Toward an Understanding of Biogenic-silica Dissolution in Seawater – An Initial Rate Approach Applied between 40 and 90 °C

Summary The kinetics of phytoplankton frustule dissolution has generally been studied as the appearance of silicic acid in a batch reactor. Unfortunately, this approach, though often illuminating, has not so far been successful because of the difficulty of parameterising the full reaction curve. This current study shows how the initial rate approach to chemical kinetics offers a way around this bottleneck, thereby allowing much chemical kinetics information about frustule dissolution to be collected. The technique is shown to be flexible and suited to short reaction times which facilitate detailed quantitative kinetics investigation, indeed, as would be expected in a solution phase, kinetics study. The technique is exemplified by a dissolution study of uncleaned frustules of Cyclotella crypticaat 40 °C and above. The frustules were found to yield the same dissolution rate after 5 weeks dark storage, at 4 °C. Meanwhile, log dissolution rate was found to vary linearly with pH, with gradient 0.38 ± 0.01 (r ²=0.990). Linearity was upheld even at pHs as high as 14. Finally, a robust Arrhenius plot was established between 40 and 90 °C yielding an activation energy for dissolution of 84 ± 3 kJ mol ⁻¹. Follow through with the Eyring equation yielded an activation enthalpy, ΔH ^‡, and an activation entropy, ΔS ^‡, of 81 and 85 J mol ⁻¹ K ⁻¹, respectively. The discussion brings salient aspects of existing knowledge about diatom frustule dissolution kinetics into the wider context of silicate mineral dissolution.     

洞室工程地震CT与VSP联合检测方法及应用实例

地震层析成像（CT）和垂直地震剖面（VSP）法一直作为两种完全分离的探测技术在勘探活动中运用,而洞室工程地震CT与VSP联合检测方法则是充分利用VSP和CT数据采集方式的兼容性,通过一体化观测系统参数设计和优化数据处理流程,将两种地震勘探手段融为一体而成为优化组合技术下的高分辨工程物探方法。方法实验结果表明,地震CT与VSP联合检测方法在近地表岩土工程勘查应用中几乎可以不增加野外工作费用,就能够同时获取地下洞室工程体施测区间内的地震CT数据和关于洞室轴向剖面方向的逆向VSP数据体。     

Tangent Vectors of Isochron Rays and Velocity Rays Expressed in Global Cartesian Coordinates

This paper provides Cartesian expressions for tangent vectors of isochron rays and velocity rays previously derived in so-called isochron-orthonormal coordinates. The Cartesian expressions are simpler and easier to implement than the expressions in isochron-orthonormal coordinates. It is shown that the expressions in both coordinate systems are equivalent.     

岩石样品U0和ΔU的计算

本文给岩石原始铀含量和铀变化系数以确切定义 ,并系统介绍了U0 和ΔU的计算方法。计算岩石原始铀含量 (U0 )有Th/U比值法和U Pb同位素法 ,后者又包括两阶段法和三阶段法 ;铀的变化系数 (ΔU)包括近代 (现代 )和成矿时铀的变化。这一手段或方法对研究地浸砂岩型铀矿成矿机理和成矿预测有重要意义。     

业务集合预报系统的现状及展望

集合预报系统从原理上讲也可称之为概率预报系统，其最终目的是要提供所有大气变量的完全概率预报，近几年集合预报技术从以前仅考虑初值的不确定性发展为也考虑模式的不确定性，进而发展了多模式－多分析集合预报技术等，阐述了目前业务集合以预报的一些问题，如扰动初值的生成，多模式集合预报，集合预报产品的应用，检验评价等，介绍了近几年集合预报的新进展及该技术的未来发展趋势。     

中尺度数值预报中不同初值方案的检验对比

采用WMO推荐的标准化检验方法对两套初值方案进行检验，一套为使用T106L19全球中期模式预报场作为初猜场的cressman逐步订正客观分析方案（T106）；一套为直接插值客观分析方案（OBS）。通过对比分析发现：（1）反映大尺度环流场的要素，例如，300hPa风场、500hPa高度，T106初值方案略好于OBS。（2）空间尺度较小的要素，例如，850hPa温度、湿度等，OBS略优于T106；在比湿预报场中，低层预报优于高层，但850hPa比湿预报出现正的系统误差，随着预报时效的延长，正系统误差加大。（3）在风场的预报中，低层预报总体不如高层好，U风分量的预报有负的系统性误差，V风分量有正的系统性误差。同时对责任中初值预防的降水进行TS评分，评分结果表明，T106的总体评分高于OBS，但T106初值方案的空报率高于OBS，而OBS初值方案的漏报率高于T106。     

填埋场中气体运移的非稳定耦合渗流数学模型

基于多孔介质渗流力学和流固耦合理论，建立了填埋场内挥发性气体在土壤中迁移气－固耦合数学模型，并根据数学模型的非线性特征，采用摄动法求出模型的拟解析解。通过解析求解研究了挥发性气体在土壤中耦合与非耦合渗流情况下孔隙压力分布动态特征，为预测和预报挥发性气体在土壤中的扩散状况，以及对环境污染的治理，控制污染的扩散理论了理论依据。     

Second-Order and Higher-Order Perturbations of Travel Time in Isotropic and Anisotropic Media

The partial derivatives of travel time with respect to model parameters are referred to as perturbations. Explicit equations for the second-order and higher-order perturbations of travel time in both isotropic and anisotropic media are derived. The perturbations of travel time and its spatial derivatives can be calculated by simple numerical quadratures along rays.     

Experimental Assessment of Gradual Deformation Method

Uncertainty in future reservoir performance is usually evaluated from the simulated performance of a small number of reservoir realizations. Unfortunately, most of the practical methods for generating realizations conditional to production data are only approximately correct. It is not known whether or not the recently developed method of Gradual Deformation is an approximate method or if it actually generates realizations that are distributed correctly. In this paper, we evaluate the ability of the Gradual Deformation method to correctly assess the uncertainty in reservoir predictions by comparing the distribution of conditional realizations for a small test problem with the standard distribution from a Markov Chain Monte Carlo (MCMC) method, which is known to be correct, and with distributions from several approximate methods. Although the Gradual Deformation algorithm samples inefficiently for this test problem and is clearly not an exact method, it gives similar uncertainty estimates to those obtained by MCMC method based on a relatively small number of realizations.