Millar  R. H.; Scott  J. M. 《ICES Journal of Marine Science》1968,32(1):123-130

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Hunter  John R.; Mitchell  Charles T. 《ICES Journal of Marine Science》1968,31(3):427-434

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R. A. Scrutton 《Marine Geophysical Researches》1973,2(1):11-21

Gravity, magnetic and bathymetric data were collected over the continental margin of south-western Africa by H.M.S. Hecla in 1966. A study of the gravity measurements shows that the positive free-air anomalies of the continental edge effect are unusually large, and in excess of those calculated for an isostatic model of the Earth's crust. Taking into account the available seismic and magnetic evidence, a two-dimensional crustal model has been designed incorporating a body of relatively high density in the upper crust to account for the unusually large values.  相似文献   

    

P. A. A. Laura  R. O. Grossi  L. Ercoli 《Ocean Engineering》1983,10(2):139

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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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  总被引：4，自引：4，他引：0  

Murawski  S. A.; Lange  A. M.; Sissenwine  M. P.; Mayo  R. K. 《ICES Journal of Marine Science》1983,41(1):13-27

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R.S. Langley 《Applied Ocean Research》1984,6(4):182-186

A starting point in the statistical analysis of the slow drift motions of moored offshore structures is the determination of the statistical distribution of the second order exciting forces. In the past^2,6 an exponential probability density function has been used, this being the limiting case as the incident seastate becomes infinitely narrow banded. In the present note the second order force distribution is found for a general seastate and a significant deviation from an exponential distribution is found for those seastates which are likely to occur in practice. The statistical theory is based on a heuristic approximation to the second order force, which is shown to be consistent with a frequently used frequency domain approximation which has been suggested by Newman.⁸ Although Roberts² has shown that for very lightly damped systems the response statistics are independent of those of the exciting force, the present results may have a significant effect on the response statistics for higher levels of damping.  相似文献   

    

R.A. Sonstegard  T.T. Chen 《Marine environmental research》1984,14(1-4)

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Sluczanowski  Philip R. 《ICES Journal of Marine Science》1984,41(3):211-225

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S.J Hawkins  R.G Hartnoll 《Marine environmental research》1983,9(3):131-181

The basic aim of this study was to record the changes in the communities on a moderately exposed rocky shore by a programme of repeated non-destructive sampling (‘monitoring’) and to determine the causes of these changes. Possible causative factors were investigated by the combined approach of analysing detailed sea-temperature and meteorological data for the period of the study and establishing manipulative field experiments.Fixed quadrats (2 m by 1 m) at three levels were visited at 6–8 weekly intervals for 30 months and the abundance and spatial pattern of major species assessed. In the ‘High’ quadrat the balance between Fucus spiralis and F. vesiculosus changed, and an outburst of ephemeral algae occurred following a decline in overall canopy cover. In the ‘Mid’ quadrat F. vesiculosus decreased considerably from its initial cover and virtually disappeared by the end of the study. In the ‘Low’ quadrat F. vesiculosus increased from being absent to comprising 20% of the canopy, whilst Semmibalanus (= Balanus) balanoides and ‘understorey’ algae decreased in cover. Actinia equina, Nucella lapillus and Patella vulgata showed marked changes in number at all levels where they occurred.Only certain of these changes could be attributed to the physical environment—most were biologically controlled. For example, manipulative experiments showed that the blooms of ephemeral algae and the decline of Patella in the high-shore quadrat, and the decline of Actinia in the mid-shore quadrat, were due to decreases in the fucoid canopy. These canopy changes were, in turn, the result of biological cycles which are characteristic of these communities. However, even with the support of manipulative experiments, it was not possible to account for (or predict) all of the observed natural changes. The extent of these fluctuations poses a serious obstacle to the recognition of any but very gross pollution-induced effects. The conclusion must be that the monitoring of rocky shores as a means of detecting and measuring pollution is likely to be an unproductive investment of time and resources.  相似文献