A mechanism for guiding a windrower while making an initial swath pass in a multi-pass windrow merging operation in a manner to establish the lateral spacing between an end of the header and the adjacent edge of the uncut crop so that the header encounters an optimal width of standing crop in a subsequent swath pass. In one aspect, a non-parametric variable bandwidth mean shift technique, which is based on adaptive estimation of a normalized density gradient, is used for detecting one or more modes in the underlying data and clustering the underlying data. The catalyst of the present invention comprises one or more metal oxides, including at least vanadium oxide, and zirconia as a carrier. The user is permitted to adjust preferences related to a selected one or more of the goals. In the on-line detection system, reflectivity measuring means emits a laser beam onto a moving steel strip and continuously measuring the reflectivity of the laser beam returning from the surface of the steel strip, and signal processing means detects a weld of the steel strip based on change in the reflectivity measured on the weld. The package’s total transmission of the gas of interest is determined by adding its leakage and permeation components so determined.