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Due to high hardness, low density and heat resistance, ceramics are widely used in armor applications and industry, thus, in this study, perforation process of projectile into ceramic targets is investigated analytically and numerically and a modified model is developed. In the analytical section, Woodward’s theory, one of the important theories in perforation process of projectile into ceramic targets, is investigated and some modifications are applied in Woodward’s model, hence the ballistic results of analytical method are improved and the modified model shows good agreement with the experimental results that in the analytical section, the modified model is based on Woodward’s model and modification of semi-angle of ceramic fracture cone, erosion, mushrooming and rigid from of projectile and also changes in yield strength of ceramic during perforation process, damage, are considered. In the numerical section, a finite element model is created using Ls-Dyna software and perforation process of projectile into Ceramic-Aluminum target is simulated. The results of the analytical method and numerical simulation are compared to the results of the other investigators and results of modified model show improvement in prediction of ballistic results.

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Background: Cerebral stroke, known as one of the most common causes of mortality and morbidity worldwide. The frequency of stroke is rising by ageing the population and placed a significant concern for public health. However, modifying risk factors contributing to stroke may decrease the burden of the disease. This study aimed to examine the association of life stressors and personality types with stroke. Method: The participants were a convenient clinical sample of 100 patients with ischemic stroke and 100 individuals without stroke. The Paykel life event questionnaire and Friedman and Rosenman personality type questionnaire were used to evaluate life stressor and personality characteristics, respectively. Results: Among the different types of stressor subgroups, mean prevalence score of total life stressors, psycho-social stressors, frustration-despair stressors and mental-physical stressors were significantly higher in patients (p=0.001, p<0.001, p=0.001, and p<0.001 respectively). The prevalence of type A personality in stroke patients and control groups were 52 and 45 %, respectively (p = 0.322). Severity scores of stressors were often higher in cerebral infarction patients with type A personality. Conclusion: There is an association between higher psychological stressors and stroke, and people with type A personality in both groups experienced more stress than type B. It suggests that cerebral infarction patients with type A personality have a higher level of stress in response to life events which could be considered as a modifiable factor.