Study of shallow groundwater quality evolution under saline intrusion with environmental isotopes and geochemistry   总被引：2，自引：0，他引：2  

F. Ma  Y. S. Yang  R. Yuan  Z. Cai  S. Pan 《Environmental Geology》2007,51(6):1009-1017

Evolution of the shallow groundwater quality under saline intrusion in porous aquifer system has been studied with environmental isotopes and geochemistry in the Laizhou Bay area, China. Two campaigns of water sampling from various sources were carried out in spring and winter for environmental isotopic and chemical analyses. The origin of groundwater salinity from intrusion of both modern seawater and deep brine water was identified by analysing the correlations between ¹⁸O, D, T, Cl⁻, SO₄²⁻ and electrical conductivity. The results indicate that the brine is originated from evaporating and concentrating of intruded seawater and its δD and δ¹⁸O are different from modern seawater but similar to those of mixture of seawater with fresh groundwater. It is hard to distinguish the salinity origin in this area by the δD–δ¹⁸O relationship alone. The relations between δ¹⁸O and conductivity, Cl⁻ and SO₄²⁻ have been used to identify the salinity origin due to the distinct difference in salinity between the brine and seawater, conjunctively with use of T. A threshold of T = 12 TU was adopted to identify the origin of saline groundwater.  相似文献   

梯级水库群联合优化调度函数研究   总被引：6，自引：3，他引：6       下载免费PDF全文

刘攀  郭生练  张文选  肖义  高仕春 《水科学进展》2007,18(6):816-822

构建了制定梯级水库群联合优化调度函数的"优化-拟合-再优化-随机仿真"框架:首先建立梯级水库群优化调度模型,通过确定性动态规划方法得到最优样本;然后对最优样本进行多元线性回归分析得到联合调度函数;并基于模拟调度结果采用非线性规划方法直接修正调度函数;最后通过水文随机模拟技术生成径流系列,进一步检验、评价所得调度函数的效率。以清江梯级水库群长期优化调度为对象进行实例研究,计算结果表明:对于1951-2005年实测径流系列,梯级水库群联合优化调度函数较常规调度方案年均增加发电量2.03亿kW·h,增幅达2.79%;对于两种随机模拟方法生成的水文径流系列,年均发电量分别提高了1.74%和2.36%,经济效益显著。  相似文献   

利用井径资料预测鱼卡煤田东部勘探区七煤顶板的稳定性     

栾安辉潘语录  田贵发 《中国煤田地质》2007,19(6):73-75

在煤田测井中，井径的变化对其它测井参数是一种干扰，但利用井径的相对变化值（井径扩大系数），可有效地评估岩石的强度等级和可采煤层顶底板的稳定性。统计鱼卡煤田东部勘探区29个钻孔孔径的变化值，按岩石抗压强度划分原则，将其七煤顶板稳定性划分为5个等级，据此固定了该煤田七煤顶板稳定性分布图。  相似文献   

Field and geochemical characteristics of the Mesoarchean ( 3075 Ma) Ivisaartoq greenstone belt, southern West Greenland: Evidence for seafloor hydrothermal alteration in supra-subduction oceanic crust     

Ali Polat  Peter W.U. Appel  Robert Frei  Yuanming Pan  Y&#x;ld&#x;r&#x;m Dilek  Juan C. Ordez-Caldern  Brian Fryer  Julie A. Hollis  Johann G. Raith 《Gondwana Research》2007,11(1-2):69

The Mesoarchean (ca. 3075 Ma) Ivisaartoq greenstone belt in southern West Greenland includes variably deformed and metamorphosed pillow basalts, ultramafic flows (picrites), serpentinized ultramafic rocks, gabbros, sulphide-rich siliceous layers, and minor siliciclastic sedimentary rocks. Primary magmatic features such as concentric cooling-cracks and drainage cavities in pillows, volcanic breccia, ocelli interpreted as liquid immiscibility textures in pillows and gabbros, magmatic layering in gabbros, and clinopyroxene cumulates in ultramafic flows are well preserved in low-strain domains. The belt underwent at least two stages of calc-silicate metasomatic alteration and polyphase deformation between 2963 and 3075 Ma. The stage I metasomatic assemblage is composed predominantly of epidote (now mostly diopside) + quartz + plagioclase ± hornblende ± scapolite, and occurs mainly in pillow cores, pillow interstitials, and along pillow basalt-gabbro contacts. The origin of this metasomatic assemblage is attributed to seafloor hydrothermal alteration. On the basis of the common presence of epidote inclusions in diopside and the local occurrence of epidote-rich aggregates, the stage I metasomatic assemblage is interpreted as relict epidosite. The stage II metasomatic assemblage occurs as concordant discontinuous layered calc-silicate bodies to discordant calc-silicate veins commonly associated with shear zones. The stage II metasomatic assemblage consists mainly of diopside + garnet + amphibole + plagioclase + quartz ± vesuvianite ± scapolite ± epidote ± titanite ± calcite ± scheelite. Given that the second stage of metasomatism is closely associated with shear zones and replaced rocks with an early metamorphic fabric, its origin is attributed to regional dynamothermal metamorphism. The least altered pillow basalts, picrites, gabbros, and diorites are characterized by LREE-enriched, near-flat HREE, and HFSE (especially Nb)-depleted trace element patterns, indicating a subduction zone geochemical signature. Ultramafic pillows and cumulates display large positive initial ε_Nd values of + 1.3 to + 5.0, consistent with a strongly depleted mantle source. Given the geological similarities between the Ivisaartoq greenstone belt and Phanerozoic forearc ophiolites, we suggest that the Ivisaartoq greenstone belt represents Mesoarchean supra-subduction zone oceanic crust.  相似文献   

石狮市基础控制网探讨     

潘志华 《测绘技术装备》2007,9(1):33-34,16

随着国民经济建设的高速发展与现代测绘技术的迅猛发展,石狮市现有的大地控制成果无论在其精度与现势性方面均无法满足城市建设的需要,为解决急需,充分发挥基础控制网在国民经济建设基础与先行作用,迫切需要加强石狮市基础测绘工作。本文根据现代测绘技术结合石狮市基础控制网发展要求,对石狮市基础控制网,包括控制基准、大地水准面精化等进行系统研讨,为项目实施提供参考。  相似文献   

Multiobjective heuristic approaches to seismic design of steel frames with standard sections     

M. Ohsaki  T. Kinoshita  P. Pan 《地震工程与结构动力学》2007,36(11):1481-1495

Seismic design problem of a steel moment‐resisting frame is formulated as a multiobjective programming problem. The total structural (material) volume and the plastic dissipated energy at the collapse state against severe seismic motions are considered as performance measures. Geometrically nonlinear inelastic time‐history analysis is carried out against recorded ground motions that are incrementally scaled to reach the predefined collapse state. The frame members are chosen from the lists of the available standard sections. Simulated annealing (SA) and tabu search (TS), which are categorized as single‐point‐search heuristics, are applied to the multiobjective optimization problem. It is shown in the numerical examples that the frames that collapse with uniform interstorey drift ratios against various levels of ground motions can be obtained as a set of Pareto optimal solutions. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Assessment of radionuclide transport uncertainty in the unsaturated zone of Yucca Mountain     

Ming Ye  Feng Pan  Yu-Shu Wu  Bill X. Hu  Craig Shirley  Zhongbo Yu 《Advances in water resources》2007

The present study assesses the uncertainty of flow and radionuclide transport in the unsaturated zone at Yucca Mountain using a Monte Carlo method. Matrix permeability, porosity, and sorption coefficient are considered random. Different from previous studies that assume distributions of the parameters, the distributions are determined in this study by applying comprehensive transformations and rigorous statistics to on-site measurements of the parameters. The distribution of permeability is further adjusted based on model calibration results. Correlation between matrix permeability and porosity is incorporated using the Latin Hypercube Sampling method. After conducting 200 Monte Carlo simulations of three-dimensional unsaturated flow and radionuclide transport for conservative and reactive tracers, the mean, variances, and 5th, 50th, and 95th percentiles for quantities of interest (e.g., matrix liquid saturation and water potential) are evaluated. The mean and 50th percentile are used as the mean predictions, and their associated predictive uncertainties are measured by the variances and the 5th and 95th percentiles (also known as uncertainty bounds). The mean predictions of matrix liquid saturation and water potential are in reasonable agreement with corresponding measurements. The uncertainty bounds include a large portion of the measurements, suggesting that the data variability can be partially explained by parameter uncertainty. The study illustrates propagation of predictive uncertainty of percolation flux, increasing downward from repository horizon to water table. Statistics from the breakthrough curves indicate that transport of the reactive tracer is delayed significantly by the sorption process, and prediction on the reactive tracer is of greater uncertainty than on the conservative tracer because randomness in the sorption coefficient increases the prediction uncertainty. Uncertainty in radionuclide transport is related to uncertainty in the percolation flux, suggesting that reducing the former entails reduction in the latter.  相似文献   

A Matrix Approach Coupled with Monte Carlo Techniques for Solving the Net Radiative Balance of the Urban Block   总被引：2，自引：0，他引：2  

Marta J. N. Oliveira Panão  Helder J. P. Gonçalves  Paulo M. C. Ferrão 《Boundary-Layer Meteorology》2007,122(1):217-241

A new method is developed for solving the shortwave and longwave net radiative balance of a three-dimensional urban structure, represented by parallelepiped blocks uniformly distributed in each direction. The method is based on a novel approach to determine the shape factors among surfaces, which are estimated by Monte Carlo techniques due to the complex geometry associated with the three-dimensional urban structure. Then, a set of linear equations is solved to quantify the radiative balance, in order to obtain their exact solution, considering all the inter-reflections among surfaces. The comparison between the new and the ray-tracing tracking methods resulted in a Pearson correlation coefficient of 0.996. However, by integrating the linear equations’ exact solution with Monte Carlo techniques, the new method reduces by a factor of 36 the central processing unit (CPU) time used to perform the calculations of the ray-tracing tracking method. The use of the model for a sensitivity study allows us to verify the effective absorptance and emittance increases with the canyon aspect ratio of the urban layout. An urban structure formed by square cross-sectional blocks absorbs more solar radiation than an urban structure formed by rectangular cross-sectional blocks. The approximation of a specific geometry for an equivalent bi-dimensional infinite street can be applied for rectangular cross-sectional blocks, where the width is 11 times or more greater than the depth dimension.  相似文献   

强台风"云娜"登陆过程的研究——基于AREM模式的数值分析   总被引：3，自引：0，他引：3  

叶成志  潘志祥程锐　许爱华 《气象学报》2007,65(2):208-220

使用新改进的双重嵌套AREM数值预报模式,并与高时空分辨率的探测资料相结合,针对台风“云娜”登陆加强的特点进行数值模拟分析,结果表明该模式对“云娜”台风环流特征、强度变化趋势和台风降雨等都有较强的预报能力。在此基础上,定量研究其登陆加强过程中三维大气中尺度场动、热力特征及演变过程,并探讨了其登陆加强的机理。由此得出了与“云娜”登陆加强相关的重要影响因子:(1)副热带高压西南侧的偏东引导气流加强是“云娜”登陆前移速加快、强度增强的有利环境场条件。(2)“云娜”近海移速加快时有较强的东密西疏的不对称流场结构,特别是其垂直速度场以及强对流发展的水平分布的强不对称特征与该气旋登陆加强同时发生,也可能与台风强度维持和加强存在一定的相关。(3)在“云娜”中心西南侧的强凝结潜热释放过程,有可能助其在登陆时加强。此外,在“云娜”发展加强阶段,低层暖湿、中层干冷的位势不稳定层结,有利于对流的强盛发展。(4)“云娜”登陆前后有强低空急流与之联结,并有垂直对流运动发展,由此可获得不断增强的潜热能量是其登陆加强的另一个重要机制。  相似文献   

2007年7月16日日本新溻地震对柏崎刈羽核电站的影响   总被引：1，自引：0，他引：1  

潘华李金臣  吴迪忠 《国际地震动态》2007,(11):21-32

2007年7月16日日本新溻县柏崎市附近海域发生Mw6．6地震（日本气象局震级MJMA6．8）。该地震引发世界最大核电厂——柏崎刈羽核电站多起核安全事件，是世界范围内有记载的对核电站影响最为严重的一次地震。本文根据收集到的资料，详细介绍了该地震对柏崎刈羽核电站造成的影响，文章最后概述了日本、国际原子能机构对该地震的反思以及我们应该从中吸取的经验教训。  相似文献