Abstract: A signal-to-noise ratio dependent adaptive spectral subtraction process eliminates noise from noise-corrupted speech signals. The process first pre-emphasizes the frequency components of the input sound signal which contain the consonant information in human speech. Next, a signal-to-noise ratio is determined and a spectral subtraction proportion adjusted appropriately. After spectral subtraction, low amplitude signals can be squelched. A single microphone is used to obtain both the noise-corrupted speech and the average noise estimate. This is done by determining if the frame of data being sampled is a voiced or unvoiced frame. During unvoiced frames an estimate of the noise is obtained. A running average of the noise is used to approximate the expected value of the noise. Spectral subtraction may be performed on a composite noise-corrupted signal, or upon individual sub-bands of the noise-corrupted signal.

Abstract: A means of attaching and supporting lagging that integrates attachment and support for both insulation and lagging. Angle irons are welded to the hot surface. Insulation pins are also welded to the hot surface at two different levels in a pattern that will support the insulation. The insulation is impaled on the insulation pins. A first subgirt is placed on the angle irons and welded at one end only to an angle iron. The insulation pins are received and extend through bores in the first subgirt. A second subgirt is received on insulation pins at a different level. A fastener is installed oil the end of each insulation pin to hold the subgirts against the outer surface of the insulation. The end of each pin is bent to retain the fasteners in place. The lagging panels are bolted to the subgirts.

Abstract: A gas cleaning filter is formed in-situ within a vessel containing a fluidizable bed of granular material of a relatively large size fraction. A filter membrane provided by a porous metal or ceramic body or such a body supported a perforated screen on one side thereof is coated in-situ with a layer of the granular material from the fluidized bed by serially passing a bed-fluidizing gas stream through the bed of granular material and the membrane. The layer of granular material provides the filtering medium for the combined membrane-granular layer filter. The filter is not blinded by the granular material and provides for the removal of virtually all of the particulates from a process gas stream. The granular material can be at least partially provided by a material capable of chemically reacting with and removing sulfur compounds from the process gas stream.