Identification of the diffusion coefficient for a semi-linear hyperbolic-parabolic problem with discontinuous nonlinear terms     

J. Pousin  A. Roukbi 《Computational Geosciences》1998,2(3):241-258

Numerical computations concerning geochemical processes in porous media require a knowledge of the values of the macroscopic parameters. In the context of the interpretation of leaching tests one such parameter is the apparent macroscopic diffusivity. In this paper, a mathematical model for dissolution in the presence of diffusion is considered. It is shown that the constant diffusion coefficient can be identifiable when the time integral of the flux is known. Moreover, a practical algorithm for computing the diffusion coefficient is proposed. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

地下水32Si年龄测试技术——液体闪烁计数法   总被引：1，自引：0，他引：1  

刘存富  王佩仪  周炼  晁念英  万军伟 《地球学报》1997,18(Z1):224-226

本文介绍了应用Fe(OH)3共沉淀法从天然水中提取SiO2，然后提取32P的方法。将H3PO4溶液和TritonX-100混合制备计数溶液，用液体闪烁计数器测量32P的放射性。最后用公式计算32Si的放射性浓度和地下水的32Si年龄。  相似文献   

A mathematical and numerical model for reactive fluid flow systems     

Astrid Holstad 《Computational Geosciences》2000,4(2):103-139

We formulate mathematical and numerical models for multispecies, multi-phase and non-isothermal reactive fluid flow in porous media focusing on the chemical reactions and the transport of solutes. Mass conservation and stability in the time integration are emphasized. We use cell-centered finite volume differencing in space and an implicit Runge-Kutta method in time. Assuming two space dimensions, we introduce flux approximation for arbitrarily shaped convex quadrilaterals. On equidistant and variable sized rectangular grids we choose limited κ= related schemes to approximate the advective flux and the central difference scheme for the diffusive flux. On non-rectangular grids we recommend the VF9 scheme for the estimation of the diffusive flux. Our model exists as a code. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Optical observations of the Be/X‐ray transient system KS 1947+300     

Ü. K&#x;z&#x;lolu  A. Baykal  N. K&#x;z&#x;lolu 《Astronomische Nachrichten》2007,328(2):142-145

ROTSE‐IIId observations of the Be/X‐ray transient system KS 1947+300 obtained between September 2004 and December 2005 make it possible to study the correlation between optical and X‐ray activity. The optical outburst of 0.1 mag was accompanied by an increase of the X‐ray flux in the 2004 observations. A strong correlation between the optical and X‐ray light curves suggests that the neutron star directly accretes from the outflowing material of the Be star. The nearly zero time lag between X‐ray and optical light curves suggests a heating of the disk of Be star by X‐rays. No optical brightening and X‐ray enhancement was seen in the 2005 observations. There is no indication of an orbital modulation in the optical light curve. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

从第32届国际地质大会看矿床学及相关学科的进展   总被引：1，自引：0，他引：1  

崔彬  白光宇  郭红霞 《现代地质》2004,18(4):460-462

第32届国际地质大会中有关矿产方面的动态和进展主要分为以下4个部分：与黑色页岩有关的矿床;中亚地区的矿床及构造;锡、钨及其他稀有金属矿床的新发展;海洋矿床的最新发展。  相似文献   

强干扰环境下提高瞬变电磁数据采集信噪比的试验     

谭嘉言  高敬语  张斌  林昌洪 《物探与化探》2013,(4)

在安微铜陵冬瓜山铜矿使用GDP-32Ⅱ进行了一系列的瞬变电磁探测抗干扰试验,通过改变发射频率、线框大小、电流大小、叠加次数和观测次数,对比了不同参数设置下所采集的原始数据的质量,提出了抗干扰数据采集方案,为在强干扰地区获取真实可靠的原始采集资料提供了有效措施。  相似文献   

Silicon-32 as a tool for dating the recent past   总被引：2，自引：2，他引：0  

L. Keith Fifield  Uwe Morgenstern 《Quaternary Geochronology》2009,4(5):400-405

Silicon-32, with a half-life of approximately 140 years, has the potential to fill the dating gap that lies between those chronologies based on the shorter-lived isotopes of ³H and ²¹⁰Pb, and those based on the longer-lived ¹⁴C. Silicon-32 is produced in the atmosphere by cosmic ray bombardment of argon, and falls out on the Earth's surface in precipitation. Silicon-32 methods may be used to date siliceous sediments and sponges, groundwater and glacier ice. Measurement of ³²Si concentrations in these archives is, however, not straightforward. Two methods are available: radioactive-decay counting of the activity of the daughter nucleus, ³²P, and accelerator mass spectrometry, but in both cases the detection of ³²Si pushes the boundaries of the technique. Even the half-life of ³²Si is not known to a precision of better than ±10%. In this paper, we review efforts to determine the isotope's half-life, survey the detection methods and discuss the applications of ³²Si chronology. We show that at least some of the chronometric potential of this radioisotope is close to being realised as a result of recent improvements in methods of measurement.  相似文献   

荣成鲁32井水温动态变化及异常分析     

崔居全  ;杜桂林  ;荆强  ;徐芳芳  ;朱音杰  ;鞠述晔  ;毕可战  ;孟祥刚 《华北地震科学》2014,(4):34-38

总结了鲁32井水温正常动态特征以及自然环境干扰形态特征,探究鲁32井水温异常变化特征,通过对该井周围500km范围内中等地震及远场大震发生时间、空间与水温异常时段对比,发现两者对应关系良好,综合分析已有数据资料认为,鲁32井水温存在附加地热场异常变化的构造条件,可作为近场中等地震前兆异常和远场大震前兆异常中短期判别指标之一。  相似文献   

柴达木盆地英西地区E32盐类矿物成因及油气地质意义     

黄成刚  李智勇  倪祥龙  马新民  张世铭 《现代地质》2017,31(4):779

近年来,柴达木盆地英西地区渐新统E32获得了持续的重大勘探发现。基于岩心观察、系统的微观岩石学、矿物学以及地球化学分析,系统总结了柴达木盆地英西地区渐新统咸化湖盆中盐类矿物特征、成因及成藏作用：(1)英西地区渐新统E32 4种重要的盐类矿物包括石盐、硬石膏、钙芒硝以及天青石等,或聚集成为具有一定厚度的盐层,或以矿物颗粒形式赋存于基质碳酸盐岩中。上部的盐间油层组的盐层较厚,以石盐为主,下部的盐下油层组的盐层较薄,以石膏为主;(2)盐类矿物“低锰”的元素地球化学特征、与盐类矿物伴生的基质碳酸盐岩具有的“低温成因”的碳氧同位素地球化学特征、未见热液矿物发育的岩石学特征以及分布面积极广的平面展布特征均显示了盐类矿物为典型的咸化湖盆沉积型,而非热液卤水析出型;(3)“盐”在油气成藏过程中发挥着重要作用,包括盐类矿物对裂缝的充填和防止油气逸散的封堵作用、盐层因具有很高的毛管突破压力和塑性特征而具有良好的封盖作用、地层条件下促进白云岩次生孔隙发育的作用以及占据一定的储集空间的消极作用等。这一研究成果可为盐下湖相碳酸盐岩的油气勘探提供重要的指导作用。  相似文献   

潜标式海洋探测仪控制系统及模块设计     

宗振  蔡晓冬  刘玉良 《海洋技术学报》2017,36(5):23-27

基于CORTEX M4内核的STM32嵌入式系统,设计并实现了用于长期监测海洋地理环境参数(温度、盐度、湿度等)的潜标式海洋探测仪,给出了主控系统及各个模块的设计方案及选型,通过合理的功能分配,可靠的硬件设计和有效的软件实现,使探测仪具备低功耗、高可靠的特点。海试实验表明,主控系统实现了对探测仪的浮力调节、能源供电及应急处置等状态控制,通过在SOFAR声道工作,完成了对深海海洋要素的实时监测。  相似文献