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  • Author or Editor: Daniel L. Wu x
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Daniel L. Wu

Abstract

The problem of determining the optimal detector sensitivity number and location of alarm detectors against instantaneous sources was examined in terms of the conventional Gaussian dispersion model for flat terrain. Analytical expressions for the effective detecting area per detector as a function of detector sensitivity were derived for a simple case. Numerical results were provided for general cases. The optimal number and location of alarm detectors were then interred from the effective detecting area per detector.

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Daniel L. Rudnick
,
Jeffrey T. Sherman
, and
Alexander P. Wu

Abstract

The depth-average velocity is routinely calculated using data from underwater gliders. The calculation is a dead reckoning, where the difference between the glider’s velocity over ground and its velocity through water yields the water velocity averaged over the glider’s dive path. Given the accuracy of global positioning system navigation and the typical 3–6-h dive cycle, the accuracy of the depth-average velocity is overwhelmingly dependent on the accurate estimation of the glider’s velocity through water. The calculation of glider velocity through water for the Spray underwater glider is described. The accuracy of this calculation is addressed using a method similar to that used with shipboard acoustic Doppler current profilers, where water velocity is compared before and after turns to determine a gain to apply to glider velocity through water. Differences of this gain from an ideal value of one are used to evaluate accuracy. Sustained glider observations of several years off California and Palau consisted of missions involving repeated straight sections, producing hundreds of turns. The root-mean-square accuracy of depth-average velocity is estimated to be in the range of 0.01–0.02 m s−1, consistent with inferences from the early days of underwater glider design.

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