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851.
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
852.
Removal of LNAPL (oil) from an aquifer is described using a multiphase flow model. At the well boundary seepage face conditions are imposed. These conditions are implemented in a numerical model and withdrawal in a twodimensional domain is simulated for two different geometries of the oil lens and for varied values of the physical parameters. Assuming vertical equilibrium, the oil flow equation is reduced by vertical integration. The well boundary condition is approximated by imposing zero oil lens thickness. Similarity solutions of the reduced equations for the two geometries show good agreement with the numerical results in most cases. 相似文献
853.
Natural fluid phases at high temperatures and low pressures 总被引:1,自引:0,他引:1
Gas phases at low pressures and high (magmatic) temperatures have certain peculiar properties. The fluid is mainly water vapour, which is usually observed during discharging of crystal magmatic melts. At >700°C and <100 bar these peculiar properties include: formation of near ‘dry' salt melts as second fluid phase, very strong fractionation of hydrolysis products between vapour and melts, subvalence state of metals during transport processes, and high sensitivity of the gas to conditions of sublimate precipitation. Phase diagram analysis as well as results of field and laboratory experiments are presented in this article. The processes could be a model for industrial technologies to clean wastes from toxic, rare and heavy metals. Transport forms of some elements in volcanic gases are very similar to the species which were formed first in the protosolar nebula. 相似文献
854.
855.
P. M. Bakker 《Geophysical Journal International》1998,134(2):515-518
In isotropic ray tracing, the ray approximation to the wavefield undergoes a phase shift when the ray crosses a caustic. The cumulative number of such phase shifts along a ray is usually called the KMAH index. The sign of these phase shifts is prescribed by the sign of the angular frequency in combination with the sign convention used for the Fourier transformation. In isotropic media the KMAH index always increases by one or by two, depending on the type of caustic crossed. For (quasi-)shear waves in anisotropic media the KMAH index may decrease. This is the case if the associated slowness sheet is locally concave in one or two of its principal directions of curvature. 相似文献
856.
在对石门雄黄矿区唯一的生产井一号窿矿体成矿条件、控矿因素研究的基础上,用逻辑信息法及回归分析法对其深部的找矿远景进行预测,两种方法结合,指明了-370~-420m段的成矿远景,为今后的采矿工作部暑提供了依据。 相似文献
857.
麻粒岩相条件下石榴黑云斜长片麻岩实验结果表明,含水矿物黑云母(Bi)脱水熔融、长英质矿物部分熔融的性质主要受控于温度条件;而矿物相转变不仅受控于温压条件,而且与脱水熔融、部分熔融存在密切成因联系。依据Bi脱水熔融性质和石榴石(Gi)转变反应特征,可划分以下三个阶段:(1)当温度在700℃时,Bi转变为钛铁矿(Ilm)+磁铁矿(Mt)+H_2O,Gt转变为Mt,(2)当温度在730—760℃,Bi脱水熔融为富K_2O熔体(Melt)+Ilm+Mt,Gt转变为紫苏辉石(Hy)+堇青石(Crd);(3)当温度大于790℃时,Bi脱水熔融为Melt+Hy+Ilm+Mt+H_2O,Gt则转变为Hy+尖晶石(Sp)+Crd组合。熔体比例和熔体演化特征除受温压条件控制外,与长英质矿物部分熔融程度和脱水熔融性质关系密切。实验结果显示,在麻粒岩相变质作用以及与其相伴随的重熔作用(或区域性混合岩化作用)过程中,不仅存在传统的固相+固相(或流体相)的反应和脱水熔融反应,而且存在熔体参与的变质反应(即:未熔矿物与熔体之间的反应)。该项实验对深入探讨麻粒岩相矿物演化的成因机制及其动力学意义提供可靠的实验依据。 相似文献
858.
THE EARLY SUMMER FLOOD PERIODS OF SOUTHERN CHINA AND THE SUMMER MONSOON CIRCULATION OF EAST ASIA 总被引:1,自引:0,他引:1
Based on the thermodynamic characteristics of the summer monsoon and foe change of the lower layer wind fields, the relation between the early summer flood periods of southern China, Including the first flood period of South China and the plum rains period of the middle-lower reaches of the Yangtze River and the activities of the summer monsoon is analysed.The establishment processes of the summer monsoon circulation of East Asia are investigated.It is shown that the beginning and ending of the flood periods are exactly in accordance with the arrival and departure of the fore boundary of the summer monsoon.The establishment process of the circulation from the very beginning of the arrival of the monsoon to the time of great prosperity of development are not the same for each year.They can be classified into four categories.Each category may have four or three stages.Besides, the structure of the summer monsoon regime of East Asia is not unitary.There exist four types of structure model of the monsoon regime of East Asia. 相似文献
859.
TherelationbetweentheresponsespectrumandthephasediferencespectrumFENG-XINZHAO(赵凤新)andYU-XIANHU(胡聿贤)InstituteofGeophysics,Sta... 相似文献
860.
S. Sørensen H. Falbe-Hansen M. Mangoni J. Hjorth N. R. Jensen 《Journal of Atmospheric Chemistry》1996,24(3):299-315
Products and mechanisms have been investigated for the reactions between dimethylsulfide (DMS) and dimethylsulfoxide (DMSO) and the hydroxyl radical (OH) in the presence of NOx. All of the experiments were performed in a 480 L reaction chamber, applying Fourier transform infrared spectroscopy (FT-IR) and ion chromatography as the analytical techniques.In addition to the sulfur containing products that are known to be produced from the gas phase reaction between DMS and OH (SO2, dimethylsulfone, methylsulfonyl peroxynitrate, methanesulfonic acid, H2SO4), DMSO and methanesulfinic acid (CH3S(O)OH) were also observed as products. Only SO2, DMSO2 and methylsulfonyl peroxynitrate were found as sulfur containing products in the reaction between DMSO and OH. Based on these new results we propose a mechanism for the atmospheric oxidation of DMS and DMSO by OH radical. 相似文献