Khayyam Higher Education Institute

Mashhad, Iran

Khayyam Higher Education Institute

Mashhad, Iran
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Karimi H.,University of Technology Malaysia | Rahmani R.,University of Technology Malaysia | Mashayekhi R.,Khayyam higher education Institute | Ranjbari L.,University of Technology Malaysia | And 5 more authors.
Beilstein Journal of Nanotechnology | Year: 2014

Graphene, which as a new carbon material shows great potential for a range of applications because of its exceptional electronic and mechanical properties, becomes a matter of attention in these years. The use of graphene in nanoscale devices plays an important role in achieving more accurate and faster devices. Although there are lots of experimental studies in this area, there is a lack of analytical models. Quantum capacitance as one of the important properties of field effect transistors (FETs) is in our focus. The quantum capacitance of electrolyte-gated transistors (EGFETs) along with a relevant equivalent circuit is suggested in terms of Fermi velocity, carrier density, and fundamental physical quantities. The analytical model is compared with the experimental data and the mean absolute percentage error (MAPE) is calculated to be 11.82. In order to decrease the error, a new function of E composed of α and β parameters is suggested. In another attempt, the ant colony optimization (ACO) algorithm is implemented for optimization and development of an analytical model to obtain a more accurate capacitance model. To further confirm this viewpoint, based on the given results, the accuracy of the optimized model is more than 97% which is in an acceptable range of accuracy. © 2014 Karimi et al; licensee Beilstein-Institut.


Naderi A.,Islamic Azad University at Mashhad | Mazinani S.M.,Imam Reza University | Shirazi A.Z.,Khayyam Higher Education Institute | Setoodefar M.,Khayyam Higher Education Institute | Faghihnia M.,Mashhad University of Medical Sciences
Proceedings - 2012 IEEE 17th International Conference on Engineering of Complex Computer Systems, ICECCS 2012 | Year: 2012

A good deal of research and development has been carried out in architecture and protocol design, energy saving and location, but only a few studies have been done on network performance in WSN (Quality of Service-QoS). The commonly accepted QoS metrics include bandwidth, delay, delay jitter and reliability. Whereas the majority of developed applications for WSNs are event-critical applications, achieving reliable data transfer as the main factor of dependability and quality of service seems vital. In many applications, the reliability level required by the data packets is different. Also, there are some applications in which the significance of the data obtained from the sensor nodes, depends on the majority of the reports denoting occurrence of specific events in some parts of the environment. In this paper, we focus on building a routing protocol called MBRR which routes packets towards the destination node in a highly reliable manner by classifying data into differentiated classes. Moreover, MBRR employs a new adaptive policy called majority based re-routing policy in order to route the packets with instantaneously change in number implying occurrence of special events via more reliable paths. © 2012 C.E.S.A.M.E.S.


PubMed | University of Turku, University of Genoa, University of Technology Malaysia, khayyam higher education Institute and 2 more.
Type: | Journal: Beilstein journal of nanotechnology | Year: 2014

Graphene, which as a new carbon material shows great potential for a range of applications because of its exceptional electronic and mechanical properties, becomes a matter of attention in these years. The use of graphene in nanoscale devices plays an important role in achieving more accurate and faster devices. Although there are lots of experimental studies in this area, there is a lack of analytical models. Quantum capacitance as one of the important properties of field effect transistors (FETs) is in our focus. The quantum capacitance of electrolyte-gated transistors (EGFETs) along with a relevant equivalent circuit is suggested in terms of Fermi velocity, carrier density, and fundamental physical quantities. The analytical model is compared with the experimental data and the mean absolute percentage error (MAPE) is calculated to be 11.82. In order to decrease the error, a new function of E composed of and parameters is suggested. In another attempt, the ant colony optimization (ACO) algorithm is implemented for optimization and development of an analytical model to obtain a more accurate capacitance model. To further confirm this viewpoint, based on the given results, the accuracy of the optimized model is more than 97% which is in an acceptable range of accuracy.


Barati E.,Khayyam Higher Education Institute | Halabian M.,Iran University of Science and Technology | Karimi A.,Iran University of Science and Technology | Navidbakhsh M.,Iran University of Science and Technology
Journal of Biomaterials and Tissue Engineering | Year: 2014

In the present study, the numerical simulation of steady and Newtonian flows in S-shaped bends with sweep angle of 45 degree is performed at different Reynolds numbers. It is examined blood flow in a model of the femoral artery with and without obstruction to simulate conditions which are common in arterial disease. The effect of both conditions on the flow behavior is evaluated. Hemodynamic characteristics such as secondary flow, vorticity, and axial velocity profiles are analyzed thoroughly. The combined effects of stenosis and curvature on flow characteristics are also investigated. The results indicate that the highest wall shear stresses values are observed in the outer regions which are vulnerable sites to the initiation and development of thrombus formation lesions which leads to stroke. The results also demonstrate that the formation of shear stress by the stenotic region is higher than that by curved tube without stenosis. The results suggest the importance of location of stenosis on the hemodynamic characteristics. In addition, it is shown that stenosis at the beginning of curve has the significant effects on the flow patterns. Moreover, the wall shear stress depends on both Reynolds number and the location of stenosis on curvature. These results may have implications not only for blood hemodynamics studies and surgery simulations of arterial diseases, but also for understating the effects of cardiovascular diseases especially stenosis on the flow patterns and wall shear stress. © 2014 American Scientific Publishers. All rights reserved.


Esfahani J.A.,Ferdowsi University of Mashhad | Karbasian H.R.,Ferdowsi University of Mashhad | Kangarshahi A.F.,University of Tehran | Barati E.,Khayyam Higher Education Institute
CFD Letters | Year: 2013

One of the problems may be occurred in the Town Border Station (TBS) for reducing of natural gas pressure is a serious damage which follows the bends. In this paper the bend erosion by gas-particle flows is investigated. The process is simulated using Computational Fluid Dynamics (CFD) and solved by k-ε model. The particles momentum can easily transfer to surface of the bend and it increases the rate of erosion by disorder in pressure distribution and gas high velocity. For protecting bend form erosion a novel method is proposed. A multistage diffuser is installed before the bend, which influence on gas momentum and spread the velocity profile in pipe. Additionally, this process produces local turbulence, which helps erosion to drop. Overall results show the proposed method can notably reduce the rate of erosion until 51% and may be used as a procedure to reduce erosion in units where the gas pressure drop is their major duty, such as TBS. © 2013 All rights reserved. ISSR Journals.


Barati E.,Khayyam Higher Education Institute | Esfahani J.A.,Ferdowsi University of Mashhad
Journal of Food Engineering | Year: 2013

The paper deals with modeling the convective drying process. A relevant and reliable mathematical model that captures the history and distribution of temperature is presented. The attention is focused on the simultaneous heat and mass transfer occurring during drying where dry and hot air flows about the food. In the present study, external resistance to mass transfer is considered negligible. As a result, the drying curve is almost independent of the boundary conditions, which means that drying is diffusion-controlled. The main connotation of present study regards to undertake analytical procedure to establish the novel model for practical applications. The results show that the temperature evolution can be evaluated from an advanced analytical solution in a quick and efficient manner. The model is validated with the literature experimental data obtained for carrot and mango slabs. A good agreement is obtained between the model predictions and the available experimental results. © 2012 Elsevier Ltd. All rights reserved.


Esfahani J.A.,Ferdowsi University of Mashhad | Barati E.,Khayyam Higher Education Institute | Karbasian H.R.,Ferdowsi University of Mashhad
Journal of Naval Architecture and Marine Engineering | Year: 2013

In flapping underwater vehicles the propulsive performance of harmonically sinusoidal heaving and pitching foil will be degraded by some awkward changes in effective angle of attack profile, as the Strouhal number increases. This paper surveys different angle of attack profiles (Sinusoidal, Square, Sawtooth and Cosine) and considers their thrust production ability. In the wide range of Strouhal numbers, thrust production of Square profile is considerable but it has a discontinuity in heave velocity profile, in which an infinite acceleration exists. This problem poses a significant defect in control of flapping foil. A novel profile function is proposed to omit sharp changes in heave velocity and acceleration. Furthermore, an optimum profile is found for different Strouhal numbers with respect to Square angle of attack profile. © 2013 ANAME Publication. All rights reserved.


Esfahani J.A.,Ferdowsi University of Mashhad | Barati E.,Khayyam Higher Education Institute | Karbasian H.R.,Ferdowsi University of Mashhad
Applied Ocean Research | Year: 2013

In the present study the effect of caudal length on hydrodynamic performance of flapping foil is investigated. According to reality of swimming of fishes, the kinematics of their oscillation tail is involved with two rotational motions where one of them causes the tail to move in circular direction and the other leads the tail to pitch around its pitch axis. With this concept, a generalized kinematic model is considered. According to simulation of the motion trajectory of flapping foil, it is shown that the length of caudal may affect the hydrodynamic performance. It is shown that at lower and higher Strouhal numbers (St < 0.2 and St > 0.6) the hydrodynamic performance of flapping foil is optimum when the length of caudal is infinitive. It should be noted that at higher caudal length the variation of propulsive efficiency and produced thrust are stopped and these hydrodynamic parameters are kept at constant values. Additionally, it is demonstrated that there is the possibility of improving propulsive efficiency at moderate Strouhal numbers (0.2 < St < 0.6) by manipulation of caudal length. Furthermore, it is shown that in some cases the manipulation of caudal length may increase thrust coefficient as the propulsive efficiency is also increased. © 2013 Elsevier Ltd.


Esfahani J.A.,Ferdowsi University of Mashhad | Majdi H.,Ferdowsi University of Mashhad | Barati E.,Khayyam Higher Education Institute
Journal of Food Engineering | Year: 2014

The two-dimensional analysis of transport phenomena occurring during drying of a rectangular object is performed employing analytical method. The external flow is predicted numerically and then the convective heat transfer coefficient is determined during convective drying. The convective mass transfer coefficient is obtained through the analogy between the thermal and concentration boundary layers. After calculating average heat and mass transfer coefficients, the heat and mass transfer equations within the object are analytically solved and temperature and moisture distribution is obtained. The present study is contemplated to fill a gap in analytical modeling of two-dimensional heat and mass transfer equations; since most of analytical solutions are one-dimensional, they cannot show the effect of front and rear faces of the moist object on the drying, so the motivation to do this study is to show mentioned effect. Results demonstrated that front and rear faces have significant influences on the drying which should be considered in modeling. It is expected that the model can be applied for other food products and processes involving similar phenomenon. The analytical results are compared to the numerical ones, presenting a reasonable adjustment. © 2013 Elsevier Ltd. All rights reserved.


Mazinani S.M.,Khayyam Higher Education Institute | Naderi A.,Islamic Azad University at Mashhad | Setoodefar M.,Khayyam Higher Education Institute | Shirazi A.Z.,Khayyam Higher Education Institute
Proceedings - 2012 IEEE 17th International Conference on Engineering of Complex Computer Systems, ICECCS 2012 | Year: 2012

Many wireless sensor network (WSN) applications require real-time communication. One of the most important and challenging issues in real-time applications of resource-constrained WSNs is providing end-to-end delay requirement. To address such an issue a few QoS routing protocols have been proposed. Also, in many applications, the delay level required by the data packets is different. In this paper, we focus on building an energy-efficient real-time routing protocol called EERT which routes the differentiated classified packets towards the destination node via a modular approach. It takes into account both power transmission costs and residual energy of routers along with nearness of node to the shortest path and link usage in the energy-efficient module in order to prolong the network life time. Moreover, EERT employs a new policy called re-routing policy which allows the packets of a specific class to be routed as the packets of a lower/higher real-time class in particular situations. In this way, it can improve real-time performance by means of reducing the packet dropping in routing decisions. © 2012 C.E.S.A.M.E.S.

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