Abstract: A lighting control system for maintaining a predetermined light level in a lighting zone illuminated by both natural and artificial light includes a CPU connected to an electrical power source and to an electric light. The CPU directs a predetermined initial amount of current to the electric light when the electric light is activated. The system includes a sensor for sensing the light level within the lighting zone and communicating the sensed level to the CPU. Following a comparison of the sensed light level with a predetermined light level, the CPU either increases or decreases the amount of current to the electric light for maintaining the predetermined light level. A thyristor connected to the CPU blocks and releases current flowing to the electric light for gradual power changes. Present light level sensing and current adjustments continue while the electric light is activated.

Abstract: A phased-beam transducer is disclosed for transmitting and receiving steered acoustic beam signals that includes a sheet of piezoelectric material such as Polyvinylidene Fluoride (PVDF), a copolymer, piezo-rubber, quartz, 1-3 PZT composite, or similar transducer material. The transducer includes specially designed electrode on each side of the piezoelectric sheet. The transducer is a two channel device with a sine channel, cosine channel and a ground lead. A summing circuit is used to sum the sine and cosine channels with a 90 .degree. phase shift applied by a phase shift circuit to one of the two channels, for example, the sine channel. The transducer is designed to form a predetermined steered beam at a particular frequency. If a different sound wave frequencies are used, the transducer will form useful directional beams with different steer angles and beamwidths. Variable sector coverage is achieved by forming beams at different frequencies.

Abstract: In an oil field tubular assembly, a flapper valve permitting downward flow and blocking upward flow is closed by down-hole pressure. A pivotally mounted flapper is urged to the closed position by a spring force, which may be moderated approaching the open position to reduce flow resistance, and an offset valve inlet passage provides clearance for flapper opening and room for the pivotal mounting.

Abstract: A forward look sonar system in which speed and direction of a sonar platform is obtained. Each acoustic transmission towards the target area over which the platform is traveling is comprised of a plurality of frequencies. A plurality of receiver beams is formed and each individual beam from one transmission is cross-correlated with its corresponding beam from a selected subsequent transmission to derive a delay value. The later received signal for each beam, for each frequency is divided into a plurality of small segments each of which is cross-correlated with a portion of the first return signal corresponding to the same frequency and beam. The cross-correlation functions for the plurality of frequencies for each particular segment are added together to obtain a more precise delay value. The correlation functions for each of the beams are added together and compared to derive a value for platform direction in the intercomparison period and the delay values are utilized to derive a velocity indication.