A streamlined technique for obtaining interpolated color output values from corresponding color input values based on color output values stored in a color look-up table, with tetrahedral interpolation being applied so as to dissect each cubic grid of the color look-up table into plural tetrahedrons. The engine utilizes recovered methane gas and ventilation air methane gas from the coal mine by adjusting methane concentration to produce a lean air-methane gas mixture. The slot is configured to be welded closed, or the pinch blades are configured to weldingly secure the wire thereto. The frame classification and rate decision module comprises M sub-classifiers and a final decision module. The tool member may include a neck portion having the indicator device applied on the outer portion, and arranged for allowing the indicator device to be clearly seen by the users, such that the users may easily and quickly find and select or fetch the tool member having the required type andor the required size or dimension, without rummaging the tool boxes.