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31.
An important task in modern geostatistics is the assessment and quantification of resource and reserve uncertainty. This uncertainty
is valuable support information for many management decisions. Uncertainty at specific locations and uncertainty in the global
resource is of interest. There are many different methods to build models of uncertainty, including Kriging, Cokriging, and
Inverse Distance. Each method leads to different results. A method is proposed to combine local uncertainties predicted by
different models to obtain a combined measure of uncertainty that combines good features of each alternative. The new estimator
is the overlap of alternate conditional distributions. 相似文献
32.
Makoto Yamano Masataka Kinoshita Shusaku Goto 《International Journal of Earth Sciences》2008,97(2):345-352
Thirty-three new measurements on the seaward slope and outer rise of the Japan Trench along a parallel of 38°45′N revealed
the existence of high heat flow anomalies on the subducting Pacific plate, where the seafloor age is about 135 m.y.. The most
prominent anomaly with the highest value of 114 mW/m2 is associated with a small mound on the outer rise, which was reported to be a kind of mud volcano. On the seaward slope
of the trench, heat flow is variable: high (70–90 mW/m2) at some locations and normal for the seafloor age (about 50 mW/m2) at others. The spatial variation of heat flow may be related to development of normal faults and horst/graben structures
due to bending of the Pacific plate before subduction, with fluid flow along the fault zones enhancing the vertical heat transfer.
Possible heat sources of the high heat flow anomalies are intra-plate volcanism in the last several million years like that
discovered recently on the Pacific plate east of the Japan Trench. 相似文献
33.
Inversely-Mapped Analytical Solutions for Flow Patterns around and within Inclined Elliptic Inclusions in Fluid-Saturated Rocks 总被引:1,自引:0,他引:1
Chongbin Zhao Bruce E. Hobbs Alison Ord Shenglin Peng Liangming Liu 《Mathematical Geosciences》2008,40(2):179-197
In this paper, an inverse mapping is used to transform the previously-derived analytical solutions from a local elliptical
coordinate system into a conventional Cartesian coordinate system. This enables a complete set of exact analytical solutions
to be derived rigorously for the pore-fluid velocity, stream function, and excess pore-fluid pressure around and within buried
inclined elliptic inclusions in pore-fluid-saturated porous rocks. To maximize the application range of the derived analytical
solutions, the focal distance of an ellipse is used to represent the size of the ellipse, while the length ratio of the long
axis to the short one is used to represent the geometrical shape of the ellipse. Since the present analytical solutions are
expressed in a conventional Cartesian coordinate system, it is convenient to investigate, both qualitatively and quantitatively,
the distribution patterns of the pore-fluid flow and excess pressure around and within many different families of buried inclined
elliptic inclusions. The major advantage in using the present analytical solution is that they can be conveniently computed
in a global Cartesian coordinate system, which is widely used in many scientific and engineering computations. As an application
example, the present analytical solutions have been used to investigate how the dip angle of an inclined elliptic inclusion
affects the distribution patterns of the pore-fluid flow and excess pore-fluid pressure when the permeability ratio of the
elliptic inclusion is of finite but nonzero values. 相似文献
34.
这是中国青藏高原研究会理事长刘东生院士在该会青藏高原青年科技奖第一次颁奖大会(1996年3月6日)上的演讲。本文指出了当前青藏高原研究的方向,表达了对青年一代的殷切期望。征得作者同意,以飨读者。青藏高原青年科技奖获奖者是:丁林、王保海、方小敏、刘晓东、刘燕华、张春光、高锐、姚檀栋、彭敏、廖俊国。 相似文献
35.
Liu X-f 《International journal of population geography : IJPG》1997,3(1):15-29
"The humanitarian policy that the Canadian government implemented in response to the 1989 Tiananmen Square crackdown changed a migration system primarily based on personal networks into a brain drain. Post-Tiananmen mainland Chinese immigrants (MCIs) were better educated than those arriving in Canada previously. Among the post-Tiananmen MCIs, those who landed under the policy were better educated than those landing in other categories. The analysis suggests that post-Tiananmen MCIs represented a brain-drain rather than a refugee flow, that the humanitarian policy implicitly contained ideological and human capital concerns in addition to humanitarian concerns, and that Canada benefited from the policy by obtaining human capital as well as satisfying its humanitarian obligations and ideological aspirations." 相似文献
36.
We analyse conditions of the innermost portion of an accretion disk and establish a set of equations for this region. A stable innermost region may exist, which can probably explain the observed UV and X-ray spectra, avoiding the unstable emission. We then discuss the detailed radial structure of a disk around a black hole for typical AGN parameters and obtain different kinds of- relationships for different regions of a disk. On the basis of this, we discuss the stability. A new type of cycle is present, which we call a double S shaped cycle. In this cycle, the extent of accretion rate variability is much larger than that in dwarf nova cycles. This probably solves the problem of violent variability of AGN. In the meantime, the very high accretion rate at the hottest state in limit cycles in the unstable region may provide continuous injection of matter to the jet and power the relativistic motion of the jet. 相似文献
37.
38.
A local-scale model for temperature-dependence of water-retention curves may be applicable to large scales. Consideration of this temperature dependence is important for modeling unsaturated flow and transport in the subsurface in numerous cases. Although significant progress has been made in understanding and modeling this temperature effect, almost all the previous studies have been limited to small scales (on the order of several centimeters). Numerical experiments were used to investigate the possibility of extending a local-scale model for the temperature-dependence of water retention curves to large scales (on the order of meters). Temperature effects on large-scale hydraulic properties are of interest in many practical applications. Numerical experiment results indicate that the local-scale model can indeed be applicable to large-scale problems for special porous media with high air entry values. A typical porous medium of this kind is the porous tuff matrix in the unsaturated zone of Yucca Mountain, Nevada, the proposed geologic disposal site for national high-level nuclear wastes. Whether this finding can approximately hold for general cases needs to be investigated in future studies. 相似文献
39.
40.
L.J. Hou M. Liu J.J. Lu S.Y. Xu D.N. Ou Y. Yang D.G. Zheng 《Environmental Geology》2006,49(7):937-945
The influences of exposure to the atmosphere on ammonium cycle in the intertidal surface sediments were in situ studied with
a geochemical approach at a typical station in the Yangtze Estuary during three tidal cycles in September 2003. During an
about 8-h emersion period of each diurnal tide, six high-resolution vertical profiles of adsorbed and dissolved ammonium were
measured. It was observed that both adsorbed and dissolved ammonium generally had an increasing trend in sediment cores during
the exposure. The rate of ammonium regeneration in sediments was estimated using the accumulation amount of ammonium including
adsorbed and soluble fractions during the daytime emersion. The calculation result showed that there was relatively high ammonification
rate (˜500 nmol N cm−3 day−1), which reflected that organic nitrogen in sediments was quickly decomposed with a residence time of ˜52.7 days. Due to the
dramatic temperature difference observed in sediment profiles, free convection was considered an important mechanism of regulating
the efflux of produced ammonium into overlying waters. The total estimated amount of regenerated ammonium was ˜1.35×105 t N year−1 in the intertidal flat of the Yangtze Estuary, which occupied 7.6% of the total inorganic nitrogen annually transported to
the estuarine ecosystem. 相似文献