Abstract: Denier and other optically transmissivity-dependent parameters of yarn are monitored on-line and in real-time with a preferably microprocessor-controlled high frequency modulated-demodulated optically-based system. An LED is spaced-apart from an array of preferably identical photodetector ("PD") diodes that will track one another, with the yarn spaced between one of the PDs. The LED outputs preferably collimated light in response to a periodic LED drive signal, and yarn characteristics will affect light received by at least one PD in the array. An output signal from a first PD is fedback to the LED driver to continuously compensate the system against dust or other factors affect LED transmission and PD light reception. An output signal from a second PD is coupled to a fraction of the drive signal so as to enhance dynamic range. This signal is amplified and AC-coupled to a sample and hold that samples during a stable active portion of the LED drive signal to demodulate the relevant signal.

Abstract: A tube expanding apparatus and method are disclosed utilizing a hollow, elastic, tubular bladder, an elongate connection member positioned within the bladder, a pair of end caps sealably connecting the bladder to the elongate member and forming an annular chamber between the bladder and elongate member in between the end caps, and means for providing fluid communication to the chamber for expanding the bladder against a tubular member. The connection member is disclosed as either a rigid tie rod or an axially inextendible, flexible member. The tie rod has reduced diameter portions adjacent each end forming shoulders and threaded portions at the end thereof for threadibly connecting the end caps thereon and clamping the bladder against the shoulders. An engagement means can be provided at one end of the connection member for urging the tubular member toward the opposite end of the connection member.