013 Elsevier Ltd. All rights reserved.

Vahid B.,Islamic Azad University at Tabriz | Khataee A.,University of Tabriz
Electrochimica Acta | Year: 2013

In this research work, a photoassisted electrochemical system under recirculation mode and with UV irradiation was designed for treatment of C.I. Acid Blue 92 (AB92) as a model anionic azo dye in aqueous solution. Degradation experiments were carried out with boron-doped diamond (BDD) anode and carbon nanotubes-polytetrafluoroethylene (CNTs-PTFE) cathode in the presence of sulfate as an electrolyte. A comparative study of AB92 degradation by photolysis, electrochemical oxidation and photoassisted electrochemical processes after 45 min of treatment demonstrated that degradation efficiency was 27.89, 37.65 and 95.86%, respectively. Experimental data revealed that the degradation rate of AB92 in all of the processes obeyed pseudo-first-order kinetics and application of photoassisted electrochemical system reduced electrical energy per order (EEO), considerably. Degradation efficiency of photoassisted electrochemical process enhanced by increasing applied current and flow rate values, but vice versa trend was observed for initial dye concentration and an optimum amount of 6 was obtained for initial pH. The TOC measurement results demonstrated that 93.24% of organic substrates were mineralized after 120 min of photoassisted electrochemical process and GC-Mass analysis was performed for identification of degradation intermediates. © 2012 Elsevier Ltd. All rights reserved.

This work, describes synthesis and in vitro evaluation of new acrylic-type polymeric prodrugs containing mesalazine, as colon targeted drug delivery systems. First, mesalazine reacted with formic acid, and the obtained material was reacted with 2-hydroxypropyl methacrylat in the presence of 1,1-carbonyldiimidazole to produce methacryloyloxypropyl 5-amino salicylate. The resulted acrylic-derivative of mesalazine was then polymerized with various acrylic monomers by free radical solution polymerization, utlizing azobisisobutyronitrile as an initiator at 70±2°C. The obtained polymer-drug conjugates were characterized by FT-IR, 1 H-NMR, elemental analysis, gel permeation chromatography, and differential scanning calorimetery techniques. The release studies were performed into dialysis bags by hydrolysis buffered solutions at 37°C. Detection of hydrolysis by UV spectrophotometer at free drug λmax (300 nm for pH 1; 339 nm for pH 7 and 8) in selected intervals showed that the mesalazine can be released by selective hydrolysis of the ester bond at the side of drug moiety. The release profiles indicated that the hydrophobicity of polymers and the pH value of the hydrolysis media have strongly effects on the hydrolytic behavior of the polymeric prodrugs.

Navimipour N.J.,Islamic Azad University at Tabriz
Expert Systems with Applications | Year: 2015

Expert Cloud as a new class of Cloud computing systems enables its users to request the skill, knowledge and expertise of people without any information of their location by employing Internet infrastructures and Cloud computing concepts. One of the most important service in Expert Cloud is to search trustworthy peoples in order to benefit from their knowledge and skills. In this paper we propose a new and applicable method for Trustworthy Human Resource Discovery (THRD) in Expert Cloud by introducing a resource discovery and trust evaluating method, implement the proposed method by using ASP.Net and SQL in Expert Cloud; verify the structures and compositions of THRD by describing the behavioral models and state diagrams; define a Kripke structure with marked states to provide the formal relationship between the expanded model and the original state diagram structures; define the expected properties of the structures and compositions of THRD by means of temporal logic languages; and implement the proposed model by NuSMV model checker. The results show that the proposed method can discover trustworthy people efficiently and is sound, complete, reachable, fair, deadlock-free and consistent. © 2015 Elsevier Ltd.

Hanifian S.,Islamic Azad University at Tabriz
Letters in Applied Microbiology | Year: 2014

Mycobacterium avium subsp. paratuberculosis (Map) is considered as a potential public health threat due to its possible association with Crohn's disease in humans. This study aimed to investigate the survival of Map in ultra-filtered white (UFW) cheese, with special reference to the effect of initial inoculum level, addition of starter culture and salt concentration. Behaviour of Map was monitored during the storage of UFW cheese using F57-quantitative real-time PCR and culture assay. According to the results, higher inoculum level prolongs Map persistence in UFW cheese. Furthermore, the addition of starter culture was found as the main restrictive parameter affecting the survival of Map in UFW cheese. Meanwhile, salt concentration did not accelerate Map inactivation. It was concluded that UFW cheese has potential to support the survival of Map. © 2014 The Society for Applied Microbiology.

Razagifard P.,Islamic Azad University at Tabriz
Journal of Computer Assisted Learning | Year: 2013

This paper reports on a study investigating the potential effect of synchronous and asynchronous text-based computer-mediated communication (CMC) on oral fluency development of second-language (L2) learners. Sixty-three intermediate learners of English were randomly assigned to one of three groups (two experimental groups and one control group), each consisting of 21 participants. The participants in the experimental groups completed four communicative tasks under two different instructional environments: synchronous text-based CMC environment and asynchronous text-based CMC environment. The average length of pauses, the articulation rate, the fluent-run, the phonation-time ratio and the speaking rate served as dependent variables. The study found that the participants in synchronous CMC group improved their L2 oral fluency significantly compared with their peers in the other two groups. The results also revealed the students in asynchronous CMC group obtained higher mean scores than those in the control group, although the differences between groups were not statistically significant. © 2012 Blackwell Publishing Ltd.

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