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991.
Ian Knowles Michael Teubner Aimin Yan Paul Rasser Jong Wook Lee 《Hydrogeology Journal》2007,15(6):1107-1118
A new inverse technique for modelling groundwater flow, based on a functional minimization technique, has been used to calibrate
a groundwater flow model of a subregion of the Port Willunga aquifer within the Willunga Basin in South Australia. The Willunga
Basin is the location of extensive viticulture, irrigated primarily by groundwater, the levels and quality of which have declined
significantly over the last 40 years. The new method is able to generate estimates of transmissivity, storativity and groundwater
recharge over the whole subregion as a time-varying continuous surface; previous methods estimate local discrete parameter
values at specific times. The new method has also been shown to produce accurate head values for the subregion and very good
estimates of groundwater recharge. Its ultimate goal will be to provide a new and invaluable tool for significantly improved
groundwater resource management.
Supported in part by US National Science Foundation grants, DMS-0107492 and DMS-0079478. 相似文献
992.
渗漏是严重影响堤坝安全的主要形式,确定渗漏通道的位置是进行堤坝渗漏整治的前提和基础。温度场探测堤坝渗漏的研究是其中一种较便捷的方法,但是在理论上还需要进一步完善。在库水和地下水存在着温度差异的基础上,考虑堤坝发生集中渗漏后,渗漏通道中的地下水与周围土体进行热量交换,造成渗流通道附近地层温度发生改变,建立起温度场对渗漏通道的反演模型。在前人研究的基础上,考虑地温梯度的影响,可以建立有集中渗漏通道影响下的二维热传导方程,进而以现场测井的温度数据作为边界条件,对泛定方程进行求解,最终得到渗漏通道的位置。计算结果和实测结果的对比表明,通过温度场反推渗漏通道参数的方法是可行的。 相似文献
993.
994.
摸索沙拐枣属(Calligonum L.)七种植物沙拐枣(Calligonum mongolicum Turcz. )、泡果沙拐枣(C. junceum (Fisch. et Mey.) Endl.)、无叶沙拐枣(C. aphyllum (Pall.) Gürke)、红果沙拐枣(C. rubicundum Bge.)、心形沙拐枣(C. cordatum E. Kor. ex N. Pavl.)、密刺沙拐枣(C. densum Borszcz.)、乔木状沙拐枣(C. arborescens Litv.)的总DNA提取方法并对DNA样品的纯度和浓度进行鉴定,对传统的CTAB法进行方法和材料的改进,开展与总DNA相关的PCR扩增和其他遗传学分析,并取得满意的结果。其结果对于沙拐枣属植物的有关研究提供了有效的实验手段。 相似文献
995.
Young Hong Shin Houze Xu Carla Braitenberg Jian Fang Yong Wang 《Geophysical Journal International》2007,170(3):971-985
996.
997.
The stiffness degradation and damping ratio evolution of Taipei Silty Clay under cyclic straining 总被引:2,自引:0,他引:2
The non-linear behavior of Taipei Silty Clay under cyclic strain loading was investigated through a series of undrained cyclic strain-controlled tests. The Ramberg–Osgood equation was used with our proposed stiffness degradation model to calculate degraded secant moduli. The proposed degradation model is simple in that it has only one more component than Idriss's model, the modulus ratio for the first cycle, which reflects the effects of the previous cyclic strain history and the current level of the cyclic strain amplitude, and can be used to describe softening and hardening behavior under irregular cyclic straining. It was found that the Ramberg–Osgood equation successfully predicts the damping ratio for small to medium strains. However, it overestimates the damping ratio for larger strains, so we suggest it can be corrected with a damping ratio index. In addition, the proposed equation for describing the evolution of the damping ratio provides the means to assess the variation for Taipei Silty Clay in the measured damping ratio with both the number of cycles and the strain amplitude. 相似文献
998.
Determination of vertical displacements over the coastal area of Korea due to the ocean tide loading using GPS observations 总被引:2,自引:0,他引:2
This paper describes the GPS applicability for detecting the vertical displacements of ground stations caused by ocean tide loading effects. An experiment was carried out using 12 permanent GPS stations located in the coastal area of Korea using data in the period 1 July until 26 August 2003. The relative height differences were calculated from hourly DGPS data processing based on the carrier-phase observation. The power spectra of the M2 and N2 constituents of ocean tide loading were derived using the CLEAN algorithm. The differential vertical displacements generated by the ocean tide loading effect are typically 3–25 mm in coastal area of the Korea. We compared the results from GPS with those of the ocean tide models, NAO.99Jb regional model and GOT00.2, FES99 global models. The M2 (N2) amplitude differences of vertical displacements between GPS and GOT00.2 is 1.22 ± 3.61 mm (1.01 ± 1.48 mm), and that of the M2 (N2) amplitude difference between GPS and FES99 is 0.04 ± 4.64 mm (0.64 ± 1.75 mm), whereas the M2 (N2) amplitude difference between GPS and NAO.99Jb are 0.05 ± 1.03 mm (0.86 ± 1.18 mm). The highest vertical displacements at the PALM station are found for 24.5 ± 0.7 mm from GPS observation, and 22.9 mm from the regional model NAO.99Jb and 13.17 and 10.00 mm from the global models GOT00.2 and FES99, respectively. These values show that the vertical displacements derived from GPS are in good agreement with those of the regional model NAO.99Jb around Korea, more than with the global models. This result indicated that GPS is an effective tool to measure the vertical displacement caused by the ocean tide loading effect in the coastal area, and we need to use the NAO.99Jb ocean tide model rather than the global ocean tide models in and around the Korean peninsula for position determination with permanent GPS installations. This work demonstrates that vertical displacement caused by the M2 and N2 constituents of ocean tide loading can be measured by carrier-phase DGPS. 相似文献
999.
Jie GU Chiwai LI Hong YANG Yong ZHAN 《国际泥沙研究》2007,22(2):150-159
The mixing characteristics of dredged sediments of variable size discharged into cross-flow are studied by an Eulerian-Lagrangian method. A three-dimensional (3D) numerical model has been developed by using the modified k-ε parameterization for the turbulence in fluid phase/water and a Lagrangian method for the solid phase/sediments. In the model the wake turbulence induced by sediments has been included as additional source and sink terms in the k-ε model; and the trajectories of the sediments are tracked by the Lagrangian method in which the sediment drift velocities in cross-flow are computed by a multiphase particle-in-cell (MP-PIC) method and the diffusion process is approximated by a random walk model. The hydrodynamic behavior of dumped sediment cloud is governed by the total buoyancy on the cloud, the drag force on each particle and velocity of cross-flow. The cross-flow destroys more or less the double vortices occurred in stagnant ambience and dominates the longitudinal movement of sediment cloud. The computed results suggest satisfactory agreement by comparison with the experimental results of laboratory. 相似文献
1000.