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991.
This environmental overview of Eckernförde Bay (northern Germany) summarizes the results of previous studies relevant to the Office of Naval Research's Coastal Benthic Boundary Layer (CBBL) Baltic field exercise conducted during 1993–1994. Significant environmental characteristics include the following: (1) surface sediment distribution is related to water depth, dictated primarily by hydrodynamic reworking of older glacial deposits; (2) the origin and characteristics of small-scale sedimentary structures depend on storm-generated waves and currents; (3) the proximity of the sea surface and sediment —water interface results in a pelagic—benthic coupling that drives biogeochemical processes and produces organicrich, acoustically turbid sediments; and (4) the bay floor is complicated topographically by pockmarks and manmade sedimentary structures.  相似文献   
992.
993.
Abstract. Ecology and Global Ecology (GE) are terms by which the relations between the organism (or living matter as a whole) and the environment (or Earth as a whole) have been treated for almost a century. Geophysiology and Parahistology (PH) are terms slowly replacing older scientific thoughts jointly with an increasing number of modifications and alterations of the Darwinian Evolution (DE) concept. Somehow Geophysiology and Parahistology seem to describe evolution in a non-Darwinian domain. According to V.I. Vernadsky (1929,1930,1988) - the great Russian naturalist and biogeochemist - the biogeochemical processes on Earth are controlled by the force of living matter rather than by species associations developing in and with individual ecosystems as expressed by darwinian evolutionary terms. He also claimed that Goethe was incorrectly regarded as a predecessor of DE by some authors (including Darwin) and that “Natur” (nature) and “Lebendige Natur” (the totality of creatures) are two very different things for Goethe. Detailed analyses of microbial mat systems in the German Wadden Sea and in artificial hypersaline WInogradsky columns have shown that the totality of creatures and matter around them i.e., the “lebendige Natur”sensu Goethe or “living matter”sensu Vernadsky of such environments control to a considerable extent the structure, stability. and (geo-)morphology of sediments and thereby the geological structure of the living Earth. These structures do not follow the rules of sedimentation formulated by the laws of Stokes They represent growth structures (Aufwuchs), whose physics and dynamics are controlled by complex fractal systems. The factors controlling the ultimate shape and stabilisation potential of the eventually resulting rocks and fossils are comparable to tissue development in macroorganisms. Also, certain microbial associations in the sub-recent and in the fossil record may be compared to metazoan tissues. Chemical gradients in the sedimentary column, regulated by the interplay of living matter and sluggish (slow-reactive to non-reactive) compounds, combine to create a pattern of porosity and structure of the resulting deposits that clearly indicates microbial influences and especially those of extracellular polymeric substances on the morphology and texture. The combined effects of microbiota or living matter on the sedimentary record are described as parahistology of sediments in analogy of the histology of tissue on a geological scale. This conceptual living tissue made up of microbially generated rocks and ore deposits cycled through metabolic processes and forced into tissue-like structures by microbial biofilms and mats may extend down to the upper mantle of Earth and far up into the stratosphere when Earth is regarded as a living entity over geological periods. We may have to conceive Earth as a living specimen, which is breathing at a frequency of thousands of years instead of the normal physiological breathing rate of man or an insect. Macroorganisms in all terrestrial systems represent the transport and logistic media, which, however, utterly depend on myriads of intra-, inter-, and extracellular microbial symbiotic partners.  相似文献   
994.
The trend of previous estimates of the world's ultimate recovery of oil suggests a figure of 1650 BBO, of which 1438 BBO have been discovered and 978 BBO remain to be produced. Some large reported reserve figures are questioned. Importance is attached to the mid-point of depletion when rising production tends to give way to decline. The share of the world's supply coming from six Middle East countries is set to continue to rise from its 1986 low of 16% to as much as 50% by 2010, with the likely consequence of higher oil prices and serious political implications. The world is rapidly approaching a turning point when it has to face the consequences of an irreversible decline in oil production.  相似文献   
995.
The plastic node method is reformulated by the variational principle and is applied to elasto-plastic finite element analysis of tubular joints, eventually including the effect of internal and external gussets, stiffener rings, etc., if necessary. Four different joints are studied here in detail for the elasto-plastic behavior, the strain at the hot spot, the strain concentration factor around the intersection line, and the propagation of the plastic region with loading up to collapse in order to determine the ultimate strength, safety factor, and development of the plastic field. The present results are in good agreement with the experimental results.  相似文献   
996.
997.
A study of the mineralogy of red clay sequences overlying basalt in the Bay of Biscay revealed two successive units: unit one (lower unit) indicates that clay minerals are the result of subaerial weathering of acid or basic continental rocks, occurring in the Galice province (northwest Spain); and unit two (upper unit) consists of fine-grained particles which suggest distinct volcanic activity. Clay materials from the first unit (Paleocene) are deposited in shallow environments, whereas the second unit materials (lower Eocene) Occur in deeper environments followed by neoformation of clay Minerals and concentration of chemical elements (cobalt, nickel, lead, zinc, and barium).  相似文献   
998.
999.
1000.
A statistical analysis of non-linear random waves   总被引:2,自引:0,他引:2  
A statistical analysis of unidirectional non-linear random waves is presented which is based on second-order random wave theory. The analysis technique is similar to a method which is available for the statistical analysis of a two-term Volterra series. It is shown that the statistical problem can be reduced to that of finding the eigenvalues and eigenvectors of two real symmetric matrices, from which the cumulants, the characteristic function, and the probability density function of the surface elevation can be found. Various numerical examples are considered, and the possibility of extending the technique to deal with spreading seas is discussed.  相似文献   
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