A tide station at which continuous observations have been made over a minimum period of 30 days but less than 1 year. The series is reduced by comparison with simultaneous observations from a secondary control tide station. This station provides for a 29-day harmonic analysis.
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ADJUSTABLE DIFFERENTIAL
A means of changing the difference between the control cut-in and cut-out points.
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ACTION
Refers to the action of a controller. It defines what is done to regulate the final control element to effect control.
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SHED MODE
A method of demand control that reduces kW demand through shedding and restoring loads.
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HALF-TIDE BASIN
A lock of very large size and usually of irregular shape, the gates of which are kept open for several hours after high tide so that vessels may enter as long as there is sufficient depth over the sill. Vessels remain in the half-tide basin until the ensuing flood tide before they may pass through the gate to the inner harbor. If entry to the inner harbor is required before this time, water must be admitted to the half-tide basin from some external source.
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HARMONIC FUNCTION
Any real function that satisfies a certain equation. In its simplest form, as used in tide and tidal current predictions, it is a quantity that varies as the cosine of an angle that increases uniformly with time
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HARMONIC CONSTANTS
The amplitudes and epochs of the harmonic constituents of the tide or tidal current at any place
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HIGH WATER
The maximum height reached by a rising tide. The height may be due solely to the periodic tidal forces or it may have super- imposed upon it the effects of prevailing meteorological condi- tions. Use of the synonymous term HIGH TIDE is discouraged.
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HALF-TIDE LEVEL
A tidal datum midway between mean high water and mean low water. Mean sea level may coincide with half-tide level, but seldom does; the variation is generally about 3 centimeters and rarely exceeds 6 centimeters. Also called MEAN TIDE LEVEL.
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DOGWATCH
A short, evening period of watch duty on a ship
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ANTI-OXIDANT
Additive that prolongs the induction period of a base oil in the presence of oxidizing conditions and catalyst metals at elevated temperatures. The additive is consumed and degradation products increase not only with increasing and sustained temperature, but also with increases in mechanical agitation or turbulence and contamination: air, water, metallic particles, and dust.
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