Sharif Digital Repository

This survey investigated the cultural identity of Iranian English language teachers. Accordingly, a cultural identity model was proposed a priori, based on which a questionnaire was developed and piloted on 50 Iranian English language teachers (α = 0.87). The developed questionnaire was then administered to 636 male and female Iranian English language teachers. The results of confirmatory factor analysis showed that the model was fit and eight components namely 1) religious beliefs, 2) history, 3) customs, 4) manners and behaviors, 5) Persian language, 6) literature and art, 7) parents’ influence and 8) family relations were confirmed to form the core of Iranian cultural identity. The... 

The present mixed-methods research examined the identity and attitude of Iranian English language learners as a result of their participation in an online critical reflective course. The participants were 38 English language students who attended ten online sessions within a five-month English language course. Their online posts underwent inductive qualitative content analysis and subsequently five themes were extracted. In addition, the content of the first and last two sessions were analysed quantitatively. A validated questionnaire was also administered and 18 participants were interviewed. Qualitative and quantitative content analyses of the data revealed eight finalised codes. The... 

Terephthalic acid is generally produced via oxidation of p-xylene. In this process, a large quantity of residue is produced containing cobalt, manganese, and bromine catalysts as well as by-products such as benzoic acid. Our purpose is to totally recover this residue. Extraction by water has been used as an efficient method to recover catalyst from this residue. In this study, the best condition for extraction was obtained at water/residue dilution ratio of 6: 1, extraction temperature of 45°C and extraction time of 40 min. Efficiency of catalyst recovery was 92 wt % at these conditions. The catalyst containing extracted solution can be reused in the oxidation process after being... 

This survey research investigated the attitude of Iranian Azeri native speakers towards Azeri language. A questionnaire was developed and its reliability was estimated (r = 0.74) through a piloting phase on 54 Azeri native speakers. The participants, for the main phase of this study, were 400 Azeri native speakers with different social and educational backgrounds and from some densely Azeri-populated provinces in Iran. They completed either the online or the printed version of the survey, the results of which indicated that Iranian Azeri native speakers have a high level of positive attitude towards their mother tongue in spite of the negligence of this language in the Iranian educational... 

To ameliorate high collision, a nefarious side effect of route discovery stage of reactive routing protocols in wireless networks, jitter mechanisms are proposed which enforce wireless nodes to postpone their transmission for a random amount of time so as to reduce probability of simultaneous transmission. Although it has been shown that jitter mechanisms can dramatically improve reactive routing protocols, it was not until recently that jitter mechanisms have been subjected to study. In this paper, different random distributions are proposed for jittering mechanisms and also shaping function, with the aim of which a simple routing protocol like AODV becomes sensitive to any arbitrary... 

In recent years, descriptive evaluation has been introduced as a new model for educational evaluation of Iranian students. The current descriptive evaluation method is based on four-valued logic. Assessing all students with only four values is led to a lack of relative justice and creation of unrealistic equality. Also, the complexity of the evaluation process in the current method increases teacher error’s likelihood. As a suitable solution, in this paper, a fuzzy descriptive evaluation system has been proposed. The proposed method is based on fuzzy logic, which is an infinite-valued logic, and it can perform approximate reasoning on natural language propositions. By the proposed fuzzy... 

Structural, microstructural and mechanical properties in roll bonding of AA5052 and polypropylene sheets have been evaluated in this study. The surface roughness of the AA5052 sheets, rolling temperature and the surface energy of polymer were selected as the bonding variables. The findings indicated that an increase in the surface energy of polypropylene by grafting maleic anhydride would result in higher bonding strength due to chemical interaction between the AA5052 and the maleic anhydride grafted polypropylene (PP-g-MAH). In fact, this reaction caused the formation of an interphase layer at the polymer side of the interface and the diffusion of aluminum into the PP-g-MAH layer. It was... 

Structural, microstructural and mechanical properties in roll bonding of AA5052 and polypropylene sheets have been evaluated in this study. The surface roughness of the AA5052 sheets, rolling temperature and the surface energy of polymer were selected as the bonding variables. The findings indicated that an increase in the surface energy of polypropylene by grafting maleic anhydride would result in higher bonding strength due to chemical interaction between the AA5052 and the maleic anhydride grafted polypropylene (PP-g-MAH). In fact, this reaction caused the formation of an interphase layer at the polymer side of the interface and the diffusion of aluminum into the PP-g-MAH layer. It was... 

Fracture process of fiber-reinforced concrete notched beams is investigated here. Polypropylene macrosynthetic fibers are utilized for reinforcing concrete specimens, and a high-strength mix design is used to produce strong bonds between the embossed polypropylene fibers and the cementitious matrix of beams. Considering different locations for the notch, this study focuses on bridging mechanism under different conditions using both experimental and numerical approaches. First mode of fracture occurs due to opening of crack faces. This mode of failure is simulated by imposing symmetric boundary conditions on middle-notched beams. Inducing the notch with an offset from the middle, mixed-mode... 

In this paper, the impression of surface oxidization on the aluminum nanopowders is investigated using the reactive molecular dynamics (MD) method under the triaxial compression tests. Validation of the computational model is examined with the experimental results, which demonstrates an acceptable accuracy of the numerical simulations. The MD simulations are performed in three stages; relaxing the nanopowders at 300 K and 0.1 MPa, confining the nanopowders under hydrostatic pressure, and imposing the deviatoric stress through the triaxial compression. Evolutions of the relative density with pressure, stress with strain, and dislocation density with strain are derived together with the... 

Fracture process of fiber-reinforced concrete notched beams is investigated here. Polypropylene macrosynthetic fibers are utilized for reinforcing concrete specimens, and a high-strength mix design is used to produce strong bonds between the embossed polypropylene fibers and the cementitious matrix of beams. Considering different locations for the notch, this study focuses on bridging mechanism under different conditions using both experimental and numerical approaches. First mode of fracture occurs due to opening of crack faces. This mode of failure is simulated by imposing symmetric boundary conditions on middle-notched beams. Inducing the notch with an offset from the middle, mixed-mode... 

This research investigates a three dimensional parametric risk assessment model considering the 3rd factor to be the impact on business. In order to represent the 3rd order risk assessment matrix monitoring the impact of safety reports on the continuous economical performance of the airline, the other two factors, probability of safety and severity are redefined. Introducing two quantitative and qualitative assessment methodologies, the overall risk of the organization can be studied by means of Analytical Hierarchy Process (AHP). providing an adequate background to define the safety goals of the organization  

In the present study, the electrodeposition of Fe, Pd and Fe-Pd alloys, in alkaline solutions, has been investigated. Using ammonium hydroxide and trisodium citrate as the complexing agents, it has been shown that the co-deposition of Fe and Pd is achieved due to diminishing the difference between the reduction potentials of these two metals. Cyclic voltammetry results clearly show that the electrodeposition processes are diffusion-controlled and the diffusion coefficients of Fe2+ and Pd2+ are 1.11 × 10-6 and 2.19 × 10-5 cm2 s -1, respectively. The step potential experiments reveal that nucleation mechanism is instantaneous with a typical three-dimensional (3D) growth. At low overpotentials,... 

Cognitive radio (CR) technology enables dynamic spectrum access (DSA) to improve the efficiency of under-utilized licensed bands and overcrowded unlicensed bands. However, providing an acceptable service for cognitive users requires more sophisticated approaches due to the existence of Primary Users (PU) with high priority over licensed bands. Additionally, it is of paramount importance that interference with PUs be reduced so that they can communicate without interruption. In order to meet requirements of users as much as possible and reduce interference with PUs, a new Class-based Multi-path Ondemand Routing protocol for Cognitive radio networks (CMORC) is proposed. CMORC is a multipath... 

The end-to-end throughput of multi-hop communication in wireless ad hoc networks is affected by the conflict between forwarding nodes. It has been shown that sending more packets than maximum achievable end-to-end throughput not only fails to increase throughput but also decreases throughput owing to high contention and collision. Accordingly, it is of crucial importance for a source node to know the maximum end-to-end throughput. The end-to-end throughput depends on multiple factors, such as physical layer limitations, medium access control (MAC) protocol properties, routing policy, and nodes' distribution. There have been many studies on analytical modeling of end-to-end throughput but... 

Textbooks provide the most serious source of knowledge construction and transmission for children at schools. This paper used a discursive and qualitative content analysis approach to extract the dominant values, ideologies and identities in four social studies textbooks taught nationwide to children in primary schools in Iran. Textual and visual analysis were applied on these textbooks and the results showed the saliency of four dominant discourses and values including pre-Islamic ethos and Iranian-Islamic identity, war and peace, social and traditional values in Iranian culture, and respect for diversity. Each of these discourses are discussed and some recommendations are made at the end... 

Textbooks provide the most serious source of knowledge construction and transmission for children at schools. This paper used a discursive and qualitative content analysis approach to extract the dominant values, ideologies and identities in four social studies textbooks taught nationwide to children in primary schools in Iran. Textual and visual analysis were applied on these textbooks and the results showed the saliency of four dominant discourses and values including pre-Islamic ethos and Iranian-Islamic identity, war and peace, social and traditional values in Iranian culture, and respect for diversity. Each of these discourses are discussed and some recommendations are made at the end... 

By displacing oil in porous media with other fluid, different mechanisms of fluid displacing occur. The importance of understanding the trapping mechanisms like pore body filling is irrefutable. Pore body filling mechanism with a coordination number of four has different events like I0, I1, I2 and I3. Previous studies showed that the event of I0 occurs when the pore is only filled by a compressible non-wetting phase, but this study showed that this event could also occur by an incompressible non-wetting phase. Trapping mechanisms can be examined in a glass micro-model. In this research, a glass micro-model with three different patterns was used. Results showed that at two spots of the... 

Mobile networks have been growing rapidly, where it is of paramount importance to evaluate the performance of any protocol designed for such networks before deployment. Mobility is one of the main mobile network issues that directly affects performance metrics. Since mobile nodes are often carried by their owners, nodes movement should be modeled according to humans movement. In this paper, we extend our previously published human mobility model based on real collected data. The real human movement is traced, cleaned up and analyzed. To the best of our knowledge, our collected data set is the only one that contains the detail of both walking and driving nodes. The analysis shows several... 

In this paper, the problem of placing a minimum number of phasor measurement units (PMUs) in a transmission system is considered so that faults on all lines of the network can be diagnosed and located irrespective of their locations. For this purpose, a PMU placement algorithm is applied to calculate the required data for impedance-based fault location of any fault line in the network, achieving the full potential of the circuit laws throughout the system. Another algorithm is then proposed to compute the voltage and current values of the fault line for fault-location purposes. Moreover, as many networks are already equipped with PMUs, the proposed algorithm makes it possible to locate...