Experimental and Numerical Flow Simulation over Weirs     

Hriday Mani Kalita  Das  Rajdeep  Hajong  Atul  Kumar  Neeraj  Kharnaior  Donly  Dkhar  Heart Casingh 《Water Resources》2019,46(6):934-943

Water Resources - This paper reports a series of experimental studies done to simulate the flow behavior over crump and ogee type of weirs. The transition of subcritical to supercritical flow, as...  相似文献   

Assessment of the radiological hazards of sand sediments collected from streams and streamlets of the uranium deposit areas in West Khasi Hills District,Meghalaya, India     

S. A. War  P. Nongkynrih  D. T. Khathing  P. S. Iongwai  L. M. Dkhar 《Environmental Earth Sciences》2012,65(6):1695-1703

Primordial radionuclides in sand sediments that are often used as constructing materials are one of the sources of radiation hazard in dwellings. Activity concentrations of the primordial radionuclides of ⁴⁰K, ²²⁶Ra and ²³²Th have been measured in sand sediments collected from streams and streamlets lying within and around the uranium mineralization deposit blocks of Kylleng-Pyndensohiong, Mawthabah Areas of West Khasi Hills District, Meghalaya, India. The technique of gamma-ray spectroscopy using a NaI(Tl) detector with a PC-based multi channel analyser was applied for determination of the activity concentrations. The activity of the sand sediments obtained in this study ranges from 95.3 to 1,088.8 Bq kg⁻¹ for ⁴⁰K; 38.3 to 784.1 Bq kg⁻¹ for ²²⁶Ra and 78.0 to 316.1 Bq kg⁻¹ for ²³²Th. Sand sediments from two sampling locations lying within the mineralization zone show highest concentrations of these radionuclides. The radiological hazards of the sand sediments were calculated using various models given in the literature. The radium equivalent activity was found to be higher than the accepted standard criterion value of 370 Bq kg⁻¹ and the values of external and internal hazard indices were also found to be higher than unity in these two sampling locations. Besides these two sampling locations, a sampling location lying at a nearby distance from the mineralization zone also exhibits hazard indices values greater than unity.  相似文献