نتایج جستجو برای: railroad tunnel
تعداد نتایج: 37938 فیلتر نتایج به سال:
Diesel exhaust has been suspected to be a lung carcinogen. The assessment of this lung cancer risk has been limited by lack of studies of exposed workers followed for many years. In this study, we assessed lung cancer mortality in 54,973 U.S. railroad workers between 1959 and 1996 (38 years). By 1959, the U.S. railroad industry had largely converted from coal-fired to diesel-powered locomotives...
در دهه های اخیر استفاده از فضاهای زیرزمینی اعم از تونل های راه، راه آهن، مترو، مغارها، فضاهای زیرزمینی برای نیروگاهها، مخازن ذخیره نفت و گاز و سایر موارد رشد به سزایی داشته است. از آنجا که این فضاهای زیرزمینی مدت زمان نستبا زیادی باید استفاده شود، بنابراین پایداری آنها در مدت زمان بهره برداری از اهمیت زیادی برخوردار است. مهمترین فاکتور برای ایجاد پایداری در این فضاها، طراحی سیستم نگهداری مناسب ...
OBJECTIVE This study evaluated the prevalence of, and the risk factors for, obstructive sleep apnea syndrome (OSAS) among Brazilian railroad workers. METHODS Male railroad workers (745) from a railway company in Brazil were analyzed after responding to questionnaires about their demographics, sleep habits, excessive daytime sleepiness (Epworth), and the likelihood of having apnea (Berlin). We...
This reasearch studies ACO algorithms for the switch engine scheduling in a Railroad Yard. The cars are moved individually or grouped into blocks by a set of locomotives called switch engines which are dedicated to moving around the cars in the yard. The need for moving comes from the fact that the arriving trains are disassembled into blocks of cars, undergo some operations like, loading , unl...
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