background: more than 50% of the total dose received by human beings from all sources of radiation (both from natural and manmade) comes from radon and its progeny which is responsible for lung cancer in many cases. materials and methods: in the present study, the measurements have been carried out by using twin chamber dosimeter cups with lr-115 type-ii detectors. the value of track density of...

the vibrations produced by trains include two parts which are deterministic and random vibrations. due to variation of dynamic loads and patterns of load-time, the random vibration of moving train is one of the most important issues in the field of railway engineering. one of the important sources in producing the train vibrations is rail roughness and irregularities. in this paper, responses o...

in order to study the effects of sugar cane harvest machinery traffic on bulk density and cone index variation, a survey was conducted in 10 farms of deabel khozaiee sugarcane agro-industrial company, ahvaz, in 2006. in this experiment, two types of harvesters including wheel half track and tire wheels with 14 tons of weight, versus two types of tractor and basket transporters, with 10 and 18 t...

current practices in railway track analysis and design are reviewed and discussed in this paper. the mechanical behavior of railway track structure comprising of various components has not been fully understood due to the railway track structural complexity. although there have been some improvements in the accuracy of current track design methods in recent decades, there are still considerable...

Nearly all proposed tests for the nature of dark energy measure some combination of four fundamental observables: the Hubble parameter H(z), the distance-redshift relation d(z), the age-redshift relation t(z), or the linear growth factor D1(z). I discuss the sensitivity of these observables to the value and redshift history of the equation of state parameter w, emphasizing where these different...