The International Measurement Evaluation Programme (IMEP) is an interlaboratory comparison scheme founded, owned and co-ordinated by the Institute for Reference Materials and Measurements (IRMM) since 1988. IMEP-14, for the first time in the series, is focusing on trace elements in sediment. Reference values for ten elements stating total concentrations and expanded uncertainties according to GUM were established. In total, 239 laboratories from 43 countries in five continents participated in the comparison, and the degree of equivalence between the results from the laboratories and the reference values is presented graphically. Identical samples were distributed to nine National Measurement Institutes within the frame of the CCQM-P15 pilot study. Participation in the IMEP-14 interlaboratory comparison was offered to laboratories in the EU new member states and acceding countries according to the IRMMs Metrology in Chemistry support programme for EU new member states and acceding countries.This revised version was published online in August 2004 with corrections to text especially to the Discussion section. 相似文献
We have discovered a new antiferromagnetic phase in TmNi2B2C by neutron diffraction. The ordering vector is Q(A) = (0.48,0,0) and the phase appears above a critical in-plane magnetic field of 0.9 T. The field was applied in order to test the assumption that the zero-field magnetic structure at Q(F) = (0.094,0.094,0) would change into a c-axis ferromagnet if superconductivity were destroyed. We present theoretical calculations which show that two effects are important: a suppression of the ferromagnetic component of the RKKY exchange interaction in the superconducting phase and a reduction of the superconducting condensation energy due to the periodic modulation of the moments at Q(A). 相似文献
We analyze the source of the self-force errors in the node-centered adaptive-mesh-refinement particle-in-cell (AMR-PIC) algorithm and propose a method for reducing those self-forces. Our approach is based on a method of charge deposition due to Mayo [A. Mayo, The fast solution of Poisson’s and the biharmonic equations on irregular regions, SIAM Journal of Numerical Analysis 21(2) (1984) 285–299] that can reduce the self-force error to any specified degree of accuracy. 相似文献
In the International Measurement Evaluation Programme (IMEP-12) comparison, a synthetically prepared water sample was offered to the analytical laboratories to perform measurements of As, B, Cd, Cr, Cu, Fe, Mg, Mn, Ni and Pb. The choice of elements to be measured was based on EU legislation, which the comparison was aiming to support. As to the IMEP policy, the laboratories’ results were presented according to the certified/assigned reference values established by several reference laboratories all around the world. The performed certification campaign is described in detail in this paper. Isotope dilution mass spectrometry (IDMS) was applied as a primary method of measurement (PMM), whenever possible, to achieve SI-traceable results. Apart from IDMS for reference measurements of some elements, ko-neutron activation analysis (ko-NAA) and external calibration (Ext-Calib) using inductively coupled plasma-mass spectrometry (ICP-MS) were applied. The reference values were characterised as “certified” (for B, Cd, Cr, Cu, Fe, Mg, Ni and Pb) or “assigned” (for As and Mn) according to the IMEP policy. Measurement uncertainty of the certified/assigned reference values was calculated according to the ISO/BIPM guide using the specialised software GUM Workbench.
In the International Measurement Evaluation Programme (IMEP-12) comparison, a synthetically prepared water sample was offered to the analytical laboratories to perform measurements of As, B, Cd, Cr, Cu, Fe, Mg, Mn, Ni and Pb. The choice of elements to be measured was based on EU legislation, which the comparison was aiming to support. As to the IMEP policy, the laboratories’ results were presented according to the certified/assigned reference values established by several reference laboratories all around the world. The performed certification campaign is described in detail in this paper. Isotope dilution mass spectrometry (IDMS) was applied as a primary method of measurement (PMM), whenever possible, to achieve SI-traceable results. Apart from IDMS for reference measurements of some elements, ko-neutron activation analysis (ko-NAA) and external calibration (Ext-Calib) using inductively coupled plasma-mass spectrometry (ICP-MS) were applied. The reference values were characterised as “certified” (for B, Cd, Cr, Cu, Fe, Mg, Ni and Pb) or “assigned” (for As and Mn) according to the IMEP policy. Measurement uncertainty of the certified/assigned reference values was calculated according to the ISO/BIPM guide using the specialised software GUM Workbench. 相似文献