共查询到20条相似文献，搜索用时 31 毫秒
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Water Resources - The statistical homogeneity of the total inflow into Lake Baikal have been analyzed. The periods of 1901–1933 and 1933–2014 have been found not only to show... 相似文献
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A numerical study of the development and structure of the sea breeze in Mallorca is presented using a meso- numerical model. The model includes a detailed representation of the soil and vegetation processes. The study covers a diurnal cycle. The results show that the model reproduces the main known features of the circulation and new ones appear, which seem to have an appreciable effect on the circulation during the decay of the sea breeze. The orography and soil dryness have been identified as the main factors determining the structure of the breeze. Three more experiments have been performed in order to isolate the effect of each factor. 相似文献
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以水平裂缝分布的孔隙介质模型为基础,建立了水平裂缝面的平行裂缝分布和带粗糙表面的点接触裂缝模型,导出了两类裂缝模型的水平和垂直电阻率响应关系,分析了两类裂缝模型在没有围压和存在围压条件下的水平电阻率、垂直电阻率变化规律和电各向异性系数的变化特征.讨论了裂缝开度、裂缝密度和裂缝粗糙度等裂缝特征参数对裂缝性储层电各向异性的影响.为简化讨论,所有电性响应特征的分析都忽略了裂缝和孔隙表面的导电性和极化的影响.利用平行分布水平裂缝面模型和带粗糙面的裂缝模型,考察了围压条件下的裂缝性岩石的电各向异性响应特征,得到了对实际应用有意义的结果. 相似文献
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The Water Framework Directive, under the European Legislation, requires that all European waters, should reach a good ecological status by 2015. To achieve this goal, a phytoplankton monitoring network with monthly water samplings was established to evaluate the ecological quality, in the coastal waters of the Community of Valencia, and the collected data have allowed us to study the efficiency of the monthly campaigns of the monitoring network. With the results obtained in this research, we have designed a new monitoring strategy for the coastal waters of Valencia that for certain water bodies can mean lower sampling frequency. The new monitoring policy provides results as reliable as the previous strategy and allows a precise ecological classification of water bodies at a lower cost. The methodologies we have developed can be used in other monitoring networks and are not limited by geographic location or by the type of water body. 相似文献
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Petrological evolution of the Tertiary island arc in the Izu-Mariana region has been accompanied by the development of three different volcanic suites: 1) oceanridge basalt now exposed as the metamorphic basement on Yap; 2) island-arc tholeiites of Eocene to early Oligocene age characterized by low contents of incompatible elements at all levels of silica enrichment; and 3) calc-alkalic rocks of late Oligocene to early Miocene age showing higher contents of silica and incompatible elements. All these three suites have primitive, undifferentiated basalts or andesites (boninites) characterized by high Mg/Fe, Cr, and Ni, suggesting that they have been derived from an upper mantle peridotite at relatively high temperatures. The earliest volcanism appears to have occurred at a spreading ridge. Later, as subduction proceeded, the island-arc tholeiite magma may have been produced by the introduction of a smaller amount of water into the locus of fusion from the subducted oceanic crust. An increasingly larger amount of water introduced into the same region could have led to the development of the more siliceous, calc-alkalic magma, as represented typically by the boninite. 相似文献
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Water Resources - The published schemes of the net alongshore sediment transport near the eastern coast of Gdansk Bay have been systematized. Considerable discrepancies have been identified in the... 相似文献
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S. S. Starjinsky 《Geomagnetism and Aeronomy》2008,48(2):265-276
Results of studying the lunar daily geomagnetic variations in the spectral and time regions at the network of observatories are presented. The seasonal variations in the amplitudes of the fundamental harmonic constituents of three lunar variation components have been revealed. The seasonal time variations have been analyzed using the digital bandpass filtering and harmonic synthesis based on the data of the Kakioka and Memambetsu geomagnetic observatories. The 11-year solar cycle and annual and semiannual periods have been distinguished in the seasonal variation spectrum. Studying the spectral singularities of the lunar daily variation at these observatories and the sea level variations in daytime and nighttime hours has made it possible to identify the contribution of the oceanic dynamo to the lunar variation vertical component. 相似文献
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研究地质体的边缘位置是重、磁位场数据解释永恒的主题,也是其优势.最近几年,国内外利用重、磁位场进行地质体边缘识别研究的文章明显增多,但没有作者系统整理和对比各方法的优点和缺点,给使用者带来诸多不便.本文首先将现有重、磁位场边缘识别方法分为数理统计、数值计算和其他三大类,并概述了各类方法的研究现状;之后较详细总结了数值计算类中垂向导数、总水平导数、解析信号振幅、倾斜角、θ图这5种基本的边缘识别方法以及在这些基本方法之上发展起来的诸如倾斜角总水平导数、增强解析信号振幅等方法的研究历史和应用效果;并用理论模型对比了几种主要边缘识别方法的识别效果.通过以上总结、对比和分析,指出了重、磁位场边缘识别方法使用中需要注意的问题以及将来的研究重点及发展方向. 相似文献
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The orbits of two geodetic satellites, Starlette and Stella, have been analysed in order to determine ocean-tide parameters. The orbit of Starlette has been determined over a three-year period and Stella over a one-year period. Long-period analysis techniques have been used to determine the evolutions of the orbital inclination, eccentricity and right ascension of the ascending node for each satellite due to ocean tides. The ocean-tide parameters have been determined in a simultaneous fitting of the theoretical orbital variations to the observed variations. The results are compared with ocean-tide models. 相似文献
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Abstract We have used techniques of nonlinear dynamics to compare a special model for the reversals of the Earth's magnetic field with the observational data. Although this model is rather simple, there is no essential difference to the data by means of well-known characteristics, such as correlation function and probability distribution. Applying methods of symbolic dynamics we have found that the considered model is not able to describe the dynamical properties of the observed process. These significant differences are expressed by algorithmic complexity and Renyi information. 相似文献
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Myrl E. Beck 《Earth and Planetary Science Letters》1975,26(2):263-268
The Twin Sisters Dunite Intrusion has a homogeneous remanent magnetization directed nearly due east and inclined about 60° below the horizontal. It was emplaced in the Early Tertiary as a solid intrusion, but probably was above its Curie temperature at the time and so became magnetized substantially in situ. If so, it must have undergone considerable tectonic disturbance subsequent to emplacement and magnetization, including an important component of clockwise rotation. Examination of paleomagnetic data for the westernmost Cordillera shows that an abnormal number of rock bodies have discordant directions of remanent magnetization, mostly clockwise rotations of declination, flattened inclinations, or both. This sense of discordance in turn suggests that the western margin of the North American plate may have been deformed intermittently by right-lateral shear for at least some few tens of millions of years. 相似文献
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N. A. Barkhatov S. E. Revunov G. G. Vertogradov V. G. Vertogradov V. A. Valov V. P. Uryadov 《Geomagnetism and Aeronomy》2006,46(1):84-93
The algorithm for predicting one of the main parameters of the ionospheric HF radio channel—maximum observed frequency (MOF)—for the interval 0.5–3 h has been synthesized based on the technology of artificial neural networks (ANNs). The data of oblique-incidence LFM sounding obtained on the Inskip (England)-Rostov-on-Don path have been used for this purpose. The studies have been performed under different geophysical conditions. The relation of MOF to the variations in the key parameters of the solar wind and IMF, responsible for the succession of development of magnetospheric-ionospheric disturbances leading to a change in the HF radiocommunication conditions, has been established. The time scales of the ionospheric response have been determined. The practical value of the performed work consists in that the obtained results are used to increase the reliability of ionospheric HF radiocommunication. 相似文献
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The geodynamic interpretation of the results of GPS observations among the permanently operating stations which establish the frame for defining and conserving the coordinate system and simultaneously for describing the fundamental tendencies of dynamics in the area represented by them, should be deprived of the effects of geodynamic phenomena, which can be either periodic or short-term (even non-periodic) so that secular changes may be found. Some of these influences are included in scientific processing software, others have to be modelled later. The purpose of this project is to determine the influences of the indirect effect of ocean tides and the direct deformational effect of the atmosphere on the results of GPS observations, performed at stations Pecný (Czech Republic), Wettzell (FRG) and Graz (Austria), and also for the GPS stations of the Central Europe Regional Geodynamic Project (CERGOP) in the region of Central and East Europe. On the basis of analyses and results it is possible to claim that at the present accuracy of GPS observations the influence of ocean loading and atmospheric pressure effects for geodynamic campaigns in the region of the Czech Republic is negligible. For campaigns in larger regions (i.e. Central Europe) atmospheric corrections will have to be applied to height differences. These corrections, however, due to their periodicity have negligible influence on secular changes. 相似文献
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The features of fracturing and dissolving of Yunnan marble in distilled water near the critical temperature have been studied
experimentally. The results indicate that the mechanical parameters of the samples (fracture strength, Young’s Modulus, shear
fracture energy and fracture toughness) drop with the temperature of the environment water, near the critical temperature
(380°C), these parameters have sudden changes (drop), then keep stable values roughly. The contents of some chemical materials
in the water, PH value and conductivity at every experiment temperature have been analysed and measured. At 380°C, there all
exist sudden changes. According to the results, it is pointed out that the sudden changes are related to strong stress corrosion
of water near its critical temperature to the rock and the exist and its migration of the water solution near the critical
temperature in the crust have important significance to the earthquake source process, the formation cause of the low-focal
depth earthquakes in the crust.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 156–163, 1992.
This work was sponsored by the Chinese Joint Seismological Science Foundation. 相似文献
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在数据完整率达到95%的基础上,为进一步确保中国大陆构造环境监测网络GNSS基准站观测数据质量,选取2010—2020年全国基准站观测数据,采用TEQC软件进行质量检验,分类整理其中多路径效应计算结果呈典型特征的台站,结合观测环境状态,对多路径效应存在的区域性特征进行分析,发现除接收机天线周围发生遮挡外,硬件更换、台站周围地势差等因素,均对多路径效应产生不同程度的影响,可为建站选址和观测环境监测工作提供参考。 相似文献
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We have developed a new computer graphic technique to use in reconstructing plate tectonic evolution and to make movies illustrating this evolution. Using this technique, we have deciphered the evolutionary history of the Juan de Fuca area in the northeast Pacific, and show that a combination of seafloor spreading and rift propagation can explain this seemingly complex area as a simple consequence of the interaction of two rigid plates. 相似文献