电感耦合等离子体质谱法(ICP-MS)测定水系沉积物中的铌钽锆铪

建立电感耦合等离子体质谱法(ICP-MS)测定水系沉积物中铌、钽、锆、铪四种元素的分析方法。将样品与氢氧化钠、过氧化钠混合物放入高温炉中,熔融分解完全,用热水提取,过滤后弃去滤液,将滤纸及沉淀用酒石酸-盐酸溶液溶解,稀释至刻度测定。方法检出限(3s)为:LD(Nb)=0.08μg/g,LD(Ta)=0.04μg/g,LD(Zr)=0.5μg/g,LD(Hf)=0.04μg/g,精密度(RSD%,n=6)为:0.84%~4.21%。该测定方法具有灵敏度高、精密度好、分析速度快、线性范围宽、操作性强等优势。采用该方法对国家一级标准物质进行测定表明,其结果与标准值吻合。此方法已在实际地质调查样品分析中得到应用。     

Study on the Period Changes of xy Leonis

XY Leo (BD+18° 2307, p = 0d .28) was observed each season from 1992 through 1995 at Yunnan Observatory with the 1 m telescope and 37 new heliocentric times of minimum light were determined. The newly expanded database of the minimum times,including these new epochs, definitely confirm the sine-like variation of its O–C values. Observations and analyses strongly supported the viewpoint that the variation of the O–C values of the minimum times is mainly caused by the light- time effect. Based on this newly expanded database, new light elements for the eclipsing system XY Leo and new light-time orbit for this complex system have been obtained with much better accuracy than before by means of the least squares fitting to the light-time equation. It's also noted that the additional period variation for XY Leo probably may not be ruled out besides the light-time effect. The method of analysis and the discussion of the results are presented in this paper. This revised version was published online in July 2006 with corrections to the Cover Date.     

A sequential sparse polynomial chaos expansion using Bayesian regression for geotechnical reliability estimations

Polynomial chaos expansions (PCEs) have been widely employed to estimate failure probabilities in geotechnical engineering. However, PCEs suffer from two deficiencies: (a) PCE coefficients are solved by the least-square minimization method which easily causes overfitting issues; (b) building a high order PCE is often computationally expensive. In order to overcome the aforementioned drawbacks, the Bayesian regression technique is employed to evaluate PCE coefficients, which not only provides a sparse solution but also avoids overfitting. With the aid of the predictive means and variances given by Bayesian analysis, a learning function is proposed to sequentially select the most informative samples that are critical to build a PCE. This sequential learning scheme can highly enhance the computational efficiency of PCEs. Besides, importance sampling (IS) is incorporated into the sequential learning (SL)-PCEs to deal with geotechnical problems with small failure probabilities. The proposed method of SL-PCE-IS is applied to three illustrative examples, which shows that the improved PCE method is more effective and efficient than the common PCEs method, leading to accurate estimations of small failure probabilities using fewer training samples.     

实时精密单点定位中的数据预处理研究

提出了适用于实时环境的一套数据预处理方案,包括钟跳修复、联合使用Geometry-Free和Melbourne-Wübbena组合进行周跳探测。通过丰富的实验算例,说明了对观测值进行钟跳修复的必要性;证明了联合使用GF与MW组合能够准确有效地探测出实际数据中存在的以及手工模拟加入的周跳。     

Electron Probe Microanalysis of Bromine in Minerals and Glasses with Correction for Spectral Interference from Aluminium,and Comparison with Microbeam Synchrotron X‐Ray Fluorescence Spectrometry

The strong spectral interference between Br‐ and Al‐induced X‐ray lines hampers the utilisation of electron probe microanalysis (EPMA) for measuring Br mass fractions in Al‐bearing minerals and glasses. Through measuring Br‐free Al‐bearing materials, we established an EPMA method to quantify the overlap from AlKα on BrLβ, which can be expressed as a linear function of the Al₂O₃ content. The count rate of the BrLβ peak signal was enhanced by high beam currents and long measurement times. Application of this EPMA method to Al‐ and Br‐bearing materials, such as sodalite and scapolite, and to five experimental glasses yielded Br mass fractions (in the range of 250–4000 μg g^?1) that are consistent with those measured by microbeam synchrotron X‐ray fluorescence (μ‐SXRF) spectrometry. The EPMA method has an estimated detection limit of ~ 100–300 μg g^?1. We propose that this method is useful for measuring Br mass fractions (hundreds to thousands of μg g^?1) in Al‐bearing minerals and glasses, including those produced in Br‐doped experiments. In addition, the natural marialitic scapolite (ON70) from Mpwapwa (Tanzania) containing homogeneously distributed high mass fractions of Br (2058 ± 56 μg g^?1) and Cl (1.98 ± 0.03% m/m) is an ideal reference material for future in situ analyses.     

电子探针化学测年技术及其在地学中的应用

电子探针主要应用于固体无机材料的微区化学成分定量测定和表面形貌研究。近十年来电子探针化学测年技术发展迅速，并取得了丰富的研究成果。本文在简单介绍该技术发展历程后，进一步详细介绍该技术的基本原理、样品制备与分析、年龄计算方法等内容，最后讨论了该技术的优缺点，同时指出电子探针测年技术在地学中的具有广泛的应用前景。     

五大连池近代火山老黑山火烧山火山喷发过程的考察研究

作者在已有工作的基础上,以当代火山学的研究思路和观点,为恢复五大连池两个近代火山,老黑山火烧山的喷发历史过程进行了野外考察研究工作。老黑山火山锥是由三套不同的碎屑堆积物组成。在锥体的南侧、东侧和西侧以及北测和北西侧有５个熔岩溢出口,按它们形成先后关系,认为有早、中、晚三期熔岩流。本文还对老黑山火山锥上的寄生火山、结壳熔岩与渣状熔岩的分布、流动特点及形成的控制因素进行了分析讨论。最后得出结论：老黑山火山是经多期次喷发活动形成的。火烧山火山锥是一碎屑化泡沫化程度很低的浮岩块和熔岩碎块组成,同老黑山有明显区别。