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51.
Jean S. Kane 《Geostandards and Geoanalytical Research》2002,26(1):7-29
As in all fields of sample analysis, reference materials play a large role in supporting measurements in the geosciences. While a rather large number of materials are in distribution (> 380), not all are equally effective or fit-for-purpose in supporting laboratory data quality and thereby assuring the desired comparability of measurements between laboratories. Equally important, reference values that are not fit-for-purpose cannot be used effectively to establish traceability links between laboratory measurements and national and international standards. The needed fitness-for-purpose is not achieved for reference values either when more than one reference value has been proposed and a consensus does not exist among users as to which should be used by all, or when reference value uncertainties are too large in comparison to those of routine laboratory measurements. The focus of this review will be, first to outline the current reality, and second to suggest ways in which certifications of RMs can be improved to provide reference values that are universally accepted and more fit-for-purpose in general laboratory use. The discussion will be illustrated largely by current uses of USGS BCR-1, NIST SRM 610 and IAEA NBS28, as these three materials are those for which the largest body of newly published data exists, according to recent bibliographies of the geoanalytical literature published annually in Geostandards Newsletter: The Journal of Geostandards and Geoanalysis. 相似文献
52.
Preparation of a New Geological Survey of Japan Geochemical Reference Material: Coral JCp-1 总被引:2,自引:0,他引:2
Takashi Okai Atsushi Suzuki Hodaka Kawahata Shigeru Terashima Noboru Imai 《Geostandards and Geoanalytical Research》2002,26(1):95-99
A new geochemical reference material, coral Porites sp. JCp-1 has been prepared by the Geological Survey of Japan (GSJ). Provisional values for twenty one major, minor and trace elements are presented. The homogeneity tests showed that all elements studied are considered to be homogeneously distributed. 相似文献
53.
Study of the Earth’s free core nutation by tidal gravity data recorded with international superconducting gravimeters 总被引:2,自引:0,他引:2
By stacking high-precision tidal gravity observations obtained with superconducting gravimeters at six stations in China,
Japan, Belgium, France, Germany and Finland, the local systematical discrepancies in the parameter fitting, caused by atmospheric,
oceanic tidal loading and the other local environmental perturbations, are eliminated effectively. As a result, the resonance
parameters of the Earth’s free core nutation are accurately determined. In this study, the eigenperiod of free core nutation
is given as 429.0 sidereal days, which is in agreement with those published in the previous studies. It is about 30 sidereal
days less than those calculated in theoretical models (about 460 sidereal days), which confirms the real ellipticity of the
fluid core of the Earth to be about 5% larger than the one expected in assumption of hydrostatic equilibrium. The quality
factor (Q value) of free core nutation is given as about 9543, which, compared with those determined before based on the body
tide observations, is much larger, but more close to those obtained using the VLBI observations. The complex resonance strength
is also determined as (−6.10×10−4, −0.01 ×10−4)°/h, which can principally describe the deformation characteristics of an anelastic mantle. 相似文献
54.
55.
A comparison of subgrid-scale models for large-eddy simulations of convection in the Earth's core 总被引:2,自引:1,他引:2
Bruce A. Buffett 《Geophysical Journal International》2003,153(3):753-765
56.
大多数火山喷发以强酸 (主要是硫酸 )的形式在极地冰芯中留下痕迹 ,通过冰芯连续电导率 (ECM)或各个雪冰样品SO42 - 浓度测定能够恢复历史上的火山作用。极地冰芯中已知年代的火山喷发还可用于冰芯定年。极地冰芯记录的火山信号大小依赖于火山喷发的规模和类型 ,火山喷发的地理位置和酸性气体组成 ,大气气溶胶传输 ,以及沉降地点的年积累率和沉积后生过程等。单个火山喷发通常会导致数月至数年的半球乃至全球范围的气候相对变冷 (这种现象在极区变得更明显 ) ,但过去大规模的爆炸性火山喷发对气候的影响及其与气候变化之间的联系仍有待于进一步研究 相似文献
57.
58.
压电双晶片双向大幅振动的探讨 总被引:3,自引:0,他引:3
通过压电陶瓷的逆压电效应对压电陶瓷双晶片在自动生产送料线上的应用研究,得出在二元系Ph(Ni1/3Nb2/3)O3-PhTiO3-PhZrO3的基础上作调整制作的压电双晶片。经运用在振动料斗上,作调频调幅控制。达到了压电双晶片振子结构,振子谐振频率为300Hz,当外加电压达300V时,振子偏转位移量大于1.7mm,故可作为一种理想的振动源。 相似文献
59.
60.
白秧坪铜银多金属矿床主要产于白垩系下统景星组石英砂岩、粉砂岩中,矿石铅同位素组成特征与景星组砂岩的铅同位素组成比较接近,表明壳源物质参与了成矿作用。作ZartMan图解和△γ—△β图解表明,矿石铅属于壳幔混合来源。矿石铅μ值介于9.43—9.65之间,Th/U比值介于3.72—3.87之间,表明矿石铅为壳幔混合铅。该矿床硫同位素组成表明,硫来源于深部地幔硫遭受地壳硫的混入。该矿床的成矿作用发生于开放体系之中,成矿物质来源为深部幔源物质混合了壳源物质。 相似文献