Численная модель системы вывода электронного пучка медицинского ускорителя

A novel incremental ring rolling process is proposed, in which a narrow mandrel is moved both radially and axially. The process has potential to allow flexible near-net-shape forming of both hot and cold rings, and has been assessed by experiments on commercial cold ring rolling machines, a physical simulation using wax rings, and two finite element models. The results suggest that the process is technically feasible although the cycle time increases with the degree of flexibility and the stability of deformation depends on careful design of the tool path

Time-temperature-transformation diagram within the bainitic temperature range in a medium carbon steel

The time-temperature-transformation (ITT) diagram within the medium temperature range of medium carbon steel has been determined. A single type of C-curve is found within the bainite temperature range for the studied steel. Distinct reaction C-curves were not observed for both types of microstructure, upper bainite and lower bainite in the TTT diagram. Experimental results on the kinetics of the isothermal formation of bainite at different temperature have demonstrated that both type of microstructure, upper and lower bainite, possesses similar overall transformation kinetics. Some applications of phase transformation theory towards the formation of bainitic microstructures are discussed, with particular emphasis on the bainite start temperature, transition temperature from upper to lower bainite, martensite start temperature and the thickness of bainitic plates.Peer Reviewe

An international comparison of the science education priorities of science teachers, lecturers and students in two developing countries: Turkey and Lesotho

Lesotho and Turkey are two developing countries, both relatively deficient in educational resources one in Southern Africa, and the other straddling the continents of Europe and Asia in the Middle East. This study reports and compares the priorities and responses of (a) 172 Turkish science teachers, lecturers and students, and (b) 171 Lesotho science educators and students, to 20 literature derived recommendations for improving science education in the two countries. Both quantitative and qualitative sur vey data are analysed. The educational outcomes of the study are commonly identified areas of future concentration and corresponding sets of recommendations for science teacher training curricula in these two developing nations. In both Turkey and Lesotho the most frequently prioritised recommendations are found to be similar. They are: to engage more self discovery in science learning; to introduce more real life skills into science teaching; to utilise better science teaching methods; and to acquire more resources for science and technology lessons

An international comparison of the science education priorities of science teachers, lecturers and students in two developing countries: Turkey and Lesotho

Lesotho and Turkey are two developing countries, both relatively deficient in educational resources B one in Southern Africa, and the other straddling the continents of Europe and Asia in the Middle East. This study reports and compares the priorities and responses of (a) 172 Turkish science teachers, lecturers and students, and (b) 171 Lesotho science educators and students, to 20 literature-derived recommendations for improving science education in the two countries. Both quantitative and qualitative survey data are analysed. The educational outcomes of the study are commonly identified areas of future concentration and corresponding sets of recommendations for science teacher-training curricula in these two developing nations. In both Turkey and Lesotho the most frequently prioritised recommendations are found to be similar. They are: to engage more self-discovery in science learning; to introduce more real life skills into science teaching; to utilise better science teaching methods; and to acquire more resources for science and technology lessons. South African Journal of Higher Education Vol.17(2) 2003: 187-19