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Maleki V.A.,Islamic Azad University at Tabriz | Mohammadi N.,Islamic Azad University at Parand
Smart Materials and Structures | Year: 2017

In the current study, stability analysis of cracked functionally graded material (FGM) columns under the effect of piezoelectric patches is analytically investigated. Configuration of the patches is somehow chosen to create axial load in the column. The crack is modeled by a rotational massless spring which connects the two intact parts of the column at the crack location. After applying the boundary and compatibility conditions at the crack location and the ends of the piezoelectric patches, the governing equation of buckling behavior of the cracked FGM column is derived. The effect of important parameters on the first and second buckling load of the column such as crack parameters (location and depth), location and length of the patches and also applied voltage is studied and discussed. Results show that a crack significantly reduces the column load capacity which is dependent on location and depth of the crack. By applying static load to the column, piezoelectric patches produce local torque, and controlling this torque leads to reduced crack effects on the column. Using piezoelectric patches with proper location and length compensates the effect of the crack. Despite the first buckling load, positive voltage increases the second buckling load of the column. © 2017 IOP Publishing Ltd.

Hassanzadeh P.,Shahid Beheshti University of Medical Sciences | Hassanzadeh P.,Tehran University of Medical Sciences | Hassanzadeh A.,Islamic Azad University at Parand
European Neuropsychopharmacology | Year: 2011

The anxiolytic- and antidepressant-like effects of the neurokinin (NK) receptor antagonists have been shown in behavioral studies. According to the involvement of neurotrophin signaling in the mechanisms of action of psychotropic agents, we aimed to investigate whether the selective NK 1, NK 2, or NK 3 receptor antagonists (GR-205171, SR48968, and SR142801, respectively) affect nerve growth factor (NGF) contents in the brain regions involved in the modulation of emotions. To gain a mechanistical insight into the process by which the NK antagonists regulate brain NGF levels, we evaluated the role of the cannabinoid system which is linked to depression and/or antidepressant effects and appears to interact with neurotrophin signaling. According to the results, single injection of the NK receptor antagonists (3, 5, and 10mg/kg, i.p.) into gerbils did not alter NGF or endocannabinoid (eCB) levels quantified by Bio-Rad protein assay and isotope-dilution liquid chromatography/mass spectrometry, respectively. Three-week administration of 10mg/kg NK antagonists significantly elevated both NGF and eCB levels in brain-region specific fashion. Pre-application of the CB 1 receptor neutral antagonist AM4113 (5.6mg/kg) prevented the elevation of NGF or eCB induced by the NK antagonists. AM4113 showed no effect by itself. We conclude that the cannabinoid system is implicated in the mechanisms of action of NK receptor antagonists including the upregulation of brain NGF levels. © 2011 Elsevier B.V.

Mirhabibi A.,Islamic Azad University at Parand | Soroush A.,Amirkabir University of Technology
Tunnelling and Underground Space Technology | Year: 2013

Buildings are usually modeled as elastic beams in plane strain finite element (FE) simulation of tunnel-building interaction. However, neither tunnel nor surface buildings behave in a plane strain manner. In order to assess the effect of building modeling type on twin tunneling-induced ground settlement, some full three-dimensional FE models were analyzed and the effect of building modeling type was reviewed. Two dimensional (2D) plane strain interaction and green-field situation models were also analyzed to compare the results with the three dimensional (3D) models and assess the influence of modeling type. Outcomes of the studies showed that three-dimensional modeling has great influence on the results and equivalent surface beam, which is used in common practice of two-dimensional plane strain models, over-estimates the stiffness of building and leads to less settlement prediction in comparison with 3D simulation. © 2013 Elsevier Ltd.

Moghaddam B.F.,Islamic Azad University at Parand | Ruiz R.,Polytechnic University of Valencia | Sadjadi S.J.,Iran University of Science and Technology
Computers and Industrial Engineering | Year: 2012

The Vehicle Routing Problem (VRP) has been thoroughly studied in the last decades. However, the main focus has been on the deterministic version where customer demands are fixed and known in advance. Uncertainty in demand has not received enough consideration. When demands are uncertain, several problems arise in the VRP. For example, there might be unmet customers' demands, which eventually lead to profit loss. A reliable plan and set of routes, after solving the VRP, can significantly reduce the unmet demand costs, helping in obtaining customer satisfaction. This paper investigates a variant of an uncertain VRP in which the customers' demands are supposed to be uncertain with unknown distributions. An advanced Particle Swarm Optimization (PSO) algorithm has been proposed to solve such a VRP. A novel decoding scheme has also been developed to increase the PSO efficiency. Comprehensive computational experiments, along with comparisons with other existing algorithms, have been provided to validate the proposed algorithms.

Heidari M.R.,Islamic Azad University at Parand
Aerospace Science and Technology | Year: 2016

In the present study, the impacts of embedding belts are experimentally studied for a supersonic flow field around a long axisymmetric body. Also, the longitudinal and circumferential pressure coefficients along with the boundary layer profile are investigated for g-2 to 6 degrees angles of attack. To this end, two conical-cylindrical belts were installed at the middle and end parts of ogival cylinder model. To ensure the turbulent flow around the model, a trip strip causing artificial disturbances is utilized and the acquired results are compared with the acquired results from the model without a trip strip. To study the effects of the cross section variations on the pressure distribution as well as the boundary layer profiles, three different belts with various leading edge angles were installed at different locations along the cylindrical section of the model. These belts significantly affected both the surface pressure distribution and the boundary layer profile. Passing of flow over the belt leads to sudden variations in pressure coefficient distribution on the belt that is due to sudden cross section variations and consequent development of reverse flow or flow separation regions and production of vortices along the flow path. Also, the presence of belt leads to the development of oblique shock wave on the model, which in turn reduces the Mach number downstream the belt. Studying the circumferential pressure distribution reveals that the presence of belt leads to more asymmetric flow downstream the model, which is intensified as the angle of attack increases. © 2016 Elsevier Masson SAS.

Ghazi S.,Islamic Azad University at Parand | Ip K.,University of Brighton
Renewable Energy | Year: 2014

Increasing installation of photovoltaic (PV) systems and demand for more accurate prediction of their operational performance in the UK has prompted the research that aims to establish the relationships between output efficiencies, weather parameters and deposited solid particles on the panel surface. The direct use of efficiency figures quoted by PV manufacturers, normally based on measurements taken in clean laboratory environments of 25°C and at standard air density, is often not appropriate as field studies demonstrated the actual outputs could be reduced by as much as 60% in dusty or polluted climate without regular cleaning. The experimental investigations and case studies took place in the town of Brighton in the southeast of the UK. Experimental simulations of dry dust cover were carried out in the laboratory to establish the effect of dust density to light transmittance. The effect of dust deposit on panels subjected to the climatic elements was studied using a set of outdoor glass units configured at different tilt angles placed on a roof, which were subsequently analysed in the laboratory after exposures between one and four weeks. Effects of climatic parameters on the performance of PV panels were examined through detailed analysis of the performance of two existing PV installations in relation to their weather exposure. Results for the indoor experiments showed that even a small amount of fine particles could reduce light transmittance by as much as 11%. Distribution analysis of dust collected from the exposed glass units revealed particles sizes were smaller than 400 microns with the highest frequency under 20 microns but the impact on solar transmission through the glass was mere 5% after exposure of four weeks due to the frequent rainy days. Amongst a wide range of climatic parameters used in the statistical analysis, high humidity, rain and snow were found to have significant effects to the efficiencies of the two PV installations, which in some cases could annihilated any system output. This study has also revealed the geographical issue of birds in this coastal city as their droppings can create overheated spots on the PV panel and reduce its output. © 2014 Elsevier Ltd.

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

In this paper, considering the photon self energy in Krein space quantization including quantum metric fluctuation, the running coupling constant of QED is calculated and compared with the conventional result in QED theory. © 2012 Springer Science+Business Media, LLC.

Molaei S.,Islamic Azad University at Parand
Measurement: Journal of the International Measurement Confederation | Year: 2016

Mechanical properties of thin films, which can be used to improve the quality of products, have an important role in industry. In this study a new optical measurement technique based on secondary laser speckle patterns to extract Young's modulus by changing resonance frequency of specimen was developed. The samples investigated in this non-destructive and non-contact method were low density polyethylene (LDPE) and paperboard (PPR). This simple and highly accurate scheme has all the advantages of previous measurement techniques without any complex set-up and additional processing. © 2016 Elsevier Ltd. All rights reserved.

Parvinzadeh Gashti M.,Islamic Azad University at Tehran | Elahi A.,Islamic Azad University at South Tehran | Parvinzadeh Gashti M.,Islamic Azad University at Parand
Composites Part B: Engineering | Year: 2013

The aim of this research was to embed silica-kaolinite on a cotton surface using succinic acid (SA) as a cross-linking agent and sodium hypophosphite (SHP) as a catalyst. The influence of inorganic particles on the performance of the cellulose fiber was investigated using Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermo-gravimetric analyzer (TGA), scanning electron microscope (SEM), electron dispersive X-ray spectrometer (EDX), water contact angle (WCA) and reflectance spectroscopy (RS). ATR showed the possible interactions between silica, kaolinite, the cross-linking agent and cellulose functional groups on the surface. The results obtained from the thermal measurements demonstrated that the stabilized silica-kaolinite particles can significantly improve the thermal stability of the cotton fiber. This research suggests a successful method for stabilization and compatibility of various inorganic particles on cotton. © 2013 Elsevier Ltd. All rights reserved.

Azami S.,Islamic Azad University at Parand
Match | Year: 2015

Let G be a graph with n vertices and μ1 , . . . , μn and q1 , . . . , qn denote the Laplacian eigenvalues and signless Laplacian eigenvalues of G, respectively. The Laplacian Estrada index and signless Laplacian Estrada index of G is defined as LEE(G) = eμ1 + ⋯ + eμn and SLEE(G) = eq1 + ⋯ + eqn . We prove that for any graph G, SLEE(G) ≥ LEE(G), with equality if and only if G is bipartite. Also, we show that if G has m edges and t triangles, then SLEE(G) > n+3m+t+(Formula presented). and SLEE(G) ≥(Formula presented).

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