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991.
Chen Tieyun Zhu Zhenghong
Professor Dept. of Naval Architecture Ocean Engineering Shanghai Jiao Tong University Shanghai Lecturer 《中国海洋工程》1991,(1)
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
992.
993.
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
994.
995.
996.
A statistical analysis of non-linear random waves 总被引:2,自引:0,他引:2
R. S. Langley 《Ocean Engineering》1987,14(5)
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
997.
998.
999.
We consider the problem of stable development of natural economical complexes from the viewpoint of basic balances in an ecological
economical system. We construct a basic dynamical model of the complex capable of predicting various scenarios of the industrial
development, consumption of natural resources, and pollution of the environment and propose a mechanism of control over the
process of development by introducing rent payments for the use of natural resources and ecological fines for the pollution
of the environment. The efficiency of the applied model is demonstrated by analysing the process of control over the concentration
of biological resources in marine media as an example. We describe the results of numerical experiments performed to show
the possibility of creation of the information technology of control over marine bioresources.
Translated by Peter V. Malyshev and Dmitry V. Malyshev 相似文献
1000.
A. J. O'Neill T. S. Galloway M. A. Browne A. Dissanayake M. H. Depledge 《Marine environmental research》2004,58(2-5):327
Increasing numbers of industrial, agricultural and natural chemicals are present in sewage effluent and are known to elicit toxic effects in laboratory exposures, but little is known of their combined sub-lethal effect in the field. In this study, a combination of esterase activity and ventilation rate assays was performed to determine the neurological and physiological function of the freshwater crustacean Asellus aquaticus (L.) at sites above and below a sewage treatment works (STW). Cholinesterase and carboxylesterase activities were significantly inhibited (n=8, P<0.05) and ventilation rates increased (n=8, P=0.0001) in A. aquaticus at STW sites compared to those from reference sites, indicating a decrease in neurological and physiological function. The ecological relevance of these findings for the population dynamics of the organisms in the field is discussed. 相似文献