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941.
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S. Grimaud G. Boillot B.J. Collette A. Mauffret P.R. Miles D.B. Roberts 《Marine Geology》1983,53(3):238-239
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Personal thermal insulation by means of neoprene from wet suits provides adequate temporary control of body heat loss only at the shallow end of the air diving depth range, but it constitutes by far the most popular approach to diver thermal support. Howewer, compression of the trapped gas phase in neoprene foam seriously reduces its insulation performance on exposure to high ambient pressure. With conventional wet suits equipped with heating, the necessary level of power required at depths greater than about 30 m is too high, and also unsafe without the back up that increased insulation would provide. One approach to the goal of depth-insensitive insulation is to use a wet suit with a continuous internal gas space pressurized nominally to ambient pressure, so that its thickness remains substantially constant at all depths. The composite material properties required are: outer skins that are tough, flexible and free of pin holes; an open foam internal structure capable of resisting, without significant dimensional change, the relatively small pressure changes that occur over the height of a man; and a high bond strength.Samples of a composite material that meets these requirements have been developed, and a prototype suit has been successfully fabricated by conventional techniques. 相似文献
947.
A simple and effective method of heating divers in extreme cold water has been developed. The local heating concept utilizes a uniformly distributed granular mixture of magnesium and iron particles packed in small sachets. Upon activation by sea water, the two metal mixture behaves as a multitude of short-circuited electrolytic cells, producing thermal energy rather than electrical energy. The 45 mm-square sachets may be placed where heating is required on the diver's body, thus giving rise to the term “local heating”, obviously, the heating system requires no pumping device, or distribution network. Heating rate and duration of output of the sachets are controlled by particle size, and mixture ratio of the constituent Mg and Fe particles.This paper described the development, testing and performance of the heating sachets. Results of live tests in different dive situations are also presented and discussed. 相似文献
948.
The BIO Mark 8 thrust anemometer measures the drag of the wind on a perforated table tennis ball mounted on a vertical beam. The tri-axial displacement of the beam is sensed by eddy current proximity sensors. This anemometer has a flat frequency response from 0 to 10 Hz and can measure wind from 0 to 28 m s−1 at temperature from − 19 to + 28°C. It is designed for remote operation for extended periods of time such as on stable towers at sea. 相似文献
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The Maracaibo Estuary is of particular interest because of its location in the tropics, its large size (over 12,000 km2), the economic importance of its underlying hydrocarbon deposits and its increasing rate of pollution. Sediments from this estuary were studied in order to characterise their capacity to adsorb and desorb phosphorus. Considerable variability in capacity for phosphate sorption was found among the seventeen samples studied. This variability can be attributed first to the differences among the samples in total P content and, secondly, to their differences in free iron content. Also, it appears that P retention contributes to the control of P concentration in the water and therefore the sediments serve as a buffer in controlling P eutrophication in the estuary. 相似文献