Daily coal mining as a factor influencing methane concentration at a longwall - a case study

This paper describes an exemplary method of presenting the average concentration of methane at the outlet of one of walls in the "Krupinski" mine. This method involves the linear function of current mining and mining on preceding days. The ordinary least squares method used to determine parameters of that function was found to produce too serious errors. Therefore, it is recommended to use one of generalised least squares method. In this case Cochrane-Orcutt estimation for the generalised least squares method was applied. Measured and approximated values of methane concentration showed good compliance. Also, parameters of the approximation function for the average concentration of methane was determined. It was a linear function of the square root of mining on the current day and the preceding days. For that purpose, Cochrane-Orcutt procedure was also applied. Results from approximation by mentioned functions were nearly identical.