This paper investigates the computational solution to the problem of projectile motion under a significant linear drag effect. The drag force acting on the particle within the medium of propagation is proportional to ...This paper investigates the computational solution to the problem of projectile motion under a significant linear drag effect. The drag force acting on the particle within the medium of propagation is proportional to the cross-section area of the projectile, the velocity of the particle, and the medium’s density. From zero air resistance force (vacuum) the problems are well known with solutions, but with air resistance (drag force) the problems have no exact analytical solutions which lead to most of the significant scientific research works using numerical methods. Therefore, this study aims to present the analysis of the computational modelling of drag force exerted by the surrounding medium on the linear motion. However, the horizontal and vertical components of differential equations of motion were derived and characterized from the solutions governed by Newton’s 2<sup>nd</sup> law of motion. The baseball features were presented as the projectile (object) in this work. In addition, the numerical computational results were received from FreeMat. The results were discussed and compared with those from the vacuum. Moreover, the displacements, velocities, range, and trajectories of the projectile were all discussed and a conclusion was made.展开更多
Objective: To assess current practices, attitudes, and perceived barriers toward pediatric vision screening. Patients and Methods: A link to a 9-question survey was electronically distributed to a national sample of 6...Objective: To assess current practices, attitudes, and perceived barriers toward pediatric vision screening. Patients and Methods: A link to a 9-question survey was electronically distributed to a national sample of 6000 pediatricians through Medical Marketing Services Inc. Data were collected using Survey Monkey. Results: Email open rate was 11%;37% of those who opened the email responded (225 respondents). Over ninety percent of respondents perform some type of vision screening at least yearly, although age at which screening began varied, with two thirds of respondents instituting formal vision screening after three years. Fifty eight percent of respondents were either extremely unsatisfied, unsatisfied or only somewhat satisfied with their current screening method. Preferred methods of screening and confidence of pediatricians in their ability to detect pathology varied for children under versus over age three. The least frequently used methods for all age groups were autorefraction and photoscreening. The most commonly reported barriers to screening were inadequate training (48%), time required for exam (42%), and inadequate reimbursement (32%). Conclusions: Perceived barriers to vision screening in the pediatrician office have been previously identified, and photoscreening and autorefraction have been identified as a possible means to circumvent them. In spite of the addition of new procedural codes, pediatricians continue to report similar barriers to screening.展开更多
文摘This paper investigates the computational solution to the problem of projectile motion under a significant linear drag effect. The drag force acting on the particle within the medium of propagation is proportional to the cross-section area of the projectile, the velocity of the particle, and the medium’s density. From zero air resistance force (vacuum) the problems are well known with solutions, but with air resistance (drag force) the problems have no exact analytical solutions which lead to most of the significant scientific research works using numerical methods. Therefore, this study aims to present the analysis of the computational modelling of drag force exerted by the surrounding medium on the linear motion. However, the horizontal and vertical components of differential equations of motion were derived and characterized from the solutions governed by Newton’s 2<sup>nd</sup> law of motion. The baseball features were presented as the projectile (object) in this work. In addition, the numerical computational results were received from FreeMat. The results were discussed and compared with those from the vacuum. Moreover, the displacements, velocities, range, and trajectories of the projectile were all discussed and a conclusion was made.
文摘Objective: To assess current practices, attitudes, and perceived barriers toward pediatric vision screening. Patients and Methods: A link to a 9-question survey was electronically distributed to a national sample of 6000 pediatricians through Medical Marketing Services Inc. Data were collected using Survey Monkey. Results: Email open rate was 11%;37% of those who opened the email responded (225 respondents). Over ninety percent of respondents perform some type of vision screening at least yearly, although age at which screening began varied, with two thirds of respondents instituting formal vision screening after three years. Fifty eight percent of respondents were either extremely unsatisfied, unsatisfied or only somewhat satisfied with their current screening method. Preferred methods of screening and confidence of pediatricians in their ability to detect pathology varied for children under versus over age three. The least frequently used methods for all age groups were autorefraction and photoscreening. The most commonly reported barriers to screening were inadequate training (48%), time required for exam (42%), and inadequate reimbursement (32%). Conclusions: Perceived barriers to vision screening in the pediatrician office have been previously identified, and photoscreening and autorefraction have been identified as a possible means to circumvent them. In spite of the addition of new procedural codes, pediatricians continue to report similar barriers to screening.
