IDENTIFICATION OF NATURAL ATTENUATION OF TRICHLOROETHENE AND TECHNETIUM-99 ALONG LITTLE BAYOU CREEK, McCRACKEN COUNTY, KENTUCKY

Natural attenuation of trichloroethene (TCE) and technetium (99Tc) was studied for five consecutive seasons (from January 2002 to January 2003) in Little Bayou Creek. The stream receives ground water discharge from an aquifer contaminated by past waste disposal activities at the Paducah Gaseous Diffusion Plant (PGDP), a uranium enrichment facility near Paducah, Kentucky. Results from stream gaging, contaminant monitoring, tracer tests (with bromide, nitrate, rhodamine WT and propane) and simulation modeling indicate the TCE is naturally attenuated by volatilization and dilution, with volatilization rates related to the ambient temperature and surface discharge rate. The only apparent mechanism of 99Tc attenuation is dilution. Travel times of non-gaseous tracers were found to be similar and have highest values in October and lowest in June. It was also estimated from modeling that the transport of the solutes in the stream was mostly one-dimensional with insignificant secondary storage

DEEPER GROUNDWATER FLOW AND CHEMISTRY IN THE ARSENIC AFFECTED WESTERN BENGAL BASIN, WEST BENGAL, INDIA

Natural attenuation of trichloroethene (TCE) and technetium (99Tc) was studied for five consecutive seasons (from January 2002 to January 2003) in Little Bayou Creek. The stream receives ground water discharge from an aquifer contaminated by past waste disposal activities at the Paducah Gaseous Diffusion Plant (PGDP), a uranium enrichment facility near Paducah, Kentucky. Results from stream gaging, contaminant monitoring, tracer tests (with bromide, nitrate, rhodamine WT and propane) and simulation modeling indicate the TCE is naturally attenuated by volatilization and dilution, with volatilization rates related to the ambient temperature and surface discharge rate. The only apparent mechanism of 99Tc attenuation is dilution. Travel times of non-gaseous tracers were found to be similar and have highest values in October and lowest in June. It was also estimated from modeling that the transport of the solutes in the stream was mostly one-dimensional with insignificant secondary storage

Biogeography-based algorithm for high voltage electrode surface optimization of a single-phase GIS bus terminal

A new method applying the biogeography-based optimization (BBO) technique is presented for the optimization of high voltage electrode surfaces. The aim is to obtain the optimization of the electrode shape in order to achieve a uniform field distribution along the surface of the electrode and maintain maximum field stress at minimum value. The principle of the developed optimization technique is described with an axi-symmetric single-phase GIS bus terminal electrode considered as a quarter-ellipse. In this scheme different aspects of the optimization technique are compared by means of semi-infinite line charges and ring charges to compute the electric field with the charge simulation method (CSM). The new Biogeography Based optimized approach helps in achieving a uniform field distribution with a minimum electric stress on the electrode surface and a minimum deviation angle for the otherwise normal stress vector, holding the assignment factor within the assigned range. The deviation angle is the more sensitive indicator of the simulation accuracy .The assignment factor has an impact on simulation accuracy. The combined BBO/CSM algorithm is capable of finding a better-quality solution, better accuracy, better convergence characteristics and computational efficiency

Nonlinear differential polynomials sharing a small function

summary:Dealing with a question of Lahiri [6] we study the uniqueness problem of meromorphic functions concerning two nonlinear differential polynomials sharing a small function. Our results will not only improve and supplement the results of Lin-Yi [16], Lahiri Sarkar [12] but also improve and supplement a very recent result of the first author [1]