Summary A method of propagating the components of the displacement across interfaces in a multi-layered spherical earth model is presented. It is useful both for explosion sources and tangential dislocation sources, buried in an arbitrary layer of the model. Combined with known techniques, our method yields a useful tool for generating synthetic seismograms for earthquake sources in realistic earth models. 相似文献
A methodology is presented for the economic analysis of investments in research, technology development and water resources conservation. The role of technology development and resource conservation is directly related to the availability of resources. Mathematically speaking, we are dealing with a problem in which part of the control variables are investments on technologies related to the manufacturing of diverse products. The methodology enables the decision maker to distribute efficiently restricted amounts of capital and resources to the different manufacturing systems so as to achieve the most profitable combination of production levels.Using the so called ‘technology function’, the solution procedure consists of a combination of decomposition and dynamic programming. Two specific technology functions are considered as examples and it is shown how analytical consideration can be incorporated in the solution procedure so as to reduce computational requirements.Possible extensions of the problem are also discussed. 相似文献
In this paper we present a detailed record of proxy-climatic events in the coastal belt of the eastern Mediterranean during the past 53,000 years. A sequence of alternating palaeosols, aeolianites, and dune sands, which have been dated by luminescence and by 14C, was studied by the magnetic susceptibility, particle-size distribution, clay mineralogy and soil micromorphology. Thirteen proxy-climatic events, demonstrating fluctuations of relatively dry and wet episodes, were recognized. The soil parent materials, as well as the different soil types, were rated in a semi-quantitative “dry” to “wet” scale. The palaeosol sequence is compared to a proxy-climatic record of oxygen and carbon isotopes in speleothems from a karstic cave in central Israel and to a record of lake levels of Lake Lisan and its successor, which is known as the Dead Sea. A genuine red Mediterranean Soil (Rhodoxeralfs), localy designated as “Hamra Soil” developed during the Last Glacial Stage, from 40 to 12.5 thousand calendar years BP. Climatic fluctuations that were recorded in speleothems and in changing lake levels were not preserved in this soil. During the cold and dry Younger Dryas, ca 12.5 to 11.5 calendar ka BP, a thick bed of loess material, deriving from atmospheric dust of the Sahara and Arabian deserts, covered the entire coastal belt. During this phase Lake Lisan was desiccated and turned into the modern, smaller Dead Sea. During the early Holocene, some 10–7.5 calendar ka BP, a second Red Hamra soil developed in warm and wet environments, associated with a relatively high stand of the Dead Sea level. A depletion of δ18O and a significant enrichment of δ13C in the speleothems were recorded during this episode. This event was in phase with the widespread distribution of freshwater lakes in the Sahara Desert and the accumulation of the S1 Sapropel in the eastern Mediterranean. Several small-scale dry and somewhat wet fluctuations of the Late Holocene, from 7.5 calendar ka BP to the present, were recorded in the coastal belt. Changes in human history, as reflected in archaeological records, are associated with proxy-climatic fluctuations. Periods of desertification and deterioration are coupled with dry episodes; periods of relative human prosperity are coupled with wetter episodes. 相似文献
Static displacements and strain fields are computed at the free surface of a gravitating radially-heterogeneous earth model. The numerical results indicate that the fields corresponding to a real earth model differ meaningly with comparison to a homogeneous non-gravitating model.The theory is applied to the Alaskan earthquake of March 28, 1964. The strains recorded at Isabella agree with the calculated values; but those at Kippapa and Green Observatory are larger than the theoretical values. In all cases the observed and calculated values are of the same order of magnitude. 相似文献
A model for the pathway of some trace elements during fluidized-bed combustion of israeli oil shale is suggested, based both
on pilot plant and laboratory tests. This model demonstrates the role of carbonate matrix in suppressing the volatilization
of trace elements due to fixation of most elements in new-formed silicates. The quality of leachates derived from oil shale
combustion wastes can be predicted on the basis of the proposed model. 相似文献
The Dead Sea rift is considered to be a plate boundary of the transform type. Several key questions regarding its structure and evolution are: Does sea floor spreading activity propagate from the Red Sea into the Dead Sea rift? Did rifting activity start simultaneously along the entire length of the Dead Sea rift, or did it propagate from several centres? Why did the initial propagation of the Red Sea into the Gulf of Suez stop and an opening of the Gulf of Elat start?
Using crustal structure data from north Africa and the eastern Mediterranean and approximating the deformation of the lithosphere by a deformation of a multilayer thin sheet that overlies an inviscid half-space, the regional stress field in this region was calculated. Using this approach it is possible to take into account variations of lithospheric thickness and the transition from a continental to an oceanic crust. By application of a strain-dependent visco-elastic model of a solid with damage it is possible to describe the process of creation and evolution of narrow zones of strain rate localization, corresponding to the high value of the damage parameter i.e. fault zones.
Mathematical simulation of the plate motion and faulting process suggests that the Dead Sea rift was created as a result of a simultaneous propagation of two different transforms. One propagated from the Red Sea through the Gulf of Elat to the north. The other transform started at the collision zone in Turkey and propagated to the south. 相似文献