波西米亚块体西部长周期电磁研究(英文)   总被引：1，自引：0，他引：1       下载免费PDF全文

V.Cerv  J.Pek 《地震地质》2001,23(2):166-177

在波西米亚块体西南部做了一条长周期电磁剖面 ,它靠近德国超深钻的位置。用一个二维合成模型对数据做了大体的拟合 ,模型走向东西 ,近地表盖层高度地不均匀畸变。畸变层显示强烈的各向异性 ,优势电导方向为NW -SE至NNW -SSE。讨论了深部区域结构的几个不同的模型 ,其中一个模型可以解释由MT和GDS数据显示的主方向的偏差 ,还讨论了沿特别剖面得到的结果与区域地电结构的关系  相似文献   

On the meridional circulation and balance of momentum in the Southern Ocean of POP     

Dirk Olbers  Vladimir O. Ivchenko 《Ocean Dynamics》2001,52(2):79-93

 The circulation of the Southern Ocean is studied in the eddy-resolving model POP (Parallel Ocean Program) by an analysis of zonally integrated balances. The TEM formalism (Transformed Eulerian Mean) is extended to include topography and continental boundaries, thus deviations from a zonally integrated state involve transient and standing eddies. The meridional circulation is presented in terms of the Eulerian, eddy-induced, and residual streamfunctions. It is shown that the splitting of the meridional circulation into Ekman and geostrophic transports and the component induced by subgrid and Reynolds stresses is identical to a particular form of the zonally integrated balance of zonal momentum. In this balance, the eddy-induced streamfunctions represent the interfacial form stresses by transient and standing eddies and the residual streamfunction represents the acceleration of the zonal current by density fluxes in a zonally integrated frame. The latter acceleration term is directly related to the surface flux of density and interior fluxes due to the resolved and unresolved eddies. The eddy-induced circulation is extremely vigorous in POP. In the upper ocean a shallow circulation, reversed in comparison to the Deacon cell and mainly due to standing eddies, appears to the north of Drake Passage latitudes, and in the Drake Passage belt of latitudes a deep-reaching cell is induced by transient eddies. In the resulting residual circulation the Deacon cell is largely cancelled and the residual advection of the zonal mean potential density is balanced by diapycnal eddy and subgrid fluxes which are strong in the upper few hundred meters but small in the ocean interior. The balance of zonal momentum is consistent with other eddy-resolving models; a new aspect is the clear identification of density effects in the zonally integrated balance. We show that the wind stress and the stress induced by the residual circulation drive the eastward current, whereas both eddy species result in a braking. Finally, we extend the Johnson–Bryden model of zonal transport to incorporate all relevant terms from the zonal momentum balance. It is shown that wind stress and induction by the residual circulation carry an eastward transport while bottom form stress and the stress induced by standing eddies yield westward components of transport. Received: 26 June 2001 / Accepted: 2 November 2001  相似文献   

A fractal-multifractal approach to groundwater contamination. 2. Predicting conservative tracers at the Borden site     

C. E. Puente  O. Robayo  B. Sivakumar 《Stochastic Environmental Research and Risk Assessment (SERRA)》2001,15(5):372-383

 In a companion paper (Puente et al., this issue), the capability of a deterministic fractal-multifractal (FM) approach to faithfully and compactly describe the geometry of chloride and bromide tracers gathered at the Borden site was illustrated. As trends in surrogate parameter space were found for successive plume contours (i.e. linear growth in coordinates by which fractal interpolating functions pass, nearly constant rotations and fairly high scalings), this article reports usage of a variety of prediction schemes, based on linear regressions and the aforementioned trends, in order to study the evolving plumes. It is shown that the FM representation leads to plausible non-Gaussian plume evolutions and yields predictions that closely approximate records for a period of time that extends even beyond one year. It is illustrated that such predicted geometries are also consistent with predictions made via stochastic theories (i.e. Dagan, 1984).  相似文献   

A fractal-multifractal approach to groundwater contamination. 1. Modeling conservative tracers at the Borden site     

C. E. Puente  O. Robayo  M. C. Díaz  B. Sivakumar 《Stochastic Environmental Research and Risk Assessment (SERRA)》2001,15(5):357-371

  相似文献   

Evolutionary properties of stochastic models of earthquake accelerograms: Their dependence on magnitude and distance     

J. Alamilla  L. Esteva  J. García-Pérez  O. Díaz-López 《Journal of Seismology》2001,5(1):1-21

An approach to generate artificial earthquakeaccelerograms on hard soil sites is presented. Eachtime-history of accelerations is considered as arealization of a non-stationary gaussian stochasticprocess, with statistical parameters depending onmagnitude and source-to-site distance. In order tolink the values of these parameters for each groundmotion record with the corresponding magnitude andsource-to-site distance, semi-empirical functionalrelations called generalized attenuationfunctions are determined. The set of realground-motion time histories used to obtain thesefunctions correspond to shocks generated at differentsources and recorded at different sites in thevicinity of the southern coast of Mexico. The resultsshow significant dispersion in the parameters of themodel adopted, which reflect that associated with thereal earthquakes included in the sample employed.The problem of conditional simulation of artificialacceleration time histories for prescribed intensitiesis briefly presented, but its detailed study is leftfor a companion paper. The criteria and modelsproposed are applied to generate two families ofartificial acceleration records for recurrenceintervals of 100 and 200 years at a specific sitelocated in the region under study. The results shownin this article correspond to acceleration timehistories recorded on firm ground for earthquakesgenerated at the subduction zone that runs along thesouthern coast of Mexico, and cannot be generalized tocases of earthquakes generated at other sources orrecorded at other types of local conditions. Thismeans that the methods and functional forms presentedhere are applicable to these other cases, but thevalues of the parameters that characterize thosefunctions may differ from those presented here.  相似文献   

Model of Formation and Development of Spring Thermal Bar     

Blokhina  N. S.  Ordanovich  A. E.  Savel'eva  O. S. 《Water Resources》2001,28(2):201-204

A mathematical model simulating the thermo- and hydrodynamic processes near the thermal bar in the period of lake warming in spring is considered. A closed system of Reynolds type equations is constructed based on the Navier–Stokes nonlinear system of equations using the Boussinesq approximation and a special technique for isolating large-scale structures in turbulent medium. The turbulent viscosity coefficient is evaluated in the course of problem solution. The results of calculations are shown to agree well with field observation data.  相似文献   

Stochastic delineation of wellhead protection area in fractured aquifers and parametric sensitivity study   总被引：1，自引：0，他引：1  

S. Chevalier  M. A. Buès  J. Tournebize  O. Banton 《Stochastic Environmental Research and Risk Assessment (SERRA)》2001,15(3):205-227

 In many countries, the setup of protection areas around every drinking water well was instituted at a national level in order to preserve the quality of water as well as the perennially of the resource. Wellhead protection surfaces have been defined using capture zones showing the area influenced by a well within a certain time. A stochastic method is developed for delineating time-related capture zones in fractured aquifers characterised by a low porosity and a high degree of fracturing. The flow velocity within the fractures is determined statistically depending on the distribution of the fracture features and the mass transfer solution is obtained through a particle tracking algorithm. Probabilistic capture zone curves are obtained as a function of the travel time of particles to the well and the percentage of particles apt to be extracted up to this time. A sensitivity study of fracture network parameters leads to the conclusion that orientations and aperture distribution of the fracture sets are of primary importance to the wellhead protection delineation.  相似文献   

Diurnal Variations in the Hydrochemical Indices in Amur Bay     

Shevtsova  O. V. 《Water Resources》2001,28(6):666-677

A study was conducted to assess the diurnal variations in water temperature, in-situ density, and salinity; major components of the salt composition; ion–chlorine relationships; elements of the carbonate system and their chlorine ratios; major nutrient compounds; total organic carbon content; suspended matter; dissolved oxygen and its percentage in the coastal waters of Amur Bay. The notions of zero, very small, small, medium, high, and very high relative variability are introduced.  相似文献   

Climate induced temperature effects on growth performance, fecundity and recruitment in marine fish: developing a hypothesis for cause and effect relationships in Atlantic cod (Gadus morhua) and common eelpout (Zoarces viviparus)     

H. O. Prtner  B. Berdal  R. Blust  O. Brix  A. Colosimo  B. De Wachter  A. Giuliani  T. Johansen  T. Fischer  R. Knust  G. Lannig  G. Naevdal  A. Nedenes  G. Nyhammer  F. J. Sartoris  I. Serendero  P. Sirabella  S. Thorkildsen  M. Zakhartsev 《Continental Shelf Research》2001,21(18-19)

Effects of global warming on animal distribution and performance become visible in many marine ecosystems. The present study was designed to develop a concept for a cause and effect understanding with respect to temperature changes and to explain ecological findings based on physiological processes. The concept is based on a wide comparison of invertebrate and fish species with a special focus on recent data obtained in two model species of fish. These fish species are both characterized by northern and southern distribution limits in the North Atlantic: eelpout (Zoarces viviparus), as a typical non-migrating inhabitant of the coastal zone and the cod (Gadus morhua), as a typical inhabitant of the continental shelf with a high importance for fisheries.Mathematical modelling demonstrates a clear significant correlation between climate induced temperature fluctuations and the recruitment of cod stocks. Growth performance in cod is optimal at temperatures close to 10°C, regardless of the population investigated in a latitudinal cline. However, temperature specific growth rates decrease at higher latitudes. Also, fecundity is less in White Sea than in North and Baltic Sea cod or eelpout populations. These findings suggest that a cold-induced shift in energy budget occurs which is unfavorable for growth performance and fecundity. Thermal tolerance limits shift depending on latitude and are characterized by oxygen limitation at both low or high temperatures. Oxygen supply to tissues is optimized at low temperature by a shift in hemoglobin isoforms and oxygen binding properties to lower affinities and higher unloading potential. Protective stimulation of heat shock protein synthesis was not observed.According to a recent model of thermal tolerance the downward shift of tolerance limits during cold adaptation is associated with rising mitochondrial densities and, thus, aerobic capacity and performance in the cold, especially in eurythermal species. At the same time the costs of mitochondrial maintenance reflected by mitochondrial proton leakage should rise leaving a lower energy fraction for growth and reproduction. The preliminary conclusion can be drawn that warming will cause a northern shift of distribution limits for both species with a rise in growth performance and fecundity larger than expected from the Q₁₀ effect in the north and lower growth or even extinction of the species in the south. Such a shift may heavily affect fishing activities in the North Sea.  相似文献   

The dust envelope of the symbiotic nova V1016 Cyg     

M. B. Bogdanov  O. G. Taranova 《Astronomy Reports》2001,45(6):461-466

Brightness and color variations of V1016 Cyg are studied using many years of UBVRJHKLM photometric observations and information about its spectral energy distribution in the intermediate IR (7.7 to 22.7 µm) obtained with the IRAS and ISO low-resolution spectrometers. Models for its stationary, spherically symmetrical, extended dust envelope are computed for two cases of heating: by the radiation of the cool component only and by the combined radiation from both components. Model fitting of the IRAS and ISO observations shows that the model with a single central source—the Mira star—provides a better fit to the data, indicating that the hot component’s radiation is appreciably reprocessed by the ambient gas medium and has almost no direct influence on the IR spectrum of the symbiotic nova. The mean spectral energy distributions measured by IRAS in 1983 and ISO on October 1, 1996, differ considerably. The observed evolution of the envelope’s spectrum probably reflects an increasing grain concentration and decreasing grain temperature at the inner edge of the envelope, associated with decreased luminosity and increased temperature of the hot component. The total mass-loss rate, gas-expansion velocity at the outer edge of the envelope, and upper limit to the mass of the central radiation source are estimated.  相似文献