University of Applied Science and Technology of Iran

www.uast.ac.ir/
Tehran, Iran

University of Applied Science and Technology is a university administrated by Ministry of Science, Research and Technology with various branches all over the Provinces of Iran.This university helps to increase skill level of employed personnel in various sectors of economic field and graduates of higher education and professional skills that are lacking in administrative. Wikipedia.


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Mohsen O.,Tehran University of Medical Sciences | Fereshteh N.,University of Applied Science and Technology of Iran
Safety Science | Year: 2017

Process equipment failures (PEFs) are recognized as one of the leading causes of process accidents. Failure modes and effect analysis (FMEA) as a risk assessment technique, has widely been used in a variety of process industries. The conventional form of FMEA uses three parameters of severity (S), occurrence (O), and detection (D) as risk factors to calculate a risk priority number (R.P.N) and rank the failure modes based on this number. But several shortcomings associated with the FMEA have limited its applicability. This study aims at the development of an extension of FMEA that could efficiently handle the vagueness and uncertainty exists in the experts’ judgments in process of failure modes ranking in conventional FMEA. In this paper we used the concept of the Z number to capture the inherent uncertainty exists in the experts’ judgments. In addition, we used Shannon entropy concept to deploy objective weights to adjust subjective weights assigned by experts. Furthermore, the fuzzy VIKOR technique applied to rank and prioritize the failure modes based on the minimum individual regret and the maxi group utility. A numerical example is presented to illustrate an application of the proposed method in a geothermal power plant (GPP). Results are also compared with the conventional FMEA. A sensitivity analysis was conducted to validate the obtained results. Findings indicate that the application of the proposed approach (subjective-objective ranking) in fuzzy environment can improve the applicability of the conventional FMEA method. © 2016 Elsevier Ltd


Mohammadzadeh I.,University of Applied Science and Technology of Iran | Sheibani H.,Shahid Bahonar University of Kerman
Chinese Chemical Letters | Year: 2012

In this investigation a new strategy involves the one-pot, three-component reaction of malononitrile, salycilaldehyde and phenol derivatives in the presence of high surface area of MgO is extended to the formation of chromeno[3,4-c]chromene derivatives in good to excellent yields in a short reaction time. Also, the three component reactions of an aldehyde such as salycilaldehyde and ketones with malononitril for the formation of chromeno[3,4-c]pyridines are investigated. © 2012 Iman Mohammadzadeh. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.


Akhgar M.R.,Islamic Azad University at Kermān | Salari M.,Islamic Azad University at Kermān | Zamani H.,University of Applied Science and Technology of Iran
Journal of Solid State Electrochemistry | Year: 2011

The redox response of a modified carbon nanotube paste electrode of ferrocenedicarboxylic acid was investigated. Cyclic voltammetry, differential pulse voltammetry, and chronoamperometry were used to investigate the electrochemical behavior of levodopa (LD) at modified electrode. Under the optimized conditions (pH 5.0), the modified electrode showed high electrocatalytic activity toward LD oxidation; the overpotential for the oxidation of LD was decreased by more than 190 mV, and the corresponding peak current increased significantly. Differential pulse voltammetric peak currents of LD increased linearly with its concentrations at the range of 0.04 to 1,100 μM, and the detection limit (3σ) was determined to be 12 nM. The diffusion coefficient ({D = 9.2 × 10 -6cm 2 and transfer coefficient (α=0.49) of LD were also determined. Mixture of LD, NADH, and tryptophan (TRP) can be separated from one another by differential pulse voltammetry. These conditions are sufficient to allow determination of LD, NADH, and TRP both individually and simultaneously. The modified electrode showed good reproducibility, remarkable long-term stability, and especially good surface renewability by simple mechanical polishing. The results showed that this electrode could be used as an electrochemical sensor for determination of LD, NADH, and TRP in real samples such as urine and water samples. © 2010 Springer-Verlag.


Tashkhourian J.,Shiraz University | Hormozi-Nezhad M.R.,Sharif University of Technology | Khodaveisi J.,University of Applied Science and Technology of Iran | Dashti R.,Persian Gulf University
Sensors and Actuators, B: Chemical | Year: 2011

A novel glucose biosensor based on chromophore (silver nanoparticles) decolorizing for the photometric determination of glucose was developed. Silver nanoparticles are directly synthesized in the sol-gel matrix by a one-step method based on the reduction of the inorganic precursor AgNO3 and were used for the preparation, characterization and calibration of a highly sensitive and cost-effective localized surface plasmon resonance-based glucose biosensor. In the presence of glucose oxidase (GOx) and due to the enzyme-substrate (glucose) reaction, H2O2 was produced and silver nanoparticles in the sol-gel glass have the ability for the decomposition of hydrogen peroxide. Due to the degradation of silver nanoparticles a remarkable change in the localized surface plasmon resonance absorbance strength could be observed which have been monitored as a suitable signal for determination of substrate concentration. Beer's law is obeyed in the range from 50 to 800 mg/L glucose and the limit of detection is 23 mg/L. The proposed optical biosensor has been successfully applied to the determination of glucose in various real samples. © 2011 Elsevier B.V. Al rights reserved.


Motie I.,Islamic Azad University at Mashhad | Bokaeeyan M.,University of Applied Science and Technology of Iran
Physics of Plasmas | Year: 2015

A close analysis of dust charging process in the presence of radio frequency (RF) discharge on low pressure and fully ionized plasma for both weak and strong discharge's electric field is considered. When the electromagnetic waves pass throughout fully ionized plasma, the collision frequency of the plasma is derived. Moreover, the disturbed distribution function of plasma particles in the presence of the RF discharge is obtained. In this article, by using the Krook model, we separate the distribution function in two parts, the Maxwellian part and the perturbed part. The perturbed part of distribution can make an extra current, so-called the accretion rate of electron (or ion) current, towards a dust particle as a function of the average electron-ion collision frequency. It is proven that when the potential of dust grains increases, the accretion rate of electron current experiences an exponential reduction. Furthermore, the accretion rate of electron current for a strong electric field is relatively smaller than that for a weak electric field. The reasons are elaborated. © 2015 AIP Publishing LLC.


Mousavi-Sabet H.,Guilan University | Anvarifar H.,University of Applied Science and Technology of Iran
Folia Zoologica | Year: 2013

A 13-landmark morphometric system was used for 617 specimens to investigate the hypothesis of species differentiation among Cobitis keyvani, Cobitis faridpaki and an unknown Cobitis sp. population from the River Babolrud in the southern Caspian Sea basin. Univariate analysis of variance showed significant differences among the means of the three groups for 41 out of 78 standardized morphometric measurements. In discriminant function analysis, the overall assignment of individuals into their original groups was 58.0 %. The proportions of individuals correctly classified into their original groups were 58.1 %, 64.7 % and 44.1 % for Cobitis sp., C. faridpaki and C. keyvani, respectively. Principal component analysis (PCA) and canonical variates analysis (CVA) confirmed the significant difference among these populations (λ de Wilks = 0.42, P = 0). The CVA scatter plot showed 617 specimens grouped into three distinct areas with some overlap. Clustering based on Euclidean distances among the groups of centroids using an UPGMA indicated segregation of the three populations into two distinct clusters: Cobitis sp. and C. faridpaki in one group and C. keyani in other group. Also the unknown population of spined loach from the River Babolrud was recognized as C. faridpaki and the river as a new habitat for the species.


Choobi M.S.,University of Applied Science and Technology of Iran
Journal of Strain Analysis for Engineering Design | Year: 2013

Welding-induced distortions are one of the major problems frequently encountered in industry. Different geometrical and welding process parameters are believed to influence distortions. One of the most common types of distortions frequently observed in butt-welded plates is angular distortion. In this study, the effect of geometrical parameters on angular distortions in butt-welded plates has been investigated numerically and experimentally. A comprehensive study has been performed, and several cases with different plate lengths, widths and thicknesses have been studied. Distortions have been predicted by three-dimensional thermo-elastic-plastic finite element simulation. The finite element results have been verified by a series of experimental measurements for temperatures and angular distortions. The results of this study revealed that plate thickness, length and width influence the magnitude and mode of distortions greatly. The results revealed that decreasing the plate thickness or increasing the weld length results in higher and nonlinear angular distortions. Increasing the plate width has an adverse effect and reduces the angular distortion. In addition, the thickness of the plate has a key role on distortion behavior and can lead to buckling in thin plates. © IMechE 2013.


Torabizadeh M.A.,University of Applied Science and Technology of Iran
Indian Journal of Engineering and Materials Sciences | Year: 2013

Composite materials are subjected to low temperatures in service and this has induced the need for a proper knowledge of low temperature behavior of composites. Most of the research in this field is focused on applying different types of loading and laminated configurations. This paper discusses the experimental study on the tensile, compressive and in-plane shear behavior of unidirectional (UD) glass fiber reinforced polymeric composite under static and low temperature loading conditions. Since UD composite is the basic building block of a composite structure and can be used to make general laminates. In order to fully characterize UD laminate, several experimental tests are performed using an environmental test chamber and a universal testing machine. Thermo-mechanical loads are applied to glass/epoxy unidirectional laminates at room temperature (25°C), -20°C and -60°C. The results of the present study indicate that low temperatures have a significant effect on composite failure mode. It is also found that the strength and modulus of UD composites both increased with decreasing the temperature in all cases including tensile, compressive and shear loads. On the other hand, the results show that strain to failure decreased by decreasing the temperature.


Farsadi M.,University of Applied Science and Technology of Iran | Ochsner A.,University of Technology Malaysia | Rahmandoust M.,University of Technology Malaysia
Journal of Composite Materials | Year: 2013

This paper studies the extent to which the effective stiffness of composite materials can be impacted by the characteristic waviness of nanotubes embedded in polymers. A three-dimensional finite element model is used to investigate the effect of volume fraction and waviness on mechanical properties, i.e. Young's modulus and Poisson's ratio, of composites reinforced with waved carbon nanotubes. According to the obtained results, the nanotube waviness causes a decrease in the longitudinal and transverse Young's modulus of composites, compared to the straight nanotube reinforcement, but the change in the value of transverse Young's modulus (Eyy) is less remarkable than the longitudinal Young's modulus (Exx). Furthermore, the effect of fiber curvature on Poisson's ratio has also been studied. The results show that the curvature has not much effect on Poisson's ratio and when a fiber curvature changes, Poisson's ratio value almost remains unchanged. In addition, the effect of fiber volume fraction on the longitudinal Young's modulus and major Poisson's ratio has been studied. As the mesh density may have a significant role in evaluating the model, several different meshes have been generated in order to predict their effect on the mechanical properties of the composite. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.


Benam A.S.,University of Applied Science and Technology of Iran
China Foundry | Year: 2015

Austempered ductile iron (ADI) parts have a unique combination of high strength and toughness with excellent design flexibility and low cost. These excellent properties are directly related to its microstructure called "ausferrite" that is the result of austempering heat treatment applied to ductile irons. Alloying elements increase ADI austemperability and change speeds of austempering reactions. Thus, they can affect ADI resultant microstructure and mechanical properties. In this paper, the effects of alloying elements on ADI mechanical properties, microstructural changes, two-stage austempering reactions, processing windows, austemperability, and other aspects are reviewed. © 2015, Foundry Journal Agency. All rights reserved.

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