应用生物吸附剂技术处理中低放废液的研究

利用高担子菌所含壳多糖的强吸附性能研制成功的生物吸附剂,以其具有对放射性核素的强选择性吸附能力、减容效果好和显经济效益的优势,可用于处理中低放废液。迄今,已应用于对切尔诺贝利核事故核心区和若干核电站正常运行产生的核废液的处理,在俄罗斯、乌克兰、法国、芬兰等国家的应用研究中效果显。我国自1999年引进该项技术以来,通过对BR厂YG废液和SG废水的吸附小试,验证了该吸附剂对Cs与sr的吸附能力,查明了应用该生物吸附剂技术的最佳条件。目前,正积极筹备对SG废水的扩大规模台架试验。该项技术具有极良好的应用前景。     

A simple procedure to improve the explicit integration of Cam-Clay models

A simple procedure is proposed to reduce the error in the calculation of the stresses when simulating stress paths applying explicit stress integration schemes in Cam-Clay models with an associated flow rule. The procedure consists of defining the value of the preconsolidation stress (the hardening parameter of a Cam-Clay model) so that the drift of the yield surface is zero at each calculation step. The results demonstrate the efficiency of the proposed procedure, especially along softening paths. The method can easily be implemented in existing explicit integration modules, which facilitates its practical application.     

The role of preconditioning in the solution to FE coupled consolidation equations by Krylov subspace methods

The repeated solution in time of the linear system arising from the finite element integration of coupled consolidation equations is a major computational effort. This system can be written in either a symmetric or an unsymmetric form, thus calling for the implementation of different preconditioners and Krylov subspace solvers. The present paper aims at investigating when either a symmetric or an unsymmetric approach should be better used. The results from a number of representative numerical experiments indicate that a major role in selecting either form is played by the preconditioner rather than by the Krylov subspace method itself. Two other important issues addressed are the size of the time integration step and the possible lumping of the flow capacity matrix. It appears that ad hoc block constrained preconditioners provide the most robust algorithm independently of the time step size, lumping, and symmetry. Copyright © 2008 John Wiley & Sons, Ltd.     

On the growth and decay of irregularities in the ionosphere

It has been demonstrated that VHF/UHF scintillation data can be used to evaluate important physical parameters such as scale sizes, strength, growth and decay of irregularities in the equatorial ionosphere. These parameters are important in constructing electroject models. It is shown that large scale irregularities are generated first which later break into smaller scale sizes. During the decay phase, the small scale irregularities disappear first after followed by large scale irregularities. The generation and destruction time of these irregularities has been estimated to be around 20 min. In addition these irregularities affect propagation of radio waves from HF to UHF range which suggests the existence of a wide spectrum of irregularities in the ionosphere. It has been found that the scale sizes of daytimeE-region irregularities are smaller than those in theF-region during night-time. The growth rate of the irregularities seems to be larger in theE-region than in theF-region of the ionosphere.     

Numerical simulation of permafrost growth and decay

A series of numerical models on permafrost growth and decay are presented with special emphasis on the climatic conditions in western Europe during the last glacial stage. Numerical modelling of growth and decay of the active layer suggests penetration depths in the range between 0.6 to 1.4 m. Permafrost is estimated to have grown, depending on the sediment type, to a thickness of 90 m to 140 m in northern Germany and The Netherlands within 10 000 y during the peak period of the last glacial stage. Permafrost continued to exist at depth for about 2000 y after the climatic improvement following the Younger Dryas. Permafrost growth under rivers and lakes is shown to be unlikely under the climatic conditions of the last glacial stage in northern Germany. A time period of 10 000 to 42 000 years and a massive climatic excursion (of the order of > 11°C) is required to remove the thick permafrost layers in Siberia and Alaska of today. © 1998 John Wiley & Sons, Ltd.     

基于快速汉克尔变换算法的CSAMT一维正演

水平层状介质上的电偶源产生的电磁场数值解是含有零阶和一阶贝塞尔函数的无穷积分,这类积分实质上是汉克尔变换式。通过3种方案的计算实例,说明快速汉克尔变换滤波系数的选取对正演结果的影响。计算结果显示:加长滤波系数能明显提高计算精度,使正演结果真实地接近实际;相反,滤波系数区间过短会出现场值的畸变,视电阻率会受到较大影响。因此,合理选取滤波系数可以提高计算精度和速度。     

Geochemical kinetics via the Swift-Connick equations and solution NMR

Signal analysis in Nuclear Magnetic Resonance spectroscopy is among the most powerful methods to quantify reaction rates in aqueous solutions. To this end, the Swift-Connick approximations to the Bloch-McConnell equations have been used extensively to estimate rate parameters for elementary reactions. The method is primarily used for ¹⁷O NMR in aqueous solutions, but the list of geochemically relevant nuclei that can be used is long, and includes ²⁹Si, ²⁷Al, ¹⁹F, ¹³C and many others of particular interest to geochemists. Here we review the derivation of both the Swift-Connick and Bloch-McConnell equations and emphasize assumptions and quirks. For example, the equations were derived for CW-NMR, but are used with modern pulse FT-NMR and can be applied to systems that have exchange rates that are shorter than the lifetime of a typical pulse. The method requires a dilute solution where the minor reacting species contributes a negligible amount of total magnetization. We evaluate the sensitivity of results to this dilute-solution requirement and also highlight the need for chemically well-defined systems if reliable data are to be obtained. The limitations in using longitudinal relaxation to estimate reaction rate parameters are discussed. Finally, we provide examples of the application of the method, including ligand exchanges from aqua ions and hydrolysis complexes, that emphasize its flexibility. Once the basic requirements of the Swift-Connick method are met, it allows geochemists to establish rates of elementary reactions. Reactions at this scale lend themselves well to methods of computational simulation and could provide key tests of accuracy.     

Methods for the numerical solution of the equations of viscoelasticity

In this paper a finite element formulation for a linear viscoelastic ageing material is developed. It is shown that these equations can be solved in the from of an eigenvalue expansion thus reducing the problem to the solution of a set of Volterra Integral equations. An alternative method of solution based on expansion in terms of an operator related to Poisson's ratio is also developed and this solution method is found to significantly reduce the computational effort necessary in the solution of aproblem.     

The effects of radioactive decay of uranium on elemental and isotopic ratios of Alum shale kerogen

The organic matter in the Alum Shale of Sweden is believed to have been affected post-depositionally by irradiation from the natural decay of U. Alum Shale kerogen H/C ratios are inversely proportional to the natural log of the U concentration, presumably as a result of the liberation of H by irradiation of the organic matter. Stable isotopic ratios of¹³C/¹²C in Alum Shale kerogen are directly proportional to the natural log of the U concentration. Experimental irradiation of Green River shale generated hydrocarbon gases 18% lighter than the parent organic matter, which demonstrates the possibility that irradiation induced generation of isotopically light gases could lower¹³C/¹²C ratios in parent organic matter. Irradiation may be a factor governing the relation between¹³C/¹²C ratios in the Alum Shales. Alum Shale O/C ratios generally increase with increasing U concentration and it is suggested that irradiation of organic matter may facilitate oxidation. The “Rock-Eval” maturity parameters “P.I.” and “Tmax” decrease with increasing U concentration. “P.I.” is presumed to decrease as a result of bitumen destruction or polymerization by irradiation.     

Direct,partitioned and projected solution to finite element consolidation models

Direct, partitioned, and projected (conjugate gradient‐like) solution approaches are compared on unsymmetric indefinite systems arising from the finite element integration of coupled consolidation equations. The direct method is used in its most recent and computationally efficient implementations of the Harwell Software Library. The partitioned approach designed for coupled problems is especially attractive as it addresses two separate positive definite problems of a smaller size that can be solved by symmetric conjugate gradients. However, it may stagnate and when converging it does not prove competitive with a global projection method such as Bi‐CGSTAB, which may take full advantage of its flexibility in working on scaled and reordered equations, and thus may greatly improve its computational performance in terms of both robustness and convergence rate. The Bi‐CGSTAB superiority to the other approaches is discussed and demonstrated with a few representative examples in two‐dimensional (2‐D) and three‐dimensional (3‐D) coupled consolidation problems. Copyright © 2002 John Wiley & Sons, Ltd.     

泰斯模型的统计分析求解

本文利用统计分析来求解水文地质参数,原理简单,解是唯一的。其基本思想是利用非稳定流抽水试验获得的s-t系列资料,以泰斯公式为参考模型,建立试验系列的非线性统计模型,求解导水系数T和贮水系数μ 。统计模型既可利用目前先进的软件辅助求解,亦可利用一台可编程计算器完成计算。本文借助一个实例,应用MATLAB语言的统计分析工具的多元回归分析模块进行求解,获得了理想的结果。     

高放处置罐铁释放诱发膨润土矿物相变研究进展

作为高放废物处置罐候选金属材料,低碳钢在处置库服役期间,其腐蚀产物侵入缓冲屏障,导致缓冲材料矿物相变与性能变异,威胁多重屏障体系的长期安全稳定。本文详细综述了国内外处置库深部还原环境所处的弱碱性化学场与中低温度场的变化趋势,认为处置库深部化学-温度还原条件可导致处置罐Fe腐蚀释放Fe~(2+)。在处置库长期运行过程中,蒙脱石与Fe~(2+)接触发生矿物相变,一方面Fe~(2+)置换蒙脱石八面体晶格中的Al~(3+)和Mg~(2+),还原Fe~(3+)或直接占据空位,生成次生矿物;另一方面Fe~(2+)交换蒙脱石层间的Na~+、K~+和Ca~(2+),转化为铁基蒙脱石。矿物相变可诱发缓冲屏障性能变异甚至退化。基于"抗矿物转化"理念,提出了下一阶段缓冲材料矿物相变研究方向,为地下实验室碳素钢选型、缓冲屏障验证试验设计以及屏障体系安全评价提供科学依据。     

Empirical evaluation of solution models for pelitic minerals and their application to thermobarometry

One of the major sources of uncertainty for thermobarometry in pelitic rocks is the inability of solution models to represent accurately the non-ideal behavior of important pelitic minerals, in particular garnet, biotite, and plagioclase. In recent years, a large number of different solution models have been proposed for these phases. The purpose here is to test the effects on the overall uncertainty of the most commonly-used solution models using the garnet-muscovite-annite-plagioclase (GMAP) barometer and the empirical calibration technique. The GMAP reaction has been empirically calibrated several times with varying results, due in large part to the choice of solution models. The method's dependence on the choice of solution model makes it an excellent was in which to address the quality of specific models. By repeating the calibration exercise for different combinations of solution models, it is possible to determine which set of solution models results in the lowest uncertainties, using a sample set of 72 published electron microprobe analyses of pelitic rocks containing the assemblage garnet+muscovite+biotite +plagioclase+aluminum silicate+quartz. As an independent test of the suitability of solution models, we compare the fit of the sample set to the kyanite-sillimanite equilibrium curve, obtaining thermobarometric estimates by simultaneous solution of the garnet-biotite exchange thermometer and GMAP calibrated from thermochemical data.     

Thermodynamic analysis of binary liquid silicates and prediction of ternary solution properties by modified quasichemical equations

Modified quasichemical equations, developed for the analysis of the thermodynamic properties of structurally ordered liquid solutions, are shown to be well-suited for use with molten silicates. For binary systems, these equations have been coupled with a least-squares optimization computer program to analyse simultaneously all thermodynamic data including phase diagrams, Gibbs energies and enthalpies of formation of compounds, activities, enthalpies of mixing, entropies of fusion, miscibility gaps, etc. In this manner, data for several binary systems have been analysed and represented with a small number of parameters. In the present article, results for the SiO₂-MgO, SiO₂-Na₂O and MgO-CaO systems are presented. The resulting equations represent all the binary data, including the phase diagrams, within or virtually within experimental error limits.From the modified quasichemical equations for ternary systems, ternary thermodynamic properties can be approximated solely from data from the subsidiary binary systems. Results for the SiO₂-CaO-Na₂O, SiO₂-CaO-MgO, and SiO₂-MgO-FeO systems are in excellent agreement with measured ternary data. Predictions for the quaternary system SiO₂-MgO-CaO-Na₂O are also presented.     

Application of the geochemical prospecting to improve oilfield structure models

Background： Complicated structure of surveyed area has minor efficiency of seismic surveys-the main method for petroleum and gas prospecting and interpretation of subsurface structure of the Earth. This paper gives an example that in certain cases geochemical surveys can be used as additional tool to establish suitable geological model of the trap. This paper presents geochemical studies in the southeastern part of European territory of Russia-Nagumanovskoe oilfield. Complicated geological structure causes difficulties to create suitable geological model of the trap itself. There are two models of geological structure for the Nagumanovskoe oilfield： Variant A： Researchers assume the presence of gas condensate accumulation and perspective for exploration traps. Variant B： Researchers assume presence of 2 local structures. Method and results： Geochemical data came from over than 2000 shallow probes （2 meters, 6.6 feet） of soil gas samples collected every 200 meters over more than 7 different long profiles. The adsorbed soil gases were analyzed for hydrocarbones. All samples were decomposed into geochemical populations. According to geochemical data the Nagumanovskoe oilfield was well defined on all geochemical profiles. Examination and comparison of hydrocarbon ratio plots and magnitude graphs for each of the two models indicate that the more anomalous magnitude sites agree with the disposition of structures according to model B. The geochemical oil/gas data exhibit clearly defined compositional sub-populations which match the composition of the underlying reservoirs, difference in standard deviation of hydrocarbon values at background and Cretaceous structure （model B） leads to the deduction that variant B is more suitable geological structure model of the Nagumanovskoe oilfield.     

Application of a generalized power transformation to geochemical data

In the context of analysis of variance, Box and Cox (1964) developed a generalized technique for power transformation of frequency distributions to normality. It is here applied to geochemical data, based on the nonlinear optimization of skewness and kurtosis. The transform appears to be particularly well suited to the preprocessing of geochemical data prior to multivariate analysis.     

Improved moraine age interpretations through explicit matching of geomorphic process models to cosmogenic nuclide measurements from single landforms

The statistical distributions of cosmogenic nuclide measurements from moraine boulders contain previously unused information on moraine ages, and they help determine whether moraine degradation or inheritance is more important on individual moraines. Here, we present a method for extracting this information by fitting geomorphic process models to observed exposure ages from single moraines. We also apply this method to 94 ¹⁰Be apparent exposure ages from 11 moraines reported in four published studies. Our models represent ¹⁰Be accumulation in boulders that are exhumed over time by slope processes (moraine degradation), and the delivery of boulders with preexisting ¹⁰Be inventories to moraines (inheritance). For now, we neglect boulder erosion and snow cover, which are likely second-order processes. Given a highly scattered data set, we establish which model yields the better fit to the data, and estimate the age of the moraine from the better model fit. The process represented by the better-fitting model is probably responsible for most of the scatter among the apparent ages. Our methods should help resolve controversies in exposure dating; we reexamine the conclusions from two published studies based on our model fits.     

Application of the coconut fiber in radioactive liquid waste treatment

The treatment of radioactive liquid waste containing organic compounds was always a cause for concern to radioactive waste management facilities because the processes available are expensive and difficult to manage. Biosorption has been studied as a new process in simulated wastes as an alternative to treating them. Among the potential biomass, the coconut fiber has very attractive features that allow the removal of radionuclides using a low-cost biosorbent. The aim of this study was to evaluate the capacity of coconut fiber to remove uranium, americium, and cesium from real radioactive liquid organic waste. Experiments with the biosorption of these radionuclides in coconut fiber were made including (1) preparation, activation, and characterization of biomass and (2) biosorption assays. The biomass was tested in raw and activated form. Biosorption assays were performed, adding the biomass to real waste solutions. The solutions contain natural uranium, americium-241, and cesium-137. The contact times and the concentrations range were varied. The radioisotopes remaining concentration in the solutions was determined by inductively coupled plasma optical emission spectrometry and gamma spectrometry. The results were evaluated by maximum experimental sorption capacity and isotherm and kinetics ternary models. The highest sorption capacity was observed with the activated coconut fiber, with values of 2 mg/g of U (total), 70E?06 mg/g of Am-241 and 40E?09 mg/g of Cs-137. These results suggest that biosorption with activated coconut fiber can be applied in the treatment of radioactive liquid organic wastes containing uranium, americium-241, and cesium-137.