Thermal comfort evaluation in Tehran metro using relative warmth index

Underground railway systems, can generate heat from their operations to raise the temperatures of carriages and the station substantially. This may lead to passenger discomfort and complain especially in warm weather conditions that prevail in Tehran if underground environment is not cooled. Transportation air conditioning Committee of American Society of Heating, Refrigerating and air-conditioning Engineers proposed the Relative Warmth Index for thermal comfort design and investigation in subway environment. In this research, thermal comfort at Tehran metro stations and carriages of lines 1 and 2 has been studied using this index. The measurements were taken during two periods of September 2006 and July 2007 at different zones of stations. For this purpose, temperature, relative humidity and air velocity were measured at different times. The status of the air-conditioning systems together with passenger traffic was also recorded. A total number of 231 measurements including 114 and 117 measurements were carried out in September 2006 and in July 2007 respectively. The measurements in September 2006 did not exceed the thermal limit. However, it did exceed in July 2007. In comparison, with thermal comfort level of metros all over the world, Tehran Metro stands in an acceptable condition, while the maximum capacity of air-conditioning systems was not used, if so the thermal comfort condition would be better

Assessment of gestational age based on ultrasonic femur length of fetus

The ultrasonic measurement of the fetal femur length is a sensitive and precise variable for estimation of fetal growth and development. The objective of this study was to predict gestational age in fetuses older than twenty-four weeks of gestation by ultrasonic measurement of the femur length. In this study, pregnant mothers were identified by the criteria of normality, such as well-known LMP, regular menstrual cycles, no use of oral contraceptive pills for the prior 3 months, no smoking, no history of diabetes. The relation between gestational age and fetal femur length was determined by cross-sectional analysis of 900 normal fetuses [>/= 25 weeks] using realtime ultrusonography. Mathematical modeling of the data demonstrated that the femur growth curve is always linear beyond 24 weeks of gestation. The following regression equation was derived: GA [week] = 5.2 FL [cm] + 2, SD +/- 5 days [Honarvar's Formula 2]. According to this data, the error in estimation of GA for given FL is less than 6 days. This equation appears to be clinically reliable and easy to use. Previous normal ultrasonic fetal femur length curves for other populations may underestimate or overestimate normal fetal age for Iranian population