NaCl在DMF和1,2-丙二醇混合溶剂中电导的研究   总被引：1，自引：0，他引：1       下载免费PDF全文

王卫东 《盐湖研究》2005,13(3):35-37

在283~308K温度范围内测定了NaCl在DMF和1,2-丙二醇混合溶剂中的电导率,根据公式求得NaCl的摩尔电导率值,应用Kohlrausch经验规则,使用Origin软件进行线性拟合,作图外推求得NaCl在DMF和1,2-丙二醇混合溶剂中的无限稀释摩尔电导率λ0值,并讨论了NaCl溶液的电导率、摩尔电导率、无限稀释摩尔电导率与温度和浓度的关系。  相似文献   

CLM在淮河流域数值模拟试验   总被引：8，自引：1，他引：8  

黄伟  郭振海  宇如聪 《气象学报》2004,62(6):764-775

文中利用 1998年HUCEX资料对CommonLandModel(CLM )的模拟能力进行了验证。结果表明 ,CLM不但能够较好地模拟陆 气间各种能量通量 ,而且还能模拟出土壤中温度的时空分布特征。春季 ,CLM对潜热模拟偏高 ,从而引起土壤温度模拟偏低 ;而在夏季 ,潜热模拟偏低 ,在旱地下垫面由于净辐射模拟偏低使土壤温度的模拟仍然偏低 ,水田下垫面的土壤温度模拟趋向合理。夏季的水田无论在对大气的能量输送还是土壤的温度分布上 ,都有其特殊性 ,需在陆面模式中予以特殊的考虑。  相似文献   

Concentrations of Trace Elements in Carbonate Reference Materials Coral JCp-1 and Giant Clam JCt-1 by Inductively Coupled Plasma-Mass Spectrometry   总被引：1，自引：0，他引：1  

Mayuri Inoue  Masato Nohara  Takashi Okai  Atsushi Suzuki  Hodaka Kawahata 《Geostandards and Geoanalytical Research》2004,28(3):411-416

Trace elements in the Geological Survey of Japan carbonate reference materials Coral JCp-1 and Giant Clam JCt-1 were determined by inductively coupled plasma-mass spectrometry after digestion with 2% v/v HNO₃. A standard addition method was adopted in this determination in order to neutralise the Ca matrix effect. In addition, Sc, Y, In and Bi were used as internal standards to control the matrix effect and correct instrumental drift. Of the eighteen elements measured in JCp-1, precisions for fourteen elements, including Cu, Cd and Ba, were better than 10% RSD and concentrations ranged from 0.002 μg g^-1 (Cs) to 8.02 μg g^-1 (Ba). The concentrations of measured trace elements in JCt-1, except for Cu, were lower than those in JCp-1. Precisions for all elements with concentrations higher than 0.04 μg g^-1 in JCt-1 were also better than 10% RSD and concentrations were found to be between 0.001 μg g^-1 (Cs) and 4.84 μg g^-1 (Ba). The concentrations of more than fifteen trace elements in the aragonite reference materials are reported here for the first time. Both reference materials are suitable for use in geochemical studies of environmental reconstruction based upon biogenic carbonate materials.  相似文献   

Isotope Dilution MC-ICP-MS Rare Earth Element Analysis of Geochemical Reference Materials NIST SRM 610, NIST SRM 612, NIST SRM 614, BHVO-2G, BHVO-2, BCR-2G, JB-2, WS-E, W-2, AGV-1 and AGV-2     

Adam J.R. Kent  Benjamin Jacobsen  David W. Peate  Tod E. Waight  Joel A. Baker 《Geostandards and Geoanalytical Research》2004,28(3):417-429

We present data for the concentrations of eleven rare earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Er, Yb, Lu) in eleven international geochemical reference materials obtained by isotope dilution multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). We have analysed both rock powders and synthetic silicate glasses, and the latter provide precise data to support the use of these as reference materials for in situ trace element determination techniques. Our data also provide precise measurements of the abundance of mono-isotopic Pr in both glasses and powders, which allows more accurate constraints on the anomalous redox-related behaviour of Ce during geochemical processes. All materials were analysed in replicate providing data that typically reproduce to better than one percent. Sm/Nd ratios in all these materials also reproduce to better than 0.2% and are accurate to < 0.2% and can thus be used as calibrants for Sm-Nd geochronology. Our analyses agree well with existing data on these reference materials. In particular, for NIST SRM 610, USGS BHVO-2, AGV-1 and AGV-2, our measured REE abundances are typically within < 2% (and mostly 1%) of REE concentrations previously determined by isotope dilution analysis and thermal ionisation mass spectrometry, consistent with the higher degree of precision and accuracy obtained from isotope dilution techniques. Close agreement of results between basaltic glass reference materials USGS BHVO-2G and BCR-2G and the BHVO-2 and BCR-2 powders from which they were created suggests that little fractionation, concentration or dilution of REE contents occurred during glass manufacture.  相似文献   

Planning for El Niño: The Stages of Natural Hazard Mitigation and Preparation*     

Nancy Beller‐Simms 《The Professional geographer》2004,56(2):213-222

This study examines mitigation and preparation activities selected by four county and state governments in anticipation of the 1997–1998 El Niño. It expands the knowledge of how state and local governments plan short‐term projects and mitigate with longer‐term activities in anticipation of a natural hazard. It also provides a preliminary understanding of divergent responses and plans under similar disaster warnings. It outlines stages that governments follow in determining their natural hazard mitigation and preparedness activities. This model should provide hazard planners, particularly those planning for slower onset hazards, with insights into their own local circumstances, allowing them to choose appropriate strategies.  相似文献   

IMPACTS OF TRANSPORTATION CHANGES ON THE WOODWORKING INDUSTRY OF MEXICO'S PURÉPECHA REGION     

PAUL MARR  CHRISTOPHER SUTTON 《Geographical review》2004,94(4):440-461

ABSTRACT. The PurÉpecha region of Michoacán State, in west‐central Mexico, has a strong tradition of craft production, especially wooden items. Transportation improvements in the region since the mid‐twentieth century have led to a higher level of integration of the regional economy, yet access to the broader Mexican market remains limited. Towns throughout the region have experienced substantial changes in the types of crafts produced, the extent of their local and external markets, and the location of craft production. Transportation improvements have, in part, led to agglomeration economies and a resultant contraction in the number of different types and an increase in the volume of the crafts produced. Market changes have led to the proliferation of craft storefronts in towns with higher levels of accessibility. Conversely, remote towns still rely heavily on distributors and have not been able to expand their markets. As a result, the region has seen the development of a two‐tiered system whereby towns with increased accessibility have viable craft industries and towns with limited accessibility struggle with stagnant craft industries.  相似文献   

南京—仪征地区新近纪地层层序及时代讨论   总被引：7，自引：0，他引：7       下载免费PDF全文

张祥云  刘志平范迪富蒋梦林邵家骥 《中国地质》2004,31(2):179-185

上世纪70年代以来，由于雨花台组与其他砂砾层之间接触关系未被发现，南京—仪征地区新近纪地层层序及时代一直存在着争议。笔者对仪征大仪集新仪1孔剖面进行了重新整理划分，新近纪各地层叠置关系明显，同时结合其他剖面及岩相古地理分析，在前人工作的基础上，对新近纪地层层序及时代进行了讨论。该地区新近纪地层层序为中新世中期的洞玄观组(N1d)、中新世晚期的六合组(N1l)黄岗组(N1h)及上新世的雨花台组(N2γ)以及非正式岩石地层单位方山玄武岩(fb)。雨花台组沉积是位于六合组之上的另一套砂砾层，其沉积时代为上新世晚期。  相似文献   

轮南油田原油中三甲基苯基类异戊二烯化合物的检出及其意义     

卢鸿孙永革  彭平安 《高校地质学报》2004,10(2):283-289

轮南油田不同时代储层原油中检出了丰富的三甲基苯基类异戊二烯化合物。该类化合物被普遍认为是来自于高盐度和强还原水体沉积环境中绿硫菌体内的类胡萝卜素的特征性生物标志化合物。该类化合物的检出对轮南油田烃源岩研究具有重要的指示意义，暗示了具有分层水体或高盐度的强还原环境下发育的优势烃源岩，对该区烃类的主力生烃贡献不容忽视。基于C15-3，4，5-三甲基苯基类异戊二烯异构体在轮南油田原油中的分布规律，及C15-3，4，5／C13-2，3，6-比值与Pr／Ph，Ga／C31H和Ts／Tm等常规地球化学参数的对比，说明具有生源意义、能够指示沉积相特征的三甲基苯基类异戊二烯化合物分布，在一定程度上也受烃类热演化程度的影响。  相似文献   

时变参数PGM(1, 1)变形预测模型及其应用   总被引：7，自引：1，他引：7  

汪孔政 《武汉大学学报(信息科学版)》2005,30(5):456-459

在GM(1，1)模型的基础上，考虑参数随时间的变化，用多项式逼近模型参数，同时针对GM(1，1)模型背景值取值方法的不足，引入背景值最佳生成系数，建立了时变参数PGM(1，1)变形预测模型。多项式中的待定系数采用最小二乘法确定，背景值最佳生成系数采用搜索法确定。实例计算表明，时变参数PGM(1，1)变形预测模型具有较高的模拟精度和预测精度，适合用于变形体的变形预测。  相似文献   

Sign-constrained robust least squares, subjective breakdown point and the effect of weights of observations on robustness   总被引：3，自引：1，他引：3  

Peiliang Xu 《Journal of Geodesy》2005,79(1-3):146-159

The findings of this paper are summarized as follows: (1) We propose a sign-constrained robust estimation method, which can tolerate 50% of data contamination and meanwhile achieve high, least-squares-comparable efficiency. Since the objective function is identical with least squares, the method may also be called sign-constrained robust least squares. An iterative version of the method has been implemented and shown to be capable of resisting against more than 50% of contamination. As a by-product, a robust estimate of scale parameter can also be obtained. Unlike the least median of squares method and repeated medians, which use a least possible number of data to derive the solution, the sign-constrained robust least squares method attempts to employ a maximum possible number of good data to derive the robust solution, and thus will not be affected by partial near multi-collinearity among part of the data or if some of the data are clustered together; (2) although M-estimates have been reported to have a breakdown point of 1/(t+1), we have shown that the weights of observations can readily deteriorate such results and bring the breakdown point of M-estimates of Huber’s type to zero. The same zero breakdown point of the L ₁-norm method is also derived, again due to the weights of observations; (3) by assuming a prior distribution for the signs of outliers, we have developed the concept of subjective breakdown point, which may be thought of as an extension of stochastic breakdown by Donoho and Huber but can be important in explaining real-life problems in Earth Sciences and image reconstruction; and finally, (4) We have shown that the least median of squares method can still break down with a single outlier, even if no highly concentrated good data nor highly concentrated outliers exist. An erratum to this article is available at .  相似文献