Capillary pressure for the sand–CO2–water system under various pressure conditions. Application to CO2 sequestration

Accurate modeling of storage of carbon dioxide (CO₂) in heterogeneous aquifers requires experiments of the capillary pressure as function of temperature and pressure. We present a method with which static drainage and imbibition capillary pressures can be measured continuously as a function of saturation at various temperature (T) and pressure (P) conditions. The measurements are carried out at (T, P) conditions of practical interest. Static conditions can be assumed as small injection rates are applied. The capillary pressure curves are obtained for the unconsolidated sand–distilled water–CO₂ system. The experimental results show a decrease of drainage and imbibition capillary pressure for increasing CO₂ pressures and pronounced dissolution rate effects for gaseous CO₂. Significant capillary pressure fluctuations and negative values during imbibition are observed at near critical conditions. The measurement procedure is validated by a numerical model that simulates the experiments.     

Stochastic assessment of GPS carrier phase measurements for precise static relative positioning

 Global positioning system (GPS) carrier phase measurements are used in all precise static relative positioning applications. The GPS carrier phase measurements are generally processed using the least-squares method, for which both functional and stochastic models need to be carefully defined. Whilst the functional model for precise GPS positioning is well documented in the literature, realistic stochastic modelling for the GPS carrier phase measurements is still both a controversial topic and a difficult task to accomplish in practice. The common practice of assuming that the raw GPS measurements are statistically independent in space and time, and have the same accuracy, is certainly not realistic. Any mis-specification in the stochastic model will inevitably lead to unreliable positioning results. A stochastic assessment procedure has been developed to take into account the heteroscedastic, space- and time-correlated error structure of the GPS measurements. Test results indicate that the reliability of the estimated positioning results is improved by applying the developed stochastic assessment procedure. In addition, the quality of ambiguity resolution can be more realistically evaluated. Received: 13 February 2001 / Accepted: 3 September 2001     

上海市磁悬浮轨道交通线工程岩土工程概况

文章概述了上海市磁县浮轨道交通工程，并对工程沿线的岩土工程特性作了简要的分析评价。     

云南蒙自五里冲水库岩溶及其工程处理

五里冲水库个旧组（T2^cg)灰岩，岩溶极其发育，其中尤以洼地深、峰丛高、溶洞多又大，地下河管道单一较长、岩溶总体发育历史悠久为特点，以更新世以来岩溶最为发育，现今地下河管道主要形成于晚更新世至今。因区域地壳持续抬升，岩溶没有成层发育的规律，但自上向下递减现象明显。工程上五里冲水库是以帷幕高压灌浆技术为主辅以其它多种方法处理溶洞及封堵地下河，利用天然盲谷成库的一座无大坝中型水库。帷幕高压灌浆技术先、便捷、可靠。水库蓄水己达设计水位，发挥了效益。一年可向蒙自县供水8161万m^3，可增加灌溉面积10万亩，改善灌溉2.3万亩，向城市及工业供水1210万m^3，使蒙自水利化程度由37%提高到70%以上。     

高温高压下橄榄石含水实验和软流圈成因

高温高压橄榄石含水实验表明，水进入橄榄石能加速其塑性形变，促进了地幔塑性流动，为上部软流圈成因提供一种新的可能依据。     

农业生态的化学元素分类及其与作物优质高产的关系

利用国家科学技术成果，并根据国内外研究现状，将103个化学元素分成对作物生长发育、增产起显著作用、起一定作用、起有害作用和起未知作用4个农业生态元素类型，进而论述了它们与作物优质高产的关系。     

单波高精度测距系统的研究

本文介绍了测距精度优于１０＾－６的自动高精度测距系统的构成、原理及春应用。     

GPS定位中对流层折射估计研究

本文首先讨论了ＧＰＳ相对定位中的对流层折射２估计的单参数方法，多参数方法，分估线性方法和随机过程方法。论证了其它方法都是随机过程方法的近似。为了用随机过程模拟对流折射，建立了一种最小二乘递推算法。在此基础上，在ＧＡＭＩＴ软件中统一实现了以各种对流层折射估计方法。最后给出并分析了不同方法所获得的结果。     

高密度电阻率法探测岩溶的应用研究

应用高密度电阻率法查清三家子地段输油管道地下岩溶的分布状态，解决了岩溶对输油管道影响的问题。     

1986/1987厄尔尼诺期间的西风强化和海气相互作用过程分析

本文利用欧洲中期数值天气预报中心(ECMWF)西北太平洋上空(25°—35°N,110°—180°)850 hPa客观分析的西风分量,计算了1986/1987厄尔尼诺期间的西风强度.结果表明1986年12月—1987年5月西风的累计强度比1986/1987厄尔尼诺前后诸年份同期的西风更强,这种强化与历次厄尔尼诺期间西北太平洋副热带高压的加强是一致的,都反映了哈德莱环流的强化.为了探讨大气环流发生这种变化的原因,作者利用中美海气观测期间的海洋资料,说明了热带两太平洋东部对低纬度大气异常的加热和西部边界流向中纬度海洋输送热量的减少是两个十分重要的原因.