共查询到20条相似文献，搜索用时 281 毫秒
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Sergio E. Serrano 《水文科学杂志》2013,58(1):177-205
Abstract Mathematical models are the means to characterize variables quantitatively in many groundwater problems. Recent advances in applied mathematics have perfected what is now called Adomian's decomposition method (ADM), a simple modelling procedure for practical applications. Decomposition exhibits the benefits of analytical solutions (i.e. stability, analytic derivation of heads, gradients, fluxes and simple programming). It also offers the advantages of traditional numerical methods (i.e. consideration of heterogeneity, irregular domain shapes and multiple dimensions). In addition, decomposition is one of the few systematic procedures for solving nonlinear equations. By far its greatest advantage is its simplicity of application. It may produce simple results for preliminary simulations, or in cases with scarce information. The method is described with simple applications to regional groundwater flow. Many applications in groundwater flow and contaminant transport are available in the literature. Editor D. Koutsoyiannis; Associate editor Xi Chen Citation Serrano, S.E., 2013. A simple approach to groundwater modelling with decomposition. Hydrological Sciences Journal, 58 (1), 1–9. 相似文献
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M. A. BENSON 《水文科学杂志》2013,58(3):5-6
Abstract This study was made to define the relation between floods in a humid region and the causative factors that account for their variability. The study covered the basic relationships between peak discharges and hydrologic factors as well as the practical working methods for generalizing the results on a regional basis. Statistical multiple-correlation techniques were applied to hydrologic data in New England. A field and library investigation of historical flood data extended the period of flood knowledge to as much as 300 years. The relation of many topographic and climatic factors to flood peaks was tested. Flood peaks with recurrence intervals at 9 levels, from 1.2 to 300 years, were related to 6 independent variables, 3 of which are topographic, 2 climatic, and 1 orographic. 相似文献
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H. G. WILM 《水文科学杂志》2013,58(2):5-16
Synopsis A method of synthesis has been used to combine the variables characterising sediment transport in laboratory flumes into nondimensional functional equations. These equations are used to provide a basis for logical data correlations. By selecting appropriate nondimensional groups the effect of variation of individual variables such as flume width, sediment grain size, etc., can be determined. It has been found that work of this nature is hampered by the small amount of data available from rational experimentation. Much of the published data is unsuitable for direct use in correlations but may be of use in the future once the trend of results has been predicted by more limited but more basic data. When sufficient data for the transport of light weight materials is available correlations of the type presented may provide a secure basis for the choice of bed material for hydraulic models. 相似文献
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黄国忠 《地震地磁观测与研究》1985,(1)
G.S.I—等磁力仪是日本进口的用来精密测量地磁偏角D和倾角I的测磁仪器。放大器的输出端接上一个压电晶体耳机用来监测信号。由于某些原因造成晶体性能变差或损坏,观测时声小或无声,而本耳机为专用无磁性耳机,原机无备件,市场上难于购买,一旦损坏观测就得被迫停止。耳机的好坏可用万用表作简单的检查,从仪器上拔下耳机插头,用500型万用表×10KΩ档测量阻值应在1MΩ以上;表针一点不动可能是连接线断或插头和耳机有脱焊;如果阻值偏 相似文献
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Charles W. CARLSTON 《水文科学杂志》2013,58(3):62-84
ABSTRACT Sir Charles Cotton (1964) has pointed out that in an earlier paper (Carlston, 1963) which related drainage density to hydrology, there was insufficient emphasis on the role of climate in its effect on drainage density. Re-examination of the relation of drainage density to base flow in the 15 basins originally described has revealed additional evidence that base flow is affected by precipitation or recharge (a climatic variable), while varying inversely with drainage density. Within the climatic region studied in the earlier paper (the Humid Subtropical Climate of the eastern U. S.), no evidence could be found that amount or intensity of rainfall affected the intensity of flood runoff or the scale of drainage density. In comparison with other climates, however, such as the Marine West Coast Climate, it is possible that the less intense precipitation of a marine climate may result in lower runoff intensities and lower drainage densities, however the lower mean temperatures of such climates may develop soils of generally higher infiltration capacity which would produce lower drainage densities. A progressive increase in aridity results in a decrease in soil and vegetal cover which greatly magnifies the range of drainage densities characteristic of semi-arid regions. In such regions, where the land sur-face has a good infiltration capacity rainfall sinks readily into the dry soil (although recharge to ground water may be negligible), and runoff is virtually zero, as is drainage density, Impermeable terranes devoid of vegetal and soil cover reject the rain, runoff is briefly total and drainage density may be greatly magnified, as in the South Dakota Badlands, where drainage density runs into the hundreds. Arid or Desert Climates should produce erosional landforms with generally high drainage densities, though not reaching the magnitudes of drainage density found in the semi-arid badlands where rainfall intensities are much higher. 相似文献
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ANDRÉ RENAUD 《水文科学杂志》2013,58(2):109-116
Abstract The authors give data of water infiltrations in horizontal and vertical columns, and in a two dimensional model. The soils are two mixtures of sand and loam, and a natural sandy loam. The characteristics of these soils are given in the article. As a conclusion, the two dimensional problem can be approached by a linear combination of data in horizontal and vertical columns. 相似文献
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本文讨论了Ｔｓｅｌｅｎｔｉｓ和Ｍｅｌｉｓ（１９９６）提出的震中位置容限依赖于震级这一引起人们兴趣的建议 。 相似文献
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G. Böhnecke 《Ocean Dynamics》1957,10(5):202-203
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《Continental Shelf Research》1990,10(5):397-428
Bottom stress is calculated for several long-term time-series observations, made on the U.S. east coast continental shelf during winter, using the wave-current interaction and moveable bed models of Grant and Madsen (1979, Journal of Geophysical Research, 84, 1797–1808; 1982, Journal of Geophysical Research, 87, 469–482). The wave and current measurements were obtained by means of a bottom tripod system which measured current using a Savonius rotor and vane and waves by means of a pressure sensor. The variables were burst sampled about 10% of the time. Wave energy was reasonably resolved, although aliased by wave groupiness, and wave period was accurate to 1–2 s during large storms. Errors in current speed and direction depend on the speed of the mean current relative to the wave current. In general, errors in bottom stress caused by uncertainties in measured current speed and wave characteristics were 10–20%.During storms, the bottom stress calculated using the Grant-Madsen models exceeded stress computed from conventional drag laws by a factor of about 1.5 on average and 3 or more during storm peaks. Thus, even in water as deep as 80 m, oscillatory near-bottom currents associated with surface gravity waves of period 12 s or longer will contribute substantially to bottom stress. Given that the Grant-Madsen model is correct, parameterizations of bottom stress that do not incorporate wave effects will substantially underestimate stress and sediment transport in this region of the continental shelf. 相似文献
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Bruce W.MELVILLE 《国际泥沙研究》2002,(4)
1 FLOW INTENSITY, PF Local scour processes differ between clear-water (sub-threshold) and live-bed (post-threshold) conditions of sediment transport on the channel bed ahead of the bridge abutment. As described by Melville and Coleman (2000), the stage of sediment transport can be represented by the mean velocity ratio U/Uc, termed the flow intensity. For U/Uc 1, clear-water conditions pertain, while live-bed scour occurs for U/Uc > 1. The variation of local scour depth at bridge … 相似文献
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J. C. SCHÖNFELD 《水文科学杂志》2013,58(1):11-22
Abstract The intrusion of seawater in a tidal river is treated as a diffusion problem, characterized by a coefficient of longitudinal diffusivity. In order to analyse the longitudinal diffusivity, a mathematical model is set up, consisting of two bodies of water, either one besides the other or one on top of the other. The two bodies are assumed to move relatively to each other, as a secondary effect of the tidal flow. It is moreover assumed that there is turbulent exchange of salt between the bodies. It is demonstrated that the diffusion of salt into the river is greatest for an optimum value of the coefficient of exchange between the two bodies. Exchange weaker or stronger than this optimum both diminish the salt intrusion. The theory is applied to the Rotterdam Waterway, for which estimates of the exchange are made. Estimation of the reduction of the turbulence by stratification and hence of the vertical exchange, shows that the observed strong intrusion is explainable. Intensified vertical mixing, for instance as provoked by compressed air, need not always result in less intrusion, and hence should be considered carefully. 相似文献
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亚美尼亚地震学和地球物理学协会(AASPE)主席、亚洲地震委员会(ASC)前任主席、亚美尼亚国立埃里温(Yerevan)大学Serguei Balassanian教授，2004年11月23日因车祸不幸遇难，享年57岁。 相似文献
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我感谢Forsyth等对南纬18°地震活动性质的澄清,同时我认为地震活动与厄尔尼诺之间的关系是不清楚的。我也相信偏离洋脊轴线的地震活动本身未必跟厄尔尼诺有直接关系,并相信由远震记录得到的发生于遥远洋脊系上的许多地震是一种不伴随火山活动、其震中没有热液成分的洋脊外地震。然而,远震记录到的异常地震活动事件在发生时间上似乎与厄尔尼诺有某种同步性。怎么会是这样的?沿着洋脊系异常高的地震活动水平往往伴生异常的 相似文献
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V. V. Shcherbakova G. V. Zhidkov V. P. Shcherbakov 《Izvestiya Physics of the Solid Earth》2008,44(10):816-821
A large volume of data on the paleointensity H an obtained by A.S. Bol’shakov and G.M. Solodovnikov is ignored in modern reconstructions because the authors did not indicate whether they used the check-point procedure for the detection of chemical alterations in rocks associated with determination of H an. The paper presents new values of H an determined by the Thellier-Coe method with the use of the checkpoint procedure from samples of the Armenian collection of Cretaceous rocks used in published studies of Bol’shakov and Solodovnikov. The new results are close to the published ones and point to a small value of the geomagnetic field in the Cretaceous, thereby corroborating Bol’shakov-Solodovnikov’s hypothesis on a low paleofield in the Mesozoic. Our study of samples of the collection studied confirms the reliability of Bol’shakov-Solodovnikov’s determinations of H an. 相似文献
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W. B. Langbein 《水文科学杂志》2013,58(2):34-36
Abstract Sampling in undisturbed soils of clearcuts and adjacent unlogged virgin forests in western Oregon indicates that clear cutting results in reduced soil moisture depletion and accelerated recharge. 相似文献
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《Journal of Atmospheric and Solar》1999,61(12):913-923
An updated version of the equivalent circuit model for simulating the ionospheric dynamo process is described. The contributions of the E and F regions to the flux tube integrated conductivities are compared. The results confirm that the ionospheric electric process is controlled by the E region during daytime but by the F region during nighttime. The F region has a larger effect on the dynamo processes during solar maximum than at solar minimum, and during equinox than in solstice. 相似文献
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Summary Methods are outlined for determining the hydraulic properties of an aquifer, namely, the transmissivity and storativity from a well located near one or more impermeable barriers. The procedures are based on the theory of the nonsteady radial flow toward a well steadily discharging from an aquifer of semiinfinite areal extent. Two different flow systems have been considered, namely a well near an impermeable barrier and a well located between two impermeable barriers. 相似文献