The Oxides of Nitrogen and their It is assumed that nitrogen and small amounts of inert gases

monitor either acoustical or vibrational signals. The objective is to determine whether a sensed signal originated at one or another of several critical, monitored locations. The electronic processing means automatically determines the relative times of arrival and compares this pattern with stored patterns previously determined for each of the monitored sources. An alarm is triggered only if the order of arrival corresponds to a previously determined pattern. It is applicable to monitoring a nuclear reactor or components of such a structure.--CHA es. The pulse shapers release an audio-frequency band only when a desired threshold level is exceeded. High-frequency transmitters are modulated by the signals from the pulse shapers. Two high-frequency transmitters are used to send polarity information. The high-frequency signals are radiated from a coil placed adjacent to the skin, and are picked up by tuned coils in an implanted receiver unit. The signals from the coils are delivered to implanted electrodes after rectification to the appropriate polarity.--SFL 4,600,078 43.55. Rg SOUND BARRIER Leslie S. Wirt, assignor to Lockheed Corporation