=+37. The article “Analysis of the Modeling Methodologies for Predicting the Strength of Air-Jet Spun Yarns” (Textile Res. J., 1997: 39–44) reported on a study carried out to relate yarn tenacity (y, in g/tex) to yarn count (x1, in tex), percentage polyester (x2), first nozzle pressure (x3, in kg/cm2

), and second nozzle pressure (x4, in kg/cm2