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621.
622.
V. S. Singh 《Environmental Geology》1999,38(2):168-170
Estimation of aquifer parameters is vital for the assessment of groundwater potential and groundwater flow regime. On an
oceanic island where fresh water lens is fragile and sensitive to various stresses, it is even more essential that in order
to assess the potential of fresh water lens and the effect of various stresses on the fresh groundwater regime the parameters
should be representative to the field hydrogeological set up. Pumping tests conducted on existing large diameter wells on
an oceanic island have been analyzed. A finite difference method has been used to take into account the well storage, partial
penetration and upconing effect into the aquifer. Forward modeling has been carried out to estimate aquifer parameters from
the pumping test data. Field examples are described.
Received: 15 June 1998 · Accepted: 25 August 1998 相似文献
623.
研究了时滞区间大系统的鲁棒稳定性分析问题 ,给出了相应的理论结果。并应用遗传算法 ,给出了相应的实现算法和数值仿真结果 相似文献
624.
625.
We acquired high spectral and spatial resolution hyperspectral imaging spectrometer observations of Mars from near-UV to near-IR wavelengths (∼300 to 1020 nm) using the STIS instrument on the Hubble Space Telescope during the 1999, 2001, and 2003 oppositions. The data sets have been calibrated to radiance factor (I/F) and map-projected for comparison to each other and to other Mars remote sensing measurements. We searched for and (where detected) mapped a variety of iron-bearing mineral signatures within the data. The strong and smooth increase in I/F from the near-UV to the visible that gives Mars its distinctive reddish color indicates that poorly crystalline ferric oxides dominate the spectral properties of the high albedo regions (as well as many intermediate and low albedo regions), a result consistent with previous remote sensing studies of Mars at these wavelengths. In the near-IR, low albedo regions with a negative spectral slope and/or a distinctive ∼900 nm absorption feature are consistent with, but not unique indicators of, the presence of high-Ca pyroxene or possibly olivine. Mixed ferric-ferrous minerals could also be responsible for the ∼900 nm feature, especially in higher albedo regions with a stronger visible spectral slope. We searched for the presence of several known diagnostic absorption features from the hydrated ferric sulfate mineral jarosite, but did not find any unique evidence for its occurrence at the spatial scale of our observations. We identified a UV contrast reversal in some dark region spectra: at wavelengths shorter than about 340 nm these regions are actually brighter than classical bright regions. This contrast reversal may be indicative of extremely “clean” low albedo surfaces having very little ferric dust contamination. Ratios between the same regions observed during the planet-encircling dust storm of 2001 and during much clearer atmospheric conditions in 2003 provide a good direct estimate of the UV to visible spectral characteristics of airborne dust aerosols. These HST observations can help support the calibration of current and future Mars orbital UV to near-IR spectrometers, and they also provide a dramatic demonstration that even at the highest spatial resolution possible to achieve from the Earth, spectral variations on Mars at these wavelengths are subtle at best. 相似文献
626.
This study is devoted to the first French determinations of absolute gravity in the Antarctic (Dumont-d'Urville, Terre Adélie) and Arctic (Ny-Alesund, Spitsbergen) polar regions. The measurements in Dumont-d'Urville were performed in 2000 with the help of the FG5#206 absolute gravimeter belonging to the French geodetic community since beginning 1997; they show a strong noise that causes an uncertainty close to 11 μGal in the determination of the mean gravity value, which will be compared, to a new determination planned for 2005. The Ny-Alesund measurements show on the contrary a noise that, although very variable in time, leads to a gravity determination of better than 5 μGal. The comparison of our value with a previous one two years before suggests a gravity decrease of about 4 μGal which is related to the vertical uplift measured by Very Large Baseline Interferometry (VLBI) at the same site. However, the uncertainty does not allow discriminating between height-to-gravity conversion factors originating from different models. To cite this article: J. Hinderer et al., C. R. Geoscience 334 (2002) 819–826. 相似文献
627.
云南莫霍面形状与大型矿床空间关系探讨 总被引:3,自引:0,他引:3
以32个大型金属矿床为例,探讨其与莫霍面形态,空间关系及其相关的问题,应用的莫霍面图可靠程度较高,莫霍面形态复杂,地幔坳陷分坳陷带和坳陷区两大类,大小不一,统计显示,大型矿床平均分布于规模较大的幔坳中心两侧22km范围内,其原因可能有三:一是界面金属原子的能量比内部要大得多,它的活动性增强,有利于成矿作用的进行,二是边缘成矿效应,三是坳陷两侧往往被超壳断裂切穿,成为矿液上升的通道和赋矿场所,提出云县-勐海、兰坪东支杆-三山及宾川小龙潭三个预测区,认为思茅以东 江以北及昆明-石屏等幔坳带两侧,均是寻找大型矿床的有利区带。 相似文献
628.
选用我国大陆1969-1991年发生的11次Ms≥6.9地震作为样本,取地球物理、地球化学、地形变和地震活动性方面共计12项手段的资料为判定指标,编制了模糊聚类计算机程序用以预报未来3个月、6个月和12个月内发生大震的概率,并给出一个预报实例。 相似文献
629.
630.