RESUMEN
Chatter has been recognized as major restriction for the increase in productivity of cold rolling processes, limiting the rolling speed for thin steel strips. It is shown that chatter has close relation with rolling conditions. So the main aim of this paper is to attain the optimum set points of rolling to achieve maximum rolling speed, preventing chatter to occur. Two combination methods were used for optimization. First method is done in four steps: providing a simulation program for chatter analysis, preparing data from simulation program based on central composite design of experiment, developing a statistical model to relate system tendency to chatter and rolling parameters by response surface methodology, and finally optimizing the process by genetic algorithm. Second method has analogous stages. But central composite design of experiment is replaced by Taguchi method and response surface methodology is replaced by neural network method. Also a study on the influence of the rolling parameters on system stability has been carried out. By using these combination methods, new set points were determined and significant improvement achieved in rolling speed
RESUMEN
Background and Purpose: Using levonorgestrel tablet is one of EC methods that could be effective until 72 hours after sexual intercourse. Therefore, the present study was intended to investigate the women's awareness about correct use and sideeffects of this tablet
Methods and Materials: In this descriptive analytical study, women referring to heath centers of Sabzevar were selected through cluster sampling. Data were collected through a questionnaire including specific demographic characteristics and the participants' awareness about correct using and side effects of levonorgestrel tablet. The reliability of the questionnaire was checked with cronbach alpha [= alpha 0.716], and its validity was controlled by expert. The sample size was 396 persons. The obtained data were analyzed in SPSS using descriptive and analytical statistics [independent t-test and Pearson correlation coefficient]
Results: Among women studied, 29.8% had used the tablet, and the average score of awareness in correct using of tablet on the basis of 100 was 46.1 +/- 34.5, while the average score of knowing the tablet's side effects on the basis of 100 was only 22.39 +/- 28.92. A negative correlation was found between the correct using score and age [p=0.029, r=-0.11]
Conclusion: The findings revealed that the average awareness score of correct using and side-effects of the tablet are low