Abstract: A flue-gas to air heat exchanger having a flue-gas containing shell with a heat exchange surface, flue-gas inlet and outlet sections, and at least one tubular clean-out fitting is provided with a removable plug having an outer peripheral portion resiliently engageable with a section of the inner peripheral portion of the fitting adjacent the shell. The plug periphery is expanded into gas-tight sealing contact with the fitting inner periphery by means affording installation and removal without tools.

Abstract: A method and system is disclosed of characterizing an optical amplifier for operation with a required tilt or curvature within predetermined limits. As the temperature of the erbium-doped optical amplifier is varied while a test signal is launched into the amplifier accompanied by a pump signal the output spectrum is compared with a desired spectrum. At different temperatures different measures of tilt or curvature are present at the output port of the amplifier in the presence of an input signal at the input port. Feedback related to the measure of tilt or curvature of at least one of the plurality of different temperatures is provided in the form of a feedback signal or an information signal.

Abstract: A child safety harness is provided having a waistband, a backpiece, a pair of shoulder straps and a tether. The shoulder straps are secured at one end to the waistband and at the opposite end to the backpiece. When fitting the safety harness on a child the waistband is extended around the waist so that its free ends are behind the child. The shoulder straps are pulled over the shoulders and downwardly across the back so that the back piece is in alignment with the waistband. The free ends of the waistband can then be releasably secured to the backpiece effectively securing the child safety harness on the child.