dr. i. ebrahimzadeh

In this research, the transient liquid phase bonding of St52 carbon steel to WC-Co cermet using a copper interlayer with 50 μm thickness was done. For this purpose, samples were jointed to each other at a constant temperature of 1100 ºC and bonding times of 1, 15, 30, and 45 min. The microstructure of the joints was examined using an optical microscope and scanning electron microscope equipped with energy-dispersive X-ray spectroscopy. XRD analysis was also used to investigate the effect of bonding on the phase changes of the bonding area. Microhardness and tensile shear tests were also conducted to study the mechanical properties of the samples. Microstructural investigations showed the formation of three different zones including isothermal and athermal solidification zones and DAZ in the WC-Co base material side, which determine the characteristics of the samples. The isothermal solidification zone contained a Fe-rich solid solution and the athermal solidification zone contained a Cu-rich solid solution. η phase was not formed in the DAZ of WC-Co cermet at bonding times of 1 and 15 min. This phase was formed in the DAZ of WC-Co cermet by increasing the bonding time to 30 and 45 min. The microhardness studies showed that all samples had the same trend. Maximum microhardness was 1100 HV which was related to WC-Co base cermet and the lowest microhardness was about 220 HV which was related to steel base metal. Also, the maximum tensile-shear strength of the bonded samples was about 180 MPa for a bonded sample at a bonding time of 15 min, which was due to the increase in the volume fraction of iron-rich solid solution, as well as proper microstructural continuity and the presence of an optimal amount of copper-rich phase in the microstructure.

In this study, the shear spinning process and the rolling process on C11000 copper metal with a thickness reduction of 50% at room temperature were performed and investigated. In the shear spinning specimen, the grains are stretched in the axis direction and elongated in the circumferential direction. In the rolled specimen, the grains are extended in the direction of rolling, and the elongation of the grains in the T-N plane is less than in the shear spinning specimen. EBSD analysis showed that the ratio of high angle boundaries to low angle boundaries in the shear spinning specimen is higher than the rolled specimen. The mechanical properties of the rolled and shear spinning specimens were investigated in three directions of zero, 45, and 90 degrees relative to the forming direction, which showed that the strength in all three directions was higher in the rolled specimen than in the shear spinning specimen. The elongation in the shear spinning specimen is more than in the rolled specimen. The highest amount of tensile strength in the rolled specimen is about 370 MPa, and the highest elongation is about 12% in the shear spinning specimen. Also, anisotropy in shear spinning specimens was less than rolled specimens.

Spinning is one of the novel and unique processes in metal forming for the production of cylindrical and conical thin-walled parts with precise tolerances, good surface smoothness and suitable mechanical properties. This process includes conventional spinning, shear forming and flow forming. Metallurgical investigation is great importance in this process. The microstructure obtained from the spinning specimens, especially the shear forming and flow-forming, shows that the grains and the impurity particles are elongated in the direction of the main axis and are also stretched in the circumferential direction. This change in grain size on the roller side was larger than on the mandrel side. Fragmentation of coarse and brittle particles has also been observed. Also, due to the amount of strain and forces applied, the grain size decreases and as a result, the strength increases. The texture of the spinning parts has also changed. As the thickness decreases, the orientation of the grains and textures increases and the large angle boundaries increase

In this study, the effect of cladded tungsten carbide layer upon HSS - M2 tool steel on microstructure, hardness, and wear behavior has been studied in two cases without using the middle layer and using the middle layer of nickel. Tungsten Carbide cladded on HSS - M2 tool steel by Arc Weld ( SMAW ). The ASTM-G65 wear test was used to determine its application for use in the mineral industry. The results show that the formation of M6C ( tungsten - rich carbide) is deposited layer, as well as tungsten carbide with the formation of a composite layer on the base metal surface, increases the wear resistance up to 60% and the hardness up to 150% compared to the uncoated sample. Comparing the results in terms of the use or non-use of the middle nickel layer indicates the improvement of wear behavior in conditions without using middle nickel layers.

In this article, the insight of the foreign language faculties towards using information technologies in teaching languages online, have been investigated in four fields of teaching languages including: English, French, German and Farsi. Meanwhile the foreign language faculties’ perceptions towards the facilities provided at their work and their readiness to take part in the workshops of teaching languages online were studied descriptively. Different variables such as age, sex, educational rank and types of teaching (virtual online via face to face) were also considered thoroughly. 68 language faculties, from 7 different universities, answered the questionaires. The result showed that most of the language faculties were not aware of IT based devices or strategies of teaching their courses in virtual environments, and the necessary technological infrastructure and facilities for online language teaching is totally different at their work. It was cleared out that the majority numbers of foreign language faculties need to pass supplementary courses in almost all of the fields related to teaching languages electronically. However, the educational rank showed some positive effect on transition towards e- teaching, the higher the educational rank or teaching section, the more tendency towards using online strategies or devices, could be observed. Therefore, the researcher concluded that a well-planned, proactive IT-based training program for foreign language faculty is an essential prerequisite for further educational development in our country.

Over the recent decades, a massive amount of new knowledge and research has been added to various fields of science including engineering. Due to the half-life of knowledge and the urgent need for replacing old information with new findings, learning has become quite challenging task for the learners. The demand of new line of learning is focus on critical thinking, problem solving, and applying learned materials in various fields. Also, in different area of engineering, learning and appropriate application of knowledge is of remarkable significance. In order to prepare an appropriate instructional design for different fields of study, the various approaches to information analysis and learning styles of students should be examined and revised. The aim of this research was to study and compare learning styles and their relation to hemispheric dominance in male and female engineering students. The results of this study indicated that engineering male and female students are different with regard to their perception and processing information and their learning styles. Also, there was a significant relationship between learning styles and hemispheric dominance. Findings of this study would be beneficial for appropriate instructional designs, especially in distance education.

Introduction Ignoring the villages in the process of development plans, particularly in the developing countries caused considerable differences and socio-economic between rural and urban communities. The poverty and deprivation derived from such situation made the rural residents to migrate to other settlements such as towns and cities in order to improve their own social and economical position. This kind of movements which is due to different motivations satisfies the migrant’s in small towns. The impacts of ignoring the villages in the development plans were the lack of services and opportunities as well as the lack of settlement hierarchies for the better distribution of services which led to immense rural migration. In such cases villages with further distance from the urban centers with unsuitable accessibility find their security both socially and economically in migrating to the towns and cities, where they are being considered as a more deprived residents. However this kind of migration is found in different levels of the country from national to local ones. The individual and family movements of rural residents of Mamasani are an obvious example for this claim.. As such 27 out of 35 Mamasani’s villages have had negative population growth rate which ranges between -0/7 to-7/39 percent. Due to the importance and sensitivity of unplanned rural - urban migration and its rate of increase as well as its due depopulation particularly in regard to the young ones, this paper attempts to understand the factors which have been causing the rural –urban migration in Mamasani County. It also tries to focus attention on the role of distance, accessibility and services in such movements. Theoretical Bases The increase of inequality between rural and urban centers particularly in regard to income, job opportunity, services and etc. in the developing world have been acting as a push and pull factors between these centers and led to immense migration to the urban centers. In fact the lack of facilities for sustainable livelihood in the rural areas not only led to poverty and the increase of socio-economic gaps between these centers but in case of continuity causes the deserted villages. In this case distance as a physical and relative indicator can be considered as basic factors for determination of interaction and movement between these places. As a result the theoretical bases of this research are mainly based on the gravity and distance decay Models. These models are generally based on the the theory that “everything is related to everything else”. The first model is taken from Isaac Newton which throws light on geographer’s understanding of flows and movements between places. It believes that nearby things are more related. So the flow of migration between the cities is directly related to the size of the cities involved and inversely proportional to the distance separating them. These theories for justifying the volume of migration pay attention to distance and accessibility too. Accordingly settlements with more services and less distance in regard to its peripheral centers have more attraction. Discussion The analysis of data shows that the 52 percent of samples household have mainly migrated due to their social needs such as lack and shortage of welfare and livelihood opportunities in the original villages. The accessibility to job opportunities and income increase were the reason for 39 percent of the samples for migration to Norabad. For the illumination of the role and importance of Norabad in the population changes of the migrant’s origin, the relationship between distance and their population for the years 1375 and 1385 were calculated. The finding shows that those villages with distance under the median have more population and this is vice versa for those higher than median. For the better understanding of the relationship between the populations of original villages with services the centrality index were calculated. Accordingly the median for all the villages was 19 and the range of changes were between 2-103 and from 35 of villages 25 were below the mean and 8 out of 10 villages which were above the mean had a population of more than 1000 person each. The analysis of data also shows the relationship between the unsuitability of roads with distance and the landforms on which the villages are situated with their out-migration. As such among 27 of villages with negative population growth rate 14 had an unsuitable roads and 15 from the landform point of view were mountainous- plains. on the other hand among 8 of those villages with positive population growth rate 5 had a suitable road, 6 were plain-mountainous and 5 had a distance below the mean. Conclusion The spatial analysis of the migration causes shows the role of distance and other variables such as services, means of accessibility, mountainous situation and unsuitable roads and the landform of the villages in their out-migration. Accordingly when the mountainous situation and unsuitable roads of migrants origin were added to the high distance from Norabad the result was the decline in services and consequently the increase of migration and under population of the villages. This is vice versa for those with lower distance, better accessibility and plain landform. Suggestions: The most important suggestions which can be given for the betterment of the study area is summarized as below *planning for the reduction of spatial inequality between Norabad and the peripheral villages by adapting the regional approach in rural development * Paying special attention to the role of distance and accessibility in spatial and hierarchical arrangement of rural settlements *extension and renewing the road networks between urban and rural centers in particulate to those villages further away from the urban centers.