Zavvari M.,Islamic Azad University at Urmia |
Abedi K.,Shahid Beheshti University |
Yusefli A.,Islamic Azad University at Hidaj |
Karimi M.,Islamic Azad University at Mahābād
Optik | Year: 2015
In this paper, a novel design of quantum ring infrared photodetector (QRIP) is proposed based on an additional avalanche multiplication region and its performance theoretically is investigated. The device consists of two intrinsic regions including: (i) quantum ring based absorption region which is responsible for absorption longer wavelength radiations and (ii) avalanche multiplication region for multiplying the generated carriers in absorption layer. Since lower electric fields are needed for absorption region to keep the dark current low and higher fields are required for multiplication region, a highly doped charge layer is used to separate absorption and multiplication regions and non-uniformly distribute the electric field. Also to further reduction of dark current, resonant tunneling barriers are embedded in absorption region to provide only a pass for optically excited electrons. Simulation results shows a higher responsivity and specific detectivity about 40 A/W and 2 × 1010 cm Hz1/2/W at λ = 20 μm, respectively. © 2015 Elsevier GmbH. All rights reserved.
Ahangari A.,Islamic Azad University at Hidaj |
Mojtaba S.,Islamic Azad University at Zanjan |
Saghatchi F.,Zanjan University of Medical Sciences
IET Nanobiotechnology | Year: 2016
There is no optimal imaging method for the detection of unknown infectious foci in some diseases. This study introduces a novel method in X-ray imaging of infection foci due to Staphylococcus aureus by developing a contrast agent based on gold nanoparticles (GNPs). GNPs in spherical shape were synthesised by the reduction of tetrachloroauric acid with sodium citrate. Then gentamicin was bound directly to citrate functionalised GNPs and the complex was stabilised by polyethylene glycol. The interaction of gentamicin with GNPs was confirmed by ultraviolet-visible and Fourier transform infrared spectroscopies. The stability of complex was studied in human blood up to 6 h. The stability of conjugate was found to be high in human blood with no aggregation. The biodistribution study showed localisation of gentamicin-GNPs conjugate at the site of Staphylococcal infection. The infection site was properly visualised in X-ray images in mouse model using the gentamicin-GNPs conjugate as a contrast agent. The results demonstrated that one may consider the potential of new nanodrug as a contrast agent for X-ray imaging of infection foci in human beings which needs more investigations. © The Institution of Engineering and Technology 2016.
Zareiegovar G.,Islamic Azad University at Tabriz |
Sakhavati A.,Islamic Azad University at Tabriz |
Nabaei V.,Islamic Azad University at Hidaj |
Gharehpetian G.B.,Amirkabir University of Technology
2010 9th Conference on Environment and Electrical Engineering, EEEIC 2010 | Year: 2010
In this paper, parameters of PID controller and bias coefficient for Load Frequency Control (LFC) are designed using a new approach. In the proposed method, the power system uncertainties and nonlinear limitations of governors and turbines, i.e. Valve Speed Limit (VSL) and Generation Rate Constraint (GRC), are taken into account in designing. Variations of uncertain parameters are considered between -40% and +40% of nominal values with 5% step. In order to design the proposed PID controller, a new objective function is defined. To optimize the new objective function, PSO algorithm is applied. In the two-area power system, simulation results of test system using the proposed PID and classic PID controller are compared.
Ahmadi I.,Amirkabir University of Technology |
Ahmadi I.,Islamic Azad University at Hidaj |
Sheikhy N.,Islamic Azad University at Hidaj |
Aghdam M.M.,Amirkabir University of Technology |
Nourazar S.S.,Amirkabir University of Technology
Engineering Analysis with Boundary Elements | Year: 2010
In this paper a truly meshless method based on the integral form of energy equation is presented to study the steady-state heat conduction in the anisotropic and heterogeneous materials. The presented meshless method is based on the satisfaction of the integral form of energy balance equation for each sub-particle (sub-domain) inside the material. Moving least square (MLS) approximation is used for approximation of the field variable over the randomly located nodes inside the domain. In the absence of heat generation, the domain integration is eliminated from the formulation of presented method and the computational efforts are reduced substantially with respect to the conventional MLPG method. A direct method is presented for treatment of material discontinuity at the heterogeneous material in the presented meshless method. As a practical problem the heat conduction in fibrous composite material is studied and the steady-state heat conduction in unidirectional fibermatrix composites is investigated. The solution domain includes a small area of the composite system called representative volume element (RVE). Comparison of numerical results shows that the presented meshless method is simple, effective, accurate and less costly method for micromechanical analysis of heat conduction in heterogeneous materials. © 2010 Elsevier Ltd. All rights reserved.
Mohammadpour H.,Islamic Azad University |
Moghimipour E.,Ahvaz Jundishapur University of Medical Sciences |
Rasooli I.,Shahed University |
Fakoor M.H.,Islamic Azad University |
And 4 more authors.
Jundishapur Journal of Natural Pharmaceutical Products | Year: 2012
Background: Aflatoxin B1 (AFB1) is a highly toxic and hepatocarcinogenic metabolite produced by Aspergillus species. Some natural products are known to kill fungi and destroy toxins and toxin-producing agents. Objectives: The purpose of this study is to provide experimental data on the antifungal activity of cumin oils and their components that could be considered suitable for application in foods and drugs. Materials and Methods: The essential oil (EO) of Cuminum cyminum L. collected from Alborz Mountain, Iran, was obtained by hydro-distillation. The oil was analyzed by gas chromatography (GC) and chromatography/mass spectrophotometry (GC/MS). The antifungal activity of the oil was studied with regard to the inhibition of the growth of Aspergillus flavus PICC-AF39, Aspergillus flavus PICC-AF24, Aspergillus parasiticus NRRL-2999 and Aspergillus niger. The minimal inhibitory (MIC) and minimal fungicidal (MFC) concentrations of the oil were determined. Results: α-Pinene (29.2%), limonene (21.7%), 1,8-cineole (18.1%), linalool (10.5%), linalyl acetate (4.8%), and α-terpineole (3.17%) were the major components of the essential oil from C. cyminum L., and the oil showed a strong inhibitory effect on fungal growth. Conclusions: Essential oils could be safely used as preservatives in pharmaceuticals as well as health and food products to protect them against toxigenic fungal infections. © 2012 Kowsar Corp.
Ghorbani A.,Islamic Azad University at Abhar |
Masoudi S.,Islamic Azad University at Abhar |
Shabani A.,Islamic Azad University at Hidaj
Turkish Journal of Electrical Engineering and Computer Sciences | Year: 2012
In this paper, the Posicast control method is used for decreasing the reactive power oscillations of static shunt compensators. Shunt compensators such as the static synchronous compensator (STATCOM) and static VAR compensator (SVC) are considered to be FACTS devices. The applied control method decreases the amount of oscillations in the outputs of STATCOM and SVC considerably, with fast damping. In this paper, a PI controller is added to the model to decrease the sensitivity of the Posicast controller to the parameter variations and plant model mismatch. Simplicity and applicability are the main features of this controller. The model is simulated in a MATLAB/Simulink environment. © TÜBITAK.
Safaeian M.,Islamic Azad University at Hidaj |
Abapoor M.,Islamic Azad University at Abhar
International Review on Modelling and Simulations | Year: 2010
This paper presents an application of fuzzy control to determine the control signal of static var compensator (SVC) for reactive power compensation and power factor correction. Input signals for the FLC are chosen as load reactive power and initial firing angle of thyristors. The control signal is calculated using fuzzy membership functions. The effectiveness and feasibility of the TSK (Takagi-Sugeno-Kang) and mamdani type fuzzy controllers for thyristors firing control in SVC is compared. Effectiveness of the proposed technique is demonstrated by simulation studies on a single machine infinite bus system. Results obtained show improvement in the overall system characteristics using the proposed adaptive fuzzy logic SVC controller. © 2010 Praise Worthy Prize S.r.l.-All rights reserved.
Shabani A.,Islamic Azad University at Hidaj
International Review on Modelling and Simulations | Year: 2011
The problem of power system expansion planning has large dimensions in generation and transmission sections. One of the required tools which have an important role in this problem analysis is power flow. Optimal DC power flow is faster than AC power flow and it is preferred for large problems. In this paper, an approach of fast optimal power flow based on DC power flow is presented and is formulated simply to be user friendly. The linear programming is used as an optimization tool to solve this problem. Finally, performance of the proposed approach is studied on a case. The results verify that this approach can be used as a tool in planning problems easily. © 2011 Praise Worthy Prize S.r.l. - All rights reserved.
Manzin A.,INRIM - Istituto Nazionale di Ricerca Metrologica |
Nabaei V.,INRIM - Istituto Nazionale di Ricerca Metrologica |
Nabaei V.,Polytechnic University of Turin |
Nabaei V.,Islamic Azad University at Hidaj
Journal of Applied Physics | Year: 2014
This paper presents a numerical model for the study of micro-Hall magnetometry applications, aiming at evaluating the sensitivity of semiconductor miniaturized devices to the stray field of permalloy nanostructures with ring and disk geometry. The procedure couples a micromagnetic code, for the calculation of the stray field generated by the nanomagnet, to a 2D classical transport model for the determination of the electric potential distribution inside the Hall plate. The model is applied to study the sensitivity of a micro-Hall device in the detection of magnetization switching processes characterized by vortex state, focusing on the influence of magnetic nanostructure position. © 2014 AIP Publishing LLC.
Sheikhy N.,Islamic Azad University at Hidaj |
Ahmadi I.,Islamic Azad University at Hidaj
ICCET 2010 - 2010 International Conference on Computer Engineering and Technology, Proceedings | Year: 2010
In this study a new meshless method is presented for the analysis of heat transfer in heterogeneous solid structures. The presented meshless method is based on the integral form of energy equation for the sub-particles in the domain of the material. A micromechanical model based on the presented meshless method is presented for analysis of heat transfer, temperature distribution and steady-state effective thermal conductivities of fiber-matrix type of composite materials. Because the domain integration is eliminated in the presented meshless formulation, the computational efforts in presented method are decreased substantially. A small area of the composite system called the representative volume element (RVE) is considered as the solution domain. The fully bonded fiber-matrix interface is considered and contact thermal resistant is neglected in the fiber-matrix interface and so the continuity of temperature and reciprocity of heat flux is satisfied in the fiber-matrix interface. A direct interpolation method is employed for enforcement the appropriate boundary conditions to the RVE. Numerical results are presented for temperature distribution, heat flux and thermal conductivity. Numerical results show that presented meshless method is simple, effective, accurate and less costly method in micromechanical modeling of heat conduction in heterogeneous materials. © 2010 IEEE.