Radio, television (TV), movies, video games, cell phones, and computer networks have assumed central roles in our children's daily lives. The media has demonstrated potentially profound effects, both positive and negative, on children's cognitive, social, and behavioral development. Considering the increasing exposure of children to newer forms of media, we decided to review the current literature on the effects of media on child health both in the Western countries and India. It is widely accepted that media has profound influence on child health, including violence, obesity, tobacco and alcohol use, and risky sexual behaviors. Simultaneously, media may have some positive effects on child health. We need to find ways to optimize the role of media in our society, taking advantage of their positive attributes and minimizing their negative ones. We need to understand better how to reverse the negative impact of media and make it more positive.
An LSDYNA finite element model of the knee-thigh-hip (KTH) of a 50th percentile male was developed for exploring mechanics of injuries to the KTH during frontal crashes. This includes a model of the geometry of bones and also discrete element representations of ligaments and muscles of the KTH. The model was validated using physical tests obtained from the National Highway Traffic and Safety Administration's (NHTSA) test database. Validation of individual components like the upper femur, femoral condyles and pelvis were performed and compared to similar physical tests. The results were used to verify geometry, material properties and failure mechanisms of bone materials. Validations were also performed against a whole-body cadaver test to verify contributions of passive muscle and ligament forces. Failure mechanisms in the tests and simulations were compared to ensure the model provides a useful tool for exploring fractures in the KTH resulting from frontal vehicle crashes.
The performance of many guardrail terminal systems is dependent on the strength of timber guardrail posts and soil conditions. Accurately simulating the breakaway characteristits of guardrail posts mounted in soils is an important issue concerning researchers in the roadside safety community. Finite-element analysis is one method that can be used to evaluate roadside hardware designs, but good simulations are contingent on developing accurate models of the components. A description is provided of the development of a model of a breakaway timber post and soil system used in the breakaway cable terminal (BCT) and the modified eccentric loader terminal (MELT). The model is described and simulation results are compared with data from physical tests of BCT/MELT posts.
The weak-post W-beam guardrail has been widely used in the Northeast for many decades. Weak-post guardrails are characterized by larger dynamic deflections in a collision and are considered more forgiving than other, stiffer barriers. Most states have experienced good performance with these barriers over the last several decades if adequate clear space is provided behind the barrier. Unfortunately, recent crash tests of the standard weak-post W-beam guardrail involving a 2000-kg pickup truck resulted in a series of unacceptable test results, including overriding and penetrating the guardrail. Design modifications to the weak-post W-beam guardrail were explored by using finite element simulations and full-scale crash tests. An improved version of the weak-post W-beam guardrail system was developed and tested, and this was found to satisfy the requirements of NCHRP Report 350 for Test Level 3.
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