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581.
试论会东大银厂铅锌矿找矿模式 总被引:2,自引:0,他引:2
对大银厂铅锌矿点分布区的地层、构造和成矿地质背景进行了论述,并与大梁子铅锌矿床作了对比,提出了寻找该类矿床的模式及找寻工业矿体最有希望的地段。找矿方法宜先化探后钻探。 相似文献
582.
An iterative inverse method, the sequential self-calibration method, is developed for mapping spatial distribution of a hydraulic
conductivity field by conditioning on nonreactive tracer breakthrough curves. A streamline-based, semi-analytical simulator
is adopted to simulate solute transport in a heterogeneous aquifer. The simulation is used as the forward modeling step. In
this study, the hydraulic conductivity is assumed to be a deterministic or random variable. Within the framework of the streamline-based
simulator, the efficient semi-analytical method is used to calculate sensitivity coefficients of the solute concentration
with respect to the hydraulic conductivity variation. The calculated sensitivities account for spatial correlations between
the solute concentration and parameters. The performance of the inverse method is assessed by two synthetic tracer tests conducted
in an aquifer with a distinct spatial pattern of heterogeneity. The study results indicate that the developed iterative inverse
method is able to identify and reproduce the large-scale heterogeneity pattern of the aquifer given appropriate observation
wells in these synthetic cases. 相似文献
583.
Modeling Trophic Structure and Energy Flows in a Coastal Artificial Ecosystem Using Mass-Balance Ecopath Model 总被引:1,自引:0,他引:1
Using a large-scale enclosed sea area in northern Hangzhou Bay as a case study, the trophic interactions, energy flows, and
ecosystem properties of a coastal artificial ecosystem were analyzed by ecotrophic modeling using Ecopath with Ecosim software
(EwE, 5.1 version). The model consists of 13 functional groups: piscivorous fish, benthic-feeding fish, zooplanktivorous fish,
herbivorous fish, crabs, shrimp, mollusca, infauna, carnivorous zooplankton, herbivorous zooplankton, macrophytes, phytoplankton,
and detritus. Input information for the model was gathered from published and unpublished reports and from our own estimates
during the period 2006–2007. Results show that the food web in the enclosed sea area was dominated by a detritus pathway.
The trophic levels of the groups varied from 1.00 for primary producers and detritus to 3.90 for piscivorous fish in the coastal
artificial system. Using network analysis, the system network was mapped into a linear food chain, and five discrete trophic
levels were found with a mean transfer efficiency of 9.8% from detritus and 9.4% from primary producer within the ecosystem.
The geometric mean of the trophic transfer efficiencies was 9.6%. Detritus contributed 57% of the total energy flux, and the
other 43% came from primary producers. The ecosystem maturity indices—total primary production/total respiration, Finn’s cycling
index, and ascendancy—were 2.56, 25.0%, and 31.0%, respectively, showing that the coastal artificial system is at developmental
stage according to Odum’s theory of ecosystem development. Generally, this is the first trophic model of a large-scale artificial
sea enclosure in China and provides some useful insights into the structure and functioning of the system. 相似文献
584.
Accumulation of heavy metals in wild commercial fish from the Baotou Urban Section of the Yellow River,China 总被引:1,自引:0,他引:1
In this work we studied the accumulation of heavy metals in nine species of fish with different life and feeding habitats
which are native and major commercial fish in the Baotou Urban Section of the Yellow River. The results showed that the concentration
of heavy metals was significantly dependent on fish species; the pollution index of heavy metals in different species were
ranked as Hemiculter leucisclus > Carassius auratus auratus > Hemibarbus maculatus > Megalobrama amblycephala > Abbottina rivularis > Cyprinus carpio > Squaliobarbus curriculus > Perccottus glehni > Saurogobio dabryi. Product–moment correlation coefficients among the metal pairs Pb–Zn, Cu–Cd, Cu–Zn, Cu–Pb, Pb–Cd, and Zn–Cd revealed there
was no competitions between metals in each tissue. Correlations between heavy metal concentrations and fish length or weight
indicated that accumulation of the heavy metals by the different fish species was related to their surrounding environments
and their life and feeding habitats. According to the mean bioconcentration factors (BCFs), the heavy metal concentrations
in these nine species were ranked Zn ≫ Cu > Cd ≈ Pb. In this work, the bioaccumulation factors (BAFs) were developed by using
the sum of exchangeable and bound-to-carbonate heavy metals as Cs values. It was found that BAFs better reveal the accumulation
characteristics of the heavy metals in the fish, which might provide an effective method for assessing bioaccumulation of
heavy metals. 相似文献
585.
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587.
地震和测井资料联合反演储层物性参数的方法 总被引:2,自引:0,他引:2
为了充分利用测井资料较高的纵向分辨率及其反映井壁周围物性直接准确的特点和地震资料良好的横向可追踪性,针对厚储层和薄储层地震—地质模型分别提出了利用测井和地震资料联合反演纵横波速度和密度参数的方法。理论模型的计算结果表明,反演方法是切实可行的 相似文献
588.
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590.
The dynamic responses of the Tsing Ma suspension bridge and the running behaviors of trains on the bridge under turbulent wind actions are analyzed by a three-dimensional wind-train-bridge interaction model. This model consists of a spatial finite element bridge model, a train model composed of eight 4-axle identical coaches of 27 degrees-of-freedom, and a turbulent wind model. The fluctuating wind forces, including the buffeting forces and the self-excited forces, act on the bridge only, since the train runs inside the bridge deck. The dynamic responses of the bridge are calculated and some results are compared with data measured from Typhoon York. The runnability of the train passing through the Tsing Ma suspension bridge at different speeds is researched under turbulent winds with different wind velocities. Then, the threshold curve of wind velocity for ensuring the running safety of the train in the bridge deck is proposed, from which the allowable train speed at different wind velocities can be determined. The numerical results show that rail traffic on the Tsing Ma suspension bridge should be closed as the mean wind velocity reaches 30 m/s. 相似文献