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With increase in the axle load and wagon speed, the cost of damage to rail track and wagon components increases significantly. This leads to widespread interests in the investigation of the dynamic interactions of the rail track and the wagon. Rail irregularities are one of the important vibration sources of the rail track structure and train. These irregularities have generally random distribution that are assumed to be stationary random and ergodic processes in space, with Gaussian amplitude probability densities and zero mean values. In this paper, the dynamic response of the railway vehicle due to random irregularity of rail track is analysed. The wagon is modelled as a two degrees-of-freedom non-linear model where includes non-linear spring and linear damper of primary suspension system. The Hertzian contact theory is used to obtain the relationship between normal contact force and the displacement of the mass centre of the wheel. Using the method of multiple scales the analytical approximate response of the railway vehicle due to track irregularities is obtained. The amplitudes of vibrations of the vehicle and the interaction forces between the vehicle and the rail for different line grades and train speeds have been analysed analytically by this model. According to the results, rail irregularities have more effect on the vertical acceleration of the vehicle than the train speed.

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This study was an attempt to investigate the effect of input enhancement instruction on vocabulary acquisition among Iranian university students. Moreover, the possible effect of two kinds of input enhancement (i.e., auditory and visual) was examined. To this end, 75 Iranian university students, majoring English language Teaching at Applied Science and Technology of Kurdistan University, Iran, were randomly selected. The method used in this study was quantitative research and the true experimental design. One experimental group received vocabulary instruction via visual input enhancement, and the other experimental group was taught vocabulary via auditory input enhancement. After administering the posttest, the dada was analyzed by one-way ANOVA. The findings revealed that both auditory and visual input enhanced instruction had a significant effect on the vocabulary development of Iranian EFL students. In addition, comparing the efficacy of two types of instruction, the results indicated that the effect of either visual or auditory input enhancement for both experimental EFL university students were fairly the same in Iranian EFL educational setting.

Images are part of the content of the English textbooks and since junior high school curriculum is currently being underdevelopment, developing criteria for the images of the content of high school textbooks needs attentive consideration. The images need to be chosen according to the needs of students and those objectives found at the higher level documents. This research is conducted based on mixed approach in which students' need is surveyed and data gathered by sifting through the higher level documents. Also, exploring the goals and objectives of the higher level documents, the criteria are obtained and determined by which the content was developed. In addition, the Delphi method is applied to measure the validity of the developed content. The study population at this research consisted of all students in the seventh grade (the first grade of high school), the third grade Secondary School and the first grade high school in five provinces of Iran, including Tehran, Semnan, Kurdistan, Khuzestan and East Azerbaijan counting 394 boys and 396 girls who completed the questionnaire. Also, 10 accessible experts and practitioners in English curriculum participated in developing and validating the criteria. One of the findings of this research indicates that 321 students interested in real images at the first rank and 306 other students fascinated with colored ones, at the second rank respectively.