麦夸特算法在X射线衍射物相定量分析中的应用

常规的X射线衍射物相定量分析方法有各自的优点,但这些方法往往也存在一些不足.在实际应用中迫切需要一种简便、高效的普适性多物相无标样定量分析方法.选择麦夸特算法、粒子群算法、遗传算法、差分进化算法这4种迭代搜索领域的经典算法构建了基于非线性模型参数估计方法的4模冗余系统,以19个配制的4相样品中各相“前三强线”的积分强度之和作为计算的原始数据,通过Matlab软件进行了含量计算.理论分析及试验结果表明,运用麦夸特算法进行定量分析具有更小的计算复杂度、更快的收敛速度及更好的全局搜索能力,各相含量的计算值与配比值的绝对误差在5%以内的约占总计算量的83%.为了验证该算法,计算了昭苏黄土剖面82个混合样品及青海湖二郎剑钻孔359个混合样品中刚玉的含量,刚玉含量的配比值与计算值的相关性分别达到0.83和0.63,刚玉含量的误差超过5%的分别占总计算量的4.88%和9.75%.基于麦夸特算法的定量分析方法在批量化处理多物相定量中具有效率高、可操作性强、准确度高等优点.      

The Ancient Rural Settlement Structure in the Hinterland of Pompeii Inferred from Spatial Analysis and Predictive Modeling of Villae Rusticae

Pompeii, buried by the explosive A.D. 79 eruption of Somma‐Vesuvius, is one of the most studied ancient cities in the Roman world. However, until very recently, the rural settlement in its hinterland had been largely ignored by systematic archaeological research. The ancient landscape around Pompeii consisted of a dense network of Roman farms (villae rusticae). They are believed to have played a vital role in ancient rural life and economy and thus represented the interactive rural–urban relationship in the Sarno River plain. The systematic investigation of published work combined with new fieldwork has yielded a data set of 140 villae rusticae in the Sarno River plain. Geographic information system based spatial statistics as well as predictive modeling were applied to gain a more detailed understanding of the ancient rural settlement structure in relation to the underlying paleoenvironmental and socioeconomic conditions. A high‐resolution pre‐A.D. 79 paleolandscape model of the Sarno River plain was utilized. The aim of this paper is to address theoretical considerations, the methodological implementation, and the archaeological discussion of the analysis of the ancient rural settlements and agriculture around Pompeii.     

一种实用的X射线无标定量相分析方法

本文推出一种新的Ｘ射线定量相分析方法。其无论有无纯相标样皆可适用，而且分析物相的衍射强度测定不用加内标，还能消除仪器性能衰减的影响。加之余相判别式的建立和完善的计算处理，从而克服了其他方法的种种缺陷。该方法简便、实用、稳定，适应性较强，已在海泡石粘土、氯氧镁水泥等多种材料数千个样品的分析中应用获得成功。     

X射线衍射定量分相分析的策略架构

引入分析策略的概念,揭示了当代研究X射线衍射定量相分析方法的正确途径。通过策略的系统演绎,对现今X射线定量相分析的基本方法进行了全面的构筑和科学分类,总共有7类分析方法,分别称之为内标消约法、外标消约法、样内异相消约法、样间异相消约法、样间同相消约法、归并C值法和理论计算法,并对各类方法的固有特点作了全面的概括。阐述了如何用现代谱图拟合技术进行常规定量方法的扩展以实现择优取向的强度修正。     

南海南部地壳结构的重力模拟及伸展模式探讨

对南海南部地壳结构研究有助于揭示南海完整的演化历史。本研究对南海南部获取的两条多道地震剖面进行了地震 解释,并对重力数据进行了壳幔密度反演。其中 NH973-1 测线始于南海西南次海盆,覆盖了南沙中部的北段;NH973-2 测 线始于南海东部次海盆,穿越礼乐滩东侧。反演结果显示,莫霍面埋深在海盆区 10~11 km,陆缘区 15~21 km 左右,洋壳向 陆壳莫霍面深度迅速增加。海盆区厚度在 6~7 km,为典型的洋壳;陆缘区地壳厚度在 15~19 km,为减薄型地壳。进一步研 究表明(1)在西南次海盆残余扩张脊之下,莫霍面比两侧略深;(2)在礼乐滩外侧海盆区有高值重力异常体,推测为洋壳与深 部岩浆混合的块体;(3)南沙区域上地壳存在高密度带,且横向上岩性可能变化。南海南部陆缘未发现有下地壳高速层,有 比较一致的构造属性和拉张样式,为非火山型陆缘。我们对两条测线陆缘的伸展因子进行了计算,发现上地壳脆性拉伸因 子与全地壳拉伸因子存在差异,其陆缘的拉张模式在纵向上是不均匀一的。     

多组分混合物X射线衍射直接定量相分析方法

研究了物质粉末衍射强度与样品堆积密度的关系,将粉末样品紧密度导入衍射强度公式。在此基础上推导出直接法测定多组分混合物质量吸收系数及各相浓度的数学公式,并通过实验证明了方法的实用性。还研究了缺乏纯样品以及样品中存在非晶质相、结晶度变化大的柑、择优取向严重的相等特殊情况的实验方法。 该方法不需要向待测样品中加入任何参考物质,不称样,不混样,不损耗纯样品,制样简便,特别适合大批量样品的定量相分析。     

微量相X射线衍射定量分析的一种简便方法

阐述了关于微量相X射线衍射定量分析的一种简便方法———近似线性关系法,它适用于二相体系(或基体吸收系数基本恒定的多相体系)材料中微量相的定量分析。该方法不需要在待测样品中加入参考物相,分析时仅需对一条衍射线进行测定,因而分析时间很短,其测定结果与实际含量的相对误差为-10.2%～ 21.4%,与外标法和内标法的测量结果的精度相当。     

古构造应力场反演的理论与实践——基于断层滑动矢量分析

古构造应力场恢复是重建区域地质演化历史的重要手段之一。断层作为地壳浅表发育的脆性变形构造,为恢复古构造应力场提供了重要地质条件。关于利用断层滑动矢量反演古构造应力场,前人进行了长期探索。目前其相关理论基础、研究方法与实际应用均取得重要进展。在断层滑动矢量反演古构造应力场的理论方面,改进的安德森模式描述了在发育先存薄弱带的情况下断层形成与演化的规律,克服了安德森模式只适用于均匀变形域的理论局限性;在研究方法方面,突破了在沉积盆地内部变形相对单一的限制,在造山带前陆或者叠加褶皱区等复杂变形区有效地开展了相关研究,并通过断层相关褶皱与同褶皱变形的滑动矢量分析,厘定出同造山作用的古构造应力场。这一方法在大巴山造山带强变形区得到了有效应用,为探讨其构造演化提供了基础。     

中高含硫量煤中硫的形态分析

利用超声提取、高速离心分离和加入助分散剂等手段，实现了中，高含硫量煤中单质硫，硫酸盐硫，硫化物硫，有机硫等主要形态硫的分步提取和顺序测定。所建分析方法测定了国家一级标样，统样样品和部分有分析结果的样品，其主要形态硫的加和与标准样品参考值，统检样品定值，原样品的总硫分析结果相符，RSD（n=3)为0．80％－4．23％，方法可用于煤中各主要形态硫的测定。     

The Neotectonic Structure of Deception Island (Antarctica) Inferred from the Results of Structural and Geomorphic Analysis

Doklady Earth Sciences - We present the results of analysis of the Strombolian-type Deception volcano after its explosive caldera-forming eruption. The volcano studied, located in the South...     

油气田开发中后期的储层三步建模法——以赵凹油田为例

三步建模法强调建立等时地层对比格架是储层建模的关键,即首先借助地震、测井和钻井岩心等资料,利用高分辨率层序地层学理论建立精细的等时地层对比格架,继而在格架内以不同层次的旋回层序建立沉积微相模型,从而在沉积微相的约束下建立储层物性模型.三步建模法应用于赵凹油田的结果显示,所建立的模型较好地反映了储层地下特征,经验证效果较好.     

Comparison of Mathematical Methods of Potential Modeling

Various attempts are known to turn the “catalogue” of mineral deposit models compiled by Cox and Singer (1986) operational, and have initiated activities called “potential mapping”, “potential modeling”, or “targeting”. The common ultimate objective is to estimate the probability for a given location that a mineralization of a given type occurred. The mathematics range from “weights of evidence” and others featuring a Bayesian approach to logistic regression by maximum likelihood, and include other realizations by means of fuzzy methods, genetic programming, and artificial neural nets. Once developed and coded, applications are not restricted to mineral prospection and exploration but include any kind of occurrences and their estimated probabilities, e.g., risk assessment of land slides and many others.     

粘土矿物的X射线衍射物相分析

文章总结了粘土矿物的Ｘ射线衍射物相分析经验。阐述粘土矿物的分析条件,制样方法和衍射图解释等特点。研究重系定量分析方法,总结出几种常见的粘土矿物的权重系数。讨论了放物高温衍射分析问题。     

Saline Coals of the Ukraine

An original concept of salinization of coals at the peat bog generation stage is substantiated on the basis of on new data. The distribution of saline coals within coal and hydrocarbon basins has been revealed to be wider than it was previously assumed. The degree of salt enrichment of organic matter in coal is related to paleogeographic formation conditions of peat bogs that facilitated the penetration of sea waters (under conditions of paralic basins) or NaCl-rich solutions (related to wash-out of halogenic formations) into the coals. The initial salinization degree does not remain constant, because it is intimately related to superimposed processes leading to the desalinization of coals. The desalinization is controlled by the degree of coalification and realized under favorable tectonic and hydrogeological conditions. The paper presents a review of the current state of the elaboration of techniques for saline coal utilization that must meet requirements of economic and multipurpose utilization of raw material and environment protection.     

How Different Analysis and Interpolation Methods Affect the Accuracy of Ice Surface Elevation Changes Inferred from Satellite Altimetry

Satellite altimetry has been widely used to determine surface elevation changes in polar ice sheets. The original height measurements are irregularly distributed in space and time. Gridded surface elevation changes are commonly derived by repeat altimetry analysis (RAA) and subsequent spatial interpolation of height change estimates. This article assesses how methodological choices related to those two steps affect the accuracy of surface elevation changes, and how well this accuracy is represented by formal uncertainties. In a simulation environment resembling CryoSat-2 measurements acquired over a region in northeast Greenland between December 2010 and January 2014, different local topography modeling approaches and different cell sizes for RAA, and four interpolation approaches are tested. Among the simulated cases, the choice of either favorable or unfavorable RAA affects the accuracy of results by about a factor of 6, and the different accuracy levels are propagated into the results of interpolation. For RAA, correcting local topography by an external digital elevation model (DEM) is best, if a very precise DEM is available, which is not always the case. Yet the best DEM-independent local topography correction (nine-parameter model within a 3,000 m diameter cell) is comparable to the use of a perfect DEM, which exactly represents the ice sheet topography, on the same cell size. Interpolation by heterogeneous measurement-error-filtered kriging is significantly more accurate (on the order of 50% error reduction) than interpolation methods, which do not account for heterogeneous errors.

     

富营养化机理及数学模拟研究进展

水体富营养化是目前面临的水环境问题之一，从富营养化的形成机理，富营养化的数学模拟，富荣养化的控制等3个方面，综述了对富营养化问题的研究现状。     

Catagenesis and composition of petroleum: Origin of n-alkanes and isoalkanes in petroleum crudes

Distribution of n-alkanes and isoalkanes in ca. 50 petroleum crudes have been examined by the gas chromatography. Molar distributions of n-alkanes with respect to their c atom numbers in the majority of crudes follow the exponential law, which signifies a random, chemical nature of n-alkane-generating processes occurring in the catagenesis stage of petroleum maturation. Similar distributions of n-alkanes were found in the products of mild thermolysis of heavy n-alkanes.Isoalkanes represent a major, 10–25%, petroleum component. The principal types of isoalkanes in crudes are monomethyl-branched, with the branches randomly positioned in the chains, and dimethyl-branched with one of the methyl groups predominantly in the second position in the chains. Thermolysis studies of individual n-alkanes, alkanoic acids, and esters in the presence of various minerals provided an explanation of the n-alkane and isoalkane distributions. Selected heavy n-alkanes are initially formed in decarboxylation reactions of heavy n-alkanoic acids and esters. Extensive thermocracking produces mixtures of lighter n-alkane and α-olefins. The olefins, in the presence of acidic clays, are converted in cationic reactions into mixtures of predominantly mono- and dimethyl-branched isoalkanes.     

冰湖溃决洪水的二维水动力学数值模拟

为分析冰湖溃决洪水过程,建立了一个二维非恒定流数值模型,可以定量的开展冰湖溃决洪水预测.数值模型的基本控制方程采用二维浅水水流方程,数值方法采用可以捕捉激波的WAF TVD二阶精度格式,并用非界面追踪的方法处理干湿边界.通过理想情况下一维解析解的验证和二维复杂地形情况的数值试验,证明数值模型具有较好的精度和可靠性,并且可以适应复杂地形.将数值模型应用于一个典型的冰湖溃决事件,定量地预估了该冰湖溃决洪水过程,结果表明:水流流速很高,床面剪切应力很大,可能诱发活跃的泥沙运动,形成泥石流灾害.     

Ammonium Photoproduction from Aquatic Humic and Colloidal Matter

It has recently been shown thatnitrogen contained in humic substances can be releasedas low molecular weight species through photochemicalprocesses or reactions. Nitrogen released in thismanner may then become available for biological useand chemical reactivity. This report providesadditional kinetic data for nitrogen photochemistry oforganic matter in natural waters from Louisiana andfor Suwannee River humic and fulvic acids. Naturalwater samples were fractionated into colloidal(>0.2 m, <1000 Dalton) and dissolved (>1000Dalton) fractions and the kinetics of these fractionsas well as 0.2 m filtered water samples weremeasured. For irradiations of less than 10 hours ofsimulated noon-time sun, samples showed linearproduction of ammonium and first-order fading at350 nm. Ammonium photoproduction was enhanced asmuch as three-fold by lowering pH, but linear kineticswere maintained. Light-dark cycling showed continuedrelease of ammonium immediately after irradiation,followed by uptake at longer post irradiation times.A two step mechanism was proposed to explain theobserved kinetics. Calculated net daytime release ofammonium from natural surface waters ranged from 0.33to 1.9 M h^-1 in the samples studied,corresponding to a photic zone conversion rate of9–20% of the total organic nitrogen per day intoammonium.     

Phylogeny of Devonian Lycopsids Inferred from Bayesian Phylogenetic Analyses

To investigate the phylogeny of early lycopsids, cladistic analyses using both parsimony and Bayesian approaches are presented, with a data matrix of 33 morphological characters across 25 taxa. The resulting parsimony and Bayesian trees showed overall similarities in tree topologies. In the Bayesian tree, the Protolepidodendrales and the heterosporous lycopsids are recognized as two monophyletic groups, and within the latter group, the Isoetales sensu lato forms a subclade. This topology implies that the acquisition of a ligulate character evolved twice in the lycopsids, once in the protolepidodendralean Leclercqia Banks et al., and once in the heterosporous lycopsid clade. Phylogenetic positions of several lycopsid plants previously reported from the Mid-Upper Devonian of South China, which have uncertain ordinal affinities, were estimated by the cladistic analyses; cf. Longostachys Xue et Hao, Longostachys Zhu et al., Monilistrobus Wang et Berry, and Yuguangia Hao et al. fall well within the Isoetales clade, as earliest members of this order, while Minostrobus Wang and Wuxia Berry et al. are nested within the basal part of the heterosporous lycopsids. Bayesian analyses are a very useful approach in systematic studies and can be applied in analyzing paleobotanical data sets as well.